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Sample records for internalization receptor endo180

  1. The collagen receptor uPARAP/Endo180

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  2. Increased expression of the collagen internalization receptor uPARAP/Endo180 in the stroma of head and neck cancer

    DEFF Research Database (Denmark)

    Sulek, Jay; Wagenaar-Miller, Rebecca A; Shireman, Jessica

    2007-01-01

    Local growth, invasion, and metastasis of malignancies of the head and neck involve extensive degradation and remodeling of the underlying, collagen-rich connective tissue. Urokinase plasminogen activator receptor-associated protein (uPARAP)/Endo180 is an endocytic receptor recently shown to play...

  3. The collagen receptor uPARAP/Endo180 in tissue degradation and cancer (Review)

    DEFF Research Database (Denmark)

    Carlsen Melander, Eva Maria; Jürgensen, Henrik J; Madsen, Daniel H

    2015-01-01

    The collagen receptor uPARAP/Endo180, the product of the MRC2 gene, is a central component in the collagen turnover process governed by various mesenchymal cells. Through the endocytosis of collagen or large collagen fragments, this recycling receptor serves to direct basement membrane collagen...... as well as interstitial collagen to lysosomal degradation. This capacity, shared only with the mannose receptor from the same protein family, endows uPARAP/Endo180 with a critical role in development and homeostasis, as well as in pathological disruptions of the extracellular matrix structure. Important...

  4. The urokinase receptor associated protein (uPARAP/endo180)

    DEFF Research Database (Denmark)

    Engelholm, L H; Nielsen, B S; Danø, K

    2001-01-01

    The urokinase-mediated plasminogen activation system plays a central role in the extracellular proteolytic degradation reactions in cancer invasion. In this review article we discuss a number of recent findings identifying a new cellular receptor protein, uPARAP, that interacts with components of...... and their substrate degradation products and thus may add to the complicated interplay between several cell types in governing restricted tissue degradation....

  5. The urokinase plasminogen activator receptor-associated protein/endo180 is coexpressed with its interaction partners urokinase plasminogen activator receptor and matrix metalloprotease-13 during osteogenesis

    DEFF Research Database (Denmark)

    Engelholm, L H; Nielsen, B S; Netzel-Arnett, Sarah

    2001-01-01

    ), and collagen V on the cell surface. We have determined the sites of expression of this novel receptor during murine postimplantation development. uPARAP/Endo180 was expressed in all tissues undergoing primary ossification, including the developing bones of the viscerocranium and calvarium that ossify...... intramembranously, and developing long bones undergoing endochondral ossification. uPARAP/Endo180 mRNA was expressed by both immature osteoblasts and by mature osteocalcin-producing osteoblasts-osteocytes, and was coexpressed with MMP-13. Interestingly, osteoblasts also expressed uPAR. Besides bone-forming tissues...

  6. The collagen receptor uPARAP/Endo180 as a novel target for antibody-drug conjugate mediated treatment of mesenchymal and leukemic cancers

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Fagernæs; van Putten, Sander Maarten; Lund, Ida Katrine

    2017-01-01

    A key task in developing the field of personalized cancer therapy is the identification of novel molecular targets that enable treatment of cancers not susceptible to other means of specific therapy. The collagen receptor uPARAP/Endo180 is overexpressed by malignant cells in several non-epithelia......A key task in developing the field of personalized cancer therapy is the identification of novel molecular targets that enable treatment of cancers not susceptible to other means of specific therapy. The collagen receptor uPARAP/Endo180 is overexpressed by malignant cells in several non...... into the endosomal-lysosomal system, thus opening a potential route of entry into receptor-positive cells. This combination of specific expression and endocytic function appears well suited for targeting of uPARAP/Endo180-positive cancers by antibody-drug conjugate (ADC) mediated drug delivery. Therefore, we...... model with human uPARAP/Endo180-positive leukemic cells, obtaining a complete cure of all tested mice following intravenous ADC treatment with no sign of adverse effects. Our study identifies uPARAP/Endo180 as a promising target for novel therapy against several highly malignant cancer types....

  7. Extracellular collagenases and the endocytic receptor, urokinase plasminogen activator receptor-associated protein/Endo180, cooperate in fibroblast-mediated collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H; Engelholm, Lars H; Ingvarsen, Signe

    2007-01-01

    in these events. A recently discovered turnover route with importance for tumor growth involves intracellular collagen degradation and is governed by the collagen receptor, urokinase plasminogen activator receptor-associated protein (uPARAP or Endo180). The interplay between this mechanism and extracellular...... collagenolysis is not known. In this report, we demonstrate the existence of a new, composite collagen breakdown pathway. Thus, fibroblast-mediated collagen degradation proceeds preferentially as a sequential mechanism in which extracellular collagenolysis is followed by uPARAP/Endo180-mediated endocytosis......The collagens of the extracellular matrix are the most abundant structural proteins in the mammalian body. In tissue remodeling and in the invasive growth of malignant tumors, collagens constitute an important barrier, and consequently, the turnover of collagen is a rate-limiting process...

  8. Targeting a novel bone degradation pathway in primary bone cancer by inactivation of the collagen receptor uPARAP/Endo180

    DEFF Research Database (Denmark)

    Engelholm, Lars H; Carlsen Melander, Eva Maria; Hald, Andreas

    2016-01-01

    metastases of carcinoma origin. This opened the possibility that sarcoma cells might directly mediate bone degeneration. To examine this question, we utilized a syngeneic, osteolytic bone tumour model with transplanted NCTC-2472 sarcoma cells in mice. When analysed in vitro, these cells were capable......In osteosarcoma, a primary mesenchymal bone cancer occurring predominantly in younger patients, invasive tumour growth leads to extensive bone destruction. This process is insufficiently understood, cannot be efficiently counteracted and calls for novel means of treatment. The endocytic collagen...... receptor, uPARAP/Endo180, is expressed on various mesenchymal cell types and is involved in bone matrix turnover during normal bone growth. Human osteosarcoma specimens showed strong expression of this receptor on tumour cells, along with the collagenolytic metalloprotease, MT1-MMP. In advanced tumours...

  9. The urokinase receptor (uPAR) and the uPAR-associated protein (uPARAP/Endo180)

    DEFF Research Database (Denmark)

    Behrendt, Niels

    2004-01-01

    The breakdown of the barriers formed by extracellular matrix proteins is a pre-requisite for all processes of tissue remodeling. Matrix degradation reactions take part in specific physiological events in the healthy organism but also represent a crucial step in cancer invasion. These degradation...... on the surface of various cell types that serves to bind the urokinase plasminogen activator and localize the activation reactions in the proteolytic cascade system of plasminogen activation. uPARAP is an integral membrane protein with a pronounced role in the internalization of collagen for intracellular...... degradation. Both receptors have additional functions that are currently being unraveled. The present discussion of uPAR and uPARAP is centered on their protein structure and molecular and cellular function....

  10. Differential actions of the endocytic collagen receptor uPARAP/Endo180 and the collagenase MMP-2 in bone homeostasis

    DEFF Research Database (Denmark)

    Madsen, Daniel H; Jürgensen, Henrik J; Ingvarsen, Signe

    2013-01-01

    A well-coordinated remodeling of uncalcified collagen matrices is a pre-requisite for bone development and homeostasis. Collagen turnover proceeds through different pathways, either involving extracellular reactions exclusively, or being dependent on endocytic processes. Extracellular collagen...... degradation requires the action of secreted or membrane attached collagenolytic proteases, whereas the alternative collagen degradation pathway proceeds intracellularly after receptor-mediated uptake and delivery to the lysosomes. In this study we have examined the functional interplay between...

  11. uPARAP/endo180 directs lysosomal delivery and degradation of collagen IV

    DEFF Research Database (Denmark)

    Kjøller, Lars; Engelholm, Lars H; Høyer-Hansen, Maria

    2004-01-01

    Collagen turnover is crucial for tissue homeostasis and remodeling and pathological processes such as cancer invasion, but the underlying molecular mechanisms are poorly understood. A major pathway appears to be internalization and degradation by fibroblasts. We now show that the endocytic...... transmembrane glycoprotein urokinase plasminogen activator receptor-associated protein (uPARAP/endo180) directs collagen IV for lysosomal delivery and degradation. In wild-type fibroblasts, fluorescently labeled collagen IV was first internalized into vesicular structures with diffuse fluorescence eventually...... appearing uniformly within the wild-type cells after longer incubation times. In these cells, some collagen-containing vesicles were identified as lysosomes by staining for LAMP-1. In contrast, collagen IV remained extracellular and associated with fiber-like structures on uPARAP/endo180-deficient...

  12. uPARAP/Endo180 is essential for cellular uptake of collagen and promotes fibroblast collagen adhesion

    DEFF Research Database (Denmark)

    Engelholm, Lars H; List, Karin; Netzel-Arnett, Sarah

    2003-01-01

    The uptake and lysosomal degradation of collagen by fibroblasts constitute a major pathway in the turnover of connective tissue. However, the molecular mechanisms governing this pathway are poorly understood. Here, we show that the urokinase plasminogen activator receptor-associated protein (u......, these cells had diminished initial adhesion to a range of different collagens, as well as impaired migration on fibrillar collagen. These studies identify a central function of uPARAP/Endo180 in cellular collagen interactions....

  13. Intracellular collagen degradation mediated by uPARAP/Endo180 is a major pathway of extracellular matrix turnover during malignancy

    DEFF Research Database (Denmark)

    Curino, Alejandro C; Engelholm, Lars H; Yamada, Susan S

    2005-01-01

    We recently reported that uPARAP/Endo180 can mediate the cellular uptake and lysosomal degradation of collagen by cultured fibroblasts. Here, we show that uPARAP/Endo180 has a key role in the degradation of collagen during mammary carcinoma progression. In the normal murine mammary gland, uPARAP/...

  14. uPARAP/endo180 directs lysosomal delivery and degradation of collagen IV

    DEFF Research Database (Denmark)

    Kjøller, Lars; Engelholm, Lars H; Høyer-Hansen, Maria

    2004-01-01

    appearing uniformly within the wild-type cells after longer incubation times. In these cells, some collagen-containing vesicles were identified as lysosomes by staining for LAMP-1. In contrast, collagen IV remained extracellular and associated with fiber-like structures on uPARAP/endo180-deficient...

  15. AGE-modified basement membrane cooperates with Endo180 to promote epithelial cell invasiveness and decrease prostate cancer survival

    DEFF Research Database (Denmark)

    Rodriguez-Teja, Mercedes; Gronau, Julian H; Breit, Claudia

    2015-01-01

    Biomechanical strain imposed by age-related thickening of the basal lamina and augmented tissue stiffness in the prostate gland coincides with increased cancer risk. Here we hypothesized that the structural alterations in the basal lamina associated with age can induce mechanotransduction pathways...... in prostate epithelial cells (PECs) to promote invasiveness and cancer progression. To demonstrate this, we developed a 3D model of PEC acini in which thickening and stiffening of basal lamina matrix was induced by advanced glycation end-product (AGE)-dependent non-enzymatic crosslinking of its major......(Δ) (Ex2-6/) (Δ) (Ex2-6) mice, with constitutively exposed CTLD2 and decreased survival of men with early (non-invasive) prostate cancer with high epithelial Endo180 expression and levels of AGE. These findings indicate that AGE-dependent modification of the basal lamina induces invasive behaviour...

  16. Phagocytosis of Collagen Fibrils by Fibroblasts In Vivo is Independent of the uPARAP/Endo180 Receptor

    DEFF Research Database (Denmark)

    Sprangers, Sara; Behrendt, Niels; Engelholm, Lars

    2017-01-01

    electron microscopy (TEM), we found that fibroblasts in the periosteum of tibia and calvaria, as well as in the periodontal ligament of molar and incisor, phagocytosed collagen fibrils independently of uPARAP. Quantification of phagocytosed collagen in the periodontal ligament of uPARAP-deficient mice...... cleavage products probably occurs through fundamentally different pathways. This article is protected by copyright. All rights reserved....

  17. Complex Determinants in Specific Members of the Mannose Receptor Family Govern Collagen Endocytosis

    DEFF Research Database (Denmark)

    Jürgensen, Henrik J; Johansson, Kristina; Madsen, Daniel H

    2014-01-01

    Members of the well-conserved mannose receptor (MR) protein family have been functionally implicated in diverse biological and pathological processes. Importantly, a proposed common function is the internalization of collagen for intracellular degradation occurring during bone development, cancer...... invasion, and fibrosis protection. This functional relationship is suggested by a common endocytic capability and a candidate collagen-binding domain. Here we conducted a comparative investigation of each member's ability to facilitate intracellular collagen degradation. As expected, the family members u......PARAP/Endo180 and MR bound collagens in a purified system and internalized collagens for degradation in cellular settings. In contrast, the remaining family members, PLA2R and DEC-205, showed no collagen binding activity and were unable to mediate collagen internalization. To pinpoint the structural elements...

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

    Science.gov (United States)

    Calebiro, Davide; Godbole, Amod

    2018-04-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

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

    Science.gov (United States)

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

    2012-07-13

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

  1. Dynamics of Receptor-Mediated Nanoparticle Internalization into Endothelial Cells

    Science.gov (United States)

    Gonzalez-Rodriguez, David; Barakat, Abdul I.

    2015-01-01

    Nanoparticles offer a promising medical tool for targeted drug delivery, for example to treat inflamed endothelial cells during the development of atherosclerosis. To inform the design of such therapeutic strategies, we develop a computational model of nanoparticle internalization into endothelial cells, where internalization is driven by receptor-ligand binding and limited by the deformation of the cell membrane and cytoplasm. We specifically consider the case of nanoparticles targeted against ICAM-1 receptors, of relevance for treating atherosclerosis. The model computes the kinetics of the internalization process, the dynamics of binding, and the distribution of stresses exerted between the nanoparticle and the cell membrane. The model predicts the existence of an optimal nanoparticle size for fastest internalization, consistent with experimental observations, as well as the role of bond characteristics, local cell mechanical properties, and external forces in the nanoparticle internalization process. PMID:25901833

  2. TTP specifically regulates the internalization of the transferrin receptor

    DEFF Research Database (Denmark)

    Tosoni, Daniela; Puri, Claudia; Confalonieri, Stefano

    2005-01-01

    Different plasma membrane receptors are internalized through saturable/noncompetitive pathways, suggesting cargo-specific regulation. Here, we report that TTP (SH3BP4), a SH3-containing protein, specifically regulates the internalization of the transferrin receptor (TfR). TTP interacts...... with endocytic proteins, including clathrin, dynamin, and the TfR, and localizes selectively to TfR-containing coated-pits (CCP) and -vesicles (CCV). Overexpression of TTP specifically inhibits TfR internalization, and causes the formation of morphologically aberrant CCP, which are probably fission impaired....... This effect is mediated by the SH3 of TTP, which can bind to dynamin, and it is rescued by overexpression of dynamin. Functional ablation of TTP causes a reduction in TfR internalization, and reduced cargo loading and size of TfR-CCV. Tyrosine phosphorylation of either TTP or dynamin prevents...

  3. A novel functional role of collagen glycosylation

    DEFF Research Database (Denmark)

    Jürgensen, Henrik J; Madsen, Daniel H; Ingvarsen, Signe

    2011-01-01

    Collagens make up the most abundant component of interstitial extracellular matrices and basement membranes. Collagen remodeling is a crucial process in many normal physiological events and in several pathological conditions. Some collagen subtypes contain specific carbohydrate side chains......, the function of which is poorly known. The endocytic collagen receptor urokinase plasminogen activator receptor-associated protein (uPARAP)/Endo180 plays an important role in matrix remodeling through its ability to internalize collagen for lysosomal degradation. uPARAP/Endo180 is a member of the mannose...... receptor protein family. These proteins all include a fibronectin type II domain and a series of C-type lectin-like domains, of which only a minor part possess carbohydrate recognition activity. At least two of the family members, uPARAP/Endo180 and the mannose receptor, interact with collagens...

  4. Rapid internalization of the insulin receptor in rat hepatoma cells

    International Nuclear Information System (INIS)

    Backer, J.M.; White, M.F.; Kahn, C.R.

    1987-01-01

    The authors have studied the internalization of the insulin receptor (IR) in rat hepatoma cells (Fao). The cells were surface-iodinated at 4 0 C, stimulated with insulin at 37 0 C, and then cooled rapidly, trypsinized at 4 0 C and solubilized. The IR was immunoprecipitated with a specific antibody, and internalization of the IR was assessed by the appearance of trypsin-resistant bands on SDS-PAGE. Insulin induced the internalization of surface receptors with a t 1/2 of 9-10 mins; cells not exposed to insulin internalized less than 20% of the IR during 1 h at 37 0 C. Further experiments demonstrated that the accumulation of trypsin-resistant IR paralleled a loss of receptor from the cell surface. Insulin-stimulated cells were chilled and iodinated at 4 0 C, followed by solubilization, immunoprecipitation and SDS-PAGE; alternatively, insulin-stimulated cells were chilled, surface-bound ligand removed by washing the cells at pH 4.2, and specific [ 125 I]insulin binding measured at 4 0 C. Both techniques confirmed the disappearance of IR from the cell surface at rates comparable to the insulin-stimulated internalization described above. The total amount of phosphotyrosine-containing IR, as assessed by immunoprecipitation with an anti-phosphotyrosine antibody, remained constant during this time interval, suggesting that active kinase is translocated into the cell. In summary, the authors data indicate that insulin binding increases the rate of IR internalization of Fao cells. This relocation may facilitate the interaction of the activated tyrosine kinase in the IR with intracellular substrates, thus transmitting the insulin signal to metabolic pathways

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

    Science.gov (United States)

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

    2015-11-19

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

  6. B cell antigen receptor signaling and internalization are mutually exclusive events.

    Directory of Open Access Journals (Sweden)

    Ping Hou

    2006-07-01

    Full Text Available Engagement of the B cell antigen receptor initiates two concurrent processes, signaling and receptor internalization. While both are required for normal humoral immune responses, the relationship between these two processes is unknown. Herein, we demonstrate that following receptor ligation, a small subpopulation of B cell antigen receptors are inductively phosphorylated and selectively retained at the cell surface where they can serve as scaffolds for the assembly of signaling molecules. In contrast, the larger population of non-phosphorylated receptors is rapidly endocytosed. Each receptor can undergo only one of two mutually exclusive fates because the tyrosine-based motifs that mediate signaling when phosphorylated mediate internalization when not phosphorylated. Mathematical modeling indicates that the observed competition between receptor phosphorylation and internalization enhances signaling responses to low avidity ligands.

  7. Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors.

    Science.gov (United States)

    Koshimizu, Taka-Aki; Kashiwazaki, Aki; Taniguchi, Junichi

    2016-05-03

    Reducing Na(+) in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na(+)-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na(+) sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na(+) increased cell surface [(3)H]AVP binding and decreased receptor internalization. Substitution of Na(+) by Cs(+) or NH4(+) inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na(+) over Cs(+). Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations.

  8. Insulin receptor internalization defect in an insulin-resistant mouse melanoma cell line

    International Nuclear Information System (INIS)

    Androlewicz, M.J.; Straus, D.S.; Brandenburg, D.F.

    1989-01-01

    Previous studies from this laboratory demonstrated that the PG19 mouse melanoma cell line does not exhibit a biological response to insulin, whereas melanoma x mouse embryo fibroblast hybrids do respond to insulin. To investigate the molecular basis of the insulin resistance of the PG19 melanoma cells, insulin receptors from the insulin-resistant melanoma cells and insulin-sensitive fibroblast x melanoma hybrid cells were analyzed by the technique of photoaffinity labeling using the photoprobe 125 I-NAPA-DP-insulin. Photolabeled insulin receptors from the two cell types have identical molecular weights as determined by SDS gel electrophoresis under reducing and nonreducing conditions, indicating that the receptors on the two cell lines are structurally similar. Insulin receptor internalization studies revealed that the hybrid cells internalize receptors to a high degree at 37 degree C, whereas the melanoma cells internalize receptors to a very low degree or not at all. The correlation between ability to internalize insulin receptors and sensitivity to insulin action in this system suggests that uptake of the insulin-receptor complex may be required for insulin action in these cells. Insulin receptors from the two cell lines autophosphorylate in a similar insulin-dependent manner both in vitro and in intact cells, indicating that insulin receptors on the melanoma and hybrid cells have functional tyrosine protein kinase activity. Therefore, the block in insulin action in the PG19 melanoma cells appears to reside at a step beyond insulin-stimulated receptor autophosphorylation

  9. β-arrestins negatively control human adrenomedullin type 1-receptor internalization

    International Nuclear Information System (INIS)

    Kuwasako, Kenji; Kitamura, Kazuo; Nagata, Sayaka; Sekiguchi, Toshio; Danfeng, Jiang; Murakami, Manabu; Hattori, Yuichi; Kato, Johji

    2017-01-01

    Adrenomedullin (AM) is a potent hypotensive peptide that exerts a powerful variety of protective effects against multiorgan damage through the AM type 1 receptor (AM 1 receptor), which consists of the calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 2 (RAMP2). Two β-arrestin (β-arr) isoforms, β-arr-1 and β-arr-2, play a central role in the agonist-induced internalization of many receptors for receptor resensitization. Notably, β-arr-biased agonists are now being tested in phase II clinical trials, targeting acute pain and acute heart failure. Here, we examined the effects of β-arr-1 and β-arr-2 on human AM 1 receptor internalization. We constructed a V5-tagged chimera in which the cytoplasmic C-terminal tail (C-tail) of CLR was replaced with that of the β 2 -adrenergic receptor (β 2 -AR), and it was transiently transfected into HEK-293 cells that stably expressed RAMP2. The cell-surface expression and internalization of the wild-type or chimeric receptor were quantified by flow cytometric analysis. The [ 125 I]AM binding and the AM-induced cAMP production of these receptors were also determined. Surprisingly, the coexpression of β-arr-1 or -2 resulted in significant decreases in AM 1 receptor internalization without affecting AM binding and signaling prior to receptor internalization. Dominant-negative (DN) β-arr-1 or -2 also significantly decreased AM-induced AM 1 receptor internalization. In contrast, the AM-induced internalization of the chimeric AM 1 receptor was markedly augmented by the cotransfection of β-arr-1 or -2 and significantly reduced by the coexpression of DN-β-arr-1 or -2. These results were consistent with those seen for β 2 -AR. Thus, both β-arrs negatively control AM 1 receptor internalization, which depends on the C-tail of CLR. - Highlights: • We found that β-arrestins 1 and 2 negatively control agonist-induced GPCR internalization. • β-arrestins 1 and 2 significantly inhibits the AM

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  11. Opiates Modulate Thermosensation by Internalizing Cold Receptor TRPM8

    Directory of Open Access Journals (Sweden)

    George Shapovalov

    2013-08-01

    Full Text Available Stimulation of μ-opioid receptors (OPRMs brings powerful pain relief, but it also leads to the development of tolerance and addiction. Ensuing withdrawal in abstinent patients manifests itself with severe symptoms, including cold hyperalgesia, often preventing addicted patients from successfully completing the rehabilitation. Unsurprisingly, OPRMs have been a central point of many studies. Nonetheless, a satisfactory understanding of the pathways leading to distorted sensory responses during opiate administration and abstinence is far from complete. Here, we present a mechanism that leads to modulation by OPRMs of one of the sensory responses, thermosensation. Activation of OPRM1 leads to internalization of a cold-sensor TRPM8, which can be reversed by a follow-up treatment with the inverse OPRM agonist naloxone. Knockout of TRPM8 protein leads to a decrease in morphine-induced cold analgesia. The proposed pathway represents a universal mechanism that is probably shared by regulatory pathways modulating general pain sensation in response to opioid treatment.

  12. Clathrin-dependent internalization of the angiotensin II AT₁A receptor links receptor internalization to COX-2 protein expression in rat aortic vascular smooth muscle cells.

    Science.gov (United States)

    Morinelli, Thomas A; Walker, Linda P; Velez, Juan Carlos Q; Ullian, Michael E

    2015-02-05

    The major effects of Angiotensin II (AngII) in vascular tissue are mediated by AngII AT1A receptor activation. Certain effects initiated by AT1A receptor activation require receptor internalization. In rat aortic vascular smooth muscle cells (RASMC), AngII stimulates cyclooxygenase 2 protein expression. We have previously shown this is mediated by β-arrestin-dependent receptor internalization and NF-κB activation. In this study, a specific inhibitor of clathrin-mediated endocytosis (CME), pitstop-2, was used to test the hypothesis that clathrin-dependent internalization of activated AT1A receptor mediates NF-κB activation and subsequent cyclooxygenase 2 expression. Radioligand binding assays, real time qt-PCR and immunoblotting were used to document the effects of pitstop-2 on AngII binding and signaling in RASMC. Laser scanning confocal microscopy (LSCM) was used to image pitstop-2׳s effects on AT1 receptor/GFP internalization in HEK-293 cells and p65 NF-κB nuclear localization in RASMC. Pitstop-2 significantly inhibited internalization of AT1A receptor (44.7% ± 3.1% Control vs. 13.2% ± 8.3% Pitstop-2; n=3) as determined by radioligand binding studies in RASMC. Studies utilizing AT1A receptor/GFP expressed in HEK 293 cells and LSCM confirmed these findings. Pitstop-2 significantly inhibited AngII-induced p65 NF-κB phosphorylation and nuclear localization, COX-2 message and protein expression in RASMC without altering activation of p42/44 ERK or TNFα signaling. Pitstop-2, a specific inhibitor of clathrin-mediated endocytosis, confirms that internalization of activated AT1A receptor mediates AngII activation of cyclooxygenase 2 expression in RASMC. These data provide support for additional intracellular signaling pathways activated through β-arrestin mediated internalization of G protein-coupled receptors, such as AT1A receptors. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. β-arrestins negatively control human adrenomedullin type 1-receptor internalization.

    Science.gov (United States)

    Kuwasako, Kenji; Kitamura, Kazuo; Nagata, Sayaka; Sekiguchi, Toshio; Danfeng, Jiang; Murakami, Manabu; Hattori, Yuichi; Kato, Johji

    2017-05-27

    Adrenomedullin (AM) is a potent hypotensive peptide that exerts a powerful variety of protective effects against multiorgan damage through the AM type 1 receptor (AM 1 receptor), which consists of the calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 2 (RAMP2). Two β-arrestin (β-arr) isoforms, β-arr-1 and β-arr-2, play a central role in the agonist-induced internalization of many receptors for receptor resensitization. Notably, β-arr-biased agonists are now being tested in phase II clinical trials, targeting acute pain and acute heart failure. Here, we examined the effects of β-arr-1 and β-arr-2 on human AM 1 receptor internalization. We constructed a V5-tagged chimera in which the cytoplasmic C-terminal tail (C-tail) of CLR was replaced with that of the β 2 -adrenergic receptor (β 2 -AR), and it was transiently transfected into HEK-293 cells that stably expressed RAMP2. The cell-surface expression and internalization of the wild-type or chimeric receptor were quantified by flow cytometric analysis. The [ 125 I]AM binding and the AM-induced cAMP production of these receptors were also determined. Surprisingly, the coexpression of β-arr-1 or -2 resulted in significant decreases in AM 1 receptor internalization without affecting AM binding and signaling prior to receptor internalization. Dominant-negative (DN) β-arr-1 or -2 also significantly decreased AM-induced AM 1 receptor internalization. In contrast, the AM-induced internalization of the chimeric AM 1 receptor was markedly augmented by the cotransfection of β-arr-1 or -2 and significantly reduced by the coexpression of DN-β-arr-1 or -2. These results were consistent with those seen for β 2 -AR. Thus, both β-arrs negatively control AM 1 receptor internalization, which depends on the C-tail of CLR. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Molecular characterization of the di-leucine-based internalization motif of the T cell receptor

    DEFF Research Database (Denmark)

    Dietrich, J; Hou, X; Wegener, A M

    1996-01-01

    Several cell surface receptors including the T cell receptor (TCR) are phosphorylated and down-regulated following activation of protein kinases. We have recently shown that both phosphorylation of Ser-126 and the presence of the di-leucine sequence Leu-131 and Leu-132 in CD3 gamma are required f...... are important. 2) Recognition of phosphorylated CD3 gamma by molecules involved in receptor internalization. In this process Ser(P)-126, Asp-127, Leu-131, and Leu-132 are important....

  15. Receptor-mediated internalization of [3H]-neurotensin in synaptosomal preparations from rat neostriatum.

    Science.gov (United States)

    Nguyen, Ha Minh Ky; Cahill, Catherine M; McPherson, Peter S; Beaudet, Alain

    2002-06-01

    Following its binding to somatodendritic receptors, the neuropeptide neurotensin (NT) internalizes via a clathrin-mediated process. In the present study, we investigated whether NT also internalizes presynaptically using synaptosomes from rat neostriatum, a region in which NT1 receptors are virtually all presynaptic. Binding of [(3)H]-NT to striatal synaptosomes in the presence of levocabastine to block NT2 receptors is specific, saturable, and has NT1 binding properties. A significant fraction of the bound radioactivity is resistant to hypertonic acid wash indicating that it is internalized. Internalization of [(3)H]-NT, like that of [(125)I]-transferrin, is blocked by sucrose and low temperature, consistent with endocytosis occurring via a clathrin-dependent pathway. However, contrary to what was reported at the somatodendritic level, neither [(3)H]-NT nor [(125)I]-transferrin internalization in synaptosomes is sensitive to the endocytosis inhibitor phenylarsine oxide. Moreover, treatment of synaptosomes with monensin, which prevents internalized receptors from recycling to the plasma membrane, reduces [(3)H]-NT binding and internalization, suggesting that presynaptic NT1 receptors, in contrast to somatodendritic ones, are recycled back to the plasma membrane. Taken together, these results suggest that NT internalizes in nerve terminals via an endocytic pathway that is related to, but is mechanistically distinct from that responsible for NT internalization in nerve cell bodies.

  16. Receptor activation and 2 distinct COOH-terminal motifs control G-CSF receptor distribution and internalization kinetics

    NARCIS (Netherlands)

    L.H.J. Aarts (Bart); O. Roovers (Onno); A.C. Ward (Alister); I.P. Touw (Ivo)

    2004-01-01

    textabstractWe have studied the intracellular distribution and internalization kinetics of the granulocyte colony-stimulating factor receptor (G-CSF-R) in living cells using fusion constructs of wild-type or mutant G-CSF-R and enhanced green fluorescent protein (EGFP). Under

  17. Internalization mechanisms of the epidermal growth factor receptor after activation with different ligands.

    Directory of Open Access Journals (Sweden)

    Lasse Henriksen

    Full Text Available The epidermal growth factor receptor (EGFR regulates normal growth and differentiation, but dysregulation of the receptor or one of the EGFR ligands is involved in the pathogenesis of many cancers. There are eight ligands for EGFR, however most of the research into trafficking of the receptor after ligand activation focuses on the effect of epidermal growth factor (EGF and transforming growth factor-α (TGF-α. For a long time it was believed that clathrin-mediated endocytosis was the major pathway for internalization of the receptor, but recent work suggests that different pathways exist. Here we show that clathrin ablation completely inhibits internalization of EGF- and TGF-α-stimulated receptor, however the inhibition of receptor internalization in cells treated with heparin-binding EGF-like growth factor (HB-EGF or betacellulin (BTC was only partial. In contrast, clathrin knockdown fully inhibits EGFR degradation after all ligands tested. Furthermore, inhibition of dynamin function blocked EGFR internalization after stimulation with all ligands. Knocking out a number of clathrin-independent dynamin-dependent pathways of internalization had no effect on the ligand-induced endocytosis of the EGFR. We suggest that EGF and TGF-α lead to EGFR endocytosis mainly via the clathrin-mediated pathway. Furthermore, we suggest that HB-EGF and BTC also lead to EGFR endocytosis via a clathrin-mediated pathway, but can additionally use an unidentified internalization pathway or better recruit the small amount of clathrin remaining after clathrin knockdown.

  18. Internalization Mechanisms of the Epidermal Growth Factor Receptor after Activation with Different Ligands

    Science.gov (United States)

    Henriksen, Lasse; Grandal, Michael Vibo; Knudsen, Stine Louise Jeppe; van Deurs, Bo; Grøvdal, Lene Melsæther

    2013-01-01

    The epidermal growth factor receptor (EGFR) regulates normal growth and differentiation, but dysregulation of the receptor or one of the EGFR ligands is involved in the pathogenesis of many cancers. There are eight ligands for EGFR, however most of the research into trafficking of the receptor after ligand activation focuses on the effect of epidermal growth factor (EGF) and transforming growth factor-α (TGF-α). For a long time it was believed that clathrin-mediated endocytosis was the major pathway for internalization of the receptor, but recent work suggests that different pathways exist. Here we show that clathrin ablation completely inhibits internalization of EGF- and TGF-α-stimulated receptor, however the inhibition of receptor internalization in cells treated with heparin-binding EGF-like growth factor (HB-EGF) or betacellulin (BTC) was only partial. In contrast, clathrin knockdown fully inhibits EGFR degradation after all ligands tested. Furthermore, inhibition of dynamin function blocked EGFR internalization after stimulation with all ligands. Knocking out a number of clathrin-independent dynamin-dependent pathways of internalization had no effect on the ligand-induced endocytosis of the EGFR. We suggest that EGF and TGF-α lead to EGFR endocytosis mainly via the clathrin-mediated pathway. Furthermore, we suggest that HB-EGF and BTC also lead to EGFR endocytosis via a clathrin-mediated pathway, but can additionally use an unidentified internalization pathway or better recruit the small amount of clathrin remaining after clathrin knockdown. PMID:23472148

  19. Internalization mechanisms of the epidermal growth factor receptor after activation with different ligands

    DEFF Research Database (Denmark)

    Henriksen, Lasse; Grandal, Michael Vibo; Knudsen, Stine Louise Jeppe

    2013-01-01

    after ligand activation focuses on the effect of epidermal growth factor (EGF) and transforming growth factor-α (TGF-α). For a long time it was believed that clathrin-mediated endocytosis was the major pathway for internalization of the receptor, but recent work suggests that different pathways exist....... Here we show that clathrin ablation completely inhibits internalization of EGF- and TGF-α-stimulated receptor, however the inhibition of receptor internalization in cells treated with heparin-binding EGF-like growth factor (HB-EGF) or betacellulin (BTC) was only partial. In contrast, clathrin knockdown...... fully inhibits EGFR degradation after all ligands tested. Furthermore, inhibition of dynamin function blocked EGFR internalization after stimulation with all ligands. Knocking out a number of clathrin-independent dynamin-dependent pathways of internalization had no effect on the ligand...

  20. The GPRC6A Receptor displays Constitutive Internalization and Sorting to the Slow Recycling Pathway

    DEFF Research Database (Denmark)

    Jacobsen, Stine Engesgaard; Ammendrup-Johnsen, Ina; Jansen, Anna Mai

    2017-01-01

    The class C G protein-coupled receptor GPRC6A is a putative nutrient sensing receptor and represents a possible new drug target in metabolic disorders. However, the specific physiological role of this receptor has yet to be identified, and the mechanisms regulating its activity and cell surface...... availability also remain enigmatic. In the present study, we investigated the trafficking properties of GPRC6A by use of both a classical antibody feeding internalization assay in which cells were visualized using confocal microscopy and a novel internalization assay that is based on real-time measurements...... slow recycling pathway, which may be responsible for ensuring a persistent pool of GPRC6A receptors at the cell surface despite chronic agonist exposure. Distinct trafficking pathways have been reported for several of the class C receptors, and our results thus substantiate that non...

  1. The mechanisms behind decreased internalization of angiotensin II type 1 receptor.

    Science.gov (United States)

    Bian, Jingwei; Zhang, Suli; Yi, Ming; Yue, Mingming; Liu, Huirong

    2018-04-01

    The internalization of angiotensin II type 1 receptor (AT 1 R) plays an important role in maintaining cardiovascular homeostasis. Decreased receptor internalization is closely related to cardiovascular diseases induced by the abnormal activation of AT 1 R, such as hypertension. However, the mechanism behind reduced AT 1 R internalization is not fully understood. This review focuses on four parts of the receptor internalization process (the combination of agonists and receptors, receptor phosphorylation, endocytosis, and recycling) and summarizes the possible mechanisms by which AT 1 R internalization is reduced based on these four parts of the process. (1) The agonist has a large molecular weight or a stronger ability to hydrolyze phosphatidylinositol 4,5-bisphosphate (PtdIns (4,5) P 2 ), which can increase the consumption of PtdIns (4,5) P 2 . (2) AT 1 R phosphorylation is weakened because of an abnormal function of phosphorylated kinase or changes in phospho-barcoding and GPCR-β-arrestin complex conformation. (3) The abnormal formation of vesicles or AT 1 R heterodimers with fewer endocytic receptors results in less AT 1 R endocytosis. (4) The enhanced activity and upregulated expression of small GTP-binding protein 4 (Rab4) and 11 (Rab11), which regulate receptor recycling, and phosphatidylinositol 3-kinase increase AT 1 R recycling. In addition, lower expression of AT 1 R-associated protein (ATRAP) or higher expression of AT 1 R-associated protein 1 (ARAP1) can reduce receptor internalization. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. γ-Aminobutyric Acid Type B (GABAB) Receptor Internalization Is Regulated by the R2 Subunit*

    Science.gov (United States)

    Hannan, Saad; Wilkins, Megan E.; Dehghani-Tafti, Ebrahim; Thomas, Philip; Baddeley, Stuart M.; Smart, Trevor G.

    2011-01-01

    γ-Aminobutyric acid type B (GABAB) receptors are important for slow synaptic inhibition in the CNS. The efficacy of inhibition is directly related to the stability of cell surface receptors. For GABAB receptors, heterodimerization between R1 and R2 subunits is critical for cell surface expression and signaling, but how this determines the rate and extent of receptor internalization is unknown. Here, we insert a high affinity α-bungarotoxin binding site into the N terminus of the R2 subunit and reveal its dominant role in regulating the internalization of GABAB receptors in live cells. To simultaneously study R1a and R2 trafficking, a new α-bungarotoxin binding site-labeling technique was used, allowing α-bungarotoxin conjugated to different fluorophores to selectively label R1a and R2 subunits. This approach demonstrated that R1a and R2 are internalized as dimers. In heterologous expression systems and neurons, the rates and extents of internalization for R1aR2 heteromers and R2 homomers are similar, suggesting a regulatory role for R2 in determining cell surface receptor stability. The fast internalization rate of R1a, which has been engineered to exit the endoplasmic reticulum, was slowed to that of R2 by truncating the R1a C-terminal tail or by removing a dileucine motif in its coiled-coil domain. Slowing the rate of internalization by co-assembly with R2 represents a novel role for GPCR heterodimerization whereby R2 subunits, via their C terminus coiled-coil domain, mask a dileucine motif on R1a subunits to determine the surface stability of the GABAB receptor. PMID:21724853

  3. Inhibition of TRAIL-induced apoptosis and forced internalization of TRAIL receptor 1 by adenovirus proteins.

    Science.gov (United States)

    Tollefson, A E; Toth, K; Doronin, K; Kuppuswamy, M; Doronina, O A; Lichtenstein, D L; Hermiston, T W; Smith, C A; Wold, W S

    2001-10-01

    Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces apoptosis through two receptors, TRAIL-R1 (also known as death receptor 4) and TRAIL-R2 (also known as death receptor 5), that are members of the TNF receptor superfamily of death domain-containing receptors. We show that human adenovirus type 5 encodes three proteins, named RID (previously named E3-10.4K/14.5K), E3-14.7K, and E1B-19K, that independently inhibit TRAIL-induced apoptosis of infected human cells. This conclusion was derived from studies using wild-type adenovirus, adenovirus replication-competent mutants that lack one or more of the RID, E3-14.7K, and E1B-19K genes, and adenovirus E1-minus replication-defective vectors that express all E3 genes, RID plus E3-14.7K only, RID only, or E3-14.7K only. RID inhibits TRAIL-induced apoptosis when cells are sensitized to TRAIL either by adenovirus infection or treatment with cycloheximide. RID induces the internalization of TRAIL-R1 from the cell surface, as shown by flow cytometry and indirect immunofluorescence for TRAIL-R1. TRAIL-R1 was internalized in distinct vesicles which are very likely to be endosomes and lysosomes. TRAIL-R1 is degraded, as indicated by the disappearance of the TRAIL-R1 immunofluorescence signal. Degradation was inhibited by bafilomycin A1, a drug that prevents acidification of vesicles and the sorting of receptors from late endosomes to lysosomes, implying that degradation occurs in lysosomes. RID was also shown previously to internalize and degrade another death domain receptor, Fas, and to prevent apoptosis through Fas and the TNF receptor. RID was shown previously to force the internalization and degradation of the epidermal growth factor receptor. E1B-19K was shown previously to block apoptosis through Fas, and both E1B-19K and E3-14.7K were found to prevent apoptosis through the TNF receptor. These findings suggest that the receptors for TRAIL, Fas ligand, and TNF play a role in limiting virus

  4. Microplate-compatible total internal reflection fluorescence microscopy for receptor pharmacology

    Science.gov (United States)

    Chen, Minghan; Zaytseva, Natalya V.; Wu, Qi; Li, Min; Fang, Ye

    2013-05-01

    We report the use of total internal reflection fluorescence (TIRF) microscopy for analyzing receptor pharmacology and the development of a microplate-compatible TIRF imaging system. Using stably expressed green fluorescence protein tagged β2-adrenergic receptor as the reporter, we found that the activation of different receptors results in distinct kinetic signatures of the TIRF intensity of cells. These TIRF signatures closely resemble the characteristics of their respective label-free dynamic mass redistribution signals in the same cells. This suggests that TIRF in microplate can be used for profiling and screening drugs.

  5. Internalization and recycling of receptor-bound gonadotropin-releasing hormone agonist in pituitary gonadotropes

    International Nuclear Information System (INIS)

    Schvartz, I.; Hazum, E.

    1987-01-01

    The fate of cell surface gonadotropin-releasing hormone (GnRH) receptors on pituitary cells was studied utilizing lysosomotropic agents and monensin. Labeling of pituitary cells with a photoreactive GnRH derivative, [azidobenzoyl-D-Lys6]GnRH, revealed a specific band of Mr = 60,000. When photoaffinity-labeled cells were exposed to trypsin immediately after completion of the binding, the radioactivity incorporated into the Mr = 60,000 band decreased, with a concomitant appearance of a proteolytic fragment (Mr = 45,000). This fragment reflects cell surface receptors. Following GnRH binding, the hormone-receptor complexes underwent internalization, partial degradation, and recycling. The process of hormone-receptor complex degradation was substantially prevented by lysosomotropic agents, such as chloroquine and methylamine, or the proton ionophore, monensin. Chloroquine and monensin, however, did not affect receptor recycling, since the tryptic fragment of Mr = 45,000 was evident after treatment with these agents. This suggests that recycling of GnRH receptors in gonadotropes occurs whether or not the internal environment is acidic. Based on these findings, we propose a model describing the intracellular pathway of GnRH receptors

  6. Rate of Homologous Desensitization and Internalization of the GLP-1 Receptor.

    Science.gov (United States)

    Shaaban, Ghina; Oriowo, Mabayoje; Al-Sabah, Suleiman

    2016-12-26

    The glucagon-like peptide-1 receptor (GLP-1R) is an important target in the treatment of type 2 diabetes mellitus. The aim of this study was to compare the rate of agonist stimulated desensitization and internalization of GLP-1R. To this end, an N-terminally myc-tagged GLP-1R was stably expressed in HEK-293 cells. Homologous desensitization was assessed by measuring the cAMP response to agonist stimulation following pre-incubation with agonist for up to 120 min. Receptor internalization was monitored using an indirect ELISA-based method and confocal microscopy. Pre-incubation with GLP-1 resulted in a time-dependent loss of response to a second stimulation. Washing cells following pre-incubation failed to bring cAMP levels back to basal. Taking this into account, two desensitization rates were calculated: "apparent" (t 1/2 = 19.27 min) and "net" (t 1/2 = 2.99 min). Incubation of cells with GLP-1 also resulted in a time-dependent loss of receptor cell surface expression (t 1/2 = 2.05 min). Rapid agonist-stimulated internalization of GLP-1R was confirmed using confocal microscopy. Stimulation of GLP-1R with GLP-1 results in rapid desensitization and internalization of the receptor. Interestingly, the rate of "net" desensitization closely matches the rate of internalization. Our results suggest that agonist-bound GLP-1R continues to generate cAMP after it has been internalized.

  7. Chemerin C9 peptide induces receptor internalization through a clathrin-independent pathway

    Science.gov (United States)

    Zhou, Jun-xian; Liao, Dan; Zhang, Shuo; Cheng, Ni; He, Hui-qiong; Ye, Richard D

    2014-01-01

    Aim: The chemerin receptor CMKLR1 is one type of G protein-coupled receptors abundant in monocyte-derived dendritic cells and macrophages, which plays a key role in the entry of a subset of immunodeficiency viruses including HIV/SIV into lymphocytes and macrophages. The aim of this work was to investigate how CMKLR1 was internalized and whether its internalization affected cell signaling in vitro. Methods: Rat basophilic leukemia RBL-2H3 cells, HEK 293 cells, and HeLa cells were used. CMKLR1 internalization was visualized by confocal microscopy imaging or using a FACScan flow cytometer. Six potential phosphorylation sites (Ser337, Ser343, Thr352, Ser344, Ser347, and Ser350) in CMKLR1 were substituted with alanine using site-directed mutagenesis. Heterologous expression of wild type and mutant CMKLR1 allowed for functional characterization of endocytosis, Ca2+ flux and extracellular signal-regulated kinase (ERK) phosphorylation. Results: Chemerin and the chemerin-derived nonapeptide (C9) induced dose-dependent loss of cell surface CMKLR1-GFP fusion protein and increased its intracellular accumulation in HEK 293 cells and RBL-2H3 cells stably expressing CMKLR1. Up to 90% of CMKLR1 was internalized after treatment with C9 (1 μmol/L). By using different agents, it was demonstrated that clathrin-independent mechanism was involved in CMKLR1 internalization. Mutations in Ser343 for G protein-coupled receptor kinase phosphorylation and in Ser347 for PKC phosphorylation abrogated CMKLR1 internalization. Loss of CMKLR1 internalization partially enhanced the receptor signaling, as shown by increased Ca2+ flux and a shorter latency to peak level of ERK phosphorylation. Conclusion: CMKLR1 internalization occurs in a clathrin-independent manner, which negatively regulated the receptor-mediated Ca2+ flux and ERK phosphorylation. PMID:24658352

  8. Pancreatic acini possess endothelin receptors whose internalization is regulated by PLC-activating agents.

    Science.gov (United States)

    Hildebrand, P; Mrozinski, J E; Mantey, S A; Patto, R J; Jensen, R T

    1993-05-01

    Endothelin-1 (ET-1) and ET-3 mRNA have been found in the pancreas. We investigated the ability of ET-1, ET-2, and ET-3 to interact with and alter dispersed rat pancreatic acinar cell function. Radiolabeled ETs bound in a time- and temperature-dependent fashion, which was specific and saturable. Analysis demonstrated two classes of receptors, one class (ETA receptor) had a high affinity for ET-1 but a low affinity for ET-3, and the other class (ETB receptor) had equally high affinities for ET-1 and ET-3. No specific receptor for ET-2 was identified. Pancreatic secretagogues that activate phospholipase C (PLC) inhibited binding of 125I-labeled ET-1 (125I-ET-1) or 125I-ET-3, whereas agents that act through adenosine 3',5'-cyclic monophosphate (cAMP) did not. A23187 had no effect on 125I-ET-1 or 125I-ET-3 binding, whereas the phorbol ester 12-O-tetradecanoylphorbol 13-acetate reduced binding. The effect of cholecystokinin octapeptide (CCK-8) was mediated through its own receptor. Stripping of surface bound ligand studies demonstrated that both 125I-labeled ET-1 and 125I-labeled ET-3 were rapidly internalized. CCK-8 decreased the internalization but did not change the amount of surface bound ligand. Endothelins neither stimulate nor alter changes in enzyme secretion, intracellular calcium, cAMP, or [3H]inositol trisphosphate (IP3). This study demonstrates the presence of ETA and ETB receptors on rat pancreatic acini; occupation of both receptors resulted in rapid internalization, which is regulated by PLC-activating secretagogues. Occupation of either ET receptor did not alter intracellular calcium, cAMP, IP3, or stimulate amylase release.

  9. Solar advanced internal film receiver; Receptor avanzado de pelicular interna

    Energy Technology Data Exchange (ETDEWEB)

    Torre Cabezas, M. de la

    1990-07-01

    In a Solar Central Internal Film Receiver, the heat absorbing fluid (a molten nitrate salt) flows in a thin film down over the non illuminated side of an absorber panel. Since the molten salt working fluid is not contained in complicated tube manifolds, the receiver design is simples than a conventional tube type-receiver resulting in a lower cost and a more reliable receiver. The Internal Film Receiver can be considered as an alternative to the Direct Absorption Receiver, in the event that the current problems of the last one can not be solved. It also describes here the test facility which will be used for its solar test, and the test plans foreseen. (Author) 17 refs.

  10. The non-phagocytic route of collagen uptake

    DEFF Research Database (Denmark)

    Madsen, Daniel H; Ingvarsen, Signe; Jürgensen, Henrik J

    2011-01-01

    The degradation of collagens, the most abundant proteins of the extracellular matrix, is involved in numerous physiological and pathological conditions including cancer invasion. An important turnover pathway involves cellular internalization and degradation of large, soluble collagen fragments......, generated by initial cleavage of the insoluble collagen fibers. We have previously observed that in primary mouse fibroblasts, this endocytosis of collagen fragments is dependent on the receptor urokinase plasminogen activator receptor-associated protein (uPARAP)/Endo180. Others have identified additional...... mechanisms of collagen uptake, with different associated receptors, in other cell types. These receptors include β1-integrins, being responsible for collagen phagocytosis, and the mannose receptor. We have now utilized a newly developed monoclonal antibody against uPARAP/Endo180, which down...

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

    Directory of Open Access Journals (Sweden)

    Rocío Alcántara-Hernández

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

  12. Collagen Type I as a Ligand for Receptor-Mediated Signaling

    Directory of Open Access Journals (Sweden)

    Iris Boraschi-Diaz

    2017-05-01

    Full Text Available Collagens form the fibrous component of the extracellular matrix in all multi-cellular animals. Collagen type I is the most abundant collagen present in skin, tendons, vasculature, as well as the organic portion of the calcified tissue of bone and teeth. This review focuses on numerous receptors for which collagen acts as a ligand, including integrins, discoidin domain receptors DDR1 and 2, OSCAR, GPVI, G6b-B, and LAIR-1 of the leukocyte receptor complex (LRC and mannose family receptor uPARAP/Endo180. We explore the process of collagen production and self-assembly, as well as its degradation by collagenases and gelatinases in order to predict potential temporal and spatial sites of action of different collagen receptors. While the interactions of the mature collagen matrix with integrins and DDR are well-appreciated, potential signals from immature matrix as well as collagen degradation products are possible but not yet described. The role of multiple collagen receptors in physiological processes and their contribution to pathophysiology of diseases affecting collagen homeostasis require further studies.

  13. Carboxyl-terminal multi-site phosphorylation regulates internalization and desensitization of the human sst2 somatostatin receptor.

    Science.gov (United States)

    Lehmann, Andreas; Kliewer, Andrea; Schütz, Dagmar; Nagel, Falko; Stumm, Ralf; Schulz, Stefan

    2014-04-25

    The somatostatin receptor 2 (sst2) is the pharmacological target of somatostatin analogs that are widely used in the diagnosis and treatment of human neuroendocrine tumors. We have recently shown that the stable somatostatin analogs octreotide and pasireotide (SOM230) stimulate distinct patterns of sst2 receptor phosphorylation and internalization. Like somatostatin, octreotide promotes the phosphorylation of at least six carboxyl-terminal serine and threonine residues namely S341, S343, T353, T354, T356 and T359, which in turn leads to a robust receptor endocytosis. Unlike somatostatin, pasireotide stimulates a selective phosphorylation of S341 and S343 of the human sst2 receptor followed by a partial receptor internalization. Here, we show that exchange of S341 and S343 by alanine is sufficient to block pasireotide-driven internalization, whereas mutation of T353, T354, T356 and T359 to alanine is required to strongly inhibited both octreotide- and somatostatin-induced internalization. Yet, combined mutation of T353, T354, T356 and T359 is not sufficient to prevent somatostatin-driven β-arrestin mobilization and receptor desensitization. Replacement of all fourteen carboxyl-terminal serine and threonine residues by alanine completely abrogates sst2 receptor internalization and β-arrestin mobilization in HEK293 cells. Together, our findings demonstrate for the first time that agonist-selective sst2 receptor internalization is regulated by multi-site phosphorylation of its carboxyl-terminal tail. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. Quantitative measurement of cell membrane receptor internalization by the nanoluciferase reporter: Using the G protein-coupled receptor RXFP3 as a model.

    Science.gov (United States)

    Liu, Yu; Song, Ge; Shao, Xiao-Xia; Liu, Ya-Li; Guo, Zhan-Yun

    2015-02-01

    Nanoluciferase (NanoLuc) is a newly developed small luciferase reporter with the brightest bioluminescence to date. In the present work, we developed NanoLuc as a sensitive bioluminescent reporter to measure quantitatively the internalization of cell membrane receptors, based on the pH dependence of the reporter activity. The G protein-coupled receptor RXFP3, the cognate receptor of relaxin-3/INSL7, was used as a model receptor. We first generated stable HEK293T cells that inducibly coexpressed a C-terminally NanoLuc-tagged human RXFP3 and a C-terminally enhanced green fluorescent protein (EGFP)-tagged human RXFP3. The C-terminal EGFP-tag and NanoLuc-tag had no detrimental effects on the ligand-binding potency and intracellular trafficking of RXFP3. Based on the fluorescence of the tagged EGFP reporter, the ligand-induced RXFP3 internalization was visualized directly under a fluorescence microscope. Based on the bioluminescence of the tagged NanoLuc reporter, the ligand-induced RXFP3 internalization was measured quantitatively by a convenient bioluminescent assay. Coexpression of an EGFP-tagged inactive [E141R]RXFP3 had no detrimental effect on the ligand-binding potency and ligand-induced internalization of the NanoLuc-tagged wild-type RXFP3, suggesting that the mutant RXFP3 and wild-type RXFP3 worked independently. The present bioluminescent internalization assay could be extended to other G protein-coupled receptors and other cell membrane receptors to study ligand-receptor and receptor-receptor interactions. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Dopamine receptor D4 internalization requires a beta-arrestin and a visual arrestin.

    Science.gov (United States)

    Deming, Janise D; Shin, Jung-A; Lim, Kayleen; Lee, Eun-Jin; Van Craenenbroeck, Kathleen; Craft, Cheryl Mae

    2015-10-01

    The G-protein coupled receptor (GPCR) Dopamine Receptor D4 (DRD4) plays an essential role in cAMP regulation and gap junctional coupling in the photoreceptors, where DRD4 expression is under circadian control. Previous in vitro transfection studies of human DRD4 desensitization have reported that DRD4 is not internalized upon dopamine stimulation when beta-arrestin is co-transfected with DRD4. We hypothesized that the visual arrestins, ARR1 and ARR4, play a modulatory role in DRD4 desensitization in the photoreceptors. To test this hypothesis, immunohistochemistry analysis of mouse retinas was used to determine the cellular localization of beta-arrestins and DRD4 in photoreceptors. In vitro studies were performed in HEK293T cells transiently transfected with human DRD4 and arrestins. First, co-immunoprecipitation experiments were executed to test protein-protein interactions and to investigate the effect of dopamine stimulation. Second, immunohistochemistry analysis was implemented to study DRD4 internalization and translocation of ARR4. Immunohistochemistry studies of mouse retinas confirmed the expression of beta-arrestin 2, ARR1 and ARR4, as well as DRD4 in mouse cone photoreceptor inner segments. Co-immunoprecipitation experiments revealed a dopamine-dependent protein-protein interaction between human DRD4 and ARR4. In vitro internalization experiments showed that no detectable internalization of DRD4 was observed with any single arrestin co-transfected. However, a dopamine-dependent internalization of DRD4 was observed with three out of six sets of two arrestins co-transfected with DRD4. Each of these pairs of arrestins contained one visual arrestin and one beta-arrestin, and no internalization was observed with either two visual arrestins or two beta-arrestins. Additional time-course experiments revealed that in vitro, ARR4 translocates to co-localize with DRD4 at the plasma membrane in response to 30min of dopamine stimulation. The results have functional

  16. International Union of Pharmacology. XXXII. The mammalian calcitonin gene-related peptides, adrenomedullin, amylin, and calcitonin receptors.

    Science.gov (United States)

    Poyner, David R; Sexton, Patrick M; Marshall, Ian; Smith, David M; Quirion, Remi; Born, Walter; Muff, Roman; Fischer, Jan A; Foord, Steven M

    2002-06-01

    The calcitonin family of peptides comprises calcitonin, amylin, two calcitonin gene-related peptides (CGRPs), and adrenomedullin. The first calcitonin receptor was cloned in 1991. Its pharmacology is complicated by the existence of several splice variants. The receptors for the other members the family are made up of subunits. The calcitonin-like receptor (CL receptor) requires a single transmembrane domain protein, termed receptor activity modifying protein, RAMP1, to function as a CGRP receptor. RAMP2 and -3 enable the same CL receptor to behave as an adrenomedullin receptor. Although the calcitonin receptor does not require RAMP to bind and respond to calcitonin, it can associate with the RAMPs, resulting in a series of receptors that typically have high affinity for amylin and varied affinity for CGRP. This review aims to reconcile what is observed when the receptors are reconstituted in vitro with the properties they show in native cells and tissues. Experimental conditions must be rigorously controlled because different degrees of protein expression may markedly modify pharmacology in such a complex situation. Recommendations, which follow International Union of Pharmacology guidelines, are made for the nomenclature of these multimeric receptors.

  17. Internalization of the human CRF receptor 1 is independent of classical phosphorylation sites and of beta-arrestin 1 recruitment

    DEFF Research Database (Denmark)

    Rasmussen, Trine N; Novak, Ivana; Nielsen, Søren M

    2004-01-01

    The corticotropin releasing factor receptor 1 (CRFR1) belongs to the superfamily of G-protein coupled receptors. Though CRF is involved in the aetiology of several stress-related disorders, including depression and anxiety, details of CRFR1 regulation such as internalization remain uncharacterized...

  18. Pharmacokinetic/Pharmacodynamic Modelling of Receptor Internalization with CRTH2 Antagonists to Optimize Dose Selection.

