Beta 1/beta 2-adrenergic receptor heterodimerization regulates beta 2-adrenergic receptor internalization and ERK signaling efficacy.
Beta(1)- and beta(2)-adrenergic receptors (beta(1)AR and beta(2)AR) are co-expressed in numerous tissues where they play a central role in the responses of various organs to sympathetic stimulation. Although the two receptor subtypes share some signaling pathways, each has been shown to have specific signaling and regulatory properties. Given the recent recognition that many G protein-coupled receptors can form homo- and heterodimers, the present study was undertaken to determine whether the beta(1)AR and beta(2)AR can form dimers in cells and, if so, to investigate the potential functional consequences of such heterodimerization. Using co-immunoprecipitation and bioluminescence resonance energy transfer, we show that beta(1)AR and beta(2)AR can form heterodimers in HEK 293 cells co-expressing the two receptors. Functionally, beta-adrenergic stimulated adenylyl cyclase activity was found to be identical in cells expressing beta(1)AR, beta(2)AR, or both receptors at similar levels, indicating that heterodimerization did not affect this signaling pathway. When considering ERK1/2 MAPK activity, a significant agonist-promoted activation was detected in beta(2)AR- but not beta(1)AR-expressing cells. Similarly to what was observed in cells expressing the beta(1)AR alone, no beta-adrenergic stimulated ERK1/2 phosphorylation was observed in cells co-expressing the two receptors. A similar inhibition of agonist-promoted internalization of the beta(2)AR was observed upon co-expression of the beta(1)AR, which by itself internalized to a lesser extent. Taken together, our data suggest that heterodimerization between beta(1)AR and beta(2)AR inhibits the agonist-promoted internalization of the beta(2)AR and its ability to activate the ERK1/2 MAPK signaling pathway.
Lavoie
Catherine
C
Centre de Recherche, Institut de Cardiologie de Montréal, Montréal, Québec, H1T 1C8, Canada.
Mercier
Jean-Francois
JF
Salahpour
Ali
A
Umapathy
Dhiviya
D
Breit
Andreas
A
Villeneuve
Louis-Robert
LR
Zhu
Wei-Zhong
WZ
Xiao
Rui-Ping
RP
Lakatta
Edward G
EG
Bouvier
Michel
M
Hébert
Terence E
TE
D002460:Cell Line; D019281:Dimerization; D004705:Endocytosis; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D018342:Receptors, Adrenergic, beta-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D011993:Recombinant Fusion Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases