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Mancini AD, Bertrand G, Vivot K, Carpentier É, Tremblay C, Ghislain J, Bouvier M, Poitout V. β-Arrestin Recruitment and Biased Agonism at Free Fatty Acid Receptor 1. J Biol Chem 2015; 290:21131-21140. [PMID: 26157145 DOI: 10.1074/jbc.m115.644450] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Indexed: 11/06/2022] Open
Abstract
FFAR1/GPR40 is a seven-transmembrane domain receptor (7TMR) expressed in pancreatic β cells and activated by FFAs. Pharmacological activation of GPR40 is a strategy under consideration to increase insulin secretion in type 2 diabetes. GPR40 is known to signal predominantly via the heterotrimeric G proteins Gq/11. However, 7TMRs can also activate functionally distinct G protein-independent signaling via β-arrestins. Further, G protein- and β-arrestin-based signaling can be differentially modulated by different ligands, thus eliciting ligand-specific responses ("biased agonism"). Whether GPR40 engages β-arrestin-dependent mechanisms and is subject to biased agonism is unknown. Using bioluminescence resonance energy transfer-based biosensors for real-time monitoring of cell signaling in living cells, we detected a ligand-induced GPR40-β-arrestin interaction, with the synthetic GPR40 agonist TAK-875 being more effective than palmitate or oleate in recruiting β-arrestins 1 and 2. Conversely, TAK-875 acted as a partial agonist of Gq/11-dependent GPR40 signaling relative to both FFAs. Pharmacological blockade of Gq activity decreased FFA-induced insulin secretion. In contrast, knockdown or genetic ablation of β-arrestin 2 in an insulin-secreting cell line and mouse pancreatic islets, respectively, uniquely attenuated the insulinotropic activity of TAK-875, thus providing functional validation of the biosensor data. Collectively, these data reveal that in addition to coupling to Gq/11, GPR40 is functionally linked to a β-arrestin 2-mediated insulinotropic signaling axis. These observations expose previously unrecognized complexity for GPR40 signal transduction and may guide the development of biased agonists showing improved clinical profile in type 2 diabetes.
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Affiliation(s)
- Arturo D Mancini
- Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada
| | - Gyslaine Bertrand
- Institut de Génomique Fonctionnelle, CNRS UMR 5203, INSERM U661, Universités de Montpellier 1 & 2, 34060 Montpellier, France
| | - Kevin Vivot
- Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada
| | - Éric Carpentier
- Department of Biochemistry and Molecular Medicine, University of Montreal, Quebec H3C 3J7, Canada
| | - Caroline Tremblay
- Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada
| | - Julien Ghislain
- Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada
| | - Michel Bouvier
- Department of Biochemistry and Molecular Medicine, University of Montreal, Quebec H3C 3J7, Canada
| | - Vincent Poitout
- Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada; Department of Biochemistry and Molecular Medicine, University of Montreal, Quebec H3C 3J7, Canada.
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252
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Aznar N, Midde KK, Dunkel Y, Lopez-Sanchez I, Pavlova Y, Marivin A, Barbazán J, Murray F, Nitsche U, Janssen KP, Willert K, Goel A, Abal M, Garcia-Marcos M, Ghosh P. Daple is a novel non-receptor GEF required for trimeric G protein activation in Wnt signaling. eLife 2015; 4:e07091. [PMID: 26126266 PMCID: PMC4484057 DOI: 10.7554/elife.07091] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 06/01/2015] [Indexed: 12/17/2022] Open
Abstract
Wnt signaling is essential for tissue homeostasis and its dysregulation causes cancer. Wnt ligands trigger signaling by activating Frizzled receptors (FZDRs), which belong to the G-protein coupled receptor superfamily. However, the mechanisms of G protein activation in Wnt signaling remain controversial. In this study, we demonstrate that FZDRs activate G proteins and trigger non-canonical Wnt signaling via the Dishevelled-binding protein, Daple. Daple contains a Gα-binding and activating (GBA) motif, which activates Gαi proteins and an adjacent domain that directly binds FZDRs, thereby linking Wnt stimulation to G protein activation. This triggers non-canonical Wnt responses, that is, suppresses the β-catenin/TCF/LEF pathway and tumorigenesis, but enhances PI3K-Akt and Rac1 signals and tumor cell invasiveness. In colorectal cancers, Daple is suppressed during adenoma-to-carcinoma transformation and expressed later in metastasized tumor cells. Thus, Daple activates Gαi and enhances non-canonical Wnt signaling by FZDRs, and its dysregulation can impact both tumor initiation and progression to metastasis.
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Affiliation(s)
- Nicolas Aznar
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Krishna K Midde
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Ying Dunkel
- Department of Medicine, University of California, San Diego, San Diego, United States
| | | | - Yelena Pavlova
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Jorge Barbazán
- Translational Medical Oncology Laboratory, Health Research Institute of Santiago, Servizo Galego de Saúde, Santiago de Compostela, Spain
| | - Fiona Murray
- Department of Medicine, University of California, San Diego, San Diego, United States
| | - Ulrich Nitsche
- Department of Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Klaus-Peter Janssen
- Department of Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Karl Willert
- Sanford Consortium for Regenerative Medicine, University of California, San Diego, La Jolla, California, United States
| | - Ajay Goel
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, Texas, United States
| | - Miguel Abal
- Translational Medical Oncology Laboratory, Health Research Institute of Santiago, Servizo Galego de Saúde, Santiago de Compostela, Spain
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Pradipta Ghosh
- Department of Medicine, University of California, San Diego, San Diego, United States
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253
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Wie J, Kim BJ, Myeong J, Ha K, Jeong SJ, Yang D, Kim E, Jeon JH, So I. The Roles of Rasd1 small G proteins and leptin in the activation of TRPC4 transient receptor potential channels. Channels (Austin) 2015; 9:186-95. [PMID: 26083271 PMCID: PMC4594510 DOI: 10.1080/19336950.2015.1058454] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
TRPC4 is important regulators of electrical excitability in gastrointestinal myocytes, pancreatic β-cells and neurons. Much is known regarding the assembly and function of these channels including TRPC1 as a homotetramer or a heteromultimer and the roles that their interacting proteins play in controlling these events. Further, they are one of the best-studied targets of G protein-coupled receptors and growth factors in general and Gαi/o and Gαq protein coupled receptor or epidermal growth factor and leptin in particular. However, our understanding of the roles of small G proteins and leptin on TRPC4 channels is still rudimentary. We discuss potential roles for Rasd1 small G protein and leptin in channel activation in addition to their known role in cellular signaling.
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Affiliation(s)
- Jinhong Wie
- a Department of Physiology ; Seoul National University College of Medicine ; Seoul , Republic of Korea
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254
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Heinick A, Husser X, Himmler K, Kirchhefer U, Nunes F, Schulte JS, Seidl MD, Rolfes C, Dedman JR, Kaetzel MA, Gerke V, Schmitz W, Müller FU. Annexin A4 is a novel direct regulator of adenylyl cyclase type 5. FASEB J 2015; 29:3773-87. [PMID: 26023182 DOI: 10.1096/fj.14-269837] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 05/12/2015] [Indexed: 12/14/2022]
Abstract
Annexin A4 (AnxA4), a Ca(2+)- and phospholipid-binding protein, is up-regulated in the human failing heart. In this study, we examined the impact of AnxA4 on β-adrenoceptor (β-AR)/cAMP-dependent signal transduction. Expression of murine AnxA4 in human embryonic kidney (HEK)293 cells dose-dependently inhibited cAMP levels after direct stimulation of adenylyl cyclases (ACs) with forskolin (FSK), as determined with an exchange protein activated by cAMP-Förster resonance energy transfer (EPAC-FRET) sensor and an ELISA (control vs. +AnxA4: 1956 ± 162 vs. 1304 ± 185 fmol/µg protein; n = 8). Disruption of the anxA4 gene led to a consistent increase in intracellular cAMP levels in isolated adult mouse cardiomyocytes, with heart-directed expression of the EPAC-FRET sensor, stimulated with FSK, and as determined by ELISA, also in mouse cardiomyocytes stimulated with the β-AR agonist isoproterenol (ISO) (anxA4a(+/+) vs. anxA4a(-/-): 5.1 ± 0.3 vs. 6.7 ± 0.6 fmol/µg protein) or FSK (anxA4a(+/+) vs. anxA4a(-/-): 1891 ± 238 vs. 2796 ± 343 fmol/µg protein; n = 9-10). Coimmunoprecipitation experiments in HEK293 cells revealed a direct interaction of murine AnxA4 with human membrane-bound AC type 5 (AC5). As a functional consequence of AnxA4-mediated AC inhibition, AnxA4 inhibited the FSK-induced transcriptional activation mediated by the cAMP response element (CRE) in reporter gene studies (10-fold vs. control; n = 4 transfections) and reduced the FSK-induced phosphorylation of the CRE-binding protein (CREB) measured on Western blots (control vs. +AnxA4: 150 ± 17% vs. 105 ± 10%; n = 6) and by the use of the indicator of CREB activation caused by phosphorylation (ICAP)-FRET sensor, indicating CREB phosphorylation. Inactivation of AnxA4 in anxA4a(-/-) mice was associated with an increased cardiac response to β-AR stimulation. Together, these results suggest that AnxA4 is a novel direct negative regulator of AC5, adding a new facet to the functions of annexins.
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Affiliation(s)
- Alexander Heinick
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Xenia Husser
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Kirsten Himmler
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Uwe Kirchhefer
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Frank Nunes
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Jan S Schulte
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Matthias D Seidl
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Christina Rolfes
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - John R Dedman
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Marcia A Kaetzel
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Volker Gerke
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Wilhelm Schmitz
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
| | - Frank U Müller
- *Institute of Pharmacology and Toxicology, Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center, University of Münster, Münster, Germany; and Department of Genome Science, University of Cincinnati Genome Research Institute, Cincinnati, Ohio, USA
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255
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Knapman A, Santiago M, Connor M. Buprenorphine signalling is compromised at the N40D polymorphism of the human μ opioid receptor in vitro. Br J Pharmacol 2015; 171:4273-88. [PMID: 24846673 DOI: 10.1111/bph.12785] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 05/02/2014] [Accepted: 05/03/2014] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE There is significant variation in individual response to opioid drugs, which may result in inappropriate opioid therapy. Polymorphisms of the μ opioid receptor (MOP receptor) may contribute to individual variation in opioid response by affecting receptor function, and the effect may be ligand-specific. We sought to determine functional differences in MOP receptor signalling at several signalling pathways using a range of structurally distinct opioid ligands in cells expressing wild-type MOP receptors (MOPr-WT) and the commonly occurring MOP receptor variant, N40D. EXPERIMENTAL APPROACH MOPr-WT and MOPr-N40D were stably expressed in CHO cells and in AtT-20 cells. Assays of AC inhibition and ERK1/2 phosphorylation were performed on CHO cells, and assays of K activation were performed on AtT-20 cells. Signalling profiles for each ligand were compared between variants. KEY RESULTS Buprenorphine efficacy was reduced by over 50% at MOPr-N40D for AC inhibition and ERK1/2 phosphorylation. Buprenorphine potency was reduced threefold at MOPr-N40D for K channel activation. Pentazocine efficacy was reduced by 50% for G-protein-gated inwardly rectifying K channel activation at MOPr-N40D. No other differences were observed for any other ligands tested. CONCLUSIONS AND IMPLICATIONS The N40D variant is present in 10-50% of the population. Buprenorphine is a commonly prescribed opioid analgesic, and many individuals do not respond to buprenorphine therapy. This study demonstrates that buprenorphine signalling to several effectors via the N40D variant of MOP receptors is impaired, and this may have important consequences in a clinical setting for individuals carrying the N40D allele.
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Affiliation(s)
- Alisa Knapman
- Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
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256
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Lecat S, Matthes HWD, Pepperkok R, Simpson JC, Galzi JL. A Fluorescent Live Imaging Screening Assay Based on Translocation Criteria Identifies Novel Cytoplasmic Proteins Implicated in G Protein-coupled Receptor Signaling Pathways. Mol Cell Proteomics 2015; 14:1385-99. [PMID: 25759509 PMCID: PMC4424407 DOI: 10.1074/mcp.m114.046698] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/20/2015] [Indexed: 12/13/2022] Open
Abstract
Several cytoplasmic proteins that are involved in G protein-coupled receptor signaling cascades are known to translocate to the plasma membrane upon receptor activation, such as beta-arrestin2. Based on this example and in order to identify new cytoplasmic proteins implicated in the ON-and-OFF cycle of G protein-coupled receptor, a live-imaging screen of fluorescently labeled cytoplasmic proteins was performed using translocation criteria. The screening of 193 fluorescently tagged human proteins identified eight proteins that responded to activation of the tachykinin NK2 receptor by a change in their intracellular localization. Previously we have presented the functional characterization of one of these proteins, REDD1, that translocates to the plasma membrane. Here we report the results of the entire screening. The process of cell activation was recorded on videos at different time points and all the videos can be visualized on a dedicated website. The proteins BAIAP3 and BIN1, partially translocated to the plasma membrane upon activation of NK2 receptors. Proteins ARHGAP12 and PKM2 translocated toward membrane blebs. Three proteins that associate with the cytoskeleton were of particular interest : PLEKHH2 rearranged from individual dots located near the cell-substrate adhesion surface into lines of dots. The speriolin-like protein, SPATC1L, redistributed to cell-cell junctions. The Chloride intracellular Channel protein, CLIC2, translocated from actin-enriched plasma membrane bundles to cell-cell junctions upon activation of NK2 receptors. CLIC2, and one of its close paralogs, CLIC4, were further shown to respond with the same translocation pattern to muscarinic M3 and lysophosphatidic LPA receptors. This screen allowed us to identify potential actors in signaling pathways downstream of G protein-coupled receptors and could be scaled-up for high-content screening.
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Affiliation(s)
- Sandra Lecat
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France;
| | - Hans W D Matthes
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France
| | - Rainer Pepperkok
- §European Molecular Biology Laboratory, Advanced Light Microscopy Facility, Meyerhofstr 1, 69117 Heidelberg, Germany
| | - Jeremy C Simpson
- ¶¶School of Biology and Environmental Science and UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Jean-Luc Galzi
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France
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257
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Terra SR, Cardoso JCR, Félix RC, Martins LAM, Souza DOG, Guma FCR, Canário AVM, Schein V. STC1 interference on calcitonin family of receptors signaling during osteoblastogenesis via adenylate cyclase inhibition. Mol Cell Endocrinol 2015; 403:78-87. [PMID: 25591908 DOI: 10.1016/j.mce.2015.01.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/15/2014] [Accepted: 01/06/2015] [Indexed: 12/24/2022]
Abstract
Stanniocalcin 1 (STC1) and calcitonin gene-related peptide (CGRP) are involved in bone formation/remodeling. Here we investigate the effects of STC1 on functional heterodimer complex CALCRL/RAMP1, expression and activity during osteoblastogenesis. STC1 did not modify CALCRL and ramp1 gene expression during osteoblastogenesis when compared to controls. However, plasma membrane spatial distribution of CALCRL/RAMP1 was modified in 7-day pre-osteoblasts exposed to either CGRP or STC1, and both peptides induced CALCRL and RAMP1 assembly. CGRP, but not STC1 stimulated cAMP accumulation in 7-day osteoblasts and in CALCRL/RAMP1 transfected HEK293 cells. Furthermore, STC1 inhibited forskolin stimulated cAMP accumulation of HEK293 cells, but not in CALCRL/RAMP1 transfected HEK293 cells. However, STC1 inhibited cAMP accumulation in calcitonin receptor (CTR) HEK293 transfected cells stimulated by calcitonin. In conclusion, STC1 signals through inhibitory G-protein modulates CGRP receptor spatial localization during osteoblastogenesis and may function as a regulatory factor interacting with calcitonin peptide members during bone formation.
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Affiliation(s)
- Silvia R Terra
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - João Carlos R Cardoso
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal
| | - Rute C Félix
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal
| | - Leo Anderson M Martins
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - Diogo Onofre G Souza
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - Fatima C R Guma
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil
| | - Adelino Vicente M Canário
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal
| | - Vanessa Schein
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90003-035, Brazil; Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Faro 8005-139, Portugal.
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258
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Insel PA, Wilderman A, Zambon AC, Snead AN, Murray F, Aroonsakool N, McDonald DS, Zhou S, McCann T, Zhang L, Sriram K, Chinn AM, Michkov AV, Lynch RM, Overland AC, Corriden R. G Protein-Coupled Receptor (GPCR) Expression in Native Cells: "Novel" endoGPCRs as Physiologic Regulators and Therapeutic Targets. Mol Pharmacol 2015; 88:181-7. [PMID: 25737495 DOI: 10.1124/mol.115.098129] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/02/2015] [Indexed: 12/24/2022] Open
Abstract
G protein-coupled receptors (GPCRs), the largest family of signaling receptors in the human genome, are also the largest class of targets of approved drugs. Are the optimal GPCRs (in terms of efficacy and safety) currently targeted therapeutically? Especially given the large number (∼ 120) of orphan GPCRs (which lack known physiologic agonists), it is likely that previously unrecognized GPCRs, especially orphan receptors, regulate cell function and can be therapeutic targets. Knowledge is limited regarding the diversity and identity of GPCRs that are activated by endogenous ligands and that native cells express. Here, we review approaches to define GPCR expression in tissues and cells and results from studies using these approaches. We identify problems with the available data and suggest future ways to identify and validate the physiologic and therapeutic roles of previously unrecognized GPCRs. We propose that a particularly useful approach to identify functionally important GPCRs with therapeutic potential will be to focus on receptors that show selective increases in expression in diseased cells from patients and experimental animals.
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Affiliation(s)
- Paul A Insel
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Andrea Wilderman
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Alexander C Zambon
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Aaron N Snead
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Fiona Murray
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Nakon Aroonsakool
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Daniel S McDonald
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Shu Zhou
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Thalia McCann
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Lingzhi Zhang
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Krishna Sriram
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Amy M Chinn
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Alexander V Michkov
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Rebecca M Lynch
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Aaron C Overland
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
| | - Ross Corriden
- Departments of Pharmacology (P.A.I., A.W., A.C.Z., A.N.S., N.A., D.S.M., S.Z., T.M., L.Z., K.S., A.M.C., A.V.M., R.M.L., A.C.O., R.C.) and Medicine (P.A.I., F.M.), University of California, San Diego, La Jolla, California
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Mystek P, Tworzydło M, Dziedzicka-Wasylewska M, Polit A. New insights into the model of dopamine D1 receptor and G-proteins interactions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:594-603. [DOI: 10.1016/j.bbamcr.2014.12.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/03/2014] [Accepted: 12/10/2014] [Indexed: 01/11/2023]
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Smith TH, Blume LC, Straiker A, Cox JO, David BG, McVoy JRS, Sayers KW, Poklis JL, Abdullah RA, Egertová M, Chen CK, Mackie K, Elphick MR, Howlett AC, Selley DE. Cannabinoid receptor-interacting protein 1a modulates CB1 receptor signaling and regulation. Mol Pharmacol 2015; 87:747-65. [PMID: 25657338 DOI: 10.1124/mol.114.096495] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cannabinoid CB1 receptors (CB1Rs) mediate the presynaptic effects of endocannabinoids in the central nervous system (CNS) and most behavioral effects of exogenous cannabinoids. Cannabinoid receptor-interacting protein 1a (CRIP1a) binds to the CB1R C-terminus and can attenuate constitutive CB1R-mediated inhibition of Ca(2+) channel activity. We now demonstrate cellular colocalization of CRIP1a at neuronal elements in the CNS and show that CRIP1a inhibits both constitutive and agonist-stimulated CB1R-mediated guanine nucleotide-binding regulatory protein (G-protein) activity. Stable overexpression of CRIP1a in human embryonic kidney (HEK)-293 cells stably expressing CB1Rs (CB1-HEK), or in N18TG2 cells endogenously expressing CB1Rs, decreased CB1R-mediated G-protein activation (measured by agonist-stimulated [(35)S]GTPγS (guanylyl-5'-[O-thio]-triphosphate) binding) in both cell lines and attenuated inverse agonism by rimonabant in CB1-HEK cells. Conversely, small-interfering RNA-mediated knockdown of CRIP1a in N18TG2 cells enhanced CB1R-mediated G-protein activation. These effects were not attributable to differences in CB1R expression or endocannabinoid tone because CB1R levels did not differ between cell lines varying in CRIP1a expression, and endocannabinoid levels were undetectable (CB1-HEK) or unchanged (N18TG2) by CRIP1a overexpression. In CB1-HEK cells, 4-hour pretreatment with cannabinoid agonists downregulated CB1Rs and desensitized agonist-stimulated [(35)S]GTPγS binding. CRIP1a overexpression attenuated CB1R downregulation without altering CB1R desensitization. Finally, in cultured autaptic hippocampal neurons, CRIP1a overexpression attenuated both depolarization-induced suppression of excitation and inhibition of excitatory synaptic activity induced by exogenous application of cannabinoid but not by adenosine A1 agonists. These results confirm that CRIP1a inhibits constitutive CB1R activity and demonstrate that CRIP1a can also inhibit agonist-stimulated CB1R signaling and downregulation of CB1Rs. Thus, CRIP1a appears to act as a broad negative regulator of CB1R function.
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Affiliation(s)
- Tricia H Smith
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Lawrence C Blume
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Alex Straiker
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Jordan O Cox
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Bethany G David
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Julie R Secor McVoy
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Katherine W Sayers
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Justin L Poklis
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Rehab A Abdullah
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Michaela Egertová
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Ching-Kang Chen
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Ken Mackie
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Maurice R Elphick
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Allyn C Howlett
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
| | - Dana E Selley
- Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies (T.H.S., J.O.C., B.G.D., J.R.S.M., J.L.P., R.A.A., D.E.S.), Department of Anatomy and Neurobiology (K.W.S.), Department of Biochemistry and Molecular Biology (C.-K.C.), Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina (L.C.B., A.C.H.); The Gill Center for Biomolecular Science and the Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana (A.S., K.M.); and School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom (M.E., M.R.E.)
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PKA reduces the rat and human KCa3.1 current, CaM binding, and Ca2+ signaling, which requires Ser332/334 in the CaM-binding C terminus. J Neurosci 2015; 34:13371-83. [PMID: 25274816 DOI: 10.1523/jneurosci.1008-14.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The Ca(2+)-dependent K(+) channel, KCa3.1 (KCNN4/IK/SK4), is widely expressed and contributes to cell functions that include volume regulation, migration, membrane potential, and excitability. KCa3.1 is now considered a therapeutic target for several diseases, including CNS disorders involving microglial activation; thus, we need to understand how KCa3.1 function is regulated. KCa3.1 gating and trafficking require calmodulin binding to the two ends of the CaM-binding domain (CaMBD), which also contains three conserved sites for Ser/Thr kinases. Although cAMP protein kinase (PKA) signaling is important in many cells that use KCa3.1, reports of channel regulation by PKA are inconsistent. We first compared regulation by PKA of native rat KCa3.1 channels in microglia (and the microglia cell line, MLS-9) with human KCa3.1 expressed in HEK293 cells. In all three cells, PKA activation with Sp-8-Br-cAMPS decreased the current, and this was prevented by the PKA inhibitor, PKI14-22. Inhibiting PKA with Rp-8-Br-cAMPS increased the current in microglia. Mutating the single PKA site (S334A) in human KCa3.1 abolished the PKA-dependent regulation. CaM-affinity chromatography showed that CaM binding to KCa3.1 was decreased by PKA-dependent phosphorylation of S334, and this regulation was absent in the S334A mutant. Single-channel analysis showed that PKA decreased the open probability in wild-type but not S334A mutant channels. The same decrease in current for native and wild-type expressed KCa3.1 channels (but not S334A) occurred when PKA was activated through the adenosine A2a receptor. Finally, by decreasing the KCa3.1 current, PKA activation reduced Ca(2+)-release-activated Ca(2+) entry following activation of metabotropic purinergic receptors in microglia.