    Science.gov (United States)

    Krause, Andreas; Zisowsky, Jochen; Strasser, Daniel S; Gehin, Martine; Sidharta, Patricia N; Groenen, Peter M A; Dingemanse, Jasper

    2016-07-01

    The chemoattractant receptor-homologous molecule expressed on T helper-2 cells (CRTH2) is a G-protein-coupled receptor for prostaglandin D2 (PGD2), a key mediator in inflammatory disorders. Two selective and potent CRTH2 antagonists currently in clinical development, ACT-453859 and setipiprant, were compared with respect to their (predicted) clinical efficacy. Population pharmacokinetic (PK) and pharmacodynamic (PD) models were developed to characterize how plasma concentrations (PK) of ACT-453859, its active metabolite ACT-463036 and setipiprant related to their effect on blocking PGD2-induced internalization of CRTH2 on eosinophils (PD). Simulations were used to identify doses and dosing regimens leading to 90 % of maximum blockade of CRTH2 internalization at trough. A combined concentration of ACT-453859 and its metabolite ACT-463036, with weights proportional to potency (based on an eosinophil shape change assay), enabled good characterization of the PD effect. The modelling and simulation results facilitated decision making by suggesting an ACT-453859 dose of 400 mg once daily (or 100 mg twice daily) for clinically relevant CRTH2 antagonism. Pharmacometric quantification demonstrated that CRTH2 internalization is a useful new biomarker to study CRTH2 antagonism. Ninety percent of maximum blockade of CRTH2 internalization at trough is suggested as a quantitative PD target in clinical studies.

  19. Internalized insulin-receptor complexes are unidirectionally translocated to chloroquine-sensitive degradative sites. Dependence on metabolic energy

    International Nuclear Information System (INIS)

    Berhanu, P.

    1988-01-01

    Insulin receptors on the surface of isolated rat adipocytes were photoaffinity labeled at 12 degrees C with the iodinated photoreactive insulin analogue, 125I-B2 (2-nitro-4-azidophenylacetyl)-des-PheB1-insulin, and the pathways in the intracellular processing of the labeled receptors were studied at 37 degrees C. During 37 degrees C incubations, the labeled 440-kDa insulin receptors were continuously internalized (as assessed by trypsin inaccessibility) and degraded such that up to 50% of the initially labeled receptors were lost by 120 min. Metabolic poisons (0.125-0.75 mM 2,4-dinitrophenol (DNP) and 1-10 mM NaF), which led to dose-dependent depletion of adipocyte ATP pools, inhibited receptor loss, and caused up to 3-fold increase in intracellular receptor accumulation. This effect was due to inhibition of intracellular receptor degradation, and there was no apparent effect of the metabolic poisons on initial internalization of the receptors. Following maximal intracellular accumulation of labeled insulin receptors in the presence of NaF or DNP, removal of these agents resulted in a subsequent, time-dependent degradation of the accumulated receptors. However, when the lysosomotropic agent, chloroquine (0.2 mM), was added immediately following removal of the metabolic poisons, further degradation of the intracellularly accumulated receptors was prevented, suggesting that the chloroquine-sensitive degradation of insulin receptors occurs distal to the site of inhibition by NaF or DNP. To confirm this, maximal intracellular accumulation of labeled receptors was first allowed to occur in the presence of chloroquine and the cells were then washed and reincubated in chloroquine-free media in the absence or presence of NaF or DNP. Under these conditions, degradation of the intracellularly accumulated receptors continued to occur, and NaF or DNP failed to block the degradation

  20. Imaging of persistent cAMP signaling by internalized G protein-coupled receptors.

    Science.gov (United States)

    Calebiro, Davide; Nikolaev, Viacheslav O; Lohse, Martin J

    2010-07-01

    G protein-coupled receptors (GPCRs) are the largest family of plasma membrane receptors. They mediate the effects of several endogenous cues and serve as important pharmacological targets. Although many biochemical events involved in GPCR signaling have been characterized in great detail, little is known about their spatiotemporal dynamics in living cells. The recent advent of optical methods based on fluorescent resonance energy transfer allows, for the first time, to directly monitor GPCR signaling in living cells. Utilizing these methods, it has been recently possible to show that the receptors for two protein/peptide hormones, the TSH and the parathyroid hormone, continue signaling to cAMP after their internalization into endosomes. This type of intracellular signaling is persistent and apparently triggers specific cellular outcomes. Here, we review these recent data and explain the optical methods used for such studies. Based on these findings, we propose a revision of the current model of the GPCR-cAMP signaling pathway to accommodate receptor signaling at endosomes.

  1. Unraveling a molecular determinant for clathrin-independent internalization of the M2 muscarinic acetylcholine receptor

    Science.gov (United States)

    Wan, Min; Zhang, Wenhua; Tian, Yangli; Xu, Chanjuan; Xu, Tao; Liu, Jianfeng; Zhang, Rongying

    2015-01-01

    Endocytosis and postendocytic sorting of G-protein-coupled receptors (GPCRs) is important for the regulation of both their cell surface density and signaling profile. Unlike the mechanisms of clathrin-dependent endocytosis (CDE), the mechanisms underlying the control of GPCR signaling by clathrin-independent endocytosis (CIE) remain largely unknown. Among the muscarinic acetylcholine receptors (mAChRs), the M4 mAChR undergoes CDE and recycling, whereas the M2 mAChR is internalized through CIE and targeted to lysosomes. Here we investigated the endocytosis and postendocytic trafficking of M2 mAChR based on a comparative analysis of the third cytoplasmic domain in M2 and M4 mAChRs. For the first time, we identified that the sequence 374KKKPPPS380 servers as a sorting signal for the clathrin-independent internalization of M2 mAChR. Switching 374KKKPPPS380 to the i3 loop of the M4 mAChR shifted the receptor into lysosomes through the CIE pathway; and therefore away from CDE and recycling. We also found another previously unidentified sequence that guides CDE of the M2 mAChR, 361VARKIVKMTKQPA373, which is normally masked in the presence of the downstream sequence 374KKKPPPS380. Taken together, our data indicate that endocytosis and postendocytic sorting of GPCRs that undergo CIE could be sequence-dependent. PMID:26094760

  2. Heterologous activation of protein kinase C stimulates phosphorylation of delta-opioid receptor at serine 344, resulting in beta-arrestin- and clathrin-mediated receptor internalization

    DEFF Research Database (Denmark)

    Xiang, B; Yu, G H; Guo, J

    2001-01-01

    The purpose of the current study is to investigate the effect of opioid-independent, heterologous activation of protein kinase C (PKC) on the responsiveness of opioid receptor and the underlying molecular mechanisms. Our result showed that removing the C terminus of delta opioid receptor (DOR......) containing six Ser/Thr residues abolished both DPDPE- and phorbol 12-myristate 13-acetate (PMA)-induced DOR phosphorylation. The phosphorylation levels of DOR mutants T352A, T353A, and T358A/T361A/S363S were comparable to that of the wild-type DOR, whereas S344G substitution blocked PMA-induced receptor......, and ionomycin resulted in DOR internalization that required phosphorylation of Ser-344. Expression of dominant negative beta-arrestin and hypertonic sucrose treatment blocked PMA-induced DOR internalization, suggesting that PKC mediates DOR internalization via a beta-arrestin- and clathrin-dependent mechanism...

  3. Clathrin-dependent internalization, signaling, and metabolic processing of guanylyl cyclase/natriuretic peptide receptor-A.

    Science.gov (United States)

    Somanna, Naveen K; Mani, Indra; Tripathi, Satyabha; Pandey, Kailash N

    2018-04-01

    Cardiac hormones, atrial and brain natriuretic peptides (ANP and BNP), have pivotal roles in renal hemodynamics, neuroendocrine signaling, blood pressure regulation, and cardiovascular homeostasis. Binding of ANP and BNP to the guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) induces rapid internalization and trafficking of the receptor via endolysosomal compartments, with concurrent generation of cGMP. However, the mechanisms of the endocytotic processes of NPRA are not well understood. The present study, using 125 I-ANP binding assay and confocal microscopy, examined the function of dynamin in the internalization of NPRA in stably transfected human embryonic kidney-293 (HEK-293) cells. Treatment of recombinant HEK-293 cells with ANP time-dependently accelerated the internalization of receptor from the cell surface to the cell interior. However, the internalization of ligand-receptor complexes of NPRA was drastically decreased by the specific inhibitors of clathrin- and dynamin-dependent receptor internalization, almost 85% by monodansylcadaverine, 80% by chlorpromazine, and 90% by mutant dynamin, which are specific blockers of endocytic vesicle formation. Visualizing the internalization of NPRA and enhanced GFP-tagged NPRA in HEK-293 cells by confocal microscopy demonstrated the formation of endocytic vesicles after 5 min of ANP treatment; this effect was blocked by the inhibitors of clathrin and by mutant dynamin construct. Our results suggest that NPRA undergoes internalization via clathrin-mediated endocytosis as part of its normal itinerary, including trafficking, signaling, and metabolic degradation.

  4. International Union of Pharmacology. LXXXIX. Update on the Extended Family of Chemokine Receptors and Introducing a New Nomenclature for Atypical Chemokine Receptors

    Science.gov (United States)

    Bachelerie, Francoise; Ben-Baruch, Adit; Burkhardt, Amanda M.; Combadiere, Christophe; Farber, Joshua M.; Graham, Gerard J.; Horuk, Richard; Sparre-Ulrich, Alexander Hovard; Locati, Massimo; Luster, Andrew D.; Mantovani, Alberto; Matsushima, Kouji; Nibbs, Robert; Nomiyama, Hisayuki; Power, Christine A.; Proudfoot, Amanda E. I.; Rosenkilde, Mette M.; Rot, Antal; Sozzani, Silvano; Thelen, Marcus; Yoshie, Osamu; Zlotnik, Albert

    2014-01-01

    Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145–176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human

  5. [Differences in dynamics of insulin and insulin-like growth I (IGF-I) receptors internalization in isolated rat hepatocytes].

    Science.gov (United States)

    Kolychev, A P; Ternovskaya, E E; Arsenieva, A V; Shapkina, E V

    2013-01-01

    Insulin and IGF-I are two related peptides performing in the mammalian body functionally different roles of the metabolic and growth hormones, respectively. Internalization of the insulin-receptor complex (IRC) is the most important chain of mechanism of the action of hormone. To elucidate differences in the main stages of internalization of the two related hormones, the internalization dynamics of 125I-insulin and 125I-IGF-I was traced in isolated rat hepatocytes at 37 and 12 degrees C. There were established marked differences in the process of internalization of labeled hormones, which is stimulated by insulin and IGF-I. At 37 degrees C the insulin-stimulated internalization, unlike the process initiated by IGF-I, did not reach the maximal level for 1 h of incubation. However, essential differences in the internalization course of these two related peptide were obvious at the temperature of 12 degrees C. The internalization level of insulin receptors at 12 degrees C decreased by one third in spite of a significant increase of the insulin receptor binding on the hepatocytes plasma membrane. At 12 degrees C a slight decrease of the proportion of intracellular 125I-IGF-I correlated with a decrease in the 125I-IGF-I binding to receptors on the cell membrane. Internalization of IGF-I receptors was not affected by low temperature, as neither its level, nor the rate changed at 12 degrees C. The paradoxical decrease of the insulin-stimulated internalization at low temperature seems to represent a peculiar "inhibition mechanism" of immersion of IRC into the cell, which leads to accumulation of the complexes on the cell surface and possibly to a readjustment of the insulin biological activity. The resistance of internalization of the IGF-I receptor to cold seems to be related to the more ancient origin of this mechanism in the poikilothermal vertebrates.

  6. Identification of phenylalanine 346 in the rat growth hormone receptor as being critical for ligand-mediated internalization and down-regulation

    DEFF Research Database (Denmark)

    Allevato, G; Billestrup, N; Goujon, L

    1995-01-01

    The functional significance of growth hormone (GH) receptor (GHR) internalization is unknown; therefore, we have analyzed domains and individual amino acids in the cytoplasmic region of the rat GHR required for ligand-mediated receptor internalization, receptor down-regulation, and transcriptiona...

  7. Imaging Agonist-Induced D2/D3 Receptor Desensitization and Internalization In Vivo with PET/fMRI.

    Science.gov (United States)

    Sander, Christin Y; Hooker, Jacob M; Catana, Ciprian; Rosen, Bruce R; Mandeville, Joseph B

    2016-04-01

    This study investigated the dynamics of dopamine receptor desensitization and internalization, thereby proposing a new technique for non-invasive, in vivo measurements of receptor adaptations. The D2/D3 agonist quinpirole, which induces receptor internalization in vitro, was administered at graded doses in non-human primates while imaging with simultaneous positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). A pronounced temporal divergence between receptor occupancy and fMRI signal was observed: occupancy remained elevated while fMRI responded transiently. Analogous experiments with an antagonist (prochlorperazine) and a lower-affinity agonist (ropinirole) exhibited reduced temporal dissociation between occupancy and function, consistent with a mechanism of desensitization and internalization that depends upon drug efficacy and affinity. We postulated a model that incorporates internalization into a neurovascular-coupling relationship. This model yielded in vivo desensitization/internalization rates (0.2/min for quinpirole) consistent with published in vitro measurements. Overall, these results suggest that simultaneous PET/fMRI enables characterization of dynamic neuroreceptor adaptations in vivo, and may offer a first non-invasive method for assessing receptor desensitization and internalization.

  8. Morphine-induced internalization of the L83I mutant of the rat μ-opioid receptor.

    Science.gov (United States)

    Cooke, A E; Oldfield, S; Krasel, C; Mundell, S J; Henderson, G; Kelly, E

    2015-01-01

    Naturally occurring single-nucleotide polymorphisms (SNPs) within GPCRs can result in alterations in various pharmacological parameters. Understanding the regulation and function of endocytic trafficking of the μ-opioid receptor (MOP receptor) is of great importance given its implication in the development of opioid tolerance. This study has compared the agonist-dependent trafficking and signalling of L83I, the rat orthologue of a naturally occurring variant of the MOP receptor. Cell surface elisa, confocal microscopy and immunoprecipitation assays were used to characterize the trafficking properties of the MOP-L83I variant in comparison with the wild-type receptor in HEK 293 cells. Functional assays were used to compare the ability of the L83I variant to signal to several downstream pathways. Morphine-induced internalization of the L83I MOP receptor was markedly increased in comparison with the wild-type receptor. The altered trafficking of this variant was found to be specific to morphine and was both G-protein receptor kinase- and dynamin-dependent. The enhanced internalization of L83I variant in response to morphine was not due to increased phosphorylation of serine 375, arrestin association or an increased ability to signal. These results suggest that morphine promotes a specific conformation of the L83I variant that makes it more liable to internalize in response to morphine, unlike the wild-type receptor that undergoes significantly less morphine-stimulated internalization, providing an example of a ligand-selective biased receptor. The presence of this SNP within an individual may consequently affect the development of tolerance and analgesic responses. 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. © 2014 The British Pharmacological Society.

  9. Charomers-Interleukin-6 Receptor Specific Aptamers for Cellular Internalization and Targeted Drug Delivery.

    Science.gov (United States)

    Hahn, Ulrich

    2017-12-06

    Interleukin-6 (IL-6) is a key player in inflammation and the main factor for the induction of acute phase protein biosynthesis. Further to its central role in many aspects of the immune system, IL-6 regulates a variety of homeostatic processes. To interfere with IL-6 dependent diseases, such as various autoimmune diseases or certain cancers like multiple myeloma or hepatocellular carcinoma associated with chronic inflammation, it might be a sensible strategy to target human IL-6 receptor (hIL-6R) presenting cells with aptamers. We therefore have selected and characterized different DNA and RNA aptamers specifically binding IL-6R. These IL-6R aptamers, however, do not interfere with the IL-6 signaling pathway but are internalized with the receptor and thus can serve as vehicles for the delivery of different cargo molecules like therapeutics. We succeeded in the construction of a chlorin e6 derivatized aptamer to be delivered for targeted photodynamic therapy (PDT). Furthermore, we were able to synthesize an aptamer intrinsically comprising the cytostatic 5-Fluoro-2'-deoxy-uridine for targeted chemotherapy. The α6β4 integrin specific DNA aptamer IDA, also selected in our laboratory is internalized, too. All these aptamers can serve as vehicles for targeted drug delivery into cells. We call them charomers-in memory of Charon, the ferryman in Greek mythology, who ferried the deceased into the underworld.

  10. Charomers—Interleukin-6 Receptor Specific Aptamers for Cellular Internalization and Targeted Drug Delivery

    Science.gov (United States)

    2017-01-01

    Interleukin-6 (IL-6) is a key player in inflammation and the main factor for the induction of acute phase protein biosynthesis. Further to its central role in many aspects of the immune system, IL-6 regulates a variety of homeostatic processes. To interfere with IL-6 dependent diseases, such as various autoimmune diseases or certain cancers like multiple myeloma or hepatocellular carcinoma associated with chronic inflammation, it might be a sensible strategy to target human IL-6 receptor (hIL-6R) presenting cells with aptamers. We therefore have selected and characterized different DNA and RNA aptamers specifically binding IL-6R. These IL-6R aptamers, however, do not interfere with the IL-6 signaling pathway but are internalized with the receptor and thus can serve as vehicles for the delivery of different cargo molecules like therapeutics. We succeeded in the construction of a chlorin e6 derivatized aptamer to be delivered for targeted photodynamic therapy (PDT). Furthermore, we were able to synthesize an aptamer intrinsically comprising the cytostatic 5-Fluoro-2′-deoxy-uridine for targeted chemotherapy. The α6β4 integrin specific DNA aptamer IDA, also selected in our laboratory is internalized, too. All these aptamers can serve as vehicles for targeted drug delivery into cells. We call them charomers—in memory of Charon, the ferryman in Greek mythology, who ferried the deceased into the underworld. PMID:29211023

  11. Charomers—Interleukin-6 Receptor Specific Aptamers for Cellular Internalization and Targeted Drug Delivery

    Directory of Open Access Journals (Sweden)

    Ulrich Hahn

    2017-12-01

    Full Text Available Interleukin-6 (IL-6 is a key player in inflammation and the main factor for the induction of acute phase protein biosynthesis. Further to its central role in many aspects of the immune system, IL-6 regulates a variety of homeostatic processes. To interfere with IL-6 dependent diseases, such as various autoimmune diseases or certain cancers like multiple myeloma or hepatocellular carcinoma associated with chronic inflammation, it might be a sensible strategy to target human IL-6 receptor (hIL-6R presenting cells with aptamers. We therefore have selected and characterized different DNA and RNA aptamers specifically binding IL-6R. These IL-6R aptamers, however, do not interfere with the IL-6 signaling pathway but are internalized with the receptor and thus can serve as vehicles for the delivery of different cargo molecules like therapeutics. We succeeded in the construction of a chlorin e6 derivatized aptamer to be delivered for targeted photodynamic therapy (PDT. Furthermore, we were able to synthesize an aptamer intrinsically comprising the cytostatic 5-Fluoro-2′-deoxy-uridine for targeted chemotherapy. The α6β4 integrin specific DNA aptamer IDA, also selected in our laboratory is internalized, too. All these aptamers can serve as vehicles for targeted drug delivery into cells. We call them charomers—in memory of Charon, the ferryman in Greek mythology, who ferried the deceased into the underworld.

  12. Multiple autophosphorylation sites of the epidermal growth factor receptor are essential for receptor kinase activity and internalization. Contrasting significance of tyrosine 992 in the native and truncated receptors

    DEFF Research Database (Denmark)

    Sorkin, A; Helin, K; Waters, C M

    1992-01-01

    The role of epidermal growth factor (EGF) receptor autophosphorylation sites in the regulation of receptor functions has been studied using cells transfected with mutant EGF receptors. Simultaneous point mutation of 4 tyrosines (Y1068, Y1086, Y1148, Y1173) to phenylalanine, as well as removal of ...

  13. G protein-coupled receptor internalization assays in the high-content screening format.

    Science.gov (United States)

    Haasen, Dorothea; Schnapp, Andreas; Valler, Martin J; Heilker, Ralf

    2006-01-01

    High-content screening (HCS), a combination of fluorescence microscopic imaging and automated image analysis, has become a frequently applied tool to study test compound effects in cellular disease-modeling systems. This chapter describes the measurement of G protein-coupled receptor (GPCR) internalization in the HCS format using a high-throughput, confocal cellular imaging device. GPCRs are the most successful group of therapeutic targets on the pharmaceutical market. Accordingly, the search for compounds that interfere with GPCR function in a specific and selective way is a major focus of the pharmaceutical industry today. This chapter describes methods for the ligand-induced internalization of GPCRs labeled previously with either a fluorophore-conjugated ligand or an antibody directed against an N-terminal tag of the GPCR. Both labeling techniques produce robust assay formats. Complementary to other functional GPCR drug discovery assays, internalization assays enable a pharmacological analysis of test compounds. We conclude that GPCR internalization assays represent a valuable medium/high-throughput screening format to determine the cellular activity of GPCR ligands.

  14. (/sup 3/H)Haloperidol labels brain dopamine receptors after its injection into the internal carotid artery of the rat

    Energy Technology Data Exchange (ETDEWEB)

    D' Ambrosio, A; Zivkovic, B; Bartholini, G [Research Department, Synthelabo-L.E.R.S., Paris (France)

    1982-04-29

    Pulse injection of (/sup 3/H)haloperidol (0.1 ..mu..Ci; 0.003 ..mu..g) into the internal carotid artery of the rat specifically labelled dopamine receptors in striatum and olfactory tubercle, as indicated by the kinetics of, and the effects of neuroleptic drugs on, the ligand disposition. The described method may prove useful for labelling brain receptors with ligands which readily cross the blood-brain barrier but which do not selectively mark their receptors if injected systemically.

  15. [3H]Haloperidol labels brain dopamine receptors after its injection into the internal carotid artery of the rat

    International Nuclear Information System (INIS)

    D'Ambrosio, A.; Zivkovic, B.; Bartholini, G.

    1982-01-01

    Pulse injection of [ 3 H]haloperidol (0.1 μCi; 0.003 μg) into the internal carotid artery of the rat specifically labelled dopamine receptors in striatum and olfactory tubercle, as indicated by the kinetics of, and the effects of neuroleptic drugs on, the ligand disposition. The described method may prove useful for labelling brain receptors with ligands which readily cross the blood-brain barrier but which do not selectively mark their receptors if injected systemically. (Auth.)

  16. Caenorhabditis elegans reveals a FxNPxY-independent low-density lipoprotein receptor internalization mechanism mediated by epsin1

    Science.gov (United States)

    Kang, Yuan-Lin; Yochem, John; Bell, Leslie; Sorensen, Erika B.; Chen, Lihsia; Conner, Sean D.

    2013-01-01

    Low-density lipoprotein receptor (LDLR) internalization clears cholesterol-laden LDL particles from circulation in humans. Defects in clathrin-dependent LDLR endocytosis promote elevated serum cholesterol levels and can lead to atherosclerosis. However, our understanding of the mechanisms that control LDLR uptake remains incomplete. To identify factors critical to LDLR uptake, we pursued a genome-wide RNA interference screen using Caenorhabditis elegans LRP-1/megalin as a model for LDLR transport. In doing so, we discovered an unanticipated requirement for the clathrin-binding endocytic adaptor epsin1 in LDLR endocytosis. Epsin1 depletion reduced LDLR internalization rates in mammalian cells, similar to the reduction observed following clathrin depletion. Genetic and biochemical analyses of epsin in C. elegans and mammalian cells uncovered a requirement for the ubiquitin-interaction motif (UIM) as critical for receptor transport. As the epsin UIM promotes the internalization of some ubiquitinated receptors, we predicted LDLR ubiquitination as necessary for endocytosis. However, engineered ubiquitination-impaired LDLR mutants showed modest internalization defects that were further enhanced with epsin1 depletion, demonstrating epsin1-mediated LDLR endocytosis is independent of receptor ubiquitination. Finally, we provide evidence that epsin1-mediated LDLR uptake occurs independently of either of the two documented internalization motifs (FxNPxY or HIC) encoded within the LDLR cytoplasmic tail, indicating an additional internalization mechanism for LDLR. PMID:23242996

  17. Internalization and down-regulation of the human epidermal growth factor receptor are regulated by the carboxyl-terminal tyrosines

    DEFF Research Database (Denmark)

    Helin, K; Beguinot, L

    1991-01-01

    with receptors in which 1, 2, or all 3 tyrosines were changed to phenylalanines. The triple point mutant EGF-R, expressed in NIH-3T3, exhibited low autophosphorylation in vivo, low biological and reduced kinase activities. Single and double point mutants were down-regulated, as well as wild type EGF......-R in response to EGF showing a half-life of about 1 h. Degradation of the triple point mutant, however, was impaired and resulted in a half-life of 4 h in the presence of EGF. EGF-dependent down-regulation of surface receptors was decreased in the triple point mutant EGF-R as was internalization and degradation...... of EGF. The specific rate of internalization of the triple point mutant was reduced. By contrast, intracellular processing of ligand previously internalized at 20 degrees C was similar between wild type and mutant receptors. Taken together the data indicate that the delay in degradation observed in cells...

  18. In vivo [3H]spiperone binding: evidence for accumulation in corpus striatum by agonist-mediated receptor internalization

    International Nuclear Information System (INIS)

    Chugani, D.C.; Ackermann, R.F.; Phelps, M.E.

    1988-01-01

    The processes of receptor internalization and recycling have been well-documented for receptors for hormones, growth factors, lysosomal enzymes, and cellular substrates. Evidence also exists that these processes also occur for beta-adrenergic, muscarinic cholinergic, and delta-opiate receptors in frog erythrocytes or cultured nervous tissue. In this study, evidence is presented that agonist-mediated receptor internalization and recycling occurs at the dopamine receptor in rat corpus striatum. First, the in vivo binding of the dopamine antagonist [3H]spiperone was increased by both electrical stimulation and pharmacologically induced increases of dopamine release. Conversely, depletion of dopamine with reserpine decreased in vivo [3H]spiperone binding, but the same reserpine treatment did not alter its in vitro binding. Second, the rate of dissociation of [3H]spiperone from microsomal membranes prepared from rat striatum following in vivo binding was fivefold slower than its dissociation following in vitro equilibrium binding. Mild detergent treatment, employed to disrupt endocytic vesicle membranes, increased the rate of dissociation of in vivo bound [3H]spiperone from microsomal membranes to values not significantly different from its in vitro bound dissociation rate. Third, treatment of rats with chloroquine, a drug that prevents receptor recycling but not internalization, prior to [3H]spiperone injection resulted in a selective increase of in vivo [3H]spiperone binding in the light microsome membranes. The existence of mechanisms that rapidly alter the number of neurotransmitter receptors at synapses provides dynamic regulation of receptors in response to varied acute stimulation states

  19. Lupus risk variants in the PXK locus alter B-cell receptor internalization

    Directory of Open Access Journals (Sweden)

    Samuel E. Vaughn

    2015-01-01

    Full Text Available Genome wide association studies have identified variants in PXK that confer risk for humoral autoimmune diseases, including systemic lupus erythematosus (SLE or lupus, rheumatoid arthritis and more recently systemic sclerosis. While PXK is involved in trafficking of epidermal growth factor Receptor (EGFR in COS-7 cells, mechanisms linking PXK to lupus pathophysiology have remained undefined. In an effort to uncover the mechanism at this locus that increases lupus-risk, we undertook a fine-mapping analysis in a large multi-ancestral study of lupus patients and controls. We define a large (257kb common haplotype that confers lupus risk detected only in European ancestral populations and spans the promoter through the 3’ UTR of PXK. The strongest association was found at rs6445972 with P < 4.62 x 10-10, OR 0.81 (0.75 – 0.86. Using stepwise logistic regression analysis, we demonstrate that one signal drives the genetic association in the region. Bayesian analysis confirms our results, identifying a 95% credible set consisting of 172 variants spanning 200kb.Functionally, we found that PXK operates on the B-cell antigen receptor (BCR; we confirmed that PXK influenced the rate of BCR internalization. Furthermore, we demonstrate that individuals carrying the risk haplotype exhibited a decreased rate of BCR internalization, a process known to impact B cell survival and cell fate. Taken together, these data define a new candidate mechanism for the genetic association of variants around PXK with lupus risk and highlight the regulation of intracellular trafficking as a genetically regulated pathway mediating human autoimmunity.

  20. Delayed internalization and lack of recycling in a beta2-adrenergic receptor fused to the G protein alpha-subunit

    Directory of Open Access Journals (Sweden)

    Floridi Aristide

    2008-10-01

    Full Text Available Abstract Background Chimeric proteins obtained by the fusion of a G protein-coupled receptor (GPCR sequence to the N-terminus of the G protein α-subunit have been extensively used to investigate several aspects of GPCR signalling. Although both the receptor and the G protein generally maintain a fully functional state in such polypeptides, original observations made using a chimera between the β2-adrenergic receptor (β2AR and Gαs indicated that the fusion to the α-subunit resulted in a marked reduction of receptor desensitization and down-regulation. To further investigate this phenomenon, we have compared the rates of internalization and recycling between wild-type and Gαs-fused β2AR. Results The rate of agonist-induced internalization, measured as the disappearance of cell surface immunofluorescence in HEK293 cells permanently expressing N-terminus tagged receptors, was reduced three-fold by receptor-G protein fusion. However, both fused and non-fused receptors translocated to the same endocytic compartment, as determined by dual-label confocal analysis of cells co-expressing both proteins and transferrin co-localization. Receptor recycling, determined as the reversion of surface immunofluorescence following the addition of antagonist to cells that were previously exposed to agonist, markedly differed between wild-type and fused receptors. While most of the internalized β2AR returned rapidly to the plasma membrane, β2AR-Gαs did not recycle, and the observed slow recovery for the fusion protein immunofluorescence was entirely accounted for by protein synthesis. Conclusion The covalent linkage between β2AR and Gαs does not appear to alter the initial endocytic translocation of the two proteins, although there is reduced efficiency. It does, however, completely disrupt the process of receptor and G protein recycling. We conclude that the physical separation between receptor and Gα is not necessary for the transit to early endosomes

  1. Ligand-induced internalization of neurotensin in transfected COS-7 cells: differential intracellular trafficking of ligand and receptor.

    Science.gov (United States)

    Vandenbulcke, F; Nouel, D; Vincent, J P; Mazella, J; Beaudet, A

    2000-09-01

    The neuropeptide neurotensin (NT) is known to be internalized in a receptor-mediated fashion into its target cells. To gain insight into the mechanisms underlying this process, we monitored in parallel the migration of the NT1 neurotensin receptor subtype and a fluorescent analog of NT (fluo-NT) in COS-7 cells transfected with a tagged NT1 construct. Fluo-NT internalization was prevented by hypertonic sucrose, potassium depletion and cytosol acidification, demonstrating that it proceeded via clathrin-coated pits. Within 0-30 minutes, fluo-NT accumulated together with its receptor in Acridine Orange-positive, acidic organelles. These organelles concentrated transferrin and immunostained positively for rab 5A, therefore they were early endosomes. After 30-45 minutes, the ligand and its receptor no longer colocalized. Fluo-NT was first found in rab 7-positive late endosomes and later in a nonacidic juxtanuclear compartment identified as the Trans-Golgi Network (TGN) by virtue of its staining for syntaxin 6. This juxtanuclear compartment also stained positively for rab 7 and for the TGN/pericentriolar recycling endosome marker rab 11, suggesting that the ligand could have been recruited to the TGN from either late or recycling endosomes. By that time, internalized receptors were detected in Lamp-1-immunoreactive lysosomes. These results demonstrate that neurotensin/NT1 receptor complexes follow a recycling cycle that is unique among the G protein-coupled receptors studied to date, and provide the first evidence for the targeting of a nonendogenous protein from endosomes to the TGN.

  2. SGIP1 alters internalization and modulates signaling of activated cannabinoid receptor 1 in a biased manner

    Czech Academy of Sciences Publication Activity Database

    Hájková, Alena; Techlovská, Šárka; Dvořáková, Michaela; Chambers, Jayne Nicole; Kumpošt, Jiří; Hubálková, Pavla; Prezeau, L.; Blahoš, Jaroslav

    2016-01-01

    Roč. 107, léto (2016), s. 201-214 ISSN 0028-3908 R&D Projects: GA ČR GAP303/12/2408 Institutional support: RVO:68378050 Keywords : Seven transmembrane receptors * G-protein coupled receptors * Cannabinoid receptor 1 * Protein-protein interactions * Bias signaling * Receptor endocytosis Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.012, year: 2016

  3. ARF6 Activated by the LHCG Receptor through the Cytohesin Family of Guanine Nucleotide Exchange Factors Mediates the Receptor Internalization and Signaling*

    Science.gov (United States)

    Kanamarlapudi, Venkateswarlu; Thompson, Aiysha; Kelly, Eamonn; López Bernal, Andrés

    2012-01-01

    The luteinizing hormone chorionic gonadotropin receptor (LHCGR) is a Gs-coupled GPCR that is essential for the maturation and function of the ovary and testis. LHCGR is internalized following its activation, which regulates the biological responsiveness of the receptor. Previous studies indicated that ADP-ribosylation factor (ARF)6 and its GTP-exchange factor (GEF) cytohesin 2 regulate LHCGR internalization in follicular membranes. However, the mechanisms by which ARF6 and cytohesin 2 regulate LHCGR internalization remain incompletely understood. Here we investigated the role of the ARF6 signaling pathway in the internalization of heterologously expressed human LHCGR (HLHCGR) in intact cells using a combination of pharmacological inhibitors, siRNA and the expression of mutant proteins. We found that human CG (HCG)-induced HLHCGR internalization, cAMP accumulation and ARF6 activation were inhibited by Gallein (βγ inhibitor), Wortmannin (PI 3-kinase inhibitor), SecinH3 (cytohesin ARF GEF inhibitor), QS11 (an ARF GAP inhibitor), an ARF6 inhibitory peptide and ARF6 siRNA. However, Dynasore (dynamin inhibitor), the dominant negative mutants of NM23-H1 (dynamin activator) and clathrin, and PBP10 (PtdIns 4,5-P2-binding peptide) inhibited agonist-induced HLHCGR and cAMP accumulation but not ARF6 activation. These results indicate that heterotrimeric G-protein, phosphatidylinositol (PI) 3-kinase (PI3K), cytohesin ARF GEF and ARF GAP function upstream of ARF6 whereas dynamin and clathrin act downstream of ARF6 in the regulation of HCG-induced HLHCGR internalization and signaling. In conclusion, we have identified the components and molecular details of the ARF6 signaling pathway required for agonist-induced HLHCGR internalization. PMID:22523074

  4. Internalization of Rat FSH and LH/CG Receptors by rec-eCG in CHO-K1 Cells.

    Science.gov (United States)

    Park, Jong-Ju; Seong, Hun-Ki; Kim, Jeong-Soo; Munkhzaya, Byambaragchaa; Kang, Myung-Hwa; Min, Kwan-Sik

    2017-06-01

    Equine chorionic gonadotropin (eCG) is a unique molecule that elicits the response characteristics of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in other species. Previous studies from this laboratory had demonstrated that recombinant eCG (rec-eCG) from Chinese hamster ovary (CHO-K1) cells exhibited both FSH- and LH-like activity in rat granulosa and Leydig cells. In this study, we analyzed receptor internalization through rec-eCGs, wild type eCG (eCGβ/α) and mutant eCG (eCGβ/αΔ56) with an N-linked oligosaccharide at Asn 56 of the α-subunit. Both the rec-eCGs were obtained from CHO-K1 cells. The agonist activation of receptors was analyzed by measuring stimulation time and concentrations of rec-eCGs. Internalization values in the stably selected rat follicle-stimulating hormone receptor (rFSHR) and rat luteinizing/chorionic gonadotropin receptor (rLH/CGR) were highest at 50 min after stimulation with 10 ng of rec-eCGβ/α. The dose-dependent response was highest when 10 ng of rec-eCGβ/α was used. The deglycosylated eCGβ/αΔ56 mutant did not enhance the agonist-stimulated internalization. We concluded that the state of activation of rFSHR and rLH/CGR could be modulated through agonist-stimulated internalization. Our results suggested that the eLH/CGRs are mostly internalized within 60 min by agonist-stimulation by rec-eCG. We also suggested that the lack of responsiveness of the deglycosylated eCGβ/ αΔ56 was likely because the site of glycosylation played a pivotal role in agonist-stimulated internalization in cells expressing rFSHR and rLH/CGR.

  5. Internalization of EGF receptor following lipid rafts disruption in keratinocytes is delayed and dependent on p38 MAPK activation

    DEFF Research Database (Denmark)

    Lambert, S.; Ameels, H.; Gniadecki, R.

    2008-01-01

    The receptor for epidermal growth factor (EGF) plays an important role in epidermal keratinocytes and is known to move out of lipid raft after cholesterol depletion, leading to ligand-independent activation. Accumulation of evidence indicates the ability of EGF receptor (EGFR) to undergo internal......The receptor for epidermal growth factor (EGF) plays an important role in epidermal keratinocytes and is known to move out of lipid raft after cholesterol depletion, leading to ligand-independent activation. Accumulation of evidence indicates the ability of EGF receptor (EGFR) to undergo...... internalization without participation of the ligand under the control of p38 MAPK during stress conditions. Since cholesterol depletion using methyl-beta-cyclodextrin is known to induce ligand-independent activation of EGFR in keratinocytes, we investigated by confocal microscopy and ligand-binding tests...... the process of internalization, which can be considered as a protective response to stress. Moreover, cholesterol-depleted keratinocytes recover their ability to proliferate during the recovery period that follows lipid raft disruption Udgivelsesdato: 2008/12...

  6. Aberrant Receptor Internalization and Enhanced FRS2-dependent Signaling Contribute to the Transforming Activity of the Fibroblast Growth Factor Receptor 2 IIIb C3 Isoform*

    Science.gov (United States)

    Cha, Jiyoung Y.; Maddileti, Savitri; Mitin, Natalia; Harden, T. Kendall; Der, Channing J.

    2009-01-01

    Alternative splice variants of fibroblast growth factor receptor 2 (FGFR2) IIIb, designated C1, C2, and C3, possess progressive reduction in their cytoplasmic carboxyl termini (822, 788, and 769 residues, respectively), with preferential expression of the C2 and C3 isoforms in human cancers. We determined that the progressive deletion of carboxyl-terminal sequences correlated with increasing transforming potency. The highly transforming C3 variant lacks five tyrosine residues present in C1, and we determined that the loss of Tyr-770 alone enhanced FGFR2 IIIb C1 transforming activity. Because Tyr-770 may compose a putative YXXL sorting motif, we hypothesized that loss of Tyr-770 in the 770YXXL motif may cause disruption of FGFR2 IIIb C1 internalization and enhance transforming activity. Surprisingly, we found that mutation of Leu-773 but not Tyr-770 impaired receptor internalization and increased receptor stability and activation. Interestingly, concurrent mutations of Tyr-770 and Leu-773 caused 2-fold higher transforming activity than caused by the Y770F or L773A single mutations, suggesting loss of Tyr and Leu residues of the 770YXXL773 motif enhances FGFR2 IIIb transforming activity by distinct mechanisms. We also determined that loss of Tyr-770 caused persistent activation of FRS2 by enhancing FRS2 binding to FGFR2 IIIb. Furthermore, we found that FRS2 binding to FGFR2 IIIb is required for increased FRS2 tyrosine phosphorylation and enhanced transforming activity by Y770F mutation. Our data support a dual mechanism where deletion of the 770YXXL773 motif promotes FGFR2 IIIb C3 transforming activity by causing aberrant receptor recycling and stability and persistent FRS2-dependent signaling. PMID:19103595

  7. Deletion of the distal COOH-terminus of the A2B adenosine receptor switches internalization to an arrestin- and clathrin-independent pathway and inhibits recycling.

    Science.gov (United States)

    Mundell, S J; Matharu, A-L; Nisar, S; Palmer, T M; Benovic, J L; Kelly, E

    2010-02-01

    We have investigated the effect of deletions of a postsynaptic density, disc large and zo-1 protein (PDZ) motif at the end of the COOH-terminus of the rat A(2B) adenosine receptor on intracellular trafficking following long-term exposure to the agonist 5'-(N-ethylcarboxamido)-adenosine. The trafficking of the wild type A(2B) adenosine receptor and deletion mutants expressed in Chinese hamster ovary cells was studied using an enzyme-linked immunosorbent assay in combination with immunofluorescence microscopy. The wild type A(2B) adenosine receptor and deletion mutants were all extensively internalized following prolonged treatment with NECA. The intracellular compartment through which the Gln(325)-stop receptor mutant, which lacks the Type II PDZ motif found in the wild type receptor initially trafficked was not the same as the wild type receptor. Expression of dominant negative mutants of arrestin-2, dynamin or Eps-15 inhibited internalization of wild type and Leu(330)-stop receptors, whereas only dominant negative mutant dynamin inhibited agonist-induced internalization of Gln(325)-stop, Ser(326)-stop and Phe(328)-stop receptors. Following internalization, the wild type A(2B) adenosine receptor recycled rapidly to the cell surface, whereas the Gln(325)-stop receptor did not recycle. Deletion of the COOH-terminus of the A(2B) adenosine receptor beyond Leu(330) switches internalization from an arrestin- and clathrin-dependent pathway to one that is dynamin dependent but arrestin and clathrin independent. The presence of a Type II PDZ motif appears to be essential for arrestin- and clathrin-dependent internalization, as well as recycling of the A(2B) adenosine receptor following prolonged agonist addition.

  8. C-terminal of human histamine H1 receptors regulates their agonist-induced clathrin-mediated internalization and G-protein signaling.

    Science.gov (United States)

    Hishinuma, Shigeru; Nozawa, Hiroki; Akatsu, Chizuru; Shoji, Masaru

    2016-11-01

    It has been suggested that the agonist-induced internalization of G-protein-coupled receptors from the cell surface into intracellular compartments regulates cellular responsiveness. We previously reported that G q/11 -protein-coupled human histamine H 1 receptors internalized via clathrin-dependent mechanisms upon stimulation with histamine. However, the molecular determinants of H 1 receptors responsible for agonist-induced internalization remain unclear. In this study, we evaluated the roles of the intracellular C-terminal of human histamine H 1 receptors tagged with hemagglutinin (HA) at the N-terminal in histamine-induced internalization in Chinese hamster ovary cells. The histamine-induced internalization was evaluated by the receptor binding assay with [ 3 H]mepyramine and confocal immunofluorescence microscopy with an anti-HA antibody. We found that histamine-induced internalization was inhibited under hypertonic conditions or by pitstop, a clathrin terminal domain inhibitor, but not by filipin or nystatin, disruptors of the caveolar structure and function. The histamine-induced internalization was also inhibited by truncation of a single amino acid, Ser487, located at the end of the intracellular C-terminal of H 1 receptors, but not by its mutation to alanine. In contrast, the receptor-G-protein coupling, which was evaluated by histamine-induced accumulation of [ 3 H]inositol phosphates, was potentiated by truncation of Ser487, but was lost by its mutation to alanine. These results suggest that the intracellular C-terminal of human H 1 receptors, which only comprises 17 amino acids (Cys471-Ser487), plays crucial roles in both clathrin-dependent internalization of H 1 receptors and G-protein signaling, in which truncation of Ser487 and its mutation to alanine are revealed to result in biased signaling toward activation of G-proteins and clathrin-mediated internalization, respectively. © 2016 International Society for Neurochemistry.

  9. Evidence for ligand and/or receptor-specific mechanisms of internalization and processing in cultured H35 hepatoma cells

    International Nuclear Information System (INIS)

    Goldberg, R.I.; Smith, R.M.; Jarett, L.

    1987-01-01

    Total cell associated (TC) and intracellularly accumulated (IC) 125 I-labeled insulin (INS) or α-2-macroglobulin (α2M) were assessed in cultured H35 hepatoma cells which were preincubated with various agents. Cytochalasin D or sodium azide, which affect microfilament- or energy-dependent receptor internalization, had no significant effects on INS TC or IC but each decreased α2M TC and IC to 50-75% of control. Monensin and chloroquine, acidotrophic agents, each increased INS TC and IC to 150-300% of control yet decreased TC and IC of α2M to 20-50% of control. Only leupeptin, a lysosomal protease inhibitor, caused an increase in both INS and α2M TC and IC. These data suggest significant differences exist in the biochemical regulation or structural routes of INS and α2M receptors and/or receptor-ligand complexes in their (1) internalization, (2) processing in acidic organelles, (3) recycling to the cell surface or in combinations of the above. Biochemical and ultrastructural studies are being performed on the H35 hepatoma cell which will characterize the processing of INS and α2M receptors and provide an explanation for the differences observed

  10. Comparative analysis of the internalization of the macrophage receptor sialoadhesin in human and mouse primary macrophages and cell lines.

    Science.gov (United States)

    De Schryver, Marjorie; Leemans, Annelies; Pintelon, Isabel; Cappoen, Davie; Maes, Louis; Caljon, Guy; Cos, Paul; Delputte, Peter L

    2017-06-01

    Sialoadhesin (Sn) is a surface receptor expressed on resident macrophages with the ability to bind with sialic acids. During inflammation, an upregulation of Sn is observed. Upon binding of monoclonal antibodies to Sn, the receptor becomes internalized and this has been observed in multiple species. The latter characteristic, combined with the strong upregulation of Sn on inflammatory macrophages and the fact that Sn-positive macrophages contribute to certain inflammatory diseases, makes Sn an interesting entry portal for phenotype-modulating or cytotoxic drugs. Such drugs or toxins can be linked to Sn-specific antibodies which should enable their targeted uptake by macrophages. However, the activity of such drugs depends not only on their internalization but also on the intracellular trafficking and final fate in the endolysosomal system. Although information is available for porcine Sn, the detailed mechanisms of human and mouse Sn internalization and subsequent intracellular trafficking are currently unknown. To allow development of Sn-targeted therapies, differences across species and cellular background need to be characterized in more detail. In the current report, we show that internalization of human and mouse Sn is dynamin-dependent and clathrin-mediated, both in primary macrophages and CHO cell lines expressing a recombinant Sn. In primary macrophages, internalized Sn-specific F(ab') 2 fragments are located mostly in the early endosomes. With Fc containing Sn-specific antibodies, there is a slight shift towards lysosomal localization in mouse macrophages, possibly because of an interaction with Fc receptors. Surprisingly, in CHO cell lines expressing Sn, there is a predominant lysosomal localization. Our results show that the mechanism of Sn internalization and intracellular trafficking is concurrent in the tested species. The cellular background in which Sn is expressed and the type of antibody used can affect the intracellular fate, which in turn can

  11. Ephrinb1 and Ephrinb2 Are Associated with Interleukin-7 Receptor α and Retard Its Internalization from the Cell Surface*

    Science.gov (United States)

    Luo, Hongyu; Wu, Zenghui; Qi, Shijie; Jin, Wei; Han, Bing; Wu, Jiangping

    2011-01-01

    IL-7 plays vital roles in thymocyte development, T cell homeostasis, and the survival of these cells. IL-7 receptor α (IL-7Rα) on thymocytes and T cells is rapidly internalized upon IL-7 ligation. Ephrins (Efns) are cell surface molecules and ligands of the largest receptor kinase family, Eph kinases. We discovered that T cell-specific double gene knock-out (dKO) of Efnb1 and Efnb2 in mice led to reduced IL-7Rα expression in thymocytes and T cells, and that IL-7Rα down-regulation was accelerated in dKO CD4 cells upon IL-7 treatment. On the other hand, Efnb1 and Efnb2 overexpression on T cell lymphoma EL4 cells retarded IL-7Rα down-regulation. dKO T cells manifested compromised STAT5 activation and homeostatic proliferation, an IL-7-dependent process. Fluorescence resonance energy transfer and immunoprecipitation demonstrated that Efnb1 and Efnb2 interacted physically with IL-7Rα. Such interaction likely retarded IL-7Rα internalization, as Efnb1 and Efnb2 were not internalized. Therefore, we revealed a novel function of Efnb1 and Efnb2 in stabilizing IL-7Rα expression at the post-translational level, and a previously unknown modus operandi of Efnbs in the regulation of expression of other vital cell surface receptors. PMID:22069310

  12. receptores

    Directory of Open Access Journals (Sweden)

    Salete Regina Daronco Benetti

    2006-01-01

    Full Text Available Se trata de un estudio etnográfico, que tuvo lo objetivo de interpretar el sistema de conocimiento y del significado atribuidos a la sangre referente a la transfusión sanguínea por los donadores y receptores de un banco de sangre. Para la colecta de las informaciones se observaron los participantes y la entrevista etnográfica se realizó el análisis de dominio, taxonómicos y temáticos. Los dominios culturales fueron: la sangre es vida: fuente de vida y alimento valioso; creencias religiosas: fuentes simbólicas de apoyos; donación sanguínea: un gesto colaborador que exige cuidarse, gratifica y trae felicidad; donación sanguínea: fuente simbólica de inseguridad; estar enfermo es una condición para realizar transfusión sanguínea; transfusión sanguínea: esperanza de vida; Creencias populares: transfusión sanguínea como riesgo para la salud; donadores de sangre: personas benditas; donar y recibir sangre: como significado de felicidad. Temática: “líquido precioso que origina, sostiene, modifica la vida, provoca miedo e inseguridad”.

  13. Ligand- and cell-dependent determinants of internalization and cAMP modulation by delta opioid receptor (DOR) agonists

    Science.gov (United States)

    Charfi, Iness; Nagi, Karim; Mnie-Filali, Ouissame; Thibault, Dominic; Balboni, Gianfranco; Schiller, Peter W.; Trudeau, Louis-Eric

    2014-01-01

    Signaling bias refers to G protein-coupled receptor ligand ability to preferentially activate one type of signal over another. Bias to evoke signaling as opposed to sequestration has been proposed as a predictor of opioid ligand potential for generating tolerance. Here we measured whether delta opioid receptor agonists preferentially inhibited cyclase activity over internalization in HEK cells. Efficacy (τ) and affinity (KA) values were estimated from functional data and bias was calculated from efficiency coefficients (log τ/KA). This approach better represented the data as compared to alternative methods that estimate bias exclusively from τ values. Log (τ/KA) coefficients indicated that SNC-80 and UFP-512 promoted cyclase inhibition more efficiently than DOR internalization as compared to DPDPE (bias factor for SNC-80: 50 and for UFP-512: 132). Molecular determinants of internalization were different in HEK293 cells and neurons with βarrs contributing to internalization in both cell types, while PKC and GRK2 activities were only involved in neurons. Rank orders of ligand ability to engage different internalization mechanisms in neurons were compared to rank order of Emax values for cyclase assays in HEK cells. Comparison revealed a significant reversal in rank order for cyclase Emax values and βarr-dependent internalization in neurons, indicating that these responses were ligand-specific. Despite this evidence, and because kinases involved in internalization were not the same across cellular backgrounds, it is not possible to assert if the magnitude and nature of bias revealed by rank orders of maximal responses is the same as the one measured in HEK cells. PMID:24022593

  14. Identification of specific sites in the third intracellular loop and carboxyl terminus of the Bombyx mori PBAN receptor crucial for ligand-induced internalization

    Science.gov (United States)

    Sex pheromone production in most moths is mediated by the pheromone biosynthesis activating neuropeptide receptor (PBANR). Similar to other rhodopsin-like G protein-coupled receptors, the silkmoth Bombyx mori PBANR (BmPBANR) undergoes agonist-induced internalization. Despite interest in developing...

  15. Different amounts of ejaculatory activity, a natural rewarding behavior, induce differential mu and delta opioid receptor internalization in the rat's ventral tegmental area.

    Science.gov (United States)

    Garduño-Gutiérrez, René; León-Olea, Martha; Rodríguez-Manzo, Gabriela

    2013-12-06

    Opioid receptors internalize upon specific agonist stimulation. The in vivo significance of receptor internalization is not well established, partly due to the limited in vivo models used to study this phenomenon. Ejaculation promotes endogenous opioid release which activates opioid receptors at the brain, including the mesolimbic system and medial preoptic area. The objective of the present work was to analyze if there was a correlation between the degree of in vivo mu (MOR) and delta opioid receptor (DOR) internalization in the ventral tegmental area and the execution of different amounts of ejaculatory behavior of male rats. To this aim, we analyzed the brains of rats that ejaculated once or six successive times and of sexually exhausted rats with an established sexual inhibition, using immunofluorescence and confocal microscopy. Results showed that MOR and DOR internalization increased as a consequence of ejaculation. There was a relationship between the amount of sexual activity executed and the degree of internalization for MOR, but not for DOR. MOR internalization was larger in rats that ejaculated repeatedly than in animals ejaculating only once. Significant DOR internalization was found only in animals ejaculating once. Changes in MOR, DOR and beta arrestin2 detection, associated to sexual activity, were also found. It is suggested that copulation to satiety might be useful as a model system to study the biological significance of receptor internalization. © 2013 Published by Elsevier B.V.

  16. Tracking Drug-induced Changes in Receptor Post-internalization Trafficking by Colocalizational Analysis.

    Science.gov (United States)

    Ong, Edmund; Cahill, Catherine

    2015-07-03

    The intracellular trafficking of receptors is a collection of complex and highly controlled processes. Receptor trafficking modulates signaling and overall cell responsiveness to ligands and is, itself, influenced by intra- and extracellular conditions, including ligand-induced signaling. Optimized for use with monolayer-plated cultured cells, but extendable to free-floating tissue slices, this protocol uses immunolabelling and colocalizational analysis to track changes in intracellular receptor trafficking following both chronic/prolonged and acute interventions, including exogenous drug treatment. After drug treatment, cells are double-immunolabelled for the receptor and for markers for the intracellular compartments of interest. Sequential confocal microscopy is then used to capture two-channel photomicrographs of individual cells, which are subjected to computerized colocalizational analysis to yield quantitative colocalization scores. These scores are normalized to permit pooling of independent replicates prior to statistical analysis. Representative photomicrographs may also be processed to generate illustrative figures. Here, we describe a powerful and flexible technique for quantitatively assessing induced receptor trafficking.

  17. Hemin inhibits internalization of transferrin by reticulocytes and promotes phosphorylation of the membrane transferrin receptor

    International Nuclear Information System (INIS)

    Cox, T.M.; O'Donnell, M.W.; Aisen, P.; London, I.M.

    1985-01-01

    Addition of hemin to reticulocytes inhibits incorporation of iron from transferrin. Heme also regulates protein synthesis in immature erythroid cells through its effects on phosphorylation of the initiation factor eIF-2. The authors have examined its effects on endocytosis of iron-transferrin and phosphorylation of the transferrin receptor. Hemin reduced iron transport but increased cell-associated transferrin. During uptake of 125 I-labeled transferrin in the steady state, the use of a washing technique to dissociate bound transferrin on the cell membrane showed that radioligand accumulated on the surface of hemin-treated cells. Receptor phosphorylation was investigated by immunoprecipitation of reticulocyte extracts after metabolic labeling with [ 32 P]P/sub i/. In the absence of ligand, phosphorylated receptor was chiefly localized on cell stroma. Exposure to transferrin increased cytosolic phosphorylated receptor from 15-30% to approximately 50% of the total, an effect overcome by hemin treatment. The findings suggest a possible relationship of phosphorylation to endocytosis of the transferrin receptor in reticulocytes

  18. Nonmuscle Myosin II Is Required for Internalization of the Epidermal Growth Factor Receptor and Modulation of Downstream Signaling*

    Science.gov (United States)

    Kim, Jong Hyun; Wang, Aibing; Conti, Mary Anne; Adelstein, Robert S.

    2012-01-01

    Ligand-induced internalization of the epidermal growth factor receptor (EGFR) is an important process for regulating signal transduction, cellular dynamics, and cell-cell communication. Here, we demonstrate that nonmuscle myosin II (NM II) is required for the internalization of the EGFR and to trigger the EGFR-dependent activation of ERK and AKT. The EGFR was identified as a protein that interacts with NM II by co-immunoprecipitation and mass spectrometry analysis. This interaction requires both the regulatory light chain 20 (RLC20) of NM II and the kinase domain of the EGFR. Two paralogs of NM II, NM II-A, and NM II-B can act to internalize the EGFR, depending on the cell type and paralog content of the cell line. Loss (siRNA) or inhibition (25 μm blebbistatin) of NM II attenuates the internalization of the EGFR and impairs EGFR-dependent activation of ERK and AKT. Both internalization of the EGFR and downstream signaling to ERK and AKT can be partially restored in siRNA-treated cells by introduction of wild type (WT) GFP-NM II, but cannot be restored by motor mutant NM II. Taken together, these results suggest that NM II plays a role in the internalization of the EGFR and EGFR-mediated signaling pathways. PMID:22718763

  19. Functional role of the extracellular N-terminal domain of neuropeptide Y subfamily receptors in membrane integration and agonist-stimulated internalization.

    Science.gov (United States)

    Lindner, Diana; Walther, Cornelia; Tennemann, Anja; Beck-Sickinger, Annette G

    2009-01-01

    The N terminus is the most variable element in G protein-coupled receptors (GPCRs), ranging from seven residues up to approximately 5900 residues. For family B and C GPCRs it is described that at least part of the ligand binding site is located within the N terminus. Here we investigated the role of the N terminus in the neuropeptide Y receptor family, which belongs to the class A of GPCRs. We cloned differentially truncated Y receptor mutants, in which the N terminus was partially or completely deleted. We found, that eight amino acids are sufficient for full ligand binding and signal transduction activity. Interestingly, we could show that no specific amino acids but rather the extension of the first transmembrane helix by any residues is sufficient for receptor activity but also for membrane integration in case of the hY(1) and the hY(4) receptors. In contrast, the complete deletion of the N terminus in the hY(2) receptors resulted in a mutant that is fully integrated in the membrane but does not bind the ligand very well and internalizes much slower compared to the wild type receptor. Interestingly, also these effects could be reverted by any N-terminal extension. Accordingly, the most important function of the N termini seems to be the stabilization of the first transmembrane helix to ensure the correct receptor structure, which obviously is essential for ligand binding, integration into the cell membrane and receptor internalization.

  20. Direct demonstration of rapid insulin-like growth factor II receptor internalization and recycling in rat adipocytes. Insulin stimulates 125I-insulin-like growth factor II degradation by modulating the IGF-II receptor recycling process

    International Nuclear Information System (INIS)

    Oka, Y.; Rozek, L.M.; Czech, M.P.

    1985-01-01

    The photoactive insulin-like growth factor (IGF)-II analogue 4-azidobenzoyl- 125 I-IGF-II was synthesized and used to label specifically and covalently the Mr = 250,000 Type II IGF receptor. When rat adipocytes are irradiated after a 10-min incubation with 4-azidobenzoyl- 125 I-IGF-II at 10 degrees C and immediately homogenized, most of the labeled IGF-II receptors are associated with the plasma membrane fraction, indicating that receptors accessible to the labeling reagent at low temperature are on the cell surface. However, when the photolabeled cells are incubated at 37 degrees C for various times before homogenization, labeled IGF-II receptors are rapidly internalized with a half-time of 3.5 min as evidenced by a loss from the plasma membrane fraction and a concomitant appearance in the low density microsome fraction. The steady state level of cell surface IGF-II receptors in the presence or absence of IGF-II remains constant under these conditions, demonstrating that IGF-II receptors rapidly recycle back to the cell surface at the same rate as receptor internalization. Using the above methodology, it is shown that acute insulin action: 1) increases the steady state number of cell surface IGF-II receptors; 2) increases the number of ligand-bound IGF-II receptors that are internalized per unit of time; and 3) increases the rate of cellular 125 I-IGF-II degradation by a process that is blocked by anti-IGF-II receptor antibody

  1. Cryptococcus neoformans Is Internalized by Receptor-Mediated or ‘Triggered’ Phagocytosis, Dependent on Actin Recruitment

    Science.gov (United States)

    Guerra, Caroline Rezende; Seabra, Sergio Henrique; de Souza, Wanderley; Rozental, Sonia

    2014-01-01

    Cryptococcosis by the encapsulated yeast Cryptococcus neoformans affects mostly immunocompromised individuals and is a frequent neurological complication in AIDS patients. Recent studies support the idea that intracellular survival of Cryptococcus yeast cells is important for the pathogenesis of cryptococcosis. However, the initial steps of Cryptococcus internalization by host cells remain poorly understood. Here, we investigate the mechanism of Cryptococcus neoformans phagocytosis by peritoneal macrophages using confocal and electron microscopy techniques, as well as flow cytometry quantification, evaluating the importance of fungal capsule production and of host cell cytoskeletal elements for fungal phagocytosis. Electron microscopy analyses revealed that capsular and acapsular strains of C. neoformans are internalized by macrophages via both ‘zipper’ (receptor-mediated) and ‘trigger’ (membrane ruffle-dependent) phagocytosis mechanisms. Actin filaments surrounded phagosomes of capsular and acapsular yeasts, and the actin depolymerizing drugs cytochalasin D and latrunculin B inhibited yeast internalization and actin recruitment to the phagosome area. In contrast, nocodazole and paclitaxel, inhibitors of microtubule dynamics decreased internalization but did not prevent actin recruitment to the site of phagocytosis. Our results show that different uptake mechanisms, dependent on both actin and tubulin dynamics occur during yeast internalization by macrophages, and that capsule production does not affect the mode of Cryptococcus uptake by host cells. PMID:24586631

  2. Adaptor Protein Complex-2 (AP-2) and Epsin-1 Mediate Protease-activated Receptor-1 Internalization via Phosphorylation- and Ubiquitination-dependent Sorting Signals*

    Science.gov (United States)

    Chen, Buxin; Dores, Michael R.; Grimsey, Neil; Canto, Isabel; Barker, Breann L.; Trejo, JoAnn

    2011-01-01

    Signaling by protease-activated receptor-1 (PAR1), a G protein-coupled receptor (GPCR) for thrombin, is regulated by desensitization and internalization. PAR1 desensitization is mediated by β-arrestins, like most classic GPCRs. In contrast, internalization of PAR1 occurs through a clathrin- and dynamin-dependent pathway independent of β-arrestins. PAR1 displays two modes of internalization. Constitutive internalization of unactivated PAR1 is mediated by the clathrin adaptor protein complex-2 (AP-2), where the μ2-adaptin subunit binds directly to a tyrosine-based motif localized within the receptor C-tail domain. However, AP-2 depletion only partially inhibits agonist-induced internalization of PAR1, suggesting a function for other clathrin adaptors in this process. Here, we now report that AP-2 and epsin-1 are both critical mediators of agonist-stimulated PAR1 internalization. We show that ubiquitination of PAR1 and the ubiquitin-interacting motifs of epsin-1 are required for epsin-1-dependent internalization of activated PAR1. In addition, activation of PAR1 promotes epsin-1 de-ubiquitination, which may increase its endocytic adaptor activity to facilitate receptor internalization. AP-2 also regulates activated PAR1 internalization via recognition of distal C-tail phosphorylation sites rather than the canonical tyrosine-based motif. Thus, AP-2 and epsin-1 are both required to promote efficient internalization of activated PAR1 and recognize discrete receptor sorting signals. This study defines a new pathway for internalization of mammalian GPCRs. PMID:21965661

  3. A Broad G Protein-Coupled Receptor Internalization Assay that Combines SNAP-Tag Labeling, Diffusion-Enhanced Resonance Energy Transfer, and a Highly Emissive Terbium Cryptate.

    Science.gov (United States)

    Levoye, Angélique; Zwier, Jurriaan M; Jaracz-Ros, Agnieszka; Klipfel, Laurence; Cottet, Martin; Maurel, Damien; Bdioui, Sara; Balabanian, Karl; Prézeau, Laurent; Trinquet, Eric; Durroux, Thierry; Bachelerie, Françoise

    2015-01-01

    Although G protein-coupled receptor (GPCR) internalization has long been considered as a major aspect of the desensitization process that tunes ligand responsiveness, internalization is also involved in receptor resensitization and signaling, as well as the ligand scavenging function of some atypical receptors. Internalization thus contributes to the diversity of GPCR-dependent signaling, and its dynamics and quantification in living cells has generated considerable interest. We developed a robust and sensitive assay to follow and quantify ligand-induced and constitutive-induced GPCR internalization but also receptor recycling in living cells. This assay is based on diffusion-enhanced resonance energy transfer (DERET) between cell surface GPCRs labeled with a luminescent terbium cryptate donor and a fluorescein acceptor present in the culture medium. GPCR internalization results in a quantifiable reduction of energy transfer. This method yields a high signal-to-noise ratio due to time-resolved measurements. For various GPCRs belonging to different classes, we demonstrated that constitutive and ligand-induced internalization could be monitored as a function of time and ligand concentration, thus allowing accurate quantitative determination of kinetics of receptor internalization but also half-maximal effective or inhibitory concentrations of compounds. In addition to its selectivity and sensitivity, we provided evidence that DERET-based internalization assay is particularly suitable for characterizing biased ligands. Furthermore, the determination of a Z'-factor value of 0.45 indicates the quality and suitability of DERET-based internalization assay for high-throughput screening (HTS) of compounds that may modulate GPCRs internalization.

  4. Differential requirements of arrestin-3 and clathrin for ligand-dependent and -independent internalization of human G protein-coupled receptor 40.

    Science.gov (United States)

    Qian, Jing; Wu, Chun; Chen, Xiaopan; Li, Xiangmei; Ying, Guoyuan; Jin, Lili; Ma, Qiang; Li, Guo; Shi, Ying; Zhang, Guozheng; Zhou, Naiming

    2014-11-01

    G protein-coupled receptor 40 (GPR40) is believed to be an attractive target to enhance insulin secretion in patients with type 2 diabetes. GPR40 has been found to couple to Gq protein, leading to the activation of phospholipase C and subsequent increases in the intracellular Ca(2+) level. However, the underlying mechanisms that regulate the internalization and desensitization of GPR40 remain to be elucidated. In the present study, a construct of GPR40 fused with enhanced green fluorescent protein (EGFP) at its C-terminus was constructed for direct imaging of the localization and internalization of GPR40 by confocal microscopy. In stably transfected HEK-293 cells, GPR40 receptors underwent rapid agonist-induced internalization and constitutive ligand-independent internalization. Our data demonstrated that the agonist-mediated internalization of GPR40 was significantly blocked by hypertonic sucrose treatment and by siRNA mediated depletion of the heavy chain of clathrin. In contrast, constitutive GPR40 internalization was not affected by hypertonic sucrose or by knock-down of clathrin expression, but it was affected by treatment with methyl-β-cyclodextrin (MβCD) and nystatin. Furthermore, our results using an arrestin-3-EGFP redistribution assay and siRNA-mediated knock-down of arrestin-3 and GRK2 expression revealed that arrestin-3 and GRK2 play an essential role in the regulation of agonist-mediated GPR40 internalization, but are not involved in the regulation of constitutive GPR40 internalization. Additionally, our observation showed that upon activation by agonist, the internalized GPR40 receptors were rapidly recycled back to the plasma membrane via Rab4/Rab5 positive endosomes, whereas the constitutively internalized GPR40 receptors were recycled back to the cell surface through Rab5 positive endosomes. Because FFA receptors exhibit a high level of homology, our observations could be applicable to other members of this family. Copyright © 2014 Elsevier Inc

  5. A broad G protein-coupled receptor internalization assay that combines SNAP-tag labeling, diffusion-enhanced resonance energy transfer, and a highly emissive terbium cryptate acceptor

    Directory of Open Access Journals (Sweden)

    Angélique eLEVOYE

    2015-11-01

    Full Text Available Although G protein-coupled receptor (GPCR internalization has long been considered a major aspect of the desensitization process that tunes ligand responsiveness, internalization is also involved in receptor resensitization and signaling, as well as the ligand scavenging function of some atypical receptors. Internalization thus contributes to the diversity of GPCR-dependent signaling, and its dynamics and quantification in living cells has generated considerable interest. We developed a robust and sensitive assay to follow and quantify ligand-induced and constitutive GPCR internalization but also receptor recycling in living cells. This assay is based on diffusion-enhanced resonance energy transfer (DERET between cell surface GPCRs labeled with a luminescent terbium cryptate donor and a fluorescein acceptor present in the culture medium. GPCR internalization results in a quantifiable reduction of energy transfer. This method yields a high signal-to-noise ratio due to time-resolved measurements. For various GPCRs belonging to different classes, we demonstrated that constitutive and ligand-induced internalization could be monitored as a function of time and ligand concentration, thus allowing accurate quantitative determination of kinetics of receptor internalization but also half-maximal effective or inhibitory concentrations of compounds. In addition to its selectivity and sensitivity, we provided evidence that DERET-based internalization assay is particularly suitable for characterizing biased ligands. Furthermore, the determination of a Z’-factor value of 0.45 indicates the quality and suitability of DERET-based internalization assay for high-throughput screening (HTS of compounds that may modulate GPCRs internalization.

  6. Endocytic collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H.; Jürgensen, Henrik J.; Ingvarsen, Signe Ziir

    2012-01-01

    it crucially important to understand both the collagen synthesis and turnover mechanisms in this condition. Here we show that the endocytic collagen receptor, uPARAP/Endo180, is a major determinant in governing the balance between collagen deposition and degradation. Cirrhotic human livers displayed a marked...... up-regulation of uPARAP/Endo180 in activated fibroblasts and hepatic stellate cells located close to the collagen deposits. In a hepatic stellate cell line, uPARAP/Endo180 was shown to be active in, and required for, the uptake and intracellular degradation of collagen. To evaluate the functional...... groups of mice clearly revealed a fibrosis protective role of uPARAP/Endo180. This effect appeared to directly reflect the activity of the collagen receptor, since no compensatory events were noted when comparing the mRNA expression profiles of the two groups of mice in an array system focused on matrix-degrading...

  7. Receptor-mediated endocytosis of polypeptide hormones is a regulated process: inhibition of [125I]iodoinsulin internalization in hypoinsulinemic diabetes of rat and man

    International Nuclear Information System (INIS)

    Carpentier, J.L.; Robert, A.; Grunberger, G.; van Obberghen, E.; Freychet, P.; Orci, L.; Gorden, P.

    1986-01-01

    Much data suggest that receptor-mediated endocytosis is regulated in states of hormone excess. Thus, in hyperinsulinemic states there is an accelerated loss of cell surface insulin receptors. In the present experiments we addressed this question in hypoinsulinemic states, in which insulin binding to cell surface receptors is generally increased. In hepatocytes obtained from hypoinsulinemic streptozotocin-induced diabetic rats, [ 125 I]iodoglucagon internalization was increased, while at the same time [ 125 I]iodoinsulin internalization was decreased. The defect in [ 125 I]iodoinsulin internalization was corrected by insulin treatment of the animal. In peripheral blood monocytes from patients with type I insulinopenic diabetes, internalization of [ 125 I]iodoinsulin was impaired; this defect was not present in insulin-treated patients. These data in the hypoinsulinemic rat and human diabetes suggest that receptor-mediated endocytosis is regulated in states of insulin deficiency as well as insulin excess. Delayed or reduced internalization of the insulin-receptor complex could amplify the muted signal caused by deficient hormone secretion

  8. Ubiquitylation of an internalized killer cell Ig-like receptor by Triad3A disrupts sustained NF-κB signaling.

    Science.gov (United States)

    Miah, S M Shahjahan; Purdy, Amanda K; Rodin, Nicholas B; MacFarlane, Alexander W; Oshinsky, Jennifer; Alvarez-Arias, Diana A; Campbell, Kerry S

    2011-03-01

    Killer cell Ig-like receptor (KIR) with two Ig-like domains and a long cytoplasmic domain 4 (2DL4; CD158d) is a unique KIR expressed on human NK cells, which stimulates cytokine production, but mechanisms regulating its expression and function are poorly understood. By yeast two-hybrid screening, we identified the E3 ubiquitin ligase, Triad3A, as an interaction partner for the 2DL4 cytoplasmic domain. The protein interaction was confirmed in vivo, and Triad3A expression induced polyubiquitylation and degradation of 2DL4. Overexpression of Triad3A selectively abrogated the cytokine-producing function of 2DL4, whereas Triad3A short hairpin RNA reversed ubiquitylation and restored cytokine production. Expression of Triad3A in an NK cell line did not affect receptor surface expression, internalization, or early signaling, but significantly reduced receptor turnover and suppressed sustained NF-κB activation. 2DL4 endocytosis was found to be vital to stimulate cytokine production, and Triad3A expression diminished localization of internalized receptor in early endosomes. Our results reveal a critical role for endocytosed 2DL4 receptor to generate sustained NF-κB signaling and drive cytokine production. We conclude that Triad3A is a key negative regulator of sustained 2DL4-mediated NF-κB signaling from internalized 2DL4, which functions by promoting ubiquitylation and degradation of endocytosed receptor from early endosomes.

  9. The carboxy-terminal tail or the intracellular loop 3 is required for β-arrestin-dependent internalization of a mammalian type II GnRH receptor.

    Science.gov (United States)

    Madziva, Michael T; Mkhize, Nonhlanhla N; Flanagan, Colleen A; Katz, Arieh A

    2015-08-15

    The type II GnRH receptor (GnRH-R2) in contrast to mammalian type I GnRH receptor (GnRH-R1) has a cytosolic carboxy-terminal tail. We investigated the role of β-arrestin 1 in GnRH-R2-mediated signalling and mapped the regions in GnRH-R2 required for recruitment of β-arrestin, employing internalization assays. We show that GnRH-R2 activation of ERK is dependent on β-arrestin and protein kinase C. Appending the tail of GnRH-R2 to GnRH-R1 enabled GRK- and β-arrestin-dependent internalization of the chimaeric receptor. Surprisingly, carboxy-terminally truncated GnRH-R2 retained β-arrestin and GRK-dependent internalization, suggesting that β-arrestin interacts with additional elements of GnRH-R2. Mutating serine and threonine or basic residues of intracellular loop 3 did not abolish β-arrestin 1-dependent internalization but a receptor lacking these basic residues and the carboxy-terminus showed no β-arrestin 1-dependent internalization. Our results suggest that basic residues at the amino-terminal end of intracellular loop 3 or the carboxy-terminal tail are required for β-arrestin dependent internalization. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. Autoantibody-induced internalization of CNS AQP4 water channel and EAAT2 glutamate transporter requires astrocytic Fc receptor.

    Science.gov (United States)

    Hinson, Shannon R; Clift, Ian C; Luo, Ningling; Kryzer, Thomas J; Lennon, Vanda A

    2017-05-23

    Aquaporin-4 (AQP4) water channel-specific IgG distinguishes neuromyelitis optica (NMO) from multiple sclerosis and causes characteristic immunopathology in which central nervous system (CNS) demyelination is secondary. Early events initiating the pathophysiological outcomes of IgG binding to astrocytic AQP4 are poorly understood. CNS lesions reflect events documented in vitro following IgG interaction with AQP4: AQP4 internalization, attenuated glutamate uptake, intramyelinic edema, interleukin-6 release, complement activation, inflammatory cell recruitment, and demyelination. Here, we demonstrate that AQP4 internalization requires AQP4-bound IgG to engage an astrocytic Fcγ receptor (FcγR). IgG-lacking Fc redistributes AQP4 within the plasma membrane and induces interleukin-6 release. However, AQP4 endocytosis requires an activating FcγR's gamma subunit and involves astrocytic membrane loss of an inhibitory FcγR, CD32B. Interaction of the IgG-AQP4 complex with FcγRs triggers coendocytosis of the excitatory amino acid transporter 2 (EAAT2). Requirement of FcγR engagement for internalization of two astrocytic membrane proteins critical to CNS homeostasis identifies a complement-independent, upstream target for potential early therapeutic intervention in NMO.

  11. Schistosome-derived omega-1 drives Th2 polarization by suppressing protein synthesis following internalization by the mannose receptor

    Science.gov (United States)

    Everts, Bart; Hussaarts, Leonie; Driessen, Nicole N.; Meevissen, Moniek H.J.; Schramm, Gabriele; van der Ham, Alwin J.; van der Hoeven, Barbara; Scholzen, Thomas; Burgdorf, Sven; Mohrs, Markus; Pearce, Edward J.; Hokke, Cornelis H.; Haas, Helmut; Smits, Hermelijn H.

    2012-01-01

    Omega-1, a glycosylated T2 ribonuclease (RNase) secreted by Schistosoma mansoni eggs and abundantly present in soluble egg antigen, has recently been shown to condition dendritic cells (DCs) to prime Th2 responses. However, the molecular mechanisms underlying this effect remain unknown. We show in this study by site-directed mutagenesis of omega-1 that both the glycosylation and the RNase activity are essential to condition DCs for Th2 polarization. Mechanistically, we demonstrate that omega-1 is bound and internalized via its glycans by the mannose receptor (MR) and subsequently impairs protein synthesis by degrading both ribosomal and messenger RNA. These experiments reveal an unrecognized pathway involving MR and interference with protein synthesis that conditions DCs for Th2 priming. PMID:22966004

  12. Effects of the dopamine D2 allosteric modulator, PAOPA, on the expression of GRK2, arrestin-3, ERK1/2, and on receptor internalization.

    Directory of Open Access Journals (Sweden)

    Dipannita Basu

    Full Text Available The activity of G protein-coupled receptors (GPCRs is intricately regulated by a range of intracellular proteins, including G protein-coupled kinases (GRKs and arrestins. Understanding the effects of ligands on these signaling pathways could provide insights into disease pathophysiologies and treatment. The dopamine D2 receptor is a GPCR strongly implicated in the pathophysiology of a range of neurological and neuropsychiatric disorders, particularly schizophrenia. Previous studies from our lab have shown the preclinical efficacy of a novel allosteric drug, 3(R-[(2(S-pyrrolidinylcarbonylamino]-2-oxo-1-pyrrolidineacetamide (PAOPA, in attenuating schizophrenia-like behavioural abnormalities in rodent models of the disease. As an allosteric modulator, PAOPA binds to a site on the D2 receptor, which is distinct from the endogenous ligand-binding site, in order to modulate the binding of the D2 receptor ligand, dopamine. The exact signaling pathways affected by this allosteric modulator are currently unknown. The objectives of this study were to decipher the in vivo effects, in rats, of chronic PAOPA administration on D2 receptor regulatory and downstream molecules, including GRK2, arrestin-3 and extracellular receptor kinase (ERK 1/2. Additionally, an in vitro cellular model was also used to study PAOPA's effects on D2 receptor internalization. Results from western immunoblots showed that chronic PAOPA treatment increased the striatal expression of GRK2 by 41%, arrestin-3 by 34%, phospho-ERK1 by 51% and phospho-ERK2 by 36%. Results also showed that the addition of PAOPA to agonist treatment in cells increased D2 receptor internalization by 33%. This study provides the foundational evidence of putative signaling pathways, and changes in receptor localization, affected by treatment with PAOPA. It improves our understanding on the diverse mechanisms of action of allosteric modulators, while advancing PAOPA's development into a novel drug for the

  13. Interaction with beta-arrestin determines the difference in internalization behavor between beta1- and beta2-adrenergic receptors.

    Science.gov (United States)

    Shiina, T; Kawasaki, A; Nagao, T; Kurose, H

    2000-09-15

    The beta(1)-adrenergic receptor (beta(1)AR) shows the resistance to agonist-induced internalization. As beta-arrestin is important for internalization, we examine the interaction of beta-arrestin with beta(1)AR with three different methods: intracellular trafficking of beta-arrestin, binding of in vitro translated beta-arrestin to intracellular domains of beta(1)- and beta(2)ARs, and inhibition of betaAR-stimulated adenylyl cyclase activities by beta-arrestin. The green fluorescent protein-tagged beta-arrestin 2 translocates to and stays at the plasma membrane by beta(2)AR stimulation. Although green fluorescent protein-tagged beta-arrestin 2 also translocates to the plasma membrane, it returns to the cytoplasm 10-30 min after beta(1)AR stimulation. The binding of in vitro translated beta-arrestin 1 and beta-arrestin 2 to the third intracellular loop and the carboxyl tail of beta(1)AR is lower than that of beta(2)AR. The fusion protein of beta-arrestin 1 with glutathione S-transferase inhibits the beta(1)- and beta(2)AR-stimulated adenylyl cyclase activities, although inhibition of the beta(1)AR-stimulated activity requires a higher concentration of the fusion protein than that of the beta(2)AR-stimulated activity. These results suggest that weak interaction of beta(1)AR with beta-arrestins explains the resistance to agonist-induced internalization. This is further supported by the finding that beta-arrestin can induce internalization of beta(1)AR when beta-arrestin 1 does not dissociate from beta(1)AR by fusing to the carboxyl tail of beta(1)AR.

  14. Single-domain antibodies that compete with the natural ligand fibroblast growth factor block the internalization of the fibroblast growth factor receptor 1

    Energy Technology Data Exchange (ETDEWEB)

    Veggiani, Gianluca; Ossolengo, Giuseppe; Aliprandi, Marisa; Cavallaro, Ugo [IFOM-IEO Campus, Via Adamello 16, 20139 Milano (Italy); Marco, Ario de, E-mail: ario.demarco@ung.si [IFOM-IEO Campus, Via Adamello 16, 20139 Milano (Italy); Dept. Environmental Sciences, University of Nova Gorica (UNG), Vipavska 13, P.O. Box 301-SI-5000, Rozna Dolina, Nova Gorica (Slovenia)

    2011-05-20

    Highlights: {yields} Recombinant antibodies for FGFR1 were isolated from a llama naive library in VHH format. {yields} These antibodies compete with the natural ligand FGF-2 for the same epitope on FGFR1. {yields} The antibody competition inhibits the FGF-2-dependent internalization of FGFR1. -- Abstract: Single-domain antibodies in VHH format specific for fibroblast growth factor receptor 1 (FGFR1) were isolated from a phage-display llama naive library. In particular, phage elution in the presence of the natural receptor ligand fibroblast growth factor (FGF) allowed for the identification of recombinant antibodies that compete with FGF for the same region on the receptor surface. These antibodies posses a relatively low affinity for FGFR1 and were never identified when unspecific elution conditions favoring highly affine binders were applied to panning procedures. Two populations of competitive antibodies were identified that labeled specifically the receptor-expressing cells in immunofluorescence and recognize distinct epitopes. Antibodies from both populations effectively prevented FGF-dependent internalization and nuclear accumulation of the receptor in cultured cells. This achievement indicates that these antibodies have a capacity to modulate the receptor physiology and, therefore, constitute powerful reagents for basic research and a potential lead for therapeutic applications.

  15. Single-domain antibodies that compete with the natural ligand fibroblast growth factor block the internalization of the fibroblast growth factor receptor 1

    International Nuclear Information System (INIS)

    Veggiani, Gianluca; Ossolengo, Giuseppe; Aliprandi, Marisa; Cavallaro, Ugo; Marco, Ario de

    2011-01-01

    Highlights: → Recombinant antibodies for FGFR1 were isolated from a llama naive library in VHH format. → These antibodies compete with the natural ligand FGF-2 for the same epitope on FGFR1. → The antibody competition inhibits the FGF-2-dependent internalization of FGFR1. -- Abstract: Single-domain antibodies in VHH format specific for fibroblast growth factor receptor 1 (FGFR1) were isolated from a phage-display llama naive library. In particular, phage elution in the presence of the natural receptor ligand fibroblast growth factor (FGF) allowed for the identification of recombinant antibodies that compete with FGF for the same region on the receptor surface. These antibodies posses a relatively low affinity for FGFR1 and were never identified when unspecific elution conditions favoring highly affine binders were applied to panning procedures. Two populations of competitive antibodies were identified that labeled specifically the receptor-expressing cells in immunofluorescence and recognize distinct epitopes. Antibodies from both populations effectively prevented FGF-dependent internalization and nuclear accumulation of the receptor in cultured cells. This achievement indicates that these antibodies have a capacity to modulate the receptor physiology and, therefore, constitute powerful reagents for basic research and a potential lead for therapeutic applications.

  16. Human circulating monocytes internalize 125I-insulin in a similar fashion to rat hepatocytes: relevance to receptor regulation in target and nontarget tissues

    International Nuclear Information System (INIS)

    Grunberger, G.; Robert, A.; Carpentier, J.L.; Dayer, J.M.; Roth, A.; Stevenson, H.C.; Orci, L.; Gorden, P.

    1985-01-01

    Circulating monocytes bind 125 I-insulin in a specific fashion and have been used to analyze the ambient receptor status in humans. When freshly isolated circulating monocytes are incubated with 125 I-insulin and examined by electron microscopic autoradiography, approximately 18% of the labeled material is internalized after 15 minutes at 37 degrees C. By 2 hours at 37 degrees C, approximately one half of the 125 I-insulin is internalized. Internalization occurs also at 15 degrees C but at a slower rate. Furthermore, the monocytes bind and internalize 125 I-insulin in a manner that mirrors that of major target tissues, such as rat hepatocytes. These data suggest that the insulin receptor of the circulating monocyte might be regulated by adsorptive endocytosis in a manner analogous to that of target tissue, such as the liver

  17. An Ultra-High Fluorescence Enhancement and High Throughput Assay for Revealing Expression and Internalization of Chemokine Receptor CXCR4.

    Science.gov (United States)

    He, Hua; Wang, Xiaojuan; Cheng, Tiantian; Xia, Yongqing; Lao, Jun; Ge, Baosheng; Ren, Hao; Khan, Naseer Ullah; Huang, Fang

    2016-04-18

    Revealing chemokine receptor CXCR4 expression, distribution, and internalization levels in different cancers helps to evaluate cancer progression or prognosis and to set personalized treatment strategy. We here describe a sensitive and high-throughput immunoassay for determining CXCR4 expression and distribution in cancer cells. The assay is accessible to a wide range of users in an ordinary lab only by dip-coating poly(styrene-co-N-isopropylacrylamide) spheres on the glass substrate. The self- assembled spheres form three-dimensional photonic colloidal crystals which enhance the fluorescence of CF647 and Alexa Fluor 647 by a factor of up to 1000. CXCR4 in cells is detected by using the sandwich immunoassay, where the primary antibody recognizes CXCR4 and the secondary antibody is labeled with CF647. With the newly established assay, we quantified the total expression of CXCR4, its distribution on the cell membrane and cytoplasm, and revealed their internalization level upon SDF-1α activation in various cancer cells, even for those with extremely low expression level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Plasma membrane cholesterol level and agonist-induced internalization of delta-opioid receptors; colocalization study with intracellular membrane markers of Rab family\

    Czech Academy of Sciences Publication Activity Database

    Brejchová, Jana; Vošahlíková, Miroslava; Roubalová, Lenka; Parenti, M.; Mauri, M.; Chernyavskiy, Oleksandr; Svoboda, Petr

    2016-01-01

    Roč. 48, č. 4 (2016), s. 375-396 ISSN 0145-479X R&D Projects: GA ČR(CZ) GAP207/12/0919 Institutional support: RVO:67985823 Keywords : cholesterol * plasma membrane * delta-opioid receptor * internalization * Rab proteins Subject RIV: CE - Biochemistry Impact factor: 2.576, year: 2016

  19. Calcium modulates calmodulin/α-actinin 1 interaction with and agonist-dependent internalization of the adenosine A2A receptor.

    Science.gov (United States)

    Piirainen, Henni; Taura, Jaume; Kursula, Petri; Ciruela, Francisco; Jaakola, Veli-Pekka

    2017-04-01

    Adenosine receptors are G protein-coupled receptors that sense extracellular adenosine to transmit intracellular signals. One of the four adenosine receptor subtypes, the adenosine A 2A receptor (A 2A R), has an exceptionally long intracellular C terminus (A 2A R-ct) that mediates interactions with a large array of proteins, including calmodulin and α-actinin. Here, we aimed to ascertain the α-actinin 1/calmodulin interplay whilst binding to A 2A R and the role of Ca 2+ in this process. First, we studied the A 2A R-α-actinin 1 interaction by means of native polyacrylamide gel electrophoresis, isothermal titration calorimetry, and surface plasmon resonance, using purified recombinant proteins. α-Actinin 1 binds the A 2A R-ct through its distal calmodulin-like domain in a Ca 2+ -independent manner with a dissociation constant of 5-12μM, thus showing an ~100 times lower affinity compared to the A 2A R-calmodulin/Ca 2+ complex. Importantly, calmodulin displaced α-actinin 1 from the A 2A R-ct in a Ca 2+ -dependent fashion, disrupting the A 2A R-α-actinin 1 complex. Finally, we assessed the impact of Ca 2+ on A 2A R internalization in living cells, a function operated by the A 2A R-α-actinin 1 complex. Interestingly, while Ca 2+ influx did not affect constitutive A 2A R endocytosis, it abolished agonist-dependent internalization. In addition, we demonstrated that the A 2A R/α-actinin interaction plays a pivotal role in receptor internalization and function. Overall, our results suggest that the interplay of A 2A R with calmodulin and α-actinin 1 is fine-tuned by Ca 2+ , a fact that might power agonist-mediated receptor internalization and function. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. RGS2 modulates the activity and internalization of dopamine D2 receptors in neuroblastoma N2A cells.

    Science.gov (United States)

    Luessen, Deborah J; Hinshaw, Tyler P; Sun, Haiguo; Howlett, Allyn C; Marrs, Glen; McCool, Brian A; Chen, Rong

    2016-11-01

    Dysregulated expression and function of dopamine D2 receptors (D2Rs) are implicated in drug addiction, Parkinson's disease and schizophrenia. In the current study, we examined whether D2Rs are modulated by regulator of G protein signaling 2 (RGS2), a member of the RGS family that regulates G protein signaling via acceleration of GTPase activity. Using neuroblastoma 2a (N2A) cells, we found that RGS2 was immunoprecipitated by aluminum fluoride-activated Gαi2 proteins. RGS2 siRNA knockdown enhanced membrane [(35)S] GTPγS binding to activated Gαi/o proteins, augmented inhibition of cAMP accumulation and increased ERK phosphorylation in the presence of a D2/D3R agonist quinpirole when compared to scrambled siRNA treatment. These data suggest that RGS2 is a negative modulator of D2R-mediated Gαi/o signaling. Moreover, RGS2 knockdown slightly increased constitutive D2R internalization and markedly abolished quinpirole-induced D2R internalization assessed by immunocytochemistry. RGS2 knockdown did not compromise agonist-induced β-arrestin membrane recruitment; however, it prevents β-arrestin dissociation from the membrane after prolonged quinpirole treatment during which time β-arrestin moved away from the membrane in control cells. Additionally, confocal microscopy analysis of β-arrestin post-endocytic fate revealed that quinpirole treatment caused β-arrestin to translocate to the early and the recycling endosome in a time-dependent manner in control cells whereas translocation of β-arrestin to these endosomes did not occur in RGS2 knockdown cells. The impaired β-arrestin translocation likely contributed to the abolishment of quinpirole-stimulated D2R internalization in RGS2 knockdown cells. Thus, RGS2 is integral for β-arrestin-mediated D2R internalization. The current study revealed a novel regulation of D2R signaling and internalization by RGS2 proteins. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Internalization and desensitization of the human glucose-dependent-insulinotropic receptor is affected by N-terminal acetylation of the agonist.

    Science.gov (United States)

    Ismail, Sadek; Dubois-Vedrenne, Ingrid; Laval, Marie; Tikhonova, Irina G; D'Angelo, Romina; Sanchez, Claire; Clerc, Pascal; Gherardi, Marie-Julie; Gigoux, Véronique; Magnan, Remi; Fourmy, Daniel

    2015-10-15

    How incretins regulate presence of their receptors at the cell surface and their activity is of paramount importance for the development of therapeutic strategies targeting these receptors. We have studied internalization of the human Glucose-Insulinotropic Polypeptide receptor (GIPR). GIP stimulated rapid robust internalization of the GIPR, the major part being directed to lysosomes. GIPR internalization involved mainly clathrin-coated pits, AP-2 and dynamin. However, neither GIPR C-terminal region nor β-arrestin1/2 was required. Finally, N-acetyl-GIP recognized as a dipeptidyl-IV resistant analogue, fully stimulated cAMP production with a ∼15-fold lower potency than GIP and weakly stimulated GIPR internalization and desensitization of cAMP response. Furthermore, docking N-acetyl-GIP in the binding site of modeled GIPR showed slighter interactions with residues of helices 6 and 7 of GIPR compared to GIP. Therefore, incomplete or partial activity of N-acetyl-GIP on signaling involved in GIPR desensitization and internalization contributes to the enhanced incretin activity of this peptide. Copyright © 2015. Published by Elsevier Ireland Ltd.

  2. Preliminary study on the inhibition of nuclear internalization of Tat peptides by conjugation with a receptor-specific peptide and fluorescent dyes

    Science.gov (United States)

    Shen, Duanwen; Liang, Kexiang; Ye, Yunpeng; Tetteh, Elizabeth; Achilefu, Samuel

    2006-02-01

    Numerous studies have shown that basic Tat peptide (48-57) internalized non-specifically in cells and localized in the nucleus. However, localization of imaging agents in cellular nucleus is not desirable because of the potential mutagenesis. When conjugated to the peptides that undergo receptor-mediated endocytosis, Tat peptide could target specific cells or pathologic tissue. We tested this hypothesis by incorporating a somatostatin receptor-avid peptide (octreotate, Oct) and two different fluorescent dyes, Cypate 2 (Cy2) and fluorescein 5'-carboxlic acid (5-FAM), into the Tat-peptide sequence. In addition to the Cy2 or 5-FAM-labeled Oct conjugated to Tat peptide (Tat) to produce Tat-Oct-Cypate2 or Tat-Oct-5-FAM, we also labeled the Tat the Tat peptide with these dyes (Tat-Cy2 and Tat-5-FAM) to serve as positive control. A somatostatin receptor-positive pancreatic tumor cell line, AR42J, was used to assess cell internalization. The results show that Tat-5-FAM and Tat-Cypate2 localized in both nucleus and cytoplasm of the cells. In contrast to Tat-Oct-Cypate2, which localized in both the cytoplasm and nucleus, Tat-Oct-5-FAM internalized in the cytoplasm but not in the nucleus of AR42J cells. The internalizations were inhibited by adding non-labeled corresponding peptides, suggesting that the endocytoses of each group of labeled and the corresponding unlabeled compounds occurred through a common pathway. Thus, fluorescent probes and endocytosis complex between octreotate and somatostatin receptors in cytoplasm could control nuclear internalization of Tat peptides.

  3. Acute inflammation induces segmental, bilateral, supraspinally mediated opioid release in the rat spinal cord, as measured by μ-opioid receptor internalization

    Science.gov (United States)

    Chen, Wenling; Marvizón, Juan Carlos G.

    2009-01-01

    The objective of this study was to measure opioid release in the spinal cord during acute and long-term inflammation using μ-opioid receptor (MOR) internalization. In particular, we determined whether opioid release occurs in the segments receiving the noxious signals or in the entire spinal cord, and whether it involves supraspinal signals. Internalization of neurokinin 1 receptors (NK1Rs) was measured to track the intensity of the noxious stimulus. Rats received peptidase inhibitors intrathecally to protect opioids from degradation. Acute inflammation of the hindpaw with formalin induced moderate MOR internalization in the L5 segment bilaterally, whereas NK1R internalization occurred only ipsilaterally. MOR internalization was restricted to the lumbar spinal cord, regardless of whether the peptidase inhibitors were injected in a lumbar or thoracic site. Formalin-induced MOR internalization was substantially reduced by isoflurane anesthesia. It was also markedly reduced by a lidocaine block of the cervical-thoracic spinal cord (which did not affect the evoked NK1R internalization) indicating that spinal opioid release is mediated supraspinally. In the absence of peptidase inhibitors, formalin and hindpaw clamp induced a small amount of MOR internalization, which was significantly higher than in controls. To study spinal opioid release during chronic inflammation, we injected Complete Freund's Adjuvant (CFA) in the hindpaw and peptidase inhibitors intrathecally. Two days later, no MOR or NK1R internalization was detected. Furthermore, CFA inflammation decreased MOR internalization induced by clamping the inflamed hindpaw. These results show that acute inflammation, but not chronic inflammation, induce segmental opioid release in the spinal cord that involves supraspinal signals. PMID:19298846

  4. Acute inflammation induces segmental, bilateral, supraspinally mediated opioid release in the rat spinal cord, as measured by mu-opioid receptor internalization.

    Science.gov (United States)

    Chen, W; Marvizón, J C G

    2009-06-16

    The objective of this study was to measure opioid release in the spinal cord during acute and long-term inflammation using mu-opioid receptor (MOR) internalization. In particular, we determined whether opioid release occurs in the segments receiving the noxious signals or in the entire spinal cord, and whether it involves supraspinal signals. Internalization of neurokinin 1 receptors (NK1Rs) was measured to track the intensity of the noxious stimulus. Rats received peptidase inhibitors intrathecally to protect opioids from degradation. Acute inflammation of the hind paw with formalin induced moderate MOR internalization in the L5 segment bilaterally, whereas NK1R internalization occurred only ipsilaterally. MOR internalization was restricted to the lumbar spinal cord, regardless of whether the peptidase inhibitors were injected in a lumbar or thoracic site. Formalin-induced MOR internalization was substantially reduced by isoflurane anesthesia. It was also markedly reduced by a lidocaine block of the cervical-thoracic spinal cord (which did not affect the evoked NK1R internalization) indicating that spinal opioid release is mediated supraspinally. In the absence of peptidase inhibitors, formalin and hind paw clamp induced a small amount of MOR internalization, which was significantly higher than in controls. To study spinal opioid release during chronic inflammation, we injected complete Freund's adjuvant (CFA) in the hind paw and peptidase inhibitors intrathecally. Two days later, no MOR or NK1R internalization was detected. Furthermore, CFA inflammation decreased MOR internalization induced by clamping the inflamed hind paw. These results show that acute inflammation, but not chronic inflammation, induces segmental opioid release in the spinal cord that involves supraspinal signals.

  5. Steroid hormone receptors: long- and short-term integrators of the internal milieu and the external environment.

    Science.gov (United States)

    Blaustein, J D

    2012-07-01

    Many of the influences of estrogens and progestins on the brain and behavior are mediated by estrogen receptors and progestin receptors, acting as transcriptional regulators. The homologous and heterologous regulation of the concentrations of these receptors by cognate hormones is well established. However, although they were discovered and characterized based on their binding to cognate hormone and their role in transcriptional regulation, steroid hormone receptors have a more complex role and serve many more functions than originally suspected. First, besides being regulated by steroid hormones, the intracellular concentrations of brain steroid hormone receptors are regulated by neurotransmitters, a pathway by which stimuli from the environment, including from conspecific animals, can modulate the concentration of particular steroid hormone receptors in subsets of cells. Further, besides being activated by cognate steroid hormones, the receptors can be activated by a variety of neurotransmitters and phosphorylation pathways, providing a route through which environmental stimulation can activate steroid-receptor-dependent functions in specific cells. In addition, the transcription factor, estrogen receptor-α, produced from the estrogen receptor-α gene, can be modified to be targeted to membranes, where it can signal via kinase pathways. Finally, developmental experiences, such as particular stressors during the pubertal period, can permanently remodel the brain's response to ovarian hormones, most likely by long-term changes in regulation of the receptors mediating those responses. In addition to their function in responding to cognate ligand, it is now more appropriate to think of steroid hormone receptors as integrators of a wide variety of signaling pathways. © Georg Thieme Verlag KG Stuttgart · New York.

  6. Eps15 is recruited to the plasma membrane upon epidermal growth factor receptor activation and localizes to components of the endocytic pathway during receptor internalization

    DEFF Research Database (Denmark)

    Torrisi, M R; Lotti, L V; Belleudi, F

    1999-01-01

    Eps15 is a substrate for the tyrosine kinase of the epidermal growth factor receptor (EGFR) and is characterized by the presence of a novel protein:protein interaction domain, the EH domain. Eps15 also stably binds the clathrin adaptor protein complex AP-2. Previous work demonstrated an essential...

  7. Follicle-stimulating hormone (FSH) activates extracellular signal-regulated kinase phosphorylation independently of beta-arrestin- and dynamin-mediated FSH receptor internalization

    Science.gov (United States)

    Piketty, Vincent; Kara, Elodie; Guillou, Florian; Reiter, Eric; Crepieux, Pascale

    2006-01-01

    Background The follicle-stimulating hormone receptor (FSH-R) is a seven transmembrane spanning receptor (7TMR) which plays a crucial role in male and female reproduction. Upon FSH stimulation, the FSH-R activates the extracellular signal-regulated kinases (ERK). However, the mechanisms whereby the agonist-stimulated FSH-R activates ERK are poorly understood. In order to activate ERK, some 7 TMRs require beta-arrestin-and dynamin-dependent internalization to occur, whereas some others do not. In the present study, we examined the ability of the FSH-activated FSH-R to induce ERK phosphorylation, in conditions where its beta-arrestin- and dynamin-mediated internalization was impaired. Methods Human embryonic kidney (HEK) 293 cells were transiently transfected with the rat FSH-R. Internalization of the FSH-R was manipulated by co-expression of either a beta-arrestin (319–418) dominant negative peptide, either an inactive dynamin K44A mutant or of wild-type beta-arrestin 1 or 2. The outcomes on the FSH-R internalization were assayed by measuring 125I-FSH binding at the cell surface when compared to internalized 125I-FSH binding. The resulting ERK phosphorylation level was visualized by Western blot analysis. Results In HEK 293 cells, FSH stimulated ERK phosphorylation in a dose-dependent manner. Co-transfection of the beta- arrestin (319–418) construct, or of the dynamin K44A mutant reduced FSH-R internalization in response to FSH, without affecting ERK phosphorylation. Likewise, overexpression of wild-type beta-arrestin 1 or 2 significantly increased the FSH-R internalization level in response to FSH, without altering FSH-induced ERK phosphorylation. Conclusion From these results, we conclude that the FSH-R does not require beta-arrestin- nor dynamin-mediated internalization to initiate ERK phosphorylation in response to FSH. PMID:16787538

  8. Aberrant Receptor Internalization and Enhanced FRS2-dependent Signaling Contribute to the Transforming Activity of the Fibroblast Growth Factor Receptor 2 IIIb C3 Isoform*

    OpenAIRE

    Cha, Jiyoung Y.; Maddileti, Savitri; Mitin, Natalia; Harden, T. Kendall; Der, Channing J.

    2009-01-01

    Alternative splice variants of fibroblast growth factor receptor 2 (FGFR2) IIIb, designated C1, C2, and C3, possess progressive reduction in their cytoplasmic carboxyl termini (822, 788, and 769 residues, respectively), with preferential expression of the C2 and C3 isoforms in human cancers. We determined that the progressive deletion of carboxyl-terminal sequences correlated with increasing transforming potency. The highly transforming C3 variant lacks five tyrosine r...

  9. Mitogen-activated protein kinase signaling pathways promote low-density lipoprotein receptor-related protein 1-mediated internalization of beta-amyloid protein in primary cortical neurons.

    Science.gov (United States)

    Yang, Wei-Na; Ma, Kai-Ge; Qian, Yi-Hua; Zhang, Jian-Shui; Feng, Gai-Feng; Shi, Li-Li; Zhang, Zhi-Chao; Liu, Zhao-Hui

    2015-07-01

    Mounting evidence suggests that the pathological hallmarks of Alzheimer's disease (AD) are caused by the intraneuronal accumulation of beta-amyloid protein (Aβ). Reuptake of extracellular Aβ is believed to contribute significantly to the intraneuronal Aβ pool in the early stages of AD. Published reports have claimed that the low-density lipoprotein receptor-related protein 1 (LRP1) mediates Aβ1-42 uptake and lysosomal trafficking in GT1-7 neuronal cells and mouse embryonic fibroblast non-neuronal cells. However, there is no direct evidence supporting the role of LRP1 in Aβ internalization in primary neurons. Our recent study indicated that p38 MAPK and ERK1/2 signaling pathways are involved in regulating α7 nicotinic acetylcholine receptor (α7nAChR)-mediated Aβ1-42 uptake in SH-SY5Y cells. This study was designed to explore the regulation of MAPK signaling pathways on LRP1-mediated Aβ internalization in neurons. We found that extracellular Aβ1-42 oligomers could be internalized into endosomes/lysosomes and mitochondria in cortical neurons. Aβ1-42 and LRP1 were also found co-localized in neurons during Aβ1-42 internalization, and they could form Aβ1-42-LRP1 complex. Knockdown of LRP1 expression significantly decreased neuronal Aβ1-42 internalization. Finally, we identified that p38 MAPK and ERK1/2 signaling pathways regulated the internalization of Aβ1-42 via LRP1. Therefore, these results demonstrated that LRP1, p38 MAPK and ERK1/2 mediated the internalization of Aβ1-42 in neurons and provided evidence that blockade of LRP1 or inhibitions of MAPK signaling pathways might be a potential approach to lowering brain Aβ levels and served a potential therapeutic target for AD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Lipopolysaccharide (LPS)-binding protein stimulates CD14-dependent Toll-like receptor 4 internalization and LPS-induced TBK1-IKKϵ-IRF3 axis activation.

    Science.gov (United States)

    Tsukamoto, Hiroki; Takeuchi, Shino; Kubota, Kanae; Kobayashi, Yohei; Kozakai, Sao; Ukai, Ippo; Shichiku, Ayumi; Okubo, Misaki; Numasaki, Muneo; Kanemitsu, Yoshitomi; Matsumoto, Yotaro; Nochi, Tomonori; Watanabe, Kouichi; Aso, Hisashi; Tomioka, Yoshihisa

    2018-05-14

    Toll-like receptor 4 (TLR4) is an indispensable immune receptor for lipopolysaccharide (LPS), a major component of the Gram-negative bacterial cell wall. Following LPS stimulation, TLR4 transmits the signal from the cell surface and becomes internalized in an endosome. However, the spatial regulation of TLR4 signaling is not fully understood. Here, we investigated the mechanisms of LPS-induced TLR4 internalization and clarified the roles of the extracellular LPS-binding molecules, LPS-binding protein (LBP), and glycerophosphatidylinositol-anchored protein (CD14). LPS stimulation of CD14-expressing cells induced TLR4 internalization in the presence of serum, and an inhibitory anti-LBP mAb blocked its internalization. Addition of LBP to serum-free cultures restored LPS-induced TLR4 internalization to comparable levels of serum. The secretory form of the CD14 (sCD14) induced internalization but required a much higher concentration than LBP. An inhibitory anti-sCD14 mAb was ineffective for serum-mediated internalization. LBP lacking the domain for LPS transfer to CD14 and a CD14 mutant with reduced LPS binding both attenuated TLR4 internalization. Accordingly, LBP is an essential serum molecule for TLR4 internalization, and its LPS transfer to membrane-anchored CD14 (mCD14) is a prerequisite. LBP induced the LPS-stimulated phosphorylation of TBK1, IKKϵ, and IRF3, leading to IFN-β expression. However, LPS-stimulated late activation of NFκB or necroptosis were not affected. Collectively, our results indicate that LBP controls LPS-induced TLR4 internalization, which induces TLR adaptor molecule 1 (TRIF)-dependent activation of the TBK1-IKKϵ-IRF3-IFN-β pathway. In summary, we showed that LBP-mediated LPS transfer to mCD14 is required for serum-dependent TLR4 internalization and activation of the TRIF pathway. Copyright © 2018, The American Society for Biochemistry and Molecular Biology.

  11. HER2 monoclonal antibodies that do not interfere with receptor heterodimerization-mediated signaling induce effective internalization and represent valuable components for rational antibody-drug conjugate design.

    Science.gov (United States)

    de Goeij, Bart E C G; Peipp, Matthias; de Haij, Simone; van den Brink, Edward N; Kellner, Christian; Riedl, Thilo; de Jong, Rob; Vink, Tom; Strumane, Kristin; Bleeker, Wim K; Parren, Paul W H I

    2014-01-01

    The human epidermal growth factor receptor (HER)2 provides an excellent target for selective delivery of cytotoxic drugs to tumor cells by antibody-drug conjugates (ADC) as has been clinically validated by ado-trastuzumab emtansine (Kadcyla(TM)). While selecting a suitable antibody for an ADC approach often takes specificity and efficient antibody-target complex internalization into account, the characteristics of the optimal antibody candidate remain poorly understood. We studied a large panel of human HER2 antibodies to identify the characteristics that make them most suitable for an ADC approach. As a model toxin, amenable to in vitro high-throughput screening, we employed Pseudomonas exotoxin A (ETA') fused to an anti-kappa light chain domain antibody. Cytotoxicity induced by HER2 antibodies, which were thus non-covalently linked to ETA', was assessed for high and low HER2 expressing tumor cell lines and correlated with internalization and downmodulation of HER2 antibody-target complexes. Our results demonstrate that HER2 antibodies that do not inhibit heterodimerization of HER2 with related ErbB receptors internalize more efficiently and show greater ETA'-mediated cytotoxicity than antibodies that do inhibit such heterodimerization. Moreover, stimulation with ErbB ligand significantly enhanced ADC-mediated tumor kill by antibodies that do not inhibit HER2 heterodimerization. This suggests that the formation of HER2/ErbB-heterodimers enhances ADC internalization and subsequent killing of tumor cells. Our study indicates that selecting HER2 ADCs that allow piggybacking of HER2 onto other ErbB receptors provides an attractive strategy for increasing ADC delivery and tumor cell killing capacity to both high and low HER2 expressing tumor cells.

  12. Pituitary adenylate cyclase 1 receptor internalization and endosomal signaling mediate the pituitary adenylate cyclase activating polypeptide-induced increase in guinea pig cardiac neuron excitability.

    Science.gov (United States)

    Merriam, Laura A; Baran, Caitlin N; Girard, Beatrice M; Hardwick, Jean C; May, Victor; Parsons, Rodney L

    2013-03-06

    After G-protein-coupled receptor activation and signaling at the plasma membrane, the receptor complex is often rapidly internalized via endocytic vesicles for trafficking into various intracellular compartments and pathways. The formation of signaling endosomes is recognized as a mechanism that produces sustained intracellular signals that may be distinct from those generated at the cell surface for cellular responses including growth, differentiation, and survival. Pituitary adenylate cyclase activating polypeptide (PACAP; Adcyap1) is a potent neurotransmitter/neurotrophic peptide and mediates its diverse cellular functions in part through internalization of its cognate G-protein-coupled PAC1 receptor (PAC1R; Adcyap1r1). In the present study, we examined whether PAC1R endocytosis participates in the regulation of neuronal excitability. Although PACAP increased excitability in 90% of guinea pig cardiac neurons, pretreatment with Pitstop 2 or dynasore to inhibit clathrin and dynamin I/II, respectively, suppressed the PACAP effect. Subsequent addition of inhibitor after the PACAP-induced increase in excitability developed gradually attenuated excitability with no changes in action potential properties. Likewise, the PACAP-induced increase in excitability was markedly decreased at ambient temperature. Receptor trafficking studies with GFP-PAC1 cell lines demonstrated the efficacy of Pitstop 2, dynasore, and low temperatures at suppressing PAC1R endocytosis. In contrast, brefeldin A pretreatments to disrupt Golgi vesicle trafficking did not blunt the PACAP effect, and PACAP/PAC1R signaling still increased neuronal cAMP production even with endocytic blockade. Our results demonstrate that PACAP/PAC1R complex endocytosis is a key step for the PACAP modulation of cardiac neuron excitability.

  13. Plasma membrane cholesterol level and agonist-induced internalization of δ-opioid receptors; colocalization study with intracellular membrane markers of Rab family.

    Science.gov (United States)

    Brejchova, Jana; Vosahlikova, Miroslava; Roubalova, Lenka; Parenti, Marco; Mauri, Mario; Chernyavskiy, Oleksandr; Svoboda, Petr

    2016-08-01

    Decrease of cholesterol level in plasma membrane of living HEK293 cells transiently expressing FLAG-δ-OR by β-cyclodextrin (β-CDX) resulted in a slight internalization of δ-OR. Massive internalization of δ-OR induced by specific agonist DADLE was diminished in cholesterol-depleted cells. These results suggest that agonist-induced internalization of δ-OR, which has been traditionally attributed exclusively to clathrin-mediated pathway, proceeds at least partially via membrane domains. Identification of internalized pools of FLAG-δ-OR by colocalization studies with proteins of Rab family indicated the decreased presence of receptors in early endosomes (Rab5), late endosomes and lysosomes (Rab7) and fast recycling vesicles (Rab4). Slow type of recycling (Rab11) was unchanged by cholesterol depletion. As expected, agonist-induced internalization of oxytocin receptors was totally suppressed in β-CDX-treated cells. Determination of average fluorescence lifetime of TMA-DPH, the polar derivative of hydrophobic membrane probe diphenylhexatriene, in live cells by FLIM indicated a significant alteration of the overall PM structure which may be interpreted as an increased "water-accessible space" within PM area. Data obtained by studies of HEK293 cells transiently expressing FLAG-δ-OR by "antibody feeding" method were extended by analysis of the effect of cholesterol depletion on distribution of FLAG-δ-OR in sucrose density gradients prepared from HEK293 cells stably expressing FLAG-δ-OR. Major part of FLAG-δ-OR was co-localized with plasma membrane marker Na,K-ATPase and β-CDX treatment resulted in shift of PM fragments containing both FLAG-δ-OR and Na,K-ATPase to higher density. Thus, the decrease in content of the major lipid constituent of PM resulted in increased density of resulting PM fragments.

  14. Ligand-induced tyrosine phosphorylation of cysteinyl leukotriene receptor 1 triggers internalization and signaling in intestinal epithelial cells

    DEFF Research Database (Denmark)

    Parhamifar, Ladan; Sime, Wondossen; Yudina, Yuliana

    2010-01-01

    Leukotriene D(4) (LTD(4)) belongs to the bioactive lipid group known as eicosanoids and has implications in pathological processes such as inflammation and cancer. Leukotriene D(4) exerts its effects mainly through two different G-protein-coupled receptors, CysLT(1) and CysLT(2). The high affinit...

  15. PAF-receptor is preferentially expressed in a distinct synthetic phenotype of smooth muscle cells cloned from human internal thoracic artery: Functional implications in cell migration

    International Nuclear Information System (INIS)

    Stengel, Dominique; O'Neil, Caroline; Brocheriou, Isabelle; Karabina, Sonia-Athina; Durand, Herve; Caplice, Noel M.; Pickering, J. Geoffrey; Ninio, Ewa

    2006-01-01

    Platelet-activating-Factor (PAF) and its structural analogues formed upon low density lipoprotein oxidation are involved in atherosclerotic plaque formation and may signal through PAF-receptor (PAF-R) expressed in human macrophages and in certain smooth muscle cells (SMCs) in the media, but rarely in the intima of human plaques. Our aim was to determine which SMC phenotype expresses PAF-R and whether this receptor is functional in cell migration. Circulating SMC progenitors and two phenotypically distinct clones of proliferative, epithelioid phenotype vs contractile, spindle-shaped SMCs from the media of adult internal thoracic artery were studied for the presence of PAF-receptor (PAF-R). The levels of specific mRNA were obtained by reverse transcription/real-time PCR, the protein expression was deduced from immunohistochemistry staining, and the functional transmigration assay was performed by Boyden chamber-type chemotaxis assay. Only SMCs of spindle-shape and synthetic phenotype expressed both mRNA and PAF-R protein and in the functional test migrated at low concentrations of PAF. Two unrelated, specific PAF-R antagonists inhibited PAF-induced migration, but did not modify the migration initiated by PDGF. The presence of functional PAF-R in arterial spindle-shaped SMCs of synthetic phenotype may be important for their migration from the media into the intima and atherosclerotic plaques formation

  16. Internalization and Recycling of the HER2 Receptor on Human Breast Adenocarcinoma Cells Treated with Targeted Phototoxic Protein DARPinminiSOG

    Science.gov (United States)

    Shilova, O. N.; Proshkina, G. M.; Lebedenko, E. N.; Deyev, S. M.

    2015-01-01

    Design and evaluation of new high-affinity protein compounds that can selectively and efficiently destroy human cancer cells are a priority research area in biomedicine. In this study we report on the ability of the recombinant phototoxic protein DARPin-miniSOG to interact with breast adenacarcinoma human cells overexpressing the extracellular domain of human epidermal growth factor receptor 2 (HER2). It was found that the targeted phototoxin DARPin-miniSOG specifically binds to the HER2 with following internalization and slow recycling back to the cell membrane. An insight into the role of DARPin-miniSOG in HER2 internalization could contribute to the treatment of HER2-positive cancer using this phototoxic protein. PMID:26483969

  17. Focal adhesion kinase-mediated activation of glycogen synthase kinase 3β regulates IL-33 receptor internalization and IL-33 signaling.

    Science.gov (United States)

    Zhao, Jing; Wei, Jianxin; Bowser, Rachel K; Traister, Russell S; Fan, Ming-Hui; Zhao, Yutong

    2015-01-15

    IL-33, a relatively new member of the IL-1 cytokine family, plays a crucial role in allergic inflammation and acute lung injury. Long form ST2 (ST2L), the receptor for IL-33, is expressed on immune effector cells and lung epithelia and plays a critical role in triggering inflammation. We have previously shown that ST2L stability is regulated by the ubiquitin-proteasome system; however, its upstream internalization has not been studied. In this study, we demonstrate that glycogen synthase kinase 3β (GSK3β) regulates ST2L internalization and IL-33 signaling. IL-33 treatment induced ST2L internalization, and an effect was attenuated by inhibition or downregulation of GSK3β. GSK3β was found to interact with ST2L on serine residue 446 in response to IL-33 treatment. GSK3β binding site mutant (ST2L(S446A)) and phosphorylation site mutant (ST2L(S442A)) are resistant to IL-33-induced ST2L internalization. We also found that IL-33 activated focal adhesion kinase (FAK). Inhibition of FAK impaired IL-33-induced GSK3β activation and ST2L internalization. Furthermore, inhibition of ST2L internalization enhanced IL-33-induced cytokine release in lung epithelial cells. These results suggest that modulation of the ST2L internalization by FAK/GSK3β might serve as a unique strategy to lessen pulmonary inflammation. Copyright © 2015 by The American Association of Immunologists, Inc.

  18. B Cell Receptor-Mediated Internalization of Salmonella: A Novel Pathway for Autonomous B Cell Activation and Antibody Production

    NARCIS (Netherlands)

    Souwer, Yuri; Griekspoor, Alexander; Jorritsma, Tineke; de Wit, Jelle; Janssen, Hans; Neefjes, Jacques; van Ham, S. Marieke

    2009-01-01

    The present paradigm is that primary B cells are nonphagocytosing cells. In this study, we demonstrate that human primary B cells are able to internalize bacteria when the bacteria are recognized by the BCR. BCR-mediated internalization of Salmonella typhimurium results in B cell differentiation and

  19. Provision of a simplified methodology for determining estradiol and progesterone receptors in human breast tumours. Internal and external quality control

    International Nuclear Information System (INIS)

    Farinate, Z.

