Characterization of the human dopamine D3 receptor expressed in transfected cell lines.
A full-length cDNA clone of the human dopamine D3 receptor was obtained by the polymerase chain reaction (PCR) using reverse-transcribed RNA from human brain as the template. The cDNA was inserted into an expression vector which was then stably transfected into either Chinese hamster ovary (CHO), SK-N-MC human epithelioma or mouse CCL1.3 fibroblast cell lines. Post-transfection, the Bmax for D3 receptor expression was 1.9, 1.1 and 0.4 pmol/mg protein in the CHO-K1, SK-N-MC and CCL1.3 cell lines, respectively. The D3 receptor expressed in CHO-K1 and CCL1.3 cells exhibited similar radioligand binding profiles, especially for the D3-selective compound, 7-hydroxy-2-(di-n-propylamino)tetralin (7-OH-DPAT). Radioligand-binding competition curves of presumed D3 agonists were shifted to the right by the addition of guanine nucleotides and Na+ to the assay buffer. Presumed D3-receptor agonists had no effect on cAMP accumulation in any of the D3-transfected cell lines although cAMP accumulation was inhibited by dopamine D2 receptor activation in D2-transfected CHO and CCL1.3 cells and by activation of the exogenously expressed neuropeptide Y receptor in SK-N-MC cells. Also, D3 receptor activation neither potentiated ATP-stimulated arachidonic acid release from CHO cells nor stimulated inositol phosphate production in CCL1.3-cells although both of these responses were elicited by D2 agonists in D2-transfected cells. We conclude that the signalling properties of the D3 receptor differ from those of its closest homolog, the D2 receptor.
MacKenzie
R G
RG
Parke-Davis, Department of Pharmacology, Ann Arbor, MI 48106.
VanLeeuwen
D
D
Pugsley
T A
TA
Shih
Y H
YH
Demattos
S
S
Tang
L
L
Todd
R D
RD
O'Malley
K L
KL
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001667:Binding, Competitive; D016466:CHO Cells; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism*; D015259:Dopamine Agents / Q000378:metabolism / Q000494:pharmacology*; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism*; D051379:Mice; D011869:Radioligand Assay; D011954:Receptors, Dopamine / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes / Q000378:metabolism; D014162:Transfection
C493593:DRD3 protein, human; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; C493594:Drd3 protein, mouse; D007295:Inositol Phosphates; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes; D016718:Arachidonic Acid; D000242:Cyclic AMP; C031349:7-hydroxy-2-N,N-dipropylaminotetralin