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262
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Wie J, Kim J, Ha K, Zhang YH, Jeon JH, So I. Dexamethasone activates transient receptor potential canonical 4 (TRPC4) channels via Rasd1 small GTPase pathway. Pflugers Arch 2014; 467:2081-91. [PMID: 25502319 DOI: 10.1007/s00424-014-1666-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 11/24/2014] [Accepted: 12/01/2014] [Indexed: 12/15/2022]
Abstract
Canonical transient receptor potential 4 (TRPC4) channels are calcium-permeable, nonselective cation channels that are widely distributed in mammalian cells. It is generally speculated that TRPC4 channels are activated by Gq/11-PLC pathway or directly activated by Gi/o proteins. Although many mechanistic studies regarding TRPC4 have dealt with heterotrimeric G proteins, here, we first report the functional relationship between TRPC4 and small GTPase, Rasd1. Rasd1 selectively activated TRPC4 channels, and it was the only Ras protein among Ras protein family that can activate TRPC4 channels. For this to occur, it was found that certain population of functional Gαi1 and Gαi3 proteins are essential. Meanwhile, dexamethasone, a synthetic glucocorticoid and anti-inflammatory drug was known to increase messenger RNA (mRNA) level of Rasd1 in pancreatic β-cells. We have found that dexamethasone triggers TRPC4-like cationic current in INS-1 cells via increasing protein expression level of Rasd1. This relationship among dexamethasone, Rasd1, and TRPC4 could suggest a new therapeutic agent for hospitalized diabetes mellitus (DM) patients with prolonged dexamethasone prescription.
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Affiliation(s)
- Jinhong Wie
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Jinsung Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea.,Catholic University of Korea, College of Medicine, Seoul, 137-701, Republic of Korea
| | - Kotdaji Ha
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Yin Hua Zhang
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Ju-Hong Jeon
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea
| | - Insuk So
- Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Republic of Korea.
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263
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Deshotels MR, Xia H, Sriramula S, Lazartigues E, Filipeanu CM. Angiotensin II mediates angiotensin converting enzyme type 2 internalization and degradation through an angiotensin II type I receptor-dependent mechanism. Hypertension 2014; 64:1368-1375. [PMID: 25225202 PMCID: PMC4231883 DOI: 10.1161/hypertensionaha.114.03743] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 08/24/2014] [Indexed: 02/07/2023]
Abstract
Angiotensin-converting enzyme type 2 (ACE2) is a pivotal component of the renin-angiotensin system, promoting the conversion of angiotensin II (Ang-II) to Ang-(1-7). We previously reported that decreased ACE2 expression and activity contributes to the development of Ang-II-mediated hypertension in mice. The present study aimed to investigate the mechanisms involved in ACE2 downregulation during neurogenic hypertension. In ACE2-transfected Neuro-2A cells, Ang-II treatment resulted in a significant attenuation of ACE2 enzymatic activity. Examination of the subcellular localization of ACE2 revealed that Ang-II treatment leads to ACE2 internalization and degradation into lysosomes. These effects were prevented by both the Ang-II type 1 receptor (AT1R) blocker losartan and the lysosomal inhibitor leupeptin. In contrast, in HEK293T cells, which lack endogenous AT1R, Ang-II failed to promote ACE2 internalization. Moreover, this effect could be induced after AT1R transfection. Furthermore, coimmunoprecipitation experiments demonstrated that AT1R and ACE2 form complexes, and these interactions were decreased by Ang-II treatment, which also enhanced ACE2 ubiquitination. In contrast, ACE2 activity was not changed by transfection of AT2 or Mas receptors. In vivo, Ang-II-mediated hypertension was blunted by chronic infusion of leupeptin in wildtype C57Bl/6, but not in ACE2 knockout mice. Overall, this is the first demonstration that elevated Ang-II levels reduce ACE2 expression and activity by stimulation of lysosomal degradation through an AT1R-dependent mechanism.
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Affiliation(s)
- Matthew R. Deshotels
- Department of Pharmacology & Experimental Therapeutics and Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Huijing Xia
- Department of Pharmacology & Experimental Therapeutics and Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Srinivas Sriramula
- Department of Pharmacology & Experimental Therapeutics and Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Eric Lazartigues
- Department of Pharmacology & Experimental Therapeutics and Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Catalin M. Filipeanu
- Department of Pharmacology & Experimental Therapeutics and Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, USA
- Department of Pharmacology, College of Medicine, Howard University Washington, DC, USA
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Chruścicka B, Burnat G, Brański P, Chorobik P, Lenda T, Marciniak M, Pilc A. Tetracycline-based system for controlled inducible expression of group III metabotropic glutamate receptors. ACTA ACUST UNITED AC 2014; 20:350-8. [PMID: 25394730 DOI: 10.1177/1087057114559183] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A stable and inducible expression of metabotropic glutamate receptor type 4, 7, and 8 was obtained in T-REx 293 cells using the tetracycline system. Tetracycline administration to the cell medium resulted in rapid induction and time-dependent expression of mGlu receptors, which also correlates with its functionality in a cAMP accumulation assay. The pharmacological properties of recombinant mGlu receptors were verified using orthosteric and allosteric ligands. Data suggest that the Tet-on inducible system is suitable for functional mGlu receptors' expression and characterization by means of the cAMP accumulation assay. It makes this system a precise, reproducible, and large-scale screening method, as well as a reasonable tool to study signaling properties of mGlu receptors.
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Affiliation(s)
- Barbara Chruścicka
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Smętna, Poland
| | - Grzegorz Burnat
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Smętna, Poland
| | - Piotr Brański
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Smętna, Poland
| | - Paulina Chorobik
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Smętna, Poland
| | - Tomasz Lenda
- Department of Neuropsychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Smętna, Poland
| | - Marcin Marciniak
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Smętna, Poland
| | - Andrzej Pilc
- Department of Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, Kraków, Smętna, Poland Faculty of Health Sciences, Medical College, Jagiellonian University, Kraków, Grzegórzecka, Poland
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265
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Illing S, Mann A, Schulz S. Heterologous regulation of agonist-independent μ-opioid receptor phosphorylation by protein kinase C. Br J Pharmacol 2014; 171:1330-40. [PMID: 24308893 DOI: 10.1111/bph.12546] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 11/12/2013] [Accepted: 12/02/2013] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE Homologous agonist-induced phosphorylation of the μ-opioid receptor (MOR) is initiated at the carboxyl-terminal S375, followed by phosphorylation of T370, T376 and T379. In HEK293 cells, this sequential and hierarchical multi-site phosphorylation is specifically mediated by G-protein coupled receptor kinases 2 and 3. In the present study, we provide evidence for a selective and dose-dependent phosphorylation of T370 after activation of PKC by phorbol esters. EXPERIMENTAL APPROACH We used a combination of phospho site-specific antibodies, kinase inhibitors and siRNA knockdown screening to identify kinases that mediate agonist-independent phosphorylation of the MOR in HEK293 cells. In addition, we show with phospho site-specific antibodies were also used to study constitutive phosphorylation at S363 of MORs in mouse brain in vivo. KEY RESULTS Activation of PKC by phorbol esters or heterologous activation of substance P receptors co-expressed with MORs in the same cell induced a selective and dose-dependent phosphorylation of T370 that specifically requires the PKCα isoform. Inhibition of PKC activity did not compromise homologous agonist-driven T370 phosphorylation. In addition, S363 was constitutively phosphorylated in both HEK293 cells and mouse brain in vivo. Constitutive S363 phosphorylation required ongoing PKC activity. When basal PKC activity was decreased, S363 was also a substrate for homologous agonist-stimulated phosphorylation. CONCLUSIONS AND IMPLICATIONS Our results have disclosed novel mechanisms of heterologous regulation of MOR phosphorylation by PKC. These findings represent a useful starting point for definitive experiments elucidating the exact contribution of PKC-driven MOR phosphorylation to diminished MOR responsiveness in morphine tolerance and pathological pain.
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Affiliation(s)
- Susann Illing
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
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Gaskill PJ, Yano HH, Kalpana GV, Javitch JA, Berman JW. Dopamine receptor activation increases HIV entry into primary human macrophages. PLoS One 2014; 9:e108232. [PMID: 25268786 PMCID: PMC4182469 DOI: 10.1371/journal.pone.0108232] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/25/2014] [Indexed: 01/11/2023] Open
Abstract
Macrophages are the primary cell type infected with HIV in the central nervous system, and infection of these cells is a major component in the development of neuropathogenesis and HIV-associated neurocognitive disorders. Within the brains of drug abusers, macrophages are exposed to increased levels of dopamine, a neurotransmitter that mediates the addictive and reinforcing effects of drugs of abuse such as cocaine and methamphetamine. In this study we examined the effects of dopamine on HIV entry into primary human macrophages. Exposure to dopamine during infection increased the entry of R5 tropic HIV into macrophages, irrespective of the concentration of the viral inoculum. The entry pathway affected was CCR5 dependent, as antagonizing CCR5 with the small molecule inhibitor TAK779 completely blocked entry. The effect was dose-dependent and had a steep threshold, only occurring above 108 M dopamine. The dopamine-mediated increase in entry required dopamine receptor activation, as it was abrogated by the pan-dopamine receptor antagonist flupenthixol, and could be mediated through both subtypes of dopamine receptors. These findings indicate that the effects of dopamine on macrophages may have a significant impact on HIV pathogenesis. They also suggest that drug-induced increases in CNS dopamine may be a common mechanism by which drugs of abuse with distinct modes of action exacerbate neuroinflammation and contribute to HIV-associated neurocognitive disorders in infected drug abusers.
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Affiliation(s)
- Peter J. Gaskill
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
| | - Hideaki H. Yano
- Department of Psychiatry and Pharmacology, Columbia University, New York, New York, United States of America
| | - Ganjam V. Kalpana
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Jonathan A. Javitch
- Department of Psychiatry and Pharmacology, Columbia University, New York, New York, United States of America
| | - Joan W. Berman
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
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267
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Selectivity of peptide ligands for the human incretin receptors expressed in HEK-293 cells. Eur J Pharmacol 2014; 741:311-5. [PMID: 25179575 DOI: 10.1016/j.ejphar.2014.08.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 12/20/2022]
Abstract
The increase in insulin response to oral glucose compared with glucose given by intravenous injection is termed the incretin effect and is mediated by two peptide hormones secreted from the gut in response to nutrient intake: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). GLP-1 and GIP exert their insulinotropic effects through their respective receptors expressed on pancreatic β-cells. Both the GLP-1 receptor and the GIP receptor are members of the secretin family of G protein-coupled receptors and couple positively with adenylate cyclase, resulting in an increase in intracellular cAMP. In the present study, we investigated the activity of six previously reported peptide ligands at both the GLP-1 and GIP receptors expressed on HEK-293 cells using a highly sensitive reporter gene assay. GLP-1 and GIP demonstrated almost 100,000-fold selectivity for their respective receptors. Exendin 4 (Ex-4), a long-acting GLP-1 receptor agonist, displayed considerable activity at the GIP receptor. Exendin 9-39 (Ex 9-39) was able to block activity at both the GLP-1 and GIP receptors, and Pro3GIP, a previously-reported GIP receptor antagonist, was shown to act as a partial agonist at the GIP receptor. These data highlight the need for more selective antagonists to study these therapeutically important receptors.
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268
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Octeau JC, Schrader JM, Masuho I, Sharma M, Aiudi C, Chen CK, Kovoor A, Celver J. G protein beta 5 is targeted to D2-dopamine receptor-containing biochemical compartments and blocks dopamine-dependent receptor internalization. PLoS One 2014; 9:e105791. [PMID: 25162404 PMCID: PMC4146516 DOI: 10.1371/journal.pone.0105791] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/23/2014] [Indexed: 11/18/2022] Open
Abstract
G beta 5 (Gbeta5, Gβ5) is a unique G protein β subunit that is thought to be expressed as an obligate heterodimer with R7 regulator of G protein signaling (RGS) proteins instead of with G gamma (Gγ) subunits. We found that D2-dopamine receptor (D2R) coexpression enhances the expression of Gβ5, but not that of the G beta 1 (Gβ1) subunit, in HEK293 cells, and that the enhancement of expression occurs through a stabilization of Gβ5 protein. We had previously demonstrated that the vast majority of D2R either expressed endogenously in the brain or exogenously in cell lines segregates into detergent-resistant biochemical fractions. We report that when expressed alone in HEK293 cells, Gβ5 is highly soluble, but is retargeted to the detergent-resistant fraction after D2R coexpression. Furthermore, an in-cell biotin transfer proximity assay indicated that D2R and Gβ5 segregating into the detergent-resistant fraction specifically interacted in intact living cell membranes. Dopamine-induced D2R internalization was blocked by coexpression of Gβ5, but not Gβ1. However, the same Gβ5 coexpression levels had no effect on agonist-induced internalization of the mu opioid receptor (MOR), cell surface D2R levels, dopamine-mediated recruitment of β-arrestin to D2R, the amplitude of D2R-G protein coupling, or the deactivation kinetics of D2R-activated G protein signals. The latter data suggest that the interactions between D2R and Gβ5 are not mediated by endogenously expressed R7 RGS proteins.
