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Sample records for human scavenger receptor

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

    SciTech Connect

    Matsumoto, Akiyo; Itakura, Hiroshige; Kodama, Tatsuhiko National Inst. of Health and Nutrition, Tokyo ); Naito, Makoto; Takahashi, Kiyoshi ); Ikemoto, Shinji; Asaoka, Hitoshi; Hayakawa, Ikuho ); Kanamori, Hiroshi; Takaku, Fumimaro ); Aburatani, Hiroyuki Massachusetts Inst. of Tech., Cambridge, MA ); Suzuki, Hiroshi; Kobari, Yukage; Miyai, Tatsuya ); Cohen, E.H.; Wydro, R. ); Housman, D.E. )

    1990-12-01

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

  2. Standardizing scavenger receptor nomenclature.

    PubMed

    Prabhudas, Mercy; Bowdish, Dawn; Drickamer, Kurt; Febbraio, Maria; Herz, Joachim; Kobzik, Lester; Krieger, Monty; Loike, John; Means, Terry K; Moestrup, Soren K; Post, Steven; Sawamura, Tatsuya; Silverstein, Samuel; Wang, Xiang-Yang; El Khoury, Joseph

    2014-03-01

    Scavenger receptors constitute a large family of proteins that are structurally diverse and participate in a wide range of biological functions. These receptors are expressed predominantly by myeloid cells and recognize a variety of ligands, including endogenous and modified host-derived molecules and microbial pathogens. There are currently eight classes of scavenger receptors, many of which have multiple names, leading to inconsistencies and confusion in the literature. To address this problem, a workshop was organized by the U.S. National Institute of Allergy and Infectious Diseases, National Institutes of Health to help develop a clear definition of scavenger receptors and a standardized nomenclature based on that definition. Fifteen experts in the scavenger receptor field attended the workshop and, after extensive discussion, reached a consensus regarding the definition of scavenger receptors and a proposed scavenger receptor nomenclature. Scavenger receptors were defined as cell surface receptors that typically bind multiple ligands and promote the removal of non-self or altered-self targets. They often function by mechanisms that include endocytosis, phagocytosis, adhesion, and signaling that ultimately lead to the elimination of degraded or harmful substances. Based on this definition, nomenclature and classification of these receptors into 10 classes were proposed. The discussion and nomenclature recommendations described in this report only refer to mammalian scavenger receptors. The purpose of this article is to describe the proposed mammalian nomenclature and classification developed at the workshop and to solicit additional feedback from the broader research community.

  3. Expression of alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein and scavenger receptor in human atherosclerotic lesions.

    PubMed Central

    Luoma, J; Hiltunen, T; Särkioja, T; Moestrup, S K; Gliemann, J; Kodama, T; Nikkari, T; Ylä-Herttuala, S

    1994-01-01

    Macrophage- and smooth muscle cell (SMC)-derived foam cells are typical constituents of human atherosclerotic lesions. At least three receptor systems have been characterized that could be involved in the development of foam cells: alpha 2-macroglobulin receptor/LDL receptor-related protein (alpha 2 MR/LRP), scavenger receptor, and LDL receptor. We studied the expression of these receptors in human atherosclerotic lesions with in situ hybridization and immunocytochemistry. An abundant expression of alpha 2MR/LRP mRNA and protein was found in SMC and macrophages in both early and advanced lesions in human aortas. alpha 2MR/LRP was also present in SMC in normal aortas. Scavenger receptor mRNA and protein were expressed in lesion macrophages but no expression was found in lesion SMC. LDL receptor was absent from the lesion area but was expressed in some aortas in medial SMC located near the adventitial border. The results demonstrate that (a) alpha 2MR/LRP is, so far, the only lipoprotein receptor expressed in lesions SMC in vivo; (b) scavenger receptors are expressed only in lesion macrophages; and (c) both receptors may play important roles in the development of human atherosclerotic lesions. Images PMID:8182133

  4. Human Scavenger Receptor A1-Mediated Inflammatory Response to Silica Particle Exposure Is Size Specific.

    PubMed

    Nishijima, Nobuo; Hirai, Toshiro; Misato, Kazuki; Aoyama, Michihiko; Kuroda, Etsushi; Ishii, Ken J; Higashisaka, Kazuma; Yoshioka, Yasuo; Tsutsumi, Yasuo

    2017-01-01

    The application of nanotechnology in the health care setting has many potential benefits; however, our understanding of the interactions between nanoparticles and our immune system remains incomplete. Although many of the biological effects of nanoparticles are negatively correlated with particle size, some are clearly size specific and the mechanisms underlying these size-specific biological effects remain unknown. Here, we examined the pro-inflammatory effects of silica particles in THP-1 cells with respect to particle size; a large overall size range with narrow intervals between particle diameters (particle diameter: 10, 30, 50, 70, 100, 300, and 1,000 nm) was used. Secretion of the pro-inflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α induced by exposure to the silica particles had a bell-shaped distribution, where the maximal secretion was induced by silica nanoparticles with a diameter of 50 nm and particles with smaller or larger diameters had progressively less effect. We found that blockade of IL-1β secretion markedly inhibited TNF-α secretion, suggesting that IL-1β is upstream of TNF-α in the inflammatory cascade induced by exposure to silica particles, and that the induction of IL-1β secretion was dependent on both the NLRP3 inflammasome and on uptake of the silica particles into the cells via endocytosis. However, a quantitative analysis of silica particle uptake showed that IL-1β secretion was not correlated with the amount of silica particles taken up by the cells. Further investigation revealed that the induction of IL-1β secretion and uptake of silica nanoparticles with diameters of 50 or 100 nm, but not of 10 or 1,000 nm, was dependent on scavenger receptor (SR) A1. In addition, of the silica particles examined, only those with a diameter of 50 nm induced strong IL-1β secretion via activation of Mer receptor tyrosine kinase, a signal mediator of SR A1. Together, our results suggest that the SR A1

  5. Dielectric polymer: scavenging energy from human motion

    NASA Astrophysics Data System (ADS)

    Jean-Mistral, Claire; Basrour, Skandar; Chaillout, Jean-Jacques

    2008-03-01

    More and more sensors are embedded in human body for medical applications, for sport. The short lifetime of the batteries, available on the market, reveals a real problem of autonomy of these systems. A promising alternative is to scavenge the ambient energy such as the mechanical one. Up to now, few scavenging structures have operating frequencies compatible with ambient one. And, most of the developed structures are rigid and use vibration as mechanical source. For these reasons, we developed a scavenger that operates in a large frequency spectrum from quasi-static to dynamic range. This generator is fully flexible, light and does not hamper the human motion. Thus, we report in this paper an analytical model for dielectric generator with news electrical and mechanical characterization, and the development of an innovating application: scavenging energy from human motion. The generator is located on the knee and design to scavenge 0.1mJ per scavenging cycle at a frequency of 1Hz, enough to supply a low consumption system and with a poling voltage as low as possible to facilitate the power management. Our first prototype is a membrane with an area of 5*3cm and 31µm in thickness which scavenge 0.1mJ under 170V at constant charge Q.

  6. Scavenger Receptors: Emerging Roles in Cancer Biology and Immunology.

    PubMed

    Yu, Xiaofei; Guo, Chunqing; Fisher, Paul B; Subjeck, John R; Wang, Xiang-Yang

    2015-01-01

    Scavenger receptors constitute a large family of evolutionally conserved protein molecules that are structurally and functionally diverse. Although scavenger receptors were originally identified based on their capacity to scavenge modified lipoproteins, these molecules have been shown to recognize and bind to a broad spectrum of ligands, including modified and unmodified host-derived molecules or microbial components. As a major subset of innate pattern recognition receptors, scavenger receptors are mainly expressed on myeloid cells and function in a wide range of biological processes, such as endocytosis, adhesion, lipid transport, antigen presentation, and pathogen clearance. In addition to playing a crucial role in maintenance of host homeostasis, scavenger receptors have been implicated in the pathogenesis of a number of diseases, e.g., atherosclerosis, neurodegeneration, or metabolic disorders. Emerging evidence has begun to reveal these receptor molecules as important regulators of tumor behavior and host immune responses to cancer. This review summarizes our current understanding on the newly identified, distinct functions of scavenger receptors in cancer biology and immunology. The potential of scavenger receptors as diagnostic biomarkers and novel targets for therapeutic interventions to treat malignancies is also highlighted.

  7. Scavenger Receptors: Emerging Roles in Cancer Biology and Immunology

    PubMed Central

    Yu, Xiaofei; Guo, Chunqing; Fisher, Paul B.; Subjeck, John R.; Wang, Xiang-Yang

    2015-01-01

    Scavenger receptors constitute a large family of evolutionally conserved protein molecules that are structurally and functionally diverse. Although scavenger receptors were originally identified based on their capacity to scavenge modified lipoproteins, these molecules have been shown to recognize and bind to a broad spectrum of ligands, including modified and unmodified host-derived molecules or microbial components. As a major subset of innate pattern recognition receptors, scavenger receptors are mainly expressed on myeloid cells and function in a wide range of biological processes, such as endocytosis, adhesion, lipid transport, antigen presentation, and pathogen clearance. In addition to playing a crucial role in maintenance of host homeostasis, scavenger receptors have been implicated in the pathogenesis of a number of diseases, e.g., atherosclerosis, neurodegeneration, or metabolic disorders. Emerging evidence has begun to reveal these receptor molecules as important regulators of tumor behavior and host immune responses to cancer. This review summarizes our current understanding on the newly identified, distinct functions of scavenger receptors in cancer biology and immunology. The potential of scavenger receptors as diagnostic biomarkers and novel targets for therapeutic interventions to treat malignancies is also highlighted. PMID:26216637

  8. Determinants of host susceptibility to murine respiratory syncytial virus (RSV) disease identify a role for the innate immunity scavenger receptor MARCO gene in human infants.

    PubMed

    High, Monica; Cho, Hye-Youn; Marzec, Jacqui; Wiltshire, Tim; Verhein, Kirsten C; Caballero, Mauricio T; Acosta, Patricio L; Ciencewicki, Jonathan; McCaw, Zackary R; Kobzik, Lester; Miller-DeGraff, Laura; Gladwell, Wes; Peden, David B; Serra, M Elina; Shi, Min; Weinberg, Clarice; Suzuki, Oscar; Wang, Xuting; Bell, Douglas A; Polack, Fernando P; Kleeberger, Steven R

    2016-09-01

    Respiratory syncytial virus (RSV) is the global leading cause of lower respiratory tract infection in infants. Nearly 30% of all infected infants develop severe disease including bronchiolitis, but susceptibility mechanisms remain unclear. We infected a panel of 30 inbred strains of mice with RSV and measured changes in lung disease parameters 1 and 5days post-infection and they were used in genome-wide association (GWA) studies to identify quantitative trait loci (QTL) and susceptibility gene candidates. GWA identified QTLs for RSV disease phenotypes, and the innate immunity scavenger receptor Marco was a candidate susceptibility gene; targeted deletion of Marco worsened murine RSV disease. We characterized a human MARCO promoter SNP that caused loss of gene expression, increased in vitro cellular response to RSV infection, and associated with increased risk of disease severity in two independent populations of children infected with RSV. Translational integration of a genetic animal model and in vitro human studies identified a role for MARCO in human RSV disease severity. Because no RSV vaccines are approved for clinical use, genetic studies have implications for diagnosing individuals who are at risk for severe RSV disease, and disease prevention strategies (e.g. RSV antibodies). Published by Elsevier B.V.

  9. Spatial patterning of vulture scavenged human remains.

    PubMed

    Spradley, M Katherine; Hamilton, Michelle D; Giordano, Alberto

    2012-06-10

    This article presents the results of a pilot study on the effects of vulture modification to human remains. A donated body from the Willed Body Donation Program was placed at the Forensic Anthropology Research Facility (FARF), an outdoor human decomposition laboratory located at Texas State University-San Marcos. The effects of vulture scavenging on the timing and sequence, and the rate of skeletonization, disarticulation, and dispersal were observed via a motion sensing camera and direct observation. Using GIS (Geographic Information Systems) and GPS (Global Positioning System) technologies and spatial analytical methods, the transport of skeletal elements was mapped in order to analyze dispersal and terrain-influenced patterns of active vulture scavenging. Results showed that the initial scavenging took place 37 days after placement at FARF. This delay in scavenging differs from previous research. After the initial appearance of the vultures, the body was reduced from a fully-fleshed individual to a skeleton within only 5h. This underscores the potential for errors in postmortem interval estimations made at vulture scavenged scenes. Additionally, spatial analysis showed that skeletal elements were dispersed by vultures to lower elevations, and that the disarticulation and dispersal of the skeletal elements occurs early in the scavenging sequence.

  10. Rare variant in scavenger receptor BI raises HDL cholesterol and increases risk of coronary heart disease

    USDA-ARS?s Scientific Manuscript database

    Scavenger receptor BI (SR-BI) is the major receptor for high-density lipoprotein (HDL) cholesterol (HDL-C). In humans, high amounts of HDL-C in plasma are associated with a lower risk of coronary heart disease (CHD). Mice that have depleted Scarb1 (SR-BI knockout mice) have markedly elevated HDL-C l...

  11. Intestinal scavenger receptors are involved in vitamin K1 absorption.

    PubMed

    Goncalves, Aurélie; Margier, Marielle; Roi, Stéphanie; Collet, Xavier; Niot, Isabelle; Goupy, Pascale; Caris-Veyrat, Catherine; Reboul, Emmanuelle

    2014-10-31

    Vitamin K1 (phylloquinone) intestinal absorption is thought to be mediated by a carrier protein that still remains to be identified. Apical transport of vitamin K1 was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium and in transfected HEK cells. Phylloquinone uptake was then measured ex vivo using mouse intestinal explants. Finally, vitamin K1 absorption was compared between wild-type mice and mice overexpressing scavenger receptor class B type I (SR-BI) in the intestine and mice deficient in cluster determinant 36 (CD36). Phylloquinone uptake by Caco-2 cells was saturable and was significantly impaired by co-incubation with α-tocopherol (and vice versa). Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 85% of vitamin K1 uptake. BLT1 also decreased phylloquinone apical efflux by ∼80%. Transfection of HEK cells with SR-BI and CD36 significantly enhanced vitamin K1 uptake, which was subsequently decreased by the addition of BLT1 or sulfo-N-succinimidyl oleate (CD36 inhibitor), respectively. Similar results were obtained in mouse intestinal explants. In vivo, the phylloquinone postprandial response was significantly higher, and the proximal intestine mucosa phylloquinone content 4 h after gavage was increased in mice overexpressing SR-BI compared with controls. Phylloquinone postprandial response was also significantly increased in CD36-deficient mice compared with wild-type mice, but their vitamin K1 intestinal content remained unchanged. Overall, the present data demonstrate for the first time that intestinal scavenger receptors participate in the absorption of dietary phylloquinone.

  12. Intestinal Scavenger Receptors Are Involved in Vitamin K1 Absorption*

    PubMed Central

    Goncalves, Aurélie; Margier, Marielle; Roi, Stéphanie; Collet, Xavier; Niot, Isabelle; Goupy, Pascale; Caris-Veyrat, Catherine; Reboul, Emmanuelle

    2014-01-01

    Vitamin K1 (phylloquinone) intestinal absorption is thought to be mediated by a carrier protein that still remains to be identified. Apical transport of vitamin K1 was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium and in transfected HEK cells. Phylloquinone uptake was then measured ex vivo using mouse intestinal explants. Finally, vitamin K1 absorption was compared between wild-type mice and mice overexpressing scavenger receptor class B type I (SR-BI) in the intestine and mice deficient in cluster determinant 36 (CD36). Phylloquinone uptake by Caco-2 cells was saturable and was significantly impaired by co-incubation with α-tocopherol (and vice versa). Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 85% of vitamin K1 uptake. BLT1 also decreased phylloquinone apical efflux by ∼80%. Transfection of HEK cells with SR-BI and CD36 significantly enhanced vitamin K1 uptake, which was subsequently decreased by the addition of BLT1 or sulfo-N-succinimidyl oleate (CD36 inhibitor), respectively. Similar results were obtained in mouse intestinal explants. In vivo, the phylloquinone postprandial response was significantly higher, and the proximal intestine mucosa phylloquinone content 4 h after gavage was increased in mice overexpressing SR-BI compared with controls. Phylloquinone postprandial response was also significantly increased in CD36-deficient mice compared with wild-type mice, but their vitamin K1 intestinal content remained unchanged. Overall, the present data demonstrate for the first time that intestinal scavenger receptors participate in the absorption of dietary phylloquinone. PMID:25228690

  13. Protective Effects of Human and Mouse Soluble Scavenger-Like CD6 Lymphocyte Receptor in a Lethal Model of Polymicrobial Sepsis

    PubMed Central

    Martínez-Florensa, Mario; Consuegra-Fernández, Marta; Aranda, Fernando; Armiger-Borràs, Noelia; Di Scala, Marianna; Carrasco, Esther; Pachón, Jerónimo; Vila, Jordi; González-Aseguinolaza, Gloria

    2016-01-01

    ABSTRACT Sepsis still constitutes an unmet clinical need, which could benefit from novel adjunctive strategies to conventional antibiotic therapy. The soluble form of the scavenger-like human CD6 lymphocyte receptor (shCD6) binds to key pathogenic components from Gram-positive and -negative bacteria and shows time- and dose-dependent efficacy in mouse models of monobacterial sepsis. The objective of the present work was to demonstrate the effectiveness of infusing mouse and human sCD6 by different systemic routes, either alone or as adjunctive therapy to gold standard antibiotics, in a lethal model of polymicrobial sepsis. To this end, C57BL/6 mice undergoing high-grade septic shock induced by cecal ligation and puncture (CLP; ≥90% lethality) were infused via the intraperitoneal (i.p.) or intravenous (i.v.) route with shCD6 at different doses and time points, either alone or in combination with imipenem/cilastatin (I/C) at a dose of 33 mg/kg of body weight every 8 h. Significantly reduced mortality and proinflammatory cytokine levels were observed by i.p. infusion of a single shCD6 dose (1.25 mg/kg) 1 h pre- or post-CLP. When using the i.v. route, mice survival was significantly extended by starting shCD6 infusion at later time points post-CLP (up to 6 h after CLP). Significant adjunctive effects on mouse survival were observed by i.p. or i.v. infusion of shCD6 in combination with i.p. I/C post-CLP. Similar results were obtained in mice expressing high sustained levels (5 to 10 μg/ml) of mouse sCD6 in serum by means of transduction with hepatotropic adeno-associated virus (AAV). Taken together, the data support the conserved antibacterial effects of human and mouse sCD6 and their use as adjunctive therapy in experimental models of complex and severe polymicrobial sepsis. PMID:27895015

  14. Protective Effects of Human and Mouse Soluble Scavenger-Like CD6 Lymphocyte Receptor in a Lethal Model of Polymicrobial Sepsis.

    PubMed

    Martínez-Florensa, Mario; Consuegra-Fernández, Marta; Aranda, Fernando; Armiger-Borràs, Noelia; Di Scala, Marianna; Carrasco, Esther; Pachón, Jerónimo; Vila, Jordi; González-Aseguinolaza, Gloria; Lozano, Francisco

    2017-01-01

    Sepsis still constitutes an unmet clinical need, which could benefit from novel adjunctive strategies to conventional antibiotic therapy. The soluble form of the scavenger-like human CD6 lymphocyte receptor (shCD6) binds to key pathogenic components from Gram-positive and -negative bacteria and shows time- and dose-dependent efficacy in mouse models of monobacterial sepsis. The objective of the present work was to demonstrate the effectiveness of infusing mouse and human sCD6 by different systemic routes, either alone or as adjunctive therapy to gold standard antibiotics, in a lethal model of polymicrobial sepsis. To this end, C57BL/6 mice undergoing high-grade septic shock induced by cecal ligation and puncture (CLP; ≥90% lethality) were infused via the intraperitoneal (i.p.) or intravenous (i.v.) route with shCD6 at different doses and time points, either alone or in combination with imipenem/cilastatin (I/C) at a dose of 33 mg/kg of body weight every 8 h. Significantly reduced mortality and proinflammatory cytokine levels were observed by i.p. infusion of a single shCD6 dose (1.25 mg/kg) 1 h pre- or post-CLP. When using the i.v. route, mice survival was significantly extended by starting shCD6 infusion at later time points post-CLP (up to 6 h after CLP). Significant adjunctive effects on mouse survival were observed by i.p. or i.v. infusion of shCD6 in combination with i.p. I/C post-CLP. Similar results were obtained in mice expressing high sustained levels (5 to 10 μg/ml) of mouse sCD6 in serum by means of transduction with hepatotropic adeno-associated virus (AAV). Taken together, the data support the conserved antibacterial effects of human and mouse sCD6 and their use as adjunctive therapy in experimental models of complex and severe polymicrobial sepsis. Copyright © 2016 American Society for Microbiology.

  15. Investigation into Seasonal Scavenging Patterns of Raccoons on Human Decomposition.

    PubMed

    Jeong, Yangseung; Jantz, Lee Meadows; Smith, Jake

    2016-03-01

    Although raccoons are known as one of the most common scavengers in the U.S., scavenging by these animals has seldom been studied in terms of forensic significance. In this research, the seasonal pattern of raccoon scavenging and its effect on human decomposition was investigated using 178 human cadavers placed at the Anthropological Research Facility (ARF) of the University of Tennessee, Knoxville (UTK) between February 2011 and December 2013. The results reveal that (i) the frequency of scavenging increases during summer, (ii) scavenging occurs relatively immediately and lasts shorter in summer months, and (iii) scavenging influences the decomposition process by hollowing limbs and by disturbing insect activities, both of which eventually increases the chance of mummification on the affected body. This information is expected to help forensic investigators identify raccoon scavenging as well as make a more precise interpretation of the effect of raccoon scavenging on bodies at crime scenes. © 2015 American Academy of Forensic Sciences.

  16. Scavenger Receptors and Resistance to Inhaled Allergens

    DTIC Science & Technology

    2010-02-01

    procedures were performed at 4°C. Cells were preincubated for 20 min with a Fc receptor blocking Ab (anti-CD16/ CD32 ; BD Biosciences) to reduce...106 per ml and incu- bated  in 20 μg/ml  rat  anti-mouse CD16/ CD32   (catalog no. 553140;  BD Biosciences — Pharmingen) for 45 minutes on ice. After 45

  17. Scavenger Receptors and Resistance to Inhaled Allergens

    DTIC Science & Technology

    2007-02-01

    resistance to asthma and pneumonia. The scope of the research includes studies using in vivo mouse models (Aim 1), studies of the specific role of...in modulating allergic responses using the mouse model. We have made good progress, matching the projected completion of task 1 in year 1. This...defense of the lung against inhaled allergens using receptor-deficient mice and a model of allergic asthma. We found that sensitized mice lacking SRAs

  18. Diagnostic and prognostic value of scavenger receptor class B type 1 in clear cell renal cell carcinoma.

    PubMed

    Xu, Guanghua; Lou, Ning; Xu, Yuchen; Shi, Hangchuan; Ruan, Hailong; Xiao, Wen; Liu, Lei; Xiao, Haibing; Qiu, Bin; Bao, Lin; Yuan, Changfei; Chen, Ke; Yang, Hongmei; Zhang, Xiaoping

    2017-05-01

    Aberrant expression of scavenger receptor class B type 1 has been reported in several human cancers. Nevertheless, the roles of scavenger receptor class B type 1 in clear cell renal cell carcinoma remain unclear. The aim of this study was to evaluate the diagnostic and prognostic value of scavenger receptor class B type 1 in clear cell renal cell carcinoma. The messenger RNA level of scavenger receptor class B type 1 in clear cell renal cell carcinoma tissues was detected by quantitative reverse transcription polymerase chain reaction, while protein level was determined by western blot and immunohistochemistry. The lipid content between clear cell renal cell carcinoma tissues and normal kidney tissues was differentiated by Oil Red O and hematoxylin-eosin staining. The diagnostic value of scavenger receptor class B type 1 was determined by receiver operating characteristic curve. The prognostic significance of scavenger receptor class B type 1 was assessed by Kaplan-Meier analysis and Cox regression analysis. Our results showed that the expression of scavenger receptor class B type 1 in clear cell renal cell carcinoma tissues at both messenger RNA and protein level was much higher than that in normal kidney tissues. Receiver operating characteristic curve analysis exhibited a significant value of area under the curve (0.8486, 95% confidence interval: 0.7926-0.9045) with strong sensitivity (0.75, 95% confidence interval: 0.6535-0.8312) and specificity (0.90, 95% confidence interval: 0.8238-0.9510). Kaplan-Meier analysis revealed that patients with higher scavenger receptor class B type 1 expression had shorter progression-free survival time. Cox analysis indicated that scavenger receptor class B type 1 was an independent prognostic biomarker. In conclusion, our findings implied that scavenger receptor class B type 1 might serve as a diagnostic and independent prognostic biomarker in clear cell renal cell carcinoma.

  19. Scavenging energy from human limb motions

    NASA Astrophysics Data System (ADS)

    Fan, Kangqi; Yu, Bo; Tang, Lihua

    2017-04-01

    This paper proposes a nonlinear piezoelectric energy harvester (PEH) to scavenge energy from human limb motions. The proposed PEH is composed of a ferromagnetic ball, a sleeve, and two piezoelectric cantilever beams each with a magnetic tip mass. The ball is used to sense the swing motions of human limbs and excite the beams to vibrate. The two beams, which are sensitive to the excitation along the radialis or tibial axis, generate electrical outputs. Theoretical and experimental studies are carried out to examine the performance of the proposed PEH when it is fixed at the wrist, thigh and ankle of a male who travels at constant velocities of 2 km/h, 4 km/h, 6 km/h, and 8 km/h on a treadmill. The results indicate that the low-frequency swing motions of human limbs are converted to higher-frequency vibrations of piezoelectric beams. During each gait cycle, different excitations produced by human limbs can be superposed and multiple peaks in the voltage output can be generated by the proposed PEH. Moreover, the voltage outputs of the PEH increase monotonously with the walking speed, and the maximum effective voltage is obtained when the PEH is mounted at the ankle under the walking speed of 8 km/h.

  20. Fluorescence energy transfer studies on the macrophage scavenger receptor

    NASA Astrophysics Data System (ADS)

    Louie, Angelique Y.; Tromberg, Bruce J.; Berns, Michael W.

    1994-08-01

    The macrophage scavenger receptor is a transmembrane, trimeric glycoprotein which recognizes a number of negatively charged ligands. Cross competition studies of various ligands indicate that the scavenger receptor may bear more than one type of binding site or that there may be more than one type of receptor. In this study we employed resonance energy transfer techniques to identify the location of the binding site for maleylated bovine serum albumin. Using vesicles derived from plasma membrane, we labeled the ligand with a donor probe and labeled the membrane surface with acceptor probes to determine the distance of bound ligand from the membrane surface. Measurements were taken with three different donor-acceptor pairs. Transfer measurements for ligand labeled with dansyl and HAE (hexadecanoylaminoeosin) as the acceptor yielded a distance of 47 angstrom from the surface of the plasma membrane. Similar measurements employing the same donors but using ORB (octadecylrhodamine B) as the acceptor produced a distance of 58 angstrom. Assuming that the receptor extends perpendicularly from the cell surface this distance lies within the two receptor `domains' closest to the cell surface. These domains include the spacer region, with no distinct proposed structure and a region which has sequence similarity to an alpha helical coiled coil. No transfer was observed between ligand monolabeled with fluorescein and DiI in the membrane. This suggests that the orientation of mal-BSA bound to receptor places the fluorescein probe too far from acceptor on the membrane surface to experience energy transfer.

  1. Human disturbance of an avian scavenging guild

    USGS Publications Warehouse

    Skagen, Susan K.; Knight, Richard L.; Orians, Gordon H.

    1991-01-01

    In order to investigate the effects of human activities on relationships within foraging guilds, we examined inacanus dynamics of eagles, crows, and gulls scavenging on spawned salmon in the Pacific Northwest. We examined several hypotheses that postulate the asymmetric foraging relationships of the three guild members and that reveal the influence of competition and facilitation in these relationships. Spatial and temporal patterns of resource use by the three primary guild members varied with the presence and absence of human activity at experimental feeding stations. At control (undisturbed) stations, eagles preferred to feed >100 m from vegetative cover, whereas gulls fed <50 m from cover. At experimental (disturbed) stations, eagles rarely fed, and feeding activity by gulls increased at both near and far stations. Crows often fed on alternate food sources in fields adjacent to the river, especially when salmon carcasses were scarce, whereas eagles and gulls rarely did so. We also examined if and how the behavior of single guild members changes in the presence or absence of other guild members. In the absence of eagles, gulls and crows preferred stations far from cover, numbers of both increased at feeding stations, birds were distributed nearer to carcasses, and they fed more. We emphasize that guild theory lends important insights to our understanding of the effects of human disturbance on wildlife communities.

  2. Dietary homocysteine promotes atherosclerosis in apoE-deficient mice by inducing scavenger receptors expression

    USDA-ARS?s Scientific Manuscript database

    Elevated plasma homocysteine (Hcy) levels have been recognized as an independent risk factor for cardiovascular and cerebrovascular diseases. However, the causative mechanisms have not been delineated. Scavenger receptors such as scavenger receptor-AI/II (SR-A), CD36, and lectin-like oxidized LDL ...

  3. Scavenger receptor A gene regulatory elements target gene expression to macrophages and to foam cells of atherosclerotic lesions.

    PubMed Central

    Horvai, A; Palinski, W; Wu, H; Moulton, K S; Kalla, K; Glass, C K

    1995-01-01

    Transcription of the macrophage scavenger receptor A gene is markedly upregulated during monocyte to macrophage differentiation. In these studies, we demonstrate that 291 bp of the proximal scavenger receptor promoter, in concert with a 400-bp upstream enhancer element, is sufficient to direct macrophage-specific expression of a human growth hormone reporter in transgenic mice. These regulatory elements, which contain binding sites for PU.1, AP-1, and cooperating ets-domain transcription factors, are also sufficient to mediate regulation of transgene expression during the in vitro differentiation of bone marrow progenitor cells in response to macrophage colony-stimulating factor. Mutation of the PU.1 binding site within the scavenger receptor promoter severely impairs transgene expression, consistent with a crucial role of PU.1 in regulating the expression of the scavenger receptor gene. The ability of the scavenger receptor promoter and enhancer to target gene expression to macrophages in vivo, including foam cells of atherosclerotic lesions, suggests that these regulatory elements will be of general utility in the study of macrophage differentiation and function by permitting specific modifications of macrophage gene expression. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:7777517

  4. Molecular cloning, mapping to human chromosome 1 q21-q23, and cell binding characteristics of Spalpha, a new member of the scavenger receptor cysteine-rich (SRCR) family of proteins.

    PubMed

    Gebe, J A; Kiener, P A; Ring, H Z; Li, X; Francke, U; Aruffo, A

    1997-03-07

    CD5 and CD6, two type I cell surface antigens predominantly expressed by T cells and a subset of B cells, have been shown to function as accessory molecules capable of modulating T cell activation. Here we report the cloning of a cDNA encoding Spalpha, a secreted protein that is highly homologous to CD5 and CD6. Spalpha has the same domain organization as the extracellular region of CD5 and CD6 and is composed of three SRCR (scavenger receptor cysteine rich) domains. Chromosomal mapping by fluorescence in situ hybridization and radiation hybrid panel analysis indicated that the gene encoding Spalpha is located on the long arm of human chromosome 1 at q21-q23 within contig WC1.17. RNA transcripts encoding Spalpha were found in human bone marrow, spleen, lymph node, thymus, and fetal liver but not in non-lymphoid tissues. Cell binding studies with an Spalpha immunoglobulin (Spalpha-mIg) fusion protein indicated that Spalpha is capable of binding to peripheral monocytes but not to T or B cells. Spalpha-mIg was also found to bind to the monocyte precursor cell lines K-562 and weakly to THP-1 but not to U937. Spalpha-mIg also bound to the B cell line Raji and weakly to the T cell line HUT-78. These findings indicate that Spalpha, a novel secreted protein produced in lymphoid tissues, may regulate monocyte activation, function, and/or survival.

  5. Scavenger receptor b2 as a receptor for hand, foot, and mouth disease and severe neurological diseases.

    PubMed

    Yamayoshi, Seiya; Fujii, Ken; Koike, Satoshi

    2012-01-01

    Enterovirus 71 (EV71) is one of the major causative agents of hand, foot, and mouth disease (HFMD). Infection with EV71 is occasionally associated with severe neurological diseases such as acute encephalitis, acute flaccid paralysis, and cardiopulmonary failure. Because cellular receptors for viruses play an important role in cell, tissue, and species tropism, it is important to identify and characterize the receptor molecule. Recently, cellular receptors and host factors that stimulate EV71 infection have been identified. Several lines of evidence suggest that scavenger receptor class B, member 2 (SCARB2) plays critical roles in efficient EV71 infection and the development of disease in humans. In this review, we will summarize the findings of recent studies on EV71 infection and on the roles of SCARB2.

  6. Defective expression of scavenger receptors in celiac disease mucosa.

    PubMed

    Cupi, Maria Laura; Sarra, Massimiliano; De Nitto, Daniela; Franzè, Eleonora; Marafini, Irene; Monteleone, Ivan; Del Vecchio Blanco, Giovanna; Paoluzi, Omero Alessandro; Di Fusco, Davide; Gentileschi, Paolo; Ortenzi, Angela; Colantoni, Alfredo; Pallone, Francesco; Monteleone, Giovanni

    2014-01-01

    Celiac disease (CD) is a gluten sensitive enteropathy characterized by a marked infiltration of the mucosa with immune cells, over-production of inflammatory cytokines and epithelial cell damage. The factors/mechanisms that sustain and amplify the ongoing mucosal inflammation in CD are not however fully understood. Here, we have examined whether in CD there is a defective clearance of apoptotic cells/bodies, a phenomenon that helps promote tolerogenic signals thus liming pathogenic responses. Accumulation of apoptotic cells and bodies was more pronounced in the epithelial and lamina propria compartments of active CD patients as compared to inactive CD patients and normal controls. Expression of scavenger receptors, which are involved in the clearance of apoptotic cells/bodies, namely thrombospondin (TSP)-1, CD36 and CD61, was significantly reduced in active CD as compared to inactive CD and normal mucosal samples. Consistently, lamina propria mononuclear cells (LPMC) of active CD patients had diminished ability to phagocyte apoptotic cells. Interleukin (IL)-15, IL-21 and interferon-γ, cytokines over-produced in active CD, inhibited the expression of TSP-1, CD36, and CD61 in normal intestinal LPMC. These results indicate that CD-related inflammation is marked by diminished clearance of apoptotic cells/bodies, thus suggesting a role for such a defect in the ongoing mucosal inflammation in this disorder.

  7. Defective Expression of Scavenger Receptors in Celiac Disease Mucosa

    PubMed Central

    Cupi, Maria Laura; Sarra, Massimiliano; De Nitto, Daniela; Franzè, Eleonora; Marafini, Irene; Monteleone, Ivan; Del Vecchio Blanco, Giovanna; Paoluzi, Omero Alessandro; Di Fusco, Davide; Gentileschi, Paolo; Ortenzi, Angela; Colantoni, Alfredo; Pallone, Francesco; Monteleone, Giovanni

    2014-01-01

    Celiac disease (CD) is a gluten sensitive enteropathy characterized by a marked infiltration of the mucosa with immune cells, over-production of inflammatory cytokines and epithelial cell damage. The factors/mechanisms that sustain and amplify the ongoing mucosal inflammation in CD are not however fully understood. Here, we have examined whether in CD there is a defective clearance of apoptotic cells/bodies, a phenomenon that helps promote tolerogenic signals thus liming pathogenic responses. Accumulation of apoptotic cells and bodies was more pronounced in the epithelial and lamina propria compartments of active CD patients as compared to inactive CD patients and normal controls. Expression of scavenger receptors, which are involved in the clearance of apoptotic cells/bodies, namely thrombospondin (TSP)-1, CD36 and CD61, was significantly reduced in active CD as compared to inactive CD and normal mucosal samples. Consistently, lamina propria mononuclear cells (LPMC) of active CD patients had diminished ability to phagocyte apoptotic cells. Interleukin (IL)-15, IL-21 and interferon-γ, cytokines over-produced in active CD, inhibited the expression of TSP-1, CD36, and CD61 in normal intestinal LPMC. These results indicate that CD-related inflammation is marked by diminished clearance of apoptotic cells/bodies, thus suggesting a role for such a defect in the ongoing mucosal inflammation in this disorder. PMID:24971453

  8. Scavenger receptor BI modulates platelet reactivity and thrombosis in dyslipidemia.

    PubMed

    Ma, Yi; Ashraf, Mohammad Z; Podrez, Eugene A

    2010-09-16

    Hypercholesterolemia is associated with increased platelet sensitivity to agonists and a prothrombotic phenotype. Mechanisms of platelet hypersensitivity are poorly understood; however, increased platelet cholesterol levels associated with hypercholesterolemia were proposed as leading to hypersensitivity. Scavenger receptor class B type I (SR-BI) in the liver controls plasma high-density lipoprotein (HDL) levels, and SR-BI-deficient mice display a profound dyslipoproteinemia. SR-BI is also expressed on platelets, and recent studies have suggested a role for SR-BI in platelet function; however, its role in hemostasis is unknown. Our present studies demonstrated that non-bone marrow-derived SR-BI deficiency and the dyslipidemia associated with it lead to platelet hyperreactivity that was mechanistically linked to increased platelet cholesterol content. Platelet-specific deficiency of SR-BI, on the other hand, was associated with resistance to hyperreactivity induced by increased platelet cholesterol content. Intravital thrombosis studies demonstrated that platelet SR-BI deficiency protected mice from prothrombotic phenotype in 2 types of dyslipidemia associated with increased platelet cholesterol content. These novel findings demonstrate that SR-BI plays dual roles in thrombosis and may contribute to acute cardiovascular events in vivo in hypercholesterolemia.

  9. Scavenger Receptors and Their Potential as Therapeutic Targets in the Treatment of Cardiovascular Disease

    PubMed Central

    Stephen, Sam L.; Freestone, Katie; Dunn, Sarah; Twigg, Michael W.; Homer-Vanniasinkam, Shervanthi; Walker, John H.; Wheatcroft, Stephen B.; Ponnambalam, Sreenivasan

    2010-01-01

    Scavenger receptors act as membrane-bound and soluble proteins that bind to macromolecular complexes and pathogens. This diverse supergroup of proteins mediates binding to modified lipoprotein particles which regulate the initiation and progression of atherosclerotic plaques. In vascular tissues, scavenger receptors are implicated in regulating intracellular signaling, lipid accumulation, foam cell development, and cellular apoptosis or necrosis linked to the pathophysiology of atherosclerosis. One approach is using gene therapy to modulate scavenger receptor function in atherosclerosis. Ectopic expression of membrane-bound scavenger receptors using viral vectors can modify lipid profiles and reduce the incidence of atherosclerosis. Alternatively, expression of soluble scavenger receptors can also block plaque initiation and progression. Inhibition of scavenger receptor expression using a combined gene therapy and RNA interference strategy also holds promise for long-term therapy. Here we review our current understanding of the gene delivery by viral vectors to cells and tissues in gene therapy strategies and its application to the modulation of scavenger receptor function in atherosclerosis. PMID:20981357

  10. Scavenger receptor BI and HDL regulate thymocyte apoptosis in sepsis

    PubMed Central

    Guo, Ling; Zheng, Zhong; Ai, Junting; Howatt, Deborah A.; Mittelstadt, Paul R.; Thacker, Seth; Daugherty, Alan; Ashwell, Jonathan D.; Remaley, Alan T.; Li, Xiang-An

    2014-01-01

    Objective Thymocyte apoptosis is a major event in sepsis; however, how this process is regulated remains poorly understood. Approach and Results Septic stress induces glucocorticoids (GC) production which triggers thymocyte apoptosis. Here, we used scavenger receptor BI (SR-BI) null mice, which are completely deficient in inducible GC (iGC) in sepsis, to investigate the regulation of thymocyte apoptosis in sepsis. Cecal ligation and puncture (CLP) induced profound thymocyte apoptosis in SR-BI+/+ mice, but no thymocyte apoptosis in SR-BI−/− mice due to lack of iGC. Unexpectedly, supplementation of GC only partly restored thymocyte apoptosis in SR-BI−/− mice. We demonstrated that HDL is a critical modulator for thymocyte apoptosis. SR-BI+/+ HDL significantly enhanced GC-induced thymocyte apoptosis but SR-BI−/− HDL had no such activity. Further study revealed that SR-BI+/+ HDL modulates GC-induced thymocyte apoptosis via promoting glucocorticoid receptor translocation, but SR-BI−/− HDL loses such regulatory activity. To understand why SR-BI−/− HDL loses its regulatory activity, we analyzed HDL cholesterol contents. There was 3-fold enrichment of unesterified cholesterol in SR-BI−/− HDL compared with SR-BI+/+ HDL. Normalization of unesterified cholesterol in SR-BI−/− HDL by probucol administration or LCAT expression restored GC-induced thymocyte apoptosis, and incorporating unesterified cholesterol into SR-BI+/+ HDL rendered SR-BI+/+ HDL dysfunctional. Using lckCre-GRfl/fl mice in whom thymocytes lack CLP-induced thymocyte apoptosis, we showed that lckCre-GRfl/fl mice were significantly more susceptible to CLP-induced septic death than GRfl/fl control mice, suggesting that GC-induced thymocyte apoptosis is required for protection against sepsis. Conclusions The findings in this study reveal a novel regulatory mechanism of thymocyte apoptosis in sepsis by SR-BI and HDL. PMID:24603680

  11. HSV-1 exploits the innate immune scavenger receptor MARCO to enhance epithelial adsorption and infection

    PubMed Central

    MacLeod, Daniel T.; Nakatsuji, Teruaki; Yamasaki, Kenshi; Kobzik, Lester; Gallo, Richard L.

    2013-01-01

    HSV-1 is an important epithelial pathogen and has the potential for significant morbidity in humans. Here we demonstrate that a cell surface scavenger receptor, macrophage receptor with collagenous structure (MARCO), previously thought to enhance antiviral defense by enabling nucleic acid recognition, is usurped by HSV-1 and functions together with heparan sulfate proteoglycans to mediate adsorption to epithelial cells. Ligands of MARCO dramatically inhibit HSV-1 adsorption and infection of human keratinocytes and protect mice against infection. HSV-1 glycoprotein C (gC) closely co-localizes with MARCO at the cell surface, and gC binds directly to purified MARCO with high affinity. Increasing MARCO expression enhances HSV-1 infection while MARCO-/- mice have reduced susceptibility to infection by HSV-1. These findings demonstrate that HSV-1 binds to MARCO to enhance its capacity for disease, and suggests a new therapeutic target to alter pathogenicity of HSV-1 in skin infection. PMID:23739639

  12. Scavenging energy from human motion with tubular dielectric polymer

    NASA Astrophysics Data System (ADS)

    Jean-Mistral, Claire; Basrour, Skandar

    2010-04-01

    Scavenging energy from human motion is a challenge to supply low consumption systems for sport or medical applications. A promising solution is to use electroactive polymers and especially dielectric polymers to scavenge mechanical energy during walk. In this paper, we present a tubular dielectric generator which is the first step toward an integration of these structures into textiles. For a 10cm length and under a strain of 100%, the structure is able to scavenge 1.5μJ for a poling voltage of 200V and up to 40μJ for a poling voltage of 1000V. A 30cm length structure is finally compared to our previous planar structure, and the power management module for those structures is discussed.

  13. Amphiphilic Nanoparticles Repress Macrophage Atherogenesis: Novel Core/Shell Designs for Scavenger Receptor Targeting and Down-Regulation

    PubMed Central

    2015-01-01

    Atherosclerosis, an inflammatory lipid-rich plaque disease is perpetuated by the unregulated scavenger-receptor-mediated uptake of oxidized lipoproteins (oxLDL) in macrophages. Current treatments lack the ability to directly inhibit oxLDL accumulation and foam cell conversion within diseased arteries. In this work, we harness nanotechnology to design and fabricate a new class of nanoparticles (NPs) based on hydrophobic mucic acid cores and amphiphilic shells with the ability to inhibit the uncontrolled uptake of modified lipids in human macrophages. Our results indicate that tailored NP core and shell formulations repress oxLDL internalization via dual complementary mechanisms. Specifically, the most atheroprotective molecules in the NP cores competitively reduced NP-mediated uptake to scavenger receptor A (SRA) and also down-regulated the surface expression of SRA and CD36. Thus, nanoparticles can be designed to switch activated, lipid-scavenging macrophages to antiatherogenic phenotypes, which could be the basis for future antiatherosclerotic therapeutics. PMID:24972372

  14. Uptake and metabolism of polymerized albumin by rat liver. Role of the scavenger receptor

    SciTech Connect

    Wright, T.L.; Roll, F.J.; Jones, A.L.; Weisiger, R.A.

    1988-02-01

    Hepatitis B virus binds avidly to albumin polymers, which in turn may mediate viral attachment to liver cells. This hypothesis is critically dependent on prior results obtained using glutaraldehyde-polymerized human serum albumin as a model for naturally occurring albumin species. We used the perfused rat liver to characterize the uptake, cellular distribution, and metabolism of glutaraldehyde-polymerized human albumin. /sup 125/I-glutaraldehyde-polymerized human albumin was efficiently removed from the perfusate by the liver (29% extraction). However, few autoradiographic grains were located over hepatic parenchymal cells (6%). Instead, most glutaraldehyde-polymerized human albumin appeared to be removed by endothelial (59%) or Kupffer (31%) cells. Hepatic uptake was strongly inhibited by formaldehyde-treated monomeric albumin, a known ligand of the endothelial scavenger receptor for chemically modified proteins. After uptake, most glutaraldehyde-polymerized human albumin was rapidly degraded and released into the perfusate (74% within 60 min). This process was blocked by chloroquine and leupeptin, suggesting that it involves lysosomal acid hydrolases. We conclude that glutaraldehyde-polymerized albumin is efficiently cleared and degraded by the endothelial scavenger pathway. Glutaraldehyde-polymerized albumin therefore appears to be a poor model for predicting the hepatic handling of naturally occurring albumin species bound to hepatitis B virions. Even if viral particles were to follow this pathway, few would enter parenchymal hepatocytes.

  15. Phagocytosis in vitro of polyethylene glycol-modified liposome-encapsulated hemoglobin by human peripheral blood monocytes plus macrophages through scavenger receptors.

    PubMed

    Shibuya-Fujiwara, N; Hirayama, F; Ogata, Y; Ikeda, H; Ikebuchi, K

    2001-12-07

    Liposome-encapsulated hemoglobin (LEH), a candidate for red blood cell substitute, is cleared from circulation primarily by the phagocytic system, most likely after opsonization of the vesicles by immunoproteins, particularly complement components. Although modification of LEH by polyethylene glycol (PEG) derivatives prolongs its half-life by blocking the opsonization, the half-life is still short as compared with that of red blood cell components. Therefore, this study was performed to elucidate the opsonin-independent mechanisms that regulate phagocytosis of Neo Red Cell (NRC), a PEG-modified LEH, in culture. PKH67 was used as a fluorescence marker, allowing the quantitation of the phagocytosis of NRC by peripheral blood monocytes plus macrophages. The phagocytosis of PKH67-labeled NRC was inhibited by the addition of an excess of unlabeled NRC, indicating that the phagocytosis of PKH67-labeled NRC is specific to NRC, but not to PKH67. The phagocytosis of NRC was blocked about 70% by anti-CD14, 60% by anti-CD36 and 30% by anti-CD51/61 (vitronectin receptor, alpha(v)beta3). These results provided evidence of an opsonin-independent pathway for the phagocytosis of PEG-modified LEH.

  16. Scavenger receptor mediates systemic RNA interference in ticks.

    PubMed

    Aung, Kyaw Min; Boldbaatar, Damdinsuren; Umemiya-Shirafuji, Rika; Liao, Min; Xuenan, Xuan; Suzuki, Hiroshi; Galay, Remil Linggatong; Tanaka, Tetsuya; Fujisaki, Kozo

    2011-01-01

    RNA interference is an efficient method to silence gene and protein expressions. Here, the class B scavenger receptor CD36 (SRB) mediated the uptake of exogenous dsRNAs in the induction of the RNAi responses in ticks. Unfed female Haemaphysalis longicornis ticks were injected with a single or a combination of H. longicornis SRB (HlSRB) dsRNA, vitellogenin-1 (HlVg-1) dsRNA, and vitellogenin receptor (HlVgR) dsRNA. We found that specific and systemic silencing of the HlSRB, HlVg-1, and HlVgR genes was achieved in ticks injected with a single dsRNA of HlSRB, HlVg-1, and HlVgR. In ticks injected first with HlVg-1 or HlVgR dsRNA followed 96 hours later with HlSRB dsRNA (HlVg-1/HlSRB or HlVgR/HlSRB), gene silencing of HlSRB was achieved in addition to first knockdown in HlVg-1 or HlVgR, and prominent phenotypic changes were observed in engorgement, mortality, and hatchability, indicating that a systemic and specific double knockdown of target genes had been simultaneously attained in these ticks. However, in ticks injected with HlSRB dsRNA followed 96 hours later with HlVg-1 or HlVgR dsRNAs, silencing of HlSRB was achieved, but no subsequent knockdown in HlVgR or HlVg-1 was observed. The Westernblot and immunohistochemical examinations revealed that the endogenous HlSRB protein was fully abolished in midguts of ticks injected with HlSRB/HlVg-1 dsRNAs but HlVg-1 was normally expressed in midguts, suggesting that HlVg-1 dsRNA-mediated RNAi was fully inhibited by the first knockdown of HlSRB. Similarly, the abolished localization of HlSRB protein was recognized in ovaries of ticks injected with HlSRB/HlVgR, while normal localization of HlVgR was observed in ovaries, suggesting that the failure to knock-down HlVgR could be attributed to the first knockdown of HlSRB. In summary, we demonstrated for the first time that SRB may not only mediate the effective knock-down of gene expression by RNAi but also play essential roles for systemic RNAi of ticks.

  17. Scavenger Receptor Mediates Systemic RNA Interference in Ticks

    PubMed Central

    Aung, Kyaw Min; Boldbaatar, Damdinsuren; Umemiya-Shirafuji, Rika; Liao, Min; Xuenan, Xuan; Suzuki, Hiroshi; Linggatong Galay, Remil; Tanaka, Tetsuya; Fujisaki, Kozo

    2011-01-01

    RNA interference is an efficient method to silence gene and protein expressions. Here, the class B scavenger receptor CD36 (SRB) mediated the uptake of exogenous dsRNAs in the induction of the RNAi responses in ticks. Unfed female Haemaphysalis longicornis ticks were injected with a single or a combination of H. longicornis SRB (HlSRB) dsRNA, vitellogenin-1 (HlVg-1) dsRNA, and vitellogenin receptor (HlVgR) dsRNA. We found that specific and systemic silencing of the HlSRB, HlVg-1, and HlVgR genes was achieved in ticks injected with a single dsRNA of HlSRB, HlVg-1, and HlVgR. In ticks injected first with HlVg-1 or HlVgR dsRNA followed 96 hours later with HlSRB dsRNA (HlVg-1/HlSRB or HlVgR/HlSRB), gene silencing of HlSRB was achieved in addition to first knockdown in HlVg-1 or HlVgR, and prominent phenotypic changes were observed in engorgement, mortality, and hatchability, indicating that a systemic and specific double knockdown of target genes had been simultaneously attained in these ticks. However, in ticks injected with HlSRB dsRNA followed 96 hours later with HlVg-1 or HlVgR dsRNAs, silencing of HlSRB was achieved, but no subsequent knockdown in HlVgR or HlVg-1 was observed. The Westernblot and immunohistochemical examinations revealed that the endogenous HlSRB protein was fully abolished in midguts of ticks injected with HlSRB/HlVg-1 dsRNAs but HlVg-1 was normally expressed in midguts, suggesting that HlVg-1 dsRNA-mediated RNAi was fully inhibited by the first knockdown of HlSRB. Similarly, the abolished localization of HlSRB protein was recognized in ovaries of ticks injected with HlSRB/HlVgR, while normal localization of HlVgR was observed in ovaries, suggesting that the failure to knock-down HlVgR could be attributed to the first knockdown of HlSRB. In summary, we demonstrated for the first time that SRB may not only mediate the effective knock-down of gene expression by RNAi but also play essential roles for systemic RNAi of ticks. PMID:22145043

  18. Complementary Roles for Scavenger Receptor A and CD36 of Human Monocyte–derived Macrophages in Adhesion to Surfaces Coated with Oxidized Low-Density Lipoproteins and in Secretion of H2O2

    PubMed Central

    Maxeiner, Horst; Husemann, Jens; Thomas, Christian A.; Loike, John D.; Khoury, Joseph El; Silverstein, Samuel C.

    1998-01-01

    Oxidized low-density lipoprotein (oxLDL) is considered one of the principal effectors of atherogenesis. To explore mechanisms by which oxLDL affects human mononuclear phagocytes, we incubated these cells in medium containing oxLDL, acetylated LDL (acLDL), or native LDL, or on surfaces coated with these native and modified lipoproteins. The presence of soluble oxLDL, acLDL, or native LDL in the medium did not stimulate H2O2 secretion by macrophages. In contrast, macrophages adherent to surfaces coated with oxLDL secreted three- to fourfold more H2O2 than macrophages adherent to surfaces coated with acLDL or native LDL. Freshly isolated blood monocytes secreted little H2O2 regardless of the substrate on which they were plated. H2O2 secretion was maximal in cells maintained for 4–6 d in culture before plating on oxLDL-coated surfaces. Fucoidan, a known ligand of class A macrophage scavenger receptors (MSR-A), significantly reduced macrophage adhesion to surfaces coated with oxLDL or acLDL. Monoclonal antibody SMO, which blocks oxLDL binding to CD36, did not inhibit adhesion of macrophages to oxLDL-coated surfaces but markedly reduced H2O2 secretion by these cells. These studies show that MSR-A is primarily responsible for adhesion of macrophages to oxLDL-coated surfaces, that CD36 signals H2O2 secretion by macrophages adherent to these surfaces, and that substrate-bound, but not soluble, oxLDL stimulates H2O2 secretion by macrophages. PMID:9858512

  19. Scavenger receptor cysteine-rich domains 9 and 11 of WC1 are receptors for the WC1 counter receptor.

    PubMed

    Ahn, J S; Konno, A; Gebe, J A; Aruffo, A; Hamilton, M J; Park, Y H; Davis, W C

    2002-08-01

    Workshop cluster 1 (WC1) is a member of the scavenger receptor cysteine-rich (SRCR) superfamily that includes CD5, CD6, CD163, and M160. Bovine WC1 consists of 11 SRCR domains, a unique domain 1, and two homologous 5 SRCR domain cassettes, WC1 domains 2-6 and 7-11. The porcine orthologue of WC1 contains five SRCR domains with a different domain arrangement. Although the function of WC1 is unknown, WC1 is proposed to be an accessory or homing molecule. Thus, identification of cells that express the counter receptor for WC1 (WC1-CR) is critical to understanding the function of WC1. For this reason, we constructed WC1-human immunoglobulin G1 fusion proteins to identify the binding domain of WC1 and cells that express the WC1-CR. Immunohistochemical analysis revealed WC1 domains 9 and 11 bind cells with macrophage and dendritic cell morphology and cells in ellipsoids in the spleen. These results and the finding of conserved signaling motifs in the cytoplasmic tail suggest WC1 may be an accessory molecule.

  20. Free Actin Impairs Macrophage Bacterial Defenses via Scavenger Receptor MARCO Interaction, with Reversal by Plasma Gelsolin.

    PubMed

    Ordija, Christine M; Chiou, Terry Ting-Yu; Yang, Zhiping; Deloid, Glen M; de Oliveira Valdo, Melina; Wang, Zhi; Bedugnis, Alice; Noah, Terry L; Jones, Samuel; Koziel, Henry; Kobzik, Lester

    2017-04-06

    Lung injury can release intracellular actin into the alveolar milieu, and is also associated with increased susceptibility to secondary infections. We investigated the effect of free (extracellular) actin on lung macrophage host defense functions. Western blot analysis demonstrated free actin release into the lung lavage fluids of mouse models of ozone injury, influenza infection and secondary pneumococcal pneumonia, and in samples from patients following burn and inhalation injury. Using levels comparable to those observed in lung injury, we found that free actin markedly inhibited murine lung macrophage binding and uptake in vitro of S. pneumoniae, S. aureus and E. coli e.g., S. pneumoniae, mean % inhibition, actin vs vehicle: 85 ± 0.3 (SD), n = 22, p <.001). Similar effects were observed on the ability of primary human macrophages to bind and ingest fluorescent S. aureus (~75 % inhibition). Plasma gelsolin (pGSN), a protein that functions to bind and cleave actin, restored bacterial binding and uptake by both murine and human macrophages. Scavenger receptor inhibitors reduced binding of fluorescent actin by murine macrophages (fluorescence index (x 10-3) after incubation with vehicle, actin, or actin + polyinosinic acid, respectively: 0.8 ± 0.7, 101.7 ± 50.7, 52.7 ± 16.9, n = 5-6, p < 0.05). In addition, actin binding was reduced in a MARCO / SR-AI/II deficient cell line and by normal AMs obtained from MARCO -/- mice. After release from injured cells during lung injury, free actin likely contributes to impaired host defense by blocking scavenger receptor binding of bacteria. This mechanism for increased risk of secondary infections after lung injury or inflammation may represent another target for therapeutic intervention with pGSN.

  1. Scavenging behavior of Lynx rufus on human remains during the winter months of Southeast Texas.

    PubMed

    Rippley, Angela; Larison, Nicole C; Moss, Kathryn E; Kelly, Jeffrey D; Bytheway, Joan A

    2012-05-01

    Animal-scavenging alterations on human remains can be mistaken as human criminal activity. A 32-day study, documenting animal scavenging on a human cadaver, was conducted at the Southeast Texas Applied Forensic Science facility, Sam Houston State University, Huntsville, Texas. A Stealth Cam Rogue IR was positioned near the cadaver to capture scavenging activity. An atypical scavenger, the bobcat, Lynx rufus, was recorded feeding on the cadaver. Scavenging by bobcats on human remains is not a predominant behavior and has minimal documentation. Scavenging behaviors and destruction of body tissues were analyzed. Results show that the bobcat did not feed on areas of the body that it does for other large animal carcasses. Results also show the bobcat feeds similarly during peak and nonpeak hours. Understanding the destruction of human tissue and covering of the body with leaf debris may aid forensic anthropologists and pathologists in differentiating between nefarious human activity and animal scavenging. © 2012 American Academy of Forensic Sciences.

  2. Type I macrophage scavenger receptor contains α-helical and collagen-like coiled coils

    NASA Astrophysics Data System (ADS)

    Kodama, Tatsuhiko; Freeman, Mason; Rohrer, Lucia; Zabrecky, James; Matsudaira, Paul; Krieger, Monty

    1990-02-01

    The macrophage scavenger receptor is a trimeric membrane glycoprotein with unusual ligand-binding properties which has been implicated in the development of atherosclerosis. The trimeric structure of the bovine type I scavenger receptor, deduced by complementary DNA cloning, contains three extracellular C-terminal cysteine-rich domains connected to the transmembrane domain by a long fibrous stalk. This stalk structure, composed of an a-helical coiled coil and a collagen-like triple helix, has not previously been observed in an integral membrane protein.

  3. Scavenger Receptor CD36 Directs Nonclassical Monocyte Patrolling Along the Endothelium During Early Atherogenesis.

    PubMed

    Marcovecchio, Paola M; Thomas, Graham D; Mikulski, Zbigniew; Ehinger, Erik; Mueller, Karin A L; Blatchley, Amy; Wu, Runpei; Miller, Yury I; Nguyen, Anh Tram; Taylor, Angela M; McNamara, Coleen A; Ley, Klaus; Hedrick, Catherine C

    2017-09-21

    Nonclassical monocytes (NCM) function to maintain vascular homeostasis by crawling or patrolling along the vessel wall. This subset of monocytes responds to viruses, tumor cells, and other pathogens to aid in protection of the host. In this study, we wished to determine how early atherogenesis impacts NCM patrolling in the vasculature. To study the role of NCM in early atherogenesis, we quantified the patrolling behaviors of NCM in ApoE(-/-) (apolipoprotein E) and C57BL/6J mice fed a Western diet. Using intravital imaging, we found that NCM from Western diet-fed mice display a 4-fold increase in patrolling activity within large peripheral blood vessels. Both human and mouse NCM preferentially engulfed OxLDL (oxidized low-density lipoprotein) in the vasculature, and we observed that OxLDL selectively induced NCM patrolling in vivo. Induction of patrolling during early atherogenesis required scavenger receptor CD36, as CD36(-/-) mice revealed a significant reduction in patrolling activity along the femoral vasculature. Mechanistically, we found that CD36-regulated patrolling was mediated by a SFK (src family kinase) through DAP12 (DNAX activating protein of 12KDa) adaptor protein. Our studies show a novel pathway for induction of NCM patrolling along the vascular wall during early atherogenesis. Mice fed a Western diet showed increased NCM patrolling activity with a concurrent increase in SFK phosphorylation. This patrolling activity was lost in the absence of either CD36 or DAP12. These data suggest that NCM function in an atheroprotective manner through sensing and responding to oxidized lipoprotein moieties via scavenger receptor engagement during early atherogenesis. © 2017 American Heart Association, Inc.

  4. Rare variant in scavenger receptor BI raises HDL cholesterol and increases risk of coronary heart disease

    PubMed Central

    Zanoni, Paolo; Khetarpal, Sumeet A.; Larach, Daniel B.; Hancock-Cerutti, William F.; Millar, John S.; Cuchel, Marina; DerOhannessian, Stephanie; Kontush, Anatol; Surendran, Praveen; Saleheen, Danish; Trompet, Stella; Jukema, J. Wouter; De Craen, Anton; Deloukas, Panos; Sattar, Naveed; Ford, Ian; Packard, Chris; Majumder, Abdullah al Shafi; Alam, Dewan S.; Di Angelantonio, Emanuele; Abecasis, Goncalo; Chowdhury, Rajiv; Erdmann, Jeanette; Nordestgaard, Børge G.; Nielsen, Sune F.; Tybjærg-Hansen, Anne; Schmidt, Ruth Frikke; Kuulasmaa, Kari; Liu, Dajiang J.; Perola, Markus; Blankenberg, Stefan; Salomaa, Veikko; Männistö, Satu; Amouyel, Philippe; Arveiler, Dominique; Ferrieres, Jean; Müller-Nurasyid, Martina; Ferrario, Marco; Kee, Frank; Willer, Cristen J.; Samani, Nilesh; Schunkert, Heribert; Butterworth, Adam S.; Howson, Joanna M. M.; Peloso, Gina M.; Stitziel, Nathan O.; Danesh, John; Kathiresan, Sekar; Rader, Daniel J.

    2016-01-01

    Scavenger receptor BI (SR-BI) is the major receptor for high-density lipoprotein (HDL) cholesterol (HDL-C). In humans, high amounts of HDL-C in plasma are associated with a lower risk of coronary heart disease (CHD). Mice that have depleted Scarb1 (SR-BI knockout mice) have markedly elevated HDL-C levels but, paradoxically, increased atherosclerosis. The impact of SR-BI on HDL metabolism and CHD risk in humans remains unclear. Through targeted sequencing of coding regions of lipid-modifying genes in 328 individuals with extremely high plasma HDL-C levels, we identified a homozygote for a loss-of-function variant, in which leucine replaces proline 376 (P376L), in SCARB1, the gene encoding SR-BI. The P376L variant impairs posttranslational processing of SR-BI and abrogates selective HDL cholesterol uptake in transfected cells, in hepatocyte-like cells derived from induced pluripotent stem cells from the homozygous subject, and in mice. Large population-based studies revealed that subjects who are heterozygous carriers of the P376L variant have significantly increased levels of plasma HDL-C. P376L carriers have a profound HDL-related phenotype and an increased risk of CHD (odds ratio = 1.79, which is statistically significant). PMID:26965621

  5. Rare variant in scavenger receptor BI raises HDL cholesterol and increases risk of coronary heart disease.

    PubMed

    Zanoni, Paolo; Khetarpal, Sumeet A; Larach, Daniel B; Hancock-Cerutti, William F; Millar, John S; Cuchel, Marina; DerOhannessian, Stephanie; Kontush, Anatol; Surendran, Praveen; Saleheen, Danish; Trompet, Stella; Jukema, J Wouter; De Craen, Anton; Deloukas, Panos; Sattar, Naveed; Ford, Ian; Packard, Chris; Majumder, Abdullah al Shafi; Alam, Dewan S; Di Angelantonio, Emanuele; Abecasis, Goncalo; Chowdhury, Rajiv; Erdmann, Jeanette; Nordestgaard, Børge G; Nielsen, Sune F; Tybjærg-Hansen, Anne; Schmidt, Ruth Frikke; Kuulasmaa, Kari; Liu, Dajiang J; Perola, Markus; Blankenberg, Stefan; Salomaa, Veikko; Männistö, Satu; Amouyel, Philippe; Arveiler, Dominique; Ferrieres, Jean; Müller-Nurasyid, Martina; Ferrario, Marco; Kee, Frank; Willer, Cristen J; Samani, Nilesh; Schunkert, Heribert; Butterworth, Adam S; Howson, Joanna M M; Peloso, Gina M; Stitziel, Nathan O; Danesh, John; Kathiresan, Sekar; Rader, Daniel J

    2016-03-11

    Scavenger receptor BI (SR-BI) is the major receptor for high-density lipoprotein (HDL) cholesterol (HDL-C). In humans, high amounts of HDL-C in plasma are associated with a lower risk of coronary heart disease (CHD). Mice that have depleted Scarb1 (SR-BI knockout mice) have markedly elevated HDL-C levels but, paradoxically, increased atherosclerosis. The impact of SR-BI on HDL metabolism and CHD risk in humans remains unclear. Through targeted sequencing of coding regions of lipid-modifying genes in 328 individuals with extremely high plasma HDL-C levels, we identified a homozygote for a loss-of-function variant, in which leucine replaces proline 376 (P376L), in SCARB1, the gene encoding SR-BI. The P376L variant impairs posttranslational processing of SR-BI and abrogates selective HDL cholesterol uptake in transfected cells, in hepatocyte-like cells derived from induced pluripotent stem cells from the homozygous subject, and in mice. Large population-based studies revealed that subjects who are heterozygous carriers of the P376L variant have significantly increased levels of plasma HDL-C. P376L carriers have a profound HDL-related phenotype and an increased risk of CHD (odds ratio = 1.79, which is statistically significant).

  6. Scavenger Receptor C-Type Lectin Binds to the Leukocyte Cell Surface Glycan Lewis By a Novel Mechanism

    SciTech Connect

    Feinberg, H.; Taylor, M.E.; Weis, W.I.; /Stanford U., Med. School /Imperial Coll., London

    2007-07-10

    The scavenger receptor C-type lectin (SRCL) is unique in the family of class A scavenger receptors, because in addition to binding sites for oxidized lipoproteins it also contains a C-type carbohydrate-recognition domain (CRD) that interacts with specific glycans. Both human and mouse SRCL are highly specific for the Lewis(x) trisaccharide, which is commonly found on the surfaces of leukocytes and some tumor cells. Structural analysis of the CRD of mouse SRCL in complex with Lewis(x) and mutagenesis show the basis for this specificity. The interaction between mouse SRCL and Lewis(x) is analogous to the way that selectins and DC-SIGN bind to related fucosylated glycans, but the mechanism of the interaction is novel, because it is based on a primary galactose-binding site similar to the binding site in the asialoglycoprotein receptor. Crystals of the human receptor lacking bound calcium ions reveal an alternative conformation in which a glycan ligand would be released during receptor-mediated endocytosis.

  7. Regulation of platelet function by class B scavenger receptors in hyperlipidemia

    PubMed Central

    Zimman, Alejandro; Podrez, Eugene A.

    2010-01-01

    Platelets constitutively express class B scavenger receptors CD36 and SR-BI, two closely related pattern recognition receptors best known for their roles in lipoprotein and lipid metabolism. The biological role of scavenger receptors in platelets is poorly understood. However, in vitro and in vivo data suggest that class B scavenger receptors modulate platelet function and contribute significantly to thrombosis by sensing pathological or physiological ligands, inducing prothrombotic signaling, and increasing platelet reactivity. Platelet CD36 recognizes a novel family of endogenous oxidized choline phospholipids that accumulate in plasma of hyperlipidemic mice and in plasma of subjects with low HDL levels. This interaction leads to the activation of specific signaling pathways and promotes platelet activation and thrombosis. Platelet SR-BI, on the other hand, plays a critical role in the induction of platelet hyper-reactivity and accelerated thrombosis in conditions associated with increased platelet cholesterol content. Intriguingly, oxidized HDL, aSR-BI ligand, can suppress platelet function. These recent findings demonstrate that platelet class B scavenger receptors play roles in thrombosis in dyslipidemia and may contribute to acute cardiovascular events in vivo in hypercholesterolemia. PMID:21071700

  8. Exploiting scavenger receptors in cancer immunotherapy: Lessons from CD5 and SR-B1.

    PubMed

    Vasquez, Marcos; Simões, Inês; Consuegra-Fernández, Marta; Aranda, Fernando; Lozano, Francisco; Berraondo, Pedro

    2017-07-01

    Scavenger receptors (SRs) are structurally heterogeneous cell surface receptors characterized by their capacity to remove extraneous or modified self-macromolecules from circulation, thus avoiding the accumulation of noxious agents in the extracellular space. This scavenging activity makes SRs important molecules for host defense and homeostasis. In turn, SRs keep the activation of the steady-state immune response in check, and participate as co-receptors in the priming of the effector immune responses when the macromolecules are associated with a threat that might compromise host homeostasis. Therefore, SRs built up sophisticated sensor mechanisms controlling the immune system, which may be exploited to develop novel drugs for cancer immunotherapy. In this review, we focus on the regulation of the anti-tumor immune response by two paradigmatic SRs: the lymphocyte receptor CD5 and the more broadly distributed scavenger receptor class B type 1 (SR-B1). Cancer immunity can be boosted by blockade of SRs working as immune checkpoint inhibitors (CD5) and/or by proper engagement of SRs working as innate danger receptor (SR-B1). Thus, these receptors illustrate both the complexity of targeting SRs in cancer immunotherapy and also the opportunities offered by such an approach. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Scavenger Receptor MARCO Orchestrates Early Defenses and Contributes to Fungal Containment during Cryptococcal Infection.

    PubMed

    Xu, Jintao; Flaczyk, Adam; Neal, Lori M; Fa, Zhenzong; Eastman, Alison J; Malachowski, Antoni N; Cheng, Daphne; Moore, Bethany B; Curtis, Jeffrey L; Osterholzer, John J; Olszewski, Michal A

    2017-03-15

    The scavenger receptor macrophage receptor with collagenous structure (MARCO) promotes protective innate immunity against bacterial and parasitic infections; however, its role in host immunity against fungal pathogens, including the major human opportunistic fungal pathogen Cryptococcus neoformans, remains unknown. Using a mouse model of C. neoformans infection, we demonstrated that MARCO deficiency leads to impaired fungal control during the afferent phase of cryptococcal infection. Diminished fungal containment in MARCO(-/-) mice was accompanied by impaired recruitment of Ly6C(high) monocytes and monocyte-derived dendritic cells (moDC) and lower moDC costimulatory maturation. The reduced recruitment and activation of mononuclear phagocytes in MARCO(-/-) mice was linked to diminished early expression of IFN-γ along with profound suppression of CCL2 and CCL7 chemokines, providing evidence for roles of MARCO in activation of the CCR2 axis during C. neoformans infection. Lastly, we found that MARCO was involved in C. neoformans phagocytosis by resident pulmonary macrophages and DC. We conclude that MARCO facilitates early interactions between C. neoformans and lung-resident cells and promotes the production of CCR2 ligands. In turn, this contributes to a more robust recruitment and activation of moDC that opposes rapid fungal expansion during the afferent phase of cryptococcal infection.

  10. Cellular Recognition and Trafficking of Amorphous Silica Nanoparticles by Macrophage Scavenger Receptor A

    SciTech Connect

    Orr, Galya; Chrisler, William B.; Cassens, Kaylyn J.; Tan, Ruimin; Tarasevich, Barbara J.; Markillie, Lye Meng; Zangar, Richard C.; Thrall, Brian D.

    2011-09-01

    The internalization of engineered nanoparticles (ENPs) into cells is known to involve active transport mechanisms, yet the precise biological molecules involved are poorly understood. We demonstrate that the uptake of amorphous silica ENPs (92 nm) by macrophage cells is strongly inhibited by silencing expression of scavenger receptor A (SR-A). In addition, ENP uptake is augmented by introducing SR-A expression into human cells that are normally non-phagocytic. Confocal fluorescent microscopy analyses show that the majority of single or small clusters of silica ENPs co-localize intracellularly with SR-A and are internalized through a pathway characteristic of clathrin-dependent endocytosis. In contrast, larger silica NP agglomerates (>500 nm) are poorly co-localized with the receptor, suggesting independent trafficking or internalization pathways are involved. SR-A silencing also caused decreased cellular secretion of pro-inflammatory cytokines in response to silica ENPs. As SR-A is expressed in macrophages throughout the reticulo-endothelial system, this pathway is likely an important determinant of the biodistribution of, and cellular response to ENPs.

  11. Hydroxyl radical scavengers inhibit human lectin-dependent cellular cytotoxicity.

    PubMed

    Melinn, M; McLaughlin, H

    1986-06-01

    The role of oxygen-derived free radicals (ODFR) in lectin-dependent cellular cytotoxicity (LDCC) in humans was investigated. The hydroxyl radical traps thiourea, methanol, ethanol and phenol were effective in inhibiting LDCC, as was DABCO, a singlet oxygen quencher. The proposed pathway of hydroxyl radical production in living cells is either an iron catalysed Haber-Weiss reaction or a Fenton reaction. The effect of inhibitors of these pathways was investigated. The superoxide anion scavengers superoxide dismutase, ferricytochrome c and Tiron were without effect. It was shown that Tiron inhibits the lucigenin-amplified chemiluminescence produced by the action of xanthine oxidase, and also the lucigenin-amplified chemiluminescence produced by activated PMN, suggesting that this agent (Tiron) scavenges intracellular superoxide anion. Catalase gave slight inhibition of LDCC only. The ferric iron chelator desferrioxamine gave no protection of the target cells, while the ferrous chelator, 1,10-phenanthroline, inhibited LDCC and partially prevented the detection of hydroxyl radicals generated by the Fe2+-H2O2 system. Cibacron blue, an agent that inhibits NAD(P)H linked enzymes, also inhibited LDCC. The cyclo-oxygenase inhibitors indomethacin and salicylate were without effect, while the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) inhibited cytolysis. None of the LDCC inhibitors was cytotoxic to the effector cells or to the target cells, neither did they inhibit lymphocyte-target binding. The findings would suggest that hydroxyl radicals have a role to play in human T-cell mediated cytolysis, either as the active lytic agent or as an epiphenomenon.

  12. The Role of Macrophage Class A Scavenger Receptors in a Laser-Induced Murine Choroidal Neovascularization Model

    PubMed Central

    Jawad, Shayma; Liu, Baoying; Li, Zhiyu; Katamay, Robert; Campos, Mercedes; Wei, Lai; Sen, H. Nida; Ling, Diamond; Martinez Estrada, Fernando; Amaral, Juan; Chan, Chi-Chao; Fariss, Robert; Gordon, Siamon; Nussenblatt, Robert B.

    2013-01-01

    Purpose. Laser-induced choroidal neovascularization (CNV) is a widely used model to mimic many features of CNV resulting from wet AMD. Macrophages have been implicated in the pathogenesis of AMD. Class A scavenger receptors, scavenger receptor-A (SR-A) and macrophage receptor with collagenous domain (MARCO), are expressed on macrophages and are associated with macrophage function. The goal of this study is to examine the role of macrophage scavenger receptors in immune cell recruitment and the formation of CNV. Methods. Laser photocoagulation was performed in wild-type and knockout mice with deletion of SR-A (SR-A−/−), MARCO (MARCO−/−), or both SR-A and MARCO double knockout (DKO). Immune cell recruitment at different time points and CNV lesions at 14 days after laser treatment were evaluated through immunostaining and confocal microscopy. Microarray analysis was performed in eyes 1 day after laser injury. Results. Wild-type eyes showed higher chemokine/receptor expression compared with knockout eyes after laser injury. Scavenger receptor deficiency markedly impaired the recruitment of neutrophils and macrophages to CNV lesions at 1- and 3-days post laser injury, respectively. Significantly reduced CNV volumes were found in the eyes from scavenger receptor knockout mice compared with wild-type mice. Conclusions. The deficiency of scavenger receptors impairs the formation of CNV and immune cell recruitment. Our findings suggest a potential role for scavenger receptors in contributing to CNV formation and inflammation in AMD. PMID:23927892

  13. Ferric human neuroglobin scavenges superoxide to form oxy adduct.

    PubMed

    Yamashita, Taku; Hafsi, Leila; Masuda, Eri; Tsujino, Hirofumi; Uno, Tadayuki

    2014-01-01

    Neuroglobin (Ngb) is the third member of the vertebrate globin family, and the structure was solved as a typical globin fold with a b-type heme. Although it has been proposed that Ngb could be involved in neuroprotection against oxidative stress, the protective mechanism has not been fully identified yet. In order to clarify functions under hypoxic condition, in this study, we focused on the scavenger activity of human Ngb (hNgb) against superoxide. The activity of hNgb for superoxide was evaluated to be 7.4 µM for IC50, the half maximal inhibitory concentration. The result indicates that hNgb can be an anti-oxidant, and the value was almost the same as that of ascorbic acid. In addition, we characterized oxidation states of a heme iron in superoxide-treated hNgb with spectroscopic measurements. Superoxide-treated hNgb in the ferric form was readily converted to the oxygenated ferrous form, and the result suggested that ferric hNgb could scavenge superoxide by change of an oxidation state in a heme iron. Moreover, mutational experiments were performed, and the each variant mutated at 46 and 55 positions suggested a disulfide bond between Cys46 and Cys55 could be essential to be sensors for oxidative stress with the direct binding of superoxide. As a consequence, we concluded that redox changes of the heme iron and the disulfide bond could regulate neuroprotective functions of hNgb, and it suggests that hNgb can afford protection against hypoxic and ischemic stress in the brain.

  14. Scavenger receptor B1 facilitates macrophage uptake of silver nanoparticles and cellular activation

    NASA Astrophysics Data System (ADS)

    Aldossari, Abdullah A.; Shannahan, Jonathan H.; Podila, Ramakrishna; Brown, Jared M.

    2015-07-01

    Due to increased use of silver nanoparticles (AgNPs) for their antimicrobial activity, concerns have risen regarding potential adverse human health effects. Scavenger receptor B1 (SR-B1), a major receptor for high-density lipoprotein (HDL), is expressed by macrophages and has also been reported to play a role in recognition of negatively charged particles. We, therefore, hypothesized that SR-B1 mediates macrophage uptake of AgNPs and inflammatory activation. To test this hypothesis, we exposed a mouse macrophage cell line RAW264.7 (RAW) and bone marrow-derived macrophages (BMDM) to 20 nm citrate-suspended AgNPs. To verify the role of the SR-B1 receptor, we utilized a SR-B1 inhibitor (Blt2). In vitro studies demonstrated uptake of AgNPs and HDL-coated AgNPs by macrophages which were significantly reduced following pretreatment with Blt2. Inflammatory cytokine arrays revealed that macrophages exposed to AgNPs up-regulated expression of Tnf- α, Oncostatin m (OSM), Ccl4, Il17f, Ccl7, and Ccl2, whereas Il16 was found to be down-regulated. Macrophage activation was observed following AgNP and HDL-coated AgNP exposure as measured by OSM protein production and increased surface expression of CD86. These markers of activation were reduced with Blt2 pretreatment. The in vitro findings were confirmed in vivo through pulmonary instillation of AgNPs in mice. Pulmonary instillation of AgNPs resulted in a recruitment of inflammatory cells that were reduced in SR-B1-deficient mice or following Blt2 pretreatment. This study suggests that SR-B1 plays a major role in cellular recognition of AgNPs and the induction of cell responses that could contribute to inflammation caused by AgNP exposure.

  15. Cooperation between hepatic cholesteryl ester hydrolase and scavenger receptor BI for hydrolysis of HDL-CE.

    PubMed

    Yuan, Quan; Bie, Jinghua; Wang, Jing; Ghosh, Siddhartha S; Ghosh, Shobha

    2013-11-01

    Liver is the sole organ responsible for the final elimination of cholesterol from the body either as biliary cholesterol or bile acids. High density lipoprotein (HDL)-derived cholesterol is the major source of biliary sterols and represents a mechanism for the removal of cholesterol from peripheral tissues including artery wall-associated macrophage foam cells. Via selective uptake through scavenger receptor BI (SR-BI), HDL-cholesterol is thought to be directly secreted into bile, and HDL cholesteryl esters (HDL-CEs) enter the hepatic metabolic pool and need to be hydrolyzed prior to conversion to bile acids. However, the identity of hepatic CE hydrolase (CEH) as well as the role of SR-BI in bile acid synthesis remains elusive. In this study we examined the role of human hepatic CEH (CES1) in facilitating hydrolysis of SR-BI-delivered HDL-CEs. Over-expression of CEH led to increased hydrolysis of HDL-[³H]CE in primary hepatocytes and SR-BI expression was required for this process. Intracellular CEH associated with BODIPY-CE delivered by selective uptake via SR-BI. CEH and SR-BI expression enhanced the movement of [³H]label from HDL-[³H]CE to bile acids in vitro and in vivo. Taken together, these studies demonstrate that SR-BI-delivered HDL-CEs are hydrolyzed by hepatic CEH and utilized for bile acid synthesis.

  16. Carbohydrate composition of amphiphilic macromolecules influences physicochemical properties and binding to atherogenic scavenger receptor A.

    PubMed

    Hehir, Sarah; Plourde, Nicole M; Gu, Li; Poree, Dawanne E; Welsh, William J; Moghe, Prabhas V; Uhrich, Kathryn E

    2012-11-01

    Amphiphilic macromolecules (AMs) based on carbohydrate domains functionalized with poly(ethylene glycol) can inhibit the uptake of oxidized low density lipoprotein (oxLDL) mediated by scavenger receptor A (SR-A) and counteract foam cell formation, the characteristic "atherosclerotic" phenotype. A series of AMs was prepared by altering the carbohydrate chemistry to evaluate the influence of backbone architecture on the physicochemical and biological properties. Upon evaluating the degree of polymer-based inhibition of oxLDL uptake in human embryonic kidney cells expressing SR-A, two AMs (2a and 2c) were found to have the most efficacy. Molecular modeling and docking studies show that these same AMs have the most favorable binding energies and most close interactions with the molecular model of the SR-A collagen-like domain. Thus, minor changes in the AMs' architecture can significantly affect the physicochemical properties and inhibition of oxLDL uptake. These insights can be critical for designing optimal AM-based therapeutics for the management of cardiovascular disease. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Carbohydrate Composition of Amphiphilic Macromolecules Influences Physicochemical Properties and Binding to Atherogenic Scavenger Receptor A

    PubMed Central

    Hehir, Sarah; Plourde, Nicole M.; Gu, Li; Poree, Dawanne E.; Welsh, William J.; Moghe, Prabhas V.; Uhrich, Kathryn E.

    2012-01-01

    Amphiphilic macromolecules (AMs) based on carbohydrate domains functionalized with poly(ethylene glycol) can inhibit the uptake of oxidized low density lipoprotein (oxLDL) mediated by scavenger receptor A (SR-A) and counteract foam cell formation, the characteristic “atherosclerotic” phenotype. A series of AMs were prepared by altering the carbohydrate chemistry to evaluate the influence of backbone architecture on the physicochemical and biological properties. Upon evaluating the degree of polymer-based inhibition of oxLDL uptake in human embryonic kidney cells expressing SR-A, two AMs (2a and 2c) were found to have the most efficacy. Molecular modeling and docking studies show that these same AMs have the most favorable binding energies and most close interactions with the molecular model of SR-A collagen-like domain. Thus, minor changes in the AMs architecture can significantly affect the physicochemical properties and inhibition of oxLDL uptake. These insights can be critical for designing optimal AM-based therapeutics for management of cardiovascular disease. PMID:22835678

  18. Malondialdehyde-acetaldehyde (MAA) adducted proteins bind to scavenger receptor A in airway epithelial cells

    PubMed Central

    Berger, John P.; Simet, Samantha M.; DeVasure, Jane M.; Boten, Jessica A.; Sweeter, Jenea M.; Kharbanda, Kusum K.; Sisson, Joseph H.; Wyatt, Todd A.

    2014-01-01

    Co-exposure to cigarette smoke and ethanol generates malondialdehyde and acetaldehyde, which can subsequently lead to the formation of aldehyde-adducted proteins. We have previously shown that exposure of bronchial epithelial cells to malondialdehyde-acetaldehyde (MAA) adducted protein increases protein kinase C (PKC) activity and proinflammatory cytokine release. A specific ligand to scavenger receptor A (SRA), fucoidan, blocks this effect. We hypothesized that MAA-adducted protein binds to bronchial epithelial cells via SRA. Human bronchial epithelial cells (BEAS-2B) were exposed to MAA-adducted protein (either bovine serum albumin [BSA-MAA] or surfactant protein D [SPD-MAA]) and SRA examined using confocal microscopy, fluorescent activated cell sorting (FACS), and immunoprecipitation. Differentiated mouse tracheal epithelial cells (MTEC) cultured by air-liquid interface were assayed for MAA-stimulated PKC activity and keratinocyte-derived chemokine (KC) release. Specific cell surface membrane dye co-localized with upregulated SRA after exposure to MAA for 3–7 min and subsided by 20 min. Likewise, MAA-adducted protein co-localized to SRA from 3–7 min with a subsequent internalization of MAA by 10 min. These results were confirmed using FACS analysis and revealed a reduced mean fluorescence of SRA after 3 min. Furthermore, increased amounts of MAA-adducted protein could be detected by Western blot in immunoprecipitated SRA samples after 3 min treatment with MAA. MAA stimulated PKCε-mediated KC release in wild type, but not SRA knockout mice. These data demonstrate that aldehyde-adducted proteins in the lungs rapidly bind to SRA and internalize this receptor prior to the MAA-adducted protein stimulation of PKC-dependent inflammatory cytokine release in airway epithelium. PMID:24880893

  19. Malondialdehyde-acetaldehyde (MAA) adducted proteins bind to scavenger receptor A in airway epithelial cells.

    PubMed

    Berger, John P; Simet, Samantha M; DeVasure, Jane M; Boten, Jessica A; Sweeter, Jenea M; Kharbanda, Kusum K; Sisson, Joseph H; Wyatt, Todd A

    2014-08-01

    Co-exposure to cigarette smoke and ethanol generates malondialdehyde and acetaldehyde, which can subsequently lead to the formation of aldehyde-adducted proteins. We have previously shown that exposure of bronchial epithelial cells to malondialdehyde-acetaldehyde (MAA) adducted protein increases protein kinase C (PKC) activity and proinflammatory cytokine release. A specific ligand to scavenger receptor A (SRA), fucoidan, blocks this effect. We hypothesized that MAA-adducted protein binds to bronchial epithelial cells via SRA. Human bronchial epithelial cells (BEAS-2B) were exposed to MAA-adducted protein (either bovine serum albumin [BSA-MAA] or surfactant protein D [SPD-MAA]) and SRA examined using confocal microscopy, fluorescent activated cell sorting (FACS), and immunoprecipitation. Differentiated mouse tracheal epithelial cells (MTEC) cultured by air-liquid interface were assayed for MAA-stimulated PKC activity and keratinocyte-derived chemokine (KC) release. Specific cell surface membrane dye co-localized with upregulated SRA after exposure to MAA for 3-7 min and subsided by 20 min. Likewise, MAA-adducted protein co-localized to SRA from 3 to 7 min with a subsequent internalization of MAA by 10 min. These results were confirmed using FACS analysis and revealed a reduced mean fluorescence of SRA after 3 min. Furthermore, increased amounts of MAA-adducted protein could be detected by Western blot in immunoprecipitated SRA samples after 3 min treatment with MAA. MAA stimulated PKCε-mediated KC release in wild type, but not SRA knockout mice. These data demonstrate that aldehyde-adducted proteins in the lungs rapidly bind to SRA and internalize this receptor prior to the MAA-adducted protein stimulation of PKC-dependent inflammatory cytokine release in airway epithelium.

  20. Scavenger receptor function of mouse Fcγ receptor III contributes to progression of atherosclerosis in apolipoprotein E hyperlipidemic mice.

    PubMed

    Zhu, Xinmei; Ng, Hang Pong; Lai, Yen-Chun; Craigo, Jodi K; Nagilla, Pruthvi S; Raghani, Pooja; Nagarajan, Shanmugam

    2014-09-01

    Recent studies showed loss of CD36 or scavenger receptor-AI/II (SR-A) does not ameliorate atherosclerosis in a hyperlipidemic mouse model, suggesting receptors other than CD36 and SR-A may also contribute to atherosclerosis. In this report, we show that apolipoprotein E (apoE)-CD16 double knockout (DKO; apoE-CD16 DKO) mice have reduced atherosclerotic lesions compared with apoE knockout mice. In vivo and in vitro foam cell analyses showed apoE-CD16 DKO macrophages accumulated less neutral lipids. Reduced foam cell formation in apoE-CD16 DKO mice is not due to change in expression of CD36, SR-A, and LOX-1. This led to a hypothesis that CD16 may have scavenger receptor activity. We presented evidence that a soluble form of recombinant mouse CD16 (sCD16) bound to malondialdehyde-modified low-density lipoprotein (MDALDL), and this binding is blocked by molar excess of MDA- modified BSA and anti-MDA mAbs, suggesting CD16 specifically recognizes MDA epitopes. Interestingly, sCD16 inhibited MDALDL binding to macrophage cell line, as well as soluble forms of recombinant mouse CD36, SR-A, and LOX-1, indicating CD16 can cross-block MDALDL binding to other scavenger receptors. Anti-CD16 mAb inhibited immune complex binding to sCD16, whereas it partially inhibited MDALDL binding to sCD16, suggesting MDALDL binding site may be in close proximity to the immune complex binding site in CD16. Loss of CD16 expression resulted in reduced levels of MDALDL-induced proinflammatory cytokine expression. Finally, CD16-deficient macrophages showed reduced MDALDL-induced Syk phosphorylation. Collectively, our findings suggest scavenger receptor activity of CD16 may, in part, contribute to the progression of atherosclerosis.

  1. Effect of cinnamon water extract on monocyte-to-macrophage differentiation and scavenger receptor activity

    PubMed Central

    2014-01-01

    Background Water soluble cinnamon extract has been shown to increase insulin sensitivity and modulate macrophage activation, a desirable trait for the management of obesity or atherosclerosis. Our present study investigated whether cinnamon water extract (CWE) may influence the differentiation of monocytes into macrophages and the activity of macrophage scavenger receptors, commonly observed in atherosclerotic lesions. Methods We investigated the effect of CWE on the expression of various surface markers and the uptake of acetylated low density lipoprotein (LDL) in phorbol-12-myristate-13-acetate (PMA)-stimulated THP-1 cells. The protein levels of PMA or macrophage-colony stimulating factor (M-CSF)-stimulated type 1 macrophage scavenger receptor (SRA) were analyzed. Finally, the role of extracellar signal-related kinase (ERK) 1/2 in SRA synthesis and the effect of CWE on PMA-stimulated ERK1/2 were determined. Results CWE inhibited the differentiation of monocyte by decreasing the expression of CD11b, CD36 and SRA and the uptake of acetyl LDL. CWE suppressed the upregulation of SRA by M-CSF and modulated ERK1/2 activity, which was required for PMA-induced SRA synthesis. Conclusions Our results demonstrate that CWE was able to interfere with monocyte differentiation and macrophage scavenger activity, indicating its potential in preventing the development of atherosclerotic lesions. PMID:24602512

  2. HlSRB, a Class B scavenger receptor, is key to the granulocyte-mediated microbial phagocytosis in ticks.

    PubMed

    Aung, Kyaw Min; Boldbaatar, Damdinsuren; Umemiya-Shirafuji, Rika; Liao, Min; Tsuji, Naotoshi; Xuenan, Xuan; Suzuki, Hiroshi; Kume, Aiko; Galay, Remil Linggatong; Tanaka, Tetsuya; Fujisaki, Kozo

    2012-01-01

    Ixodid ticks transmit various pathogens of deadly diseases to humans and animals. However, the specific molecule that functions in the recognition and control of pathogens inside ticks is not yet to be identified. Class B scavenger receptor CD36 (SRB) participates in internalization of apoptotic cells, certain bacterial and fungal pathogens, and modified low-density lipoproteins. Recently, we have reported on recombinant HlSRB, a 50-kDa protein with one hydrophobic SRB domain from the hard tick, Haemaphysalis longicornis. Here, we show that HlSRB plays vital roles in granulocyte-mediated phagocytosis to invading Escherichia coli and contributes to the first-line host defense against various pathogens. Data clearly revealed that granulocytes that up-regulated the expression of cell surface HlSRB are almost exclusively involved in hemocyte-mediated phagocytosis for E. coli in ticks, and post-transcriptional silencing of the HlSRB-specific gene ablated the granulocytes' ability to phagocytose E. coli and resulted in the mortality of ticks due to high bacteremia. This is the first report demonstrating that a scavenger receptor molecule contributes to hemocyte-mediated phagocytosis against exogenous pathogens, isolated and characterized from hematophagous arthropods.

  3. HlSRB, a Class B Scavenger Receptor, Is Key to the Granulocyte-Mediated Microbial Phagocytosis in Ticks

    PubMed Central

    Aung, Kyaw Min; Boldbaatar, Damdinsuren; Umemiya-Shirafuji, Rika; Liao, Min; Tsuji, Naotoshi; Xuenan, Xuan; Suzuki, Hiroshi; Kume, Aiko; Galay, Remil Linggatong; Tanaka, Tetsuya; Fujisaki, Kozo

    2012-01-01

    Ixodid ticks transmit various pathogens of deadly diseases to humans and animals. However, the specific molecule that functions in the recognition and control of pathogens inside ticks is not yet to be identified. Class B scavenger receptor CD36 (SRB) participates in internalization of apoptotic cells, certain bacterial and fungal pathogens, and modified low-density lipoproteins. Recently, we have reported on recombinant HlSRB, a 50-kDa protein with one hydrophobic SRB domain from the hard tick, Haemaphysalis longicornis. Here, we show that HlSRB plays vital roles in granulocyte-mediated phagocytosis to invading Escherichia coli and contributes to the first-line host defense against various pathogens. Data clearly revealed that granulocytes that up-regulated the expression of cell surface HlSRB are almost exclusively involved in hemocyte-mediated phagocytosis for E. coli in ticks, and post-transcriptional silencing of the HlSRB-specific gene ablated the granulocytes' ability to phagocytose E. coli and resulted in the mortality of ticks due to high bacteremia. This is the first report demonstrating that a scavenger receptor molecule contributes to hemocyte-mediated phagocytosis against exogenous pathogens, isolated and characterized from hematophagous arthropods. PMID:22479406

  4. Ionizing Radiation Induces Macrophage Foam Cell Formation and Aggregation Through JNK-Dependent Activation of CD36 Scavenger Receptors

    SciTech Connect

    Katayama, Ikuo; Hotokezaka, Yuka; Matsuyama, Toshifumi; Sumi, Tadateru; Nakamura, Takashi

    2008-03-01

    Purpose: Irradiated arteries of cancer patients can be associated with atherosclerosis-like lesions containing cholesterol-laden macrophages (foam cells). Endothelial cell damage by irradiation does not completely explain the foam cell formation. We investigated the possible underlying mechanisms for ionizing radiation (IR)-induced foam cell formation. Methods and Materials: Human peripheral blood monocytes were activated by macrophage colony-stimulating factor and then treated with varying doses of IR in vitro in the absence of endothelial cells. Scavenger receptor expression and foam cell formation of IR-treated macrophages were investigated in the presence or absence of oxidized low-density lipoprotein. We also assessed the importance of mitogen-activated protein kinase activity in the macrophage colony-stimulating factor-activated human monocytes (macrophages) for the foam cell formation. Results: We found that IR treatment of macrophage colony-stimulating factor-activated human peripheral blood monocytes resulted in the enhanced expression of CD36 scavenger receptors and that cholesterol accumulated in the irradiated macrophages with resultant foam cell formation in the presence of oxidized low-density lipoprotein. Furthermore, when cultured on collagen gels, human macrophages formed large foam cell aggregates in response to IR. Antibodies against CD36 inhibited the IR-induced foam cell formation and aggregation, indicating that the IR-induced foam cell formation and the subsequent aggregation are dependent on functional CD36. In addition, we found that IR of human macrophages resulted in c-Jun N-terminal kinase activation and that c-Jun N-terminal kinase inhibition suppressed IR-induced CD36 expression and the subsequent foam cell formation and aggregation. Conclusion: Taken together, these results suggest that IR-induced foam cell formation is mediated by c-Jun N-terminal kinase-dependent CD36 activation.

  5. The scavenger receptor SCARF1 mediates apoptotic cell clearance and prevents autoimmunity

    PubMed Central

    Ramirez-Ortiz, Zaida G.; Pendergraft, William F.; Prasad, Amit; Byrne, Michael H.; Iram, Tal; Blanchette, Christopher J.; Luster, Andrew D.; Hacohen, Nir; Khoury, Joseph El; Means, Terry K.

    2013-01-01

    Clearance of apoptotic cells is critical for control of tissue homeostasis however the full range of receptor(s) on phagocytes responsible for recognition of apoptotic cells remains to be identified. Here we show that dendritic cells (DCs), macrophages and endothelial cells use scavenger receptor type F family member 1 (SCARF1) to recognize and engulf apoptotic cells via C1q. Loss of SCARF1 impairs uptake of apoptotic cells. Consequently, in SCARF1-deficient mice, dying cells accumulate in tissues leading to a lupus-like disease with the spontaneous generation of autoantibodies to DNA-containing antigens, immune cell activation, dermatitis and nephritis. The discovery of SCARF1 interactions with C1q and apoptotic cells provides insights into molecular mechanisms involved in maintenance of tolerance and prevention of autoimmune disease. PMID:23892722

  6. Bismuth increases hydroxyl radical-scavenging activity of histamine H2-receptor antagonists.

    PubMed

    Kirkova, Margarita; Alexandrova, Albena; Yordanova, Neli

    2006-01-01

    The effects of histamine H2-receptor antagonists, alone or in a combination with bismuth, on *OH-provoked degradation of deoxyribose were studied. The histamine H2-receptor antagonists (cimetidine, ranitidine and roxatidine), themselves decreased the deoxyribose damage in Fenton-type systems. In combinations with bismuth, their inhibitory effect in Fenton system (Fe(III)/ascorbic acid + H2O2 was stronger. Moreover, unlike F(III) and Cu(II), which in the presence of ascorbic acid + H2O2 led to an increase in the *OH formation (deoxyribose damage), Bi(III) showed an opposite effect. The present results are interpreted in view of a better ( )OH scavenging activity of bismuth complexes of histamine H2-receptor antagonists as compared to that of the corresponding drugs. These findings might be one more explanation why bismuth salts, in combination with acid-reducing agents, are more effective anti-ulcer agents.

  7. Understanding molecular interactions between scavenger receptor A and its natural product inhibitors through molecular modeling studies.

    PubMed

    Pagare, Piyusha P; Zaidi, Saheem A; Zhang, Xiaomei; Li, Xia; Yu, Xiaofei; Wang, Xiang-Yang; Zhang, Yan

    2017-08-16

    Scavenger receptor A (SRA), as an immune regulator, has been shown to play important roles in lipid metabolism, cardiovascular diseases, and pathogen recognition. Several natural product inhibitors of SRA have been studied for their potential application in modulating SRA functions. To understand the binding mode of these inhibitors on SRA, we conducted systematic molecular modeling studies in order to identify putative binding domain(s) that may be responsible for their recognition to the receptor as well as their inhibitory activity. Treatment of SRA with one of the natural product inhibitors, rhein, led to significant dissociation of SRA oligomers to its trimer and dimer forms, which further supported our hypothesis on their putative mechanism of action. Such information is believed to shed light on design of more potent inhibitors for the receptor in order to develop potential therapeutics through immune system modulation. Published by Elsevier Inc.

  8. LOX-1: a male hormone-regulated scavenger receptor for atherosclerosis.

    PubMed

    Gao, Song; Geng, Yong-Jian

    2013-01-01

    Lectin-like oxidized LDL receptor-1 (LOX-1) is a unique scavenger receptor that mediates the binding and uptake of oxidized LDL (ox-LDL) by vascular cells during the development of atherosclerosis. Exposure to ox-LDL induces LOX-1 expression and LOX-1-dependent biological activities, such as activation of NF-κB, a nuclear factor important for signal transduction in inflammation. Accumulating evidence indicates that male hormones may regulate expression of LOX-1 and NF-κB as well as atherogenesis. Deficiency or low levels of the male hormone testosterone promote LOX-1 expression and NF-κB activation, while testosterone replacement therapy reduces the expression of LOX-1 and the activation of NF-κB, thereby protecting the arterial wall against atherogenesis.

  9. Development of contrast agents targeted to macrophage scavenger receptors for MRI of vascular inflammation

    PubMed Central

    Gustafsson, Björn; Youens, Susan; Louie, Angelique Y.

    2008-01-01

    Atherosclerosis is a leading cause of death in the U.S. Because there is a potential to prevent coronary and arterial diseases through early diagnosis, there is a need for methods to image arteries in the sub-clinical stage as well as clinical stage using various non-invasive techniques, including Magnetic Resonance Imaging (MRI). We describe a development of a novel MRI contrast agent targeted to plaques that will allow imaging of lesion formation. The contrast agent is directed to macrophages, one of the earliest components of developing plaques. Macrophages are labeled through the macrophage scavenger receptor A, a macrophage specific cell surface protein, using an MRI contrast agent derived from scavenger receptor ligands. We have synthesized and characterized these contrast agents with a range of relaxivities. In vitro studies show that the targeted contrast agent accumulates in macrophages and solution studies indicate that micromolar concentrations are sufficient to produce contrast in an MR image. Cell toxicity and initial biodistribution studies indicate low toxicity, no detectable retention in normal blood vessels, and rapid clearance from blood. The promising performance of this contrast agent targeted towards vascular inflammation opens doors to tracking of other inflammatory diseases such as tumor immunotherapy and transplant acceptance using MRI. PMID:16536488

  10. Scavenger Receptor C Mediates Phagocytosis of White Spot Syndrome Virus and Restricts Virus Proliferation in Shrimp

    PubMed Central

    Yang, Ming-Chong; Shi, Xiu-Zhen; Yang, Hui-Ting; Sun, Jie-Jie; Xu, Ling; Wang, Xian-Wei; Zhao, Xiao-Fan

    2016-01-01

    Scavenger receptors are an important class of pattern recognition receptors that play several important roles in host defense against pathogens. The class C scavenger receptors (SRCs) have only been identified in a few invertebrates, and their role in the immune response against viruses is seldom studied. In this study, we firstly identified an SRC from kuruma shrimp, Marsupenaeus japonicus, designated MjSRC, which was significantly upregulated after white spot syndrome virus (WSSV) challenge at the mRNA and protein levels in hemocytes. The quantity of WSSV increased in shrimp after knockdown of MjSRC, compared with the controls. Furthermore, overexpression of MjSRC led to enhanced WSSV elimination via phagocytosis by hemocytes. Pull-down and co-immunoprecipitation assays demonstrated the interaction between MjSRC and the WSSV envelope protein. Electron microscopy observation indicated that the colloidal gold-labeled extracellular domain of MjSRC was located on the outer surface of WSSV. MjSRC formed a trimer and was internalized into the cytoplasm after WSSV challenge, and the internalization was strongly inhibited after knockdown of Mjβ-arrestin2. Further studies found that Mjβ-arrestin2 interacted with the intracellular domain of MjSRC and induced the internalization of WSSV in a clathrin-dependent manner. WSSV were co-localized with lysosomes in hemocytes and the WSSV quantity in shrimp increased after injection of lysosome inhibitor, chloroquine. Collectively, this study demonstrated that MjSRC recognized WSSV via its extracellular domain and invoked hemocyte phagocytosis to restrict WSSV systemic infection. This is the first study to report an SRC as a pattern recognition receptor promoting phagocytosis of a virus. PMID:28027319

  11. Scavenger Receptor C Mediates Phagocytosis of White Spot Syndrome Virus and Restricts Virus Proliferation in Shrimp.

    PubMed

    Yang, Ming-Chong; Shi, Xiu-Zhen; Yang, Hui-Ting; Sun, Jie-Jie; Xu, Ling; Wang, Xian-Wei; Zhao, Xiao-Fan; Wang, Jin-Xing

    2016-12-01

    Scavenger receptors are an important class of pattern recognition receptors that play several important roles in host defense against pathogens. The class C scavenger receptors (SRCs) have only been identified in a few invertebrates, and their role in the immune response against viruses is seldom studied. In this study, we firstly identified an SRC from kuruma shrimp, Marsupenaeus japonicus, designated MjSRC, which was significantly upregulated after white spot syndrome virus (WSSV) challenge at the mRNA and protein levels in hemocytes. The quantity of WSSV increased in shrimp after knockdown of MjSRC, compared with the controls. Furthermore, overexpression of MjSRC led to enhanced WSSV elimination via phagocytosis by hemocytes. Pull-down and co-immunoprecipitation assays demonstrated the interaction between MjSRC and the WSSV envelope protein. Electron microscopy observation indicated that the colloidal gold-labeled extracellular domain of MjSRC was located on the outer surface of WSSV. MjSRC formed a trimer and was internalized into the cytoplasm after WSSV challenge, and the internalization was strongly inhibited after knockdown of Mjβ-arrestin2. Further studies found that Mjβ-arrestin2 interacted with the intracellular domain of MjSRC and induced the internalization of WSSV in a clathrin-dependent manner. WSSV were co-localized with lysosomes in hemocytes and the WSSV quantity in shrimp increased after injection of lysosome inhibitor, chloroquine. Collectively, this study demonstrated that MjSRC recognized WSSV via its extracellular domain and invoked hemocyte phagocytosis to restrict WSSV systemic infection. This is the first study to report an SRC as a pattern recognition receptor promoting phagocytosis of a virus.

  12. Efficient intracellular drug-targeting of macrophages using stealth liposomes directed to the hemoglobin scavenger receptor CD163.

    PubMed

    Etzerodt, Anders; Maniecki, Maciej Bogdan; Graversen, Jonas Heilskov; Møller, Holger Jon; Torchilin, Vladimir P; Moestrup, Søren Kragh

    2012-05-30

    The hemoglobin scavenger receptor CD163 is exclusively expressed in the monocytic lineage and preferentially in tissue resident macrophages of the M2 phenotype and in macrophages in sites of inflammation and tumor growth. In the present study we have designed liposomes specifically targeting CD163 by hydrophobic linkage of CD163-binding monoclonal antibodies to polyethylene glycol-coated liposomes ('stealth liposomes'). Targeting to the endocytic CD163 protein greatly increased the uptake of liposomes in CD163 transfected cells and macrophages as visualized by confocal microscopy and flow cytometry of cells exposed to CD163 targeting liposomes loaded with calcein. Strong cytotoxic effects were seen in CD163-expressing human monocytes by using the chemotherapeutic agent doxorubicin as cargo of the liposomes. In conclusion, the use of stealth liposomes modified to recognize CD163 is a potential way to target drugs to macrophages that support inflammatory and malignant processes. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Relationship between expression levels and atherogenesis in scavenger receptor class B, type I transgenics.

    PubMed

    Ueda, Y; Gong, E; Royer, L; Cooper, P N; Francone, O L; Rubin, E M

    2000-07-07

    Both in vitro and in vivo studies of scavenger receptor class B type I (SR-BI) have implicated it as a likely participant in the metabolism of HDL cholesterol. To investigate the effect of SR-BI on atherogenesis, we examined two lines of SR-BI transgenic mice with high (10-fold increases) and low (2-fold increases) SR-BI expression in an inbred mouse background hemizygous for a human apolipoprotein (apo) B transgene. Unlike non-HDL cholesterol levels that minimally differed in the various groups of animals, HDL cholesterol levels were inversely related to SR-BI expression. Mice with the low expression SR-BI transgene had a 50% reduction in HDL cholesterol, whereas the high expression SR-BI transgene was associated with 2-fold decreases in HDL cholesterol as well as dramatic alterations in HDL composition and size including the near absence of alpha-migrating particles as determined by two-dimensional electrophoresis. The low expression SR-BI/apo B transgenics had more than a 2-fold decrease in the development of diet-induced fatty streak lesions compared with the apo B transgenics (4448 +/- 1908 micrometer(2)/aorta to 10133 +/- 4035 micrometer (2)/aorta; p < 0.001), whereas the high expression SR-BI/apo B transgenics had an atherogenic response similar to that of the apo B transgenics (14692 +/- 7238 micrometer(2)/aorta) but 3-fold greater than the low SR-BI/apo B mice (p < 0.001). The prominent anti-atherogenic effect of moderate SR-BI expression provides in vivo support for the hypothesis that HDL functions to inhibit atherogenesis through its interactions with SR-BI in facilitating reverse cholesterol transport. The failure of the high SR-BI/apo B transgenics to have similar or even greater reductions in atherogenesis suggests that the changes resulting from extremely high SR-BI expression including dramatic changes in lipoproteins may have both pro- and anti-atherogenic consequences, illustrating the complexity of the relationship between SR-BI and

  14. Scavenging of hydroxyl radicals generated in human plasma following X-ray irradiation.

    PubMed

    Hosokawa, Yoichiro; Sano, Tomoaki

    2015-11-01

    There are various antioxidant materials that scavenge free radicals in human plasma. It is possible that the radical-scavenging function causes a radiation protective effect in humans. This study estimated the hydroxyl (OH) radical-scavenging activity induced by X-ray irradiation in human plasma. The test subjects included 111 volunteers (75 males and 36 females) ranging from 22 to 35 years old (average, 24.0). OH radicals generated in irradiated human plasma were measured by electron spin resonance (ESR). The relationships between the amount of the OH radical and chemical and biological parameters [total protein, total cholesterol, triglycerides and hepatitis B surface (HBs) antibodies] were estimated in the plasma of the 111 volunteers by a multivariate analysis. The presence of HBs antibodies had the greatest influence on OH radical-scavenging activity. One volunteer who did not have the HBs antibody was given an inoculation of the hepatitis B vaccine. There was a remarkable decrease in the amount of OH radical generated from plasma after the HBs antibody was produced. The results indicate that the HBs antibody is an important factor for the scavenging of OH radicals initiated by X-ray irradiation in the human body.

  15. Impact of gene variants on sex-specific regulation of human Scavenger receptor class B type 1 (SR-BI) expression in liver and association with lipid levels in a population-based study

    PubMed Central

    2010-01-01

    Background Several studies have noted that genetic variants of SCARB1, a lipoprotein receptor involved in reverse cholesterol transport, are associated with serum lipid levels in a sex-dependent fashion. However, the mechanism underlying this gene by sex interaction has not been explored. Methods We utilized both epidemiological and molecular methods to study how estrogen and gene variants interact to influence SCARB1 expression and lipid levels. Interaction between 35 SCARB1 haplotype-tagged polymorphisms and endogenous estradiol levels was assessed in 498 postmenopausal Caucasian women from the population-based Rancho Bernardo Study. We further examined associated variants with overall and SCARB1 splice variant (SR-BI and SR-BII) expression in 91 human liver tissues using quantitative real-time PCR. Results Several variants on a haplotype block spanning intron 11 to intron 12 of SCARB1 showed significant gene by estradiol interaction affecting serum lipid levels, the strongest for rs838895 with HDL-cholesterol (p = 9.2 × 10-4) and triglycerides (p = 1.3 × 10-3) and the triglyceride:HDL cholesterol ratio (p = 2.7 × 10-4). These same variants were associated with expression of the SR-BI isoform in a sex-specific fashion, with the strongest association found among liver tissue from 52 young women <45 years old (p = 0.002). Conclusions Estrogen and SCARB1 genotype may act synergistically to regulate expression of SCARB1 isoforms and impact serum levels of HDL cholesterol and triglycerides. This work highlights the importance of considering sex-dependent effects of gene variants on serum lipid levels. PMID:20085651

  16. CBLB502, an agonist of Toll-like receptor 5, has antioxidant and scavenging free radicals activities in vitro.

    PubMed

    Li, Weiguang; Ge, Changhui; Yang, Liu; Wang, Ruixue; Lu, Yiming; Gao, Yan; Li, Zhihui; Wu, Yonghong; Zheng, Xiaofei; Wang, Zhaoyan; Zhang, Chenggang

    2016-01-01

    The bacterial protein flagellin is the known agonist of Toll-like receptor 5 (TLR5). It has been reported that CBLB502, a novel agonist of TLR5 derived from Salmonella flagellin, could reduce radiation toxicity in mouse and primate models, protect mice from dermatitis and oral mucositis caused by radiation, inhibit acute renal ischemic failure, and inhibit the growth of A549 lung cancer cell. The property of CBLB502 is able to bind to TLR5 and activates NF-κB signaling. In this study, we investigated the antioxidant potential and free radicals scavenging properties of CBLB502 in vitro. Interestingly, we found that CBLB502 has a direct and distinct antioxidant capacity and can efficiently scavenge a variety of free radicals, including superoxide anion, hydroxyl radical, and ABTS cation (ABTS(+)). Through wave scanning and kinetic evaluation of scavenging ABTS(+), we found that the ABTS(+) scavenging process of CBLB502 is relatively slow, and the ABTS(+) scavenging activity of CBLB502 has a consistently kinetics characteristics. In conclusion, our results suggested that CBLB502 has antioxidant and scavenging free radicals activities in vitro. It is implied that CBLB502 might partially promote the beneficial protective effect through its scavenging free radicals.

  17. Molecular determinants of enterovirus 71 viral entry: cleft around GLN-172 on VP1 protein interacts with variable region on scavenge receptor B 2.

    PubMed

    Chen, Pan; Song, Zilin; Qi, Yonghe; Feng, Xiaofeng; Xu, Naiqing; Sun, Yinyan; Wu, Xing; Yao, Xin; Mao, Qunyin; Li, Xiuling; Dong, Wenjuan; Wan, Xiaobo; Huang, Niu; Shen, Xinliang; Liang, Zhenglun; Li, Wenhui

    2012-02-24

    Enterovirus 71 (EV71) is one of the major pathogens that cause hand, foot, and mouth disease outbreaks in young children in the Asia-Pacific region in recent years. Human scavenger receptor class B 2 (SCARB2) is the main cellular receptor for EV71 on target cells. The requirements of the EV71-SCARB2 interaction have not been fully characterized, and it has not been determined whether SCARB2 serves as an uncoating receptor for EV71. Here we compared the efficiency of the receptor from different species including human, horseshoe bat, mouse, and hamster and demonstrated that the residues between 144 and 151 are critical for SCARB2 binding to viral capsid protein VP1 of EV71 and seven residues from the human receptor could convert murine SCARB2, an otherwise inefficient receptor, to an efficient receptor for EV71 viral infection. We also identified that EV71 binds to SCARB2 via a canyon of VP1 around residue Gln-172. Soluble SCARB2 could convert the EV71 virions from 160 S to 135 S particles, indicating that SCARB2 is an uncoating receptor of the virus. The uncoating efficiency of SCARB2 significantly increased in an acidic environment (pH 5.6). These studies elucidated the viral capsid and receptor determinants of enterovirus 71 infection and revealed a possible target for antiviral interventions.

  18. Lack of the scavenger receptor CD36 alters microglial phenotypes after neonatal stroke

    PubMed Central

    Li, Fan; Faustino, Joel; Woo, Moon-Sook; Derugin, Nikita; Vexler, Zinaida S

    2016-01-01

    The stage of brain development at the time of stroke has a major impact on the pathophysiological mechanisms of ischemic damage, including the neuroinflammatory response. Microglial cells have been shown to contribute to acute and sub-chronic injury in adult stroke models, whereas in neonatal rodents we showed that microglial cells serve as endogenous neuroprotectants early following transient middle cerebral artery occlusion (tMCAO), limiting neuroinflammation and injury. In the neonate, microglial depletion or lack of the scavenger receptor CD36 exacerbates injury. In this study we asked if lack of CD36 affects microglial phenotypes after neonatal stroke. Using RT-PCR we characterized the patterns of gene expression in microglia isolated from injured regions following acute tMCAO in postnatal day 10 mice and showed that expression of several pro-inflammatory genes, including Toll-like receptors (TLR), remains largely unaffected in activated microglia in injured regions. Using multiple biochemical assays we demonstrated that lack of CD36 alters several functions of microglia in acutely injured neonatal brain: it further enhances accumulation of the chemokine MCP-1, affects the number of CD11b+/CD45+ cells, along with protein expression of its co-receptor, TLR2, but does not affect accumulation of superoxide in microglia or the cytokines TNFα and IL-1β in injured regions. PMID:26223273

  19. The Role of Scavenger Receptor B1 in Infection with Mycobacterium tuberculosis in a Murine Model

    PubMed Central

    Schäfer, Georgia; Guler, Reto; Murray, Graeme; Brombacher, Frank; Brown, Gordon D.

    2009-01-01

    Background The interaction between Mycobacterium tuberculosis (Mtb) and host cells is complex and far from being understood. The role of the different receptor(s) implicated in the recognition of Mtb in particular remains poorly defined, and those that have been found to have activity in vitro were subsequently shown to be redundant in vivo. Methods and Findings To identify novel receptors involved in the recognition of Mtb, we screened a macrophage cDNA library and identified scavenger receptor B class 1 (SR-B1) as a receptor for mycobacteria. SR-B1 has been well-described as a lipoprotein receptor which mediates both the selective uptake of cholesteryl esters and the efflux of cholesterol, and has also recently been implicated in the recognition of other pathogens. We show here that mycobacteria can bind directly to SR-B1 on transfected cells, and that this interaction could be inhibited in the presence of a specific antibody to SR-B1, serum or LDL. We define a variety of macrophage populations, including alveolar macrophages, that express this receptor, however, no differences in the recognition and response to mycobacteria were observed in macrophages isolated from SR-B1−/− or wild type mice in vitro. Moreover, when wild type and SR-B1−/− animals were infected with a low dose of Mtb (100 CFU/mouse) there were no alterations in survival, bacterial burdens, granuloma formation or cytokine production in the lung. However, significant reduction in the production of TNF, IFNγ, and IL10 were observed in SR-B1−/− mice following infection with a high dose of Mtb (1000 CFU/mouse), which marginally affected the size of inflammatory foci but did not influence bacterial burdens. Deficiency of SR-B1 also had no effect on resistance to disease under conditions of varying dietary cholesterol. We did observe, however, that the presence of high levels of cholesterol in the diet significantly enhanced the bacterial burdens in the lung, but this was independent of SR

  20. Tryptophan 415 Is Critical for the Cholesterol Transport Functions of Scavenger Receptor BI.

    PubMed

    Holme, Rebecca L; Miller, James J; Nicholson, Kay; Sahoo, Daisy

    2016-01-12

    High density lipoproteins (HDL) are anti-atherogenic particles, primarily due to their role in the reverse cholesterol transport pathway whereby HDL delivers cholesteryl esters (CE) to the liver for excretion upon interaction with its receptor, scavenger receptor BI (SR-BI). We designed experiments to test the hypothesis that one or more of the eight highly conserved tryptophan (Trp; W) residues in SR-BI are critical for mediating function. We created a series of Trp-to-phenylalanine (Phe, F) mutant receptors, as well as Trp-less SR-BI (ΔW-SR-BI), and assessed their ability to mediate cholesterol transport. Wild-type (WT) or mutant SR-BI receptors were transiently expressed in COS-7 cells, and cell surface expression was confirmed. Next, we showed that Trp-less- and W415F-SR-BI had significantly decreased abilities to bind HDL and promote selective uptake of HDL-CE, albeit with higher selective uptake efficiency as compared to WT-SR-BI. Interestingly, only Trp-less-, but not W415F-SR-BI, showed an impaired ability to mediate efflux of free cholesterol (FC). Furthermore, both W415F- and Trp-less-SR-BI were unable to reorganize plasma membrane pools of FC based on lack of sensitivity to exogenous cholesterol oxidase. Restoration of Trp 415 into the Trp-less-SR-BI background was unable to rescue Trp-less-SR-BI's impaired functions, suggesting that Trp 415 is critical, but not sufficient for full receptor function. Furthermore, with the exception of Trp 262, restoration of individual extracellular Trp residues, in combination with Trp 415, into the Trp-less-SR-BI background partially rescued SR-BI function, indicating that Trp 415 must be present in combination with other Trp residues for proper cholesterol transport functions.

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

    PubMed

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

    2015-08-01

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

  2. Cell entry of hepatitis C virus requires a set of co-receptors that include the CD81 tetraspanin and the SR-B1 scavenger receptor.

    PubMed

    Bartosch, Birke; Vitelli, Alessandra; Granier, Christelle; Goujon, Caroline; Dubuisson, Jean; Pascale, Simona; Scarselli, Elisa; Cortese, Riccardo; Nicosia, Alfredo; Cosset, François-Loïc

    2003-10-24

    Several cell surface molecules have been proposed as receptor candidates, mediating cell entry of hepatitis C virus (HCV) on the basis of their physical association with virions or with soluble HCV E2 glycoproteins. However, due to the lack of infectious HCV particles, evidence that these receptor candidates support infection was missing. Using our recently described infectious HCV pseudotype particles (HCVpp) that display functional E1E2 glycoprotein complexes, here we show that HCV is a pH-dependent virus, implying that its receptor component(s) mediate virion internalization by endocytosis. Expression of the CD81 tetraspanin in non-permissive CD81-negative hepato-carcinoma cells was sufficient to restore susceptibility to HCVpp infection, confirming its critical role as a cell attachment factor. As a cell surface molecule likely to mediate endosomal trafficking, we demonstrate that the human scavenger receptor class B type 1 (SR-B1), a high-density lipoprotein-internalization molecule that we previously proposed as a novel HCV receptor candidate due to its affinity with E2 glycoproteins, is required for infection of CD81-expressing hepatic cells. By receptor competition assays, we found that SR-B1 antibodies that blocked binding of soluble E2 could prevent HCVpp infectivity. Furthermore, we establish that the hyper-variable region 1 of the HCV E2 glycoprotein is a critical determinant mediating entry in SR-B1-positive cells. Finally, by correlating expression of HCV receptors and infectivity, we suggest that, besides CD81 and SR-B1, additional hepatocyte-specific co-factor(s) are necessary for HCV entry.

  3. Phospholipids in oxidized LDL not adducted to apoB are recognized by the CD36 scavenger receptor.

    PubMed

    Podrez, Eugene A; Hoppe, George; O'Neil, June; Hoff, Henry F

    2003-02-01

    Previous studies have shown that oxidation of low-density lipoprotein (oxLDL) results in its recognition by scavenger receptors on macrophages. Whereas blockage of lysyl residues on apoB-100 of oxLDL by lipid peroxidation products appears to be critical for recognition by the scavenger receptor class A (SR-A), modification of the lipid moiety has been suggested to be responsible for recognition by the scavenger class B receptor, CD36. We studied the recognition by scavenger receptors of oxidized LDL in which lysyl residues are blocked prior to oxidation through methylation [ox(m)LDL]. This permits us to minimize any contribution of modified apoB-100 to the recognition of oxLDL, but does not disrupt the native configuration of lipids in the particle. We found that ox(m)LDL was recognized by receptors on mouse peritoneal macrophages (MPM) almost as well as oxLDL. Ox(m)LDL was recognized by CD36-transfected cells but not by SR-A-transfected cells. Oxidized phospholipids (oxPC) transferred from oxLDL or directly from oxPC to LDL, conveyed recognition by CD36-transfected cells, confirming that CD36 recognized unbound oxidized phospholipids in ox(m)LDL. Collectively, these results suggest that oxPC not adducted to apoB within the intact oxLDL particle are recognized by the macrophage scavenger receptor CD36, that these lipids are not recognized by SR-A, and that they can transfer from oxidized to unoxidized LDL and induce CD36 recognition.

  4. Identification of nonabsorbable inhibitors of the scavenger receptor-BI (SR-BI) for tissue-specific administration.

    PubMed

    Sparks, Steven M; Zhou, Huiqiang; Generaux, Claudia; Harston, Lindsey; Moncol, David; Jayawickreme, Channa; Parham, Janet; Condreay, Patrick; Rimele, Thomas

    2016-04-15

    The identification of a low-permeability scavenger receptor BI (SR-BI) inhibitor starting from the ITX-5061 template is described. Structure-activity and structure-permeability relationships were assessed for analogs leading to the identification of compound 8 as a potent and nonabsorbable SR-BI inhibitor.

  5. Mycobacterium tuberculosis lipoarabinomannan enhances LPS-induced TNF-α production and inhibits NO secretion by engaging scavenger receptors.

    PubMed

    Józefowski, Szczepan; Sobota, Andrzej; Pawłowski, Andrzej; Kwiatkowska, Katarzyna

    2011-06-01

    Lipoarabinomannan capped with terminal oligomannosides (ManLAM) is a component of mycobacteria cell wall enabling Mycobacterium tuberculosis to infect macrophages. We found that short treatment (3.5h) of macrophage-like J774 cells and thioglycollate-elicited peritoneal murine macrophages with ManLAM and its deacylated form enhanced LPS-stimulated release of tumor necrosis factor-α (TNF-α). In contrast, prolong incubation of J774 cells with ManLAM (16h) led to inhibition of LPS-stimulated TNF-α production. LPS-triggered secretion of nitric oxide (NO) was suppressed by ManLAM and its deacylated form. Effects of ManLAM and its deacylated derivative were mimicked by dextran sulfate, a general ligand of scavenger receptors. The enhancement of LPS-induced TNF-α production by dextran sulfate was partially reversed by an antibody neutralizing scavenger receptor SR-PSOX/CXCL16 while the stimulatory activity of deacylated ManLAM was reversed by an antibody neutralizing class B scavenger receptor CD36. Our data suggest that CD36 mediates the activity of ManLAM and its deacylated form leading to TNF-α release in LPS-stimulated J774 cells and peritoneal murine macrophages, while NO production is modulated by unknown scavenger receptors.

  6. Albumin-based microbubbles bind up-regulated scavenger receptors following vascular injury.

    PubMed

    Anderson, Daniel R; Duryee, Michael J; Anchan, Rajeev K; Garvin, Robert P; Johnston, Michael D; Porter, Thomas R; Thiele, Geoffrey M; Klassen, Lynell W

    2010-12-24

    We have shown previously that perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles bind to injured vascular tissue and can be detected with ultrasound imaging techniques. Prior studies have shown that scavenger receptors (SRs) are regulators of innate and adaptive immune responses and are involved in the progression of vascular disease such as atherosclerosis. In this study, we sought to determine the molecular mechanism of PESDA binding to balloon-injured vasculature. RT-PCR analysis of angioplastied aortas demonstrated a significantly (p ≤ 0.01) increased expression of SRs. Binding to SRs was confirmed using SR-expressing CHO cells, and this binding was blocked by competitive inhibition with the SR-binding ligands oxidized LDL and malondialdehyde-acetaldehyde-modified LDL. Confocal imaging confirmed the co-localization of PESDA microbubbles to CD36, SRB-1, and Toll-like receptor 4, but not to monocytes/macrophages. This study demonstrates that PESDA binds to SRs and that this binding is in major part dependent upon the oxidized nature of PESDA microbubble shell proteins. The extent of SR mRNA expression was increased with injury and associated with microbubble retention as defined by scanning electron microscopy and immunohistochemistry. These findings clarify the mechanisms of how albumin-based microbubbles bind to injured and inflamed vasculature and further support the potential of this imaging technique to detect early vascular innate inflammatory pathophysiologic processes.

  7. Interferon alpha bioactivity critically depends on Scavenger receptor class B type I function

    PubMed Central

    Vasquez, Marcos; Fioravanti, Jessica; Aranda, Fernando; Paredes, Vladimir; Gomar, Celia; Ardaiz, Nuria; Fernandez-Ruiz, Veronica; Méndez, Miriam; Nistal-Villan, Estanislao; Larrea, Esther; Gao, Qinshan; Gonzalez-Aseguinolaza, Gloria; Prieto, Jesus; Berraondo, Pedro

    2016-01-01

    ABSTRACT Scavenger receptor class B type I (SR-B1) binds pathogen-associated molecular patterns participating in the regulation of the inflammatory reaction but there is no information regarding potential interactions between SR-B1 and the interferon system. Herein, we report that SR-B1 ligands strongly regulate the transcriptional response to interferon α (IFNα) and enhance its antiviral and antitumor activity. This effect was mediated by the activation of TLR2 and TLR4 as it was annulled by the addition of anti-TLR2 or anti-TLR4 blocking antibodies. In vivo, we maximized the antitumor activity of IFNα co-expressing in the liver a SR-B1 ligand and IFNα by adeno-associated viruses. This gene therapy strategy eradicated liver metastases from colon cancer with reduced toxicity. On the other hand, genetic and pharmacological inhibition of SR-B1 blocks the clathrin-dependent interferon receptor recycling pathway with a concomitant reduction in IFNα signaling and bioactivity. This effect can be applied to enhance cancer immunotherapy with oncolytic viruses. Indeed, SR-B1 antagonists facilitate replication of oncolytic viruses amplifying their tumoricidal potential. In conclusion, SR-B1 agonists behave as IFNα enhancers while SR-B1 inhibitors dampen IFNα activity. These results demonstrate that SR-B1 is a suitable pharmacology target to enhance cancer immunotherapy based on IFNα and oncolytic viruses. PMID:27622065

  8. Uncoupling scavenger receptor A-mediated phagocytosis of bacteria from endotoxic shock resistance.

    PubMed

    Amiel, Eyal; Acker, Julie L; Collins, Ryan M; Berwin, Brent

    2009-10-01

    Unresolved infection by gram-negative bacteria can result in the potentially lethal condition known as endotoxic shock, whereby uncontrolled inflammation can lead to multiple organ failure and death of the infected host. Previous results have demonstrated that animals deficient in class A scavenger receptor (SRA), a trafficking receptor for bacteria and bacterium-derived molecules, are more susceptible to endotoxic shock. This has been proposed to be a result of impaired SRA-dependent phagocytic clearance of bacteria resulting in stronger proinflammatory stimuli. In this report, we test the hypothesis that there is an obligate reciprocal relationship between SRA-mediated phagocytosis of bacteria and susceptibility to endotoxic shock. Here, we demonstrate that both SRA-dependent and -independent gram-negative bacterial strains elicit SRA-dependent increased cytokine production in vitro and in vivo and increased susceptibility to endotoxic shock in SRA-deficient mice. This is the first evidence showing that SRA-mediated clearance of LPS is functionally distinct from the role of SRA in bacterial phagocytosis and is a formal demonstration that the SRA-dependent cytokine responses and the resultant endotoxic shock are not coupled to SRA-mediated clearance of bacteria.

  9. Exploring the link between scavenger receptor B1 expression and chronic obstructive pulmonary disease pathogenesis.

    PubMed

    Valacchi, Giuseppe; Maioli, Emanuela; Sticozzi, Claudia; Cervellati, Franco; Pecorelli, Alessandra; Cervellati, Carlo; Hayek, Joussef

    2015-03-01

    Chronic obstructive pulmonary disease (COPD) has been recognized as one of the major causes of morbidity and mortality in the United States; it is the third leading cause of deaths in the United States, with approximately 15 million Americans affected with COPD. Although exposure to cigarette smoke has been shown to be the main, if not the only, risk factor for COPD, the mechanisms underlying this association remain unclear. Most smokers do not develop COPD, suggesting that a combination of exposure and susceptibility (genetic background) is required. Several mechanisms contribute to the pathogenesis of COPD, such as influx of inflammatory cells into the lung, imbalance between proteolytic and antiproteolytic molecules, disruption of the balance between apoptosis and replenishment of structural cells in the lung, and disruption of oxidant/antioxidant balance. The scavenger receptor BI (SRB1) plays an important role in mediating the uptake of high-density lipoprotein (HDL)-derived cholesterol and cholesteryl ester in tissues. In addition to its role as the HDL receptor, SRB1 is also involved in pathogen recognition, identification of apoptotic cells, tissue antioxidant uptake (tocopherol and carotenoids), and lung surfactant composition, all factors involved in COPD pathogenesis. Therefore, it is possible that lung SRB1 levels are involved in the development of COPD.

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

    SciTech Connect

    Takemura, Kenichi; Sakashita, Naomi; Fujiwara, Yukio; Komohara, Yoshihiro; Lei, XiaoFeng; Ohnishi, Koji; Suzuki, Hiroshi; Kodama, Tatsuhiko; Mizuta, Hiroshi; Takeya, Motohiro

    2010-01-22

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

  11. Plant carbohydrate scavenging through tonB-dependent receptors: a feature shared by phytopathogenic and aquatic bacteria.

    PubMed

    Blanvillain, Servane; Meyer, Damien; Boulanger, Alice; Lautier, Martine; Guynet, Catherine; Denancé, Nicolas; Vasse, Jacques; Lauber, Emmanuelle; Arlat, Matthieu

    2007-02-21

    TonB-dependent receptors (TBDRs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc), predicts 72 TBDRs. Such an overrepresentation is common in Xanthomonas species but is limited to only a small number of bacteria. Here, we show that one Xcc TBDR transports sucrose with a very high affinity, suggesting that it might be a sucrose scavenger. This TBDR acts with an inner membrane transporter, an amylosucrase and a regulator to utilize sucrose, thus defining a new type of carbohydrate utilization locus, named CUT locus, involving a TBDR for the transport of substrate across the outer membrane. This sucrose CUT locus is required for full pathogenicity on Arabidopsis, showing its importance for the adaptation to host plants. A systematic analysis of Xcc TBDR genes and a genome context survey suggested that several Xcc TBDRs belong to other CUT loci involved in the utilization of various plant carbohydrates. Interestingly, several Xcc TBDRs and CUT loci are conserved in aquatic bacteria such as Caulobacter crescentus, Colwellia psychrerythraea, Saccharophagus degradans, Shewanella spp., Sphingomonas spp. or Pseudoalteromonas spp., which share the ability to degrade a wide variety of complex carbohydrates and display TBDR overrepresentation. We therefore propose that TBDR overrepresentation and the presence of CUT loci designate the ability to scavenge carbohydrates. Thus CUT loci, which seem to participate to the adaptation of phytopathogenic bacteria to their host plants, might also play a very important role in the biogeochemical cycling of plant-derived nutrients in marine environments. Moreover, the TBDRs and CUT loci identified in this study are clearly different from those characterized in the human gut symbiont Bacteroides thetaiotaomicron, which allow glycan foraging, suggesting a convergent

  12. Plant Carbohydrate Scavenging through TonB-Dependent Receptors: A Feature Shared by Phytopathogenic and Aquatic Bacteria

    PubMed Central

    Boulanger, Alice; Lautier, Martine; Guynet, Catherine; Denancé, Nicolas; Vasse, Jacques

    2007-01-01

    TonB-dependent receptors (TBDRs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc), predicts 72 TBDRs. Such an overrepresentation is common in Xanthomonas species but is limited to only a small number of bacteria. Here, we show that one Xcc TBDR transports sucrose with a very high affinity, suggesting that it might be a sucrose scavenger. This TBDR acts with an inner membrane transporter, an amylosucrase and a regulator to utilize sucrose, thus defining a new type of carbohydrate utilization locus, named CUT locus, involving a TBDR for the transport of substrate across the outer membrane. This sucrose CUT locus is required for full pathogenicity on Arabidopsis, showing its importance for the adaptation to host plants. A systematic analysis of Xcc TBDR genes and a genome context survey suggested that several Xcc TBDRs belong to other CUT loci involved in the utilization of various plant carbohydrates. Interestingly, several Xcc TBDRs and CUT loci are conserved in aquatic bacteria such as Caulobacter crescentus, Colwellia psychrerythraea, Saccharophagus degradans, Shewanella spp., Sphingomonas spp. or Pseudoalteromonas spp., which share the ability to degrade a wide variety of complex carbohydrates and display TBDR overrepresentation. We therefore propose that TBDR overrepresentation and the presence of CUT loci designate the ability to scavenge carbohydrates. Thus CUT loci, which seem to participate to the adaptation of phytopathogenic bacteria to their host plants, might also play a very important role in the biogeochemical cycling of plant-derived nutrients in marine environments. Moreover, the TBDRs and CUT loci identified in this study are clearly different from those characterized in the human gut symbiont Bacteroides thetaiotaomicron, which allow glycan foraging, suggesting a convergent

  13. Relationship Between Scavenger Receptors and UPA:PAI-l and UPA Receptors in Breast Cancer

    DTIC Science & Technology

    1999-10-01

    cells or the human fibrosarcoma -derived cell line , HT1080 . The results we...Obtained in Year 3: 1. LRP and uPAR expressed on the surface of the breast cancer cell line , Hs578T, and a human fibrosarcoma , HT1080 , are functionally...expression in three estrogen-insensitive and one sensitive breast cell lines , one normal mammary cell line , and a human fibrosarcoma cell line . Our

  14. The Macrophage Scavenger Receptor A Is Host-Protective in Experimental Meningococcal Septicaemia

    PubMed Central

    Makepeace, Katherine; Moxon, E. Richard; Gordon, Siamon

    2009-01-01

    Macrophage Scavenger Receptor A (SR-A) is a major non-opsonic receptor for Neisseria meningitidis on mononuclear phagocytes in vitro, and the surface proteins NMB0278, NMB0667, and NMB1220 have been identified as ligands for SR-A. In this study we ascertain the in vivo role of SR-A in the recognition of N. meningitidis MC58 (serogroup B) in a murine model of meningococcal septicaemia. We infected wild-type and SR-A−/− animals intraperitoneally with N. meningitidis MC58 and monitored their health over a period of 50 hours. We also determined the levels of bacteraemia in the blood and spleen, and measured levels of the pro-inflammatory cytokine interleukin-6 (IL-6). The health of SR-A−/− animals deteriorated more rapidly, and they showed a 33% reduction in survival compared to wild-type animals. SR-A−/− animals consistently exhibited higher levels of bacteraemia and increased levels of IL-6, compared to wild-type animals. Subsequently, we constructed a bacterial mutant (MC58-278-1220) lacking two of the SR-A ligands, NMB0278 and NMB1220. Mutation of NMB0667 proved to be lethal. When mice were infected with the mutant bacteria MC58-278-1220, no significant differences could be observed in the health, survival, bacteraemia, and cytokine production between wild-type and SR-A−/− animals. Overall, mutant bacteria appeared to cause less severe symptoms of septicaemia, and a competitive index assay showed that higher levels of wild-type bacteria were recovered when animals were infected with a 1∶1 ratio of wild-type MC58 and mutant MC58-278-1220 bacteria. These data represent the first report of the protective role of SR-A, a macrophage-restricted, non-opsonic receptor, in meningococcal septicaemia in vivo, and the importance of the recognition of bacterial protein ligands, rather than lipopolysaccharide. PMID:19214213

  15. Lung macrophage uptake of unopsonized environmental particulates: Role of scavenger-type receptors

    SciTech Connect

    Kobzik, L.

    1995-07-01

    The receptors responsible for avid alveolar macrophage (AM) phagocytosis of unopsonized environmental particulates have not been well defined. This study used flow cytometry to quantitate the effects of a panel of soluble ligands for macrophage adhesion receptors on AM binding of unopsonized environmental dusts (titanium dioxide, TiO{sub 2}; iron oxide, Fe{sub 2}O{sub 3}; {alpha}-quartz, SiO{sub 2}; diesel engine exhaust dust) or fluorescent latex beads. Polyanionic ligands of the macrophage scavenger receptor (SR) for acetylated-LDL caused marked inhibition of AM binding of the oxide particles and latex beads (e.g., TiO{sub 2} binding; polyinosinic acid (polyl), 10 {mu}g/ml: 70.2 {+-} 1.5% inhibition, mean {+-} SE, n = 11). In contrast, no inhibition was seen with the polyanions heparin and chondroitin sulfate (chond-S), or dextran, consistent with the known inhibitor profile of macrophage SRs for acetylated-LDL. AM uptake of latex or SiO{sub 2} beads instilled into lungs of hamsters was inhibited by administration of polyl but not chondroitin sulfate (AM beads per cell: control, 6.1 {+-} 0.7; polyl, 3.5 {+-} 0.2; chond-S, 5.1 {+-} 0.7, n {ge} 4, p < 0.05 for control vs polyl) indicating macrophage SRs operate in vivo as well as in vitro. In contrast, AM binding of the carbonaceous diesel dust particles was not inhibited by any ligand tested. AM uptake of unopsonized TiO{sub 2}, SR ligands or acetylated LDL caused no significant activation of AM respiratory burst or TNF production, consistent with past observations that opsonin-independent phagocytosis of inert particles by normal AMs is not accompanied by pro-inflammatory activation. These data implicate macrophage-type SRs in AM binding of charged environmental particles and indicate that distinct mechanisms mediate binding of carbonaceous dusts. 54 refs., 7 figs., 4 tabs.

  16. Scavenger receptor class B, type I (Scarb1) deficiency promotes osteoblastogenesis but stunts terminal osteocyte differentiation

    PubMed Central

    Martineau, Corine; Kevorkova, Olha; Brissette, Louise; Moreau, Robert

    2014-01-01

    Abstract Scavenger receptor class B type I (SR‐BI), the Scarb1 gene product, is a high‐density lipoprotein (HDL) receptor which was shown to influence bone metabolism. Its absence in mice is associated with alterations of the glucocorticoid/adrenocorticotropic hormone axis, and translated in high bone mass and enhanced bone formation. Since the cellular alterations underlying the enhanced bone formation remain unknown, we investigated Scarb1‐deficient marrow stromal cells (MSC) behavior in vitro. No difference in HDL3, cholesteryl ester (CE) or estradiol (E) association/binding was measured between Scarb1‐null and wild‐type (WT) cells. Scarb1 genic expression was down‐regulated twofold following osteogenic treatment. Neither WT nor null cell proliferation was influenced by HDL3 exposure whereas this condition decreased genic expression of osteoblastic marker osterix (Sp7), and osteocyte markers sclerostin (Sost) and dentin matrix protein 1 (Dmp1) independently of genotype. Sost and Dmp1 basal expression in null cells was 40% and 50% that of WT cells; accordingly, osteocyte density was 20% lower in vertebrae from Scarb1‐null mice. Genic expression of co‐receptors for Wnt signaling, namely LDL‐related protein (Lrp) 5 and Lrp8, was increased, respectively, by two‐ and threefold, and of transcription target‐genes axis inhibition protein 2 (Axin2) and lymphoid enhancer‐binding factor 1 (Lef1) over threefold. Gene expression of Wnt signaling agonist Wnt5a and of the antagonist dickkopfs‐related protein 1 (Dkk1) were found to be increased 10‐ to 20‐fold in null MSC. These data suggest alterations of Wnt pathways in Scarb1‐deficient MSC potentially explaining their enhanced function, hence contributing to the high bone mass observed in these mice. PMID:25281615

  17. Identification and characterization of class B scavenger receptor CD36 from the hard tick, Haemaphysalis longicornis.

    PubMed

    Aung, Kyaw Min; Boldbaatar, Damdinsuren; Liao, Min; Umemiya-Shirafuji, Rika; Nakao, Sumihiro; Matsuoka, Terushige; Tanaka, Tetsuya; Fujisaki, Kozo

    2011-02-01

    Scavenger receptors (SRs) are cell-surface proteins and exhibit distinctive ligand-binding properties, recognizing a wide range of ligands that include microbial surface constituents and intact microbes. The class B scavenger receptor CD36 (SRB) is predominantly expressed by macrophages and is considered important in innate immunity. We here show the identification and characterization of SRB from the hard ixodid tick, Haemaphysalis longicornis (HlSRB). The full-length cDNA was 2,908 bp, including an ORF encoding of 1,518 amino acids with a pI value of 5.83. H. longicornis SRB contains a hydrophobic SRB domain and four centrally clustered cysteine residues for arrangement of disulfide bridges. Deduced amino acid sequence has an identity of 30-38% with the SRB of other organisms. RT-PCR analysis showed that mRNA transcripts were expressed in multiple organs of adult ticks but with a different transcript level in the developmental stages of H. longicornis ticks. His-tagged recombinant HlSRB was expressed in Escherichia coli with an expected molecular mass of 50 kDa. In Western blot analysis, mouse anti-rHlSRB serum recognized a strong reaction with a 50 kDa protein band in lysates prepared from egg and adult tick but showed a weak reaction with lysates of larva and nymph. In an indirect immunofluorescent antibody test, HlSRB antiserum recognized the protein located on the midgut, salivary glands, and ovary of partially fed H. longicornis females. Silencing of the HlSRB gene by RNAi led to a significant reduction in the engorged female body weight. It is noteworthy that more than a dozen SRB orthologs have been identified in the genomes of insect species with functions related to pheromone signaling, innate immunity, phagocytic clearance of apoptotic cells, and various aspects of the fatty acid metabolism. This is the first report of the identification and characterization of the SRB homologue in Chelicerata, including ticks, horseshoe crabs, scorpions, spiders, and

  18. Expression of scavenger receptor-BI and low-density lipoprotein receptor and differential use of lipoproteins to support early steroidogenesis in luteinizing macaque granulosa cells.

    PubMed

    Cherian-Shaw, Mary; Puttabyatappa, Muraly; Greason, Erin; Rodriguez, Annabelle; VandeVoort, Catherine A; Chaffin, Charles L

    2009-02-01

    An ovulatory hCG stimulus to rhesus macaques undergoing controlled ovarian stimulation protocols results in a rapid and sustained increase in progesterone synthesis. The use of lipoproteins as a substrate for progesterone synthesis remains unclear, and the expression of lipoprotein receptors [very-low-density lipoprotein receptor (VLDLR), low-density lipoprotein receptor (LDLR), and scavenger receptor-BI (SR-BI)] soon after human chorionic gonadotropin (hCG) (<12 h) has not been characterized. This study investigated lipoprotein receptor expression and lipoprotein (VLDL, LDL, and HDL) support of steroidogenesis during luteinization of macaque granulosa cells. Granulosa cells were aspirated from rhesus monkeys undergoing controlled ovarian stimulation before or up to 24 h after an ovulatory hCG stimulus. The expression of VLDLR decreased within 3 h of hCG, whereas LDLR and SR-BI increased at 3 and 12 h, respectively. Granulosa cells isolated before hCG were cultured for 24 h in the presence of FSH or FSH plus hCG with or without VLDL, LDL, or HDL. Progesterone levels increased in the presence of hCG regardless of lipoprotein addition, although LDL, but not HDL, further augmented hCG-induced progesterone. Other cells were cultured with FSH or FSH plus hCG without an exogenous source of lipoprotein for 24 h, followed by an additional 24 h culture with or without lipoproteins. Cells treated with hCG in the absence of any lipoprotein were unable to maintain progesterone levels through 48 h, whereas LDL (but not HDL) sustained progesterone synthesis. These data suggest that an ovulatory stimulus rapidly mobilizes stored cholesterol esters for use as a progesterone substrate and that as these are depleted, new cholesterol esters are obtained through an LDLR- and/or SR-BI-mediated mechanism.

  19. Uptake and catabolism of modified LDL in scavenger-receptor class A type I/II knock-out mice.

    PubMed Central

    Van Berkel, T J; Van Velzen, A; Kruijt, J K; Suzuki, H; Kodama, T

    1998-01-01

    The liver is the major organ responsible for the uptake of modified low-density lipoprotein (LDL) from the blood circulation, with endothelial and Kupffer cells as major cellular uptake sites. Scavenger-receptors, which include various classes, are held responsible for this uptake. Mice deficient in scavenger-receptor class A types I and II were created and the fate of acetylated LDL (Ac-LDL) in vivo and its interaction with liver endothelial, Kupffer and peritoneal macrophages was characterized. Surprisingly, the decay in vivo (t12 < 2 min), tissue distribution and liver uptake (at 5 min it was 77.4 +/- 4.6% of the injected dose) of Ac-LDL in the knock-out mice were not significantly different from control mice (t12 < 2 min and liver uptake 79.1 +/- 4.6% of the injected dose). A separation of mice liver cells into parenchymal, endothelial and Kupffer cells 10 min after injection of Ac-LDL indicated that in both control and knock-out mice the liver endothelial cells were responsible for more than 70% of the liver uptake. Both in control and knock-out mice, preinjection of polyinosinic acid (poly I, 200 microg) completely blocked the liver uptake, indicating that both in control and knock-out mice the scavenger-receptors are sensitive to poly I. Preinjection of suboptimal poly I concentrations (20 and 50 microg) provided evidence that the serum decay and liver uptake of Ac-LDL is more readily inhibited in the knock-out mice as compared with the control mice, indicating less efficient removal of Ac-LDL in vivo in the knock-out mice under these conditions. Studies in vitro with isolated liver endothelial and Kupffer cells from knock-out mice indicate that the cell association of Ac-LDL during 2 h at 37 degrees C is 50 and 53% of the control, respectively, whereas the degradation reaches values of 58 and 63%. For peritoneal macrophages from knock-out mice the cell association of Ac-LDL was identical to the control mice whereas the Ac-LDL degradation in cells from the

  20. Endothelial Expression of Scavenger Receptor Class B, Type I Protects against Development of Atherosclerosis in Mice

    PubMed Central

    2015-01-01

    The role of scavenger receptor class B, type I (SR-BI) in endothelial cells (EC) was examined in several novel transgenic mouse models expressing SR-BI in endothelium of mice with normal C57Bl6/N, apoE-KO, or Scarb1-KO backgrounds. Mice were also created expressing SR-BI exclusively in endothelium and liver. Endothelial expression of the Tie2-Scarb1 transgene had no significant effect on plasma lipoprotein levels in mice on a normal chow diet but on an atherogenic diet, significantly decreased plasma cholesterol levels, increased plasma HDL cholesterol (HDL-C) levels, and protected mice against atherosclerosis. In 8-month-old apoE-KO mice fed a normal chow diet, the Tie2-Scarb1 transgene decreased aortic lesions by 24%. Mice expressing SR-BI only in EC and liver had a 1.5 ± 0.1-fold increase in plasma cholesterol compared to mice synthesizing SR-BI only in liver. This elevation was due mostly to increased HDL-C. In EC culture studies, SR-BI was found to be present in both basolateral and apical membranes but greater cellular uptake of cholesterol from HDL was found in the basolateral compartment. In summary, enhanced expression of SR-BI in EC resulted in a less atherogenic lipoprotein profile and decreased atherosclerosis, suggesting a possible role for endothelial SR-BI in the flux of cholesterol across EC. PMID:26504816

  1. Hepatic scavenger receptor BI protects against polymicrobial-induced sepsis through promoting LPS clearance in mice.

    PubMed

    Guo, Ling; Zheng, Zhong; Ai, Junting; Huang, Bin; Li, Xiang-An

    2014-05-23

    Recent studies revealed that scavenger receptor BI (SR-BI or Scarb1) plays a critical protective role in sepsis. However, the mechanisms underlying this protection remain largely unknown. In this study, using Scarb1(I179N) mice, a mouse model specifically deficient in hepatic SR-BI, we report that hepatic SR-BI protects against cecal ligation and puncture (CLP)-induced sepsis as shown by 75% fatality in Scarb1(I179N) mice, but only 21% fatality in C57BL/6J control mice. The increase in fatality in Scarb1(I179N) mice was associated with an exacerbated inflammatory cytokine production. Further study demonstrated that hepatic SR-BI exerts its protection against sepsis through its role in promoting LPS clearance without affecting the inflammatory response in macrophages, the glucocorticoid production in adrenal glands, the leukocyte recruitment to peritoneum or the bacterial clearance in liver. Our findings reveal hepatic SR-BI as a critical protective factor in sepsis and point out that promoting hepatic SR-BI-mediated LPS clearance may provide a therapeutic approach for sepsis.

  2. Identification of Adenovirus Serotype 5 Hexon Regions That Interact with Scavenger Receptors

    SciTech Connect

    Khare, Reeti; Reddy, Vijay S.; Nemerow, Glen R.; Barry, Michael A.

    2012-05-04

    Most of an intravenous dose of species C adenovirus serotype 5 (Ad5) is destroyed by liver Kupffer cells. In contrast, another species C virus, Ad6, evades these cells to mediate more efficient liver gene delivery. Given that this difference in Kupffer cell interaction is mediated by the hypervariable (HVR) loops of the virus hexon protein, we genetically modified each of the seven HVRs of Ad5 with a cysteine residue to enable conditional blocking of these sites with polyethylene glycol (PEG). We show that these modifications do not affect in vitro virus transduction. In contrast, after intravenous injection, targeted PEGylation at HVRs 1, 2, 5, and 7 increased viral liver transduction up to 20-fold. Elimination or saturation of liver Kupffer cells did not significantly affect this increase in the liver transduction. In vitro, PEGylation blocked uptake of viruses via the Kupffer cell scavenger receptor SRA-II. These data suggest that HVRs 1, 2, 5, and 7 of Ad5 may be involved in Kupffer cell recognition and subsequent destruction. These data also demonstrate that this conditional genetic-chemical mutation strategy is a useful tool for investigating the interactions of viruses with host tissues.

  3. Lung and salivary scavenger receptor glycoprotein-340 contribute to the host defense against influenza A viruses.

    PubMed

    Hartshorn, Kevan L; White, Mitchell R; Mogues, Tirsit; Ligtenberg, Toon; Crouch, Erika; Holmskov, Uffe

    2003-11-01

    The lung scavenger receptor-rich protein glycoprotein-340 (gp-340) is present in bronchoalveolar lavage (BAL) fluids and saliva and mediates specific adhesion to and aggregation of bacteria. It also binds to surfactant proteins A and D (SP-A and -D). Prior studies demonstrated that SP-A and SP-D contribute to innate defense against influenza A virus (IAV). We now show that lung and salivary gp-340 inhibit the hemagglutination activity and infectivity of IAV and agglutinate the virions through a mechanism distinct from that of SP-D. As in the case of SP-A, the antiviral effects of gp-340 are mediated by noncalcium-dependent interactions between the virus and sialic acid-bearing carbohydrates on gp-340. Gp-340 inhibits IAV strains that are resistant to SP-D. Concentrations of gp-340 present in saliva and BAL fluid of healthy donors are sufficient to bind to IAV and inhibit viral infectivity. On the basis of competition experiments using competing saccharide ligands, it appears that SP-D does not entirely mediate that anti-IAV activity of BAL fluid and contributes little to that of saliva. Furthermore, removal of gp-340 from BAL fluid and saliva significantly reduced anti-IAV activity. Hence, gp-340 contributes to defense against IAV and may be particularly relevant to defense against SP-D-resistant viral strains.

  4. Micellar lipid composition affects micelle interaction with class B scavenger receptor extracellular loops.

    PubMed

    Goncalves, Aurélie; Gontero, Brigitte; Nowicki, Marion; Margier, Marielle; Masset, Gabriel; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-06-01

    Scavenger receptors (SRs) like cluster determinant 36 (CD36) and SR class B type I (SR-BI) play a debated role in lipid transport across the intestinal brush border membrane. We used surface plasmon resonance to analyze real-time interactions between the extracellular protein loops and various ligands ranging from single lipid molecules to mixed micelles. Micelles mimicking physiological structures were necessary for optimal binding to both the extracellular loop of CD36 (lCD36) and the extracellular loop of SR-BI (lSR-BI). Cholesterol, phospholipid, and fatty acid micellar content significantly modulated micelle binding to and dissociation from the transporters. In particular, high phospholipid micellar concentrations inhibited micelle binding to both receptors (-53.8 and -74.4% binding at 0.32 mM compared with 0.04 mM for lCD36 and lSR-BI, respectively, P < 0.05). The presence of fatty acids was crucial for micelle interactions with both proteins (94.4 and 81.3% binding with oleic acid for lCD36 and lSR-BI, respectively, P < 0.05) and fatty acid type substitution within the micelles was the component that most impacted micelle binding to the transporters. These effects were partly due to subsequent modifications in micellar size and surface electric charge, and could be correlated to micellar vitamin D uptake by Caco-2 cells. Our findings show for the first time that micellar lipid composition and micellar properties are key factors governing micelle interactions with SRs.

  5. Deficiency of calcium and magnesium induces apoptosis via scavenger receptor BI

    PubMed Central

    Feng, Hong; Guo, Ling; Gao, Haiqing; Li, Xiang-An

    2011-01-01

    Aims Cell undergoes apoptosis in stressed status such as intracellular calcium overload or extracellular calcium/magnesium deficiency. The mechanisms of how deficiency of the divalent metal ions induces apoptosis remain to be defined. Scavenger receptor BI (SRBI) is a high density lipoprotein (HDL) receptor. Recent studies demonstrated that SR-BI is a stress response molecule which induces apoptosis upon serum deprivation. In this study, we assessed our hypothesis that the deficiency of calcium/magnesium induces apoptosis via SR-BI apoptotic pathway. Main methods We employed CHO cell lines expressing vector and SR-BI to test the effect of SR-BI on apoptosis induced by deficiency of calcium, magnesium and zinc in culture medium. The regain of different metal ions in deficient medium was also performed, respectively. Cell death was detected by morphological changes and quantified by LDH cytotoxicity assay. Apoptosis was also assessed by DNA ladder assay and DNA condensation assay. The SR-BIC323G mutant cells which lack the apoptotic activity of SR-BI were employed to verify the SR-BI-dependent effect on calcium/magnesium induced apoptosis. Key findings The deficiency of calcium/magnesium induced cell apoptosis CHO-SR-BI cells, but not in CHO-vector cells. Moreover, no apoptotic cell death was observed in SR-BIC323G mutant cells, indicating that the deficiency of divalent metal ions induces apoptosis in a SR-BI-dependent manner. Furthermore, the restoration of calcium or magnesium, but not zinc, protected CHO-SR-BI cells from apoptotic cell death, in a dose-dependent fashion. Significance These findings extend our understanding about how calcium and magnesium deficiency induces apoptosis. PMID:21291896

  6. Micellar lipid composition affects micelle interaction with class B scavenger receptor extracellular loops

    PubMed Central

    Goncalves, Aurélie; Gontero, Brigitte; Nowicki, Marion; Margier, Marielle; Masset, Gabriel; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-01-01

    Scavenger receptors (SRs) like cluster determinant 36 (CD36) and SR class B type I (SR-BI) play a debated role in lipid transport across the intestinal brush border membrane. We used surface plasmon resonance to analyze real-time interactions between the extracellular protein loops and various ligands ranging from single lipid molecules to mixed micelles. Micelles mimicking physiological structures were necessary for optimal binding to both the extracellular loop of CD36 (lCD36) and the extracellular loop of SR-BI (lSR-BI). Cholesterol, phospholipid, and fatty acid micellar content significantly modulated micelle binding to and dissociation from the transporters. In particular, high phospholipid micellar concentrations inhibited micelle binding to both receptors (−53.8 and −74.4% binding at 0.32 mM compared with 0.04 mM for lCD36 and lSR-BI, respectively, P < 0.05). The presence of fatty acids was crucial for micelle interactions with both proteins (94.4 and 81.3% binding with oleic acid for lCD36 and lSR-BI, respectively, P < 0.05) and fatty acid type substitution within the micelles was the component that most impacted micelle binding to the transporters. These effects were partly due to subsequent modifications in micellar size and surface electric charge, and could be correlated to micellar vitamin D uptake by Caco-2 cells. Our findings show for the first time that micellar lipid composition and micellar properties are key factors governing micelle interactions with SRs. PMID:25833688

  7. Prostaglandin E2 Receptor Subtype 2 Regulation of Scavenger Receptor CD36 Modulates Microglial Aβ42 Phagocytosis

    PubMed Central

    Li, Xianwu; Melief, Erica; Postupna, Nadia; Montine, Kathleen S.; Keene, C. Dirk; Montine, Thomas J.

    2016-01-01

    Recent studies underline the potential relevance of microglial innate immune activation in Alzheimer disease. Primary mouse microglia that lack prostaglandin E2 receptor subtype 2 (EP2) show decreased innate immune-mediated neurotoxicity and increased amyloid β (Aβ) peptide phagocytosis, features that were replicated in vivo. Here, we tested the hypothesis that scavenger receptor CD36 is an effector of EP2-regulated Aβ phagocytosis. CD36 expression was 143-fold greater in mouse primary microglia than in primary astrocytes. Three different means of suppressing EP2 signaling increased and an agonist of EP2 decreased CD36 expression in primary wild-type microglia. Activation of Toll-like receptor (TLR) 3, TLR4, and TLR7, but not TLR2 or TLR9, reduced primary microglial CD36 transcription and cell surface CD36 protein and reduced Aβ42 phagocytosis as well. At each step, the effects of innate immune activation on CD36 were reversed by at least 50% by an EP2 antagonist, and this partial rescue of microglia Aβ42 phagocytosis was largely mediated by CD36 activity. Finally, we showed in hippocampus of wild-type mice that innate immune activation suppressed CD36 expression by an EP2-dependent mechanism. Taken together with results of others that found brain clearance of Aβ peptides and behavioral improvements mediated by CD36 in mice, regulation of CD36-mediated Aβ phagocytosis by suppression of EP2 signaling may provide a new approach to suppressing some aspects of Alzheimer disease pathogenesis. PMID:25452117

  8. Identification of a novel class B scavenger receptor homologue in Portunus trituberculatus: Molecular cloning and microbial ligand binding.

    PubMed

    Yang, Ning; Zhang, Dan-Feng; Tao, Zhen; Li, Meng; Zhou, Su-Ming; Wang, Guo-Liang

    2016-11-01

    Class B scavenger receptors (SRBs), which are present in mammals and insects, have been implicated in a wide range of functions. Herein, a novel SRB homologue, PtSRB, was cloned from the swimming crab, Portunus trituberculatus. PtSRB has 538 amino acid residues, and it consists of two transmembrane regions, a large extracellular loop, and two intracellular tails. A phylogenetic analysis showed that PtSRB distinctly clustered with Marsupenaeus japonicas SRB-1 and most Drosophila SRB homologues, including Croquemort, Peste, NinaD, and Santa Maria, but was separate from the Drosophila sensory neuron membrane protein, MjSRB-2, and all vertebrate SRBs. Real-time quantitative PCR analyses showed that the PtSRB gene was constitutively expressed in all tissues tested. When PtSRB was overexpressed in human embryonic kidney 293T cells, it was distributed in the membrane and cytoplasm. Moreover, in vitro assays showed that rPtSRB bound microbial lipopolysaccharide with low affinity, and lipoteichoic acid and peptidoglycan with high affinity. PtSRB transcripts were down-regulated after challenge with Vibrio alginolyticus or white spot syndrome virus, but not after a Candida lusitaniae challenge. This study provides valuable data for understanding the role of SRBs in the host defense against microbial pathogens, which will facilitate future studies of host-pathogen interactions in crabs.

  9. Upregulation of Scavenger Receptor BI by Hepatic Nuclear Factor 4α through a Peroxisome Proliferator-Activated Receptor γ-Dependent Mechanism in Liver

    PubMed Central

    Zhang, Yi; Shen, Chen; Ai, Ding; Xie, Xuefen; Zhu, Yi

    2011-01-01

    Hepatic nuclear factor 4α (HNF4α) modulates the transcriptional activation of numerous metabolic genes in liver. In this study, gene-array analysis revealed that HNF4α overexpression increased peroxisome proliferator-activated receptorγ (PPARγ) greatly in cultured rat primary hepatocytes. PPAR-response-element-driven reporter gene expression could be elevated by HNF4α. Bioinformatics analysis revealed a high-affinity HNF4α binding site in the human PPARγ2 promoter and in vitro experiments showed that this promoter could be transactivated by HNF4α. The presence of HNF4α on the promoter was then confirmed by ChIP assay. In vivo, hepatic overexpression of HNF4α decreased cholesterol levels both in plasma and liver and several hepatic genes related to cholesterol metabolism, including scavenger receptor BI (SR-BI), were upregulated. The upregulation of SR-BI by HNF4α could be inhibited by a PPARγ antagonist in vitro. In conclusion, HNF4α regulates cholesterol metabolism in rat by modulating the expression of SR-BI in the liver, in which the upregulation of PPARγ was involved. PMID:22190905

  10. Suppression of TLR4-mediated inflammatory response by macrophage class A scavenger receptor (CD204)

    SciTech Connect

    Ohnishi, Koji; Komohara, Yoshihiro; Fujiwara, Yukio; Takemura, Kenichi; Lei, XiaoFeng; Nakagawa, Takenobu; Sakashita, Naomi; Takeya, Motohiro

    2011-08-05

    Highlights: {yields} We focused on the interaction between SR-A and TLR4 signaling in this study. {yields} SR-A deletion promoted NF{kappa}B activation in macrophages in septic model mouse. {yields} SR-A suppresses both MyD88-dependent and -independent TLR4 signaling in vitro. {yields} SR-A clears LPS binding to TLR4 which resulting in the suppression of TLR4 signals. -- Abstract: The class A scavenger receptor (SR-A, CD204), one of the principal receptors expressed on macrophages, has been found to regulate inflammatory response and attenuate septic endotoxemia. However, the detailed mechanism of this process has not yet been well characterized. To clarify the regulative mechanisms of lipopolysaccharide (LPS)-induced macrophage activation by SR-A, we evaluated the activation of Toll-like receptor 4 (TLR4)-mediated signaling molecules in SR-A-deficient (SR-A{sup -/-}) macrophages. In a septic shock model, the blood levels of tumor necrosis factor (TNF)-{alpha}, interleukin (IL)-6 and interferon (IFN)-{beta} were significantly increased in SR-A{sup -/-} mice compared to wild-type mice, and elevated nuclear factor kappa B (NF{kappa}B) activation was detected in SR-A{sup -/-} macrophages. SR-A deletion increased the production of pro-inflammatory cytokines, and the phosphorylation of mitogen-activated protein kinase (MAPK) and NF{kappa}B in vitro. SR-A deletion also promoted the nuclear translocation of NF{kappa}B and IFN regulatory factor (IRF)-3. In addition, a competitive binding assay with acetylated low-density lipoprotein, an SR-A-specific ligand, and anti-SR-A antibody induced significant activation of TLR4-mediated signaling molecules in wild-type macrophages but not in SR-A{sup -/-} macrophages. These results suggest that SR-A suppresses the macrophage activation by inhibiting the binding of LPS to TLR4 in a competitive manner and it plays a pivotal role in the regulation of the LPS-induced inflammatory response.

  11. HSL-knockout mouse testis exhibits class B scavenger receptor upregulation and disrupted lipid raft microdomains[S

    PubMed Central

    Casado, María Emilia; Huerta, Lydia; Ortiz, Ana Isabel; Pérez-Crespo, Mirian; Gutiérrez-Adán, Alfonso; Kraemer, Fredric B.; Lasunción, Miguel Ángel; Busto, Rebeca; Martín-Hidalgo, Antonia

    2012-01-01

    There is a tight relationship between fertility and changes in cholesterol metabolism during spermatogenesis. In the testis, class B scavenger receptors (SR-B) SR-BI, SR-BII, and LIMP II mediate the selective uptake of cholesterol esters from HDL, which are hydrolyzed to unesterified cholesterol by hormone-sensitive lipase (HSL). HSL is critical because HSL knockout (KO) male mice are sterile. The aim of the present work was to determine the effects of the lack of HSL in testis on the expression of SR-B, lipid raft composition, and related cell signaling pathways. HSL-KO mouse testis presented altered spermatogenesis associated with decreased sperm counts, sperm motility, and infertility. In wild-type (WT) testis, HSL is expressed in elongated spermatids; SR-BI, in Leydig cells and spermatids; SR-BII, in spermatocytes and spermatids but not in Leydig cells; and LIMP II, in Sertoli and Leydig cells. HSL knockout male mice have increased expression of class B scavenger receptors, disrupted caveolin-1 localization in lipid raft plasma membrane microdomains, and activated phospho-ERK, phospho-AKT, and phospho-SRC in the testis, suggesting that class B scavenger receptors are involved in cholesterol ester uptake for steroidogenesis and spermatogenesis in the testis. PMID:22988039

  12. The human decapping scavenger enzyme DcpS modulates microRNA turnover.

    PubMed

    Meziane, Oussama; Piquet, Sandra; Bossé, Gabriel D; Gagné, Dominic; Paquet, Eric; Robert, Claude; Tones, Michael A; Simard, Martin J

    2015-11-20

    The decapping scavenger enzyme DcpS is known for its role in hydrolyzing the cap structure following mRNA degradation. Recently, we discovered a new function in miRNA degradation activation for the ortholog of DcpS in C. elegans. Here we show that human DcpS conserves its role in miRNA turnover. In human cells, DcpS is a nucleocytoplasmic shuttling protein that activates miRNA degradation independently of its scavenger decapping activity in the cytoplasmic compartment. We also demonstrate that this new function for DcpS requires the contribution of the 5'-3' exonuclease Xrn2. Our findings support a conserved role of DcpS as a modulator of miRNA turnover in animals.

  13. The human decapping scavenger enzyme DcpS modulates microRNA turnover

    PubMed Central

    Meziane, Oussama; Piquet, Sandra; Bossé, Gabriel D.; Gagné, Dominic; Paquet, Eric; Robert, Claude; Tones, Michael A.; Simard, Martin J.

    2015-01-01

    The decapping scavenger enzyme DcpS is known for its role in hydrolyzing the cap structure following mRNA degradation. Recently, we discovered a new function in miRNA degradation activation for the ortholog of DcpS in C. elegans. Here we show that human DcpS conserves its role in miRNA turnover. In human cells, DcpS is a nucleocytoplasmic shuttling protein that activates miRNA degradation independently of its scavenger decapping activity in the cytoplasmic compartment. We also demonstrate that this new function for DcpS requires the contribution of the 5′-3′ exonuclease Xrn2. Our findings support a conserved role of DcpS as a modulator of miRNA turnover in animals. PMID:26584588

  14. Affinity of dinucleotide cap analogues for human decapping scavenger (hDcpS).

    PubMed

    Darzynkiewicz, Zbigniew M; Bojarska, Elzbieta; Stepinski, Janusz; Jemielity, Jacek; Jankowska-Anyszka, Marzena; Davis, Richard E; Darzynkiewicz, Edward

    2007-01-01

    Eukaryotic cells utilize scavenger decapping enzymes to degrade cap structure following 3'-5' mRNA decay. Human DcpS recently has been described as a highly specific hydrolase (a member of the HIT family) that catalyses the cleavage of m(7)GpppG and short capped oligoribonucleotides. We have demonstrated here that cap-1 (m(7)GpppGm) is a preferred substrate among several investigated dinucleotide cap analogues m(7)Gp(n)N (n = 3-5, N is a purine or pyrimidine base) and m(7)GMP is always one of the reaction product. Cap analogues containing pyrimidine base instead of guanine or diphosphate chain are resistant to hydrolysis catalyzed by human scavenger. Contrary to the other enzymes of HIT family, hDcpS activity is not stimulated by Mg(2+).

  15. Human presynaptic receptors.

    PubMed

    Schlicker, Eberhard; Feuerstein, Thomas

    2017-04-01

    Presynaptic receptors are sites at which transmitters, locally formed mediators or hormones inhibit or facilitate the release of a given transmitter from its axon terminals. The interest in the identification of presynaptic receptors has faded in recent years and it may therefore be justified to give an overview of their occurrence in the autonomic and central nervous system; this review will focus on presynaptic receptors in human tissues. Autoreceptors are presynaptic receptors at which a given transmitter restrains its further release, though in some instances may also increase its release. Inhibitory autoreceptors represent a typical example of a negative feedback; they are tonically activated by the respective endogenous transmitter and/or are constitutively active. Autoreceptors also play a role under pathophysiological conditions, e.g. by limiting the massive noradrenaline release occurring during congestive heart failure. They can be used for therapeutic purposes; e.g., the α2-adrenoceptor antagonist mirtazapine is used as an antidepressant and the inverse histamine H3 receptor agonist pitolisant has been marketed as a new drug for the treatment of narcolepsy in 2016. Heteroreceptors are presynaptic receptors at which transmitters from adjacent neurons, locally formed mediators (e.g. endocannabinoids) or hormones (e.g. adrenaline) can inhibit or facilitate transmitter release; they may be subject to an endogenous tone. The constipating effect of the sympathetic nervous system or of the antihypertensive drug clonidine is related to the activation of inhibitory α2-adrenoceptors on postganglionic parasympathetic neurons. Part of the stimulating effect of adrenaline on the sympathetic nervous system during stress is related to its facilitatory effect on noradrenaline release via β2-adrenoceptors.

  16. Debris buster is a Drosophila scavenger receptor essential for airway physiology.

    PubMed

    Wingen, Almut; Carrera, Pilar; Ekaterini Psathaki, Olympia; Voelzmann, André; Paululat, Achim; Hoch, Michael

    2017-10-01

    Scavenger receptors class B (SR-B) are multifunctional transmembrane proteins, which in vertebrates participate in lipid transport, pathogen clearance, lysosomal delivery and intracellular sorting. Drosophila has 14 SR-B members whose functions are still largely unknown. Here, we reveal a novel role for the SR-B family member Debris buster (Dsb) in Drosophila airway physiology. Larvae lacking dsb show yeast avoidance behavior, hypoxia, and severe growth defects associated with impaired elongation and integrity along the airways. Furthermore, in dsb mutant embryos, the barrier function of the posterior spiracles, which are critical for gas exchange, is not properly established and liquid clearance is locally impaired at the spiracular lumen. We found that Dsb is specifically expressed in a group of distal epithelial cells of the posterior spiracle organ and not throughout the entire airways. Furthermore, tissue-specific knockdown and rescue experiments demonstrate that Dsb function in the airways is only required in the posterior spiracles. Dsb localizes in intracellular vesicles, and a subset of these associate with lysosomes. However, we found that depletion of proteins involved in vesicular transport to the apical membrane, but not in lysosomal function, causes dsb-like airway elongation defects. We propose a model in which Dsb sorts components of the apical extracellular matrix which are essential for airway physiology. Since SR-B LIMP2-deficient mice show reduced expression of several apical plasma membrane proteins, sorting of proteins to the apical membrane is likely an evolutionary conserved function of Dsb and LIMP2. Our data provide insights into a spatially confined function of the SR-B Dsb in intracellular trafficking critical for the physiology of the whole tubular airway network. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Hypoxia-inducible factor-1alpha suppresses the expression of macrophage scavenger receptor 1.

    PubMed

    Shirato, Ken; Kizaki, Takako; Sakurai, Takuya; Ogasawara, Jun-Etsu; Ishibashi, Yoshinaga; Iijima, Takehiko; Okada, Chikako; Noguchi, Izumi; Imaizumi, Kazuhiko; Taniguchi, Naoyuki; Ohno, Hideki

    2009-11-01

    Macrophages are distributed in all peripheral tissues and play a critical role in the first line of the innate immune defenses against bacterial infection by phagocytosis of bacterial pathogens through the macrophage scavenger receptor 1 (MSR1). Within tissues, the partial pressure of oxygen (pO2) decreases depending on the distance of cells from the closest O2-supplying blood vessel. However, it is not clear how the expression of MSR1 in macrophages is regulated by low pO2. On the other hand, hypoxia-inducible factor (HIF)-1alpha is well known to control hypoxic responses through regulation of hypoxia-inducible genes. Therefore, we investigated the effects of hypoxia and HIF-1alpha on MSR1 expression and function in the macrophage cell line RAW264. Exposure to 1% O2 or treatment with the hypoxia-mimetic agent cobalt chloride (CoCl2) significantly suppressed the expression of MSR1 mRNA, accompanied by a markedly increase in levels of nuclear HIF-1alpha protein. The overexpression of HIF-1alpha in RAW264 cells suppressed the expression of MSR1 mRNA and protein, transcriptional activity of the MSR1 gene, and phagocytic capacity against the Gram-positive bacteria Listeria monocytogenes. The suppression of MSR1 mRNA by hypoxia or CoCl2 was inhibited by YC-1, an inhibitor of HIF-1alpha, or by the depletion of HIF-1alpha expression by small interference RNA. These results indicate that hypoxia transcriptionally suppresses MSR1 expression through HIF-1alpha.

  18. Evolutionarily conserved recognition and innate immunity to fungal pathogens by the scavenger receptors SCARF1 and CD36

    PubMed Central

    Mylonakis, Eleftherios; Tampakakis, Emmanouil; Colvin, Richard A.; Seung, Edward; Puckett, Lindsay; Tai, Melissa F.; Stewart, Cameron R.; Pukkila-Worley, Read; Hickman, Suzanne E.; Moore, Kathryn J.; Calderwood, Stephen B.; Hacohen, Nir; Luster, Andrew D.; El Khoury, Joseph

    2009-01-01

    Receptors involved in innate immunity to fungal pathogens have not been fully elucidated. We show that the Caenorhabditis elegans receptors CED-1 and C03F11.3, and their mammalian orthologues, the scavenger receptors SCARF1 and CD36, mediate host defense against two prototypic fungal pathogens, Cryptococcus neoformans and Candida albicans. CED-1 and C03F11.1 mediated antimicrobial peptide production and were necessary for nematode survival after C. neoformans infection. SCARF1 and CD36 mediated cytokine production and were required for macrophage binding to C. neoformans, and control of the infection in mice. Binding of these pathogens to SCARF1 and CD36 was β-glucan dependent. Thus, CED-1/SCARF1 and C03F11.3/CD36 are β-glucan binding receptors and define an evolutionarily conserved pathway for the innate sensing of fungal pathogens. PMID:19237602

  19. Scavenging energy from the motion of human lower limbs via a piezoelectric energy harvester

    NASA Astrophysics Data System (ADS)

    Fan, Kangqi; Yu, Bo; Zhu, Yingmin; Liu, Zhaohui; Wang, Liansong

    2017-03-01

    Scavenging energy from human motion through piezoelectric transduction has been considered as a feasible alternative to batteries for powering portable devices and realizing self-sustained devices. To date, most piezoelectric energy harvesters (PEHs) developed can only collect energy from the uni-directional mechanical vibration. This deficiency severely limits their applicability to human motion energy harvesting because the human motion involves diverse mechanical motions. In this paper, a novel PEH is proposed to harvest energy from the motion of human lower limbs. This PEH is composed of two piezoelectric cantilever beams, a sleeve and a ferromagnetic ball. The two beams are designed to sense the vibration along the tibial axis and conduct piezoelectric conversion. The ball senses the leg swing and actuates the two beams to vibrate via magnetic coupling. Theoretical and experimental studies indicate that the proposed PEH can scavenge energy from both the vibration and the swing. During each stride, the PEH can produce multiple peaks in voltage output, which is attributed to the superposition of different excitations. Moreover, the root-mean-square (RMS) voltage output of the PEH increases when the walking speed ranges from 2 to 8 km/h. In addition, the ultra-low frequencies of human motion are also up-converted by the proposed design.

  20. Iron chlorin e6 scavenges hydroxyl radical and protects human endothelial cells against hydrogen peroxide toxicity.

    PubMed

    Yu, J W; Yoon, S S; Yang, R

    2001-09-01

    Iron chlorin e6 (FeCe6) has recently been proposed to be potentially antimutagenic and antioxidative. However, the antioxidant property of FeCe6 has not been elucidated in detail. In this study, we investigated the ability of FeCe6 to scavenge hydroxyl radical and to protect biomolecules and mammalian cells from oxidative stress-mediated damage. In electron spin resonance (ESR) experiments, FeCe6 showed excellent hydroxyl radical scavenging activity, whereas its iron-deficient molecule, chlorin e6 (Ce6) showed little effect. FeCe6 also significantly reduced hydroxyl radical-induced thiobarbituric acid reactive substance (TBARS) formation and benzoate hydroxylation in a dose-dependent manner. The rate constant for reaction between FeCe6 and hydroxyl radical was measured as 8.5 x 10(10) M(-1) s(-1) by deoxyribose degradation method, and this value was much higher than that of most hydroxyl radical scavengers. Superoxide dismutase (SOD) activity of FeCe6 was also confirmed by ESR study and cytochrome c reduction assay, but its in vitro activity appeared to be less efficient in comparison with other well-known SOD mimics. In addition, FeCe6 appreciably diminished hydroxyl radical-induced DNA single-strand breakage and protein degradation in Fe-catalyzed and Cu-catalyzed Fenton systems, and it significantly protected human endothelial cells against hydrogen peroxide (H2O2) toxicity. These results suggest that FeCe6 is a novel hydroxyl radical scavenger and may be useful for preventing oxidative injury in biological systems.

  1. Role of Scavenger Receptor A and CD36 in Diet-Induced Nonalcoholic Steatohepatitis in Hyperlipidemic Mice

    PubMed Central

    BIEGHS, VEERLE; WOUTERS, KRISTIAAN; VAN GORP, PATRICK J.; GIJBELS, MARION J. J.; DE WINTHER, MENNO P. J.; BINDER, CHRISTOPH J.; LÜTJOHANN, DIETER; FEBBRAIO, MARIA; MOORE, KATHRYN J.; VAN BILSEN, MARC; HOFKER, MARTEN H.; SHIRI–SVERDLOV, RONIT

    2011-01-01

    BACKGROUND & AIMS Nonalcoholic steatohepatitis (NASH) is a disorder that consists of steatosis and hepatic inflammation. It is not known why only some people with steatosis develop NASH. Recently, we identified dietary cholesterol as a factor that directly leads to hepatic inflammation and hepatic foam cell formation. We propose a mechanism by which Kupffer cells (KCs) take up modified cholesterol-rich lipoproteins via scavenger receptors (SRs). KCs thereby accumulate cholesterol, become activated, and may then trigger an inflammatory reaction. Scavenging of modified lipoproteins mainly depends on CD36 and macrophage scavenger receptor 1. METHODS To evaluate the involvement of SR-mediated uptake of modified lipoproteins by KCs in the development of diet-induced NASH, female low-density lipoprotein receptor-deficient (Ldlr−/−) mice were lethally irradiated and transplanted with bone marrow from Msr1+/+/Cd36+/+ or Msr1−/−/Cd36−/− mice and fed a Western diet. RESULTS Macrophage and neutrophil infiltration revealed that hepatic inflammation was substantially reduced by approximately 30% in Msr1−/−/Cd36−/−-transplanted mice compared with control mice. Consistent with this, the expression levels of well-known inflammatory mediators were reduced. Apoptotis and fibro-sis were less pronounced in Msr1−/−/Cd36−/−-transplanted mice, in addition to the protective phenotype of natural antibodies against oxidized low-density lipoprotein in the plasma. Surprisingly, the effect on hepatic inflammation was independent of foam cell formation. CONCLUSIONS Targeted inactivation of SR pathways reduces the hepatic inflammation and tissue destruction associated with NASH, independent of hepatic foam cell formation. PMID:20206177

  2. Coarse grained molecular dynamics of engineered macromolecules for the inhibition of oxidized low-density lipoprotein uptake by macrophage scavenger receptors.

    PubMed

    Tomasini, Michael D; Zablocki, Kyle; Petersen, Latrisha K; Moghe, Prabhas V; Tomassone, M Silvina

    2013-08-12

    Atherosclerosis is a condition resulting from the accumulation of oxidized low-density lipoproteins (oxLDLs) in arterial walls. Previously developed macromolecules consisting of alkyl chains and polyethylene glycol (PEG) on a mucic acid backbone, termed nanolipoblockers (NLBs) are hypothesized to mitigate the uptake of oxLDL by macrophage scavenger receptors. In this work, we developed a coarse grained model to characterize the interactions between NLBs with a segment of human scavenger receptor A (SR-A), a key receptor domain that regulates cholesterol uptake and foam cell conversion of macrophages, and studied NLB ability to block oxLDL uptake in PBMC macrophages. We focused on four different NLB configurations with variable molecular charge, charge location, and degree of NLB micellization. Kinetic studies showed that three of the four NLBs form micelles within 300 ns and of sizes comparable to literature results. In the presence of SR-A, micelle-forming NLBs interacted with the receptor primarily in an aggregated state rather than as single unimers. The model showed that incorporation of an anionic charge near the NLB mucic acid head resulted in enhanced interaction with the proposed binding pocket of SR-A compared to uncharged NLBs. By contrast, NLBs with an anionic charge located at the PEG tail showed no interaction increase as NLB aggregates were predominately observed to interact away from the oxLDL binding site. Additionally, using two different methods to assess the number of contacts that each NLB type formed with SR-A, we found that the rank order of contacts coincided with our experimental flow cytometry results evaluating the ability of the different NLBs to block the uptake of oxLDL.

  3. [Ketanserin, an antagonist of 5-HT2 serotoninergic receptors and free-radical scavenger].

    PubMed

    Neri, M S; Stagnaro, S

    1992-12-01

    The authors describe an original clinical method of auscultatory percussion which is easily performed and reliable for bedside evaluation of tissue Co Q10, tissue acidosis, endothelial damage, free radicals and microcirculatory functional reserve. They report data observed in 25 arteriosclerotic patients treated with ketanserin which show the drug to be an excellent scavenger of free radicals.

  4. The class A scavenger receptor SR-A/CD204 and the class B scavenger receptor CD36 regulate immune functions of macrophages differently.

    PubMed

    Józefowski, Szczepan; Biedroń, Rafał; Sróttek, Małgorzata; Chadzińska, Magdalena; Marcinkiewicz, Janusz

    2014-11-01

    SR-A/CD204 and CD36 are major receptors responsible for oxidized lipoproteins uptake by macrophages in atherosclerotic plaques. Both receptors also share the role as receptors for different pathogens, but studies on their signaling have been hampered by the lack of selective ligands. We report that, upon specific ligation by Ab, SR-A does not induce cytokine production, but mediates inhibition of LPS-stimulated production of IL-6 and IL-12/23p40, enhancement of IL-10 release, and has no effect on TNF-α and RANTES production in murine macrophages. In contrast, anti-CD36 Ab alone stimulated production of all these cytokines, with IL-10 production being exceptionally high. Effects of anti-CD36 Ab, except of IL-10 production, were mediated by CD14 and TLR2, whereas those of SR-A ligation by heterotrimeric Gi/o proteins and by phosphatidylinositol 3-kinases. Surprisingly, we found that LPS uptake by macrophages was mediated in part by CD36 cooperating with CD14, whereas SR-A was not involved in this process. Finely, during in vitro Ag presentation to naïve CD4(+) lymphocytes, pre-incubation of macrophages with anti-CD36 Ab enhanced IFN-γ production in the co-culture, but exerted the opposite effect under conditions enabling IL-10 accumulation. In contrast, anti-SR-A Ab was ineffective alone, but reversed the Th1-polarizing effect of LPS. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  5. Hydroxyl radical scavenging mechanism of human erythrocytes by quercetin-germanium (IV) complex.

    PubMed

    Li, Sheng-Pu; Xie, Wei-Ling; Cai, Huai-Hong; Cai, Ji-Ye; Yang, Pei-Hui

    2012-08-30

    Quercetin is a popular flavonoid in plant foods, herbs, and dietary supplement. Germanium, a kind of trace elements, can enhance the body immunity. This study investigated the hydroxyl-radical-scavenging mechanism of the quercertin-germanium (IV) (Qu-Ge) complex to human erythrocytes, especially the effects on ultrastructure and mechanical properties of cell membrane, plasma membrane potential and intracellular free Ca(2+) concentration. Results showed that QuGe(2), a kind of the Qu-Ge complex, could reduce the oxidative damage of erythrocytes, change the cell-surface morphology, and partly recover the disruption of plasma membrane potential and intracellular free Ca(2+) level. Atomic force microscopy (AFM) was used to characterize the changes of the cell morphology, cell-membrane ultrastructure and biophysical properties at nanoscalar level. QuGe(2) has triggered the antioxidative factor to inhibit cellular damage. These results can improve the understanding of hydroxyl-radical-scavenging mechanism of human erythrocytes induced by the Qu-Ge complex, which can be potentially developed as a new antioxidant for treatment of oxidative damage. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  6. Scavenger Receptor-Mediated Targeted Treatment of Collagen-Induced Arthritis by Dextran Sulfate-Methotrexate Prodrug.

    PubMed

    Yang, Modi; Ding, Jianxun; Feng, Xiangru; Chang, Fei; Wang, Yinan; Gao, Zhongli; Zhuang, Xiuli; Chen, Xuesi

    2017-01-01

    Rheumatoid arthritis (RA) is a chronic autoimmune disorder implicated in multiple joint affection and even disability. The activated macrophages perform a predominant role in onset and persistence of RA. Scavenger receptor (SR), one of several receptors overexpressed on the activated macrophages, is a specific biomarker for targeted therapy of numerous chronic inflammation diseases like RA. In this work, dextran sulfate-graft-methotrexate conjugate (DS-g-MTX) is synthesized and characterized, which exhibits excellent targetability to SR on the activated RAW 264.7 cells. Additionally, the enhanced accumulation and potent inflammatory inhibition are observed in the affected joint after intravenous injection of DS-g-MTX, compared to the treatment with dextran-graft-methotrexate (Dex-g-MTX), as is confirmed by the detection of histopathology and pro-inflammatory cytokines. Our work highlights DS-g-MTX as a potential therapeutic option for RA aiming the SR-expressed activated macrophages.

  7. Scavenger Receptor-Mediated Targeted Treatment of Collagen-Induced Arthritis by Dextran Sulfate-Methotrexate Prodrug

    PubMed Central

    Yang, Modi; Ding, Jianxun; Feng, Xiangru; Chang, Fei; Wang, Yinan; Gao, Zhongli; Zhuang, Xiuli; Chen, Xuesi

    2017-01-01

    Rheumatoid arthritis (RA) is a chronic autoimmune disorder implicated in multiple joint affection and even disability. The activated macrophages perform a predominant role in onset and persistence of RA. Scavenger receptor (SR), one of several receptors overexpressed on the activated macrophages, is a specific biomarker for targeted therapy of numerous chronic inflammation diseases like RA. In this work, dextran sulfate-graft-methotrexate conjugate (DS-g-MTX) is synthesized and characterized, which exhibits excellent targetability to SR on the activated RAW 264.7 cells. Additionally, the enhanced accumulation and potent inflammatory inhibition are observed in the affected joint after intravenous injection of DS-g-MTX, compared to the treatment with dextran-graft-methotrexate (Dex-g-MTX), as is confirmed by the detection of histopathology and pro-inflammatory cytokines. Our work highlights DS-g-MTX as a potential therapeutic option for RA aiming the SR-expressed activated macrophages. PMID:28042319

  8. Scavenger receptor class B type I (SR-BI) is involved in vitamin E transport across the enterocyte.

    PubMed

    Reboul, Emmanuelle; Klein, Alexis; Bietrix, Florence; Gleize, Béatrice; Malezet-Desmoulins, Christiane; Schneider, Martina; Margotat, Alain; Lagrost, Laurent; Collet, Xavier; Borel, Patrick

    2006-02-24

    Although cellular uptake of vitamin E was initially described as a passive process, recent studies in the liver and brain have shown that SR-BI (scavenger receptor class B type I) is involved in this phenomenon. As SR-BI is expressed at high levels in the intestine, the present study addressed the involvement of SR-BI in vitamin E trafficking across enterocytes. Apical uptake and efflux of the main dietary forms of vitamin E were examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium. (R,R,R)-gamma-tocopherol bioavailability was compared between wild-type mice and mice overexpressing SR-BI in the intestine. The effect of vitamin E on enterocyte SR-BI mRNA levels was measured by real-time quantitative reverse transcription-PCR. Concentration-dependent curves for vitamin E uptake were similar for (R,R,R)-alpha-, (R,R,R)-gamma-, and dl-alpha-tocopherol. (R,R,R)-alpha-tocopherol transport was dependent on incubation temperature, with a 60% reduction in absorption at 4 degrees C compared with 37 degrees C (p < 0.05). Vitamin E flux in enterocytes was directed from the apical to the basal side, with a relative 10-fold reduction in the transfer process when measured in the opposite direction (p < 0.05). Co-incubation with cholesterol, gamma-tocopherol, or lutein significantly impaired alpha-tocopherol absorption. Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 80% of vitamin E uptake and up to 30% of apical vitamin E efflux (p < 0.05), and similar results were obtained for (R,R,R)-gamma-tocopherol. SR-BI mRNA levels were not significantly modified after a 24-h incubation of Caco-2 cells with vitamin E. Finally, (R,R,R)-gamma-tocopherol bioavailability was 2.7-fold higher in mice overexpressing SR-BI than in wild-type mice (p < 0.05). The present data show for the first time that vitamin E intestinal absorption is, at least in part, mediated by SR-BI.

  9. Tear lipocalin: evidence for a scavenging function to remove lipids from the human corneal surface.

    PubMed

    Gasymov, Oktay K; Abduragimov, Adil R; Prasher, Pawan; Yusifov, Taleh N; Glasgow, Ben J

    2005-10-01

    Lipid contamination of the cornea may create an unwettable surface and result in desiccation of the corneal epithelium. Tear lipocalin (TL), also known as lipocalin-1, is the principal lipid-binding protein in tears. TL has been shown to scavenge lipids from hydrophobic surfaces. The hypothesis that TL can remove contaminating fatty acids and phospholipids from the human corneal surface was tested. TL was purified from pooled human tear samples by size exclusion and ion exchange chromatographies. Tears depleted of TL were reconstituted from fractions eluted by size exclusion chromatography that did not contain TL. Fresh and formalin-fixed human corneas were obtained from exenteration specimens. Fluorescent analogs of either palmitic acid or phosphatidylcholine were applied to the corneal epithelial surface. Tears, TL, or tears depleted of TL were applied over the corneas, and spectrofluorometry and fluorescent stereomicroscopy were used to monitor the removal of fluorescent lipids. Tears used in the experiments were then fractionated by size exclusion chromatography to determine the component of tears associated with fluorescent lipids. Significant enhancement of fluorescence for 16AP and NBD C(6)-HPC was evident in solutions incubated with whole tears and purified TL but not with tears depleted of TL for fixed and unfixed corneas. After the experiment, size exclusion fractions of tears showed that the fluorescence component coeluted with TL. TL scavenges lipids from the human corneal surface and delivers them into the aqueous phase of tears. TL may have an important role in removing lipids from the corneal surface to maintain the wettability and integrity of the ocular surface.

  10. The Scavenger Receptor SSc5D Physically Interacts with Bacteria through the SRCR-Containing N-Terminal Domain

    PubMed Central

    Bessa Pereira, Catarina; Bocková, Markéta; Santos, Rita F.; Santos, Ana Mafalda; Martins de Araújo, Mafalda; Oliveira, Liliana; Homola, Jiří; Carmo, Alexandre M.

    2016-01-01

    The scavenger receptor cysteine-rich (SRCR) family comprises a group of membrane-attached or secreted proteins that contain one or more modules/domains structurally similar to the membrane distal domain of type I macrophage scavenger receptor. Although no all-inclusive biological function has been ascribed to the SRCR family, some of these receptors have been shown to recognize pathogen-associated molecular patterns (PAMP) of bacteria, fungi, or other microbes. SSc5D is a recently described soluble SRCR receptor produced by monocytes/macrophages and T lymphocytes, consisting of an N-terminal portion, which contains five SRCR modules, and a large C-terminal mucin-like domain. Toward establishing a global common role for SRCR domains, we interrogated whether the set of five SRCR domains of SSc5D displayed pattern recognition receptor (PRR) properties. For that purpose, we have expressed in a mammalian expression system the N-terminal SRCR-containing moiety of SSc5D (N-SSc5D), thus excluding the mucin-like domain likely by nature to bind microorganisms, and tested the capacity of the SRCR functional groups to physically interact with bacteria. Using conventional protein–bacteria binding assays, we showed that N-SSc5D had a superior capacity to bind to Escherichia coli strains RS218 and IHE3034 compared with that of the extracellular domains of the SRCR proteins CD5 and CD6 (sCD5 and sCD6, respectively), and similar E. coli-binding properties as Spα, a proven PRR of the SRCR family. We have further designed a more sensitive, real-time, and label-free surface plasmon resonance (SPR)-based assay and examined the capacity of N-SSc5D, Spα, sCD5, and sCD6 to bind to different bacteria. We demonstrated that N-SSc5D compares with Spα in the capacity to bind to E. coli and Listeria monocytogenes, and further that it can distinguish between pathogenic E. coli RS218 and IHE3034 strains and the non-pathogenic laboratory E. coli strain BL21(DE3). Our work thus advocates the

  11. Human red cells scavenge extracellular hydrogen peroxide and inhibit formation of hypochlorous acid and hydroxyl radical.

    PubMed Central

    Winterbourn, C C; Stern, A

    1987-01-01

    The ability of intact human red cells to scavenge extracellularly generated H2O2 and O2-, and to prevent formation of hydroxyl radicals and hypochlorous acid has been examined. Red cells inhibited oxidation of ferrocytochrome c by H2O2. Cells treated with aminotriazole no longer inhibited, indicating that protection was almost entirely due to intracellular catalase. Contribution by the GSH system was slight, and apparent only with low H2O2 concentrations when catalase was inhibited by aminotriazole. The cells were about a quarter as efficient at inhibiting cytochrome c oxidation as an equivalent concentration of purified catalase. No inhibition of O2(-)-dependent reduction of ferricytochrome c or nitroblue tetrazolium was observed, although extracted red cell superoxide dismutase inhibited nitroblue tetrazolium reduction at one fortieth the concentration of that in the cells. Red cells efficiently inhibited deoxyribose oxidation by hydroxyl radicals generated from H2O2, O2- and Fe(EDTA), and myeloperoxidase-dependent oxidation of methionine to methionine sulfoxide by stimulated neutrophils. Most of the red cell inhibition of hydroxyl radical production, and all the inhibition of methionine oxidation, was prevented by blocking intracellular catalase with aminotriazole. Thus red cells are able to efficiently scavenge H2O2, but not O2-, produced in their environment, and to inhibit formation of hydroxyl radicals and hypochlorous acid. They may therefore have an important role in extracellular antioxidant defense. PMID:2824562

  12. Scavenger receptor-targeted photodynamic therapy of J774 tumors in mice: tumor response and concomitant immunity

    NASA Astrophysics Data System (ADS)

    Hamblin, Michael R.; O'Donnell, David A.; Huzaira, Misbah; Zahra, Touqir

    2002-06-01

    J774 is a cell line derived from Balb/c mice that in vitro behaves as macrophages (including scavenger-receptor expression) and has been widely used to study macrophage cell biology. In vivo it produces histiocytic lymphoma tumors that are invasive and metastatic. We report here on the response of subcutaneous J774 tumors to photodynamic therapy with scavenger-receptor targeted chlorin(e6). Bovine serum albumin was covalently conjugated with chlorin(e6), maleylated and purified by acetone precipitation and both this and free chlorin(e6) were injected IV into mice at 2 mg/kg. When tumors were illuminated with 665 nm laser-light after 24 hours there was a highly significant response (tumor volume and growth rate) for the conjugate, but this led to a relatively small survival increase due to the highly metastatic nature of the tumor. The free chlorin(e6) gave very little tumor response. When light was delivered 3 hours after injection the response from the conjugate disappeared due to insufficient time for the tumor cells to take up the photosensitizer by receptor-mediated endocytosis. Free chlorin(e6) at 3 hours, however, produced a total regression of the tumors due to a primarily vascular effect, but the mice died sooner than control animals. When J774 tumors were surgically removed at different times after implantation the mouse survival was proportional to the length of time they had had the tumor. We interpret this data to show that mice with J774 tumors slowly develop concomitant immunity and a PDT regimen that swiftly ablates the tumor will give worse survival results than a regimen with a slower tumor response.

  13. Two distinct receptors account for recognition of maleyl-albumin in human monocytes during differentiation in vitro.

    PubMed Central

    Haberland, M E; Rasmussen, R R; Olch, C L; Fogelman, A M

    1986-01-01

    A comparison of the receptor-mediated interaction of malondialdehyde-low density lipoprotein and maleyl-albumin has been examined in human monocytes during differentiation in vitro. The recognition of both ligands by the scavenger receptor of these cells has been confirmed. We now report that human monocytes express a second cellular surface receptor for maleyl-albumin that is distinct from the scavenger receptor. The activity of the maleyl-albumin receptor, determined by both binding and lysosomal hydrolytic assays, substantially exceeds that of the scavenger receptor in freshly isolated monocytes. A dramatic and rapid decline in the activity of the maleyl-albumin receptor occurs within 72 to 96 h during differentiation in vitro. At day 7, while only 5-10% of the original activity of the maleyl-albumin receptor remains, it is similar to that of the maximally expressed scavenger receptor. Both the binding and hydrolysis of ligand mediated by the maleyl-albumin receptor are specifically inhibited by alpha-casein and alkaline-treated albumin; neither of these proteins is recognized by the scavenger receptor. The occurrence of the exceptionally active maleyl-albumin receptor on freshly isolated human monocytes suggests that it participates in processes necessary to the function of the cells that diminish in importance after differentiation of the monocytes into macrophages in vitro. Furthermore, while maleyl-albumin is a useful adjunct to studies of cellular events mediated by the scavenger receptor, the presence of a second receptor for maleyl-albumin must be taken into account as a potential contributing and complicating event. Images PMID:3949974

  14. Inhibition of mTOR down-regulates scavenger receptor, class B, type I (SR-BI) expression, reduces endothelial cell migration and impairs nitric oxide production.

    PubMed

    Fruhwürth, Stefanie; Krieger, Sigurd; Winter, Katharina; Rosner, Margit; Mikula, Mario; Weichhart, Thomas; Bittman, Robert; Hengstschläger, Markus; Stangl, Herbert

    2014-07-01

    The mammalian target of rapamycin (mTOR) inhibiting drug rapamycin (Sirolimus) has severe side effects in patients including hyperlipidemia, an established risk factor for atherosclerosis. Recently, it was shown that rapamycin decreases hepatic LDL receptor (LDL-R) expression, which likely contributes to hypercholesterolemia. Scavenger receptor, class B, type I (SR-BI) is the major HDL receptor and consequently regulating HDL-cholesterol levels and the athero-protective effects of HDL. By using the mTOR inhibitor rapamycin, we show that SR-BI is down-regulated in human umbilical vein endothelial cells (HUVECs). This reduction of SR-BI protein as well as mRNA levels by about 50% did not alter HDL particle uptake or HDL-derived lipid transfer. However, rapamycin reduced HDL-induced activation of eNOS and stimulation of endothelial cell migration. The effects on cell migration could be counteracted by SR-BI overexpression, indicating that decreased SR-BI expression is in part responsible for the rapamycin-induced effects. We demonstrate that inhibition of mTOR leads to endothelial cell dysfunction and decreased SR-BI expression, which may contribute to atherogenesis during rapamycin treatment.

  15. Expression Pattern of Scavenger Receptors and Amyloid-β Phagocytosis of Astrocytes and Microglia in Culture are Modified by Acidosis: Implications for Alzheimer's Disease.

    PubMed

    Eugenín, Jaime; Vecchiola, Andrea; Murgas, Paola; Arroyo, Pablo; Cornejo, Francisca; von Bernhardi, Rommy

    2016-05-30

    The pathological hallmarks of Alzheimer's disease (AD) are amyloid-β (Aβ) plaques, neurofibrillary tangles, and glia activation. The pathology also includes vascular amyloidosis and cerebrovascular disease. Vascular compromise can result in hypoperfusion, local tissue hypoxia, and acidosis. Activated microglia and astrocytes can phagocytose Aβ through membrane receptors that include scavenger receptors. Changes in glial cells induced by extracellular acidosis could play a role in the development of AD. Here, we assess whether extracellular acidosis changes glial cell properties relevant for Aβ clearance capacity. Incubation of glial cells on acidified culture medium (pH 6.9 or 6.5) for 24-48 h resulted in decreased cell diameter, with thinner branches in astrocytes, slight reduction in cell body size in microglia, a transient decrease in astrocyte adhesion to substrates, and a persistent decrease in microglia adhesion compared with control media (pH 7.4). Astrocyte Aβ phagocytosis decreased at pH 6.9 and 6.5, whereas microglia phagocytosis only transiently decreased in acidified media. Scavenger receptors class B member I (SR-BI) increased and scavenger receptors-macrophage receptors with collagenous structures (SR-MARCO) decreased in astrocytes cultured at pH 6.5. In contrast, in microglia exposed to pH 6.5, expression of SR-BI and SR-MARCO increased and fatty acid translocase (CD-36) decreased. In conclusion, the acidic environment changed the adhesiveness and morphology of both microglia and astrocytes, but only astrocytes showed a persistent decrease in Aβ clearance activity. Expression of scavenger receptors was affected differentially in microglia and astrocytes by acidosis. These changes in scavenger receptor patterns can affect the activation of glia and their contribution to neurodegeneration.

  16. Identification of neutrophil granule glycoproteins as Lewis(x)-containing ligands cleared by the scavenger receptor C-type lectin.

    PubMed

    Graham, Sarah A; Antonopoulos, Aristotelis; Hitchen, Paul G; Haslam, Stuart M; Dell, Anne; Drickamer, Kurt; Taylor, Maureen E

    2011-07-08

    The scavenger receptor C-type lectin (SRCL) is a glycan-binding receptor that has the capacity to mediate endocytosis of glycoproteins carrying terminal Lewis(x) groups (Galβ1-4(Fucα1-3)GlcNAc). A screen for glycoprotein ligands for SRCL using affinity chromatography on immobilized SRCL followed by mass spectrometry-based proteomic analysis revealed that soluble glycoproteins from secondary granules of neutrophils, including lactoferrin and matrix metalloproteinases 8 and 9, are major ligands. Binding competition and surface plasmon resonance analysis showed affinities in the low micromolar range. Comparison of SRCL binding to neutrophil and milk lactoferrin indicates that the binding is dependent on cell-specific glycosylation in the neutrophils, as the milk form of the glycoprotein is a much poorer ligand. Binding to neutrophil glycoproteins is fucose-dependent, and mass spectrometry-based glycomic analysis of neutrophil and milk lactoferrin was used to establish a correlation between high affinity binding to SRCL and the presence of multiple clustered terminal Lewis(x) groups on a heterogeneous mixture of branched glycans, some with poly N-acetyllactosamine extensions. The ability of SRCL to mediate uptake of neutrophil lactoferrin was confirmed using fibroblasts transfected with SRCL. The common presence of Lewis(x) groups in granule protein glycans can thus target granule proteins for clearance by SRCL. PCR and immunohistochemical analysis confirm that SRCL is widely expressed on endothelial cells and thus represents a distributed system that could scavenge released neutrophil glycoproteins both locally at sites of inflammation or systemically when they are released in the circulation.

  17. Inhibition of hepatic scavenger receptor-class B type I by RNA interference decreases atherosclerosis in rabbits.

    PubMed

    Demetz, Egon; Tancevski, Ivan; Duwensee, Kristina; Stanzl, Ursula; Huber, Eva; Heim, Christiane; Handle, Florian; Theurl, Markus; Schroll, Andrea; Tailleux, Anne; Dietrich, Hermann; Patsch, Josef R; Eller, Philipp; Ritsch, Andreas

    2012-06-01

    Scavenger receptor-class B type I (SR-BI), the receptor for HDL-cholesterol, plays a key role in HDL metabolism, whole body cholesterol homeostasis, and reverse cholesterol transport. We investigated the in vivo impact of hepatic SR-BI inhibition on lipoprotein metabolism and the development of atherosclerosis employing RNA interference. Small hairpin RNA plasmid specific for rabbit SR-BI was complexed with galactosylated poly-l-lysine, allowing an organ-selective, receptor-mediated gene transfer. Rabbits were fed a cholesterol-rich diet, and were injected with plasmid-complexes once a week. After 2 weeks of treatment hepatic SR-BI mRNA levels were reduced by 80% accompanied by reduced SR-BI protein levels and a modulation of the lipoprotein profile. Rabbits treated with SR-BI-specific plasmid-complexes displayed higher cholesteryl ester transfer from HDL to apoB-containing lipoproteins, lower HDL-cholesterol, and higher VLDL-cholesterol levels, when compared to controls. In a long-term study, this gene therapeutic intervention led to a similar modulation of the lipoprotein profile, to lower total cholesterol levels, and most importantly to a 50% reduction of the relative atherosclerotic lesion area. Our results are another indication that the role of SR-BI in lipoprotein metabolism and atherogenesis in rabbits--a CETP-expressing animal model displaying a manlike lipoprotein profile may be different from the one found in rodents. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  18. Pattern Recognition Scavenger Receptor A/CD204 Regulates Airway Inflammatory Homeostasis Following Organic Dust Extract Exposures

    PubMed Central

    Poole, Jill A.; Anderson, Leigh; Gleason, Angela M.; West, William W.; Romberger, Debra J.; Wyatt, Todd A.

    2014-01-01

    Exposure to agriculture organic dusts, comprised of a diversity of pathogen-associated molecular patterns, results in chronic airway diseases. The multi-functional class A macrophage scavenger receptor (SRA)/CD204 has emerged as an important class of pattern recognition receptors with broad ligand binding ability. Our objective was to determine the role of SRA in mediating repetitive and post-inflammatory organic dust extract (ODE)-induced airway inflammation. Wild-type (WT) and SRA knockout (KO) mice were intra-nasally treated with ODE or saline daily for 3 wk and immediately euthanized or allowed to recover for 1 wk. Results show that lung histopathologic changes were increased in SRA KO mice as compared to WT following repetitive ODE exposures marked predominately by increased size and distribution of lymphoid aggregates. After a 1-wk recovery from daily ODE treatments, there was significant resolution of lung injury in WT mice, but not SRA KO animals. The increased lung histopathology induced by ODE treatment was associated with decreased accumulation of neutrophils, but greater accumulation of CD4+ T-cells. The lung cytokine milieu induced by ODE was consistent with a TH1/TH17 polarization in both WT and SRA KO mice. Overall, our data demonstrate that SRA/CD204 plays an important role in the normative inflammatory lung response to ODE as evidenced by the enhanced dust-mediated injury viewed in the absence of this receptor. PMID:24491035

  19. P2X7 from j774 murine macrophages acts as a scavenger receptor for bacteria but not yeast.

    PubMed

    Pérez-Flores, Gabriela; Hernández-Silva, Cesar; Gutiérrez-Escobedo, Guadalupe; De Las Peñas, Alejandro; Castaño, Irene; Arreola, Jorge; Pérez-Cornejo, Patricia

    2016-12-02

    We studied the effects of extracellular ATP and Ca(2+) on uptake of bacteria (Staphylococcus aureus or Escherichia coli) and live yeast (Candida glabrata) by J774 macrophages to determine the role of endogenous P2X7 receptors in phagocytosis. Our findings show that phagocytosis of bio-particles coated with S. aureus or E. coli was blocked by ATP and the P2X7 receptor agonist BzATP, while yeast phagocytosis was not. A438079, an antagonist of P2X7 receptors, partially reverted the effects of ATP on bacterial phagocytosis. To determine if P2X7-mediated Ca(2+) entry into macrophages was blocking the engulfment of bacteria, we measured phagocytic activity in the absence or presence of 2 mM extracellular Ca(2+) with or without ATP. Ca(2+), in the absence of ATP, was required for engulfment of E. coli and C. glabrata but not S. aureus. Adding ATP inhibited phagocytosis of S. aureus and E. coli regardless of Ca(2+), suggesting that Ca(2+) entry was not important for inhibiting phagocytosis. On the other hand, phagocytosis of normal or hyper-adherent C. glabrata mutants had an absolute requirement for extracellular Ca(2+) due to yeast adhesion to macrophages mediated by Ca(2+)-dependent adhesion proteins. We conclude that unstimulated P2X7 from J774 cells act as scavenger receptor for the uptake of S. aureus and E. coli but not of yeast; Ca(2+) entry via P2X7 receptors play no role in phagocytosis of S. aureus and E. coli; while the effect of Ca(2+) on C. glabrata phagocytosis was mediated by the adhesins Epa1, Epa6 and Epa7.

  20. Scavenger receptor collectin placenta 1 is a novel receptor involved in the uptake of myelin by phagocytes

    PubMed Central

    Bogie, Jeroen F. J.; Mailleux, Jo; Wouters, Elien; Jorissen, Winde; Grajchen, Elien; Vanmol, Jasmine; Wouters, Kristiaan; Hellings, Niels; Van Horsen, Jack; Vanmierlo, Tim; Hendriks, Jerome J. A.

    2017-01-01

    Myelin-containing macrophages and microglia are the most abundant immune cells in active multiple sclerosis (MS) lesions. Our recent transcriptomic analysis demonstrated that collectin placenta 1 (CL-P1) is one of the most potently induced genes in macrophages after uptake of myelin. CL-P1 is a type II transmembrane protein with both a collagen-like and carbohydrate recognition domain, which plays a key role in host defense. In this study we sought to determine the dynamics of CL-P1 expression on myelin-containing phagocytes and define the role that it plays in MS lesion development. We show that myelin uptake increases the cell surface expression of CL-P1 by mouse and human macrophages, but not by primary mouse microglia in vitro. In active demyelinating MS lesions, CL-P1 immunoreactivity was localized to perivascular and parenchymal myelin-laden phagocytes. Finally, we demonstrate that CL-P1 is involved in myelin internalization as knockdown of CL-P1 markedly reduced myelin uptake. Collectively, our data indicate that CL-P1 is a novel receptor involved in myelin uptake by phagocytes and likely plays a role in MS lesion development. PMID:28317919

  1. Evidence that human Fc gamma receptor IIA (CD32) subtypes are not receptors for oxidized LDL.

    PubMed

    Morganelli, P M; Groveman, D S; Pfeiffer, J R

    1997-11-01

    Several lines of evidence suggest that clearance of oxidized LDL (oxLDL) immune complexes by macrophage IgG Fc receptors (Fc gamma Rs) plays a role in atherogenesis. Ox-LDL may also be cleared directly by Fc gamma Rs, as shown for murine Fc gamma RII-B2. In humans, the homologous Fc gamma R is Fc gamma RIIA (CD32), which is abundantly expressed on monocytes and macrophages and shares 60% sequence identity with murine Fc gamma RII-B2. As murine Fc gamma RII-B2 and human Fc gamma RIIA also share similar IgG ligand-binding properties, the purpose of this study was to test the hypothesis that human CD32 is a receptor for oxLDL. For these studies we used transfected Chinese hamster ovary (CHO) cells, monocytes, and cell lines that functionally express either of two Fc gamma RIIA subtypes (R131 or H131) and assayed binding or degradation of several preparations of oxLDL. The integrity of all oxLDL preparations was checked by studying their ability to react with CHO cells expressing human type I scavenger receptors and by other characteristics of lipoprotein oxidation. Although we showed that each preparation of oxLDL could recognize class A or class B scavenger receptors, we did not detect any differences in the binding or degradation of any type of oxLDL preparation among control versus CHO cell transfectants. Using monocytes that express Fc gamma RIIA and CD36, we showed that the binding of oxLDL was inhibited by antibodies to CD36, but not by Fc gamma RIIA antibodies. Thus, the data do not support the hypothesis that human Fc gamma RIIA is by itself a receptor for oxLDL. We conclude that human CD32 can mediate uptake of lipoprotein immune complexes, but does not mediate uptake of oxLDL in the absence of anti-oxLDL antibodies. OxLDL may interact with human mononuclear phagocytes directly via other types of receptors, such as class A and class B scavenger receptors or CD68.

  2. Design and synthesis of novel 3-substituted-indole derivatives as selective H3 receptor antagonists and potent free radical scavengers.

    PubMed

    Tang, Li; Zhao, Liying; Hong, Lingjuan; Yang, Fenyan; Sheng, Rong; Chen, Jianzhong; Shi, Ying; Zhou, Naimin; Hu, Yongzhou

    2013-10-01

    A series of novel 3-substituted-indole derivatives with a benzyl tertiary amino moiety were designed, synthesized and evaluated as H3 receptor antagonists and free radical scavengers for Alzheimer's disease therapy. Most of these synthesized compounds exhibited moderate to potent antagonistic activities in CREs driven luciferase assay. In particular, compound 2d demonstrated the most favorable H3 receptor antagonistic activity with the IC50 value of 0.049μM. Besides, it also displayed high binding affinity to H3 receptor (Ki=4.26±2.55nM) and high selectivity over other three histamine receptors. Moreover, 2d and other two 3-substituted indole derivatives 1d and 3d exerted potent ABTS radical cation scavenging capacities similar to melatonin. Above results illustrate that 2d is an interesting lead for extensive optimization to explore new drug candidate for AD therapy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Lowbush blueberries inhibit scavenger receptors CD36 and SR-A expression and attenuate foam cell formation in ApoE-deficient mice

    USDA-ARS?s Scientific Manuscript database

    Blueberries have recently been reported to reduce atherosclerotic lesion progression in apoE deficient (apoE-/-) mice. However, the underlying mechanisms are not fully understood. The objective of this study was to determine whether blueberries altered scavenger receptors expression and foam cell fo...

  4. Low-density lipoprotein receptor-related protein-1 facilitates heme scavenging after intracerebral hemorrhage in mice.

    PubMed

    Wang, Gaiqing; Manaenko, Anatol; Shao, Anwen; Ou, Yibo; Yang, Peng; Budbazar, Enkhjargal; Nowrangi, Derek; Zhang, John H; Tang, Jiping

    2017-04-01

    Heme-degradation after erythrocyte lysis plays an important role in the pathophysiology of intracerebral hemorrhage. Low-density lipoprotein receptor-related protein-1 is a receptor expressed predominately at the neurovascular interface, which facilitates the clearance of the hemopexin and heme complex. In the present study, we investigated the role of low-density lipoprotein receptor-related protein-1 in heme removal and neuroprotection in a mouse model of intracerebral hemorrhage. Endogenous low-density lipoprotein receptor-related protein-1 and hemopexin were increased in ipsilateral brain after intracerebral hemorrhage, accompanied by increased hemoglobin levels, brain water content, blood-brain barrier permeability and neurological deficits. Exogenous human recombinant low-density lipoprotein receptor-related protein-1 protein reduced hematoma volume, brain water content surrounding hematoma, blood-brain barrier permeability and improved neurological function three days after intracerebral hemorrhage. The expression of malondialdehyde, fluoro-Jade C positive cells and cleaved caspase 3 was increased three days after intracerebral hemorrhage in the ipsilateral brain tissues and decreased with recombinant low-density lipoprotein receptor-related protein-1. Intracerebral hemorrhage decreased and recombinant low-density lipoprotein receptor-related protein-1 increased the levels of superoxide dismutase 1. Low-density lipoprotein receptor-related protein-1 siRNA reduced the effect of human recombinant low-density lipoprotein receptor-related protein-1 on all outcomes measured. Collectively, our findings suggest that low-density lipoprotein receptor-related protein-1 contributed to heme clearance and blood-brain barrier protection after intracerebral hemorrhage. The use of low-density lipoprotein receptor-related protein-1 as supplement provides a novel approach to ameliorating intracerebral hemorrhage brain injury via its pleiotropic neuroprotective effects.

  5. Scavenger receptor-mediated endocytosis by sinusoidal cells in rat bone marrow

    SciTech Connect

    Geoffroy, J.S.

    1987-01-01

    Endocytosis of serum albumin by sinusoidal endothelial cells in rat bone marrow was investigated initially at the ultrastructural level with subsequent biochemical investigation of the specificity mediating this event. Bovine serum albumin adsorbed to 20nm colloidal gold particles (AuBSA) was chosen as the electron microscopic probe. Morphological data strongly suggested that a receptor was involved in uptake of AuBSA. Confirmation of receptor involvement in the uptake of AuBSA by marrow sinusoidal endothelial cells was achieved utilizing an in situ isolated hind limb perfusion protocol in conjunction with unlabeled, radiolabeled, and radio-/colloidal gold labeled probes. The major findings of competition and saturation experiments were: (1) endocytosis of AuBSA was mediated by a receptor for modified/treated serum albumin; (2) endocytosis of formaldehyde-treated serum albumin was mediated by a binding site which may be the same or closely related to the site responsible for the uptake of AuBSA; and (3) endocytosis of native untreated albumin was not mediated by receptor and probably represents fluid-phase pinocitosis.

  6. The O2-scavenging flavodiiron protein in the human parasite Giardia intestinalis.

    PubMed

    Di Matteo, Adele; Scandurra, Francesca Maria; Testa, Fabrizio; Forte, Elena; Sarti, Paolo; Brunori, Maurizio; Giuffrè, Alessandro

    2008-02-15

    The flavodiiron proteins (FDP) are widespread among strict or facultative anaerobic prokaryotes, where they are involved in the response to nitrosative and/or oxidative stress. Unexpectedly, FDPs were fairly recently identified in a restricted group of microaerobic protozoa, including Giardia intestinalis, the causative agent of the human infectious disease giardiasis. The FDP from Giardia was expressed, purified, and extensively characterized by x-ray crystallography, stopped-flow spectroscopy, respirometry, and NO amperometry. Contrary to flavorubredoxin, the FDP from Escherichia coli, the enzyme from Giardia has high O(2)-reductase activity (>40 s(-1)), but very low NO-reductase activity (approximately 0.2 s(-1)); O(2) reacts with the reduced protein quite rapidly (milliseconds) and with high affinity (K(m) < or = 2 microM), producing H(2)O. The three-dimensional structure of the oxidized protein determined at 1.9A resolution shows remarkable similarities with prokaryotic FDPs. Consistent with HPLC analysis, the enzyme is a dimer of dimers with FMN and the non-heme di-iron site topologically close at the monomer-monomer interface. Unlike the FDP from Desulfovibrio gigas, the residue His-90 is a ligand of the di-iron site, in contrast with the proposal that ligation of this histidine is crucial for a preferential specificity for NO. We propose that in G. intestinalis the primary function of FDP is to efficiently scavenge O(2), allowing this microaerobic parasite to survive in the human small intestine, thus promoting its pathogenicity.

  7. Human pancreatic cancer tumors are nutrient poor and tumor cells actively scavenge extracellular protein

    PubMed Central

    Kamphorst, Jurre J.; Nofal, Michel; Commisso, Cosimo; Hackett, Sean R.; Lu, Wenyun; Grabocka, Elda; Vander Heiden, Matthew G.; Miller, George; Drebin, Jeffrey A.; Bar-Sagi, Dafna; Thompson, Craig B.; Rabinowitz, Joshua D.

    2014-01-01

    Glucose and amino acids are key nutrients supporting cell growth. Amino acids are imported as monomers, but an alternative route induced by oncogenic KRAS involves uptake of extracellular proteins via macropinocytosis and subsequent lysosomal degradation of these proteins as a source of amino acids. In this study, we examined the metabolism of pancreatic ductal adenocarcinoma (PDAC), a poorly vascularized lethal KRAS-driven malignancy. Metabolomic comparisons of human PDAC and benign adjacent tissue revealed that tumor tissue was low in glucose, upper glycolytic intermediates, creatine phosphate and the amino acids glutamine and serine, two major metabolic substrates. Surprisingly, PDAC accumulated essential amino acids. Such accumulation could arise from extracellular proteins being degraded through macropinocytosis in quantities necessary to meet glutamine requirements, which in turn produces excess of most other amino acids. Consistent with this hypothesis, active macropinocytosis is observed in primary human PDAC specimens. Moreover, in the presence of physiological albumin, we found that cultured murine PDAC cells grow indefinitely in media lacking single essential amino acids, and replicate once in the absence of free amino acids. Growth under these conditions was characterized by simultaneous glutamine depletion and essential amino acid accumulation. Overall, our findings argue that the scavenging of extracellular proteins is an important mode of nutrient uptake in PDAC. PMID:25644265

  8. Baicalin Scavenged Reactive Oxygen Species and Protected Human Keratinocytes Against UVB-induced Cytotoxicity.

    PubMed

    Chang, Wen-Shin; Lin, En-Yuan; Hsu, Shih-Wei; Hu, Pei-Shin; Chuang, Chin-Liang; Liao, Cheng-Hsi; Fu, Chun-Kai; Su, Chung-Hao; Gong, Chi-Li; Hsiao, Chieh-Lun; Bau, DA-Tian; Tsai, Chia-Wen

    Ultraviolet B (UVB), with a wavelength of 280-320 nm, represents one of the most important environmental factors for skin disorders, including sunburn, hyperpigmentation, solar keratosis, solar elastosis and skin cancer. Therefore, protection against excessive UVA-induced damage is useful for prevention of sunburn and other human diseases. Baicalin, a major component of traditional Chinese medicine Scutellaria baicalensis, has been reported to possess antioxidant and cytostatic capacities. In this study, we examined whether baicalin is also capable of protecting human keratinocytes from UVB irradiation. The results showed that baicalin effectively scavenged reactive oxygen species (ROS) elevated within 4 h after UVB radiation and reversed the UVB-suppressed cell viability and UVB-induced apoptosis after 24 h. Our results demonstrated the utility of baicalin to complement the contributions of traditional Chinese medicine in UVB-induced damage to skin and suggested their potential application as pharmaceutical agents in long-term sun-shining injury prevention. Copyright © 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  9. Pathways for Modulating Exosome Lipids Identified By High-Density Lipoprotein-Like Nanoparticle Binding to Scavenger Receptor Type B-1.

    PubMed

    Angeloni, Nicholas L; McMahon, Kaylin M; Swaminathan, Suchitra; Plebanek, Michael P; Osman, Iman; Volpert, Olga V; Thaxton, C Shad

    2016-03-11

    Exosomes are produced by cells to mediate intercellular communication, and have been shown to perpetuate diseases, including cancer. New tools are needed to understand exosome biology, detect exosomes from specific cell types in complex biological media, and to modify exosomes. Our data demonstrate a cellular pathway whereby membrane-bound scavenger receptor type B-1 (SR-B1) in parent cells becomes incorporated into exosomes. We tailored synthetic HDL-like nanoparticles (HDL NP), high-affinity ligands for SR-B1, to carry a fluorescently labeled phospholipid. Data show SR-B1-dependent transfer of the fluorescent phospholipid from HDL NPs to exosomes. Modified exosomes are stable in serum and can be directly detected using flow cytometry. As proof-of-concept, human serum exosomes were found to express SR-B1, and HDL NPs can be used to label and isolate them. Ultimately, we discovered a natural cellular pathway and nanoparticle-receptor pair that enables exosome modulation, detection, and isolation.

  10. Scavenger receptor class B type I and the hypervariable region-1 of hepatitis C virus in cell entry and neutralisation.

    PubMed

    Dao Thi, Viet Loan; Dreux, Marlène; Cosset, François-Loïc

    2011-04-14

    Hepatitis C virus (HCV) infection is a leading cause of chronic liver disease worldwide and represents a major public health problem. Viral attachment and entry - the first encounter of the virus with the host cell - are major targets of neutralising immune responses. Thus, a detailed understanding of the HCV entry process offers interesting opportunities for the development of novel therapeutic strategies. Different cellular or soluble host factors mediate HCV entry, and considerable progress has been made in recent years to decipher how they induce HCV attachment, internalisation and membrane fusion. Among these factors, the scavenger receptor class B type I (SR-BI/SCARB1) is essential for HCV replication in vitro, through its interaction with the HCV E1E2 surface glycoproteins and, more particularly, the HVR1 segment located in the E2 protein. SR-BI is an interesting receptor because HCV, whose replication cycle intersects with lipoprotein metabolism, seems to exploit some aspects of its physiological functions, such as cholesterol transfer from high-density lipoprotein (HDL), during cell entry. SR-BI is also involved in neutralisation attenuation and therefore could be an important target for therapeutic intervention. Recent results suggest that it should be possible to identify inhibitors of the interaction of HCV with SR-BI that do not impair its important physiological properties, as discussed in this review.

  11. Chitosan oligosaccharides promote reverse cholesterol transport and expression of scavenger receptor BI and CYP7A1 in mice.

    PubMed

    Zong, Chuanlong; Yu, Yang; Song, Guohua; Luo, Tian; Li, Luqin; Wang, Xinnong; Qin, Shucun

    2012-02-01

    Chitosan oligosaccharides (COS) are beneficial in improving plasma lipids and diminishing atherosclerotic risks. In this study, we examined the effects of COS on reverse cholesterol transport (RCT) in C57BL/6 mice. (3)H-cholesterol-laden macrophages were injected intraperitoneally into mice fed with various dosage of COS (250, 500, 1000 mg/kg mouse weight, respectively) or vehicle by gastric gavages. Plasma lipid level was determined and (3)H-cholesterol was traced in plasma, liver, bile and feces. The effects of COS on hepatic cholesterol 7 alpha-hydroxylase (CYP7A1) and scavenger receptor BI (SR-BI) expression were also investigated. COS administration led to a significant decrease in plasma total cholesterol and low-density lipoprotein (LDL) cholesterol and a significant increase in peritoneal macrophage-derived (3)H-cholesterol in liver and bile as well as in feces. Liver protein expressions of CYP7A1, SR-BI and LDL receptor (LDL-R) were improved in a dosage-dependent manner in COS-administered mice. Our findings provide the first in vivo demonstration of a positive role for COS in RCT pathway and hepatic CYP7A1 and SR-BI expression in mice. Additionally, the LDL cholesterol lowering effect might be relative to hepatic LDL-R expression stimulated by COS in mice.

  12. The unfolded protein response is a negative regulator of scavenger receptor class B, type I (SR-BI) expression.

    PubMed

    Eberhart, Tanja; Eigner, Karin; Filik, Yüksel; Fruhwürth, Stefanie; Stangl, Herbert; Röhrl, Clemens

    2016-10-21

    Scavenger receptor class B, type I (SR-BI) is the main receptor for high-density lipoprotein (HDL) and an emerging atheroprotective candidate. A central function of SR-BI is the delivery of HDL-derived cholesterol to the liver for subsequent excretion into the bile. Here, we investigated the regulation of SR-BI by the unfolded protein response (UPR), an adaptive mechanism induced by endoplasmic reticulum (ER) stress, which is frequently activated in metabolic disorders. We provide evidence that induction of acute ER stress by well-characterized chemical inducers leads to decreased SR-BI expression in hepatocyte-derived cell lines. This results in a functional reduction of selective lipid uptake from HDL. However, the regulation of SR-BI by ER stress is not a direct consequence of altered cellular cholesterol metabolism. Finally, we show that SR-BI down-regulation by the UPR might be a compensatory mechanism to provide partial adaption to ER stress. The observed down-regulation of SR-BI by ER stress in hepatic cells might contribute to the unfavorable effects of metabolic disorders on cholesterol homeostasis and cardiovascular diseases.

  13. Development and application of a nonradioactive binding assay of oxidized low-density lipoprotein to macrophage scavenger receptors

    PubMed Central

    Montano, Erica N.; Boullier, Agnès; Almazan, Felicidad; Binder, Christoph J.; Witztum, Joseph L.; Hartvigsen, Karsten

    2013-01-01

    Macrophages play a key role in atherogenesis in part through excessive uptake of oxidized LDL (OxLDL) via scavenger receptors. Binding of OxLDL to macrophages has traditionally been assessed using radiolabeled OxLDL. To allow more efficient and convenient measurements, we developed a nonradioactive binding assay in which biotinylated OxLDL (Bt-OxLDL) is added to macrophages in 96-well microtiter culture plates under various conditions and the extent of binding is determined using solid phase chemiluminescent immunoassay techniques. As examples, we show that Bt-OxLDL displayed high and saturable binding to macrophages in contrast to Bt-LDL, which showed very low binding. In competition assays, unlabeled OxLDL and the anti-OxLDL monoclonal antibody E06 inhibited Bt-OxLDL binding to macrophages in a dose-dependent manner. Specific binding of Bt-OxLDL to ApoE/SR-A/CD36 triple knockout macrophages was reduced by 80% as compared with binding to macrophages from ApoE knockout mice. Binding of Bt-OxLDL to CD36 transfected COS-7 cells showed enhanced saturable binding compared with mock-transfected cells. This assay avoids the use of radioactivity and uses small amounts of materials. It can be used to study binding of OxLDL to macrophages and factors that influence this binding. The techniques described should be readily adaptable to study of other ligands, receptors, and cell types. PMID:23997238

  14. Class A scavenger receptor-mediated cell adhesion requires the sequential activation of Lyn and PI3-kinase.

    PubMed

    Nikolic, Dejan M; Cholewa, Jill; Gass, Cecelia; Gong, Ming C; Post, Steven R

    2007-04-01

    Class A scavenger receptors (SR-A) participate in multiple macrophage functions including macrophage adhesion to modified proteins. SR-A-mediated adhesion may therefore contribute to chronic inflammation by promoting macrophage accumulation at sites of protein modification. The mechanisms that couple SR-A binding to modified proteins with increased cell adhesion have not been defined. In this study, SR-A expressing HEK cells and SR-A+/+ or SR-A-/- macrophages were used to delineate the signaling pathways required for SR-A-mediated adhesion to modified protein. Inhibiting G(i/o) activation, which decreases initial SR-A-mediated cell attachment, did not prevent the subsequent spreading of attached cells. In contrast, inhibition of Src kinases or PI3-kinase abolished SR-A-dependent cell spreading without affecting SR-A-mediated cell attachment. Consistent with these results, the Src kinase Lyn and PI3-kinase were sequentially activated during SR-A-mediated cell spreading. Furthermore, activation of both Lyn and PI3-kinase was required for enhancing paxillin phosphorylation. Activation of a Src kinase-PI3-kinase-Akt pathway was also observed in cells expressing a truncated SR-A protein that does not internalize indicating that SR-A-mediated activation of intracellular signaling cascades following adhesion to MDA-BSA is independent of receptor internalization. Thus SR-A binding to modified protein activates signaling cascades that have distinct roles in regulating initial cell attachment and subsequent cell spreading.

  15. Glucose-regulated protein 78 inhibits scavenger receptor A-mediated internalization of acetylated low density lipoprotein.

    PubMed

    Ben, Jingjing; Gao, Song; Zhu, Xudong; Zheng, Yuan; Zhuang, Yan; Bai, Hui; Xu, Yong; Ji, Yong; Sha, Jiahao; He, Zhigang; Chen, Qi

    2009-11-01

    Class A scavenger receptor (SR-A) plays an important role in foam cell formation. However, the mechanism underlying the internalization of the receptor-ligand complexes remains unclear. The aim of the present study was to investigate the molecular mechanism to regulate SR-A-mediated intracellular lipid accumulation in macrophages. A pull-down assay was performed and glucose-regulated protein 78 (GRP78) was identified to bind with the cytoplasmic domain of SR-A (CSR-A). Immunoprecipitation and artificially expressed protein binding assay demonstrated the direct specific binding of GRP78 with SR-A in cells. Indirect immunofluorescence assay and western blot analysis showed their co-localization in membrane and cytoplasm. Over-expression of GRP78 specifically inhibited SR-A-mediated uptake of fluorescent acetylated low-density lipoprotein, a specific ligand for SR-A, without altering cellular SR-A expression and binding ability, and significantly inhibited cholesterol ester accumulation in cells, which can be partly attributed to the suppression of c-Jun-NH2-terminal kinase signaling pathway. These results suggest that GRP78 may act as an inhibitor of SR-A-mediated internalization of modified low-density lipoprotein into macrophages.

  16. Radical scavenger activity of phenylethanoid glycosides in FMLP stimulated human polymorphonuclear leukocytes: structure-activity relationships.

    PubMed

    Heilmann, J; Calis, I; Kirmizibekmez, H; Schühly, W; Harput, S; Sticher, O

    2000-12-01

    Radical scavenger activities of 21 phenylethanoid glycosides, including 15 ester derivatives of caffeic, ferulic, vanillic and syringic acid as well as 6 deacyl derivatives were determined by quantifying their effects on the production of reactive oxygen species (ROS) in a luminol-enhanced chemiluminescence assay with formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated human polymorphonuclear neutrophils (PMNs). All phenylethanoids acylated with phenolic acids showed strong antioxidant activity whereas the deacyl derivatives were more than 30-fold less active. Therefore, the antioxidant activity is mainly related to the number of aromatic methoxy and hydroxy groups and the structure of the acyl moiety (C6-C1 or C6-C3). In contrast, modification of the sugar chain or replacement of hydroxy groups by methoxy groups in the acyl or the phenylethanoid moiety is of minor importance. The position of the acyl moiety is without significance. Free caffeic, ferulic, vanillic and syringic acid are less active compared to the phenylethanoid derivatives. This points to the importance of dissociation and lipophilicity of these acids in a cellular test system.

  17. Polyphenols enhance total oxidant-scavenging capacities of human blood by binding to red blood cells.

    PubMed

    Koren, Erez; Kohen, Ron; Ginsburg, Isaac

    2010-06-01

    The present study offers a new look at the role of erythrocytes and of erythrocytes-polyphenol complexes as potent 'sinks' for reactive oxygen species. We hereby show that human erythrocytes have the capacity not only to carry oxygen, but also to bind avidly to their surfaces a large variety of polyphenol antioxidants, which endows upon such complexes enhanced total oxidant-scavenging capacities (TOSC). This was proven by using confocal microscopy, 2,2-diphenyl-1-picrylhydrazyl radical, Folin-Ciocalteu's reagent, cyclic voltammetry and chemiluminescence techniques. The results presented suggest that the true TOSC of blood is the sum of intracellular antioxidants of red blood cells and other blood cells (mainly due to catalase), the polyphenols bound to their surfaces and the antioxidant agents present in plasma. Since erythrocytes can avidly bind and rapidly remove circulating polyphenols, the rule of the thumb to quantify antioxidants in health and disease processes exclusively in plasma as customary in clinical settings, does not represent the true TOSC of whole blood. We also postulate that circulating erythrocytes and possibly also other blood cells might be constantly coated by polyphenols from supplemented nutrients, which act as antioxidant depots and can thus act as protectors against the harmful consequences of oxidative stress. Further studies are needed to determine the faith of polyphenols in the circulation and their sequestration in the spleen.

  18. Albumin inhibits human polymorphonuclear leucocyte luminol-dependent chemiluminescence: evidence for oxygen radical scavenging.

    PubMed Central

    Holt, M. E.; Ryall, M. E.; Campbell, A. K.

    1984-01-01

    Luminol-dependent chemiluminescence of normal human polymorphonuclear leucocytes (PMN) which were resting, or stimulated by unopsonized latex beads, opsonized zymosan or the chemotactic peptide N-formyl-met-leu-phe was decreased more than 80% in the presence of physiological concentrations of albumin (4%, w/v). This inhibition did not result from impairment of light transmission, cellular toxicity, luminol excited-state quenching or a dialysable contaminant in the albumin preparation, but was reduced by 30% when the fall induced by albumin in extracellular free Ca2+ concentration was corrected. The inhibition was most apparent in the larger second phase of the PMN chemiluminescent response to chemotactic peptide or opsonized zymosan stimulation. The smaller first phase of these responses was in fact enhanced by low concentrations of albumin (0.05-0.5%, w/v) and only inhibited up to 50% by 4% (w/v) albumin. Albumin in the range 0.1-4% (w/v) exerted a similar effect on chemiluminescence resulting from superoxide anion (O-2) and hydrogen peroxide (H2O2) production by xanthine oxidase catalysed oxidation of xanthine in the presence of luminol. We suggest that the effect of albumin on PMN luminol-dependent chemiluminescence is mediated by modification of the oxygen radical generating pathway, or oxygen radical scavenging. This previously undocumented property of the major extracellular protein requires further examination if oxygen radicals are to be established as important mediators of inflammation. PMID:6712882

  19. Luteolin decreases the UVA-induced autophagy of human skin fibroblasts by scavenging ROS

    PubMed Central

    Yan, Miaomiao; Liu, Zhongrong; Yang, Huilan; Li, Cuihua; Chen, Hulin; Liu, Yan; Zhao, Minling; Zhu, Yingjie

    2016-01-01

    Luteolin (LUT) is a flavone, which is universally present as a constituent of traditional Chinese herbs, and certain vegetables and spices, and has been demonstrated to exhibit potent radical scavenging and cytoprotective properties. Although LUT has various beneficial effects on health, the effects of LUT on the protection of skin remain to be fully elucidated. The present study investigated whether LUT can protect human skin fibroblasts (HSFs) from ultraviolet (UV) A irradiation. It was found that, following exposure to different doses of UVA irradiation, the HSFs exhibited autophagy, as observed by fluorescence and transmission electron microscopy, and reactive oxygen species (ROS) bursts, analyzed by flow cytometry, to differing degrees. Following incubation with micromolar concentrations of LUT, ROS production decreased and autophagy gradually declined. In addition, the expression of hypoxia-inducible factor-1α and the classical autophagy-associated proteins, LC3 and Beclin 1 were observed by western blotting. Western blot analysis showed that the expression levels of HIF-1α, LC3-II and Beclin 1 gradually decreased in the UVA-irradiated HSFs following treatment with LUT. These data indicated that UVA-induced autophagy was mediated by ROS, suggesting the possibility of resistance against UV by certain natural antioxidants, including LUT. PMID:27430964

  20. The scavenger receptor repertoire in six cnidarian species and its putative role in cnidarian-dinoflagellate symbiosis

    PubMed Central

    Neubauer, Emilie F.; Poole, Angela Z.; Davy, Simon K.

    2016-01-01

    Many cnidarians engage in a mutualism with endosymbiotic photosynthetic dinoflagellates that forms the basis of the coral reef ecosystem. Interpartner interaction and regulation includes involvement of the host innate immune system. Basal metazoans, including cnidarians have diverse and complex innate immune repertoires that are just beginning to be described. Scavenger receptors (SR) are a diverse superfamily of innate immunity genes that recognize a broad array of microbial ligands and participate in phagocytosis of invading microbes. The superfamily includes subclades named SR-A through SR-I that are categorized based on the arrangement of sequence domains including the scavenger receptor cysteine rich (SRCR), the C-type lectin (CTLD) and the CD36 domains. Previous functional and gene expression studies on cnidarian-dinoflagellate symbiosis have implicated SR-like proteins in interpartner communication and regulation. In this study, we characterized the SR repertoire from a combination of genomic and transcriptomic resources from six cnidarian species in the Class Anthozoa. We combined these bioinformatic analyses with functional experiments using the SR inhibitor fucoidan to explore a role for SRs in cnidarian symbiosis and immunity. Bioinformatic searches revealed a large diversity of SR-like genes that resembled SR-As, SR-Bs, SR-Es and SR-Is. SRCRs, CTLDs and CD36 domains were identified in multiple sequences in combinations that were highly homologous to vertebrate SRs as well as in proteins with novel domain combinations. Phylogenetic analyses of CD36 domains of the SR-B-like sequences from a diversity of metazoans grouped cnidarian with bilaterian sequences separate from other basal metazoans. All cnidarian sequences grouped together with moderate support in a subclade separately from bilaterian sequences. Functional experiments were carried out on the sea anemone Aiptasia pallida that engages in a symbiosis with Symbiodinium minutum (clade B1

  1. Role of the scavenger receptor in the uptake of methylamine-activated alpha 2-macroglobulin by rat liver.

    PubMed Central

    van Dijk, M C; Boers, W; Linthorst, C; van Berkel, T J

    1992-01-01

    Alpha 2-Macroglobulin (alpha 2M) requires activation by small nucleophiles (e.g. methylamine; giving alpha 2M-Me) or proteolytic enzymes (e.g. trypsin; giving alpha 2M-Tr) in order to be rapidly removed from the circulation by the liver. Separation of rat liver cells into parenchymal, endothelial and Kupffer cells at 10 min after injection indicates that liver uptake of alpha 2M-Me is shared between parenchymal and endothelial cells, with relative contributions of 51.3% and 48.3% respectively of total liver-associated radioactivity. In contrast, alpha 2M-Tr is almost exclusively taken up by the parenchymal cells (90.1% of liver-associated radioactivity). A preinjection of 5 mg of poly(inosinic acid) decreased liver uptake of alpha 2M-Me to 39.9% of the control value, while it had no effect on liver uptake of alpha 2M-Tr. It appears that poly(inosinic acid) specifically reduces the uptake of alpha 2M-Me in vivo by endothelial cells, leaving uptake by parenchymal cells unaffected. In vitro studies with isolated liver cells indicate that the association of alpha 2M-Me with endothelial cells is 21-fold higher per mg of cell protein than with parenchymal cells. The capacity of endothelial cells to degrade alpha 2M-Me appears to be 46 times higher than that of parenchymal cells. Competition studies show that poly(inosinic acid) or acetylated low-density lipoprotein effectively competes with the association of alpha 2M-Me with endothelial and Kupffer cells, but association with parenchymal cells is unaffected. It is suggested that activation of alpha 2M by methylamine induces a charge distribution on the protein which triggers specific uptake by the scavenger receptor on endothelial cells. It is concluded that the uptake of alpha 2M-Me by the scavenger receptor might function as an additional system for the uptake of activated alpha 2M. Images Fig. 11. PMID:1280102

  2. The scavenger receptor repertoire in six cnidarian species and its putative role in cnidarian-dinoflagellate symbiosis.

    PubMed

    Neubauer, Emilie F; Poole, Angela Z; Weis, Virginia M; Davy, Simon K

    2016-01-01

    Many cnidarians engage in a mutualism with endosymbiotic photosynthetic dinoflagellates that forms the basis of the coral reef ecosystem. Interpartner interaction and regulation includes involvement of the host innate immune system. Basal metazoans, including cnidarians have diverse and complex innate immune repertoires that are just beginning to be described. Scavenger receptors (SR) are a diverse superfamily of innate immunity genes that recognize a broad array of microbial ligands and participate in phagocytosis of invading microbes. The superfamily includes subclades named SR-A through SR-I that are categorized based on the arrangement of sequence domains including the scavenger receptor cysteine rich (SRCR), the C-type lectin (CTLD) and the CD36 domains. Previous functional and gene expression studies on cnidarian-dinoflagellate symbiosis have implicated SR-like proteins in interpartner communication and regulation. In this study, we characterized the SR repertoire from a combination of genomic and transcriptomic resources from six cnidarian species in the Class Anthozoa. We combined these bioinformatic analyses with functional experiments using the SR inhibitor fucoidan to explore a role for SRs in cnidarian symbiosis and immunity. Bioinformatic searches revealed a large diversity of SR-like genes that resembled SR-As, SR-Bs, SR-Es and SR-Is. SRCRs, CTLDs and CD36 domains were identified in multiple sequences in combinations that were highly homologous to vertebrate SRs as well as in proteins with novel domain combinations. Phylogenetic analyses of CD36 domains of the SR-B-like sequences from a diversity of metazoans grouped cnidarian with bilaterian sequences separate from other basal metazoans. All cnidarian sequences grouped together with moderate support in a subclade separately from bilaterian sequences. Functional experiments were carried out on the sea anemone Aiptasia pallida that engages in a symbiosis with Symbiodinium minutum (clade B1

  3. Effect of 7,8-dihydroneopterin mediated CD36 down regulation and oxidant scavenging on oxidised low-density lipoprotein induced cell death in human macrophages.

    PubMed

    Shchepetkina, Anastasia A; Hock, Barry D; Miller, Allison; Kennedy, Martin A; Gieseg, Steven P

    2017-03-26

    The role of CD36 in oxidised low-density lipoprotein (oxLDL) mediated cell death was examined by down regulating the receptor level with the macrophage generated antioxidant 7,8-dihydroneopterin. Down regulation of CD36 protein levels in human monocyte derived macrophages by 7,8-dihydroneopterin corresponded to a decrease in CD36-mRNA. The oxidation products of 7,8-dihydroneopterin, dihydroxanthopterin and neopterin did not significantly down regulate CD36. The CD36 down regulation resulted in a decrease in oxLDL uptake measured as 7-ketocholesterol accumulation. Though less oxLDL was taken up by the macrophages as a result of the 7,8-dihydroneopterin induced down regulation in CD36 levels, the cytotoxicity of the oxLDL was not decreased. Addition of 7,8-dihydroneopterin to oxLDL treated macrophages decreased the concentration of intracellular oxidants. In the presence of oxLDL, 7,8-dihydroneopterin was oxidised to neopterin showing that the 7,8-dihydroneopterin was scavenging intracellular oxidants generated in response to the oxLDL. The results show CD36 down regulation does not protect human macrophages form oxLDL cytotoxicity but 7,8-dihydroneopterin intracellular oxidant scavenging is protective.

  4. Vascular endothelial growth factor is neuroprotective against ischemic brain injury by inhibiting scavenger receptor A expression on microglia.

    PubMed

    Xu, Zheng; Han, Kaiwei; Chen, Jigang; Wang, Chunhui; Dong, Yan; Yu, Mingkun; Bai, Rulin; Huang, Chenguang; Hou, Lijun

    2017-09-01

    Vascular endothelial growth factor (VEGF) is a secreted mitogen associated with angiogenesis. VEGF has long been thought to be a potent neurotrophic factor for the survival of spinal cord neurons. However, the role of VEGF in the regulation of ischemic brain injury remains unclear. In this study, rats were subjected to MCAO (middle cerebral artery occlusion) followed by intraperitoneal injection of VEGF165 (10 mg/kg) immediately after surgery and once daily until the day 10. The expression of target genes was assayed using qPCR, western blot and immunofluorescence to investigate the role of VEGF165 in regulating ischemic brain injury. We found that VEGF165 significantly inhibited MCAO-induced up-regulation of Scavenger receptor class A (SR-A) on microglia in a VEGFR1-dependent manner. VEGF165 inhibited lipopolysaccharide (LPS)-induced expression of proinflammatory cytokines IL-1β, tumor necrosis factor alpha (TNF-α) and iNOS in microglia. More importantly, the role of VEGF165 in inhibiting neuroinflammation is partially abolished by SR-A over-expression. SR-A further reduced the protective effect of VEGF165 in ischemic brain injury. These data suggest that VEGF165 suppresses neuroinflammation and ischemic brain injury by inhibiting SR-A expression, thus offering a new target for prevention of ischemic brain injury. © 2017 International Society for Neurochemistry.

  5. Cleavage of Type I Collagen by Fibroblast Activation Protein-α Enhances Class A Scavenger Receptor Mediated Macrophage Adhesion.

    PubMed

    Mazur, Anna; Holthoff, Emily; Vadali, Shanthi; Kelly, Thomas; Post, Steven R

    2016-01-01

    Pathophysiological conditions such as fibrosis, inflammation, and tumor progression are associated with modification of the extracellular matrix (ECM). These modifications create ligands that differentially interact with cells to promote responses that drive pathological processes. Within the tumor stroma, fibroblasts are activated and increase the expression of type I collagen. In addition, activated fibroblasts specifically express fibroblast activation protein-α (FAP), a post-prolyl peptidase. Although FAP reportedly cleaves type I collagen and contributes to tumor progression, the specific pathophysiologic role of FAP is not clear. In this study, the possibility that FAP-mediated cleavage of type I collagen modulates macrophage interaction with collagen was examined using macrophage adhesion assays. Our results demonstrate that FAP selectively cleaves type I collagen resulting in increased macrophage adhesion. Increased macrophage adhesion to FAP-cleaved collagen was not affected by inhibiting integrin-mediated interactions, but was abolished in macrophages lacking the class A scavenger receptor (SR-A/CD204). Further, SR-A expressing macrophages localize with activated fibroblasts in breast tumors of MMTV-PyMT mice. Together, these results demonstrate that FAP-cleaved collagen is a substrate for SR-A-dependent macrophage adhesion, and suggest that by modifying the ECM, FAP plays a novel role in mediating communication between activated fibroblasts and macrophages.

  6. Scavenger receptor CD36 mediates uptake of high density lipoproteins in mice and by cultured cells[S

    PubMed Central

    Brundert, May; Heeren, Joerg; Merkel, Martin; Carambia, Antonella; Herkel, Johannes; Groitl, Peter; Dobner, Thomas; Ramakrishnan, Rajasekhar; Moore, Kathryn J.; Rinninger, Franz

    2011-01-01

    The mechanisms of HDL-mediated cholesterol transport from peripheral tissues to the liver are incompletely defined. Here the function of scavenger receptor cluster of differentiation 36 (CD36) for HDL uptake by the liver was investigated. CD36 knockout (KO) mice, which were the model, have a 37% increase (P = 0.008) of plasma HDL cholesterol compared with wild-type (WT) littermates. To explore the mechanism of this increase, HDL metabolism was investigated with HDL radiolabeled in the apolipoprotein (125I) and cholesteryl ester (CE, [3H]) moiety. Liver uptake of [3H] and 125I from HDL decreased in CD36 KO mice and the difference, i. e. hepatic selective CE uptake ([3H]125I), declined (–33%, P = 0.0003) in CD36 KO compared with WT mice. Hepatic HDL holo-particle uptake (125I) decreased (–29%, P = 0.0038) in CD36 KO mice. In vitro, uptake of 125I-/[3H]HDL by primary liver cells from WT or CD36 KO mice revealed a diminished HDL uptake in CD36-deficient hepatocytes. Adenovirus-mediated expression of CD36 in cells induced an increase in selective CE uptake from HDL and a stimulation of holo-particle internalization. In conclusion, CD36 plays a role in HDL uptake in mice and by cultured cells. A physiologic function of CD36 in HDL metabolism in vivo is suggested. PMID:21217164

  7. Targeting the Hemoglobin Scavenger receptor CD163 in Macrophages Highly Increases the Anti-inflammatory Potency of Dexamethasone

    PubMed Central

    Graversen, Jonas H; Svendsen, Pia; Dagnæs-Hansen, Frederik; Dal, Jakob; Anton, Gabriele; Etzerodt, Anders; Petersen, Mikkel D; Christensen, Peter A; Møller, Holger J; Moestrup, Søren K

    2012-01-01

    Synthetic glucocorticoids are potent anti-inflammatory drugs but serious side effects such as bone mobilization, muscle mass loss, immunosuppression, and metabolic alterations make glucocorticoid therapy a difficult balance. The therapeutic anti-inflammatory effect of glucocorticoids relies largely on the suppressed release of tumor-necrosis factor-α and other cytokines by macrophages at the sites of inflammation. We have now developed a new biodegradable anti-CD163 antibody-drug conjugate that specifically targets the glucocorticoid, dexamethasone to the hemoglobin scavenger receptor CD163 in macrophages. The conjugate, that in average contains four dexamethasone molecules per antibody, exhibits retained high functional affinity for CD163. In vitro studies in rat macrophages and in vivo studies of Lewis rats showed a strong anti-inflammatory effect of the conjugate measured as reduced lipopolysaccharide-induced secretion of tumor-necrosis factor-α. The in vivo potency of conjugated dexamethasone was about 50-fold that of nonconjugated dexamethasone. In contrast to a strong systemic effect of nonconjugated dexamethasone, the equipotent dose of the conjugate had no such effect, measured as thymus lymphocytes apoptosis, body weight loss, and suppression of endogenous cortisol levels. In conclusion, the study shows antibody-drug conjugates as a future approach in anti-inflammatory macrophage-directed therapy. Furthermore, the data demonstrate CD163 as an excellent macrophage target for anti-inflammatory drug delivery. PMID:22643864

  8. Characterization of Hepatitis C Virus Particle Subpopulations Reveals Multiple Usage of the Scavenger Receptor BI for Entry Steps*

    PubMed Central

    Dao Thi, Viet Loan; Granier, Christelle; Zeisel, Mirjam B.; Guérin, Maryse; Mancip, Jimmy; Granio, Ophélia; Penin, François; Lavillette, Dimitri; Bartenschlager, Ralf; Baumert, Thomas F.; Cosset, François-Loïc; Dreux, Marlène

    2012-01-01

    Hepatitis C virus (HCV) particles assemble along the very low density lipoprotein pathway and are released from hepatocytes as entities varying in their degree of lipid and apolipoprotein (apo) association as well as buoyant densities. Little is known about the cell entry pathway of these different HCV particle subpopulations, which likely occurs by regulated spatiotemporal processes involving several cell surface molecules. One of these molecules is the scavenger receptor BI (SR-BI), a receptor for high density lipoprotein that can bind to the HCV glycoprotein E2. By studying the entry properties of infectious virus subpopulations differing in their buoyant densities, we show that these HCV particles utilize SR-BI in a manifold manner. First, SR-BI mediates primary attachment of HCV particles of intermediate density to cells. These initial interactions involve apolipoproteins, such as apolipoprotein E, present on the surface of HCV particles, but not the E2 glycoprotein, suggesting that lipoprotein components in the virion act as host-derived ligands for important entry factors such as SR-BI. Second, we found that in contrast to this initial attachment, SR-BI mediates entry of HCV particles independent of their buoyant density. This function of SR-BI does not depend on E2/SR-BI interaction but relies on the lipid transfer activity of SR-BI, probably by facilitating entry steps along with other HCV entry co-factors. Finally, our results underscore a third function of SR-BI governed by specific residues in hypervariable region 1 of E2 leading to enhanced cell entry and depending on SR-BI ability to bind to E2. PMID:22767607

  9. Class A Scavenger Receptor Exacerbates Osteoclastogenesis by an Interleukin-6-Mediated Mechanism through ERK and JNK Signaling Pathways

    PubMed Central

    Guo, Shuyu; Ni, Yuanyuan; Ben, Jingjing; Xia, Yang; Zhou, Tingting; Wang, Dongyue; Ni, Jieli; Bai, Hui; Wang, Lin; Ma, Junqing; Chen, Qi

    2016-01-01

    Osteoclasts originate from bone marrow monocyte/macrophage lineage cells, which are important for bone health. Class A scavenger receptor (SR-A) is a multifunctional molecule that functions during differentiation of monocyte into macrophages and osteoclasts. To further characterize the role of SR-A in osteoclasts, we used the murine tooth movement model (TM) and the murine anterior cruciate ligament transection model of osteoarthritis (ACLT OA). In these two models the bones involved are of different origin and have different properties. Bone resorption was decreased in SR-A-/- mice compared to SR-A+/+ mice. Further evaluation showed that the number of multinucleated osteoclasts in SR-A-/- mice, compared to SR-A+/+ mice, was significantly decreased both in vivo and in vitro. The levels of interleukin-6 (IL-6) produced by osteoclasts were reduced in SR-A-/- mice compared to SR-A+/+ mice. In the in vitro marrow-derived osteoclast formation assay and in both mouse models, osteoclastogenesis was restored to normal in SR-A-/- mice by administration of recombinant murine IL-6. Moreover, neutralization of IL-6 reduced the number of osteoclasts formed in SR-A+/+ mice of TM model. Both extracellular signal-regulated kinase (ERK) and c-Jun N-terminal protein kinase (JNK), but not p38, signaling pathways were downregulated in receptor activator of nuclear factor-κB ligand (RANKL)-stimulated SR-A-/- osteoclasts. Importantly, when treated with either ERK or JNK inhibitor, the numbers of osteoclasts generated from RANKL-induced bone marrow derived-macrophages of SR-A+/+ mice, and their IL-6 production, were significantly decreased. This suggests that SR-A activates the ERK and JNK signaling pathways, and promotes production of IL-6 by osteoclasts to further stimulate osteoclast formation. PMID:27766031

  10. Scavenger receptor function of mouse FcγRIII contributes to progression of atherosclerosis in apoE hyperlipidemic mice1

    PubMed Central

    Zhu, Xinmei; Ng, Hang Pong; Lai, Yen-Chun; Craigo, Jodi K.; Nagilla, Pruthvi S.; Raghani, Pooja; Nagarajan, Shanmugam

    2014-01-01

    Recent studies showed loss of CD36 or scavenger receptor-AI/II (SR-A) does not ameliorate atherosclerosis in hyperlipidemic mouse model, suggesting receptors other than CD36 and SR-A may also contribute to atherosclerosis. In this report, we show that apoE-CD16 double knockout mice (apoE-CD16 DKO) have reduced atherosclerotic lesions compared with apoE KO mice. In vivo and in vitro foam cells analyses showed apoE-CD16 DKO macrophages accumulated less neutral lipids. Reduced foam cell formation in apoE-CD16 DKO mice is not due to change in expression of CD36, SR-A and LOX-1. This led to a hypothesis that CD16 may have scavenger receptor activity. We presented evidence that a soluble form of recombinant mouse CD16 (sCD16) bound to malondialdehyde-modified low-density lipoprotein (MDALDL), and this binding is blocked by molar excess of MDA-BSA and anti-MDA mAbs, suggesting CD16 specifically recognizes MDA epitopes. Interestingly, sCD16 inhibited MDALDL binding to macrophage cell line as well as sCD36, sSR-A and sLOX-1, indicating CD16 can cross-block MDALDL binding to other scavenger receptors. Anti-CD16 mAb inhibited IC binding to sCD16, while partially inhibited MDALDL binding to sCD16, suggesting MDALDL binding site may be in close proximity to the IC binding site in CD16. Loss of CD16 expression resulted in reduced levels of MDALDL induced pro-inflammatory cytokine expression. Finally, CD16 deficient macrophages showed reduced MDALDL-induced Syk phosphorylation. Collectively our findings suggest scavenger receptor activity of CD16 may in part contribute to the progression of atherosclerosis. PMID:25038257

  11. Prostaglandins produced during class A scavenger receptor-mediated macrophage adhesion differentially regulate cytokine production.

    PubMed

    Nikolic, Dejan M; Vadali, Shanthi; He, Beixiang; Ware, Jerry; Kelly, Thomas; Post, Steven R

    2015-05-01

    Inflammation is associated with modification of the extracellular environment, changes in cytokine expression, and the accumulation of immune cells. Such modifications create ligands that support SR-A-mediated macrophage adhesion and retention. This may be particularly important in settings, such as atherosclerosis and diabetes, as modified lipoproteins and gluc-collagen are ligands for SR-A. SR-A-mediated adhesion requires the PLA2-dependent generation of AA and its metabolism by 12/15 LOX. In contrast, the inhibition of the COX-dependent conversion of AA to PG had no effect on SR-A-mediated adhesion. In this study, macrophages were isolated from SR-A(+/+) and SR-A(-/-) mice and plated on gluc-collagen to test the hypothesis that COX-derived PGs are produced during SR-A-mediated adhesion and regulate macrophage function. SR-A-mediated binding to gluc-collagen induced a rapid but transient increase in PG production, which required the activation of PLA2 and Src kinase but not PI3K. SR-A(+/+) macrophages cultured on gluc-collagen for 24 h secreted a similar amount of TNF-α and 2.5-fold more IL-10 than SR-A(-/-) macrophages. The inhibition of COX substantially increased TNF-α production but reduced IL-10 levels in SR-A(+/+) macrophages. These effects of COX inhibition were reversed by exogenous PGE2 and mimicked by specific antagonism of the EP4 receptor. Thus, in addition to the enhancement of macrophage adhesion, SR-A binding to gluc-collagen stimulates PG production, which in turn, differentially regulates the expression of inflammatory cytokines. © Society for Leukocyte Biology.

  12. Class A scavenger receptor-mediated dsRNA internalization is independent of innate antiviral signaling and does not require PI3K activity1

    PubMed Central

    Nellimarla, Srinivas; Baid, Kaushal; Loo, Yueh-Ming; Gale, Michael; Bowdish, Dawn M.; Mossman, Karen L.

    2016-01-01

    Double-stranded RNA is a potent trigger of innate immune signaling, eliciting effects within virally infected cells and following release from dying cells. Given its inherent stability, extracellular dsRNA induces both local and systemic effects. Although the class A scavenger receptors (SR-As)3 mediate dsRNA entry, it is unknown if they contribute to signaling beyond ligand internalization. Here, we investigated if SR-As contribute to innate immune signaling independent of the classic TLR and RLR pathways. We generated a stable A549 human epithelial cell line with inducible expression of the Hepatitis C virus protease NS3/4A, which efficiently cleaves TRIF and IPS-1, adaptors for TLR3 and the RLRs respectively. Cells expressing NS3/4A as well as TLR3/MDA5/IPS-1−/− mouse embryonic fibroblasts completely lacked antiviral activity to extracellular dsRNA relative to control cells, suggesting that SR-As do not possess signaling capacity independent of TLR3 or the RLRs. Previous studies implicated PI3K signaling in SR-A-mediated activities and in downstream production of type I interferon. We found that SR-A-mediated dsRNA internalization occurs independent of PI3K activation, while downstream signaling leading to interferon production was partially dependent on PI3K activity. Overall, these findings suggest that SR-A-mediated dsRNA internalization is independent of innate antiviral signaling. PMID:26363049

  13. Antagonism of scavenger receptor CD36 by 5A peptide prevents chronic kidney disease progression in mice independent of blood pressure regulation.

    PubMed

    Souza, Ana Carolina P; Bocharov, Alexander V; Baranova, Irina N; Vishnyakova, Tatyana G; Huang, Yuning G; Wilkins, Kenneth J; Hu, Xuzhen; Street, Jonathan M; Alvarez-Prats, Alejandro; Mullick, Adam E; Patterson, Amy P; Remaley, Alan T; Eggerman, Thomas L; Yuen, Peter S T; Star, Robert A

    2016-04-01

    Scavenger receptor CD36 participates in lipid metabolism and inflammatory pathways important for cardiovascular disease and chronic kidney disease (CKD). Few pharmacological agents are available to slow the progression of CKD. However, apolipoprotein A-I-mimetic peptide 5A antagonizes CD36 in vitro. To test the efficacy of 5A, and to test the role of CD36 during CKD, we compared wild-type to CD36 knockout mice and wild-type mice treated with 5A, in a progressive CKD model that resembles human disease. Knockout and 5A-treated wild-type mice were protected from CKD progression without changes in blood pressure and had reductions in cardiovascular risk surrogate markers that are associated with CKD. Treatment with 5A did not further protect CD36 knockout mice from CKD progression, implicating CD36 as its main site of action. In a separate model of kidney fibrosis, 5A-treated wild-type mice had less macrophage infiltration and interstitial fibrosis. Peptide 5A exerted anti-inflammatory effects in the kidney and decreased renal expression of inflammasome genes. Thus, CD36 is a new therapeutic target for CKD and its associated cardiovascular risk factors. Peptide 5A may be a promising new agent to slow CKD progression.

  14. Antagonism of scavenger receptor CD36 by 5A peptide prevents chronic kidney disease progression in mice independent of blood pressure regulation

    PubMed Central

    Souza, Ana Carolina P.; Bocharov, Alexander V.; Baranova, Irina; Vishnyakova, Tatyana; Huang, Yuning G.; Wilkins, Kenneth J.; Hu, Xuzhen; Street, Jonathan M.; Alvarez-Prats, Alejandro; Mullick, Adam E.; Patterson, Amy P.; Remaley, Alan; Eggerman, Thomas L.; Yuen, Peter S.T.; Star, Robert A.

    2016-01-01

    Scavenger receptor CD36 participates in lipid metabolism and inflammatory pathways important for cardiovascular disease and chronic kidney disease (CKD). Few pharmacological agents are available to slow the progression of CKD. However, apolipoprotein AI-mimetic peptide 5A antagonizes CD36 in vitro. To test the efficacy of 5A, and to test the role of CD36 during CKD, we compared wild type to CD36 knockout mice and wild type mice treated with 5A, in a progressive CKD model that resembles human disease. Knockout and 5A-treated wild type mice were protected from CKD progression without changes in blood pressure and had reductions in cardiovascular risk surrogate markers that are associated with CKD. Treatment with 5A did not further protect CD36 knockout mice from CKD progression, implicating CD36 as its main site of action. In a separate model of kidney fibrosis, 5A-treated wild type mice had less macrophage infiltration and interstitial fibrosis. Peptide 5A exerted anti-inflammatory effects in the kidney and decreases renal expression of inflammasome genes. Thus, CD36 is a new therapeutic target for CKD and its associated cardiovascular risk factors. Peptide 5A may be a promising new agent to slow CKD progression. PMID:26994575

  15. Relationship Between Scavenger Receptors and uPA:PAI-1 and uPA Receptors in Breast Cancer

    DTIC Science & Technology

    1998-10-01

    Cell Surface Expression of LRP Methods: Confluent cell layers of tumor-derived mammary epithelial cells and a human fibrosarcoma cell line ...could be co-immunoprecipitated together. The human fibrosarcoma cells , HT1080 , were used in this procedure to optimize our co- immunoprecipitation... fibrosarcoma cell line , HT1080 . 100" M MDA-MB-231 E0 184-B5 90 0 NRK 80 70 60t M 50- " 40- LO~ 30- 20- 10-

  16. Cupric ion reducing antioxidant capacity assay for antioxidants in human serum and for hydroxyl radical scavengers.

    PubMed

    Apak, Reşat; Güçlü, Kubilay; Ozyürek, Mustafa; Bektaşoğlu, Burcu; Bener, Mustafa

    2010-01-01

    Tests measuring the combined antioxidant effect of the nonenzymatic defenses in biological fluids may be useful in providing an index of the organism's capability to counteract reactive species known as pro-oxidants, resist oxidative damage, and combat oxidative stress-related diseases. The selected chromogenic redox reagent for the assay of human serum should be easily accessible, stable, selective, and respond to all types of biologically important antioxidants such as ascorbic acid, alpha-tocopherol, beta-carotene, reduced glutathione (GSH), uric acid, and bilirubin, regardless of chemical type or hydrophilicity. Our recently developed cupric reducing antioxidant capacity (CUPRAC) spectrophotometric method for a number of polyphenols and flavonoids using the copper(II)-neocuproine reagent in ammonium acetate buffer is now applied to a complete series of plasma antioxidants for the assay of total antioxidant capacity of serum, and the resulting absorbance at 450 nm is recorded either directly (e.g., for ascorbic acid, alpha-tocopherol, and glutathione) or after incubation at 50 degrees C for 20 min (e.g., for uric acid, bilirubin, and albumin), quantitation being made by means of a calibration curve. The lipophilic antioxidants, alpha-tocopherol and beta-carotene, are assayed in dichloromethane. Lipophilic antioxidants of serum are extracted with n-hexane from an ethanolic solution of serum subjected to centrifugation. Hydrophilic antioxidants of serum are assayed in the centrifugate after perchloric acid precipitation of proteins. The CUPRAC molar absorptivities, linear ranges, and TEAC (trolox equivalent antioxidant capacity) coefficients of the serum antioxidants are established, and the results are evaluated in comparison with the findings of the ABTS/TEAC reference method. The intra- and inter-assay coefficients of variation (CVs) are 0.7 and 1.5%, respectively, for serum. The CUPRAC assay proved to be efficient for glutathione and thiol-type antioxidants

  17. Silencing of the scavenger receptor (Class B - Type 1) gene using siRNA-loaded chitosan nanaoparticles in a HepG2 cell model.

    PubMed

    Farid, Mariane M; Hathout, Rania M; Fawzy, Mahmoud; Abou-Aisha, Khaled

    2014-11-01

    Gene silencing mediated by small interfering RNA (siRNA) has gained increasing interest through the past few decades. However, the partial negative charge and the susceptibility to degradation by nucleases have hampered its use in a naked form. In this study, we investigated the use of chitosan nanoparticles as non-viral delivery carriers of siRNA. As a model target, we selected the scavenger receptor (SR-B1), due to its proposed involvement in hepatitis C virus (HCV) internalization. Low molecular weight (LMW) chitosan nanoparticles were prepared by simple ionic gelation using sodium tripolyphosphate (TPP) as a cross-linking agent; a fixed chitosan and TPP concentration of 0.1% was used, and a chitosan to TPP weight ratios of 3:1, 5:1, and 9:1 were investigated. Nanoparticle uptake efficiency was measured using FITC-labeled chitosan nanoparticles and silencing of scavenger receptor class B type 1 (SR-B1) in HepG2 cell line was tested using Western blot analysis. Nanoparticles produced were spherical in shape with an optimum particle size and distribution. The uptake of FITC-labeled nanoparticles by HepG2 cells was found to be both concentration and time dependent. Furthermore, Western Blot analysis showed that SR-B1 siRNA was able to silence the scavenger receptor for up to 96 h of incubation with HepG2 cells.

  18. Extra-epitopic hepatitis C virus polymorphisms confer resistance to broadly neutralizing antibodies by modulating binding to scavenger receptor B1.

    PubMed

    El-Diwany, Ramy; Cohen, Valerie J; Mankowski, Madeleine C; Wasilewski, Lisa N; Brady, Jillian K; Snider, Anna E; Osburn, William O; Murrell, Ben; Ray, Stuart C; Bailey, Justin R

    2017-02-01

    Broadly-neutralizing monoclonal antibodies (bNAbs) may guide vaccine development for highly variable viruses including hepatitis C virus (HCV), since they target conserved viral epitopes that could serve as vaccine antigens. However, HCV resistance to bNAbs could reduce the efficacy of a vaccine. HC33.4 and AR4A are two of the most potent anti-HCV human bNAbs characterized to date, binding to highly conserved epitopes near the amino- and carboxy-terminus of HCV envelope (E2) protein, respectively. Given their distinct epitopes, it was surprising that these bNAbs showed similar neutralization profiles across a panel of natural HCV isolates, suggesting that some viral polymorphisms may confer resistance to both bNAbs. To investigate this resistance, we developed a large, diverse panel of natural HCV envelope variants and a novel computational method to identify bNAb resistance polymorphisms in envelope proteins (E1 and E2). By measuring neutralization of a panel of HCV pseudoparticles by 10 μg/mL of each bNAb, we identified E1E2 variants with resistance to one or both bNAbs, despite 100% conservation of the AR4A binding epitope across the panel. We discovered polymorphisms outside of either binding epitope that modulate resistance to both bNAbs by altering E2 binding to the HCV co-receptor, scavenger receptor B1 (SR-B1). This study is focused on a mode of neutralization escape not addressed by conventional analysis of epitope conservation, highlighting the contribution of extra-epitopic polymorphisms to bNAb resistance and presenting a novel mechanism by which HCV might persist even in the face of an antibody response targeting multiple conserved epitopes.

  19. Extra-epitopic hepatitis C virus polymorphisms confer resistance to broadly neutralizing antibodies by modulating binding to scavenger receptor B1

    PubMed Central

    El-Diwany, Ramy; Mankowski, Madeleine C.; Wasilewski, Lisa N.; Brady, Jillian K.; Snider, Anna E.; Osburn, William O.; Murrell, Ben; Ray, Stuart C.

    2017-01-01

    Broadly-neutralizing monoclonal antibodies (bNAbs) may guide vaccine development for highly variable viruses including hepatitis C virus (HCV), since they target conserved viral epitopes that could serve as vaccine antigens. However, HCV resistance to bNAbs could reduce the efficacy of a vaccine. HC33.4 and AR4A are two of the most potent anti-HCV human bNAbs characterized to date, binding to highly conserved epitopes near the amino- and carboxy-terminus of HCV envelope (E2) protein, respectively. Given their distinct epitopes, it was surprising that these bNAbs showed similar neutralization profiles across a panel of natural HCV isolates, suggesting that some viral polymorphisms may confer resistance to both bNAbs. To investigate this resistance, we developed a large, diverse panel of natural HCV envelope variants and a novel computational method to identify bNAb resistance polymorphisms in envelope proteins (E1 and E2). By measuring neutralization of a panel of HCV pseudoparticles by 10 μg/mL of each bNAb, we identified E1E2 variants with resistance to one or both bNAbs, despite 100% conservation of the AR4A binding epitope across the panel. We discovered polymorphisms outside of either binding epitope that modulate resistance to both bNAbs by altering E2 binding to the HCV co-receptor, scavenger receptor B1 (SR-B1). This study is focused on a mode of neutralization escape not addressed by conventional analysis of epitope conservation, highlighting the contribution of extra-epitopic polymorphisms to bNAb resistance and presenting a novel mechanism by which HCV might persist even in the face of an antibody response targeting multiple conserved epitopes. PMID:28235087

  20. Antioxidant capacity and radical scavenging effect of polyphenol rich Mallotus philippenensis fruit extract on human erythrocytes: an in vitro study.

    PubMed

    Gangwar, Mayank; Gautam, Manish Kumar; Sharma, Amit Kumar; Tripathi, Yamini B; Goel, R K; Nath, Gopal

    2014-01-01

    Mallotus philippinensis is an important source of molecules with strong antioxidant activity widely used medicinal plant. Previous studies have highlighted their anticestodal, antibacterial, wound healing activities, and so forth. So, present investigation was designed to evaluate the total antioxidant activity and radical scavenging effect of 50% ethanol fruit glandular hair extract (MPE) and its role on Human Erythrocytes. MPE was tested for phytochemical test followed by its HPLC analysis. Standard antioxidant assays like DPPH, ABTS, hydroxyl, superoxide radical, nitric oxide, and lipid peroxidation assay were determined along with total phenolic and flavonoids content. Results showed that MPE contains the presence of various phytochemicals, with high total phenolic and flavonoid content. HPLC analysis showed the presence of rottlerin, a polyphenolic compound in a very rich quantity. MPE exhibits significant strong scavenging activity on DPPH and ABTS assay. Reducing power showed dose dependent increase in concentration absorption compared to standard, Quercetin. Superoxide, hydroxyl radical, lipid peroxidation, nitric oxide assay showed a comparable scavenging activity compared to its standard. Our finding further provides evidence that Mallotus fruit extract is a potential natural source of antioxidants which have a protective role on human Erythrocytes exhibiting minimum hemolytic activity and this justified its uses in folklore medicines.

  1. Antioxidant Capacity and Radical Scavenging Effect of Polyphenol Rich Mallotus philippenensis Fruit Extract on Human Erythrocytes: An In Vitro Study

    PubMed Central

    Gautam, Manish Kumar; Sharma, Amit Kumar; Tripathi, Yamini B.; Goel, R. K.; Nath, Gopal

    2014-01-01

    Mallotus philippinensis is an important source of molecules with strong antioxidant activity widely used medicinal plant. Previous studies have highlighted their anticestodal, antibacterial, wound healing activities, and so forth. So, present investigation was designed to evaluate the total antioxidant activity and radical scavenging effect of 50% ethanol fruit glandular hair extract (MPE) and its role on Human Erythrocytes. MPE was tested for phytochemical test followed by its HPLC analysis. Standard antioxidant assays like DPPH, ABTS, hydroxyl, superoxide radical, nitric oxide, and lipid peroxidation assay were determined along with total phenolic and flavonoids content. Results showed that MPE contains the presence of various phytochemicals, with high total phenolic and flavonoid content. HPLC analysis showed the presence of rottlerin, a polyphenolic compound in a very rich quantity. MPE exhibits significant strong scavenging activity on DPPH and ABTS assay. Reducing power showed dose dependent increase in concentration absorption compared to standard, Quercetin. Superoxide, hydroxyl radical, lipid peroxidation, nitric oxide assay showed a comparable scavenging activity compared to its standard. Our finding further provides evidence that Mallotus fruit extract is a potential natural source of antioxidants which have a protective role on human Erythrocytes exhibiting minimum hemolytic activity and this justified its uses in folklore medicines. PMID:25525615

  2. Relationship between expression levels and atherogenesis in scavenger receptor Class B, Type I Transgenics

    SciTech Connect

    Ueda, Yukihiko; Gong, Elaine; Royer, Lori; Cooper, Philip N.; Francone, Omar L; Rubin, Edward M.

    2000-03-15

    Both in vitro and in vivo studies of SR-BI have implicated it as a likely participant in the metabolism of HDL cholesterol. To investigate SR-BI's effect on atherogenesis we examined two lines of SR-BI transgenic mice with high (10-fold increases) and low (2-fold increases) in SR-BI expression in an inbred mouse background hemizygous for a human apo B transgene. Unlike non-HDL cholesterol levels which minimally differed in the various groups of animals, HDL cholesterol levels were inversely related to SR-BI expression. Mice with the low expression SR-BI transgene had a 50% reduction in HDL cholesterol while the high expression SR-BI transgene was associated with two-fold decreases in HDL as well as dramatic alterations in HDL composition and size including the near absence of a-migrating particles as determined by 2-dimensional electrophoresis. The low expression SR-BI/apo B transgenics had more than a two-fold decrease in the development of diet induced fatty streak lesions compared t o the apo B transgenics (4448{+-}1908 {mu}m2/aorta to 10133 {+-} 4035 {mu}m2/aorta; p<0.001), while the high expression SR-BI/apo B transgenics had an atherogenic response similar to that of the apo B transgenics (14692{+-}7238 {mu}m2/aorta) but three-fold greater than the low SR-BI/apo B mice (p<0.001). The prominent anti-atherogenic effect of moderate SR-BI expression provides in vivo support for the hypothesis that HDL functions to inhibit atherogenesis through its interactions with SR-BI in facilitating reverse cholesterol transport. The failure of the high SR-BI/apo B transgenics to have similar or even greater reductions in atherogenesis suggests that the changes resulting from extremely high SR-BI expression including dramatic changes in lipoproteins may have both pro- and anti-atherogenic consequences illustrating the complexity of the relationship between SR-BI and atherogenesis.

  3. Hepatic lipase promotes the selective uptake of high density lipoprotein-cholesteryl esters via the scavenger receptor B1.

    PubMed

    Lambert, G; Chase, M B; Dugi, K; Bensadoun, A; Brewer, H B; Santamarina-Fojo, S

    1999-07-01

    Hepatic lipase (HL) plays a major role in high-density lipoprotein (HDL) metabolism both as a lipolytic enzyme and as a ligand. To investigate whether HL enhances the uptake of HDL-cholesteryl ester (CE) via the newly described scavenger receptor BI (SR-BI), we measured the effects of expressing HL and SR-BI on HDL-cell association as well as uptake of 125I-labeled apoA-I and [3H]CE-HDL, by embryonal kidney 293 cells. As expected, HDL cell association and CE selective uptake were increased in SR-BI transfected cells by 2- and 4-fold, respectively, compared to controls (P < 0.001). Cells transfected with HL alone or in combination with SR-BI expressed similar amounts of HL, 20% of which was bound to cell surface proteoglycans. HL alone increased HDL cell association by 2-fold but had no effect on HDL-CE uptake in 293 cells. However, in cells expressing SR-BI, HL further enhanced the selective uptake of CE from HDL by 3-fold (P < 0.001). To determine whether the lipolytic and/or ligand function of HL are required in this process, we generated a catalytically inactive form of HL (HL-145G). Cells co-transfected with HL-145G and SR-BI increased their HDL cell association and HDL-CE selective uptake by 1.4-fold compared to cells expressing SR-BI only (P < 0.03). Heparin abolished the effect of HL-145G on SR-BI-mediated HDL-CE selective uptake.Thus, the enhanced uptake of HDL-CE by HL is mediated by both its ligand role, which requires interaction with proteoglycans, and by lipolysis with subsequent HDL particle remodeling. These results establish HL as a major modulator of SR-BI mediated selective uptake of HDL-CE.

  4. Regulation of smooth muscle cell scavenger receptor expression in vivo by atherogenic diets and in vitro by cytokines.

    PubMed Central

    Li, H; Freeman, M W; Libby, P

    1995-01-01

    Scavenger receptor (ScR)-mediated uptake of modified lipoproteins may contribute to the transformation of smooth muscle cells into lipid-laden foam cells during atherogenesis. This study examined the in vivo expression of ScRs in aortas, with or without balloon injury, taken from hypercholesterolemic or normocholesterolemic rabbits. Numerous intimal cells in the rabbit aortic lesions expressed ScRs as detected by immunocytochemical staining with a goat anti-rabbit ScR antibody. Single immunostaining for cell identification markers in serial sections, as well as double staining, confirmed the expression of ScRs by both intimal smooth muscle cells and macrophages. To explore potential inducers of ScR expression by smooth muscle cells in vivo, we studied the regulation of ScR expression in vitro by cytokines known to be present in atherosclerotic lesions. Tumor necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-gamma) increased ScR mRNA levels, protein expression, and AcLDL degradative activity in cultured rabbit aortic smooth muscle cells. The induction of ScR expression in intimal smooth muscle cells in vivo could be a useful marker of smooth muscle cell activation during atherogenesis and may contribute to foam cell formation by this cell type following balloon injury and/or hypercholesterolemia. Cytokines, such as TNF-alpha or IFN-gamma, may stimulate some of the phenotypic changes that characterize the alteration in gene expression of intimal smooth muscle cells in rabbit atherosclerotic lesions. Images PMID:7814605

  5. Effect of scavenger receptor BI antagonist ITX5061 in patients with hepatitis C virus infection undergoing liver transplantation

    PubMed Central

    Rowe, Ian A; Tully, Damien C; Armstrong, Matthew J; Parker, Richard; Guo, Kathy; Barton, Darren; Morse, Gene D; Venuto, Charles S; Ogilvie, Colin B; Hedegaard, Ditte L; McKelvy, Jeffrey F; Wong-Staal, Flossie; Allen, Todd M; Balfe, Peter; McKeating, Jane A; Mutimer., David J

    2016-01-01

    Hepatitis C virus (HCV) entry inhibitors have been hypothesized to prevent infection of the liver after transplantation. ITX5061 is a Scavenger Receptor B-I (SR-BI) antagonist that blocks HCV entry and infection in vitro. We assessed the safety and efficacy of ITX5061 to limit HCV infection of the graft. The study included 23 HCV infected patients undergoing liver transplantation. The first 13 “control” patients did not receive drug. The subsequent 10 patients received ITX5061 150 mg immediately pre- and post-transplant, and daily for 1 week thereafter. ITX5061 pharmacokinetics and plasma HCV RNA were quantified. Viral genetic diversity was measured by ultradeep pyrosequencing. ITX5061 was well tolerated with measurable plasma concentrations during therapy. Whilst the median HCV RNA reduction was greater in ITX treated patients at all time points in the first week after transplantation there was no difference in the overall change in the area over the HCV RNA curve in the 7-day treatment period. However, in genotype 1 infected patients treatment was associated with a sustained reduction in HCV RNA levels compared to the control group (area over the HCV RNA curve analysis, p=0.004). Ultradeep pyrosequencing revealed a complex and evolving pattern of HCV variants infecting the graft during the first week. ITX5061 significantly limited viral evolution where the median divergence between day 0 and day 7 was 3.5% in the control group compared to 0.1% in the treated group. Conclusions ITX5061 reduces plasma HCV RNA post transplant notably in genotype 1 infected patients and slows viral evolution. Following liver transplantation the likely contribution of extrahepatic reservoirs of HCV necessitates combining entry inhibitors such as ITX5061 with inhibitors of replication in future studies. PMID:26437376

  6. Liver growth factor induces testicular regeneration in EDS-treated rats and increases protein levels of class B scavenger receptors.

    PubMed

    Lobo, M V T; Arenas, M I; Huerta, L; Sacristán, S; Pérez-Crespo, M; Gutiérrez-Adán, A; Díaz-Gil, J J; Lasunción, M A; Martín-Hidalgo, A

    2015-01-15

    The aim of the present work was to determine the effects of liver growth factor (LGF) on the regeneration process of rat testes after chemical castration induced by ethane dimethanesulfonate (EDS) by analyzing some of the most relevant proteins involved in cholesterol metabolism, such as hormone sensitive lipase (HSL), 3β-hydroxysteroid dehydrogenase (3β-HSD), scavenger receptor SR-BI, and other components of the SR family that could contribute to the recovery of steroidogenesis and spermatogenesis in the testis. Sixty male rats were randomized to nontreated (controls) and LGF-treated, EDS-treated, and EDS + LGF-treated groups. Testes were obtained on days 10 (T1), 21 (T2), and 35 (T3) after EDS treatment, embedded in paraffin, and analyzed by immunohistochemistry and Western blot. LGF improved the recovery of the seminiferous epithelia, the appearance of the mature pattern of Leydig cell interstitial distribution, and the expression of mature SR-BI. Moreover, LGF treatment resulted in partial recovery of HSL expression in Leydig cells and spermatogonia. No changes in serum testosterone were observed in control or LGF-treated rats, but in EDS-castrated animals LGF treatment induced a progressive increase in serum testosterone levels and 3β-HSD expression. Based on the pivotal role of SR-BI in the uptake of cholesteryl esters from HDL, it is suggested that the observed effects of LGF would facilitate the provision of cholesterol for sperm cell growth and Leydig cell recovery. Copyright © 2015 the American Physiological Society.

  7. Serum levels of the soluble haemoglobin scavenger receptor CD163 in MPO-ANCA-associated renal vasculitis.

    PubMed

    Nagai, M; Hirayama, K; Ebihara, I; Higuchi, T; Shimohata, H; Kobayashi, M

    2016-10-01

    The contribution of infections to the mortality of patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is important, and early and careful infection control is necessary. We investigated the usefulness of the serum-soluble haemoglobin scavenger receptor CD163 for detecting the presence of infectious complications regardless of disease activity. Soluble CD163 in serum obtained from 45 Japanese patients with myeloperoxidase (MPO)-AAV was measured by an enzyme-linked immunosorbent assay (ELISA). We evaluated 36 samples from active-vasculitis patients, 36 samples from inactive-vasculitis patients without infection, and 19 samples from inactive-vasculitis patients with infectious complications. Serum-soluble CD163 was also measured in 15 infectious patients without vasculitis and in 30 normal controls. The mean serum-soluble CD163 level was higher in the patients with infectious complications than in the active-vasculitis patients, inactive-vasculitis patients, and normal controls. There were significant positive correlations between serum-soluble CD163 levels and white blood cell (WBC) count, serum C-reactive protein (CRP) levels, and serum albumin levels, but only serum CRP levels were correlated with serum-soluble CD163 levels in a multiple regression analysis. On the receiver-operating characteristic (ROC) curve, serum-soluble CD163 levels had 80.6% sensitivity and 86.7% specificity for differentiating patients with infection from those without infection. Among the active-vasculitis patients, the mean serum-soluble CD163 level of the patients with alveolar haemorrhage was significantly lower than that of the patients with interstitial lung diseases and that of the patients without pulmonary lesions. The serum-soluble CD163 level may be a useful marker for the detection of infectious complications in MPO-AAV patients.

  8. Expression and regulation of scavenger receptor class B type 1 in the rat ovary and uterus during the estrous cycle.

    PubMed

    Wang, Yalei; Meng, Chenling; Wei, Quanwei; Shi, Fangxiong; Mao, Dagan

    2015-04-01

    Scavenger receptor class B type 1 (SR-B1) preferentially mediates the selective uptake of high density lipoprotein-cholesterol ester and the delivery of cholesterol for steroidogenesis. Although multiple analyses have investigated the function of SR-B1 in the liver, adrenal and ovary, its expression in rat ovary and uterus during the estrous cycle is lacking. In the present study, real-time PCR, western blot and immunohistochemistry (IHC) were used to investigate SR-B1 expression in the rat ovary and uterus during the estrous cycle. The results demonstrated that ovarian SR-B1 expression was in a stage-dependent manner, continuously increased from proestrus and kept elevated during metoestrus, while uterine SR-B1 expression decreased from proestrus to diestrus. To determine whether ovarian and uterine SR-B1 expression were affected by sex steroid hormones, immature rats were treated with 17 β-estradiol (E2), progesterone (P4), or their antagonists from postnatal days 24-26. Results showed that the levels of SR-B1 mRNA and protein were significantly up-regulated by E2 in both the ovary and uterus. IHC results showed that SR-B1 was primarily localized in the oocytes, theca internal cells (T-I) of follicles, interstitial cells (IC) as well as corpus luteum (CL), but not granulosa cells (GC) in the ovary during the estrous cycle. Uterine SR-B1 was highly expressed in the endometrial luminal epithelial cells (LEC) and glandular epithelial cells (GEC) as well as in the circular muscle (CM) cells, and weak staining in stromal cells (SC) through estrous cycle. Taken together, SR-B1 expression in the ovary and uterus across the estrous cycle demonstrate that SR-B1 may be involved in uterine function, follicular development as well as luteal function. Copyright © 2015 Elsevier GmbH. All rights reserved.

  9. Cholesterol, ganglioside GM1 and class A scavenger receptor contribute to infection by Brucella ovis and Brucella canis in murine macrophages.

    PubMed

    Martín-Martín, Ana I; Vizcaíno, Nieves; Fernández-Lago, Luis

    2010-03-01

    The establishment of infection by Brucella ovis and Brucella canis in J774.A1 macrophages was found to be dependent upon cholesterol and ganglioside GM(1), two components of lipid rafts. This process also required a class A scavenger receptor of macrophages, and was not inhibited by smooth and rough lipopolysaccharides from Brucella spp. In response to infection, both bacteria induced a weak degree of macrophage activation. These results demonstrate that B. ovis and B. canis use cell surface receptors common to smooth Brucella spp. for macrophage infection, thus limiting macrophage activation and favouring intracellular multiplication and/or the survival of both bacteria. Copyright 2010 Elsevier Masson SAS. All rights reserved.

  10. Adverse Signaling of Scavenger Receptor Class B1 and PGC1s in Alcoholic Hepatosteatosis and Steatohepatitis and Protection by Betaine in Rat

    PubMed Central

    Varatharajalu, Ravi; Garige, Mamatha; Leckey, Leslie C.; Arellanes-Robledo, Jaime; Reyes-Gordillo, Karina; Shah, Ruchi; Lakshman, M. Raj

    2015-01-01

    Because scavenger receptor class B type 1 is the cholesterol uptake liver receptor, whereas peroxisome proliferator–activated receptor γ coactivator-1β (PGC-1β) and PGC-1α are critical for lipid synthesis and degradation, we investigated the roles of these signaling molecules in the actions of ethanol-polyunsaturated fatty acids and betaine on hepatosteatosis and steatohepatitis. Ethanol-polyunsaturated fatty acid treatment caused the following: i) hepatosteatosis, as evidenced by increased liver cholesterol and triglycerides, lipid score, and decreased serum adiponectin; ii) marked inhibition of scavenger receptor class B type 1 glycosylation, its plasma membrane localization, and its hepatic cholesterol uptake function; and iii) moderate steatohepatitis, as evidenced by histopathological characteristics, increased liver tumor necrosis factor α and IL-6, decreased glutathione, and elevated serum alanine aminotransferase. These actions of ethanol involved up-regulated PGC-1β, sterol regulatory element-binding proteins 1c and 2, acetyl-CoA carboxylase, and HMG-CoA reductase mRNAs/proteins and inactive non-phosphorylated AMP kinase; and down-regulated silence regulator gene 1 and PGC-1α mRNA/proteins and hepatic fatty acid oxidation. Betaine markedly blunted all these actions of ethanol on hepatosteatosis and steatohepatitis. Therefore, we conclude that ethanol-mediated impaired post-translational modification, trafficking, and function of scavenger receptor class B type 1 may account for alcoholic hyperlipidemia. Up-regulation of PGC-1β and lipid synthetic genes and down-regulation of silence regulator gene 1, PGC-1α, adiponectin, and lipid degradation genes account for alcoholic hepatosteatosis. Induction of proinflammatory cytokines and depletion of endogenous antioxidant, glutathione, account for alcoholic steatohepatitis. We suggest betaine as a potential therapeutic agent because it effectively protects against adverse actions of ethanol. PMID

  11. Adverse signaling of scavenger receptor class B1 and PGC1s in alcoholic hepatosteatosis and steatohepatitis and protection by betaine in rat.

    PubMed

    Varatharajalu, Ravi; Garige, Mamatha; Leckey, Leslie C; Arellanes-Robledo, Jaime; Reyes-Gordillo, Karina; Shah, Ruchi; Lakshman, M Raj

    2014-07-01

    Because scavenger receptor class B type 1 is the cholesterol uptake liver receptor, whereas peroxisome proliferator-activated receptor γ coactivator-1β (PGC-1β) and PGC-1α are critical for lipid synthesis and degradation, we investigated the roles of these signaling molecules in the actions of ethanol-polyunsaturated fatty acids and betaine on hepatosteatosis and steatohepatitis. Ethanol-polyunsaturated fatty acid treatment caused the following: i) hepatosteatosis, as evidenced by increased liver cholesterol and triglycerides, lipid score, and decreased serum adiponectin; ii) marked inhibition of scavenger receptor class B type 1 glycosylation, its plasma membrane localization, and its hepatic cholesterol uptake function; and iii) moderate steatohepatitis, as evidenced by histopathological characteristics, increased liver tumor necrosis factor α and IL-6, decreased glutathione, and elevated serum alanine aminotransferase. These actions of ethanol involved up-regulated PGC-1β, sterol regulatory element-binding proteins 1c and 2, acetyl-CoA carboxylase, and HMG-CoA reductase mRNAs/proteins and inactive non-phosphorylated AMP kinase; and down-regulated silence regulator gene 1 and PGC-1α mRNA/proteins and hepatic fatty acid oxidation. Betaine markedly blunted all these actions of ethanol on hepatosteatosis and steatohepatitis. Therefore, we conclude that ethanol-mediated impaired post-translational modification, trafficking, and function of scavenger receptor class B type 1 may account for alcoholic hyperlipidemia. Up-regulation of PGC-1β and lipid synthetic genes and down-regulation of silence regulator gene 1, PGC-1α, adiponectin, and lipid degradation genes account for alcoholic hepatosteatosis. Induction of proinflammatory cytokines and depletion of endogenous antioxidant, glutathione, account for alcoholic steatohepatitis. We suggest betaine as a potential therapeutic agent because it effectively protects against adverse actions of ethanol. Copyright

  12. Pseudocatalytic scavenging of the nerve agent VX with human blood components and the oximes obidoxime and HI-6.

    PubMed

    Wille, Timo; von der Wellen, Jens; Thiermann, Horst; Worek, Franz

    2017-03-01

    Despite six decades of extensive research in medical countermeasures against nerve agent poisoning, a broad spectrum acetylcholinesterase (AChE) reactivator is not yet available. One current approach is directed toward synthesizing oximes with high affinity and reactivatability toward butyrylcholinesterase (BChE) in plasma to generate an effective pseudocatalytic scavenger. An interim solution could be the administration of external AChE or BChE from blood products to augment pseudocatalytic scavenging with slower but clinically approved oximes to decrease nerve agent concentrations in the body. We here semiquantitatively investigate the ability of obidoxime and HI-6 to decrease the inhibitory activity of VX with human AChE and BChE from whole blood, erythrocyte membranes, erythrocytes, plasma, clinically available fresh frozen plasma and packed red blood cells. The main findings are that whole blood showed a VX concentration-dependent decrease in inhibitory activity with HI-6 being more potent than obidoxime. Using erythrocytes and erythrocyte membranes again, HI-6 was more potent compared to obidoxime. With freshly prepared plasma, obidoxime and HI-6 showed comparable results for the decrease in VX. The use of the clinically available blood products revealed that packed red blood cells showed similar kinetics as fresh erythrocytes. Fresh frozen plasma resulted in a slower and incomplete decrease in inhibitory plasma compared to freshly prepared plasma. In conclusion, the administration of blood products in combination with available oximes augments pseudocatalytic scavenging and might be useful to decrease the body load of persistent, highly toxic nerve agents.

  13. Estimating Carcass Persistence and Scavenging Bias in a Human Influenced Landscape

    USGS Publications Warehouse

    Flint, Paul L.; Lance, Ellen W.; Sowl, Kristine M.; Donnelly, Tyrone F.

    2010-01-01

    We examined variation in persistence rates of waterfowl carcasses placed along a series of transects in tundra habitats in western Alaska. This study was designed to assess the effects of existing tower structures and was replicated with separate trials in winter, summer and fall as both the resident avian population and the suite of potential scavengers varied seasonally. Carcass persistence rates were uniformly low, with <50% of carcasses persisting for more than a day on average. Persistence rate varied by carcass age, carcass size, among transects and was lowest in the fall and highest in the summer. We found little support for models where persistence varied in relation to the presence of tower structures. We interpret this as evidence that scavengers were not habituated to searching for carcasses near these structures. Our data demonstrate that only a small fraction of bird carcasses are likely to persist between searches, and if not appropriately accounted for, scavenging bias could significantly influence bird mortality estimates. The variation that we documented suggests that persistence rates should not be extrapolated among tower locations or across time periods as the variation in carcass persistence will result in biased estimates of total bird strike mortality.

  14. HPLC analysis of vitamin E isoforms in human epidermis: correlation with minimal erythema dose and free radical scavenging activity.

    PubMed

    Fuchs, Jürgen; Weber, Stefan; Podda, Maurizio; Groth, Norbert; Herrling, Thomas; Packer, Lester; Kaufmann, Roland

    2003-02-01

    The content and composition of different vitamin E isoforms was analyzed in normal human skin. Interestingly the epidermis contained 1% alpha-tocotrienol, 3% gamma-tocotrienol, 87% alpha-tocopherol, and 9% gamma-tocopherol. Although the levels of tocotrienol in human epidermis appear to be considerably lower than reported in the hairless mouse, the presence of significant amounts of tocotrienol levels leads to speculation about the physiological function of tocotrienols in skin. Besides antioxidant activity and photoprotection, tocotrienols may have skin barrier and growth-modulating properties. A good correlation was found for epidermal alpha-tocopherol (r = 0.7909, p <.0003), gamma-tocopherol (r = 0.556, p <.025), and the total vitamin E content (r = 0.831, p <.0001) with the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging in epidermis, as assessed by electron paramagnetic resonance (EPR) spectroscopy. In human epidermis, alpha-tocopherol is quantitatively the most important vitamin E isoform present and comprises the bulk of first line free radical defense in the lipid compartment. Epidermal tocotrienol levels were not correlated with DPPH scavenging activity. The minimal erythema dose (MED), an individual measure for sun sensitivity and a crude indicator for skin cancer susceptibility, did not correlate with the epidermal content of the vitamin E isoforms. Hence it is concluded that vitamin E alone is not a determinant of individual photosensitivity in humans.

  15. Reversal of adipose tissue loss by probucol in mice with deficiency of both scavenger receptor class B type 1 and LDL receptor on high fat diet.

    PubMed

    Guo, Xin; Liao, Jiawei; Huang, Xiaomin; Wang, Yuhui; Huang, Wei; Liu, George

    2017-05-15

    Scavenger receptor class B type 1(SR-B1) and low density lipoprotein receptor (LDLR) play vital roles in cholesterol homeostasis. Previous studies indicated a strong link between cholesterol and adipose tissue (AT). In this study, adult male SR-B1 and LDLR double knockout (DKO) mice were fed with high fat diet (HFD) for 3 months. Interestingly, we found severe loss of AT in DKO mice fed with HFD. To reverse the AT loss in DKO mice, 1% probucol was added in HFD. In DKO mice on HFD, plasma total cholesterol (TC) and free cholesterol (FC) levels were increased 6 and 15 folds respectively compared with wild type (WT) mice. We found severe loss of AT in whole body of DKO mice compared with WT or single KO mice. In AT of DKO mice, histology showed the very small size of adipocytes and infiltration of inflammatory cells; Genes expressions related to fatty acid uptake, lipogenesis and adipogenesis were decreased; TUNEL analysis and related genes expressions of endoplasmic reticulum (ER) stress and inflammation were significantly higher than those of WT or single KO mice. Probucol could reduce increased TC and FC levels, and reverse the loss of fat and apoptosis of AT in DKO mice. AT loss in DKO mice with HFD was probably due to high levels of FC which led to apoptosis induced by ER stress and inflammation of AT. This study provided a novel utility of probucol in rescue of fat loss in DKO mice. Copyright © 2017. Published by Elsevier Inc.

  16. Expression of type I and type II bovine scavenger receptors in Chinese hamster ovary cells: Lipid droplet accumulation and nonreciprocal cross competition by acetylated and oxidized low density lipoprotein

    SciTech Connect

    Freeman, M. Massachusetts General Hospital, Boston ); Ekkel, Y.; Rohrer, L.; Penman, M.; Freedman, N.J.; Krieger, M. ); Chisolm, G.M. )

    1991-06-01

    Type I and type II scavenger receptors, which have been implicated in the development of atherosclerosis and other macrophage-associated functions, differ only by the presence in the type I receptor of an extracellular cysteine-rich C-terminal domain. Stable Chinese hamster ovary (CHO) cell transfectants expressing high levels of either the type I or type II bovine scavenger receptors have been generated. Type I and type II receptors in these cells mediated high-affinity saturable endocytosis of both {sup 125}I-labeled acetylated low density lipoprotein (LDL) and {sup 125}I-labeled oxidized LDL with the distinctive broad ligand specificity characteristic of scavenger receptors. After incubation for 2 days with acetylated LDL, the transfected cells accumulated oil red O-staining lipid droplets reminiscent of those in macrophage foam cells, whereas untransfected CHO cells did not. Thus, macrophage-specific gene products other than the scavenger receptor are not required for modified-LDL-induced intracellular lipid accumulation. In transfected cells, acetylated LDL efficiently competed for both its own endocytosis and that of oxidized LDL. This nonreciprocal cross competition suggests that these ligands may bind to nonidentical but interacting sites on a single receptor. Results were similar for transfectants expressing either type I or type II scavenger receptors. The nonreciprocal cross competition seen in the transfected CHO cells differs from that previously observed with cultured macrophages.

  17. New Insight into Atherosclerosis in Hemodialysis Patients: Overexpression of Scavenger Receptor and Macrophage Colony-Stimulating Factor Genes

    PubMed Central

    Nishida, Miki; Ando, Minoru; Iwamoto, Yusuke; Tsuchiya, Ken; Nitta, Kosaku

    2016-01-01

    Background Scavenger receptors (SRs) play a pivotal role in atherogenesis. The mechanism of atherosclerosis, which is specific to hemodialysis (HD) patients, was studied on the basis of SR gene expressions. Methods The gene expressions of SR type A (SR-A) and CD36 were studied in peripheral monocytes by real-time reverse transcription polymerase chain reaction. Data were compared between HD (n = 30) and age-matched control subjects (n = 10). Serum levels of macrophage colony-stimulating factor (M-CSF) were measured with enzyme-linked immunosorbent assay to test its role in SR expression. The statistical differences and associations between two continuous variables were assessed using the Mann-Whitney U test and Pearson's correlation coefficient, respectively. Results The relative quantities of SR mRNAs were significantly greater in HD patients than in controls [median (interquartile range): SR-A, 1.67 (0.96-2.76) vs. 0.90 (0.60-1.04), p = 0.0060; CD36, 1.09 (0.88-1.74) vs. 0.74 (0.64-0.99), p = 0.0255]. The serum concentration of M-CSF was significantly higher in HD patients than in controls [1, 121 (999-1,342) vs. 176 (155-202) pg/ml, p < 0.0001]. In addition, the relative quantity of M-CSF mRNA was significantly greater in HD patients than in controls [0.79 (0.42-1.53) vs. 0.42 (0.28-0.66), p = 0.0392]. The serum M-CSF levels were positively correlated with both the relative quantity of SR-A mRNA (r2 = 0.1681, p = 0.0086) and that of CD36 mRNA (r2 = 0.1202, p = 0.0284) in all subjects (n = 40). Conclusion HD patients are predisposed to atherosclerosis as a consequence of their enhanced monocyte SR expressions. SRs and M-CSF are potential therapeutic targets for atherosclerosis in this high-risk population. PMID:27721822

  18. Investigation of genetic variation in scavenger receptor class B, member 1 (SCARB1) and association with serum carotenoids.

    PubMed

    McKay, Gareth J; Loane, Edward; Nolan, John M; Patterson, Christopher C; Meyers, Kristin J; Mares, Julie A; Yonova-Doing, Ekaterina; Hammond, Christopher J; Beatty, Stephen; Silvestri, Giuliana

    2013-08-01

    To investigate association of scavenger receptor class B, member 1 (SCARB1) genetic variants with serum carotenoid levels of lutein (L) and zeaxanthin (Z) and macular pigment optical density (MPOD). A cross-sectional study of healthy adults aged 20 to 70. We recruited 302 participants after local advertisement. We measured MPOD by customized heterochromatic flicker photometry. Fasting blood samples were taken for serum L and Z measurement by high-performance liquid chromatography and lipoprotein analysis by spectrophotometric assay. Forty-seven single nucleotide polymorphisms (SNPs) across SCARB1 were genotyped using Sequenom technology. Association analyses were performed using PLINK to compare allele and haplotype means, with adjustment for potential confounding and correction for multiple comparisons by permutation testing. Replication analysis was performed in the TwinsUK and Carotenoids in Age-Related Eye Disease Study (CAREDS) cohorts. Odds ratios for MPOD area, serum L and Z concentrations associated with genetic variations in SCARB1 and interactions between SCARB1 and gender. After multiple regression analysis with adjustment for age, body mass index, gender, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, smoking, and dietary L and Z levels, 5 SNPs were significantly associated with serum L concentration and 1 SNP with MPOD (P<0.01). Only the association between rs11057841 and serum L withstood correction for multiple comparisons by permutation testing (P<0.01) and replicated in the TwinsUK cohort (P = 0.014). Independent replication was also observed in the CAREDS cohort with rs10846744 (P = 2×10(-4)), an SNP in high linkage disequilibrium with rs11057841 (r(2) = 0.93). No interactions by gender were found. Haplotype analysis revealed no stronger association than obtained with single SNP analyses. Our study has identified association between rs11057841 and serum L concentration (24% increase per T allele) in

  19. Investigation of genetic variation in scavenger receptor class B, member 1 (SCARB1) and association with serum carotenoids

    PubMed Central

    McKay, Gareth J; Loane, Edward; Nolan, John M; Patterson, Christopher C; Meyers, Kristin J; Mares, Julie A; Yonova-Doing, Ekaterina; Hammond, Christopher J; Beatty, Stephen; Silvestri, Giuliana

    2013-01-01

    Objective To investigate association of scavenger receptor class B, member 1 (SCARB1) genetic variants with serum carotenoid levels of lutein (L) and zeaxanthin (Z) and macular pigment optical density (MPOD). Design A cross-sectional study of healthy adults aged 20-70. Participants 302 participants recruited following local advertisement. Methods MPOD was measured by customized heterochromatic flicker photometry. Fasting blood samples were taken for serum L and Z measurement by HPLC and lipoprotein analysis by spectrophotometric assay. Forty-seven single nucleotide polymorphisms (SNPs) across SCARB1 were genotyped using Sequenom technology. Association analyses were performed using PLINK to compare allele and haplotype means, with adjustment for potential confounding and correction for multiple comparisons by permutation testing. Replication analysis was performed in the TwinsUK and CAREDS cohorts. Main outcome measures Odds ratios (ORs) for macular pigment optical density area, serum lutein and zeaxanthin concentrations associated with genetic variations in SCARB1 and interactions between SCARB1 and sex. Results Following multiple regression analysis with adjustment for age, body mass index, sex, high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), triglycerides, smoking, dietary L and Z levels, 5 SNPs were significantly associated with serum L concentration and 1 SNP with MPOD (P<0.01). Only the association between rs11057841 and serum L withstood correction for multiple comparisons by permutation testing (P<0.01) and replicated in the TwinsUK cohort (P=0.014). Independent replication was also observed in the CAREDS cohort with rs10846744 (P=2×10−4), a SNP in high linkage disequilibrium with rs11057841 (r2=0.93). No significant interactions by sex were found. Haplotype analysis revealed no stronger association than obtained with single SNP analyses. Conclusions Our study has identified association between rs11057841 and

  20. P2X7 Receptor-mediated Scavenger Activity of Mononuclear Phagocytes toward Non-opsonized Particles and Apoptotic Cells Is Inhibited by Serum Glycoproteins but Remains Active in Cerebrospinal Fluid*

    PubMed Central

    Gu, Ben J.; Duce, James A.; Valova, Valentina A.; Wong, Bruce; Bush, Ashley I.; Petrou, Steven; Wiley, James S.

    2012-01-01

    Rapid phagocytosis of non-opsonized particles including apoptotic cells is an important process that involves direct recognition of the target by multiple scavenger receptors including P2X7 on the phagocyte surface. Using a real-time phagocytosis assay, we studied the effect of serum proteins on this phagocytic process. Inclusion of 1–5% serum completely abolished phagocytosis of non-opsonized YG beads by human monocytes. Inhibition was reversed by pretreatment of serum with 1–10 mm tetraethylenepentamine, a copper/zinc chelator. Inhibitory proteins from the serum were determined as negatively charged glycoproteins (pI < 6) with molecular masses between 100 and 300 kDa. A glycoprotein-rich inhibitory fraction of serum not only abolished YG bead uptake but also inhibited phagocytosis of apoptotic lymphocytes or neuronal cells by human monocyte-derived macrophages. Three copper- and/or zinc-containing serum glycoproteins, ceruloplasmin, serum amyloid P-component, and amyloid precursor protein, were identified, and the purified proteins were shown to inhibit the phagocytosis of beads by monocytes as well as phagocytosis of apoptotic neuronal cells by macrophages. Human adult cerebrospinal fluid, which contains very little glycoprotein, had no inhibitory effect on phagocytosis of either beads or apoptotic cells. These data suggest for the first time that metal-interacting glycoproteins present within serum are able to inhibit the scavenger activity of mononuclear phagocytes toward insoluble debris and apoptotic cells. PMID:22461619

  1. Metformin Scavenges Methylglyoxal To Form a Novel Imidazolinone Metabolite in Humans.

    PubMed

    Kinsky, Owen R; Hargraves, Tiffanie L; Anumol, Tarun; Jacobsen, Neil E; Dai, Jixun; Snyder, Shane A; Monks, Terrence J; Lau, Serrine S

    2016-02-15

    Methylglyoxal (MG) is a highly reactive dicarbonyl compound involved in the formation of advanced glycation endproducts (AGE). Levels of MG are elevated in patients with type-2 diabetes mellitus (T2DM), and AGE have been implicated in the progression of diabetic complications. The antihyperglycemic drug metformin (MF) has been suggested to be a scavenger of MG. The present work examined and characterized unequivocally the resulting scavenged product from the metformin-MG reaction. The primary product was characterized by (1)H, (13)C, 2D-HSQC, and HMBC NMR and tandem mass spectrometry. X-ray diffraction analysis determined the structure of the metformin and MG-derived imidazolinone compound as (E)-1,1-dimethyl-2-(5-methyl-4-oxo-4,5-dihydro-1H-imidazol-2-yl)guanidine (IMZ). A LC-MS/MS multiple reaction monitoring method was developed to detect and quantify the presence of IMZ in metformin-treated T2DM patients. Urine from >90 MF-treated T2DM patients was analyzed, with increased levels of MF directly correlating with elevations in IMZ. Urinary MF was detected in the range of 0.17 μM to 23.0 mM, and simultaneous measurement of IMZ concentrations were in the range of 18.8 nM to 4.3 μM. Since plasma concentrations of MG range from 40 nM to 4.5 μM, the level of IMZ production may be of therapeutic significance. Thus, in addition to lowering hepatic gluconeogenesis, metformin also scavenges the highly reactive MG in vivo, thereby reducing potentially detrimental MG protein adducts, with subsequent reductions in diabetic complications.

  2. Scavenger receptor B1 (SR-B1) profoundly excludes high density lipoprotein (HDL) apolipoprotein AII as it nibbles HDL-cholesteryl ester.

    PubMed

    Gillard, Baiba K; Bassett, G Randall; Gotto, Antonio M; Rosales, Corina; Pownall, Henry J

    2017-05-26

    Reverse cholesterol transport (transfer of macrophage-cholesterol in the subendothelial space of the arterial wall to the liver) is terminated by selective high density lipoprotein (HDL)-cholesteryl ester (CE) uptake, mediated by scavenger receptor class B, type 1 (SR-B1). We tested the validity of two models for this process: "gobbling," i.e. one-step transfer of all HDL-CE to the cell and "nibbling," multiple successive cycles of SR-B1-HDL association during which a few CEs transfer to the cell. Concurrently, we compared cellular uptake of apoAI with that of apoAII, which is more lipophilic than apoAI, using HDL-[(3)H]CE labeled with [(125)I]apoAI or [(125)I]apoAII. The studies were conducted in CHO-K1 and CHO-ldlA7 cells (LDLR(-/-)) with (CHO-SR-B1) and without SR-B1 overexpression and in human Huh7 hepatocytes. Relative to CE, both apoAI and apoAII were excluded from uptake by all cells. However, apoAII was more highly excluded from uptake (2-4×) than apoAI. To distinguish gobbling versus nibbling mechanisms, media from incubations of HDL with CHO-SR-B1 cells were analyzed by non-denaturing PAGE, size-exclusion chromatography, and the distribution of apoAI, apoAII, cholesterol, and phospholipid among HDL species as a function of incubation time. HDL size gradually decreased, i.e. nibbling, with the concurrent release of lipid-free apoAI; apoAII was retained in an HDL remnant. Our data support an SR-B1 nibbling mechanism that is similar to that of streptococcal serum opacity factor, which also selectively removes CE and releases apoAI, leaving an apoAII-rich remnant. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Structure-activity relationships of GHRP-6 azapeptide ligands of the CD36 scavenger receptor by solid-phase submonomer azapeptide synthesis.

