Metabotropic glutamate type 5, dopamine D₂ and adenosine A₂a receptors form higher-order oligomers in living cells

• Published in: Journal of neurochemistry 2009-06, Vol.109 (5), p.1497-1507
• Main Authors: Cabello, Nuria, Gandía, Jorge, Bertarelli, Daniela C.G, Watanabe, Masahiko, Lluís, Carme, Franco, Rafael, Ferré, Sergi, Luján, Rafael, Ciruela, Francisco
• Format: Article
• Language: English
• Subjects: adenosine; Animals; Bacterial Proteins; Biochemistry; Biological and medical sciences; Bioluminescence; Cell Line, Transformed - metabolism; Cell Line, Transformed - ultrastructure; Cell receptors; Cell structures and functions; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Corpus Striatum - cytology; Dimerization; dopamine; Fluorescence Resonance Energy Transfer - methods; Fundamental and applied biological sciences. Psychology; G protein-coupled receptors; glutamate; Humans; Immunoprecipitation; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Microscopy, Electron, Transmission - methods; Models, Molecular; Molecular and cellular biology; Monoamines receptors (catecholamine, serotonine, histamine, acetylcholine); Neurology; Neurotransmitters; Rats; receptor oligomerization; Receptor, Adenosine A2A - chemistry; Receptor, Adenosine A2A - genetics; Receptor, Adenosine A2A - metabolism; Receptor, Adenosine A2A - ultrastructure; Receptor, Metabotropic Glutamate 5; Receptors, Dopamine D2 - chemistry; Receptors, Dopamine D2 - genetics; Receptors, Dopamine D2 - metabolism; Receptors, Dopamine D2 - ultrastructure; Receptors, Metabotropic Glutamate - chemistry; Receptors, Metabotropic Glutamate - genetics; Receptors, Metabotropic Glutamate - metabolism; Receptors, Metabotropic Glutamate - ultrastructure; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Scientific imaging; Transfection; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2009.06078.x

G protein-coupled receptors are known to form homo- and heteromers at the plasma membrane, but the stoichiometry of these receptor oligomers are relatively unknown. Here, by using bimolecular fluorescence complementation, we visualized for the first time the occurrence of heterodimers of metabotropic glutamate mGlu₅ receptors (mGlu₅R) and dopamine D₂ receptors (D₂R) in living cells. Furthermore, the combination of bimolecular fluorescence complementation and bioluminescence resonance energy transfer techniques, as well as the sequential resonance energy transfer technique, allowed us to detect the occurrence receptor oligomers containing more than two protomers, mGlu₅R, D₂R and adenosine A₂A receptor (A₂AR). Interestingly, by using high-resolution immunoelectron microscopy we could confirm that the three receptors co-distribute within the extrasynaptic plasma membrane of the same dendritic spines of asymmetrical, putative glutamatergic, striatal synapses. Also, co-immunoprecipitation experiments in native tissue demonstrated the existence of an association of mGlu₅R, D₂R and A₂AR in rat striatum homogenates. Overall, these results provide new insights into the molecular composition of G protein-coupled receptor oligomers in general and the mGlu₅R/D₂R/A₂AR oligomer in particular, a receptor oligomer that might constitute an important target for the treatment of some neuropsychiatric disorders.