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Affiliation(s)
- J. Christopher Octeau
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Joseph M. Schrader
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Meenakshi Sharma
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Christopher Aiudi
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Ching-Kang Chen
- Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Abraham Kovoor
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
- * E-mail: (AK); (JC)
| | - Jeremy Celver
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
- * E-mail: (AK); (JC)
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269
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Ligand-specific endocytic dwell times control functional selectivity of the cannabinoid receptor 1. Nat Commun 2014; 5:4589. [PMID: 25081814 PMCID: PMC4227836 DOI: 10.1038/ncomms5589] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 07/03/2014] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are the major transducers of external stimuli and
key therapeutic targets in many pathological conditions. When activated by different
ligands, one receptor can elicit multiple signalling cascades that are mediated by G
proteins or β-arrestin, a process defined as functional selectivity or
ligand bias. However, the dynamic mechanisms underlying β-arrestin
signalling remain unknown. Here by studying the cannabinoid receptor 1 (CB1R), we identify ligand-specific endocytic dwell times, that
is, the time during which receptors are clustered into clathrin pits together with
β-arrestins before endocytosis, as the mechanism controlling
β-arrestin signalling. Agonists inducing short endocytic dwell times
produce little or no β-arrestin signalling, whereas those eliciting
prolonged dwell times induce robust signalling. Remarkably, extending CB1R dwell times by preventing endocytosis
substantially increased β-arrestin signalling. These studies reveal how
receptor activation translates into β-arrestin signalling and identify a
mechanism to control this pathway. G-protein coupled receptors can signal through G-proteins or through
β-arrestin, however mechanisms determining pathway selection remain unclear.
Here the authors show that the duration of cannabinoid receptor clustering in clathrin
coated pits prior to endocytosis determines the strength of β-arrestin
signalling.
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270
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Tirupula KC, Desnoyer R, Speth RC, Karnik SS. Atypical signaling and functional desensitization response of MAS receptor to peptide ligands. PLoS One 2014; 9:e103520. [PMID: 25068582 PMCID: PMC4113456 DOI: 10.1371/journal.pone.0103520] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 07/01/2014] [Indexed: 11/19/2022] Open
Abstract
MAS is a G protein-coupled receptor (GPCR) implicated in multiple physiological processes. Several physiological peptide ligands such as angiotensin-(1-7), angiotensin fragments and neuropeptide FF (NPFF) are reported to act on MAS. Studies of conventional G protein signaling and receptor desensitization upon stimulation of MAS with the peptide ligands are limited so far. Therefore, we systematically analyzed G protein signals activated by the peptide ligands. MAS-selective non-peptide ligands that were previously shown to activate G proteins were used as controls for comparison on a common cell based assay platform. Activation of MAS by the non-peptide agonist (1) increased intracellular calcium and D-myo-inositol-1-phosphate (IP1) levels which are indicative of the activation of classical Gαq-phospholipase C signaling pathways, (2) decreased Gαi mediated cAMP levels and (3) stimulated Gα12-dependent expression of luciferase reporter. In all these assays, MAS exhibited strong constitutive activity that was inhibited by the non-peptide inverse agonist. Further, in the calcium response assay, MAS was resistant to stimulation by a second dose of the non-peptide agonist after the first activation has waned suggesting functional desensitization. In contrast, activation of MAS by the peptide ligand NPFF initiated a rapid rise in intracellular calcium with very weak IP1 accumulation which is unlike classical Gαq-phospholipase C signaling pathway. NPFF only weakly stimulated MAS-mediated activation of Gα12 and Gαi signaling pathways. Furthermore, unlike non-peptide agonist-activated MAS, NPFF-activated MAS could be readily re-stimulated the second time by the agonists. Functional assays with key ligand binding MAS mutants suggest that NPFF and non-peptide ligands bind to overlapping regions. Angiotensin-(1-7) and other angiotensin fragments weakly potentiated an NPFF-like calcium response at non-physiological concentrations (≥100 µM). Overall, our data suggest that peptide ligands induce atypical signaling and functional desensitization of MAS.
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Affiliation(s)
- Kalyan C. Tirupula
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Russell Desnoyer
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Robert C. Speth
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida, United States of America
| | - Sadashiva S. Karnik
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- * E-mail:
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271
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Knapman A, Connor M. Cellular signalling of non-synonymous single-nucleotide polymorphisms of the human μ-opioid receptor (OPRM1). Br J Pharmacol 2014; 172:349-63. [PMID: 24527749 DOI: 10.1111/bph.12644] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Revised: 01/21/2014] [Accepted: 02/07/2014] [Indexed: 12/15/2022] Open
Abstract
UNLABELLED There is significant variability in individual responses to opioid drugs, which is likely to have a significant genetic component. A number of non-synonymous single-nucleotide polymorphisms (SNPs) in the coding regions of the μ-opioid receptor gene (OPRM1) have been postulated to contribute to this variability. Although many studies have investigated the clinical influences of these μ-opioid receptor variants, the outcomes are reported in the context of thousands of other genes and environmental factors, and we are no closer to being able to predict individual response to opioids based on genotype. Investigation of how μ-opioid receptor SNPs affect their expression, coupling to second messengers, desensitization and regulation is necessary to understand how subtle changes in receptor structure can impact individual responses to opioids. To date, the few functional studies that have investigated the consequences of SNPs on the signalling profile of the μ-opioid receptor in vitro have shown that the common N40D variant has altered functional responses to some opioids, while other, rarer, variants display altered signalling or agonist-dependent regulation. Here, we review the data available on the effects of μ-opioid receptor polymorphisms on receptor function, expression and regulation in vitro, and discuss the limitations of the studies to date. Whether or not μ-opioid receptor SNPs contribute to individual variability in opioid responses remains an open question, in large part because we have relatively little good data about how the amino acid changes affect μ-opioid receptor function. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- Alisa Knapman
- Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
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272
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Mann A, Illing S, Miess E, Schulz S. Different mechanisms of homologous and heterologous μ-opioid receptor phosphorylation. Br J Pharmacol 2014; 172:311-6. [PMID: 24517854 DOI: 10.1111/bph.12627] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/16/2014] [Accepted: 01/19/2014] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED The efficiency of μ-opioid receptor signalling is tightly regulated and ultimately limited by the coordinated phosphorylation of intracellular serine and threonine residues. Here, we review and discuss recent progress in the generation and application of phosphosite-specific μ-opioid receptor antibodies, which have proved to be excellent tools for monitoring the spatial and temporal dynamics of receptor phosphorylation and dephosphorylation. Agonist-induced phosphorylation of μ-opioid receptors occurs at a conserved 10 residue sequence (370) TREHPSTANT(379) in the receptor's carboxyl-terminal cytoplasmic tail. Diverse opioids induce receptor phosphorylation at S375, present in the middle of this sequence, but only high-efficacy opioids have the ability to drive higher order phosphorylation on flanking residues (T370, T376 and T379). S375 is the initiating residue in a hierarchical phosphorylation cascade. In contrast, agonist-independent heterologous μ-opioid receptor phosphorylation occurs primarily at T370. The combination of phosphosite-specific antibodies and siRNA knockdown screening also facilitated the identification of relevant kinases and phosphatases. In fact, morphine induces a selective S375 phosphorylation that is predominantly catalysed by GPCR kinase 5 (GRK5), whereas multisite phosphorylation induced by high-efficacy opioids specifically requires GRK2/3. By contrast, T370 phosphorylation stimulated by phorbol esters or heterologous activation of Gq -coupled receptors is mediated by PKCα. Rapid μ-opioid receptor dephosphorylation occurs at or near the plasma membrane and is catalysed by protein phosphatase 1γ (PP1γ). These findings suggest that there are distinct phosphorylation motifs for homologous and heterologous regulation of μ-opioid receptor phosphorylation. However, it remains to be seen to what extent different μ-opioid receptor phosphorylation patterns contribute to the development of tolerance and dependence in vivo. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- Anika Mann
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany
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273
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Teichmann A, Gibert A, Lampe A, Grzesik P, Rutz C, Furkert J, Schmoranzer J, Krause G, Wiesner B, Schülein R. The specific monomer/dimer equilibrium of the corticotropin-releasing factor receptor type 1 is established in the endoplasmic reticulum. J Biol Chem 2014; 289:24250-62. [PMID: 24966326 DOI: 10.1074/jbc.m114.553644] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
G protein-coupled receptors (GPCRs) represent the most important drug targets. Although the smallest functional unit of a GPCR is a monomer, it became clear in the past decades that the vast majority of the receptors form dimers. Only very recently, however, data were presented that some receptors may in fact be expressed as a mixture of monomers and dimers and that the interaction of the receptor protomers is dynamic. To date, equilibrium measurements were restricted to the plasma membrane due to experimental limitations. We have addressed the question as to where this equilibrium is established for the corticotropin-releasing factor receptor type 1. By developing a novel approach to analyze single molecule fluorescence cross-correlation spectroscopy data for intracellular membrane compartments, we show that the corticotropin-releasing factor receptor type 1 has a specific monomer/dimer equilibrium that is already established in the endoplasmic reticulum (ER). It remains constant at the plasma membrane even following receptor activation. Moreover, we demonstrate for seven additional GPCRs that they are expressed in specific but substantially different monomer/dimer ratios. Although it is well known that proteins may dimerize in the ER in principle, our data show that the ER is also able to establish the specific monomer/dimer ratios of GPCRs, which sheds new light on the functions of this compartment.
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Affiliation(s)
- Anke Teichmann
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Arthur Gibert
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - André Lampe
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Paul Grzesik
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Claudia Rutz
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Jens Furkert
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Jan Schmoranzer
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Gerd Krause
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Burkhard Wiesner
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Ralf Schülein
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
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274
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Masseck OA, Spoida K, Dalkara D, Maejima T, Rubelowski JM, Wallhorn L, Deneris ES, Herlitze S. Vertebrate cone opsins enable sustained and highly sensitive rapid control of Gi/o signaling in anxiety circuitry. Neuron 2014; 81:1263-1273. [PMID: 24656249 DOI: 10.1016/j.neuron.2014.01.041] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2014] [Indexed: 10/25/2022]
Abstract
G protein-coupled receptors (GPCRs) coupling to Gi/o signaling pathways are involved in the control of important physiological functions, which are difficult to investigate because of the limitation of tools to control the signaling pathway with precise kinetics and specificity. We established two vertebrate cone opsins, short- and long-wavelength opsin, for long-lasting and repetitive activation of Gi/o signaling pathways in vitro and in vivo. We demonstrate for both opsins the repetitive fast, membrane-delimited, ultra light-sensitive, and wavelength-dependent activation of the Gi/o pathway in HEK cells. We also show repetitive control of Gi/o pathway activation in 5-HT1A receptor domains in the dorsal raphe nucleus (DRN) in brain slices and in vivo, which is sufficient to modulate anxiety behavior in mice. Thus, vertebrate cone opsins represent a class of tools for understanding the role of Gi/o-coupled GPCRs in health and disease.
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Affiliation(s)
- Olivia A Masseck
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Katharina Spoida
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Deniz Dalkara
- INSERM, U968, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, CNRS, UMR_7210 Institut de la Vision, Paris, F-75012, France
| | - Takashi Maejima
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Johanna M Rubelowski
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Lutz Wallhorn
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Evan S Deneris
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Stefan Herlitze
- Department of General Zoology and Neurobiology, ND7/31, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany.