    1990-10-01

    A simplified assay for the detection of progesterone receptors (PR) in human breast tissue is described. Tissue storage is at -20 deg. C rather than -70 deg. C and a centrifugation speed of 20,000 rpm avoids requirement of an ultracentrifuge. Cytosol preparations obtained from homogenized oestradiol benzoate primed wistar rat uteri performed satisfactorily as positive controls with stability of two months in liquid nitrogen. The use of iodinated tracer (progesterone 11 alpha glucuronide 125 I iodotyramine) proved disappointing in the progesterone receptor assay in contrast to 125 I oestradiol which worked well in a oestrogen receptor assay, previously developed. Hydroxyl-apatite was a better separating agent than dextran coated charcoal in both assays and yielded better sensitivity, particularly when protein concentrations were low. Five breast cancer specimens assayed yielded, by Scatchard analysis, Kd values between 12 to 22x10 -9 m|h, comparable to the positive controls. However, two of these had binding site capacity of less than 5 fmol/mg cytosol as compared to the three others and the positive controls where values ranged from 47-196 fmol/mg cytosol. 28 refs, 6 figs, 14 tabs

  20. International

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    This rubric reports on 10 short notes about international economical facts about nuclear power: Electricite de France (EdF) and its assistance and management contracts with Eastern Europe countries (Poland, Hungary, Bulgaria); Transnuclear Inc. company (a 100% Cogema daughter company) acquired the US Vectra Technologies company; the construction of the Khumo nuclear power plant in Northern Korea plays in favour of the reconciliation between Northern and Southern Korea; the delivery of two VVER 1000 Russian reactors to China; the enforcement of the cooperation agreement between Euratom and Argentina; Japan requested for the financing of a Russian fast breeder reactor; Russia has planned to sell a floating barge-type nuclear power plant to Indonesia; the control of the Swedish reactor vessels of Sydkraft AB company committed to Tractebel (Belgium); the renewal of the nuclear cooperation agreement between Swiss and USA; the call for bids from the Turkish TEAS electric power company for the building of the Akkuyu nuclear power plant answered by three candidates: Atomic Energy of Canada Limited (AECL), Westinghouse (US) and the French-German NPI company. (J.S.)

  1. Artesunate Reduces Serum Lipopolysaccharide in Cecal Ligation/Puncture Mice via Enhanced LPS Internalization by Macrophages through Increased mRNA Expression of Scavenger Receptors

    Directory of Open Access Journals (Sweden)

    Bin Li

    2014-01-01

    Full Text Available Innate immunity is the first line of defense in human beings against pathogen infection; monocytes/macrophages are the primary cells of the innate immune system. Recently, macrophages/monocytes have been discovered to participate in LPS clearance, and the clearance efficiency determines the magnitude of the inflammatory response and subsequent organ injury. Previously, we reported that artesunate (AS protected sepsis mice against heat-killed E. coli challenge. Herein, we further confirmed that AS protected cecal ligation/puncture (CLP sepsis mice. Its protection on sepsis mice was related to not only reduction of pro-inflammatory cytokines and serum LPS levels but also improvement of liver function. Based on the fact that AS did not directly bind and neutralize LPS, we hypothesized that the reduction of serum LPS level might be related to enhancement of LPS internalization and subsequent detoxification. Our results showed that AS increased FITC-LPS internalization by peritoneal macrophage and liver Kupffer cell, but enhancement of LPS internalization by AS was not related to the clathrin-dependent pathway. However, AS induced mRNA expression of important scavenger receptors (SRs; SR-A and MARCO mRNA expression was upregulated, suggesting that AS enhancement of LPS internalization and inhibition of pro-inflammatory cytokines was related to changes in mRNA expression of SRs.

  2. The p38 mitogen activated protein kinase regulates β-amyloid protein internalization through the α7 nicotinic acetylcholine receptor in mouse brain.

    Science.gov (United States)

    Ma, Kai-Ge; Lv, Jia; Yang, Wei-Na; Chang, Ke-Wei; Hu, Xiao-Dan; Shi, Li-Li; Zhai, Wan-Ying; Zong, Hang-Fan; Qian, Yi-Hua

    2018-03-01

    Alzheimer's disease (AD) is one of the most devastating neurodegenerative disorders. Intracellular β-amyloid protein (Aβ) is an early event in AD. It induces the formation of amyloid plaques and neuron damage. The α7 nicotinic acetylcholine receptor (α7nAChR) has been suggested to play an important role in Aβ caused cognition. It has high affinity with Aβ and could mediate Aβ internalization in vitro. However, whether in mouse brain the p38 MAPK signaling pathway is involved in the regulation of the α7nAChR mediated Aβ internalization and their role in mitochondria remains little known. Therefore, in this study, we revealed that Aβ is internalized by cholinergic and GABAergic neurons. The internalized Aβ were found deposits in lysosomes/endosomes and mitochondria. Aβ could form Aβ-α7nAChR complex with α7nAChR, activates the p38 mitogen activated protein kinase (MAPK). And the increasing of α7nAChR could in return mediate Aβ internalization in the cortex and hippocampus. In addition, by using the α7nAChR agonist PNU282987, the p38 phosphorylation level decreases, rescues the biochemical changes which are tightly associated with Aβ-induced apoptosis, such as Bcl2/Bax level, cytochrome c (Cyt c) release. Collectively, the p38 MAPK signaling pathway could regulate the α7nAChR-mediated internalization of Aβ. The activation of α7nAChR or the inhibition of p38 MAPK signaling pathway may be a beneficial therapy to AD. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Serotonin Receptors in the Medulla Oblongata of the Human Fetus and Infant: The Analytic Approach of the International Safe Passage Study

    Science.gov (United States)

    Folkerth, Rebecca D.; Paterson, David S.; Broadbelt, Kevin G.; Dan Zaharie, S.; Hewlett, Richard H.; Dempers, Johan J.; Burger, Elsie; Wadee, Shabbir; Schubert, Pawel; Wright, Colleen; Sens, Mary Ann; Nelsen, Laura; Randall, Bradley B.; Tran, Hoa; Geldenhuys, Elaine; Elliott, Amy J.; Odendaal, Hein J.; Kinney, Hannah C.

    2016-01-01

    The Safe Passage Study is an international, prospective study of approximately 12 000 pregnancies to determine the effects of prenatal alcohol exposure (PAE) upon stillbirth and the sudden infant death syndrome (SIDS). A key objective of the study is to elucidate adverse effects of PAE upon binding to serotonin (5-HT) 1A receptors in brainstem homeostatic networks postulated to be abnormal in unexplained stillbirth and/or SIDS. We undertook a feasibility assessment of 5-HT1A receptor binding using autoradiography in the medulla oblongata (6 nuclei in 27 cases). 5-HT1A binding was compared to a reference dataset from the San Diego medical examiner’s system. There was no adverse effect of postmortem interval ≤100 h. The distribution and quantitated values of 5-HT1A binding in Safe Passage Study cases were essentially identical to those in the reference dataset, and virtually identical between stillbirths and live born fetal cases in grossly non-macerated tissues. The pattern of binding was present at mid-gestation with dramatic changes in binding levels in the medullary 5-HT nuclei over the second half of gestation; there was a plateau at lower levels in the neonatal period and into infancy. This study demonstrates feasibility of 5-HT1A binding analysis in the medulla in the Safe Passage Study. PMID:27634962

  4. Role of the Fc gamma receptor IIA polymorphism in the antiphospholipid syndrome - an international meta-analysis

    NARCIS (Netherlands)

    Karassa, FB; Bijl, M; Davies, KA; Kallenberg, CGM; Khamashta, MA; Manger, K; Michel, M; Piette, JC; Salmon, JE; Song, YW; Tsuchiya, N; Yoo, DH; Ioannidis, JPA

    Objective. To assess the impact of the FcgammaRIIA-R/H131 polymorphism on the risk for antiphospholipid syndrome (APS), both primary and secondary to systemic lupus erythematosus (SLE). Methods. This international meta-analysis combined data from 9 research teams. FcgammaRIIA-R/H131 genotypes were

  5. Trastuzumab beyond progression in human epidermal growth factor receptor 2-positive advanced breast cancer: a german breast group 26/breast international group 03-05 study

    DEFF Research Database (Denmark)

    von Minckwitz, Gunter; du Bois, Andreas; Schmidt, Marcus

    2009-01-01

    PURPOSE: Trastuzumab shows clinical activity in human epidermal growth factor receptor 2 (HER-2)-positive early and advanced breast cancer. In the German Breast Group 26/Breast International Group 03-05 trial, we investigated if trastuzumab treatment should be continued beyond progression. METHODS......: Patients with HER-2-positive breast cancer that progresses during treatment with trastuzumab were randomly assigned to receive capecitabine (2,500 mg/m(2) body-surface area on days 1 through 14 [1,250 mg/m(2) semi-daily]) alone or with continuation of trastuzumab (6 mg/kg body weight) in 3-week cycles....... The primary end point was time to progression. RESULTS: We randomly assigned 78 patients to capecitabine and 78 patients to capecitabine plus trastuzumab. Sixty-five events and 38 deaths in the capecitabine group and 62 events and 33 deaths in the capecitabine-plus-trastuzumab group occurred during 15...

  6. Roles of Fragile X Mental Retardation Protein in Dopaminergic Stimulation-induced Synapse-associated Protein Synthesis and Subsequent α-Amino-3-hydroxyl-5-methyl-4-isoxazole-4-propionate (AMPA) Receptor Internalization*

    Science.gov (United States)

    Wang, Hansen; Kim, Susan S.; Zhuo, Min

    2010-01-01

    Fragile X syndrome, the most common form of inherited mental retardation, is caused by the absence of the RNA-binding protein fragile X mental retardation protein (FMRP). FMRP regulates local protein synthesis in dendritic spines. Dopamine (DA) is involved in the modulation of synaptic plasticity. Activation of DA receptors can regulate higher brain functions in a protein synthesis-dependent manner. Our recent study has shown that FMRP acts as a key messenger for DA modulation in forebrain neurons. Here, we demonstrate that FMRP is critical for DA D1 receptor-mediated synthesis of synapse-associated protein 90/PSD-95-associated protein 3 (SAPAP3) in the prefrontal cortex (PFC). DA D1 receptor stimulation induced dynamic changes of FMRP phosphorylation. The changes in FMRP phosphorylation temporally correspond with the expression of SAPAP3 after D1 receptor stimulation. Protein phosphatase 2A, ribosomal protein S6 kinase, and mammalian target of rapamycin are the key signaling molecules for FMRP linking DA D1 receptors to SAPAP3. Knockdown of SAPAP3 did not affect surface expression of α-amino-3-hydroxyl-5-methyl-4-isoxazole-4-propionate (AMPA) GluR1 receptors induced by D1 receptor activation but impaired their subsequent internalization in cultured PFC neurons; the subsequent internalization of GluR1 was also impaired in Fmr1 knock-out PFC neurons, suggesting that FMRP may be involved in subsequent internalization of GluR1 through regulating the abundance of SAPAP3 after DA D1 receptor stimulation. Our study thus provides further insights into FMRP involvement in DA modulation and may help to reveal the molecular mechanisms underlying impaired learning and memory in fragile X syndrome. PMID:20457613

  7. Roles of fragile X mental retardation protein in dopaminergic stimulation-induced synapse-associated protein synthesis and subsequent alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-4-propionate (AMPA) receptor internalization.

    Science.gov (United States)

    Wang, Hansen; Kim, Susan S; Zhuo, Min

    2010-07-09

    Fragile X syndrome, the most common form of inherited mental retardation, is caused by the absence of the RNA-binding protein fragile X mental retardation protein (FMRP). FMRP regulates local protein synthesis in dendritic spines. Dopamine (DA) is involved in the modulation of synaptic plasticity. Activation of DA receptors can regulate higher brain functions in a protein synthesis-dependent manner. Our recent study has shown that FMRP acts as a key messenger for DA modulation in forebrain neurons. Here, we demonstrate that FMRP is critical for DA D1 receptor-mediated synthesis of synapse-associated protein 90/PSD-95-associated protein 3 (SAPAP3) in the prefrontal cortex (PFC). DA D1 receptor stimulation induced dynamic changes of FMRP phosphorylation. The changes in FMRP phosphorylation temporally correspond with the expression of SAPAP3 after D1 receptor stimulation. Protein phosphatase 2A, ribosomal protein S6 kinase, and mammalian target of rapamycin are the key signaling molecules for FMRP linking DA D1 receptors to SAPAP3. Knockdown of SAPAP3 did not affect surface expression of alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-4-propionate (AMPA) GluR1 receptors induced by D1 receptor activation but impaired their subsequent internalization in cultured PFC neurons; the subsequent internalization of GluR1 was also impaired in Fmr1 knock-out PFC neurons, suggesting that FMRP may be involved in subsequent internalization of GluR1 through regulating the abundance of SAPAP3 after DA D1 receptor stimulation. Our study thus provides further insights into FMRP involvement in DA modulation and may help to reveal the molecular mechanisms underlying impaired learning and memory in fragile X syndrome.

  8. Sphingosine-1-phosphate receptors: Zooming in on ligand-induced intracellular trafficking and its functional implications

    NARCIS (Netherlands)

    Verzijl, Dennis; Peters, Stephan L. M.; Alewijnse, Astrid E.

    2010-01-01

    Regulatory processes including receptor phosphorylation and intracellular trafficking, also referred to as receptor internalization, are important processes to terminate G protein-coupled receptor (GPCR) signaling. Compelling evidence now indicates that internalization of a receptor is not

  9. The donor-receptor relation in international cooperation management in Medellín Relaciones donante -receptor en la gestión de la cooperación internacional en Medellín

    Directory of Open Access Journals (Sweden)

    Sergio Castrillón Orrego

    2011-12-01

    Full Text Available Foreign Aid plays an increasingly important role in the political and economic dynamics of Latin America. This article analyses the findings regarding the relationships between donors and partners in the management of international cooperation in the city of Medellin, for the period comprehended between 2003 and 2008. The detailed content analysis of the interviews conducted with a representative sample of key players of international cooperation in the city, has enabled us to identify the key moments that characterize and dynamize those relationships as. basically we found that successful management of Foreign Aid must consider the following key moments: identification of partners and sources of international cooperation; building trust and credibility; forming partnerships; developing plans and bargaining and finally relationships with partners and community.La Cooperación Internacional juega un papel cada vez más importante en las dinámicaspolíticas y económicas de América Latina. El presente artículo muestra los hallazgossobre las relaciones donante-receptor, en la gestión de la cooperación internacional enla ciudad de Medellín, respecto al periodo comprendido entre los años 2003 y 2008.A partir de un estudio minucioso de los contenidos de las entrevistas realizadas a losactores significativos de la cooperación internacional en la ciudad, se identifican losprincipales momentos que caracterizan y dinamizan dichas relaciones. Fundamentalmenteencontramos que una buena gestión de la cooperación internacional debe considerarlos siguientes momentos: la identificación de los socios y de las fuentes de cooperacióninternacional; la generación de confianza y credibilidad; la conformación de alianzas; laelaboración de planes y negociación y, finalmente, la relación ejecutor comunidad.

  10. Determination of sites of U50,488H-promoted phosphorylation of the mouse κ opioid receptor (KOPR): disconnect between KOPR phosphorylation and internalization.

    Science.gov (United States)

    Chen, Chongguang; Chiu, Yi-Ting; Wu, Wenman; Huang, Peng; Mann, Anika; Schulz, Stefan; Liu-Chen, Lee-Yuan

    2016-02-15

    Phosphorylation sites of KOPR (κ opioid receptor) following treatment with the selective agonist U50,488H {(-)(trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidiny)cyclo-hexyl]benzeneacetamide} were identified after affinity purification, SDS/PAGE, in-gel digestion with Glu-C and HPLC-MS/MS. Single- and double-phosphorylated peptides were identified containing phosphorylated Ser(356), Thr(357), Thr(363) and Ser(369) in the C-terminal domain. Antibodies were generated against three phosphopeptides containing pSer(356)/pThr(357), pThr(363) and pSer(369) respectively, and affinity-purified antibodies were found to be highly specific for phospho-KOPR. U50,488H markedly enhanced staining of the KOPR by pThr(363)-, pSer(369)- and pSer(356)/pThr(357)-specific antibodies in immunoblotting, which was blocked by the selective KOPR antagonist norbinaltorphimine. Ser(369) phosphorylation affected Thr(363) phosphorylation and vice versa, and Thr(363) or Ser(369) phosphorylation was important for Ser(356)/Thr(357) phosphorylation, revealing a phosphorylation hierarchy. U50,488H, but not etorphine, promoted robust KOPR internalization, although both were full agonists. U50,488H induced higher degrees of phosphorylation than etorphine at Ser(356)/Thr(357), Thr(363) and Ser(369) as determined by immunoblotting. Using SILAC (stable isotope labelling by amino acids in cell culture) and HPLC-MS/MS, we found that, compared with control (C), U50,488H (U) and etorphine (E) KOPR promoted single phosphorylation primarily at Thr(363) and Ser(369) with U/E ratios of 2.5 and 2 respectively. Both induced double phosphorylation at Thr(363)+Ser(369) and Thr(357)+Ser(369) with U/E ratios of 3.3 and 3.4 respectively. Only U50,488H induced triple phosphorylation at Ser(356)+Thr(357)+Ser(369). An unphosphorylated KOPR-(354-372) fragment containing all of the phosphorylation sites was detected with a C/E/U ratio of 1/0.7/0.4, indicating that ∼60% and ∼30% of the mouse KOPR are phosphorylated

  11. Fibroblast Activation Protein (FAP) Accelerates Collagen Degradation and Clearance from Lungs in Mice

    DEFF Research Database (Denmark)

    Fan, Ming-Hui; Zhu, Qiang; Li, Hui-Hua

    2016-01-01

    , intratracheal bleomycin instillation and thoracic irradiation, we find increased mortality and increased lung fibrosis in FAP-deficient mice compared with wild-type mice. Lung extracellular matrix analysis reveals accumulation of intermediate-sized collagen fragments in FAP-deficient mouse lungs, consistent...... within vitrostudies showing that FAP mediates ordered proteolytic processing of matrix metalloproteinase (MMP)-derived collagen cleavage products. FAP-mediated collagen processing leads to increased collagen internalization without altering expression of the endocytic collagen receptor, Endo180....... Pharmacologic FAP inhibition decreases collagen internalization as expected. Conversely, restoration of FAP expression in the lungs of FAP-deficient mice decreases lung hydroxyproline content after intratracheal bleomycin to levels comparable with that of wild-type controls. Our findings indicate that FAP...

  12. Ga-66 labeled somatostatin analogue DOTA-DPhe1-Tyr3-octreotide as a potential agent for positron emission tomography imaging and receptor mediated internal radiotherapy of somatostatin receptor positive tumors

    International Nuclear Information System (INIS)

    Ugur, Oemer; Kothari, Paresh J.; Finn, Ronald D.; Zanzonico, Pat; Ruan, Shutian; Guenther, Ilonka; Maecke, Helmut R.; Larson, Steven M.

    2002-01-01

    Radionuclide labeled somatostatin analogues selectively target somatostatin receptor (SSTR)-expressing tumors as a basis for diagnosis and treatment of these tumors. Recently, a DOTA-functionalized somatostatin analogue, DOTATOC (DOTA-DPhe 1 -Tyr 3 -octreotide) has been developed. This compound has been shown to be superior to the other somatostatin analogues as indicated by its uniquely high tumor-to-non-target tissue ratio. DOTATOC can be labeled with a variety of radiometals including gallium radioisotopes. Gallium-66 is a positron emitting radionuclide (T 1/2 =9.5 hr; β + =56%), that can be produced in carrier free form by a low-beam energy cyclotron. In this study we investigated SSTR targeting characteristics of 66 Ga-DOTATOC in AR42J rat pancreas tumor implanted nude mice as a potential agent for diagnosis and receptor-mediated internal radiotherapy of SSTR-expressing tumors. We compared our results with 67 Ga- and 68 Ga- labeled DOTATOC. The radiolabeling procedure gave labeling yield ranged from 85-95% and radiochemical and chemical purity was >95%. In-vitro competitive binding curves and in-vivo competitive displacement studies with an excess of unlabeled peptide indicates that there is specific binding of the radioligand to SSTR. Animal biodistribution data and serial microPET TM images demonstrated rapid tumor uptake and rapid clearance from the blood and all tissues except kidney. Maximum % ID/g values for tumor were 10.0±0.7, 13.2±2.1 and 9.8±1.5 for 66 Ga-, 67 Ga-, and 68 Ga-DOTATOC, respectively. Calculated tumor, kidney and bone marrow doses for 66 Ga-DOTATOC based on biodistribution data were 178, 109 and 1.2 cGy/MBq, respectively. We conclude that 66 Ga labeled DOTATOC can be used for PET diagnosis and quantitative imaging-based dosimetry of SSTR positive tumors. 66 Ga-DOTATOC may also be used in higher doses for ablation of these tumors. However, kidney is the critical organ for toxicity (tumor/kidney ratio 1.64), and high kidney uptake must

  13. Ga-66 labeled somatostatin analogue DOTA-DPhe{sup 1}-Tyr{sup 3}-octreotide as a potential agent for positron emission tomography imaging and receptor mediated internal radiotherapy of somatostatin receptor positive tumors

    Energy Technology Data Exchange (ETDEWEB)

    Ugur, Oemer E-mail: ougur@hacettepe.edu.tr; Kothari, Paresh J.; Finn, Ronald D.; Zanzonico, Pat; Ruan, Shutian; Guenther, Ilonka; Maecke, Helmut R.; Larson, Steven M

    2002-02-01

    Radionuclide labeled somatostatin analogues selectively target somatostatin receptor (SSTR)-expressing tumors as a basis for diagnosis and treatment of these tumors. Recently, a DOTA-functionalized somatostatin analogue, DOTATOC (DOTA-DPhe{sup 1}-Tyr{sup 3}-octreotide) has been developed. This compound has been shown to be superior to the other somatostatin analogues as indicated by its uniquely high tumor-to-non-target tissue ratio. DOTATOC can be labeled with a variety of radiometals including gallium radioisotopes. Gallium-66 is a positron emitting radionuclide (T{sub 1/2} =9.5 hr; {beta}{sup +}=56%), that can be produced in carrier free form by a low-beam energy cyclotron. In this study we investigated SSTR targeting characteristics of {sup 66}Ga-DOTATOC in AR42J rat pancreas tumor implanted nude mice as a potential agent for diagnosis and receptor-mediated internal radiotherapy of SSTR-expressing tumors. We compared our results with {sup 67}Ga- and {sup 68}Ga- labeled DOTATOC. The radiolabeling procedure gave labeling yield ranged from 85-95% and radiochemical and chemical purity was >95%. In-vitro competitive binding curves and in-vivo competitive displacement studies with an excess of unlabeled peptide indicates that there is specific binding of the radioligand to SSTR. Animal biodistribution data and serial microPET{sup TM} images demonstrated rapid tumor uptake and rapid clearance from the blood and all tissues except kidney. Maximum % ID/g values for tumor were 10.0{+-}0.7, 13.2{+-}2.1 and 9.8{+-}1.5 for {sup 66}Ga-, {sup 67}Ga-, and {sup 68}Ga-DOTATOC, respectively. Calculated tumor, kidney and bone marrow doses for {sup 66}Ga-DOTATOC based on biodistribution data were 178, 109 and 1.2 cGy/MBq, respectively. We conclude that {sup 66}Ga labeled DOTATOC can be used for PET diagnosis and quantitative imaging-based dosimetry of SSTR positive tumors. {sup 66}Ga-DOTATOC may also be used in higher doses for ablation of these tumors. However, kidney is the

  14. Insulin receptors

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  15. Comparison of the binding and internalization properties of 12 DOTA-coupled and {sup 111}In-labelled CCK2/gastrin receptor binding peptides: a collaborative project under COST Action BM0607

    Energy Technology Data Exchange (ETDEWEB)

    Aloj, Luigi; Aurilio, Michela; Rinaldi, Valentina; D' Ambrosio, Laura [Istituto Nazionale Tumori, Fondazione ' ' G. Pascale' ' , AF Medicina Nucleare, Naples (Italy); Tesauro, Diego [Universita ' ' Federico II' ' , CIRPeB, Naples (Italy); Peitl, Petra Kolenc [University Medical Centre Ljubljana, Department of Nuclear Medicine, Ljubljana (Slovenia); Maina, Theodosia [National Center for Scientific Research Demokritos, Molecular Radiopharmacy, Institute of Radioisotopes-Radiodiagnostic Products, Athens (Greece); Mansi, Rosalba [University Hospital Freiburg, Department of Nuclear Medicine, Freiburg (Germany); Guggenberg, Elisabeth von [Innsbruck Medical University, Department of Nuclear Medicine, Innsbruck (Austria); Joosten, Lieke [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, Nijmegen (Netherlands); Sosabowski, Jane K. [Institute of Cancer, Barts and the London Queen Mary' s School of Medicine and Dentistry, Centre for Molecular Oncology and Imaging, London (United Kingdom); Breeman, W.A.P.; Blois, Erik de; Koelewijn, Stuart; Melis, Marleen; Jong, Marion de [Erasmus MC, Department of Nuclear Medicine, Rotterdam (Netherlands); Waser, Beatrice; Beetschen, Karin; Reubi, Jean Claude [University of Berne, Berne (Switzerland)

    2011-08-15

    Specific overexpression of cholecystokinin 2 (CCK2)/gastrin receptors has been demonstrated in several tumours of neuroendocrine origin. In some of these cancer types, such as medullary thyroid cancer (MTC), a sensitive diagnostic modality is still unavailable and therapeutic options for inoperable lesions are needed. Peptide receptor radionuclide therapy (PRRT) may be a viable therapeutic strategy in the management of these patients. Several CCK2R-targeted radiopharmaceuticals have been described in recent years. As part of the European Union COST Action BM0607 we studied the in vitro and in vivo characteristics of 12 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-conjugated CCK2R binding peptides. In the present study, we analysed binding and internalization characteristics. Stability, biodistribution and imaging studies have been performed in parallel by other centres involved in the project. Determination of IC{sub 50} values was performed using autoradiography, with DOTA-peptides displacing {sup 125}I-CCK from receptors on tissue sections from human tumours. Saturation binding and internalization experiments were performed using {sup 111}In-labelled peptides. The rat AR42J cell line and the human A431-CCK2R transfected cell line were utilized for in vitro experiments; dissociation constants (K{sub d}) and apparent number of binding sites (B{sub max}) were determined. Internalization was determined in receptor-expressing cells by incubating with tracer amounts of peptide at 37 and 4 C for different times up to 120 min. Surface-bound peptide was then stripped either by acid wash or subsequent incubation with 1 {mu}M unlabelled peptide at 4 C. All peptides showed high receptor affinity with IC{sub 50} values ranging from 0.2 to 3.4 nM. Saturation experiments also showed high affinity with K{sub d} values in the 10{sup -9}-10{sup -8} M range. B{sub max} values estimated in A431-CCK2R cells ranged from 0.6 to 2.2 x 10{sup 6} per cell. All peptides

  16. Does collagen trigger the recruitment of osteoblasts into vacated bone resorption lacunae during bone remodeling?

    DEFF Research Database (Denmark)

    Abdelgawad, Mohamed Essameldin; Søe, Kent; Andersen, Thomas Levin

    2014-01-01

    matrix molecules, collagen's potency was superior and only equaled by fibronectin. Next, the majority of the newly recruited osteoblast lineage cells positioned immediately next to the osteoclasts exhibit uPARAP/Endo180, an endocytic collagen receptor reported to be involved in collagen internalization......Osteoblast recruitment during bone remodeling is obligatory to re-construct the bone resorbed by the osteoclast. This recruitment is believed to be triggered by osteoclast products and is therefore likely to start early during the remodeling cycle. Several osteoclast products with osteoblast...... recruitment potential are already known. Here we draw the attention on the osteoblast recruitment potential of the collagen that is freshly demineralized by the osteoclast. Our evidence is based on observations on adult human cancellous bone, combined with in vitro assays. First, freshly eroded surfaces where...

  17. N-terminal truncation of the dopamine transporter abolishes phorbol ester- and substance P receptor-stimulated phosphorylation without impairing transporter internalization

    DEFF Research Database (Denmark)

    Granas, Charlotta; Ferrer, Jasmine; Loland, Claus Juul

    2003-01-01

    (q)-coupled human substance P receptor (hNK-1) co-expressed with hDAT in HEK293 cells and in N2A neuroblastoma cells. In both cell lines, activation of the hNK-1 receptor by substance P reduced the V(max) for [(3)H]dopamine uptake to the same degree as did PMA ( approximately 50 and approximately 20% in HEK293...

  18. Somatostatin receptors

    DEFF Research Database (Denmark)

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

    2003-01-01

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

  19. Internalization of interleukin 1 (IL 1) correlates with IL 1-induced IL 2 receptor expression and IL 2 secretion of EL4 thymoma cells

    OpenAIRE

    Von Hoegen, I.; Falk, Werner; Kojouharoff, G.; Krammer, P. H.

    1989-01-01

    The cytokine interleukin 1 (IL 1) plays an important role in the induction of IL 2 secretion and high-affinity IL 2 receptor (IL 2R) expression by T cells. The events that follow binding of IL 1 to IL 1R, however, are still unknown. In this study we describe two variants of the murine thymoma EL4 (5D3 and D6/76) that express comparable numbers of cell surface IL 1 receptors and bind IL 1 with the same affinity, but show distinct IL 1-dependent IL 2 secretion and IL 2R expression. In the prese...

  20. The p38 mitogen-activated protein kinase signaling pathway is involved in regulating low-density lipoprotein receptor-related protein 1-mediated β-amyloid protein internalization in mouse brain.

    Science.gov (United States)

    Ma, Kai-Ge; Lv, Jia; Hu, Xiao-Dan; Shi, Li-Li; Chang, Ke-Wei; Chen, Xin-Lin; Qian, Yi-Hua; Yang, Wei-Na; Qu, Qiu-Min

    2016-07-01

    Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Recently, increasing evidence suggests that intracellular β-amyloid protein (Aβ) alone plays a pivotal role in the progression of AD. Therefore, understanding the signaling pathway and proteins that control Aβ internalization may provide new insight for regulating Aβ levels. In the present study, the regulation of Aβ internalization by p38 mitogen-activated protein kinases (MAPK) through low-density lipoprotein receptor-related protein 1 (LRP1) was analyzed in vivo. The data derived from this investigation revealed that Aβ1-42 were internalized by neurons and astrocytes in mouse brain, and were largely deposited in mitochondria and lysosomes, with some also being found in the endoplasmic reticulum. Aβ1-42-LRP1 complex was formed during Aβ1-42 internalization, and the p38 MAPK signaling pathway was activated by Aβ1-42 via LRP1. Aβ1-42 and LRP1 were co- localized in the cells of parietal cortex and hippocampus. Furthermore, the level of LRP1-mRNA and LRP1 protein involved in Aβ1-42 internalization in mouse brain. The results of this investigation demonstrated that Aβ1-42 induced an LRP1-dependent pathway that related to the activation of p38 MAPK resulting in internalization of Aβ1-42. These results provide evidence supporting a key role for the p38 MAPK signaling pathway which is involved in the regulation of Aβ1-42 internalization in the parietal cortex and hippocampus of mouse through LRP1 in vivo. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Activatory and Inhibitory Fcγ Receptors Augment Rituximab-mediated Internalization of CD20 Independent of Signaling via the Cytoplasmic Domain*

    Science.gov (United States)

    Vaughan, Andrew T.; Chan, Claude H. T.; Klein, Christian; Glennie, Martin J.; Beers, Stephen A.; Cragg, Mark S.

    2015-01-01

    Type I anti-CD20 mAb such as rituximab and ofatumumab engage with the inhibitory FcγR, FcγRIIb on the surface of B cells, resulting in immunoreceptor tyrosine-based inhibitory motif (ITIM) phosphorylation. Internalization of the CD20·mAb·FcγRIIb complex follows, the rate of which correlates with FcγRIIb expression. In contrast, although type II anti-CD20 mAb such as tositumomab and obinutuzumab also interact with and activate FcγRIIb, this interaction fails to augment the rate of CD20·mAb internalization, raising the question of whether ITIM phosphorylation plays any role in this process. We have assessed the molecular requirements for the internalization process and demonstrate that in contrast to internalization of IgG immune complexes, FcγRIIb-augmented internalization of rituximab-ligated CD20 occurs independently of the FcγRIIb ITIM, indicating that signaling downstream of FcγRIIb is not required. In transfected cells, activatory FcγRI, FcγRIIa, and FcγRIIIa augmented internalization of rituximab-ligated CD20 in a similar manner. However, FcγRIIa mediated a slower rate of internalization than cells expressing equivalent levels of the highly homologous FcγRIIb. The difference was maintained in cells expressing FcγRIIa and FcγRIIb lacking cytoplasmic domains and in which the transmembrane domains had been exchanged. This difference may be due to increased degradation of FcγRIIa, which traffics to lysosomes independently of rituximab. We conclude that the cytoplasmic domain of FcγR is not required for promoting internalization of rituximab-ligated CD20. Instead, we propose that FcγR provides a structural role in augmenting endocytosis that differs from that employed during the endocytosis of immune complexes. PMID:25568316

  2. Proceedings of the International Symposium on Subtypes of Muscarinic Receptors 2 (2nd) Held in Boston, Massachusetts on August 22-24 1985

    Science.gov (United States)

    1986-04-30

    Uiversity ’ Hospital. Walter Reed Army Institute Of Research Lund &-22185 Building 40 MEWashington, D.C. 20307-5100 Pm Mau i~bers~, .D.Paul Bianckhi, M.D...acetyl- 6 Yamada, S., Yarmamura, H. 1. and Roeske, W. Rt. (1982) choline? (We suspect, for example, that the consistently Life Sci. 31, 1161-1170 lower...regulation of 9 Hammer, R., Giralo, E., Schiavi. G. B., Monferini. E. and receptor number be studied under in-vivo conditions? Can Ladinsky, H. Life

  3. Distinct cytoplasmic domains of the growth hormone receptor are required for glucocorticoid- and phorbol ester-induced decreases in growth hormone (GH) binding. These domains are different from that reported for GH-induced receptor internalization

    DEFF Research Database (Denmark)

    King, A P; Tseng, M J; Logsdon, C D

    1996-01-01

    Glucocorticoids inhibit growth in children and antagonize the growth-promoting action of GH in peripheral tissues. Recently, they have been shown to decrease GH binding. In this study we examine the molecular mechanisms by which the glucocorticoid dexamethasone (DEX) and the phorbol ester phorbol...... of GH binding are also observed in a Chinese hamster ovary (CHO) cell line stably transfected with a rat liver GHR cDNA, further arguing that DEX and PMA act post-translationally on GHR. Using mutant GHRs stably expressed in CHO cells, amino acids 455-506 and tyrosines 333 and/or 338 of GHR were shown...... to be required for maximal DEX-induced inhibition of GH binding. DEX decreased GH binding to a GHR mutant F346A, which is reported to be deficient in ligand-induced internalization, suggesting that DEX decreases GH binding by a mechanism distinct from that of ligand-induced GHR internalization. PMA reduced GH...

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  5. Activatory and inhibitory Fcγ receptors augment rituximab-mediated internalization of CD20 independent of signaling via the cytoplasmic domain.

    Science.gov (United States)

    Vaughan, Andrew T; Chan, Claude H T; Klein, Christian; Glennie, Martin J; Beers, Stephen A; Cragg, Mark S

    2015-02-27

    Type I anti-CD20 mAb such as rituximab and ofatumumab engage with the inhibitory FcγR, FcγRIIb on the surface of B cells, resulting in immunoreceptor tyrosine-based inhibitory motif (ITIM) phosphorylation. Internalization of the CD20·mAb·FcγRIIb complex follows, the rate of which correlates with FcγRIIb expression. In contrast, although type II anti-CD20 mAb such as tositumomab and obinutuzumab also interact with and activate FcγRIIb, this interaction fails to augment the rate of CD20·mAb internalization, raising the question of whether ITIM phosphorylation plays any role in this process. We have assessed the molecular requirements for the internalization process and demonstrate that in contrast to internalization of IgG immune complexes, FcγRIIb-augmented internalization of rituximab-ligated CD20 occurs independently of the FcγRIIb ITIM, indicating that signaling downstream of FcγRIIb is not required. In transfected cells, activatory FcγRI, FcγRIIa, and FcγRIIIa augmented internalization of rituximab-ligated CD20 in a similar manner. However, FcγRIIa mediated a slower rate of internalization than cells expressing equivalent levels of the highly homologous FcγRIIb. The difference was maintained in cells expressing FcγRIIa and FcγRIIb lacking cytoplasmic domains and in which the transmembrane domains had been exchanged. This difference may be due to increased degradation of FcγRIIa, which traffics to lysosomes independently of rituximab. We conclude that the cytoplasmic domain of FcγR is not required for promoting internalization of rituximab-ligated CD20. Instead, we propose that FcγR provides a structural role in augmenting endocytosis that differs from that employed during the endocytosis of immune complexes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Receptor assay

    Energy Technology Data Exchange (ETDEWEB)

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

    1975-05-01

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

  7. Sorafenib suppresses TGF-β responses by inducing caveolae/lipid raft-mediated internalization/degradation of cell-surface type II TGF-β receptors: Implications in development of effective adjunctive therapy for hepatocellular carcinoma.

    Science.gov (United States)

    Chung, Chih-Ling; Wang, Shih-Wei; Sun, Wei-Chih; Shu, Chih-Wen; Kao, Yu-Chen; Shiao, Meng-Shin; Chen, Chun-Lin

    2018-04-18

    Sorafenib is the only FDA approved drug for the treatment of advanced hepatocellular carcinoma (HCC) and other malignancies. Studies indicate that TGF-β signalling is associated with tumour progression in HCC. Autocrine and paracrine TGF-β promotes tumour growth and malignancy by inducing epithelial-mesenchymal transition (EMT). Sorafenib is believed to antagonize tumour progression by inhibiting TGF-β-induced EMT. It improves survival of patients but HCC later develops resistance and relapses. The underlying mechanism of resistance is unknown. Understanding of the molecular mechanism of sorafenib inhibition of TGF-β-induced signalling or responses in HCC may lead to development of adjunctive effective therapy for HCC. In this study, we demonstrate that sorafenib suppresses TGF-β responsiveness in hepatoma cells, hepatocytes, and animal liver, mainly by downregulating cell-surface type II TGF-β receptors (TβRII) localized in caveolae/lipid rafts and non-lipid raft microdomains via caveolae/lipid rafts-mediated internalization and degradation. Furthermore, sorafenib-induced downregulation and degradation of cell-surface TβRII is prevented by simultaneous treatment with a caveolae disruptor or lysosomal inhibitors. On the other hand, sorafenib only downregulates cell-surface TβRII localized in caveolae/lipid rafts but not localized in non-lipid raft microdomains in hepatic stellate cells. These results suggest that sorafenib inhibits TGF-β signalling mainly by inducing caveolae/lipid raft-mediated internalization and degradation of cell-surface TβR-II in target cells. They may also imply that treatment with agents which promote formation of caveolae/lipid rafts, TGF-β receptor kinase inhibitors (e.g., LY2157299) or TGF-β peptide antagonists (by liver-targeting delivery) may be considered as effective adjunct therapy with sorafenib for HCC. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Mutation D816V alters the internal structure and dynamics of c-KIT receptor cytoplasmic region: implications for dimerization and activation mechanisms.

    Directory of Open Access Journals (Sweden)

    Elodie Laine

    2011-06-01

    Full Text Available The type III receptor tyrosine kinase (RTK KIT plays a crucial role in the transmission of cellular signals through phosphorylation events that are associated with a switching of the protein conformation between inactive and active states. D816V KIT mutation is associated with various pathologies including mastocytosis and cancers. D816V-mutated KIT is constitutively active, and resistant to treatment with the anti-cancer drug Imatinib. To elucidate the activating molecular mechanism of this mutation, we applied a multi-approach procedure combining molecular dynamics (MD simulations, normal modes analysis (NMA and binding site prediction. Multiple 50-ns MD simulations of wild-type KIT and its mutant D816V were recorded using the inactive auto-inhibited structure of the protein, characteristic of type III RTKs. Computed free energy differences enabled us to quantify the impact of D816V on protein stability in the inactive state. We evidenced a local structural alteration of the activation loop (A-loop upon mutation, and a long-range structural re-organization of the juxta-membrane region (JMR followed by a weakening of the interaction network with the kinase domain. A thorough normal mode analysis of several MD conformations led to a plausible molecular rationale to propose that JMR is able to depart its auto-inhibitory position more easily in the mutant than in wild-type KIT and is thus able to promote kinase mutant dimerization without the need for extra-cellular ligand binding. Pocket detection at the surface of NMA-displaced conformations finally revealed that detachment of JMR from the kinase domain in the mutant was sufficient to open an access to the catalytic and substrate binding sites.

  9. International Workshop at the Nobel Forum, Karolinska Institutet on G protein-coupled receptors: finding the words to describe monomers, oligomers, and their molecular mechanisms and defining their meaning. Can a consensus be reached?

    Science.gov (United States)

    Kenakin, Terry; Agnati, Luigi F; Caron, Marc; Fredholm, Bertil; Guidoli, Diego; Kobilka, Brian; Lefkowitz, Robert W; Lohse, Martin; Woods, Amina; Fuxe, Kjell

    2010-10-01

    A meeting was held May 19, 2010 at the Karolinski Institute on Nomenclature in Pharmacology. This meeting occurred in conjunction with the Symposium The Changing World of G Protein Coupled Receptors: From Monomers to Dimers and Receptor Mosaics (Higher-order Oligomers) held the previous day at the Royal Swedish Academy of Science. Two broad topics of nomenclature were discussed; ligand nomenclature and the definition of 'receptor-receptor' interactions. This paper summarizes discussions on these topics along with a consensus definition of the term 'receptor-receptor' interaction.

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

    Science.gov (United States)

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

    2016-04-12

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

  11. Opioid receptor desensitization: mechanisms and its link to tolerance

    Directory of Open Access Journals (Sweden)

    Stéphane eAllouche

    2014-12-01

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

  12. Rapid resensitization of purinergic receptor function in human platelets.

    Science.gov (United States)

    Mundell, S J; Barton, J F; Mayo-Martin, M B; Hardy, A R; Poole, A W

    2008-08-01

    Adenosine diphosphate (ADP) is a critical regulator of platelet activation, mediating its actions through two G protein-coupled receptors (GPCRs), the P2Y(1) and P2Y(12) purinergic receptors. Recently, we demonstrated that both receptors desensitize and internalize in human platelets by differential kinase-dependent mechanisms. To demonstrate whether responses to P2Y(1) and P2Y(12) purinergic receptors resensitize in human platelets and determine the role of receptor traffic in this process. These studies were undertaken either in human platelets or in cells stably expressing epitope-tagged P2Y(1) and P2Y(12) purinergic receptor constructs. In this study we show for the first time that responses to both of these receptors can rapidly resensitize following agonist-dependent desensitization in human platelets. Further, we show that in human platelets or in 1321N1 cells stably expressing receptor constructs, the disruption of receptor internalization, dephosphorylation or subsequent receptor recycling is sufficient to block resensitization of purinergic receptor responses. We also show that, in platelets, internalization of both these receptors is dependent upon dynamin, and that this process is required for resensitization of responses. This study is therefore the first to show that both P2Y(1) and P2Y(12) receptor activities are rapidly and reversibly modulated in human platelets, and it reveals that the underlying mechanism requires receptor trafficking as an essential part of this process.

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

    Directory of Open Access Journals (Sweden)

    María S. Aymerich

    2011-01-01

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

  14. M2-like macrophages are responsible for collagen degradation through a mannose receptor–mediated pathway

    Science.gov (United States)

    Madsen, Daniel H.; Leonard, Daniel; Masedunskas, Andrius; Moyer, Amanda; Jürgensen, Henrik Jessen; Peters, Diane E.; Amornphimoltham, Panomwat; Selvaraj, Arul; Yamada, Susan S.; Brenner, David A.; Burgdorf, Sven; Engelholm, Lars H.; Behrendt, Niels; Holmbeck, Kenn; Weigert, Roberto

    2013-01-01

    Tissue remodeling processes critically depend on the timely removal and remodeling of preexisting collagen scaffolds. Nevertheless, many aspects related to the turnover of this abundant extracellular matrix component in vivo are still incompletely understood. We therefore took advantage of recent advances in optical imaging to develop an assay to visualize collagen turnover in situ and identify cell types and molecules involved in this process. Collagen introduced into the dermis of mice underwent cellular endocytosis in a partially matrix metalloproteinase–dependent manner and was subsequently routed to lysosomes for complete degradation. Collagen uptake was predominantly executed by a quantitatively minor population of M2-like macrophages, whereas more abundant Col1a1-expressing fibroblasts and Cx3cr1-expressing macrophages internalized collagen at lower levels. Genetic ablation of the collagen receptors mannose receptor (Mrc1) and urokinase plasminogen activator receptor–associated protein (Endo180 and Mrc2) impaired this intracellular collagen degradation pathway. This study demonstrates the importance of receptor-mediated cellular uptake to collagen turnover in vivo and identifies a key role of M2-like macrophages in this process. PMID:24019537

  15. Checking the STEP-Associated Trafficking and Internalization of Glutamate Receptors for Reduced Cognitive Deficits: A Machine Learning Approach-Based Cheminformatics Study and Its Application for Drug Repurposing.

    Directory of Open Access Journals (Sweden)

    Salma Jamal

    Full Text Available Alzheimer's disease, a lethal neurodegenerative disorder that leads to progressive memory loss, is the most common form of dementia. Owing to the complexity of the disease, its root cause still remains unclear. The existing anti-Alzheimer's drugs are unable to cure the disease while the current therapeutic options have provided only limited help in restoring moderate memory and remain ineffective at restricting the disease's progression. The striatal-enriched protein tyrosine phosphatase (STEP has been shown to be involved in the internalization of the receptor, N-methyl D-aspartate (NMDR and thus is associated with the disease. The present study was performed using machine learning algorithms, docking protocol and molecular dynamics (MD simulations to develop STEP inhibitors, which could be novel anti-Alzheimer's molecules.The present study deals with the generation of computational predictive models based on chemical descriptors of compounds using machine learning approaches followed by substructure fragment analysis. To perform this analysis, the 2D molecular descriptors were generated and machine learning algorithms (Naïve Bayes, Random Forest and Sequential Minimization Optimization were utilized. The binding mechanisms and the molecular interactions between the predicted active compounds and the target protein were modelled using docking methods. Further, the stability of the protein-ligand complex was evaluated using MD simulation studies. The substructure fragment analysis was performed using Substructure fingerprint (SubFp, which was further explored using a predefined dictionary.The present study demonstrates that the computational methodology used can be employed to examine the biological activities of small molecules and prioritize them for experimental screening. Large unscreened chemical libraries can be screened to identify potential novel hits and accelerate the drug discovery process. Additionally, the chemical libraries can be

  16. International Trade. International Business

    OpenAIRE

    Мохнюк, А. М.; Mokhniuk, A. M.

    2015-01-01

    Work programme of the study course “International Trade. International Business” was prepared in accordance with educational and vocational training program for bachelors of training direction 6.030601 “Management”.

  17. Relationship of epidermal growth factor receptor activating mutations with histologic subtyping according to International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society 2011 adenocarcinoma classification and their impact on overall survival

    Directory of Open Access Journals (Sweden)

    Venkata Nagarjuna Maturu

    2016-01-01

    Full Text Available Background: There is limited Indian data on epidermal growth factor receptor (EGFR gene activating mutations (AMs prevalence and their clinicopathologic associations. The current study aimed to assess the relationship between EGFR AM and histologic subtypes and their impact on overall survival (OS in a North Indian cohort. Patients and Methods: Retrospective analysis of nonsmall cell lung cancer patients who underwent EGFR mutation testing (n = 186 over 3 years period (2012-2014. EGFR mutations were tested using polymerase chain reaction amplification and direct sequencing. Patients were classified as EGFR AM, EGFR wild type (WT or EGFR unknown (UKN. Histologically adenocarcinomas (ADC were further categorized as per the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society-2011 classification. Results: Overall EGFR AM prevalence was 16.6%. The ratio of exon 19 deletions to exon 21 L858R mutations was 3.17:1. Female sex (P = 0.002, never smoking status (P = 0.002, metastatic disease (P = 0.032, and nonsolid subtype of ADC (P = 0.001 were associated with EGFR AM on univariate logistic regression analysis (LRA. On multivariate LRA, solid ADC was negatively associated with EGFR AM. Median OS was higher in patients with EGFR AM (750 days as compared to EGFR-WT (459 days or EGFR-UKN (291 days for the overall population and in patients with Stage IV disease (750 days vs. 278 days for EGFR-WT, P = 0.024. On univariate Cox proportional hazard (CPH analysis, smoking, poor performance status (Eastern Cooperative Oncology Group ≥ 2, EGFR-UKN status, and solid ADC were associated with worse OS while female sex and lepidic ADC had better OS. On multivariate CPH analysis, lepidic ADC (hazard ratio [HR] =0.12 and EGFR-WT/EGFR-UKN (HR = 2.39 and HR = 3.30 respectively were independently associated with OS in separate analyses. Conclusions: Histologic subtyping of ADC performed on small biopsies is

  18. The LDL receptor.

    Science.gov (United States)

    Goldstein, Joseph L; Brown, Michael S

    2009-04-01

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

  19. Purinergic Receptors in Ocular Inflammation

    Directory of Open Access Journals (Sweden)

    Ana Guzman-Aranguez

    2014-01-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2017-07-01

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

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

    DEFF Research Database (Denmark)

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

    2004-01-01

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

  3. Roles of Fragile X Mental Retardation Protein in Dopaminergic Stimulation-induced Synapse-associated Protein Synthesis and Subsequent α-Amino-3-hydroxyl-5-methyl-4-isoxazole-4-propionate (AMPA) Receptor Internalization*

    OpenAIRE

    Wang, Hansen; Kim, Susan S.; Zhuo, Min

    2010-01-01

    Fragile X syndrome, the most common form of inherited mental retardation, is caused by the absence of the RNA-binding protein fragile X mental retardation protein (FMRP). FMRP regulates local protein synthesis in dendritic spines. Dopamine (DA) is involved in the modulation of synaptic plasticity. Activation of DA receptors can regulate higher brain functions in a protein synthesis-dependent manner. Our recent study has shown that FMRP acts as a key messenger for DA modulation in forebrain ne...

  4. Insulin receptor membrane retention by a traceable chimeric mutant

    OpenAIRE

    Giudice, Jimena; Jares, Elizabeth Andrea; Coluccio Leskow, Federico

    2015-01-01

    Background: The insulin receptor (IR) regulates glucose homeostasis, cell growth and differentiation. It has been hypothesized that the specific signaling characteristics of IR are in part determined by ligand-receptor complexes localization. Downstream signaling could be triggered from the plasma membrane or from endosomes. Regulation of activated receptor's internalization has been proposed as the mechanism responsible for the differential isoform and ligand-specific signaling. Re...

  5. Receptor-receptor interactions within receptor mosaics. Impact on neuropsychopharmacology.

    Science.gov (United States)

    Fuxe, K; Marcellino, D; Rivera, A; Diaz-Cabiale, Z; Filip, M; Gago, B; Roberts, D C S; Langel, U; Genedani, S; Ferraro, L; de la Calle, A; Narvaez, J; Tanganelli, S; Woods, A; Agnati, L F

    2008-08-01

    Future therapies for diseases associated with altered dopaminergic signaling, including Parkinson's disease, schizophrenia and drug addiction or drug dependence may substantially build on the existence of intramembrane receptor-receptor interactions within dopamine receptor containing receptor mosaics (RM; dimeric or high-order receptor oligomers) where it is believed that the dopamine D(2) receptor may operate as the 'hub receptor' within these complexes. The constitutive adenosine A(2A)/dopamine D(2) RM, located in the dorsal striato-pallidal GABA neurons, are of particular interest in view of the demonstrated antagonistic A(2A)/D(2) interaction within these heteromers; an interaction that led to the suggestion and later demonstration that A(2A) antagonists could be used as novel anti-Parkinsonian drugs. Based on the likely existence of A(2A)/D(2)/mGluR5 RM located both extrasynaptically on striato-pallidal GABA neurons and on cortico-striatal glutamate terminals, multiple receptor-receptor interactions within this RM involving synergism between A(2A)/mGluR5 to counteract D(2) signaling, has led to the proposal of using combined mGluR5 and A(2A) antagonists as a future anti-Parkinsonian treatment. Based on the same RM in the ventral striato-pallidal GABA pathways, novel strategies for the treatment of schizophrenia, building on the idea that A(2A) agonists and/or mGluR5 agonists will help reduce the increased dopaminergic signaling associated with this disease, have been suggested. Such treatment may ensure the proper glutamatergic drive from the mediodorsal thalamic nucleus to the prefrontal cortex, one which is believed to be reduced in schizophrenia due to a dominance of D(2)-like signaling in the ventral striatum. Recently, A(2A) receptors also have been shown to counteract the locomotor and sensitizing actions of cocaine and increases in A(2A) receptors have also been observed in the nucleus accumbens after extended cocaine self-administration, probably

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  7. Fucosylation and protein glycosylation create functional receptors for cholera toxin

    DEFF Research Database (Denmark)

    Wands, Amberlyn M; Fujita, Akiko; McCombs, Janet E

    2015-01-01

    Cholera toxin (CT) enters and intoxicates host cells after binding cell surface receptors using its B subunit (CTB). The ganglioside (glycolipid) GM1 is thought to be the sole CT receptor; however, the mechanism by which CTB binding to GM1 mediates internalization of CT remains enigmatic. Here we...... in normal human intestinal epithelia and could play a role in cholera....

  8. Acetylcholine receptor antibody

    Science.gov (United States)

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

  9. Fluctuation correlation models for receptor immobilization

    Science.gov (United States)

    Fourcade, B.

    2017-12-01

    Nanoscale dynamics with cycles of receptor diffusion and immobilization by cell-external-or-internal factors is a key process in living cell adhesion phenomena at the origin of a plethora of signal transduction pathways. Motivated by modern correlation microscopy approaches, the receptor correlation functions in physical models based on diffusion-influenced reaction is studied. Using analytical and stochastic modeling, this paper focuses on the hybrid regime where diffusion and reaction are not truly separable. The time receptor autocorrelation functions are shown to be indexed by different time scales and their asymptotic expansions are given. Stochastic simulations show that this analysis can be extended to situations with a small number of molecules. It is also demonstrated that this analysis applies when receptor immobilization is coupled to environmental noise.

  10. Cooperative ethylene receptor signaling

    OpenAIRE

    Liu, Qian; Wen, Chi-Kuang

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-02-12

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

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

    Directory of Open Access Journals (Sweden)

    Resat Haluk

    2007-11-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  14. Pairwise comparison of 89Zr- and 124I-labeled cG250 based on positron emission tomography imaging and nonlinear immunokinetic modeling: in vivo carbonic anhydrase IX receptor binding and internalization in mouse xenografts of clear-cell renal cell carcinoma

    International Nuclear Information System (INIS)

    Cheal, Sarah M.; Punzalan, Blesida; Doran, Michael G.; Osborne, Joseph R.; Evans, Michael J.; Lewis, Jason S.; Zanzonico, Pat; Larson, Steven M.

    2014-01-01

    The PET tracer, 124 I-cG250, directed against carbonic anhydrase IX (CAIX) shows promise for presurgical diagnosis of clear-cell renal cell carcinoma (ccRCC) (Divgi et al. in Lancet Oncol 8:304-310, 2007; Divgi et al. in J Clin Oncol 31:187-194, 2013). The radiometal 89 Zr, however, may offer advantages as a surrogate PET nuclide over 124 I in terms of greater tumor uptake and retention (Rice et al. in Semin Nucl Med 41:265-282, 2011). We have developed a nonlinear immunokinetic model to facilitate a quantitative comparison of absolute uptake and antibody turnover between 124 I-cG250 and 89 Zr-cG250 using a human ccRCC xenograft tumor model in mice. We believe that this unique model better relates quantitative imaging data to the salient biological features of tumor antibody-antigen binding and turnover. We conducted experiments with 89 Zr-cG250 and 124 I-cG250 using a human ccRCC cell line (SK-RC-38) to characterize the binding affinity and internalization kinetics of the two tracers in vitro. Serial PET imaging was performed in mice bearing subcutaneous ccRCC tumors to simultaneously detect and quantify time-dependent tumor uptake in vivo. Using the known specific activities of the two tracers, the equilibrium rates of antibody internalization and turnover in the tumors were derived from the PET images using nonlinear compartmental modeling. The two tracers demonstrated virtually identical tumor cell binding and internalization but showed markedly different retentions in vitro. Superior PET images were obtained using 89 Zr-cG250, owing to the more prolonged trapping of the radiolabel in the tumor and simultaneous washout from normal tissues. Estimates of cG250/CAIX complex turnover were 1.35 - 5.51 x 10 12 molecules per hour per gram of tumor (20 % of receptors internalized per hour), and the ratio of 124 I/ 89 Zr atoms released per unit time by tumor was 17.5. Pairwise evaluation of 89 Zr-cG250 and 124 I-cG250 provided the basis for a nonlinear immunokinetic

  15. Pairwise comparison of {sup 89}Zr- and {sup 124}I-labeled cG250 based on positron emission tomography imaging and nonlinear immunokinetic modeling: in vivo carbonic anhydrase IX receptor binding and internalization in mouse xenografts of clear-cell renal cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Cheal, Sarah M.; Punzalan, Blesida; Doran, Michael G.; Osborne, Joseph R. [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York, NY (United States); Evans, Michael J. [Memorial Sloan-Kettering Cancer Center, Human Oncology and Pathogenesis Program, New York, NY (United States); Lewis, Jason S. [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York, NY (United States); Memorial Sloan-Kettering Cancer Center, Program in Molecular Pharmacology and Chemistry, New York, NY (United States); Memorial Sloan-Kettering Cancer Center, Radiochemistry and Imaging Sciences Service, New York, NY (United States); Zanzonico, Pat [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York, NY (United States); Memorial Sloan-Kettering Cancer Center, Molecular Pharmacology and Therapy Service, New York, NY (United States); Memorial-Sloan Kettering Cancer Center, New York, NY (United States); Larson, Steven M. [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York, NY (United States); Memorial Sloan-Kettering Cancer Center, Program in Molecular Pharmacology and Chemistry, New York, NY (United States); Memorial Sloan-Kettering Cancer Center, Molecular Pharmacology and Therapy Service, New York, NY (United States)

    2014-05-15

    The PET tracer, {sup 124}I-cG250, directed against carbonic anhydrase IX (CAIX) shows promise for presurgical diagnosis of clear-cell renal cell carcinoma (ccRCC) (Divgi et al. in Lancet Oncol 8:304-310, 2007; Divgi et al. in J Clin Oncol 31:187-194, 2013). The radiometal {sup 89}Zr, however, may offer advantages as a surrogate PET nuclide over {sup 124}I in terms of greater tumor uptake and retention (Rice et al. in Semin Nucl Med 41:265-282, 2011). We have developed a nonlinear immunokinetic model to facilitate a quantitative comparison of absolute uptake and antibody turnover between {sup 124}I-cG250 and {sup 89}Zr-cG250 using a human ccRCC xenograft tumor model in mice. We believe that this unique model better relates quantitative imaging data to the salient biological features of tumor antibody-antigen binding and turnover. We conducted experiments with {sup 89}Zr-cG250 and {sup 124}I-cG250 using a human ccRCC cell line (SK-RC-38) to characterize the binding affinity and internalization kinetics of the two tracers in vitro. Serial PET imaging was performed in mice bearing subcutaneous ccRCC tumors to simultaneously detect and quantify time-dependent tumor uptake in vivo. Using the known specific activities of the two tracers, the equilibrium rates of antibody internalization and turnover in the tumors were derived from the PET images using nonlinear compartmental modeling. The two tracers demonstrated virtually identical tumor cell binding and internalization but showed markedly different retentions in vitro. Superior PET images were obtained using {sup 89}Zr-cG250, owing to the more prolonged trapping of the radiolabel in the tumor and simultaneous washout from normal tissues. Estimates of cG250/CAIX complex turnover were 1.35 - 5.51 x 10{sup 12} molecules per hour per gram of tumor (20 % of receptors internalized per hour), and the ratio of {sup 124}I/{sup 89}Zr atoms released per unit time by tumor was 17.5. Pairwise evaluation of {sup 89}Zr-cG250 and {sup

  16. A2A-D2 receptor-receptor interaction modulates gliotransmitter release from striatal astrocyte processes.

    Science.gov (United States)

    Cervetto, Chiara; Venturini, Arianna; Passalacqua, Mario; Guidolin, Diego; Genedani, Susanna; Fuxe, Kjell; Borroto-Esquela, Dasiel O; Cortelli, Pietro; Woods, Amina; Maura, Guido; Marcoli, Manuela; Agnati, Luigi F

    2017-01-01

    Evidence for striatal A2A-D2 heterodimers has led to a new perspective on molecular mechanisms involved in schizophrenia and Parkinson's disease. Despite the increasing recognition of astrocytes' participation in neuropsychiatric disease vulnerability, involvement of striatal astrocytes in A2A and D2 receptor signal transmission has never been explored. Here, we investigated the presence of D2 and A2A receptors in isolated astrocyte processes prepared from adult rat striatum by confocal imaging; the effects of receptor activation were measured on the 4-aminopyridine-evoked release of glutamate from the processes. Confocal analysis showed that A2A and D2 receptors were co-expressed on the same astrocyte processes. Evidence for A2A-D2 receptor-receptor interactions was obtained by measuring the release of the gliotransmitter glutamate: D2 receptors inhibited the glutamate release, while activation of A2A receptors, per se ineffective, abolished the effect of D2 receptor activation. The synthetic D2 peptide VLRRRRKRVN corresponding to the receptor region involved in electrostatic interaction underlying A2A-D2 heteromerization abolished the ability of the A2A receptor to antagonize the D2 receptor-mediated effect. Together, the findings are consistent with heteromerization of native striatal astrocytic A2A-D2 receptors that via allosteric receptor-receptor interactions could play a role in the control of striatal glutamatergic transmission. These new findings suggest possible new pathogenic mechanisms and/or therapeutic approaches to neuropsychiatric disorders. © 2016 International Society for Neurochemistry.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  18. GABA receptor imaging

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-04-15

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

  19. GABA receptor imaging

    International Nuclear Information System (INIS)

    Lee, Jong Doo

    2007-01-01

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

  20. Glucocorticoid receptor modulators.

    Science.gov (United States)

    Meijer, Onno C; Koorneef, Lisa L; Kroon, Jan

    2018-06-01

    The glucocorticoid hormone cortisol acts throughout the body to support circadian processes and adaptation to stress. The glucocorticoid receptor is the target of cortisol and of synthetic glucocorticoids, which are used widely in the clinic. Both agonism and antagonism of the glucocorticoid receptor may be beneficial in disease, but given the wide expression of the receptor and involvement in various processes, beneficial effects are often accompanied by unwanted side effects. Selective glucocorticoid receptor modulators are ligands that induce a receptor conformation that allows activation of only a subset of downstream signaling pathways. Such molecules thereby combine agonistic and antagonistic properties. Here we discuss the mechanisms underlying selective receptor modulation and their promise in treating diseases in several organ systems where cortisol signaling plays a role. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  1. Internal Bleeding

    Science.gov (United States)

    ... Fractures (Part II) Additional Content Medical News Internal Bleeding By Amy H. Kaji, MD, PhD, Associate Professor, ... Emergency First Aid Priorities Cardiac Arrest Choking Internal Bleeding Severed or Constricted Limbs or Digits Soft-Tissue ...

