title: Role of silent polymorphisms within the dopamine D1 receptor associated with schizophrenia on D1-D2 receptor hetero-dimerization.
abstract: Within the coding region of the dopamine D(1) receptor (D(1)R), two synonymous polymorphisms, D(1)R(G198A) and D(1)R(G1263), have been identified and postulated to correlate with the schizophrenia phenotype. Binding studies revealed that the density of these genetic variants was much lower than the density of wild type D(1)R in the human embryonic kidney (HEK) 293 cell line, used as a model system. From the data obtained using MFOLD software it is apparent that the G198A mutation has a greater impact on the secondary structure of the mRNA, which may affect its translation. However, the G1263A mutation is localized within the serine 421 codon of D(1)R, which is predicted to be a potential site of phosphorylation according to the PHOSIDA database. In order to determine whether the studied synonymous polymorphisms influence the process of dopamine D(1)-D(2) receptors heterodimerization, we employed fluorescence resonance energy transfer (FRET) technology. The dopamine D(2) receptor (D(2)R) was tagged with cyan fluorescence protein and the D(1)R and its genetic variants were tagged with yellow fluorescence protein. The degree of D(1)-D(2) receptor hetero-dimerization was significantly decreased when genetic variants of D(1)R were co-expressed with D(2)R. Since the D(1)R mutations affected the expression levels of the proteins in the cell membrane without affecting the cellular localization of the receptor proteins, we postulated that the D(1)R polymorphisms altered the translation rate and protein structure of the receptor. The altered hetero-dimerization that likely results from the lower expression of these genetic variants of D(1)R with D(2)R may be partially responsible for the association of both G198A and G1263A polymorphisms with the schizophrenia phenotype.
authors.affiliation: Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, PL 30-387 Kraków, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Grymek
authors.forename: Sylwia
authors.initials: S
authors.lastname: Łukasiewicz
authors.forename: Agata
authors.initials: A
authors.lastname: Faron-Góreckaa
authors.forename: Magdalena
authors.initials: M
authors.lastname: Tworzydlo
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Polit
authors.forename: Marta
authors.initials: M
authors.lastname: Dziedzicka-Wasylewska
mesh_terms: D002460:Cell Line; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D005456:Fluorescent Dyes / Q000737:chemistry; D014644:Genetic Variation; D006801:Humans; D007668:Kidney / Q000166:cytology; D009154:Mutation; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D055503:Protein Multimerization; D012333:RNA, Messenger / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000235:genetics* / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000235:genetics* / Q000378:metabolism; D012559:Schizophrenia / Q000235:genetics*; D012984:Software
chemical_list: D005456:Fluorescent Dyes; D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2