The human D2 dopamine receptor synergizes with the A2A adenosine receptor to stimulate adenylyl cyclase in PC12 cells.
The adenosine A(2A) receptor and the dopamine D(2) receptor are prototypically coupled to G(s) and G(i)/G(o), respectively. In striatal intermediate spiny neurons, these receptors are colocalized in dendritic spines and act as mutual antagonists. This antagonism has been proposed to occur at the level of the receptors or of receptor-G protein coupling. We tested this model in PC12 cells which endogenously express A(2A) receptors. The human D(2) receptor was introduced into PC12 cells by stable transfection. A(2A)-agonist-mediated inhibition of D(2) agonist binding was absent in PC12 cell membranes but present in HEK293 cells transfected as a control. However, in the resulting PC12 cell lines, the action of the D(2) agonist quinpirole depended on the expression level of the D(2) receptor: at low and high receptor levels, the A(2A)-agonist-induced elevation of cAMP was enhanced and inhibited, respectively. Forskolin-stimulated cAMP formation was invariably inhibited by quinpirole. The effects of quinpirole were abolished by pretreatment with pertussis toxin. A(2A)-receptor-mediated cAMP formation was inhibited by other G(i)/G(o)-coupled receptors that were either endogenously present (P(2y12)-like receptor for ADP) or stably expressed after transfection (A(1) adenosine, metabotropic glutamate receptor-7A). Similarly, voltage activated Ca(2+) channels were inhibited by the endogenous P(2Y) receptor and by the heterologously expressed A(1) receptor but not by the D(2) receptor. These data indicate functional segregation of signaling components. Our observations are thus compatible with the proposed model that D(2) and A(2A) receptors are closely associated, but they highlight the fact that this interaction can also support synergism.
Kudlacek
Oliver
O
Institute of Pharmacology, University of Vienna, A-1090 Wien, Austria.
Just
Herwig
H
Korkhov
Vladimir M
VM
Vartian
Nina
N
Klinger
Markus
M
Pankevych
Halyna
H
Yang
Qiong
Q
Nanoff
Christian
C
Freissmuth
Michael
M
Boehm
Stefan
S
D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology; D000225:Adenine / Q000493:pharmacokinetics; D000241:Adenosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D000243:Adenosine Deaminase / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001549:Benzamides / Q000493:pharmacokinetics; D001667:Binding, Competitive; D002453:Cell Cycle / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D051338:Cofilin 1; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D003598:Cytoskeletal Proteins; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000493:pharmacokinetics; D065127:Dopamine D2 Receptor Antagonists; D004789:Enzyme Activation; D015870:Gene Expression; D018698:Glutamic Acid / Q000494:pharmacology; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D016716:PC12 Cells; D018408:Patch-Clamp Techniques / Q000379:methods; D037342:Pertussis Toxin / Q000494:pharmacology; D010627:Phenethylamines / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010750:Phosphoproteins / Q000494:pharmacology; D011422:Propionates / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D011759:Pyrrolidines / Q000493:pharmacokinetics; D019257:Quinpirole / Q000494:pharmacology; D011869:Radioligand Assay / Q000379:methods; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000502:physiology*; D018047:Receptors, Purinergic P1 / Q000235:genetics / Q000502:physiology*; D013873:Thionucleotides / Q000494:pharmacology; D014162:Transfection; D014227:Triazines / Q000493:pharmacokinetics; D014230:Triazoles / Q000493:pharmacokinetics; D029867:Xenopus Proteins
C114785:2-amino-4-phosphono-propinate; D001549:Benzamides; D051338:Cofilin 1; D003598:Cytoskeletal Proteins; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D010627:Phenethylamines; D010726:Phosphodiesterase Inhibitors; D010750:Phosphoproteins; D011422:Propionates; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; D018047:Receptors, Purinergic P1; D013873:Thionucleotides; D014227:Triazines; D014230:Triazoles; C098933:XAC1 protein, Xenopus; D029867:Xenopus Proteins; C097270:ZM 241385; C063525:epidepride; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D005576:Colforsin; D019257:Quinpirole; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; C030812:adenosine 5'-O-(2-thiodiphosphate); D018698:Glutamic Acid; C048599:N(6)-cyclopentyladenosine; D000244:Adenosine Diphosphate; D000242:Cyclic AMP; D037342:Pertussis Toxin; D000243:Adenosine Deaminase; D000262:Adenylyl Cyclases; D000225:Adenine; D000241:Adenosine