    PubMed

    Sabatino, David; Proulx, Caroline; Pohankova, Petra; Ong, Huy; Lubell, William D

    2011-08-17

    The cluster of differentiation 36 (CD36) class B scavenger receptor binds a variety of biologically endogenous ligands in addition to synthetic peptides (i.e., growth hormone-releasing peptides, GHRPs), which modulate biological function related to anti-angiogenic and anti-atherosclerotic activities. Affinity labeling had previously shown that GHRP-6 analogues such as hexarelin, [2-Me-W(2)]GHRP-6 (1), bind to the lysine-rich domain of the CD36 receptor. Moreover, the azapeptide analogue [aza-F(4)]GHRP-6, 2, exhibited a characteristic β-turn conformation as described by CD and NMR spectroscopy and a slightly higher CD36 binding affinity relative to hexarelin (1.34 and 2.37 μM, respectively), suggesting receptor binding was mediated by the conformation and the aromatic residues of these peptide sequences. Ligand-receptor binding interactions were thus explored using azapeptides to examine influences of side-chain diversity and backbone conformation. In particular, considering that aromatic cation interactions may contribute to binding affinity, we have explored the potential of introducing salt bridges to furnish GHRP-6 azapeptide ligands of the CD36 receptor. Fifteen aza-glutamic acid analogues related to 2 were prepared by submonomer solid-phase synthesis. The azapeptide side chains were installed by novel approaches featuring alkylation of resin-bound semicarbazone with Michael acceptors and activated allylic acetates in the presence of phosphazene base (BTPP). Moreover, certain Michael adducts underwent intramolecular cyclization during semicarbazone deprotection, leading to novel pyrrazoline and aza-pyroglutamate N-terminal residues. Structural studies indicated that contingent on sequence the [aza-Glu]GHRP-6 analogues exhibited CD spectra characteristic of random coil, polyproline type II and β-turn secondary structures in aqueous media. In covalent competition binding studies with the GHRP-6 prototype hexarelin bearing a radiotracer, certain [aza-Glu]GHRP-6

  4. Scavenger Receptor Class B, Type I, a CD36 Related Protein in Macrobrachium nipponense: Characterization, RNA Interference, and Expression Analysis with Different Dietary Lipid Sources

    PubMed Central

    Ding, Zhili; Luo, Na; Kong, Youqin; Li, Jingfen; Zhang, Yixiang; Cao, Fang

    2016-01-01

    The scavenger receptor class B, type I (SR-BI), is a member of the CD36 superfamily comprising transmembrane proteins involved in mammalian and fish lipid homeostasis regulation. We hypothesize that this receptor plays an important role in Macrobrachium nipponense lipid metabolism. However, little attention has been paid to SR-BI in commercial crustaceans. In the present study, we report a cDNA encoding M. nipponense scavenger receptor class B, type I (designated as MnSR-BI), obtained from a hepatopancreas cDNA library. The complete MnSR-BI coding sequence was 1545 bp, encoding 514 amino acid peptides. The MnSR-BI primary structure consisted of a CD36 domain that contained two transmembrane regions at the N- and C-terminals of the protein. SR-BI mRNA expression was specifically detected in muscle, gill, ovum, intestine, hepatopancreas, stomach, and ovary tissues. Furthermore, its expression in the hepatopancreas was regulated by dietary lipid sources, with prawns fed soybean and linseed oils exhibiting higher expression levels. RNAi-based SR-BI silencing resulted in the suppression of its expression in the hepatopancreas and variation in the expression of lipid metabolism-related genes. This is the first report of SR-BI in freshwater prawns and provides the basis for further studies on SR-BI in crustaceans. PMID:28003996

  5. Comparison of Radical Scavenging Activity, Cytotoxic Effects and Apoptosis Induction in Human Melanoma Cells by Taiwanese Propolis from Different Sources

    PubMed Central

    2004-01-01

    Propolis is a sticky substance that is collected from plants by honeybees. We previously demonstrated that propolins A, B, C, D, E and F, isolated from Taiwanese propolis (TP), could effectively induce human melanoma cell apoptosis and were strong antioxidant agents. In this study, we evaluated TP for free radical scavenging activity by DPPH (1,2-diphenyl-2-picrylhydrazyl). The phenolic concentrations were quantified by the Folin–Ciocalteu method. The apoptosis trigger activity in human melanoma cells was evaluated. TP contained a higher level of phenolic compounds and showed strong capability to scavenge free radicals. Additionally, TP1g, TP3, TP4 and TP7 exhibited a cytotoxic effect on human melanoma cells, with an IC50 of ∼2.3, 2.0, 3.3 and 3.3 μg/ml, respectively. Flow cytometric analysis for DNA fragmentation indicated that TP1g, TP2, TP3 and TP7 could induce apoptosis in human melanoma cells and there is a marked loss of cells from the G2/M phase of the cell cycle. To address the mechanism of the apoptosis effect of TP, we evaluated its effects on induction of apoptosis-related proteins in human melanoma cells. The levels of procaspase-3 and PARP [poly(ADP-ribose) polymerase] were markedly decreased. Furthermore, propolins A, B, C, D, E and F in TP were determined using HPLC. The results indicate that TP is a rich source of these compounds. The findings suggest that TP induces apoptosis in human melanoma cells due to its high level of propolins. PMID:15480443

  6. Comparison of Radical Scavenging Activity, Cytotoxic Effects and Apoptosis Induction in Human Melanoma Cells by Taiwanese Propolis from Different Sources.

    PubMed

    Chen, Chia-Nan; Weng, Meng-Shih; Wu, Chia-Li; Lin, Jen-Kun

    2004-09-01

    Propolis is a sticky substance that is collected from plants by honeybees. We previously demonstrated that propolins A, B, C, D, E and F, isolated from Taiwanese propolis (TP), could effectively induce human melanoma cell apoptosis and were strong antioxidant agents. In this study, we evaluated TP for free radical scavenging activity by DPPH (1,2-diphenyl-2-picrylhydrazyl). The phenolic concentrations were quantified by the Folin-Ciocalteu method. The apoptosis trigger activity in human melanoma cells was evaluated. TP contained a higher level of phenolic compounds and showed strong capability to scavenge free radicals. Additionally, TP1g, TP3, TP4 and TP7 exhibited a cytotoxic effect on human melanoma cells, with an IC(50) of approximately 2.3, 2.0, 3.3 and 3.3 μg/ml, respectively. Flow cytometric analysis for DNA fragmentation indicated that TP1g, TP2, TP3 and TP7 could induce apoptosis in human melanoma cells and there is a marked loss of cells from the G2/M phase of the cell cycle. To address the mechanism of the apoptosis effect of TP, we evaluated its effects on induction of apoptosis-related proteins in human melanoma cells. The levels of procaspase-3 and PARP [poly(ADP-ribose) polymerase] were markedly decreased. Furthermore, propolins A, B, C, D, E and F in TP were determined using HPLC. The results indicate that TP is a rich source of these compounds. The findings suggest that TP induces apoptosis in human melanoma cells due to its high level of propolins.

  7. Lutein transport by Caco-2 TC-7 cells occurs partly by a facilitated process involving the scavenger receptor class B type I (SR-BI).

    PubMed

    Reboul, Emmanuelle; Abou, Lydia; Mikail, Céline; Ghiringhelli, Odette; André, Marc; Portugal, Henri; Jourdheuil-Rahmani, Dominique; Amiot, Marie-Josèphe; Lairon, Denis; Borel, Patrick

    2005-04-15

    The carotenoid lutein is thought to play a role in the human eye and to protect against age-related macular degeneration. Lutein transport in the human intestine has not been characterized. We examined lutein transport processes using Caco-2 TC-7 monolayers as a model for human intestinal epithelium. Purified lutein was mixed with phospholipids, lysophospholipids, cholesterol, mono-olein, oleic acid and taurocholate to obtain lutein-rich mixed micelles that mimicked those found under physiological conditions. The micelles were added to the apical side of Caco-2 TC-7 cell monolayers for 30 min or 3 h at 37 degrees C. Absorbed lutein, i.e. the sum of lutein recovered in the scraped cells and in the basolateral chamber, was quantified by HPLC. Transport rate was measured (i) as a function of time (from 15 to 60 min), (ii) as a function of micellar lutein concentration (from 1.5 to 15 microM), (iii) at 4 degrees C, (iv) in the basolateral to apical direction, (v) after trypsin pretreatment, (vi) in the presence of beta-carotene and/or lycopene, (vii) in the presence of increasing concentrations of antibody against SR-BI (scavenger receptor class B type 1) and (viii) in the presence of increasing concentrations of a chemical inhibitor of the selective transfer of lipids mediated by SR-BI, i.e. BLT1 (blocks lipid transport 1). The rate of transport of lutein as a function of time and as a function of concentration was saturable. It was significantly lower at 4 degrees C than at 37 degrees C (approx. 50%), in the basal to apical direction than in the opposite direction (approx. 85%), and after trypsin pretreatment (up to 45%). Co-incubation with beta-carotene, but not lycopene, decreased the lutein absorption rate (approx. 20%) significantly. Anti-SR-BI antibody and BLT1 significantly impaired the absorption rate (approx. 30% and 57% respectively). Overall, these results indicate that lutein absorption is, at least partly, protein-mediated and that some lutein is taken up

  8. Lutein transport by Caco-2 TC-7 cells occurs partly by a facilitated process involving the scavenger receptor class B type I (SR-BI)

    PubMed Central

    2004-01-01

    The carotenoid lutein is thought to play a role in the human eye and to protect against age-related macular degeneration. Lutein transport in the human intestine has not been characterized. We examined lutein transport processes using Caco-2 TC-7 monolayers as a model for human intestinal epithelium. Purified lutein was mixed with phospholipids, lysophospholipids, cholesterol, mono-olein, oleic acid and taurocholate to obtain lutein-rich mixed micelles that mimicked those found under physiological conditions. The micelles were added to the apical side of Caco-2 TC-7 cell monolayers for 30 min or 3 h at 37 °C. Absorbed lutein, i.e. the sum of lutein recovered in the scraped cells and in the basolateral chamber, was quantified by HPLC. Transport rate was measured (i) as a function of time (from 15 to 60 min), (ii) as a function of micellar lutein concentration (from 1.5 to 15 μM), (iii) at 4 °C, (iv) in the basolateral to apical direction, (v) after trypsin pretreatment, (vi) in the presence of β-carotene and/or lycopene, (vii) in the presence of increasing concentrations of antibody against SR-BI (scavenger receptor class B type 1) and (viii) in the presence of increasing concentrations of a chemical inhibitor of the selective transfer of lipids mediated by SR-BI, i.e. BLT1 (blocks lipid transport 1). The rate of transport of lutein as a function of time and as a function of concentration was saturable. It was significantly lower at 4 °C than at 37 °C (approx. 50%), in the basal to apical direction than in the opposite direction (approx. 85%), and after trypsin pretreatment (up to 45%). Co-incubation with β-carotene, but not lycopene, decreased the lutein absorption rate (approx. 20%) significantly. Anti-SR-BI antibody and BLT1 significantly impaired the absorption rate (approx. 30% and 57% respectively). Overall, these results indicate that lutein absorption is, at least partly, protein-mediated and that some lutein is taken up through SR

  9. Human dopamine receptor and its uses

    DOEpatents

    Civelli, Olivier; Van Tol, Hubert Henri-Marie

    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.

  10. Human olfactory receptor responses to odorants

    PubMed Central

    Mainland, Joel D; Li, Yun R; Zhou, Ting; Liu, Wen Ling L; Matsunami, Hiroaki

    2015-01-01

    Although the human olfactory system is capable of discriminating a vast number of odors, we do not currently understand what chemical features are encoded by olfactory receptors. In large part this is due to a paucity of data in a search space covering the interactions of hundreds of receptors with billions of odorous molecules. Of the approximately 400 intact human odorant receptors, only 10% have a published ligand. Here we used a heterologous luciferase assay to screen 73 odorants against a clone library of 511 human olfactory receptors. This dataset will allow other researchers to interrogate the combinatorial nature of olfactory coding. PMID:25977809

  11. Xenobiotic receptor humanized mice and their utility.

    PubMed

    Scheer, Nico; Roland Wolf, C

    2013-02-01

    The nuclear receptors pregnane X receptor, constitutive androstane receptor, and peroxisome proliferator-activated receptor alpha have important endogenous functions and are also involved in the induction of drug-metabolizing enzymes and transporters in response to exogenous xenobiotics. Though not belonging to the same protein family, the Per-Sim-ARNT domain receptor aryl hydrocarbon receptor functionally overlaps with the three nuclear receptors in many aspects and is therefore included in this review. Significant species differences in ligand affinity and biological responses as a result of activation of these receptors have been described. Several xenobiotic receptor humanized mice have been created to overcome these species differences and to provide in vivo models that are more predictive for human responses. This review provides an overview of the different xenobiotic receptor humanized mouse models described to date and will summarize how these models can be applied in basic research and improve drug discovery and development. Some of the key applications in the evaluation of drug induction, drug-drug interactions, nongenotoxic carcinogenicity, other toxicity, or efficacy studies are described. We also discuss relevant considerations in the interpretation of such data and potential future directions for the use of xenobiotic receptor humanized mice.

  12. Dose-dependent vitamin C uptake and radical scavenging activity in human skin measured with in vivo electron paramagnetic resonance spectroscopy.

    PubMed

    Lauer, Anna-Christina; Groth, Norbert; Haag, Stefan F; Darvin, Maxim E; Lademann, Jürgen; Meinke, Martina C

    2013-01-01

    Vitamin C is a potent radical scavenger and a physiological part of the antioxidant system in human skin. The aim of this study was to measure changes in the radical-scavenging activity of human skin in vivo due to supplementation with different doses of vitamin C and at different time points. Therefore, 33 volunteers were supplemented with vitamin C or placebo for 4 weeks. The skin radical-scavenging activity was measured with electron paramagnetic resonance spectroscopy. After 4 weeks, the intake of 100 mg vitamin C/day resulted in a significant increase in the radical-scavenging activity by 22%. Intake of 180 mg/day even resulted in a significant increase of 37%. No changes were found in the placebo group. A part of the study population was additionally measured after 2 weeks: in this group radical scavenging had already reached maximal activity after 2 weeks. In conclusion, orally administered vitamin C increases the radical-scavenging activity of the skin. The effect occurs fast and is enhanced with higher doses of vitamin C.

  13. Genetic Variants at the PDZ-Interacting Domain of the Scavenger Receptor Class B Type I Interact with Diet to Influence the Risk of Metabolic Syndrome in Obese Men and Women

    USDA-ARS?s Scientific Manuscript database

    The scaffolding protein PDZ domain containing 1 (PDZK1) regulates the HDL receptor scavenger receptor class B type I. However, the effect of PDZK1 genetic variants on lipids and metabolic syndrome (MetS) traits remains unknown. This study evaluated the association of 3 PDZK1 single nucleotide polymo...

  14. Hydrogen scavengers

    SciTech Connect

    Carroll, David W.; Salazar, Kenneth V.; Trkula, Mitchell; Sandoval, Cynthia W.

    2002-01-01

    There has been invented a codeposition process for fabricating hydrogen scavengers. First, a .pi.-bonded allylic organometallic complex is prepared by reacting an allylic transition metal halide with an organic ligand complexed with an alkali metal; and then, in a second step, a vapor of the .pi.-bonded allylic organometallic complex is combined with the vapor of an acetylenic compound, irradiated with UV light, and codeposited on a substrate.

  15. The physiological expression of scavenger receptor SR-B1 in canine endometrial and placental epithelial cells and its potential involvement in pathogenesis of pyometra.

    PubMed

    Gabriel, C; Becher-Deichsel, A; Hlavaty, J; Mair, G; Walter, I

    2016-06-01

    Pyometra, the purulent inflammation of the uterus, is a common uterine disease of bitches that has potentially life-threatening consequences. The opportunistic bacterial infection of the uterus often progresses into the serious systemic inflammatory response syndrome. In a previous study, we characterized epithelial foam cells in the canine endometrial surface occurring in metestrus, and we regularly observed pronounced epithelial foam-cell formations in pyometra-affected uteri. Therefore, it was assumed that the mechanism behind lipid droplet accumulation in surface epithelial cells might even increase bacterial binding capacity and promote pyometra development. Lipid droplet accumulation in epithelial cells is accomplished via specialized lipid receptors called scavenger receptors (SR). Scavenger receptor class B type 1 (SR-B1) is an important receptor for lipid accumulation in diverse cell types, but it is also a strong binding partner for bacteria, and thereby enhances bacterial adhesion and clinical signs of systemic inflammatory response syndrome. In the present study, after the isolation of metestrous surface epithelial cells from canine uteri by laser capture microdissection, SR-B1 was identified at the messenger RNA (mRNA) level by quantitative real time polymerase chain reaction and also at the protein level by means of immunohistochemistry. In pyometra-affected uteri, SR-B1 mRNA expression was higher than that in the healthy control samples, and SR-B1 protein was expressed in the surface and crypt epithelial cells. Furthermore, to understand the physiological role of SR-B1 expression in the metestrus surface epithelial cells, we investigated its expression in the epithelial cells of the glandular chambers of canine placenta in different stages of gestation because these cells are also characterized by lipid droplet accumulation. SR-B1 was present in the placental epithelial cells of the glandular chambers from 25 to 30 and 45 to 50 days of gestation

  16. Acetylcholine receptors in the human retina

    SciTech Connect

    Hutchins, J.B.; Hollyfield, J.G.

    1985-11-01

    Evidence for a population of acetylcholine (ACh) receptors in the human retina is presented. The authors have used the irreversible ligand TH-propylbenzilylcholine mustard (TH-PrBCM) to label muscarinic receptors. TH- or SVI-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 TH-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.

  17. Scavenger Receptor Class B Type 1 Deletion Led to Coronary Atherosclerosis and Ischemic Heart Disease in Low-density Lipoprotein Receptor Knockout Mice on Modified Western-type Diet

    PubMed Central

    Liao, Jiawei; Guo, Xin; Wang, Mengyu; Dong, Chengyan; Gao, Mingming; Wang, Huan; Kayoumu, Abudurexiti; Shen, Qiang; Wang, Yuhui; Wang, Fan; Liu, George

    2017-01-01

    Aim: Atherosclerosis-prone apolipoprotein E (apoE) or low-density lipoprotein receptor (LDL-R) knockout (KO) mice are generally resistant to developing coronary atherosclerosis (CA) and ischemic heart disease (IHD). However, studies have demonstrated the occurrence of spontaneous CA and IHD in scavenger receptor class B type 1 (SR-BI)/apoE double KO (dKO) mice, which suggests that SR-BI could be a potential target for the prevention and therapy of CA and IHD. This possibility was later investigated in SR-BI/LDL-R dKO mice, but no signs of CA or IHD was identified when mice were fed a normal western-type diet. Here we explored whether SR-BI deletion could result in CA and IHD in LDL-R KO mice when fed a modified western-type diet containing higher (0.5%) cholesterol. Methods: Cardiac functions were detected by electrocardiography, single photon emission computed tomography (SPECT), echocardiography (Echo) and 2,3,5-triphenyltetrazolium chloride staining. CA was visualized by hematoxylin-eosin staining. Results: After 12 weeks on the modified diet, SR-BI/LDL-R dKO mice developed cardiac ischemia/infarction, together with systolic dysfunction and left ventricular dilatation. CA was most severe at the aortic sinus level to an extent that no dKO mice survived to 20 weeks on the modified diet. None of control mice, however, developed CA or IHD. Conclusions: SR-BI deletion led to CA and IHD in LDL-R KO mice when fed the modified western-type diet. We established SR-BI/LDL-R dKO mice as a diet-induced murine model of human IHD and developed detection methods, using a combination of SPECT and Echo, for effective in vivo evaluation of cardiac functions. PMID:27373983

  18. Scavenger Receptor SREC-I Mediated Entry of TLR4 into Lipid Microdomains and Triggered Inflammatory Cytokine Release in RAW 264.7 Cells upon LPS Activation

    PubMed Central

    Murshid, Ayesha; Gong, Jianlin; Prince, Thomas; Borges, Thiago J.; Calderwood, Stuart K.

    2015-01-01

    Scavenger receptor associated with endothelial cells I (SREC-I) was shown to be expressed in immune cells and to play a role in the endocytosis of peptides and antigen presentation. As our previous studies indicated that SREC-I required intact Toll-like receptor 4 (TLR4) expression for its functions in tumor immunity, we examined potential interactions between these two receptors. We have shown here that SREC-I became associated with TLR4 on binding bacterial lipopolysaccharides (LPS) in RAW 264.7 and HEK 293 cells overexpressing these two receptors. The receptors then became internalized together in intracellular endosomes. SREC-I promoted TLR4-induced signal transduction through the NF-kB and MAP kinase pathways, leading to enhanced inflammatory cytokine release. Activation of inflammatory signaling through SREC-I/TLR4 complexes appeared to involve recruitment of the receptors into detergent-insoluble, cholesterol-rich lipid microdomains that contained the small GTPase Cdc42 and the non-receptor tyrosine kinase c-src. Under conditions of SREC-I activation by LPS, TLR4 activity required Cdc42 as well as cholesterol and actin polymerization for signaling through NF-kB and MAP kinase pathways in RAW 264.7 cells. SREC-I appeared to respond differently to another ligand, the molecular chaperone Hsp90 that, while triggering SREC-I-TLR4 binding caused only faint activation of the NF-kB pathway. Our experiments therefore indicated that SREC-I could bind LPS and might be involved in innate inflammatory immune responses to extracellular danger signals in RAW 264.7 cells or bone marrow-derived macrophages. PMID:25836976

  19. Leukocyte chemoattractant receptors in human disease pathogenesis.

    PubMed

    Zabel, Brian A; Rott, Alena; Butcher, Eugene C

    2015-01-01

    Combinations of leukocyte attractant ligands and cognate heptahelical receptors specify the systemic recruitment of circulating cells by triggering integrin-dependent adhesion to endothelial cells, supporting extravasation, and directing specific intratissue localization via gradient-driven chemotaxis. Chemoattractant receptors also control leukocyte egress from lymphoid organs and peripheral tissues. In this article, we summarize the fundamental mechanics of leukocyte trafficking, from the evolution of multistep models of leukocyte recruitment and navigation to the regulation of chemoattractant availability and function by atypical heptahelical receptors. To provide a more complete picture of the migratory circuits involved in leukocyte trafficking, we integrate a number of nonchemokine chemoattractant receptors into our discussion. Leukocyte chemoattractant receptors play key roles in the pathogenesis of autoimmune diseases, allergy, inflammatory disorders, and cancer. We review recent advances in our understanding of chemoattractant receptors in disease pathogenesis, with a focus on genome-wide association studies in humans and the translational implications of mechanistic studies in animal disease models.

  20. Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis

    SciTech Connect

    Williams, K.J.; Vallabhajosula, S.; Rahman, I.U.; Donnelly, T.M.; Parker, T.S.; Weinrauch, M.; Goldsmith, S.J.

    1988-01-01

    The metabolism of infused /sup 111/In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t/sub 1/2/) for clearance of /sup 111/In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits. By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue sores. Disappearance of excess plasma cholesterol was > 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative ..gamma.. camera imaging, hepatic trapping of /sup 111/In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance. Aortic uptake of /sup 111/In was < 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, the results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia.

  1. Surfactant protein A (SP-A)-mediated clearance of Staphylococcus aureus involves binding of SP-A to the staphylococcal adhesin eap and the macrophage receptors SP-A receptor 210 and scavenger receptor class A.

    PubMed

    Sever-Chroneos, Zvjezdana; Krupa, Agnieszka; Davis, Jeremy; Hasan, Misbah; Yang, Ching-Hui; Szeliga, Jacek; Herrmann, Mathias; Hussain, Muzafar; Geisbrecht, Brian V; Kobzik, Lester; Chroneos, Zissis C

    2011-02-11

    Staphylococcus aureus causes life-threatening pneumonia in hospitals and deadly superinfection during viral influenza. The current study investigated the role of surfactant protein A (SP-A) in opsonization and clearance of S. aureus. Previous studies showed that SP-A mediates phagocytosis via the SP-A receptor 210 (SP-R210). Here, we show that SP-R210 mediates binding and control of SP-A-opsonized S. aureus by macrophages. We determined that SP-A binds S. aureus through the extracellular adhesin Eap. Consequently, SP-A enhanced macrophage uptake of Eap-expressing (Eap(+)) but not Eap-deficient (Eap(-)) S. aureus. In a reciprocal fashion, SP-A failed to enhance uptake of Eap(+) S. aureus in peritoneal Raw264.7 macrophages with a dominant negative mutation (SP-R210(DN)) blocking surface expression of SP-R210. Accordingly, WT mice cleared infection with Eap(+) but succumbed to sublethal infection with Eap- S. aureus. However, SP-R210(DN) cells compensated by increasing non-opsonic phagocytosis of Eap(+) S. aureus via the scavenger receptor scavenger receptor class A (SR-A), while non-opsonic uptake of Eap(-) S. aureus was impaired. Macrophages express two isoforms: SP-R210(L) and SP-R210(S). The results show that WT alveolar macrophages are distinguished by expression of SP-R210(L), whereas SR-A(-/-) alveolar macrophages are deficient in SP-R210(L) expressing only SP-R210(S). Accordingly, SR-A(-/-) mice were highly susceptible to both Eap(+) and Eap(-) S. aureus. The lungs of susceptible mice generated abnormal inflammatory responses that were associated with impaired killing and persistence of S. aureus infection in the lung. In conclusion, alveolar macrophage SP-R210(L) mediates recognition and killing of SP-A-opsonized S. aureus in vivo, coordinating inflammatory responses and resolution of S. aureus pneumonia through interaction with SR-A.

  2. Varenicline enhances oxidized LDL uptake by increasing expression of LOX-1 and CD36 scavenger receptors through α7 nAChR in macrophages.

    PubMed

    Kanaoka, Yuki; Koga, Mitsuhisa; Sugiyama, Keita; Ohishi, Kaoru; Kataoka, Yasufumi; Yamauchi, Atsushi

    2017-04-01

    Varenicline is a widely used and effective drug for smoking cessation. It is a partial agonist of the α4β2 nicotinic acetylcholine receptor (nAChR) and full agonist of α7 nAChR. We have reported that varenicline aggravates formation of atherosclerotic plaques through α7 nAChR in apolipoprotein E knockout mice. However, little is known about its effects on macrophages in atherosclerotic plaques. Here, we ascertained whether varenicline promotes oxidized low-density lipoprotein (oxLDL) uptake in mouse peritoneal macrophages in vitro and clarified its mechanism. We investigated the effects of varenicline (1-10μM) on expression of scavenger receptors (lectin-like oxidized LDL receptor-1 (LOX-1), cluster of differentiation (CD) 36 and scavenger receptor class A (SR-A)) in RAW264.7 cells. Expression of protein and mRNA was determined by western blotting and real-time quantitative reverse transcription-polymerase chain reaction, respectively. Effects of varenicline (10μM) on oxLDL uptake were examined by counting the number of macrophages stained with oil red O and hematoxylin. Varenicline significantly increased expression of the protein and mRNA of LOX-1 and CD36, but not SR-A, in RAW264.7 cells, and increased oxLDL uptake in macrophages. These effects of varenicline were blocked significantly by an α7 nAChR antagonist, methyllycaconitine (MLA) (50nM), but not by an α4β2 nAChR antagonist, dihydro-β-erythroidine hydrobromide (DHβE) (1μM). These data suggest that varenicline promotes oxLDL uptake by upregulating expression of LOX-1 and CD36 through α7 nAChR in macrophages. We found that varenicline significantly activated extracellular signal-regulated kinase 1/2 (ERK1/2) and nuclear factor-kappa B (NF-κB) signaling pathways in RAW264.7 cells. This activation was blocked by MLA but not DHβE. Therefore, ERK1/2-NF-κB signaling pathway is highly likely to be responsible for varenicline-induced upregulation of LOX-1 and CD36 expression through α7 nAChR in

  3. Generation of Recombinant Human AChE OP-Scavengers with Extended Circulatory Longevity

    DTIC Science & Technology

    2006-11-01

    correspond to complex-type biantennary forms carrying a fucose moiety, while triantennary glycans (22-30% of the total glycans) were represented to...solid square, GalNAc; elongated diamond, Fucose . Rh, rhesus; Hu, human; Bo, Bovine. ê ê Ä P!!PÄ A 0 5 10 15 20 25 G416S 11.3S 6.1S 100 75 50 kDa 1 2...previously (Kronman et al., 2000; Chitlaru et al., 2001, 2002). These include glycan structures that carry 2 GalNac (MW = 2011.0 Da) or 2 fucose (MW

  4. Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis.

    PubMed Central

    Williams, K J; Vallabhajosula, S; Rahman, I U; Donnelly, T M; Parker, T S; Weinrauch, M; Goldsmith, S J

    1988-01-01

    The metabolism of infused 111In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t1/2) for clearance of 111In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits (means +/- SEM; n = 4). By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue stores. Disappearance of excess plasma cholesterol was greater than 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative gamma camera imaging, hepatic trapping of 111In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance, acquiring 22.0% +/- 1.7% (WHHL) and 16.8% +/- 1.0% (normal of total 111In. Aortic uptake of 111In was less than 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, our results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia. PMID:3422421

  5. Differential effects of radical scavengers on X-ray-induced mutation and cytotoxicity in human cells

    SciTech Connect

    Corn, B.W.; Liber, H.L.; Little, J.B.

    1987-01-01

    The cytotoxic and mutagenic effects of X irradiation on a human lymphoblast cell line were examined in the presence of two radioprotective agents which modulate damage to DNA. The cells were treated with X rays alone or in the presence of either dimethyl sulfoxide or cysteamine. Surviving fraction and mutation to trifluorothymidine resistance (tk locus) and to 6-thioguanine resistance (hgprt locus) were measured. Survival was enhanced when the cells were irradiated in the presence of dimethyl sulfoxide; the D0 rose from 58 to 107 rad. However, at both genetic loci the induced mutant fractions were identical in the presence or absence of dimethyl sulfoxide. Survival was enhanced to a greater degree when the cells were irradiated in the presence of cysteamine; the D0 rose from 58 to 200 rad. Cysteamine also protected the cells from X-ray-induced mutation; the frequencies of X-ray-induced mutation at both the tk and hgprt loci were reduced by 50-75%. No protective effects were observed unless dimethyl sulfoxide or cysteamine was present during irradiation. These findings are discussed in terms of the hypothesis that, unlike for cell killing, radiation-induced mutagenesis in human lymphoblast cells is not mediated by the actions of aqueous free radicals, but rather by the direct effects of ionizing radiation.

  6. Expression, purification and reconstitution of the C-terminal transmembrane domain of scavenger receptor BI into detergent micelles for NMR analysis.

    PubMed

    Chadwick, Alexandra C; Jensen, Davin R; Peterson, Francis C; Volkman, Brian F; Sahoo, Daisy

    2015-03-01

    Scavenger receptor class B type I (SR-BI), the high density lipoprotein (HDL) receptor, is important for the delivery of HDL-cholesteryl esters to the liver for excretion via bile formation. The focus on therapeutic strategies aimed at reducing cholesterol levels highlights the critical need to understand the structural features of SR-BI that drive cholesterol removal. Yet, in the absence of a high-resolution structure of SR-BI, our understanding of how SR-BI interacts with HDL is limited. In this study, we have optimized the NMR solution conditions for the structural analysis of the C-terminal transmembrane domain of SR-BI that harbors putative domains required for receptor oligomerization. An isotopically-labeled SR-BI peptide encompassing residues 405-475 was bacterially-expressed and purified. [U-(15)N]-SR-BI(405-475) was incorporated into different detergent micelles and assessed by (1)H-(15)N-HSQC in order to determine which detergent micelle best maintained SR-BI(405-475) in a folded, native conformation for subsequent NMR analyses. We also determined the optimal detergent concentration used in micelles, as well as temperature, solution buffer and pH conditions. Based on (1)H-(15)N-HSQC peak dispersion, intensity, and uniformity, we determined that [U-(15)N]-SR-BI(405-475) should be incorporated into 5% detergent micelles consisting of 1-palmitoyl-2-hydroxy-sn-glycero-3-phospho-[1'-rac-glycerol] (LPPG) and data collected at 40°C in a non-buffered solution at pH 6.8. Furthermore, we demonstrate the ability of SR-BI(405-475) to form dimers upon chemical crosslinking. These studies represent the first steps in obtaining high-resolution structural information by NMR for the HDL receptor that plays a critical role in regulating whole body cholesterol removal.

  7. Oxidized or acetylated low density lipoproteins are rapidly cleared by the liver in mice with disruption of the scavenger receptor class A type I/II gene.

    PubMed Central

    Ling, W; Lougheed, M; Suzuki, H; Buchan, A; Kodama, T; Steinbrecher, U P

    1997-01-01

    Oxidized low density lipoprotein (LDL) and acetyl LDL are recognized by the scavenger receptor class A type I/II (SR-AI/II) on macrophages and liver endothelial cells. Several investigators have suggested that there are additional receptors specific for oxidized LDL, but characterization of these alternate receptors for oxidized LDL and evaluation of their quantitative importance in uptake of oxidized LDL has been difficult because of overlapping ligand specificity with SR-AI/II. The purpose of this study was to determine the importance of SR-AI/II in the removal of modified LDL from the bloodstream in vivo. The clearance rate of oxidized LDL from plasma in normal mice was very rapid, and > 90% of injected dose was removed from the blood within 5 min. Clearance rates of oxidized LDL were equally high in SR-AI/II knockout mice, indicating that this receptor is not required for removal of oxidized LDL from plasma. Surprisingly, there was no difference in the clearance rate of acetyl LDL in wild-type and SR-AI/II knockout animals. The plasma clearance of radioiodinated acetyl LDL was almost fully blocked by a 50-fold excess of unlabeled acetyl LDL, but the latter only inhibited oxidized LDL clearance by approximately 5%. Both modified LDLs were cleared mostly by the liver, and there was no difference in the tissue distribution of modified LDL in control and knockout mice. Studies in isolated nonparenchymal liver cells showed that Kupffer cells accounted for most of the uptake of oxidized LDL. Extensively oxidized LDL and LDL modified by exposure to fatty acid peroxidation products were efficient competitors for the uptake of labeled oxidized LDL by SR-AI/II-deficient Kupffer cells, while acetyl LDL and malondialdehyde-modified LDL were relatively poor competitors. PMID:9218499

  8. 25(OH) vitamin D suppresses macrophage adhesion and migration by downregulation of ER stress and scavenger receptor A1 in type 2 diabetes.

    PubMed

    Riek, Amy E; Oh, Jisu; Darwech, Isra; Moynihan, Clare E; Bruchas, Robin R; Bernal-Mizrachi, Carlos

    2014-10-01

    Cardiovascular disease (CVD) is the leading cause of mortality in patients with type 2 diabetes mellitus (T2DM). Vitamin D deficiency is not only more prevalent in diabetics but also doubles the risk of developing CVD. However, it is unknown whether 25-hydroxy vitamin D [25(OH)D3] replacement slows monocyte adhesion and migration, critical mechanisms involved in atherosclerosis progression. In this study, monocytes from vitamin D-deficient diabetic patients were cultured either in the patient's serum or in vitamin D-deficient media with or without 25(OH)D3 treatment. Adding 25(OH)D3 to monocytes cultured in vitamin D-deficient serum or media decreased monocyte adhesion to fibronectin and migration stimulated by monocyte chemotactic protein 1 (MCP-1). Accordingly, 25(OH)D3 decreased adhesion marker β1- and β2-integrin expression and migration receptor chemokine (C-C motif) receptor 2 (CCR2) expression. 25(OH)D3 treatment downregulated monocyte endoplasmic reticulum (ER) stress and scavenger receptor class A, type 1 (SR-A1) expression. The absence of SR-A1 prevented the increased macrophage adhesion and migration induced by vitamin D deficiency. Moreover, the absence of SR-A1 prevented the induction of adhesion and migration and expression of their associated membrane receptors by Thapsigargin, an ER stress inducer. These results identify cellular activation of monocyte/macrophage vitamin D signaling through 25(OH)D3 as a potential mechanism that could modulate adhesion and migration in diabetic subjects. This article is part of a Special Issue entitled '16th Vitamin D Workshop'. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Human serum albumin incorporating synthetic heme: red blood cell substitute without hypertension by nitric oxide scavenging.

    PubMed

    Tsuchida, Eishun; Komatsu, Teruyuki; Matsukawa, Yasuko; Nakagawa, Akito; Sakai, Hiromi; Kobayashi, Koichi; Suematsu, Makoto

    2003-02-01

    The administration of extracellular, hemoglobin-based oxygen carriers often elicits an acute increase in blood pressure by vasoconstriction. This side effect is now recognized to be due to the depletion of nitric oxide (endothelial-derived relaxing factor) by the extravasuated hemoglobins. We have recently found that the administration of a recombinant human serum albumin (rHSA)-based oxygen carrier involving synthetic tetraphenyporphinatoiron(II) derivative (FeP) (rHSA-FeP) does not induce such hypertensive action, because of its low permeability through the vascular endothelium. The heart rate responses after the rHSA-FeP injection were also negligibly small. Visualization of the intestinal microcirculatory changes clearly revealed the widths of the venule and arteriole to be fairly constant. The entirely synthetic rHSA-FeP becomes a promising material as a new type of red blood cell substitute. Copyright 2002 Wiley Periodicals Inc. J Biomed Mater Res 64A: 257-261, 2003

  10. Reactivity and endogenous modification by nitrite and hydrogen peroxide: does human neuroglobin act only as a scavenger?

    PubMed Central

    Nicolis, Stefania; Monzani, Enrico; Ciaccio, Chiara; Ascenzi, Paolo; Moens, Luc; Casella, Luigi

    2007-01-01

    NGB (human neuroglobin), a recently discovered haem protein of the globin family containing a six-co-ordinated haem, is expressed in nervous tissue, but the physiological function of NGB is currently unknown. As well as playing a role in neuronal O2 homoeostasis, NGB is thought to act as a scavenger of reactive species. In the present study, we report on the reactivity of metNGB (ferric-NGB), which accumulates in vivo as a result of the reaction of oxyNGB (oxygenated NGB) with NO, towards NO2− and H2O2. NO2− co-ordination of the haem group accounts for the activity of metNGB in the nitration of phenolic substrates. The two different metNGB forms, with and without the internal disulfide bond between Cys46 (seventh residue on the inter-helix region between helices C and D) and Cys55 (fifth residue on helix D), exhibit different reactivity, the former being more efficient in activating NO2−. The kinetics of the reactions, the NO2−-binding studies and the analysis of the nitrated products from different substrates all support the hypothesis that metNGB is able to generate an active species with the chemical properties of peroxynitrite, at pathophysiological concentrations of NO2− and H2O2. Without external substrates, the targets of the reactive species generated by the metNGB/NO2−/H2O2 system are endogenous tyrosine (resulting in the production of 3-nitrotyrosine) and cysteine (oxidized to sulfinic acid and sulfonic acid) residues. These endogenous modifications were characterized by HPLC-MS/MS (tandem MS) analysis of metNGB after reaction with NO2− and H2O2 under various conditions. The internal S–S bond affects the functional properties of the protein. Therefore metNGB acts not only as scavenger of toxic species, but also as a target of the self-generated reactive species. Self-modification of the protein may be related to or inhibit its postulated neuroprotective activity. PMID:17600531

  11. TmSR-C, scavenger receptor class C, plays a pivotal role in antifungal and antibacterial immunity in the coleopteran insect Tenebrio molitor.

    PubMed

    Kim, Soo Gon; Jo, Yong Hun; Seong, Jeong Hwan; Park, Ki Beom; Noh, Mi Young; Cho, Jun Ho; Ko, Hye Jin; Kim, Chang Eun; Tindwa, Hamisi; Patnaik, Bharat Bhusan; Bang, In Seok; Lee, Yong Seok; Han, Yeon Soo

    2017-10-01

    Scavenger receptors (SRs) constitute a family of membrane-bound receptors that bind to multiple ligands. The SR family of proteins is involved in removing cellular debris, oxidized low-density lipoproteins, and pathogens. Specifically, class C scavenger receptors (SR-C) have also been reported to be involved in phagocytosis of gram-positive and -negative bacteria in Drosophila and viruses in shrimp. However, reports are unavailable regarding the role of SR-C in antifungal immune mechanisms in insects. In this study, a full-length Tenebrio molitor SR-C (TmSR-C) sequence was obtained by 5'- and 3'-Rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The TmSR-C full-length cDNA comprised 1671 bp with 5'- and 3'-untranslated regions of 23- and 107-bp, respectively. TmSR-C encodes a putative protein of 556 amino acid residues that is constitutively expressed in all tissues of late instar larvae and 2-day-old adults, with the highest transcript levels observed in hemocytes of larvae and adults. TmSR-C mRNA showed a 2.5-fold and 3-fold increase at 24 and 6 h after infection with Candida albicans and β-glucan, respectively. Immunoassay with TmSR-C polyclonal antibody showed induction of the putative protein in the cytosols of hemocytes at 3 h after inoculation of C. albicans. RNA interference (RNAi)-based gene silencing and phagocytosis assays were used to understand the role of TmSR-C in antifungal immunity. Silencing of TmSR-C transcripts reduced the survivability of late instar larvae at 2 days post-inoculation of C. albicans, Escherichia coli, or Staphylococcus aureus. Furthermore, in TmSR-C-silenced larvae, there was a decline in the rate of microorganism phagocytosis. Taken together, results of this study suggest that TmSR-C plays a pivotal role in phagocytosing not only fungi but also gram-negative and -positive bacteria in T. molitor. Copyright © 2017. Published by Elsevier Ltd.

  12. Cholesterol depletion induces PKA-mediated basolateral-to-apical transcytosis of the scavenger receptor class B type I in MDCK cells

    PubMed Central

    Burgos, Patricia V.; Klattenhoff, Carla; de la Fuente, Erwin; Rigotti, Attilio; González, Alfonso

    2004-01-01

    Cholesterol-based membrane microdomains, or lipid rafts, are believed to play important, yet poorly defined, roles in protein trafficking and signal transduction. In polarized epithelial cells, the current view is that rafts are involved in apical but not in basolateral protein transport from the trans-Golgi network (TGN). We report here that cholesterol is required in a post-TGN mechanism of basolateral regionalization. Permanently transfected Madin-Darby canine kidney cells segregated the caveolae/raft-associated high-density lipoprotein scavenger receptor class B type I (SR-BI) predominantly to the basolateral domain where it was constitutively internalized and recycled basolaterally. Acute cholesterol depletion did not significantly alter SR-BI internalization, implying a cholesterol depletion-insensitive endocytic process but instead induced its transcytosis through a protein kinase A (PKA)- and microtubule-dependent mechanism. Forskolin also elicited SR-BI transcytosis. The basolateral distribution of endogenous epidermal growth factor receptor remained unaffected. Strikingly, cholesterol depletion induced PKA activity without increasing the cAMP levels. Thus, our results are consistent with a scenario in which cholesterol-based rafts promote internalization and basolateral recycling of internalized SR-BI whereas a PKA pool sensitive to cholesterol depletion mediates SR-BI transcytosis. Regulated transcytosis of SR-BI may provide an additional mechanism to control cholesterol homeostasis. These results disclose relationships between cholesterol-based rafts and PKA activity operating in a post-TGN mechanism of regulated apical-to-basolateral cell surface protein distribution. PMID:15007173

  13. Chronic psychosocial stress in male mice causes an up-regulation of scavenger receptor class B type 1 protein in the adrenal glands.

    PubMed

    Füchsl, Andrea M; Uschold-Schmidt, Nicole; Reber, Stefan O

    2013-07-01

    Mice exposed to chronic subordinate colony housing (CSC, 19 days) show an exaggerated adrenal corticosterone response to an acute heterotypic stressor (elevated platform (EPF), 5 min) despite no difference from EPF-exposed single-housed control (SHC) mice in corticotropin (ACTH) secretion. In the present study, we asked the question whether this CSC-induced increase in adrenal capability to produce and secrete corticosterone is paralleled by an enhanced adrenal availability and/or mobilization capacity of the corticosterone precursor molecule cholesterol. Employing oil-red staining and western blot analysis we revealed comparable relative density of cortical lipid droplets and relative protein expression of hormone-sensitive lipase, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and low-density lipoprotein receptor (LDL-R) between CSC and SHC mice. However, relative protein expression of the scavenger receptor class B type 1 (SR-BI) was increased following CSC exposure. Moreover, analysis of plasma high-density lipoprotein-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) revealed increased LDL-C levels in CSC mice. Together with the pronounced increase in adrenal weight, evidently mediated by hyperplasia of adrenocortical cells, these data strongly indicate an enhanced adrenal availability of and capacity to mobilize cholesterol in chronic psychosocially-stressed mice, contributing to their increased in vivo corticosterone response during acute heterotypic stressor exposure.

  14. Class A macrophage scavenger receptor gene expression levels in peripheral blood mononuclear cells specifically increase in patients with acute coronary syndrome.

    PubMed

    Nakayama, Masafumi; Kudoh, Takashi; Kaikita, Koichi; Yoshimura, Michihiro; Oshima, Shuichi; Miyamoto, Yoshihiro; Takeya, Motohiro; Ogawa, Hisao

    2008-06-01

    Morbidity and mortality rates are still high among patients with acute coronary syndrome (ACS); moreover, it is clinically difficult to determine precisely which patients will progress satisfactorily. Unstable plaque is characterized by an increased number of activated inflammatory cells, including macrophages and lymphocytes, and an increased release of numerous inflammatory mediators and proteolytic enzymes. Mononuclear cells consist of monocytes/macrophages and lymphocytes and are able to be experimentally isolated. We searched for a specific risk factor for ACS in the peripheral blood mononuclear cells (PBMCs). We examined the expression of 12,625 genes in PBMCs utilizing a gene chip microarray system in ACS patients in acute and chronic stable phases. The gene expression profiles revealed that class A macrophage scavenger receptors (SR-A), among the immune response factors and the receptor activity markers, were the most strongly increased in the acute phase. We examined SR-A gene expression levels of PBMCs using real time RT-PCR in 122 consecutive patients: 32 ACS patients; 41 stable angina patients; and, 49 control subjects. The SR-A gene expression levels of the PBMCs were highest in the ACS patients (p<0.0001). The occurrence of a reattack of a cardiovascular event was significantly lower in the low SR-A group than in the high SR-A group (p<0.001). SR-A gene expression level in the PBMCs specifically increases in patients with ACS, and provides a predictive marker for a reattack of a cardiovascular event.

  15. Scavenging energy from human walking through a shoe-mounted piezoelectric harvester

    NASA Astrophysics Data System (ADS)

    Fan, Kangqi; Liu, Zhaohui; Liu, Haiyan; Wang, Liansong; Zhu, Yingmin; Yu, Bo

    2017-04-01

    This study presents a shoe-mounted nonlinear piezoelectric energy harvester (PEH) with intent to capture energy from human walking. The PEH consists of a piezoelectric cantilever beam magnetically coupled to a ferromagnetic ball and a crossbeam. A sleeve is included to guide the travel of the ball. Experimental measurements and theoretical simulations demonstrate that the proposed design can collect energy from diverse excitation sources with different directions produced by the foot, including vibrations, swing motions, and the compressive force. The ball and the crossbeam sense the swing motion and the compressive force, respectively, and then actuate the piezoelectric beam to function. The piezoelectric beam senses the vibration along the tibial axis and generates electricity. The proposed PEH achieves the superposition of these excitations and generates multiple peaks in voltage output within one gait cycle. The output power generated by the fabricated prototype ranges from 0.03 mW to 0.35 mW when the walking velocity varies from 2 km/h to 8 km/h.

  16. Human receptors for sweet and umami taste

    PubMed Central

    Li, Xiaodong; Staszewski, Lena; Xu, Hong; Durick, Kyle; Zoller, Mark; Adler, Elliot

    2002-01-01

    The three members of the T1R class of taste-specific G protein-coupled receptors have been hypothesized to function in combination as heterodimeric sweet taste receptors. Here we show that human T1R2/T1R3 recognizes diverse natural and synthetic sweeteners. In contrast, human T1R1/T1R3 responds to the umami taste stimulus l-glutamate, and this response is enhanced by 5′-ribonucleotides, a hallmark of umami taste. The ligand specificities of rat T1R2/T1R3 and T1R1/T1R3 correspond to those of their human counterparts. These findings implicate the T1Rs in umami taste and suggest that sweet and umami taste receptors share a common subunit. PMID:11917125

  17. An interplay between hypervariable region 1 of the hepatitis C virus E2 glycoprotein, the scavenger receptor BI, and high-density lipoprotein promotes both enhancement of infection and protection against neutralizing antibodies.

    PubMed

    Bartosch, Birke; Verney, Géraldine; Dreux, Marlène; Donot, Peggy; Morice, Yoann; Penin, François; Pawlotsky, Jean-Michel; Lavillette, Dimitri; Cosset, Francois-Loïc

    2005-07-01

    Hepatitis C virus (HCV) circulates in the bloodstream in different forms, including complexes with immunoglobulins and/or lipoproteins. To address the significance of such associations, we produced or treated HCV pseudoparticles (HCVpp), a valid model of HCV cell entry and its inhibition, with naïve or patient-derived sera. We demonstrate that infection of hepatocarcinoma cells by HCVpp is increased more than 10-fold by human serum factors, of which high-density lipoprotein (HDL) is a major component. Infection enhancement requires scavenger receptor BI, a molecule known to mediate HDL uptake into cells as well as HCVpp entry, and involves conserved amino acid positions in hypervariable region 1 (HVR1) of the E2 glycoprotein. Additionally, we show that the interaction with human serum or HDL, but not with low-density lipoprotein, leads to the protection of HCVpp from neutralizing antibodies, including monoclonal antibodies and antibodies present in patient sera. Finally, the deletion or mutation of HVR1 in HCVpp abolishes infection enhancement and leads to increased sensitivity to neutralizing antibodies/sera compared to that of parental HCVpp. Altogether, these results assign to HVR1 new roles which are complementary in helping HCV to survive within its host. Besides immune escape by mutation, HRV1 can mediate the enhancement of cell entry and the protection of virions from neutralizing antibodies. By preserving a balance between these functions, HVR1 may be essential for the viral persistence of HCV.

  18. Modulation of genotoxic effects in asbestos-exposed primary human mesothelial cells by radical scavengers, metal chelators and a glutathione precursor.

    PubMed

    Poser, Ina; Rahman, Qamar; Lohani, Mohtashim; Yadav, Santosh; Becker, Hans-Henner; Weiss, Dieter G; Schiffmann, Dietmar; Dopp, Elke

    2004-04-11

    The genotoxicity of asbestos fibers is generally mediated by reactive oxygen species (ROS) and by insufficient antioxidant protection. To further elucidate which radicals are involved in asbestos-mediated genotoxicity and to which extent, we have carried out experiments with the metal chelators deferoxamine (DEF) and phytic acid (PA), and with the radical scavengers superoxide dismutase (SOD), dimethylthiourea (DMTU) and the glutathione precursor Nacystelyn trade mark (NAL). We investigated the influence of these compounds on the potency of crocidolite, an amphibole asbestos fiber with a high iron content (27%), and chrysotile, a serpentine asbestos fiber with a low iron content (2%), to induce micronuclei (MN) in human mesothelial cells (HMC) after an exposure time of 24-72 h. Our results show that the number of crocidolite-induced MN is significantly reduced after pretreatment of fibers with PA and DEF. This effect was not observed with chrysotile. In contrast, simultaneous treatment of cells with asbestos and the OH*scavenging DMTU or the O2- -scavenging SOD significantly decreased the number of MN induced by chrysotile and crocidolite. In particular, DMTU almost completely suppressed micronucleus induction by both fiber types. A similar effect was observed in the presence of the H(2)O(2)-scavenging NAL after chrysotile treatment of HMC. By means of kinetochore analysis, it could be shown that the number of clastogenic events is decreased after PA and DEF pretreatment of fibers as well as after application of the above-mentioned scavengers. Our results show that chrysotile asbestos induces an increased release of H(2)O(2) in contrast to crocidolite. Also, the iron content of the fiber plays an important role in radical formation, but nevertheless, chrysotile produces oxy radicals to a similar extent as crocidolite, probably by phagocytosis-mediated oxidative bursting.

  19. [The role of the class A scavenger receptors, SR-A and MARCO, in the immune system. Part 1. The structure of receptors, their ligand binding repertoires and ability to initiate intracellular signaling].

    PubMed

    Józefowski, Szczepan

    2012-02-29

    Recognition of pathogens by innate immune cells is mediated by pattern recognition receptors (PRR), which include scavenger receptors (SR). The class A SR, SR-A/CD204 and MARCO, are characterized by the presence of collagenous and SR cysteine-rich domains in their extracellular portions. Both receptors are expressed mainly on macrophages and dendritic cells. Thanks to their ability to bind to a wide range of polyanionic ligands, the class A SR may participate in numerous functions of these cells, such as endocytosis, and adhesion to extracellular matrix and to other cells. Among SR-A ligands are oxidized lipoproteins and β-amyloid fibrils, which link SR-A to the pathogenesis of arteriosclerosis and Alzheimer's disease. Despite the demonstration of class A SR involvement in so many processes, the lack of selective ligands precluded reaching definite conclusions concerning their signaling abilities. Using specific receptor ligation with antibodies, we showed that SR-A and MARCO trigger intracellular signaling, modulating pro-inflammatory and microbicidal activities of macrophages. Surprisingly, despite similarities in structure and ligand binding repertoires, SR-A and MARCO exert opposite effects on interleukin-12 (IL-12) production in macrophages. SR-A ligation also stimulated H₂O₂ and IL-10 production, but had no effect on the release of several other cytokines. These limited effects of specific SR-A ligation contrast with generalized enhancement of immune responses observed in SR-A-deficient mice. Recent studies have revealed that many of these effects of SR-A deficiency may be caused by compensatory changes in the expression of other receptors and/or disinhibition of signal transduction from receptors belonging to the Toll/IL-1R family, rather than by the loss of the receptor function of SR-A.

  20. Beta adrenergic receptors in human cavernous tissue

    SciTech Connect

    Dhabuwala, C.B.; Ramakrishna, C.V.; Anderson, G.F.

    1985-04-01

    Beta adrenergic receptor binding was performed with /sup 125/I iodocyanopindolol on human cavernous tissue membrane fractions from normal tissue and transsexual procedures obtained postoperatively, as well as from postmortem sources. Isotherm binding studies on normal fresh tissues indicated that the receptor density was 9.1 fmoles/mg. with a KD of 23 pM. Tissue stored at room temperature for 4 to 6 hours, then at 4C in saline solution for 19 to 20 hours before freezing showed no significant changes in receptor density or affinity, and provided evidence for the stability of postmortem tissue obtained within the same time period. Beta receptor density of 2 cavernous preparations from transsexual procedures was not significantly different from normal control tissues, and showed that high concentrations of estrogen received by these patients had no effect on beta adrenergic receptor density. Displacement of /sup 125/iodocyanopindolol by 5 beta adrenergic agents demonstrated that 1-propranolol had the greatest affinity followed by ICI 118,551, zinterol, metoprolol and practolol. When the results of these displacement studies were subjected to Scatfit, non- linear regression line analysis, a single binding site was described. Based on the relative potency of the selective beta adrenergic agents it appears that these receptors were of the beta 2 subtype.

  1. Imaging dopamine receptors in the human brain by position tomography

    SciTech Connect

    Wagner, H.N. Jr.; Burns, H.D.; Dannals, R.F.; Wong, D.F.; Langstrom, B.; Duelfer, T.; Frost, J.J.; Ravert, H.T.; Links, J.M.; Rosenbloom, S.B.

    1983-01-01

    Neurotransmitter receptors may be involved in a number of neuropsychiatric disease states. The ligand 3-N-(/sup 11/C)methylspiperone, which preferentially binds to dopamine receptors in vivo, was used to image the receptors by positron emission tomography scanning in baboons and in humans. This technique holds promise for noninvasive clinical studies of dopamine receptors in humans.

  2. CXCL16 Is Expressed in Podocytes and Acts as a Scavenger Receptor for Oxidized Low-Density Lipoprotein

    PubMed Central

    Gutwein, Paul; Abdel-Bakky, Mohamed Sadek; Schramme, Anja; Doberstein, Kai; Kämpfer-Kolb, Nicole; Amann, Kerstin; Hauser, Ingeborg A.; Obermüller, Nicholas; Bartel, Christine; Abdel-Aziz, Abdel-Aziz H.; El Sayed, El Sayed M.; Pfeilschifter, Josef

    2009-01-01

    Podocytes are a crucial cell type in the kidney and play an important role in the pathology of glomerular kidney diseases like membranous nephropathy (MN). The identification of new factors involved in the progression of glomerular kidney diseases is of great importance to the development of new strategies for the treatment of renal injury. Here we demonstrate that CXCL16 and ADAM10 are constitutively expressed in human podocytes in normal renal tissue. Proinflammatory cytokines like interferon-γ and tumor necrosis factor-α induced the expression of cellular CXCL16 and the release of its soluble form from human podocytes. Using different metalloproteinase inhibitors, we provide evidence that ADAM10 is involved in the interferon-γ- and tumor necrosis factor-α-induced shedding of CXCL16 from human podocytes. In addition, ADAM10 knockdown by siRNA significantly increased both CXCL16 levels and, surprisingly, its ADAM17-mediated release. Notably, targeting of CXCL16 in human podocytes both decreased the chemotaxis of CXCR6-expressing T cells and strongly reduced oxidized low-density lipoprotein uptake in human podocytes. Importantly, in kidney biopsies of patients with MN, increased glomerular CXCL16 expression was accompanied by high levels of oxidized low-density lipoprotein and decreased expression of ADAM10. In addition, we found increased glomerular ADAM17 expression in patients diagnosed with MN. In summary, we presume important roles for CXCL16, ADAM10, and ADAM17 in the development of MN, suggesting these proteins as new therapeutic targets in this glomerular kidney disease. PMID:19435795

  3. Determination of in vitro free radical scavenging and antiproliferative effect of Pennisetum alopecuroides on cultured A549 human lung cancer cells

    PubMed Central

    Mathew, Githa Elizabeth; Mathew, Bijo; Gokul, S.; Krishna, Rahul; Farisa, M. P.

    2015-01-01

    Context: Pennisetum alopecuroides (Poaceae) is a grass predominantly distributed in tropics and sub tropics. It is used as a cattle feed in many regions. Aim: The objective of the present study was to investigate the in vitro free radical scavenging and antiproliferative activity of ethanol extract of P. alopecuroides (EEPA) on cultured A549 human lung cancer cell lines. Settings and Design: The anti-oxidant activity of ethanol extract was evaluated at dose level 12.5, 25, 50, 100, and 200 μg/ml. The in vitro antiproliferative activity was measured at doses of 10, 50, and 100 μg/ml. Materials and Methods: The free radical scavenging activity of the EEPA was determined by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) method and in vitro antiproliferative activity on A549 human lung cancer cells was conducted by using MTT assay method. Results: The phytochemical screening revealed that the P. alopecuroides contained alkaloids, tannins, saponins, and flavonoids as the major secondary metabolites. The IC50 value of DPPH scavenging activity was found to be 44.41 μg/ml and 31.02 μg/ml  for a mixture of EEPA and standard ascorbic acid, respectively. In vitro MTT assay showed that EEPA had anti-proliferation effects on A549 cells in a dose dependent manner. Conclusions: This is the 1st time a pharmacological exploration of P. alopecuroides grasses has been conducted. We have shown that P. alopecuroides exhibits good free radical scavenging and strong in vitro cytotoxic activities against human lung cancer cell lines. PMID:26120234

  4. Scavenger receptor for lipoteichoic acid is involved in the potent ability of Lactobacillus plantarum strain L-137 to stimulate production of interleukin-12p40.

    PubMed

    Hatano, Shinya; Hirose, Yoshitaka; Yamamoto, Yoshihiro; Murosaki, Shinji; Yoshikai, Yasunobu

    2015-04-01

    Heat-killed Lactobacillus plantarum strain L-137 (HK L-137) is a more potent inducer of interleukin (IL)-12 than other heat-killed Lactobacillus strains. To elucidate the mechanism involved in this IL-12p40 induction, we compared HK L-137 with heat-killed L. plantarum strain JCM1149 (HK JCM1149) by nuclear magnetic resonance and mass spectrometry. Results showed that HK L-137 contained lipoteichoic acid (LTA) with a chemical structure similar to that of JCM1149, except for a lower degree of glucosyl substitution in the poly(glycerol phosphate) backbone. Lysozyme sensitivity and electrophoretic moiety analysis revealed that HK L-137 exposed more LTA on its cell surface than HK JCM1149. Phagocytosis of HK L-137 by splenic adherent cells was significantly greater than that of HK JCM1149. Anti-LTA antibody and anti-scavenger receptor-A (SR-A) antibody selectively inhibited phagocytosis of HK L-137, as well as IL-12p40 production, by splenic adherent cells. Thus, a higher efficiency of phagocytosis of HK L-137 via SR-A for LTA is responsible for the potent IL-12p40 induction.

  5. Increased Susceptibility of  Thymocytes to Apoptosis in Mice Lacking AIM, a Novel Murine Macrophage-derived Soluble Factor Belonging to the Scavenger Receptor Cysteine-rich Domain Superfamily

    PubMed Central

    Miyazaki, Toru; Hirokami, Yumiko; Matsuhashi, Nobuyuki; Takatsuka, Hisakazu; Naito, Makoto

    1999-01-01

    Apoptosis of cells must be regulated both positively and negatively in response to a variety of stimuli in the body. Various environmental stresses are known to initiate apoptosis via differential signal transduction cascades. However, induction of signals that may inhibit apoptosis is poorly understood, although a number of intracellular molecules that mediate inhibition of apoptosis have been identified. Here we present a novel murine macrophage-specific 54-kD secreted protein which inhibits apoptosis (termed AIM, for apoptosis inhibitor expressed by macrophages). AIM belongs to the macrophage scavenger receptor cysteine-rich domain superfamily (SRCR-SF), members of which share a highly homologous conserved cysteine-rich domain. In AIM-deficient mice, the thymocyte numbers were diminished to half those in wild-type mice, and CD4/CD8 double-positive (DP) thymocytes were strikingly more susceptible to apoptosis induced by both dexamethasone and irradiation in vivo. Recombinant AIM protein significantly inhibited cell death of DP thymocytes in response to a variety of stimuli in vitro. These results indicate that in the thymus, AIM functions in trans to induce resistance to apoptosis within DP cells, and thus supports the viability of DP thymocytes before thymic selection. PMID:9892623

  6. Molecular cloning, genomic structure, and tissue distribution of EW135, a novel chicken egg white protein with group B scavenger receptor cysteine-rich domains.

    PubMed

    Yoo, Whayoung; Nakamura, Tomohiro; Asanuma, Hideki; Matsushita, Misao

    2013-11-01

    Approximately 80 proteins are reported to be present in chicken egg white. The major function of egg white proteins isolated so far is to defend the egg yolk against infections. We recently isolated a novel protein termed EW135 from chicken egg white. In this paper, we have determined the complete amino acid sequence of EW135 based on cDNA cloning. EW135 consists of 970 amino acids with a putative signal peptide of 17 amino acids. It is composed exclusively of tandem repeats of nine group B scavenger receptor cysteine-rich (SRCR) domains separated by eight seven-amino acid peptides. The features of consensus sequences found in the group B SRCR domain were well conserved in EW135. The EW135 gene consists of putative 11 exons, with each SRCR domain being encoded by a single exon. Reverse transcription PCR showed that EW135 is expressed in only the oviduct among the 11 types of tissues tested. EW135 is a second soluble protein belonging to the group B SRCR domain superfamily identified in chickens. One of the important functions of proteins belonging to the group B SRCR domain superfamily is to recognize pathogens in innate immunity. It is, therefore, conceivable that EW135 could be involved in host defense in egg white.

  7. Carbamate Insecticides Target Human Melatonin Receptors.

    PubMed

    Popovska-Gorevski, Marina; Dubocovich, Margarita L; Rajnarayanan, Rajendram V

    2017-02-20

    Carbaryl (1-naphthyl methylcarbamate) and carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) are among the most toxic insecticides, implicated in a variety of diseases including diabetes and cancer among others. Using an integrated pharmacoinformatics based screening approach, we have identified these insecticides to be structural mimics of the neurohormone melatonin and were able to bind to the putative melatonin binding sites in MT1 and MT2 melatonin receptors in silico. Carbaryl and carbofuran then were tested for competition with 2-[(125)I]-iodomelatonin (300 pM) binding to hMT1 or hMT2 receptors stably expressed in CHO cells. Carbaryl and carbofuran showed higher affinity for competition with 2-[(125)I]-iodomelatonin binding to the hMT2 compared to the hMT1 melatonin receptor (33 and 35-fold difference, respectively) as predicted by the molecular modeling. In the presence of GTP (100 μM), which decouples the G-protein linked receptors to modulate signaling, the apparent efficacy of carbaryl and carbofuran for 2-[(125)I]-iodomelatonin binding for the hMT1 melatonin receptor was not affected but significantly decreased for the hMT2 melatonin receptor compatible with receptor antagonist/inverse agonist and agonist efficacy, respectively. Altogether, our data points to a potentially new mechanism through which carbamate insecticides carbaryl and carbofuran could impact human health by altering the homeostatic balance of key regulatory processes by directly binding to melatonin receptors.

  8. Brain ischaemia induces shedding of a BDNF-scavenger ectodomain from TrkB receptors by excitotoxicity activation of metalloproteinases and γ-secretases.

    PubMed

    Tejeda, Gonzalo S; Ayuso-Dolado, Sara; Arbeteta, Raquel; Esteban-Ortega, Gema M; Vidaurre, Oscar G; Díaz-Guerra, Margarita

    2016-04-01

    Stroke remains a leading cause of death and disability in the world with limited therapies available to restrict brain damage or improve functional recovery after cerebral ischaemia. A promising strategy currently under investigation is the promotion of brain-derived neurotrophic factor (BDNF) signalling through tropomyosin-related kinase B (TrkB) receptors, a pathway essential for neuronal survival and function. However, TrkB and BDNF-signalling are impaired by excitotoxicity, a primary pathological process in stroke also associated with neurodegenerative diseases. Pathological imbalance of TrkB isoforms is critical in neurodegeneration and is caused by calpain processing of BDNF high affinity full-length receptor (TrkB-FL) and an inversion of the transcriptional pattern of the Ntrk2 gene, to favour expression of the truncated isoform TrkB-T1 over TrkB-FL. We report here that both TrkB-FL and neuronal TrkB-T1 also undergo ectodomain shedding by metalloproteinases activated after ischaemic injury or excitotoxic damage of cortical neurons. Subsequently, the remaining membrane-bound C-terminal fragments (CTFs) are cleaved by γ-secretases within the transmembrane region, releasing their intracellular domains (ICDs) into the cytosol. Therefore, we identify TrkB-FL and TrkB-T1 as new substrates of regulated intramembrane proteolysis (RIP), a mechanism that highly contributes to TrkB-T1 regulation in ischaemia but is minor for TrkB-FL which is mainly processed by calpain. However, since the secreted TrkB ectodomain acts as a BDNF scavenger and significantly alters BDNF/TrkB signalling, the mechanism of RIP could contribute to neuronal death in excitotoxicity. These results are highly relevant since they reveal new targets for the rational design of therapies to treat stroke and other pathologies with an excitotoxic component.

  9. Salvianolic acid B inhibits macrophage uptake of modified low density lipoprotein (mLDL) in a scavenger receptor CD36-dependent manner

    PubMed Central

    Bao, Yi; Wang, Li; Xu, Yanni; Yang, Yuan; Wang, Lifei; Si, Shuyi; Cho, Sunghee; Hong, Bin

    2012-01-01

    CD36, a class B scavenger receptor, has been implicated in the pathogenesis of a host of vascular inflammatory diseases. Through a high-throughput screening (HTS) assay for CD36 antagonist, we previously identified salvianolic acid B (SAB), a hydrophilic component derived from the herb Danshen, as a potential candidate. Danshen, the dried roots of Salvia miltiorrhiza, has been widely used in China for the prevention and treatment of atherosclerosis-related disorders. Previous studies showed that SAB acted as an anti-oxidant by preventing lipid peroxidation and oxidized LDL (oxLDL) formation. The present study was to investigate the specificity and efficacy of SAB in the inhibition of CD36-mediated lipid uptake. SAB reduced modified LDL (mLDL) uptake in a dose-dependent manner in phorbol-12-myristate-13-acetate (PMA)-stimulated THP-1 and RAW 264.7 cells. In the CD36 silenced THP-1 cells, SAB had no effect in reducing mLDL uptake, whereas its over-expression in CHO cells reinstates the effect, indicating a specific involvement of SAB in antagonizing the CD36's function. Surface plasmon resonance (SPR) analysis revealed a direct binding of SAB to CD36 with a high affinity (KD =3.74 μM), confirming physical interactions of SAB with the receptor. Additionally, SAB reduced oxLDL-induced CD36 gene expression in the cultured cell lines and primary macrophages. In ApoE KO mice fed a high fat diet, SAB reduced CD36 gene expression and lipid uptake in macrophages, showing its ability to antagonize CD36 pathways in vivo. These results demonstrate that SAB is an effective CD36 antagonist and suggest SAB as a potential anti-atherosclerotic agent. PMID:22658257

  10. An ethanol extract derived from Bonnemaisonia hamifera scavenges ultraviolet B (UVB) radiation-induced reactive oxygen species and attenuates UVB-induced cell damage in human keratinocytes.

    PubMed

    Piao, Mei Jing; Hyun, Yu Jae; Cho, Suk Ju; Kang, Hee Kyoung; Yoo, Eun Sook; Koh, Young Sang; Lee, Nam Ho; Ko, Mi Hee; Hyun, Jin Won

    2012-12-14

    The present study investigated the photoprotective properties of an ethanol extract derived from the red alga Bonnemaisonia hamifera against ultraviolet B (UVB)-induced cell damage in human HaCaT keratinocytes. The Bonnemaisonia hamifera ethanol extract (BHE) scavenged the superoxide anion generated by the xanthine/xanthine oxidase system and the hydroxyl radical generated by the Fenton reaction (FeSO₄ + H₂O₂), both of which were detected by using electron spin resonance spectrometry. In addition, BHE exhibited scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species (ROS) that were induced by either hydrogen peroxide or UVB radiation. BHE reduced UVB-induced apoptosis, as shown by decreased apoptotic body formation and DNA fragmentation. BHE also attenuated DNA damage and the elevated levels of 8-isoprostane and protein carbonyls resulting from UVB-mediated oxidative stress. Furthermore, BHE absorbed electromagnetic radiation in the UVB range (280-320 nm). These results suggest that BHE protects human HaCaT keratinocytes against UVB-induced oxidative damage by scavenging ROS and absorbing UVB photons, thereby reducing injury to cellular components.

  11. Androgen receptor in human endothelial cells

    PubMed Central

    Torres-Estay, Verónica; Carreño, Daniela V; San Francisco, Ignacio F; Sotomayor, Paula; Godoy, Alejandro S; Smith, Gary J

    2015-01-01

    Androgen receptor (AR) is a ligand-inducible transcription factor, and a member of the steroid-thyroid-retinoid receptor superfamily, that mediates the biological effects of androgens in a wide range of physiological and pathological processes. AR expression was identified in vascular cells nearly 20 years ago, and recent research has shown that AR mediates a variety of actions of androgens in endothelial and vascular smooth muscle cells. In this mini-review, we review evidence indicating the importance of AR in human endothelial cell (HUVEC) homeostatic and pathogenic processes. Although a role for AR in the modulation of HUVEC biology is evident, the molecular mechanisms by which AR regulates HUVEC homeostasis and disease processes are not fully understood. Understanding these mechanisms could provide critical insights into the processes of pathogenesis of diseases ranging from cardiovascular disease to cancer that are major causes of human morbidity and mortality. PMID:25563353

  12. Adrenergic receptors in human fetal liver membranes

    SciTech Connect

    Falkay, G.; Kovacs, L. )

    1990-01-01

    The adrenergic receptor binding capacities in human fetal and adult livers were measured to investigate the mechanism of the reduced alpha-1 adrenoreceptor response of the liver associated with a reciprocal increase in beta-adrenoreceptor activity in a number of conditions. Alpha-1 and beta-adrenoreceptor density were determined using {sup 3}H-prazosin and {sup 3}H-dihydroalprenolol, respectively, as radioligand. Heterogeneous populations of beta-adrenoreceptors were found in fetal liver contrast to adult. Decreased alpha-1 and increased beta-receptor density were found which may relate to a decreased level in cellular differentiation. These findings may be important for the investigation of perinatal hypoglycemia of newborns after treatment of premature labor with beta-mimetics. This is the first demonstration of differences in the ratio of alpha-1 and beta-adrenoceptors in human fetal liver.

  13. Scavenger receptor class B type I (SR-BI) is involved in vitamin E transport across the enterocyte

    PubMed Central

    Reboul, Emmanuelle; Klein, Alexis; Bietrix, Florence; Gleize, Béatrice; Malezet-Desmoulins, Christiane; Schneider, Martina; Margotat, Alain; Lagrost, Laurent; Collet, Xavier; Borel, Patrick

    2006-01-01

    Although cellular uptake of vitamin E was initially described as a passive process, recent studies in the liver and brain have shown that SR-BI is involved in this phenomenon. As SR-BI is expressed at high levels in the intestine, the present study addressed the involvement of SR-BI in vitamin E trafficking across enterocytes. Apical uptake and efflux of the main dietary forms of vitamin E was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium. RRR-γ-tocopherol bioavailability was compared between wild-type mice and mice overexpressing SR-BI in the intestine. The effect of vitamin E on enterocyte SR-BI mRNA levels was measured by real-time quantitative RT-PCR. Concentration-dependent curves for vitamin E uptake were similar for RRR-α-, RRR-γ- and DL-α-tocopherol. RRR-α-tocopherol transport was dependent on incubation temperature, with a 60% reduction in absorption at 4°C compared to 37°C (p<0.05). Vitamin E flux in enterocytes was directed from the apical to the basal side, with a relative 10-fold reduction in the transfer process when measured in the opposite direction (p<0.05). Co-incubation with cholesterol, γ-tocopherol or lutein significantly impaired α-tocopherol absorption. Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 80% of vitamin E uptake and up to 30 % of apical vitamin E efflux (p<0.05), and similar results were obtained for RRR-γ-tocopherol. SR-BI mRNA levels were not significantly modified after a 24-hour incubation of Caco-2 cells with vitamin E. Finally, RRR-γ-tocopherol bioavailability was 2.7-fold higher in mice overexpressing SR-BI than in wild-type mice (p<0.05). The present data show for the first time that vitamin E intestinal absorption is, at least partly, mediated by SR-BI. PMID:16380385

  14. Evaluation of the free-radical-scavenging activity of diclofenac acid on the free-radical-induced haemolysis of human erythrocytes.

    PubMed

    Tang, You-Zhi; Liu, Zai-Qun

    2006-05-01

    Free-radical-induced peroxidation in-vivo is regarded as the aetiology of some diseases and free-radical-scavenging drugs, also called antioxidants (AH), have been widely used to overcome oxidative stress. An in-vitro experimental method, 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH)-induced haemolysis of human erythrocytes can be applied to assess the free-radical-scavenging activity of a drug. The major objectives of this work were focused on three aspects. Firstly, introduction of the chemical kinetic deduction of free-radical-initiating reaction to AAPH-induced haemolysis of human erythrocytes, by which the number of free radicals trapped by an antioxidant, n, can be obtained after finding the quantitative relationship between the inhibition period (t(inh)) and the concentration of the antioxidant, t(inh) = (n/Ri) [AH]. Ri, the free-radical-initiating rate, was initially confirmed by using alpha-tocopherol (VE) whose n was taken as 2. Secondly, the free-radical-scavenging activity of diclofenac acid (DaH) and its sodium salt (DaNaH) was assessed. It has been found that DaH and DaNaH protect human erythrocytes against AAPH-induced haemolysis dose-dependently. In particular, the n values of DaH and DaNaH (4.96 and 3.60) were much higher than some traditional antioxidants, such as 6-hydroxyl-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox, a water-soluble structural analogue of VE, n = 0.30) and L-ascorbic acid (VC, n = 0.25), and L-ascorbyl-6-laurate (VC-12, a lipophilic structural analogue of VC, n = 1.11). Moreover, the free-radical-scavenging activity of lipophilic antioxidants is higher than the corresponding water-soluble species. Thirdly, the free-radical-scavenging activity of mixed antioxidants, VE + DaH, VC-12 + DaH, Trolox + DaNaH and VC + DaNaH, was revealed. The n value of VC, VC-12, VE and Trolox increase in the case of mixed usage with DaH and DaNaH, implying that diclofenac acid can repair the radical of these antioxidants. Thus, a mutual

  15. IL-21 Receptor Expression in Human Tendinopathy

    PubMed Central

    Campbell, Abigail L.; Smith, Nicola C.; Reilly, James H.; Kerr, Shauna C.; Leach, William J.; Fazzi, Umberto G.; Rooney, Brian P.; Murrell, George A. C.; Millar, Neal L.

    2014-01-01

    The pathogenetic mechanisms underlying tendinopathy remain unclear, with much debate as to whether inflammation or degradation has the prominent role. Increasing evidence points toward an early inflammatory infiltrate and associated inflammatory cytokine production in human and animal models of tendon disease. The IL-21/IL-21R axis is a proinflammatory cytokine complex that has been associated with chronic inflammatory diseases including rheumatoid arthritis and inflammatory bowel disease. This project aimed to investigate the role and expression of the cytokine/receptor pair IL-21/IL-21R in human tendinopathy. We found significantly elevated expression of IL-21 receptor message and protein in human tendon samples but found no convincing evidence of the presence of IL-21 at message or protein level. The level of expression of IL-21R message/protein in human tenocytes was significantly upregulated by proinflammatory cytokines (TNFα/IL-1β) in vitro. These findings demonstrate that IL-21R is present in early human tendinopathy mainly expressed by tenocytes and macrophages. Despite a lack of IL-21 expression, these data again suggest that early tendinopathy has an inflammatory/cytokine phenotype, which may provide novel translational targets in the treatment of tendinopathy. PMID:24757284

  16. Hormone Receptor Expression in Human Fascial Tissue

    PubMed Central

    Fede, C.; Albertin, G.; Petrelli, L.; Sfriso, M.M.; Biz, C.; De Caro, R.

    2016-01-01

    Many epidemiologic, clinical, and experimental findings point to sex differences in myofascial pain in view of the fact that adult women tend to have more myofascial problems with respect to men. It is possible that one of the stimuli to sensitization of fascial nociceptors could come from hormonal factors such as estrogen and relaxin, that are involved in extracellular matrix and collagen remodeling and thus contribute to functions of myofascial tissue. Immunohistochemical and molecular investigations (real-time PCR analysis) of relaxin receptor 1 (RXFP1) and estrogen receptor-alpha (ERα) localization were carried out on samples of human fascia collected from 8 volunteers patients during orthopedic surgery (all females, between 42 and 70 yrs, divided into pre- and post-menopausal groups), and in fibroblasts isolated from deep fascia, to examine both protein and RNA expression levels. We can assume that the two sex hormone receptors analyzed are expressed in all the human fascial districts examined and in fascial fibroblasts culture cells, to a lesser degree in the post-menopausal with respect to the pre-menopausal women. Hormone receptor expression was concentrated in the fibroblasts, and RXFP1 was also evident in blood vessels and nerves. Our results are the first demonstrating that the fibroblasts located within different districts of the muscular fasciae express sex hormone receptors and can help to explain the link between hormonal factors and myofascial pain. It is known, in fact, that estrogen and relaxin play a key role in extracellular matrix remodeling by inhibiting fibrosis and inflammatory activities, both important factors affecting fascial stiffness and sensitization of fascial nociceptors. PMID:28076930

  17. The Scientist Scavenger Hunt.

    ERIC Educational Resources Information Center

    Morphew, Valerie N.; Key, Kathleen

    1994-01-01

    Using a well-planned scavenger hunt, students' awareness of the significance of minorities and women in science is enhanced. Provides a sample scavenger hunt and resource list as well as activities for extension. (ZWH)

  18. The Scientist Scavenger Hunt.

    ERIC Educational Resources Information Center

    Morphew, Valerie N.; Key, Kathleen

    1994-01-01

    Using a well-planned scavenger hunt, students' awareness of the significance of minorities and women in science is enhanced. Provides a sample scavenger hunt and resource list as well as activities for extension. (ZWH)

  19. Increased DNA methylation of scavenger receptor class B type I contributes to inhibitory effects of prenatal caffeine ingestion on cholesterol uptake and steroidogenesis in fetal adrenals.

