title: Influence of the antipsychotic drug pipamperone on the expression of the dopamine D4 receptor.
abstract: The dopamine D4 receptor is a G protein-coupled receptor that binds with high affinity various antipsychotics. The receptor may be involved in attention/cognition, and in genetic studies a polymorphic repeat sequence in its coding sequence has been associated with attention deficit/hyperactivity disorder. We developed an inducible episomal expression system based on the reverse tetracycline transactivator and Epstein-Barr viral sequences. In HEK293rtTA cells expressing the dopamine D4 receptor from this episomal expression vector, addition of doxycycline in combination with sodium butyrate and trichostatin A induces high levels of receptor expression, resulting in 1970 +/- 20 fmol/mg membrane protein. Addition of the dopamine D4 receptor and serotonin 5-HT2A receptor antagonist pipamperone to these cells further increased the expression of the dopamine receptor, reaching 3800 +/- 60 fmol/mg membrane protein. This up-regulation was not restricted to the dopamine D4 receptor but was also found for the serotonin 5-HT2A receptor. We further provide evidence that the increase in receptor expression is not due to increased mRNA synthesis. As pipamperone could rescue the expression of a folding mutant of the dopamine D4 receptor (M345), we propose that pipamperone acts as a pharmacological chaperone for correct receptor folding thereby resulting in an increased dopamine D4 receptor expression. This study describes a strong and inducible expression system for proteins, difficult to express in other heterologous expression systems. This study also demonstrates that pipamperone, an antipsychotic, acts as a pharmacological chaperone and by doing so, increases the expression level of the dopamine D4 receptor. The fact that ligands can also act as pharmacological chaperones is a fairly new additional element in the regulation of receptor expression levels with potential great impact in drug treatment.
authors.affiliation: Laboratory for Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Molecular Biology, Ghent University - UGent, K.L. Ledeganckstraat 35, 9000 Gent, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Van Craenenbroeck
authors.forename: Evelien
authors.initials: E
authors.lastname: Gellynck
authors.forename: Béatrice
authors.initials: B
authors.lastname: Lintermans
authors.forename: Josée E
authors.initials: JE
authors.lastname: Leysen
authors.forename: Hubert H M
authors.initials: HH
authors.lastname: Van Tol
authors.forename: Guy
authors.initials: G
authors.lastname: Haegeman
authors.forename: Peter
authors.initials: P
authors.lastname: Vanhoenacker
mesh_terms: D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology*; D002090:Butyrophenones / Q000494:pharmacology*; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D006801:Humans; D051379:Mice; D018832:Molecular Chaperones / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D044402:Receptor, Serotonin, 5-HT2A / Q000032:analysis / Q000187:drug effects / Q000235:genetics; D017448:Receptors, Dopamine D2 / Q000032:analysis / Q000187:drug effects* / Q000235:genetics
chemical_list: D014150:Antipsychotic Agents; D002090:Butyrophenones; D018832:Molecular Chaperones; D012333:RNA, Messenger; D044402:Receptor, Serotonin, 5-HT2A; D017448:Receptors, Dopamine D2; C005569:pipamperone