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275
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Perez-Aso M, Flacco N, Carpena N, Montesinos MC, D'Ocon P, Ivorra MD. β-Adrenoceptors differentially regulate vascular tone and angiogenesis of rat aorta via ERK1/2 and p38. Vascul Pharmacol 2014; 61:80-9. [PMID: 24768830 DOI: 10.1016/j.vph.2014.04.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 01/14/2023]
Abstract
β-Adrenoceptors (β-ARs) modulate ERK1/2 and p38 in different cells, but little is known about the contribution of these signaling pathways to the function of β-ARs in vascular tissue. Immunoblotting analysis of rat aortic rings, primary endothelial (ECs) and smooth muscle cells (SMCs) isolated from aorta showed that β-AR stimulation with isoprenaline activated p38 in aortic rings and in both cultured cell types, whereas it had a dual effect on ERK1/2 phosphorylation, decreasing it in ECs while increasing it in SMCs. These effects were reversed by propranolol, which by itself increased p-ERK1/2 in ECs. Isoprenaline β-AR mediated vasodilation of aortic rings was potentiated by the ERK1/2 inhibitor, U0126, in the presence or absence of endothelium or L-NAME, whereas inhibition of p38 had no impact. Isoprenaline moderately decreased sprouting from aorta rings in the Matrigel angiogenesis assay; conversely propranolol not only prevented isoprenaline inhibition, but stimulated angiogenesis. ERK1/2 inhibition decreased angiogenesis, while a dramatic stimulation was observed by p38 blockade. Our results suggest that ERK1/2 activation after β-ARs stimulation in the smooth muscle hinders the vasodilator effect of isoprenaline, but in the endothelium β-ARs decreases ERK1/2 and increases p38 activity reducing therefore angiogenesis.
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Affiliation(s)
- Miguel Perez-Aso
- Departament de Farmacologia, Facultat de Farmàcia, Universitat de València, 46100 Burjassot, Spain
| | - Nicla Flacco
- Departament de Farmacologia, Facultat de Farmàcia, Universitat de València, 46100 Burjassot, Spain
| | - Nuria Carpena
- Departament de Farmacologia, Facultat de Farmàcia, Universitat de València, 46100 Burjassot, Spain
| | - M Carmen Montesinos
- Departament de Farmacologia, Facultat de Farmàcia, Universitat de València, 46100 Burjassot, Spain; Institut de Reconociment Molecular i Desenvolupament Tecnològic, Centre Mixte Universitat Politècnica de València - Universitat de València, Spain
| | - Pilar D'Ocon
- Departament de Farmacologia, Facultat de Farmàcia, Universitat de València, 46100 Burjassot, Spain
| | - M Dolores Ivorra
- Departament de Farmacologia, Facultat de Farmàcia, Universitat de València, 46100 Burjassot, Spain.
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276
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Singh N, Yadav M, Singh AK, Kumar H, Dwivedi SKD, Mishra JS, Gurjar A, Manhas A, Chandra S, Yadav PN, Jagavelu K, Siddiqi MI, Trivedi AK, Chattopadhyay N, Sanyal S. Synthetic FXR agonist GW4064 is a modulator of multiple G protein-coupled receptors. Mol Endocrinol 2014; 28:659-73. [PMID: 24597548 DOI: 10.1210/me.2013-1353] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The synthetic nuclear bile acid receptor (farnesoid X receptor [FXR]) agonist GW4064 is extensively used as a specific pharmacological tool to illustrate FXR functions. We noticed that GW4064 activated empty luciferase reporters in FXR-deficient HEK-293T cells. We postulated that this activity of GW4064 might be routed through as yet unknown cellular targets and undertook an unbiased exploratory approach to identify these targets. Investigations revealed that GW4064 activated cAMP and nuclear factor for activated T-cell response elements (CRE and NFAT-RE, respectively) present on these empty reporters. Whereas GW4064-induced NFAT-RE activation involved rapid intracellular Ca(2+) accumulation and NFAT nuclear translocation, CRE activation involved soluble adenylyl cyclase-dependent cAMP accumulation and Ca(2+)-calcineurin-dependent nuclear translocation of transducers of regulated CRE-binding protein 2. Use of dominant negative heterotrimeric G-protein minigenes revealed that GW4064 caused activation of Gαi/o and Gq/11 G proteins. Sequential pharmacological inhibitor-based screening and radioligand-binding studies revealed that GW4064 interacted with multiple G protein-coupled receptors. Functional studies demonstrated that GW4064 robustly activated H1 and H4 and inhibited H2 histamine receptor signaling events. We also found that MCF-7 breast cancer cells, reported to undergo GW4064-induced apoptosis in an FXR-dependent manner, did not express FXR, and the GW4064-mediated apoptosis, also apparent in HEK-293T cells, could be blocked by selective histamine receptor regulators. Taken together, our results demonstrate identification of histamine receptors as alternate targets for GW4064, which not only necessitates cautious interpretation of the biological functions attributed to FXR using GW4064 as a pharmacological tool but also provides a basis for the rational designing of new pharmacophores for histamine receptor modulation.
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Affiliation(s)
- Nidhi Singh
- Division of Biochemistry (N.S., M.Y., A.K.S., H.K., J.S.M., A.G., S.S.), Division of Endocrinology and Center for Anabolic Skeletal Targets in Health and Illness (S.K.D.D., N.C.), Division of Pharmacology (A.M., P.N.Y., K.J.), and Division of Molecular and Structural Biology (S.C., M.I.S.), Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
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277
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Dickson EJ, Falkenburger BH, Hille B. Quantitative properties and receptor reserve of the IP(3) and calcium branch of G(q)-coupled receptor signaling. ACTA ACUST UNITED AC 2014; 141:521-35. [PMID: 23630337 PMCID: PMC3639578 DOI: 10.1085/jgp.201210886] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Gq-coupled plasma membrane receptors activate phospholipase C (PLC), which hydrolyzes membrane phosphatidylinositol 4,5-bisphosphate (PIP2) into the second messengers inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). This leads to calcium release, protein kinase C (PKC) activation, and sometimes PIP2 depletion. To understand mechanisms governing these diverging signals and to determine which of these signals is responsible for the inhibition of KCNQ2/3 (KV7.2/7.3) potassium channels, we monitored levels of PIP2, IP3, and calcium in single living cells. DAG and PKC are monitored in our companion paper (Falkenburger et al. 2013. J. Gen. Physiol.http://dx.doi.org/10.1085/jgp.201210887). The results extend our previous kinetic model of Gq-coupled receptor signaling to IP3 and calcium. We find that activation of low-abundance endogenous P2Y2 receptors by a saturating concentration of uridine 5′-triphosphate (UTP; 100 µM) leads to calcium release but not to PIP2 depletion. Activation of overexpressed M1 muscarinic receptors by 10 µM Oxo-M leads to a similar calcium release but also depletes PIP2. KCNQ2/3 channels are inhibited by Oxo-M (by 85%), but not by UTP (<1%). These differences can be attributed purely to differences in receptor abundance. Full amplitude calcium responses can be elicited even after PIP2 was partially depleted by overexpressed inducible phosphatidylinositol 5-phosphatases, suggesting that very low amounts of IP3 suffice to elicit a full calcium release. Hence, weak PLC activation can elicit robust calcium signals without net PIP2 depletion or KCNQ2/3 channel inhibition.
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Affiliation(s)
- Eamonn J Dickson
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
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278
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dela Paz NG, Melchior B, Shayo FY, Frangos JA. Heparan sulfates mediate the interaction between platelet endothelial cell adhesion molecule-1 (PECAM-1) and the Gαq/11 subunits of heterotrimeric G proteins. J Biol Chem 2014; 289:7413-24. [PMID: 24497640 DOI: 10.1074/jbc.m113.542514] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The endothelial cell-cell junction has emerged as a major cell signaling structure that responds to shear stress by eliciting the activation of signaling pathways. Platelet endothelial cell adhesion molecule-1 (PECAM-1) and heterotrimeric G protein subunits Gαq and 11 (Gαq/11) are junctional proteins that have been independently proposed as mechanosensors. Our previous findings suggest that they form a mechanosensitive junctional complex that discriminates between different flow profiles. The nature of the PECAM-1·Gαq/11 interaction is still unclear although it is likely an indirect association. Here, we investigated the role of heparan sulfates (HS) in mediating this interaction and in regulating downstream signaling in response to flow. Co-immunoprecipitation studies show that PECAM-1·Gαq/11 binding is dramatically decreased by competitive inhibition with heparin, pharmacological inhibition with the HS antagonist surfen, and enzymatic removal of HS chains with heparinase III treatment as well as by site-directed mutagenesis of basic residues within the extracellular domain of PECAM-1. Using an in situ proximity ligation assay, we show that endogenous PECAM-1·Gαq/11 interactions in endothelial cells are disrupted by both competitive inhibition and HS degradation. Furthermore, we identified the heparan sulfate proteoglycan syndecan-1 in complexes with PECAM-1 that are rapidly decreased in response to flow. Finally, we demonstrate that flow-induced Akt activation is attenuated in endothelial cells in which PECAM-1 was knocked down and reconstituted with a binding mutant. Taken together, our results indicate that the PECAM-1·Gαq/11 mechanosensitive complex contains an endogenous heparan sulfate proteoglycan with HS chains that is critical for junctional complex assembly and regulating the flow response.
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279
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Ignatious Raja JS, Katanayeva N, Katanaev VL, Galizia CG. Role of Go/i subgroup of G proteins in olfactory signaling of Drosophila melanogaster. Eur J Neurosci 2014; 39:1245-55. [PMID: 24443946 PMCID: PMC4324130 DOI: 10.1111/ejn.12481] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Revised: 12/11/2013] [Accepted: 12/16/2013] [Indexed: 01/01/2023]
Abstract
Intracellular signaling in insect olfactory receptor neurons remains unclear, with both metabotropic and ionotropic components being discussed. Here, we investigated the role of heterotrimeric Go and Gi proteins using a combined behavioral, in vivo and in vitro approach. Specifically, we show that inhibiting Go in sensory neurons by pertussis toxin leads to behavioral deficits. We heterologously expressed the olfactory receptor dOr22a in human embryonic kidney cells (HEK293T). Stimulation with an odor led to calcium influx, which was amplified via calcium release from intracellular stores. Subsequent experiments indicated that the signaling was mediated by the Gβγ subunits of the heterotrimeric Go/i proteins. Finally, using in vivo calcium imaging, we show that Go and Gi contribute to odor responses both for the fast (phasic) as for the slow (tonic) response component. We propose a transduction cascade model involving several parallel processes, in which the metabotropic component is activated by Go and Gi, and uses Gβγ.
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280
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Michel G, Matthes HWD, Hachet-Haas M, El Baghdadi K, de Mey J, Pepperkok R, Simpson JC, Galzi JL, Lecat S. Plasma membrane translocation of REDD1 governed by GPCRs contributes to mTORC1 activation. J Cell Sci 2013; 127:773-87. [PMID: 24338366 DOI: 10.1242/jcs.136432] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The mTORC1 kinase promotes cell growth in response to growth factors by activation of receptor tyrosine kinase. It is regulated by the cellular energy level and the availability of nutrients. mTORC1 activity is also inhibited by cellular stresses through overexpression of REDD1 (regulated in development and DNA damage responses). We report the identification of REDD1 in a fluorescent live-imaging screen aimed at discovering new proteins implicated in G-protein-coupled receptor signaling, based on translocation criteria. Using a sensitive and quantitative plasma membrane localization assay based on bioluminescent resonance energy transfer, we further show that a panel of endogenously expressed GPCRs, through a Ca(2+)/calmodulin pathway, triggers plasma membrane translocation of REDD1 but not of its homolog REDD2. REDD1 and REDD2 share a conserved mTORC1-inhibitory motif characterized at the functional and structural level and differ most in their N-termini. We show that the N-terminus of REDD1 and its mTORC1-inhibitory motif participate in the GPCR-evoked dynamic interaction of REDD1 with the plasma membrane. We further identify REDD1 as a novel effector in GPCR signaling. We show that fast activation of mTORC1 by GPCRs correlates with fast and maximal translocation of REDD1 to the plasma membrane. Overexpression of functional REDD1 leads to a reduction of mTORC1 activation by GPCRs. By contrast, depletion of endogenous REDD1 protein unleashes mTORC1 activity. Thus, translocation to the plasma membrane appears to be an inactivation mechanism of REDD1 by GPCRs, which probably act by sequestering its functional mTORC1-inhibitory motif that is necessary for plasma membrane targeting.