  2. Dengue virus receptor

    OpenAIRE

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

    2011-01-01

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

  3. International Relations

    OpenAIRE

    McGlinchey, S.

    2017-01-01

    A ‘Day 0’ introduction to International Relations for beginners. Written by a range of emerging and established experts, the chapters offer a broad sweep of the basic components of International Relations and the key contemporary issues that concern the discipline. The narrative arc forms a complete circle, taking readers from no knowledge to competency. The journey starts by examining how the international system was formed and ends by reflecting that International Relations is always adapti...

  4. International law

    CERN Document Server

    Shaw, Malcolm N

    2017-01-01

    International Law is the definitive and authoritative text on the subject, offering Shaw's unbeatable combination of clarity of expression and academic rigour and ensuring both understanding and critical analysis in an engaging and authoritative style. Encompassing the leading principles, practice and cases, and retaining and developing the detailed references which encourage and assist the reader in further study, this new edition motivates and challenges students and professionals while remaining accessible and engaging. Fully updated to reflect recent case law and treaty developments, this edition contains an expanded treatment of the relationship between international and domestic law, the principles of international humanitarian law, and international criminal law alongside additional material on international economic law.

  5. Nature and regulation of the receptors for insulin-like growth factors

    International Nuclear Information System (INIS)

    Rechler, M.M.; Nissley, S.P.

    1985-01-01

    Two subtypes of IGF receptors have been identified. Type I IGF receptors have a Mr greater than 300,000 and are composed of disulfide-linked 130,000-dalton (alpha) and approximately 90,000-dalton (beta) subunits. Type I receptors preferentially bind IGF-I but also bind IGF-II and, more weakly, insulin. Type II IGF receptors consist of a 250,000-dalton protein that contains internal disulfide bonds but is not linked to other membrane components. Type II receptors bind IGF-II with higher affinity than IGF-I. They do not interact with even very high concentrations of insulin. Type I IGF receptors and insulin receptors are homologous structures. Type II IGF receptors do not appear to be homologous to type I receptors. Type II receptors do not appear to be downregulated. Insulin acutely upregulates type II IGF receptors in intact rat adipose cells by effecting a redistribution of receptors cycling between a large intracellular pool and the plasma membrane. Insulin and the IGFs elicit the same biological responses, either by cross-reacting with one of the receptors for the heterologous ligand or by concurrent activation of convergent effector pathways by binding to the homologous receptor. Which mechanism is utilized appears to depend more on the tissue than on the biological response. Insulin desensitizes rat hepatoma cells to the actions of insulin and IGFs, mediated by both insulin and IGF receptors, by mechanisms distal to hormone binding and possibly common to IGF and insulin effector pathways

  6. Structure-function relationships for the interleukin 2 receptor system

    Directory of Open Access Journals (Sweden)

    Richard J. Robb

    1987-01-01

    Full Text Available Receptors for interleukin 2 (IL-2 esit in at least three forms which differ in their subunit compositio, their affinity for ligand and their ability to mediate a cellular reponse. Type I receptors occur following cellular acitivation and consist of the 55,000 m. w. glycoprotein Tac. These receptors bind IL-2 with a low affinity, do not internalize ligand and have not been definitively associated with any response. Type II receptors, on the other hand, conssit of one or more glycoproteins of 70,000 m. w. which have been termed "beta ([beta] chains." They bind IL-2 with an intermediate affinity and rapidly internalize the ligand. [Beta] proteins mediate many cellular IL-2-dependent reponses, including the short-term activation of natural killer cells and the induction of Tac protein expression. Type III receptors consist of a ternary complex of the Tac protein, the [beta] chain(s and IL-2. They are characterized by a paricularly high affinity for ligand association. Type III receptors also internalize ligand and mediate IL-2-dependent responses at low factor concentrations. The identification of two independent IL-2-binding molecules, Tac and [beta], thus provides the elusive molecular explanation for the differences in IL-2 receptor affinity and suggests the potential for selective therapeutic manipulation of IL-2 reponses.

  7. Genetic moderation of child maltreatment effects on depression and internalizing symptoms by serotonin transporter linked polymorphic region (5-HTTLPR), brain-derived neurotrophic factor (BDNF), norepinephrine transporter (NET), and corticotropin releasing hormone receptor 1 (CRHR1) genes in African American children.

    Science.gov (United States)

    Cicchetti, Dante; Rogosch, Fred A

    2014-11-01

    Genetic moderation of the effects of child maltreatment on depression and internalizing symptoms was investigated in a sample of low-income maltreated and nonmaltreated African American children (N = 1,096). Lifetime child maltreatment experiences were independently coded from Child Protective Services records and maternal report. Child depression and internalizing problems were assessed in the context of a summer research camp by self-report on the Children's Depression Inventory and adult counselor report on the Teacher Report Form. DNA was obtained from buccal cell or saliva samples and genotyped for polymorphisms of the following genes: serotonin transporter linked polymorphic region (5-HTTLPR), brain-derived neurotrophic factor (BDNF), norepinephrine transporter, and corticotropin releasing hormone receptor 1. Analyses of covariance with age and gender as covariates were conducted, with maltreatment status and respective polymorphism as main effects and their Gene × Environment (G × E) interactions. Maltreatment consistently was associated with higher Children's Depression Inventory and Teacher Report Form symptoms. The results for child self-report symptoms indicated a G × E interaction for BDNF and maltreatment. In addition, BDNF and triallelic 5-HTTLPR interacted with child maltreatment in a G × G × E interaction. Analyses for counselor report of child anxiety/depression symptoms on the Teacher Report Form indicated moderation of child maltreatment effects by triallelic 5-HTTLPR. These effects were elaborated based on variation in developmental timing of maltreatment experiences. Norepinephrine transporter was found to further moderate the G × E interaction of 5-HTTLPR and maltreatment status, revealing a G × G × E interaction. This G × G × E was extended by consideration of variation in maltreatment subtype experiences. Finally, G × G × E effects were observed for the co-action of BDNF and the corticotropin releasing hormone receptor 1

  8. Angiotensin type 2 receptors

    DEFF Research Database (Denmark)

    Sumners, Colin; de Kloet, Annette D; Krause, Eric G

    2015-01-01

    In most situations, the angiotensin AT2-receptor (AT2R) mediates physiological actions opposing those mediated by the AT1-receptor (AT1R), including a vasorelaxant effect. Nevertheless, experimental evidence vastly supports that systemic application of AT2R-agonists is blood pressure neutral...

  9. Glutamate receptor agonists

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  10. AMPA receptor ligands

    DEFF Research Database (Denmark)

    Strømgaard, Kristian; Mellor, Ian

    2004-01-01

    Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR), subtype of the ionotropic glutamate receptors (IGRs), mediate fast synaptic transmission in the central nervous system (CNS), and are involved in many neurological disorders, as well as being a key player in the f......Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR), subtype of the ionotropic glutamate receptors (IGRs), mediate fast synaptic transmission in the central nervous system (CNS), and are involved in many neurological disorders, as well as being a key player...... in the formation of memory. Hence, ligands affecting AMPARs are highly important for the study of the structure and function of this receptor, and in this regard polyamine-based ligands, particularly polyamine toxins, are unique as they selectively block Ca2+ -permeable AMPARs. Indeed, endogenous intracellular...

  11. Eleventh international symposium on radiopharmaceutical chemistry

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    This document contains abstracts of papers which were presented at the Eleventh International Symposium on Radiopharmaceutical Chemistry. Sessions included: radiopharmaceuticals for the dopaminergic system, strategies for the production and use of labelled reactive small molecules, radiopharmaceuticals for measuring metabolism, radiopharmaceuticals for the serotonin and sigma receptor systems, labelled probes for molecular biology applications, radiopharmaceuticals for receptor systems, radiopharmaceuticals utilizing coordination chemistry, radiolabelled antibodies, radiolabelling methods for small molecules, analytical techniques in radiopharmaceutical chemistry, and analytical techniques in radiopharmaceutical chemistry.

  12. Eleventh international symposium on radiopharmaceutical chemistry

    International Nuclear Information System (INIS)

    1995-01-01

    This document contains abstracts of papers which were presented at the Eleventh International Symposium on Radiopharmaceutical Chemistry. Sessions included: radiopharmaceuticals for the dopaminergic system, strategies for the production and use of labelled reactive small molecules, radiopharmaceuticals for measuring metabolism, radiopharmaceuticals for the serotonin and sigma receptor systems, labelled probes for molecular biology applications, radiopharmaceuticals for receptor systems, radiopharmaceuticals utilizing coordination chemistry, radiolabelled antibodies, radiolabelling methods for small molecules, analytical techniques in radiopharmaceutical chemistry, and analytical techniques in radiopharmaceutical chemistry

  13. Lipophorin Receptor: The Insect Lipoprotein Receptor

    Indian Academy of Sciences (India)

    IAS Admin

    Director of ... function of the Lp is to deliver lipids throughout the insect body for metabolism ... Lipid is used as a major energy source for development as well as other metabolic .... LpR4 receptor variant was expressed exclusively in the brain and.

  14. internal branding

    OpenAIRE

    Rai, Anu; Omanga, Josphat

    2014-01-01

    The project report provides an insight into internal branding of two different leading firms – Coca-Cola and Google. The aim of this project report is to study how these two companies use internal branding to promote or build brand performance of the company. This report follows a qualitative research method. The report is deductive in nature and hence, it is guided by the literatures of internal branding. The project report conducted research on brand identity, brand commitment and brand loy...

  15. Internal branding

    OpenAIRE

    Rijal, Ramesh; Dhakal, Rajendra

    2015-01-01

    The project report provides an insight into internal branding of two different leading firms – Coca-Cola and Google. The aim of this project report is to study how these two companies use internal branding to promote or build brand performance of the company. This report follows a qualitative research method. The report is deductive in nature and hence, it is guided by the literatures of internal branding. The project report conducted research on brand identity, brand commitment and brand loy...

  16. Cutaneous corpuscular receptors of the human glans clitoris: descriptive characteristics and comparison with the glans penis.

    Science.gov (United States)

    Shih, Cheryl; Cold, Christopher J; Yang, Claire C

    2013-07-01

    The female genital sensory pathways that initiate sexual arousal reflexes begin with cutaneous corpuscular receptors in the glabrous genital skin, including those of the glans clitoris. The aim of this study is to characterize the corpuscular receptors of the glans clitoris. In addition, we compared basic features with the receptors of the glans penis. Number of stained receptors. Five cadaveric vulvectomy specimens and four cadaveric penile specimens were used. They were serially sectioned and stained with hematoxylin and eosin. Selected blocks were stained with Masson's trichrome, and immunohistochemical staining was done with neuronal markers S-100 and neurofilament. Using the three stains, we identified an abundance of corpuscular receptors within the glans clitoris, as compared with the surrounding prepuce. These receptors were of varied arrangements, situated in the subepithelial tissues of the glans clitoris. They were indistinguishable from the receptors of the glans penis. The number of receptors per 100× high-powered field ranged from 1 to 14, whereas the receptor density in the glans penis ranged from 1 to 3. A second type of receptor, the Pacinian corpuscle, was identified within the suspensory ligament along the trunks of the dorsal nerve but not within the glans itself. The glans clitoris is densely innervated with cutaneous corpuscular receptors, and these receptors are morphologically similar to the corpuscular receptors of the glans penis. The glans clitoris has greater variability in receptor density compared with the glans penis. © 2013 International Society for Sexual Medicine.

  17. Platelet dysfunction associated with the novel Trp29Cys thromboxane A₂ receptor variant.

    Science.gov (United States)

    Mumford, A D; Nisar, S; Darnige, L; Jones, M L; Bachelot-Loza, C; Gandrille, S; Zinzindohoue, F; Fischer, A-M; Mundell, S J; Gaussem, P

    2013-03-01

    Genetic variations that affect the structure of the thromboxane A2 receptor (TP receptor) provide insights into the function of this key platelet and vascular receptor, but are very rare in unselected populations. To determine the functional consequences of the TP receptor Trp29Cys (W29C) substitution. We performed a detailed phenotypic analysis of an index case (P1) with reduced platelet aggregation and secretion responses to TP receptor pathway activators, and a heterozygous TP receptor W29C substitution. An analysis of the variant W29C TP receptor expressed in heterologous cells was performed. Total TP receptor expression in platelets from P1 was similar to that of controls, but there was reduced maximum binding and reduced affinity of binding to the TP receptor antagonist [(3) H]SQ29548. HEK293 cells transfected with W29C TP receptor cDNA showed similar total TP receptor expression to wild-type (WT) controls. However, the TP receptor agonist U46619 was less potent at inducing rises in cytosolic free Ca(2+) in HEK293 cells expressing the W29C TP receptor than in WT controls, indicating reduced receptor function. Immunofluorescence microscopy and cell surface ELISA showed intracellular retention and reduced cell surface expression of the W29C TP receptor in HEK293 cells. Consistent with the platelet phenotype, both maximum binding and the affinity of binding of [(3) H]SQ29548 to the W29C TP receptor were reduced compared to WT controls. These findings extend the phenotypic description of the very rare disorder TP receptor deficiency, and show that the W29C substitution reduces TP receptor function by reducing surface receptor expression and by disrupting ligand binding. © 2012 International Society on Thrombosis and Haemostasis.

  18. Serotonin Receptors in Hippocampus

    Science.gov (United States)

    Berumen, Laura Cristina; Rodríguez, Angelina; Miledi, Ricardo; García-Alcocer, Guadalupe

    2012-01-01

    Serotonin is an ancient molecular signal and a recognized neurotransmitter brainwide distributed with particular presence in hippocampus. Almost all serotonin receptor subtypes are expressed in hippocampus, which implicates an intricate modulating system, considering that they can be localized as autosynaptic, presynaptic, and postsynaptic receptors, even colocalized within the same cell and being target of homo- and heterodimerization. Neurons and glia, including immune cells, integrate a functional network that uses several serotonin receptors to regulate their roles in this particular part of the limbic system. PMID:22629209

  19. International cooperation

    International Nuclear Information System (INIS)

    2008-01-01

    In this chapter international cooperation of the Division for Radiation Safety, NPP Decommissioning and Radwaste Management of the VUJE, a. s. is presented. Very important is cooperation with the International Atomic Energy Agency. This cooperation has various forms - national and regional projects of technical cooperation, coordinated research activities, participation of our experts in preparation of the IAEA documentation etc.

  20. International indsats

    DEFF Research Database (Denmark)

    Sachs, Therese

    En analyse af Beredskabsstyrelsens internationale engagement og muligheder for international indsats fremover. Forslag til struktur logistisk og materielt samt til udvikling af personel-kompetencer......En analyse af Beredskabsstyrelsens internationale engagement og muligheder for international indsats fremover. Forslag til struktur logistisk og materielt samt til udvikling af personel-kompetencer...

  1. International Curriculums.

    Science.gov (United States)

    Neal, Larry L.

    This workshop presentation on international curriculums in the field of parks, recreation, leisure, cultural services, and travel/tourism comments that the literature is replete with articles addressing what the field is about, but not about curriculum issues, models, and structure. It reports an international survey of 12 college educators…

  2. International Illiquidity

    DEFF Research Database (Denmark)

    Malkhozov, Aytek; Mueller, Philippe; Vedolin, Andrea

    -predicted effect of funding conditions on asset prices internationally. Global illiquidity lowers the slope and increases the intercept of the international security market line. Local illiquidity helps explain the variation in alphas, Sharpe ratios, and the performance of betting-against-beta (BAB) strategies...

  3. International relations

    International Nuclear Information System (INIS)

    Anon.

    2008-01-01

    Concerning international relations, the different meetings in the field of nuclear safety are reported (Western european nuclear regulator association or Wenra, Nea, IAEA, northern dimension environmental partnership or N.D.E.P., nuclear safety and security group or N.S.S.G., international nuclear regulators association or I.N.R.A.). (N.C.)

  4. Dynamic complexity: plant receptor complexes at the plasma membrane.

    Science.gov (United States)

    Burkart, Rebecca C; Stahl, Yvonne

    2017-12-01

    Plant receptor complexes at the cell surface perceive many different external and internal signalling molecules and relay these signals into the cell to regulate development, growth and immunity. Recent progress in the analyses of receptor complexes using different live cell imaging approaches have shown that receptor complex formation and composition are dynamic and take place at specific microdomains at the plasma membrane. In this review we focus on three prominent examples of Arabidopsis thaliana receptor complexes and how their dynamic spatio-temporal distribution at the PM has been studied recently. We will elaborate on the newly emerging concept of plasma membrane microdomains as potential hubs for specific receptor complex assembly and signalling outputs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Molecular mechanisms of platelet P2Y(12) receptor regulation.

    Science.gov (United States)

    Cunningham, Margaret R; Nisar, Shaista P; Mundell, Stuart J

    2013-02-01

    Platelets are critical for haemostasis, however inappropriate activation can lead to the development of arterial thrombosis, which can result in heart attack and stroke. ADP is a key platelet agonist that exerts its actions via stimulation of two surface GPCRs (G-protein-coupled receptors), P2Y(1) and P2Y(12). Similar to most GPCRs, P2Y receptor activity is tightly regulated by a number of complex mechanisms including receptor desensitization, internalization and recycling. In the present article, we review the molecular mechanisms that underlie P2Y(1) and P2Y(12) receptor regulation, with particular emphasis on the structural motifs within the P2Y(12) receptor, which are required to maintain regulatory protein interaction. The implications of these findings for platelet responsiveness are also discussed.

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

    Directory of Open Access Journals (Sweden)

    Harish Shankaran

    2007-06-01

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

  7. International Specialization

    DEFF Research Database (Denmark)

    Kleindienst, Ingo; Geisler Asmussen, Christian; Hutzschenreuter, Thomas

    2012-01-01

    Whether and how international diversification and cross-border arbitrage affects firm performance remains one of the major unresolved research questions in the strategy and international business literatures. We propose that knowing how much a firm has internationally diversified tells us very...... little about performance implications, if we do not know, and do not ask, how the firm has diversified. Therefore, building on the two broad arguments of operating flexibility and location-specific commitment, we develop a theoretical framework that focuses on the extent to which a firm's international...... arbitrage strategy is characterized by specialization versus replication and argue that these different strategies may have differential impact on profitability and risk reduction. Developing a sophisticated measure of international specialization and using a unique panel data set of 92 German MNEs to test...

  8. Investigating Internalization and Intracellular Trafficking of GPCRs

    DEFF Research Database (Denmark)

    Foster, Simon R; Bräuner-Osborne, Hans

    2017-01-01

    for signal transduction. One of the major mechanisms for GPCR regulation involves their endocytic trafficking, which serves to internalize the receptors from the plasma membrane and thereby attenuate G protein-dependent signaling. However, there is accumulating evidence to suggest that GPCRs can signal...... independently of G proteins, as well as from intracellular compartments including endosomes. It is in this context that receptor internalization and intracellular trafficking have attracted renewed interest within the GPCR field. In this chapter, we will review the current understanding and methodologies...

  9. Characterization of glucagon-like peptide-1 receptor beta-arrestin 2 interaction: a high-affinity receptor phenotype

    DEFF Research Database (Denmark)

    Jorgensen, Rasmus; Martini, Lene; Schwartz, Thue W

    2005-01-01

    To dissect the interaction between beta-arrestin ((beta)arr) and family B G protein-coupled receptors, we constructed fusion proteins between the glucagon-like peptide 1 receptor and (beta)arr2. The fusion constructs had an increase in apparent affinity selectively for glucagon, suggesting...... that (beta)arr2 interaction locks the receptor in a high-affinity conformation, which can be explored by some, but not all, ligands. The fusion constructs adopted a signaling phenotype governed by the tethered (beta)arr2 with an attenuated G protein-mediated cAMP signal and a higher maximal internalization...... of that which has previously been characterized for family A G protein-coupled receptors, suggesting similarities in the effect of (beta)arr interaction between family A and B receptors also at the molecular level....

  10. Structure and function of the IFNγ receptor on human mononuclear phagocytes

    International Nuclear Information System (INIS)

    Schreiber, R.D.; Celada, A.

    1986-01-01

    Human mononuclear phagocytes bear a receptor that binds 125 I-IFNγ in a saturable, reversible and specific manner. The receptor consists minimally of a 70 kD polypeptide chain and its expression (5000/cell) and binding affinity (Ka=10 9 M -1 ) are unaffected by cellular activation or differentiation. The receptor's biological relevance was validated by correlating receptor occupancy with induction of a cellular response. 50% maximal induction of Fc receptors on U937 was effected by 0.8 nM IFNγ; the same concentration needed to half saturate U937 IFNγ receptors. Ligand-receptor interaction displayed species specificity but not cellular specificity. The receptors on U937 and human fibroblasts displayed identical ligand binding affinities (1.5-1.8 x 10 9 M -1 ). At 37 0 C, IFNγ bound to U937 in a biphasic manner. The high affinity binding component was due to ligand internalization since purified cell membranes and paraformaldehyde fixed cells displayed only the lower Ka and ligand internalization could be directly demonstrated. Using lysosomotropic amines, the internalized IFNγ-IFNγ receptor complex was tracked into an acid compartment where dissociation occurred. Free intracellular IFNγ was then degraded while free receptor entered an intracellular pool and eventually recycled back to the cell surface

  11. International Health

    Science.gov (United States)

    ... create refugee populations with immediate and long-term health problems. Some of the major diseases currently affecting ... also an international problem which can affect people's health. Many countries and health organizations are working together ...

  12. Juris International

    CERN Document Server

    A database on international trade law aimed at lawyers and legal counsel in developing and transition economies. Juris International is a multilingual collection (English, Spanish, and French) of legal information on international trade. Juris International aims to facilitate and reduce the work involved in research for business lawyers, advisers and in-house counsel, and state organizations in developing nd transition economies, by providing access to texts which have often been difficult to obtain. Its objective is to gather a large quantity of basic information at one site (favoring complete legal texts), without the need to send for the information, and consequently without excessive communication costs for users who d benefit from an efficient and cheap telecommunications network.

  13. Microvesicle transfer of kinin B1-receptors is a novel inflammatory mechanism in vasculitis.

    Science.gov (United States)

    Kahn, Robin; Mossberg, Maria; Ståhl, Anne-Lie; Johansson, Karl; Lopatko Lindman, Ingrid; Heijl, Caroline; Segelmark, Mårten; Mörgelin, Matthias; Leeb-Lundberg, L M Fredrik; Karpman, Diana

    2017-01-01

    During vasculitis, activation of the kinin system induces inflammation, whereby the kinin B1-receptor is expressed and activated after ligand binding. Additionally, activated blood cells release microvesicles into the circulation. Here we determined whether leukocyte-derived microvesicles bear B1-kinin receptors during vasculitis, and if microvesicles transfer functional B1-receptors to recipient cells, thus promoting inflammation. By flow cytometry, plasma from patients with vasculitis were found to contain high levels of leukocyte-derived microvesicles bearing B1-receptors. Importantly, renal biopsies from two patients with vasculitis showed leukocyte-derived microvesicles bearing B1-receptors docking on glomerular endothelial cells providing in vivo relevance. Microvesicles derived from B1-receptor-transfected human embryonic kidney cells transferred B1-receptors to wild-type human embryonic kidney cells, lacking the receptor, and to glomerular endothelial cells. The transferred B1-receptors induced calcium influx after B1-receptor agonist stimulation: a response abrogated by a specific B1-receptor antagonist. Microvesicles derived from neutrophils also transferred B1-receptors to wild-type human embryonic kidney cells and induced calcium influx after stimulation. Thus, we found a novel mechanism by which microvesicles transfer functional receptors and promote kinin-associated inflammation. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  14. Thyrotropin modulates receptor-mediated processing of the atrial natriuretic peptide receptor in cultured thyroid cells

    International Nuclear Information System (INIS)

    Tseng, Y.L.; Burman, K.D.; Lahiri, S.; Abdelrahim, M.M.; D'Avis, J.C.; Wartofsky, L.

    1991-01-01

    In a prior study of atrial natriuretic peptide (ANP) binding to cultured thyroid cells, we reported that at 4 C, more than 95% of bound ANP is recovered on cell membranes, with negligible ANP internalization observed. Since ANP binding was inhibited by TSH, we have further studied TSH effects on postbinding ANP processing to determine whether this phenomenon reflects enhanced endocytosis of the ANP-receptor complex. An ANP chase study was initiated by binding [125I] ANP to thyroid cells at 4 C for 2 h, followed by incubation at 37 C. ANP processing was then traced by following 125I activity at various time intervals in three fractions: cell surface membranes, incubation medium, and inside the cells. Radioactivity released into medium represented processed ANP rather than ANP dissociated from surface membranes, since prebound [125I]ANP could not be competitively dissociated by a high concentration of ANP (1 mumol/L) at 37 C. Chase study results showed that prebound ANP quickly disappeared from cell membranes down to 34% by 30 min. Internalized ANP peaked at 10 min, with 21% of initial prebound ANP found inside the cells. At the same time, radioactivity recovered in incubation medium sharply increased between 10-30 min from 8% to 52%. Preincubation of cells with chloroquine (which blocks degradation of the ANP-receptor complex by inhibiting lysosomal hydrolase) caused a 146% increase in internalized [125I]ANP by 30 min (39% compared to 15% control), while medium radioactivity decreased from 52% to 16%, suggesting that processing of the receptor complex is mediated via lysosomal enzymes. In chase studies employing cells pretreated with chloroquine, TSH stimulated the internalization rate of ANP-receptor complex. By 30 min, TSH significantly reduced the membrane-bound ANP, and the decrease was inversely correlated to the increase in internalized radioactivity

  15. Regulating Internalities

    OpenAIRE

    Sunstein, Cass Robert; Allcott, Hunt

    2015-01-01

    This paper offers a framework for regulating internalities. Using a simple economic model, we provide four principles for designing and evaluating behaviorally-motivated policy. We then outline rules for determining which contexts reliably reflect true preferences and discuss empirical strategies for measuring internalities. As a case study, we focus on energy efficiency policy, including Corporate Average Fuel Economy (CAFE) standards and appliance and lighting energy efficiency standards.

  16. Particle compositions with a pre-selected cell internalization mode

    Science.gov (United States)

    Decuzzi, Paolo (Inventor); Ferrari, Mauro (Inventor)

    2012-01-01

    A method of formulating a particle composition having a pre-selected cell internalization mode involves selecting a target cell having surface receptors and obtaining particles that have i) surface moieties, that have an affinity for or are capable of binding to the surface receptors of the cell and ii) a preselected shape, where a surface distribution of the surface moieties on the particles and the shape of the particles are effective for the pre-selected cell internalization mode.

  17. Scintigraphic portrayal of β receptors in the heart

    International Nuclear Information System (INIS)

    Sisson, J.C.; Wieland, D.M.; Koeppe, R.A.; Normolle, D.; Frey, K.A.; Bolgos, G.; Johnson, J.; Van Dort, M.E.; Gildersleeve, D.L.

    1991-01-01

    Myocardial β adrenergic receptors play important roles in physiology and disease, but the receptors have not before been portrayed. The β antagonist, iodocyanopindolol (ICYP), was used to develop a scintigraphic method for depicting the receptors in the living heart. Labeled with 125I, ICYP bound firmly to β receptors in the rat heart; the data conformed to a mathematical model. In vivo saturation kinetics indicated binding sites with two affinities. Inhibition of ICYP binding by beta antagonists of different potency and different selectivity for β-1 and β-2 receptors produced the expected pharmacologic effects. Inhibition by lipophilic and hydrophilic antagonists gave no evidence that ICYP was appreciably bound to internalized receptors. Fractional binding by tracer quantities of (-) ICYP and ± ICYP demonstrated stereospecificity. Labeled with 123I, ICYP bound to the hearts of intact dogs so that scintigraphic tomographs depicted ventricular myocardium. Small doses of beta antagonists selectively reduced the binding of ICYP to lung enabling better visualization of the heart. Thus, 123I-ICYP appears to portray the beta receptors in the living heart, and the characteristics of binding permit the development of mathematical models and lay the basis for quantifying this receptor binding

  18. Inter-domain tagging implicates caveolin-1 in insulin receptor trafficking and Erk signaling bias in pancreatic beta-cells

    Directory of Open Access Journals (Sweden)

    Tobias Boothe

    2016-05-01

    Full Text Available Objective: The role and mechanisms of insulin receptor internalization remain incompletely understood. Previous trafficking studies of insulin receptors involved fluorescent protein tagging at their termini, manipulations that may be expected to result in dysfunctional receptors. Our objective was to determine the trafficking route and molecular mechanisms of functional tagged insulin receptors and endogenous insulin receptors in pancreatic beta-cells. Methods: We generated functional insulin receptors tagged with pH-resistant fluorescent proteins between domains. Confocal, TIRF and STED imaging revealed a trafficking pattern of inter-domain tagged insulin receptors and endogenous insulin receptors detected with antibodies. Results: Surprisingly, interdomain-tagged and endogenous insulin receptors in beta-cells bypassed classical Rab5a- or Rab7-mediated endocytic routes. Instead, we found that removal of insulin receptors from the plasma membrane involved tyrosine-phosphorylated caveolin-1, prior to trafficking within flotillin-1-positive structures to lysosomes. Multiple methods of inhibiting caveolin-1 significantly reduced Erk activation in vitro or in vivo, while leaving Akt signaling mostly intact. Conclusions: We conclude that phosphorylated caveolin-1 plays a role in insulin receptor internalization towards lysosomes through flotillin-1-positive structures and that caveolin-1 helps bias physiological beta-cell insulin signaling towards Erk activation. Author Video: Author Video Watch what authors say about their articles Keywords: Insulin receptor internalization, Insulin resistance, Pancreatic islet beta-cells, Autocrine insulin signaling

  19. Ionotropic crustacean olfactory receptors.

    Directory of Open Access Journals (Sweden)

    Elizabeth A Corey

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

  20. International Criminalization of International Terrorizm

    Directory of Open Access Journals (Sweden)

    Alexander Grigoryevich Volevodz

    2014-01-01

    Full Text Available Analysis and studying of the terrorism in all its facets is a complex entangled problem with less clear legal regulation that it might seem at first glance, especially after its transformation from local phenomenon into a world threat. Hitherto terrorism and actions connected to it have been criminalized by the majority of states. There are in modern criminal law whole systems of rules on criminal liability for terrorism which differs considerably from country to country. Terrorism has been criminalized in numerous international regional and universal antiterrorist legal instruments. The author notes that differences in definitions that are enshrined in them hinders international cooperation in criminal matters with respect to terrorist cases. Difficulties reside in the necessity to meet the dual criminality requirement and in the political offense exception. These difficulties can only be overcome through elaboration of a universally recognized definition of the notion of international terrorism and making it legally binding via its inclusion into a universal convention. The issue of definition of international terrorism is an important part of an efficient mutual assistance among states in fight against this crime. In this article the author accounts of actual ways of tackling by the international community of the issue of criminalization of international terrorism and of factors influencing them.

  1. International Relations:

    DEFF Research Database (Denmark)

    This is the textbook for the Open University module International Relations: Continuity and Change in Global Politics. Instead of leading with a succession of theoretical 'isms', the module structures its presentation of the subject around six teaching ‘blocks’, each of which explores a dilemma...... • Block 6: Continuity or change in global politics? Each block introduces new IR theories through discussions of the substantive dilemmas and adds in a layered way levels of analysis and conceptual complexity......., or dimension of variation. The dilemmas in question were chosen for the way they capture key themes in the field of International Studies (IR) as well as central aspects of the ‘international’ itself (ir). The six Blocks are: • Block 1: Co-operation or conflict? Introducing international relations • Block 2...

  2. International cooperation

    International Nuclear Information System (INIS)

    Prieto, F.E.

    1984-01-01

    It looks doubtless that the need for an international cooperation to solve the worldwide energy problems is already a concern of individuals, institutions, and governments. This is an improvement. But there is something lacking. The author refers to the Atoms for Peace speech, the origin of the IAEA and of the subsequent spreading of the nuclear option. He also refers back to the call made by the Mexican government for a worldwide energy cooperation. He stresses the need for governments to cooperate, so that this international cooperation on energy can be put into operation for the benefit of mankind

  3. International collaboration

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    In the wake of the demise of the US Superconducting Supercollider (SSC) project last year which empoverished both US and world science, some rapid scene shifting is going on. The SSC may be dead, but the underlying physics quest lives on. In the US, the 'future vision' subpanel of the High Energy Physics Advisory Board (HEPAP) is at work formulating its recommendations. On the international front, the International Committee for Future Accelerators (ICFA) at a special meeting in Vancouver in January drafted a statement

  4. Assays for calcitonin receptors

    International Nuclear Information System (INIS)

    Teitelbaum, A.P.; Nissenson, R.A.; Arnaud, C.D.

    1985-01-01

    The assays for calcitonin receptors described focus on their use in the study of the well-established target organs for calcitonin, bone and kidney. The radioligand used in virtually all calcitonin binding studies is 125 I-labelled salmon calcitonin. The lack of methionine residues in this peptide permits the use of chloramine-T for the iodination reaction. Binding assays are described for intact bone, skeletal plasma membranes, renal plasma membranes, and primary kidney cell cultures of rats. Studies on calcitonin metabolism in laboratory animals and regulation of calcitonin receptors are reviewed

  5. Transparency International

    NARCIS (Netherlands)

    Hulten, van M. (Michel)

    2009-01-01

    Established in 1993, Transparency International (TI) defines itself as “the global civil society organization leading the fight against corruption, that brings people together in a powerful worldwide coalition to end the devastating impact of corruption on men, women and children around the

  6. International Entomology

    Science.gov (United States)

    Pests and diseases of plants in agriculture are a shared international problem. Yet some of the very places that pest invaders come from often lack the institutional structure and organization necessary to help in understanding the biology of the pest or disease. Strengthening entomology by stimulat...

  7. International safeguards

    International Nuclear Information System (INIS)

    Sanders, B.; Ha Vinh Phuong

    1976-01-01

    Since the start of the post-war era, international safeguards were considered essential to ensure that nuclear materials should not be diverted to unauthorised uses. In parallel, it was proposed to set up an international atomic energy agency within the United Nations through which international cooperation in nuclear matters would be channelled and controlled. Created in 1957, the IAEA was authorized to administer safeguards in connection with any assistance it provided as well as at the request of Member State and of any party to bilateral or multilateral arrangements in its ambit. Today, there are two international treaties requiring that its parties should accept Agency safeguards unilaterally, the Latin America Tlatelolco Treaty of 1967, and the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), operative since 1970, which requires in particular that non-nuclear weapon states should accept Agency safeguards on its peaceful nuclear activities. Thus while NPT covers peaceful nuclear activities indiscriminately in a country, the Agency's original safeguards system is applied according to specific agreements and to given facilities. A basic conflict has now emerged between commercial interests and the increasing wish that transfer of nuclear equipment and know-how should not result in proliferation of military nuclear capacity; however, serious efforts are currently in progress to ensure universal application of IAEA safeguards and to develop them in step with the uses of nuclear energy. (N.E.A.) [fr

  8. Fibroblast Activation Protein (FAP) Accelerates Collagen Degradation and Clearance from Lungs in Mice*

    Science.gov (United States)

    Fan, Ming-Hui; Zhu, Qiang; Li, Hui-Hua; Ra, Hyun-Jeong; Majumdar, Sonali; Gulick, Dexter L.; Jerome, Jacob A.; Madsen, Daniel H.; Christofidou-Solomidou, Melpo; Speicher, David W.; Bachovchin, William W.; Feghali-Bostwick, Carol; Puré, Ellen

    2016-01-01

    Idiopathic pulmonary fibrosis is a disease characterized by progressive, unrelenting lung scarring, with death from respiratory failure within 2–4 years unless lung transplantation is performed. New effective therapies are clearly needed. Fibroblast activation protein (FAP) is a cell surface-associated serine protease up-regulated in the lungs of patients with idiopathic pulmonary fibrosis as well as in wound healing and cancer. We postulate that FAP is not only a marker of disease but influences the development of pulmonary fibrosis after lung injury. In two different models of pulmonary fibrosis, intratracheal bleomycin instillation and thoracic irradiation, we find increased mortality and increased lung fibrosis in FAP-deficient mice compared with wild-type mice. Lung extracellular matrix analysis reveals accumulation of intermediate-sized collagen fragments in FAP-deficient mouse lungs, consistent with in vitro studies showing that FAP mediates ordered proteolytic processing of matrix metalloproteinase (MMP)-derived collagen cleavage products. FAP-mediated collagen processing leads to increased collagen internalization without altering expression of the endocytic collagen receptor, Endo180. Pharmacologic FAP inhibition decreases collagen internalization as expected. Conversely, restoration of FAP expression in the lungs of FAP-deficient mice decreases lung hydroxyproline content after intratracheal bleomycin to levels comparable with that of wild-type controls. Our findings indicate that FAP participates directly, in concert with MMPs, in collagen catabolism and clearance and is an important factor in resolving scar after injury and restoring lung homeostasis. Our study identifies FAP as a novel endogenous regulator of fibrosis and is the first to show FAP's protective effects in the lung. PMID:26663085

  9. Fluorescent ligands for studying neuropeptide receptors by confocal microscopy

    Directory of Open Access Journals (Sweden)

    A. Beaudet

    1998-11-01

    Full Text Available This paper reviews the use of confocal microscopy as it pertains to the identification of G-protein coupled receptors and the study of their dynamic properties in cell cultures and in mammalian brain following their tagging with specific fluorescent ligands. Principles that should guide the choice of suitable ligands and fluorophores are discussed. Examples are provided from the work carried out in the authors' laboratory using custom synthetized fluoresceinylated or BODIPY-tagged bioactive peptides. The results show that confocal microscopic detection of specifically bound fluorescent ligands permits high resolution appraisal of neuropeptide receptor distribution both in cell culture and in brain sections. Within the framework of time course experiments, it also allows for a dynamic assessment of the internalization and subsequent intracellular trafficking of bound fluorescent molecules. Thus, it was found that neurotensin, somatostatin and mu- and delta-selective opioid peptides are internalized in a receptor-dependent fashion and according to receptor-specific patterns into their target cells. In the case of neurotensin, this internalization process was found to be clathrin-mediated, to proceed through classical endosomal pathways and, in neurons, to result in a mobilization of newly formed endosomes from neural processes to nerve cell bodies and from the periphery of cell bodies towards the perinuclear zone. These mechanisms are likely to play an important role for ligand inactivation, receptor regulation and perhaps also transmembrane signaling.

  10. Angiotensin type 2 receptor (AT2R) and receptor Mas

    DEFF Research Database (Denmark)

    Villela, Daniel; Leonhardt, Julia; Patel, Neal

    2015-01-01

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

  11. Smart dual-functional warhead for folate receptor-specific activatable imaging and photodynamic therapy.

    Science.gov (United States)

    Kim, Jisu; Tung, Ching-Hsuan; Choi, Yongdoo

    2014-09-21

    A smart dual-targeted theranostic agent becomes highly fluorescent and phototoxic only when its linker is cleaved by tumor-associated lysosomal enzyme cathepsin B after internalization into folate receptor-positive cancer cells.

  12. Tracking Cell Surface GABAB Receptors Using an α-Bungarotoxin Tag*

    Science.gov (United States)

    Wilkins, Megan E.; Li, Xinyan; Smart, Trevor G.

    2008-01-01

    GABAB receptors mediate slow synaptic inhibition in the central nervous system and are important for synaptic plasticity as well as being implicated in disease. Located at pre- and postsynaptic sites, GABAB receptors will influence cell excitability, but their effectiveness in doing so will be dependent, in part, on their trafficking to, and stability on, the cell surface membrane. To examine the dynamic behavior of GABAB receptors in GIRK cells and neurons, we have devised a method that is based on tagging the receptor with the binding site components for the neurotoxin, α-bungarotoxin. By using the α-bungarotoxin binding site-tagged GABAB R1a subunit (R1aBBS), co-expressed with the R2 subunit, we can track receptor mobility using the small reporter, α-bungarotoxin-conjugated rhodamine. In this way, the rates of internalization and membrane insertion for these receptors could be measured with fixed and live cells. The results indicate that GABAB receptors rapidly turnover in the cell membrane, with the rate of internalization affected by the state of receptor activation. The bungarotoxin-based method of receptor-tagging seems ideally suited to follow the dynamic regulation of other G-protein-coupled receptors. PMID:18812318

  13. Tracking cell surface GABAB receptors using an alpha-bungarotoxin tag.

    Science.gov (United States)

    Wilkins, Megan E; Li, Xinyan; Smart, Trevor G

    2008-12-12

    GABA(B) receptors mediate slow synaptic inhibition in the central nervous system and are important for synaptic plasticity as well as being implicated in disease. Located at pre- and postsynaptic sites, GABA(B) receptors will influence cell excitability, but their effectiveness in doing so will be dependent, in part, on their trafficking to, and stability on, the cell surface membrane. To examine the dynamic behavior of GABA(B) receptors in GIRK cells and neurons, we have devised a method that is based on tagging the receptor with the binding site components for the neurotoxin, alpha-bungarotoxin. By using the alpha-bungarotoxin binding site-tagged GABA(B) R1a subunit (R1a(BBS)), co-expressed with the R2 subunit, we can track receptor mobility using the small reporter, alpha-bungarotoxin-conjugated rhodamine. In this way, the rates of internalization and membrane insertion for these receptors could be measured with fixed and live cells. The results indicate that GABA(B) receptors rapidly turnover in the cell membrane, with the rate of internalization affected by the state of receptor activation. The bungarotoxin-based method of receptor-tagging seems ideally suited to follow the dynamic regulation of other G-protein-coupled receptors.

  14. Adenosine A(2A) receptor dynamics studied with the novel fluorescent agonist Alexa488-APEC.

    Science.gov (United States)

    Brand, Frank; Klutz, Athena M; Jacobson, Kenneth A; Fredholm, Bertil B; Schulte, Gunnar

    2008-08-20

    G protein-coupled receptors, such as the adenosine A(2A) receptor, are dynamic proteins, which undergo agonist-dependent redistribution from the cell surface to intracellular membranous compartments, such as endosomes. In order to study the kinetics of adenosine A(2A) receptor redistribution in living cells, we synthesized a novel fluorescent agonist, Alexa488-APEC. Alexa488-APEC binds to adenosine A(2A) (K(i)=149+/-27 nM) as well as A(3) receptors (K(i)=240+/-160 nM) but not to adenosine A(1) receptors. Further, we characterized the dose-dependent increase in Alexa488-APEC-induced cAMP production as well as cAMP response element binding (CREB) protein phosphorylation, verifying the ligand's functionality at adenosine A(2A) but not A(2B) receptors. In live-cell imaging studies, Alexa488-APEC-induced adenosine A(2A) receptor internalization, which was blocked by the competitive reversible antagonist ZM 241385 and hyperosmolaric sucrose. Further, internalized adenosine A(2A) receptors co-localized with clathrin and Rab5, indicating that agonist stimulation promotes adenosine A(2A) receptor uptake through a clathrin-dependent mechanism to Rab5-positive endosomes. The basic characterization of Alexa488-APEC described here showed that it provides a useful tool for tracing adenosine A(2A) receptors in vitro.

  15. TLX: An elusive receptor.

    Science.gov (United States)

    Benod, Cindy; Villagomez, Rosa; Webb, Paul

    2016-03-01

    TLX (tailless receptor) is a member of the nuclear receptor superfamily and belongs to a class of nuclear receptors for which no endogenous or synthetic ligands have yet been identified. TLX is a promising therapeutic target in neurological disorders and brain tumors. Thus, regulatory ligands for TLX need to be identified to complete the validation of TLX as a useful target and would serve as chemical probes to pursue the study of this receptor in disease models. It has recently been proved that TLX is druggable. However, to identify potent and specific TLX ligands with desirable biological activity, a deeper understanding of where ligands bind, how they alter TLX conformation and of the mechanism by which TLX mediates the transcription of its target genes is needed. While TLX is in the process of escaping from orphanhood, future ligand design needs to progress in parallel with improved understanding of (i) the binding cavity or surfaces to target with small molecules on the TLX ligand binding domain and (ii) the nature of the TLX coregulators in particular cell and disease contexts. Both of these topics are discussed in this review. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Glutamate receptor ligands

    DEFF Research Database (Denmark)

    Guldbrandt, Mette; Johansen, Tommy N; Frydenvang, Karla Andrea

    2002-01-01

    Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA...

  17. Ginkgolides and glycine receptors

    DEFF Research Database (Denmark)

    Jaracz, Stanislav; Nakanishi, Koji; Jensen, Anders A.

    2004-01-01

    Ginkgolides from the Ginkgo biloba tree are diterpenes with a cage structure consisting of six five-membered rings and a unique tBu group. They exert a variety of biological properties. In addition to being antagonists of the platelet activating factor receptor (PAFR), it has recently been shown ...

  18. adrenergic receptor with preeclampsia

    African Journals Online (AJOL)

    User

    2011-05-09

    May 9, 2011 ... due to a post- receptor defect (Karadas et al., 2007). Several polymorphisms have ... the detection of the Arg16Gly polymorphism, overnight digestion at. 37°C with 10 U ..... DW, Wood AJ, Stein CM (2004). Beta2-adrenoceptor ...

  19. Metformin and insulin receptors

    International Nuclear Information System (INIS)

    Vigneri, R.; Gullo, D.; Pezzino, V.

    1984-01-01

    The authors evaluated the effect of metformin (N,N-dimethylbiguanide), a biguanide known to be less toxic than phenformin, on insulin binding to its receptors, both in vitro and in vivo. Specific 125 I-insulin binding to cultured IM-9 human lymphocytes and MCF-7 human breast cancer cells was determined after preincubation with metformin. Specific 125 I-insulin binding to circulating monocytes was also evaluated in six controls, eight obese subjects, and six obese type II diabetic patients before and after a short-term treatment with metformin. Plasma insulin levels and blood glucose were also measured on both occasions. Metformin significantly increased insulin binding in vitro to both IM-9 lymphocytes and MCF-7 cells; the maximum increment was 47.1% and 38.0%, respectively. Metformin treatment significantly increased insulin binding in vivo to monocytes of obese subjects and diabetic patients. Scatchard analysis indicated that the increased binding was mainly due to an increase in receptor capacity. Insulin binding to monocytes of normal controls was unchanged after metformin as were insulin levels in all groups; blood glucose was significantly reduced after metformin only in diabetic patients. These data indicate that metformin increases insulin binding to its receptors in vitro and in vivo. The effect in vivo is observed in obese subjects and in obese type II diabetic patients, paralleling the clinical effectiveness of this antidiabetic agent, and is not due to receptor regulation by circulating insulin, since no variation in insulin levels was recorded

  20. Internal pump

    International Nuclear Information System (INIS)

    Kushima, Jun; Hayashi, Youjiro; Ueda, Masayuki.

    1997-01-01

    The present invention relates to an internal pump. A water hole allowing communication between internal and external circumferences of a stretch tube is provided at the portion of the stretch tube corresponding to a position where an end face of a nozzle portion of a motor case and an end face of a diffuser are joined with each other so that hot filtered water inside a pressure container which has entered from where the end face of the nozzle portion of the motor case and the end face of the diffuser are joined with each other is combined with the purged water so that it can be sent back to the pressure container again. (author) figs

  1. Immune inhibitory receptors in viral infection and cancer

    NARCIS (Netherlands)

    Karnam, G.

    2014-01-01

    We are protected from external and internal dangers by our immune system. Immune responses need to be balanced to prevent uncontrolled inflammation and/or autoimmunity. Cell growth inhibition, apoptosis, and down regulation of receptor signals are all part of the inhibitory tools used by the immune

  2. International safeguards

    International Nuclear Information System (INIS)

    1995-01-01

    The system of international safeguards carried out by the IAEA is designed to verify that governments are living up to pledges to use nuclear energy only for peaceful purposes under the NPT (Treaty on the non-proliferation of nuclear weapons) and similar agreements. The film illustrates the range of field inspections and analytical work involved. It also shows how new approaches are helping to strengthen the system

  3. Olfactory Receptor Database: a sensory chemoreceptor resource

    OpenAIRE

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

    2000-01-01

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

  4. International cooperation

    International Nuclear Information System (INIS)

    1996-01-01

    In 1995, Nuclear Regulatory Authority of the Slovak Republic (NRA SR) ensured foreign cooperation particularly in the frame of the Slovak Republic is membership in the IAEA, as well as cooperation with the Nuclear Energy Agency of the Organization for Economic Cooperation and Development (OECD NEA), cooperation with European Union in the frame of PHARE programmes, and intergovernmental cooperation and cooperation among nuclear regulatory authorities. With respect to an international importance, prestige and a wide-scope possibilities of a technical assistance , either a direct one (expert assessments, technology supplies, work placement, scientific trips, training courses) or indirect one (participation at various conferences, seminars, technical committees, etc), the most important cooperation with the IAEA in Vienna. In 1994, the Slovak Republic, was elected to the Board Governors, the represent the group of Eastern European countries. The Slovak Government entrusted the NRA SR's Chairman with representing the Slovak Republic in the Board of Governors. Owing to a good name of Slovakia was elected to the one of two Vice-Chairmen of the Board of Governors at the 882-nd session on the Board. IAEA approved and developed 8 national projects for Slovakia in 1995. Generally, IAEA is contracting scientific contracts with research institutes, nuclear power plants and other organizations. Slovak organizations used these contracts as complementary funding of their tasks. In 1995, there were 12 scientific contracts in progress, or approved respectively. Other international activities of the NRA SR, international co-operations as well as foreign affairs are reported

  5. Bombyx neuropeptide G protein-coupled receptor A7 is the third cognate receptor for short neuropeptide F from silkworm.

    Science.gov (United States)

    Ma, Qiang; Cao, Zheng; Yu, Yena; Yan, Lili; Zhang, Wenjuan; Shi, Ying; Zhou, Naiming; Huang, Haishan

    2017-12-15

    The short neuropeptide F (sNPF) neuropeptides, closely related to vertebrate neuropeptide Y (NPY), have been suggested to exert pleiotropic effects on many physiological processes in insects. In the silkworm ( Bombyx mori ) two orphan G protein-coupled receptors, Bombyx neuropeptide G protein-coupled receptor (BNGR) A10 and A11, have been identified as cognate receptors for sNPFs, but other sNPF receptors and their signaling mechanisms in B. mori remain unknown. Here, we cloned the full-length cDNA of the orphan receptor BNGR-A7 from the brain of B. mori larvae and identified it as a receptor for Bombyx sNPFs. Further characterization of signaling and internalization indicated that BNGR-A7, -A10, and -A11 are activated by direct interaction with synthetic Bombyx sNPF-1 and -3 peptides. This activation inhibited forskolin or adipokinetic hormone-induced adenylyl cyclase activity and intracellular Ca 2+ mobilization via a G i/o -dependent pathway. Upon activation by sNPFs, BNGR-A7, -A10, and -A11 evoked ERK1/2 phosphorylation and underwent internalization. On the basis of these findings, we designated the receptors BNGR-A7, -A10, and -A11 as Bommo -sNPFR-1, -2, and -3, respectively. Moreover, the results obtained with quantitative RT-PCR analysis revealed that the three Bombyx sNPF receptor subtypes exhibit differential spatial and temporal expression patterns, suggesting possible roles of sNPF signaling in the regulation of a wide range of biological processes. Our findings provide the first in-depth information on sNPF signaling for further elucidation of the roles of the Bombyx sNPF/sNPFR system in the regulation of physiological activities. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Prostaglandin Receptor Signaling in Disease

    Directory of Open Access Journals (Sweden)

    Toshiyuki Matsuoka

    2007-01-01

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

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

    Science.gov (United States)

    Keegan, A D; Pierce, J H

    1994-02-01

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

  8. [Gradient of serotonergic innervation of internal organs].

    Science.gov (United States)

    Lychkova, A E

    2004-01-01

    The unidirectional synergistic effect of the vegetative nervous system departments was studied at the regulation of the activity of internal organs. It was shown that the sympathetic nerve intensification of the vagal stimulation of EMA of stomach, urinary bladder, ureters, uteruss, fallopian tubes and deferent duct is realized by means of activation of serotonergic fibrae preganglionares that transmit the activation to 5-NTS,4 serotonin receptors of intramural ganglia that, in their turn, activate 5-NT1,2 serotonin receptors of effector cells.

  9. Meeting report: nuclear receptors

    DEFF Research Database (Denmark)

    Tuckermann, Jan; Bourguet, William; Mandrup, Susanne

    2010-01-01

    The biannual European Molecular Biology Organization (EMBO) conference on nuclear receptors was organized by Beatrice Desvergne and Laszlo Nagy and took place in Cavtat near Dubrovnik on the Adriatic coast of Croatia September 25-29, 2009. The meeting brought together researchers from all over...... the world covering a wide spectrum from fundamental mechanistic studies to metabolism, clinical studies, and drug development. In this report, we summarize the recent and exciting findings presented by the speakers at the meeting....

  10. Neurotransmitter receptor imaging

    International Nuclear Information System (INIS)

    Cordes, M.; Hierholzer, J.; Nikolai-Beyer, K.

    1993-01-01

    The importance of neuroreceptor imaging in vivo using single photon emission tomography (SPECT) and positron emission tomography (PET) has increased enormously. The principal neurotransmitters, such as dopamine, GABA/benzodiazepine, acetylcholine, and serotonin, are presented with reference to anatomical, biochemical, and physiological features. The main radioligands for SPECT and PET are introduced, and methodological characteristics of both PET and SPECT presented. Finally, the results of neurotransmitter receptor imaging obtained so far will be discussed. (orig.) [de

  11. Thyroid Stimulating Hormone Receptor

    Directory of Open Access Journals (Sweden)

    Murat Tuncel

    2017-02-01

    Full Text Available Thyroid stimulating hormone receptor (TSHR plays a pivotal role in thyroid hormone metabolism. It is a major controller of thyroid cell function and growth. Mutations in TSHR may lead to several thyroid diseases, most commonly hyperthyroidism. Although its genetic and epigenetic alterations do not directly lead to carcinogenesis, it has a crucial role in tumor growth, which is initiated by several oncogenes. This article will provide a brief review of TSHR and related diseases.

  12. Quantitative Impact of Plasma Clearance and Down-regulation on GLP-1 Receptor Molecular Imaging.

    Science.gov (United States)

    Zhang, Liang; Thurber, Greg M

    2016-02-01

    Quantitative molecular imaging of beta cell mass (BCM) would enable early detection and treatment monitoring of type 1 diabetes. The glucagon-like peptide-1 (GLP-1) receptor is an attractive target due to its beta cell specificity and cell surface location. We quantitatively investigated the impact of plasma clearance and receptor internalization on targeting efficiency in healthy B6 mice. Four exenatide-based probes were synthesized that varied in molecular weight, binding affinity, and plasma clearance. The GLP-1 receptor internalization rate and in vivo receptor expression were quantified. Receptor internalization (54,000 receptors/cell in vivo) decreased significantly within minutes, reducing the benefit of a slower-clearing agent. The multimers and albumin binding probes had higher kidney and liver uptake, respectively. Slow plasma clearance is beneficial for GLP-1 receptor peptide therapeutics. However, for exendin-based imaging of islets, down-regulation of the GLP-1 receptor and non-specific background uptake result in a higher target-to-background ratio for fast-clearing agents.