    PubMed

    Wu, Dong-Mei; He, Zheng; Ma, Liang-Peng; Wang, Lin-Long; Ping, Jie; Wang, Hui

    2015-06-01

    Steroid hormones synthesized from cholesterol in the fetal adrenal are crucial for fetal development. We have observed the inhibited fetal adrenal corticosterone synthesis and increased intrauterine growth retardation (IUGR) rate in rats under prenatal caffeine ingestion. The aim of this study is to evaluate the effects of prenatal caffeine ingestion on cholesterol supply in fetal adrenal steroidogenesis in rats and explore the underlying epigenetic mechanisms. Pregnant Wistar rats were treated with 60 mg/kg · d caffeine from gestational day (GD) 7 to GD17. Histological changes of fetal adrenals and increased IUGR rates were observed in the caffeine group. There were significantly decreased steroid hormone contents and cholesterol supply in caffeine-treated fetal adrenals. Data from the gene expression array suggested that prenatal caffeine ingestion caused increased expression of genes related to DNA methylation and decreased expression of genes related to cholesterol uptake. The following conjoint analysis of DNA methylation array with these differentially expressed genes suggested that scavenger receptor class B type I (SR-BI) may play an important role in caffeine-induced cholesterol supply deficiency. Moreover, real-time RT-PCR and immunohistochemical detection certified the inhibitory effects of caffeine on both mRNA expression and protein expression of SR-BI in the fetal adrenal. And the increased DNA methylation frequency in the proximal promoter of SR-BI was confirmed by bisulfite-sequencing PCR. In conclusion, prenatal caffeine ingestion can induce DNA hypermethylation of the SR-BI promoter in the rat fetal adrenal. These effects may lead to decreased SR-BI expression and cholesterol uptake, which inhibits steroidogenesis in the fetal adrenal.

  20. Cell-specific expression of the macrophage scavenger receptor gene is dependent on PU.1 and a composite AP-1/ets motif.

    PubMed Central

    Moulton, K S; Semple, K; Wu, H; Glass, C K

    1994-01-01

    The type I and II scavenger receptors (SRs) are highly restricted to cells of monocyte origin and become maximally expressed during the process of monocyte-to-macrophage differentiation. In this report, we present evidence that SR genomic sequences from -245 to +46 bp relative to the major transcriptional start site were sufficient to confer preferential expression of a reporter gene to cells of monocyte and macrophage origin. This profile of expression resulted from the combinatorial actions of multiple positive and negative regulatory elements. Positive transcriptional control was primarily determined by two elements, located 181 and 46 bp upstream of the major transcriptional start site. Transcriptional control via the -181 element was mediated by PU.1/Spi-1, a macrophage and B-cell-specific transcription factor that is a member of the ets domain gene family. Intriguingly, the -181 element represented a relatively low-affinity binding site for Spi-B, a closely related member of the ets domain family that has been shown to bind with relatively high affinity to other PU.1/Spi-1 binding sites. These observations support the idea that PU.1/Spi-1 and Spi-B regulate overlapping but nonidentical sets of genes. The -46 element represented a composite binding site for a distinct set of ets domain proteins that were preferentially expressed in monocyte and macrophage cell lines and that formed ternary complexes with members of the AP-1 gene family. In concert, these observations suggest a model for how interactions between cell-specific and more generally expressed transcription factors function to dictate the appropriate temporal and cell-specific patterns of SR expression during the process of macrophage differentiation. Images PMID:8007948

  1. Regulation of expression and function of scavenger receptor class B, type I (SR-BI) by Na+/H+ exchanger regulatory factors (NHERFs).

    PubMed

    Hu, Zhigang; Hu, Jie; Zhang, Zhonghua; Shen, Wen-Jun; Yun, C Chris; Berlot, Catherine H; Kraemer, Fredric B; Azhar, Salman

    2013-04-19

    Scavenger receptor class B, type I (SR-BI) binds HDL and mediates selective delivery of cholesteryl esters (CEs) to the liver, adrenals, and gonads for product formation (bile acids and steroids). Because relatively little is known about SR-BI posttranslational regulation in steroidogenic cells, we examined the roles of Na(+)/H(+) exchanger regulatory factors (NHERFs) in regulating SR-BI expression, SR-BI-mediated selective CE uptake, and steroidogenesis. NHERF1 and NHERF2 mRNA and protein are expressed at varying levels in model steroidogenic cell lines and the adrenal, with only low expression of PDZK1 (NHERF3) and NHERF4. Dibutyryl cyclic AMP decreased NHERF1 and NHERF2 and increased SR-BI mRNA expression in primary rat granulosa cells and MLTC-1 cells, whereas ACTH had no effect on NHERF1 and NHERF2 mRNA levels but decreased their protein levels in rat adrenals. Co-immunoprecipitation, colocalization, bimolecular fluorescence complementation, and mutational analysis indicated that SR-BI associates with NHERF1 and NHERF2. NHERF1 and NHERF2 down-regulated SR-BI protein expression through inhibition of its de novo synthesis. NHERF1 and NHERF2 also inhibited SR-BI-mediated selective CE transport and steroidogenesis, which were markedly attenuated by partial deletions of the PDZ1 or PDZ2 domain of NHERF1, the PDZ2 domain of NHERF2, or the MERM domains of NHERF1/2 or by gene silencing of NHERF1/2. Moreover, an intact COOH-terminal PDZ recognition motif (EAKL) in SR-BI is needed. Transient transfection of hepatic cell lines with NHERF1 or NHERF2 caused a significant reduction in endogenous protein levels of SR-BI. Collectively, these data establish NHERF1 and NHERF2 as SR-BI protein binding partners that play a negative role in the regulation of SR-BI expression, selective CE transport, and steroidogenesis.

  2. Increased DNA methylation of scavenger receptor class B type I contributes to inhibitory effects of prenatal caffeine ingestion on cholesterol uptake and steroidogenesis in fetal adrenals

    SciTech Connect

    Wu, Dong-Mei; He, Zheng; Ma, Liang-Peng; Wang, Lin-Long; Ping, Jie; Wang, Hui

    2015-06-01

    Steroid hormones synthesized from cholesterol in the fetal adrenal are crucial for fetal development. We have observed the inhibited fetal adrenal corticosterone synthesis and increased intrauterine growth retardation (IUGR) rate in rats under prenatal caffeine ingestion. The aim of this study is to evaluate the effects of prenatal caffeine ingestion on cholesterol supply in fetal adrenal steroidogenesis in rats and explore the underlying epigenetic mechanisms. Pregnant Wistar rats were treated with 60 mg/kg·d caffeine from gestational day (GD) 7 to GD17. Histological changes of fetal adrenals and increased IUGR rates were observed in the caffeine group. There were significantly decreased steroid hormone contents and cholesterol supply in caffeine-treated fetal adrenals. Data from the gene expression array suggested that prenatal caffeine ingestion caused increased expression of genes related to DNA methylation and decreased expression of genes related to cholesterol uptake. The following conjoint analysis of DNA methylation array with these differentially expressed genes suggested that scavenger receptor class B type I (SR-BI) may play an important role in caffeine-induced cholesterol supply deficiency. Moreover, real-time RT-PCR and immunohistochemical detection certified the inhibitory effects of caffeine on both mRNA expression and protein expression of SR-BI in the fetal adrenal. And the increased DNA methylation frequency in the proximal promoter of SR-BI was confirmed by bisulfite-sequencing PCR. In conclusion, prenatal caffeine ingestion can induce DNA hypermethylation of the SR-BI promoter in the rat fetal adrenal. These effects may lead to decreased SR-BI expression and cholesterol uptake, which inhibits steroidogenesis in the fetal adrenal. - Highlights: • Prenatal caffeine ingestion inhibits steroid hormone production in the fetal adrenal. • Prenatal caffeine ingestion inhibits cholesterol uptake in the fetal adrenal. • Prenatal caffeine

  3. Association of three polymorphisms of scavenger receptor class BI gene (exon8, exon1, intron5) with coronary stenosis in a coronary Tunisian population.

    PubMed

    Rejeb, Jihène; Omezzine, Asma; Boumaiza, Imen; Rebhi, Lamia; Kacem, Slim; Rejeb, Nabila Ben; Nabli, Naoufel; Abdelaziz, Ahmed Ben; Boughzala, Essia; Bouslama, Ali

    2012-12-15

    The potential role of scavenger receptor class BI (gene name SCARB1) in the regulation of lipoproteins metabolism and atherosclerosis has attracted considerable interest. We tested the relationship of SCARB1 polymorphisms with significant coronary stenosis (SCS) and lipid profile in a coronary Tunisian population. Three SCARB1 polymorphisms (exon8 (C/T), exon1 (G/A), intron5 (C/T)) were studied in 316 Tunisian patients undergoing coronary angiography. SCS was defined as a luminal narrowing of ≥ 50% in at least one major coronary artery. Lipid profile was measured. Genotyping was performed using PCR-RFLP. Individuals with TT genotypes of exon8 were associated with higher concentrations of plasma HDL-C and ApoAI in the group without SCS. Carriers of T allele of exon8 were associated with 41% lower risk of SCS. This protective effect seemed to be particularly significant in women, nondiabetics and nonsmokers. Subjects homozygous for the variant allele of intron5 were significantly associated with an increased risk of SCS, particularly in smokers. AA genotype of exon1 was associated with an increased risk of SCS in diabetics and in patients with metabolic syndrome. The (CAT) haplotype was associated with increase in the risk of SCS compared to the wild haplotype and had a 4-fold greater risk of SCS than patients with haplotype (TGC) which seems to be the most protective against SCS. Carriers of T allele of exon8 in SCARB1 seemed to increase HDL-C and ApoAI concentrations and reduce the risk of SCS. The intron5, exon1 and (CAT) haplotype seemed to have an atherogenic effect. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Skeletal manifestations of bear scavenging.

    PubMed

    Carson, E A; Stefan, V H; Powell, J F

    2000-05-01

    In many partially or fully skeletonized forensic cases, postmortem animal damage is simply attributed to rodents or carnivores; little effort is made to determine the general size or assign a genus to the scavenger. As one of the largest wild carnivores to inhabit mountainous and forested areas throughout the continental United States, Alaska, and Canada, black bears (Ursus americanus) must be considered possible suspects when skeletonized remains are located showing marks of carnivore damage. Since 1995, three cases of known bear scavenging have been referred to the Maxwell Museum's Laboratory of Human Osteology by the New Mexico Office of the Medical Investigator for skeletal analysis. These cases comprise a total of seven individuals, and all of the remains were deposited in high altitude forests of New Mexico along the western border with Arizona with a minimum of 4 months exposure before recovery. When analyzed, all cases shared a similar pattern of element survivorship and damage. We suggest that bears can be distinguished from members of the canid family, the other common scavenger of human remains, based on the representation of skeletal elements at the scene. Rates and patterns of damage are not as accurate as element recovery in the discrimination of scavenger genus. Use of this information should allow forensic anthropologists to better understand the postmortem taphonomic processes that shaped the skeletal remains, and hopefully prevent misdiagnoses of perimortem trauma on elements not typically scavenged by canids.

  5. Bombesin-like peptide receptors in human bronchial epithelial cells.

    PubMed

    Kane, M A; Toi-Scott, M; Johnson, G L; Kelley, K K; Boose, D; Escobedo-Morse, A

    1996-01-01

    Northern blot and RNAse protection assays previously failed to detect bombesin-like peptide (BLP) receptors in normal human lung tissue, but by RT/PCR cultured human bronchial epithelial (HBE) cells expressed all three BLP receptor subtypes, predominantly neuromedin B (NMB) receptor. By RT/PCR, we found expression of all three BLP receptor subtypes by human lung tissue and confirmed NMB receptor expression in six out of six HBE samples. However, transformed HBE BEAS B2B cells expressed only gastrin-releasing peptide (GRP) receptors; saturable, high-affinity (Kd = 3.5 nM) specific [125I]GRP binding confirmed functional GRP receptor, with M(r) = 75 kDa and immunologic cross-reactivity with GRP receptor from human small-cell lung carcinoma (SCLC) NCI-H345 cells. Altered regulation of BLP receptors may accompany transformation of normal lung cells to cancer.

  6. Crystal structures of the human adiponectin receptors

    PubMed Central

    Tanabe, Hiroaki; Fujii, Yoshifumi; Hosaka, Toshiaki; Motoyama, Kanna; Ikeda, Mariko; Wakiyama, Motoaki; Terada, Takaho; Ohsawa, Noboru; Hato, Masakatsu; Ogasawara, Satoshi; Hino, Tomoya; Murata, Takeshi; Iwata, So; Hirata, Kunio; Kawano, Yoshiaki; Yamamoto, Masaki; Kimura-Someya, Tomomi; Shirouzu, Mikako; Yamauchi, Toshimasa; Kadowaki, Takashi; Yokoyama, Shigeyuki

    2015-01-01

    Adiponectin stimulation of its receptors, AdipoR1 and AdipoR2, increases AMPK and PPAR activities, respectively, thereby contributing to healthy longevity as key anti-diabetic molecules. AdipoR1 and AdipoR2 were predicted to contain seven transmembrane helices with the opposite topology to G protein-coupled receptor (GPCR)s. Here we report the crystal structures of human AdipoR1 and AdipoR2 at 2.9- and 2.4-Å resolution, respectively, which represent a novel class of receptor structure. The seven-transmembrane helices, conformationally distinct from those of GPCRs, enclose a large cavity where three conserved histidine residues coordinate a zinc ion. The zinc-binding structure may play a role in the adiponectin-stimulated AMPK phosphorylation and UCP2 upregulation. Adiponectin may broadly interact with the extracellular face, rather than the C-terminal flexible tail, of the receptors. The present information will facilitate the understanding of novel structure-function relationships and the development and optimization of AdipoR agonists for the treatment of obesity-related diseases, such as type 2 diabetes. PMID:25855295

  7. Scavenging for the Past.

    ERIC Educational Resources Information Center

    McMahon, Sue; Strubbe, Mary

    1988-01-01

    Discusses the goals and planning of a scavenger hunt which was designed to increase enthusiasm in students and promote active learning. States that a scavenger hunt instills a sense of community pride in students and that the community cooperation fosters a positive relationship with the school. Provides a sample scavenger hunt checklist. (GEA)

  8. Scavenging for the Past.

    ERIC Educational Resources Information Center

    McMahon, Sue; Strubbe, Mary

    1988-01-01

    Discusses the goals and planning of a scavenger hunt which was designed to increase enthusiasm in students and promote active learning. States that a scavenger hunt instills a sense of community pride in students and that the community cooperation fosters a positive relationship with the school. Provides a sample scavenger hunt checklist. (GEA)

  9. Human blood-brain barrier insulin receptor.

    PubMed

    Pardridge, W M; Eisenberg, J; Yang, J

    1985-06-01

    A new model system for characterizing the human brain capillary, which makes up the blood-brain barrier (BBB) in vivo, is described in these studies and is applied initially to the investigation of the human BBB insulin receptor. Autopsy brains were obtained from the pathologist between 22-36 h postmortem and were used to isolate human brain microvessels which appeared intact on both light and phase microscopy. The microvessels were positive for human factor 8 and for a BBB-specific enzyme marker, gamma-glutamyl transpeptidase. The microvessels avidly bound insulin with a high-affinity dissociation constant, KD = 1.2 +/- 0.5 nM. The human brain microvessels internalized insulin based on acid-wash assay, and 75% of insulin was internalized at 37 degrees C. The microvessels transported insulin to the medium at 37 degrees C with a t1/2 = approximately 70 min. Little of the 125I-insulin was metabolized by the microvessels under these conditions based on the elution profile of the medium extract over a Sephadex G-50 column. Plasma membranes were obtained from the human brain microvessels and these membranes were enriched in membrane markers such as gamma-glutamyl transpeptidase or alkaline phosphatase. The plasma membranes bound 125I-insulin with and ED50 = 10 ng/ml, which was identical to the 50% binding point in intact microvessels. The human BBB plasma membranes were solubilized in Triton X-100 and were adsorbed to a wheat germ agglutinin Sepharose affinity column, indicating the BBB insulin receptor is a glycoprotein. Affinity cross-linking of insulin to the plasma membranes revealed a 127K protein that specifically binds insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. The effect of albumin on podocytes: The role of the fatty acid moiety and the potential role of CD36 scavenger receptor

    SciTech Connect

    Pawluczyk, I.Z.A.; Pervez, A.; Ghaderi Najafabadi, M.; Saleem, M.A.; Topham, P.S.

    2014-08-15

    Evidence is emerging that podocytes are able to endocytose proteins such as albumin using kinetics consistent with a receptor-mediated process. To date the role of the fatty acid moiety on albumin uptake kinetics has not been delineated and the receptor responsible for uptake is yet to be identified. Albumin uptake studies were carried out on cultured human podocytes exposed to FITC-labelled human serum albumin either carrying fatty acids (HSA{sub +FA}) or depleted of them (HSA{sub −FA}). Receptor-mediated endocytosis of FITC-HSA{sub +FA} over 60 min was 5 times greater than that of FITC-HSA{sub −FA}. 24 h exposure of podocytes to albumin up-regulated nephrin expression and induced the activation of caspase-3. These effects were more pronounced in response to HSA{sub −FA.} Individually, anti-CD36 antibodies had no effect upon endocytosis of FITC-HSA. However, a cocktail of 2 antibodies reduced uptake by nearly 50%. Albumin endocytosis was enhanced in the presence of the CD36 specific inhibitor sulfo-N-succinimidyl oleate (SSO) while knock-down of CD36 using CD36siRNA had no effect on uptake. These data suggest that receptor-mediated endocytosis of albumin by podocytes is regulated by the fatty acid moiety, although, some of the detrimental effects are induced independently of it. CD36 does not play a direct role in the uptake of albumin. - Highlights: • The fatty acid moiety is essential for receptor mediated endocytosis of albumin. • Fatty acid depleted albumin is more pathogenic to podocytes. • CD36 is not directly involved in albumin uptake by podocytes.

  11. Dopamine receptors in human gastrointestinal mucosa

    SciTech Connect

    Hernandez, D.E.; Mason, G.A.; Walker, C.H.; Valenzuela, J.E.

    1987-12-21

    Dopamine is a putative enteric neurotransmitter that has been implicated in exocrine secretory and motility functions of the gastrointestinal tract of several mammalian species including man. This study was designed to determine the presence of dopamine binding sites in human gastric and duodenal mucosa and to describe certain biochemical characteristics of these enteric receptor sites. The binding assay was performed in triplicate with tissue homogenates obtained from healthy volunteers of both sexes using /sup 3/H-dopamine as a ligand. The extent of nonspecific binding was determined in the presence of a 100-fold excess of unlabeled dopamine. Scatchard analysis performed with increasing concentrations of /sup 3/H-dopamine (20-500 nM) revealed a single class of saturable dopamine binding sites in gastric and duodenal mucosa. The results of this report demonstrate the presence of specific dopamine receptors in human gastric and duodenal mucosa. These biochemical data suggest that molecular abnormalities of these receptor sites may be operative in the pathogenesis of important gastrointestinal disorders. 33 references, 2 figures.

  12. Human specific loss of olfactory receptor genes

    PubMed Central

    Gilad, Yoav; Man, Orna; Pääbo, Svante; Lancet, Doron

    2003-01-01

    Olfactory receptor (OR) genes constitute the basis for the sense of smell and are encoded by the largest mammalian gene superfamily of >1,000 genes. In humans, >60% of these are pseudogenes. In contrast, the mouse OR repertoire, although of roughly equal size, contains only ≈20% pseudogenes. We asked whether the high fraction of nonfunctional OR genes is specific to humans or is a common feature of all primates. To this end, we have compared the sequences of 50 human OR coding regions, regardless of their functional annotations, to those of their putative orthologs in chimpanzees, gorillas, orangutans, and rhesus macaques. We found that humans have accumulated mutations that disrupt OR coding regions roughly 4-fold faster than any other species sampled. As a consequence, the fraction of OR pseudogenes in humans is almost twice as high as in the non-human primates, suggesting a human-specific process of OR gene disruption, likely due to a reduced chemosensory dependence relative to apes. PMID:12612342

  13. Novel mechanisms for superoxide-scavenging activity of human manganese superoxide dismutase determined by the K68 key acetylation site.

    PubMed

    Lu, Jiaqi; Cheng, Kuoyuan; Zhang, Bo; Xu, Huan; Cao, Yuanzhao; Guo, Fei; Feng, Xudong; Xia, Qing

    2015-08-01

    Superoxide is the primary reactive oxygen species generated in the mitochondria. Manganese superoxide dismutase (SOD2) is the major enzymatic superoxide scavenger present in the mitochondrial matrix and one of the most crucial reactive oxygen species-scavenging enzymes in the cell. SOD2 is activated by sirtuin 3 (SIRT3) through NAD(+)-dependent deacetylation. However, the exact acetylation sites of SOD2 are ambiguous and the mechanisms underlying the deacetylation-mediated SOD2 activation largely remain unknown. We are the first to characterize SOD2 mutants of the acetylation sites by investigating the relative enzymatic activity, structures, and electrostatic potential of SOD2 in this study. These SOD2 mutations affected the superoxide-scavenging activity in vitro and in HEK293T cells. The lysine 68 (K68) site is the most important acetylation site contributing to SOD2 activation and plays a role in cell survival after paraquat treatment. The molecular basis underlying the regulation of SOD2 activity by K68 was investigated in detail. Molecular dynamics simulations revealed that K68 mutations induced a conformational shift of residues located in the active center of SOD2 and altered the charge distribution on the SOD2 surface. Thus, the entry of the superoxide anion into the coordinated core of SOD2 was inhibited. Our results provide a novel mechanistic insight, whereby SOD2 acetylation affects the structure and charge distribution of SOD2, its tetramerization, and p53-SOD2 interactions of SOD2 in the mitochondria, which may play a role in nuclear-mitochondrial communication during aging.

  14. 21 CFR 868.5590 - Scavenging mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Scavenging mask. 868.5590 Section 868.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5590 Scavenging mask. (a) Identification....

  15. 21 CFR 868.5590 - Scavenging mask.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Scavenging mask. 868.5590 Section 868.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5590 Scavenging mask. (a) Identification. A...

  16. Receptors for human γG Globulin on human neutrophils

    PubMed Central

    Messner, R. P.; Jelinek, J.

    1970-01-01

    Cell surface receptors for human γG antibodies directed against bacterial antigens were demonstrated on human neutrophils using an in vitro bacteriocidal-phagocytic assay. These results were confirmed by adherence of sensitized erythrocytes to monolayers of neutrophils or monocytes. Erythrocytes sensitized indirectly with antibacterial γG antibodies after passive sensitization with bacterial antigens adhered to both neutrophils and monocytes. Erythrocytes sensitized directly with conventional anti-D γG antibodies adhered only to monocytes, while those sensitized with the hyperimmune anti-CD γG antibody Ripley adhered to both monocytes and neutrophils. Adherence of anti-Rh or antibacterial γG antibodies to monocytes and neutrophils could be inhibited by whole γG, myeloma globulins of the γ1 or γ3 subclasses, or Fc fragments, but not by Fab fragment. These results indicate that receptors for the Fc portion of human γG antibodies exist on both neutrophils and monocytes, and that γG antibodies differ in their ability to attach to these two cell types. Differences in the behavior of the γG antibodies studied may be related to differences in the density of antibodies on the erythrocyte surface and receptors on the phagocytic cells. Images PMID:4991439

  17. NOD-like receptors and human diseases.

    PubMed

    Rosenstiel, Philip; Till, Andreas; Schreiber, Stefan

    2007-04-01

    NOD-like receptors are cytosolic proteins that contain a central nucleotide-binding oligomerization domain (NACHT), an N-terminal effector-binding domain and C-terminal leucine-rich repeats (LRRs). NOD-like receptors have been implicated as ancient cellular sentinels mediating protective immune responses against intracellular pathogens. Recent studies have described the genetic association of polymorphisms in NOD-like receptor genes with complex chronic inflammatory barrier diseases, such as Crohn's disease and asthma and with rare auto-inflammatory syndromes including familial cold urticaria, Muckle-Wells syndrome and Blau syndrome. Whereas genetic variability in NLRs may have been an important element to provide plasticity to antigen recognition and host defense in the past, recent changes in the lifestyle of industrialized societies (e.g. hygiene ("cold-chain-hypothesis"), nutrition, or antibiotics) may have turned ancient genetic variability into disease-causing mutations. The review focuses on NLR function in the molecular pathophysiology of human inflammatory disorders.

  18. Gene Transfer and Molecular Cloning of the Human NGF Receptor

    NASA Astrophysics Data System (ADS)

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

    1986-04-01

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

  19. Phosphatidylinositol 3-kinase, phosphoinositide-specific phospholipase-Cgamma and protein kinase-C signal myelin phagocytosis mediated by complement receptor-3 alone and combined with scavenger receptor-AI/II in macrophages.

    PubMed

    Makranz, Chen; Cohen, Goni; Baron, Ayellet; Levidor, Lital; Kodama, Tatsuhiko; Reichert, Fanny; Rotshenker, Shlomo

    2004-03-01

    Complement-receptor-3 (CR3/MAC-1), scavenger-receptor-AI/II (SRAI/II) and Fcgamma-receptor (FcgammaR) can mediate phagocytosis of degenerated myelin in macrophages and microglia. However, CR3/MAC-1 and SRAI/II, but not FcgammaR, mediate phagocytosis after axonal injury. We tested for phosphatidylinositol 3-kinase (PI3K), phosphoinositide-specific phospholipase-Cgamma (PLCgamma) and protein kinase-C (PKC) signaling in myelin phagocytosis mediated by CR3/MAC-1 alone and by CR3/MAC-1 combined with SRAI/II. Phagocytosis was inhibited by PI3K inhibitors wortmannin and LY-294002, PLCgamma inhibitor U-73122, classical PKC (cPKC) inhibitor Go-6976, general PKC inhibitors Ro-318220 and calphostin-C, and BAPTA/AM which chelates intracellular Ca(2+) required for cPKC activation. PKC activator PMA augmented phagocytosis and further alleviated inhibitions induced by PI3K and PLCgamma inhibitors. Overall, altering PKC activity modulated phagocytosis 4- to 6-fold between inhibition and augmentation. PLCgamma activation did not require tyrosine phosphorylation. Thus, signaling of myelin phagocytosis mediated by CR3/MAC-1 alone and by CR3/MAC-1 combined with SRAI/II involves PI3K, PLCgamma and cPKC, the cascade PI3K-->PLCgamma-->cPKC, and wide-range modulation by PKC. This pathway may thus be targeted for in vivo modulation, which may explain differences in the efficiency of CR3/MAC-1-mediated myelin phagocytosis in different pathological conditions.

  20. DNA damage protecting and free radical scavenging properties of mycosporine-2-glycine from the Dead Sea cyanobacterium in A375 human melanoma cell lines.

    PubMed

    Cheewinthamrongrod, Vipaporn; Kageyama, Hakuto; Palaga, Tanapat; Takabe, Teruhiro; Waditee-Sirisattha, Rungaroon

    2016-11-01

    Mycosporine-like amino acids (MAAs) are a group of natural sunscreen compounds that possess highly photoprotective properties. The most commonly found MAAs in marine organisms is shinorine, porphyra-334, and mycosporine-glycine. However, the halophilic species accumulate mycosporine-2-glycine (M2G) as the major MAA. In this study, we have investigated the protective effect of M2G against oxidative stress. In vitro radical scavenging activity revealed that M2G exhibited a significant inhibition with scavenging concentration (SC) 50 value of 22±1.4μM. In vivo analysis using the human melanoma A375 and a control cell line (NHSF) showed that M2G at low concentration (i.e. micromolar range) protected the cells against the oxidative stress (H2O2)-induced cell death. Comet assay to assess total DNA strand breaks demonstrated that M2G was not genotoxic and protected against the DNA damage by H2O2 treatment at the same level as ascorbic acid. To our knowledge, this is the first evidence demonstrating potential protective role of the natural sunscreen compound M2G against oxidative stress-induced DNA damage in human cell lines. The potent antioxidant activity combined with DNA protection ability of M2G may support its endorsement as a potential natural sunscreen with antioxidant property. These findings provide important clues for possible use of M2G in pharmaceutical and biotechnological applications.

  1. Down-regulation of intestinal scavenger receptor class B, type I (SR-BI) expression in rodents under conditions of deficient bile delivery to the intestine.

    PubMed Central

    Voshol, P J; Schwarz, M; Rigotti, A; Krieger, M; Groen, A K; Kuipers, F

    2001-01-01

    Scavenger receptor class B, type I (SR-BI) is expressed in the intestines of rodents and has been suggested to be involved in the absorption of dietary cholesterol. The aim of this study was to determine whether intestinal SR-BI expression is affected in animal models with altered bile delivery to the intestine and impaired cholesterol absorption. SR-BI protein and mRNA levels were determined in proximal and distal small intestine from control, bile-duct-ligated and bile-diverted rats and from control and bile-duct-ligated mice. Two genetically altered mouse models were studied: multidrug resistance-2 P-glycoprotein-deficient [Mdr2((-/-))] mice that produce phospholipid/cholesterol-free bile, and cholesterol 7alpha-hydroxylase-deficient [Cyp7a((-/-))] mice, which exhibit qualitative and quantitative changes in the bile-salt pool. Cholesterol-absorption efficiency was quantified using a dual-isotope ratio method. SR-BI was present at the apical membrane of enterocytes in control rats and mice and was more abundant in proximal than in distal segments of the intestine. In bile-duct-ligated animals, levels of SR-BI protein were virtually absent and mRNA levels were decreased by approximately 50%. Bile-diverted rats, Mdr2((-/-)) mice and Cyp7a((-/-)) mice showed decreased levels of intestinal SR-BI protein while mRNA levels were unaffected. Cholesterol absorption was reduced by >90% in bile-duct-ligated and bile-diverted animals and in Cyp7a((-/-)) mice, whereas Mdr2((-/-)) mice showed an approximately 50% reduction. This study shows that SR-BI is expressed at the apical membrane of enterocytes of rats and mice, mainly in the upper intestine where cholesterol absorption is greatest, and indicates that bile components play a role in post-transcriptional regulation of SR-BI expression. Factors associated with cholestasis appear to be involved in transcriptional control of intestinal SR-BI expression. The role of SR-BI in the cholesterol-absorption process remains to be

  2. Enhanced expression of hemoglobin scavenger receptor CD163 in accumulated macrophages within filtered debris between acute coronary syndromes and stable angina pectoris.

    PubMed

    Sato, Takao; Kameyama, Tomoki; Noto, Takahisa; Ueno, Hiroshi; Inoue, Hiroshi

    2015-01-01

    Coronary intraplaque hemorrhage up-regulates hemoglobin scavenger receptor CD163 expression on macrophages, and has an association with vulnerable plaque development. During percutaneous coronary intervention, mechanical plaque disruption exposes potentially embolic atheromatous contents from culprit plaque.In 37 patients with stable angina pectoris (SAP, n = 20) or acute coronary syndrome (ACS, n = 17), atherothrombotic debris was collected using a filter-based distal embolic protection device. We immunohistochemically determined CD14-positive macrophages and CD163-positive macrophages in filtered debris. We also examined the relation of CD14- and CD163-positive macrophages with culprit plaque volume and components evaluated with ultrasonic tissue characterization (VH-IVUS).The only significant difference in clinical characteristics between the two groups was in hs-CRP. In ACS, the percentage of CD14- and CD163-positive macrophages to the whole cells (%CD14 and %CD163, respectively) was significantly higher than that in SAP (20.1 ± 8.2 versus 8.8 ± 6.8%, P < 0.001 and 32.6 ± 18.9 versus 9.0 ± 3.8%, P < 0.001, respectively). In IVUS indices of culprit plaque, the remodeling index was significantly higher in ACS than in SAP. However, necrotic core component (%NC) in ACS was significantly higher than that in SAP. Furthermore, fibrotic component (%Fibrous) in ACS was significantly lower than that in SAP (56.1 ± 4.7 versus 60.1 ± 3.3%, P = 0.03). %CD14 and %CD163 had a significant positive correlation with %NC (%CD14: r = 0.40, P = 0.01 and %CD163: r = 0.45, P = 0.01), but only %CD163 was negatively correlated with %Fibrous (%CD163: r = -0.48, P = 0.01).These findings suggest that the presence of CD14- and CD163-positive macrophages may reflect plaque inflammation, NC expansion, and plaque vulnerability in patients with coronary heart disease.

  3. Bitter taste receptor polymorphisms and human aging.

    PubMed

    Campa, Daniele; De Rango, Francesco; Carrai, Maura; Crocco, Paolina; Montesanto, Alberto; Canzian, Federico; Rose, Giuseppina; Rizzato, Cosmeri; Passarino, Giuseppe; Barale, Roberto

    2012-01-01

    Several studies have shown that genetic factors account for 25% of the variation in human life span. On the basis of published molecular, genetic and epidemiological data, we hypothesized that genetic polymorphisms of taste receptors, which modulate food preferences but are also expressed in a number of organs and regulate food absorption processing and metabolism, could modulate the aging process. Using a tagging approach, we investigated the possible associations between longevity and the common genetic variation at the three bitter taste receptor gene clusters on chromosomes 5, 7 and 12 in a population of 941 individuals ranging in age from 20 to 106 years from the South of Italy. We found that one polymorphism, rs978739, situated 212 bp upstream of the TAS2R16 gene, shows a statistically significant association (p = 0.001) with longevity. In particular, the frequency of A/A homozygotes increases gradually from 35% in subjects aged 20 to 70 up to 55% in centenarians. These data provide suggestive evidence on the possible correlation between human longevity and taste genetics.

  4. Laminin receptor on human breast carcinoma cells.

    PubMed Central

    Terranova, V P; Rao, C N; Kalebic, T; Margulies, I M; Liotta, L A

    1983-01-01

    Human MCF-7 breast carcinoma cells possess a receptor-like moiety on their surface that has a high binding affinity (Kd = 2 nM) for laminin, a glycoprotein localized in basement membranes. Laminin preferentially stimulates (8-fold) MCF-7 cells to attach to type IV (basement membrane) collagen, whereas fibronectin stimulates attachment only 2-fold for these cells on type I collagen. The attachment properties of two other human breast carcinoma cell lines to type IV collagen were also studied. The attachment of ZR-75-1 cells was stimulated 4-fold by laminin and 5-fold by fibronectin, whereas T47-D cell attachment was stimulated 2-fold by laminin and 7-fold by fibronectin. By employing protease-derived fragments of laminin, the major domains of the laminin molecule that participate in MCF-7 cell attachment to type IV collagen were identified. The whole laminin molecule has the configuration of a four-armed cross with three short arms and one long arm. A major cell-binding domain was found to reside near the intersection point of the short arms, and the type IV collagen-binding domain was associated with the globular end regions of the short arms. The receptor for laminin on the surface of these tumor cells may be involved in the initial interaction of tumor cells via laminin with the vascular basement membrane to facilitate invasion and subsequent promotion of metastasis. Images PMID:6300843

  5. Bitter Taste Receptor Polymorphisms and Human Aging

    PubMed Central

    Carrai, Maura; Crocco, Paolina; Montesanto, Alberto; Canzian, Federico; Rose, Giuseppina; Rizzato, Cosmeri

    2012-01-01

    Several studies have shown that genetic factors account for 25% of the variation in human life span. On the basis of published molecular, genetic and epidemiological data, we hypothesized that genetic polymorphisms of taste receptors, which modulate food preferences but are also expressed in a number of organs and regulate food absorption processing and metabolism, could modulate the aging process. Using a tagging approach, we investigated the possible associations between longevity and the common genetic variation at the three bitter taste receptor gene clusters on chromosomes 5, 7 and 12 in a population of 941 individuals ranging in age from 20 to 106 years from the South of Italy. We found that one polymorphism, rs978739, situated 212 bp upstream of the TAS2R16 gene, shows a statistically significant association (p = 0.001) with longevity. In particular, the frequency of A/A homozygotes increases gradually from 35% in subjects aged 20 to 70 up to 55% in centenarians. These data provide suggestive evidence on the possible correlation between human longevity and taste genetics. PMID:23133589

  6. Human native kappa opioid receptor functions not predicted by recombinant receptors: Implications for drug design

    PubMed Central

    Broad, John; Maurel, Damien; Kung, Victor W. S.; Hicks, Gareth A.; Schemann, Michael; Barnes, Michael R.; Kenakin, Terrence P.; Granier, Sébastien; Sanger, Gareth J.

    2016-01-01

    If activation of recombinant G protein-coupled receptors in host cells (by drugs or other ligands) has predictive value, similar data must be obtained with native receptors naturally expressed in tissues. Using mouse and human recombinant κ opioid receptors transfected into a host cell, two selectively-acting compounds (ICI204448, asimadoline) equi-effectively activated both receptors, assessed by measuring two different cell signalling pathways which were equally affected without evidence of bias. In mouse intestine, naturally expressing κ receptors within its nervous system, both compounds also equi-effectively activated the receptor, inhibiting nerve-mediated muscle contraction. However, whereas ICI204448 acted similarly in human intestine, where κ receptors are again expressed within its nervous system, asimadoline was inhibitory only at very high concentrations; instead, low concentrations of asimadoline reduced the activity of ICI204448. This demonstration of species-dependence in activation of native, not recombinant κ receptors may be explained by different mouse/human receptor structures affecting receptor expression and/or interactions with intracellular signalling pathways in native environments, to reveal differences in intrinsic efficacy between receptor agonists. These results have profound implications in drug design for κ and perhaps other receptors, in terms of recombinant-to-native receptor translation, species-dependency and possibly, a need to use human, therapeutically-relevant, not surrogate tissues. PMID:27492592

  7. Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells

    PubMed Central

    Shin, Hee Soon; Satsu, Hideo; Bae, Min-Jung; Totsuka, Mamoru; Shimizu, Makoto

    2017-01-01

    Chlorogenic acid (CHA) and caffeic acid (CA) are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL)-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H2O2)-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK). Additionally, upstream of IKK, protein kinase D (PKD) was also suppressed. Finally, we found that they scavenged H2O2-induced reactive oxygen species (ROS) and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H2O2-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells. PMID:28230729

  8. Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells.

    PubMed

    Shin, Hee Soon; Satsu, Hideo; Bae, Min-Jung; Totsuka, Mamoru; Shimizu, Makoto

    2017-02-20

    Chlorogenic acid (CHA) and caffeic acid (CA) are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL)-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H₂O₂)-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK). Additionally, upstream of IKK, protein kinase D (PKD) was also suppressed. Finally, we found that they scavenged H₂O₂-induced reactive oxygen species (ROS) and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H₂O₂-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells.

  9. Noncanonical Role of the PDZ4 Domain of the Adaptor Protein PDZK1 in the Regulation of the Hepatic High Density Lipoprotein Receptor Scavenger Receptor Class B, Type I (SR-BI)*

    PubMed Central

    Tsukamoto, Kosuke; Wales, Thomas E.; Daniels, Kathleen; Pal, Rinku; Sheng, Ren; Cho, Wonhwa; Stafford, Walter; Engen, John R.; Krieger, Monty; Kocher, Olivier

    2013-01-01

    The four PDZ (PDZ1 to PDZ4) domain-containing adaptor protein PDZK1 controls the expression, localization, and function of the HDL receptor scavenger receptor class B, type I (SR-BI), in hepatocytes in vivo. This control depends on both the PDZ4 domain and the binding of SR-BI's cytoplasmic C terminus to the canonical peptide-binding sites of either the PDZ1 or PDZ3 domain (no binding to PDZ2 or PDZ4). Using transgenic mice expressing in the liver domain deletion (ΔPDZ2 or ΔPDZ3), domain replacement (PDZ2→1), or target peptide binding-negative (PDZ4(G389P)) mutants of PDZK1, we found that neither PDZ2 nor PDZ3 nor the canonical target peptide binding activity of PDZ4 were necessary for hepatic SR-BI regulatory activity. Immunohistochemical studies established that the localization of PDZK1 on hepatocyte cell surface membranes in vivo is dependent on its PDZ4 domain and the presence of SR-BI. Analytical ultracentrifugation and hydrogen deuterium exchange mass spectrometry suggested that the requirement of PDZ4 for localization and SR-BI regulation is not due to PDZ4-mediated oligomerization or induction of conformational changes in the PDZ123 portion of PDZK1. However, surface plasmon resonance analysis showed that PDZ4, but not the other PDZ domains, can bind vesicles that mimic the plasma membrane. Thus, PDZ4 may potentiate PDZK1's regulation of SR-BI by promoting its lipid-mediated attachment to the cytoplasmic membrane. Our results show that not all of the PDZ domains of a multi-PDZ domain-containing adaptor protein are required for its biological activities and that both canonical target peptide binding and noncanonical (peptide binding-independent) capacities of PDZ domains may be employed by a single such adaptor for optimal in vivo activity. PMID:23720744

  10. Hypervariable Region 1 Deletion and Required Adaptive Envelope Mutations Confer Decreased Dependency on Scavenger Receptor Class B Type I and Low-Density Lipoprotein Receptor for Hepatitis C Virus

    PubMed Central

    Prentoe, Jannick; Serre, Stéphanie B. N.; Ramirez, Santseharay; Nicosia, Alfredo; Gottwein, Judith M.

    2014-01-01

    Hypervariable region 1 (HVR1) of envelope protein 2 (E2) of hepatitis C virus (HCV) serves important yet undefined roles in the viral life cycle. We previously showed that the viability of HVR1-deleted JFH1-based recombinants with Core-NS2 of H77 (H77ΔHVR1, genotype 1a) and S52 (S52ΔHVR1, genotype 3a) in Huh7.5 cells was rescued by E2 substitutions N476D/S733F and an E1 substitution, A369V, respectively; HVR1-deleted J6 (J6ΔHVR1, genotype 2a) was fully viable. In single-cycle production assays, where HCV RNA was transfected into entry-deficient Huh7-derived S29 cells with low CD81 expression, we found no effect of HVR1 deletion on replication or particle release for H77 and S52. HCV pseudoparticle assays in Huh7.5 cells showed that HVR1 deletion decreased entry by 20- to 100-fold for H77, J6, and S52; N476D/S733F restored entry for H77ΔHVR1, while A369V further impaired S52ΔHVR1 entry. We investigated receptor usage by antibody blocking and receptor silencing in Huh7.5 cells, followed by inoculation of parental and HVR1-deleted HCV recombinants. Compared to parental viruses, scavenger receptor class B type I (SR-BI) dependency was decreased for H77ΔHVR1/N476D/S733F, H77N476D/S733F, S52ΔHVR1/A369V, and S52A369V, but not for J6ΔHVR1. Low-density lipoprotein receptor (LDLr) dependency was decreased for HVR1-deleted viruses, but not for H77N476D/S733F and S52A369V. Soluble LDLr neutralization revealed strong inhibition of parental HCV but limited effect against HVR1-deleted viruses. Apolipoprotein E (ApoE)-specific HCV neutralization was similar for H77, J6, and S52 viruses with and without HVR1. In conclusion, HVR1 and HVR1-related adaptive envelope mutations appeared to be involved in LDLr and SR-BI dependency, respectively. Also, LDLr served ApoE-independent but HVR1-dependent functions in HCV entry. PMID:24257605

  11. Replacement of Porcine CD163 Scavenger Receptor Cysteine-Rich Domain 5 with a CD163-Like Homolog Confers Resistance of Pigs to Genotype 1 but Not Genotype 2 Porcine Reproductive and Respiratory Syndrome Virus.

    PubMed

    Wells, Kevin D; Bardot, Rachel; Whitworth, Kristin M; Trible, Benjamin R; Fang, Ying; Mileham, Alan; Kerrigan, Maureen A; Samuel, Melissa S; Prather, Randall S; Rowland, Raymond R R

    2017-01-15

    CD163 knockout (KO) pigs are resistant to infection with genotype 2 (type 2) porcine reproductive and respiratory syndrome virus (PRRSV). Furthermore, the substitution of CD163 scavenger receptor cysteine-rich (SRCR) domain 5 with a homolog of human CD163-like (hCD163L1) SRCR 8 domain confers resistance of transfected HEK cells to type 1 PRRSV. As a means to understand the role of domain 5 in PRRSV infection with both type 1 and type 2 viruses, pigs were genetically modified (GM) to possess one of the following genotypes: complete knockout (KO) of CD163, deletions within SRCR domain 5, or replacement (domain swap) of SRCR domain 5 with a synthesized exon encoding a homolog of hCD163L1 SRCR domain 8. Immunophenotyping of porcine alveolar macrophages (PAMs) showed that pigs with the KO or SRCR domain 5 deletion did not express CD163. When placed in culture, PAMs from pigs with the CD163 KO phenotype were completely resistant to a panel consisting of six type 1 and nine type 2 isolates. PAMs from pigs that possessed the hCD163L1 domain 8 homolog expressed CD163 and supported the replication of all type 2 isolates, but no type 1 viruses. Infection of CD163-modified pigs with representative type 1 and type 2 viruses confirmed the in vitro results. The results confirm that CD163 is the likely receptor for all PRRS viruses. Even though type 1 and type 2 viruses are considered phenotypically similar at several levels, there is a distinct difference between the viral genotypes in the recognition of CD163. Genetic modification of the CD163 gene creates the opportunity to develop production animals that are resistant to PRRS, the costliest viral disease to ever face the swine industry. The results create further opportunities to develop refinements in the modification of CD163 with the goal of making pigs refractory to infection while retaining important CD163 functions. Copyright © 2017 American Society for Microbiology.

  12. Replacement of Porcine CD163 Scavenger Receptor Cysteine-Rich Domain 5 with a CD163-Like Homolog Confers Resistance of Pigs to Genotype 1 but Not Genotype 2 Porcine Reproductive and Respiratory Syndrome Virus

    PubMed Central

    Wells, Kevin D.; Bardot, Rachel; Whitworth, Kristin M.; Trible, Benjamin R.; Fang, Ying; Mileham, Alan; Kerrigan, Maureen A.; Samuel, Melissa S.; Prather, Randall S.

    2016-01-01

    ABSTRACT CD163 knockout (KO) pigs are resistant to infection with genotype 2 (type 2) porcine reproductive and respiratory syndrome virus (PRRSV). Furthermore, the substitution of CD163 scavenger receptor cysteine-rich (SRCR) domain 5 with a homolog of human CD163-like (hCD163L1) SRCR 8 domain confers resistance of transfected HEK cells to type 1 PRRSV. As a means to understand the role of domain 5 in PRRSV infection with both type 1 and type 2 viruses, pigs were genetically modified (GM) to possess one of the following genotypes: complete knockout (KO) of CD163, deletions within SRCR domain 5, or replacement (domain swap) of SRCR domain 5 with a synthesized exon encoding a homolog of hCD163L1 SRCR domain 8. Immunophenotyping of porcine alveolar macrophages (PAMs) showed that pigs with the KO or SRCR domain 5 deletion did not express CD163. When placed in culture, PAMs from pigs with the CD163 KO phenotype were completely resistant to a panel consisting of six type 1 and nine type 2 isolates. PAMs from pigs that possessed the hCD163L1 domain 8 homolog expressed CD163 and supported the replication of all type 2 isolates, but no type 1 viruses. Infection of CD163-modified pigs with representative type 1 and type 2 viruses confirmed the in vitro results. The results confirm that CD163 is the likely receptor for all PRRS viruses. Even though type 1 and type 2 viruses are considered phenotypically similar at several levels, there is a distinct difference between the viral genotypes in the recognition of CD163. IMPORTANCE Genetic modification of the CD163 gene creates the opportunity to develop production animals that are resistant to PRRS, the costliest viral disease to ever face the swine industry. The results create further opportunities to develop refinements in the modification of CD163 with the goal of making pigs refractory to infection while retaining important CD163 functions. PMID:27847356

  13. Botanical Scavenger Hunt

    ERIC Educational Resources Information Center

    Walker-Livingston, Wendy

    2009-01-01

    Why not combine the use of technology with the excitement of a scavenger hunt that moves middle-level students out into the "wilds" of their school campus to classify plants? In the lesson plan described here, students embark on a botanical scavenger hunt and then document their findings using a digital camera. This project was designed to allow…

  14. Botanical Scavenger Hunt

    ERIC Educational Resources Information Center

    Walker-Livingston, Wendy

    2009-01-01

    Why not combine the use of technology with the excitement of a scavenger hunt that moves middle-level students out into the "wilds" of their school campus to classify plants? In the lesson plan described here, students embark on a botanical scavenger hunt and then document their findings using a digital camera. This project was designed to allow…

  15. REACTOR FUEL SCAVENGING MEANS

    DOEpatents

    Coffinberry, A.S.

    1962-04-10

    A process for removing fission products from reactor liquid fuel without interfering with the reactor's normal operation or causing a significant change in its fuel composition is described. The process consists of mixing a liquid scavenger alloy composed of about 44 at.% plutoniunm, 33 at.% lanthanum, and 23 at.% nickel or cobalt with a plutonium alloy reactor fuel containing about 3 at.% lanthanum; removing a portion of the fuel and scavenger alloy from the reactor core and replacing it with an equal amount of the fresh scavenger alloy; transferring the portion to a quiescent zone where the scavenger and the plutonium fuel form two distinct liquid layers with the fission products being dissolved in the lanthanum-rich scavenger layer; and the clean plutonium-rich fuel layer being returned to the reactor core. (AEC)

  16. Arbutin, an intracellular hydroxyl radical scavenger, protects radiation-induced apoptosis in human lymphoma U937 cells.

    PubMed

    Wu, Li-Hua; Li, Peng; Zhao, Qing-Li; Piao, Jin-Lan; Jiao, Yu-Fei; Kadowaki, Makoto; Kondo, Takashi

    2014-11-01

    Ionizing radiation (IR) can generate reactive oxygen species (ROS). Excessive ROS have the potential to damage cellular macromolecules including DNA, proteins, and lipids and eventually lead to cell death. In this study, we evaluated the potential of arbutin, a drug chosen from a series of traditional herbal medicine by measuring intracellular hydroxyl radical scavenging ability in X-irradiated U937 cells. Arbutin (hydroquinone-β-D-glucopyranoside), a naturally occurring glucoside of hydroquinone, has been traditionally used to treat pigmentary disorders. However, there are no reports describing the effect of arbutin on IR-induced apoptosis. We confirmed that arbutin can protect cells from apoptosis induced by X-irradiation. The combination of arbutin and X-irradiation could reduce intracellular hydroxyl radical production and prevent mitochondrial membrane potential loss. It also could down-regulate the expression of phospho-JNK, phospho-p38 in whole cell lysate and activate Bax in mitochondria. Arbutin also inhibits cytochrome C release from mitochondria to cytosol. To verify the role of JNK in X-irradiation-induced apoptosis, the cells were pretreated with a JNK inhibitor, and found that JNK inhibitor could reduce apoptosis induced by X-irradiation. Taken together, our data indicate that arbutin plays an anti-apoptotic role via decreasing intracellular hydroxyl radical production, inhibition of Bax-mitochondria pathway and activation of the JNK/p38 MAPK pathway.

  17. Expression of prostacyclin receptor in human megakaryocytes.

    PubMed

    Sasaki, Y; Takahashi, T; Tanaka, I; Nakamura, K; Okuno, Y; Nakagawa, O; Narumiya, S; Nakao, K

    1997-08-01

    Prostacyclin (prostaglandin I2, PGI2) is a potent vasodilator and inhibitor of platelet aggregation. Although it is well known that the specific receptor for prostacyclin (PGI2-R) is abundantly expressed on platelets, PGI2-R expression in megakaryocytes is poorly understood. In this study, we examined its expression in leukemic or normal megakaryocytes. PGI2-R mRNA was expressed in human leukemic cell lines of megakaryocytic nature as evaluated by Northern blot analysis. Phorbol 12-myristate 13-acetate (PMA), interleukin-1 (IL-1), IL-3, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), thrombopoietin (TPO), and tumor necrosis factor-alpha (TNF-alpha) enhanced PGI2-R mRNA expression. The enhancement of PGI2-R expression by PMA and TPO was associated with the upregulation of platelet factor 4 or glycoprotein IIb mRNA expression. Iloprost, an agonist of prostacyclin, induced significant cyclic (c)AMP synthesis in these leukemic cells indicating that interaction of PGI2-R and its ligand can induce postreceptor signal transduction. Furthermore, iloprost-induced cAMP synthesis was enhanced by the pretreatment with PMA or the cytokines that promoted PGI2-R expression. PMA and TPO also increased the specific binding of [3H]iloprost to these cells. Pooled normal megakaryocytic colonies from TPO-containing semisolid culture of purified human CD34+ cells expressed PGI2-R, which were increased as the megakaryocytes matured with the peak expression before proplatelet formation, as evaluated by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). These results indicate that PGI2-R is expressed in human megakaryocytes and is upregulated by cytokines involved in thrombopoiesis or inflammation. Also, it was indicated that megakaryocytic maturation accompanies enhancement of PGI2-R expression.

  18. Characterization of functional urotensin II receptors in human skeletal muscle myoblasts: comparison with angiotensin II receptors.

    PubMed

    Qi, Jian-shen; Minor, Lisa K; Smith, Charles; Hu, Bing; Yang, Jing; Andrade-Gordon, Patricia; Damiano, Bruce

    2005-04-01

    The properties of urotensin II (U-II) receptor (UT receptor) and angiotensin II (ANG II) receptor (AT receptor) in primary human skeletal myoblasts (HSMM) and differentiated skeletal myotubes (HSMMT) were characterized. Radiolabeled U-II and ANG II bound specifically to HSMM with Kd's of 0.31 nM (2311 receptors/cell) and 0.61 nM (18,257 receptors/cell), respectively. The cyclic segment of U-II peptide, CFWKYC, was the minimal sequence required for binding, with the WKY residues essential. Inhibitor studies suggested AT1 is the predominant ANG II receptor. After radioligand binding, under conditions designed to minimize receptor internalization, half the bound U-II was resistant to acid washing suggesting that U-II binds tightly to its receptor in a quasi-irreversible fashion. The AT1 receptor-bound radioligand was completely removed under the same conditions. RT-PCR detected the expression of mRNAs for UT and AT1 receptors. Western blotting showed that U-II and ANG II signaled via ERK1/2 kinase. UT receptor was not lost upon differentiation into myotubes since both mRNA for UT receptor and U-II binding were still present. ANG II receptors were also present as shown by ANG II-induced calcium mobilization.

  19. Induction of nerve growth factor receptors on cultured human melanocytes

    SciTech Connect

    Peacocke, M.; Yaar, M.; Mansur, C.P.; Chao, M.V.; Gilchrest, B.A. )

    1988-07-01

    Normal differentiation and malignant transformation of human melanocytes involve a complex series of interactions during which both genetic and environmental factors play roles. At present, the regulation of these processes is poorly understood. The authors have induced the expression of nerve growth factor (NGF) receptors on cultured human melanocytes with phorbol 12-tetradecanoate 13-acetate and have correlated this event with the appearance of a more differentiated, dendritic morphology. Criteria for NGF receptor expression included protein accumulation and cell-surface immunofluorescent staining with a monoclonal antibody directed against the human receptor and induction of the messenger RNA species as determined by blot-hybridization studies. The presence of the receptor could also be induced by UV irradiation or growth factor deprivation. The NGF receptor is inducible in cultured human melanocytes, and they suggest that NGF may modulate the behavior of this neural crest-derived cell in the skin.

  20. Glucocorticoid receptor in human respiratory epithelial cells.

    PubMed

    Pujolsa, Laura; Mullol, Joaquim; Picado, Cèsar

    2009-01-01

    Inhaled and intranasal glucocorticoids (GCs) are the most common and effective drugs for controlling symptoms and airway inflammation in respiratory diseases such as allergic rhinitis, chronic rhinosinusitis with/without nasal polyps, and asthma, and the respiratory epithelium is a primary target of GC anti-inflammatory actions. GC effects are mediated through the GC receptor (GR). In humans, one single GR gene gives rise to two main GR products, namely GRalpha and GRbeta, which are subject to translational and posttranslational modifications. GRalpha is expressed in virtually all human cells and tissues, including respiratory epithelial cells, and - at least in vitro - is downregulated by GC. GRalpha mediates the anti-inflammatory actions of GC by activating transcription of anti-inflammatory genes through binding of GRalpha to glucocorticoid response elements (GRE) located in the promoter region of target genes, repressing transcription of proinflammatory genes through direct interaction between GRalpha and proinflammatory transcription factors, such as AP-1 and NF-kappaB (transrepression), and also by destabilizing the mRNA of proinflammatory mediators. GRbeta acts as a dominant negative inhibitor of GRalpha-mediated transactivation and transrepression in certain in vitro studies with transfected cells. The GRbeta message is expressed at low levels in numerous tissues and its protein is mainly expressed in inflammatory cells, although it has also been detected in airway epithelial cells. Increased GRbeta expression has been reported in bronchial asthma and nasal polyposis, and after incubation of cells with certain proinflammatory stimuli. However, the role of GRbeta in modulating GC sensitivity in vivo has been highly debated and is as yet unclear.

  1. In vitro and in vivo Analysis of the Binding of the C Terminus of the HDL Receptor Scavenger Receptor Class B type I (SR-BI) to the PDZ1 Domain of its Cytoplasmic Adaptor Protein PDZK1

    SciTech Connect

    O Kocher; G Birrane; K Tsukamoto; S Fenske; A Yesilaltay; R Pal; K Daniels; J Ladias; M Krieger

    2011-12-31

    The PDZ1 domain of the four PDZ domain-containing protein PDZK1 has been reported to bind the C terminus of the HDL receptor scavenger receptor class B, type I (SR-BI), and to control hepatic SR-BI expression and function. We generated wild-type (WT) and mutant murine PDZ1 domains, the mutants bearing single amino acid substitutions in their carboxylate binding loop (Lys(14)-Xaa(4)-Asn(19)-Tyr-Gly-Phe-Phe-Leu(24)), and measured their binding affinity for a 7-residue peptide corresponding to the C terminus of SR-BI ((503)VLQEAKL(509)). The Y20A and G21Y substitutions abrogated all binding activity. Surprisingly, binding affinities (K(d)) of the K14A and F22A mutants were 3.2 and 4.0 ?M, respectively, similar to 2.6 ?M measured for the WT PDZ1. To understand these findings, we determined the high resolution structure of WT PDZ1 bound to a 5-residue sequence from the C-terminal SR-BI ((505)QEAKL(509)) using x-ray crystallography. In addition, we incorporated the K14A and Y20A substitutions into full-length PDZK1 liver-specific transgenes and expressed them in WT and PDZK1 knock-out mice. In WT mice, the transgenes did not alter endogenous hepatic SR-BI protein expression (intracellular distribution or amount) or lipoprotein metabolism (total plasma cholesterol, lipoprotein size distribution). In PDZK1 knock-out mice, as expected, the K14A mutant behaved like wild-type PDZK1 and completely corrected their hepatic SR-BI and plasma lipoprotein abnormalities. Unexpectedly, the 10-20-fold overexpressed Y20A mutant also substantially, but not completely, corrected these abnormalities. The results suggest that there may be an additional site(s) within PDZK1 that bind(s) SR-BI and mediate(s) productive SR-BI-PDZK1 interaction previously attributed exclusively to the canonical binding of the C-terminal SR-BI to PDZ1.

  2. A critique of the evidence for scavenging by Neanderthals and early modern humans: new data from Kobeh Cave (Zagros Mountains, Iran) and Die Kelders Cave 1 layer 10 (South Africa).

    PubMed

    Marean, C W

    1998-08-01

    The primary mode of faunal exploitation by Neandertals and early modern humans remains a debated topic. Binford (1981, 1984, 1985, 1988) has argued for an obligate scavenging mode, Stiner (1991a, 1991b, 1991c, 1993, 1994) for a more opportunistic scavenging mode, while other researchers (Chase, 1986, 1988, 1989; Klein, 1989, 1994, 1995; Klein & Cruz-Uribe, 1996) deny the importance of scavenging as a faunal exploitation tactic. The scavenging interpretations rely primarily on several patterns in the faunal remains: the presence of a skeletal element pattern dominated by heads or head and foot parts, the presence of carnivore tooth marks on bone fragments, and infrequent cut marks that typically are not located on shaft regions of long bones or on fleshy bones. Five sites have been used to argue for scavenging: Klasies River Mouth, Combe Grenal, Grotta Guattari, Grotta dei Moscerini, and Grotte Vaufrey. The former four of the five sites are biased samples in that long bone shafts and other difficult to identify fragments were discarded at excavation. The analysis of Grotte Vaufrey included only those shafts identifiable to species or genus, thus excluding the vast majority of shaft specimens. This bias systematically shapes the skeletal element and surface modification patterning in ways that make the assemblages appear to fit a model of scavenging, when in fact the main determinant of the pattern is the bias in the flawed samples. This problem is illustrated with two unbiased faunal assemblages (Kobeh Cave and Die Kelders Layer 10). Skeletal element abundance is calculated in a way that mimics the bias in the sites listed above by excluding the shafts. Using this procedure, both Kobeh and Die Kelders have a head and foot skeletal element pattern and thus appear scavenged. Both assemblages are then analyzed in their entirety and a new pattern, consistent with hunting, is revealed. Taphonomic data on bone survival and destruction provide an explanation for this

  3. Simultaneous Profiling of 194 Distinct Receptor Transcripts in Human Cells

    PubMed Central

    Kang, Byong H.; Jensen, Karin J.; Hatch, Jaime A.; Janes, Kevin A.

    2013-01-01

    Many signal transduction cascades are initiated by transmembrane receptors with the presence or absence and abundance of receptors dictating cellular responsiveness. Here, we provide a validated array of quantitative reverse-transcription polymerase chain reaction (qRT-PCR) reagents for high-throughput profiling of the presence and relative abundance of transcripts for 194 transmembrane receptors in the human genome. We found that the qRT-PCR array had greater sensitivity and specificity for the detected receptor transcript profiles compared to conventional oligonucleotide microarrays or exon microarrays. The qRT-PCR array also distinguished functional receptor presence versus absence more accurately than deep sequencing of adenylated RNA species, RNA-seq. By applying qRT-PCR-based receptor transcript profiling to 40 human cell lines representing four main tissues (pancreas, skin, breast, and colon), we identified clusters of cell lines with enhanced signaling capabilities and revealed a role for receptor silencing in defining tissue lineage. Ectopic expression of the interleukin 10 (IL-10) receptor encoding gene IL10RA in melanoma cells engaged an IL-10 autocrine loop not otherwise present in this cell type, which altered signaling, gene expression, and cellular responses to proinflammatory stimuli. Our array provides a rapid, inexpensive, and convenient means for assigning a receptor signature to any human cell or tissue type. PMID:23921087

  4. Transmembrane signaling by a chimera of the Escherichia coli aspartate receptor and the human insulin receptor.

    PubMed Central

    Moe, G R; Bollag, G E; Koshland, D E

    1989-01-01

    Since many receptors apparently contain only one or two membrane-spanning segments, their transmembrane topology should be similar. This feature suggests that these receptors share common mechanisms of transmembrane signaling. To test the degree of conservation of signaling properties, a chimeric receptor containing the ligand-binding extracellular domain of the Escherichia coli aspartate chemoreceptor and the cytosolic portion of the human insulin receptor was constructed. This chimeric receptor is active as a tyrosine kinase, and aspartate stimulates its activity. Some interesting differences are noted in the target proteins phosphorylated by the chimera compared to the wild-type insulin receptor. These results indicate that features of the signaling mechanisms used by these diverse receptors are conserved, but that interesting changes in the protein properties are caused by differences in the neighboring domains. Images PMID:2548185

  5. Non-covalent interaction between dietary stilbenoids and human serum albumin: Structure-affinity relationship, and its influence on the stability, free radical scavenging activity and cell uptake of stilbenoids.

    PubMed

    Cao, Hui; Jia, Xueping; Shi, Jian; Xiao, Jianbo; Chen, Xiaoqing

    2016-07-01

    Dietary stilbenoids are associated with many benefits for human health, which depend on their bioavailability and bioaccessibility. The stilbenoid-human serum albumin (HSA) interactions are investigated to explore the structure-affinity relationship and influence on the stability, free radical scavenging activity and cell uptake of stilbenoids. The structure-affinity relationship of the stilbenoids-HSA interaction was found as: (1) the methoxylation enhanced the affinity, (2) an additional hydroxyl group increases the affinity and (3) the glycosylation significantly weakened the affinity. HSA obviously masked the free radical scavenging potential of stilbenoids. The stabilities of stilbenoids in different medium were determined as: HSA solution>human plasma>Dulbecco's modified Eagle's medium. It appears that the milk enhanced the cell uptake of stilbenoids with multi-hydroxyl groups and weakened the cell uptake of stilbenoids with methoxyl group on EA.hy 926 endothelial cells. The stilbenoids are hardly absorbed by human umbilical vein endothelial cells in the presence of milk.

  6. Adenosine receptor antagonists alter the stability of human epileptic GABAA receptors

    PubMed Central

    Roseti, Cristina; Martinello, Katiuscia; Fucile, Sergio; Piccari, Vanessa; Mascia, Addolorata; Di Gennaro, Giancarlo; Quarato, Pier Paolo; Manfredi, Mario; Esposito, Vincenzo; Cantore, Gianpaolo; Arcella, Antonella; Simonato, Michele; Fredholm, Bertil B.; Limatola, Cristina; Miledi, Ricardo; Eusebi, Fabrizio

    2008-01-01

    We examined how the endogenous anticonvulsant adenosine might influence γ-aminobutyric acid type A (GABAA) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 μM), GABAA receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABAA-current (IGABA) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced IGABA run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated IGABA run-down in ≈40% and ≈20% of tested oocytes, respectively. The ADA-resistant, AR agonist 2-chloroadenosine (2-CA) (10 μM) potentiated IGABA run-down but only in ≈20% of tested oocytes. CGS15943 administration again decreased IGABA run-down in patch-clamped neurons from either human or rat neocortex slices. IGABA run-down in pyramidal neurons was equivalent in A1 receptor-deficient and wt neurons but much larger in neurons from A2A receptor-deficient mice, indicating that, in mouse cortex, GABAA-receptor stability is tonically influenced by A2A but not by A1 receptors. IGABA run-down from wt mice was not affected by 2-CA, suggesting maximal ARs activity by endogenous adenosine. Our findings strongly suggest that cortical A2–A3 receptors alter the stability of GABAA receptors, which could offer therapeutic opportunities. PMID:18809912

  7. Expression of the Endocannabinoid Receptors in Human Fascial Tissue

    PubMed Central

    Fede, C.; Albertin, G.; Petrelli, L.; Sfriso, M.M.; Biz, C.; Caro, R. De; Stecco, C.

    2016-01-01

    Cannabinoid receptors have been localized in the central and peripheral nervous system as well as on cells of the immune system, but recent studies on animal tissue gave evidence for the presence of cannabinoid receptors in different types of tissues. Their presence was supposed also in myofascial tissue, suggesting that the endocannabinoid system may help resolve myofascial trigger points and relieve symptoms of fibromyalgia. However, until now the expression of CB1 (cannabinoid receptor 1) and CB2 (cannabinoid receptor 2) in fasciae has not yet been established. Small samples of fascia were collected from volunteers patients during orthopedic surgery. For each sample were done a cell isolation, immunohistochemical investigation (CB1 and CB2 antibodies) and real time RT-PCR to detect the expression of CB1 and CB2. Both cannabinoid receptors are expressed in human fascia and in human fascial fibroblasts culture cells, although to a lesser extent than the control gene. We can assume that the expression of mRNA and protein of CB1 and CB2 receptors in fascial tissue are concentrated into the fibroblasts. This is the first demonstration that the fibroblasts of the muscular fasciae express CB1 and CB2. The presence of these receptors could help to provide a description of cannabinoid receptors distribution and to better explain the role of fasciae as pain generator and the efficacy of some fascial treatments. Indeed the endocannabinoid receptors of fascial fibroblasts can contribute to modulate the fascial fibrosis and inflammation. PMID:27349320

  8. Characterization of muscarinic receptor subtypes in human tissues

    SciTech Connect

    Giraldo, E.; Martos, F.; Gomez, A.; Garcia, A.; Vigano, M.A.; Ladinsky, H.; Sanchez de La Cuesta, F.

    1988-01-01

    The affinities of selective, pirenzepine and AF-DX 116, and classical, N-methylscopolamine and atropine, muscarinic cholinergic receptor antagonists were investigated in displacement binding experiments with (/sup 3/H)Pirenzepine and (/sup 3/H)N-methylscopolamine in membranes from human autoptic tissues (forebrain, cerebellum, atria, ventricle and submaxillary salivary glands). Affinity estimates of N-methylscopolamine and atropine indicated a non-selective profile. Pirenzepine showed differentiation between the M/sub 1/ neuronal receptor of the forebrain and the receptors in other tissues while AF-DX 116 clearly discriminated between muscarinic receptors of heart and glands. The results in human tissues confirm the previously described selectivity profiles of pirenzepine and AF-DX 116 in rat tissues. These findings thus reveal the presence also in man of three distinct muscarinic receptor subtypes: the neuronal M/sub 1/, the cardiac M/sub 2/ and the glandular M/sub 3/.

  9. Propolis Inhibits UVA-Induced Apoptosis of Human Keratinocyte HaCaT Cells by Scavenging ROS

    PubMed Central

    Kim, Han Bit; Yoo, Byung Sun

    2016-01-01

    Propolis is a resinous material collected by honeybees from several plant sources. This research aimed at showing its protective effect against UVA-induced apoptosis of human keratinocyte HaCaT cells. Using Hoechst staining, it was demonstrated that propolis (5 and 10 μg/mL) significantly inhibited the apoptosis of HaCaT cells induced by UVA-irradiation. Propolis also showed the protective effect against loss of mitochondrial membrane potential induced by UVA-irradiaiton in HaCaT cells. Propolis also inhibited the expression of activated caspase-3 induced by UVA-irradiation. To investigate the role of ROS in UVA-induced apoptosis and protection by propolis, the generation of ROS was determined in cells. The results showed that the generation of ROS was markedly reduced in cells pretreated with propolis. Consequently, propolis protected human keratinocyte HaCaT cells against UVA-induced apoptosis, which might be related to the reduction of ROS generation by UVA-irradiation. PMID:27818737

  10. Propolis Inhibits UVA-Induced Apoptosis of Human Keratinocyte HaCaT Cells by Scavenging ROS.

    PubMed

    Kim, Han Bit; Yoo, Byung Sun

    2016-10-01

    Propolis is a resinous material collected by honeybees from several plant sources. This research aimed at showing its protective effect against UVA-induced apoptosis of human keratinocyte HaCaT cells. Using Hoechst staining, it was demonstrated that propolis (5 and 10 μg/mL) significantly inhibited the apoptosis of HaCaT cells induced by UVA-irradiation. Propolis also showed the protective effect against loss of mitochondrial membrane potential induced by UVA-irradiaiton in HaCaT cells. Propolis also inhibited the expression of activated caspase-3 induced by UVA-irradiation. To investigate the role of ROS in UVA-induced apoptosis and protection by propolis, the generation of ROS was determined in cells. The results showed that the generation of ROS was markedly reduced in cells pretreated with propolis. Consequently, propolis protected human keratinocyte HaCaT cells against UVA-induced apoptosis, which might be related to the reduction of ROS generation by UVA-irradiation.

  11. Melanocortin MC₁ receptor in human genetics and model systems.

    PubMed

    Beaumont, Kimberley A; Wong, Shu S; Ainger, Stephen A; Liu, Yan Yan; Patel, Mira P; Millhauser, Glenn L; Smith, Jennifer J; Alewood, Paul F; Leonard, J Helen; Sturm, Richard A

    2011-06-11

    The melanocortin MC(1) receptor is a G-protein coupled receptor expressed in the melanocytes of the skin and hair and is known for its key role in the regulation of human pigmentation. Melanocortin MC(1) receptor activation after ultraviolet radiation exposure results in a switch from the red/yellow pheomelanin to the brown/black eumelanin pigment synthesis within cutaneous melanocytes; this pigment is then transferred to the surrounding keratinocytes of the skin. The increase in melanin maturation and uptake results in tanning of the skin, providing a physical protection of skin cells from ultraviolet radiation induced DNA damage. Melanocortin MC(1) receptor polymorphism is widespread within the Caucasian population and some variant alleles are associated with red hair colour, fair skin, poor tanning and increased risk of skin cancer. Here we will discuss the use of mouse coat colour models, human genetic association studies, and in vitro cell culture studies to determine the complex functions of the melanocortin MC(1) receptor and the molecular mechanisms underlying the association between melanocortin MC(1) receptor variant alleles and the red hair colour phenotype. Recent research indicates that melanocortin MC(1) receptor has many non-pigmentary functions, and that the increased risk of skin cancer conferred by melanocortin MC(1) receptor variant alleles is to some extent independent of pigmentation phenotypes. The use of new transgenic mouse models, the study of novel melanocortin MC(1) receptor response genes and the use of more advanced human skin models such as 3D skin reconstruction may provide key elements in understanding the pharmacogenetics of human melanocortin MC(1) receptor polymorphism.

  12. [The role of the class A scavenger receptors, SR-A and MARCO, in the immune system. Part 2. Contribution to recognition and phagocytosis of pathogens as well as induction of immune response].

    PubMed

    Józefowski, Szczepan

    2012-02-29

    Recognition of pathogens by innate immune cells is mediated by pattern recognition receptors (PRR), which include the class A scavenger receptors (SR), SR-A/CD204 and MARCO. It seems that in addition to activating innate immune responses, phagocytosis and inflammation, this initial, PRR-mediated recognition also determines polarization of adaptive immune responses (Th1, Th2, Th17 or Treg). It has been demonstrated that class A SR are major PRR mediating opsonin-independent phagocytosis. SR-A- or MARCO-deficient mice exhibit impaired ability to control bacterial infections, resulting in increased mortality. Our results suggest that in addition to impaired bacterial destruction by macrophages, dysregulation of immune responses may contribute to defective antibacterial defense in class A SR-deficient mice. Using specific receptor ligation with antibodies, we showed that SR-A and MARCO regulate in an opposite manner production of IL-12 in macrophages, the cytokine playing a crucial role in Th1/Th2 polarization of adaptive immune responses. Together with the observation that expression of MARCO is increased by different Th1-polarizing factors and decreased by Th2-polarizing factors, these results suggest that changes in relative expression levels of SR-A and MARCO may be a mechanism of sustained polarization of adaptive immune responses.

  13. Human Receptor Activation by Aroclor 1260, a Polychlorinated Biphenyl Mixture

    PubMed Central

    Wahlang, Banrida; Falkner, K. Cameron; Clair, Heather B.; Al-Eryani, Laila; Prough, Russell A.; States, J. Christopher; Coslo, Denise M.; Omiecinski, Curtis J.; Cave, Matthew C.

    2014-01-01

    Polychlorinated biphenyls (PCBs) are persistent environmental toxicants, present in 100% of U.S. adults and dose-dependently associated with obesity and non-alcoholic fatty liver disease (NAFLD). PCBs are predicted to interact with receptors previously implicated in xenobiotic/energy metabolism and NAFLD. These receptors include the aryl hydrocarbon receptor (AhR), pregnane xenobiotic receptor (PXR), constitutive androstane receptor (CAR), peroxisome proliferator-activated receptors (PPARs), liver-X-receptor (LXRα), and farnesoid-X-receptor (FXR). This study evaluates Aroclor 1260, a PCB mixture with congener composition mimicking that of human adipose tissue, and selected congeners, as potential ligands for these receptors utilizing human hepatoma-derived (HepG2) and primate-derived (COS-1) cell lines, and primary human hepatocytes. Aroclor 1260 (20 μg/ml) activated AhR, and PCB 126, a minor component, was a potent inducer. Aroclor 1260 activated PXR in a simple concentration-dependent manner at concentrations ≥10 μg/ml. Among the congeners tested, PCBs 138, 149, 151, 174, 183, 187, and 196 activated PXR. Aroclor 1260 activated CAR2 and CAR3 variants at lower concentrations and antagonize CAR2 activation by the CAR agonist, CITCO, at higher concentrations (≥20 μg/ml). Additionally, Aroclor 1260 induced CYP2B6 in primary hepatocytes. At subtoxic doses, Aroclor 1260 did not activate LXR or FXR and had no effect on LXR- or FXR-dependent induction by the agonists T0901317 or GW4064, respectively. Aroclor 1260 (20 μg/ml) suppressed PPARα activation by the agonist nafenopin, although none of the congeners tested demonstrated significant inhibition. The results suggest that Aroclor 1260 is a human AhR, PXR and CAR3 agonist, a mixed agonist/antagonist for CAR2, and an antagonist for human PPARα. PMID:24812009

  14. Expression of glutamate receptor subunits in human cancers.

    PubMed

    Stepulak, Andrzej; Luksch, Hella; Gebhardt, Christine; Uckermann, Ortrud; Marzahn, Jenny; Sifringer, Marco; Rzeski, Wojciech; Staufner, Christian; Brocke, Katja S; Turski, Lechoslaw; Ikonomidou, Chrysanthy

    2009-10-01

    Emerging evidence suggests a role for glutamate and its receptors in the biology of cancer. This study was designed to systematically analyze the expression of ionotropic and metabotropic glutamate receptor subunits in various human cancer cell lines, compare expression levels to those in human brain tissue and, using electrophysiological techniques, explore whether cancer cells respond to glutamate receptor agonists and antagonists. Expression analysis of glutamate receptor subunits NR1-NR3B, GluR1-GluR7, KA1, KA2 and mGluR1-mGluR8 was performed by means of RT-PCR in human rhabdomyosarcoma/medulloblastoma (TE671), neuroblastoma (SK-NA-S), thyroid carcinoma (FTC 238), lung carcinoma (SK-LU-1), astrocytoma (MOGGCCM), multiple myeloma (RPMI 8226), glioma (U87-MG and U343), lung carcinoma (A549), colon adenocarcinoma (HT 29), T cell leukemia cells (Jurkat E6.1), breast carcinoma (T47D) and colon adenocarcinoma (LS180). Analysis revealed that all glutamate receptor subunits were differentially expressed in the tumor cell lines. For the majority of tumors, expression levels of NR2B, GluR4, GluR6 and KA2 were lower compared to human brain tissue. Confocal imaging revealed that selected glutamate receptor subunit proteins were expressed in tumor cells. By means of patch-clamp analysis, it was shown that A549 and TE671 cells depolarized in response to application of glutamate agonists and that this effect was reversed by glutamate receptor antagonists. This study reveals that glutamate receptor subunits are differentially expressed in human tumor cell lines at the mRNA and the protein level, and that their expression is associated with the formation of functional channels. The potential role of glutamate receptor antagonists in cancer therapy is a feasible goal to be explored in clinical trials.

  15. Evidence for Alpha Receptors in the Human Ureter

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

  16. Targeting xenobiotic receptors PXR and CAR in human diseases

    PubMed Central

    Banerjee, Monimoy; Robbins, Delira; Chen, Taosheng

    2014-01-01

    Nuclear receptors such as the pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are xenobiotic receptors regulating not only drug metabolism and disposition but also various human diseases such as cancer, diabetes, inflammatory disease, metabolic disease and liver diseases, suggesting that PXR and CAR are promising targets for drug discovery. Consequently, there is an urgent need to discover and develop small molecules that target these PXR- and/or CAR-mediated human-disease-related pathways for relevant therapeutic applications. This review proposes approaches to target PXR and CAR, either individually or simultaneously, in the context of various human diseases, taking into consideration the structural differences between PXR and CAR. PMID:25463033

  17. Cloning, functional expression and characterization of a human olfactory receptor.

    PubMed

    Hatt, H; Gisselmann, G; Wetzel, C H

    1999-05-01

    The human olfactory system can recognize and discriminate a large number of different odorant molecules. The detection of chemically distinct odorants begins with the binding of an odorant ligand to a specific receptor protein on the olfactory neuron cell surface. To address the problem of olfactory perception at a molecular level, we have cloned, functionally expressed and characterized the first human olfactory receptor (OR 17-40). Application of a mixture of hundred different odorants elicited a transient increase in intracellular calcium at HEK 293-cells which were transfected with a plasmid containing the receptor encoding DNA and a membrane import sequence. By subdividing the odorant mixture in smaller groups we could identify a single component which represented the only effective substance: helional. Testing some structurally closely related molecules we found only one other compound which also could activate the receptor: heliotropyl acetone. All other compounds tested were completely ineffective. These findings represent the beginning of molecular understanding of odorant recognition in humans.

  18. Antioxidant effects of the sarsaparilla via scavenging of reactive oxygen species and induction of antioxidant enzymes in human dermal fibroblasts.

    PubMed

    Park, Gunhyuk; Kim, Tae-mi; Kim, Jeong Hee; Oh, Myung Sook

    2014-07-01

    Ultraviolet (UV) radiation from sunlight causes distinct changes in collagenous skin tissues as a result of the breakdown of collagen, a major component of the extracellular matrix. UV irradiation downregulates reactive oxygen species (ROS)-elimination pathways, thereby promoting the production of ROS, which are implicated in skin aging. Smilax glabra Roxb (sarsaparilla) has been used in folk medicine because of its many effects. However, no study on the protective effects of sarsaparilla root (SR) on human dermal fibroblasts has been reported previously. Here, we investigated the protective effect of SR against oxidative stress in dermal fibroblasts. SR significantly inhibited oxidative damage and skin-aging factor via mitogen-activated protein kinase signaling pathways. Also, SR decreased Ca(2+) and ROS, mitochondrial membrane potential, dysfunction, and increased glutathione, NAD(P)H dehydrogenase and heme oxygenase-1. These results demonstrate that SR can protect dermal fibroblasts against UVB-induced skin aging via antioxidant effects.

  19. The Insect Ortholog of the Human Orphan Cytokine Receptor CRLF3 Is a Neuroprotective Erythropoietin Receptor

    PubMed Central

    Hahn, Nina; Knorr, Debbra Y.; Liebig, Johannes; Wüstefeld, Liane; Peters, Karsten; Büscher, Marita; Bucher, Gregor; Ehrenreich, Hannelore; Heinrich, Ralf

    2017-01-01

    The cytokine erythropoietin (Epo) mediates various cell homeostatic responses to environmental challenges and pathological insults. While stimulation of vertebrate erythrocyte production is mediated by homodimeric “classical” Epo receptors, alternative receptors are involved in neuroprotection. However, their identity remains enigmatic due to complex cytokine ligand and receptor interactions and conflicting experimental results. Besides the classical Epo receptor, the family of type I cytokine receptors also includes the poorly characterized orphan cytokine receptor-like factor 3 (CRLF3) present in vertebrates including human and various insect species. By making use of the more simple genetic makeup of insect model systems, we studied whether CRLF3 is a neuroprotective Epo receptor in animals. We identified a single ortholog of CRLF3 in the beetle Tribolium castaneum, and established protocols for primary neuronal cell cultures from Tribolium brains and efficient in vitro RNA interference. Recombinant human Epo as well as the non-erythropoietic Epo splice variant EV-3 increased the survival of serum-deprived brain neurons, confirming the previously described neuroprotective effect of Epo in insects. Moreover, Epo completely prevented hypoxia-induced apoptotic cell death of primary neuronal cultures. Knockdown of CRLF3 expression by RNA interference with two different double stranded RNA (dsRNA) fragments abolished the neuroprotective effect of Epo, indicating that CRLF3 is a crucial component of the insect Epo-responsive receptor. This suggests that a common urbilaterian ancestor of the orphan human and insect cytokine receptor CRLF3 served as a neuroprotective receptor for an Epo-like cytokine. Our work also suggests that vertebrate CRLF3, like its insect ortholog, might represent a tissue protection-mediating receptor. PMID:28769759

  20. The Insect Ortholog of the Human Orphan Cytokine Receptor CRLF3 Is a Neuroprotective Erythropoietin Receptor.

    PubMed

    Hahn, Nina; Knorr, Debbra Y; Liebig, Johannes; Wüstefeld, Liane; Peters, Karsten; Büscher, Marita; Bucher, Gregor; Ehrenreich, Hannelore; Heinrich, Ralf

    2017-01-01

    The cytokine erythropoietin (Epo) mediates various cell homeostatic responses to environmental challenges and pathological insults. While stimulation of vertebrate erythrocyte production is mediated by homodimeric "classical" Epo receptors, alternative receptors are involved in neuroprotection. However, their identity remains enigmatic due to complex cytokine ligand and receptor interactions and conflicting experimental results. Besides the classical Epo receptor, the family of type I cytokine receptors also includes the poorly characterized orphan cytokine receptor-like factor 3 (CRLF3) present in vertebrates including human and various insect species. By making use of the more simple genetic makeup of insect model systems, we studied whether CRLF3 is a neuroprotective Epo receptor in animals. We identified a single ortholog of CRLF3 in the beetle Tribolium castaneum, and established protocols for primary neuronal cell cultures from Tribolium brains and efficient in vitro RNA interference. Recombinant human Epo as well as the non-erythropoietic Epo splice variant EV-3 increased the survival of serum-deprived brain neurons, confirming the previously described neuroprotective effect of Epo in insects. Moreover, Epo completely prevented hypoxia-induced apoptotic cell death of primary neuronal cultures. Knockdown of CRLF3 expression by RNA interference with two different double stranded RNA (dsRNA) fragments abolished the neuroprotective effect of Epo, indicating that CRLF3 is a crucial component of the insect Epo-responsive receptor. This suggests that a common urbilaterian ancestor of the orphan human and insect cytokine receptor CRLF3 served as a neuroprotective receptor for an Epo-like cytokine. Our work also suggests that vertebrate CRLF3, like its insect ortholog, might represent a tissue protection-mediating receptor.

  1. G protein-coupled receptor mutations and human genetic disease.

    PubMed

    Thompson, Miles D; Hendy, Geoffrey N; Percy, Maire E; Bichet, Daniel G; Cole, David E C

    2014-01-01

    Genetic variations in G protein-coupled receptor genes (GPCRs) disrupt GPCR function in a wide variety of human genetic diseases. In vitro strategies and animal models have been used to identify the molecular pathologies underlying naturally occurring GPCR mutations. Inactive, overactive, or constitutively active receptors have been identified that result in pathology. These receptor variants may alter ligand binding, G protein coupling, receptor desensitization and receptor recycling. Receptor systems discussed include rhodopsin, thyrotropin, parathyroid hormone, melanocortin, follicle-stimulating hormone (FSH), luteinizing hormone, gonadotropin-releasing hormone (GNRHR), adrenocorticotropic hormone, vasopressin, endothelin-β, purinergic, and the G protein associated with asthma (GPRA or neuropeptide S receptor 1 (NPSR1)). The role of activating and inactivating calcium-sensing receptor (CaSR) mutations is discussed in detail with respect to familial hypocalciuric hypercalcemia (FHH) and autosomal dominant hypocalemia (ADH). The CASR mutations have been associated with epilepsy. Diseases caused by the genetic disruption of GPCR functions are discussed in the context of their potential to be selectively targeted by drugs that rescue altered receptors. Examples of drugs developed as a result of targeting GPCRs mutated in disease include: calcimimetics and calcilytics, therapeutics targeting melanocortin receptors in obesity, interventions that alter GNRHR loss from the cell surface in idiopathic hypogonadotropic hypogonadism and novel drugs that might rescue the P2RY12 receptor congenital bleeding phenotype. De-orphanization projects have identified novel disease-associated receptors, such as NPSR1 and GPR35. The identification of variants in these receptors provides genetic reagents useful in drug screens. Discussion of the variety of GPCRs that are disrupted in monogenic Mendelian disorders provides the basis for examining the significance of common

  2. The Crystal Structure of the Fifth Scavenger Receptor Cysteine-Rich Domain of Porcine CD163 Reveals an Important Residue Involved in Porcine Reproductive and Respiratory Syndrome Virus Infection.

    PubMed

    Ma, Hongfang; Jiang, Longguang; Qiao, Songlin; Zhi, Yubao; Chen, Xin-Xin; Yang, Yanyan; Huang, Xiaojing; Huang, Mingdong; Li, Rui; Zhang, Gai-Ping

    2017-02-01

    Porcine reproductive and respiratory syndrome (PRRS) has become an economically critical factor in swine industry since its worldwide spread in the 1990s. Infection by its causative agent, PRRS virus (PRRSV), was proven to be mediated by an indispensable receptor, porcine CD163 (pCD163), and the fifth scavenger receptor cysteine-rich domain (SRCR5) is essential for virus infection. However, the structural details and specific residues of pCD163 SRCR5 involved in infection have not been defined yet. In this study, we prepared recombinant pCD163 SRCR5 in Drosophila melanogaster Schneider 2 (S2) cells and determined its crystal structure at a high resolution of 2.0 Å. This structure includes a markedly long loop region and shows a special electrostatic potential, and these are significantly different from those of other members of the scavenger receptor cysteine-rich superfamily (SRCR-SF). Subsequently, we carried out structure-based mutational studies to identify that the arginine residue at position 561 (Arg561) in the long loop region is important for PRRSV infection. Further, we showed Arg561 probably takes effect on the binding of pCD163 to PRRSV during virus invasion. Altogether the current work provides the first view of the CD163 SRCR domain, expands our knowledge of the invasion mechanism of PRRSV, and supports a molecular basis for prevention and control of the virus. PRRS has caused huge economic losses to pig farming. The syndrome is caused by PRRSV, and PRRSV infection has been shown to be mediated by host cell surface receptors. One of them, pCD163, is especially indispensable, and its SRCR5 domain has been further demonstrated to play a significant role in virus infection. However, its structural details and the residues involved in infection are unknown. In this study, we determined the crystal structure of pCD163 SRCR5 and then carried out site-directed mutational studies based on the crystal structure to elucidate which residue is important. Our

  3. Autoimmune anti-androgen-receptor antibodies in human serum.

    PubMed Central

    Liao, S; Witte, D

    1985-01-01

    Circulating autoantibodies to human and rat androgen receptors are present at high titers in the blood sera of some patients with prostate diseases. The antibodies from some serum samples were associated with a purified IgG fraction and interacted with the 3.8S cytosolic androgen-receptor complexes of rat ventral prostate to form 9- to 12S units. Other serum samples, however, formed 14- to 19S units, suggesting that other immunoglobulins might be involved. In the presence of an anti-human immunoglobulin as a second antibody, the androgen-receptor-antibody complexes could be immunoprecipitated. The antibodies interacted with the nuclear and the cytosolic androgen-receptor complexes, either the DNA-binding or the nonbinding form, but not with receptors for estradiol, progestin, or dexamethasone from a variety of sources. Human testosterone/estradiol-binding globulin, rat epididymal androgen-binding protein, or rat prostate alpha-protein (a nonreceptor steroid-binding protein) also did not interact with the antibodies to form immunoprecipitates. About 37% of male and 3% of female serum samples screened had significant antibody titer. The chance of finding serum with a high titer is much better in males older than 66 years than in the younger males or females at all ages. The presence of the high-titer antibodies may make it possible to prepare monoclonal antibodies to androgen receptors without purification of the receptors for immunization. PMID:3866227

  4. Functional CB1 cannabinoid receptors in human vascular endothelial cells.

    PubMed Central

    Liu, J; Gao, B; Mirshahi, F; Sanyal, A J; Khanolkar, A D; Makriyannis, A; Kunos, G

    2000-01-01

    Cannabinoid CB1 receptor mRNA was detected using reverse transcription-polymerase chain reaction (RT-PCR) in endothelial cells from human aorta and hepatic artery and in the ECV304 cell line derived from human umbilical vein endothelial cells. CB1 receptor-binding sites were detected by the high-affinity antagonist radioligand [(125)I]AM-251. In ECV304 cells, both the highly potent synthetic cannabinoid agonist HU-210 and the endogenous ligand anandamide induce activation of mitogen-activated protein (MAP) kinase, and the effect of HU-210 was completely blocked, whereas the effect of anandamide was partially inhibited by SR141716A, a selective CB1 receptor antagonist. Transfection of ECV304 cells with CB1 receptor antisense, but not sense, oligonucleotides caused the same pattern of inhibition as SR141716A. This provides more definitive evidence for the involvement of CB1 receptors in MAP kinase activation and suggests that anandamide may also activate MAP kinase via an additional, CB1 receptor-independent, SR141716A-resistant mechanism. The MAP kinase activation by anandamide in ECV304 cells requires genistein-sensitive tyrosine kinases and protein kinase C (PKC), and anandamide also activates p38 kinase and c-Jun kinase. These findings indicate that CB1 receptors located in human vascular endothelium are functionally coupled to the MAP kinase cascade. Activation of protein kinase cascades by anandamide may be involved in the modulation of endothelial cell growth and proliferation. PMID:10698714

  5. Distribution of cellular HSV-1 receptor expression in human brain.

    PubMed

    Lathe, Richard; Haas, Juergen G

    2016-12-15

    Herpes simplex virus type 1 (HSV-1) is a neurotropic virus linked to a range of acute and chronic neurological disorders affecting distinct regions of the brain. Unusually, HSV-1 entry into cells requires the interaction of viral proteins glycoprotein D (gD) and glycoprotein B (gB) with distinct cellular receptor proteins. Several different gD and gB receptors have been identified, including TNFRSF14/HVEM and PVRL1/nectin 1 as gD receptors and PILRA, MAG, and MYH9 as gB receptors. We investigated the expression of these receptor molecules in different areas of the adult and developing human brain using online transcriptome databases. Whereas all HSV-1 receptors showed distinct expression patterns in different brain areas, the Allan Brain Atlas (ABA) reported increased expression of both gD and gB receptors in the hippocampus. Specifically, for PVRL1, TNFRFS14, and MYH9, the differential z scores for hippocampal expression, a measure of relative levels of increased expression, rose to 2.9, 2.9, and 2.5, respectively, comparable to the z score for the archetypical hippocampus-enriched mineralocorticoid receptor (NR3C2, z = 3.1). These data were confirmed at the Human Brain Transcriptome (HBT) database, but HBT data indicate that MAG expression is also enriched in hippocampus. The HBT database allowed the developmental pattern of expression to be investigated; we report that all HSV1 receptors markedly increase in expression levels between gestation and the postnatal/adult periods. These results suggest that differential receptor expression levels of several HSV-1 gD and gB receptors in the adult hippocampus are likely to underlie the susceptibility of this brain region to HSV-1 infection.

  6. Identification of agonists for a group of human odorant receptors

    PubMed Central

    Gonzalez-Kristeller, Daniela C.; do Nascimento, João B. P.; Galante, Pedro A. F.; Malnic, Bettina

    2015-01-01

    Olfaction plays a critical role in several aspects of the human life. Odorants are detected by hundreds of odorant receptors (ORs) which belong to the superfamily of G protein-coupled receptors. These receptors are expressed in the olfactory sensory neurons of the nose. The information provided by the activation of different combinations of ORs in the nose is transmitted to the brain, leading to odorant perception and emotional and behavioral responses. There are ~400 intact human ORs, and to date only a small percentage of these receptors (~10%) have known agonists. The determination of the specificity of the human ORs will contribute to a better understanding of how odorants are discriminated by the olfactory system. In this work, we aimed to identify human specific ORs, that is, ORs that are present in humans but absent from other species, and their corresponding agonists. To do this, we first selected 22 OR gene sequences from the human genome with no counterparts in the mouse, rat or dog genomes. Then we used a heterologous expression system to screen a subset of these human ORs against a panel of odorants of biological relevance, including foodborne aroma volatiles. We found that different types of odorants are able to activate some of these previously uncharacterized human ORs. PMID:25784876

  7. Homology modeling of human muscarinic acetylcholine receptors.

    PubMed

    Thomas, Trayder; McLean, Kimberley C; McRobb, Fiona M; Manallack, David T; Chalmers, David K; Yuriev, Elizabeth

    2014-01-27

    We have developed homology models of the acetylcholine muscarinic receptors M₁R-M₅R, based on the β₂-adrenergic receptor crystal as the template. This is the first report of homology modeling of all five subtypes of acetylcholine muscarinic receptors with binding sites optimized for ligand binding. The models were evaluated for their ability to discriminate between muscarinic antagonists and decoy compounds using virtual screening using enrichment factors, area under the ROC curve (AUC), and an early enrichment measure, LogAUC. The models produce rational binding modes of docked ligands as well as good enrichment capacity when tested against property-matched decoy libraries, which demonstrates their unbiased predictive ability. To test the relative effects of homology model template selection and the binding site optimization procedure, we generated and evaluated a naïve M₂R model, using the M₃R crystal structure as a template. Our results confirm previous findings that binding site optimization using ligand(s) active at a particular receptor, i.e. including functional knowledge into the model building process, has a more pronounced effect on model quality than target-template sequence similarity. The optimized M₁R-M₅R homology models are made available as part of the Supporting Information to allow researchers to use these structures, compare them to their own results, and thus advance the development of better modeling approaches.

  8. A Geospatial Scavenger Hunt

    ERIC Educational Resources Information Center

    Martinez, Adriana E.; Williams, Nikki A.; Metoyer, Sandra K.; Morris, Jennifer N.; Berhane, Stephen A.

    2009-01-01

    With the use of technology such as Global Positioning System (GPS) units and Google Earth for a simple-machine scavenger hunt, you will transform a standard identification activity into an exciting learning experience that motivates students, incorporates practical skills in technology, and enhances students' spatial-thinking skills. In the…

  9. A Geometric Scavenger Hunt

    ERIC Educational Resources Information Center

    Smart, Julie; Marshall, Jeff

    2007-01-01

    Children possess a genuine curiosity for exploring the natural world around them. One third grade teacher capitalized on this inherent trait by leading her students on "A Geometric Scavenger Hunt." The four-lesson inquiry investigation described in this article integrates mathematics and science. Among the students' discoveries was the fact that…

  10. A Geometric Scavenger Hunt

    ERIC Educational Resources Information Center

    Smart, Julie; Marshall, Jeff

    2007-01-01

    Children possess a genuine curiosity for exploring the natural world around them. One third grade teacher capitalized on this inherent trait by leading her students on "A Geometric Scavenger Hunt." The four-lesson inquiry investigation described in this article integrates mathematics and science. Among the students' discoveries was the fact that…

  11. A Geospatial Scavenger Hunt

    ERIC Educational Resources Information Center

    Martinez, Adriana E.; Williams, Nikki A.; Metoyer, Sandra K.; Morris, Jennifer N.; Berhane, Stephen A.

    2009-01-01

    With the use of technology such as Global Positioning System (GPS) units and Google Earth for a simple-machine scavenger hunt, you will transform a standard identification activity into an exciting learning experience that motivates students, incorporates practical skills in technology, and enhances students' spatial-thinking skills. In the…

  12. Regulation of adiponectin receptor 1 in human hepatocytes by agonists of nuclear receptors

    SciTech Connect

    Neumeier, Markus; Weigert, Johanna; Schaeffler, Andreas; Weiss, Thomas; Kirchner, Stefan; Laberer, Sabine; Schoelmerich, Juergen; Buechler, Christa . E-mail: christa.buechler@klinik.uni-regensburg.de

    2005-09-02

    The adiponectin receptors AdipoR1 and AdipoR2 have been identified to mediate the insulin-sensitizing effects of adiponectin. Although AdipoR2 was suggested to be the main receptor for this adipokine in hepatocytes, AdipoR1 protein is highly abundant in primary human hepatocytes and hepatocytic cell lines. Nuclear receptors are main regulators of lipid metabolism and activation of peroxisome proliferator-activated receptor {alpha} and {gamma}, retinoid X receptor (RXR), and liver X receptor (LXR) by specific ligands may influence AdipoR1 abundance. AdipoR1 protein is neither altered by RXR or LXR agonists nor by pioglitazone. In contrast, fenofibric acid reduces AdipoR1 whereas hepatotoxic troglitazone upregulates AdipoR1 protein in HepG2 cells. Taken together this work shows for the first time that AdipoR1 protein is expressed in human hepatocytes but that it is not a direct target gene of nuclear receptors. Elevated AdipoR1 induced by hepatotoxic troglitazone may indicate a role of this receptor in adiponectin-mediated beneficial effects in liver damage.

  13. CD36 is required for phagocytosis of apoptotic cells by human macrophages that use either a phosphatidylserine receptor or the vitronectin receptor (alpha v beta 3).

    PubMed

    Fadok, V A; Warner, M L; Bratton, D L; Henson, P M

    1998-12-01

    In vivo, apoptotic cells are efficiently removed by professional or nonprofessional phagocytes, a process thought to be essential for tissue remodeling and resolution of inflammation. Macrophages recognize apoptotic cells by several mechanisms, including recognition of exposed phosphatidylserine (PS); however, PS recognition on apoptotic cells has not been identified as a feature of human macrophages. The purpose of this study was to determine whether human monocyte-derived macrophages could be stimulated to recognize PS, defined as inhibition of phagocytosis by PS-containing liposomes. We also assessed the potential roles for scavenger receptors, CD14, and lectins. Uptake of apoptotic neutrophils into unstimulated macrophages was blocked about 50% by Arg-Gly-Asp-Ser and anti-alpha(v), and up to 20% by oxidized low density lipoprotein and N-acetylglucosamine, implying a major role for integrin and minor roles for scavenger and lectin receptors. Uptake into macrophages stimulated with beta-1,3-glucan was blocked 50% by PS liposomes and 40% by oxidized low density lipoprotein, suggesting that the macrophages had switched from using integrin to recognition of PS. MEM-18 and 61D3 (anti-CD14 mAbs) were poor inhibitors of apoptotic neutrophil uptake, but good inhibitors of apoptotic lymphocyte uptake. The switch to PS recognition was accompanied by down-regulation of alpha(v)beta3 expression and function. Anti-CD36 blocked uptake into unstimulated or stimulated macrophages, suggesting CD36 involvement not only with the alpha(v)beta3 integrin mechanism (as previously reported) but also with PS recognition. A maximum of 70% inhibition was achieved by combining anti-CD36 with either anti-a(v) or PS liposomes.

  14. Expression of prostanoid receptors in human ductus arteriosus

    PubMed Central

    Leonhardt, Andreas; Glaser, Alexander; Wegmann, Markus; Schranz, Dietmar; Seyberth, Hannsjörg; Nüsing, Rolf

    2003-01-01

    Prostaglandins play a major role in maintaining ductal patency in utero. Ductal tone is regulated by both locally released and circulating vasodilatory prostaglandins. In infants with ductus arteriosus-dependent congenital heart disease, ductal patency is maintained by intravenous administration of prostaglandin (PG) E1. Little information is available regarding the expression of prostaglandin receptors in man. By means of RT–PCR and immunohistochemistry we studied the expression of the PGI2 receptor (IP), the four different PGE2 receptors (EP1, EP2, EP3 and EP4), and the receptors for thromboxane (Tx) A2 (TP), PGD2 (DP) and PGF2α (FP) in the ductus arteriosus of three newborn infants with ductus arteriosus-dependent congenital heart disease and intravenous infusion of PGE1 and of one 8 month old child with a patent ductus arteriosus. The EP3, EP4, FP, IP and TP receptor were markedly expressed at the mRNA and protein level, whereas the EP2 receptor was weakly expressed and the EP1 receptor was detected in two out of four tissue specimens only. The DP receptor was not detected in any of the samples. The most pronounced expression, which was located in the media of the ductus arteriosus, was observed for the EP4 and TP receptors followed by IP and FP receptor protein. These data indicate that ductal patency during the infusion of PGE1 in infants with ductus arteriosus-dependent congenital heart disease might be mediated by the EP4 and IP receptor. The data further suggest that a heterogeneous population of prostanoid receptors may contribute to the regulation of ductus arteriosus tone in humans. PMID:12598419

  15. Expression of human peripheral cannabinoid receptor for structural studies

    PubMed Central

    Yeliseev, Alexei A.; Wong, Karen K.; Soubias, Olivier; Gawrisch, Klaus

    2005-01-01

    Human peripheral-type cannabinoid receptor (CB2) was expressed in Escherichia coli as a fusion with the maltose-binding protein, thioredoxin, and a deca-histidine tag. Functional activity and structural integrity of the receptor in bacterial protoplast membranes was confirmed by extensive binding studies with a variety of natural and synthetic cannabinoid ligands. E. coli membranes expressing CB2 also activated cognate G-proteins in an in vitro coupled assay. Detergent-solubilized receptor was purified to 80%–90% homogeneity by affinity chromatography followed by ion-exchange chromatography. By high-resolution NMR on the receptor in DPC micelles, it was determined that purified CB2 forms 1:1 complexes with the ligands CP-55,940 and anandamide. The receptor was successfully reconstituted into phosphatidylcholine bilayers and the membranes were deposited into a porous substrate as tubular lipid bilayers for structural studies by NMR and scattering techniques. PMID:16195551

  16. The structural basis for receptor recognition of human interleukin-18.

    PubMed

    Tsutsumi, Naotaka; Kimura, Takeshi; Arita, Kyohei; Ariyoshi, Mariko; Ohnishi, Hidenori; Yamamoto, Takahiro; Zuo, Xiaobing; Maenaka, Katsumi; Park, Enoch Y; Kondo, Naomi; Shirakawa, Masahiro; Tochio, Hidehito; Kato, Zenichiro

    2014-12-15

    Interleukin (IL)-18 is a proinflammatory cytokine that belongs to the IL-1 family and plays an important role in inflammation. The uncontrolled release of this cytokine is associated with severe chronic inflammatory disease. IL-18 forms a signalling complex with the IL-18 receptor α (Rα) and β (Rβ) chains at the plasma membrane, which induces multiple inflammatory cytokines. Here, we present a crystal structure of human IL-18 bound to the two receptor extracellular domains. Generally, the receptors' recognition mode for IL-18 is similar to IL-1β; however, certain notable differences were observed. The architecture of the IL-18 receptor second domain (D2) is unique among the other IL-1R family members, which presumably distinguishes them from the IL-1 receptors that exhibit a more promiscuous ligand recognition mode. The structures and associated biochemical and cellular data should aid in developing novel drugs to neutralize IL-18 activity.

  17. Fluorescent Ligand for Human Progesterone Receptor Imaging in Live Cells

    PubMed Central

    2013-01-01

    We employed molecular modeling to design and then synthesize fluorescent ligands for the human progesterone receptor. Boron dipyrromethene (BODIPY) or tetramethylrhodamine were conjugated to the progesterone receptor antagonist RU486 (Mifepristone) through an extended hydrophilic linker. The fluorescent ligands demonstrated comparable bioactivity to the parent antagonist in live cells and triggered nuclear translocation of the receptor in a specific manner. The BODIPY labeled ligand was applied to investigate the dependency of progesterone receptor nuclear translocation on partner proteins and to show that functional heat shock protein 90 but not immunophilin FKBP52 activity is essential. A tissue distribution study indicated that the fluorescent ligand preferentially accumulates in tissues that express high levels of the receptor in vivo. The design and properties of the BODIPY-labeled RU486 make it a potential candidate for in vivo imaging of PR by positron emission tomography through incorporation of 18F into the BODIPY core. PMID:23600997

  18. Pharmacologically novel GABA receptor in human dorsal root ganglion neurons.

    PubMed

    Valeyev, A Y; Hackman, J C; Wood, P M; Davidoff, R A

    1996-11-01

    1. Whole cell voltage-clamp studies of gamma-aminobutyric acid (GABA) receptors were performed on large (> 80 microns) cultured human dorsal root ganglion (DRG) neurons. 2. GABA and pentobarbital sodium when applied in micromolar concentrations evoked inward Cl- currents in DRG neurons voltage clamped at negative membrane potentials. 3. Diazepam (10 microM) and pentobarbital (10 microM) upmodulated the GABA current by approximately 149 and 168%, respectively. 4. The GABA currents in human DRG cells were unaffected by the classical GABA antagonists picrotoxin and bicuclline (100 microM). In contrast, the GABA responses evoked in adult rat DRG cells cultured in an identical manner were inhibited by both antagonists. The glycine receptor antagonist strychnine (100 microM) did not alter GABA currents in human DRG cells. 5. Human DRG cells did not respond to glycine (10-100 microM) or taurine (10-100 microM). The GABAB agonist baclofen had no effect on the holding current when patch pipettes were filled with 130 mM KCl. The GABAB antagonists saclofen applied either alone or with GABA was without effect. 6. The differences between the GABA receptors described here and GABA receptors in other species may reflect the presence of receptor subunits unique to human DRG cells.

  19. The cardiac glycoside-receptor system in the human heart.

    PubMed

    Erdmann, E; Brown, L

    1983-01-01

    Specific binding sites have been demonstrated to exist in the heart for several drugs and hormones such as beta-blocking agents, cardiac glycosides, catecholamines, insulin, glucagon and acetylcholine. The specific binding sites for cardiac glycosides in the human heart have certain properties which make it likely that they are the pharmacological receptors for the therapeutic and toxic actions of digitalis glycosides: they are located in the cell membrane and bind cardioactive steroids reversibly with high affinity: half-maximal receptor binding occurs at approximately 2 nM (approximately 1.5 ng/ml) for digoxin; potassium decreases receptor affinity, calcium increases it; specific binding of ouabain, digoxin or digitoxin is related to inhibition of (Na+ + K+)-ATPase activity--which is supposed to be the receptor enzyme for cardiac glycosides. Human left ventricle contains approximately 1.5 x 10(14) binding sites/g wet weight, right ventricle approximately 0.9 x 10(14). In disease the number of receptors may decrease (hypothyroid states, myocardial infarction) or increase (hyperthyroidism, chronic hypokalaemia). Certain drugs (such as phenytoin) or different temperatures or pH changes cause a change in digitalis-receptor affinity. Thus, the number of receptors and possibly their properties are subject to regulation in clinically relevant situations. Further investigations will probably reveal those pathophysiological states, which allow the explanation of toxicity or digitalis refractoriness.

  20. Endomorphins fully activate a cloned human mu opioid receptor.

    PubMed

    Gong, J; Strong, J A; Zhang, S; Yue, X; DeHaven, R N; Daubert, J D; Cassel, J A; Yu, G; Mansson, E; Yu, L

    1998-11-13

    Endomorphins were recently identified as endogenous ligands with high selectivity for mu opioid receptors. We have characterized the ability of endomorphins to bind to and functionally activate the cloned human mu opioid receptor. Both endomorphin-1 and endomorphin-2 exhibited binding selectivity for the mu opioid receptor over the delta and kappa opioid receptors. Both agonists inhibited forskolin-stimulated increase of cAMP in a dose-dependent fashion. When the mu opioid receptor was coexpressed in Xenopus oocytes with G protein-activated K+ channels, application of either endomorphin activated an inward K+ current. This activation was dose-dependent and blocked by naloxone. Both endomorphins acted as full agonists with efficacy similar to that of [D-Ala2,N-Me-Phe4,Gly-ol5]enkephalin (DAMGO). These data indicate that endomorphins act as full agonists at the human mu opioid receptor, capable of stimulating the receptor to inhibit the cAMP/adenylyl cyclase pathway and activate G-protein-activated inwardly rectifying potassium (GIRK) channels.

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

    SciTech Connect

    Wu, Kailang; Li, Weikai; Peng, Guiqing; Li, Fang

    2010-03-04

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

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

    PubMed

    Wu, Kailang; Li, Weikai; Peng, Guiqing; Li, Fang

    2009-11-24

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

  3. The human T cell receptor alpha variable (TRAV) genes.

    PubMed

    Scaviner, D; Lefranc, M P

    2000-01-01

    'Human T Cell Receptor Alpha Variable (TRAV) Genes', the eighth report of the 'IMGT Locus in Focus' section, comprises four tables: (1) 'Number of human germline TRAV genes at 14q11 and potential repertoire'; (2) 'Human germline TRAV genes at 14q11'; (3) 'Human TRAV allele table', and (4) 'Correspondence between the different human TRAV gene nomenclatures'. These tables are available at the IMGT Marie-Paule page of IMGT, the international ImMunoGeneTics database (http://imgt.cines.fr:8104) created by Marie-Paule Lefranc, Université Montpellier II, CNRS, France. Copyright 2000 S. Karger AG, Basel

  4. Adenosine receptors and asthma in humans.

    PubMed

    Wilson, C N

    2008-10-01

    According to an executive summary of the GINA dissemination committee report, it is now estimated that approximately 300 million people (5% of the global population or 1 in 20 persons) have asthma. Despite the scientific progress made over the past several decades toward improving our understanding of the pathophysiology of asthma, there is still a great need for improved therapies, particularly oral therapies that enhance patient compliance and that target new mechanisms of action. Adenosine is an important signalling molecule in human asthma. By acting on extracellular G-protein-coupled ARs on a number of different cell types important in the pathophysiology of human asthma, adenosine affects bronchial reactivity, inflammation and airway remodelling. Four AR subtypes (A(1), A(2a), A(2b) and A(3)) have been cloned in humans, are expressed in the lung, and are all targets for drug development for human asthma. This review summarizes what is known about these AR subtypes and their function in human asthma as well as the pros and cons of therapeutic approaches to these AR targets. A number of molecules with high affinity and high selectivity for the human AR subtypes have entered clinical trials or are poised to enter clinical trials as anti-asthma treatments. With the availability of these molecules for testing in humans, the function of ARs in human asthma, as well as the safety and efficacy of approaches to the different AR targets, can now be determined.

  5. Leptin secretion and leptin receptor in the human stomach

    PubMed Central

    Sobhani, I; Bado, A; Vissuzaine, C; Buyse, M; Kermorgant, S; Laigneau, J; Attoub, S; Lehy, T; Henin, D; Mignon, M; Lewin, M

    2000-01-01

    BACKGROUND AND AIM—The circulating peptide leptin produced by fat cells acts on central receptors to control food intake and body weight homeostasis. Contrary to initial reports, leptin expression has also been detected in the human placenta, muscles, and recently, in rat gastric chief cells. Here we investigate the possible presence of leptin and leptin receptor in the human stomach.
METHODS—Leptin and leptin receptor expression were assessed by immunohistochemistry, reverse transcriptase-polymerase chain reaction (RT-PCR), and western blot analysis on biopsy samples from 24 normal individuals. Fourteen (10 healthy volunteers and four patients with non-ulcer dyspepsia and normal gastric mucosa histology) were analysed for gastric secretions. Plasma and fundic mucosa leptin content was determined by radioimmunoassay.
RESULTS—In fundic biopsies from normal individuals, immunoreactive leptin cells were found in the lower half of the fundic glands. mRNA encoding ob protein was detected in the corpus of the human stomach. The amount of fundic leptin was 10.4 (3.7) ng leptin/g mucosa, as determined by radioimmunoassay. Intravenous infusions of pentagastrin or secretin caused an increase in circulating leptin levels and leptin release into the gastric juice. The leptin receptor was present in the basolateral membranes of fundic and antral gastric cells. mRNA encoding Ob-RL was detected in both the corpus and antrum, consistent with a protein of ~120 kDa detected by immunoblotting.
CONCLUSION—These data provide the first evidence of the presence of leptin and leptin receptor proteins in the human stomach and suggest that gastric epithelial cells may be direct targets for leptin. Therefore, we conclude that leptin may have a physiological role in the human stomach, although much work is required to establish this.


Keywords: leptin; leptin receptor; human stomach; gastrin; secretin PMID:10896907

  6. Characterization of the inhibitory prostanoid receptors on human neutrophils.

    PubMed Central

    Wheeldon, A.; Vardey, C. J.

    1993-01-01

    1. We have evaluated the effects of various prostanoid agonists on the release of leukotriene B4 (LTB4) and superoxide anions (O2-) from human neutrophils stimulated with opsonized zymosan (OZ) and formyl-methionyl-leucyl-phenylalanine (FMLP), respectively. 2. Prostaglandin E2 (PGE2) and PGD2 inhibited both OZ-induced LTB4 release (EC50 0.72 microM and 0.91 microM respectively), and FMLP-induced O2- release (EC50 0.42 microM and 0.50 microM respectively). PGF2 alpha, the TP-receptor agonist, U46619, and the IP-receptor agonist, iloprost, were also active, but were all at least an order of magnitude less potent than PGE2 and PGD2. 3. The EP2/EP3-receptor agonist, misoprostol, and the selective EP2-agonist, AH13205, were both effective inhibitors of LTB4 release, being approximately equipotent with and 16-times less potent than PGE2, respectively. In contrast, the EP1/EP3-receptor agonist, sulprostone, had no inhibitory activity at concentrations of up to 10 microM. 4. The selective DP-receptor agonist, BW245C, inhibited LTB4 release, (EC50 0.006 microM) being approximately 50 times more potent than PGD2. BW245C also inhibited O2- release, and this inhibition was antagonized competitively by the DP-receptor blocking drug, AH6809 (pA2 6.6). 5. These data indicate the presence of both inhibitory EP- and DP-receptors on the human neutrophil. The rank order of potency of EP-receptor agonists suggest that the EP-receptors are of the EP2-subtype. PMID:8387383

  7. Mu opioid receptor binding sites in human brain

    SciTech Connect

    Pilapil, C.; Welner, S.; Magnan, J.; Zamir, N.; Quirion, R.

    1986-01-01

    Our experiments focused on the examination of the distribution of mu opioid receptor binding sites in normal human brain using the highly selective ligand (/sup 3/H)DAGO, in both membrane binding assay and in vitro receptor autoradiography. Mu opioid binding sites are very discretely distributed in human brain with high densities of sites found in the posterior amygdala, caudate, putamen, hypothalamus and certain cortical areas. Moreover the autoradiographic distribution of (/sup 3/H)DAGO binding sites clearly reveals the discrete lamination (layers I and III-IV) of mu sites in cortical areas.

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

    SciTech Connect

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

    2013-11-15

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

  9. Monoclonal Antibodies to the Human Insulin Receptor that Activate Glucose Transport but not Insulin Receptor Kinase Activity

    NASA Astrophysics Data System (ADS)

    Forsayeth, John R.; Caro, Jose F.; Sinha, Madhur K.; Maddux, Betty A.; Goldfine, Ira D.

    1987-05-01

    Three mouse monoclonal antibodies were produced that reacted with the α subunit of the human insulin receptor. All three both immunoprecipitated 125I-labeled insulin receptors from IM-9 lymphocytes and competitively inhibited 125I-labeled insulin binding to its receptor. Unlike insulin, the antibodies failed to stimulate receptor autophosphorylation in both intact IM-9 lymphocytes and purified human placental insulin receptors. Moreover, unlike insulin, the antibodies failed to stimulate receptor-mediated phosphorylation of exogenous substrates. However, like insulin, two of the three antibodies stimulated glucose transport in isolated human adipocytes. One antibody, on a molar basis, was as potent as insulin. These studies indicate, therefore, that monoclonal antibodies to the insulin receptor can mimic a major function of insulin without activating receptor kinase activity. They also raise the possibility that certain actions of insulin such as stimulation of glucose transport may not require the activation of receptor kinase activity.

  10. Chemotaxis, chemokine receptors and human disease.

    PubMed

    Jin, Tian; Xu, Xuehua; Hereld, Dale

    2008-10-01

    Cell migration is involved in diverse physiological processes including embryogenesis, immunity, and diseases such as cancer and chronic inflammatory disease. The movement of many cell types is directed by extracellular gradients of diffusible chemicals. This phenomenon, referred to as "chemotaxis", was first described in 1888 by Leber who observed the movement of leukocytes toward sites of inflammation. We now know that a large family of small proteins, chemokines, serves as the extracellular signals and a family of G-protein-coupled receptors (GPCRs), chemokine receptors, detects gradients of chemokines and guides cell movement in vivo. Currently, we still know little about the molecular machineries that control chemokine gradient sensing and migration of immune cells. Fortunately, the molecular mechanisms that control these fundamental aspects of chemotaxis appear to be evolutionarily conserved, and studies in lower eukaryotic model systems have allowed us to form concepts, uncover molecular components, develop new techniques, and test models of chemotaxis. These studies have helped our current understanding of this complicated cell behavior. In this review, we wish to mention landmark discoveries in the chemotaxis research field that shaped our current understanding of this fundamental cell behavior and lay out key questions that remain to be addressed in the future.

  11. Transgenic silkworms expressing human insulin receptors for evaluation of therapeutically active insulin receptor agonists.

    PubMed

    Matsumoto, Yasuhiko; Ishii, Masaki; Ishii, Kenichi; Miyaguchi, Wataru; Horie, Ryo; Inagaki, Yoshinori; Hamamoto, Hiroshi; Tatematsu, Ken-ichiro; Uchino, Keiro; Tamura, Toshiki; Sezutsu, Hideki; Sekimizu, Kazuhisa

    2014-12-12

    We established a transgenic silkworm strain expressing the human insulin receptor (hIR) using the GAL4/UAS system. Administration of human insulin to transgenic silkworms expressing hIR decreased hemolymph sugar levels and facilitated Akt phosphorylation in the fat body. The decrease in hemolymph sugar levels induced by injection of human insulin in the transgenic silkworms expressing hIR was blocked by co-injection of wortmannin, a phosphoinositide 3-kinase inhibitor. Administration of bovine insulin, an hIR ligand, also effectively decreased sugar levels in the transgenic silkworms. These findings indicate that functional hIRs that respond to human insulin were successfully induced in the transgenic silkworms. We propose that the humanized silkworm expressing hIR is useful for in vivo evaluation of the therapeutic activities of insulin receptor agonists.

  12. Galectins are human milk glycan receptors

    PubMed Central

    Noll, Alexander J; Gourdine, Jean-Philippe; Yu, Ying; Lasanajak, Yi; Smith, David F; Cummings, Richard D

    2016-01-01

    The biological recognition of human milk glycans (HMGs) is poorly understood. Because HMGs are rich in galactose we explored whether they might interact with human galectins, which bind galactose-containing glycans and are highly expressed in epithelial cells and other cell types. We screened a number of human galectins for their binding to HMGs on a shotgun glycan microarray consisting of 247 HMGs derived from human milk, as well as to a defined HMG microarray. Recombinant human galectins (hGal)-1, -3, -4, -7, -8 and -9 bound selectively to glycans, with each galectin recognizing a relatively unique binding motif; by contrast hGal-2 did not recognize HMGs, but did bind to the human blood group A Type 2 determinants on other microarrays. Unlike other galectins, hGal-7 preferentially bound to glycans expressing a terminal Type 1 (Galβ1-3GlcNAc) sequence, a motif that had eluded detection on non-HMG glycan microarrays. Interactions with HMGs were confirmed in a solution setting by isothermal titration microcalorimetry and hapten inhibition experiments. These results demonstrate that galectins selectively bind to HMGs and suggest the possibility that galectin–HMG interactions may play a role in infant immunity. PMID:26747425

  13. Role of Dopamine D2 Receptors in Human Reinforcement Learning

    PubMed Central

    Eisenegger, Christoph; Naef, Michael; Linssen, Anke; Clark, Luke; Gandamaneni, Praveen K; Müller, Ulrich; Robbins, Trevor W

    2014-01-01

    Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, whereas loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well. PMID:24713613

  14. Role of dopamine D2 receptors in human reinforcement learning.

    PubMed

    Eisenegger, Christoph; Naef, Michael; Linssen, Anke; Clark, Luke; Gandamaneni, Praveen K; Müller, Ulrich; Robbins, Trevor W

    2014-09-01

    Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, whereas loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well.

  15. Biotinylated human. beta. -endorphins as probes for the opioid receptor

    SciTech Connect

    Hochhaus, G.; Gibson, B.W.; Sadee, W.

    1988-01-05

    The reaction of human ..beta..-endorphin and biotinyl N-hydroxysuccinimide with or without spacer arm, afforded a series of products that were separated by high performance liquid chromatography (HPLC). Liquid secondary ion mass spectrometry of the biotinylated products and their tryptic digests produced abundant protonated molecular ions (MH/sup +/), which specified the number and location of biotinylation. Between 1 and 4 biotinyl residues were incorporated per human ..beta..-endorphin molecule, at Lys-9, -19, -24, -28, and -29, but not at the amino-terminal Try-1. Three HPLC fractions were isolated for receptor binding studies monobiotinylation of Lys-9, Lys-19, and a mixture of Lys-24, Lys-28, and Lys-29 derivatives. IC/sub 50/ values for binding to ..mu.. and delta opioid receptor sites were 3-8 times higher for monobiotinylated derivatives than for the parent human ..beta..-endorphin. Association with avidin decreased opioid receptor affinities for the C/sub 6/ spacer derivative biotinylated at position Lys-9, which is close to the (1-5) enkephalin receptor region. In contrast, avidin did not affect or even increased apparent affinities to ..mu.. and delta sites for derivatives biotinylated at the ..cap alpha..-helical part of the molecule (Lys-19, -24, -28, and -29). Biotinylated human ..beta..-endorphins also bound to low affinity nonopioid binding sites on NG-108-15 cells; however, affinities to these sites were considerably reduced when derivatives were bound to avidin. The ability of biotinylated human ..beta..-endorphin to cross-link the ..mu.. and delta opioid receptors to avidin allows application of the biotin-avidin system as a molecular probe of the opioid receptor.

  16. P2Y Receptors Sensitize Mouse and Human Colonic Nociceptors

    PubMed Central

    Hockley, James R. F.; Tranter, Michael M.; McGuire, Cian; Boundouki, George; Cibert-Goton, Vincent; Thaha, Mohamed A.; Blackshaw, L. Ashley; Michael, Gregory J.; Baker, Mark D.; Knowles, Charles H.; Winchester, Wendy J.

    2016-01-01

    Activation of visceral nociceptors by inflammatory mediators contributes to visceral hypersensitivity and abdominal pain associated with many gastrointestinal disorders. Purine and pyrimidine nucleotides (e.g., ATP and UTP) are strongly implicated in this process following their release from epithelial cells during mechanical stimulation of the gut, and from immune cells during inflammation. Actions of ATP are mediated through both ionotropic P2X receptors and metabotropic P2Y receptors. P2X receptor activation causes excitation of visceral afferents; however, the impact of P2Y receptor activation on visceral afferents innervating the gut is unclear. Here we investigate the effects of stimulating P2Y receptors in isolated mouse colonic sensory neurons, and visceral nociceptor fibers in mouse and human nerve-gut preparations. Additionally, we investigate the role of Nav1.9 in mediating murine responses. The application of UTP (P2Y2 and P2Y4 agonist) sensitized colonic sensory neurons by increasing action potential firing to current injection and depolarizing the membrane potential. The application of ADP (P2Y1, P2Y12, and P2Y13 agonist) also increased action potential firing, an effect blocked by the selective P2Y1 receptor antagonist MRS2500. UTP or ADP stimulated afferents, including mouse and human visceral nociceptors, in nerve-gut preparations. P2Y1 and P2Y2 transcripts were detected in 80% and 56% of retrogradely labeled colonic neurons, respectively. Nav1.9 transcripts colocalized in 86% of P2Y1-positive and 100% of P2Y2-positive colonic neurons, consistent with reduced afferent fiber responses to UTP and ADP in Nav1.9−/− mice. These data demonstrate that P2Y receptor activation stimulates mouse and human visceral nociceptors, highlighting P2Y-dependent mechanisms in the generation of visceral pain during gastrointestinal disease. SIGNIFICANCE STATEMENT Chronic visceral pain is a debilitating symptom of many gastrointestinal disorders. The activation of

  17. Adenovirus-receptor interaction with human lymphocytes.

    PubMed

    Mentel, R; Döpping, G; Wegner, U; Seidel, W; Liebermann, H; Döhner, L

    1997-03-01

    Lymphocytes play a key role in cell-mediated immunity and are host cells for several viral and bacterial pathogens. Their importance in adenovirus (Ad) infections is not yet fully understood. The initial event, the attachment of Ad to lymphocytes and their subsets, was examined using flow cytometry. The study included analysis of stimulated T cells in binding assays with FITC-labeled Ad fiber. The results confirm that native peripheral lymphocytes express very small amounts of Ad receptors. Stimulation with PHA and interleukin 2 induced the expression. The presence of Ad DNA as a sign of internalization in stimulated cells was demonstrated using the polymerase chain reaction. The findings suggest that lymphocytes after stimulation can turn into target cells for Ad. This is particularly important if there are indications for persistence of Ad, and in the case of immunocompromised patients severe, life-threatening diseases can develop.

  18. Dysfunctional platelet membrane receptors: from humans to mice.

    PubMed

    Ware, Jerry

    2004-09-01

    Insights into hemostasis and thrombosis have historically benefited from the astute diagnosis of human bleeding and thrombotic disorders followed by decades of careful biochemical characterization. This work has set the stage for the development of a number of mouse models of hemostasis and thrombosis generated by gene targeting strategies in the mouse genome. The utility of these models is the in depth analysis that can be performed on the precise molecular interactions that support hemostasis and thrombosis along with efficacy testing of various therapeutic strategies. Already the mouse has proven to be an excellent model of the processes that support hemostasis and thrombosis in the human vasculature. A brief summary of the salient phenotypes from knockout mice missing key platelet receptors is presented, including the glycoprotein (GP) Ib-IX-V and GP IIb/IIIa (alphaIIb/beta3) receptors; the collagen receptors, GP VI and alpha2/beta1; the protease activated receptors (PARs); and the purinergic receptors, P2Y(1) and P2Y(12). A few differences exist between mouse and human platelets and where appropriate those will be highlighted in this review. Concluding remarks focus on the importance of understanding the power and limitations of various in vitro, ex vivo and in vivo models currently being used and the impact of the mouse strain on the described platelet phenotype.

  19. Dysfunctional platelet membrane receptors: from humans to mice

    PubMed Central

    Ware, Jerry

    2010-01-01

    Summary Insights into hemostasis and thrombosis have historically benefited from the astute diagnosis of human bleeding and thrombotic disorders followed by decades of careful biochemical characterization. This work has set the stage for the development of a number of mouse models of hemostasis and thrombosis generated by gene targeting strategies in the mouse genome. The utility of these models is the in depth analysis that can be performed on the precise molecular interactions that support hemostasis and thrombosis along with efficacy testing of various therapeutic strategies. Already the mouse has proven to be an excellent model of the processes that support hemostasis and thrombosis in the human vasculature. A brief summary of the salient phenotypes from knockout mice missing key platelet receptors is presented, including the glycoprotein (GP) Ib-IX-V and GP IIb/IIIa (αIIb/β3) receptors; the collagen receptors, GPVI and α2βI; the protease activated receptors (PARs); and the purinergic receptors, P2Y1 and P2Y2. A few differences exist between mouse and human platelets and where appropriate those will be highlighted in this review. Concluding remarks focus on the importance of understanding the power and limitations of various in vitro, ex vivo and in vivo models currently being used and the impact of the mouse strain on the described platelet phenotype. PMID:15351843

  20. Overview of genetic analysis of human opioid receptors.

    PubMed

    Spampinato, Santi M

    2015-01-01

    The human μ-opioid receptor gene (OPRM1), due to its genetic and structural variation, has been a target of interest in several pharmacogenetic studies. The μ-opioid receptor (MOR), encoded by OPRM1, contributes to regulate the analgesic response to pain and also controls the rewarding effects of many drugs of abuse, including opioids, nicotine, and alcohol. Genetic polymorphisms of opioid receptors are candidates for the variability of clinical opioid effects. The non-synonymous polymorphism A118G of the OPRM1 has been repeatedly associated with the efficacy of opioid treatments for pain and various types of dependence. Genetic analysis of human opioid receptors has evidenced the presence of numerous polymorphisms either in exonic or in intronic sequences as well as the presence of synonymous coding variants that may have important effects on transcription, mRNA stability, and splicing, thus affecting gene function despite not directly disrupting any specific residue. Genotyping of opioid receptors is still in its infancy and a relevant progress in this field can be achieved by using advanced gene sequencing techniques described in this review that allow the researchers to obtain vast quantities of data on human genomes and transcriptomes in a brief period of time and with affordable costs.

  1. Increased EGF receptors on human squamous carcinoma cell lines.

    PubMed Central

    Cowley, G. P.; Smith, J. A.; Gusterson, B. A.

    1986-01-01

    Characterisation and quantitation of epidermal growth factor receptors (EGFR) have been carried out on eight human squamous carcinoma cell lines and the results compared with those from simian virus transformed keratinocytes and normal keratinocytes grown under similar conditions. All cells tested possess both high and low affinity receptors with dissociation constants ranging from 2.4 X 10(-10) M to 5.4 X 10(-9) M. When epidermal growth factor (EGF) binds to its receptor it is internalised and degraded and the receptor is down regulated. Malignant cells and virally transformed cells possess 5-50 times more EGF receptors than normal keratinocytes and one cell line LICR-LON-HN-5 possesses up to 1.4 X 10(7) receptors per cell, which is the highest number yet reported for a cell line. These results are discussed in the context of recent data that suggest that the increased expression of EGF receptors in epidermoid malignancies may be an important component of the malignant phenotype in these tumours. PMID:2420349

  2. The structural basis for receptor recognition of human interleukin-18

    PubMed Central

    Tsutsumi, Naotaka; Kimura, Takeshi; Arita, Kyohei; Ariyoshi, Mariko; Ohnishi, Hidenori; Yamamoto, Takahiro; Zuo, Xiaobing; Maenaka, Katsumi; Park, Enoch Y.; Kondo, Naomi; Shirakawa, Masahiro; Tochio, Hidehito; Kato, Zenichiro

    2014-01-01

    Interleukin (IL)-18 is a proinflammatory cytokine that belongs to the IL-1 family and plays an important role in inflammation. The uncontrolled release of this cytokine is associated with severe chronic inflammatory disease. IL-18 forms a signalling complex with the IL-18 receptor α (Rα) and β (Rβ) chains at the plasma membrane, which induces multiple inflammatory cytokines. Here, we present a crystal structure of human IL-18 bound to the two receptor extracellular domains. Generally, the receptors’ recognition mode for IL-18 is similar to IL-1β; however, certain notable differences were observed. The architecture of the IL-18 receptor second domain (D2) is unique among the other IL-1R family members, which presumably distinguishes them from the IL-1 receptors that exhibit a more promiscuous ligand recognition mode. The structures and associated biochemical and cellular data should aid in developing novel drugs to neutralize IL-18 activity. PMID:25500532

  3. The structural basis for receptor recognition of human interleukin-18

    SciTech Connect

    Tsutsumi, Naotaka; Kimura, Takeshi; Arita, Kyohei; Ariyoshi, Mariko; Ohnishi, Hidenori; Yamamoto, Takahiro; Zuo, Xiaobing; Maenaka, Katsumi; Park, Enoch Y.; Kondo, Naomi; Shirakawa, Masahiro; Tochio, Hidehito; Kato, Zenichiro

    2014-12-15

    Interleukin (IL)-18 is a proinflammatory cytokine that belongs to the IL-1 family and plays an important role in inflammation. The uncontrolled release of this cytokine is associated with severe chronic inflammatory disease. IL-18 forms a signalling complex with the IL-18 receptor α (Rα) and β (Rβ) chains at the plasma membrane, which induces multiple inflammatory cytokines. Here, we present a crystal structure of human IL-18 bound to the two receptor extracellular domains. Generally, the receptors’ recognition mode for IL-18 is similar to IL-1β; however, certain notable differences were observed. The architecture of the IL-18 receptor second domain (D2) is unique among the other IL-1R family members, which presumably distinguishes them from the IL-1 receptors that exhibit a more promiscuous ligand recognition mode. The structures and associated biochemical and cellular data should aid in developing novel drugs to neutralize IL-8 activity.

  4. Pathogen receptor discovery with a microfluidic human membrane protein array.

    PubMed

    Glick, Yair; Ben-Ari, Ya'ara; Drayman, Nir; Pellach, Michal; Neveu, Gregory; Boonyaratanakornkit, Jim; Avrahami, Dorit; Einav, Shirit; Oppenheim, Ariella; Gerber, Doron

    2016-04-19

    The discovery of how a pathogen invades a cell requires one to determine which host cell receptors are exploited. This determination is a challenging problem because the receptor is invariably a membrane protein, which represents an Achilles heel in proteomics. We have developed a universal platform for high-throughput expression and interaction studies of membrane proteins by creating a microfluidic-based comprehensive human membrane protein array (MPA). The MPA is, to our knowledge, the first of its kind and offers a powerful alternative to conventional proteomics by enabling the simultaneous study of 2,100 membrane proteins. We characterized direct interactions of a whole nonenveloped virus (simian virus 40), as well as those of the hepatitis delta enveloped virus large form antigen, with candidate host receptors expressed on the MPA. Selected newly discovered membrane protein-pathogen interactions were validated by conventional methods, demonstrating that the MPA is an important tool for cellular receptor discovery and for understanding pathogen tropism.

  5. A model of the human M2 muscarinic acetylcholine receptor

    NASA Astrophysics Data System (ADS)

    Jöhren, Kirstin; Höltje, Hans-Dieter

    2002-11-01

    The M2 muscarinic acetylcholine receptor belongs to the family of rhodopsin like G-Protein Coupled Receptors. This subtype of muscarinic receptors is of special interest because it bears, aside from an orthosteric binding site, also an allosteric binding site. Based on the X-ray structure of bovine rhodopsin a complete homology model of the human M2 receptor was developed. For the orthosteric binding site point mutations and binding studies with different agonists and antagonists are available. This knowledge was utilized for an initial verification of the M2 model. Allosteric modulation of activity is mediated by structurally different ligands such as gallamine, caracurine V salts or W84 (a hexamethonium-derivative). Caracurine V derivatives with different affinities to M2 were docked using GRID-fields. Subsequent molecular dynamics simulations yielded different binding energies based on diverse electrostatic and lipophilic interactions. The calculated affinities are in good agreement to experimentally determined affinities.

  6. The structural basis for receptor recognition of human interleukin-18

    DOE PAGES

    Tsutsumi, Naotaka; Kimura, Takeshi; Arita, Kyohei; ...

    2014-12-15

    Interleukin (IL)-18 is a proinflammatory cytokine that belongs to the IL-1 family and plays an important role in inflammation. The uncontrolled release of this cytokine is associated with severe chronic inflammatory disease. IL-18 forms a signalling complex with the IL-18 receptor α (Rα) and β (Rβ) chains at the plasma membrane, which induces multiple inflammatory cytokines. Here, we present a crystal structure of human IL-18 bound to the two receptor extracellular domains. Generally, the receptors’ recognition mode for IL-18 is similar to IL-1β; however, certain notable differences were observed. The architecture of the IL-18 receptor second domain (D2) is uniquemore » among the other IL-1R family members, which presumably distinguishes them from the IL-1 receptors that exhibit a more promiscuous ligand recognition mode. The structures and associated biochemical and cellular data should aid in developing novel drugs to neutralize IL-8 activity.« less

  7. Kaempferol suppresses lipid accumulation in macrophages through the downregulation of cluster of differentiation 36 and the upregulation of scavenger receptor class B type I and ATP-binding cassette transporters A1 and G1.

    PubMed

    Li, Xiu-Ying; Kong, Ling-Xi; Li, Juan; He, Hai-Xia; Zhou, Yuan-Da

    2013-02-01

    The accumulation of foam cells in atherosclerotic lesions is a hallmark of early-stage atherosclerosis. Kaempferol has been shown to inhibit oxidized low-density lipoprotein (oxLDL) uptake by macrophages; however, the underlying molecular mechanisms are not yet fully investigated. In this study, we shown that treatment with kaempferol markedly suppresses oxLDL-induced macrophage foam cell formation, which occurs due to a decrease in lipid accumulation and an increase in cholesterol efflux from THP-1-derived macrophages. Additionally, the kaempferol treatment of macrophages led to the downregulation of cluster of differentiation 36 (CD36) protein levels, the upregulation of ATP-binding cassette (ABC) transporter A1 (ABCA1), scavenger receptor class B type I (SR-BI) and ABCG1 protein levels, while no effects on scavenger receptor A (SR-A) expression were observed. Kaempferol had similar effects on the mRNA and protein expression of ABCA1, SR-BI, SR-A, CD36 and ABCG1. The reduced CD36 expression following kaempferol treatment involved the inhibition of c-Jun-activator protein-1 (AP-1) nuclear translocation. The inhibition of AP-1 using the inhibitor, SP600125, confirmed this involvement, as the AP-1 inhibition significantly augmented the kaempferol-induced reduction in CD36 expression. Accordingly, the kaempferol-mediated suppression of lipid accumulation in macrophages was also augmented by SP600125. The increased expression of ABCA1, SR-BI and ABCG1 following kaempferol treatment was accompanied by the enhanced protein expression of heme oxygenase-1 (HO-1). This increase was reversed following the knockdown of the HO-1 gene using small hairpin RNA (shRNA). Moreover, the kaempferol-mediated attenuation of lipid accumulation and the promotion of cholesterol efflux was also inhibited by HO-1 shRNA. In conclusion, the c-Jun-AP‑1-dependent downregulation of CD36 and the HO-1-dependent upregulation of ABCG1, SR-BI and ABCA1 may mediate the beneficial effects of

  8. Structure of the human histamine H1 receptor gene.

    PubMed Central

    De Backer, M D; Loonen, I; Verhasselt, P; Neefs, J M; Luyten, W H

    1998-01-01

    Histamine H1 receptor expression has been reported to change in disorders such as allergic rhinitis, autoimmune myocarditis, rheumatoid arthritis and atherosclerosis. Here we report the isolation and characterization of genomic clones containing the 5' flanking (regulatory) region of the human histamine H1 receptor gene. An intron of approx. 5.8 kb was identified in the 5' untranslated region, which suggests that an entire subfamily of G-protein-coupled receptors may contain an intron immediately upstream of the start codon. The transcription initiation site was mapped by 5' rapid amplification of cDNA ends to a region 6.2 kb upstream of the start codon. Immediately upstream of the transcription start site a fragment of 1.85 kb was identified that showed promoter activity when placed upstream of a luciferase reporter gene and transiently transfected into cells expressing the histamine H1 receptor. The promoter sequence shares a number of characteristics with the promoter sequences of other G-protein-coupled receptor encoding genes, including binding sites for several transcription factors, and the absence of TATA and CAAT sequences at the appropriate locations. The promoter sequence described here differs from that reported previously [Fukui, Fujimoto, Mizuguchi, Sakamoto, Horio, Takai, Yamada and Ito (1994) Biochem. Biophys. Res. Commun. 201, 894-901] because the reported genomic clone was chimaeric. Furthermore our study provides evidence that the 3' untranslated region of the H1 receptor mRNA is much longer than previously accepted. Together, these findings provide a complete view of the structure of the human histamine H1 receptor gene. Both the coding region of the H1 receptor gene and its promoter region were independently mapped to chromosome 3p25. PMID:9794809

  9. Production of a bioengineered G-protein coupled receptor of human formyl peptide receptor 3.

    PubMed

    Wang, Xiaoqiang; Zhang, Shuguang

    2011-01-01

    G-protein coupled receptors (GPCRs) participate in a wide range of vital regulations of our physiological actions. They are also of pharmaceutical importance and have become many therapeutic targets for a number of disorders and diseases. Purified GPCR-based approaches including structural study and novel biophysical and biochemical function analyses are increasingly being used in GPCR-directed drug discovery. Before these approaches become routine, however, several hurdles need to be overcome; they include overexpression, solubilization, and purification of large quantities of functional and stable receptors on a regular basis. Here we report milligram production of a human formyl peptide receptor 3 (FPR3). FPR3 comprises a functionally distinct GPCR subfamily that is involved in leukocyte chemotaxis and activation. The bioengineered FPR3 was overexpressed in stable tetracycline-inducible mammalian cell lines (HEK293S). After a systematic detergent screening, fos-choline-14 (FC-14) was selected for subsequent solubilization and purification processes. A two-step purification method, immunoaffinity using anti-rho-tag monoclonal antibody 1D4 and gel filtration, was used to purify the receptors to near homogeneity. Immunofluorescence analysis showed that expressed FPR3 was predominantly displayed on cellular membrane. Secondary structural analysis using circular dichroism showed that the purified FPR3 receptor was correctly folded with >50% α-helix, which is similar to other known GPCR secondary structures. Our method can readily produce milligram quantities of human FPR3, which would facilitate in developing human FPR as therapeutic drug targets.

  10. Crystal structure of human interferon-γ receptor 2 reveals the structural basis for receptor specificity

    PubMed Central

    Mikulecký, Pavel; Zahradník, Jirí; Kolenko, Petr; Černý, Jiří; Charnavets, Tatsiana; Kolářová, Lucie; Nečasová, Iva; Pham, Phuong Ngoc; Schneider, Bohdan

    2016-01-01

    Interferon-γ receptor 2 is a cell-surface receptor that is required for interferon-γ signalling and therefore plays a critical immunoregulatory role in innate and adaptive immunity against viral and also bacterial and protozoal infections. A crystal structure of the extracellular part of human interferon-γ receptor 2 (IFNγR2) was solved by molecular replacement at 1.8 Å resolution. Similar to other class 2 receptors, IFNγR2 has two fibronectin type III domains. The characteristic structural features of IFNγR2 are concentrated in its N-terminal domain: an extensive π–cation motif of stacked residues KWRWRH, a NAG–W–NAG sandwich (where NAG stands for N-acetyl-d-glucosamine) and finally a helix formed by residues 78–85, which is unique among class 2 receptors. Mass spectrometry and mutational analyses showed the importance of N-linked glycosylation to the stability of the protein and confirmed the presence of two disulfide bonds. Structure-based bioinformatic analysis revealed independent evolutionary behaviour of both receptor domains and, together with multiple sequence alignment, identified putative binding sites for interferon-γ and receptor 1, the ligands of IFNγR2. PMID:27599734

  11. Structural Basis for Apelin Control of the Human Apelin Receptor.

    PubMed

    Ma, Yingli; Yue, Yang; Ma, Yanbin; Zhang, Qing; Zhou, Qingtong; Song, Yunpeng; Shen, Yuqing; Li, Xun; Ma, Xiaochuan; Li, Chao; Hanson, Michael A; Han, Gye Won; Sickmier, E Allen; Swaminath, Gayathri; Zhao, Suwen; Stevens, Raymond C; Hu, Liaoyuan A; Zhong, Wenge; Zhang, Mingqiang; Xu, Fei

    2017-06-06

    Apelin receptor (APJR) is a key regulator of human cardiovascular function and is activated by two different endogenous peptide ligands, apelin and Elabela, each with different isoforms diversified by length and amino acid sequence. Here we report the 2.6-Å resolution crystal structure of human APJR in complex with a designed 17-amino-acid apelin mimetic peptide agonist. The structure reveals that the peptide agonist adopts a lactam constrained curved two-site ligand binding mode. Combined with mutation analysis and molecular dynamics simulations with apelin-13 binding to the wild-type APJR, this structure provides a mechanistic understanding of apelin recognition and binding specificity. Comparison of this structure with that of other peptide receptors suggests that endogenous peptide ligands with a high degree of conformational flexibility may bind and modulate the receptors via a similar two-site binding mechanism. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Estradiol via estrogen receptor beta influences ROS levels through the transcriptional regulation of SIRT3 in human seminoma TCam-2 cells.

    PubMed

    Panza, Salvatore; Santoro, Marta; De Amicis, Francesca; Morelli, Catia; Passarelli, Valentina; D'Aquila, Patrizia; Giordano, Francesca; Cione, Erika; Passarino, Giuseppe; Bellizzi, Dina; Aquila, Saveria

    2017-05-01

    Human testis, gonocytes, and adult germ cells mainly express estrogen receptor beta, and estrogen receptor beta loss is associated with advanced tumor stage; however, the molecular mechanisms of estrogen receptor beta-protective effects are still to be defined. Herein, we provide evidence that in human seminoma TCam-2 cells, E2 through estrogen receptor beta upregulates the mitochondrial deacetylase sirtuin-3 at protein and messenger RNA levels. Specifically, E2 increases sirtuin-3 expression through a transcriptional mechanism due to the occupancy of sirtuin-3 promoter by estrogen receptor beta, together with the transcription factor Sp1 as evidenced by Chip reChIp assay. This complex binds to a GC cluster located between -128 bp/+1 bp and is fundamental for E2 effects, as demonstrated by Sp1 small interfering RNA studies. Beside, after 24 h, E2 stimulus significantly increased activities of superoxide dismutase and catalase to scavenge reactive oxygen species produced by 30 min of E2 stimulus. In summary, this article indicates a novel functional interplay between estrogen receptor beta and sirtuin-3 counteracting reactive oxygen species production in TCam-2 cells. Our findings thus show that an important tumor-suppressive pathway through estrogen receptor beta is target of E2, actually proposing a distinctive protecting action against seminoma. Future studies may lead to additional strategies for the current therapy of seminoma.

  13. Crystal Structure of the Human Laminin Receptor Precursor

    SciTech Connect

    Jamieson,K.; Wu, J.; Hubbard, S.; Meruelo, D.

    2008-01-01

    The human laminin receptor (LamR) interacts with many ligands, including laminin, prions, Sindbis virus, and the polyphenol (-)-epigallocatechin-3-gallate (EGCG), and has been implicated in a number of diseases. LamR is overexpressed on tumor cells, and targeting LamR elicits anti-cancer effects. Here, we report the crystal structure of human LamR, which provides insights into its function and should facilitate the design of novel therapeutics targeting LamR.

  14. Estrogen Receptor Mutants/Variants in Human Breast Cancer.

    DTIC Science & Technology

    1997-12-01

    Recherche Louis- Charles Simard, Montreal, Canada. Four nor- mal human breast tissues from reduction mammoplasties of pre- menopausal women were obtained...to hormone resistance. Cancer Res 1990; 50: 6208-17. 22. Karnik PS, Kulkarni S, Lui XP, Budd GT, Bukowski RM. Estrogen receptor mutations in

  15. Functional expression of purinergic P2 receptors and transient receptor potential channels by the human urothelium.

    PubMed

    Shabir, Saqib; Cross, William; Kirkwood, Lisa A; Pearson, Joanna F; Appleby, Peter A; Walker, Dawn; Eardley, Ian; Southgate, Jennifer

    2013-08-01

    In addition to its role as a physical barrier, the urothelium is considered to play an active role in mechanosensation. A key mechanism is the release of transient mediators that activate purinergic P2 receptors and transient receptor potential (TRP) channels to effect changes in intracellular Ca²⁺. Despite the implied importance of these receptors and channels in urothelial tissue homeostasis and dysfunctional bladder disease, little is known about their functional expression by the human urothelium. To evaluate the expression and function of P2X and P2Y receptors and TRP channels, the human ureter and bladder were used to separate urothelial and stromal tissues for RNA isolation and cell culture. RT-PCR using stringently designed primer sets was used to establish which P2 and TRP species were expressed at the transcript level, and selective agonists/antagonists were used to confirm functional expression by monitoring changes in intracellular Ca²⁺ and in a scratch repair assay. The results confirmed the functional expression of P2Y₄ receptors and excluded nonexpressed receptors/channels (P2X₁, P2X₃, P2X₆, P2Y₆, P2Y₁₁, TRPV5, and TRPM8), while a dearth of specific agonists confounded the functional validation of expressed P2X₂, P2X₄, P2Y₁, P2Y₂, TRPV2, TRPV3, TRPV6 and TRPM7 receptors/channels. Although a conventional response was elicited in control stromal-derived cells, the urothelial cell response to well-characterized TRPV1 and TRPV4 agonists/antagonists revealed unexpected anomalies. In addition, agonists that invoked an increase in intracellular Ca²⁺ promoted urothelial scratch repair, presumably through the release of ATP. The study raises important questions about the ligand selectivity of receptor/channel targets expressed by the urothelium. These pathways are important in urothelial tissue homeostasis, and this opens the possibility of selective drug targeting.

  16. Human articular chondrocytes express functional leukotriene B4 receptors

    PubMed Central

    Hansen, Ann Kristin; Indrevik, Jill-Tove; Figenschau, Yngve; Martinez-Zubiaurre, Inigo; Sveinbjörnsson, Baldur

    2015-01-01

    Leukotriene B4 (LTB4) is a potent chemoattractant associated with the development of osteoarthritis (OA), while its receptors BLT1 and BLT2 have been found in synovium and subchondral bone. In this study, we have investigated whether these receptors are also expressed by human cartilage cells and their potential effects on cartilage cells. The expression of LTB4 receptors in native tissue and cultured cells was assessed by immunohistochemistry, immunocytochemistry, polymerase chain reaction (PCR) and electron microscopy. The functional significance of the LTB4 receptor expression was studied by Western blotting, using phospho-specific antibodies in the presence or absence of receptor antagonists. In further studies, the secretion of pro-inflammatory cytokines, growth factors and metalloproteinases by LTB4-stimulated chondrocytes was measured by multiplex protein assays. The effects of LTB4 in cartilage signature gene expression in cultured cells were assessed by quantitative PCR, whereas the LTB4-promoted matrix synthesis was determined using 3D pellet cultures. Both receptors were present in cultured chondrocytes, as was confirmed by immunolabelling and PCR. The relative quantification by PCR demonstrated a higher expression of the receptors in cells from healthy joints compared with OA cases. The stimulation of cultured chondrocytes with LTB4 resulted in a phosphorylation of downstream transcription factor Erk 1/2, which was reduced after blocking BLT1 signalling. No alteration in the secretion of cytokine and metalloproteinases was recorded after challenging cultured cells with LTB4; likewise, cartilage matrix gene expression and 3D tissue synthesis were unaffected. Chondrocytes express BLT1 and BLT2 receptors, and LTB4 activates the downstream Erk 1/2 pathway by engaging the high-affinity receptor BLT1. However, any putative role in cartilage biology could not be revealed, and remains to be clarified. PMID:25677035

  17. Interaction of progestins with steroid receptors in human uterus

    PubMed Central

    Kasid, Attan; Buckshee, Kamal; Hingorani, Veera; Laumas, Kesho R.

    1978-01-01

    Norethindrone (17β-hydroxy-19-nor-17α-pregn-4-en-20-yn-3-one) and norethindrone acetate (17β-acetoxy-19-nor-17α-pregn-4-en-20-yn-3-one) interfered to a varying degree, by competitive inhibition, with the binding of progesterone and oestradiol to respective cytoplasmic receptors in the human uterus. Progesterone binding to 4S macromolecule was saturable and co-specific for progestins. Competitors like norgestrel (17β-hydroxy-18-methyl-19-nor-17α-pregn-4-en-20-yn-3-one), 19-norprogesterone, medroxyprogesterone acetate (17α-acetoxy-6α-methylpregn-4-ene-3,20-dione) and compound R5020 (17,21-dimethyl-19-norpregna-4,9-diene-3,20-dione) possessed higher binding affinities for the progestin receptor. The dissociation constant (Kd) for the progesterone–receptor interaction was 0.6–1.6nm and the receptor concentration ranged between 6600 and 8200 sites/cell. Norethindrone and norethindrone acetate competed for the progesterone receptor with inhibition constants (Ki) of 6.8 and 72nm respectively. Gradient displacement and competitive-receptor assays indicated that norethindrone acetate-binding affinity for progestin receptor was approximately one-tenth that of norethindrone and progesterone. The progestins also inhibited oestradiol binding to 4.6S oestrogenic receptor by 8–12%, involving interaction at the oestradiol-binding site with a calculated Ki value of 0.5–0.8μm. The competitive interaction of progestins with steroid receptors may be of putative importance in explaining the progestin action at the target site. PMID:743257

  18. Desensitization of oxytocin receptors in human myometrium.

    PubMed

    Phaneuf, S; Asbóth, G; Carrasco, M P; Liñares, B R; Kimura, T; Harris, A; Bernal, A L

    1998-01-01

    In the present study, we investigated the possible mechanisms by which oxytocin might regulate oxytocin receptor (OTR) density. Exposure of cultured myometrial cells to oxytocin for a prolonged period caused desensitization: the steady-state level of oxytocin binding was 210 x 10(3) binding sites/cell, but this was time-dependently reduced to 20.1 x 10(3) sites/cell by exposing the cells to oxytocin for up to 20 h. In contrast, Western blotting data showed that the total amount of OTR protein was not affected by oxytocin treatment for up to 24 h. Flow cytometry experiments demonstrated that OTRs were not internalized during this treatment. However, RNase protection assays and Northern analysis showed that in cultured myometrial cells OTR mRNA was reduced by oxytocin treatment to reach a new low steady-state concentration. Analysis of this mRNA in myometrial biopsies from 17 patients undergoing emergency Caesarean section showed how it decreased with advancing labour. Samples obtained after 12 h of labour contained approximately 50 times less OTR mRNA than samples obtained from patients in labour for less than 12 h. We speculate that this decrease in OTR mRNA represents in-vivo OTR desensitization.

  19. Cryogenic Propellant Scavenging

    NASA Technical Reports Server (NTRS)

    Louie, B.; Kemp, N. J.; Daney, D. E.

    1985-01-01

    A detailed description of a computer model that has been developed for assessing the feasibility of low g cryogen propellant scavenging from the space shuttle External Tank (ET) is given. Either pump-assisted or pressure-induced propellant transfer may be selected. The program will accept a wide range of input variables, including the fuel to be transferred (LOX or LH2), heat leaks, tank temperatures, and piping and equipment specifications. The model has been parametrically analyzed to determine initial design specification for the system.

  20. Capturing One of the Human Gut Microbiome’s Most Wanted: Reconstructing the Genome of a Novel Butyrate-Producing, Clostridial Scavenger from Metagenomic Sequence Data

    PubMed Central

    Jeraldo, Patricio; Hernandez, Alvaro; Nielsen, Henrik B.; Chen, Xianfeng; White, Bryan A.; Goldenfeld, Nigel; Nelson, Heidi; Alhquist, David; Boardman, Lisa; Chia, Nicholas

    2016-01-01

    The role of the microbiome in health and disease is attracting great attention, yet we still know little about some of the most prevalent microorganisms inside our bodies. Several years ago, Human Microbiome Project (HMP) researchers generated a list of “most wanted” taxa: bacteria both prevalent among healthy volunteers and distantly related to any sequenced organisms. Unfortunately, the challenge of assembling high-quality genomes from a tangle of metagenomic reads has slowed progress in learning about these uncultured bacteria. Here, we describe how recent advances in sequencing and analysis allowed us to assemble “most wanted” genomes from metagenomic data collected from four stool samples. Using a combination of both de novo and guided assembly methods, we assembled and binned over 100 genomes from an initial data set of over 1,300 Gbp. One of these genome bins, which met HMP’s criteria for a “most wanted” taxa, contained three essentially complete genomes belonging to a previously uncultivated species. This species is most closely related to Eubacterium desmolans and the clostridial cluster IV/Clostridium leptum subgroup species Butyricicoccus pullicaecorum (71–76% average nucleotide identity). Gene function analysis indicates that the species is an obligate anaerobe, forms spores, and produces the anti-inflammatory short-chain fatty acids acetate and butyrate. It also appears to take up metabolically costly molecules such as cobalamin, methionine, and branch-chained amino acids from the environment, and to lack virulence genes. Thus, the evidence is consistent with a secondary degrader that occupies a host-dependent, nutrient-scavenging niche within the gut; its ability to produce butyrate, which is thought to play an anti-inflammatory role, makes it intriguing for the study of diseases such as colon cancer and inflammatory bowel disease. In conclusion, we have assembled essentially complete genomes from stool metagenomic data, yielding

  1. Glucocorticoid receptor activation and inactivation in cultured human lymphocytes.

    PubMed

    Wheeler, R H; Leach, K L; La Forest, A C; O'Toole, T E; Wagner, R; Pratt, W B

    1981-01-10

    Although glucocorticoids are not cytolytic for and do not inhibit the growth of the IM-9 line of cultured human lymphoblasts, these cells have a high steroid-binding capacity. We have used IM-9 cells in order to examine whether unoccupied glucocorticoid receptors are inactivated and activated in intact cells. when IM-9 cells are incubated in glucose-free medium in a nitrogen atmosphere, both their ability to bind triamcinolone acetonide and their ATP levels decline and, when glucose and oxygen are reintroduced, ATP levels and receptor activity return. The specific glucocorticoid-binding activity of cytosol prepared from cells exposed to various degrees of energy limitation is directly correlated with the ATP content. Receptor activation in intact cells is rapid and independent of protein synthesis. Cytosol prepared from inactivated cells cannot be activated by addition of ATP. The inactivation of glucocorticoid receptors that occurs when cytosol from normal IM-9 cells is incubated at 25 degrees C is inhibited by molybdate, vanadate, fluoride, ATP, and several other nucleotides. The experiments with intact human lymphoblasts suggest that assays of specific glucocorticoid-binding capacity do not necessarily reflect the cellular content of receptor protein.

  2. Characterization of the human platelet Fc sub. gamma. receptor

    SciTech Connect

    King, M.

    1988-01-01

    Thrombocytopenia is often associated with immune complex disease and may in part be due to the interaction of circulating (IgG) immune complexes with an Fc{sub {gamma}} receptor on the platelet surface. Characterization of the immune complex-platelet interaction should provide for a better understanding of the pathophysiology of immune thrombocytpenia. To this end, a ligand binding assay, employing {sup 125}I-IgG trimer, was established. Receptor expression was determined by measuring the saturable binding of radiolabeled trimer to platelets at equilibrium. Normal human platelets were observed to express 8559 {plus minus} 852 binding sites for IgG trimer with a Kd of 12.5 {plus minus} 1.7 {times} 10{sup {minus}8} M. Binding of IgG trimer to human platelets was blocked following preincubation of the cells with an anti-Fc{sub {gamma}}RII monoclonal antibody. Furthermore, this binding was ionic-strength dependent but was unaffected by the presence of Mg{sup ++} or cytochalasin B. Platelet Fc{sub {gamma}} receptor modulation was examined by assessing the effects of various physiologic and pharmacologic on the ability of platelets to bind IgG trimer. Platelet Fc{sub {gamma}} receptor expression was not affected by thrombin, ADP, or {gamma}-interferon. However, in 7/12 normal donors, treatment of platelets with dexamethasone resulted in a decrease in the number of Fc{sub {gamma}} receptors expressed.

  3. The role of GABAB receptors in human reinforcement learning.

    PubMed

    Ort, Andres; Kometer, Michael; Rohde, Judith; Seifritz, Erich; Vollenweider, Franz X

    2014-10-01

    Behavioral evidence from human studies suggests that the γ-aminobutyric acid type B receptor (GABAB receptor) agonist baclofen modulates reinforcement learning and reduces craving in patients with addiction spectrum disorders. However, in contrast to the well established role of dopamine in reinforcement learning, the mechanisms by which the GABAB receptor influences reinforcement learning in humans remain completely unknown. To further elucidate this issue, a cross-over, double-blind, placebo-controlled study was performed in healthy human subjects (N=15) to test the effects of baclofen (20 and 50mg p.o.) on probabilistic reinforcement learning. Outcomes were the feedback-induced P2 component of the event-related potential, the feedback-related negativity, and the P300 component of the event-related potential. Baclofen produced a reduction of P2 amplitude over the course of the experiment, but did not modulate the feedback-related negativity. Furthermore, there was a trend towards increased learning after baclofen administration relative to placebo over the course of the experiment. The present results extend previous theories of reinforcement learning, which focus on the importance of mesolimbic dopamine signaling, and indicate that stimulation of cortical GABAB receptors in a fronto-parietal network leads to better attentional allocation in reinforcement learning. This observation is a first step in our understanding of how baclofen may improve reinforcement learning in healthy subjects. Further studies with bigger sample sizes are needed to corroborate this conclusion and furthermore, test this effect in patients with addiction spectrum disorder.

  4. Antagonistic action of pitrazepin on human and rat GABAA receptors

    PubMed Central

    Demuro, Angelo; Martinez-Torres, Ataulfo; Francesconi, Walter; Miledi, Ricardo

    1999-01-01

    Pitrazepin, 3-(piperazinyl-1)-9H-dibenz(c,f) triazolo(4,5-a)azepin is a piperazine antagonist of GABA in a variety of electrophysiological and in vitro binding studies involving GABA and glycine receptors. In the present study we have investigated the effects of pitrazepin, and the GABAA antagonist bicuculline, on membrane currents elicited by GABA in Xenopus oocytes injected with rat cerebral cortex mRNA or cDNAs encoding α1β2 or α1β2γ2S human GABAA receptor subunits.The three types of GABAA receptors expressed were reversibly antagonized by bicuculline and pitrazepin in a concentration-dependent manner. GABA dose-current response curves for the three types of receptors were shifted to the right, in a parallel manner, by increasing concentrations of pitrazepin.Schild analyses gave pA2 values of 6.42±0.62, n=4, 6.41±1.2, n=5 and 6.21±1.24, n=6, in oocytes expressing rat cerebral cortex, α1β2 or α1β2γ2S human GABAA receptors respectively (values are given as means±s.e.mean), and the Hill coefficients were all close to unity. All this is consistent with the notion that pitrazepin acts as a competitive antagonist of these GABAA receptors; and that their antagonism by pitrazepin is not strongly dependent on the subunit composition of the receptors here studied.Since pitrazepin has been reported to act also at the benzodiazepine binding site, we studied the effect of the benzodiazepine antagonist Ro 15-1788 (flumazenil) on the inhibition of α1β2γ2S receptors by pitrazepin. Co-application of Ro 15-1788 did not alter the inhibiting effect of pitrazepin. Moreover, pitrazepin did not antagonize the potentiation of GABA-currents by flunitrazepam. All this suggests that pitrazepin does not affect the GABA receptor-chloride channel by interacting with the benzodiazepine receptor site. PMID:10369456

  5. Ionotropic GABA and Glutamate Receptor Mutations and Human Neurologic Diseases

    PubMed Central

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

    2015-01-01

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

  6. Cloning and expression of the human vasoactive intestinal peptide receptor.

    PubMed Central

    Sreedharan, S P; Robichon, A; Peterson, K E; Goetzl, E J

    1991-01-01

    Vasoactive intestinal peptide (VIP) is a neuroendocrine mediator found in the central and peripheral nervous system. Distinct subsets of neural, respiratory, gastrointestinal, and immune cells bear specific high-affinity receptors for VIP, which are associated with a guanine nucleotide-binding (G) protein capable of activating adenylate cyclase. A cDNA clone (GPRN1) encoding the human VIP receptor was identified in libraries prepared from the Nalm 6 line of leukemic pre-B lymphoblasts and the HT-29 line of colon carcinoma cells. The deduced 362-amino acid polypeptide sequence encoded by GPRN1 shares a seven-transmembrane-segment hydropathicity profile with other G protein-coupled receptors. Northern blot analyses identified a 2.7-kilobase transcript of the VIP receptor in Nalm 6 and HT-29 cells as well as in tissues from rat brain, colon, heart, lung, kidney, spleen, and small intestine. COS-6 cells transfected with GPRN1 bound 125I-labeled VIP specifically with a dissociation constant (Kd) of 2.5 nM. VIP--and less effectively secretin, peptide histidine isoleucine (PHI), and glucagon competitively displaced bound 125I-VIP from transfected COS-6 cells, with potencies in the order VIP greater than secretin = PHI much greater than glucagon. VIP stimulated adenylate cyclase activity in stably transfected Chinese hamster ovary K1 cells, inducing a 3-fold increase in the intracellular level of cAMP. When the antisense orientation of the VIP receptor clone was introduced into HT-29 cells, there was a 50% suppression of the specific binding of 125I-VIP and of the VIP-induced increase in cAMP level, relative to untransfected cells. The VIP receptor cloned exhibits less than or equal to 24% homology with other receptors in the same superfamily and thus represents a subset of G protein-coupled receptors for peptide ligands. Images PMID:1675791

  7. Pharmacological reduction of brain edema induced by intracarotid infusion of protamine sulphate: a comparison between a free radical scavenger and an AMPA receptor antagonist.

    PubMed

    Johansson, B B; Westergren, I

    1994-01-01

    The blood-brain barrier (BBB) of rats was opened by infusing 10 mg protamine sulphate (200 microliters in 30 s) into the right internal carotid artery. Ten minutes later, tirilazad, a 21-aminosteroid (3 mg/kg): NBQX, an AMPA receptor antagonist (5 mg/kg); or dixyrazine, a phenotiazine derivate (10 mg/kg), was administered intravenously and the rats were killed 2 h after protamine infusion. Brain specific gravity was determined in the frontal, parietal and occipital cortex and in the striatum. In separate experiments, serum albumin content was determined in the brain of rats by immunoelectrophoresis 2 h after protamine infusion with or without tirilazad pretreatment. Specific gravity was significantly higher in all of the studied brain regions in rats given tirilazad or NBQX than in those given vehicle or dixyrazine (p < 0.001). A combination of tirilazad and NBQX was significantly more efficient than either drug alone in reducing edema in the occipital cortex (p < 0.05) and more efficient than NBQX alone in the frontal and parietal cortex (p < 0.05). None of the drugs reduced the albumin content in CSF; in addition, tirilazad failed to reduce albumin extravasation in the brain and CSF when given before protamine infusion. We conclude that the anti-edematous effect of tirilazad and NBQX is related to cellular events within the brain and not to a reduction of leakage over the BBB.

  8. Update: the search for the human cough receptor.

    PubMed

    McGarvey, Lorcan

    2014-08-01

    Despite the best efforts of basic and applied science, the identity of the human "cough receptor" remains elusive. The attraction of identifying a single "catch all" cough receptor is obvious, although such an objective is unlikely to be realised given the concept of "cough hypersensitivity," which is now considered the most clinically relevant description of what underlies problem coughing. One means of progressing this area is to join the thinking and experimental effort of basic science and clinical research in an effective manner. Some of the best examples of cooperative and translational research over the years together with an update on the most recent work will be discussed in this article.

  9. Linking Functional Domains of the Human Insulin Receptor with the Bacterial Aspartate Receptor

    NASA Astrophysics Data System (ADS)

    Ellis, Leland; Morgan, David O.; Koshland, Daniel E.; Clauser, Eric; Moe, Gregory R.; Bollag, Gideon; Roth, Richard A.; Rutter, William J.

    1986-11-01

    A hybrid receptor has been constructed that is composed of the extracellular domain of the human insulin receptor fused to the transmembrane and cytoplasmic domains of the bacterial aspartate chemoreceptor. This hybrid protein can be expressed in rodent (CHO) cells and displays several functional features comparable to wild-type insulin receptor. It is localized to the cell surface, binds insulin with high affinity, forms oligomers, and is recognized by conformation-specific monoclonal antibodies. Although most of the expressed protein accumulates as a 180-kDa proreceptor, some processed 135-kDa receptor can be detected on the cell surface by covalent cross-linking. Expression of the hybrid receptor inhibits the insulin-activated uptake of 2-deoxyglucose by CHO cells. Thus, this hybrid is partially functional and can be processed; however, it is incapable of native transmembrane signaling. The results indicate that the intact domains of different types of receptors can retain some of the native features in a hybrid molecule but specific requirements will need to be satisfied for transmembrane signaling.

  10. Human Polyomavirus Receptor Distribution in Brain Parenchyma Contrasts with Receptor Distribution in Kidney and Choroid Plexus

    PubMed Central

    Haley, Sheila A.; O'Hara, Bethany A.; Nelson, Christian D.S.; Brittingham, Frances L.P.; Henriksen, Kammi J.; Stopa, Edward G.; Atwood, Walter J.

    2016-01-01

    The human polyomavirus, JCPyV, is the causative agent of progressive multifocal leukoencephalopathy, a rare demyelinating disease that occurs in the setting of prolonged immunosuppression. After initial asymptomatic infection, the virus establishes lifelong persistence in the kidney and possibly other extraneural sites. In rare instances, the virus traffics to the central nervous system, where oligodendrocytes, astrocytes, and glial precursors are susceptible to lytic infection, resulting in progressive multifocal leukoencephalopathy. The mechanisms by which the virus traffics to the central nervous system from peripheral sites remain unknown. Lactoseries tetrasaccharide c (LSTc), a pentasaccharide containing a terminal α2,6–linked sialic acid, is the major attachment receptor for polyomavirus. In addition to LSTc, type 2 serotonin receptors are required for facilitating virus entry into susceptible cells. We studied the distribution of virus receptors in kidney and brain using lectins, antibodies, and labeled virus. The distribution of LSTc, serotonin receptors, and virus binding sites overlapped in kidney and in the choroid plexus. In brain parenchyma, serotonin receptors were expressed on oligodendrocytes and astrocytes, but these cells were negative for LSTc and did not bind virus. LSTc was instead found on microglia and vascular endothelium, to which virus bound abundantly. Receptor distribution was not changed in the brains of patients with progressive multifocal leukoencephalopathy. Virus infection of oligodendrocytes and astrocytes during disease progression is LSTc independent. PMID:26056932

  11. Human polyomavirus receptor distribution in brain parenchyma contrasts with receptor distribution in kidney and choroid plexus.

    PubMed

    Haley, Sheila A; O'Hara, Bethany A; Nelson, Christian D S; Brittingham, Frances L P; Henriksen, Kammi J; Stopa, Edward G; Atwood, Walter J

    2015-08-01

    The human polyomavirus, JCPyV, is the causative agent of progressive multifocal leukoencephalopathy, a rare demyelinating disease that occurs in the setting of prolonged immunosuppression. After initial asymptomatic infection, the virus establishes lifelong persistence in the kidney and possibly other extraneural sites. In rare instances, the virus traffics to the central nervous system, where oligodendrocytes, astrocytes, and glial precursors are susceptible to lytic infection, resulting in progressive multifocal leukoencephalopathy. The mechanisms by which the virus traffics to the central nervous system from peripheral sites remain unknown. Lactoseries tetrasaccharide c (LSTc), a pentasaccharide containing a terminal α2,6-linked sialic acid, is the major attachment receptor for polyomavirus. In addition to LSTc, type 2 serotonin receptors are required for facilitating virus entry into susceptible cells. We studied the distribution of virus receptors in kidney and brain using lectins, antibodies, and labeled virus. The distribution of LSTc, serotonin receptors, and virus binding sites overlapped in kidney and in the choroid plexus. In brain parenchyma, serotonin receptors were expressed on oligodendrocytes and astrocytes, but these cells were negative for LSTc and did not bind virus. LSTc was instead found on microglia and vascular endothelium, to which virus bound abundantly. Receptor distribution was not changed in the brains of patients with progressive multifocal leukoencephalopathy. Virus infection of oligodendrocytes and astrocytes during disease progression is LSTc independent.

  12. Clinically used selective oestrogen receptor modulators increase LDL receptor activity in primary human lymphocytes

    PubMed Central

    Cerrato, F; Fernández-Suárez, M E; Alonso, R; Alonso, M; Vázquez, C; Pastor, O; Mata, P; Lasunción, M A; Gómez-Coronado, D

    2015-01-01

    Background and Purpose Treatment with selective oestrogen receptor modulators (SERMs) reduces low-density lipoprotein (LDL) cholesterol levels. We assessed the effect of tamoxifen, raloxifene and toremifene and their combinations with lovastatin on LDL receptor activity in lymphocytes from normolipidaemic and familial hypercholesterolaemic (FH) subjects, and human HepG2 hepatocytes and MOLT-4 lymphoblasts. Experimental Approach Lymphocytes were isolated from peripheral blood, treated with different compounds, and 1,1′-dioctadecyl-3,3,3,3′-tetramethylindocarbocyanine perchlorate (DiI)-labelled LDL uptake was analysed by flow cytometry. Key Results Tamoxifen, toremifene and raloxifene, in this order, stimulated DiI-LDL uptake by lymphocytes by inhibiting LDL-derived cholesterol trafficking and subsequent down-regulation of LDL receptor expression. Differently to what occurred in HepG2 and MOLT-4 cells, only tamoxifen consistently displayed a potentiating effect with lovastatin in primary lymphocytes. The SERM-mediated increase in LDL receptor activity was not altered by the anti-oestrogen ICI 182 780 nor was it reproduced by 17β-oestradiol. However, the tamoxifen-active metabolite endoxifen was equally effective as tamoxifen. The SERMs produced similar effects on LDL receptor activity in heterozygous FH lymphocytes as in normal lymphocytes, although none of them had a potentiating effect with lovastatin in heterozygous FH lymphocytes. The SERMs had no effect in homozygous FH lymphocytes. Conclusions and Implications Clinically used SERMs up-regulate LDL receptors in primary human lymphocytes. There is a mild enhancement between SERMs and lovastatin of lymphocyte LDLR activity, the potentiation being greater in HepG2 and MOLT-4 cells. The effect of SERMs is independent of oestrogen receptors but is preserved in the tamoxifen-active metabolite endoxifen. This mechanism may contribute to the cholesterol-lowering action of SERMs. PMID:25395200

  13. Toll-like receptor sensing of human herpesvirus infection

    PubMed Central

    West, John A.; Gregory, Sean M.; Damania, Blossom

    2012-01-01

    Toll-like receptors (TLRs) are evolutionarily conserved pathogen sensors that constitute the first line of defense in the human immune system. Herpesviruses are prevalent throughout the world and cause significant disease in the human population. Sensing of herpesviruses via TLRs has only been documented in the last 10 years and our understanding of the relationship between these sentinels of the immune system and herpesvirus infection has already provided great insight into how the host cell responds to viral infection. This report will summarize the activation and modulation of TLR signaling in the context of human herpesvirus infections. PMID:23061052

  14. Human eosinophils - potential pharmacological model applied in human histamine H4 receptor research.

    PubMed

    Grosicki, Marek; Kieć-Kononowicz, Katarzyna

    2015-01-01

    Histamine and histamine receptors are well known for their immunomodulatory role in inflammation. In this review we describe the role of histamine and histamine H4 receptor on human eosinophils. In the first part of article we provide short summary of histamine and histamine receptors role in physiology and histamine related therapeutics used in clinics. We briefly describe the human histamine receptor H4 and its ligands, as well as human eosinophils. In the second part of the review we provide detailed description of known histamine effects on eosinophils including: intracellular calcium concentration flux, actin polymerization, cellular shape change, upregulation of adhesion proteins and cellular chemotaxis. We provide proofs that these effects are mainly connected with the activation of histamine H4 receptor. When examining experimental data we discuss the controversial results and limitations of the studies performed on isolated eosinophils. In conclusion we believe that studies on histamine H4 receptor on human eosinophils can provide interesting new biomarkers that can be used in clinical studies of histamine receptors, that in future might result in the development of new strategies in the treatment of chronic inflammatory conditions like asthma or allergy, in which eosinophils are involved.

  15. Mineralocorticoid receptor is involved in the aldosterone pathway in human red blood cells

    PubMed Central

    Bordin, Luciana; Saccardi, Carlo; Donà, Gabriella; Sabbadin, Chiara; Andrisani, Alessandra; Ambrosini, Guido; Plebani, Mario; Brunati, Anna Maria; Ragazzi, Eugenio; Gizzo, Salvatore; Armanini, Decio

    2016-01-01

    We have recently demonstrated that excessive aldosterone (Aldo) secretion in primary aldosteronism (PA) is associated with red blood cells (RBC) senescence. These alterations were prevented/inhibited by cortisol (Cort) or canrenone (Can) raising the hypothesis that Aldo effects in RBC may be mediated by mineralocorticoid receptor (MR), though to date MR has never been demonstrated in human RBC. The aim of this multicenter comparative study was to investigate whether Aldo effects were mediated by MR in these a-nucleated cells. We included 12 healthy controls (HC) and 22 patients with PA. MR presence and activation were evaluated in RBC cytosol by glycerol gradient sedimentation, Western blotting, immuno-precipitation and radioimmunoassay. We demonstrated that RBC contained cytosolic MR, aggregated with HSP90 and other proteins to form multiprotein complex. Aldo induced MR to release from the complex and to form MR dimers which were quickly proteolyzed. Cort induced MR release but not dimers formation while Can was not able to induce MR release. In addition, RBC cytosol from PA patients contained significantly higher amounts of both MR fragments (p<0.0001) and Aldo (p<0.0001) concentrations. In conclusion, in RBC a genomic-like Aldo pathway is proposed involving MR activation, dimerization and proteolysis, but lacking nuclear transcription. In addition, dimers proteolysis may ensure a sort of Aldo scavenging from circulation by entrapping Aldo in MR fragments. PMID:27158328

  16. Regulation of Class A scavenger receptor-mediated cell adhesion and surface localization by PI3K: identification of a regulatory cytoplasmic motif

    PubMed Central

    Cholewa, Jill; Nikolic, Dejan; Post, Steven R.

    2010-01-01

    The importance of cytoplasmic motifs in differentially regulating SR-A function was demonstrated by deleting the first 49 cytoplasmic aa (SR-AΔ1–49), which abolished SR-A-mediated ligand internalization without reducing cell adhesion. To identify additional cytoplasmic motifs within the first 49 aa that regulate SR-A function, the acidic residues in a conserved motif (EDAD) were changed to their amide derivatives (SR-AQNAN). The function and regulation of SR-AQNAN were compared with that of SR-AΔ1–49 and SR-A in transfected HEK-293 cells. Blocking PI3K activation inhibited SR-A, but not SR-AΔ1–49- or SR-AQNAN-mediated cell adhesion. Although deleting (SR-AΔ1–49) or mutating (SR-AQNAN) the EDAD motif abolished the PI3K sensitivity of SR-A-mediated cell adhesion, these mutations did not affect ligand internalization or PI3K activation during cell adhesion. To define the mechanism by which PI3K regulates SR-A-mediated cell adhesion, the cellular localization of wild-type and mutant SR-A was examined. PI3K inhibition reduced surface localization of SR-A but not of SR-AΔ1–49 or SR-AQNAN. The regulation of SR-A surface localization by PI3K was confirmed in peritoneal macrophages, which endogenously express SR-A. Together, these results suggest a pathway in which SR-A binding to an immobilized ligand activates PI3K to recruit more receptor to the plasma membrane and enhances cell adhesion. PMID:19952357

  17. Differential endocytotic characteristics of a novel human B/DC cell line HBM-Noda: effective macropinocytic and phagocytic function rather than scavenging function

    PubMed Central

    TORII, IKUKO; MORIKAWA, SHIGERU; NAGASAKI, MAKOTO; NOKANO, AKINOBU; MORIKAWA, KEIKO

    2001-01-01

    In order to characterize a novel human B cell-lineage dendritic cell line (B/DC line) as an antigen-presenting cell (APC), we compared three types of endocytosis (micropinocytosis via a clathrin-coated pit, macropinocytosis via membrane ruffling, and phagocytosis) among myeloid-related, macrophage (Mφ) cell lines and a B/DC line. In the present examination, we used a unique human dendritic cell (DC) line, HBM-Noda (Noda). Flow cytometric and immunocytochemical analyses revealed that Noda not only expresses some DC markers, but also it expresses some B-cell associated markers. Noda shows strong capacities to stimulate allogenic T cells, to produce immunoglobulin G (IgG), and to perform immunoglobulin gene rearrangment. These data strongly suggest that Noda is a B-cell lineage DC line. The endocytic differences among these cell lines were as follows. (1) The level of micropinocytosis of Noda was significantly less than that of conventional human Mφ cell lines, and the formation of a clathrin-coated pit was not observed in Noda. (2) The level of macropinocytosis of Noda was also smaller than that of conventional Mφ cells indicating that the active membrane ruffling of Noda induces rapid recycling. (3) Phagocytosis of opsonized sheep red blood cells (SRBC) was performed more efficiently in Noda than in other Mφ cell lines. Collectively, these data suggest that in human bone marrow cells, we can identify a unique DC subtype, B/DC line, which develops through a lymphoid DC-differentiation pathway, and DC in this lineage plays an important role in the host immune response because of its effective uptake of a variety of size of antigens by using the skilful membrane ruffling and surface receptors PMID:11380694

  18. Antibodies from a patient with type 1 diabetes and celiac disease bind to macrophages that express the scavenger receptor CD163.

    PubMed

    Sonier, Brigitte; Strom, Alexander; Wang, Gen-Sheng; Patrick, Christopher; Crookshank, Jennifer A; Mojibian, Majid; MacFarlane, Amanda J; Scott, Fraser W

    2011-06-01

    Antibodies against the wheat storage globulin Glo-3A from a patient with both type 1 diabetes (T1D) and celiac disease were enriched to identify potential molecular mimicry between wheat antigens and T1D target tissues. Recombinant Glo-3A was used to enrich anti-Glo-3A immunoglobulin G antibodies from plasma by batch affinity chromatography. Rat jejunum and pancreas, as well as human duodenum and monocytes were probed, and binding was evaluated by immunohistochemistry and confocal microscopy. Glo-3A-enriched antibodies bound to a specific subset of cells in the lamina propria of rat jejunum that co-localized mostly with a marker of resident, alternatively activated CD163-positive (CD163⁺) macrophages. Blood monocytes and macrophage-like cells in human duodenum were also labelled with the enriched antibodies. Blocking studies revealed that binding to CD163⁺ macrophages was not due to cross-reactivity with anti-Glo-3A antibodies, but rather to non-Glo-3A antibodies co-purified during antibody enrichment. The novel finding of putative autoantibodies against tolerogenic intestinal CD163⁺ macrophages suggests that regulatory macrophages were targeted in this patient with celiac disease and T1D.

  19. Antibodies from a patient with type 1 diabetes and celiac disease bind to macrophages that express the scavenger receptor CD163

    PubMed Central

    Sonier, Brigitte; Strom, Alexander; Wang, Gen-Sheng; Patrick, Christopher; Crookshank, Jennifer A; Mojibian, Majid; MacFarlane, Amanda J; Scott, Fraser W

    2011-01-01

    Antibodies against the wheat storage globulin Glo-3A from a patient with both type 1 diabetes (T1D) and celiac disease were enriched to identify potential molecular mimicry between wheat antigens and T1D target tissues. Recombinant Glo-3A was used to enrich anti-Glo-3A immunoglobulin G antibodies from plasma by batch affinity chromatography. Rat jejunum and pancreas, as well as human duodenum and monocytes were probed, and binding was evaluated by immunohistochemistry and confocal microscopy. Glo-3A-enriched antibodies bound to a specific subset of cells in the lamina propria of rat jejunum that co-localized mostly with a marker of resident, alternatively activated CD163-positive (CD163+) macrophages. Blood monocytes and macrophage-like cells in human duodenum were also labelled with the enriched antibodies. Blocking studies revealed that binding to CD163+ macrophages was not due to cross-reactivity with anti-Glo-3A antibodies, but rather to non-Glo-3A antibodies co-purified during antibody enrichment. The novel finding of putative autoantibodies against tolerogenic intestinal CD163+ macrophages suggests that regulatory macrophages were targeted in this patient with celiac disease and T1D. PMID:21766094

  20. Human platelets express authentic CB₁ and CB₂ receptors.

    PubMed

    Catani, M V; Gasperi, V; Catanzaro, G; Baldassarri, S; Bertoni, A; Sinigaglia, F; Avigliano, L; Maccarrone, M

    2010-11-01

    In the last decade, the neurovascular effects exerted by endocannabinoids (eCBs) have attracted growing interest, because they hold the promise to open new avenues of therapeutic intervention against major causes of death in Western society. Several actions of eCBs are mediated by type-1 (CB₁) or type-2 (CB₂) cannabinoid receptors, yet there is no clear evidence of the presence of these proteins in platelets. To demonstrate that CB₁ and CB₂ are expressed in human platelets, we analyzed their protein level by Western blotting and ELISA, visualized their cellular localization by confocal microscopy, and ascertained their functionality by binding assays. We found that CB₁, and to a lesser extent CB₂, are expressed in highly purified human platelets. Both receptor subtypes were predominantly localized inside the cell, thus explaining why they might remain undetected in preparations of plasma membranes. The identification of authentic CB₁ and CB₂ in human platelets supports the potential exploitation of selective agonists or antagonists of these receptors as novel therapeutics to combat neurovascular disorders. It seems remarkable that some of these substances have been already used in humans to treat disease states.

  1. Sigma and opioid receptors in human brain tumors

    SciTech Connect

    Thomas, G.E.; Szuecs, M.; Mamone, J.Y.; Bem, W.T.; Rush, M.D.; Johnson, F.E.; Coscia, C.J. )

    1990-01-01

    Human brain tumors and nude mouse-borne human neuroblastomas and gliomas were analyzed for sigma and opioid receptor content. Sigma binding was assessed using ({sup 3}H) 1, 3-di-o-tolylguanidine (DTG), whereas opioid receptor subtypes were measured with tritiated forms of the following: {mu}, (D-ala{sup 2}, mePhe{sup 4}, gly-ol{sup 5}) enkephalin (DAMGE); {kappa}, ethylketocyclazocine (EKC) or U69,593; {delta}, (D-pen{sup 2}, D-pen{sup 5}) enkephalin (DPDPE) or (D-ala{sup 2}, D-leu{sup 5}) enkephalin (DADLE) with {mu} suppressor present. Binding parameters were estimated by homologous displacement assays followed by analysis using the LIGAND program. Sigma binding was detected in 15 of 16 tumors examined with very high levels found in a brain metastasis from an adenocarcinoma of lung and a human neuroblastoma (SK-N-MC) passaged in nude mice. {kappa} opioid receptor binding was detected in 4 of 4 glioblastoma multiforme specimens and 2 of 2 human astrocytoma cell lines tested but not in the other brain tumors analyzed.

  2. Genetic variation in a human odorant receptor alters odour perception.

    PubMed

    Keller, Andreas; Zhuang, Hanyi; Chi, Qiuyi; Vosshall, Leslie B; Matsunami, Hiroaki

    2007-09-27

    Human olfactory perception differs enormously between individuals, with large reported perceptual variations in the intensity and pleasantness of a given odour. For instance, androstenone (5alpha-androst-16-en-3-one), an odorous steroid derived from testosterone, is variously perceived by different individuals as offensive ("sweaty, urinous"), pleasant ("sweet, floral") or odourless. Similar variation in odour perception has been observed for several other odours. The mechanistic basis of variation in odour perception between individuals is unknown. We investigated whether genetic variation in human odorant receptor genes accounts in part for variation in odour perception between individuals. Here we show that a human odorant receptor, OR7D4, is selectively activated in vitro by androstenone and the related odorous steroid androstadienone (androsta-4,16-dien-3-one) and does not respond to a panel of 64 other odours and two solvents. A common variant of this receptor (OR7D4 WM) contains two non-synonymous single nucleotide polymorphisms (SNPs), resulting in two amino acid substitutions (R88W, T133M; hence 'RT') that severely impair function in vitro. Human subjects with RT/WM or WM/WM genotypes as a group were less sensitive to androstenone and androstadienone and found both odours less unpleasant than the RT/RT group. Genotypic variation in OR7D4 accounts for a significant proportion of the valence (pleasantness or unpleasantness) and intensity variance in perception of these steroidal odours. Our results demonstrate the first link between the function of a human odorant receptor in vitro and odour perception.

  3. Immunohistochemical study of oestrogen receptors in 351 human thyroid glands.

    PubMed

    Tavangar, S M; Monajemzadeh, M; Larijani, B; Haghpanah, V

    2007-08-01

    It is well recognised that the pathogenesis of thyroid diseases is complex and different factors such as genetic factors, iodine deficiency, sex, age, radiation therapy in childhood, growth stimulating antibodies, and other epithelial growth factors can influence them. Epidemiological features of thyroid tumours and experimental evidence suggest that female sex hormones may exert effects on the thyroid gland and its neoplasms. This possibility was addressed by investigating the expression of oestrogen receptor protein in 351 thyroid lesions. The tissues from 351 human thyroid glands comprising 130 nodular goitres and 221 neoplastic lesions were used for the present immunohistochemical assessment of oestrogen receptor expression. Incidence of oestrogen receptor positive cases were 24 percent (31/130) for nodular goitres, 22 percent (8/37) for follicular adenomas, 11 percent (2/18) for follicular carcinomas, 31 percent (37/119) for papillary carcinomas, zero percent (0/35) for medullary carcinomas and zero percent (0/12) for undifferentiated carcinomas. The incidence of oestrogen receptor positivity, which is compatible with other studies, is higher in well-differentiated thyroid lesions. The incidence of oestrogen receptor reactivity does not significantly differ between females and males of different age groups and it does not correlate with lymph node status, and vascular and capsular invasions. The relatively high proportion of oestrogen receptor positivity in goitres, follicular adenomas and papillary carcinomas, compared with its reactivity in other thyroid neoplasms, and contrasted against normal thyroid tissue, suggests that the incidence of oestrogen receptor reactivity tends to increase with better differentiation of thyroid lesions. This finding may have clinical relevance.

  4. Differential expression of laminin receptors in human hepatocellular carcinoma

    PubMed Central

    Ozaki, I; Yamamoto, K; Mizuta, T; Kajihara, S; Fukushima, N; Setoguchi, Y; Morito, F; Sakai, T

    1998-01-01

    Background—Laminin receptors are involved in cell-extracellular matrix interactions in malignant cells that show invasion and metastasis. Hepatocellular carcinoma frequently shows early invasion into blood vessels, and intrahepatic and extrahepatic metastases. However, the role of laminin receptors in hepatocellular carcinoma is unknown. 
Aims—To examine the expression of mRNA for laminin receptors and their isoforms in hepatocellular carcinoma. 
Methods—The expression of several laminin receptors, including α1 integrin, α6 integrin and its isoforms α6A and α6B, β1 integrin and its isoforms β1A and β1B, and 32kD/67kDa laminin binding protein was examined in human hepatocellular carcinomas and non-cancerous liver tissues using the reverse transcription polymerase chain reaction. 
Results—α6 Integrin, β1 integrin, and laminin binding protein showed notably increased expression in hepatocellular carcinoma, compared with non-cancerous liver tissue, although the α1 integrin did not show a significant change. Furthermore, β1B integrin, a splicing variant of β1 integrin, was overexpressed in hepatocellular carcinoma while the β1A integrin isoform did not show significant changes between hepatocellular carcinoma and surrounding non-cancerous liver tissue. 
Conclusions—The differential upregulation of laminin receptors and their splicing isoforms was shown in hepatocellular carcinoma, suggesting that certain laminin receptors and their isoforms may be involved in the development and progression of hepatocellular carcinoma. 

 Keywords: laminin receptor; integrin α6β1; hepatocellular carcinoma PMID:9824613

  5. The immunohistochemical expression of calcitonin receptor-like receptor (CRLR) in human gliomas

    PubMed Central

    Benes, L; Kappus, C; McGregor, G P; Bertalanffy, H; Mennel, H D; Hagner, S

    2004-01-01

    Background: Gliomas are the most common primary tumours of the central nervous system and exhibit rapid growth that is associated with neovascularisation. Adrenomedullin is an important tumour survival factor in human carcinogenesis. It has growth promoting effects on gliomas, and blockade of its actions has been experimentally shown to reduce the growth of glioma tissues and cell lines. There is some evidence that the calcitonin receptor-like receptor (CRLR) mediates the tumorigenic actions of adrenomedullin. Aim: To determine whether CRLR is expressed in human gliomas and the probable cellular targets of adrenomedullin. Methods: Biopsies from 95 human gliomas of varying grade were processed for immunohistochemical analysis using a previously developed and characterised antibody to CRLR. Results: All tumour specimens were positive for CRLR. As previously found in normal peripheral tissues, CRLR immunostaining was particularly intense in the endothelial cells. This was evident in all the various vascular conformations that were observed, and which are typical of gliomas. In addition, clear immunostaining of tumour cells with astrocyte morphology was observed. These were preferentially localised around vessels. Conclusions: This study has shown for the first time that the CRLR protein is present in human glioma tissue. The expression of the receptor in endothelial cells and in astrocytic tumour cells is consistent with the evidence that its endogenous ligand, adrenomedullin, may influence glioma growth by means of both direct mitogenic and indirect angiogenic effects. CRLR may be a valuable target for effective therapeutic intervention in these malignant tumours. PMID:14747444

  6. Free radical scavenging and formation by multi-walled carbon nanotubes in cell free conditions and in human bronchial epithelial cells

    PubMed Central

    2014-01-01

    Background Certain multi-walled carbon nanotubes (MWCNTs) have been shown to elicit asbestos-like toxicological effects. To reduce needs for risk assessment it has been suggested that the physicochemical characteristics or reactivity of nanomaterials could be used to predict their hazard. Fibre-shape and ability to generate reactive oxygen species (ROS) are important indicators of high hazard materials. Asbestos is a known ROS generator, while MWCNTs may either produce or scavenge ROS. However, certain biomolecules, such as albumin – used as dispersants in nanomaterial preparation for toxicological testing in vivo and in vitro - may reduce the surface reactivity of nanomaterials. Methods Here, we investigated the effect of bovine serum albumin (BSA) and cell culture medium with and without BEAS 2B cells on radical formation/scavenging by five MWCNTs, Printex 90 carbon black, crocidolite asbestos, and glass wool, using electron spin resonance (ESR) spectroscopy and linked this to cytotoxic effects measured by trypan blue exclusion assay. In addition, the materials were characterized in the exposure medium (e.g. for hydrodynamic size-distribution and sedimentation rate). Results The test materials induced highly variable cytotoxic effects which could generally be related to the abundance and characteristics of agglomerates/aggregates and to the rate of sedimentation. All carbon nanomaterials were found to scavenge hydroxyl radicals (•OH) in at least one of the solutions tested. The effect of BSA was different among the materials. Two types of long, needle-like MWCNTs (average diameter >74 and 64.2 nm, average length 5.7 and 4.0 μm, respectively) induced, in addition to a scavenging effect, a dose-dependent formation of a unique, yet unidentified radical in both absence and presence of cells, which also coincided with cytotoxicity. Conclusions Culture medium and BSA affects scavenging/production of •OH by MWCNTs, Printex 90 carbon black, asbestos and glass

  7. Purine receptor mediated actin cytoskeleton remodeling of human fibroblasts

    PubMed Central

    Goldman, Nanna; Chandler-Militello, Devin; Langevin, Helene; Nedergaard, Maiken; Takano, Takahiro

    2013-01-01

    Earlier studies have shown that activation of adenosine A1 receptors on peripheral pain fibers contributes to acupuncture-induced suppression of painful input. In addition to adenosine, acupuncture triggers the release of other purines, including ATP and ADP that may bind to purine receptors on nearby fibroblasts. We here show that purine agonists trigger increase in cytosolic Ca 2+ signaling in a cultured human fibroblasts cell line. The profile of agonist-induced Ca2+ increases indicates that the cells express functional P2yR2 and P2yR4 receptors, as well as P2yR1 and P2xR7 receptors. Unexpectedly, purine-induced Ca2+ signaling was associated with a remodeling of the actin cytoskeleton. ATP induced a transient loss in F-actin stress fiber. The changes of actin cytoskeleton occurred slowly and peaked at 10 min after agonist exposure. Inhibition of ATP-induced increases in Ca2+ by cyclopiazonic acid blocked receptor-mediated cytoskeleton remodeling. The Ca2+ ionophore failed to induce cytoskeletal remodeling despite triggering robust increases in cytosolic Ca2+. These observations indicate that purine signaling induces transient changes in fibroblast cytoarchitecture that could be related to the beneficial effects of acupuncture. PMID:23462235

  8. Heterodimeric coiled-coil interactions of human GABAB receptor

    PubMed Central

    Burmakina, Svetlana; Geng, Yong; Chen, Yan; Fan, Qing R.

    2014-01-01

    Metabotropic GABAB receptor is a G protein-coupled receptor that mediates inhibitory neurotransmission in the CNS. It functions as an obligatory heterodimer of GABAB receptor 1 (GBR1) and GABAB receptor 2 (GBR2) subunits. The association between GBR1 and GBR2 masks an endoplasmic reticulum (ER) retention signal in the cytoplasmic region of GBR1 and facilitates cell surface expression of both subunits. Here, we present, to our knowledge, the first crystal structure of an intracellular coiled-coil heterodimer of human GABAB receptor. We found that polar interactions buried within the hydrophobic core determine the specificity of heterodimer pairing. Disruption of the hydrophobic coiled-coil interface with single mutations in either subunit impairs surface expression of GBR1, confirming that the coiled-coil interaction is required to inactivate the adjacent ER retention signal of GBR1. The coiled-coil assembly buries an internalization motif of GBR1 at the heterodimer interface. The ER retention signal of GBR1 is not part of the core coiled-coil structure, suggesting that it is sterically shielded by GBR2 upon heterodimer formation. PMID:24778228

  9. Human psychometric and taste receptor responses to steviol glycosides.

    PubMed

    Hellfritsch, Caroline; Brockhoff, Anne; Stähler, Frauke; Meyerhof, Wolfgang; Hofmann, Thomas

    2012-07-11

    Steviol glycosides, the sweet principle of Stevia Rebaudiana (Bertoni) Bertoni, have recently been approved as a food additive in the EU. The herbal non-nutritive high-potency sweeteners perfectly meet the rising consumer demand for natural food ingredients in Europe. We have characterized the organoleptic properties of the most common steviol glycosides by an experimental approach combining human sensory studies and cell-based functional taste receptor expression assays. On the basis of their potency to elicit sweet and bitter taste sensations, we identified glycone chain length, pyranose substitution, and the C16 double bond as the structural features giving distinction to the gustatory profile of steviol glycosides. A comprehensive screening of 25 human bitter taste receptors revealed that two receptors, hTAS2R4 and hTAS2R14, mediate the bitter off-taste of steviol glycosides. For some test substances, e.g., stevioside, we observed a decline in sweet intensity at supra-maximum concentrations. This effect did not arise from allosteric modulation of the hTAS1R2/R3 sweet taste receptor but might be explained by intramolecular cross-modal suppression between the sweet and bitter taste component of steviol glycosides. These results might contribute to the production of preferentially sweet and least bitter tasting Stevia extracts by an optimization of breeding and postharvest downstream processing.

  10. Molecular and cellular analysis of human histamine receptor subtypes

    PubMed Central

    Seifert, Roland; Strasser, Andrea; Schneider, Erich H.; Neumann, Detlef; Dove, Stefan; Buschauer, Armin

    2013-01-01

    The human histamine receptors hH1R and hH2R constitute important drug targets, and hH3R and hH4R have substantial potential in this area. Considering the species-specificity of pharmacology of HxR orthologs, it is important to analyze hHxRs. Here,we summarize current knowledge of hHxRs endogenously expressed in human cells and hHxRs recombinantly expressed in mammalian and insect cells. We present the advantages and disadvantages of the various systems. We also discuss problems associated with the use of hHxR antibodies, an issue of general relevance for G-protein-coupled receptors (GPCRs). There is much greater overlap in activity of ‘selective’ ligands for other hHxRs than the cognate receptor subtype than generally appreciated. Studies with native and recombinant systems support the concept of ligand-specific receptor conformations, encompassing agonists and antagonists. It is emerging that for characterization of hHxR ligands, one cannot rely on a single test system and a single parameter. Rather, multiple systems and parameters have to be studied. Although such studies are time-consuming and expensive, ultimately, they will increase drug safety and efficacy. PMID:23254267

  11. Atmospheric scavenging exhaust

    NASA Technical Reports Server (NTRS)

    Fenton, D. L.; Purcell, R. Y.

    1977-01-01

    Solid propellant rocket exhaust was directly utilized to ascertain raindrop scavenging rates for hydrogen chloride. The airborne HCl concentration varied from 0.2 to 10.0 ppm and the raindrop sizes tested included 0.55 mm, 1.1 mm, and 3.0 mm. Two chambers were used to conduct the experiments. A large, rigid walled, spherical chamber stored the exhaust constituents while the smaller chamber housing all the experiments was charged as required with rocket exhaust HCl. Surface uptake experiments demonstrated an HCl concentration dependence for distilled water. Sea water and brackish water HCl uptake was below the detection limit of the chlorine-ion analysis technique employed. Plant life HCl uptake experiments were limited to corn and soybeans. Plant age effectively correlated the HCl uptake data. Metallic corrosion was not significant for single 20 minute exposures to the exhaust HCl under varying relative humidity.

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

    SciTech Connect

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

    1988-05-05

    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/sup 0/C, and internalization of insulin-receptor complexes was initiated by warming the cells to 37/sup 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.

  13. CXCL4 Downregulates the Atheroprotective Hemoglobin Receptor CD163 in Human Macrophages

    PubMed Central

    Gleissner, Christian A.; Shaked, Iftach; Erbel, Christian; Böckler, Dittmar; Katus, Hugo A.; Ley, Klaus

    2010-01-01

    Rationale CXCL4 is a platelet-derived chemokine that promotes macrophage differentiation from monocytes. Deletion of the PF4 gene that encodes CXCL4 reduces atherosclerotic lesions in ApoE−/− mice. Objective We sought to study effects of CXCL4 on macrophage differentiation with possible relevance for atherogenesis. Methods and Results Flow cytometry for expression of surface markers in macrophage colony–stimulating factor (M-CSF)– and CXCL4-induced macrophages demonstrated virtually complete absence of the hemoglobin scavenger receptor CD163 in CXCL4-induced macrophages. mRNA for CD163 was downregulated as early as 2 hours after CXCL4. CD163 protein reached a minimum after 3 days, which was not reversed by treatment of cells with M-CSF. The CXCL4 effect was entirely neutralized by heparin, which bound CXCL4 and prevented CXCL4 surface binding to monocytes. Pretreatment of cells with chlorate, which inhibits glycosaminoglycan synthesis, strongly inhibited CXCL4-dependent downregulation of CD163. Similar to recombinant CXCL4, releasate from human platelets also reduced CD163 expression. CXCL4-differentiated macrophages were unable to upregulate the atheroprotective enzyme heme oxygenase-1 at the RNA and protein level in response to hemoglobin–haptoglobin complexes. Immunofluorescence of human atherosclerotic plaques demonstrated presence of both CD68+CD163+ and CD68+CD163− macrophages. PF4 and CD163 gene expression within human atherosclerotic lesions were inversely correlated, supporting the in vivo relevance of CXCL4-induced downregulation of CD163. Conclusions CXCL4 may promote atherogenesis by suppressing CD163 in macrophages, which are then unable to upregulate the atheroprotective enzyme heme oxygenase-1 in response to hemoglobin. PMID:19910578

  14. Palmitoylethanolamide enhances anandamide stimulation of human vanilloid VR1 receptors.

    PubMed

    De Petrocellis, L; Davis, J B; Di Marzo, V

    2001-10-12

    In human embryonic kidney cells over-expressing the human vanilloid receptor type 1 (VR1), palmitoylethanolamide (PEA, 0.5-10 microM) enhanced the effect of arachidonoylethanolamide (AEA, 50 nM) on the VR1-mediated increase of the intracellular Ca2+ concentration. PEA (5 microM) decreased the AEA half-maximal concentration for this effect from 0.44 to 0.22 microM. The PEA effect was not due to inhibition of AEA hydrolysis or adhesion to non-specific sites, since bovine serum albumin (0.01-0.25%) potently inhibited AEA activity, and PEA also enhanced the effect of low concentrations of the VR1 agonists resiniferatoxin and capsaicin. PEA (5 microM) enhanced the affinity of AEA for VR1 receptors as assessed in specific binding assays. These data suggest that PEA might be an endogenous enhancer of VR1-mediated AEA actions.

  15. An examination of 5-hydroxytryptamine receptors in human saphenous vein.

    PubMed Central

    Docherty, J. R.; Hyland, L.

    1986-01-01

    We have examined the effects of antagonists on the isometric contraction of the human saphenous vein produced by 5-hydroxytryptamine (5-HT). The 5-HT2-antagonist ketanserin (1 microM) had little effect on the lower part of the concentration-response curve to 5-HT, but markedly shifted the upper part of the curve. Yohimbine caused an approximately parallel shift of the concentration-response curve to 5-HT, with a pA2 of 5.48, much lower than its pA2 against noradrenaline in the absence (6.36) or presence (7.06) of cocaine. It is concluded that there are two components to the contractile response to 5-HT in human saphenous vein: at low concentrations 5-HT activates a yohimbine-sensitive receptor, and at higher concentrations 5-HT activates a 5-HT2-receptor. PMID:3801780

  16. Human Xenobiotic Nuclear Receptor PXR Augments Mycobacterium tuberculosis Survival.

    PubMed

    Bhagyaraj, Ella; Nanduri, Ravikanth; Saini, Ankita; Dkhar, Hedwin Kitdorlang; Ahuja, Nancy; Chandra, Vemika; Mahajan, Sahil; Kalra, Rashi; Tiwari, Drishti; Sharma, Charu; Janmeja, Ashok Kumar; Gupta, Pawan

    2016-07-01

    Mycobacterium tuberculosis can evade host defense processes, thereby ensuring its survival and pathogenesis. In this study, we investigated the role of nuclear receptor, pregnane X receptor (PXR), in M. tuberculosis infection in human monocyte-derived macrophages. In this study, we demonstrate that PXR augments M. tuberculosis survival inside the host macrophages by promoting the foamy macrophage formation and abrogating phagolysosomal fusion, inflammation, and apoptosis. Additionally, M. tuberculosis cell wall lipids, particularly mycolic acids, crosstalk with human PXR (hPXR) by interacting with its promiscuous ligand binding domain. To confirm our in vitro findings and to avoid the reported species barrier in PXR function, we adopted an in vivo mouse model expressing hPXR, wherein expression of hPXR in mice promotes M. tuberculosis survival. Therefore, pharmacological intervention and designing antagonists to hPXR may prove to be a promising adjunct therapy for tuberculosis. Copyright © 2016 by The American Association of Immunologists, Inc.

  17. Behavioral analysis of Drosophila transformants expressing human taste receptor genes in the gustatory receptor neurons.

    PubMed

    Adachi, Ryota; Sasaki, Yuko; Morita, Hiromi; Komai, Michio; Shirakawa, Hitoshi; Goto, Tomoko; Furuyama, Akira; Isono, Kunio

    2012-06-01

    Transgenic Drosophila expressing human T2R4 and T2R38 bitter-taste receptors or PKD2L1 sour-taste receptor in the fly gustatory receptor neurons and other tissues were prepared using conventional Gal4/UAS binary system. Molecular analysis showed that the transgene mRNAs are expressed according to the tissue specificity of the Gal4 drivers. Transformants expressing the transgene taste receptors in the fly taste neurons were then studied by a behavioral assay to analyze whether transgene chemoreceptors are functional and coupled to the cell response. Since wild-type flies show strong aversion against the T2R ligands as in mammals, the authors analyzed the transformants where the transgenes are expressed in the fly sugar receptor neurons so that they promote feeding ligand-dependently if they are functional and activate the neurons. Although the feeding preference varied considerably among different strains and individuals, statistical analysis using large numbers of transformants indicated that transformants expressing T2R4 showed a small but significant increase in the preference for denatonium and quinine, the T2R4 ligands, as compared to the control flies, whereas transformants expressing T2R38 did not. Similarly, transformants expressing T2R38 and PKD2L1 also showed a similar preference increase for T2R38-specific ligand phenylthiocarbamide (PTC) and a sour-taste ligand, citric acid, respectively. Taken together, the transformants expressing mammalian taste receptors showed a small but significant increase in the feeding preference that is taste receptor and also ligand dependent. Although future improvements are required to attain performance comparable to the endogenous robust response, Drosophila taste neurons may serve as a potential in vivo heterologous expression system for analyzing chemoreceptor function.

  18. Endothelin-1 downregulates Mas receptor expression in human cardiomyocytes.

    PubMed

    Chen, Zhiheng; Tang, Yamei; Yang, Zuocheng; Liu, Shaojun; Liu, Yong; Li, Yan; He, Wei

    2013-09-01

    Endothelin-1 (ET-1) and the renin-angiotensin system (RAS) are involved in the pathogenesis of cardiac dysfunction. The Mas receptor is a functional binding site for angiotensin (Ang)‑(1-7), which is now considered a critical component of the RAS and exerts cardioprotective effects. To the best of our knowledge, the present study aimed to examine, for the first time, the effects of ET-1 on Mas expression in cultured human cardiomyocytes. Human cardiomyocytes were treated with ET-1 at different concentrations (1, 5, 10, 20 and 30 nM) for varied time periods (0.5, 1.5, 3, 4.5 or 6 h) with or without the transcription inhibitor actinomycin D, endothelin A (ETA) receptor blocker BQ123 and ETB receptor blocker BQ788, or different kinase inhibitors. ET-1 decreased the Mas mRNA level in a statistically significant dose- and time-dependent manner within 4.5 h, which was reflected in the dose-dependent downregulation of Mas promoter activity, Mas protein levels and Ang-(1-7) binding on the cell membrane. Actinomycin D (1 mg/ml), BQ123 (1 µM), p38 mitogen-activated protein kinase (MAPK) siRNA and inhibitor PD169316 (25 µM), completely eliminated the inhibitory effects of ET-1 on Mas expression in human cardiomyocytes. In conclusion, the present study demonstrated that ET-1 downregulates Mas expression at the transcription level in human cardiomyocytes via the ETA receptor by a p38 MAPK‑dependent mechanism. This study provides novel insights into the function of ET-1 and the Ang‑(1-7)/Mas axis in cardiac pathophysiology.

  19. Human glucagon receptor antagonists based on alkylidene hydrazides.

    PubMed

    Ling, Anthony; Plewe, Michael; Gonzalez, Javier; Madsen, Peter; Sams, Christian K; Lau, Jesper; Gregor, Vlad; Murphy, Doug; Teston, Kimberly; Kuki, Atsuo; Shi, Shenghua; Truesdale, Larry; Kiel, Dan; May, John; Lakis, James; Anderes, Kenna; Iatsimirskaia, Eugenia; Sidelmann, Ulla G; Knudsen, Lotte B; Brand, Christian L; Polinsky, Alex

    2002-02-25

    A series of alkylidene hydrazide derivatives containing an alkoxyaryl moiety was optimized. The resulting hydrazide-ethers were competitive antagonists at the human glucagon receptor. Pharmacokinetic experiments showed fast clearance of most of the compounds tested. A representative compound [4-hydroxy-3-cyanobenzoic acid (4-isopropylbenzyloxy-3,5-dimethoxymethylene)hydrazide] with an IC50 value of 20 nM was shown to reduce blood glucose levels in fasted rats.

  20. Human G protein-coupled receptor studies in Saccharomyces cerevisiae.

    PubMed

    Liu, Rongfang; Wong, Winsy; IJzerman, Adriaan P

    2016-08-15

    G protein-coupled receptors (GPCRs) are one of the largest families of membrane proteins, with approximately 800 different GPCRs in the human genome. Signaling via GPCRs regulates many biological processes, such as cell proliferation, differentiation, and development. In addition, many receptors have a pivotal role in immunophysiology. Many hormones and neurotransmitters are ligands for these receptors, and hence it is not surprising that many drugs, either mimicking or blocking the action of the bodily substances, have been developed. It is estimated that 30-40% of current drugs on the market target GPCRs. Further identifying and elucidating the functions of GPCRs will provide opportunities for novel drug discovery, including for immunotherapy. The budding yeast Saccharomyces cerevisiae (S. cerevisiae) is a very important and useful platform in this respect. There are many advantages of using a yeast assay system, as it is cheap, safe and stable; it is also convenient for rapid feasibility and optimization studies. Moreover, it offers a "null" background when studying human GPCRs. New developments regarding human GPCRs expressed in a yeast platform are providing insight into GPCR activation and signaling, and facilitate agonist and antagonist identification. In this review we summarize the latest findings regarding human G-protein-coupled receptors in studies using S. cerevisiae, ever since the year 2005 when we last published a review on this topic. We describe 11 families of GPCRs in detail, while including the principles and developments of each yeast system applied to these different GPCRs and highlight and generalize the experimental findings of GPCR function in these systems. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Characterization of the Human Platelet α-Adrenergic Receptor

    PubMed Central

    Alexander, R. Wayne; Cooper, Barry; Handin, Robert I.

    1978-01-01

    Human platelets aggregate and undergo a release reaction when incubated with catecholamines. Indirect evidence indicates that these events are mediated through α-adrenergic receptors. We used [3H]dihydroergocryptine, an α-adrenergic antagonist, to identify binding sites on platelets that have the characteristics of α-adrenergic receptors. Catecholamines compete for the binding sites in a stereo-specific manner with the potency series of (−) epinephrine > (−) norepinephrine > (±) phenylephrine > (−) isoproterenol. The dissociation constant (Kd) of (−) epinephrine is 0.34 μM. Binding is saturable using a platelet particulate fraction but not with intact platelets. There are 0.130 pmol binding sites per milligram protein in fresh platelet membranes. This number represents approximately 100 binding sites per platelet. The Kd for [3H]-dihydroergocryptine was 0.003−0.01 μM. The α-adrenergic antagonist phentolamine (Kd = 0.0069 μM) was much more potent than the β-adrenergic antagonist (±) propranolol (Kd = 27 μM) in competing for the binding sites. The binding data were correlated with catecholamine-induced platelet aggregation and inhibition of basal and prostaglandin E1-stimulated adenylate cyclase. (−) Epinephrine was more potent than (−) norepinephrine in producing aggregation whereas (−) isoproterenol was ineffective. The threshold dose for inducing aggregation by (−) epinephrine was 0.46 μM. Phentolamine and dihydroergocyrptine blocked this response, whereas (±) propranolol had no effect. (−) Epinephrine and (−) norepinephrine inhibited basal and prostaglandin E1-stimulated adenylate cyclase in a dose-related manner. The concentration of (−) epinephrine inhibiting adenylate cyclase 50% was 0.7 μM. This inhibition was also blocked by phentolamine and dihydroergocryptine but not by (±) propranolol. The specificity of binding and the close correlation with α-adrenergic receptor-mediated biochemical and physiological responses

  2. Modulation of cAMP levels by high-fat diet and curcumin and regulatory effects on CD36/FAT scavenger receptor/fatty acids transporter gene expression.

    PubMed

    Zingg, Jean-Marc; Hasan, Syeda T; Nakagawa, Kiyotaka; Canepa, Elisa; Ricciarelli, Roberta; Villacorta, Luis; Azzi, Angelo; Meydani, Mohsen

    2017-01-02

    Curcumin, a polyphenol from turmeric (Curcuma longa), reduces inflammation, atherosclerosis, and obesity in several animal studies. In Ldlr(-/-) mice fed a high-fat diet (HFD), curcumin reduces plasma lipid levels, therefore contributing to a lower accumulation of lipids and to reduced expression of fatty acid transport proteins (CD36/FAT, FABP4/aP2) in peritoneal macrophages. In this study, we analyzed the molecular mechanisms by which curcumin (500, 1000, 1500 mg/kg diet, for 4 months) may influence plasma and tissue lipid levels in Ldlr(-/-) mice fed an HFD. In liver, HFD significantly suppressed cAMP levels, and curcumin restored almost normal levels. Similar trends were observed in adipose tissues, but not in brain, skeletal muscle, spleen, and kidney. Treatment with curcumin increased phosphorylation of CREB in liver, what may play a role in regulatory effects of curcumin in lipid homeostasis. In cell lines, curcumin increased the level of cAMP, activated the transcription factor CREB and the human CD36 promoter via a sequence containing a consensus CREB response element. Regulatory effects of HFD and Cur on gene expression were observed in liver, less in skeletal muscle and not in brain. Since the cAMP/protein kinase A (PKA)/CREB pathway plays an important role in lipid homeostasis, energy expenditure, and thermogenesis by increasing lipolysis and fatty acid β-oxidation, an increase in cAMP levels induced by curcumin may contribute to its hypolipidemic and anti-atherosclerotic effects. © 2016 BioFactors, 43(1):42-53, 2017.

  3. Muscarinic receptor subtypes in human and rat colon smooth muscle.

    PubMed

    Gómez, A; Martos, F; Bellido, I; Marquez, E; Garcia, A J; Pavia, J; Sanchez de la Cuesta, F

    1992-06-09

    Muscarinic receptor subtypes in human and rat colon smooth muscle homogenates were characterized with [3H]N-methylscopolamine ([3H]NMS) by ligand binding studies. [3H]NMS saturation experiments show the existence of a homogeneous population of non-interacting binding sites with similar affinity (KD values of 1.38 +/- 0.20 nM in human colon smooth muscle and 1.48 +/- 0.47 nM in rat colon smooth muscle) and with Hill slopes close to unity in both samples of tissue. However, a significant (P less than 0.01) increase in muscarinic receptor density (Bmax) is found in human colon (29.9 +/- 2.9 fmol/mg protein) compared with rat colon (17.2 +/- 1.5 fmol/mg protein). Inhibition of [3H]NMS binding by non-labelled compounds shows the following order in human colon: atropine greater than AF-DX 116 greater than pirenzepine. Whereas in rat colon the rank order obtained is atropine greater than pirenzepine greater than AF-DX 116. Atropine and pirenzepine bind to a homogeneous population of binding sites, although pirenzepine shows higher affinity to bind to the sites present in rat colon (Ki = 1.08 +/- 0.08 microM) than those in human colon (Ki = 1.74 +/- 0.02 microM) (P less than 0.05). Similarly, IC50 values obtained in AF-DX 116 competition experiments were significantly different (P less than 0.01) in human colon (IC50 = 1.69 +/- 0.37 microM) than in rat colon (IC50 = 3.78 +/- 0.75 microM). Unlike atropine and pirenzepine, the inhibition of [3H]NMS binding by AF-DX 116 did not yield a simple mass-action binding curve (nH less than 1, P less than 0.01) suggesting the presence of more than one subtype of muscarinic receptor in both species. Computer analysis of these curves with a two binding site model suggests the presence of two populations of receptor. The apparent Ki1 value for the high affinity binding site is 0.49 +/- 0.07 microM for human colon smooth muscle and 0.33 +/- 0.05 microM for rat colon smooth muscle. The apparent Ki2 for the low affinity binding site is 8

  4. Autoradiographic visualization of muscarinic receptors in human bronchi

    SciTech Connect

    van Koppen, C.J.; Blankesteijn, W.M.; Klaassen, A.B.; Rodrigues de Miranda, J.F.; Beld, A.J.; van Ginneken, C.A.

    1988-02-01

    To visualize muscarinic receptors in human bronchi, the stripping film method was used which permits direct autoradiographic localization of tissue labeling. Cryostate sections of human bronchi were fixed in 0.5% glutaraldehyde in Krebs-Ringer buffer, pH 7.0 for 30 min at 0/sup 0/C, washed in Krebs-Ringer buffer for 20 min at 0/sup 0/C and incubated with (-)-(/sup 3/H)Quinuclidinyl benzilate ((-)-(/sup 3/H)QNB) for 90 min at 37/sup 0/C. Specific (-)-(/sup 3/H)QNB binding to tissue sections was saturable (receptor density of 0.14 +/- 0.03 fmol/tissue section) and of high affinity (Kd of 40 +/- 9 pM). For autoradiography, labeled tissue sections were covered with stripping film and exposed for 5 months. Muscarinic receptors in human bronchi were located predominantly in submucosal glands and parasympathetic ganglia. There was less labeling in smooth muscle cells and nerve bundles. Epithelium and blood vessels located within the bronchial wall were devoid of specific labeling.

  5. Opiate receptor blockade on human granulosa cells inhibits VEGF release.

    PubMed

    Lunger, Fabian; Vehmas, Anni P; Fürnrohr, Barbara G; Sopper, Sieghart; Wildt, Ludwig; Seeber, Beata

    2016-03-01

    The objectives of this study were to determine whether the main opioid receptor (OPRM1) is present on human granulosa cells and if exogenous opiates and their antagonists can influence granulosa cell vascular endothelial growth factor (VEGF) production via OPRM1. Granulosa cells were isolated from women undergoing oocyte retrieval for IVF. Complementary to the primary cells, experiments were conducted using COV434, a well-characterized human granulosa cell line. Identification and localization of opiate receptor subtypes was carried out using Western blot and flow cytometry. The effect of opiate antagonist on granulosa cell VEGF secretion was assessed by enzyme-linked immunosorbent assay. For the first time, the presence of OPRM1 on human granulosa cells is reported. Blocking of opiate signalling using naloxone, a specific OPRM1 antagonist, significantly reduced granulosa cell-derived VEGF levels in both COV434 and granulosa-luteal cells (P < 0.01). The presence of opiate receptors and opiate signalling in granulosa cells suggest a possible role in VEGF production. Targeting this signalling pathway could prove promising as a new clinical option in the prevention and treatment of ovarian hyperstimulation syndrome.

  6. Expression of growth hormone receptor in the human brain.

    PubMed

    Castro, J R; Costoya, J A; Gallego, R; Prieto, A; Arce, V M; Señarís, R

    2000-03-10

    This study was designed to investigate the presence of growth hormone receptor (GHR) expression in the human brain tissue, both normal and tumoral, as well as in the human glioblastoma cell line U87MG. Reverse transcription-polymerase chain reaction revealed the presence of GHR mRNA in all brain samples investigated and in U87MG cells. GHR immunoreactivity was also detected in this cell line using both immunocytochemistry and western blotting. All together, our data demonstrate the existence of GHR expression within the central nervous system (CNS), thus supporting a possible role for GH in the CNS physiology.

  7. Confrontational scavenging as a possible source for language and cooperation

    PubMed Central

    2011-01-01

    The emergence of language and the high degree of cooperation found among humans seems to require more than a straightforward enhancement of primate traits. Some triggering episode unique to human ancestors was likely necessary. Here it is argued that confrontational scavenging was such an episode. Arguments for and against an established confrontational scavenging niche are discussed, as well as the probable effects of such a niche on language and co-operation. Finally, several possible directions for future research are suggested. PMID:21933413

  8. Human Diversity in a Cell Surface Receptor that Inhibits Autophagy.

    PubMed

    Chaudhary, Anu; Leite, Mara; Kulasekara, Bridget R; Altura, Melissa A; Ogahara, Cassandra; Weiss, Eli; Fu, Wenqing; Blanc, Marie-Pierre; O'Keeffe, Michael; Terhorst, Cox; Akey, Joshua M; Miller, Samuel I

    2016-07-25

    Mutations in genes encoding autophagy proteins have been associated with human autoimmune diseases, suggesting that diversity in autophagy responses could be associated with disease susceptibility or severity. A cellular genome-wide association study (GWAS) screen was performed to explore normal human diversity in responses to rapamycin, a microbial product that induces autophagy. Cells from several human populations demonstrated variability in expression of a cell surface receptor, CD244 (SlamF4, 2B4), that correlated with changes in rapamycin-induced autophagy. High expression of CD244 and receptor activation with its endogenous ligand CD48 inhibited starvation- and rapamycin-induced autophagy by promoting association of CD244 with the autophagy complex proteins Vps34 and Beclin-1. The association of CD244 with this complex reduced Vps34 lipid kinase activity. Lack of CD244 is associated with auto-antibody production in mice, and lower expression of human CD244 has previously been implicated in severity of human rheumatoid arthritis and systemic lupus erythematosus, indicating that increased autophagy as a result of low levels of CD244 may alter disease outcomes.

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

    PubMed

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

    2013-11-15

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

  10. Functional atrial natriuretic peptide receptor in human adrenal tumor

    SciTech Connect

    Shionoiri, H.; Hirawa, N.; Takasaki, I.; Ishikawa, Y.; Oda, H.; Minamisawa, K.; Sugimoto, K.; Matsukawa, T.; Ueda, S.; Miyajima, E.

    1989-01-01

    The effects of synthetic human atrial natriuretic peptide (ANP) on the release of catecholamines, aldosterone, or cortisol were observed in human adrenal tumors obtained surgically from patients with pheochromocytoma, primary aldosteronism, or Cushing's syndrome, respectively. Each tumor tissue or adjacent normal cortical tissue was sectioned into slices, which were incubated in medium-199 in the presence or absence of adrenocorticotrophin (ACTH) and ANP. The amounts of epinephrine, norepinephrine, aldosterone, or cortisol released into the medium were measured. Existence of ANP receptors on the adrenal tissues was examined by binding assays, affinity labeling, and immunohistochemistry. Release of catecholamines from pheochromocytoma tissues was inhibited by ANP, and the presence of the ANP receptor on pheochromocytoma was further demonstrated by both binding assays and affinity labeling; Scatchard analysis revealed a single class of binding sites for ANP with a Kd of 1.0 nM and a Bmax of 0.4 pmol/mg of protein and the molecular size was estimated as 140 and a 70 kDa under nonreducing and reducing conditions, respectively. The presence of ANP receptors in pheochromocytoma was demonstrated by immunohistochemistry. ANP inhibited both basal and ACTH-stimulated aldosterone secretion in the slices of normal cortex, and localization of ANP receptors in zona glomerulosa cells was also demonstrated. However, ANP did not inhibit basal and ACTH-stimulated aldosterone and cortisol secretion in both tissue slices from aldosteronoma and Cushing's adenoma. Consistent with these observations, the absence of ANP receptors in adenoma tissues was determined by binding assays, affinity labeling, and immunohistochemistry.

  11. Energy scavenging sources for biomedical sensors.

    PubMed

    Romero, E; Warrington, R O; Neuman, M R

    2009-09-01

    Energy scavenging has increasingly become an interesting option for powering electronic devices because of the almost infinite lifetime and the non-dependence on fuels for energy generation. Moreover, the rise of wireless technologies promises new applications in medical monitoring systems, but these still face limitations due to battery lifetime and size. A trade-off of these two factors has typically governed the size, useful life and capabilities of an autonomous system. Energy generation from sources such as motion, light and temperature gradients has been established as commercially viable alternatives to batteries for human-powered flashlights, solar calculators, radio receivers and thermal-powered wristwatches, among others. Research on energy harvesting from human activities has also addressed the feasibility of powering wearable or implantable systems. Biomedical sensors can take advantage of human-based activities as the energy source for energy scavengers. This review describes the state of the art of energy scavenging technologies for powering sensors and instrumentation of physiological variables. After a short description of the human power and the energy generation limits, the different transduction mechanisms, recent developments and challenges faced are reviewed and discussed.

  12. Intrinsic Relative Activities of Opioid Agonists in Activating Gα proteins and Internalizing Receptor: Differences between Human and Mouse Receptors

    PubMed Central

    DiMattio, Kelly M.; Ehlert, Frederick J.; Liu-Chen, Lee-Yuan

    2015-01-01

    Several investigators recently identified biased opioid receptor (KOP receptor) agonists. However, no comprehensive study of the functional selectivity of available KOP receptor agonists at the human and mouse KOP receptors (hKOP receptor and mKOP receptor, respectively) has been published. Here we examined the ability of over 20 KOP receptor agonists to activate G proteins and to internalize the receptor. Clonal neuro-2a mouse neuroblastoma (N2a) cells stably transfected with the hKOP receptor or mKOP receptor were used. We employed agonist-induced [35S]GTPγS binding and KOP receptor internalization as measures of activation of G protein and β-arrestin pathways, respectively. The method of Ehlert and colleagues was used to quantify intrinsic relative activities at G protein activation (RAi−G) and receptor internalization (RAi−I) and the degree of functional selectivity between the two [Log RAi−G − Log RAi−I, RAi−G/RAi−I and bias factor]. The parameter, RAi, represents a relative estimate of agonist affinity for the active receptor state that elicits a given response. The endogenous ligand dynorphin A (1–17) was designated as the balanced ligand with a bias factor of 1. Interestingly, we found that there were species differences in functional selectivity. The most striking differences were for 12-epi-salvinorin A, U69,593, and ICI-199,441. 12-Epi-salvinorin A was highly internalization-biased at the mKOP receptor, but apparently G protein-biased at hKOP receptor. U69,593 was much more internalization-biased at mKOP receptor than hKOP receptor. ICI199,441 showed internalization-biased at the mKOP receptor and G protein-biased at the hKOP receptor. Possible mechanisms for the observed species differences are discussed. PMID:26057692

  13. Characterization of a scavenger receptor cysteine-rich-domain-containing protein of the starfish, Asterina pectinifera: ApSRCR1 acts as an opsonin in the larval and adult innate immune systems.

    PubMed

    Furukawa, Ryohei; Matsumoto, Midori; Kaneko, Hiroyuki

    2012-01-01

    Proteins containing a scavenger receptor cysteine-rich (SRCR) domain (SRCR proteins) play an important role in the innate immune system of various metazoan animals. In the starfish Asterina pectinifera, mesenchyme cells and coelomocytes govern the two distinct innate immune systems of the larvae and adults, respectively. Here we identify a cDNA encoding a protein containing nine SRCR domains termed ApSRCR1, and present characterization of the molecular structure, expression, subcellular localization and function of ApSRCR1 protein during ontogenesis of this animal. ApSRCR1 protein is a membrane-type protein with a predicted molecular mass of approximately 120 kDa. During ontogenesis, ApSRCR1 protein is de novo synthesized and localizes to cytoplasmic vesicles in both mesenchyme cells and coelomocytes without translation of maternal mRNA; however, the net production and modification by N-glycosylation of ApSRCR1 protein differs in each cell type. In both types of cell, functional inhibition of ApSRCR1 protein leads to incompetent bacterial clearance and failure of aggregate formation. However, this inhibitory effect is weaker in the mesenchyme cells than in the coelomocytes. In the bacteria-sensitized adult, ApSRCR1 protein is up-regulated and digested to enable its secretion into the coelomic fluid. This secreted form of ApSRCR1 protein can apparently bind to bacteria. Overall, we show that ApSRCR1 protein is finely regulated for expression not only during development but also in a sensitive innate immunological situation, and thereupon acts as an opsonin for bacteria to different extents in the larvae and adults of A. pectinifera. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. A Library of Infectious Hepatitis C Viruses with Engineered Mutations in the E2 Gene Reveals Growth-Adaptive Mutations That Modulate Interactions with Scavenger Receptor Class B Type I.

    PubMed

    Zuiani, Adam; Chen, Kevin; Schwarz, Megan C; White, James P; Luca, Vincent C; Fremont, Daved H; Wang, David; Evans, Matthew J; Diamond, Michael S

    2016-12-01

    While natural hepatitis C virus (HCV) infection results in highly diverse quasispecies of related viruses over time, mutations accumulate more slowly in tissue culture, in part because of the inefficiency of replication in cells. To create a highly diverse population of HCV particles in cell culture and identify novel growth-enhancing mutations, we engineered a library of infectious HCV with all codons represented at most positions in the ectodomain of the E2 gene. We identified many putative growth-adaptive mutations and selected nine highly represented E2 mutants for further study: Q412R, T416R, S449P, T563V, A579R, L619T, V626S, K632T, and L644I. We evaluated these mutants for changes in particle-to-infectious-unit ratio, sensitivity to neutralizing antibody or CD81 large extracellular loop (CD81-LEL) inhibition, entry factor usage, and buoyant density profiles. Q412R, T416R, S449P, T563V, and L619T were neutralized more efficiently by anti-E2 antibodies and T416R, T563V, and L619T by CD81-LEL. Remarkably, all nine variants showed reduced dependence on scavenger receptor class B type I (SR-BI) for infection. This shift from SR-BI usage did not correlate with a change in the buoyant density profiles of the variants, suggesting an altered E2-SR-BI interaction rather than changes in the virus-associated lipoprotein-E2 interaction. Our results demonstrate that residues influencing SR-BI usage are distributed across E2 and support the development of large-scale mutagenesis studies to identify viral variants with unique functional properties.

  15. Bilirubin inhibits the up-regulation of inducible nitric oxide synthase by scavenging reactive oxygen species generated by the toll-like receptor 4-dependent activation of NADPH oxidase.

    PubMed

    Idelman, Gila; Smith, Darcey L H; Zucker, Stephen D

    2015-08-01

    It has been previously shown that bilirubin prevents the up-regulation of inducible nitric oxide synthase (iNOS) in response to LPS. The present study examines whether this effect is exerted through modulation of Toll-Like Receptor-4 (TLR4) signaling. LPS-stimulated iNOS and NADPH oxidase (Nox) activity in RAW 264.7 murine macrophages was assessed by measuring cellular nitrate and superoxide ( [Formula: see text] ) production, respectively. The generation of both nitrate and [Formula: see text] in response to LPS was suppressed by TLR4 inhibitors, indicating that activation of iNOS and Nox is TLR4-dependent. While treatment with superoxide dismutase (SOD) and bilirubin effectively abolished LPS-mediated [Formula: see text] production, hydrogen peroxide and nitrate release were inhibited by bilirubin and PEG-catalase, but not SOD, supporting that iNOS activation is primarily dependent upon intracellular H2O2. LPS treatment increased nuclear translocation of the redox-sensitive transcription factor Hypoxia Inducible Factor-1α (HIF-1α), an effect that was abolished by bilirubin. Cells transfected with murine iNOS reporter constructs in which the HIF-1α-specific hypoxia response element was disrupted exhibited a blunted response to LPS, supporting that HIF-1α mediates Nox-dependent iNOS expression. Bilirubin, but not SOD, blocked the cellular production of interferon-β, while interleukin-6 production remained unaffected. These data support that bilirubin inhibits the TLR4-mediated up-regulation of iNOS by preventing activation of HIF-1α through scavenging of Nox-derived reactive oxygen species. Bilirubin also suppresses interferon-β release via a ROS-independent mechanism. These findings characterize potential mechanisms for the anti-inflammatory effects of bilirubin.

  16. High Density Lipoprotein Stimulated Migration of Macrophages Depends on the Scavenger Receptor Class B, Type I, PDZK1 and Akt1 and Is Blocked by Sphingosine 1 Phosphate Receptor Antagonists

    PubMed Central

    Al-Jarallah, Aishah; Chen, Xing; González, Leticia; Trigatti, Bernardo L.

    2014-01-01

    HDL carries biologically active lipids such as sphingosine-1-phosphate (S1P) and stimulates a variety of cell signaling pathways in diverse cell types, which may contribute to its ability to protect against atherosclerosis. HDL and sphingosine-1-phosphate receptor agonists, FTY720 and SEW2871 triggered macrophage migration. HDL-, but not FTY720-stimulated migration was inhibited by an antibody against the HDL receptor, SR-BI, and an inhibitor of SR-BI mediated lipid transfer. HDL and FTY720-stimulated migration was also inhibited in macrophages lacking either SR-BI or PDZK1, an adaptor protein that binds to SR-BI's C-terminal cytoplasmic tail. Migration in response to HDL and S1P receptor agonists was inhibited by treatment of macrophages with sphingosine-1-phosphate receptor type 1 (S1PR1) antagonists and by pertussis toxin. S1PR1 activates signaling pathways including PI3K-Akt, PKC, p38 MAPK, ERK1/2 and Rho kinases. Using selective inhibitors or macrophages from gene targeted mice, we demonstrated the involvement of each of these pathways in HDL-dependent macrophage migration. These data suggest that HDL stimulates the migration of macrophages in a manner that requires the activities of the HDL receptor SR-BI as well as S1PR1 activity. PMID:25188469

  17. Characterization of interleukin-8 receptors in non-human primates

    SciTech Connect

    Alvarez, V.; Coto, E.; Gonzalez-Roces, S.; Lopez-Larrea, C.

    1996-09-01

    Interleukin-8 is a chemokine with a potent neutrophil chemoatractant activity. In humans, two different cDNAs encoding human IL8 receptors designated IL8RA and IL8RB have been cloned. IL8RA binds IL8, while IL8RB binds IL8 as well as other {alpha}-chemokines. Both human IL8Rs are encoded by two genes physically linked on chromosome 2. The IL8RA and IL8RB genes have open reading frames (ORF) lacking introns. By direct sequencing of the polymerase chain reaction products, we sequenced the IL8R genes of cell lines from four non-human primates: chimpanzee, gorilla, orangutan, and macaca. The IL8RB encodes an ORF in the four non-human primates, showing 95%-99% similarity to the human IL8RB sequence. The IL8RA homologue in gorilla and chimpanzee consisted of two ORF 98%-99% identical to the human sequence. The macaca and orangutan IL8RA homologues are pseudogenes: a 2 base pair insertion generated a sequence with several stop codons. In addition, we describe the physical linkage of these genes in the four non-human primates and discuss the evolutionary implications of these findings. 25 refs., 5 figs., 3 tabs.

  18. Competitive antagonism at thromboxane receptors in human platelets.

    PubMed Central

    Armstrong, R. A.; Jones, R. L.; Peesapati, V.; Will, S. G.; Wilson, N. H.

    1985-01-01