Marked changes in signal transduction upon heteromerization of dopamine D1 and histamine H3 receptors.
OBJECTIVE
Functional interactions between the G protein-coupled dopamine D1 and histamine H3 receptors have been described in the brain. In the present study we investigated the existence of D1-H3 receptor heteromers and their biochemical characteristics.


METHODS
D1-H3 receptor heteromerization was studied in mammalian transfected cells with Bioluminescence Resonance Energy Transfer and binding assays. Furthermore, signalling through mitogen-activated protein kinase (MAPK) and adenylyl cyclase pathways was studied in co-transfected cells and compared with cells transfected with either D1 or H3 receptors.


RESULTS
Bioluminescence Resonance Energy Transfer and binding assays confirmed that D1 and H3 receptors can heteromerize. Activation of histamine H3 receptors did not lead to signalling towards the MAPK pathway unless dopamine D1 receptors were co-expressed. Also, dopamine D1 receptors, usually coupled to G(s) proteins and leading to increases in cAMP, did not couple to G(s) but to G(i) in co-transfected cells. Furthermore, signalling via each receptor was blocked not only by a selective antagonist but also by an antagonist of the partner receptor.


CONCLUSIONS
D1-H3 receptor heteromers constitute unique devices that can direct dopaminergic and histaminergic signalling towards the MAPK pathway in a G(s)-independent and G(i)-dependent manner. An antagonist of one of the receptor units in the D1-H3 receptor heteromer can induce conformational changes in the other receptor unit and block specific signals originating in the heteromer. This gives rise to unsuspected therapeutic potentials for G protein-coupled receptor antagonists.
Molecular Neurobiology Unit, IDIBAPS, CIBERNED, Department of Biochemistry and Molecular Biology, School of Biology, University of Barcelona, Barcelona, Spain.
Carla
C
Ferrada
Estefanía
E
Moreno
Vicent
V
Casadó
Gerold
G
Bongers
Antoni
A
Cortés
Josefa
J
Mallol
Enric I
EI
Canela
Rob
R
Leurs
Sergi
S
Ferré
Carme
C
Lluís
Rafael
R
Franco
D002460:Cell Line; D031541:Fluorescence Resonance Energy Transfer; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D054828:Histamine H3 Antagonists / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D055503:Protein Multimerization; D011869:Radioligand Assay; D020239:Receptor Cross-Talk; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D018100:Receptors, Histamine H3 / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D014162:Transfection
D054828:Histamine H3 Antagonists; D017447:Receptors, Dopamine D1; D018100:Receptors, Histamine H3; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs