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Yasuda D, Hamano F, Masuda K, Dahlström M, Kobayashi D, Sato N, Hamakubo T, Shimizu T, Ishii S. Inverse agonism of lysophospholipids with cationic head groups at Gi-coupled receptor GPR82. Eur J Pharmacol 2023; 954:175893. [PMID: 37392830 DOI: 10.1016/j.ejphar.2023.175893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/20/2023] [Accepted: 06/28/2023] [Indexed: 07/03/2023]
Abstract
GPR82 is an orphan G protein-coupled receptor (GPCR) that has been implicated in lipid storage in mouse adipocytes. However, the intracellular signaling as well as the specific ligands of GPR82 remain unknown. GPR82 is closely related to GPR34, a GPCR for the bioactive lipid molecule lysophosphatidylserine. In this study, we screened a lipid library using GPR82-transfected cells to search for ligands that act on GPR82. By measuring cyclic adenosine monophosphate levels, we found that GPR82 is an apparently constitutively active GPCR that leads to Gi protein activation. In addition, edelfosine (1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine), an artificial lysophospholipid with a cationic head group that exerts antitumor activity, inhibited the Gi protein activation by GPR82. Two endogenous lysophospholipids with cationic head groups, lysophosphatidylcholine (1-oleoyl-sn-glycero-3-phosphocholine) and lysophosphatidylethanolamine (1-oleoyl-sn-glycero-3-phosphoethanolamine), also exhibited GPR82 inhibitory activity, albeit weaker than edelfosine. Förster resonance energy transfer imaging analysis consistently demonstrated that Gi protein-coupled GPR82 has an apparent constitutive activity that is edelfosine-sensitive. Consistent data were obtained from GPR82-mediated binding analysis of guanosine-5'-O-(3-thiotriphosphate) to cell membranes. Furthermore, in GPR82-transfected cells, edelfosine inhibited insulin-induced extracellular signal-regulated kinase activation, like compounds that function as inverse agonists at other GPCRs. Therefore, edelfosine is likely to act as an inverse agonist of GPR82. Finally, GPR82 expression inhibited adipocyte lipolysis, which was abrogated by edelfosine. Our findings suggested that the cationic lysophospholipids edelfosine, lysophosphatidylcholine and lysophosphatidylethanolamine are novel inverse agonists for Gi-coupled GPR82, which is apparently constitutively active, and has the potential to exert lipolytic effects through GPR82.
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Affiliation(s)
- Daisuke Yasuda
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Fumie Hamano
- Life Sciences Core Facility, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kazuyuki Masuda
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | | | - Daiki Kobayashi
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Nana Sato
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Takao Hamakubo
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Takao Shimizu
- Department of Lipid Life Science, National Center for Global Health and Medicine, Tokyo, Japan; Institute of Microbial Chemistry, Tokyo, Japan
| | - Satoshi Ishii
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan.
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Limbach MN, Antevska A, Oluwatoba DS, Gray ALH, Carroll XB, Hoffmann CM, Wang X, Voehler MW, Steren CA, Do TD. Atomic View of Aqueous Cyclosporine A: Unpacking a Decades-Old Mystery. J Am Chem Soc 2022; 144:12602-12607. [PMID: 35786958 DOI: 10.1021/jacs.2c01743] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An atomic view of a main aqueous conformation of cyclosporine A (CycA), an important 11-amino-acid macrocyclic immunosuppressant, is reported. For decades, it has been a grand challenge to determine the conformation of free CycA in an aqueous-like solution given its poor water solubility. Using a combination of X-ray and single-crystal neutron diffraction, we unambiguously resolve a unique conformer (A1) with a novel cis-amide between residues 11 and 1 and two water ligands that stabilize hydrogen bond networks. NMR spectroscopy and titration experiments indicate that the novel conformer is as abundant as the closed conformer in 90/10 (v/v) methanol/water and is the main conformer at 10/90 methanol/water. Five other conformers were also detected in 90/10 methanol/water, one in slow exchange with A1, another one in slow exchange with the closed form and three minor ones, one of which contains two cis amides Abu2-Sar3 and MeBmt1-MeVal11. These conformers help better understand the wide spectrum of membrane permeability observed for CycA analogues and, to some extent, the binding of CycA to protein targets.
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Affiliation(s)
- Miranda N Limbach
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Aleksandra Antevska
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Damilola S Oluwatoba
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Amber L H Gray
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Xian B Carroll
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Christina M Hoffmann
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Xiaoping Wang
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Markus W Voehler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Carlos A Steren
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Thanh D Do
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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3
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Hattori Y, Seifert R. Pharmacological Characterization of Human Histamine Receptors and Histamine Receptor Mutants in the Sf9 Cell Expression System. Handb Exp Pharmacol 2017; 241:63-118. [PMID: 28233175 PMCID: PMC7120522 DOI: 10.1007/164_2016_124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A large problem of histamine receptor research is data heterogeneity. Various experimental approaches, the complex signaling pathways of mammalian cells, and the use of different species orthologues render it difficult to compare and interpret the published results. Thus, the four human histamine receptor subtypes were analyzed side-by-side in the Sf9 insect cell expression system, using radioligand binding assays as well as functional readouts proximal to the receptor activation event (steady-state GTPase assays and [35S]GTPγS assays). The human H1R was co-expressed with the regulators of G protein signaling RGS4 or GAIP, which unmasked a productive interaction between hH1R and insect cell Gαq. By contrast, functional expression of the hH2R required the generation of an hH2R-Gsα fusion protein to ensure close proximity of G protein and receptor. Fusion of hH2R to the long (GsαL) or short (GsαS) splice variant of Gαs resulted in comparable constitutive hH2R activity, although both G protein variants show different GDP affinities. Medicinal chemistry studies revealed profound species differences between hH1R/hH2R and their guinea pig orthologues gpH1R/gpH2R. The causes for these differences were analyzed by molecular modeling in combination with mutational studies. Co-expression of the hH3R with Gαi1, Gαi2, Gαi3, and Gαi/o in Sf9 cells revealed high constitutive activity and comparable interaction efficiency with all G protein isoforms. A comparison of various cations (Li+, Na+, K+) and anions (Cl-, Br-, I-) revealed that anions with large radii most efficiently stabilize the inactive hH3R state. Potential sodium binding sites in the hH3R protein were analyzed by expressing specific hH3R mutants in Sf9 cells. In contrast to the hH3R, the hH4R preferentially couples to co-expressed Gαi2 in Sf9 cells. Its high constitutive activity is resistant to NaCl or GTPγS. The hH4R shows structural instability and adopts a G protein-independent high-affinity state. A detailed characterization of affinity and activity of a series of hH4R antagonists/inverse agonists allowed first conclusions about structure/activity relationships for inverse agonists at hH4R. In summary, the Sf9 cell system permitted a successful side-by-side comparison of all four human histamine receptor subtypes. This chapter summarizes the results of pharmacological as well as medicinal chemistry/molecular modeling approaches and demonstrates that these data are not only important for a deeper understanding of HxR pharmacology, but also have significant implications for the molecular pharmacology of GPCRs in general.
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Affiliation(s)
- Yuichi Hattori
- Department of Molecular and Medical Pharmacology, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Roland Seifert
- Institute of Pharmacology, Medical School of Hannover, Hannover, Germany
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4
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Baracco EE, Pietrocola F, Buqué A, Bloy N, Senovilla L, Zitvogel L, Vacchelli E, Kroemer G. Inhibition of formyl peptide receptor 1 reduces the efficacy of anticancer chemotherapy against carcinogen-induced breast cancer. Oncoimmunology 2016; 5:e1139275. [PMID: 27471610 DOI: 10.1080/2162402x.2016.1139275] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/03/2016] [Indexed: 01/21/2023] Open
Abstract
The loss-of-function mutation of formyl peptide receptor 1 (FPR1) has a negative impact on the progression-free and overall survival of breast cancer patients treated with anthracycline-based adjuvant chemotherapy. This effect may be attributed to the fact that chemotherapy-induced antitumor immunity requires FPR1 and that such anticancer immune responses are responsible for the long-term effects of chemotherapy. Here, we investigated the possible contribution of FPR1 to the efficacy of a combination of mitoxantrone (MTX) and cyclophosphamide (CTX) for the treatment of hormone-induced breast cancer. Breast cancer induced by a combination of medroxyprogesterone acetate (MPA) and 7,12-Dimethylbenz[a]anthracene (DMBA) could be successfully treated with MTX plus CTX in thus far that tumor growth was retarded and overall survival was extended (as compared to vehicle-only treated controls). However, the therapeutic efficacy of the combination therapy was completely abolished when FPR1 receptors were blocked by means of cyclosporin H (CsH). Future genetic studies on neoadjuvant chemotherapy-treated breast cancers are warranted to validate these findings at the clinical level.
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Affiliation(s)
- Elisa E Baracco
- Gustave Roussy Cancer Campus, Villejuif, France; INSERM, Paris, France; Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Faculté de Médecine, Université Paris-Saclay, Kremlin-Bicêtre, France
| | - Federico Pietrocola
- Gustave Roussy Cancer Campus, Villejuif, France; INSERM, Paris, France; Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Université Pierre et Marie Curie, Paris, France
| | - Aitziber Buqué
- Gustave Roussy Cancer Campus, Villejuif, France; INSERM, Paris, France; Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Université Pierre et Marie Curie, Paris, France
| | - Norma Bloy
- Gustave Roussy Cancer Campus, Villejuif, France; INSERM, Paris, France; Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Faculté de Médecine, Université Paris-Saclay, Kremlin-Bicêtre, France
| | - Laura Senovilla
- Gustave Roussy Cancer Campus, Villejuif, France; INSERM, Paris, France; Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Université Pierre et Marie Curie, Paris, France
| | - Laurence Zitvogel
- Gustave Roussy Cancer Campus, Villejuif, France; Faculté de Médecine, Université Paris-Saclay, Kremlin-Bicêtre, France; INSERM, Villejuif, France; Center of Clinical Investigations in Biotherapies of Cancer (CICBT) 507, Villejuif, France
| | - Erika Vacchelli
- Gustave Roussy Cancer Campus, Villejuif, France; INSERM, Paris, France; Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Université Pierre et Marie Curie, Paris, France
| | - Guido Kroemer
- Gustave Roussy Cancer Campus, Villejuif, France; INSERM, Paris, France; Equipe 11 labellisée par la Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Université Pierre et Marie Curie, Paris, France; Metabolomics and Cell Biology Platforms, Gustave Roussy Cancer Campus, Villejuif, France; Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France; Karolinska Institute, Department of Women's and Children's Health, Karolinska University Hospital, Stockholm, Sweden
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5
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Fugelli K. Effects of sodium ions on rat thyrocyte (FRTL-5 cells) swelling- and thyrotropin-activated taurine efflux dependent on cAMP and Epac. Amino Acids 2015; 48:763-777. [PMID: 26553454 DOI: 10.1007/s00726-015-2124-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 10/26/2015] [Indexed: 11/25/2022]
Abstract
Cellular osmolyte release is important in preventing water accumulation and swelling. However, the signaling pathways that detect volume increase and activate solute efflux are still not fully understood. We investigated efflux activation of the osmolyte taurine which is actively accumulated in rat thyrocytes (FRTL-5). Efflux of accumulated [(3)H]taurine was stimulated by cellular swelling and thyrotropin (TSH). These effects were significantly diminished in cells having reduced TSH receptor concentrations. Phosphodiesterase inhibitors (IBMX, Rolipram) enhanced both responses. An analog of forskolin (FSK; 7-deacetyl-7-[O-(N-methylpiperazino)-γ-butyryl] dihydrochloride) and an analog of cAMP, specific for activating exchange protein activated directly by cAMP (Epac; 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate, acetoxymethyl ester), significantly stimulated [(3)H]taurine efflux. A cAMP analog specific for activating protein kinase A (PKA; N6-benzoyladenosine-3',5'-cyclic monophosphate, acetoxymethyl ester) had no significant stimulatory effect on [(3)H]taurine efflux rate. The amiloride analog, 5-(N-ethyl-N-isopropyl)-amiloride, which inhibits a TSH-stimulated Na(+)/H(+) exchanger, enhanced (100 %) and ouabain inhibited (50 %) the TSH-stimulated [(3)H]taurine efflux rate. The effect of FSK on efflux was strongly potentiated by Na(+)-free iso-osmotic conditions and by osmolality/cell volume that affected also the db-cAMP-stimulated efflux. The TSH receptors and downstream elements of the signaling pathway comprising adenylyl cyclase, cAMP and Epac appeared to mediate the hormone-induced signal for [(3)H]taurine efflux from FRTL-5 cells. With less evidence, the cell volume/osmolality-induced [(3)H]taurine efflux cascade appeared to share some of the hormone signaling elements and to modulate the hormone signaling pathway at two levels through cellular Na(+).
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Affiliation(s)
- Kjell Fugelli
- Department of Biosciences, University of Oslo, POBox 1066, Blindern, 0316, Oslo, Norway.
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6
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Schepetkin IA, Khlebnikov AI, Kirpotina LN, Quinn MT. Antagonism of human formyl peptide receptor 1 with natural compounds and their synthetic derivatives. Int Immunopharmacol 2015; 37:43-58. [PMID: 26382576 DOI: 10.1016/j.intimp.2015.08.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 08/25/2015] [Accepted: 08/28/2015] [Indexed: 12/18/2022]
Abstract
Formyl peptide receptor 1 (FPR1) regulates a wide variety of neutrophil functional responses and plays an important role in inflammation and the pathogenesis of various diseases. To date, a variety of natural and synthetic molecules have been identified as FPR1 ligands. Here, we review current knowledge on natural products and natural product-inspired small molecules reported to antagonize and/or inhibit the FPR1-mediated responses. Based on this literature, additional screening of selected commercially available natural compounds for their ability to inhibit fMLF-induced Ca(2+) mobilization in human neutrophils and FPR1 transfected HL-60 cells, and pharmacophore modeling, natural products with potential as FPR1 antagonists are considered and discussed in this review. The identification and characterization of natural products that antagonize FPR1 activity may have potential for the development of novel therapeutics to limit or alter the outcome of inflammatory processes.
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Affiliation(s)
- Igor A Schepetkin
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, United States
| | - Andrei I Khlebnikov
- Department of Biotechnology and Organic Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia; Department of Chemistry, Altai State Technical University, Barnaul, Russia
| | - Liliya N Kirpotina
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, United States
| | - Mark T Quinn
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, United States.
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7
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Werner K, Kälble S, Wolter S, Schneider EH, Buschauer A, Neumann D, Seifert R. Flow cytometric analysis with a fluorescently labeled formyl peptide receptor ligand as a new method to study the pharmacological profile of the histamine H2 receptor. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:1039-52. [PMID: 26021872 DOI: 10.1007/s00210-015-1133-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/18/2015] [Indexed: 01/14/2023]
Abstract
The histamine H2 receptor (H2R) is a Gs protein-coupled receptor. Its activation leads to increases in the second messenger adenosine-3',5'-cyclic monophosphate (cAMP). Presently, several systems are established to characterize the pharmacological profile of the H2R, mostly requiring radioactive material, animal models, or human blood cells. This prompted us to establish a flow cytometric analysis with a fluorescently labeled formyl peptide receptor (FPR) ligand in order to investigate the H2R functionally and pharmacologically. First, we stimulated U937 promonocytes, which mature in a cAMP-dependent fashion upon H2R activation, with histamine (HA) or selective H2R agonists and measured increases in cAMP concentrations by mass spectrometry. Next, indicative for the maturation of U937 promonocytes, we assessed the FPR expression upon incubation with HA or H2R agonists. FPR expression was measured either indirectly by formyl peptide-induced changes in intracellular calcium concentrations ([Ca(2+)]i) or directly with the fluorescein-labeled FPR ligand fNleLFNleYK-Fl. HA and H2R agonists concentration-dependently induced FPR expression, and potencies and efficacies of fMLP-induced increases in [Ca(2+)]i and FPR density correlated linearly. Accordingly, flow cytometric analysis of FPR expression constitutes a simple, inexpensive, sensitive, and reliable method to characterize the H2R pharmacologically. Furthermore, we evaluated FPR expression at the mRNA level. Generally, quantitative real-time polymerase chain reaction confirmed functional data. Additionally, our study supports the concept of functional selectivity of the H2R, since we observed dissociations in the efficacies of HA and H2R agonists in cAMP accumulation and FPR expression.
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Affiliation(s)
- Kristin Werner
- Institute of Pharmacology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625, Hannover, Germany
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8
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Modulation of GPCRs by monovalent cations and anions. Naunyn Schmiedebergs Arch Pharmacol 2014; 388:363-80. [DOI: 10.1007/s00210-014-1073-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
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9
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Werner K, Neumann D, Seifert R. Analysis of the histamine H2-receptor in human monocytes. Biochem Pharmacol 2014; 92:369-79. [DOI: 10.1016/j.bcp.2014.08.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/24/2014] [Accepted: 08/25/2014] [Indexed: 01/16/2023]
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10
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Angiostatin inhibits activation and migration of neutrophils. Cell Tissue Res 2013; 355:375-96. [PMID: 24297047 DOI: 10.1007/s00441-013-1753-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 10/30/2013] [Indexed: 01/10/2023]
Abstract
There is a critical need to identify molecules that modulate the biology of neutrophils because activated neutrophils, though necessary for host defense, cause exuberant tissue damage through production of reactive oxygen species and increased lifespan. Angiostatin, an endogenous anti-angiogenic cleavage product of plasminogen, binds to integrin αvβ3, ATP synthase and angiomotin and its expression is increased in inflammatory conditions. We test the hypothesis that angiostatin inhibits neutrophil activation, induces apoptosis and blocks recruitment in vivo and in vitro. The data show immuno-reactivity for plasminogen/angiostatin in resting neutrophils. Angiostatin conjugated to FITC revealed that angiostatin was endocytozed by activated mouse and human neutrophils in a lipid raft-dependent fashion. Co-immunoprecipitation of human neutrophil lysates, confocal microscopy of isolated mouse and human neutrophils and functional blocking experiments showed that angiostatin complexes with flotillin-1 along with integrin αvβ3 and ATP synthase. Angiostatin inhibited fMLP-induced neutrophil polarization, as well as caused inhibition of hsp-27 phosphorylation and stabilization of microtubules. Angiostatin treatment, before or after LPS-induced neutrophil activation, inhibited phosphorylation of p38 and p44/42 MAPKs, abolished reactive oxygen species production and released the neutrophils from suppressed apoptosis, as indicated by expression of activated caspase-3 and morphological evidence of apoptosis. Finally, intravital microscopy and myeloperoxidase assay showed inhibition of neutrophil recruitment in post-capillary venules of TNFα-treated cremaster muscle in mouse. These in vitro and in vivo data demonstrate angiostatin as a broad deactivator and silencer of neutrophils and an inhibitor of their migration. These data potentially open new avenues for the development of anti-inflammatory drugs.
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11
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Mitchell MJ, King MR. Shear-induced resistance to neutrophil activation via the formyl peptide receptor. Biophys J 2012; 102:1804-14. [PMID: 22768936 DOI: 10.1016/j.bpj.2012.03.053] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 03/20/2012] [Accepted: 03/22/2012] [Indexed: 12/28/2022] Open
Abstract
The application of fluid shear stress on leukocytes is critical for physiological functions including initial adhesion to the endothelium, the formation of pseudopods, and migration into tissues. The formyl peptide receptor (FPR) on neutrophils, which binds to formyl-methionyl-leucyl-phenylalanine (fMLP) and plays a role in neutrophil chemotaxis, has been implicated as a fluid shear stress sensor that controls pseudopod formation. The role of shear forces on earlier indicators of neutrophil activation, such as L-selectin shedding and α(M)β(2) integrin activation, remains unclear. Here, human neutrophils exposed to uniform shear stress (0.1-4.0 dyn/cm(2)) in a cone-and-plate viscometer for 1-120 min showed a significant reduction in both α(M)β(2) integrin activation and L-selectin shedding after stimulation with 0.5 nM of fMLP. Neutrophil resistance to activation was directly linked to fluid shear stress, as the response increased in a shear stress force- and time-dependent manner. Significant shear-induced loss of FPR surface expression on neutrophils was observed, and high-resolution confocal microscopy revealed FPR internalized within neutrophils. These results suggest that physiological shear forces alter neutrophil activation via FPR by reducing L-selectin shedding and α(M)β(2) integrin activation in the presence of soluble ligand.
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Affiliation(s)
- Michael J Mitchell
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA
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12
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Bena S, Brancaleone V, Wang JM, Perretti M, Flower RJ. Annexin A1 interaction with the FPR2/ALX receptor: identification of distinct domains and downstream associated signaling. J Biol Chem 2012; 287:24690-7. [PMID: 22610094 PMCID: PMC3397896 DOI: 10.1074/jbc.m112.377101] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Understanding how proresolving agonists selectively activate FPR2/ALX is a crucial step in the clarification of proresolution molecular networks that can be harnessed for the design of novel therapeutics for inflammatory disease. FPR2/ALX, a G protein-coupled receptor belonging to the formyl peptide receptor (FPR) family, conveys the biological functions of a variety of ligands, including the proresolution mediators annexin A1 (AnxA1) and lipoxin A4, as well as the activating and proinflammatory protein serum amyloid A. FPR2/ALX is the focus of intense screening for novel anti-inflammatory therapeutics, and the small molecule compound 43 was identified as a receptor ligand. Here, we used chimeric FPR1 and FPR2/ALX clones (stably transfected in HEK293 cells) to identify the N-terminal region and extracellular loop II as the FPR2/ALX domain required for AnxA1-mediated signaling. Genomic responses were also assessed with domain-specific effects emerging, so the N-terminal region is required for AnxA1 induction of JAG1 and JAM3, whereas it is dispensable for modulation of SGPP2. By comparison, serum amyloid A non-genomic responses were reliant on extracellular loops I and II, whereas the small molecule compound 43 activated extracellular loop I with downstream signaling dependent on transmembrane region II. In desensitization experiments, the N-terminal region was dispensable for AnxA1-induced FPR2/ALX down-regulation in both the homologous and heterologous desensitization modes.
