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Kappes L, Amer RL, Sommerlatte S, Bashir G, Plattfaut C, Gieseler F, Gemoll T, Busch H, Altahrawi A, Al-Sbiei A, Haneefa SM, Arafat K, Schimke LF, Khawanky NE, Schulze-Forster K, Heidecke H, Kerstein-Staehle A, Marschner G, Pitann S, Ochs HD, Mueller A, Attoub S, Fernandez-Cabezudo MJ, Riemekasten G, Al-Ramadi BK, Cabral-Marques O. Ambrisentan, an endothelin receptor type A-selective antagonist, inhibits cancer cell migration, invasion, and metastasis. Sci Rep 2020; 10:15931. [PMID: 32985601 PMCID: PMC7522204 DOI: 10.1038/s41598-020-72960-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 09/07/2020] [Indexed: 12/17/2022] Open
Abstract
Several studies reported a central role of the endothelin type A receptor (ETAR) in tumor progression leading to the formation of metastasis. Here, we investigated the in vitro and in vivo anti-tumor effects of the FDA-approved ETAR antagonist, Ambrisentan, which is currently used to treat patients with pulmonary arterial hypertension. In vitro, Ambrisentan inhibited both spontaneous and induced migration/invasion capacity of different tumor cells (COLO-357 metastatic pancreatic adenocarcinoma, OvCar3 ovarian carcinoma, MDA-MB-231 breast adenocarcinoma, and HL-60 promyelocytic leukemia). Whole transcriptome analysis using RNAseq indicated Ambrisentan's inhibitory effects on the whole transcriptome of resting and PAR2-activated COLO-357 cells, which tended to normalize to an unstimulated profile. Finally, in a pre-clinical murine model of metastatic breast cancer, treatment with Ambrisentan was effective in decreasing metastasis into the lungs and liver. Importantly, this was associated with a significant enhancement in animal survival. Taken together, our work suggests a new therapeutic application for Ambrisentan in the treatment of cancer metastasis.
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Affiliation(s)
- Lucy Kappes
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Ruba L Amer
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Sabine Sommerlatte
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Ghada Bashir
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Corinna Plattfaut
- Section Experimental Oncology, University Hospital and Medical School (UKSH), University of Lübeck, Lübeck, Germany
| | - Frank Gieseler
- Section Experimental Oncology, University Hospital and Medical School (UKSH), University of Lübeck, Lübeck, Germany
| | - Timo Gemoll
- Section for Translational Surgical Oncology and Biobanking, Department of Surgery, University of Lübeck and University Medical Center Schleswig-Holstein, Lübeck, Germany
| | - Hauke Busch
- Lübeck Institute for Experimental Dermatology (LIED) and Institute of Cardiogenetics, University of Lübeck, Lübeck, Germany
| | - Abeer Altahrawi
- Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Ashraf Al-Sbiei
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Shoja M Haneefa
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Kholoud Arafat
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Lena F Schimke
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Nadia El Khawanky
- Department of Hematology and Oncology, Faculty of Medicine, The University of Freiburg, Freiburg, Germany
| | - Kai Schulze-Forster
- CellTrend GmbH, Luckenwalde, Brandenburg, Germany
- Department of Urology, Charité University Hospital, Berlin, Germany
| | | | - Anja Kerstein-Staehle
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Gabriele Marschner
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Silke Pitann
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Hans D Ochs
- Department of Pediatrics, University of Washington School of Medicine, and Seattle Children's Research Institute, Seattle, WA, USA
| | - Antje Mueller
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Samir Attoub
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Maria J Fernandez-Cabezudo
- Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Gabriela Riemekasten
- Department of Rheumatology and Clinical Immunology, University of Lübeck, Lübeck, Germany
| | - Basel K Al-Ramadi
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates.
| | - Otavio Cabral-Marques
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Lineu Prestes Avenue, 1730, São Paulo, SP, Brazil.
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
- Network of Immunity in Infection, Malignancy, and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), São Paulo, Brazil.
