CHARACTERIZATION OF DOPAMINE RECEPTORS INTERACTIONS ACROSS THE GPCR LANDSCAPE

G-protein coupled receptors (GPCRs) are membrane proteins essential for cell signalling and can form homo- and heteromers, involved in both physiological and pathological processes. Dopamine Receptor (DR, Class A GPCR) homomerization dysfunction is linked to brain disorders like schizophrenia, drug addiction and anxiety. Detailed investigation into their heteromerization with other GPCRs could improve our basic understanding of GPCR function, disease mechanisms and potentially support the development of new treatment strategies.This project therefore aims to systematically characterise the interactions between the long and short variants of the DR2 with different GPCRs. For this purpose, we have developed a Bioluminescence Resonance Energy Transfer (BRET)-based screening assay platform to investigate GPCRs proximity in a heterologous expression system. Using this DR2-DR2 biosensor interaction assay, in which a reduction in BRET signal indicates disruption of DR2 biosensor proximity, we confirmed the assay with several GPCRS, which are already known to interact with DR2. In addition, we identified previously unreported GPCR interaction partners that modify DR2 proximity, including Muscarinic Acetylcholine Receptor M3 and Alpha2A-Adrenergic Receptor. We further observed differences in the interaction profile for the long and short DR2 splice variants, suggesting isoform specific interaction patterns. Ongoing work focuses on i) expanding the DR2 interaction assay to the 100 top co-expressed GPCRs across the 10 brain cell types with highest DRD2 expression, ii) confirm interaction using additional proximity and physical interaction based assays, and iii) determine how selected interaction partners modify downstream signaling, in-vitro and ex-vivo.