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Villalobos-Escobedo FS, Jijón-Lorenzo R, Avalos-Fuentes JA, Paz-Bermúdez F, Recillas-Morales S, Rojas IC, Leyva-Gómez G, Cortés H, Florán B. Dopamine D3 receptor modulates D2 receptor effects on cAMP and GABA release at striatopallidal terminals-Modulation by the Ca 2+-Calmodulin-CaMKII system. Eur J Neurosci 2024; 59:1441-1459. [PMID: 38151481 DOI: 10.1111/ejn.16237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 11/15/2023] [Accepted: 11/21/2023] [Indexed: 12/29/2023]
Abstract
Dopamine D2 receptor (D2R) is expressed in striatopallidal neurons and decreases forskolin-stimulated cyclic adenine monophosphate (cAMP) accumulation and gamma-aminobutyric acid (GABA) release. Dopamine D3 receptor (D3R) mRNA is expressed in a population of striatal D2R-expressing neurons. Also, D3R protein and binding have been reported in the neuropil of globus pallidus. We explore whether D2R and D3R colocalize in striatopallidal terminals and whether D3R modulates the D2R effect on forskolin-stimulated [3H]cAMP accumulation in pallidal synaptosomes and high K+ stimulated-[3H]GABA release in pallidal slices. Previous reports in heterologous systems indicate that calmodulin (CaM) and CaMKII modulate D2R and D3R functions; thus, we study whether this system regulates its functional interaction. D2R immunoprecipitates with CaM, and pretreatment with ophiobolin A or depolarization of synaptosomes with 15 mM of K+ decreases it. Both treatments increase the D2R inhibition of forskolin-stimulated [3H]cAMP accumulation when activated with quinpirole, indicating a negative modulation of CaM on D2R function. Quinpirole also activates D3R, potentiating D2R inhibition of cAMP accumulation in the ophiobolin A-treated synaptosomes. D2R and D3R immunoprecipitate in pallidal synaptosomes and decrease after the kainic acid striatal lesion, indicating the striatal origin of the presynaptic receptors. CaM-kinase II alfa (CaMKIIα) immunoprecipitates with D3R and increases after high K+ depolarization. In the presence of KN62, a CaMKIIα blocker, D3R potentiates D2R effects on cAMP accumulation in depolarized synaptosomes and GABA release in pallidal slices, indicating D3R function regulation by CaMKIIα. Our data indicate that D3R potentiates the D2R effect on cAMP accumulation and GABA release at pallidal terminals, an interaction regulated by the CaM-CaMKIIα system.
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Affiliation(s)
- Flor Selene Villalobos-Escobedo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Rafael Jijón-Lorenzo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - José Arturo Avalos-Fuentes
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Francisco Paz-Bermúdez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | | | - Israel Conde Rojas
- Neurobiology of Eating, FES-Iztacala, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Gerardo Leyva-Gómez
- Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Hernán Cortés
- Laboratorio de Medicina Genómica, Departamento de Genómica, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, Mexico City, Mexico
| | - Benjamín Florán
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
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Skopál A, Kéki T, Tóth PÁ, Csóka B, Koscsó B, Németh ZH, Antonioli L, Ivessa A, Ciruela F, Virág L, Haskó G, Kókai E. Cathepsin D interacts with adenosine A 2A receptors in mouse macrophages to modulate cell surface localization and inflammatory signaling. J Biol Chem 2022; 298:101888. [PMID: 35367412 PMCID: PMC9065627 DOI: 10.1016/j.jbc.2022.101888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 03/21/2022] [Accepted: 03/23/2022] [Indexed: 11/30/2022] Open
Abstract
Adenosine A2A receptor (A2AR)–dependent signaling in macrophages plays a key role in the regulation of inflammation. However, the processes regulating A2AR targeting to the cell surface and degradation in macrophages are incompletely understood. For example, the C-terminal domain of the A2AR and proteins interacting with it are known to regulate receptor recycling, although it is unclear what role potential A2AR-interacting partners have in macrophages. Here, we aimed to identify A2AR-interacting partners in macrophages that may effect receptor trafficking and activity. To this end, we performed a yeast two-hybrid screen using the C-terminal tail of A2AR as the “bait” and a macrophage expression library as the “prey.” We found that the lysosomal protease cathepsin D (CtsD) was a robust hit. The A2AR–CtsD interaction was validated in vitro and in cellular models, including RAW 264.7 and mouse peritoneal macrophage (IPMΦ) cells. We also demonstrated that the A2AR is a substrate of CtsD and that the blockade of CtsD activity increases the density and cell surface targeting of A2AR in macrophages. Conversely, we demonstrate that A2AR activation prompts the maturation and enzymatic activity of CtsD in macrophages. In summary, we conclude that CtsD is a novel A2AR-interacting partner and thus describe molecular and functional interplay that may be crucial for adenosine-mediated macrophage regulation in inflammatory processes.
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Affiliation(s)
- Adrienn Skopál
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Kéki
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter Á Tóth
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Csóka
- Department of Anesthesiology, Columbia University, New York, New York, USA
| | - Balázs Koscsó
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Zoltán H Németh
- Department of Anesthesiology, Columbia University, New York, New York, USA; Department of Surgery, Morristown Medical Center, Morristown, New Jersey, USA
| | - Luca Antonioli
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Andreas Ivessa
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain; Neuropharmacology and Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, L'Hospitalet de Llobregat, Barcelona, Spain
| | - László Virág
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; MTA-DE Cell Biology and Signaling Research Group, University of Debrecen, Debrecen, Hungary
| | - György Haskó
- Department of Anesthesiology, Columbia University, New York, New York, USA.
| | - Endre Kókai
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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3
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O’Day DH. Calmodulin Binding Proteins and Alzheimer's Disease: Biomarkers, Regulatory Enzymes and Receptors That Are Regulated by Calmodulin. Int J Mol Sci 2020; 21:ijms21197344. [PMID: 33027906 PMCID: PMC7582761 DOI: 10.3390/ijms21197344] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 12/19/2022] Open
Abstract
The integral role of calmodulin in the amyloid pathway and neurofibrillary tangle formation in Alzheimer’s disease was first established leading to the “Calmodulin Hypothesis”. Continued research has extended our insight into the central function of the small calcium sensor and effector calmodulin and its target proteins in a multitude of other events associated with the onset and progression of this devastating neurodegenerative disease. Calmodulin’s involvement in the contrasting roles of calcium/CaM-dependent kinase II (CaMKII) and calcineurin (CaN) in long term potentiation and depression, respectively, and memory impairment and neurodegeneration are updated. The functions of the proposed neuronal biomarker neurogranin, a calmodulin binding protein also involved in long term potentiation and depression, is detailed. In addition, new discoveries into calmodulin’s role in regulating glutamate receptors (mGluR, NMDAR) are overviewed. The interplay between calmodulin and amyloid beta in the regulation of PMCA and ryanodine receptors are prime examples of how the buildup of classic biomarkers can underly the signs and symptoms of Alzheimer’s. The role of calmodulin in the function of stromal interaction molecule 2 (STIM2) and adenosine A2A receptor, two other proteins linked to neurodegenerative events, is discussed. Prior to concluding, an analysis of how targeting calmodulin and its binding proteins are viable routes for Alzheimer’s therapy is presented. In total, calmodulin and its binding proteins are further revealed to be central to the onset and progression of Alzheimer’s disease.
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Affiliation(s)
- Danton H. O’Day
- Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada;
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
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Blagotinšek Cokan K, Mavri M, Rutland CS, Glišić S, Senćanski M, Vrecl M, Kubale V. Critical Impact of Different Conserved Endoplasmic Retention Motifs and Dopamine Receptor Interacting Proteins (DRIPs) on Intracellular Localization and Trafficking of the D 2 Dopamine Receptor (D 2-R) Isoforms. Biomolecules 2020; 10:biom10101355. [PMID: 32977535 PMCID: PMC7598153 DOI: 10.3390/biom10101355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/09/2020] [Accepted: 09/18/2020] [Indexed: 01/13/2023] Open
Abstract
The type 2 dopamine receptor D2 (D2-R), member of the G protein-coupled receptor (GPCR) superfamily, exists in two isoforms, short (D2S-R) and long (D2L-R). They differ by an additional 29 amino acids (AA) in the third cytoplasmic loop (ICL3) of the D2L-R. These isoforms differ in their intracellular localization and trafficking functionality, as D2L-R possesses a larger intracellular pool, mostly in the endoplasmic reticulum (ER). This review focuses on the evolutionarily conserved motifs in the ICL3 of the D2-R and proteins interacting with the ICL3 of both isoforms, specifically with the 29 AA insert. These motifs might be involved in D2-R exit from the ER and have an impact on cell-surface and intracellular localization and, therefore, also play a role in the function of dopamine receptor signaling, ligand binding and possible homo/heterodimerization. Our recent bioinformatic data on potential new interaction partners for the ICL3 of D2-Rs are also presented. Both are highly relevant, and have clinical impacts on the pathophysiology of several diseases such as Parkinson’s disease, schizophrenia, Tourette’s syndrome, Huntington’s disease, manic depression, and others, as they are connected to a variety of essential motifs and differences in communication with interaction partners.
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Affiliation(s)
- Kaja Blagotinšek Cokan
- Department of Anatomy, Histology with Embryology and Cytology, Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (K.B.C.); (M.M.); (M.V.)
| | - Maša Mavri
- Department of Anatomy, Histology with Embryology and Cytology, Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (K.B.C.); (M.M.); (M.V.)
| | - Catrin Sian Rutland
- School of Veterinary Medicine and Science, Medical Faculty, University of Nottingham, Sutton, Bonington Campus, Loughborough LE12 5RD, UK;
| | - Sanja Glišić
- Center for Multidisciplinary Research, Institute of Nuclear Sciences VINCA, University of Belgrade, Mike Petrovića Alasa 12-14, 11351 Vinča, Belgrade, Serbia; (S.G.); (M.S.)
| | - Milan Senćanski
- Center for Multidisciplinary Research, Institute of Nuclear Sciences VINCA, University of Belgrade, Mike Petrovića Alasa 12-14, 11351 Vinča, Belgrade, Serbia; (S.G.); (M.S.)
| | - Milka Vrecl
- Department of Anatomy, Histology with Embryology and Cytology, Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (K.B.C.); (M.M.); (M.V.)
| | - Valentina Kubale
- Department of Anatomy, Histology with Embryology and Cytology, Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia; (K.B.C.); (M.M.); (M.V.)
- Correspondence:
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5
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Guidolin D, Marcoli M, Tortorella C, Maura G, Agnati LF. Adenosine A 2A-dopamine D 2 receptor-receptor interaction in neurons and astrocytes: Evidence and perspectives. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 169:247-277. [PMID: 31952688 DOI: 10.1016/bs.pmbts.2019.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The discovery of receptor-receptor interactions in the early 1980s, together with a more accurate focusing of allosteric mechanisms in proteins, expanded the knowledge on the G protein-coupled receptor (GPCR)-mediated signaling processes. GPCRs were seen to operate not only as monomers, but also as quaternary structures shaped by allosteric interactions. These integrative mechanisms can change the function of the GPCRs involved, leading to a sophisticated dynamic of the receptor assembly in terms of modulation of recognition and signaling. In this context, the heterodimeric complex formed by the adenosine A2A and the dopamine D2 receptors likely represents a prototypical example. The pharmacological evidence obtained, together with the tissue distribution of the A2A-D2 heteromeric complexes, suggested they could represent a target for new therapeutic strategies addressing significant disorders of the central nervous system. The research findings and the perspectives they offer from the therapeutic standpoint are the focus of the here presented discussion.
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Affiliation(s)
- Diego Guidolin
- Department of Neuroscience, Section of Anatomy, University of Padova, Padova, Italy.
| | - Manuela Marcoli
- Department of Pharmacy and Center of Excellence for Biomedical Research, University of Genova, Genova, Italy
| | - Cinzia Tortorella
- Department of Neuroscience, Section of Anatomy, University of Padova, Padova, Italy
| | - Guido Maura
- Department of Pharmacy and Center of Excellence for Biomedical Research, University of Genova, Genova, Italy
| | - Luigi F Agnati
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy; Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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6
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Burgoyne RD, Helassa N, McCue HV, Haynes LP. Calcium Sensors in Neuronal Function and Dysfunction. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035154. [PMID: 30833454 DOI: 10.1101/cshperspect.a035154] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcium signaling in neurons as in other cell types can lead to varied changes in cellular function. Neuronal Ca2+ signaling processes have also become adapted to modulate the function of specific pathways over a wide variety of time domains and these can have effects on, for example, axon outgrowth, neuronal survival, and changes in synaptic strength. Ca2+ also plays a key role in synapses as the trigger for fast neurotransmitter release. Given its physiological importance, abnormalities in neuronal Ca2+ signaling potentially underlie many different neurological and neurodegenerative diseases. The mechanisms by which changes in intracellular Ca2+ concentration in neurons can bring about diverse responses is underpinned by the roles of ubiquitous or specialized neuronal Ca2+ sensors. It has been established that synaptotagmins have key functions in neurotransmitter release, and, in addition to calmodulin, other families of EF-hand-containing neuronal Ca2+ sensors, including the neuronal calcium sensor (NCS) and the calcium-binding protein (CaBP) families, play important physiological roles in neuronal Ca2+ signaling. It has become increasingly apparent that these various Ca2+ sensors may also be crucial for aspects of neuronal dysfunction and disease either indirectly or directly as a direct consequence of genetic variation or mutations. An understanding of the molecular basis for the regulation of the targets of the Ca2+ sensors and the physiological roles of each protein in identified neurons may contribute to future approaches to the development of treatments for a variety of human neuronal disorders.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Hannah V McCue
- Centre for Genomic Research, University of Liverpool, Liverpool, United Kingdom
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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7
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Muller L, Jackson SN, Woods AS. Histidine, the less interactive cousin of arginine. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2019; 25:212-218. [PMID: 31018697 PMCID: PMC8269955 DOI: 10.1177/1469066718791793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Electrostatic interactions are one of the main factors influencing biomolecular conformation. The formation of noncovalent complexes by electrostatic interactions is governed by certain amino acid residues and post-translational modifications. It has been demonstrated that adjacent arginine forms noncovalent complex with phosphate; however, histidine noncovalent complexes have rarely been investigated. In the present work, we compare the interaction between basic epitopes (NLRRITRVN, SHHGLHSTPD) and diverse acidic and aromatic-rich peptides using both MALDI and ESI Mass spectrometry. We show that adjacent histidines can also form stable noncovalent bonds and that those bonds are probably formed by a salt bridge between the phosphate or the acid residues and the histidines. However, noncovalent complexes with the arginine epitopes form more readily and are stronger than those with histidine-containing epitopes.
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Affiliation(s)
| | | | - Amina S. Woods
- corresponding author: Amina S. Woods, Ph.D., NIDA IRP, NIH, 333 Cassell Drive, Baltimore, MD 21224, Tel: 443-740-2747, Fax: 443-740-2144,
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8
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Angelats E, Requesens M, Aguinaga D, Kreutz MR, Franco R, Navarro G. Neuronal Calcium and cAMP Cross-Talk Mediated by Cannabinoid CB 1 Receptor and EF-Hand Calcium Sensor Interactions. Front Cell Dev Biol 2018; 6:67. [PMID: 30073165 PMCID: PMC6060245 DOI: 10.3389/fcell.2018.00067] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/12/2018] [Indexed: 11/19/2022] Open
Abstract
Endocannabinoids are important players in neural development and function. They act via receptors, whose activation inhibits cAMP production. The aim of the paper was to look for calcium- and cAMP-signaling cross-talk mediated by cannabinoid CB1 receptors (CB1R) and to assess the relevance of EF-hand CaM-like calcium sensors in this regard. Using a heterologous expression system, we demonstrated that CB1R interacts with calneuron-1 and NCS1 but not with caldendrin. Furthermore, interaction motives were identified in both calcium binding proteins and the receptor, and we showed that the first two sensors competed for binding to the receptor in a Ca2+-dependent manner. Assays in neuronal primary cultures showed that, CB1R-NCS1 complexes predominate at basal Ca2+ levels, whereas in the presence of ionomycin, a calcium ionophore, CB1R-calneuron-1 complexes were more abundant. Signaling assays following forskolin-induced intracellular cAMP levels showed in mouse striatal neurons that binding of CB1R to NCS1 is required for CB1R-mediated signaling, while the binding of CB1R to calneuron-1 completely blocked Gi-mediated signaling in response to a selective receptor agonist, arachidonyl-2-chloroethylamide. Calcium levels and interaction with calcium sensors may even lead to apparent Gs coupling after CB1R agonist challenge.
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Affiliation(s)
- Edgar Angelats
- Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red, Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Requesens
- Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red, Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain
| | - David Aguinaga
- Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red, Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain
| | - Michael R Kreutz
- RG Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Leibniz Group "Dendritic Organelles and Synaptic Function", Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Rafael Franco
- Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red, Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain
| | - Gemma Navarro
- Centro de Investigación en Red, Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain.,Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Science, University of Barcelona, Barcelona, Spain
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9
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Piirainen H, Taura J, Kursula P, Ciruela F, Jaakola VP. Calcium modulates calmodulin/α-actinin 1 interaction with and agonist-dependent internalization of the adenosine A 2A receptor. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:674-686. [PMID: 28130124 DOI: 10.1016/j.bbamcr.2017.01.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/14/2017] [Accepted: 01/23/2017] [Indexed: 10/20/2022]
Abstract
Adenosine receptors are G protein-coupled receptors that sense extracellular adenosine to transmit intracellular signals. One of the four adenosine receptor subtypes, the adenosine A2A receptor (A2AR), has an exceptionally long intracellular C terminus (A2AR-ct) that mediates interactions with a large array of proteins, including calmodulin and α-actinin. Here, we aimed to ascertain the α-actinin 1/calmodulin interplay whilst binding to A2AR and the role of Ca2+ in this process. First, we studied the A2AR-α-actinin 1 interaction by means of native polyacrylamide gel electrophoresis, isothermal titration calorimetry, and surface plasmon resonance, using purified recombinant proteins. α-Actinin 1 binds the A2AR-ct through its distal calmodulin-like domain in a Ca2+-independent manner with a dissociation constant of 5-12μM, thus showing an ~100 times lower affinity compared to the A2AR-calmodulin/Ca2+ complex. Importantly, calmodulin displaced α-actinin 1 from the A2AR-ct in a Ca2+-dependent fashion, disrupting the A2AR-α-actinin 1 complex. Finally, we assessed the impact of Ca2+ on A2AR internalization in living cells, a function operated by the A2AR-α-actinin 1 complex. Interestingly, while Ca2+ influx did not affect constitutive A2AR endocytosis, it abolished agonist-dependent internalization. In addition, we demonstrated that the A2AR/α-actinin interaction plays a pivotal role in receptor internalization and function. Overall, our results suggest that the interplay of A2AR with calmodulin and α-actinin 1 is fine-tuned by Ca2+, a fact that might power agonist-mediated receptor internalization and function.
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Affiliation(s)
- Henni Piirainen
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Finland
| | - Jaume Taura
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, Spain; Institut de Neurociències, Universitat de Barcelona, Spain
| | - Petri Kursula
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Finland; Department of Biomedicine, University of Bergen, Norway
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, Spain; Institut de Neurociències, Universitat de Barcelona, Spain.
| | - Veli-Pekka Jaakola
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Finland.
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10
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Human adenosine A2A receptor binds calmodulin with high affinity in a calcium-dependent manner. Biophys J 2015; 108:903-917. [PMID: 25692595 DOI: 10.1016/j.bpj.2014.12.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 12/02/2014] [Accepted: 12/16/2014] [Indexed: 12/22/2022] Open
Abstract
Understanding how ligands bind to G-protein-coupled receptors and how binding changes receptor structure to affect signaling is critical for developing a complete picture of the signal transduction process. The adenosine A2A receptor (A2AR) is a particularly interesting example, as it has an exceptionally long intracellular carboxyl terminus, which is predicted to be mainly disordered. Experimental data on the structure of the A2AR C-terminus is lacking, because published structures of A2AR do not include the C-terminus. Calmodulin has been reported to bind to the A2AR C-terminus, with a possible binding site on helix 8, next to the membrane. The biological meaning of the interaction as well as its calcium dependence, thermodynamic parameters, and organization of the proteins in the complex are unclear. Here, we characterized the structure of the A2AR C-terminus and the A2AR C-terminus-calmodulin complex using different biophysical methods, including native gel and analytical gel filtration, isothermal titration calorimetry, NMR spectroscopy, and small-angle X-ray scattering. We found that the C-terminus is disordered and flexible, and it binds with high affinity (Kd = 98 nM) to calmodulin without major conformational changes in the domain. Calmodulin binds to helix 8 of the A2AR in a calcium-dependent manner that can displace binding of A2AR to lipid vesicles. We also predicted and classified putative calmodulin-binding sites in a larger group of G-protein-coupled receptors.
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11
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Tossavainen H, Hellman M, Piirainen H, Jaakola VP, Permi P. H(N), N, C(α), C(β) and C' assignments of the intrinsically disordered C-terminus of human adenosine A2A receptor. BIOMOLECULAR NMR ASSIGNMENTS 2015; 9:403-406. [PMID: 25952762 DOI: 10.1007/s12104-015-9618-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/03/2015] [Indexed: 06/04/2023]
Abstract
The C-terminus of the human adenosine A2A receptor differs from the other human adenosine receptors by its exceptional length and lack of a canonical cysteine residue. We have previously structurally characterized this C-terminal domain and its interaction with calmodulin. It was shown to be structurally disordered and flexible, and to bind calmodulin with high affinity in a calcium-dependent manner. Interaction with calmodulin takes place at the N-terminal end of the A2A C-terminal domain without major conformational changes in the latter. NMR was one of the biophysical methods used in the study. Here we present the H(N), N, C(α), C(β) and C' chemical shift assignments of the free form of the C-terminus residues 293-412, used in the NMR spectroscopic characterization of the domain.
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Affiliation(s)
- Helena Tossavainen
- Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014, Helsinki, Finland
| | - Maarit Hellman
- Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014, Helsinki, Finland
| | - Henni Piirainen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Veli-Pekka Jaakola
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Perttu Permi
- Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014, Helsinki, Finland.
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12
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Navarro G, Borroto-Escuela DO, Fuxe K, Franco R. Purinergic signaling in Parkinson's disease. Relevance for treatment. Neuropharmacology 2015. [PMID: 26211977 DOI: 10.1016/j.neuropharm.2015.07.024] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Purinergic signaling modulates dopaminergic neurotransmission in health and disease. Classically adenosine A1 and A2A receptors have been considered key for the fine tune control of dopamine actions in the striatum, the main CNS motor control center. The main adenosine signaling mechanism is via the cAMP pathway but the future will tell whether calcium signaling is relevant in adenosinergic control of striatal function. Very relevant is the recent approval in Japan of the adenosine A2A receptor antagonist, istradefylline, for use in Parkinson's disease patients. Purine nucleotides are also regulators of striatal dopamine neurotransmission via P2 purinergic receptors. In parallel to the alpha-synuclein hypothesis of Parkinson's disease etiology, purinergic P2X1 receptors have been identified as mediators of accumulation of the Lewy-body enriched protein alpha-synuclein. Of note is the expression in striatum of purinergic-receptor-containing heteromers that are potential targets of anti-Parkinson's disease therapies and should be taken into account in drug discovery programs. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Gemma Navarro
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Centro de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain.
| | - Dasiel O Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden; Department of Earth, Life and Environmental Sciences, Section of Physiology, Campus Scientifico Enrico Mattei, University of Urbino, Urbino, Italy.
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Rafael Franco
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Centro de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain.
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13
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Chen JF, Lee CF, Chern Y. Adenosine receptor neurobiology: overview. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 119:1-49. [PMID: 25175959 DOI: 10.1016/b978-0-12-801022-8.00001-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Adenosine is a naturally occurring nucleoside that is distributed ubiquitously throughout the body as a metabolic intermediary. In the brain, adenosine functions as an important upstream neuromodulator of a broad spectrum of neurotransmitters, receptors, and signaling pathways. By acting through four G-protein-coupled receptors, adenosine contributes critically to homeostasis and neuromodulatory control of a variety of normal and abnormal brain functions, ranging from synaptic plasticity, to cognition, to sleep, to motor activity to neuroinflammation, and cell death. This review begun with an overview of the gene and genome structure and the expression pattern of adenosine receptors (ARs). We feature several new developments over the past decade in our understanding of AR functions in the brain, with special focus on the identification and characterization of canonical and noncanonical signaling pathways of ARs. We provide an update on functional insights from complementary genetic-knockout and pharmacological studies on the AR control of various brain functions. We also highlight several novel and recent developments of AR neurobiology, including (i) recent breakthrough in high resolution of three-dimension structure of adenosine A2A receptors (A2ARs) in several functional status, (ii) receptor-receptor heterodimerization, (iii) AR function in glial cells, and (iv) the druggability of AR. We concluded the review with the contention that these new developments extend and strengthen the support for A1 and A2ARs in brain as therapeutic targets for neurologic and psychiatric diseases.
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Affiliation(s)
- Jiang-Fan Chen
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Chien-fei Lee
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
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14
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Tovo-Rodrigues L, Roux A, Hutz MH, Rohde LA, Woods AS. Functional characterization of G-protein-coupled receptors: a bioinformatics approach. Neuroscience 2014; 277:764-79. [PMID: 24997265 DOI: 10.1016/j.neuroscience.2014.06.049] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/22/2014] [Accepted: 06/18/2014] [Indexed: 12/18/2022]
Abstract
Complex molecular and cellular mechanisms regulate G protein-coupled receptors (GPCRs). It is suggested that proteins intrinsically disordered regions (IDRs) are to play a role in GPCR's intra and extracellular regions plasticity, due to their potential for post-translational modification and interaction with other proteins. These regions are defined as lacking a stable three-dimensional (3D) structure. They are rich in hydrophilic and charged, amino acids and are capable to assume different conformations which allow them to interact with multiple partners. In this study we analyzed 75 GPCR involved in synaptic transmission using computational tools for sequence-based prediction of IDRs within a protein. We also evaluated putative ligand-binding motifs using receptor sequences. The disorder analysis indicated that neurotransmitter GPCRs have a significant amount of disorder in their N-terminus, third intracellular loop (3IL) and C-terminus. About 31%, 39% and 53% of human GPCR involved in synaptic transmission are disordered in these regions. Thirty-three percent of receptors show at least one predicted PEST motif, this being statistically greater than the estimate for the rest of human GPCRs. About 90% of the receptors had at least one putative site for dimerization in their 3IL or C-terminus. ELM instances sampled in these domains were 14-3-3, SH3, SH2 and PDZ motifs. In conclusion, the increased flexibility observed in GPCRs, added to the enrichment of linear motifs, PEST and heteromerization sites, may be critical for the nervous system's functional plasticity.
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Affiliation(s)
- L Tovo-Rodrigues
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Structural Biology Unit, Integrative Neuroscience Branch, NIDA IRP, NIH, MD, United States
| | - A Roux
- Structural Biology Unit, Integrative Neuroscience Branch, NIDA IRP, NIH, MD, United States
| | - M H Hutz
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - L A Rohde
- Child and Adolescent Psychiatric Division, Department of Psychiatry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - A S Woods
- Structural Biology Unit, Integrative Neuroscience Branch, NIDA IRP, NIH, MD, United States.
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15
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Muller L, Jackson SN, Woods AS. ETD and sequential ETD localize the residues involved in D2-A2A heteromerization. RSC Adv 2014. [DOI: 10.1039/c4ra04757e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
ETD2to identify binding site in NCX.
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Affiliation(s)
- Ludovic Muller
- Structural Biology Unit
- NIDA IRP
- NIH
- Baltimore, USA
- University of Pittsburgh
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16
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Fuxe K, Borroto-Escuela DO, Romero-Fernandez W, Palkovits M, Tarakanov AO, Ciruela F, Agnati LF. Moonlighting proteins and protein-protein interactions as neurotherapeutic targets in the G protein-coupled receptor field. Neuropsychopharmacology 2014; 39:131-55. [PMID: 24105074 PMCID: PMC3857668 DOI: 10.1038/npp.2013.242] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 07/04/2013] [Accepted: 07/05/2013] [Indexed: 12/28/2022]
Abstract
There is serious interest in understanding the dynamics of the receptor-receptor and receptor-protein interactions in space and time and their integration in GPCR heteroreceptor complexes of the CNS. Moonlighting proteins are special multifunctional proteins because they perform multiple autonomous, often unrelated, functions without partitioning into different protein domains. Moonlighting through receptor oligomerization can be operationally defined as an allosteric receptor-receptor interaction, which leads to novel functions of at least one receptor protomer. GPCR-mediated signaling is a more complicated process than previously described as every GPCR and GPCR heteroreceptor complex requires a set of G protein interacting proteins, which interacts with the receptor in an orchestrated spatio-temporal fashion. GPCR heteroreceptor complexes with allosteric receptor-receptor interactions operating through the receptor interface have become major integrative centers at the molecular level and their receptor protomers act as moonlighting proteins. The GPCR heteroreceptor complexes in the CNS have become exciting new targets for neurotherapeutics in Parkinson's disease, schizophrenia, drug addiction, and anxiety and depression opening a new field in neuropsychopharmacology.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet,, Stockholm, Sweden
| | | | | | - Miklós Palkovits
- Department of Anatomy, Histology and Embryology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - Alexander O Tarakanov
- Russian Academy of Sciences, St. Petersburg Institute for Informatics and Automation, Saint Petersburg, Russia
| | - Francisco Ciruela
- Facultat de Medicina, Departament de Patologia i Terapèutica Experimental IDIBELL-Universitat de Barcelona, L'Hospitalet de Llobregat, Unitat de Farmacologia, Barcelona, Spain
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17
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Jackson SN, Woods AS. Imaging of noncovalent complexes by MALDI-MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1950-6. [PMID: 24092630 PMCID: PMC8725603 DOI: 10.1007/s13361-013-0745-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 08/12/2013] [Accepted: 08/29/2013] [Indexed: 05/25/2023]
Abstract
Noncovalent interactions govern how molecules communicate. Mass spectrometry is an important and versatile tool for the analysis of noncovalent complexes (NCX). Electrospray mass spectrometry (ESI-MS) is the most widely used MS technique for the study of NCXs because of its softer ionization and easy compatibility with the solution phase of NCX mixtures. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has also been used to study NCXs. However, successful analysis depends upon several experimental factors, such as matrix selection, solution pH, and instrumental parameters. In this study, we employ MALDI imaging mass spectrometry to investigate the location and formation of NCXs, involving both peptides and proteins, in a MALDI sample spot.
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Affiliation(s)
| | - Amina S. Woods
- corresponding author: Amina S. Woods, NIDA IRP, NIH, 333 Cassell Drive, Room 1119, Baltimore, MD 21224, Tel: 443-740-2749, Fax: 443-740-2144,
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18
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On the g-protein-coupled receptor heteromers and their allosteric receptor-receptor interactions in the central nervous system: focus on their role in pain modulation. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:563716. [PMID: 23956775 PMCID: PMC3730365 DOI: 10.1155/2013/563716] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/20/2013] [Accepted: 05/24/2013] [Indexed: 12/16/2022]
Abstract
The modulatory role of allosteric receptor-receptor interactions in the pain pathways of the Central Nervous System and the peripheral nociceptors has become of increasing interest. As integrators of nociceptive and antinociceptive wiring and volume transmission signals, with a major role for the opioid receptor heteromers, they likely have an important role in the pain circuits and may be involved in acupuncture. The delta opioid receptor (DOR) exerts an antagonistic allosteric influence on the mu opioid receptor (MOR) function in a MOR-DOR heteromer. This heteromer contributes to morphine-induced tolerance and dependence, since it becomes abundant and develops a reduced G-protein-coupling with reduced signaling mainly operating via β-arrestin2 upon chronic morphine treatment. A DOR antagonist causes a return of the Gi/o binding and coupling to the heteromer and the biological actions of morphine. The gender- and ovarian steroid-dependent recruitment of spinal cord MOR/kappa opioid receptor (KOR) heterodimers enhances antinociceptive functions and if impaired could contribute to chronic pain states in women. MOR1D heterodimerizes with gastrin-releasing peptide receptor (GRPR) in the spinal cord, mediating morphine induced itch. Other mechanism for the antinociceptive actions of acupuncture along meridians may be that it enhances the cross-desensitization of the TRPA1 (chemical nociceptor)-TRPV1 (capsaicin receptor) heteromeric channel complexes within the nociceptor terminals located along these meridians. Selective ionotropic cannabinoids may also produce cross-desensitization of the TRPA1-TRPV1 heteromeric nociceptor channels by being negative allosteric modulators of these channels leading to antinociception and antihyperalgesia.
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19
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Woods AS, Jackson SN, Egan T, Lewis EK, Tabet JC, Schultz JA. MALDI/post ionization-ion mobility mass spectrometry of noncovalent complexes of dopamine receptors' epitopes. J Proteome Res 2013; 12:1668-77. [PMID: 23469763 PMCID: PMC4144030 DOI: 10.1021/pr301004w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Protein domains involved in receptor heteromer formation are disordered and rich in the amino acids necessary for the formation of noncovalent complexes (NCX). We present mass spectral NCX data from proteins and protein receptors' epitopes obtained by combining ion mobility (IM) and MALDI. We focus on NCX involved in heteromer formation occurring between epitopes of the Dopamine D2 (D2R) and Adenosine A2A receptors (A2AR) as well as D2R and the α2 nicotinic (NR) receptor's subunit. The IM data yield information on the gas phase conformation of the singly charged NCX which are observed either directly from MALDI or as codesorbed neutrals that are subsequently postionized by a time-delayed excimer laser pulse directed onto a portion of the neutral plume created by the MALDI desorption laser. Imaging mass spectrometry of the matrix/epitope dried droplet surface shows that the acidic and basic epitopes and their NCX are found to be spatially collocated within regions as small as 25 × 50 μm(2). Subtle differences in the relative abundance of protonated and cationized NCX and epitopes are measured in spatial regions near the sodium-rich outer border of the droplet.
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MESH Headings
- Calmodulin/chemistry
- Epitopes/analysis
- Epitopes/chemistry
- Image Processing, Computer-Assisted
- Mass Spectrometry/methods
- Peptides/analysis
- Peptides/chemistry
- Receptor, Adenosine A2A/chemistry
- Receptor, Adenosine A2A/immunology
- Receptor, Adenosine A2A/metabolism
- Receptors, Dopamine/chemistry
- Receptors, Dopamine/immunology
- Receptors, Dopamine D2/chemistry
- Receptors, Dopamine D2/immunology
- Receptors, Dopamine D2/physiology
- Receptors, Nicotinic/chemistry
- Receptors, Nicotinic/immunology
- Receptors, Nicotinic/metabolism
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
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20
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Navarro G, Hradsky J, Lluís C, Casadó V, McCormick PJ, Kreutz MR, Mikhaylova M. NCS-1 associates with adenosine A(2A) receptors and modulates receptor function. Front Mol Neurosci 2012; 5:53. [PMID: 22529776 PMCID: PMC3328853 DOI: 10.3389/fnmol.2012.00053] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 04/02/2012] [Indexed: 11/13/2022] Open
Abstract
Modulation of G protein-coupled receptor (GPCR) signaling by local changes in intracellular calcium concentration is an established function of Calmodulin (CaM) which is known to interact with many GPCRs. Less is known about the functional role of the closely related neuronal EF-hand Ca2+-sensor proteins that frequently associate with CaM targets with different functional outcome. In the present study we aimed to investigate if a target of CaM—the A2A adenosine receptor is able to associate with two other neuronal calcium binding proteins (nCaBPs), namely NCS-1 and caldendrin. Using bioluminescence resonance energy transfer (BRET) and co-immunoprecipitation experiments we show the existence of A2A—NCS-1 complexes in living cells whereas caldendrin did not associate with A2A receptors under the conditions tested. Interestingly, NCS-1 binding modulated downstream A2A receptor intracellular signaling in a Ca2+-dependent manner. Taken together this study provides further evidence that neuronal Ca2+-sensor proteins play an important role in modulation of GPCR signaling.
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Affiliation(s)
- Gemma Navarro
- Faculty of Biology, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas and Department of Biochemistry and Molecular Biology, University of Barcelona Barcelona, Spain
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21
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Borroto-Escuela DO, Tarakanov AO, Guidolin D, Ciruela F, Agnati LF, Fuxe K. Moonlighting characteristics of G protein-coupled receptors: focus on receptor heteromers and relevance for neurodegeneration. IUBMB Life 2012; 63:463-72. [PMID: 21698749 DOI: 10.1002/iub.473] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
It is proposed that the moonlighting concept can be applied to G protein coupled receptors (GPCRs) as, obviously, they can carry out different types of functions. The same motifs in, for example, the third intracellular loop, can moonlight by switching between receptor-receptor interactions and interactions with signaling proteins such as G proteins or calmodulin. A "guide-and-clasp" manner of receptor-receptor interactions has been proposed where the "adhesive guides" may be the triplet homologies. As an example, the triplets AAR (or RAA) and AAE (or EAA) homologies in A(2A) R-D2 R heteromers may guide-and-clasp binding not only of the two protomers but also of calmodulin and G(i) . A beautiful moonlighting phenomenon in the A(2A) R-D2 R heteromer is that the positively charged D2 R N-terminal third intracellular loop epitope (VLRRRRKRVN) may switch between bindings to the negatively charged A(2A) R epitope (SAQEpSQGNT), localized in the medium segment of the C terminus of the A2A receptor to several negative epitopes of calmodulin. Furthermore, overlapping motifs may favor moonlighting to G(i/o) via inter alia electrostatic interaction between triplets AAR(in D2 R third intracellular loop) and AAE (G(i/alpha1) ) (and/or their symmetric variants) contributing to guide-and-clasp D2 R-G(i) interactions Thus, moonlighting in GPCR heteromers can take place via allosteric receptor-receptor interactions and is also described in D1 R-D2 R, D2 R-5-HT2 R,and A1 R-P2Y1 heteromers. Allosteric receptor-receptor interactions in GPCR-receptor tyrosine kinases (RTKs) heteromers and postulated ion channel receptor-RTK heteromers-like, for example, AMPA-NMDA-TrkB heteromers may lead to moonlighting of the participating GPCR and RTK protomers altering, for example, the pattern of the five major signaling pathways of the RTKs favoring MAPK and/or mTOR signaling with high relevance for neurodegenerative processes and depression induced atrophy of neurons. Moonlighting may also develop in the intracellular loops and C-terminal of the GPCRs as a result of dynamic allosteric interactions between different types of G proteins and other receptor interacting proteins in these domains of the receptor.
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22
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Darii E, Saravanamuthu G, Afonso C, Alves S, Gut I, Tabet JC. Possible conformational change within the desolvated and cationized sBBI/trypsin non-covalent complex during the collision-induced dissociation process. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:1725-1734. [PMID: 21598332 DOI: 10.1002/rcm.5039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Electrospray ionization mass spectrometry (ESI-MS) has become an analytical technique widely used for the investigation of non-covalent protein-protein and protein-ligand complexes due to the soft desolvation conditions that preserve the stoichiometry of the interacting partners. Dissociation studies of solvated or desolvated complexes (in the source and in the collision cell, respectively) allow access to information on protein conformation and localization of the metal ions involved in protein structure stabilization and biological activity. The complex of bovine trypsin and small soybean Bowman-Birk inhibitor (sBBI) was studied by ESI-MS to determine changes occurring within the complex during its transfer from droplets to the gas phase independently of the ion polarity. Under collision-induced dissociation (CID) conditions, unexpected binding of the Ca(2+) ion (cofactor of native trypsin) to the inhibitor molecule was observed within the desolvated sBBI/trypsin/Ca(2+) complex (with a 1:1:1 stoichiometry). This formal gas-phase migration of the calcium ion from trypsin to the inhibitor may be related to conformational rearrangements in the solvent-free and likely collapsed complex. However, under conditions leading to the increase in complex charge state, the appearance of the cationized trypsin molecule was detected during complex dissociation, thus reflecting different pathways of the evolution of complex conformation.