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Naider F, Becker JM. A Paradigm for Peptide Hormone-GPCR Analyses. Molecules 2020; 25:E4272. [PMID: 32961885 PMCID: PMC7570734 DOI: 10.3390/molecules25184272] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/16/2020] [Accepted: 09/17/2020] [Indexed: 01/14/2023] Open
Abstract
Work from our laboratories over the last 35 years that has focused on Ste2p, a G protein-coupled receptor (GPCR), and its tridecapeptide ligand α-factor is reviewed. Our work utilized the yeast Saccharomyces cerevisiae as a model system for understanding peptide-GPCR interactions. It explored the structure and function of synthetic α-factor analogs and biosynthetic receptor domains, as well as designed mutations of Ste2p. The results and conclusions are described using the nuclear magnetic resonance interrogation of synthetic Ste2p transmembrane domains (TMs), the fluorescence interrogation of agonist and antagonist binding, the biochemical crosslinking of peptide analogs to Ste2p, and the phenotypes of receptor mutants. We identified the ligand-binding domain in Ste2p, the functional assemblies of TMs, unexpected and interesting ligand analogs; gained insights into the bound α-factor structure; and unraveled the function and structures of various Ste2p domains, including the N-terminus, TMs, loops connecting the TMs, and the C-terminus. Our studies showed interactions between specific residues of Ste2p in an active state, but not resting state, and the effect of ligand activation on the dimerization of Ste2p. We show that, using a battery of different biochemical and genetic approaches, deep insight can be gained into the structure and conformational dynamics of GPCR-peptide interactions in the absence of a crystal structure.
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Affiliation(s)
- Fred Naider
- Department of Chemistry, College of Staten Island, CUNY, 2800 Victory Blvd, Staten Island, NY 10314, USA
| | - Jeffrey M. Becker
- Department of Microbiology, University of Tennessee, 610 Ken and Blaire Mossman Building, 1311 Cumberland Avenue, Knoxville, TN 37996, USA
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Bellinger DL, Lorton D. Sympathetic Nerve Hyperactivity in the Spleen: Causal for Nonpathogenic-Driven Chronic Immune-Mediated Inflammatory Diseases (IMIDs)? Int J Mol Sci 2018; 19:ijms19041188. [PMID: 29652832 PMCID: PMC5979464 DOI: 10.3390/ijms19041188] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 04/05/2018] [Accepted: 04/05/2018] [Indexed: 12/21/2022] Open
Abstract
Immune-Mediated Inflammatory Diseases (IMIDs) is a descriptive term coined for an eclectic group of diseases or conditions that share common inflammatory pathways, and for which there is no definitive etiology. IMIDs affect the elderly most severely, with many older individuals having two or more IMIDs. These diseases include, but are not limited to, type-1 diabetes, obesity, hypertension, chronic pulmonary disease, coronary heart disease, inflammatory bowel disease, and autoimmunity, such as rheumatoid arthritis (RA), Sjőgren's syndrome, systemic lupus erythematosus, psoriasis, psoriatic arthritis, and multiple sclerosis. These diseases are ostensibly unrelated mechanistically, but increase in frequency with age and share chronic systemic inflammation, implicating major roles for the spleen. Chronic systemic and regional inflammation underlies the disease manifestations of IMIDs. Regional inflammation and immune dysfunction promotes targeted end organ tissue damage, whereas systemic inflammation increases morbidity and mortality by affecting multiple organ systems. Chronic inflammation and skewed dysregulated cell-mediated immune responses drive many of these age-related medical disorders. IMIDs are commonly autoimmune-mediated or suspected to be autoimmune diseases. Another shared feature is dysregulation of the autonomic nervous system and hypothalamic pituitary adrenal (HPA) axis. Here, we focus on dysautonomia. In many IMIDs, dysautonomia manifests as an imbalance in activity/reactivity of the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS). These major autonomic pathways are essential for allostasis of the immune system, and regulating inflammatory processes and innate and adaptive immunity. Pathology in ANS is a hallmark and causal feature of all IMIDs. Chronic systemic inflammation comorbid with stress pathway dysregulation implicate neural-immune cross-talk in the etiology and pathophysiology of IMIDs. Using a rodent model of inflammatory arthritis as an IMID model, we report disease-specific maladaptive changes in β₂-adrenergic receptor (AR) signaling from protein kinase A (PKA) to mitogen activated protein kinase (MAPK) pathways in the spleen. Beta₂-AR signal "shutdown" in the spleen and switching from PKA to G-coupled protein receptor kinase (GRK) pathways in lymph node cells drives inflammation and disease advancement. Based on these findings and the existing literature in other IMIDs, we present and discuss relevant literature that support the hypothesis that unresolvable immune stimulation from chronic inflammation leads to a maladaptive disease-inducing and perpetuating sympathetic response in an attempt to maintain allostasis. Since the role of sympathetic dysfunction in IMIDs is best studied in RA and rodent models of RA, this IMID is the primary one used to evaluate data relevant to our hypothesis. Here, we review the relevant literature and discuss sympathetic dysfunction as a significant contributor to the pathophysiology of IMIDs, and then discuss a novel target for treatment. Based on our findings in inflammatory arthritis and our understanding of common inflammatory process that are used by the immune system across all IMIDs, novel strategies to restore SNS homeostasis are expected to provide safe, cost-effective approaches to treat IMIDs, lower comorbidities, and increase longevity.
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Affiliation(s)
- Denise L Bellinger
- Department of Pathology and Human Anatomy, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA.
| | - Dianne Lorton
- College of Arts and Sciences, Kent State University, Kent, OH 44304, USA.
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Bhalla S, Andurkar SV, Gulati A. Neurobiology of opioid withdrawal: Role of the endothelin system. Life Sci 2016; 159:34-42. [DOI: 10.1016/j.lfs.2016.01.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/06/2016] [Accepted: 01/11/2016] [Indexed: 02/04/2023]
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5
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Skovsted GF, Kilic S, Edvinsson L. Endothelin-1 and Endothelin-3 Regulate Endothelin Receptor Expression in Rat Coronary Arteries. Basic Clin Pharmacol Toxicol 2015; 117:297-305. [PMID: 25891848 DOI: 10.1111/bcpt.12407] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 04/07/2015] [Indexed: 11/30/2022]
Abstract
In ischaemic hearts, endothelin (ET) levels are increased, and vasoconstrictor responses to ET-1 are greatly enhanced. We previously reported that ETB receptors are up-regulated in the smooth muscle layer of coronary arteries after myocardial ischaemia-reperfusion and that the MEK-ERK1/2 signalling pathway is involved in ETB receptor up-regulation. Whether ETs are directly involved in receptor regulation has not been determined. We suggest that ET-1 and ET-3 alter the expression/activity of ET receptors in coronary vascular smooth muscle cells. Vasoconstrictor responses were studied in endothelium-denuded coronary artery segments from rats that were subjected to experimental ischaemia-reperfusion or in organ-cultured segments. Post-ischaemic and cultured coronary arteries exhibited similar increased sensitivity to ET-3. ETA receptor-mediated vasoconstriction was dominant in fresh and non-ischaemic arteries. Organ culture significantly up-regulated ETB receptors and down-regulated ETA receptor expression. Co-incubation with ET-1 (1 nM) or ET-3 (100 nM) induced further down-regulation of the ETA receptor mRNA, while the function and protein level of ETA remained unchanged. ET-3 (100 nM) further up-regulated ETB receptor mRNA and proteins but abolished ETB receptor-mediated vasoconstriction, suggesting a desensitization of ETB receptors that was not observed with ET-3 (1 nM). In conclusion, ET-1, which is the most prevalent isoform in the cardiovascular system, induces down-regulation of ETA receptor expression without changing ETA or ETB receptor function or protein levels. Intermediate concentrations of ET-3 had an effect that was similar to that of ET-1, such that high concentrations of ET-3 (100 nM) up-regulated the ETB receptor at the gene and protein levels but switched off the function of the ETB receptors via desensitization.
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Affiliation(s)
- Gry Freja Skovsted
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup Hospital, Copenhagen, Denmark
| | - Semsi Kilic
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup Hospital, Copenhagen, Denmark
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup Hospital, Copenhagen, Denmark.,Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Lund, Sweden
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6
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Molecular mechanisms underlying β-adrenergic receptor-mediated cross-talk between sympathetic neurons and immune cells. Int J Mol Sci 2015; 16:5635-65. [PMID: 25768345 PMCID: PMC4394497 DOI: 10.3390/ijms16035635] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 02/13/2015] [Accepted: 03/04/2015] [Indexed: 01/01/2023] Open
Abstract
Cross-talk between the sympathetic nervous system (SNS) and immune system is vital for health and well-being. Infection, tissue injury and inflammation raise firing rates of sympathetic nerves, increasing their release of norepinephrine (NE) in lymphoid organs and tissues. NE stimulation of β2-adrenergic receptors (ARs) in immune cells activates the cAMP-protein kinase A (PKA) intracellular signaling pathway, a pathway that interfaces with other signaling pathways that regulate proliferation, differentiation, maturation and effector functions in immune cells. Immune-SNS cross-talk is required to maintain homeostasis under normal conditions, to develop an immune response of appropriate magnitude after injury or immune challenge, and subsequently restore homeostasis. Typically, β2-AR-induced cAMP is immunosuppressive. However, many studies report actions of β2-AR stimulation in immune cells that are inconsistent with typical cAMP-PKA signal transduction. Research during the last decade in non-immune organs, has unveiled novel alternative signaling mechanisms induced by β2-AR activation, such as a signaling switch from cAMP-PKA to mitogen-activated protein kinase (MAPK) pathways. If alternative signaling occurs in immune cells, it may explain inconsistent findings of sympathetic regulation of immune function. Here, we review β2-AR signaling, assess the available evidence for alternative signaling in immune cells, and provide insight into the circumstances necessary for "signal switching" in immune cells.
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7
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Yoshikawa T, Kanazawa H, Fujimoto S, Hirata K. Epistatic effects of multiple receptor genes on pathophysiology of asthma - its limits and potential for clinical application. Med Sci Monit 2014; 20:64-71. [PMID: 24435185 PMCID: PMC3907491 DOI: 10.12659/msm.889754] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 11/09/2013] [Indexed: 01/31/2023] Open
Abstract
To date, genome-wide association studies (GWAS) permit a comprehensive scan of the genome in an unbiased manner, with high sensitivity, and thereby have the potential to identify candidate genes for the prevalence or development of multifactorial diseases such as bronchial asthma. However, most studies have only managed to explain a small additional percentage of hereditability estimates, and often fail to show consistent results among studies despite large sample sizes. Epistasis is defined as the interaction between multiple different genes affecting phenotypes. By applying epistatic analysis to clinical genetic research, we can analyze interactions among more than 2 molecules (genes) considering the whole system of the human body, illuminating dynamic molecular mechanisms. An increasing number of genetic studies have investigated epistatic effects on the risk for development of asthma. The present review highlights a concept of epistasis to overcome traditional genetic studies in humans and provides an update of evidence on epistatic effects on asthma. Furthermore, we review concerns regarding recent trends in epistatic analyses from the perspective of clinical physicians. These concerns include biological plausibility of genes identified by computational statistics, and definition of the diagnostic label of 'physician-diagnosed asthma'. In terms of these issues, further application of epistatic analysis will prompt identification of susceptibility of diseases and lead to the development of a new generation of pharmacological strategies to treat asthma.
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Affiliation(s)
- Takahiro Yoshikawa
- Department of Sports Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Hiroshi Kanazawa
- Department of Respiratory Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Shigeo Fujimoto
- Department of Sports Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Kazuto Hirata
- Department of Respiratory Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
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8
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Čikoš Š, Czikková S, Chrenek P, Makarevich AV, Burkuš J, Janštová Ž, Fabian D, Koppel J. Expression of adrenergic receptors in bovine and rabbit oocytes and preimplantation embryos. Reprod Domest Anim 2013; 49:92-100. [PMID: 23991902 DOI: 10.1111/rda.12233] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 08/03/2013] [Indexed: 01/21/2023]
Abstract
Catecholamines play an important role in embryogenesis, and data obtained in the rodent model indicate that they can act even during the preimplantation period of development. Using RT-PCR with specific oligonucleotide primers distinguishing among all members of the adrenergic receptor family, we examined expression of adrenergic receptors in bovine and rabbit oocytes, morulas and blastocysts. We found several profiles of adrenoceptor mRNA expression. Transcripts for some receptor subtypes (bovine alpha 2 receptors, rabbit α2A, α2C, β1 and β2 receptors) were detected at all examined stages, which suggests receptor expression throughout (or at most stages) the preimplantation developmental period. Expression in oocytes but not at later stages was found in only one adrenoceptor subtype (rabbit α1B). In contrast, mRNA for several adrenoceptors was found in embryos but not in oocytes (bovine beta adrenoceptors and rabbit α1A). Nucleotide sequences of our PCR products amplified in rabbit oocytes, and preimplantation embryos represent the first published mRNA sequences (partial sequences coding at least one transmembrane region) of rabbit α2C, β1 and β2 adrenoceptors. Our results suggest that the expression of adrenergic receptors can be a general feature of mammalian oocytes and preimplantation embryos. On the other hand, comparison of three mammalian species (cattle, rabbit and mouse) revealed possible interspecies differences in the expression of particular adrenoceptor subtypes. Our results support the opinion that stress mediators can act directly in cells of preimplantation embryos.
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Affiliation(s)
- Š Čikoš
- Institute of Animal Physiology, Slovak Academy of Sciences, Košice, Slovakia
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9
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Maguire JJ, Kuc RE, Pell VR, Green A, Brown M, Kumar S, Wehrman T, Quinn E, Davenport AP. Comparison of human ETA and ETB receptor signalling via G-protein and β-arrestin pathways. Life Sci 2012; 91:544-9. [PMID: 22480514 DOI: 10.1016/j.lfs.2012.03.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 03/05/2012] [Accepted: 03/08/2012] [Indexed: 02/04/2023]
Abstract
AIMS To determine the pharmacology of ET(A)- and ET(B)-mediated β-arrestin recruitment and compare this to established human pharmacology of these receptors to identify evidence for endothelin receptor biased signalling and pathway specific blockade by antagonists. MAIN METHODS The ability of ET-1, ET-2, ET-3, sarafotoxin 6b and sarafotoxin 6c to activate ET(A) and ET(B)-mediated β-arrestin recruitment was determined in CHO-K1 cells. Affinities were obtained for ET(A) selective (BQ123, sitaxentan, ambrisentan), ET(B) selective (BQ788) and mixed (bosentan) antagonists using ET-1 and compared to affinities obtained in competition experiments in human heart and by Schild analysis in human saphenous vein. Agonist dependence of affinities was compared for BQ123 and BQ788 in the ET(A) and ET(B) β-arrestin assays respectively. KEY FINDINGS For β-arrestin recruitment, order of potency was as expected for the ET(A) (ET-1≥ET-2>>ET-3) and ET(B) (ET-1=ET-2=ET-3) receptors. However, at the ET(A) receptor sarafotoxin 6b and ET-3 were partial agonists. Antagonism of ET peptides by selective and mixed antagonists appeared non-competitive. BQ123, but not BQ788, exhibited agonist-dependent affinities. Bosentan was significantly more effective an inhibitor of β-arrestin recruitment mediated by ET(A) compared to the ET(B) receptor. In the ET(A) vasoconstrictor assay, ET-1, ET-2 and S6b were equipotent, full agonists and antagonists tested behaved in a competitive manner, although affinities were lower than predicted from the competition binding experiments in left ventricle. SIGNIFICANCE These data suggest that the pharmacology of ET(A) and ET(B) receptors linked to G-protein- and β-arrestin mediated responses was different and bosentan appeared to show bias, preferentially blocking ET(A) mediated β-arrestin recruitment.
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Affiliation(s)
- Janet J Maguire
- Clinical Pharmacology Unit, University of Cambridge, Level 6 ACCI, Box 110 Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK.
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Stroth N, Svenningsson P. Ligand-specific differential regulation of 5-hydroxytryptamine receptors: functional selectivity in serotonergic signaling. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/wmts.39] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Hudson BD, Kelly MEM. Identification of novel competing β2AR phospho-extracellular signal regulated kinase 1/2 signaling pathways in human trabecular meshwork cells. J Ocul Pharmacol Ther 2011; 28:17-25. [PMID: 22010988 DOI: 10.1089/jop.2011.0016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE β-Adrenergic receptor (βAR) agonists reduce intraocular pressure (IOP) by increasing aqueous outflow through the trabecular meshwork (TM). However, although this effect is well established, the specific signaling mechanisms responsible are less clear. To address this, the current study examined βAR signaling in primary human trabecular meshwork cells (HTMCs), specifically, focusing on the effect of βAR activation on the extracellular signal regulated kinases 1/2 (ERK). METHODS HTMCs were cultured and assessed for βAR expression by both immunofluorescence and reverse-transcription-polymerase chain reaction. The effect of βAR activation on ERK phosphorylation was examined in these cells by In-Cell Western™ analysis. Pharmacological approaches were used to characterize the mechanism of the βAR effect on ERK. RESULTS Treatment of HTMCs with the nonselective βAR agonist, isoproterenol (ISO), decreased the basal phospho-ERK (pERK) level, through actions at the β2AR. The response was insensitive to pertussis toxin (PTx), but pretreatment with cholera toxin (CTx) resulted in a reversal of the response, such that ISO treatment instead increased pERK, thus implicating Gα(s) in the inhibitory pERK response. The adenylyl cyclase activator, forskolin, also decreased pERK, suggesting the involvement of adenylyl cyclase and cAMP, whereas a protein kinase A (PKA) inhibitor, H-89, blocked both ISO and forskolin-mediated pERK inhibition in HTMCs. Finally, a closer examination of the pERK increase generated in the presence of CTx demonstrated that it was also insensitive to PTx, and appeared to have differing rank orders of efficacy for various βAR agonists compared with the inhibitory pERK pathway in HTMCs. CONCLUSION A novel β(2)AR-signaling pathway leading to a decrease in pERK, which was dependent on Gα(s), cAMP, and PKA, was identified in HTMCs. A competing β(2)AR signaling pathway resulting in increased pERK was also identified. Since βAR effects on aqueous humor (AH) outflow have been linked to cAMP, and inhibition of ERK in TM cells has recently been suggested as increasing AH outflow, our findings suggest that the inhibitory β(2)AR-pERK pathway likely represents the mechanism by which βAR agonists decrease IOP. The presence of a competing β(2)AR-ERK activation pathway in the same cells suggests that this is an ideal system for the development and validation of functionally selective β(2)AR agonists.
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Affiliation(s)
- Brian D Hudson
- Department of Pharmacology, Dalhousie University, Halifax, Canada
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12
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Impedance measurement: A new method to detect ligand-biased receptor signaling. Biochem Biophys Res Commun 2011; 412:419-24. [DOI: 10.1016/j.bbrc.2011.07.087] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 07/20/2011] [Indexed: 01/14/2023]
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13
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Schulte G. International Union of Basic and Clinical Pharmacology. LXXX. The class Frizzled receptors. Pharmacol Rev 2011; 62:632-67. [PMID: 21079039 DOI: 10.1124/pr.110.002931] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The receptor class Frizzled, which has recently been categorized as a separate group of G protein-coupled receptors by the International Union of Basic and Clinical Pharmacology, consists of 10 Frizzleds (FZD(1-10)) and Smoothened (SMO). The FZDs are activated by secreted lipoglycoproteins of the Wingless/Int-1 (WNT) family, whereas SMO is indirectly activated by the Hedgehog (HH) family of proteins acting on the transmembrane protein Patched (PTCH). Recent years have seen major advances in our knowledge about these seven-transmembrane-spanning proteins, including: receptor function, molecular mechanisms of signal transduction, and the receptor's role in embryonic patterning, physiology, cancer, and other diseases. Despite intense efforts, many question marks and challenges remain in mapping receptor-ligand interaction, signaling routes, mechanisms of specificity and how these molecular details underlie disease and also the receptor's important role in physiology. This review therefore focuses on the molecular aspects of WNT/FZD and HH/SMO signaling discussing receptor structure, mechanisms of signal transduction, accessory proteins, receptor dynamics, and the possibility of targeting these signaling pathways pharmacologically.
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Affiliation(s)
- Gunnar Schulte
- Section of Receptor Biology & Signaling, Dept. of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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14
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Savergnini SQ, Beiman M, Lautner RQ, de Paula-Carvalho V, Allahdadi K, Pessoa DC, Costa-Fraga FP, Fraga-Silva RA, Cojocaru G, Cohen Y, Bader M, de Almeida AP, Rotman G, Santos RAS. Vascular Relaxation, Antihypertensive Effect, and Cardioprotection of a Novel Peptide Agonist of the Mas Receptor. Hypertension 2010; 56:112-20. [DOI: 10.1161/hypertensionaha.110.152942] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mas stimulation with angiotensin (Ang)-(1-7) produces cardioprotective effects and vasorelaxation. Using a computational discovery platform for predicting novel naturally occurring peptides that may activate G protein–coupled receptors, we discovered a novel Mas agonist peptide, CGEN-856S. An endothelium- and NO-dependent vasodilating effect was observed for CGEN-856S in thoracic aorta rings of rats (maximal value for the relaxant effect: 39.99±5.034%), which was similar to that produced by Ang-(1-7) (10
−10
to 10
−6
mol/L). In addition, the vasodilator activity of this peptide depended on a functional Mas receptor, because it was abolished in aorta rings of Mas-knockout mice. CGEN-856S appears to bind the Mas receptor at the same binding domain as Ang-(1-7), as suggested by the blocking of its vasorelaxant effect with the Ang-(1-7) analogue
d
-Ala
7
-Ang-(1-7), and by its competitive inhibition of Ang-(1-7) binding to
Mas
-transfected cells. The effect of CGEN-856S on reperfusion arrhythmias and cardiac function was studied on ischemia reperfusion of isolated rat hearts. We found that picomolar concentration of CGEN-856S (0.04 nmol/L) had an antiarrhythmogenic effect, as demonstrated by a reduction in the incidence and duration of reperfusion arrhythmias. Furthermore, acute infusion of CGEN-856S produced a shallow dose-dependent decrease in mean arterial pressure of conscious spontaneously hypertensive rats. The maximum change during infusion was observed at the highest dose. Strikingly, blood pressure continued to drop in the postinfusion period. The results presented here indicate that the novel Mas agonist, CGEN-856S, might have a therapeutic value, because it induces vasorelaxing, antihypertensive, and cardioprotective effects.
