Molecular, biochemical and behavioural evidence for a novel oxytocin receptor and serotonin 2C receptor heterocomplex

Barbara Chruścicka; Caitlin S M Cowan; Shauna E Wallace Fitzsimons; Dasiel O Borroto-Escuela; Clémentine M Druelle; Panagiota Stamou; Cristian A Bergmann; Timothy G Dinan; David A Slattery; Kjell Fuxe; John F Cryan; Harriët Schellekens

doi:10.1016/j.neuropharm.2020.108394

Molecular, biochemical and behavioural evidence for a novel oxytocin receptor and serotonin 2C receptor heterocomplex

Neuropharmacology. 2021 Feb 1:183:108394. doi: 10.1016/j.neuropharm.2020.108394. Epub 2020 Nov 12.

Affiliations

¹ APC Microbiome Ireland, University College Cork, Cork, Ireland; Małopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland.
² APC Microbiome Ireland, University College Cork, Cork, Ireland.
³ Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
⁴ APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland.
⁵ Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Frankfurt, Germany.
⁶ APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
⁷ APC Microbiome Ireland, University College Cork, Cork, Ireland; Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland. Electronic address: H.Schellekens@ucc.ie.

PMID: 33188842
DOI: 10.1016/j.neuropharm.2020.108394

Abstract

The complexity of oxytocin-mediated functions is strongly associated with its modulatory effects on other neurotransmission systems, including the serotonin (5-hydroxytryptamine, 5-HT) system. Signalling between oxytocin (OT) and 5-HT has been demonstrated during neurodevelopment and in the regulation of specific emotion-based behaviours. It is suggested that crosstalk between neurotransmitters is driven by interaction between their specific receptors, particularly the oxytocin receptor (OTR) and the 5-hydroxytryptamine 2C receptor (5-HTR_2C), but evidence for this and the downstream signalling consequences that follow are lacking. Considering the overlapping central expression profiles and shared involvement of OTR and 5-HTR_2C in certain endocrine functions and behaviours, including eating behaviour, social interaction and locomotor activity, we investigated the existence of functionally active OTR/5-HTR_2C heterocomplexes. Here, we demonstrate evidence for a potential physical interaction between OTR and 5-HTR_2Cin vitro in a cellular expression system using flow cytometry-based FRET (fcFRET). We could recapitulate this finding under endogenous expression levels of both receptors via in silico analysis of single cell transcriptomic data and ex vivo proximity ligation assay (PLA). Next, we show that co-expression of the OTR/5-HTR_2C pair resulted in a significant depletion of OTR-mediated Gαq-signalling and significant changes in receptor trafficking. Of note, attenuation of OTR-mediated downstream signalling was restored following pharmacological blockade of the 5-HTR_2C. Finally, we demonstrated a functional relevance of this novel heterocomplex, in vivo, as 5-HTR_2C antagonism increased OT-mediated hypoactivity in mice. Overall, we provide compelling evidence for the formation of functionally active OTR/5-HTR_2C heterocomplexes, adding another level of complexity to OTR and 5-HTR_2C signalling functionality. This article is part of the special issue on Neuropeptides.

Keywords: 5-HTR(2C); GPCR crosstalk; Heteroreceptor complexes; Hypoactivity; OTR.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Behavior Rating Scale
Brain / metabolism
GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism
HEK293 Cells
Humans
Male
Mice
Oxytocin / metabolism*
Protein Transport
Rats
Rats, Sprague-Dawley
Receptor Cross-Talk
Receptor, Serotonin, 5-HT2C / metabolism*
Receptors, Oxytocin / metabolism*
Serotonin
Serotonin 5-HT2 Receptor Antagonists
Signal Transduction

Substances

Receptor, Serotonin, 5-HT2C
Receptors, Oxytocin
Serotonin 5-HT2 Receptor Antagonists
Serotonin
Oxytocin
GTP-Binding Protein alpha Subunits, Gq-G11