title: Regulation of human D1 dopamine receptor function and gene expression in SK-N-MC neuroblastoma cells.
abstract: SK-N-MC human neuroblastoma cells express functional D1, but not D5, dopaminergic receptors. Stimulating cells with dopamine or the D1-selective agonist, SKF R-38393, rapidly (t(1/2) = 1 h) resulted in > 95% attenuation of dopamine-mediated accumulation of cyclic AMP, without any change in D1 dopamine receptor levels. Prolonged (> 4 h) exposure of cells to dopamine attenuated D1 receptor levels to 45-50% of control (t(1/2) = 8 h) and was accompanied by a loss of high-affinity binding sites. At the molecular level, the expression of D1 receptor messenger RNA was bimodal: an initial increase (by approximately 60%) of receptor messenger RNA within 2 h of treatment of cells with dopamine was followed by a decline to 50% below control messenger RNA levels. Low concentrations (1-10 nM) of dopamine also potentiated D1 messenger RNA levels (up to 48%), resulting in a twofold increase in receptor levels. Transfection studies with the cloned human D1 promoter construct, pGL-D1P, indicated that the up-regulation of D1 messenger RNA was due to activation of promoter by dopamine. The dopamine-mediated up-regulation of both D1 receptor messenger RNA and promoter was prevented by the D1-selective antagonist, SCH 23390. The results suggest that dopamine regulates D1 receptor gene and protein expression in a bimodal manner, partly through activation of the receptor promoter. Moreover, the effects of dopamine are independent of the second messenger, cyclic AMP.
authors.affiliation: Department of Pediatrics, Georgetown University Medical Center, Georgetown University, Washington, DC 20007, USA.
authors.forename: A
authors.initials: A
authors.lastname: Sidhu
authors.forename: B
authors.initials: B
authors.lastname: Olde
authors.forename: N
authors.initials: N
authors.lastname: Humblot
authors.forename: K
authors.initials: K
authors.lastname: Kimura
authors.forename: N
authors.initials: N
authors.lastname: Gardner
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology*; D001552:Benzazepines / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D009447:Neuroblastoma; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D017447:Receptors, Dopamine D1 / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: C049558:8-iodo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol; D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D011994:Recombinant Proteins; D005576:Colforsin; D003994:Bucladesine; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine; D004298:Dopamine