  13. Internal education

    Directory of Open Access Journals (Sweden)

    Anita Zagorc

    2016-09-01

    Full Text Available Research Question (RQ: The importance of internal trainings in an organization. Purpose: The purpose of research is to examine and present internal trainings in an organization and their contribution to greater success of an organization. The paper studies employee training in a company, how the organization itself looks after its employees during training, how trainings contribute to further development of organization and the advancement of knowledge for successful operation of organization. Method: How to achieve the purpose of research, used methods and theoretical approach. Results: Specific examples and opinions of employees. Results show the importance of trainings for an organization. We can see that all employees are fairly motivated and ready to participate in trainings and can adapt to changing business environment very well. The results demonstrate that all trainings in the organization are very important and welcome. Only with continuous learning, the organization can be successful and survive in the market despite strong competition. Organization: Trainings are designed for all employees inside an organization. Different employees participate in trainings in a different way as all trainings are divided into certain work and fields that are important for each individual or department in an organization. Society: Trainings have an impact on the whole organization by contributing to its development. Originality: The originality of study is what was new in the research, what is the value and originality of research. Limitations/Future Research: Research was limited to a small number of sources.

  14. A highly sensitive quantitative cytosensor technique for the identification of receptor ligands in tissue extracts.

    Science.gov (United States)

    Lenkei, Z; Beaudet, A; Chartrel, N; De Mota, N; Irinopoulou, T; Braun, B; Vaudry, H; Llorens-Cortes, C

    2000-11-01

    Because G-protein-coupled receptors (GPCRs) constitute excellent putative therapeutic targets, functional characterization of orphan GPCRs through identification of their endogenous ligands has great potential for drug discovery. We propose here a novel single cell-based assay for identification of these ligands. This assay involves (a) fluorescent tagging of the GPCR, (b) expression of the tagged receptor in a heterologous expression system, (c) incubation of the transfected cells with fractions purified from tissue extracts, and (d) imaging of ligand-induced receptor internalization by confocal microscopy coupled to digital image quantification. We tested this approach in CHO cells stably expressing the NT1 neurotensin receptor fused to EGFP (enhanced green fluorescent protein), in which neurotensin promoted internalization of the NT1-EGFP receptor in a dose-dependent fashion (EC(50) = 0.98 nM). Similarly, four of 120 consecutive reversed-phase HPLC fractions of frog brain extracts promoted internalization of the NT1-EGFP receptor. The same four fractions selectively contained neurotensin, an endogenous ligand of the NT1 receptor, as detected by radioimmunoassay and inositol phosphate production. The present internalization assay provides a highly specific quantitative cytosensor technique with sensitivity in the nanomolar range that should prove useful for the identification of putative natural and synthetic ligands for GPCRs.

  15. ARF6-dependent regulation of P2Y receptor traffic and function in human platelets.

    Science.gov (United States)

    Kanamarlapudi, Venkateswarlu; Owens, Sian E; Saha, Keya; Pope, Robert J; Mundell, Stuart J

    2012-01-01

    Adenosine diphosphate (ADP) is a critical regulator of platelet activation, mediating its actions through two G protein-coupled receptors, the P2Y(1) and P2Y(12) purinoceptors. Recently, we demonstrated that P2Y(1) and P2Y(12) purinoceptor activities are rapidly and reversibly modulated in human platelets, revealing that the underlying mechanism requires receptor internalization and subsequent trafficking as an essential part of this process. In this study we investigated the role of the small GTP-binding protein ADP ribosylation factor 6 (ARF6) in the internalization and function of P2Y(1) and P2Y(12) purinoceptors in human platelets. ARF6 has been implicated in the internalization of a number of GPCRs, although its precise molecular mechanism in this process remains unclear. In this study we show that activation of either P2Y(1) or P2Y(12) purinoceptors can stimulate ARF6 activity. Further blockade of ARF6 function either in cell lines or human platelets blocks P2Y purinoceptor internalization. This blockade of receptor internalization attenuates receptor resensitization. Furthermore, we demonstrate that Nm23-H1, a nucleoside diphosphate (NDP) kinase regulated by ARF6 which facilitates dynamin-dependent fission of coated vesicles during endocytosis, is also required for P2Y purinoceptor internalization. These data describe a novel function of ARF6 in the internalization of P2Y purinoceptors and demonstrate the integral importance of this small GTPase upon platelet ADP receptor function.

  16. ARF6-dependent regulation of P2Y receptor traffic and function in human platelets.

    Directory of Open Access Journals (Sweden)

    Venkateswarlu Kanamarlapudi

    Full Text Available Adenosine diphosphate (ADP is a critical regulator of platelet activation, mediating its actions through two G protein-coupled receptors, the P2Y(1 and P2Y(12 purinoceptors. Recently, we demonstrated that P2Y(1 and P2Y(12 purinoceptor activities are rapidly and reversibly modulated in human platelets, revealing that the underlying mechanism requires receptor internalization and subsequent trafficking as an essential part of this process. In this study we investigated the role of the small GTP-binding protein ADP ribosylation factor 6 (ARF6 in the internalization and function of P2Y(1 and P2Y(12 purinoceptors in human platelets. ARF6 has been implicated in the internalization of a number of GPCRs, although its precise molecular mechanism in this process remains unclear. In this study we show that activation of either P2Y(1 or P2Y(12 purinoceptors can stimulate ARF6 activity. Further blockade of ARF6 function either in cell lines or human platelets blocks P2Y purinoceptor internalization. This blockade of receptor internalization attenuates receptor resensitization. Furthermore, we demonstrate that Nm23-H1, a nucleoside diphosphate (NDP kinase regulated by ARF6 which facilitates dynamin-dependent fission of coated vesicles during endocytosis, is also required for P2Y purinoceptor internalization. These data describe a novel function of ARF6 in the internalization of P2Y purinoceptors and demonstrate the integral importance of this small GTPase upon platelet ADP receptor function.

  17. G protein-coupled receptors: the inside story.

    Science.gov (United States)

    Jalink, Kees; Moolenaar, Wouter H

    2010-01-01

    Recent findings necessitate revision of the traditional view of G protein-coupled receptor (GPCR) signaling and expand the diversity of mechanisms by which receptor signaling influences cell behavior in general. GPCRs elicit signals at the plasma membrane and are then rapidly removed from the cell surface by endocytosis. Internalization of GPCRs has long been thought to serve as a mechanism to terminate the production of second messengers such as cAMP. However, recent studies show that internalized GPCRs can continue to either stimulate or inhibit cAMP production in a sustained manner. They do so by remaining associated with their cognate G protein subunit and adenylyl cyclase at endosomal compartments. Once internalized, the GPCRs produce cellular responses distinct from those elicited at the cell surface.

  18. Ligand-receptor Interactions by NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Novak. P.

    2008-04-01

    Full Text Available Today NMR spectroscopy is a method of choice for elucidation of interactions between biomolecules and the potential ligands. Knowledge on these interactions is an essential prerequisite for the rational drug design. The most important contribution of NMR to drug design a few years ago was the 3D structure determination of proteins. Besides delivering the 3D structures of the free proteins as a raw material for the modeling studies on ligand binding, NMR can directly yield valuable experimental data on the biologically important protein-ligand complexes. In addition to X-ray diffraction, NMR spectroscopy can provide information on the internal protein dynamics ordynamics of intermolecular interactions. Changes in NMR parameters allow us to detect ("SAR by NMR" and quantitatively determine binding affinities (titration, diffusion NMR experiments, etc. of potential ligands. Also, it is possible to determine the binding site and conformations of ligands, receptors and receptor-ligand complexes with the help of NMR methods such as tr-NOESY. Epitopes or functional groups responsible for binding of ligands to the receptor can be identified by employing STD or WaterLOGSY experiments. In this review are described some of the most frequent NMR methods for the characterization of the interactions between biomolecules and ligands, together with their advantages and disadvantages.

  19. Melatonin Receptor Genes in Vertebrates

    Directory of Open Access Journals (Sweden)

    Hua Dong Yin

    2013-05-01

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

  20. International safeguards

    International Nuclear Information System (INIS)

    Petit, A.

    1991-01-01

    The IAEA has now 200 Inspectors or so, and Euratom a similar number. People in Vienna are talking about increases of this staff, in the range of a possible doubling in the five years to come, although even an immediate restart of the expansion of nuclear industry, would not materialize significantly within this period. This means that keeping the same safeguarding approach would probably lead to another doubling of such staff in the ten following years, which is completely unrealistic. Such a staff is our of proportion with those of national inspectorates in other fields. The paper analyzes the basic irrealistic dogma which have hindered the progress of international safeguards, and recall the suggestions made since ten years to improve them

  1. Acetylcholine receptors and cholinergic ligands: biochemical and genetic aspects in Torpedo californica and Drosophila melanogaster

    International Nuclear Information System (INIS)

    Rosenthal, L.S.

    1987-01-01

    This study evaluates the biochemical and genetic aspects of the acetylcholine receptor proteins and cholinergic ligands in Drosophila melanogaster and Torpedo californica. Included are (1) a comparative study of nicotinic ligand-induced cation release from acetylcholine receptors isolated from Torpedo californica and from Drosophila melanogaster, (2) solution studies of the cholinergic ligands, nikethamide and ethamivan, aimed at measuring internal molecular rotational barriers in solvents of different polarity; and (3) the isolation and characterization of the gene(s) for the acetylcholine receptor in Drosophila melasogaster. Acetylcholine receptor proteins isolated from Drosphila melanogaster heads were found to behave kinetically similar (with regards to cholinergic ligand-induced 155 Eu: 3+ displacement from prelabeled proteins) to receptor proteins isolated from Torpedo californica electric tissue, providing additional biochemical evidence for the existence of a Drosophila acetylcholine receptor

  2. Polarized expression of the GFP-tagged rat V(1a) vasopressin receptor.

    Science.gov (United States)

    Campos, D M; Reyes, C E; Sarmiento, J; Navarro, J; González, C B

    2001-11-30

    We investigated the targeting of the V(1a) receptor fused with the green fluorescence protein (V(1a)R-GFP) in polarized MDCK cells. Cells expressing V(1a)R-GFP displayed binding to vasopressin (AVP) and AVP-induced calcium responses, similar to cells expressing the wild-type V1a receptor. Interestingly, as with the wild-type V(1a)R, V(1a)R-GFP is preferentially distributed in the basolateral side of MDCK cells as monitored by confocal microscopy. Furthermore, AVP induced internalization of GFP-tagged receptors. Therefore, the GFP-tagged V(1a) receptor retains all the sorting signals of the wild-type receptor and offers an excellent system to elucidate the mechanisms of cell trafficking of V(1a) receptors.

  3. Flavivirus Entry Receptors: An Update

    Directory of Open Access Journals (Sweden)

    Manuel Perera-Lecoin

    2013-12-01

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

  4. International recommendations

    International Nuclear Information System (INIS)

    Lindell, Bo

    1986-01-01

    Full text: This short presentation will indicate the general radiation protection background to protective measures against foodstuffs contaminated with radioactive substances. A number of international organizations are involved in various aspects of radiation protection, for example, the International Atomic Energy Agency (IAEA), the United Nations Food and Agriculture Organization (FAO), the United Nations Environment Programme (UNEP), and the World Health Organization (WHO). Two international organizations, however, provide the basic background. These are the International Commission on Radiological Protection (ICRP) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). UNSCEAR provides the scientific information on radiation levels and effects. It consists of 21 member countries, with truly international coverage. It issues reports to the UN General Assembly, including comprehensive scientific annexes. Its latest comprehensive report was issued in 1982, the next is expected to be published in 1988. That report will include an assessment of the radiological consequences of the Chernobyl accident. The ICRP is a non-governmental organization. It has issued recommendations on radiation protection since 1928. The postulated biological basis for radiation protection recommendations involves two types of biological effects. The so-called non-stochastic effects, mainly due to cell death, appear only when the radiation doses exceed a certain threshold value. These effects, therefore, can only appear after high accidental exposures. After the Chernobyl accident, they only affected about 200 individuals involved in fire extinction and rescue work at the damaged nuclear power plant. Stochastic effects, with some simplification, may be seen as the result of initial changes in the genetic code of some surviving cells. If these cells are germ cells, this may lead to hereditary harm. If they are somatic cells, the result could be cancer

  5. Insulin internalization in isolated rat hepatocytes

    International Nuclear Information System (INIS)

    Galan, J.; Trankina, M.; Noel, R.; Ward, W.

    1990-01-01

    This project was designed to determine whether neomycin, an aminoglycoside antibiotic, has a significant effect upon the pathways of ligand endocytosis in isolated rat hepatocytes. The pathways studied include receptor-mediated endocytosis and fluid-phase endocytosis. Neomycin causes a dose-dependent acceleration of 125 I-insulin internalization. Since fluid-phase endocytosis can also be a significant factor in 125 I-insulin internalization, lucifer yellow (LY), a marker for fluid-phase endocytosis, was incorporated into an assay similar to the 125 I-insulin internalization procedure. In the presence of 5 mM neomycin, a significant increase in LY uptake was evident at 0.2 and 0.4 mg/ml of LY. At 0.8 mg/ml, a decrease in LY uptake was observed. The increased rate of 125 I-insulin internalization in the presence of neomycin was intriguing. Since one action of neomycin is to inhibit phosphoinositidase C, it suggests that the phosphotidylinositol cycle may be involved in ligand internalization by hepatocytes. At low insulin concentrations, receptor-mediated uptake predominates. Fluid-phase uptake can become an important uptake route as insulin concentrations are increased. Since neomycin stimulates fluid-phase endocytosis, it must also be taken into account when measuring ligand internalization

  6. International relations

    International Nuclear Information System (INIS)

    Anon.

    2009-01-01

    The French nuclear safety authority (A.S.N.) has participated at different meeting in European Union as nuclear decommissioning assistance programme(N.D.A.P.), Regulatory assistance management group (R.A.M.G.) and Instrument for nuclear safety cooperation (I.N.S.C.). The members of Western European nuclear regulator association (W.E.N.R.A.) met and discussed about the future of W.E.N.R.A. and its representativeness and its cooperation with European nuclear safety regulator group (E.N.S.R.E.G.) and head of European radiation control authorities (H.E.R.C.A.). About International relations it is to noticed a meeting at the invitation of IAEA to discuss about the possibility to resort to the Ines scale for medical events. An audit mission under the IAEA aegis stood at Fessenheim, O.S.A.R.T. for operational safety review team. Two years and a half passed by between the audit mission Integrated regulatory review service (I.R.S.S.) welcome by A.S.N. in november 2006 and the audit mission follow up in 2009, 12 experts from 11 different countries and coordinated by three representatives of IAEA worked, the conclusions were that 90% of recommendations made to A.S.N. in 2006 were treated in a satisfying way; the evaluation gives three new recommendations, 7 new suggestions and 11 new correct practices. A meeting of the commission on safety standards (C.S.S.) stood in april 2009. Some others meeting are to be noticed: nuclear safety and security group (N.S.S.G.), expert group on nuclear and radiation safety (E.G.N.R.S.) instituted by the council of the Baltic sea states (C.B.S.S.) treats data exchange on the national networks of dose rates and surveillance of radioactivity in air. International nuclear regulator association (I.N.R.A.) held its first meeting in april 2009 at Seoul (Korea). Bilateral relations with Poland, Italy, Ukraine and Germany planed cooperation or information exchange in the field of nuclear safety. Participation to conference in Usa, meetings with United

  7. Update in Internal Medicine

    Science.gov (United States)

    López-Jiménez, Francisco; Brito, Máximo; Aude, Y. Wady; Scheinberg, Phillip; Kaplan, Mariana; Dixon, Denise A.; Schneiderman, Neil; Trejo, Jorge F.; López-Salazar, Luis Humberto; Ramírez-Barba, Ector Jaime; Kalil, Roberto; Ortiz, Carmen; Goyos, José; Buenaño, Alvaro; Kottiech, Samer; Lamas, Gervasio A.

    2009-01-01

    More than 500,000 new medical articles are published every year and available time to keep updated is scarcer every day. Nowadays, the task of selecting useful, consistent, and relevant information for clinicians is a priority in many major medical journals. This review has the aim of gathering the results of the most important findings in clinical medicine in the last few years. It is focused on results from randomized clinical trials and well-designed observational research. Findings were included preferentially if they showed solid results, and we avoided as much as possible including only preliminary data, or results that included only non-clinical outcomes. Some of the most relevant findings reported here include the significant benefit of statins in patients with coronary artery disease even with mean cholesterol level. It also provides a substantial review of the most significant trials assessing the effectiveness of IIb/IIIa receptor blockers. In gastroenterology many advances have been made in the H. pylori eradication, and the finding that the cure of H. pylori infection may be followed by gastroesophageal reflux disease. Some new antivirals have shown encouraging results in patients with chronic hepatitis. In the infectious disease arena, the late breaking trials in anti-retroviral disease are discussed, as well as the new trends regarding antibiotic resistance. This review approaches also the role of leukotriene modifiers in the treatment of asthma and discusses the benefit of using methylprednisolone in patients with adult respiratory distress syndrome, among many other advances in internal medicine. PMID:11068074

  8. Adenosine Receptors and Wound Healing

    Directory of Open Access Journals (Sweden)

    Bruce N. Cronstein

    2004-01-01

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

  9. Virally encoded 7TM receptors

    DEFF Research Database (Denmark)

    Rosenkilde, M M; Waldhoer, M; Lüttichau, H R

    2001-01-01

    expression of this single gene in certain lymphocyte cell lineages leads to the development of lesions which are remarkably similar to Kaposi's sarcoma, a human herpesvirus 8 associated disease. Thus, this and other virally encoded 7TM receptors appear to be attractive future drug targets.......A number of herpes- and poxviruses encode 7TM G-protein coupled receptors most of which clearly are derived from their host chemokine system as well as induce high expression of certain 7TM receptors in the infected cells. The receptors appear to be exploited by the virus for either immune evasion...

  10. Adenosine receptor desensitization and trafficking.

    Science.gov (United States)

    Mundell, Stuart; Kelly, Eamonn

    2011-05-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

  12. International perspective

    International Nuclear Information System (INIS)

    2003-01-01

    The workshop dealt with two distinct cases: - In Port Hope - an existing situation impacting a set of communities affected by the nuclear fuel industry since the 1930's. This situation concerns the remediation of soil 'tainted' by a low level of radioactivity resulting from the processing of uranium. The facility that produced those wastes is still in town but it has changed ownership and it no longer stores or disposes of the waste in the area. - The issuance and upcoming implementation of the Nuclear Fuel Waste Act (NWF Act) charting a path towards the identification of a national, long-term management solution for nuclear fuel (high level) waste in Canada. The NWF Act restarts a process that was interrupted a few years ago, after the Seaborn Environmental Assessment Panel concluded that the solution proposed by proponent Atomic Energy Canada Ltd. had not been demonstrated to have broad public support. From an international perspective, numerous observations can be made and lessons can be drawn both from the individual and the combined cases. Some of the most prominent observations, in the view of the NEA Secretariat, are presented hereafter. (author)

  13. Sphingosine-1-phosphate (S1P) displays sustained S1P1 receptor agonism and signaling through S1P lyase-dependent receptor recycling.

    Science.gov (United States)

    Gatfield, John; Monnier, Lucile; Studer, Rolf; Bolli, Martin H; Steiner, Beat; Nayler, Oliver

    2014-07-01

    The sphingosine-1-phosphate (S1P) type 1 receptor (S1P1R) is a novel therapeutic target in lymphocyte-mediated autoimmune diseases. S1P1 receptor desensitization caused by synthetic S1P1 receptor agonists prevents T-lymphocyte egress from secondary lymphoid organs into the circulation. The selective S1P1 receptor agonist ponesimod, which is in development for the treatment of autoimmune diseases, efficiently reduces peripheral lymphocyte counts and displays efficacy in animal models of autoimmune disease. Using ponesimod and the natural ligand S1P, we investigated the molecular mechanisms leading to different signaling, desensitization and trafficking behavior of S1P1 receptors. In recombinant S1P1 receptor-expressing cells, ponesimod and S1P triggered Gαi protein-mediated signaling and β-arrestin recruitment with comparable potency and efficiency, but only ponesimod efficiently induced intracellular receptor accumulation. In human umbilical vein endothelial cells (HUVEC), ponesimod and S1P triggered translocation of the endogenous S1P1 receptor to the Golgi compartment. However, only ponesimod treatment caused efficient surface receptor depletion, receptor accumulation in the Golgi and degradation. Impedance measurements in HUVEC showed that ponesimod induced only short-lived Gαi protein-mediated signaling followed by resistance to further stimulation, whereas S1P induced sustained Gαi protein-mediated signaling without desensitization. Inhibition of S1P lyase activity in HUVEC rendered S1P an efficient S1P1 receptor internalizing compound and abrogated S1P-mediated sustained signaling. This suggests that S1P lyase - by facilitating S1P1 receptor recycling - is essential for S1P-mediated sustained signaling, and that synthetic agonists are functional antagonists because they are not S1P lyase substrates. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Axonal GABAA receptors.

    Science.gov (United States)

    Trigo, Federico F; Marty, Alain; Stell, Brandon M

    2008-09-01

    Type A GABA receptors (GABA(A)Rs) are well established as the main inhibitory receptors in the mature mammalian forebrain. In recent years, evidence has accumulated showing that GABA(A)Rs are prevalent not only in the somatodendritic compartment of CNS neurons, but also in their axonal compartment. Evidence for axonal GABA(A)Rs includes new immunohistochemical and immunogold data: direct recording from single axonal terminals; and effects of local applications of GABA(A)R modulators on action potential generation, on axonal calcium signalling, and on neurotransmitter release. Strikingly, whereas presynaptic GABA(A)Rs have long been considered inhibitory, the new studies in the mammalian brain mostly indicate an excitatory action. Depending on the neuron that is under study, axonal GABA(A)Rs can be activated by ambient GABA, by GABA spillover, or by an autocrine action, to increase either action potential firing and/or transmitter release. In certain neurons, the excitatory effects of axonal GABA(A)Rs persist into adulthood. Altogether, axonal GABA(A)Rs appear as potent neuronal modulators of the mammalian CNS.

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

    International Nuclear Information System (INIS)

    Cash, D.J.; Subbarao, K.

    1987-01-01

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

  16. Absence of down-regulation of the insulin receptor by insulin. A possible mechanism of insulin resistance in the rat.

    OpenAIRE

    Walker, A P; Flint, D J

    1983-01-01

    Insulin resistance occurs in rat adipocytes during pregnancy and lactation despite increased or normal insulin binding respectively; this suggests that a post-receptor defect exists. The possibility has been examined that, although insulin binding occurs normally, internalization of insulin or its receptor may be impaired in these states. Insulin produced a dose-dependent reduction in the number of insulin receptors on adipocytes from virgin rats maintained in culture medium, probably due to ...

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

    Directory of Open Access Journals (Sweden)

    Luigi F. Agnati

    2007-01-01

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

  18. Receptor studies in biological psychiatry

    International Nuclear Information System (INIS)

    Fujiwara, Yutaka

    1992-01-01

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

  19. Internal Audit Service | Internal Audit Service

    Science.gov (United States)

    their internal auditing function in the areas of professional excellence, quality of service and Students and teachers Media Internal Audit Service Navbar Toggle Home About the Staff Risk Assessment and Planning Internal Audit Process Search for Search Home The mission of the Fermilab Internal Audit Service

  20. Elimination of a ligand gating site generates a supersensitive olfactory receptor.

    Science.gov (United States)

    Sharma, Kanika; Ahuja, Gaurav; Hussain, Ashiq; Balfanz, Sabine; Baumann, Arnd; Korsching, Sigrun I

    2016-06-21

    Olfaction poses one of the most complex ligand-receptor matching problems in biology due to the unparalleled multitude of odor molecules facing a large number of cognate olfactory receptors. We have recently deorphanized an olfactory receptor, TAAR13c, as a specific receptor for the death-associated odor cadaverine. Here we have modeled the cadaverine/TAAR13c interaction, exchanged predicted binding residues by site-directed mutagenesis, and measured the activity of the mutant receptors. Unexpectedly we observed a binding site for cadaverine at the external surface of the receptor, in addition to an internal binding site, whose mutation resulted in complete loss of activity. In stark contrast, elimination of the external binding site generated supersensitive receptors. Modeling suggests this site to act as a gate, limiting access of the ligand to the internal binding site and thereby downregulating the affinity of the native receptor. This constitutes a novel mechanism to fine-tune physiological sensitivity to socially relevant odors.

  1. In silico discovery of novel Retinoic Acid Receptor agonist structures

    Directory of Open Access Journals (Sweden)

    Samuels Herbert H

    2001-06-01

    Full Text Available Abstract Background Several Retinoic Acid Receptors (RAR agonists have therapeutic activity against a variety of cancer types; however, unacceptable toxicity profiles have hindered the development of drugs. RAR agonists presenting novel structural and chemical features could therefore open new avenues for the discovery of leads against breast, lung and prostate cancer or leukemia. Results We have analysed the induced fit of the active site residues upon binding of a known ligand. The derived binding site models were used to dock over 150,000 molecules in silico (or virtually to the structure of the receptor with the Internal Coordinates Mechanics (ICM program. Thirty ligand candidates were tested in vitro. Conclusions Two novel agonists resulting from the predicted receptor model were active at 50 nM. One of them displays novel structural features which may translate into the development of new ligands for cancer therapy.

  2. Scavenger Receptor Structure and Function in Health and Disease

    Directory of Open Access Journals (Sweden)

    Izma Abdul Zani

    2015-05-01

    Full Text Available Scavenger receptors (SRs are a ‘superfamily’ of membrane-bound receptors that were initially thought to bind and internalize modified low-density lipoprotein (LDL, though it is currently known to bind to a variety of ligands including endogenous proteins and pathogens. New family of SRs and their properties have been identified in recent years, and have now been classified into 10 eukaryote families, defined as Classes A-J. These receptors are classified according to their sequences, although in each class they are further classified based in the variations of the sequence. Their ability to bind a range of ligands is reflected on the biological functions such as clearance of modified lipoproteins and pathogens. SR members regulate pathophysiological states including atherosclerosis, pathogen infections, immune surveillance, and cancer. Here, we review our current understanding of SR structure and function implicated in health and disease.

  3. Differential regulation by agonist and phorbol ester of cloned m1 and m2 muscarinic acetylcholine receptors in mouse Y1 adrenal cells and in Y1 cells deficient in cAMP-dependent protein kinase

    International Nuclear Information System (INIS)

    Scherer, N.M.; Nathanson, N.M.

    1990-01-01

    Cloned muscarinic acetylcholine m1 and m2 receptors were expressed in stably transfected mouse Y1 adrenal cells and in a variant Y1 line, Kin-8, which is deficient in cAMP-dependent protein kinase activity (PKA - ). m1 and m2 receptors were rapidly internalized following exposure of transfected PKA + or PKA - cells to the muscarinic agonist carbachol. Thus, agonist-dependent internalization of m1 and m2 did not require PKA activity. A differential effect of PKA on regulation by agonist of the m2 receptor, but not the m1 receptor, was unmasked in PKA - cells. These data indicate that the basal activity of PKA may modulate the agonist-dependent internalization of the m2 receptor, but not the m1 receptor. The internalization of the m1 and m2 receptors in both PKA + and PKA - cells was accompanied by desensitization of functional responses. Exposure of PKA + cells to 10 -7 M phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, resulted in a 30 ± 9% decrease in the number of m1 receptors on the cell surface. The m2 receptor was not internalized following treatment of either PKA + or PKA - cells with PMA. Thus, the m1 and m2 receptors show differential sensitivity to internalization by PMA. Agonist-dependent internalization of the m1 receptor appeared to be independent of activation of PKC because (1) agonist-dependent internalization of m1 was not attenuated in PKA - cells, (2) the rate and extent of internalization of m1 in cells exposed to PMA were less than those in cells exposed to agonist, and (3) treatment of cells with concanavalin A selectivity blocked internalization of m1 in cells exposed to PMA, but not to agonist. The effects of agonist and PMA on receptor internalization were not additive. Exposure of PKA + or PKA - cells to PMA reduced the magnitude of pilocarpine-stimulated PI hydrolysis by about 25%

  4. Quantitative analysis of receptor imaging

    International Nuclear Information System (INIS)

    Fu Zhanli; Wang Rongfu

    2004-01-01

    Model-based methods for quantitative analysis of receptor imaging, including kinetic, graphical and equilibrium methods, are introduced in detail. Some technical problem facing quantitative analysis of receptor imaging, such as the correction for in vivo metabolism of the tracer and the radioactivity contribution from blood volume within ROI, and the estimation of the nondisplaceable ligand concentration, is also reviewed briefly

  5. Coronavirus spike-receptor interactions

    NARCIS (Netherlands)

    Mou, H.

    2015-01-01

    Coronaviruses cause important diseases in humans and animals. Coronavirus infection starts with the virus binding with its spike proteins to molecules present on the surface of host cells that act as receptors. This spike-receptor interaction is highly specific and determines the virus’ cell, tissue

  6. Neurobeachin regulates neurotransmitter receptor trafficking to synapses

    NARCIS (Netherlands)

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

    2013-01-01

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

  7. A Novel Mechanism of Androgen Receptor Action

    National Research Council Canada - National Science Library

    Roberts, Jr, Charles T

    2006-01-01

    .... Specifically, the authors had determined that the androgen receptor controls the expression of the cell-surface receptor for the hormone IGF-1 at the level of translation of the IGF-1 receptor mRNA...

  8. Quantitative densitometry of neurotransmitter receptors

    International Nuclear Information System (INIS)

    Rainbow, T.C.; Bleisch, W.V.; Biegon, A.; McEwen, B.S.

    1982-01-01

    An autoradiographic procedure is described that allows the quantitative measurement of neurotransmitter receptors by optical density readings. Frozen brain sections are labeled in vitro with [ 3 H]ligands under conditions that maximize specific binding to neurotransmitter receptors. The labeled sections are then placed against the 3 H-sensitive LKB Ultrofilm to produce the autoradiograms. These autoradiograms resemble those produced by [ 14 C]deoxyglucose autoradiography and are suitable for quantitative analysis with a densitometer. Muscarinic cholinergic receptors in rat and zebra finch brain and 5-HT receptors in rat brain were visualized by this method. When the proper combination of ligand concentration and exposure time are used, the method provides quantitative information about the amount and affinity of neurotransmitter receptors in brain sections. This was established by comparisons of densitometric readings with parallel measurements made by scintillation counting of sections. (Auth.)

  9. Dopamine Receptors and Parkinson's Disease

    Directory of Open Access Journals (Sweden)

    Shin Hisahara

    2011-01-01

    Full Text Available Parkinson's disease (PD is a progressive extrapyramidal motor disorder. Pathologically, this disease is characterized by the selective dopaminergic (DAergic neuronal degeneration in the substantia nigra. Correcting the DA deficiency in PD with levodopa (L-dopa significantly attenuates the motor symptoms; however, its effectiveness often declines, and L-dopa-related adverse effects emerge after long-term treatment. Nowadays, DA receptor agonists are useful medication even regarded as first choice to delay the starting of L-dopa therapy. In advanced stage of PD, they are also used as adjunct therapy together with L-dopa. DA receptor agonists act by stimulation of presynaptic and postsynaptic DA receptors. Despite the usefulness, they could be causative drugs for valvulopathy and nonmotor complication such as DA dysregulation syndrome (DDS. In this paper, physiological characteristics of DA receptor familyare discussed. We also discuss the validity, benefits, and specific adverse effects of pharmaceutical DA receptor agonist.

  10. Ischemia- and agonist-induced changes in α- and β-adrenergic receptor traffic in guinea pig hearts

    International Nuclear Information System (INIS)

    Maisel, A.S.; Motulsky, H.J.; Ziegler, M.G.; Insel, P.A.

    1987-01-01

    The authors have used radioligand binding techniques and subcellular fraction to assess whether changes in expression of myocardial α 1 - and β-adrenergic receptors are mediated by a redistribution of receptors between various membrane fractions. Three fractions were prepared from the left ventricles of guinea pigs that underwent either 1 h of ischemia or injection of epinephrine a crude membrane, a purified sarcolemma, and a light vesicle fraction. In control animals α 1 -adrenergic receptors ([ 3 H]prazosin binding) in light vesicles was only 25% of the total α 1 -receptor density found in sarcolemmal and light vesicle fractions as compared with 50% for β-adrenergic receptors ([ 125 I]iodocyanopindolol binding sites). Although ischemia was associated with a 53% decrease in the number of light vesicle β-adrenergic receptors and a 42% increase in the number of sarcolemma β-receptors there was no change in the number of light vesicle α 1 -receptors, even though the number of sarcolemmal α 1 -receptors increased 34%. Epinephrine treatment promoted internalization of β-adrenergic receptors. These results indicate that α 1 and β 1 -adrenergic receptors may undergo a different cellular itinerary in guinea pig myocardium. Agonist and ischemia-induced changes in surface β-receptors, but not α 1 -receptors, appear to result from entry and exit of receptors from an intracellular pool that can be isolated in a light vesicle fraction. Changes in expression of α 1 -adrenergic receptors may represent changes in the properties of receptors found in the sarcolemma or in a membrane fraction other than the light vesicle fraction that they have isolated

  11. Molecular characterization of opioid receptors

    Energy Technology Data Exchange (ETDEWEB)

    Howard, A.D.

    1986-01-01

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

  12. Crystal structures of the ligand-binding region of uPARAP

    DEFF Research Database (Denmark)

    Yuan, Cai; Jürgensen, Henrik J; Engelholm, Lars H

    2016-01-01

    The proteins of the mannose receptor (MR) family share a common domain organization and have a broad range of biological functions. Urokinase plasminogen activator receptor-associated protein (uPARAP) (or Endo180) is a member of this family and plays an important role in extracellular matrix...... remodelling through interaction with its ligands, including collagens and urokinase plasminogen activator receptor (uPAR). We report the crystal structures of the first four domains of uPARAP (also named the ligand-binding region, LBR) at pH 7.4 in Ca(2+)-bound and Ca(2+)-free forms. The first domain....... These LLRs undergo a Ca(2+)-dependent conformational change, and this is likely to be the key structural determinant affecting the overall conformation of uPARAP. Our results provide a molecular mechanism to support the structural flexibility of uPARAP, and shed light on the structural flexibility of other...

  13. Odin (ANKS1A modulates EGF receptor recycling and stability.

    Directory of Open Access Journals (Sweden)

    Jiefei Tong

    Full Text Available The ANKS1A gene product, also known as Odin, was first identified as a tyrosine-phosphorylated component of the epidermal growth factor receptor network. Here we show that Odin functions as an effector of EGFR recycling. In EGF-stimulated HEK293 cells tyrosine phosphorylation of Odin was induced prior to EGFR internalization and independent of EGFR-to-ERK signaling. Over-expression of Odin increased EGF-induced EGFR trafficking to recycling endosomes and recycling back to the cell surface, and decreased trafficking to lysosomes and degradation. Conversely, Odin knockdown in both HEK293 and the non-small cell lung carcinoma line RVH6849, which expresses roughly 10-fold more EGF receptors than HEK293, caused decreased EGFR recycling and accelerated trafficking to the lysosome and degradation. By governing the endocytic fate of internalized receptors, Odin may provide a layer of regulation that enables cells to contend with receptor cell densities and ligand concentration gradients that are physiologically and pathologically highly variable.

  14. Quantification of GPCR internalization by single-molecule microscopy in living cells.

    NARCIS (Netherlands)

    Serge, A.; Keijzer, S. de; Hemert, F. Van; Hickman, M.R.; Hereld, D.; Spaink, H.P.; Schmidt, T.; Snaar-Jagalska, B.E.

    2011-01-01

    Receptor internalization upon ligand stimulation is a key component of a cell's response and allows a cell to correctly sense its environment. Novel fluorescent methods have enabled the direct visualization of the agonist-stimulated G-protein-coupled receptors (GPCR) trafficking in living cells.

  15. Correlated receptor transport processes buffer single-cell heterogeneity.

    Directory of Open Access Journals (Sweden)

    Stefan M Kallenberger

    2017-09-01

    Full Text Available Cells typically vary in their response to extracellular ligands. Receptor transport processes modulate ligand-receptor induced signal transduction and impact the variability in cellular responses. Here, we quantitatively characterized cellular variability in erythropoietin receptor (EpoR trafficking at the single-cell level based on live-cell imaging and mathematical modeling. Using ensembles of single-cell mathematical models reduced parameter uncertainties and showed that rapid EpoR turnover, transport of internalized EpoR back to the plasma membrane, and degradation of Epo-EpoR complexes were essential for receptor trafficking. EpoR trafficking dynamics in adherent H838 lung cancer cells closely resembled the dynamics previously characterized by mathematical modeling in suspension cells, indicating that dynamic properties of the EpoR system are widely conserved. Receptor transport processes differed by one order of magnitude between individual cells. However, the concentration of activated Epo-EpoR complexes was less variable due to the correlated kinetics of opposing transport processes acting as a buffering system.

  16. A high-content subtractive screen for selecting small molecules affecting internalization of GPCRs

    CSIR Research Space (South Africa)

    Kwon, Y-J

    2012-03-01

    Full Text Available was screened against seven agonist-induced GPCR internalization cell models as well as transferrin uptake in human embryonic kidney cells. Molecules acting on a single receptor were identified through excluding pan-specific compounds affecting housekeeping...

  17. The N-terminal region of the dopamine D2 receptor, a rhodopsin-like GPCR, regulates correct integration into the plasma membrane and endocytic routes

    Science.gov (United States)

    Cho, DI; Min, C; Jung, KS; Cheong, SY; Zheng, M; Cheong, SJ; Oak, MH; Cheong, JH; Lee, BK; Kim, KM

    2012-01-01

    BACKGROUND AND PURPOSE Functional roles of the N-terminal region of rhodopsin-like GPCR family remain unclear. Using dopamine D2 and D3 receptors as a model system, we probed the roles of the N-terminal region in the signalling, intracellular trafficking of receptor proteins, and explored the critical factors that determine the functionality of the N-terminal region. EXPERIMENTAL APPROACH The N-terminal region of the D2 receptor was gradually shortened or switched with that of the D3 receptor or a non-specific sequence (FLAG), or potential N-terminal glycosylation sites were mutated. Effects of these manipulations on surface expression, internalization, post-endocytic behaviours and signalling were determined. KEY RESULTS Shortening the N-terminal region of the D2 receptor enhanced receptor internalization and impaired surface expression and signalling; ligand binding, desensitization and down-regulation were not affected but their association with a particular microdomain, caveolae, was disrupted. Replacement of critical residues within the N-terminal region with the FLAG epitope failed to restore surface expression but partially restored the altered internalization and signalling. When the N-terminal regions were switched between D2 and D3 receptors, cell surface expression pattern of each receptor was switched. Mutations of potential N-terminal glycosylation sites inhibited surface expression but enhanced internalization of D2 receptors. CONCLUSIONS AND IMPLICATIONS Shortening of N-terminus or mutation of glycosylation sites located within the N-terminus enhanced receptor internalization but impaired the surface expression of D2 receptors. The N-terminal region of the D2 receptor, in a sequence-specific manner, controls the receptor's conformation and integration into the plasma membrane, which determine its subcellular localization, intracellular trafficking and signalling properties. PMID:22117524

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

    Science.gov (United States)

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

    2013-04-12

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

  19. Tyrosine 769 of the keratinocyte growth factor receptor is required for receptor signaling but not endocytosis

    International Nuclear Information System (INIS)

    Ceridono, Mara; Belleudi, Francesca; Ceccarelli, Simona; Torrisi, Maria Rosaria

    2005-01-01

    Keratinocyte growth factor receptor (KGFR) is a receptor tyrosine kinase expressed on epithelial cells which belongs to the family of fibroblast growth factor receptors (FGFRs). Following ligand binding, KGFR is rapidly autophosphorylated on specific tyrosine residues in the intracellular domain, recruits substrate proteins, and is rapidly internalized by clathrin-mediated endocytosis. The role of different autophosphorylation sites in FGFRs, and in particular the role of the tyrosine 766 in FGFR1, first identified as PLCγ binding site, has been extensively studied. We analyzed here the possible role of the tyrosine 769 in KGFR, corresponding to tyrosine 766 in FGFR1, in the regulation of KGFR signal transduction and MAPK activation as well as in the control of the endocytic process of KGFR. A mutant KGFR in which tyrosine 769 was substituted by phenylalanine was generated and transfected in NIH3T3 and HeLa cells. Our results indicate that tyrosine 769 is required for the binding to KGFR and tyrosine phosphorylation of PLCγ as well as for the full activation of MAPKs and for cell proliferation through the regulation of FRS2 tyrosine phosphorylation, suggesting that this residue represents a key regulator of KGFR signal transduction. Our data also show that tyrosine 769 is not involved in the regulation of the endocytic process of KGFR

  20. Stargazin Modulation of AMPA Receptors

    Directory of Open Access Journals (Sweden)

    Sana A. Shaikh

    2016-10-01

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

  1. Radioiodinated ligands for dopamine receptors

    International Nuclear Information System (INIS)

    Kung, H.F.

    1994-01-01

    The dopamine receptor system is important for normal brain function; it is also the apparent action site for various neuroleptic drugs for the treatment of schizophrenia and other metal disorders. In the past few years radioiodinated ligands for single photon emission tomography (SPECT) have been successfully developed and tested in humans: [ 123 I]TISCH for D1 dopamine receptors; [ 123 I]IBZM, epidepride, IBF and FIDA2, four iodobenzamide derivatives, for D2/D3 dopamine receptors. In addition, [ 123 I]β-CIT (RTI-55) and IPT, cocaine derivatives, for the dopamine reuptake site are potentially useful for diagnosis of loss of dopamine neurons. The first iodinated ligand, (R)trans-7-OH-PIPAT, for D3 dopamine receptors, was synthesized and characterized with cloned cell lines (Spodoptera frugiperda, Sf9) expressing the D2 and D3 dopamine receptors and with rat basal forebrain membrane preparations. Most of the known iodobenzamides displayed similar potency in binding to both D2 and D3 dopamine receptors expressed in the cell lines. Initial studies appear to suggest that by fine tuning the structures it may be possible to develop agents specific for D2 and D3 dopamine receptors. It is important to investigate D2/D3 selectivity for this series of potent ligands

  2. Labeled receptor ligands for spect

    International Nuclear Information System (INIS)

    Kung, H.F.

    1989-01-01

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

  3. Multistep change in epidermal growth factor receptors during spontaneous neoplastic progression in Chinese hamster embryo fibroblasts

    International Nuclear Information System (INIS)

    Wakshull, E.; Kraemer, P.M.; Wharton, W.

    1985-01-01

    Whole Chinese hamster embryo lineages have been shown to undergo multistep spontaneous neoplastic progression during serial passage in culture. The authors have studied the binding, internalization, and degradation of 125 I-labeled epidermal growth factor at four different stages of transformation. The whole Chinese hamster embryo cells lost cell surface epidermal growth factor receptors gradually during the course of neoplastic progression until only 10% of the receptor number present in the early-passage cells (precrisis) were retained in the late-passage cells (tumorigenic). No differences in internalization rates, chloroquine sensitivity, or ability to degrade hormone between the various passage levels were seen. No evidence for the presence in conditioned medium of transforming growth factors which might mask or down-regulate epidermal growth factor receptor was obtained. These results suggest that a reduction in cell surface epidermal growth factor receptor might be an early event during spontaneous transformation in whole Chinese hamster embryo cells

  4. Estradiol-induced estrogen receptor-alpha trafficking.

    Science.gov (United States)

    Bondar, Galyna; Kuo, John; Hamid, Naheed; Micevych, Paul

    2009-12-02

    Estradiol has rapid actions in the CNS that are mediated by membrane estrogen receptors (ERs) and activate cell signaling pathways through interaction with metabotropic glutamate receptors (mGluRs). Membrane-initiated estradiol signaling increases the free cytoplasmic calcium concentration ([Ca(2+)](i)) that stimulates the synthesis of neuroprogesterone in astrocytes. We used surface biotinylation to demonstrate that ERalpha has an extracellular portion. In addition to the full-length ERalpha [apparent molecular weight (MW), 66 kDa], surface biotinylation labeled an ERalpha-immunoreactive protein (MW, approximately 52 kDa) identified by both COOH- and NH(2)-directed antibodies. Estradiol treatment regulated membrane levels of both proteins in parallel: within 5 min, estradiol significantly increased membrane levels of the 66 and 52 kDa ERalpha. Internalization, a measure of membrane receptor activation, was also increased by estradiol with a similar time course. Continuous treatment with estradiol for 24-48 h reduced ERalpha levels, suggesting receptor downregulation. Estradiol also increased mGluR1a trafficking and internalization, consistent with the proposed ERalpha-mGluR1a interaction. Blocking ER with ICI 182,780 or mGluR1a with LY 367385 prevented ERalpha trafficking to and from the membrane. Estradiol-induced [Ca(2+)](i) flux was also significantly increased at the time of peak ERalpha activation/internalization. These results demonstrate that ERalpha is present in the membrane and has an extracellular portion. Furthermore, membrane levels and internalization of ERalpha are regulated by estradiol and mGluR1a ligands. The pattern of trafficking into and out of the membrane suggests that the changing concentration of estradiol during the estrous cycle regulates ERalpha to augment and then terminate membrane-initiated signaling.

  5. Estradiol-induced estrogen receptor-α trafficking

    Science.gov (United States)

    Bondar, Galyna; Kuo, John; Hamid, Naheed; Micevych, Paul

    2010-01-01

    Estradiol has rapid actions in the central nervous system, which are mediated by membrane estrogen receptors (ERs) and activate cell signaling pathways through interaction with metabotropic glutamate receptors (mGluRs). Membrane-initiated estradiol signaling increases the free cytoplasmic calcium concentration ([Ca2+]i) that stimulates the synthesis of neuroprogesterone in astrocytes. We used surface biotinylation to demonstrate that ERα has an extracellular portion. In addition to the full length ERα (apparent M.W. 66 kDa), surface biotinylation labeled an ERα-immunoreactive protein (M.W. ~ 52 kDa) identified by both COOH- and NH2-directed antibodies. Estradiol treatment regulated membrane levels of both proteins in parallel: within 5 min, estradiol significantly increased membrane levels of the 66 kDa and 52 kDa ERα. Internalization, a measure of membrane receptor activation, was also increased by estradiol with a similar time course. Continuous treatment with estradiol for 24–48 hr reduced ERα levels, suggesting receptor down-regulation. Estradiol also increased mGluR1a trafficking and internalization, consistent with the proposed ERα-mGluR1a interaction. Blocking ER with ICI 182,780 or mGluR1a with LY 367385 prevented ERα trafficking to and from the membrane. Estradiol-induced [Ca2+]i flux was also significantly increased at the time of peak ERα activation/internalization. These results demonstrate that ERα is present in the membrane and has an extracellular portion. Furthermore, membrane levels and internalization of ERα are regulated by estradiol and mGluR1a ligands. The pattern of trafficking into and out of the membrane suggests that the changing concentration of estradiol during the estrous cycle regulates ERα to augment and then terminate membrane-initiated signaling. PMID:19955385

  6. Down-regulation of parathyroid hormone (PTH) receptors in cultured bone cells is associated with agonist-specific intracellular processing of PTH-receptor complexes.

    Science.gov (United States)

    Teitelbaum, A P; Silve, C M; Nyiredy, K O; Arnaud, C D

    1986-02-01

    Exposure of cultured embryonic chicken bone cells to the PTH agonists bovine (b) PTH-(1-34) and [8Nle, 18Nle, 34Tyr]bPTH-(1-34)amide [bPTH-(1-34)A] reduces the subsequent cAMP response to the hormone and decreases the specific binding of 125I-labeled PTH to these cultures. To determine whether PTH receptor down-regulation in cultured bone cells is mediated by cellular internalization of PTH-receptor complexes, we measured the uptake of [125I]bPTH-(1-34) into an acid-resistant compartment. Uptake of radioactivity into this compartment was inhibited by incubating cells at 4 C with phenylarsineoxide and unlabeled bPTH-(1-34). Tracer uptake into the acid-resistant compartment at any time was directly proportional to total cell binding at 22 C. Thus, it is likely that PTH-receptor complexes are internalized by bone cells. This mechanism may explain the loss of cell surface receptors after PTH pretreatment. To determine whether internalized PTH-receptor complexes are reinserted into the plasma membrane, we measured PTH binding and PTH stimulation of cAMP production after cells were exposed to monensin, a known inhibitor of receptor recycling. Monensin (25 microM) had no effect on PTH receptor number or affinity and did not alter PTH-stimulated cAMP accumulation. However, monensin (25 microM) incubated with cells pretreated with various concentrations of bPTH-(1-34) for 1 h potentiated the effect of the hormone to reduce subsequent [125I]bPTH-(1-34) binding and PTH-stimulated cAMP accumulation by more than 2 orders of magnitude. Chloroquine also potentiated PTH-induced down-regulation of PTH receptors. By contrast, neither agent influenced PTH binding or PTH-stimulated cAMP production in cells pretreated with the antagonist bPTH-(3-34)A. Thus, monensin potentiated PTH receptor loss only in cells pretreated with PTH agonists, indicating that antagonist-occupied receptors may be processed differently from agonist-occupied receptors in bone cells. The data further suggest

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

    Science.gov (United States)

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

    2014-04-01

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

  8. The past, present, and future of selective progesterone receptor modulators in the management of uterine fibroids.

    Science.gov (United States)

    Singh, Sukhbir S; Belland, Liane; Leyland, Nicholas; von Riedemann, Sarah; Murji, Ally

    2017-12-21

    Uterine fibroids are common in women of reproductive age and can have a significant impact on quality of life and fertility. Although a number of international obstetrics/gynecology societies have issued evidence-based clinical practice guidelines for the management of symptomatic uterine fibroids, many of these guidelines do not yet reflect the most recent clinical evidence and approved indication for one of the key medical management options: the selective progesterone receptor modulator class. This article aims to share the clinical experience gained with selective progesterone receptor modulators in Europe and Canada by reviewing the historical development of selective progesterone receptor modulators, current best practices for selective progesterone receptor modulator use based on available data, and potential future uses for selective progesterone receptor modulators in uterine fibroids and other gynecologic conditions. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  9. International Ecohealth Forum 2008 | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... the International Forum on Ecosystem Approaches to Human Health (Montreal, ... the International Association of Ecology and Health (IAEH), and a Brazilian ... Nutrition, health policy, and ethics in the age of public-private partnerships.

  10. XMRV: usage of receptors and potential co-receptors

    Directory of Open Access Journals (Sweden)

    Gaddam Durga

    2011-09-01

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

  11. Megalin functions as an endocytic sonic hedgehog receptor.

    Science.gov (United States)

    McCarthy, Robert A; Barth, Jeremy L; Chintalapudi, Mastan R; Knaak, Christian; Argraves, W Scott

    2002-07-12

    Embryos deficient in the morphogen Sonic hedgehog (Shh) or the endocytic receptor megalin exhibit common neurodevelopmental abnormalities. Therefore, we have investigated the possibility that a functional relationship exists between the two proteins. During embryonic development, megalin was found to be expressed along the apical surfaces of neuroepithelial cells and was coexpressed with Shh in the ventral floor plate of the neural tube. Using enzyme-linked immunosorbent assay, homologous ligand displacement, and surface plasmon resonance techniques, it was found that the amino-terminal fragment of Shh (N-Shh) bound to megalin with high affinity. Megalin-expressing cells internalized N-Shh through a mechanism that was inhibited by antagonists of megalin, viz. anti-receptor-associated protein and anti-megalin antibodies. Heparin also inhibited N-Shh endocytosis, implicating proteoglycans in the internalization process, as has been described for other megalin ligands. Use of chloroquine to inhibit lysosomal proteinase activity showed that N-Shh endocytosed via megalin was not efficiently targeted to the lysosomes for degradation. The ability of megalin-internalized N-Shh to bypass lysosomes may relate to the finding that the interaction between N-Shh and megalin was resistant to dissociation with low pH. Together, these findings show that megalin is an efficient endocytic receptor for N-Shh. Furthermore, they implicate megalin as a new regulatory component of the Shh signaling pathway.

  12. T cell receptor zeta allows stable expression of receptors containing the CD3gamma leucine-based receptor-sorting motif

    DEFF Research Database (Denmark)

    Dietrich, J; Geisler, C

    1998-01-01

    The leucine-based motif in the T cell receptor (TCR) subunit CD3gamma constitutes a strong internalization signal. In fully assembled TCR this motif is inactive unless phosphorylated. In contrast, the motif is constitutively active in CD4/CD3gamma and Tac/CD3gamma chimeras independently of phosph......The leucine-based motif in the T cell receptor (TCR) subunit CD3gamma constitutes a strong internalization signal. In fully assembled TCR this motif is inactive unless phosphorylated. In contrast, the motif is constitutively active in CD4/CD3gamma and Tac/CD3gamma chimeras independently...... of phosphorylation and leads to rapid internalization and sorting of these chimeras to lysosomal degradation. Because the TCRzeta chain rescues incomplete TCR complexes from lysosomal degradation and allows stable surface expression of fully assembled TCR, we addressed the question whether TCRzeta has the potential...... to mask the CD3gamma leucine-based motif. By studying CD4/CD3gamma and CD16/CD3gamma chimeras, we found that CD16/CD3gamma chimeras associated with TCRzeta. The CD16/CD3gamma-TCRzeta complexes were stably expressed at the cell surface and had a low spontaneous internalization rate, indicating...

  13. EVIR: chimeric receptors that enhance dendritic cell cross-dressing with tumor antigens.

    Science.gov (United States)

    Squadrito, Mario Leonardo; Cianciaruso, Chiara; Hansen, Sarah K; De Palma, Michele

    2018-03-01

    We describe a lentivirus-encoded chimeric receptor, termed extracellular vesicle (EV)-internalizing receptor (EVIR), which enables the selective uptake of cancer-cell-derived EVs by dendritic cells (DCs). The EVIR enhances DC presentation of EV-associated tumor antigens to CD8 + T cells primarily through MHCI recycling and cross-dressing. EVIRs should facilitate exploring the mechanisms and implications of horizontal transfer of tumor antigens to antigen-presenting cells.

  14. Structural Diversity in Conserved Regions Like the DRY-Motif among Viral 7TM Receptors-A Consequence of Evolutionary Pressure?

    DEFF Research Database (Denmark)

    Mølleskov-Jensen, Ann-Sofie; Sparre-Ulrich, Alexander Hovard; Davis-Poynter, Nicholas

    2012-01-01

    Several herpes- and poxviruses have captured chemokine receptors from their hosts and modified these to their own benefit. The human and viral chemokine receptors belong to class A 7 transmembrane (TM) receptors which are characterized by several structural motifs like the DRY-motif in TM3...... and the C-terminal tail. In the DRY-motif, the arginine residue serves important purposes by being directly involved in G protein coupling. Interestingly, among the viral receptors there is a greater diversity in the DRY-motif compared to their endogenous receptor homologous. The C-terminal receptor tail...... constitutes another regulatory region that through a number of phosphorylation sites is involved in signaling, desensitization, and internalization. Also this region is more variable among virus-encoded 7TM receptors compared to human class A receptors. In this review we will focus on these two structural...

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

    Directory of Open Access Journals (Sweden)

    Fior-Chadi D.R.

    1998-01-01

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

  16. Ninth international symposium on radiopharmacology

    International Nuclear Information System (INIS)

    1995-01-01

    The goal of this Symposium is to provide a forum for those international scientists involved in applying the principles of pharmacology and radiation biology to the development of agents for the diagnosis and treatment of disease. The program will highlight state-of-the-art progress in the development of those agents used in conjunction with some form of radiation such as radiopharmaceuticals, radiopaques, photo- and radiosensitizing drugs, and neutron capture agents. An underlying pharmacokinetic parameter associated with all these agents is the need for site-specific delivery to an organ or tumor. Therefore, a major goal of the symposium will be to address those pharmacologic principles for targeting molecules to specific tissue sites. Accordingly, session themes will include receptor-mediated processes, membrane transporters, antibody interactions, metabolic trapping, and oligonucleotide-antisense mechanisms

  17. Ninth international symposium on radiopharmacology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    The goal of this Symposium is to provide a forum for those international scientists involved in applying the principles of pharmacology and radiation biology to the development of agents for the diagnosis and treatment of disease. The program will highlight state-of-the-art progress in the development of those agents used in conjunction with some form of radiation such as radiopharmaceuticals, radiopaques, photo- and radiosensitizing drugs, and neutron capture agents. An underlying pharmacokinetic parameter associated with all these agents is the need for site-specific delivery to an organ or tumor. Therefore, a major goal of the symposium will be to address those pharmacologic principles for targeting molecules to specific tissue sites. Accordingly, session themes will include receptor-mediated processes, membrane transporters, antibody interactions, metabolic trapping, and oligonucleotide-antisense mechanisms.

  18. Peripheral adrenergic receptors in hypertension

    NARCIS (Netherlands)

    Michel, M. C.; Brodde, O. E.; Insel, P. A.

    1990-01-01

    Increased sympathoadrenal activity appears to play an important role in the development or maintenance of elevated blood pressure in hypertensive patients and various animal models of hypertension. Alterations of adrenergic receptor number or responsiveness might contribute to this increased

  19. Are olfactory receptors really olfactive?

    DEFF Research Database (Denmark)

    Giorgi, Franco; Maggio, Roberto; Bruni, Luis Emilio

    2011-01-01

    environmental conditions. By adopting this standpoint, the functional attribution as olfactory or chemotactic sensors to these receptors should not be seen neither as a cause conditioning receptor gene expression, nor as a final effect resulting from genetically predetermined programs, but as a direct...... and odor-decoding processes. However, this type of explanation does not entirely justify the role olfactory receptors have played during evolution, since they are also expressed ectopically in different organs and/or tissues. Homologous olfactory genes have in fact been found in such diverse cells and....../or organs as spermatozoa, testis and kidney where they are assumed to act as chemotactic sensors or renin modulators. To justify their functional diversity, homologous olfactory receptors are assumed to share the same basic role: that of conferring a self-identity to cells or tissues under varying...

  20. Nuclear Receptor Signaling Atlas (NURSA)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Nuclear Receptor Signaling Atlas (NURSA) is designed to foster the development of a comprehensive understanding of the structure, function, and role in disease...

  1. Nuclear fuel cycle: international market, international constraints and international cooperation

    International Nuclear Information System (INIS)

    Imai, R.

    1977-01-01

    Some of the constraints on the nuclear fuel cycle are ones arising from economic and financial reasons, those caused by uranium resources and their distribution, those arising from technical reasons, issues of public acceptance, and those quite independent of normal industrial considerations, but caused by elements of international politics. The nuclear fuel cycle and the international market, matters of nuclear non-proliferation, and international cooperation are discussed

  2. Isolation and characterization of the inositol trisphosphate receptor from smooth muscle

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  3. L-glutamate Receptor In Paramecium

    Science.gov (United States)

    Bernal-Martínez, Juan; Ortega-Soto, Arturo

    2004-09-01

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

  4. Receptor-targeted metalloradiopharmaceuticals. Final technical report

    International Nuclear Information System (INIS)

    Green, Mark A.

    2000-01-01

    Copper (II) and platinum (II) coordination complexes were prepared and characterized. These complexes were designed to afford structural homology with steroidal and non-steroidal estrogens for possible use as receptor-targeted radiopharmaceuticals. While weak affinity for the estrogen receptor was detectable, none would appear to have sufficient receptor-affinity for estrogen-receptor-targeted imaging or therapy

  5. [The receptor theory of atherosclerosis].

