Abstract:
α6/
α3
β2
β3 nicotinic acetylcholine receptors (nAChRs) subtype is widely expressed in mesolimbic dopaminergic pathway and other regions, which plays a vital role in modulating the release of multiple neurotransmitters and drug reward mechanisms. It has become a potential therapeutic target for the treatment of various neuropsychiatric disorders and drug addiction. However, most ligands identified with high affinity and selectivity targeting
α6/
α3
β2
β3 subtype showed limited subtype discrimination against the closely related
α3
β2 subtype. Furthermore, the molecular mechanisms underlying ligands interact with
α6/
α3
β2
β3 nAChR remain absent. In this study, the related approaches of site-directed mutagenesis of receptor,
in vitro transcription and electrophysiological assay were utilized to establish the drug screening models of wild-type
α6/
α3
β2
β3 nAChR and its
α6/
α3 subunit single-point mutants. The effects led by single amino acid substitution to the function of
α6/
α3
β2
β3 nAChR were also evaluated. The animal experimental protocol involved in this study has been approved by the Ethics Committee of Guangxi University (Approval No: GXU-2023-0249). As the results showed, the half maximal effective concentration (EC
50) for ACh activating
α6/
α3
β2
β3 nAChR was 18.5 μmol·L
-1. All 7 single-point mutations of
α6/
α3 subunit resulted in increase of the agonist sensitivity, while the EC
50 of ACh towards mutants
α6/
α3V112E
β2
β3、
α6/
α3T147S
β2
β3、
α6/
α3E152K
β2
β3 nAChR decreased to the greatest extent (EC
50s were 3.5, 4.4, and 2.0 μmol·L
-1, respectively, which were 0.1-0.2-fold relative to that of the wild-type receptor). These results established models for the research of structure-function relationship of
α6/
α3
β2
β3 nAChRs and molecular mechanism of ligand-receptor specific binding, as well as provided theoretical foundation for the design and optimization of selective drug leads targeting
α6/
α3
β2
β3 nAChRs.