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Affiliation(s)
- Ekaterina Darii
- Equipe de Spectrométrie de masse, Institut Parisien de Chimie Moléculaire, UMR 7201, Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, 75252 Paris Cedex 05, France
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23
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Verzijl D, IJzerman AP. Functional selectivity of adenosine receptor ligands. Purinergic Signal 2011; 7:171-92. [PMID: 21544511 PMCID: PMC3146648 DOI: 10.1007/s11302-011-9232-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 04/05/2011] [Indexed: 12/11/2022] Open
Abstract
Adenosine receptors are plasma membrane proteins that transduce an extracellular signal into the interior of the cell. Basically every mammalian cell expresses at least one of the four adenosine receptor subtypes. Recent insight in signal transduction cascades teaches us that the current classification of receptor ligands into agonists, antagonists, and inverse agonists relies very much on the experimental setup that was used. Upon activation of the receptors by the ubiquitous endogenous ligand adenosine they engage classical G protein-mediated pathways, resulting in production of second messengers and activation of kinases. Besides this well-described G protein-mediated signaling pathway, adenosine receptors activate scaffold proteins such as β-arrestins. Using innovative and sensitive experimental tools, it has been possible to detect ligands that preferentially stimulate the β-arrestin pathway over the G protein-mediated signal transduction route, or vice versa. This phenomenon is referred to as functional selectivity or biased signaling and implies that an antagonist for one pathway may be a full agonist for the other signaling route. Functional selectivity makes it necessary to redefine the functional properties of currently used adenosine receptor ligands and opens possibilities for new and more selective ligands. This review focuses on the current knowledge of functionally selective adenosine receptor ligands and on G protein-independent signaling of adenosine receptors through scaffold proteins.
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Affiliation(s)
- Dennis Verzijl
- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
| | - Ad P. IJzerman
- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
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24
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The triplet puzzle of homologies in receptor heteromers exists also in other types of protein-protein interactions. J Mol Neurosci 2011; 44:173-7. [PMID: 21416272 DOI: 10.1007/s12031-011-9511-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 03/03/2011] [Indexed: 11/26/2022]
Abstract
Based on our theory, we point out main triplets of amino acid residues in the GABAB1 receptor, found in the central and peripheral nervous system, which seem to be critical for both receptor heterodimerization and chemokine binding. The obtained results suggest that these triplets may "guide-and-clasp" protein-protein interactions playing a role, e.g., in neuroinflammation disorders.
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25
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Fuxe K, Marcellino D, Borroto-Escuela DO, Frankowska M, Ferraro L, Guidolin D, Ciruela F, Agnati LF. The changing world of G protein-coupled receptors: from monomers to dimers and receptor mosaics with allosteric receptor-receptor interactions. J Recept Signal Transduct Res 2011; 30:272-83. [PMID: 20684666 DOI: 10.3109/10799893.2010.506191] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Based on indications of direct physical interactions between neuropeptide and monoamine receptors in the early 1980s, the term receptor-receptor interactions was introduced and later on the term receptor heteromerization in the early 1990s. Allosteric mechanisms allow an integrative activity to emerge either intramolecularly in G protein-coupled receptor (GPCR) monomers or intermolecularly via receptor-receptor interactions in GPCR homodimers, heterodimers, and receptor mosaics. Stable heteromers of Class A receptors may be formed that involve strong high energy arginine-phosphate electrostatic interactions. These receptor-receptor interactions markedly increase the repertoire of GPCR recognition, signaling and trafficking in which the minimal signaling unit in the GPCR homomers appears to be one receptor and one G protein. GPCR homomers and GPCR assemblies are not isolated but also directly interact with other proteins to form horizontal molecular networks at the plasma membrane.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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26
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Feldkamp MD, O'Donnell SE, Yu L, Shea MA. Allosteric effects of the antipsychotic drug trifluoperazine on the energetics of calcium binding by calmodulin. Proteins 2010; 78:2265-82. [PMID: 20544963 DOI: 10.1002/prot.22739] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Trifluoperazine (TFP; Stelazine) is an antagonist of calmodulin (CaM), an essential regulator of calcium-dependent signal transduction. Reports differ regarding whether, or where, TFP binds to apo CaM. Three crystallographic structures (1CTR, 1A29, and 1LIN) show TFP bound to (Ca(2+))(4)-CaM in ratios of 1, 2, or 4 TFP per CaM. In all of these, CaM domains adopt the "open" conformation seen in CaM-kinase complexes having increased calcium affinity. Most reports suggest TFP also increases calcium affinity of CaM. To compare TFP binding to apo CaM and (Ca(2+))(4)-CaM and explore differential effects on the N- and C-domains of CaM, stoichiometric TFP titrations of CaM were monitored by (15)N-HSQC NMR. Two TFP bound to apo CaM, whereas four bound to (Ca(2+))(4)-CaM. In both cases, the preferred site was in the C-domain. During the titrations, biphasic responses for some resonances suggested intersite interactions. TFP-binding sites in apo CaM appeared distinct from those in (Ca(2+))(4)-CaM. In equilibrium calcium titrations at defined ratios of TFP:CaM, TFP reduced calcium affinity at most levels tested; this is similar to the effect of many IQ-motifs on CaM. However, at the highest level tested, TFP raised the calcium affinity of the N-domain of CaM. A model of conformational switching is proposed to explain how TFP can exert opposing allosteric effects on calcium affinity by binding to different sites in the "closed," "semi-open," and "open" domains of CaM. In physiological processes, apo CaM, as well as (Ca(2+))(4)-CaM, needs to be considered a potential target of drug action.
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Affiliation(s)
- Michael D Feldkamp
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242-1109, USA
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McCue HV, Haynes LP, Burgoyne RD. The diversity of calcium sensor proteins in the regulation of neuronal function. Cold Spring Harb Perspect Biol 2010; 2:a004085. [PMID: 20668007 DOI: 10.1101/cshperspect.a004085] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Calcium signaling in neurons as in other cell types mediates changes in gene expression, cell growth, development, survival, and cell death. However, neuronal Ca(2+) signaling processes have become adapted to modulate the function of other important pathways including axon outgrowth and changes in synaptic strength. Ca(2+) plays a key role as the trigger for fast neurotransmitter release. The ubiquitous Ca(2+) sensor calmodulin is involved in various aspects of neuronal regulation. The mechanisms by which changes in intracellular Ca(2+) concentration in neurons can bring about such diverse responses has, however, become a topic of widespread interest that has recently focused on the roles of specialized neuronal Ca(2+) sensors. In this article, we summarize synaptotagmins in neurotransmitter release, the neuronal roles of calmodulin, and the functional significance of the NCS and the CaBP/calneuron protein families of neuronal Ca(2+) sensors.
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Affiliation(s)
- Hannah V McCue
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, United Kingdom
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From cradle to twilight: the carboxyl terminus directs the fate of the A(2A)-adenosine receptor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:1350-7. [PMID: 20478264 DOI: 10.1016/j.bbamem.2010.05.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 05/05/2010] [Accepted: 05/05/2010] [Indexed: 01/04/2023]
Abstract
The extended carboxyl terminus of the A(2A)-adenosine receptor is known to engage several proteins other than those canonically involved in signalling by GPCRs (i.e., G proteins, G protein-coupled receptor kinases/GRKs, arrestins). The list includes the deubiquinating enzyme USP4, α-actinin, the guanine nucleotide exchange factor for ARF6 ARNO, translin-X-associated protein, calmodulin, the neuronal calcium binding protein NECAB2 and the synapse associated protein SAP102. However, if the fate of the A(2A)-receptor is taken into account - from its birthplace in the endoplasmic reticulum to its presumed site of disposal in the lysosome, it is evident that many more proteins must interact with the A(2A)-adenosine receptor. There are several arguments that support the conjecture that these interactions will preferentially occur with the carboxyl terminus of the A(2A)-adeonsine receptor: (i) the extended carboxyl terminus (of 122 residues=) offers the required space to accommodate companions; (ii) analogies can be drawn with other receptors, which engage several of these binding partners with their C-termini. This approach allows for defining the nature of the unknown territory. As an example, we posit a chaperone/coat protein complex-II (COPII) exchange model that must occur on the carboxyl terminus of the receptor. This model accounts for the observation that a minimum size of the C-terminus is required for correct folding of the receptor. It also precludes premature recruitment of the COPII-coat to a partially folded receptor.
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Tarakanov AO, Fuxe KG. Triplet Puzzle: Homologies of Receptor Heteromers. J Mol Neurosci 2009; 41:294-303. [DOI: 10.1007/s12031-009-9313-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 11/12/2009] [Indexed: 11/27/2022]
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Ferré S, Woods AS, Navarro G, Aymerich M, Lluís C, Franco R. Calcium-mediated modulation of the quaternary structure and function of adenosine A2A-dopamine D2 receptor heteromers. Curr Opin Pharmacol 2009; 10:67-72. [PMID: 19896897 DOI: 10.1016/j.coph.2009.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 10/05/2009] [Accepted: 10/05/2009] [Indexed: 10/20/2022]
Abstract
The adenosine A(2A)-dopamine D(2) receptor heteromer is one of the most studied receptor heteromers. It has important implications for basal ganglia function and pathology. Recent studies using Bioluminescence and Sequential Resonance Energy Transfer techniques shed light on the role of Ca(2+) in the modulation of the quaternary structure of the A(2A)-D(2) receptor heteromer, which was found to depend on the binding of calmodulin (CaM) to the carboxy-terminus of the A(2A) receptor in the A(2A)-D(2) receptor heteromer. Importantly, the changes in quaternary structure correlate with changes in function. A Ca(2+)/CaM-dependent modulation of MAPK signaling upon agonist treatment could be observed in cells expressing A(2A)-D(2) receptor heteromers. These studies provide a first example of a Ca(2+)-mediated modulation of the quaternary structure and function of a receptor heteromer.
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Affiliation(s)
- Sergi Ferré
- National Institute on Drug Abuse, IRP, NIH, DHHS, Baltimore, MD 21224, USA.
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Navarro G, Aymerich MS, Marcellino D, Cortés A, Casadó V, Mallol J, Canela EI, Agnati L, Woods AS, Fuxe K, Lluís C, Lanciego JL, Ferré S, Franco R. Interactions between calmodulin, adenosine A2A, and dopamine D2 receptors. J Biol Chem 2009; 284:28058-28068. [PMID: 19632986 DOI: 10.1074/jbc.m109.034231] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Ca(2+)-binding protein calmodulin (CaM) has been shown to bind directly to cytoplasmic domains of some G protein-coupled receptors, including the dopamine D(2) receptor. CaM binds to the N-terminal portion of the long third intracellular loop of the D(2) receptor, within an Arg-rich epitope that is also involved in the binding to G(i/o) proteins and to the adenosine A(2A) receptor, with the formation of A(2A)-D(2) receptor heteromers. In the present work, by using proteomics and bioluminescence resonance energy transfer (BRET) techniques, we provide evidence for the binding of CaM to the A(2A) receptor. By using BRET and sequential resonance energy transfer techniques, evidence was obtained for CaM-A(2A)-D(2) receptor oligomerization. BRET competition experiments indicated that, in the A(2A)-D(2) receptor heteromer, CaM binds preferentially to a proximal C terminus epitope of the A(2A) receptor. Furthermore, Ca(2+) was found to induce conformational changes in the CaM-A(2A)-D(2) receptor oligomer and to selectively modulate A(2A) and D(2) receptor-mediated MAPK signaling in the A(2A)-D(2) receptor heteromer. These results may have implications for basal ganglia disorders, since A(2A)-D(2) receptor heteromers are being considered as a target for anti-parkinsonian agents.
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Affiliation(s)
- Gemma Navarro
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, and Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Marisol S Aymerich
- Centro de Investigación Médica Aplicada Neurociencias (CIMA), Universidad de Navarra, Avda. Pio XII 55, 31008 Pamplona, Spain
| | - Daniel Marcellino
- Department of Neuroscience, Karolinska Institute, 17177 Stockholm, Sweden
| | - Antoni Cortés
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, and Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Vicent Casadó
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, and Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Josefa Mallol
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, and Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Enric I Canela
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, and Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Luigi Agnati
- Department of Neuroscience, Karolinska Institute, 17177 Stockholm, Sweden
| | - Amina S Woods
- National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institute, 17177 Stockholm, Sweden
| | - Carmen Lluís
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, and Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Jose Luis Lanciego
- Centro de Investigación Médica Aplicada Neurociencias (CIMA), Universidad de Navarra, Avda. Pio XII 55, 31008 Pamplona, Spain
| | - Sergi Ferré
- National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224
| | - Rafael Franco
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, and Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain; Centro de Investigación Médica Aplicada Neurociencias (CIMA), Universidad de Navarra, Avda. Pio XII 55, 31008 Pamplona, Spain.
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Brain receptor mosaics and their intramembrane receptor-receptor interactions: molecular integration in transmission and novel targets for drug development. J Acupunct Meridian Stud 2009; 2:1-25. [PMID: 20633470 DOI: 10.1016/s2005-2901(09)60011-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 01/06/2009] [Indexed: 11/21/2022] Open
Abstract
The concept of intramembrane receptor-receptor interactions and evidence for their existence was introduced by Agnati and Fuxe in 1980/81 suggesting the existence of heteromerization of receptors. In 1982, they proposed the existence of aggregates of multiple receptors in the plasma membrane and coined the term receptor mosaics (RM). In this way, cell signaling becomes a branched process beginning at the level of receptor recognition at the plasma membrane where receptors can directly modify the ligand recognition and signaling capacity of the receptors within a RM. Receptor-receptor interactions in RM are classified as operating either with classical cooperativity, when consisting of homomers or heteromers of similar receptor subtypes having the same transmitter, or non-classical cooperativity, when consisting of heteromers. It has been shown that information processing within a RM depends not only on its receptor composition, but also on the topology and the order of receptor activation determined by the concentrations of the ligands and the receptor properties. The general function of RM has also been demonstrated to depend on allosteric regulators (e.g., homocysteine) of the receptor subtypes present. RM as integrative nodes for receptor-receptor interactions in conjunction with membrane associated proteins may form horizontal molecular networks in the plasma membrane coordinating the activity of multiple effector systems modulating the excitability and gene expression of the cells. The key role of electrostatic epitope-epitope interactions will be discussed for the formation of the RM. These interactions probably represent a general molecular mechanism for receptor-receptor interactions and, without a doubt, indicate a role for phosphorylation-dephosphorylation events in these interactions. The novel therapeutic aspects given by the RMs will be discussed in the frame of molecular neurology and psychiatry and combined drug therapy appears as the future way to go.
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