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Affiliation(s)
- Silvia Quintão Savergnini
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Merav Beiman
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Roberto Queiroga Lautner
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Vanice de Paula-Carvalho
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Kyan Allahdadi
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Dalton Caires Pessoa
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Fabiana Pereira Costa-Fraga
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Rodrigo Araújo Fraga-Silva
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Gady Cojocaru
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Yossi Cohen
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Michael Bader
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Alvair Pinto de Almeida
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Galit Rotman
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
| | - Robson Augusto Souza Santos
- From the Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica (INCT-Nanobiofar) (S.Q.S., R.Q.L., V.P.-C., K.A., D.C.P., F.P.C.-F., R.A.F.-S., A.P.A., R.A.S.S.), Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Compugen Ltd (M.Be., G.C., Y.C., G.R.), Tel Aviv, Israel; Max-Delbrück-Center for Molecular Medicine (M.Ba.), Berlin-Buch, Germany
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15
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Wang Y, Li A, Wang X, Zhang X, Zhao W, Dou D, Zheng X, Wang Y. GPR11, a putative seven-transmembrane G protein-coupled receptor, controls zoospore development and virulence of Phytophthora sojae. EUKARYOTIC CELL 2010; 9:242-50. [PMID: 20008081 PMCID: PMC2823010 DOI: 10.1128/ec.00265-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 11/28/2009] [Indexed: 11/20/2022]
Abstract
G protein-coupled receptors (GPCRs) represent a large receptor family involved in a broad spectrum of cell signaling. To understand signaling mechanisms mediated by GPCRs in Phytophthora sojae, we identified and characterized the PsGPR11 gene, which encodes a putative seven-transmembrane GPCR. An expression analysis revealed that PsGPR11 was differentially expressed during asexual development. The highest expression level occurred in zoospores and was upregulated during early infection. PsGPR11-deficienct transformants were obtained by gene silencing strategies. Silenced transformants exhibited no differences in hyphal growth or morphology, sporangium production or size, or mating behavior. However, the release of zoospores from sporangia was severely impaired in the silenced transformants, and about 50% of the sporangia did not completely release their zoospores. Zoospore encystment and germination were also impaired, and zoospores of the transformants lost their pathogenicity to soybean. In addition, no interaction was observed between PsGPR11 and PsGPA1 with a conventional yeast two-hybrid assay, and the transcriptional levels of some genes which were identified as being negatively regulated by PsGPA1 were not clearly altered in PsGPR11-silenced mutants. These results suggest that PsGPR11-mediated signaling controls P. sojae zoospore development and virulence through the pathways independent of G protein.
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Affiliation(s)
- Yonglin Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Aining Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaoli Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Xin Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Wei Zhao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Daolong Dou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaobo Zheng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
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16
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Isoldi MC, Provencio I, Castrucci AMDL. Light modulates the melanophore response to alpha-MSH in Xenopus laevis: an analysis of the signal transduction crosstalk mechanisms involved. Gen Comp Endocrinol 2010; 165:104-10. [PMID: 19539625 DOI: 10.1016/j.ygcen.2009.06.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 06/10/2009] [Accepted: 06/12/2009] [Indexed: 11/30/2022]
Abstract
Melanin granule (melanosome) dispersion within Xenopus laevis melanophores is evoked either by light or alpha-MSH. We have previously demonstrated that the initial biochemical steps of light and alpha-MSH signaling are distinct, since the increase in cAMP observed in response to alpha-MSH was not seen after light exposure. cAMP concentrations in response to alpha-MSH were significantly lower in cells pre-exposed to light as compared to the levels in dark-adapted melanophores. Here we demonstrate the presence of an adenylyl cyclase (AC) in the Xenopus melanophore, similar to the mammalian type IX which is inhibited by Ca(2+)-calmodulin-activated phosphatase. This finding supports the hypothesis that the cyclase could be negatively modulated by a light-promoted Ca(2+) increase. In fact, the activity of calcineurin PP2B phosphatase was increased by light, which could result in AC IX inhibition, thus decreasing the response to alpha-MSH. St-Ht31, a disrupting agent of protein kinase A (PKA)-anchoring kinase A protein (AKAP) complex totally blocked the melanosome dispersing response to alpha-MSH, but did not impair the photo-response in Xenopus melanophores. Sequence comparison of a melanophore AKAP partial clone with GenBank sequences showed that the anchoring protein was a gravin-like adaptor previously sequenced from Xenopus non-pigmentary tissues. Co-immunoprecipitation of Xenopus AKAP and the catalytic subunit of PKA demonstrated that PKA is associated with AKAP and it is released in the presence of alpha-MSH. We conclude that in X. laevis melanophores, AKAP12 (gravin-like) contains a site for binding the inactive PKA thus compartmentalizing PKA signaling and also possesses binding sites for PKC. Light diminishes alpha-MSH-induced increase of cAMP by increasing calcineurin (PP2B) activity, which in turn inhibits adenylyl cyclase type IX, and/or by activating PKC, which phosphorylates the gravin-like molecule, thus destabilizing its binding to the cell membrane.