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Affiliation(s)
- Grégory Michel
- GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 67412 Illkirch, France
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281
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Atanes P, Lacivita E, Rodríguez J, Brea J, Burgueño J, Vela JM, Cadavid MI, Loza MI, Leopoldo M, Castro M. The arylpiperazine derivatives N-(4-cyanophenylmethyl)-4-(2-diphenyl)-1-piperazinehexanamide and N-benzyl-4-(2-diphenyl)-1-piperazinehexanamide exert a long-lasting inhibition of human serotonin 5-HT7 receptor binding and cAMP signaling. Pharmacol Res Perspect 2013; 1:e00013. [PMID: 25505568 PMCID: PMC4186431 DOI: 10.1002/prp2.13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 09/15/2013] [Accepted: 09/24/2013] [Indexed: 12/16/2022] Open
Abstract
We performed a detailed in vitro pharmacological characterization of two arylpiperazine derivatives, compound N-(4-cyanophenylmethyl)-4-(2-diphenyl)-1-piperazinehexanamide (LP-211) previously identified as a high-affinity brain penetrant ligand for 5-hydroxytryptamine (serotonin) type 7 (5-HT7) receptors, and its analog N-benzyl-4-(2-diphenyl)-1-piperazinehexanamide (MEL-9). Both ligands exhibited competitive displacement of [3H]-(2R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-methyl-1-piperidinyl)ethyl]pyrrolidine ([3H]-SB-269970) radioligand binding and insurmountable antagonism of 5-carboxamidotryptamine (5-CT)-stimulated cyclic adenosine monophosphate (cAMP) signaling in human embryonic kidney (HEK293) cells stably expressing human 5-HT7 receptors. They also inhibited forskolin-stimulated adenylate cyclase activity in 5-HT7-expressing HEK293 cells but not in the parental cell line. The compounds elicited long-lasting (at least 24 h) concentration-dependent inhibition of radioligand binding at 5-HT7-binding sites in whole-cell radioligand binding assays, after pretreatment of the cells with the compounds and subsequent compound removal. In cAMP assays, pretreatment of cells with the compounds rendered 5-HT7 receptors unresponsive to 5-CT and also rendered 5-HT7-expressing HEK293 cells unresponsive to forskolin. Compound 1-(2-biphenyl)piperazine (RA-7), a known active metabolite of LP-211 present in vivo, was able to partially inhibit 5-HT7 radioligand binding in a long-lasting irreversible manner. Hence, LP-211 and MEL-9 were identified as high-affinity long-acting inhibitors of human 5-HT7 receptor binding and function in cell lines. The detailed in vitro characterization of these two pharmacological tools targeting 5-HT7 receptors may benefit the study of 5-HT7 receptor function and it may lead to the development of novel selective pharmacological tools with defined functional properties at 5-HT7 receptors.
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Affiliation(s)
- Patricio Atanes
- Biofarma Research Group, Department of Pharmacology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela Santiago de Compostela, Spain
| | - Enza Lacivita
- Dipartimento di Farmacia - Scienze del Farmaco, Università degli Studi di Bari "A. Moro" Bari, Italy
| | - Javier Rodríguez
- Biofarma Research Group, Department of Pharmacology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela Santiago de Compostela, Spain
| | - José Brea
- Biofarma Research Group, Department of Pharmacology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela Santiago de Compostela, Spain
| | - Javier Burgueño
- Esteve; Drug Discovery and Preclinical Development Barcelona, Spain
| | - José Miguel Vela
- Esteve; Drug Discovery and Preclinical Development Barcelona, Spain
| | - María Isabel Cadavid
- Biofarma Research Group, Department of Pharmacology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela Santiago de Compostela, Spain
| | - María Isabel Loza
- Biofarma Research Group, Department of Pharmacology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela Santiago de Compostela, Spain
| | - Marcello Leopoldo
- Dipartimento di Farmacia - Scienze del Farmaco, Università degli Studi di Bari "A. Moro" Bari, Italy
| | - Marián Castro
- Biofarma Research Group, Department of Pharmacology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela Santiago de Compostela, Spain
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282
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Ring L, Neth P, Weber C, Steffens S, Faussner A. β-Catenin-dependent pathway activation by both promiscuous "canonical" WNT3a-, and specific "noncanonical" WNT4- and WNT5a-FZD receptor combinations with strong differences in LRP5 and LRP6 dependency. Cell Signal 2013; 26:260-7. [PMID: 24269653 DOI: 10.1016/j.cellsig.2013.11.021] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/04/2013] [Accepted: 11/18/2013] [Indexed: 01/07/2023]
Abstract
The WNT/β-catenin signalling cascade is the best-investigated frizzled receptor (FZD) pathway, however, whether and how specific combinations of WNT/FZD and co-receptors LRP5 and LRP6 differentially affect this pathway are not well understood. This is mostly due to the fact that there are 19 WNTs, 10 FZDs and at least two co-receptors. In our attempt to identify the signalling capabilities of specific WNT/FZD/LRP combinations we made use of our previously reported TCF/LEF Gaussia luciferase reporter gene HEK293 cell line (Ring et al., 2011). Generation of WNT/FZD fusion constructs - but not their separate transfection - without or with additional isogenic overexpression of LRP5 and LRP6 in our reporter cells permitted the investigation of specific WNT/FZD/LRP combinations. The canonical WNT3a in fusion to almost all FZDs was able to induce β-catenin-dependent signalling with strong dependency on LRP6 but not LRP5. Interestingly, noncanonical WNT ligands, WNT4 and WNT5a, were also able to act "canonically" but only in fusion with specific FZDs and with selective dependence on LRP5 or LRP6. These data and extension of this experimental setup to the poorly characterized other WNTs should facilitate deeper insight into the complex WNT/FZD signalling system and its function.
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Affiliation(s)
- Larisa Ring
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-University Munich, Pettenkoferstraße 9, 80336 Munich, Germany.
| | - Peter Neth
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-University Munich, Pettenkoferstraße 9, 80336 Munich, Germany.
| | - Christian Weber
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-University Munich, Pettenkoferstraße 9, 80336 Munich, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, 80336 Munich, Germany.
| | - Sabine Steffens
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-University Munich, Pettenkoferstraße 9, 80336 Munich, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, 80336 Munich, Germany.
| | - Alexander Faussner
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-University Munich, Pettenkoferstraße 9, 80336 Munich, Germany.
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283
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Kirchhefer U, Heinick A, König S, Kristensen T, Müller FU, Seidl MD, Boknik P. Protein phosphatase 2A is regulated by protein kinase Cα (PKCα)-dependent phosphorylation of its targeting subunit B56α at Ser41. J Biol Chem 2013; 289:163-76. [PMID: 24225947 DOI: 10.1074/jbc.m113.507996] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a family of multifunctional serine/threonine phosphatases consisting of a catalytic C, a structural A, and a regulatory B subunit. The substrate and therefore the functional specificity of PP2A are determined by the assembly of the enzyme complex with the appropriate regulatory B subunit families, namely B55, B56, PR72, or PR93/PR110. It has been suggested that additional levels of regulating PP2A function may result from the phosphorylation of B56 isoforms. In this study, we identified a novel phosphorylation site at Ser(41) of B56α. This phosphoamino acid residue was efficiently phosphorylated in vitro by PKCα. We detected a 7-fold higher phosphorylation of B56α in failing human hearts compared with nonfailing hearts. Purified PP2A dimeric holoenzyme (subunits C and A) was able to dephosphorylate PKCα-phosphorylated B56α. The potency of B56α for PP2A inhibition was markedly increased by PKCα phosphorylation. PP2A activity was also reduced in HEK293 cells transfected with a B56α mutant, where serine 41 was replaced by aspartic acid, which mimics phosphorylation. More evidence for a functional role of PKCα-dependent phosphorylation of B56α was derived from Fluo-4 fluorescence measurements in phenylephrine-stimulated Flp293 cells. The endoplasmic reticulum Ca(2+) release was increased by 23% by expression of the pseudophosphorylated form compared with wild-type B56α. Taken together, our results suggest that PKCα can modify PP2A activity by phosphorylation of B56α at Ser(41). This interplay between PKCα and PP2A represents a new mechanism to regulate important cellular functions like cellular Ca(2+) homeostasis.
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Affiliation(s)
- Uwe Kirchhefer
- From the Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, 48149 Münster, Germany
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284
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A prospective overview of the essential requirements in molecular modeling for nanomedicine design. Future Med Chem 2013; 5:929-46. [PMID: 23682569 DOI: 10.4155/fmc.13.67] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Nanotechnology has presented many new challenges and opportunities in the area of nanomedicine design. The issues related to nanoconjugation, nanosystem-mediated targeted drug delivery, transitional stability of nanovehicles, the integrity of drug transport, drug-delivery mechanisms and chemical structural design require a pre-estimated and determined course of assumptive actions with property and characteristic estimations for optimal nanomedicine design. Molecular modeling in nanomedicine encompasses these pre-estimations and predictions of pertinent design data via interactive computographic software. Recently, an increasing amount of research has been reported where specialized software is being developed and employed in an attempt to bridge the gap between drug discovery, materials science and biology. This review provides an assimilative and concise incursion into the current and future strategies of molecular-modeling applications in nanomedicine design and aims to describe the utilization of molecular models and theoretical-chemistry computographic techniques for expansive nanomedicine design and development.
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285
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Hennen S, Wang H, Peters L, Merten N, Simon K, Spinrath A, Blättermann S, Akkari R, Schrage R, Schröder R, Schulz D, Vermeiren C, Zimmermann K, Kehraus S, Drewke C, Pfeifer A, König GM, Mohr K, Gillard M, Müller CE, Lu QR, Gomeza J, Kostenis E. Decoding signaling and function of the orphan G protein-coupled receptor GPR17 with a small-molecule agonist. Sci Signal 2013; 6:ra93. [PMID: 24150254 DOI: 10.1126/scisignal.2004350] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Replacement of the lost myelin sheath is a therapeutic goal for treating demyelinating diseases of the central nervous system (CNS), such as multiple sclerosis (MS). The G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor (GPCR) GPR17, which is phylogenetically closely related to receptors of the "purinergic cluster," has emerged as a modulator of CNS myelination. However, whether GPR17-mediated signaling positively or negatively regulates this critical process is unresolved. We identified a small-molecule agonist, MDL29,951, that selectively activated GPR17 even in a complex environment of endogenous purinergic receptors in primary oligodendrocytes. MDL29,951-stimulated GPR17 engaged the entire set of intracellular adaptor proteins for GPCRs: G proteins of the Gα(i), Gα(s), and Gα(q) subfamily, as well as β-arrestins. This was visualized as alterations in the concentrations of cyclic adenosine monophosphate and inositol phosphate, increased Ca²⁺ flux, phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), as well as multifeatured cell activation recorded with label-free dynamic mass redistribution and impedance biosensors. MDL29,951 inhibited the maturation of primary oligodendrocytes from heterozygous but not GPR17 knockout mice in culture, as well as in cerebellar slices from 4-day-old wild-type mice. Because GPCRs are attractive targets for therapeutic intervention, inhibiting GPR17 emerges as therapeutic strategy to relieve the oligodendrocyte maturation block and promote myelin repair in MS.
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Affiliation(s)
- Stephanie Hennen
- 1Molecular, Cellular, and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, 53115 Bonn, Germany
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286
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Hjortø GM, Kiilerich-Pedersen K, Selmeczi D, Kledal TN, Larsen NB. Human cytomegalovirus chemokine receptor US28 induces migration of cells on a CX3CL1-presenting surface. J Gen Virol 2013; 94:1111-1120. [DOI: 10.1099/vir.0.047290-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Human cytomegalovirus (HCMV)-encoded G protein-coupled-receptor US28 is believed to participate in virus dissemination through modulation of cell migration and immune evasion. US28 binds different CC chemokines and the CX3C chemokine CX3CL1. Membrane-anchored CX3CL1 is expressed by immune-activated endothelial cells, causing redirection of CX3CR1-expressing leukocytes in the blood to sites of infection. Here, we used stable transfected cell lines to examine how US28 expression affects cell migration on immobilized full-length CX3CL1, to model how HCMV-infected leukocytes interact with inflamed endothelium. We observed that US28-expressing cells migrated more than CX3CR1-expressing cells when adhering to immobilized CX3CL1. US28-induced migration was G protein-signalling dependent and was blocked by the phospholipase Cβ inhibitor U73122 and the intracellular calcium chelator BAPTA-AM. In addition, migration was inhibited in a dose-dependent manner by competition from CCL2 and CCL5, whereas CCL3 had little effect. Instead of migrating, CX3CR1-expressing cells performed ‘dancing-on-the-spot’ movements, demonstrating that anchored CX3CL1 acts as a strong tether for these cells. At low receptor expression levels, however, no significant difference in migration potential was observed when comparing the migration of CX3CR1- and US28-expressing cells. Thus, these data showed that, in contrast to CX3CR1, which promotes efficient cell capture upon binding to anchored CX3CL1, US28 acts to increase the migration of cells upon binding to the same ligand. Overall, this indicates that infected cells probably move more than uninfected cells in inflamed tissues with high CX3CL1 expression, with soluble chemokines affecting the final migration.
