Abstract
Association of G protein‐coupled receptors into heterodimeric complexes has been reported for over 50 receptor pairs in vitro but functional in vivo validation remains a challenge. Our recent in vitro studies defined the functional fingerprint of heteromers composed of Gi‐coupled melatonin MT2 receptors and Gq‐coupled serotonin 5‐HT2C receptors, in which melatonin transactivates phospholipase C (PLC) through 5‐HT2C. Here, we identified this functional fingerprint in the mouse brain. Gq protein activation was probed by [35S]GTPγS incorporation followed by Gq immunoprecipitation, and PLC activation by determining the inositol phosphate levels in brain lysates of animals previously treated with melatonin. Melatonin concentration‐dependently activated Gq proteins and PLC in the hypothalamus and cerebellum but not in cortex. These effects were inhibited by the 5‐HT2C receptor‐specific inverse agonist SB‐243213, and were absent in MT2 and 5‐HT2C knockout mice, fully recapitulating previous in vitro data and indicating the involvement of MT2/5‐HT2C heteromers. The antidepressant agomelatine had a similar effect than melatonin when applied alone but blocked the melatonin‐promoted Gq activation due to its 5‐HT2C antagonistic component. Collectively, we provide strong functional evidence for the existence of MT2/5‐HT2C heteromeric complexes in mouse brain. These heteromers might participate in the in vivo effects of agomelatine.
Original language | English |
---|---|
Article number | e21161 |
Number of pages | 12 |
Journal | The FASEB Journal |
Volume | 35 |
Issue number | 1 |
Early online date | 6 Nov 2020 |
DOIs | |
Publication status | Published - Jan 2021 |
Bibliographical note
The authors are grateful to E. Trinquet (Cisbio) for advice in the in vivo IP1 protocol. This work was supported by grants from the Fondation Recherche Médicale (Equipe FRM2013, DEQ 20130326503 and Equipe FRM 2019, EQU201903008055 to RJ); The French National Research Agency (ANR) ANR-19-CE16-0025-01 (Mito-GPCR) to RJ, Recherches Partenariales et Innovation Biomédicale 2012 “MED-HET-REC-2”; INSERM; CNRS and the Who am I? laboratory of excellence ANR-11-LABX- 0071 funded by the French Government through its “Investments for the Future” program operated by the ANR under Grant ANR-11-IDEX-0005-01; La Ligue Contre le Cancer N/Ref: RS19/75-127 and the Biotechnology and Biological Sciences Research Council (BB/R01857X/1 and BB/N017838/1 to LKH).Data Availability Statement
Additional Supporting Information may be found online in the Supporting Information section.Keywords
- cerebellum
- GPCR heteromerization
- hypothalamus
- melatonin receptor
- receptor transactivation
- 5-HT2C
- 5-HT
- melatonin receptors