    Science.gov (United States)

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

    2010-01-01

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

  6. Xenobiotics and the Glucocorticoid Receptor

    International Nuclear Information System (INIS)

    Gulliver, Linda S M

    2017-01-01

    Glucocorticoid Receptor (GR) is present in virtually every human cell type. Representing a nuclear receptor superfamily, GR has several different isoforms essentially acting as ligand-dependent transcription factors, regulating glucocorticoid-responsive gene expression in both a positive and a negative manner. Although the natural ligand of the Glucocorticoid Receptor, glucocorticoids (GC) represent only some of the multiple ligands for GR. Xenobiotics, ubiquitous in the environment, bind to GR and are also capable of activating or repressing GR gene expression, thereby modulating GR cell and tissue-specific downstream effects in a multitude of ways that include responses to inflammatory, allergic, metabolic, neoplastic and autoimmune processes. Many xenobiotics, if inadequately metabolized by xenobiotic metabolizing enzymes and not wholly eliminated, could have deleterious toxic effects with potentially lethal consequences. This review examines GR, the genomic and non-genomic actions of natural and synthetic GC and the body's handling of xenobiotic compounds, before reviewing what is presently known about GR's interactions with many of the more commonly encountered and some of the less well known GR-associated xenobiotics. GR promiscuity and crosstalk with other signaling pathways is discussed, alongside novel roles for GR that include mood disorder and addiction. A knowledge of GR interactions with xenobiotics is increasingly relevant when considering aging populations and the related prevalence of neoplastic disease, together with growing concerns around human exposure to mixtures of chemicals in the environment. Furthermore, escalating rates of obesity, Type 2 diabetes; autoimmune, allergy, addiction and mood disorder-related pathologies, require novel targeted interventions and GR appears a promising pharmacological candidate. - Highlights: • Biological impact of xenobiotics acting through Glucocorticoid Receptor. • Promiscuity of Glucocorticoid

  7. Xenobiotics and the Glucocorticoid Receptor

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-15

    Glucocorticoid Receptor (GR) is present in virtually every human cell type. Representing a nuclear receptor superfamily, GR has several different isoforms essentially acting as ligand-dependent transcription factors, regulating glucocorticoid-responsive gene expression in both a positive and a negative manner. Although the natural ligand of the Glucocorticoid Receptor, glucocorticoids (GC) represent only some of the multiple ligands for GR. Xenobiotics, ubiquitous in the environment, bind to GR and are also capable of activating or repressing GR gene expression, thereby modulating GR cell and tissue-specific downstream effects in a multitude of ways that include responses to inflammatory, allergic, metabolic, neoplastic and autoimmune processes. Many xenobiotics, if inadequately metabolized by xenobiotic metabolizing enzymes and not wholly eliminated, could have deleterious toxic effects with potentially lethal consequences. This review examines GR, the genomic and non-genomic actions of natural and synthetic GC and the body's handling of xenobiotic compounds, before reviewing what is presently known about GR's interactions with many of the more commonly encountered and some of the less well known GR-associated xenobiotics. GR promiscuity and crosstalk with other signaling pathways is discussed, alongside novel roles for GR that include mood disorder and addiction. A knowledge of GR interactions with xenobiotics is increasingly relevant when considering aging populations and the related prevalence of neoplastic disease, together with growing concerns around human exposure to mixtures of chemicals in the environment. Furthermore, escalating rates of obesity, Type 2 diabetes; autoimmune, allergy, addiction and mood disorder-related pathologies, require novel targeted interventions and GR appears a promising pharmacological candidate. - Highlights: • Biological impact of xenobiotics acting through Glucocorticoid Receptor. • Promiscuity of Glucocorticoid

  8. Nuclear Receptors, RXR, and the Big Bang.

    Science.gov (United States)

    Evans, Ronald M; Mangelsdorf, David J

    2014-03-27

    Isolation of genes encoding the receptors for steroids, retinoids, vitamin D, and thyroid hormone and their structural and functional analysis revealed an evolutionarily conserved template for nuclear hormone receptors. This discovery sparked identification of numerous genes encoding related proteins, termed orphan receptors. Characterization of these orphan receptors and, in particular, of the retinoid X receptor (RXR) positioned nuclear receptors at the epicenter of the "Big Bang" of molecular endocrinology. This Review provides a personal perspective on nuclear receptors and explores their integrated and coordinated signaling networks that are essential for multicellular life, highlighting the RXR heterodimer and its associated ligands and transcriptional mechanism. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. The SRC homology 2 domain of Rin1 mediates its binding to the epidermal growth factor receptor and regulates receptor endocytosis.

    Science.gov (United States)

    Barbieri, M Alejandro; Kong, Chen; Chen, Pin-I; Horazdovsky, Bruce F; Stahl, Philip D

    2003-08-22

    Activated epidermal growth factor receptors (EGFRs) recruit intracellular proteins that mediate receptor signaling and endocytic trafficking. Rin1, a multifunctional protein, has been shown to regulate EGFR internalization (1). Here we show that EGF stimulation induces a specific, rapid, and transient membrane recruitment of Rin1 and that recruitment is dependent on the Src homology 2 (SH2) domain of Rin1. Immunoprecipitation of EGFR is accompanied by co-immunoprecipitation of Rin1 in a time- and ligand-dependent manner. Association of Rin1 and specifically the SH2 domain of Rin1 with the EGFR was dependent on tyrosine phosphorylation of the intracellular domain of the EGFR. The recruitment of Rin1, observed by light microscopy, indicated that although initially cytosolic, Rin1 was recruited to both plasma membrane and endosomes following EGF addition. Moreover, the expression of the SH2 domain of Rin1 substantially impaired the internalization of EGF without affecting internalization of transferrin. Finally, we found that Rin1 co-immunoprecipitated with a number of tyrosine kinase receptors but not with cargo endocytic receptors. These results indicate that Rin1 provides a link via its SH2 domain between activated tyrosine kinase receptors and the endocytic pathway through the recruitment and activation of Rab5a.

  10. Fibroblast growth factor receptors in breast cancer.

    Science.gov (United States)

    Wang, Shuwei; Ding, Zhongyang

    2017-05-01

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

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

    NARCIS (Netherlands)

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

    2012-01-01

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

  12. Expression of GABAergic receptors in mouse taste receptor cells.

    Directory of Open Access Journals (Sweden)

    Margaret R Starostik

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

  13. Toll-like receptors in neonatal sepsis.

    LENUS (Irish Health Repository)

    O'Hare, Fiona M

    2013-06-01

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

  14. Internal Affairs Allegations

    Data.gov (United States)

    Montgomery County of Maryland — This dataset contains allegations brought to the attention of the Internal Affairs Division either through external complaints or internal complaint or recognition....

  15. Modulation of the arcuate nucleus-medial preoptic nucleus lordosis regulating circuit: a role for GABAB receptors

    Science.gov (United States)

    Sinchak, Kevin; Dewing, Phoebe; Ponce, Laura; Gomez, Liliana; Christensen, Amy; Berger, Max; Micevych, Paul

    2013-01-01

    Estradiol rapidly activates a microcircuit in the arcuate nucleus of the hypothalamus (ARH) that is needed for maximal female sexual receptivity. Membrane estrogen receptor-α complexes with and signals through the metabotropic glutamate receptor-1a stimulating NPY release within the ARH activating proopiomelanocortin (POMC) neurons. These POMC neurons project to the medial preoptic nucleus (MPN) and release β-endorphin. Estradiol treatment induces activation/internalization of MPN μ-opioid receptors (MOR) to inhibit lordosis. Estradiol membrane action modulates ARH gamma-aminobutyric acid receptor-B (GABAB) activity. We tested the hypothesis that ARH GABAB receptors mediate estradiol-induced MOR activation and facilitation of sexual receptivity. Double label immunohistochemistry revealed expression of GABAB receptors in NPY, ERα and POMC expressing ARH neurons. Approximately 70% of POMC neurons expressed GABAB receptors. Because estradiol initially activates an inhibitory circuit and maintains activation of this circuit, the effects of blocking GABAB receptors were evaluated before estradiol benzoate (EB) treatment and after at the time of lordosis testing. Bilateral infusions of the GABAB receptor antagonist, CGP52432, into the ARH prior to EB treatment of ovariectomized rats prevented estradiol-induced activation/internalization of MPN MOR, and the rats remained unreceptive. However, in EB treated rats, bilateral CGP52432 infusions 30 minutes before behavior testing attenuated MOR internalization and facilitated lordosis. These results indicated that GABAB receptors were located within the lordosis-regulating ARH microcircuit and are necessary for activation and maintenance of the estradiol inhibition of lordosis behavior. Although GABAB receptors positively influence estradiol signaling, they negatively regulate lordosis behavior since GABAB activity maintains the estradiol-induced inhibition. PMID:23756153

  16. Molecular Insights into the Transmembrane Domain of the Thyrotropin Receptor.

    Directory of Open Access Journals (Sweden)

    Vanessa Chantreau

    Full Text Available The thyrotropin receptor (TSHR is a G protein-coupled receptor (GPCR that is member of the leucine-rich repeat subfamily (LGR. In the absence of crystal structure, the success of rational design of ligands targeting the receptor internal cavity depends on the quality of the TSHR models built. In this subfamily, transmembrane helices (TM 2 and 5 are characterized by the absence of proline compared to most receptors, raising the question of the structural conformation of these helices. To gain insight into the structural properties of these helices, we carried out bioinformatics and experimental studies. Evolutionary analysis of the LGR family revealed a deletion in TM5 but provided no information on TM2. Wild type residues at positions 2.58, 2.59 or 2.60 in TM2 and/or at position 5.50 in TM5 were substituted to proline. Depending on the position of the proline substitution, different effects were observed on membrane expression, glycosylation, constitutive cAMP activity and responses to thyrotropin. Only proline substitution at position 2.59 maintained complex glycosylation and high membrane expression, supporting occurrence of a bulged TM2. The TSHR transmembrane domain was modeled by homology with the orexin 2 receptor, using a protocol that forced the deletion of one residue in the TM5 bulge of the template. The stability of the model was assessed by molecular dynamics simulations. TM5 straightened during the equilibration phase and was stable for the remainder of the simulations. Our data support a structural model of the TSHR transmembrane domain with a bulged TM2 and a straight TM5 that is specific of glycoprotein hormone receptors.

  17. Studies on insulin receptor, 2

    International Nuclear Information System (INIS)

    Sakai, Yukio

    1979-01-01

    The present study is to investigate an influence of starvation and high fat diet on insulin receptor of the plasma membrane by means of radioreceptor assay using 125 I-labelled insulin. Male guinea pigs of Hartley strain were employed for the starvation study, and 125 I-insulin binding capacity on the plasma membrane of the liver and kidney was determined at 24, 48 and 72 hours of the fast after the last meal. Male rats of Wistar strain were employed for the high fat study where the diet containing 35% of butter was fed ad libitum for 38 or 68 days. The animals were killed at the fast of 12 hours, and 125 I-insulin binding capacity on the plasma membrane of the liver was determined. The results obtained are summarized as follows: 1) An increase in 125 I-insulin binding capacity on the plasma membrane of the liver and kidney was observed by the starvation for 24 to 72 hours. 2) The mechanism of the increase by starvation was considered to be different by the organs; it was due to an increase in number of insulin receptor in the liver, and due to an increase in affinity of insulin receptor in the kidney. 3) In non-obese rats fed with high fat diet, the number of insulin receptor on the liver plasma membrane showed a decrease, and this observation clearly indicated that the decrease in number of the receptor did not depend on the obesity. 4) Obese rats also fed with high fat diet presented a decrease in number of insulin receptor without an elevation of insulin levels in the circulating blood. This indicated that at least in the obese rats fed with high fat diet, the decrease in number of the receptor was not due to hyperinsulinemia. (author)

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

    Science.gov (United States)

    Cash, D J; Subbarao, K

    1987-12-01

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

  19. The Internal Audit Outsourcing

    Directory of Open Access Journals (Sweden)

    Grzegorz Gołębiowski

    2010-06-01

    Full Text Available The article explores an issue of the internal audit outsourcing. It indicates the differences between internal audit, outsourcing and cosourcing of this service as well as their advantages and disadvantages. Drawing from the research on internal audit outsourcing the recent market trends were identified as well as motivations for choosing different forms of internal auditing.

  20. The International Criminal Court

    DEFF Research Database (Denmark)

    Damgaard, Ciara Therése

    This article considers whether acts of international terrorism can and should be prosecuted before the International Criminal Court as crimes against humanity.......This article considers whether acts of international terrorism can and should be prosecuted before the International Criminal Court as crimes against humanity....

  1. Models og International Entrepreneurship

    DEFF Research Database (Denmark)

    Rask, Morten; Servais, Per

    2015-01-01

    on International Entrepreneurship, and specifically but not exclusively, International New Ventures (INVs). The three resulting ‘meta-models’ depict the activities and loci of such firms, the motivating factors that give rise to such firms and their growth modalities and strategies. These models reflect the merger...... of entrepreneurship and international business into the field of international entrepreneurship....

  2. Scavenger receptors in homeostasis and immunity.

    Science.gov (United States)

    Canton, Johnathan; Neculai, Dante; Grinstein, Sergio

    2013-09-01

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

  3. Photo-antagonism of the GABAA receptor.

    Science.gov (United States)

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

    2014-07-29

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

  4. Models of international entrepreneurship

    DEFF Research Database (Denmark)

    Rask, Morten; Servais, Per

    2012-01-01

    on International Entrepreneurship, and specifically but not exclusively, International New Ventures (INVs). The three resulting ‘meta-models’ depict the activities and loci of such firms (Figure 1), the motivating factors that give rise to such firms (Figure 2) and their growth modalities and strategies (Figure 3......). These models reflect the merger of entrepreneurship and international business into the field of international entrepreneurship. Managers in international entrepreneurial firms and students in international business and entrepreneurship can use the models as framework for understanding international...... entrepreneurship....

  5. Theory and simulations of adhesion receptor dimerization on membrane surfaces.

    Science.gov (United States)

    Wu, Yinghao; Honig, Barry; Ben-Shaul, Avinoam

    2013-03-19

    The equilibrium constants of trans and cis dimerization of membrane bound (2D) and freely moving (3D) adhesion receptors are expressed and compared using elementary statistical-thermodynamics. Both processes are mediated by the binding of extracellular subdomains whose range of motion in the 2D environment is reduced upon dimerization, defining a thin reaction shell where dimer formation and dissociation take place. We show that the ratio between the 2D and 3D equilibrium constants can be expressed as a product of individual factors describing, respectively, the spatial ranges of motions of the adhesive domains, and their rotational freedom within the reaction shell. The results predicted by the theory are compared to those obtained from a novel, to our knowledge, dynamical simulations methodology, whereby pairs of receptors perform realistic translational, internal, and rotational motions in 2D and 3D. We use cadherins as our model system. The theory and simulations explain how the strength of cis and trans interactions of adhesive receptors are affected both by their presence in the constrained intermembrane space and by the 2D environment of membrane surfaces. Our work provides fundamental insights as to the mechanism of lateral clustering of adhesion receptors after cell-cell contact and, more generally, to the formation of lateral microclusters of proteins on cell surfaces. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. The role of dopamine receptors in the neurotoxicity of methamphetamine.

    Science.gov (United States)

    Ares-Santos, S; Granado, N; Moratalla, R

    2013-05-01

    Methamphetamine is a synthetic drug consumed by millions of users despite its neurotoxic effects in the brain, leading to loss of dopaminergic fibres and cell bodies. Moreover, clinical reports suggest that methamphetamine abusers are predisposed to Parkinson's disease. Therefore, it is important to elucidate the mechanisms involved in methamphetamine-induced neurotoxicity. Dopamine receptors may be a plausible target to prevent this neurotoxicity. Genetic inactivation of dopamine D1 or D2 receptors protects against the loss of dopaminergic fibres in the striatum and loss of dopaminergic neurons in the substantia nigra. Protection by D1 receptor inactivation is due to blockade of hypothermia, reduced dopamine content and turnover and increased stored vesicular dopamine in D1R(-/-) mice. However, the neuroprotective impact of D2 receptor inactivation is partially dependent on an effect on body temperature, as well as on the blockade of dopamine reuptake by decreased dopamine transporter activity, which results in reduced intracytosolic dopamine levels in D2R(-/-) mice. © 2013 The Association for the Publication of the Journal of Internal Medicine.

  7. GRK2 Constitutively Governs Peripheral Delta Opioid Receptor Activity

    Directory of Open Access Journals (Sweden)

    Allison Doyle Brackley

    2016-09-01

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

  8. Immune receptors involved in Streptococcus suis recognition by dendritic cells.

    Directory of Open Access Journals (Sweden)

    Marie-Pier Lecours

    Full Text Available Streptococcus suis is an important swine pathogen and an emerging zoonotic agent of septicemia and meningitis. Knowledge on host immune responses towards S. suis, and strategies used by this pathogen for subversion of these responses is scarce. The objective of this study was to identify the immune receptors involved in S. suis recognition by dendritic cells (DCs. Production of cytokines and expression of co-stimulatory molecules by DCs were shown to strongly rely on MyD88-dependent signaling pathways, suggesting that DCs recognize S. suis and become activated mostly through Toll-like receptor (TLR signaling. Supporting this fact, TLR2(-/- DCs were severely impaired in the release of several cytokines and the surface expression of CD86 and MHC-II. The release of IL-12p70 and CXC10, and the expression of CD40 were found to depend on signaling by both TLR2 and TLR9. The release of IL-23 and CXCL1 were partially dependent on NOD2. Finally, despite the fact that MyD88 signaling was crucial for DC activation and maturation, MyD88-dependent pathways were not implicated in S. suis internalization by DCs. This first study on receptors involved in DC activation by S. suis suggests a major involvement of MyD88 signaling pathways, mainly (but not exclusively through TLR2. A multimodal recognition involving a combination of different receptors seems essential for DC effective response to S. suis.

  9. Regulation of G Protein-Coupled Receptors by Ubiquitination

    Directory of Open Access Journals (Sweden)

    Kamila Skieterska

    2017-04-01

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

  10. The evolution of the class A scavenger receptors

    Directory of Open Access Journals (Sweden)

    Whelan Fiona J

    2012-11-01

    Full Text Available Abstract Background The class A scavenger receptors are a subclass of a diverse family of proteins defined based on their ability to bind modified lipoproteins. The 5 members of this family are strikingly variable in their protein structure and function, raising the question as to whether it is appropriate to group them as a family based on their ligand binding abilities. Results To investigate these relationships, we defined the domain architecture of each of the 5 members followed by collecting and annotating class A scavenger receptor mRNA and amino acid sequences from publicly available databases. Phylogenetic analyses, sequence alignments, and permutation tests revealed a common evolutionary ancestry of these proteins, indicating that they form a protein family. We postulate that 4 distinct gene duplication events and subsequent domain fusions, internal repeats, and deletions are responsible for the diverse protein structures and functions of this family. Despite variation in domain structure, there are highly conserved regions across all 5 members, indicating the possibility that these regions may represent key conserved functional motifs. Conclusions We have shown with significant evidence that the 5 members of the class A scavenger receptors form a protein family. We have indicated that these receptors have a common origin which may provide insight into future functional work with these proteins.

  11. Steroid receptor expression in the fish inner earvaries with sex, social status, and reproductive state

    Directory of Open Access Journals (Sweden)

    Fernald Russell D

    2010-04-01

    Full Text Available Abstract Background Gonadal and stress-related steroid hormones are known to influence auditory function across vertebrates but the cellular and molecular mechanisms responsible for steroid-mediated auditory plasticity at the level of the inner ear remain unknown. The presence of steroid receptors in the ear suggests a direct pathway for hormones to act on the peripheral auditory system, but little is known about which receptors are expressed in the ear or whether their expression levels change with internal physiological state or external social cues. We used qRT-PCR to measure mRNA expression levels of multiple steroid receptor subtypes (estrogen receptors: ERα, ERβa, ERβb; androgen receptors: ARα, ARβ; corticosteroid receptors: GR2, GR1a/b, MR and aromatase in the main hearing organ of the inner ear (saccule in the highly social African cichlid fish Astatotilapia burtoni, and tested whether these receptor levels were correlated with circulating steroid concentrations. Results We show that multiple steroid receptor subtypes are expressed within the main hearing organ of a single vertebrate species, and that expression levels differ between the sexes. We also show that steroid receptor subtype-specific changes in mRNA expression are associated with reproductive phase in females and social status in males. Sex-steroid receptor mRNA levels were negatively correlated with circulating estradiol and androgens in both males and females, suggesting possible ligand down-regulation of receptors in the inner ear. In contrast, saccular changes in corticosteroid receptor mRNA levels were not related to serum cortisol levels. Circulating steroid levels and receptor subtype mRNA levels were not as tightly correlated in males as compared to females, suggesting different regulatory mechanisms between sexes. Conclusions This is the most comprehensive study of sex-, social-, and reproductive-related steroid receptor mRNA expression in the peripheral

  12. TAM receptor signaling in development.

    Science.gov (United States)

    Burstyn-Cohen, Tal

    2017-01-01

    TYRO3, AXL and MERTK comprise the TAM family of receptor protein tyrosine kinases. Activated by their ligands, protein S (PROS1) and growth-arrest-specific 6 (GAS6), they mediate numerous cellular functions throughout development and adulthood. Expressed by a myriad of cell types and tissues, they have been implicated in homeostatic regulation of the immune, nervous, vascular, bone and reproductive systems. The loss-of-function of TAM signaling in adult tissues culminates in the destruction of tissue homeostasis and diseased states, while TAM gain-of-function in various tumors promotes cancer phenotypes. Combinatorial ligand-receptor interactions may elicit different molecular and cellular responses. Many of the TAM regulatory functions are essentially developmental, taking place both during embryogenesis and postnatally. This review highlights current knowledge on the role of TAM receptors and their ligands during these developmental processes in the immune, nervous, vascular and reproductive systems.

  13. How calcium makes endocytic receptors attractive

    DEFF Research Database (Denmark)

    Andersen, Christian B F; Moestrup, Søren K

    2014-01-01

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

  14. Lessons from crystal structures of kainate receptors

    DEFF Research Database (Denmark)

    Møllerud, Stine; Frydenvang, Karla Andrea; Pickering, Darryl S

    2017-01-01

    Kainate receptors belong to the family of ionotropic glutamate receptors. These receptors assemble from five subunits (GluK1-5) into tetrameric ion channels. Kainate receptors are located at both pre- and postsynaptic membranes in the central nervous system where they contribute to excitatory...... synaptic transmission and modulate network excitability by regulating neurotransmitter release. Dysfunction of kainate receptors has been implicated in several neurological disorders such as epilepsy, schizophrenia and depression. Here we provide a review on the current understanding of kainate receptor...

  15. [What's new in internal medecine?

    Science.gov (United States)

    Jachiet, M; Rybojad, M; Bouaziz, J-D

    2016-12-01

    Answering the question « what's new in internal medecine in 2016? » is very challenging. We used 3 methods of article selection to reduce the selection bias: 3 authors, a systematic review of the articles discussed in the weekly bibliographic meeting of our unit (Dermatology department, Saint-Louis Hospital, Paris, France) and a selection of the best articles by several internal medecine practitioners in Paris. Eleven « hot topics » were analyzed: i/lowering cholesterol level but not blood blessure has a significant impact on cardiovascular morbi-mortality in cardiovascular intermediate risk patients; ii/the « treat to treat target » is efficient in psoriatic arthritis; iii/ a genotype/ phenotype correlation favors the separation of ileal Crohn's disease, colonic Crohn's disease and ulcerative colitis; iv/ tocilizumab treatment (anti-IL-6 monoclonal antibody ) is very efficient in giant cell arteritis and slightly efficient in systemic sclerosis; v/ combination therapy using methotrexate plus steroids compared with steroids alone becomes the « gold standard » treatment for juvenile dermatomyositis; vi/ dupilumab treatment (antibody blocking IL-4 and IL-13 receptors) is not only efficient in atopic dermatitis but also in asthma; vii/ think of eosinophilic oesophagitis in a patient with atopic dermatitis and dypshagia or food impaction; viii/ genetic A2 protein dysfunction induces NF-kB hyperactivation and an autoinflammatory disorder with features similar to Behcet's disease; ix/ no new biotherapies have shown high efficacy in systemic lupus erythematosus; x/ nanoparticles loaded with autoantigens induce Tregs and Bregs and may be a promising therapeutic option to treat auto-immune disease in the future; xi/ ipilimumab treatment (anti-CTLA4 antibody, immune checkpoint inhibitor) may induce complete remission in acute myeloid leukemia patients relapsing after haematological stem cell transplantation. Year 2016 is full of great discoveries in internal medicine

  16. A PRACTICAL APPROACH TO THE DETECTION OF ANDROGEN RECEPTOR GENE-MUTATIONS AND PEDIGREE ANALYSIS IN FAMILIES WITH X-LINKED ANDROGEN INSENSITIVITY

    NARCIS (Netherlands)

    RISSTALPERS, C; HOOGENBOEZEM, T; SLEDDENS, HFBM; VERLEUNMOOIJMAN, MCT; DEGENHART, HJ; DROP, SLS; HALLEY, DJJ; Oosterwijk, Jan; HODGINS, MB; TRAPMAN, J; BRINKMANN, AO

    Androgen insensitivity syndrome (AIS) is an X-linked disorder in which defects in the androgen receptor gene have prevented the normal development of both internal and external male structures in 46,XY individuals. This survey reports the analysis of 11 AIS subjects. The androgen receptor gene of

  17. A practical approach to the detection of androgen receptor gene mutations and pedigree analysis in families with x-linked androgen insensitivity

    NARCIS (Netherlands)

    Ris-Stalpers, C.; Hoogenboezem, T.; Sleddens, H. F.; Verleun-Mooijman, M. C.; Degenhart, H. J.; Drop, S. L.; Halley, D. J.; Oosterwijk, J. C.; Hodgins, M. B.; Trapman, J.

    1994-01-01

    Androgen insensitivity syndrome (AIS) is an X-linked disorder in which defects in the androgen receptor gene have prevented the normal development of both internal and external male structures in 46,XY individuals. This survey reports the analysis of 11 AIS subjects. The androgen receptor gene of

  18. Gαs regulates Glucagon-Like Peptide 1 Receptor-mediated cyclic AMP generation at Rab5 endosomal compartment

    Directory of Open Access Journals (Sweden)

    Shravan Babu Girada

    2017-10-01

    Conclusions: The findings provide the mechanism of endosomal cyclic AMP generation following GLP-1R activation. We identified the specific compartment that serves as an organizing center to generate endosomal cyclic AMP by internalized activated receptor complex.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  20. Stability of solubilized benzodiazepine receptors

    NARCIS (Netherlands)

    Janssen, M.J; Ensing, K; de Zeeuw, R.A

    1997-01-01

    According to the observations of other researchers, benzodiazepine receptors solubilized with sodium deoxycholate are unstable, but stability can be improved by exchanging deoxycholate for Triton X-100. In our experiments we conclude that the choice of detergent is not the restrictive factor for the

  1. Serum transferrin receptor in polycythemia.

    Science.gov (United States)

    Manteiga, R; Remacha, A F; Sardà, M P; Ubeda, J

    1998-10-01

    We measured serum transferrin receptor (sTfR) levels in 22 patients with polycythemia vera and in 26 cases of secondary polycythemia. In our study, raised sTfR levels in both polycythemia groups were related to iron deficiency.

  2. FMRFamide receptors of Helix aspersa

    International Nuclear Information System (INIS)

    Payza, K.

    1988-01-01

    A receptor binding assay and an isolated heart bioassay were used to identify and characterize the FMRFamide receptors in Helix. In the heart bioassay, FMRFamide increased myocardial contraction force. A potent FMRFamide analog, desaminoTyr-Phe-norLeu-arg-Phe-amide (daYFnLRFamide), was used as a radioiodinated receptor ligand. The high affinity binding of 125 I-daYFnLRFamide at 0 degree C to Helix brain membranes was reversible, saturable, pH-dependent and specific, with a K D of 13-14 nM. A lower affinity (245 nM) site was also observed. Radioligand binding sites were also identified in the heart, male reproductive organs and digestive organs. The structure-activity relations (SAR) of cardiostimulation correlated with the specificity of 125 I-daYFnLRFamide binding to brain and heart receptors. The SAR were similar to those of other molluscan FMRFamide bioassays, except that they showed a marked preference for some analogs with blocked amino-terminals

  3. Pharmacological approach of the receptors

    International Nuclear Information System (INIS)

    Puech, A.J.

    1989-01-01

    This paper explains the three main goals for clinical positron emission tomography (PET) studies: detection of receptor abnormalities in groups of patients to propose therapeutic indication of new ligands; validation of current hypothesis of drug effect; rational clinical drug development specially for dose-finding studies. (H.W.)

  4. Uncompetitive antagonism of AMPA receptors

    DEFF Research Database (Denmark)

    Andersen, Trine F; Tikhonov, Denis B; Bølcho, Ulrik

    2006-01-01

    Philanthotoxins are uncompetitive antagonists of Ca2+-permeable AMPA receptors presumed to bind to the pore-forming region, but a detailed molecular mechanism for this interaction is missing. Here a small library of novel philanthotoxins was designed and synthesized using a solid-phase strategy. ...

  5. NMDA receptors and memory encoding.

    Science.gov (United States)

    Morris, Richard G M

    2013-11-01

    It is humbling to think that 30 years have passed since the paper by Collingridge, Kehl and McLennan showing that one of Jeff Watkins most interesting compounds, R-2-amino-5-phosphonopentanoate (d-AP5), blocked the induction of long-term potentiation in vitro at synapses from area CA3 of the hippocampus to CA1 without apparent effect on baseline synaptic transmission (Collingridge et al., 1983). This dissociation was one of the key triggers for an explosion of interest in glutamate receptors, and much has been discovered since that collectively contributes to our contemporary understanding of glutamatergic synapses - their biophysics and subunit composition, of the agonists and antagonists acting on them, and their diverse functions in different networks of the brain and spinal cord. It can be fairly said that Collingridge et al.'s (1983) observation was the stimulus that has led, on the one hand, to structural biological work at the atomic scale describing the key features of NMDA receptors that enables their coincidence function to happen; and, on the other, to work with whole animals investigating the contributions that calcium signalling via this receptor can have on rhythmical activities controlled by spinal circuits, memory encoding in the hippocampus (the topic of this article), visual cortical plasticity, sensitization in pain, and other functions. In this article, I lay out how my then interest in long-term potentiation (LTP) as a model of memory enabled me to recognise the importance of Collingridge et al.'s discovery - and how I and my colleagues endeavoured to take things forward in the area of learning and memory. This is in some respects a personal story, and I tell it as such. The idea that NMDA receptor activation is essential for memory encoding, though not for storage, took time to develop and to be accepted. Along the way, there have been confusions, challenges, and surprises surrounding the idea that activation of NMDA receptors can

  6. Ror receptor tyrosine kinases: orphans no more

    OpenAIRE

    Green, Jennifer L.; Kuntz, Steven G.; Sternberg, Paul W.

    2008-01-01

    Receptor tyrosine kinase-like orphan receptor (Ror) proteins are a conserved family of tyrosine kinase receptors that function in developmental processes including skeletal and neuronal development, cell movement and cell polarity. Although Ror proteins were originally named because the associated ligand and signaling pathway were unknown, recent studies in multiple species have now established that Ror proteins are Wnt receptors. Depending on the cellular context, Ror proteins can either act...

  7. Benzodiazepine receptor antagonists for hepatic encephalopathy

    DEFF Research Database (Denmark)

    Als-Nielsen, B; Gluud, L L; Gluud, C

    2004-01-01

    Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy.......Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy....

  8. Apolipoprotein D Internalization Is a Basigin-dependent Mechanism.

    Science.gov (United States)

    Najyb, Ouafa; Brissette, Louise; Rassart, Eric

    2015-06-26

    Apolipoprotein D (apoD), a member of the lipocalin family, is a 29-kDa secreted glycoprotein that binds and transports small lipophilic molecules. Expressed in several tissues, apoD is up-regulated under different stress stimuli and in a variety of pathologies. Numerous studies have revealed that overexpression of apoD led to neuroprotection in various mouse models of acute stress and neurodegeneration. This multifunctional protein is internalized in several cells types, but the specific internalization mechanism remains unknown. In this study, we demonstrate that the internalization of apoD involves a specific cell surface receptor in 293T cells, identified as the transmembrane glycoprotein basigin (BSG, CD147); more particularly, its low glycosylated form. Our results show that internalized apoD colocalizes with BSG into vesicular compartments. Down-regulation of BSG disrupted the internalization of apoD in cells. In contrast, overexpression of basigin in SH-5YSY cells, which poorly express BSG, restored the uptake of apoD. Cyclophilin A, a known ligand of BSG, competitively reduced apoD internalization, confirming that BSG is a key player in the apoD internalization process. In summary, our results demonstrate that basigin is very likely the apoD receptor and provide additional clues on the mechanisms involved in apoD-mediated functions, including neuroprotection. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Design and synthesis of small molecule agonists of EphA2 receptor.

    Science.gov (United States)

    Petty, Aaron; Idippily, Nethrie; Bobba, Viharika; Geldenhuys, Werner J; Zhong, Bo; Su, Bin; Wang, Bingcheng

    2018-01-01

    Ligand-independent activation of EphA2 receptor kinase promotes cancer metastasis and invasion. Activating EphA2 receptor tyrosine kinase with small molecule agonist is a novel strategy to treat EphA2 overexpressing cancer. In this study, we performed a lead optimization of a small molecule Doxazosin that was identified as an EphA2 receptor agonist. 33 new analogs were developed and evaluated; a structure-activity relationship was summarized based on the EphA2 activation of these derivatives. Two new derivative compounds 24 and 27 showed much improved activity compared to Doxazosin. Compound 24 possesses a bulky amide moiety, and compound 27 has a dimeric structure that is very different to the parental compound. Compound 27 with a twelve-carbon linker of the dimer activated the kinase and induced receptor internalization and cell death with the best potency. Another dimer with a six-carbon linker has significantly reduced potency compared to the dimer with a longer linker, suggesting that the length of the linker is critical for the activity of the dimeric agonist. To explore the receptor binding characteristics of the new molecules, we applied a docking study to examine how the small molecule binds to the EphA2 receptor. The results reveal that compounds 24 and 27 form more hydrogen bonds to EphA2 than Doxazosin, suggesting that they may have higher binding affinity to the receptor. Published by Elsevier Masson SAS.

  10. Internal Control: Peran Dan Perkembangannya

    OpenAIRE

    Murtin, Alek

    2000-01-01

    Perhatian terhadap pentingnya internal control dalam organisasi berjalan dari waktu ke waktu untuk meningkatkan fungsi internal control yang disesuaikan dengan perkembangan lingkungan organisasi, dimulai dengan adanya internal check, kemudian internal control system, internal control structure dan terakhir adalah internal control-integrated framework. Internal control system sempat berkembang beberapa tahun di Indonesia yang selanjutnya digantikan oleh internal control structure yang digunaka...

  11. Synaptic Bistability Due to Nucleation and Evaporation of Receptor Clusters

    KAUST Repository

    Burlakov, V. M.; Emptage, N.; Goriely, A.; Bressloff, P. C.

    2012-01-01

    interacting receptors and is stabilized against clustering by a high nucleation barrier. The other state contains a receptor gas in equilibrium with a large cluster of immobile receptors, which is stabilized by the turnover rate of receptors into and out

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

    NARCIS (Netherlands)

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

    1998-01-01

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

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

    NARCIS (Netherlands)

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

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

  14. Receptores de progesterona en meningioma.

    Directory of Open Access Journals (Sweden)

    Herminio Ojeda Di Ninno

    1995-04-01

    Full Text Available Objetivo: Determinar la presencia de los receptores de progesterona en meningiomas y su frecuencia mediante la inmunohistoquímica. Material y Métodos: Se analizaron 24 muestras provenientes de pacientes intervenidos quirúrgicamente en el Instituto Nacional de Enfermedades Neoplásicas entre los años 1990 y 1992 con diagnóstico anatomopatológico de meningioma. La determinación de los receptores se hizo mediante una técnica de inmunohistoquímica rápida que permite el estudio de tejidos fijados previamente en parafina. Resultados: De los 24 casos estudiados, nueve resultaron ser positivos en la determinación de receptores de progesterona (37%. Se pudo observar un marcado predominio dentro del grupo femenino quienes constituyeron 8/9 casos positivos. Conclusiones: El empleo de esta reciente técnica de inmunohistoquímica aplicada a tejido de fijado en parafina, nos ha permitido confirmar la presencia de receptores de progesterona en meningiomas con una frecuencia elevada que creemos amerita un estudio más amplio de manera sistemática que incluya la intervención terapéutica mediante el uso de antiprogestágenos, como el Mifepristone o RU 486. De este estudio podrían beneficiarse no sólo pacientes operados recientemente sino aquellos que, intervenidos en el pasado sean detectados como portadores de receptores de progesterona mediante la aplicación de esta novedosa técnica (Rev Med Hered 1995; 6: 121-130.

  15. International aspects of fusion

    International Nuclear Information System (INIS)

    Stacey, W.M. Jr.

    1979-12-01

    International collaborative efforts in magnetic confinement fusion in which the USA is involved are reviewed. These efforts are carried under the auspices of international agencies and through bilateral agreements

  16. International images: business cards.

    Science.gov (United States)

    Gaston, S; Pucci, J

    1991-01-01

    Nursing specialists engage in a variety of international professional activities. Business cards are an important aspect of establishing a professional image. This article presents recommended business card contents, international etiquette, card design and production, and cared innovations.

  17. International trade and environment

    International Nuclear Information System (INIS)

    Posada L, Luis Guillermo

    2000-01-01

    Topics are presented as economic theory and theory of the international trade, international dimension of the environmental problems, economic prosperity, environmental quality and lineament are given for an alternative, among others

  18. Generalized internal multiple imaging

    KAUST Repository

    Zuberi, Mohammad Akbar Hosain

    2014-12-04

    Various examples are provided for generalized internal multiple imaging (GIMI). In one example, among others, a method includes generating a higher order internal multiple image using a background Green\\'s function and rendering the higher order internal multiple image for presentation. In another example, a system includes a computing device and a generalized internal multiple imaging (GIMI) application executable in the computing device. The GIMI application includes logic that generates a higher order internal multiple image using a background Green\\'s function and logic that renders the higher order internal multiple image for display on a display device. In another example, a non-transitory computer readable medium has a program executable by processing circuitry that generates a higher order internal multiple image using a background Green\\'s function and renders the higher order internal multiple image for display on a display device.

  19. International energy outlook, 2010

    Science.gov (United States)

    2010-07-01

    This report presents international energy projections through 2035, : prepared by the U.S. Energy Information Administration, including outlooks : for major energy fuels and associated carbon dioxide emissions. The International Energy Outlook 2010 (...

  20. International diversification and Microfinance

    NARCIS (Netherlands)

    Galema, R.; Lensink, B.W.; Spierdijk, L.

    2011-01-01

    International commercial banks, institutional investors, and private investors have become increasingly interested in financing microfinance institutions (MFIs). This paper investigates whether adding microfinance funds to a portfolio of risky international assets yields diversification gains. By

  1. International diversification and Microfinance

    NARCIS (Netherlands)

    Galema, Rients; Lensink, Robert; Spierdijk, Laura

    International commercial banks, institutional investors, and private investors have become increasingly interested in financing microfinance institutions (MFIs). This paper investigates whether adding microfinance funds to a portfolio of risky international assets yields diversification gains. By

  2. Alternative international currencies

    Directory of Open Access Journals (Sweden)

    Rozhentsova Vladimirovna Elena

    2012-01-01

    Full Text Available The modern international monetary system has a number of flaws and therefore needs cardinal change. Hence, economists from all over the world are suggesting alternative international currencies that would make the international monetary system more efficient. However, it is essential when approaching the creation of a new international currency to analyze and take into account the experience of all the past international currencies. Therefore this paper begins with an exploration of the drawbacks of each of the past and present international currencies. Drawing on this analysis a justification will be made for the necessity of introducing a new international currency, pointing to the requirements it should meet. Further on, this paper proposes an alternative theoretically possible variant of the international currency, with a fixed value relative to a commodity basket. An abstract example is used to demonstrate its composition and circulation mechanism.

  3. Generalized internal multiple imaging

    KAUST Repository

    Zuberi, Mohammad Akbar Hosain; Alkhalifah, Tariq

    2014-01-01

    Various examples are provided for generalized internal multiple imaging (GIMI). In one example, among others, a method includes generating a higher order internal multiple image using a background Green's function and rendering the higher order internal multiple image for presentation. In another example, a system includes a computing device and a generalized internal multiple imaging (GIMI) application executable in the computing device. The GIMI application includes logic that generates a higher order internal multiple image using a background Green's function and logic that renders the higher order internal multiple image for display on a display device. In another example, a non-transitory computer readable medium has a program executable by processing circuitry that generates a higher order internal multiple image using a background Green's function and renders the higher order internal multiple image for display on a display device.

  4. A new family of insect tyramine receptors

    DEFF Research Database (Denmark)

    Cazzamali, Giuseppe; Klærke, Dan Arne; Grimmelikhuijzen, Cornelis J P

    2005-01-01

    in the genomic databases from the malaria mosquito Anopheles gambiae and the honeybee Apis mellifera. These four tyramine or tyramine-like receptors constitute a new receptor family that is phylogenetically distinct from the previously identified insect octopamine/tyramine receptors. The Drosophila tyramine...

  5. Imaging of receptors in clinical neurosciences

    NARCIS (Netherlands)

    Korf, J

    This article deals with the question why should one determine receptors in the brain with positron and single photon emission tomography (PET and SPECT, respectively). Radiopharmaceuticals for a wide variety of receptors are available now. Receptors studies with PET and SPECT have thus far focused

  6. Receptor conversion in distant breast cancer metastases

    NARCIS (Netherlands)

    Hoefnagel, L.D.C.

    2013-01-01

    The routine pathological work-up of breast cancer includes the evaluation of the estrogen receptor (ERα), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) which reveals biological information about the tumour as well as provides predictive biomarkers regarding hormonal

  7. Molecular pharmacology of human NMDA receptors

    DEFF Research Database (Denmark)

    Hedegaard, Maiken; Hansen, Kasper Bø; Andersen, Karen Toftegaard

    2012-01-01

    N-methyl-d-aspartate (NMDA) receptors are ionotropic glutamate receptors that mediate excitatory neurotransmission. NMDA receptors are also important drug targets that are implicated in a number of pathophysiological conditions. To facilitate the transition from lead compounds in pre-clinical ani...

  8. α1B-Adrenergic Receptors Differentially Associate with Rab Proteins during Homologous and Heterologous Desensitization

    Science.gov (United States)

    Castillo-Badillo, Jean A.; Sánchez-Reyes, Omar B.; Alfonzo-Méndez, Marco A.; Romero-Ávila, M. Teresa; Reyes-Cruz, Guadalupe; García-Sáinz, J. Adolfo

    2015-01-01

    Internalization of G protein-coupled receptors can be triggered by agonists or by other stimuli. The process begins within seconds of cell activation and contributes to receptor desensitization. The Rab GTPase family controls endocytosis, vesicular trafficking, and endosomal fusion. Among their remarkable properties is the differential distribution of its members on the surface of various organelles. In the endocytic pathway, Rab 5 controls traffic from the plasma membrane to early endosomes, whereas Rab 4 and Rab 11 regulate rapid and slow recycling from early endosomes to the plasma membrane, respectively. Moreover, Rab 7 and Rab 9 regulate the traffic from late endosomes to lysosomes and recycling to the trans-Golgi. We explore the possibility that α1B-adrenergic receptor internalization induced by agonists (homologous) and by unrelated stimuli (heterologous) could involve different Rab proteins. This possibility was explored by Fluorescence Resonance Energy Transfer (FRET) using cells coexpressing α1B-adrenergic receptors tagged with the red fluorescent protein, DsRed, and different Rab proteins tagged with the green fluorescent protein. It was observed that when α1B-adrenergic receptors were stimulated with noradrenaline, the receptors interacted with proteins present in early endosomes, such as the early endosomes antigen 1, Rab 5, Rab 4, and Rab 11 but not with late endosome markers, such as Rab 9 and Rab 7. In contrast, sphingosine 1-phosphate stimulation induced rapid and transient α1B-adrenergic receptor interaction of relatively small magnitude with Rab 5 and a more pronounced and sustained one with Rab 9; interaction was also observed with Rab 7. Moreover, the GTPase activity of the Rab proteins appears to be required because no FRET was observed when dominant-negative Rab mutants were employed. These data indicate that α1B-adrenergic receptors are directed to different endocytic vesicles depending on the desensitization type (homologous vs

  9. Devil's Claw to suppress appetite--ghrelin receptor modulation potential of a Harpagophytum procumbens root extract.

    Directory of Open Access Journals (Sweden)

    Cristina Torres-Fuentes

    Full Text Available Ghrelin is a stomach-derived peptide that has been identified as the only circulating hunger hormone that exerts a potent orexigenic effect via activation of its receptor, the growth hormone secretagogue receptor (GHS-R1a. Hence, the ghrelinergic system represents a promising target to treat obesity and obesity-related diseases. In this study we analysed the GHS-R1a receptor activating potential of Harpagophytum procumbens, popularly known as Devil's Claw, and its effect on food intake in vivo. H. procumbens is an important traditional medicinal plant from Southern Africa with potent anti-inflammatory and analgesic effects. This plant has been also used as an appetite modulator but most evidences are anecdotal and to our knowledge, no clear scientific studies relating to appetite modulation have been done to this date. The ghrelin receptor activation potential of an extract derived from the dried tuberous roots of H. procumbens was analysed by calcium mobilization and receptor internalization assays in human embryonic kidney cells (Hek stably expressing the GHS-R1a receptor. Food intake was investigated in male C57BL/6 mice following intraperitoneal administration of H. procumbens root extract in ad libitum and food restricted conditions. Exposure to H. procumbens extract demonstrated a significant increased cellular calcium influx but did not induce subsequent GHS-R1a receptor internalization, which is a characteristic for full receptor activation. A significant anorexigenic effect was observed in male C57BL/6 mice following peripheral administration of H. procumbens extract. We conclude that H. procumbens root extract is a potential novel source for potent anti-obesity bioactives. These results reinforce the promising potential of natural bioactives to be developed into functional foods with weight-loss and weight maintenance benefits.

  10. International double taxation

    OpenAIRE

    Körbl, Hugo

    2012-01-01

    1 Summary This thesis deals with the issue of international double taxation of income and capital and methods for its solution. International double taxation is an issue which states began to deal with in the late 19th century. This interest intensified after the First World War when also the League of Nations (predecessor of the United Nations) began to deal with international double taxation. Most attention the phenomenon of double taxation of income and capital with an international elemen...

  11. International Construction Measurement Standard

    OpenAIRE

    Mitchell, Charles

    2016-01-01

    The International Construction Measurement Standard Coalition (the Coalition) was formed on 17 June 2015 after meeting at the International Monetary Fund in Washington DC, USA. The Coalition, comprising the organisations listed below at the date of publication, aims to bring about consistency in construction cost reporting standards internationally. This is achieved by the creation and adoption of this ICMS, an agreed international standard for the structuring and presentation of cost reports...

  12. Epsin 1 is involved in recruitment of ubiquitinated EGF receptors into clathrin-coated pits

    DEFF Research Database (Denmark)

    Kazazic, Maja; Bertelsen, Vibeke; Pedersen, Ketil Winther

    2008-01-01

    . Furthermore, RNAi-mediated knock down of epsin 1 was found to inhibit internalization of the EGFR, while having no effect on endocytosis of the transferrin receptor. Additionally, upon knock down of epsin 1, translocation of the EGFR to central parts of clathrin-coated pits was inhibited. This supports...

  13. A Realistic International Economics.

    Science.gov (United States)

    Culbertson, John M.

    1987-01-01

    Criticizes college textbooks for adopting a "party line" of laissez-faire economic doctrine which asserts the benefits of free trade. Offers an alternative interpretation of international trade, covering such topics as the effect of unregulated international trade on wage levels, and international lending. (JDH)

  14. UNCLOS and International Law

    DEFF Research Database (Denmark)

    Martinez Romera, Beatriz; Coelho, Nelson F.

    2018-01-01

    , treaty law is only one of many sources of the law that governs international relations, the others being customary international law and principles of law. The main conclusion of this chapter is that states may have to wake up to the limitations of the UNCLOS and that this will require understanding...... the relative role of this treaty among other sources of international law....

  15. Petroleum and international policy

    International Nuclear Information System (INIS)

    Pertuzio, A.

    2002-01-01

    To illustrate the relation between the petroleum and the international policy, the author presents the place of the petroleum industry in the international relations by an analysis of the historical aspects, the states and international organizations interventions and the prices evolution. (A.L.B.)

  16. Unit III: International Conflict.

    Science.gov (United States)

    Maxey, Phyllis

    1983-01-01

    This lesson helps students understand the global network involved in international events. Students have an opportunity to examine the impact of international law and the role of international organizations, national governments, and private individuals in the effort to secure the release of United States hostages in Iran. (AM)

  17. International Corporate Debt Market

    OpenAIRE

    Manuela Geranio; Issam Hallak

    2012-01-01

    Research on international debt markets has chiefly investigated sovereign debt markets. We suggest a review of the different types of borrowers and the differences in the instruments. In particular we show that syndicated loans are an essential tool of international debt markets to monitor international markets borrowers. We also show by looking at the details of these instruments the mechanisms behind such tools.

  18. Microscopic visualization of metabotropic glutamate receptors on the surface of living cells using bifunctional magnetic resonance imaging probes.

    Science.gov (United States)

    Mishra, Anurag; Mishra, Ritu; Gottschalk, Sven; Pal, Robert; Sim, Neil; Engelmann, Joern; Goldberg, Martin; Parker, David

    2014-02-19

    A series of bimodal metabotropic glutamate-receptor targeted MRI contrast agents has been developed and evaluated, based on established competitive metabotropic Glu receptor subtype 5 (mGluR5) antagonists. In order to directly visualize mGluR5 binding of these agents on the surface of live astrocytes, variations in the core structure were made. A set of gadolinium conjugates containing either a cyanine dye or a fluorescein moiety was accordingly prepared, to allow visualization by optical microscopy in cellulo. In each case, surface receptor binding was compromised and cell internalization observed. Another approach, examining the location of a terbium analogue via sensitized emission, also exhibited nonspecific cell uptake in neuronal cell line models. Finally, biotin derivatives of two lead compounds were prepared, and the specificity of binding to the mGluR5 cell surface receptors was demonstrated with the aid of their fluorescently labeled avidin conjugates, using both total internal reflection fluorescence (TIRF) and confocal microscopy.

  19. Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells

    International Nuclear Information System (INIS)

    Niessen, Markus; Jaschinski, Frank; Item, Flurin; McNamara, Morgan P.; Spinas, Giatgen A.; Trueb, Thomas

    2007-01-01

    Ligand-activated insulin receptor (IR) attracts and phosphorylates various substrates such as insulin receptor substrates 1-4 (IRS) and Shc. To investigate how binding affinity for substrate affects signalling we generated chimeric receptors with the β-chain of the insulin receptor containing NPXY motives with different affinities for receptor substrates. We found that the extent of receptor tyrosine phosphorylation positively correlates with binding affinity towards IRS1/2 but not towards Shc. Moreover, overexpression of IRS1 or IRS2 but not of Shc increased IR tyrosine phosphorylation in a dose-dependent manner, also independent of insulin. Molecular truncations of IRS1 revealed that neither the isolated PH and PTB domains nor the C-terminus with the tyrosine phosphorylation sites alone are sufficient for substrate-dependent receptor activation. Overexpression of IRS1 and IRS2 impaired insulin-induced internalization of the IR in a dose-dependent manner suggesting that IRS proteins prevent endosome-associated receptor dephosphorylation/inactivation. IRS1 and IRS2 could therefore target the activated IR to different cellular compartments. Overexpression of IRS1 and IRS2 inhibited insulin-stimulated activation of the MAP kinases Erk1/2 while it increased/induced activation of Akt/PKB. Finally, overexpression of IRS1 and IRS2 but not of Shc induced DNA synthesis in starved CHO-IR cells independent of exogenous growth factors. Our results demonstrate that variations in cellular IRS1 and IRS2 concentration affect insulin signalling both upstream and downstream and that IRS proteins could play instructive rather than just permissive roles in signal transmission

  20. Neurology and international organizations.

    Science.gov (United States)

    Mateen, Farrah J

    2013-07-23

    A growing number of international stakeholders are engaged with neurologic diseases. This article provides a brief overview of important international stakeholders in the practice of neurology, including global disease-specific programs, United Nations agencies, governmental agencies with international influence, nongovernmental organizations, international professional organizations, large private donors, private-public partnerships, commercial interests, armed forces, and universities and colleges. The continued engagement of neurologists is essential for the growing number of international organizations that can and should incorporate neurologic disease into their global agendas.

  1. Windows® Internals

    CERN Document Server

    Russinovich, Mark E; Ionescu, Alex

    2009-01-01

    See how the core components of the Windows operating system work behind the scenes-guided by a team of internationally renowned internals experts. Fully updated for Windows Server 2008 and Windows Vista, this classic guide delivers key architectural insights on system design, debugging, performance, and support-along with hands-on experiments to experience Windows internal behavior firsthand.Delve inside Windows architecture and internals:Understand how the core system and management mechanisms work-from the object manager to services to the registryExplore internal system data structures usin

  2. Some theoretical aspects of hormone receptor determination

    International Nuclear Information System (INIS)

    Sluiter, W.J.

    1981-01-01

    Suitable antisera for determination of hormone receptors are not available for the majority of hormone receptors. Therefore, the determination of hormone receptors is mostly performed in terms of binding capacity for the appropriate hormone, using radioactive hormone labels. Some theoretical aspects of such a receptor determination are discussed including the length of incubation (total or unoccupied receptor concentration), single point or multiple point (Scatchard) analysis (regarding the influence of other specific binders), the correction procedure for non-specific binding and the influence of the circulating hormone level. (Auth.)

  3. Dynamical Binding Modes Determine Agonistic and Antagonistic Ligand Effects in the Prostate-Specific G-Protein Coupled Receptor (PSGR).

    Science.gov (United States)

    Wolf, Steffen; Jovancevic, Nikolina; Gelis, Lian; Pietsch, Sebastian; Hatt, Hanns; Gerwert, Klaus

    2017-11-22

    We analysed the ligand-based activation mechanism of the prostate-specific G-protein coupled receptor (PSGR), which is an olfactory receptor that mediates cellular growth in prostate cancer cells. Furthermore, it is an olfactory receptor with a known chemically near identic antagonist/agonist pair, α- and β-ionone. Using a combined theoretical and experimental approach, we propose that this receptor is activated by a ligand-induced rearrangement of a protein-internal hydrogen bond network. Surprisingly, this rearrangement is not induced by interaction of the ligand with the network, but by dynamic van der Waals contacts of the ligand with the involved amino acid side chains, altering their conformations and intraprotein connectivity. Ligand recognition in this GPCR is therefore highly stereo selective, but seemingly lacks any ligand recognition via polar contacts. A putative olfactory receptor-based drug design scheme will have to take this unique mode of protein/ligand action into account.

  4. Identification of G-Protein-Coupled Receptors (GPCRs) in Pulmonary Artery Smooth Muscle Cells as Novel Therapeutic Targets

    Science.gov (United States)

    2015-10-01

    orphan GPCRs has been the difficulty in setting up screens for ligands, as the G protein coupling of an orphan may not be known; chimeric G proteins...G protein-coupled receptor quantification using peptide group-specific enrichment combined with internal peptide standard reporter cali- bration. J...novel peptides and their receptors. AAPS J 12:378–384. Pan W (2002) A comparative review of statistical methods for discovering differen- tially

  5. Membrane cholesterol effect on the 5-HT2A receptor: Insights into the lipid-induced modulation of an antipsychotic drug target.

    Science.gov (United States)

    Ramírez-Anguita, Juan Manuel; Rodríguez-Espigares, Ismael; Guixà-González, Ramon; Bruno, Agostino; Torrens-Fontanals, Mariona; Varela-Rial, Alejandro; Selent, Jana

    2018-01-01

    The serotonin 5-hydroxytryptamine 2A (5-HT 2A ) receptor is a G-protein-coupled receptor (GPCR) relevant for the treatment of CNS disorders. In this regard, neuronal membrane composition in the brain plays a crucial role in the modulation of the receptor functioning. Since cholesterol is an essential component of neuronal membranes, we have studied its effect on the 5-HT 2A receptor dynamics through all-atom MD simulations. We find that the presence of cholesterol in the membrane increases receptor conformational variability in most receptor segments. Importantly, detailed structural analysis indicates that conformational variability goes along with the destabilization of hydrogen bonding networks not only within the receptor but also between receptor and lipids. In addition to increased conformational variability, we also find receptor segments with reduced variability. Our analysis suggests that this increased stabilization is the result of stabilizing effects of tightly bound cholesterol molecules to the receptor surface. Our finding contributes to a better understanding of membrane-induced alterations of receptor dynamics and points to cholesterol-induced stabilizing and destabilizing effects on the conformational variability of GPCRs. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

  6. Entry of Francisella tularensis into Murine B Cells: The Role of B Cell Receptors and Complement Receptors.

    Directory of Open Access Journals (Sweden)

    Lenka Plzakova

    Full Text Available Francisella tularensis, the etiological agent of tularemia, is an intracellular pathogen that dominantly infects and proliferates inside phagocytic cells but can be seen also in non-phagocytic cells, including B cells. Although protective immunity is known to be almost exclusively associated with the type 1 pathway of cellular immunity, a significant role of B cells in immune responses already has been demonstrated. Whether their role is associated with antibody-dependent or antibody-independent B cell functions is not yet fully understood. The character of early events during B cell-pathogen interaction may determine the type of B cell response regulating the induction of adaptive immunity. We used fluorescence microscopy and flow cytometry to identify the basic requirements for the entry of F. tularensis into B cells within in vivo and in vitro infection models. Here, we present data showing that Francisella tularensis subsp. holarctica strain LVS significantly infects individual subsets of murine peritoneal B cells early after infection. Depending on a given B cell subset, uptake of Francisella into B cells is mediated by B cell receptors (BCRs with or without complement receptor CR1/2. However, F. tularensis strain FSC200 ΔiglC and ΔftdsbA deletion mutants are defective in the ability to enter B cells. Once internalized into B cells, F. tularensis LVS intracellular trafficking occurs along the endosomal pathway, albeit without significant multiplication. The results strongly suggest that BCRs alone within the B-1a subset can ensure the internalization process while the BCRs on B-1b and B-2 cells need co-signaling from the co receptor containing CR1/2 to initiate F. tularensis engulfment. In this case, fluidity of the surface cell membrane is a prerequisite for the bacteria's internalization. The results substantially underline the functional heterogeneity of B cell subsets in relation to F. tularensis.

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

    Science.gov (United States)

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

    2007-09-25

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

  8. [Ceruloplasmin receptor on human erythrocytes].