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Affiliation(s)
- Stefania Bena
- William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, London EC1M 6BQ, United Kingdom
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13
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Pop N, Igel P, Brennauer A, Cabrele C, Bernhardt G, Seifert R, Buschauer A. Functional reconstitution of human neuropeptide Y (NPY) Y2and Y4receptors in Sf9 insect cells. J Recept Signal Transduct Res 2011; 31:271-85. [DOI: 10.3109/10799893.2011.583253] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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14
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Sutor S, Heilmann J, Seifert R. Impact of fusion to Gα(i2) and co-expression with RGS proteins on pharmacological properties of human cannabinoid receptors CB₁R and CB₂R. ACTA ACUST UNITED AC 2011; 63:1043-55. [PMID: 21718288 DOI: 10.1111/j.2042-7158.2011.01307.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES G protein coupled receptor (GPCR)-Gα fusion proteins are often employed to investigate receptor/G protein interaction. In this study, the impact of Gα fusion proteins on pharmacology of CBRs, both mediating signals through Gα(i) proteins, were investigated. Gα(i2) was fused to the C-terminus of the CBRs or co-expressed with non-fused Gα(i2) in Sf9 cells, always together with Gβ₁γ₂. Furthermore, the impact of RGS proteins on CBR signaling in combination with the CBR fusion approach was examined, using RGS4 and RGS19 as paradigms. METHODS CBR ligands were characterized in the steady-state GTPase assay and pharmacological properties of ligands in the different test systems were correlated. KEY FINDINGS Fusion of CBRs to Gα(i2) enhanced the maximal stimulatory effects of ligands compared to the co-expression system, especially for CB₂R. RGS4, but not RGS19, behaved as a GTPase-activating protein at CBRs in the Gα(i2) co-expression and fusion system. Fusion of GPCR, most prominently CB₂R, to Gα(i2) , and co-expression with RGS4 altered the pharmacological properties of ligands. CONCLUSIONS Our data suggest that fusion of CB₂R to Gα(i2) and co-expression with RGS4 impedes with conformational changes. Moreover, our results support the concept of ligand-specific receptor conformations. Finally, this paper describes the most sensitive CBR test system currently available.
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Affiliation(s)
- Sarah Sutor
- Department of Pharmaceutical Biology, Institute of Pharmacy, University of Regensburg, Regensburg Institute of Pharmacology, Medical School of Hannover, Hannover, Germany
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15
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Abstract
The investigation of constitutive activity of GPCRs in transfected mammalian cells is often hampered by the presence of other constitutively active receptors that generate a high background signal. This impairs the measurement of constitutive activity and of inverse agonistic effects, both of which often occur in a relatively small signal range. Moreover, constitutive activity of a GPCR depends on the interacting G-protein. Since the commonly used mammalian cells contain a set of several different G-protein types, it is very difficult to investigate the influence of specific Gα and Gβγ subunits on constitutive activity in more detail in these expression systems. Here, we show that the Sf9 cell/baculovirus expression system provides excellent conditions for the characterization of constitutively active GPCRs. Sf9 cells express a restricted set of G-protein subtypes that show only a limited capability of interacting with mammalian GPCRs. Moreover, the Sf9 cell/baculovirus expression system allows the combined expression of up to four different proteins encoded by the respective genetically modified baculoviruses. Using the highly constitutively active human histamine H₄R (hH₄R) as a paradigm, we demonstrate how the coexpression of hH₄R with different signaling proteins (Gα, Gβγ, and RGS-proteins) in combination with sensitive functional assays (high-affinity agonist binding and steady-state GTPase- and GTPγS-binding assays) allows in-depth studies of constitutive activity. The preparation of Sf9 cell membranes, coexpressing hH₄R and various additional proteins, is described in detail as well as the procedures of the different functional assays. Moreover, we show that coexpression of GPCRs with signal transduction components in Sf9 cells can also be applied to the characterization of other constitutively active receptors, for example, the formyl peptide receptor and β₂-adrenoceptor.
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16
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Schnell D, Brunskole I, Ladova K, Schneider EH, Igel P, Dove S, Buschauer A, Seifert R. Expression and functional properties of canine, rat, and murine histamine H₄ receptors in Sf9 insect cells. Naunyn Schmiedebergs Arch Pharmacol 2011; 383:457-70. [PMID: 21359967 DOI: 10.1007/s00210-011-0612-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 12/13/2010] [Indexed: 01/14/2023]
Abstract
The histamine H₄ receptor (H₄R) is expressed on cells of the immune system including eosinophils, dendritic cells, and T cells and plays an important role in the pathogenesis of bronchial asthma, atopic dermatitis, and pruritus. Analysis of the H₄R in these diseases depends on the use of animal models. However, there are substantial pharmacological differences between various H₄R species orthologs. The purpose of this study was to analyze the pharmacological properties of canine, rat, and murine H₄R in comparison to human H₄R expressed in Sf9 insect cells. Only hH₄R and cH₄R exhibited a sufficiently high [³H]histamine affinity for radioligand binding studies. Generally, cH₄R exhibited lower ligand-affinities than hH₄R. Similarly, in high-affinity GTPase studies, ligands were more potent at hH₄R than at other H₄R species orthologs. Unlike the other H₄R species orthologs, hH₄R exhibited high agonist-independent (constitutive) activity. Most strikingly, the prototypical H₄R antagonist (1-[(5-chloro-1H-indol-2-yl)carbonyl]-4-methylpiperazine) (JNJ7777120) exhibited partial agonistic activity at cH₄R, rH₄R, and mH₄R, whereas at hH₄R, JNJ7777120 was a partial inverse agonist. H₄R agonists from the class of N ( G )-acylated imidazolylpropylguanidines and cyanoguanidines exhibited substantial differences in terms of affinity, potency, and efficacy among H₄R species orthologs, too. The species-dependent pharmacological profiles are not due to the highly variable amino acid sequence position 341. Finally, H₄R species orthologs differ from each other in terms of regulation by NaCl. Collectively, there are profound pharmacological differences between H₄R species orthologs. Most importantly, caution must be exerted when interpreting pharmacological effects of "the prototypical H₄R antagonist" JNJ7777120 as H₄R antagonism.
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Affiliation(s)
- David Schnell
- Department of Pharmacology and Toxicology, University of Regensburg, Regensburg, Germany
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17
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Shao G, Julian MW, Bao S, McCullers MK, Lai JP, Knoell DL, Crouser ED. Formyl peptide receptor ligands promote wound closure in lung epithelial cells. Am J Respir Cell Mol Biol 2010; 44:264-9. [PMID: 20889801 DOI: 10.1165/rcmb.2010-0246rc] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial antigens released from damaged cells act as "danger signals" capable of promoting innate immune cell migration and activation via formyl peptide receptors (FPRs). Lung epithelial cells are equipped to migrate and mount innate immune responses in the context of acute lung injury. The goal of this study was to determine whether lung epithelial cells express FPRs, which are capable of responding to mitochondrial antigens to promote wound closure and inflammation. Using human Beas2B lung epithelial cells grown to confluency and subjected to linear scratch injury, it was found that mitochondrial antigens enhanced epithelial wound closure, and this phenomenon was inhibited by cyclosporin H, a selective inhibitor of FPR. Although mitochondrial antigens also promoted IL-8 release, this release was not FPR dependent and was unrelated to FPR-induced lung epithelial cell wound closure. The expression of functional FPR was confirmed in Beas2B and primary human tracheobronchial epithelial cells, particularly in lamellipodia at the leading edge of the closing wound. The expression of FPR was increased in response to TNF-α, LPS, scratch injury, and mitochondrial antigen treatment. Considered together, these data confirm that human lung epithelial cells express functional FPRs, which are capable of responding to endogenous mitochondrial danger signals, to promote wound closure.
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Affiliation(s)
- Guohong Shao
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Medical Center, Columbus, OH 43210-1252, USA
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18
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Sf9 cells: a versatile model system to investigate the pharmacological properties of G protein-coupled receptors. Pharmacol Ther 2010; 128:387-418. [PMID: 20705094 DOI: 10.1016/j.pharmthera.2010.07.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 07/12/2010] [Indexed: 11/23/2022]
Abstract
The Sf9 cell/baculovirus expression system is widely used for high-level protein expression, often with the purpose of purification. However, proteins may also be functionally expressed in the defined Sf9 cell environment. According to the literature, the pharmacology of G-protein-coupled receptors (GPCRs) functionally reconstituted in Sf9 cells is similar to the receptor properties in mammalian cells. Sf9 cells express both recombinant GPCRs and G-proteins at much higher levels than mammalian cells. Sf9 cells can be grown in suspension culture, providing an inexpensive way of obtaining large protein amounts. Co-infection with various baculoviruses allows free combination of GPCRs with different G-proteins. The absence of constitutively active receptors in Sf9 cells provides an excellent signal-to background ratio in functional assays, allowing the detection of agonist-independent receptor activity and of small ligand-induced signals including partial agonistic and inverse agonistic effects. Insect cell Gα(i)-like proteins mostly do not couple productively to mammalian GPCRs. Thus, unlike in mammalian cells, Sf9 cells do not require pertussis toxin treatment to obtain a Gα(i)-free environment. Co-expression of GPCRs with Gα(i1), Gα(i2), Gα(i3) or Gα(o) in Sf9 cells allows the generation of a selectivity profile for these Gα(i/o)-isoforms. Additionally, GPCR-G-protein combinations can be compared with defined 1:1 stoichiometry by expressing GPCR-Gα fusion proteins. Sf9 cells can also be employed for ligand screening in medicinal chemistry programs, using radioligand binding assays or functional assays, like the steady-state GTPase- or [(35)S]GTPγS binding assay. This review shows that Sf9 cells are a versatile model system to investigate the pharmacological properties of GPCRs.
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Geiger S, Nickl K, Schneider EH, Seifert R, Heilmann J. Establishment of recombinant cannabinoid receptor assays and characterization of several natural and synthetic ligands. Naunyn Schmiedebergs Arch Pharmacol 2010; 382:177-91. [PMID: 20617431 DOI: 10.1007/s00210-010-0534-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 06/21/2010] [Indexed: 11/24/2022]
Abstract
Cannabinoid receptors (CBR) are important drug targets for the treatment of various inflammatory, metabolic and neurological diseases. Therefore, sensitive test systems for the assessment of ligands are needed. In this study, a steady-state GTPase assay for human CBR subtypes 1 and 2 was developed to characterize the pharmacological property of ligands at a very proximal point of the signal transduction cascade. Establishing these in vitro test sytems, we studied cell or tissue membranes heterogenously or endogenously expressing CBR, such as CBR-infected Human Embryonic Kidney (HEK) 293 cells, rat cerebellum and spleen cells. The lack of effects in the GTPase assay and in [(35)S]GTPgammaS binding experiments in these expression system, directed us to use Spodoptera frugiperda (Sf9) cells. Co-expressing CBR, different Galpha-subunits, Gbetagamma heterodimer, and RGS (Regulator of G-protein signaling)-proteins in Sf9 cell membranes greatly improved the sensitivity of the assay, with highest GTPase activation in the CBR + Galpha(i2) + Gbeta(1)gamma(2) + RGS4 system. We examined exogenous and endogenous standard ligands as well as secondary metabolites as Delta(9)-tetrahydrocannabinol (Delta(9)-THC), dodeca-2E,4E-dienoic acid isobutylamide, an alkylamide from Echinacea purpurea, and an E. purpurea hexane extract according their agonistic and antagonistic properties. The suitability of the assay for screening procedures was also proven by detecting the activity of Delta(9)-THC in a matrix of other less active compounds (Delta(9)-THC-free Cannabis sativa extract). In conclusion, we have developed highly sensitive test systems for the analysis of CBR ligands.
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Affiliation(s)
- Sarah Geiger
- Department of Pharmaceutical Biology, Institute of Pharmacy, University of Regensburg, 93053, Regensburg, Germany
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20
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Yadav SC, Prasanna Kumari NK, Jagannadham MV. Deglycosylated milin unfolds via inactive monomeric intermediates. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 39:1581-8. [DOI: 10.1007/s00249-010-0615-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 05/23/2010] [Accepted: 05/26/2010] [Indexed: 11/30/2022]
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Dufton N, Perretti M. Therapeutic anti-inflammatory potential of formyl-peptide receptor agonists. Pharmacol Ther 2010; 127:175-88. [PMID: 20546777 DOI: 10.1016/j.pharmthera.2010.04.010] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 04/25/2010] [Indexed: 12/22/2022]
Abstract
The need for novel anti-inflammatory drugs justifies the search for innovative targets that could satisfy this goal. For quite some time now, we have proposed the study of endogenous anti-inflammation as a distinctive approach to the discovery of new drugs. This approach requires development of new compounds that activate specific receptor targets to downregulate the cellular and tissue pathways operative in the host during inflammation. Here we dwell on a family of G-protein coupled receptors (GPCR) termed FPRs, acronym for formyl-peptide receptors. With three and seven members in man and mouse, respectively, these receptors harness many biological functions, spanning odour perception and hair growth, to the control of multiple facets (pain; cell migration; oxidative burst; xenobiotic engulfment) of the inflammatory reaction. We focus on FPR biology with particular attention to molecules able to produce pharmacological effects by interacting with these GPCRs, describing endogenous agonists of FPRs and, more relevantly, the current development of synthetic agonists. Besides being potential leads for the development of the anti-inflammatory therapeutics of the future, these compounds could also help clarify the properties and roles that each FPR might play in the complex network of pathways that is inflammation. We conclude that FPR2 agonists could be valid warhorses for defining a novel philosophy for anti-inflammatory drug discovery programmes: mimicking - with new compounds - the way our body disposes of inflammation could be a viable approach to regulate aberrant inflammatory responses as in the case of several chronic rheumatic and cardiovascular pathologies.
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Affiliation(s)
- Neil Dufton
- The William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, London, United Kingdom
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22
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Schneider EH, Strasser A, Thurmond RL, Seifert R. Structural Requirements for Inverse Agonism and Neutral Antagonism of Indole-, Benzimidazole-, and Thienopyrrole-Derived Histamine H4 Receptor Ligands. J Pharmacol Exp Ther 2010; 334:513-21. [DOI: 10.1124/jpet.110.165977] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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23
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Schneider EH, Schnell D, Strasser A, Dove S, Seifert R. Impact of the DRY motif and the missing "ionic lock" on constitutive activity and G-protein coupling of the human histamine H4 receptor. J Pharmacol Exp Ther 2010; 333:382-92. [PMID: 20106995 DOI: 10.1124/jpet.109.163220] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
It is assumed that many G protein-coupled receptors (GPCRs) are restrained in an inactive state by the "ionic lock," an interaction between an arginine in transmembrane domain (TM) 3 (R3.50) and a negatively charged residue in TM6 (D/E6.30). In the human histamine H4 receptor (hH4R), alanine is present in position 6.30. To elucidate whether this mutation causes the high constitutive activity of hH4R, we aimed to reconstitute the ionic lock by constructing the A6.30E mutant. The role of R3.50 was investigated by generating hH4R-R3.50A. Both mutants were expressed alone or together with Galpha(i2) and Gbeta1gamma2 in Sf9 cells and characterized in GTPase, 35S-labeled guanosine 5'-[gamma-thio]triphosphate binding, and high-affinity agonist binding assays. Unexpectedly, compared with hH4R, hH4R-A6.30E showed only nonsignificant reduction of constitutive activity and G protein-coupling efficiency. The KD of [3H]histamine was unaltered. By contrast, hH4R-R3.50A did not stimulate G proteins. Thioperamide affinity at hH(4)R-R3.50A was increased by 300 to 400%, whereas histamine affinity was reduced by approximately 50%. A model of the active hH4R state in complex with the Galpha(i2) C terminus was compared with the crystal structures of turkey beta1 and human beta2 adrenoceptors. We conclude that 1) constitutive activity of hH4R is facilitated by the salt bridge D5.69-R6.31 rather than by the missing ionic lock, 2) Y3.60 may form alternative locks in active and inactive GPCR states, 3) R3.50 is crucial for hH4R-G protein coupling, and 4) hH4R-R3.50A represents an inactive state with increased inverse agonist and reduced agonist affinity. Thus, the ionic lock, although stabilizing the inactive rhodopsin state, is not generally important for all class A GPCRs.
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Affiliation(s)
- Erich H Schneider
- Department of Pharmacology and Toxicology, University of Regensburg, Regensburg, Germany.
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24
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Kim SD, Kim JM, Jo SH, Lee HY, Lee SY, Shim JW, Seo SK, Yun J, Bae YS. Functional expression of formyl peptide receptor family in human NK cells. THE JOURNAL OF IMMUNOLOGY 2009; 183:5511-7. [PMID: 19843937 DOI: 10.4049/jimmunol.0802986] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We determined the expression of the formyl peptide receptor (FPR) family and the functional roles of the FPR family in NK cells. All tested human NK cells express two members of the FPR family (FPR1 and FPR2). The expression of FPR3 was noted to occur in a donor-specific manner. The stimulation of NK cells with FPR family-selective agonists (fMLF (N-formyl-Met-Leu-Phe), MMK-1, F2L, and WKYMVm (Trp-Lys-Tyr-Met-Val-d-Met)) elicited cytolytic activity in resting NK cells, but not in IL-2-activated NK cells; the cytolytic activity was not inhibited by pertussis toxin. The FPR family agonists also stimulated chemotactic migration of IL-2-activated NK cells, but not resting NK cells; the chemotactic migration was completely inhibited by pertussis toxin. WKYMVm stimulates ERK, p38 MAPK, and JNK activities in both resting and IL-2-activated NK cells. WKYMVm-induced chemotactic migration was partially inhibited by PD98059 (2'-amino-3'-methoxyflavone); however, the inhibition of JNK by its selective inhibitor (SP600125, anthra[1,9-cd]pyrazol-6(2H)-one) dramatically inhibited the WKYMVm-induced cytolytic activity. Furthermore, WKYMVm-induced chemotactic migration and cytolytic activity were partly inhibited by FPR family-selective antagonists (cyclosporin H and WRWWWW). Taken together, our findings indicate that human NK cells express functional members of the FPR family, and in turn the activation of the three members of the FPR receptor family elicit cytolytic activity in NK cells, thus suggesting that the receptors are potentially important therapeutic targets for the modulation of NK cell-mediated immune responses.
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Affiliation(s)
- Sang Doo Kim
- Department of Biochemistry, College of Medicine, Dong-A University, Busan, Korea
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Schnell D, Burleigh K, Trick J, Seifert R. No Evidence for Functional Selectivity of Proxyfan at the Human Histamine H3 Receptor Coupled to Defined Gi/Go Protein Heterotrimers. J Pharmacol Exp Ther 2009; 332:996-1005. [DOI: 10.1124/jpet.109.162339] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Zhang Z, Cherryholmes G, Chang F, Rose DM, Schraufstatter I, Shively JE. Evidence that cathelicidin peptide LL-37 may act as a functional ligand for CXCR2 on human neutrophils. Eur J Immunol 2009; 39:3181-94. [PMID: 19750480 PMCID: PMC3076219 DOI: 10.1002/eji.200939496] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
LL-37, derived from human cathelicidin, stimulates immune responses in neutrophils. Although FPR2 and P2X7 were proposed as LL-37 receptors, we have shown that among 21 neutrophil receptors only CXCR2 was down-regulated by LL-37. LL-37 functions similarly to CXCR2-specific chemokines CXCL1 and CXCL7 in terms of receptor down-regulation and intracellular calcium mobilization on freshly isolated neutrophils. Neutrophils pretreated with CXCL8, a chemokine that binds both CXCR1/2, completely blocked the calcium mobilization in response to LL-37, while LL-37 also partially inhibited (125)I-CXCL8 binding to neutrophils. SB225002, a selective CXCR2 antagonist, blocked LL-37-induced calcium mobilization and migration of neutrophils. LL-37 stimulates calcium mobilization in CXCR2-transfected HEK293 cells, CXCR2(+) THP-1 cells and monocytes, but not in CXCR1-transfected HEK293 cells. WKYMVm peptide (ligand for FPR2) does not block LL-37-stimulated calcium flux in either THP-1 (FPR2(-)) or monocytes (FPR2(high)), further confirming the specificity of LL-37 for CXCR2 and not FPR2. Among all ligands tested (ATP, BzATP, WKYMVm, CXCL1, and LL-37), only LL-37 stimulated migration of monocytes (CXCR2(+) and FPR2(+)) and migration was inhibited by the CXCR2 inhibitor SB225002. Moreover, CXCR2 but not CXCR1 was internalized in LL-37-treated neutrophils. Thus, our data provide evidence that LL-37 may act as a functional ligand for CXCR2 on human neutrophils.
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Affiliation(s)
- Zhifang Zhang
- Department of Immunology, Beckman Research Institute of City of Hope, 1450 E Duarte Road, Duarte, CA 91010, USA
| | - Gregory Cherryholmes
- Department of Immunology, Beckman Research Institute of City of Hope, 1450 E Duarte Road, Duarte, CA 91010, USA
| | - Frances Chang
- Department of Immunology, Beckman Research Institute of City of Hope, 1450 E Duarte Road, Duarte, CA 91010, USA
| | - David M. Rose
- Department of Medicine, University of California at San Diego, La Jolla, CA 92161 USA
| | | | - John E. Shively
- Department of Immunology, Beckman Research Institute of City of Hope, 1450 E Duarte Road, Duarte, CA 91010, USA
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Schneider EH, Schnell D, Papa D, Seifert R. High constitutive activity and a G-protein-independent high-affinity state of the human histamine H(4)-receptor. Biochemistry 2009; 48:1424-38. [PMID: 19166345 DOI: 10.1021/bi802050d] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human histamine H(4)-receptor (hH(4)R) is expressed in mast cells and eosinophils and mediates histamine (HA)-induced chemotaxis via G(i)-proteins. For a detailed investigation of hH(4)R/G(i)-protein interaction, we coexpressed the hH(4)R with Galpha(i2) and Gbeta(1)gamma(2) as well as an hH(4)R-Galpha(i2) fusion protein with Gbeta(1)gamma(2) in Sf9 insect cells. The agonist radioligand [(3)H]HA showed a K(D) value of approximately 10 nM at hH(4)R and hH(4)R-Galpha(i2). The high-affinity states of hH(4)R and hH(4)R-Galpha(i2) were insensitive to guanosine 5'-[gamma-thio]triphosphate (GTPgammaS). The affinity of [(3)H]HA for hH(4)R was retained in the absence of mammalian G(i)-proteins. In steady-state GTPase- and [(35)S]GTPgammaS-binding assays, hH(4)R exhibited high constitutive activity and uncommon insensitivity to Na(+). Thioperamide (THIO) was only a partial inverse agonist. Addition of HA or THIO to baculovirus-infected (hH(4)R + Galpha(i2) + Gbeta(1)gamma(2)) Sf9 cells increased the B(max) in [(3)H]HA binding, but not in immunoblots, suggesting conformational instability and ligand-induced stabilization of membrane-integrated hH(4)R. No effect was observed on hH(4)R-Galpha(i2) expression, neither in [(3)H]HA binding nor in immunoblot. However, the expression level of hH(4)R-Galpha(i2) was consistently higher compared to hH(4)R, suggesting chaperone-like or stabilizing effects of Galpha(i2) on hH(4)R. In 37 degrees C stability assays, HA stabilized hH(4)R, and THIO even restored misfolded [(3)H]HA binding sites. Inhibition of hH(4)R glycosylation by tunicamycin reduced the [(3)H]HA binding B(max) value. In conclusion, (i) hH(4)R shows high constitutive activity and structural instability; (ii) hH(4)R shows a G-protein-independent high-affinity state; (iii) hH(4)R conformation is stabilized by agonists, inverse agonists and G-proteins; (iv) hH(4)R glycosylation is essential for cell-surface expression of intact hH(4)R.
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Affiliation(s)
- Erich H Schneider
- Department of Pharmacology and Toxicology, University of Regensburg, Universitatsstrasse 31, D-93040 Regensburg, Germany.
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Monocyte activation by necrotic cells is promoted by mitochondrial proteins and formyl peptide receptors. Crit Care Med 2009; 37:2000-9. [PMID: 19384205 DOI: 10.1097/ccm.0b013e3181a001ae] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Necrotic cells evoke potent innate immune responses through unclear mechanisms. The mitochondrial fraction of the cell retains constituents of its bacterial ancestors, including N-formyl peptides, which are potentially immunogenic. Thus, we hypothesized that the mitochondrial fraction of the cell, particularly N-formyl peptides, contributes significantly to the activation of monocytes by necrotic cells. DESIGN Human peripheral blood monocytes were incubated with necrotic cell fractions and mitochondrial proteins to investigate their potential for immune cell activation. SETTING University Medical Center Research Laboratory. SUBJECTS Healthy human adults served as blood donors. MEASUREMENTS AND MAIN RESULTS Human blood monocyte activation was measured after treatment with cytosolic, nuclear and mitochondrial fractions of necrotic HepG2 cells or necrotic HepG2 cells depleted of N-formyl peptides [Rho(0) cells]. The specific role of the high affinity formyl peptide receptor (FPR) was then tested using specific pharmacologic inhibitors and RNA silencing. The capacity of mitochondrial N-formyl peptides to activate monocytes was confirmed using a synthetic peptide conforming to the N-terminus of mitochondrial nicotinamide adenine dinucleotide subunit 6. The results demonstrated that mitochondrial cell fractions most potently activated monocytes, and interleukin (IL)-8 was selectively released at low-protein concentrations. Mitochondria from Rho(0) cells induced minimal monocyte IL-8 release, and specific pharmacologic inhibitors and RNA-silencing confirmed that FPR contributes significantly to monocyte IL-8 responses to both necrotic cells and mitochondrial proteins. N-formyl peptides alone did not induce monocyte IL-8 release; whereas, the combination of mitochondrial N-formyl peptides and mitochondrial transcription factor A (TFAM) dramatically increased IL-8 release from monocytes. Likewise, high mobility group box 1, the nuclear homolog of TFAM, did not induce monocyte IL-8 release unless combined with mitochondrial N-formyl peptides. CONCLUSIONS Interactions between mitochondrial N-formyl peptides and FPR in the presence of other mitochondrial antigens (e.g., TFAM) contributes significantly to the activation of monocytes by necrotic cells.
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Ye RD, Boulay F, Wang JM, Dahlgren C, Gerard C, Parmentier M, Serhan CN, Murphy PM. International Union of Basic and Clinical Pharmacology. LXXIII. Nomenclature for the formyl peptide receptor (FPR) family. Pharmacol Rev 2009; 61:119-61. [PMID: 19498085 DOI: 10.1124/pr.109.001578] [Citation(s) in RCA: 595] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Formyl peptide receptors (FPRs) are a small group of seven-transmembrane domain, G protein-coupled receptors that are expressed mainly by mammalian phagocytic leukocytes and are known to be important in host defense and inflammation. The three human FPRs (FPR1, FPR2/ALX, and FPR3) share significant sequence homology and are encoded by clustered genes. Collectively, these receptors bind an extraordinarily numerous and structurally diverse group of agonistic ligands, including N-formyl and nonformyl peptides of different composition, that chemoattract and activate phagocytes. N-formyl peptides, which are encoded in nature only by bacterial and mitochondrial genes and result from obligatory initiation of bacterial and mitochondrial protein synthesis with N-formylmethionine, is the only ligand class common to all three human receptors. Surprisingly, the endogenous anti-inflammatory peptide annexin 1 and its N-terminal fragments also bind human FPR1 and FPR2/ALX, and the anti-inflammatory eicosanoid lipoxin A4 is an agonist at FPR2/ALX. In comparison, fewer agonists have been identified for FPR3, the third member in this receptor family. Structural and functional studies of the FPRs have produced important information for understanding the general pharmacological principles governing all leukocyte chemoattractant receptors. This article aims to provide an overview of the discovery and pharmacological characterization of FPRs, to introduce an International Union of Basic and Clinical Pharmacology (IUPHAR)-recommended nomenclature, and to discuss unmet challenges, including the mechanisms used by these receptors to bind diverse ligands and mediate different biological functions.
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Affiliation(s)
- Richard D Ye
- Department of Pharmacology, University of Illinois College of Medicine, 835 South Wolcott Avenue, M/C 868, Chicago, Illinois 60612, USA.
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Schneider EH, Seifert R. Histamine H(4) receptor-RGS fusion proteins expressed in Sf9 insect cells: a sensitive and reliable approach for the functional characterization of histamine H(4) receptor ligands. Biochem Pharmacol 2009; 78:607-16. [PMID: 19464266 DOI: 10.1016/j.bcp.2009.05.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 05/08/2009] [Accepted: 05/11/2009] [Indexed: 11/16/2022]
Abstract
The human histamine H(4) receptor (hH(4)R), co-expressed with Galpha(i2) and Gbeta(1)gamma(2) in Sf9 cells, is highly constitutively active. In the steady-state GTPase assay, the full agonist histamine (HA) induces only a relatively small signal (approximately 20-30%), resulting in a low signal-to background ratio. In order to improve this system for ligand screening purposes, the effects of the regulators of G-protein signaling (RGS) RGS4 and RGS19 (GAIP) were investigated. RGS4 and GAIP were fused to the C-terminus of hH(4)R or co-expressed with non-fused hH(4)R, always combined with Galpha(i2) and Gbeta(1)gamma(2). The non-fused RGS proteins did not significantly increase the relative effect of HA. With the hH(4)R-RGS4 fusion protein the absolute GTPase activities, but not the relative HA-induced signal were increased. Fusion of hH(4)R with GAIP caused a selective increase of the HA signal, resulting in an enhanced signal-to-noise ratio. A detailed characterization of the hH(4)R-GAIP fusion protein (co-expressed with Galpha(i2) and Gbeta(1)gamma(2)) and a comparison with the data obtained for the non-fused hH(4)R (co-expressed with Galpha(i2) and Gbeta(1)gamma(2)) led to the following results: (i) the relative agonist- and inverse agonist-induced signals at hH(4)R-GAIP are markedly increased. (ii) Compared to the wild-type hH(4)R, standard ligands show unaltered potencies and efficacies at hH(4)R-GAIP. (iii) Like hH(4)R, hH(4)R-GAIP shows high and NaCl-resistant constitutive activity. (iv) hH(4)R-GAIP shows the same G-protein selectivity profile as the non-fused hH(4)R. Collectively, hH(4)R-GAIP provides a sensitive test system for the characterization of hH(4)R ligands and can replace the non-fused hH(4)R in steady-state GTPase assays.
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Affiliation(s)
- Erich H Schneider
- University of Regensburg, Department of Pharmacology and Toxicology, Regensburg, Germany.
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Svensson L, Redvall E, Johnsson M, Stenfeldt AL, Dahlgren C, Wennerås C. Interplay between signaling via the formyl peptide receptor (FPR) and chemokine receptor 3 (CCR3) in human eosinophils. J Leukoc Biol 2009; 86:327-36. [PMID: 19414538 DOI: 10.1189/jlb.0908514] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Eosinophils express the chemoattractant receptors CCR3 and FPR. CCR3 binds several agonists such as eotaxin-1, -2, and -3 and RANTES, whereas the FPR binds the formylated tripeptide fMLP and a host of other ligands. The aim of this study was to investigate if there is interplay between these two receptors regarding the elicitation of migration and respiratory burst in human blood-derived eosinophils. Inhibition of the FPR with the antagonists CyH and boc-MLP abrogated the migration of eosinophils toward all of the CCR3 agonists. Similar results were seen when the FPR was desensitized with its cognate ligand, fMLP. In contrast, the respiratory burst triggered by eotaxin-1 was not inhibited by CyH. Thus, signals evoked via the FPR caused unidirectional down-regulation of CCR3-mediated chemotaxis but not respiratory burst in human eosinophils. The underlying mechanism was neither reduced ability of the CCR3 ligand eotaxin-1 to bind to CCR3 nor down-regulation of CCR3 from the cell surface. Finally, confocal microscopy and adFRET analysis ruled out homo- or heterodimer formation between FPR and/or CCR3 as an explanation for the reduction in chemotaxis via CCR3. Pharmacologic inhibition of signal transduction molecules showed that the release of free oxygen radicals in response to eotaxin-1 compared with fMLP is relatively more dependent on the p38 MAPK pathway.