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Affiliation(s)
- Gertrud M. Hjortø
- Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, DK-2800 Kgs Lyngby, Denmark
| | - Katrine Kiilerich-Pedersen
- Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, DK-2800 Kgs Lyngby, Denmark
| | - David Selmeczi
- Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, DK-2800 Kgs Lyngby, Denmark
| | - Thomas N. Kledal
- Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, DK-2800 Kgs Lyngby, Denmark
| | - Niels B. Larsen
- Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, DK-2800 Kgs Lyngby, Denmark
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287
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Ribas L, Pardo BG, Fernández C, Alvarez-Diós JA, Gómez-Tato A, Quiroga MI, Planas JV, Sitjà-Bobadilla A, Martínez P, Piferrer F. A combined strategy involving Sanger and 454 pyrosequencing increases genomic resources to aid in the management of reproduction, disease control and genetic selection in the turbot (Scophthalmus maximus). BMC Genomics 2013; 14:180. [PMID: 23497389 PMCID: PMC3700835 DOI: 10.1186/1471-2164-14-180] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 02/27/2013] [Indexed: 02/02/2023] Open
Abstract
Background Genomic resources for plant and animal species that are under exploitation primarily for human consumption are increasingly important, among other things, for understanding physiological processes and for establishing adequate genetic selection programs. Current available techniques for high-throughput sequencing have been implemented in a number of species, including fish, to obtain a proper description of the transcriptome. The objective of this study was to generate a comprehensive transcriptomic database in turbot, a highly priced farmed fish species in Europe, with potential expansion to other areas of the world, for which there are unsolved production bottlenecks, to understand better reproductive- and immune-related functions. This information is essential to implement marker assisted selection programs useful for the turbot industry. Results Expressed sequence tags were generated by Sanger sequencing of cDNA libraries from different immune-related tissues after several parasitic challenges. The resulting database (“Turbot 2 database”) was enlarged with sequences generated from a 454 sequencing run of brain-hypophysis-gonadal axis-derived RNA obtained from turbot at different development stages. The assembly of Sanger and 454 sequences generated 52,427 consensus sequences (“Turbot 3 database”), of which 23,661 were successfully annotated. A total of 1,410 sequences were confirmed to be related to reproduction and key genes involved in sex differentiation and maturation were identified for the first time in turbot (AR, AMH, SRY-related genes, CYP19A, ZPGs, STAR FSHR, etc.). Similarly, 2,241 sequences were related to the immune system and several novel key immune genes were identified (BCL, TRAF, NCK, CD28 and TOLLIP, among others). The number of genes of many relevant reproduction- and immune-related pathways present in the database was 50–90% of the total gene count of each pathway. In addition, 1,237 microsatellites and 7,362 single nucleotide polymorphisms (SNPs) were also compiled. Further, 2,976 putative natural antisense transcripts (NATs) including microRNAs were also identified. Conclusions The combined sequencing strategies employed here significantly increased the turbot genomic resources available, including 34,400 novel sequences. The generated database contains a larger number of genes relevant for reproduction- and immune-associated studies, with an excellent coverage of most genes present in many relevant physiological pathways. This database also allowed the identification of many microsatellites and SNP markers that will be very useful for population and genome screening and a valuable aid in marker assisted selection programs.
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Affiliation(s)
- Laia Ribas
- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
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288
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Analysis and regulation of amoeboid-like cell motility using synthetic Ca2+-sensitive proteins. Cell Calcium 2013; 53:231-40. [DOI: 10.1016/j.ceca.2012.12.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 12/18/2012] [Accepted: 12/24/2012] [Indexed: 11/19/2022]
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289
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Leonard AP, Appleton KM, Luttrell LM, Peterson YK. A high-content, live-cell, and real-time approach to the quantitation of ligand-induced β-Arrestin2 and Class A/Class B GPCR mobilization. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2013; 19:150-170. [PMID: 23351552 PMCID: PMC4169994 DOI: 10.1017/s1431927612014067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report the development of a method to analyze receptor and β-arrestin2 mobilization between Class A and B GPCRs via time-resolved fluorescent microscopy coupled with semiautomated high-content multiparametric analysis. Using transiently expressed, tagged β2-adrenergic receptor (β₂-AR) or parathyroid hormone receptor type 1 (PTH₁R), we quantified trafficking of the receptors along with the mobilization and colocalization of coexpressed tagged β-arrestin2. This classification system allows for exclusion of cells with nonoptimal characteristics and calculation of multiple morphological and spatial parameters including receptor endosome formation, β-arrestin mobilization, colocalization, areas, and shape. Stimulated Class A and B receptors demonstrate dramatically different patterns with regard to β-arrestin interactions. The method provides high kinetic resolution measurement of receptor translocation, which allows for the identification of the fleeting β-arrestin interaction found with β₂-AR agonist stimulation, in contrast to stronger mobilization and receptor colocalization with agonist stimulation of the PTH₁R. Though especially appropriate for receptor kinetic studies, this method is generalizable to any dual fluorescence probe system in which quantification of object formation and movement is desired. These methodologies allow for quantitative, unbiased measurement of microscopy data and are further enhanced by providing real-time kinetics.
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Affiliation(s)
- Anthony P. Leonard
- Medical University of South Carolina, Pharmaceutical and Biomedical Sciences, Charleston, SC 29425, USA
| | - Kathryn M. Appleton
- Medical University of South Carolina, Pharmaceutical and Biomedical Sciences, Charleston, SC 29425, USA
| | - Louis M. Luttrell
- Medical University of South Carolina, Medicine, Charleston, SC 29425, USA
| | - Yuri K. Peterson
- Medical University of South Carolina, Pharmaceutical and Biomedical Sciences, Charleston, SC 29425, USA
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290
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Watts AO, Verkaar F, van der Lee MMC, Timmerman CAW, Kuijer M, van Offenbeek J, van Lith LHCJ, Smit MJ, Leurs R, Zaman GJR, Vischer HF. β-Arrestin recruitment and G protein signaling by the atypical human chemokine decoy receptor CCX-CKR. J Biol Chem 2013; 288:7169-81. [PMID: 23341447 DOI: 10.1074/jbc.m112.406108] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Chemokine receptors form a large subfamily of G protein-coupled receptors that predominantly activate heterotrimeric Gi proteins and are involved in immune cell migration. CCX-CKR is an atypical chemokine receptor with high affinity for CCL19, CCL21, and CCL25 chemokines, but is not known to activate intracellular signaling pathways. However, CCX-CKR acts as decoy receptor and efficiently internalizes these chemokines, thereby preventing their interaction with other chemokine receptors, like CCR7 and CCR9. Internalization of fluorescently labeled CCL19 correlated with β-arrestin2-GFP translocation. Moreover, recruitment of β-arrestins to CCX-CKR in response to CCL19, CCL21, and CCL25 was demonstrated using enzyme-fragment complementation and bioluminescence resonance energy transfer methods. To unravel why CCX-CKR is unable to activate Gi signaling, CCX-CKR chimeras were constructed by substituting its intracellular loops with the corresponding CCR7 or CCR9 domains. The signaling properties of chimeric CCX-CKR receptors were characterized using a cAMP-responsive element (CRE)-driven reporter gene assay. Unexpectedly, wild type CCX-CKR and a subset of the chimeras induced an increase in CRE activity in response to CCL19, CCL21, and CCL25 in the presence of the Gi inhibitor pertussis toxin. CCX-CKR signaling to CRE required an intact DRY motif. These data suggest that inactive Gi proteins impair CCX-CKR signaling most likely by hindering the interaction of this receptor with pertussis toxin-insensitive G proteins that transduce signaling to CRE. On the other hand, recruitment of the putative signaling scaffold β-arrestin to CCX-CKR in response to chemokines might allow activation of yet to be identified signal transduction pathways.
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Affiliation(s)
- Anne O Watts
- Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
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291
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Williams JT, Ingram SL, Henderson G, Chavkin C, von Zastrow M, Schulz S, Koch T, Evans CJ, Christie MJ. Regulation of μ-opioid receptors: desensitization, phosphorylation, internalization, and tolerance. Pharmacol Rev 2013; 65:223-54. [PMID: 23321159 DOI: 10.1124/pr.112.005942] [Citation(s) in RCA: 593] [Impact Index Per Article: 53.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Morphine and related µ-opioid receptor (MOR) agonists remain among the most effective drugs known for acute relief of severe pain. A major problem in treating painful conditions is that tolerance limits the long-term utility of opioid agonists. Considerable effort has been expended on developing an understanding of the molecular and cellular processes that underlie acute MOR signaling, short-term receptor regulation, and the progression of events that lead to tolerance for different MOR agonists. Although great progress has been made in the past decade, many points of contention and controversy cloud the realization of this progress. This review attempts to clarify some confusion by clearly defining terms, such as desensitization and tolerance, and addressing optimal pharmacological analyses for discerning relative importance of these cellular mechanisms. Cellular and molecular mechanisms regulating MOR function by phosphorylation relative to receptor desensitization and endocytosis are comprehensively reviewed, with an emphasis on agonist-biased regulation and areas where knowledge is lacking or controversial. The implications of these mechanisms for understanding the substantial contribution of MOR signaling to opioid tolerance are then considered in detail. While some functional MOR regulatory mechanisms contributing to tolerance are clearly understood, there are large gaps in understanding the molecular processes responsible for loss of MOR function after chronic exposure to opioids. Further elucidation of the cellular mechanisms that are regulated by opioids will be necessary for the successful development of MOR-based approaches to new pain therapeutics that limit the development of tolerance.
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Affiliation(s)
- John T Williams
- Vollum Institute, Oregon Health Sciences University, Portland, Oregon, USA
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292
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Shen F, Cheng L, Douglas AE, Riobo NA, Manning DR. Smoothened is a fully competent activator of the heterotrimeric G protein G(i). Mol Pharmacol 2013; 83:691-7. [PMID: 23292797 DOI: 10.1124/mol.112.082511] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Smoothened (Smo) is a 7-transmembrane protein essential to the activation of Gli transcription factors (Gli) by hedgehog morphogens. The structure of Smo implies interactions with heterotrimeric G proteins, but the degree to which G proteins participate in the actions of hedgehogs remains controversial. We posit that the G(i) family of G proteins provides to hedgehogs the ability to expand well beyond the bounds of Gli. In this regard, we evaluate here the efficacy of Smo as it relates to the activation of G(i), by comparing Smo with the 5-hydroxytryptamine(1A) (5-HT(1A)) receptor, a quintessential G(i)-coupled receptor. We find that with use of [(35)S]guanosine 5'-(3-O-thio)triphosphate, first, with forms of G(i) endogenous to human embryonic kidney (HEK)-293 cells made to express epitope-tagged receptors and, second, with individual forms of Gα(i) fused to the C terminus of each receptor, Smo is equivalent to the 5-HT(1A) receptor in the assay as it relates to capacity to activate G(i). This finding is true regardless of subtype of G(i) (e.g., G(i2), G(o), and G(z)) tested. We also find that Smo endogenous to HEK-293 cells, ostensibly through inhibition of adenylyl cyclase, decreases intracellular levels of cAMP. The results indicate that Smo is a receptor that can engage not only Gli but also other more immediate effectors.