    Science.gov (United States)

    Saenko, E L; Basevich, V V; Iaropolov, A I

    1988-08-01

    The structural fragments of the human ceruloplasmin (CP) molecule and of erythrocyte receptors which provide for the specific interaction of CP with erythrocytes were identified, and their properties were investigated. The interaction of CP with erythrocytes, both intact and treated with neuroaminidase and proteolytic enzymes (trypsin, chymotrypsin, papaine, pronase E) is described. Experiments with CP reception were performed at 4 degrees C, using [125I]CP and [125I]asialo-CP. The parameters of binding were determined in Scatchard plots. It was demonstrated that the specific binding of CP to erythrocyte receptors is determined by its interaction with two structural sites of the carbohydrate moiety of the CP molecule, i.e., the terminal residues of sialic acids and a site, (formula; see text) located at a large distance from the chain terminus.

  9. β(2) -adrenergic receptor Thr164IIe polymorphism, blood pressure and ischaemic heart disease in 66 750 individuals

    DEFF Research Database (Denmark)

    Thomsen, M; Dahl, Morten; Tybjærg-Hansen, Anne

    2012-01-01

    Abstract. Thomsen M, Dahl M, Tybjaerg-Hansen A, Nordestgaard BG (Copenhagen University Hospital, Copenhagen; University of Copenhagen, Copenhagen, Denmark). ß(2) -adrenergic receptor Thr164IIe polymorphism, blood pressure and ischaemic heart disease in 66 750 individuals. J Intern Med 2011; doi: 10.......1111/j.1365-2796.2011.02447.x Objectives. The ß(2) -adrenergic receptor (ADRB2) is located on smooth muscle cells and is an important regulator of smooth muscle tone. The Thr164Ile polymorphism (rs1800888) in the ADRB2 gene is rare but has profound functional consequences on receptor function and could...

  10. NGA/Insulin receptor scanning

    International Nuclear Information System (INIS)

    Kurtaran, A.; Virgolini, I.

    1994-01-01

    Tc-99m-galactosyl-neoglycoalbumin (NGA) is one of the first receptor-based radiopharmaceuticals which specifically recognizes the hepatic binding protein (HBP) located on the surface of the hepatocytes. The exclusive interactin of NGA with HBP provided the basis for a kinetic model for the evaluation hepatocellular function. During the last years we have used NGA in more than 300 patients with various liver diseases including liver cirrhosis (Stages Child A to Child C), viral hepatitis, and carcinomas. In these studies, the calculated HBP densities, after i.v.-injection of Tc-99m-NGA, significantly correlated with the clinical course of the diseases. Furthermore, similar to conventional Tc-colloid, NGA provided excellent demonstration of 'cold spots' for hepatic masses. In a further approach we used another hepatocyte receptor-seeking radioligand, I-123-Tyr-A14- insulin, and found, that its in vitro-binding to hepatocellular carcinomas is greatly enhanced over normal hepatic tissue. On this basis, we developed a double-tracer method using NGA and insulin in a single study. Thus, areas of 'cold spots' identifying hepatic masses on NGA scans, take up I-123-Tyr-A14-insulin immediately after i.v.-injection. This was true for hepatocellular hepatomas, but not for adenocarcinomas. In conclusion, NGA/insulin receptor scanning could be a novel and save method for the demonstration of hepatocellular hepatomas. (author)

  11. PAF receptor structure: a hypothesis.

    Science.gov (United States)

    Godfroid, J J; Dive, G; Lamotte-Brasseur, J; Batt, J P; Heymans, F

    1991-12-01

    Different hypotheses of the structure of platelet-activating factor (PAF) receptor based on structure-activity relationships of agonists and antagonists are reviewed. For an agonistic effect, strong hydrophobic interactions and an ether function are required in position-1 of the glycerol backbone; chain length limitations and steric hindrance demand a small group in position-2. The unusual structural properties of non-PAF-like antagonists required 3-D electrostatic potential calculations. This method applied to seven potent antagonists suggests a strong "Cache-orielles" (ear-muff) effect, i.e., two strong electronegative wells (isocontour at -10 Kcal/mole) are located at 180 degrees to each other and at a relatively constant distance. Initial consideration of the "Cache-oreilles" effect implied the structure of a bipolarized cylinder of 10-12 A diameter for the receptor. However, very recent results on studies with agonists and antagonists structurally similar to PAF suggest that the receptor may in fact be a multi-polarized cylinder.

  12. NGA/Insulin receptor scanning

    Energy Technology Data Exchange (ETDEWEB)

    Kurtaran, A; Virgolini, I [Vienna Univ. (Austria). Abt. fuer Nuklearmedizin; Angelberger, P [Ludwig Boltzmann-Institut fuer Nuklearmedizin, Vienna (Austria)

    1994-10-01

    Tc-99m-galactosyl-neoglycoalbumin (NGA) is one of the first receptor-based radiopharmaceuticals which specifically recognizes the hepatic binding protein (HBP) located on the surface of the hepatocytes. The exclusive interactin of NGA with HBP provided the basis for a kinetic model for the evaluation hepatocellular function. During the last years we have used NGA in more than 300 patients with various liver diseases including liver cirrhosis (Stages Child A to Child C), viral hepatitis, and carcinomas. In these studies, the calculated HBP densities, after i.v.-injection of Tc-99m-NGA, significantly correlated with the clinical course of the diseases. Furthermore, similar to conventional Tc-colloid, NGA provided excellent demonstration of `cold spots` for hepatic masses. In a further approach we used another hepatocyte receptor-seeking radioligand, I-123-Tyr-A14- insulin, and found, that its in vitro-binding to hepatocellular carcinomas is greatly enhanced over normal hepatic tissue. On this basis, we developed a double-tracer method using NGA and insulin in a single study. Thus, areas of `cold spots` identifying hepatic masses on NGA scans, take up I-123-Tyr-A14-insulin immediately after i.v.-injection. This was true for hepatocellular hepatomas, but not for adenocarcinomas. In conclusion, NGA/insulin receptor scanning could be a novel and save method for the demonstration of hepatocellular hepatomas. (author).

  13. Lymphocyte receptors for pertussis toxin

    Energy Technology Data Exchange (ETDEWEB)

    Clark, C.G.; Armstrong, G.D. (Univ. of Alberta, Edmonton (Canada))

    1990-12-01

    We have investigated human T-lymphocyte receptors for pertussis toxin by affinity isolation and photoaffinity labeling procedures. T lymphocytes were obtained from peripheral human blood, surface iodinated, and solubilized in Triton X-100. The iodinated mixture was then passed through pertussis toxin-agarose, and the fractions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autoradiography of the fixed, dried gels revealed several bands in the pertussis toxin-bound fraction that were not observed in fractions obtained from histone or fetuin-agarose. Further investigations employed a photoaffinity labeling reagent, sulfosuccinimidyl 2-(p-azido-salicylamido)-1,3'-dithiopropionate, to identify pertussis toxin receptors in freshly isolated peripheral blood monocytic cells, T lymphocytes, and Jurkat cells. In all three cell systems, the pertussis toxin affinity probe specifically labeled a single protein species with an apparent molecular weight of 70,000 that was not observed when the procedure was performed in the presence of excess unmodified pertussis toxin. A protein comparable in molecular weight to the one detected by the photoaffinity labeling technique was also observed among the species that bound to pertussis toxin-agarose. The results suggest that pertussis toxin may bind to a 70,000-Da receptor in human T lymphocytes.

  14. International safeguards and international nuclear trade

    International Nuclear Information System (INIS)

    Felten, P.

    1991-01-01

    A particular feature of nuclear trade is the need to ensure a good equilibrium between technology transfer and the requirements linked to non proliferation of nuclear weapons. The recent dramatic changes that occurred on the international scene have particularly underlined the difficulty to reach this equilibrium, reminding us the fragility of the existing order and the responsibility of the nuclear community in the field of non-proliferation. Consequently, there is a need for an international thorough review of the actual non proliferation tools developed until now. This review could lead to reconsider some of the dogmas upon which the present safeguard system is based

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

    Science.gov (United States)

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

    2006-06-01

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

  16. Characterization of collagenase-3 binding and internalization by rabbit chondrocytes

    International Nuclear Information System (INIS)

    Raggatt, L.J.; Choundhury, I.; Williams, S.

    2002-01-01

    Full text: Collagenase-3 (MMP-13) is an extracellular matrix metalloproteinase that cleaves type II collagen, the major protein component of cartilage, with high specificity. Several studies have identified increased levels of MMP-13 in arthritic synovial fluid where it may contribute to matrix destruction in this disease. Our laboratory has previously documented a process where by osteoblastic cells remove MMP-13 from the surrounding milieu by binding the enzyme to a specific receptor. The enzyme is then internalized and degraded through the actions of the endocytotic receptor, the low-density lipoprotein receptor-related protein (LRP). Such a mechanism provides for a controlled elimination of a potentially destructive enzyme from the extracellular environment. This process of MMP-13 internalization also occurs in chondrocytes and is significantly reduced in OA chondrocytes. We are currently characterizing the internalization of MMP-13 in normal rabbit chondrocytes. Primary rabbit chondrocytes were harvested and cultured in monolayers for three passages. Reverse transcription polymerase chain reaction (RT-PCR) was used to asses the cell phenotype during the culture period and the rabbit chondrocytes were found to express the cartilage specific genes aggrecan and type II collagen throughout this time. 125I-MMP-13 was used to assess the ability of the rabbit chondrocytes to bind MMP-13. Appreciable specific cell-association of MMP-13 was detected after 10 mm of exposure to the ligand and equilibrium was obtained after 2 h. After identifying the time to equilibrium we determined whether binding was saturable by incubating the chondrocytes with increasing concentrations of 125I-MMP-13 ranging from 0 to 100 nM at 4 deg C for 2h. The amount of specifically associated MMP-13 approached saturation at 75 nM, allowing assessment of the receptor kinetics. Finally, we have assessed the ability of rabbit chondrocytes to internalize a single cohort of 125I-MMP-13 over time at

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

    Science.gov (United States)

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

    2015-01-01

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

  18. Optodynamic simulation of β-adrenergic receptor signalling.

    Science.gov (United States)

    Siuda, Edward R; McCall, Jordan G; Al-Hasani, Ream; Shin, Gunchul; Il Park, Sung; Schmidt, Martin J; Anderson, Sonya L; Planer, William J; Rogers, John A; Bruchas, Michael R

    2015-09-28

    Optogenetics has provided a revolutionary approach to dissecting biological phenomena. However, the generation and use of optically active GPCRs in these contexts is limited and it is unclear how well an opsin-chimera GPCR might mimic endogenous receptor activity. Here we show that a chimeric rhodopsin/β2 adrenergic receptor (opto-β2AR) is similar in dynamics to endogenous β2AR in terms of: cAMP generation, MAP kinase activation and receptor internalization. In addition, we develop and characterize a novel toolset of optically active, functionally selective GPCRs that can bias intracellular signalling cascades towards either G-protein or arrestin-mediated cAMP and MAP kinase pathways. Finally, we show how photoactivation of opto-β2AR in vivo modulates neuronal activity and induces anxiety-like behavioural states in both fiber-tethered and wireless, freely moving animals when expressed in brain regions known to contain β2ARs. These new GPCR approaches enhance the utility of optogenetics and allow for discrete spatiotemporal control of GPCR signalling in vitro and in vivo.

  19. Localization of mineralocorticoid receptors at mammalian synapses.

    Directory of Open Access Journals (Sweden)

    Eric M Prager

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

  20. Protein Connectivity in Chemotaxis Receptor Complexes.

    Directory of Open Access Journals (Sweden)

    Stephan Eismann

    2015-12-01

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

  1. Characterization of astrocytic and neuronal benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Bender, A.S.

    1988-01-01

    Primary cultures of astrocytes and neurons express benzodiazepine receptors. Neuronal benzodiazepine receptors were of high-affinity, K{sub D} values were 7.5-43 nM and the densities of receptors (B{sub max}) were 924-4131 fmol/mg protein. Astrocytes posses a high-affinity benzodiazepine receptor, K{sub D} values were 6.6-13 nM. The B{sub max} values were 6,033-12,000 fmol/mg protein. The pharmacological profile of the neuronal benzodiazepine receptor was that of the central-type benzodiazepine receptor, where clonazepam has a high-affinity and Ro 5-4864 (4{prime}-chlorodiazepam) has a low-affinity. Whereas astrocytic benzoidazepine receptor was characteristic of the so called peripheral-type benzodiazepine receptors, which shows a high-affinity towards Ro 5-4863, and a low-affinity towards clonazepam. The astrocytic benzodiazepine receptors was functionally correlated with voltage dependent calcium channels, since dihydropyridines and benzodiazepines interacted with ({sup 3}H) diazepam and ({sup 3}H) nitrendipine receptors with the same rank order of potency, showing a statistically significant correlation. No such correlation was observed in neurons.

  2. International network competition

    OpenAIRE

    Tangerås, Thomas P.; Tåg, Joacim

    2014-01-01

    We analyse network competition in a market with international calls. National regulatory agencies (NRAs) have incentives to set regulated termination rates above marginal cost to extract rent from international call termination. International network ownership and deregulation are alternatives to combat the incentives of NRAs to distort termination rates. We provide conditions under which each of these policies increase efficiency and aggregate welfare. Our findings provide theoretical suppor...

  3. International business transactions

    OpenAIRE

    Buczkowski, Bogdan

    2016-01-01

    Running a business on an international scale requires not only a substantial body of knowledge but also the ability to apply it in practice. That is why our textbook, with a vast collection of practical examples, discusses a wide variety of pertinent issues connected with business operations in international markets, from international market analysis, drafting business plans, concluding business transactions and the insurance of goods through to customs clearance procedures and professional ...

  4. Emancipating Labor Internationalism

    OpenAIRE

    Waterman, Peter

    2004-01-01

    The secular trinity of c19th socialism was Labor-Internationalism-Emancipation. As early-industrial capitalism developed into a national-industrial-colonial capitalism, the internationalism of labor became literally international, and simultaneously lost its emancipatory aspiration and capacity (or vice versa). The dramatic – and labor-devastating – development of a globalised-networked-informatised capitalism is raising the necessity and possibility of a new kind of labor internationalis...

  5. Dosimetry of internal emitters

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    The Dosimetry of Internal Emitter Program endeavors to refine the correlation between radiation dose and observed biological effects. The program is presently engaged in the development of studies that will demonstrate the applicability of microdosimetry models developed under the Microdosimetry of Internal Sources Program. The program also provides guidance and assistance to Pacific Northwest Laboratory's Biology Department in the dosimetric analysis of internally deposited radionuclides. This report deals with alpha particle dosimetry plutonium 239 inhalation, and in vitro studies of chromosomal observations

  6. Editorial: International Entrepreneurial Orientation

    OpenAIRE

    Krzysztof Wach

    2015-01-01

    In recent decades, both the theory of internationalisation of the firm and/or the theory of international business have developed. Recent developments in international business studies prove that entrepreneurial orientation (EO) emerges as one of the important potential factors contributing to the intensification of the processes of internationalisation of the firm (Etemad, 2015; Gupta & Gupta, 2015). It seems that international entrepreneurship (IE) has been flourishing. The general theory o...

  7. A novel mutation in the P2Y12 receptor and a function-reducing polymorphism in protease-activated receptor 1 in a patient with chronic bleeding.

    Science.gov (United States)

    Patel, Y M; Lordkipanidzé, M; Lowe, G C; Nisar, S P; Garner, K; Stockley, J; Daly, M E; Mitchell, M; Watson, S P; Austin, S K; Mundell, S J

    2014-05-01

    The study of patients with bleeding problems is a powerful approach in determining the function and regulation of important proteins in human platelets. We have identified a patient with a chronic bleeding disorder expressing a homozygous P2RY(12) mutation, predicting an arginine to cysteine (R122C) substitution in the G-protein-coupled P2Y(12) receptor. This mutation is found within the DRY motif, which is a highly conserved region in G-protein-coupled receptors (GPCRs) that is speculated to play a critical role in regulating receptor conformational states. To determine the functional consequences of the R122C substitution for P2Y(12) function. We performed a detailed phenotypic analysis of an index case and affected family members. An analysis of the variant R122C P2Y(12) stably expressed in cells was also performed. ADP-stimulated platelet aggregation was reduced as a result of a significant impairment of P2Y(12) activity in the patient and family members. Cell surface R122C P2Y(12) expression was reduced both in cell lines and in platelets; in cell lines, this was as a consequence of agonist-independent internalization followed by subsequent receptor trafficking to lysosomes. Strikingly, members of this family also showed reduced thrombin-induced platelet activation, owing to an intronic polymorphism in the F2R gene, which encodes protease-activated receptor 1 (PAR-1), that has been shown to be associated with reduced PAR-1 receptor activity. Our study is the first to demonstrate a patient with deficits in two stimulatory GPCR pathways that regulate platelet activity, further indicating that bleeding disorders constitute a complex trait. © 2014 International Society on Thrombosis and Haemostasis.

  8. International Research Chairs Initiative | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    The International Research Chairs Initiative (IRCI) is a seven-year, CA$8 million research program that pairs top research talent from universities in Canada with their counterparts in developing countries to address key ... The results of this joint effort: world-class discoveries and healthier, wealthier, fairer societies.

  9. International Aid Transparency Initiative (IATI) | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    By offering a common format and central repository, the IATI improves the transparency, accountability, and effectiveness of international aid. It is used ... organizations. IDRC is one of almost 400 participants who publish project titles and descriptions, country and geographic area, aid type, dates, and budget information.

  10. Internal disruption in tokamaks

    International Nuclear Information System (INIS)

    Kuvshinov, B.N.; Savrukhin, P.V.

    1990-01-01

    A review of results of experimental and theoretical investigations of internal disruption in tokamaks is given. Specific features of various types of saw-tooth oscillations are described and their classification is performed. Theoretical models of the process of development of internal disruption instability are discussed. Effect of internal disruption on parameters of plasma, confined in tokamak, is considered. Scalings of period and amplitude of saw-tooth oscillations, as well as version radius are presented. Different methods for stabilizing instability of internal disruption are described

  11. EM International. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1993-07-01

    It is the intent of EM International to describe the Office of Environmental Restoration and Waste Management`s (EM`s) various roles and responsibilities within the international community. Cooperative agreements and programs, descriptions of projects and technologies, and synopses of visits to international sites are all highlighted in this semiannual journal. Focus on EM programs in this issue is on international collaboration in vitrification projects. Technology highlights covers: in situ sealing for contaminated sites; and remote sensors for toxic pollutants. Section on profiles of countries includes: Arctic contamination by the former Soviet Union, and EM activities with Germany--cooperative arrangements.

  12. Internal disruptions in tokamaks

    International Nuclear Information System (INIS)

    Kuvshinov, B.N.; Savrukhin, P.V.

    1990-01-01

    Experimental and theoretical studies of the phenomenon of internal disruptions in tokamaks are reviewed. A classification scheme is introduced and the features of different types of sawtooth oscillations are described. A theoretical model for the development of the internal disruption instability is discussed. The effect of internal disruptions on the parameters of plasma confined in tokamaks is discussed. Scaling laws for the period and amplitude of sawtooth oscillations, as well as for the inversion radius, are presented. Different methods of stabilizing the internal disruption instability are described

  13. BWR internals life assurance

    International Nuclear Information System (INIS)

    Herrera, M.L.; Stancavage, P.P.

    1988-01-01

    Boiling water reactor (BWR) internal components play an important role in power plant life extension. Many important internals were not designed for easy removal and changes in material properties and local environmental effects due to high radiation makes stress corrosion cracking more likely and more difficult to correct. Over the past several years, operating experience has shown that inspection, monitoring and refurbishment can be accomplished for internal structures with existing technology. In addition, mitigation techniques which address the causes of degradation are available to assure that life extension targets can be met. This paper describes the many considerations and aspects when evaluating life extension for reactor vessel internals

  14. Endocytosis of GPI-linked membrane folate receptor-alpha.

    Science.gov (United States)

    Rijnboutt, S; Jansen, G; Posthuma, G; Hynes, J B; Schornagel, J H; Strous, G J

    1996-01-01

    GPI-linked membrane folate receptors (MFRs) have been implicated in the receptor-mediated uptake of reduced folate cofactors and folate-based chemotherapeutic drugs. We have studied the biosynthetic transport to and internalization of MFR isoform alpha in KB-cells. MFR-alpha was synthesized as a 32-kD protein and converted in a maturely glycosylated 36-38-kD protein 1 h after synthesis. 32-kD MFR-alpha was completely soluble in Triton X-100 at 0 degree C. In contrast, only 33% of the 36-38-kD species could be solubilized at these conditions whereas complete solubilization was obtained in Triton X-100 at 37 degrees C or in the presence of saponin at 0 degree C. Similar solubilization characteristics were found when MFR-alpha at the plasma membrane was labeled with a crosslinkable 125I-labeled photoaffinity-analog of folic acid as a ligand. Triton X-100-insoluble membrane domains containing MFR-alpha could be separated from soluble MFR-alpha on sucrose flotation gradients. Only Triton X-100 soluble MFR-alpha was internalized from the plasma membrane. The reduced-folate-carrier, an integral membrane protein capable of translocating (anti-)folates across membranes, was completely excluded from the Triton X-100-resistant membrane domains. Internalized MFR-alpha recycled slowly to the cell surface during which it remained soluble in Triton X-100 at 0 degree C. Using immunoelectron microscopy, we found MFR-alpha along the entire endocytic pathway: in clathrin-coated buds and vesicles, and in small and large endosomal vacuoles. In conclusion, our data indicate that a large fraction, if not all, of internalizing MFR-alpha bypasses caveolae.

  15. Downregulation of 5-HT7 Serotonin Receptors by the Atypical Antipsychotics Clozapine and Olanzapine. Role of Motifs in the C-Terminal Domain and Interaction with GASP-1

    DEFF Research Database (Denmark)

    Manfra, Ornella; Van Craenenbroeck, Kathleen; Skieterska, Kamila

    2015-01-01

    have previously found that the atypical antipsychotics clozapine and olanzapine inhibited G protein activation and, surprisingly, induced both internalization and lysosomal degradation of 5-HT7 receptors. Here, we aimed to determine the mechanism of clozapine- and olanzapine-mediated degradation of 5......-HT7 receptors. In the C-terminus of the 5-HT7 receptor, we identified two YXXΦ motifs, LR residues, and a palmitoylated cysteine anchor as potential sites involved in receptor trafficking to lysosomes followed by receptor degradation. Mutating either of these sites inhibited clozapine- and olanzapine...... of clozapine or olanzapine to the 5-HT7 receptor leads to antagonist-mediated lysosomal degradation by exposing key residues in the C-terminal tail that interact with GASP-1....

  16. Related-to-receptor tyrosine kinase receptor regulates hematopoietic stem and progenitor sensitivity to myelosuppressive injury in mice.

    Science.gov (United States)

    Povinelli, Benjamin J; Srivastava, Pragya; Nemeth, Michael J

    2015-03-01

    Maintaining a careful balance between quiescence and proliferation of hematopoietic stem and progenitor cells (HSPCs) is necessary for lifelong blood formation. Previously, we demonstrated that the Wnt5a ligand inhibits HSPC proliferation through a functional interaction with a noncanonical Wnt ligand receptor termed 'related-to-receptor tyrosine kinase' (Ryk). Expression of Ryk on HSPCs in vivo is associated with a lower rate of proliferation, and, following treatment with fluorouracil (5-FU), the percentage of Ryk(+/high) HSPCs increased and the percentage of Ryk(-/low) HSPCs decreased. Based on these data, we hypothesized that one function of the Ryk receptor is to protect HSPCs from the effects of myeloablative agents. We found that Ryk expression on HSPCs is associated with lower rates of apoptosis following 5-FU and radiation. Transient inhibition of Ryk signaling in vivo resulted in increased hematopoietic-stem-cell proliferation and decreased hematopoietic-stem-cell function in bone marrow transplant assays. Furthermore, inhibition of Ryk signaling sensitized HSPCs to 5-FU treatment in association with increased levels of reactive oxygen species. Together, these results demonstrated an association between Ryk expression and survival of HSPCs following suppressive injury. Copyright © 2015 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

  17. NMDA receptors are important regulators of pancreatic cancer and are potential targets for treatment

    Directory of Open Access Journals (Sweden)

    North WG

    2017-07-01

    Full Text Available William G North,1,2 Fuli Liu,1 Liz Z Lin,1 Ruiyang Tian,2 Bonnie Akerman1 1Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, 2Woomera Therapeutics Inc, Lebanon, NH, USA Abstract: Pancreatic cancer, particularly adenocarcinoma of the pancreas, is a common disease with a poor prognosis. In this study, the importance of N-methyl-D-aspartate (NMDA receptors for the growth and survival of pancreatic cancer was investigated. Immunohistochemistry performed with antibodies against GluN1 and GluN2B revealed that all invasive adenocarcinoma and neuroendocrine pancreatic tumors likely express these two NMDA receptor proteins. These proteins were found to be membrane components of pancreatic cancer cell lines, and both channel-blocker antagonist and GluN2B antagonist significantly reduced cell viability in vitro. Both types of antagonists caused an internalization of the receptors. Dizocilpine maleate (MK-801 and ifenprodil hemitartrate both significantly inhibited the growth of pancreatic tumor xenografts in nu/nu mice. These findings predict that, as for other solid tumors investigated by us, pancreatic cancer could be successfully treated, alone or in combination, with NMDA receptor antagonists or other receptor-inhibiting blocking agents. Keywords: pancreatic cancer, NMDA receptors, inhibitors, potential therapy

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

    Science.gov (United States)

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

    2006-12-01

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

  19. Targeting mammalian organelles with internalizing phage (iPhage) libraries

    Science.gov (United States)

    Rangel, Roberto; Dobroff, Andrey S.; Guzman-Rojas, Liliana; Salmeron, Carolina C.; Gelovani, Juri G.; Sidman, Richard L.; Pasqualini, Renata; Arap, Wadih

    2015-01-01

    Techniques largely used for protein interaction studies and discovery of intracellular receptors, such as affinity capture complex purification and yeast two-hybrid, may produce inaccurate datasets due to protein insolubility, transient or weak protein interactions, or irrelevant intracellular context. A versatile tool to overcome these limitations as well as to potentially create vaccines and engineer peptides and antibodies as targeted diagnostic and therapeutic agents, is the phage display technique. We have recently developed a new technology for screening internalizing phage (iPhage) vectors and libraries utilizing a ligand/receptor-independent mechanism to penetrate eukaryotic cells. iPhage particles provide a unique discovery platform for combinatorial intracellular targeting of organelle ligands along with their corresponding receptors and to fingerprint functional protein domains in living cells. Here we explain the design, cloning, construction, and production of iPhage-based vectors and libraries, along with basic ligand-receptor identification and validation methodologies for organelle receptors. An iPhage library screening can be performed in ~8 weeks. PMID:24030441

  20. Nectin-like interactions between poliovirus and its receptor trigger conformational changes associated with cell entry.

    Science.gov (United States)

    Strauss, Mike; Filman, David J; Belnap, David M; Cheng, Naiqian; Noel, Roane T; Hogle, James M

    2015-04-01

    Poliovirus infection is initiated by attachment to a receptor on the cell surface called Pvr or CD155. At physiological temperatures, the receptor catalyzes an irreversible expansion of the virus to form an expanded form of the capsid called the 135S particle. This expansion results in the externalization of the myristoylated capsid protein VP4 and the N-terminal extension of the capsid protein VP1, both of which become inserted into the cell membrane. Structures of the expanded forms of poliovirus and of several related viruses have recently been reported. However, until now, it has been unclear how receptor binding triggers viral expansion at physiological temperature. Here, we report poliovirus in complex with an enzymatically partially deglycosylated form of the 3-domain ectodomain of Pvr at a 4-Å resolution, as determined by cryo-electron microscopy. The interaction of the receptor with the virus in this structure is reminiscent of the interactions of Pvr with its natural ligands. At a low temperature, the receptor induces very few changes in the structure of the virus, with the largest changes occurring within the footprint of the receptor, and in a loop of the internal protein VP4. Changes in the vicinity of the receptor include the displacement of a natural lipid ligand (called "pocket factor"), demonstrating that the loss of this ligand, alone, is not sufficient to induce particle expansion. Finally, analogies with naturally occurring ligand binding in the nectin family suggest which specific structural rearrangements in the virus-receptor complex could help to trigger the irreversible expansion of the capsid. The cell-surface receptor (Pvr) catalyzes a large structural change in the virus that exposes membrane-binding protein chains. We fitted known atomic models of the virus and Pvr into three-dimensional experimental maps of the receptor-virus complex. The molecular interactions we see between poliovirus and its receptor are reminiscent of the nectin

  1. Differential effects of EGFR ligands on endocytic sorting of the receptor

    DEFF Research Database (Denmark)

    Roepstorff, Kirstine; Grandal, Michael Vibo; Henriksen, Lasse

    2009-01-01

    signalling and is a more potent mitogen than EGF. In addition to EGF and TGF-alpha, five EGFR ligands have been identified. Although many of these ligands are upregulated in cancers, very little is known about their effect on EGFR trafficking. We have compared the effect of six different ligands on endocytic...... trafficking of EGFR. We find that, whereas they all stimulate receptor internalization, they have very diverse effects on endocytic sorting. Heparin-binding EGF-like growth factor and Betacellulin target all EGFRs for lysosomal degradation. In contrast, TGF-alpha and epiregulin lead to complete receptor...

  2. Receptor Tyrosine Kinases in Drosophila Development

    Science.gov (United States)

    Sopko, Richelle; Perrimon, Norbert

    2013-01-01

    Tyrosine phosphorylation plays a significant role in a wide range of cellular processes. The Drosophila genome encodes more than 20 receptor tyrosine kinases and extensive studies in the past 20 years have illustrated their diverse roles and complex signaling mechanisms. Although some receptor tyrosine kinases have highly specific functions, others strikingly are used in rather ubiquitous manners. Receptor tyrosine kinases regulate a broad expanse of processes, ranging from cell survival and proliferation to differentiation and patterning. Remarkably, different receptor tyrosine kinases share many of the same effectors and their hierarchical organization is retained in disparate biological contexts. In this comprehensive review, we summarize what is known regarding each receptor tyrosine kinase during Drosophila development. Astonishingly, very little is known for approximately half of all Drosophila receptor tyrosine kinases. PMID:23732470

  3. Receptor binding studies of the living heart

    International Nuclear Information System (INIS)

    Syrota, A.

    1988-01-01

    Receptors form a class of intrinsic membrane proteins (or glycoproteins) defined by the high affinity and specificity with which they bind ligands. Many receptors are associated directly or indirectly with membrane ion channels that open or close after a conformational change of the receptor induced by the binding of the neurotransmitter. Changes in number and/or affinity of cardiac neurotransmitter receptors have been associated with myocardial ischemia and infarction, congestive heart failure, and cardiomyopathy as well as diabetes or thyroid-induced heart muscle disease. These alterations of cardiac receptors have been demonstrated in vitro on membrane homogenates from samples collected mainly during surgery or postmortem. The disadvantage of these in vitro binding techniques is that receptors lose their natural environment and their relationships with the other components of the tissue

  4. Subtype selective kainic acid receptor agonists

    DEFF Research Database (Denmark)

    Bunch, Lennart; Krogsgaard-Larsen, Povl

    2009-01-01

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

  5. Characteristic molecular vibrations of adenosine receptor ligands.

    Science.gov (United States)

    Chee, Hyun Keun; Yang, Jin-San; Joung, Je-Gun; Zhang, Byoung-Tak; Oh, S June

    2015-02-13

    Although the regulation of membrane receptor activation is known to be crucial for molecular signal transduction, the molecular mechanism underlying receptor activation is not fully elucidated. Here we study the physicochemical nature of membrane receptor behavior by investigating the characteristic molecular vibrations of receptor ligands using computational chemistry and informatics methods. By using information gain, t-tests, and support vector machines, we have identified highly informative features of adenosine receptor (AdoR) ligand and corresponding functional amino acid residues such as Asn (6.55) of AdoR that has informative significance and is indispensable for ligand recognition of AdoRs. These findings may provide new perspectives and insights into the fundamental mechanism of class A G protein-coupled receptor activation. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  6. Acetylcholine receptors in the human retina

    International Nuclear Information System (INIS)

    Hutchins, J.B.; Hollyfield, J.G.

    1985-01-01

    Evidence for a population of acetylcholine (ACh) receptors in the human retina is presented. The authors have used the irreversible ligand 3 H-propylbenzilylcholine mustard ( 3 H-PrBCM) to label muscarinic receptors. 3 H- or 125 I-alpha-bungarotoxin (alpha-BTx) was used to label putative nicotinic receptors. Muscarinic receptors are apparently present in the inner plexiform layer of the retina. Autoradiographic grain densities are reduced in the presence of saturating concentrations of atropine, quinuclidinyl benzilate or scopolamine; this indicates that 3 H-PrBCM binding is specific for a population of muscarinic receptors in the human retina. Binding sites for radiolabeled alpha-BTx are found predominantly in the inner plexiform layer of the retina. Grain densities are reduced in the presence of d-tubocurarine, indicating that alpha-BTx may bind to a pharmacologically relevant nicotinic ACh receptor. This study provides evidence for cholinergic neurotransmission in the human retina

  7. Publishing International Counseling Articles

    Science.gov (United States)

    Hohenshil, Thomas H.; Amundson, Norman E.

    2011-01-01

    This article begins with a rationale for including international articles in the "Journal of Counseling & Development." Then, 2 general categories of international articles are described. First are articles that provide a general overview of counseling in a particular country. The 2nd category is more general and might involve international…

  8. International Entrepreneurship and Sourcing

    DEFF Research Database (Denmark)

    Servais, Per; Zucchella, Antonella; Palamera, Giada

    2006-01-01

    This contribution focuses on international sourcing as an entrepreneurial act and aims at demonstrating that it is actually at the core of internationalization processes of small firms, both established and international new ventures. Another issue of this research is to understand how these firm...

  9. International Student Success

    Science.gov (United States)

    Smith, Clayton

    2016-01-01

    This article, with a focus on North American postsecondary education, identifies international students as a strategic enrollment management institutional priority; presents themes in the international student retention, satisfaction, and success research literature; and describes related best practices. It also presents the findings from an…

  10. International Trade and Protectionism.

    Science.gov (United States)

    Stanford Univ., CA. Stanford Program on International and Cross Cultural Education.

    This unit is designed to investigate the reasons for international trade and the issue of trade protectionism by focusing on the case study of the U.S. trade relationship with Taiwan. The unit begins with a simulation that highlights the concepts of global interdependence, the need for international trade, and the distribution of the world's…

  11. Wording in international law

    NARCIS (Netherlands)

    d' Aspremont, J.

    2012-01-01

    Since the demise of philosophical foundationalism and that of the Aristotelian idea of an inner meaning of words, scholarship about international law is no longer perceived as a mining activity geared towards the extraction of pre-existing meaning. Rather, international legal scholarship is in a

  12. Wording in International Law

    NARCIS (Netherlands)

    d' Aspremont, J.

    2012-01-01

    Since the demise of philosophical foundationalism and that of the Aristotelian idea of an inner meaning of words, the scholarship about international law is no longer perceived as a mining activity geared towards the extraction of pre-existing meaning. Rather, international legal scholarship is in a

  13. OCRWM international procedures

    International Nuclear Information System (INIS)

    1986-03-01

    These international procedures provide guidance and assistance for the Office of Civilian Radioactive Waste Management (OCRWM) and for OCRWM Project Offices, contractors and subcontractors in conducting international activities. They supplement the relevant Department of Energy (DOE) orders (which are referenced), not supplant them

  14. International Cancer Screening Network

    Science.gov (United States)

    The International Cancer Screening Network promotes evidence-based cancer screening implementation and evaluation with cooperation from multilateral organizations around the globe. Learn more about how ICSN aims to reduce the global burden of cancer by supporting research and international collaboration.

  15. International Youth Nuclear Congress

    International Nuclear Information System (INIS)

    Fern, A.

    2017-01-01

    International Youth Nuclear Congress (IYNC) was Initiated by an international YG group of enthusiasts in 1997. Mission statement developed at ENC1998 in Nice, France Growth in enthusiasm and support: IAEA, Nuclear Societies, companies. IYNC run by the Young Generation with full support of experienced advisors, nuclear societies and companies. First came to African continent when IYNC 2010 was hosted by South Africa

  16. Internal Evaluation, Historically Speaking

    Science.gov (United States)

    Mathison, Sandra

    2011-01-01

    The author analyzes the growth and nature of internal evaluation from the 1960s to the present and suggests that internal evaluation has been on the increase because of its perceived importance. Although the 1960s were characterized by a rich intellectual development of evaluation theory and practice, the fiscal conservatism of the 1980s ushered…

  17. Modeling Internal Radiation Therapy

    NARCIS (Netherlands)

    van den Broek, Egon; Schouten, Theo E.; Pellegrini, M.; Fred, A.; Filipe, J.; Gamboa, H.

    2011-01-01

    A new technique is described to model (internal) radiation therapy. It is founded on morphological processing, in particular distance transforms. Its formal basis is presented as well as its implementation via the Fast Exact Euclidean Distance (FEED) transform. Its use for all variations of internal

  18. Studies on insulin receptor, 1

    International Nuclear Information System (INIS)

    Sakai, Yukio

    1979-01-01

    The present study was designed for the purpose of establishing a method of insulin radioreceptor assay using plasma membranes of guinea pigs as receptor sites. The results obtained are as follows: 1) Insulin receptor in the renal plasma membranes of guinea pigs showed a significantly high affinity to porcine insulin compared with that in the plasma membranes of guinea pig liver or rat kidney and liver. 2) In the insulin radioreceptor assay, an optimum condition was observed by the incubation at 4 0 C for 24 - 48 hours with 100 μg membrane protein of guinea pig kidney and 0.08 ng of 125 I-insulin. This assay method was specific for insulin and showed an accurate biological activity of insulin. 3) The recovery rate of insulin radioreceptor assay was 98.4% and dilution check up to 16 times did not influence on the result. An average of coefficient variation was 3.92% within assay. All of these results indicated the method to be satisfactory. 4) Glucose induced insulin release by perfusion method in isolated Langerhans islets of rats showed an identical pattern of reaction curves between radioreceptor assay and radioimmunoassay, although the values of radioreceptor assay was slightly low. 5) Insulin free serum produced by ultra filtration method was added to the standard assay medium. By this procedure, direct measurement of human serum by radioreceptor assay became possible. 6) The value of human serum insulin receptor binding activity by the radioreceptor assay showed a high correlation with that of insulin radioimmunoassay in sera of normal, borderline or diabetic type defined by glucose tolerance test. (author)

  19. Genomic testing in international guidelines

    Directory of Open Access Journals (Sweden)

    Peter Kern

    2013-10-01

    Full Text Available Human breast cancer was solely classified based on clinical and immunohistochemical (IHC findings in the past. A growing body of evidence suggests that these categorisations are rendered more precisely by intrinsic subtyping with the aim of an introduction of personalised medicine. Especially in breast cancer with the uncertain potential of disease spread, such as T1-2, Grade 2 and oestrogen receptor-positive (ER+ve tumours, the value of chemotherapy applied to every patient has been questioned and the need for additional information on the tumour´s specific risk of recurrence is overt. It is estimated that the average risk for recurrence is 15% at 10 years in hormone-receptor-positive breast cancer. Thus, a relatively small proportion of these patients would need chemotherapy, and the main task is to stratify which patients of this cohort are at high-risk and will benefit from cytotoxic agents. Ki67, as a proliferation marker classifying high-risk tumours, has been demonstrated as a continuous marker, but not as a clear cut risk-defining instrument in recent publications. Thus, the difficulties are perceived especially at the threshold of the low to high-risk area of this marker. Reproducibility of Ki67 is to some extent uncertain considering there is inter and intra-institutional variability of up to 30% of the results. Several multi gene arrays, such as MammaPrint®, Oncotype DX®, Endopredict®, and PAM50 have demonstrated clinical utility and experienced validation. The aim of this review is the description of the implementation of genomic testing in international guidelines (North American and European, with regard to incorporation of multigene arrays into the decision-making process in different clinical settings (including tumor size and IHC status. Data cut-off was 1st October, 2013. It seems that North America and some European countries have initiated a shift towards a personalised medicine with multigene arrays based on RT-PCR or

  20. Seventh Symposium on Subtypes of Musccarinic Receptors.

    Science.gov (United States)

    1997-01-01

    nociceptive pain, are less than ideal. For mild to moderate pain, the first line of therapy includes aspirin, acetaminophen/ paracetamol , and nonsteroidal...due to receptor degradation triggered by prolonged carbachol occupancy. This down-regulation was accompanied by uncoupling of the M2-receptors after 24...be under control by the m3 mAChR, suggesting a complex receptor regulation of phosphoinositide metabolism, including degradation and synthesis. Future

  1. Molecular identification of the first SIFamide receptor

    DEFF Research Database (Denmark)

    Jørgensen, Lars M; Hauser, Frank; Cazzamali, Giuseppe

    2006-01-01

    , an impressive sequence conservation (67-77% amino acid sequence identities between the seven-transmembrane areas; 82-87% sequence similarities). The identification of well-conserved SIFamide receptor orthologues in all other insects with a sequenced genome, suggests that the SIFamide/receptor couple must have...... an essential function in arthropods. This paper is the first report on the identification of a SIFamide receptor....

  2. Progesterone receptor modulators in breast cancer

    OpenAIRE

    WIEHLE, Ronald D.

    2015-01-01

    Breast cancer has been treated successfully with selective estrogen receptor antagonists (SERMs) such as tamoxifen, receptor-depleting agents such as fulvestrant, and aromatase inhibitors such as anastrozole. Selective progesterone receptor modulators (SPRMs or PRMs) have not been studied as much and are currently under investigation for inhibition of mammary carcinogenesis in animal models and breast cancer prevention trials in women. They might follow tamoxifen and aromatase inhibitors in t...

  3. Androgen Receptor Signaling in Bladder Cancer

    OpenAIRE

    Li, Peng; Chen, Jinbo; Miyamoto, Hiroshi

    2017-01-01

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

  4. Muscarinic Receptor Agonists and Antagonists

    Directory of Open Access Journals (Sweden)

    David R. Kelly

    2001-02-01

    Full Text Available A comprehensive review of pharmacological and medical aspects of the muscarinic class of acetylcholine agonists and antagonists is presented. The therapeutic benefits of achieving receptor subtype selectivity are outlined and applications in the treatment of Alzheimer’s disease are discussed. A selection of chemical routes are described, which illustrate contemporary methodology for the synthesis of chiral medicinal compounds (asymmetric synthesis, chiral pool, enzymes. Routes to bicyclic intrannular amines and intramolecular Diels-Alder reactions are highlighted.

  5. Hemoglobin and heme scavenger receptors

    DEFF Research Database (Denmark)

    Nielsen, Marianne Jensby; Møller, Holger Jon; Moestrup, Søren Kragh

    2010-01-01

    Heme, the functional group of hemoglobin, myoglobin, and other hemoproteins, is a highly toxic substance when it appears in the extracellular milieu. To circumvent potential harmful effects of heme from hemoproteins released during physiological or pathological cell damage (such as hemolysis...... and rhabdomyolysis), specific high capacity scavenging systems have evolved in the mammalian organism. Two major systems, which essentially function in a similar way by means of a circulating latent plasma carrier protein that upon ligand binding is recognized by a receptor, are represented by a) the hemoglobin...

  6. Terbutaline causes immobilization of single β2-adrenergic receptor-ligand complexes in the plasma membrane of living A549 cells as revealed by single-molecule microscopy

    Science.gov (United States)

    Sieben, Anne; Kaminski, Tim; Kubitscheck, Ulrich; Häberlein, Hanns

    2011-02-01

    G-protein-coupled receptors are important targets for various drugs. After signal transduction, regulatory processes, such as receptor desensitization and internalization, change the lateral receptor mobility. In order to study the lateral diffusion of β2-adrenergic receptors (β2AR) complexed with fluorescently labeled noradrenaline (Alexa-NA) in plasma membranes of A549 cells, trajectories of single receptor-ligand complexes were monitored using single-particle tracking. We found that a fraction of 18% of all β2ARs are constitutively immobile. About 2/3 of the β2ARs moved with a diffusion constant of D2 = 0.03+/-0.001 μm2/s and about 17% were diffusing five-fold faster (D3 = 0.15+/-0.02 μm2/s). The mobile receptors moved within restricted domains and also showed a discontinuous diffusion behavior. Analysis of the trajectory lengths revealed two different binding durations with τ1 = 77+/-1 ms and τ2 = 388+/-11 ms. Agonistic stimulation of the β2AR-Alexa-NA complexes with 1 μM terbutaline caused immobilization of almost 50% of the receptors within 35 min. Simultaneously, the mean area covered by the mobile receptors decreased significantly. Thus, we demonstrated that agonistic stimulation followed by cell regulatory processes results in a change in β2AR mobility suggesting that different receptor dynamics characterize different receptor states.

  7. International Fisheries Agreements

    DEFF Research Database (Denmark)

    Pintassilgo, Pedro; Kronbak, Lone Grønbæk; Lindroos, Marko

    2015-01-01

    This paper surveys the application of game theory to the economic analysis of international fisheries agreements. The relevance of this study comes not only from the existence of a vast literature on the topic but especially from the specific features of these agreements. The emphasis of the survey...... is on coalition games, an approach that has become prominent in the fisheries economics literature over the last decade. It is shown that coalition games were first applied to international fisheries agreements in the late 1990s addressing cooperative issues under the framework of characteristic function games...... and stability of international fisheries agreements. A key message that emerges from this literature strand is that self-enforcing cooperative management of internationally shared fish stocks is generally difficult to achieve. Hence, the international legal framework and regulations play a decisive role...

  8. Cancer from internal emitters

    International Nuclear Information System (INIS)

    Boecker, B.B.; Griffith, W.C. Jr.

    1995-01-01

    Irradiation from internal emitters, or internally deposited radionuclides, is an important component of radiation exposures encountered in the workplace, home, or general environment. Long-term studies of human populations exposed to various internal emitters by different routes of exposure are producing critical information for the protection of workers and members of the general public. The purpose of this report is to examine recent developments and discuss their potential importance for understanding lifetime cancer risks from internal emitters. The major populations of persons being studied for lifetime health effects from internally deposited radionuclides are well known: Lung cancer in underground miners who inhaled Rn progeny, liver cancer from persons injected with the Th-containing radiographic contrast medium Thorotrast, bone cancer from occupational or medical intakes of 226 Ra or medical injections of 224 Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes

  9. Immunity of international organizations

    CERN Document Server

    Schrijver, Nico

    2015-01-01

    Immunity rules are part and parcel of the law of international organizations. It has long been accepted that international organizations and their staff need to enjoy immunity from the jurisdiction of national courts. However, it is the application of these rules in practice that increasingly causes controversy. Claims against international organizations are brought before national courts by those who allegedly suffer from their activities. These can be both natural and legal persons such as companies. National courts, in particular lower courts, have often been less willing to recognize the immunity of the organization concerned than the organization s founding fathers. Likewise, public opinion and legal writings frequently criticize international organizations for invoking their immunity and for the lack of adequate means of redress for claimants. It is against this background that an international conference was organized at Leiden University in June 2013. A number of highly qualified academics and practit...

  10. Attracting International Hotels

    DEFF Research Database (Denmark)

    Assaf, A. George; Josiassen, Alexander; Agbola, Frank Wogbe

    2015-01-01

    With the increased international competition facing hotel chains, it is essential that the next destination they enter is the most attractive option possible. The host destinations too have a keen interest in strategically positioning themselves in order to attract international hotels since...... their presence has several positive effects. Using, for the first time, actual on-location data we investigate the factors that matter most for international hotels when selecting host destinations. Specifically, we identify 23 factors that make a destination an attractive (or unattractive) location...... for international hotels. We then rank these. The results show that welcomeness, infrastructure, and crime rate are the three most important factors that influence the location of international hotels in host destinations....

  11. FINANCING OF INTERNATIONAL TRANSACTIONS

    Directory of Open Access Journals (Sweden)

    RADU NICOLAE BĂLUNĂ

    2013-02-01

    Full Text Available Financing (funding is essentially the purchase of funds necessary for a business. This can be done from internal sources (company’s own funds or external (borrowed funds. The high value of goods traded in international trade makes revenues generated from internal resources not sufficient to settle the value of the goods. Thus, it is frequent to resort to borrowed funds. In International Business Transactions, external financing is done both by classical techniques of credit (credit supplier and buyer credit and modern techniques of financing (factoring, forfeiting, leasing all trade tailored. In terms of the length of financing, accounting funding is short-term (1-12 months and long-term financing (over a year. In principle, export and import operations prevailing short-term financing techniques, while international investment and industrial cooperation actions are specific long-term funding

  12. Internal pump monitoring device

    International Nuclear Information System (INIS)

    Kurosaki, Toshikazu.

    1996-01-01

    In the present invention, a thermometer is disposed at the upper end of an internal pump casing of a coolant recycling system in a BWR type reactor to detect leakage of reactor water thereby ensuring the improvement of reliability of the internal pump. Namely, a thermometer is disposed, which can detect temperature elevation occurred when water in the internal pump leaked from a reactor pressure vessel passes through the gap between a stretch tube and an upper end of the pump casing. Signals from the thermometer are transmitted to a signal processing device by an instrumentation cable. The signal processing device generates an alarm when the temperature signal exceeds a predetermined value and announces that leakage of reactor water occurs in the internal pump. Since the present invention can detect the leakage of the reactor water in the pump casing in an early stage, it can contribute to the improvement of the safety and reliability of the internal pump. (I.S.)

  13. Internal Social Media

    DEFF Research Database (Denmark)

    Madsen, Vibeke Thøis

    2018-01-01

    Internal social media is a web-based communication arena that provides all organizational members with a communication opportunity. The media has emerged in organizations since 2004, and is increasingly seen as a way of giving employees a voice in organizations which can benefit the organization...... in terms of knowledge sharing, collaboration, and employee participation and engagement. The first wave of studies of internal social media was primarily from an information-systems perspective and focused more on its adoption, its affordances, and the outcome of its introduction. The second wave...... of studies was more concerned with studying the dynamics of communication on internal social media, in order to understand coworkers as strategic communicators and how communication on internal social media can constitute the organization. With a successful introduction of internal social media, coworkers...

  14. PDGF-beta receptor expression and ventilatory acclimatization to hypoxia in the rat.

    Science.gov (United States)

    Alea, O A; Czapla, M A; Lasky, J A; Simakajornboon, N; Gozal, E; Gozal, D

    2000-11-01

    Activation of platelet-derived growth factor-beta (PDGF-beta) receptors in the nucleus of the solitary tract (nTS) modulates the late phase of the acute hypoxic ventilatory response (HVR) in the rat. We hypothesized that temporal changes in PDGF-beta receptor expression could underlie the ventilatory acclimatization to hypoxia (VAH). Normoxic ventilation was examined in adult Sprague-Dawley rats chronically exposed to 10% O(2), and at 0, 1, 2, 7, and 14 days, Northern and Western blots of the dorsocaudal brain stem were performed for assessment of PDGF-beta receptor expression. Although no significant changes in PDGF-beta receptor mRNA occurred over time, marked attenuation of PDGF-beta receptor protein became apparent after day 7 of hypoxic exposure. Such changes were significantly correlated with concomitant increases in normoxic ventilation, i.e., with VAH (r: -0.56, P < 0.005). In addition, long-term administration of PDGF-BB in the nTS via osmotic pumps loaded with either PDGF-BB (n = 8) or vehicle (Veh; n = 8) showed that although no significant changes in the magnitude of acute HVR occurred in Veh over time, the typical attenuation of HVR by PDGF-BB decreased over time. Furthermore, PDGF-BB microinjections did not attenuate HVR in acclimatized rats at 7 and 14 days of hypoxia (n = 10). We conclude that decreased expression of PDGF-beta receptors in the dorsocaudal brain stem correlates with the magnitude of VAH. We speculate that the decreased expression of PDGF-beta receptors is mediated via internalization and degradation of the receptor rather than by transcriptional regulation.

  15. The inflammatory role of platelets via their TLRs and Siglec receptors

    Directory of Open Access Journals (Sweden)

    Fabrice eCOGNASSE

    2015-03-01

    Full Text Available Platelets are non-nucleated cells that play central roles in the processes of haemostasis, innate immunity and inflammation; however, several reports show that these distinct functions are more closely linked than initially thought. Platelets express numerous receptors and contain hundreds of secretory products. These receptors and secretory products are instrumental to the platelet functional responses. The capacity of platelets to secrete copious amounts of cytokines, chemokines and related molecules appears intimately related to the role of the platelet in inflammation. Platelets exhibit non-self-infectious danger detection molecules on their surfaces, including those belonging to the ‘‘Toll-Like Receptor family’’, as well as pathogen sensors of other natures (Ig- or complement receptors etc.. These receptors permit platelets to both bind infectious agents and deliver differential signals leading to the secretion of cytokines/chemokines, under the control of specific intracellular regulatory pathways. In contrast, dysfunctional receptors or dysregulation of the intracellular pathway may increase the susceptibility to pathological inflammation. Physiological vs pathological inflammation is tightly controlled by the sensors of danger expressed in resting, as well as in activated, platelets. These sensors, referred to as Pathogen Recognition Receptors (PRRs, primarily sense danger signals termed Pathogen Associated Molecular Patterns (PAMPs. As platelets are found in inflamed tissues and are involved in auto-immune disorders, it is possible that they can also be stimulated by internal pathogens. In such cases, platelets can also sense danger signals using Damage Associated Molecular Patterns (DAMPs. Some of the most significant DAMP family members are the alarmins, to which the Siglec family of molecules belongs. This review examines the role of platelets in anti-infection immunity via their TLRs and Siglec receptors.

  16. CERAPP: Collaborative Estrogen Receptor Activity Prediction Project

    Data.gov (United States)

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

  17. Identification and mechanism of ABA receptor antagonism

    KAUST Repository

    Melcher, Karsten; Xu, Yong; Ng, Ley-Moy; Zhou, X. Edward; Soon, Fen-Fen; Chinnusamy, Viswanathan; Suino-Powell, Kelly M.; Kovach, Amanda; Tham, Fook S.; Cutler, Sean R.; Li, Jun; Yong, Eu-Leong; Zhu, Jian-Kang; Xu, H. Eric

    2010-01-01

    The phytohormone abscisic acid (ABA) functions through a family of fourteen PYR/PYL receptors, which were identified by resistance to pyrabactin, a synthetic inhibitor of seed germination. ABA activates these receptors to inhibit type 2C protein phosphatases, such as ABI1, yet it remains unclear whether these receptors can be antagonized. Here we demonstrate that pyrabactin is an agonist of PYR1 and PYL1 but is unexpectedly an antagonist of PYL2. Crystal structures of the PYL2-pyrabactin and PYL1-pyrabactin-ABI1 complexes reveal the mechanism responsible for receptor-selective activation and inhibition, which enables us to design mutations that convert PYL1 to a pyrabactin-inhibited receptor and PYL2 to a pyrabactin-activated receptor and to identify new pyrabactin-based ABA receptor agonists. Together, our results establish a new concept of ABA receptor antagonism, illustrate its underlying mechanisms and provide a rational framework for discovering novel ABA receptor ligands. © 2010 Nature America, Inc. All rights reserved.

  18. Dehydroepiandrosterone: an ancestral ligand of neurotrophin receptors.

    Science.gov (United States)

    Pediaditakis, Iosif; Iliopoulos, Ioannis; Theologidis, Ioannis; Delivanoglou, Nickoleta; Margioris, Andrew N; Charalampopoulos, Ioannis; Gravanis, Achille

    2015-01-01

    Dehydroepiandosterone (DHEA), the most abundant steroid in humans, affects multiple cellular functions of the endocrine, immune, and nervous systems. However, up to quite recently, no receptor has been described specifically for it, whereas most of its physiological actions have been attributed to its conversion to either androgens or estrogens. DHEA interacts and modulate a variety of membrane and intracellular neurotransmitter and steroid receptors. We have recently reported that DHEA protects neuronal cells against apoptosis, interacting with TrkA, the high-affinity prosurvival receptor of the neurotrophin, nerve growth factor. Intrigued by its pleiotropic effects in the nervous system of a variety of species, we have investigated the ability of DHEA to interact with the other two mammalian neurotrophin receptors, ie, the TrkB and TrkC, as well as their invertebrate counterparts (orthologs) in mollusks Lymnaea and Aplysia and in cephalochordate fish Amphioxus. Amazingly, DHEA binds to all Trk receptors, although with lower affinity by 2 orders of magnitude compared with that of the polypeptidic neurotrophins. DHEA effectively induced the first step of the TrkA and TrkC receptors activation (phosphorylation at tyrosine residues), including the vertebrate neurotrophin nonresponding invertebrate Lymnaea and Aplysia receptors. Based on our data, we hypothesize that early in evolution, DHEA may have acted as a nonspecific neurotrophic factor promoting neuronal survival. The interaction of DHEA with all types of neurotrophin receptors offers new insights into the largely unidentified mechanisms of its actions on multiple tissues and organs known to express neurotrophin receptors.

  19. Characterization of the chicken muscle insulin receptor

    International Nuclear Information System (INIS)

    Adamo, M.; Simon, J.; Rosebrough, R.W.; McMurtry, J.P.; Steele, N.C.; LeRoith, D.

    1987-01-01

    Insulin receptors are present in chicken skeletal muscle. Crude membrane preparations demonstrated specific 125 I-insulin binding. The nonspecific binding was high (36-55% of total binding) and slightly lower affinity receptors were found than are typically observed for crude membrane insulin binding in other chicken tissues. Affinity crosslinking of 125 I-insulin to crude membranes revealed insulin receptor alpha-subunits of Mr 128K, intermediate between those of liver (134K) and brain (124K). When solubilized and partially purified on wheat germ agglutinin (WGA) affinity columns, chicken muscle insulin receptors exhibited typical high affinity binding, with approximately 10(-10) M unlabeled insulin producing 50% inhibition of the specific 125 I-insulin binding. WGA purified chicken muscle insulin receptors also exhibited insulin-stimulated autophosphorylation of the beta-subunit, which appeared as phosphorylated bands of 92- and 81K. Both bands were immunoprecipitated by anti-receptor antiserum (B10). WGA purified membranes also demonstrated dose-dependent insulin-stimulated phosphorylation of the exogenous substrate poly(Glu,Tyr)4:1. However, unlike chicken liver, chicken muscle insulin receptor number and tyrosine kinase activity were unaltered by 48 hr of fasting or 48 hr of fasting and 24 hr of refeeding. Thus, despite the presence of insulin receptors in chicken muscle showing normal coupling to receptor tyrosine kinase activity, nutritional alterations modulate these parameters in a tissue-specific manner in chickens

  20. Human dopamine receptor and its uses

    Energy Technology Data Exchange (ETDEWEB)

    Civelli, Olivier (Portland, OR); Van Tol, Hubert Henri-Marie (Toronto, CA)

    1999-01-01

    The present invention is directed toward the isolation, characterization and pharmacological use of the human D4 dopamine receptor. The nucleotide sequence of the gene corresponding to this receptor and alleleic variant thereof are provided by the invention. The invention also includes recombinant eukaryotic expression constructs capable of expressing the human D4 dopamine receptor in cultures of transformed eukaryotic cells. The invention provides cultures of transformed eukaryotic cells which synthesize the human D4 dopamine receptor, and methods for characterizing novel psychotropic compounds using such cultures.