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Affiliation(s)
- Lena Svensson
- Department of Clinical Bacteriology, Göteborg University, Göteborg, Sweden.
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Sanganee HJ, Baxter A, Barber S, Brown AJ, Grice D, Hunt F, King S, Laughton D, Pairaudeau G, Thong B, Weaver R, Unitt J. Discovery of small molecule human C5a receptor antagonists. Bioorg Med Chem Lett 2009; 19:1143-7. [DOI: 10.1016/j.bmcl.2008.12.104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 12/23/2008] [Accepted: 12/24/2008] [Indexed: 11/15/2022]
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Chapter 13 Endogenous Cannabinoids and Neutrophil Chemotaxis. VITAMINS AND HORMONES 2009; 81:337-65. [DOI: 10.1016/s0083-6729(09)81013-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Miller TR, Baranowski JL, Estvander BR, Witte DG, Carr TL, Manelli AM, Krueger KM, Cowart MD, Brioni JD, Esbenshade TA. A robust and high-capacity [(35)S]GTPgammaS binding assay for determining antagonist and inverse agonist pharmacological parameters of histamine H(3) receptor ligands. Assay Drug Dev Technol 2008; 6:339-49. [PMID: 18593375 DOI: 10.1089/adt.2007.118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding assays were established and utilized as a reliable and high-capacity functional assay for determining antagonist and inverse agonist pharmacological parameters of novel histamine H(3) ligands, at the recombinant human H(3) receptor. [(35)S]GTPgammaS binding assays were performed with membranes prepared from human embryonic kidney 293 cells stably expressing the full-length (445 amino acids) human H(3) receptor isoform, at approximately 1 pmol/mg of protein. Utilizing robotic liquid handling, assay filtration, and scintillation counting in a 96-well format, concentration-response curves were determined for up to 40 compounds per assay. The imidazole-containing H(3) receptor antagonist ciproxifan and the non-imidazole antagonist ABT-239 inhibited (R)-alpha-methylhistamine (RAMH)-stimulated [(35)S]GTPgammaS binding in a competitive manner, and negative logarithm of the dissociation equilibrium constant (pK(b)) values determined for nearly 200 structurally diverse H(3) antagonists were very similar to the respective negative logarithm of the equilibrium inhibition constant values from N-alpha-[(3)H]methylhistamine competition binding assays. H(3) antagonists also concentration-dependently decreased basal [(35)S]GTPgammaS binding, thereby displaying inverse agonism at the constitutively active H(3) receptor. At maximally effective concentrations, non-imidazole H(3) antagonists inhibited basal [(35)S]GTPgammaS binding by approximately 20%. For over 100 of these antagonists, negative logarithm of the 50% effective concentration values for inverse agonism were very similar to the respective pK(b) values. Both H(3) receptor agonist-dependent and -independent (constitutive) [(35)S]GTPgammaS binding were sensitive to changes in assay concentrations of sodium, magnesium, and the guanine nucleotide GDP; however, the potency of ABT-239 for inhibition of RAMH-stimulated [(35)S]GTPgammaS binding was not significantly affected. These robust and reliable [(35)S]GTPgammaS binding assays have become one of the important tools in our pharmacological analysis and development of novel histamine H(3) receptor antagonists/inverse agonists.
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Affiliation(s)
- Thomas R Miller
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, IL 60064-6125, USA.
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Kleemann P, Papa D, Vigil-Cruz S, Seifert R. Functional reconstitution of the human chemokine receptor CXCR4 with G(i)/G (o)-proteins in Sf9 insect cells. Naunyn Schmiedebergs Arch Pharmacol 2008; 378:261-74. [PMID: 18523757 DOI: 10.1007/s00210-008-0313-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 05/06/2008] [Indexed: 01/10/2023]
Abstract
The chemokine stromal cell-derived factor-1alpha (SDF-1alpha) binds to the chemokine receptor CXCR4 that couples to pertussis toxin-sensitive G-proteins of the G(i)/G(o)-family. CXCR4 plays a role in the pathogenesis of autoimmune diseases, human immunodeficiency virus infection and various tumors, fetal development as well as endothelial progenitor and T-cell recruitment. To this end, most CXCR4 studies have focused on the cellular level. The aim of this study was to establish a reconstitution system for the human CXCR4 that allows for the analysis of receptor/G-protein coupling at the membrane level. We wished to study specifically constitutive CXCR4 activity and the G-protein-specificity of CXCR4. We co-expressed N- and C-terminally epitope-tagged human CXCR4 with various G(i)/G(o)-proteins and regulator of G-protein signaling (RGS)-proteins in Sf9 insect cells. Expression of CXCR4, G-proteins, and RGS-proteins was verified by immunoblotting. CXCR4 coupled more effectively to Galpha(i1) and Galpha(i2) than to Galpha(i3) and Galpha(o) and insect cell G-proteins as assessed by SDF-1alpha-stimulated high-affinity steady-state GTP hydrolysis. The RGS-proteins RGS4 and GAIP enhanced SDF-1alpha-stimulated GTP hydrolysis. SDF-1alpha stimulated [(35)S]guanosine 5'-[gamma-thio]triphosphate (GTPgammaS) binding to Galpha(i2). RGS4 did not enhance GTPgammaS binding. Na(+) salts of halides did not reduce basal GTPase activity. The bicyclam, 1-[[1,4,8,11-tetrazacyclotetradec-1-ylmethyl)phenyl]methyl]-1,4,8,11-tetrazacyclotetradecane (AMD3100), acted as CXCR4 antagonist but was devoid of inverse agonistic activity. Halides reduced the maximum SDF-1alpha-stimulated GTP hydrolysis in the order of efficacy I(-) > Br(-) > Cl(-). In addition, salts reduced the potency of SDF-1alpha at activating GTP hydrolysis. From our data, we conclude the following: (1) Sf9 cells are a suitable system for expression of functionally intact human CXCR4; (2) Human CXCR4 couples effectively to Galpha(i1) and Galpha(i2); (3) There is no evidence for constitutive activity of CXCR4; (4) RGS-proteins enhance agonist-stimulated GTP hydrolysis, showing that GTP hydrolysis becomes rate-limiting in the presence of SDF-1alpha; (5) By analogy to previous observations made for the beta(2)-adrenoceptor coupled to G(s), the inhibitory effects of halides on agonist-stimulated GTP hydrolysis may be due to increased GDP-affinity of G(i)-proteins, reducing the efficacy of CXCR4 at stimulating nucleotide exchange.
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Affiliation(s)
- Patrick Kleemann
- Lehrstuhl für Pharmakologie und Toxikologie, Institut für Pharmazie, Universität Regensburg, Regensburg, Germany
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Lee HY, Bae YS. The anti-infective peptide, innate defense-regulator peptide, stimulates neutrophil chemotaxis via a formyl peptide receptor. Biochem Biophys Res Commun 2008; 369:573-8. [DOI: 10.1016/j.bbrc.2008.02.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 02/13/2008] [Indexed: 11/24/2022]
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Cheng N, He R, Tian J, Dinauer MC, Ye RD. A critical role of protein kinase C delta activation loop phosphorylation in formyl-methionyl-leucyl-phenylalanine-induced phosphorylation of p47(phox) and rapid activation of nicotinamide adenine dinucleotide phosphate oxidase. THE JOURNAL OF IMMUNOLOGY 2008; 179:7720-8. [PMID: 18025218 DOI: 10.4049/jimmunol.179.11.7720] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Generation of superoxide by professional phagocytes is an important mechanism of host defense against bacterial infection. Several protein kinase C (PKC) isoforms have been found to phosphorylate p47(phox), resulting in its membrane translocation and activation of the NADPH oxidase. However, the mechanism by which specific PKC isoforms regulate NADPH oxidase activation remains to be elucidated. In this study, we report that PKCdelta phosphorylation in its activation loop is rapidly induced by fMLF and is essential for its ability to catalyze p47(phox) phosphorylation. Using transfected COS-7 cells expressing gp91(phox), p22(phox), p67(phox), and p47(phox) (COS-phox cells), we found that a functionally active PKCdelta is required for p47(phox) phosphorylation and reconstitution of NADPH oxidase. PKCbetaII cannot replace PKCdelta for this function. Characterization of PKCdelta/PKCbetaII chimeras has led to the identification of the catalytic domain of PKCdelta as a target of regulation by fMLF, which induces a biphasic (30 and 180 s) phosphorylation of Thr(505) in the activation loop of mouse PKCdelta. Mutation of Thr(505) to alanine abolishes the ability of PKCdelta to catalyze p47(phox) phosphorylation in vitro and to reconstitute NADPH oxidase in the transfected COS-phox cells. A correlation between fMLF-induced activation loop phosphorylation and superoxide production is also established in the differentiated PLB-985 human myelomonoblastic cells. We conclude that agonist-induced PKCdelta phosphorylation is a novel mechanism for NADPH oxidase activation. The ability to induce PKCdelta phosphorylation may distinguish a full agonist from a partial agonist for superoxide production.
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Affiliation(s)
- Ni Cheng
- Department of Pharmacology, College of Medicine, University of Illinois, Chicago, IL 60612, USA
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Rabiet MJ, Huet E, Boulay F. The N-formyl peptide receptors and the anaphylatoxin C5a receptors: an overview. Biochimie 2007; 89:1089-106. [PMID: 17428601 PMCID: PMC7115771 DOI: 10.1016/j.biochi.2007.02.015] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 02/23/2007] [Indexed: 12/31/2022]
Abstract
Leukocyte recruitment to sites of inflammation and infection is dependent on the presence of a gradient of locally produced chemotactic factors. This review is focused on current knowledge about the activation and regulation of chemoattractant receptors. Emphasis is placed on the members of the N-formyl peptide receptor family, namely FPR (N-formyl peptide receptor), FPRL1 (FPR like-1) and FPRL2 (FPR like-2), and the complement fragment C5a receptors (C5aR and C5L2). Upon chemoattractant binding, the receptors transduce an activation signal through a G protein-dependent pathway, leading to biochemical responses that contribute to physiological defense against bacterial infection and tissue damage. C5aR, and the members of the FPR family that were previously thought to be restricted to phagocytes proved to have a much broader spectrum of cell expression. In addition to N-formylated peptides, numerous unrelated ligands were recently found to interact with FPR and FPRL1. Novel agonists include both pathogen- and host-derived components, and synthetic peptides. Antagonistic molecules have been identified that exhibit limited receptor specificity. How distinct ligands can both induce different biological responses and produce different modes of receptor activation and unique sets of cellular responses are discussed. Cell responses to chemoattractants are tightly regulated at the level of the receptors. This review describes in detail the regulation of receptor signalling and the multi-step process of receptor inactivation. New concepts, such as receptor oligomerization and receptor clustering, are considered. Although FPR, FPRL1 and C5aR trigger similar biological functions and undergo a rapid chemoattractant-mediated phosphorylation, they appear to be differentially regulated and experience different intracellular fates.
