The olfactory Olfr-78/51E2 receptor interacts with the adenosine A2A receptor. Effect of menthol and 1,8-cineole on A2A receptor-mediated signaling

Jaume Lillo; Irene García-Pérez; Alejandro Lillo; Joan Serrano-Marín; Eva Martínez-Pinilla; Gemma Navarro; Rafael Franco

doi:10.3389/fphar.2023.1108617

The olfactory Olfr-78/51E2 receptor interacts with the adenosine A_2A receptor. Effect of menthol and 1,8-cineole on A_2A receptor-mediated signaling

Front Pharmacol. 2023 May 17:14:1108617. doi: 10.3389/fphar.2023.1108617. eCollection 2023.

Authors

Jaume Lillo^{1

2}, Irene García-Pérez³, Alejandro Lillo^{1

2}, Joan Serrano-Marín³, Eva Martínez-Pinilla^{4

5

6}, Gemma Navarro^{1

2

7}, Rafael Franco^{2

3

8}

Affiliations

¹ Department of Biochemistry and Physiology, School of Pharmacy and Food Science, Universitat de Barcelona, Barcelona, Spain.
² CiberNed, Network Center for Neurodegenerative Diseases, National Spanish Health Institute Carlos III, Madrid, Spain.
³ Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain.
⁴ Department of Morphology and Cell Biology, Faculty of Medicine, University of Oviedo, Asturias, Spain.
⁵ Instituto de Neurociencias del Principado de Asturias (INEUROPA), Asturias, Spain.
⁶ Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Asturias, Spain.
⁷ Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.
⁸ School of Chemistry, Universitat de Barcelona, Barcelona, Spain.

Abstract

Heteromer formation is unknown for the olfactory family of G protein-coupled receptors (GPCRs). We here identified, in a heterologous system, heteromers formed by the adenosine A_2A receptor (A_2AR), which is a target for neuroprotection, and an olfactory receptor. A_2AR interacts with the receptor family 51, subfamily E, member 2 (OR51E2), the human ortholog of the mouse Olfr-78, whose mRNA is differentially expressed in activated microglia treated with adenosine receptor ligands. Bioluminescence resonance energy transfer (BRET) assays were performed in HEK-293T cells expressing the human version of the receptors, OR51E2 and A_2AR, fused, respectively, to Renilla luciferase (RLuc) and the yellow fluorescent protein (YFP). BRET data was consistent with a receptor-receptor interaction whose consequences at the functional level were measured by cAMP level determination in CHO cells. Results showed an olfactory receptor-mediated partial blockade of G_s coupling to the A_2AR, i.e., the effect of the A_2AR selective agonist on intracellular levels of cAMP was significantly reduced. Two odorants, menthol and 1,8-cineole, which failed to show G_olf-mediated OR51E2 activation because they did not increase cytosolic cAMP levels, reduced the BRET readings in cells expressing A_2AR-YFP and OR51E2-Rluc, most likely suggesting a conformational change of at least one receptor. These odorants led to an almost complete block of A_2AR coupling to G_s.

Keywords: G protein-coupled receptor; adenosine receptor; heteromer; neuroprotection; olfactory receptor; receptor-receptor interactions; signaling.

Grants and funding

This work was supported by grants PID2020-113430RB-I00, PID2021-126600OB-I00 and PDC2022-133171-I00 funded by Spanish MCIN/AEI/10.13039/501100011033 and, as appropriate, by “ERDF A way of making Europe”, by the “European Union” or by the “European Union Next-Generation EU/PRTR”.