title: Genetic variants of dopamine D2 receptor impact heterodimerization with dopamine D1 receptor.
abstract: BACKGROUND
  The human dopamine D2 receptor gene has three polymorphic variants that alter its amino acid sequence: alanine substitution by valine in position 96 (V96A), proline substitution by serine in position 310 (P310S) and serine substitution by cysteine in position 311 (S311C). Their functional role has never been the object of extensive studies, even though there is some evidence that their occurrence correlates with schizophrenia.
  
  
  METHODS
  The HEK293 cell line was transfected with dopamine D1 and D2 receptors (or genetic variants of the D2 receptor), coupled to fluorescent proteins which allowed us to measure the extent of dimerization of these receptors, using a highly advanced biophysical approach (FLIM-FRET). Additionally, Fluoro-4 AM was used to examine changes in the level of calcium release after ligand stimulation of cells expressing different combinations of dopamine receptors.
  
  
  RESULTS
  Using FLIM-FRET experiments we have shown that in HEK 293 expressing dopamine receptors, polymorphic mutations in the D2 receptor play a role in dimmer formation with the dopamine D1 receptor. The association level of dopamine receptors is affected by ligand administration, with variable effects depending on polymorphic variant of the D2 dopamine receptor. We have found that the level of heteromer formation is reflected by calcium ion release after ligand stimulation and have observed variations of this effect dependent on the polymorphic variant and the ligand.
  
  
  CONCLUSIONS
  The data presented in this paper support the hypothesis on the role of calcium signaling regulated by the D1-D2 heteromer which may be of relevance for schizophrenia etiology.
authors.affiliation: Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland. Electronic address: ewa.blasiak@uj.edu.pl.
authors.forename: Ewa
authors.initials: E
authors.lastname: Błasiak
authors.affiliation: Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland. Electronic address: sylwia.lukasiewicz@uj.edu.pl.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Łukasiewicz
authors.affiliation: Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland. Electronic address: szafran@if-pan.krakow.pl.
authors.forename: Kinga
authors.initials: K
authors.lastname: Szafran-Pilch
authors.affiliation: Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland; Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland. Electronic address: marta.dziedzicka-wasylewska@uj.edu.pl.
authors.forename: Marta
authors.initials: M
authors.lastname: Dziedzicka-Wasylewska
mesh_terms: D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000235:genetics; D002460:Cell Line; D014644:Genetic Variation / Q000235:genetics*; D057809:HEK293 Cells; D006801:Humans; D055503:Protein Multimerization / Q000235:genetics*; D017447:Receptors, Dopamine D1 / Q000235:genetics*; D017448:Receptors, Dopamine D2 / Q000172:deficiency*; D012559:Schizophrenia / Q000235:genetics
chemical_list: C583260:DRD1 protein, human; C581293:DRD2 protein, human; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D002118:Calcium
keywords: Dopamine D1 receptor; Dopamine D2 receptor; G-protein coupled receptors; Oligomerization; Polymorphism