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Affiliation(s)
- Mauro César Isoldi
- Department of Biology, University of Virginia, Charlotesville, VA 22904-4328, USA
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17
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Kershaw T, Wavre-Shapton ST, Signoret N, Marsh M. Analysis of chemokine receptor endocytosis and intracellular trafficking. Methods Enzymol 2009; 460:357-77. [PMID: 19446735 DOI: 10.1016/s0076-6879(09)05218-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Chemokine receptors are G protein-coupled receptors (GPCRs) that, through their ability to regulate chemotaxis by responding to small chemoattractant peptides termed chemokines, are involved in the development, maintenance, and functional activities of the immune system. In addition, members of the chemokine receptor family have been implicated in a number of other physiological and pathological processes, including human immunodeficiency virus infection and malaria. These activities are dependent on receptor expression at the cell surface and cellular events that reduce the cell-surface expression of chemokine receptors can abrogate these activities. Moreover, internalization of chemokine receptors by endocytosis is necessary for both receptor degradation and recycling, key regulatory processes that determine cell-surface expression levels. Here we provide detailed methods for the quantitative analysis of CCR5 endocytosis and recycling by flow cytometry, as well as fluorescence and electron microscopic procedures to analyze the endocytosis and intracellular trafficking of CCR5 by immunolabeling of cells or cryosections. In principle, the same approaches can be used for analyzing other chemokine receptors and other GPCR or non-GPCR cell-surface proteins.
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Affiliation(s)
- Tom Kershaw
- Cell Biology Unit, MRC Laboratory for Molecular Cell Biology, and Department of Cell and Developmental Biology, University College London, London, United Kingdom
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18
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Abstract
Modulators of G protein-coupled receptors (GPCRs) form a key area for the pharmaceutical industry, representing approximately 27% of all Food and Drug Administration (FDA)-approved drugs. Consequently, there are a wide variety of in vitro plate-based screening technologies that enable the measurement of compound affinity, potency, and efficacy for almost every type of GPCR. However, to maximize success it is prudent to ensure that (i) the most suitable assay formats are identified, (ii) they are configured optimally to detect the desired compound activity, and (iii) that they form a basis for predicting clinical effects. To achieve this, an understanding of the pathways and mechanisms of receptor activation relevant to the disease mechanism, as well as the benefits and/or limitations of the specific techniques, is key.
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19
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Orcel H, Albizu L, Perkovska S, Durroux T, Mendre C, Ansanay H, Mouillac B, Rabié A. Differential coupling of the vasopressin V1b receptor through compartmentalization within the plasma membrane. Mol Pharmacol 2008; 75:637-47. [PMID: 19047484 DOI: 10.1124/mol.108.049031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We show here that the rat vasopressin V(1b) receptor simultaneously activates both the G(q/11)-inositol phosphate (IP) and G(s)-cAMP pathways when transiently expressed in Chinese hamster ovary, human embryonic kidney (HEK) 293, and COS-7 cells and stimulated with arginine-vasopressin. Higher concentrations of the hormone, however, were needed to trigger the cAMP pathway. The nonmammalian analog arginine-vasotocin and the selective V(1b) agonist d[Cha(4)]vasopressin also activated the cAMP and IP pathways, although d[Cha(4)]-vasopressin elicited the two responses with equivalent potencies. We determined that the V(1b) receptor is present as a homodimer at the plasma membrane. Treatment of V(1b)-transfected HEK-293 cells with methyl-beta-cyclodextrin, a drug known to dissociate cholesterol-rich domains of the plasma membrane, shifted the EC(50) of the vasopressin-induced cAMP accumulation to lower concentrations and, remarkably, increased the hormone efficacy related to the activation of this second messenger system. In parallel, the vasopressin-mediated activation of the IP pathway was slightly reduced without modification of its EC(50). These results suggest that, as with many other G protein-coupled receptors, when transfected in heterologous cell systems, the V(1b) receptor forms dimers that signal differentially through the G(q/11) and G(s) proteins depending on the nature of the ligand as well as on its localization within specialized compartments of the plasma membrane. The present study thus illustrates how signal transduction associated with the activation of a G protein-coupled receptor can be versatile and highly dependent on both the cell context and the chemical nature of the extracellular signaling messenger.
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Affiliation(s)
- Hélène Orcel
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Institut de Génomique Fonctionnelle, Montpellier, France
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