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Affiliation(s)
- Feng Shen
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, Pennsylvania 19104-6084, USA
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293
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A Continuous, Fluorescence-based Assay of µ-Opioid Receptor Activation in AtT-20 Cells. ACTA ACUST UNITED AC 2012; 18:269-76. [DOI: 10.1177/1087057112461376] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Opioids are widely prescribed analgesics, but their use is limited due to development of tolerance and addiction, as well as high variability in individual response. The development of improved opioid analgesics requires high-throughput functional assays to assess large numbers of potential opioid ligands. In this study, we assessed the ability of a proprietary “no-wash” fluorescent membrane potential dye to act as a reporter of µ–opioid receptor (MOR) activation and desensitization via activation of G-protein-coupled inwardly rectifying potassium channels. AtT-20 cells stably expressing mouse MOR were assayed in 96-well plates using the Molecular Devices FLIPR membrane potential dye. Dye emission intensity decreased upon membrane hyperpolarization. Fluorescence decreased in a concentration-dependent manner upon application of a range of opioid ligands to the cells, with high-efficacy agonists producing a decrease of 35% to 40% in total fluorescence. The maximum effect of morphine faded in the continued presence of agonist, reflecting receptor desensitization. The effects of opioids were prevented by prior treatment with pertussis toxin and blocked by naloxone. We have demonstrated this assay to be an effective method for assessing ligand signaling at MOR, which may potentially be scaled up as an additional high-throughput screening technique for characterizing novel opioid ligands.
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294
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Straiker A, Wager-Miller J, Mackie K. The CB1 cannabinoid receptor C-terminus regulates receptor desensitization in autaptic hippocampal neurones. Br J Pharmacol 2012; 165:2652-9. [PMID: 22014214 DOI: 10.1111/j.1476-5381.2011.01743.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE The cannabinoid CB(1) receptor is the chief mediator of the CNS effects of cannabinoids. In cell culture model systems, CB(1) receptors both desensitize and internalize on activation. Previous work suggests that the extreme carboxy-terminus of this receptor regulates internalization via phosphorylation of residues clustered within this region. Mutational analysis of the carboxy-terminus of CB(1) receptors has demonstrated that the last six serine/threonine residues are necessary for agonist-induced internalization. However, the structural determinants of CB(1) receptor internalization are also dependent on the local cellular environment. The importance of cell context on CB(1) receptor function calls for an investigation of the functional roles of these residues in neurones. EXPERIMENTAL APPROACH To determine the structural requirements of CB(1) internalization in neurones, we evaluated the signalling properties of carboxy-terminal mutated CB(1) receptors expressed in cultured autaptic hippocampal neurones, using electrophysiological methods. KEY RESULTS CB(1) receptors transfected into CB(1) knockout neurones signalled and desensitized as did wild-type neurones, allowing us to test specific CB(1) receptor mutations. Deletion of the last 13 residues yielded a CB(1) receptor that inhibited excitatory postsynaptic currents but did not desensitize. Furthermore, mutation of the final six serine and threonine residues to alanines resulted in a non-desensitizing receptor. In contrast, CB(1) receptors lacking residues 419-460, leaving the last 14 residues intact, did desensitize. CONCLUSIONS AND IMPLICATIONS The distal thirteen residues of CB(1) receptors are crucial for their desensitization in cultured neurones. Furthermore, this desensitization is likely to follow phosphorylation of serines and threonines within this region. LINKED ARTICLES This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7.
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Affiliation(s)
- Alex Straiker
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana University, Bloomington, IN 47405, USA.
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295
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Koval A, Katanaev VL. Platforms for high-throughput screening of Wnt/Frizzled antagonists. Drug Discov Today 2012; 17:1316-22. [PMID: 22819927 DOI: 10.1016/j.drudis.2012.07.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/04/2012] [Accepted: 07/13/2012] [Indexed: 12/22/2022]
Abstract
Signaling cascades initiated by Wnt lipoglycoproteins and their receptors of the Frizzled family regulate many aspects of animal development and physiology. Improper activation of this signaling promotes carcinogenic transformation and metastasis. Development of agents blocking the Wnt-Frizzled signaling is of prime interest for drug discovery. Despite certain progress no such agents are as yet brought to the market or even to clinical trials. One reason for these delays might be the use of suboptimal readout assays. In this article we overview existing and developing assay platforms to screen for Wnt-Frizzled antagonists. Among those, G protein-activating assays built on the emerging GPCR properties of Frizzleds are highlighted.
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Affiliation(s)
- Alexey Koval
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
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296
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Pinheiro PLC, Cardoso JCR, Power DM, Canário AVM. Functional characterization and evolution of PTH/PTHrP receptors: insights from the chicken. BMC Evol Biol 2012; 12:110. [PMID: 22768871 PMCID: PMC3483286 DOI: 10.1186/1471-2148-12-110] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 06/18/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The parathyroid hormone (PTH)-family consists of a group of structurally related factors that regulate calcium and bone homeostasis and are also involved in development of organs such as the heart, mammary gland and immune system. They interact with specific members of family 2 B1 G-protein coupled receptors (GPCRs), which have been characterised in teleosts and mammals. Two PTH/PTHrP receptors, PTH1R and PTH2R exist in mammals and in teleost fish a further receptor PTH3R has also been identified. Recently in chicken, PTH-family members involved in calcium transport were characterized and specific PTHRs are suggested to exist although they have not yet been isolated or functionally characterized. The aim of this study is to further explore the evolution and function of the vertebrate PTH/PTHrP system through the isolation, phylogenetic analysis and functional characterization of the chicken receptors. RESULTS Two PTHRs were isolated in chicken and sequence comparison and phylogenetic analysis indicate that the chicken receptors correspond to PTH1R and PTH3R, which emerged prior to the teleost/tetrapod divergence since they are present in cartilaginous fish. The vertebrate PTH2R receptor and its ligand TIP39 have been lost from bird genomes. Chicken PTH1R and PTH3R have a divergent and widespread tissue expression and are also evident in very early embryonic stages of development. Receptor stimulation studies using HEK293 cells stably expressing the chicken PTH1R and PTH3R and monitoring cAMP production revealed they are activated by chicken 1-34 N-terminal PTH-family peptides in a dose dependent manner. PTH-L and PTHrP were the most effective peptides in activating PTH1R (EC(50) = 7.7 nM and EC(50) = 22.7 nM, respectively). In contrast, PTH-L (100 nM) produced a small cAMP accumulation on activation of PTH3R but PTHrP and PTH (EC(50) = 2.5 nM and EC(50) = 22.1 nM, respectively) readily activated the receptor. PTHrP also stimulated intracellular Ca(2+) accumulation on activation of PTH1R but not PTH3R. CONCLUSION Two PTHR homologues of the vertebrate PTH1R and PTH3R were isolated and functionally characterized in chicken. Their distinct pattern of expression during embryo development and in adult tissues, together with their ligand preference, suggests that they have acquired specific functions, which have contributed to their maintenance in the genome. PTH2R and its activating ligand, TIP39, are absent from bird genomes. Nonetheless identification of putative PTH2R and TIP39 in the genome of an ancient agnathan, lamprey, suggests the PTH/PTHrP ligand and receptor family was already present in an early basal paraphyletic group of vertebrates and during the vertebrate radiation diverged via gene/genome duplication and deletion events. Knowledge of the role PTH/PTHrP system in early vertebrates will help to establish evolution of function.
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Affiliation(s)
- Pedro L C Pinheiro
- Centre of Marine Sciences, Comparative Molecular Endocrinology, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
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297
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Abstract
Adrenergic receptors and their ligands are important regulators of synaptic plasticity and metaplasticity, but the exact mechanisms underlying their action are still poorly understood. Octopamine, the invertebrate homolog of mammalian adrenaline or noradrenaline, plays important roles in modulating behavior and synaptic functions. We previously uncovered an octopaminergic positive-feedback mechanism to regulate structural synaptic plasticity during development and in response to starvation. Under this mechanism, activation of Octß2R autoreceptors by octopamine at octopaminergic neurons initiated a cAMP-dependent cascade that stimulated the development of new synaptic boutons at the Drosophila larval neuromuscular junction (NMJ). However, the regulatory mechanisms that served to brake such positive feedback were not known. Here, we report the presence of an alternative octopamine autoreceptor, Octß1R, with antagonistic functions on synaptic growth. Mutations in octß1r result in the overgrowth of both glutamatergic and octopaminergic NMJs, suggesting that Octß1R is a negative regulator of synaptic expansion. As Octß2R, Octß1R functioned in a cell-autonomous manner at presynaptic motorneurons. However, unlike Octß2R, which activated a cAMP pathway, Octß1R likely inhibited cAMP production through inhibitory Goα. Despite its inhibitory role, Octß1R was required for acute changes in synaptic structure in response to octopamine and for starvation-induced increase in locomotor speed. These results demonstrate the dual action of octopamine on synaptic growth and behavioral plasticity, and highlight the important role of inhibitory influences for normal responses to physiological stimuli.
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298
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Denis C, Saulière A, Galandrin S, Sénard JM, Galés C. Probing heterotrimeric G protein activation: applications to biased ligands. Curr Pharm Des 2012; 18:128-44. [PMID: 22229559 DOI: 10.2174/138161212799040466] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 11/09/2011] [Indexed: 12/17/2022]
Abstract
Cell surface G protein-coupled receptors (GPCRs) drive numerous signaling pathways involved in the regulation of a broad range of physiologic processes. Today, they represent the largest target for modern drugs development with potential application in all clinical fields. Recently, the concept of "ligand-directed trafficking" has led to a conceptual revolution in pharmacological theory, thus opening new avenues for drug discovery. Accordingly, GPCRs do not function as simple on-off switch but rather as filters capable of selecting the activation of specific signals and thus generating texture responses to ligands, a phenomenon often referred to as ligand-biased signaling. Also, one challenging task today remains optimization of pharmacological assays with increased sensitivity so to better appreciate the inherent texture of ligands. However, considering that a single receptor has pleiotropic signaling properties and that each signal can crosstalk at different levels, biased activity remains thus difficult to evaluate. One strategy to overcome these limitations would be examining the initial steps following receptor activation. Even, if some G protein independent functions have been recently described, heterotrimeric G protein activation remains a general hallmark for all GPCRs families and the first cellular event subsequent to agonist binding to the receptor. Herein, we review the different methodologies classically used or recently developed to monitor G protein activation and discussed them in the context of G protein biased-ligands.
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Affiliation(s)
- Colette Denis
- Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, France.
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299
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Hong C, Kim J, Jeon JP, Wie J, Kwak M, Ha K, Kim H, Myeong J, Kim SY, Jeon JH, So I. Gs cascade regulates canonical transient receptor potential 5 (TRPC5) through cAMP mediated intracellular Ca2+ release and ion channel trafficking. Biochem Biophys Res Commun 2012; 421:105-11. [PMID: 22490661 DOI: 10.1016/j.bbrc.2012.03.123] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 03/27/2012] [Indexed: 11/26/2022]
Abstract
Canonical transient receptor potential (TRPC) channels are Ca(2+)-permeable, non-selective cation channels those are widely expressed in mammalian cells. Various molecules have been found to regulate TRPC both in vivo and in vitro, but it is unclear how heterotrimeric G proteins transmit external stimuli to regulate the activity of TRPC5. Here, we demonstrated that TRPC5 was potentiated by the Gα(s) regulatory pathway. Whole-cell TRPC5 current was significantly increased by β-adrenergic receptor agonist, isoproterenol (ISO, 246±36%, n=6), an activator of the adenylate cyclase, forskolin (FSK, 273±6%, n=5), or a membrane permeable cAMP analogue, 8-Br-cAMP (251±63%, n=7). In addition, robust Ca(2+) transient induced by isoproterenol was observed utilizing a Ca(2+) imaging technique. When intracellular [Ca(2+)](i) was buffered to 50nM, cAMP-induced potentiation was attenuated. We also found that the Ca(2+) release is mediated by IP(3) since intracellular IP(3) infusion attenuated the potentiation of TRPC5 by Gα(s) cascade. Finally, we identified that the membrane localization of TRPC5 was significantly increased by ISO (155±17%, n=3), FSK (172±39%, n=3) or 8-Br-cAMP (216±59%, n=3). In conclusion, these results suggest that the Gα(s)-cAMP pathway potentiates the activity of TRPC5 via facilitating intracellular Ca(2+) dynamics and increasing channel trafficking to the plasma membrane.
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Affiliation(s)
- Chansik Hong
- Department of Physiology and Institute of Dermatological Science, Seoul National University College of Medicine, Seoul, Republic of Korea
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300
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Watts AO, Scholten DJ, Heitman LH, Vischer HF, Leurs R. Label-free impedance responses of endogenous and synthetic chemokine receptor CXCR3 agonists correlate with Gi-protein pathway activation. Biochem Biophys Res Commun 2012; 419:412-8. [DOI: 10.1016/j.bbrc.2012.02.036] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 02/05/2012] [Indexed: 01/13/2023]
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