title: Multi-modal regulation of endogenous D1 dopamine receptor expression and function in the CAD catecholaminergic cell line.
abstract: Dopamine receptors exhibit tissue- and cell type-specific expression that is modulated during development, aging and in diseases such as Parkinson's. The molecular mechanisms regulating expression of dopamine receptors are not well understood, in part due to the lack of a model cell line that not only expresses endogenous dopamine receptors but also has the requisite regulatory mechanisms. Here, we demonstrate that the CAD catecholaminergic cell line expresses D1, D2, D3 and D5 dopamine receptor subtypes and associated signaling proteins. CAD cell differentiation induced by serum withdrawal increases the levels of D1 receptor mRNA by transcriptional up-regulation. This increase is also mimicked by the neurotrophin NT3. Interestingly, the increase of D1 receptor mRNA does not result in increased levels of D1 receptor protein in differentiated CAD cells. Furthermore, while the D1 receptor protein is expressed in differentiated CAD cells, it loses its ability to activate adenylyl cyclase. We demonstrate that the post-transcriptional regulation is not due to decreased D1 receptor mRNA stability or generation of a truncated D1 receptor mRNA, and that the down-regulation of D1 receptor function in differentiated CAD cells is mediated by post-translational mechanisms that decrease cell surface receptor expression by altering receptor processing and trafficking.
authors.affiliation: Department of Pharmacology and Physiology, UMDNJ-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA.
authors.forename: Jennifer B
authors.initials: JB
authors.lastname: Pasuit
authors.forename: Zhuting
authors.initials: Z
authors.lastname: Li
authors.forename: Eldo V
authors.initials: EV
authors.lastname: Kuzhikandathil
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002395:Catecholamines / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020933:Neurotrophin 3 / Q000494:pharmacology; D023282:Nuclease Protection Assays; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000235:genetics* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation
chemical_list: D002395:Catecholamines; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D020933:Neurotrophin 3; D020033:Protein Isoforms; D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases