Control of glutamate release by complexes of adenosine and cannabinoid receptors

• Published in: BMC biology Vol. 18; no. 1; p. 9
• Main Authors: Köfalvi, Attila, Moreno, Estefanía, Cordomí, Arnau, Cai, Ning-Sheng, Fernández-Dueñas, Victor, Ferreira, Samira G., Guixà-González, Ramón, Sánchez-Soto, Marta, Yano, Hideaki, Casadó-Anguera, Verònica, Cunha, Rodrigo A., Sebastião, Ana M, Ciruela, Francisco, Pardo, Leonardo, Casadó, Vicent, Ferré, Sergi
• Format: Journal Article
• Language: English
• Published: England Springer Nature 23-01-2020; BioMed Central Ltd; BioMed Central; BMC
• Subjects: Activation; Adenosine; Adenosine A1 receptors; Adenosine A2A receptor; Adenosine A2A receptors; Adenylate cyclase; Adenylyl cyclase; Agonists; Biochemical characteristics; Biochemistry; C-Terminus; Caffeine; Cannabinoid CB1 receptor; Cannabinoid CB1 receptors; Cannabinoids; Cell receptors; Computational neuroscience; Control; Coordination compounds; Depolarization; Dopamine; Dopamine D2 receptors; Experiments; Glutamate; Glutamate transmission; Glutamatergic transmission; GPCR heteromers; Guanine nucleotide-binding protein; Interfaces; Localization; Mammals; Materials; Neostriatum; Nerve endings; Neuromodulation; Neurotransmission; Peptides; Protein structure; Proteins; Quaternary structure; Receptors; Signaling; Striatum; Terminals; Portugal; GPCR heteromers; Striatum; Adenylyl cyclase; Glutamate transmission; Adenosine A2A receptor; Cannabinoid CB1 receptor
• ISSN: 1741-7007; 1741-7007
• DOI: 10.1186/s12915-020-0739-0

© The Author(s). 2020 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Background: It has been hypothesized that heteromers of adenosine A2A receptors (A2AR) and cannabinoid CB1 receptors (CB1R) localized in glutamatergic nerve terminals mediate the integration of adenosine and endocannabinoid signaling involved in the modulation of striatal excitatory neurotransmission. Previous studies have demonstrated the existence of A2AR-CB1R heteromers in artificial cell systems. A dependence of A2AR signaling for the Gi protein-mediated CB1R signaling was described as one of its main biochemical characteristics. However, recent studies have questioned the localization of functionally significant A2AR-CB1R heteromers in striatal glutamatergic terminals. Results: Using a peptide-interfering approach combined with biophysical and biochemical techniques in mammalian transfected cells and computational modeling, we could establish a tetrameric quaternary structure of the A2AR-CB1R heterotetramer. This quaternary structure was different to the also tetrameric structure of heteromers of A2AR with adenosine A1 receptors or dopamine D2 receptors, with different heteromeric or homomeric interfaces. The specific quaternary structure of the A2A-CB1R, which depended on intermolecular interactions involving the long C-terminus of the A2AR, determined a significant A2AR and Gs protein-mediated constitutive activation of adenylyl cyclase. Using heteromer-interfering peptides in experiments with striatal glutamatergic terminals, we could then demonstrate the presence of functionally significant A2AR-CB1R heteromers with the same biochemical characteristics of those studied in mammalian transfected cells. First, either an A2AR agonist or an A2AR antagonist allosterically counteracted Gi-mediated CB1R agonist-induced inhibition of depolarization-induced glutamate release. Second, co-application of both an A2AR agonist and an antagonist cancelled each other effects. Finally, a CB1R agonist inhibited glutamate release dependent on a constitutive activation of A2AR by a canonical Gs-Gi antagonistic interaction at the adenylyl cyclase level. Conclusions: We demonstrate that the well-established cannabinoid-induced inhibition of striatal glutamate release can mostly be explained by a CB1R-mediated counteraction of the A2AR-mediated constitutive activation of adenylyl cyclase in the A2AR-CB1R heteromer.
Work supported with the intramural funds of the National Institute on Drug Abuse, “Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación/FEDER” (SAF2015-74627-JIN, SAF2016-77830-R, SAF2017-87349-R) and ISCIII/FEDER (PIE14/00034), the Catalan government (2017 SGR 1604), “Fundació la Marató de TV3” (20152031), FWO (SBO-140028), “Fundação para a Ciência e a Tecnologia” (PTDC/DTP-FTO/3346/2014 and PTDC/MED-NEU/31274/2017), FEDER (QREN) through “Programa Operacional Factores de Competitividade” (COMPETE 2020, POCI-01-0145-FEDER-007440, CENTRO-01-0145-FEDER-000012-N2323P30, and UID/NEU/04539/2019), and through “Programa Mais Centro” (CENTRO-01-0246-FEDER-000010 and CENTRO-07-ST24-FEDER-002006).