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Affiliation(s)
| | | | - François Boulay
- Corresponding author. Tel.: +33 438 78 31 38; fax: +33 438 78 51 85.
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Yan P, Nanamori M, Sun M, Zhou C, Cheng N, Li N, Zheng W, Xiao L, Xie X, Ye RD, Wang MW. The Immunosuppressant Cyclosporin A Antagonizes Human Formyl Peptide Receptor through Inhibition of Cognate Ligand Binding. THE JOURNAL OF IMMUNOLOGY 2006; 177:7050-8. [PMID: 17082621 DOI: 10.4049/jimmunol.177.10.7050] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cyclosporin A (CsA) is a fungus-derived cyclic undecapeptide with potent immunosuppressive activity. Its analog, cyclosporin H (CsH), lacks immunosuppressive function but can act as an antagonist for the human formyl peptide receptor (FPR). More recent studies have shown that CsA also inhibits fMLF-induced degranulation in differentiated HL-60 promyelocytic leukemia cells. However, it is unclear whether CsA interferes with ligand-receptor interaction, G protein activation, or other downstream signaling events. In this study we used human neutrophils, differentiated HL-60 cells, and rat basophilic leukemia (RBL)-2H3 cells expressing human FPR (RBL-FPR) to identify the action site of CsA. In functional assays, CsA inhibited fMLF-stimulated degranulation, chemotaxis, calcium mobilization, and phosphorylation of the MAPKs ERK 1/2 and the serine/threonine protein kinase Akt. CsA also blocked Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm)-induced functions in RBL-FPR cells. Concentrations for half-maximal inhibition with CsA are generally 6- to 50-fold higher than that of CsH. CsA was compared with another immunosuppressant, ascomycin, relative to the inhibitory effects on FPR-mediated chemotaxis, calcium mobilization, and degranulation. In these experiments, ascomycin produced no inhibitory effects at low micromolar concentrations (1-4 microM), whereas the inhibitory effects of CsA were prominent at comparable concentrations. Finally, CsA dose-dependently inhibited the uptake of fNle-Leu-Phe-Nle-Tyr-Lys-fluoresceine and [3H]fMLF or [125I]WKYMVm binding to FPR. However, CsA and CsH did not show any obvious inhibitory effect on FPR-like 1-mediated cellular functions. These results demonstrate that CsA is a selective antagonist of FPR and that its inhibition of fMLF-stimulated leukocyte activation is at the level of cognate ligand binding.
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Affiliation(s)
- Pangke Yan
- National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
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Bastian P, Posch B, Lang K, Niggemann B, Zaenker KS, Hatt H, Entschladen F. Phosphatidylinositol 3-Kinase in the G Protein-Coupled Receptor–Induced Chemokinesis and Chemotaxis of MDA-MB-468 Breast Carcinoma Cells: A Comparison with Leukocytes. Mol Cancer Res 2006; 4:411-21. [PMID: 16778088 DOI: 10.1158/1541-7786.mcr-06-0030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The polarization of tumor cells and leukocytes into a front end and a rear end is a crucial prerequisite for their autonomous, directed movement. Phosphatidylinositol 3-kinase (PI3K) is assumed to play an important role in this polarization process, whereas the results obtained with different cell types and different migration assays widely vary. Thus, we conducted a comparative study on the role of the PI3K in the locomotor activity and directionality of the migration of tumor cells on the example of MDA-MB-468 breast carcinoma cells in comparison with CTLs and neutrophil granulocytes. We used our well-established, collagen-based, three-dimensional migration assay for the investigation of the chemokinesis and chemotaxis of these cells. Our results show that the role of the PI3K in the regulation of migratory activity is distinct between the investigated cell types: the migration of CTLs and MDA-MB-468 cells was impaired by the inhibition of the PI3K with wortmannin, whereas neutrophil granulocytes were only slightly affected. However, neither cell type was impaired in the ability to respond chemotactically to gradients of ligands to G protein-coupled receptors. Thus, the PI3K contributes to the regulation of migratory activity but not to the directionality of migration of MDA-MB-468 breast carcinoma cells. As a further conclusion with regard to cancer treatment, the PI3K is not a suitable target for the inhibition of metastasis formation, because the migration of leukocytes is also affected, which leads to a dysfunction of the immune defense.
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Affiliation(s)
- Philipp Bastian
- Institute of Immunology, Witten/Herdecke University, Stockumer Str. 10, 58448 Witten, Germany
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41
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Sacerdote P, . MB. Lornoxicam Inhibits Human Polymorphonuclear Cell Migration Induced by fMLP, Interleukin-8 and Substance P. INT J PHARMACOL 2005. [DOI: 10.3923/ijp.2005.180.184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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42
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Sacerdote P, Martucci C, Vaccani A, Bariselli F, Panerai AE, Colombo A, Parolaro D, Massi P. The nonpsychoactive component of marijuana cannabidiol modulates chemotaxis and IL-10 and IL-12 production of murine macrophages both in vivo and in vitro. J Neuroimmunol 2005; 159:97-105. [PMID: 15652407 DOI: 10.1016/j.jneuroim.2004.10.003] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 09/23/2004] [Accepted: 10/08/2004] [Indexed: 11/21/2022]
Abstract
Cannabidiol is the main nonpsychoactive component of marijuana. We examined the ability of in vivo and in vitro cannabidiol to interfere with the production of interleukin (IL)-12 and IL-10 by murine macrophages and to modulate macrophage chemotaxis. Cannabidiol added in vitro to peritoneal macrophages significantly increased IL-12 and decreased IL-10 production. The CB1 and CB2 receptor antagonists prevented this modulation. Macrophages from animals treated with cannabidiol at the dose of 30 mg kg(-1) either orally or i.p. produced higher levels of IL-12 and lower levels of IL-10 in comparison to controls, and the CB receptor antagonists did not prevent these effects. Cannabidiol dose-dependently decreased fMLP-induced chemotaxis of macrophages, and the CB2 receptor antagonist prevented this decrease.
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MESH Headings
- Adjuvants, Immunologic/administration & dosage
- Adjuvants, Immunologic/metabolism
- Adjuvants, Immunologic/pharmacology
- Administration, Oral
- Animals
- Camphanes/pharmacology
- Cannabidiol/administration & dosage
- Cannabidiol/metabolism
- Cannabidiol/pharmacology
- Cell Migration Inhibition
- Cells, Cultured
- Chemotaxis/drug effects
- Chemotaxis/immunology
- Cytokines/biosynthesis
- Down-Regulation/drug effects
- Down-Regulation/immunology
- Interleukin-10/antagonists & inhibitors
- Interleukin-10/biosynthesis
- Interleukin-12/biosynthesis
- Macrophage Activation/drug effects
- Macrophage Activation/immunology
- Macrophages, Peritoneal/drug effects
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Male
- Mice
- Piperidines/pharmacology
- Pyrazoles/pharmacology
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/physiology
- Receptor, Cannabinoid, CB2/antagonists & inhibitors
- Receptor, Cannabinoid, CB2/physiology
- Rimonabant
- Up-Regulation/drug effects
- Up-Regulation/immunology
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Affiliation(s)
- P Sacerdote
- Department of Pharmacology, via Vanvitelli 32, 20129 Milano, Italy.
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de Paulis A, Montuori N, Prevete N, Fiorentino I, Rossi FW, Visconte V, Rossi G, Marone G, Ragno P. Urokinase induces basophil chemotaxis through a urokinase receptor epitope that is an endogenous ligand for formyl peptide receptor-like 1 and -like 2. THE JOURNAL OF IMMUNOLOGY 2004; 173:5739-48. [PMID: 15494526 DOI: 10.4049/jimmunol.173.9.5739] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Basophils circulate in the blood and are able to migrate into tissues at sites of inflammation. Urokinase plasminogen activator (uPA) binds a specific high affinity surface receptor (uPAR). The uPA-uPAR system is crucial for cell adhesion and migration, and tissue repair. We have investigated the presence and function of the uPA-uPAR system in human basophils. The expression of uPAR was found at both mRNA and protein levels. The receptor was expressed on the cell surface of basophils, in the intact and cleaved forms. Basophils did not express uPA at either the protein or mRNA level. uPA (10(-12)-10(-9) M) and its uPAR-binding N-terminal fragment (ATF) were potent chemoattractants for basophils, but did not induce histamine or cytokine release. Inactivation of uPA enzymatic activity by di-isopropyl fluorophosphate did not affect its chemotactic activity. A polyclonal Ab against uPAR inhibited uPA-dependent basophil chemotaxis. The uPAR-derived peptide 84-95 (uPAR84-95) induced basophil chemotaxis. Basophils expressed mRNA for the formyl peptide receptors formyl peptide receptor (FPR), FPR-like 1 (FPRL1), and FPRL2. The FPR antagonist cyclosporin H prevented chemotaxis induced by FMLP, but not that induced by uPA and uPAR84-95. Incubation of basophils with low and high concentrations of FMLP, which desensitize FPR and FPRL1, respectively, but not FPRL2, slightly reduced the chemotactic response to uPA and uPAR84-95. In contrast, desensitization with WKYMVm, which also binds FPRL2, markedly inhibited the response to both molecules. Thus, uPA is a potent chemoattractant for basophils that seems to act through exposure of the chemotactic uPAR epitope uPAR84-95, which is an endogenous ligand for FPRL2 and FPRL1.
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MESH Headings
- Adult
- Basophils/cytology
- Basophils/enzymology
- Basophils/metabolism
- Cell Line, Tumor
- Chemotaxis, Leukocyte/immunology
- Cytokines/metabolism
- Enzyme Inhibitors/pharmacology
- Epitopes/metabolism
- Epitopes/physiology
- Histamine Release/drug effects
- Histamine Release/immunology
- Humans
- Hydrolysis
- Isoflurophate/pharmacology
- Ligands
- Peptide Fragments/physiology
- Protein Structure, Tertiary
- RNA, Messenger/biosynthesis
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/metabolism
- Receptors, Cell Surface/physiology
- Receptors, Formyl Peptide/biosynthesis
- Receptors, Formyl Peptide/metabolism
- Receptors, Lipoxin/biosynthesis
- Receptors, Lipoxin/metabolism
- Receptors, Urokinase Plasminogen Activator
- Urokinase-Type Plasminogen Activator/antagonists & inhibitors
- Urokinase-Type Plasminogen Activator/biosynthesis
- Urokinase-Type Plasminogen Activator/physiology
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Affiliation(s)
- Amato de Paulis
- Divisione di Immunologia Clinica ed Allergologia, Università di Napoli Federico II, Naples, Italy
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Postma B, Poppelier MJ, van Galen JC, Prossnitz ER, van Strijp JAG, de Haas CJC, van Kessel KPM. Chemotaxis inhibitory protein of Staphylococcus aureus binds specifically to the C5a and formylated peptide receptor. THE JOURNAL OF IMMUNOLOGY 2004; 172:6994-7001. [PMID: 15153520 DOI: 10.4049/jimmunol.172.11.6994] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) is an exoprotein produced by several strains of S. aureus, and a potent inhibitor of neutrophil and monocyte chemotaxis toward C5a and formylated peptides like fMLP. These chemoattractants act on their target cells by binding and activating the C5aR and formylated peptide receptor (FPR), respectively. In the present report, we examined the mechanism by which CHIPS affects both of these receptors. We showed that CHIPS blocked binding of anti-C5aR mAb and formylated peptide to human neutrophils as efficiently at temperatures of 0 and 37 degrees C, implying that it is independent of signal transducing systems. This was confirmed by showing that CHIPS acts completely independently of ATP. Additionally, CHIPS was not internalized upon binding to neutrophils. Furthermore, we showed that CHIPS binds specifically to the C5aR and FPR expressed on U937 cells. This binding was functional in blocking C5a- and fMLP-induced calcium mobilization in these cell lines. These results suggest that CHIPS binds directly to the C5aR and FPR, thereby preventing the natural ligands from activating these receptors. The apparent K(d) values of CHIPS for the C5aR and FPR were 1.1 +/- 0.2 nM and 35.4 +/- 7.7 nM, respectively. Moreover, after screening a wide variety of other G protein-coupled receptors, CHIPS was found to affect exclusively the C5aR and FPR. This selectivity and high-affinity binding with potent antagonistic effects makes CHIPS a promising lead for the development of new anti-inflammatory compounds for diseases in which damage by neutrophils plays a key role.
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Affiliation(s)
- Bent Postma
- Eijkman-Winkler Institute, University Medical Center Utrecht, Utrecht, The Netherlands
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Chen LY, Ptasznik A, Pan ZK. RhoA and Rac1 signals in fMLP-induced NF-kappaB activation in human blood monocytes. Biochem Biophys Res Commun 2004; 319:629-35. [PMID: 15178452 DOI: 10.1016/j.bbrc.2004.05.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2004] [Indexed: 10/26/2022]
Abstract
GTPase RhoA is required for fMet-Leu-Phe (fMLP)-stimulated NF-kappaB activation in human peripheral blood monocytes. Here we have investigated different members of the Rho family of GTPases Rac1, Cdc42, and RhoA in regulating the transcription factor nuclear factor-kappaB (NF-kappaB) in human peripheral blood monocytes. Stimulation of monocytes with fMLP rapidly activated Rac1, Cdc42, and RhoA and cotransfection of the monocytic THP1 cells with dominant negative forms of Rho GTPases, we found that Rac1 and RhoA, but not Cdc42, involved fMLP-stimulated kappaB reporter gene expression. These results indicate that fMLP stimulates three members of the Rho family of GTPases Rac1, Cdc42, and RhoA activity in monocytes, and that Rac1 and RhoA, but not Cdc42, is required for fMLP-induced NF-kappaB activation. Furthermore, our data also suggest that RhoA is mediated by signals independent of Rac1 in NF-kappaB activation in human peripheral blood monocytes stimulated with bacterial products.
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Affiliation(s)
- Ling-Yu Chen
- Department of Microbiology and Immunology, Medical College of Ohio, Toledo, OH 43614, USA
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47
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de Paulis A, Prevete N, Fiorentino I, Walls AF, Curto M, Petraroli A, Castaldo V, Ceppa P, Fiocca R, Marone G. Basophils Infiltrate Human Gastric Mucosa at Sites of Helicobacter pylori Infection, and Exhibit Chemotaxis in Response to H. pylori-derived Peptide Hp(2–20). THE JOURNAL OF IMMUNOLOGY 2004; 172:7734-43. [PMID: 15187157 DOI: 10.4049/jimmunol.172.12.7734] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Basophils, which are normally confined to the circulation, can migrate to sites of allergic inflammation. Using the specific mAb, BB1, we detected basophil infiltration of the gastric mucosa of Helicobacter pylori-infected patients affected by moderate and severe gastritis. Basophils were not found in H. pylori-free individuals or in subjects with mild gastritis. The H. pylori-derived peptide, Hp(2-20), was a potent basophil chemoattractant in vitro, whereas the control peptide, Hp1, was ineffective. Basophils from peripheral blood of healthy volunteers expressed mRNA for the formyl peptide receptors, N-formyl-peptide receptor (FPR), FPR-like (FPRL)1, and FPRL2. Preincubation of basophils with FMLP or Hp(2-20) caused complete desensitization to a subsequent challenge with homologous stimulus. Incubation of basophils with a low concentration of FMLP, which binds with high affinity to FPR, but not to FPRL1 or FPRL2, did not affect the chemotactic response to Hp(2-20). In contrast, a high concentration of FMLP, which binds to FPRL1 and FPRL2, reduced the chemotactic response to Hp(2-20). The FPR antagonist, cyclosporin H, prevented chemotaxis induced by FMLP, but not by Hp(2-20). Hp(2-20) could be responsible, at least in part, for basophil infiltration of the gastric mucosa of H. pylori-infected patients presumably through the interaction with FPRL1 and FPRL2.
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Affiliation(s)
- Amato de Paulis
- Department of Clinical Immunology and Allergy, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
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48
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Paclet MH, Davis C, Kotsonis P, Godovac-Zimmermann J, Segal AW, Dekker LV. N-Formyl peptide receptor subtypes in human neutrophils activate L-plastin phosphorylation through different signal transduction intermediates. Biochem J 2004; 377:469-77. [PMID: 14556648 PMCID: PMC1223878 DOI: 10.1042/bj20031114] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Revised: 10/02/2003] [Accepted: 10/13/2003] [Indexed: 11/17/2022]
Abstract
We investigated the coupling of the fMLP (N -formyl-L-methionyl-L-leucyl-L-phenylalanine; 'chemotactic peptide') receptor with phosphorylation of the actin-binding protein L-plastin in neutrophils. Using two-dimensional IEF (isoelectric focusing)/PAGE and MALDI-TOF (matrix-assisted laser desorption ionization-time-of-flight)-MS, L-plastin was identified as a major phosphoprotein in fMLP-stimulated neutrophils whose phosphorylation was dependent on phosphoinositide 3-kinase, PLD (phospholipase D) and PKC (protein kinase C) activity. Two fMLP receptor subtypes were identified in neutrophils, characterized by a distinct sensitivity to fMLP and antagonistic peptides. Both receptor subtypes induced the phosphorylation of L-plastin. L-plastin phosphorylation induced by low-affinity fMLP receptors involves an action of phosphoinositide 3-kinase, PLD and PKC isotypes. In contrast, none of these intermediates are utilized by high-affinity fMLP receptors in the phosphorylation of L-plastin. However, the PKC inhibitor Ro-31-8220 inhibits L-plastin phosphorylation induced by the high-affinity fMLP receptor. Thus, an as yet unknown Ro-31-8220-sensitive kinase regulates L-plastin phosphorylation in response to the high-affinity fMLP receptor. The results suggest a model in which receptor subtypes induce a similar endpoint event through different signal-transduction intermediates. This may be relevant in the context of cell migration in which one receptor subpopulation may become desensitized in a concentration gradient of chemoattractant.
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Affiliation(s)
- Marie-Hélène Paclet
- Department of Medicine, Centre for Molecular Medicine, The Rayne Institute, University College London, UK.
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Kenakin T. Efficacy as a Vector: the Relative Prevalence and Paucity of Inverse Agonism. Mol Pharmacol 2004; 65:2-11. [PMID: 14722230 DOI: 10.1124/mol.65.1.2] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
This article describes the expected phenotypic behavior of all types of ligands in constitutively active receptor systems and, in particular, the molecular mechanisms of inverse agonism. The possible physiological relevance of inverse agonism also is discussed. Competitive antagonists with the molecular property of negative efficacy demonstrate inverse agonism in constitutively active receptor systems. This is a phenotypic behavior that can only be observed in the appropriate assay; a lack of observed inverse agonism is evidence that the ligand does not possess negative efficacy only if it can be shown that constitutive receptor activity is present. In the absence of constitutive activity, inverse agonists behave as simple competitive antagonists. A survey of 105 articles on the activity of 380 antagonists on 73 biological G-protein-coupled receptor targets indicates that, in this sample dataset, 322 are inverse agonists and 58 (15%) are neutral antagonists. The predominance of inverse agonism agrees with theoretical predictions which indicate that neutral antagonists are the minority species in pharmacological space.
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Affiliation(s)
- Terry Kenakin
- Department of Assay Development and Compound Profiling, GlaxoSmithKline Research and Development, Research Triangle Park, NC 27709, USA.
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Seifert R, Wenzel-Seifert K. The human formyl peptide receptor as model system for constitutively active G-protein-coupled receptors. Life Sci 2003; 73:2263-80. [PMID: 12941430 DOI: 10.1016/s0024-3205(03)00654-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
According to the two-state model of G-protein-coupled receptor (GPCR) activation, GPCRs isomerize from an inactive (R) state to an active (R*) state. In the R* state, GPCRs activate G-proteins. Agonist-independent R/R* isomerization is referred to as constitutive activity and results in an increase in basal G-protein activity, i.e. GDP/GTP exchange. Agonists stabilize the R* state and further increase, whereas inverse agonists stabilize the R state and decrease, basal G-protein activity. Constitutive activity is observed in numerous wild-type GPCRs and disease-causing GPCR mutants with increased constitutive activity. The human formyl peptide receptor (FPR) exists in several isoforms (FPR-26, FPR-98 and FPR-G6) and activates chemotaxis and cytotoxic cell functions of phagocytes through G(i)-proteins. Studies in HL-60 leukemia cell membranes demonstrated inhibitory effects of Na(+) and pertussis toxin on basal G(i)-protein activity, suggesting that the FPR is constitutively active. However, since HL-60 cells express several constitutively active chemoattractant receptors, analysis of constitutive FPR activity was difficult. Sf9 insect cells do not express chemoattractant receptors and G(i)-proteins and provide a sensitive reconstitution system for FPR/G(i)-protein coupling. Such expression studies showed that FPR-26 is much more constitutively active than FPR-98 and FPR-G6 as assessed by the relative inhibitory effects of Na(+) and of the inverse agonist cyclosporin H on basal G(i)-protein activity. Site-directed mutagenesis studies suggest that the E346A exchange in the C-terminus critically determines dimerization and constitutive activity of FPR. Moreover, N-glycosylation of the N-terminus seems to be important for constitutive FPR activity. Finally, we discuss some future directions of research.
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Affiliation(s)
- Roland Seifert
- Department of Pharmacology and Toxicology, The University of Kansas, Malott Hall, Room 5064, 1251 Wescoe Hall Drive, Lawrence, KS 66045-7582, USA.
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