Pharmacological and functional comparisons of α6/α3β2β3-nAChRs and α4β2-nAChRs heterologously expressed in the human epithelial SH-EP1 cell line. (October 2018)

• Record Type: Journal Article
• Authors: Chen, De-jie; Gao, Fen-fei; Ma, Xiao-kuang; Shi, Gang-gang; Huang, Yuan-bing; Su, Quang-xi; Sudweeks, Sterling; Gao, Ming; Dharshaun, Turner; Eaton, Jason Brek; Chang, Yong-chang; Mcintosh, J Michael; Lukas, Ronald J; Whiteaker, Paul; Steffensen, Scott C; Wu, Jie
• Is Part Of: Acta pharmacologica Sinica. Volume 39:Number 10(2018)
• Page Start: 1571
• Page End: 1581
• Publication Date: 2018-10
• Subjects: nicotinic acetylcholine receptor -- nicotine -- acetylcholine -- SH-EP1 cells -- patch-clamp; Pharmacology -- Periodicals; 615.105
• DOI: 10.1038/aps.2017.209
• Languages: English
• ISSNs: 1671-4083

Abstract

Abstract Neuronal nicotinic acetylcholine receptors containing α6 subunits (α6* -nAChRs) show highly restricted distribution in midbrain neurons associated with pleasure, reward, and mood control, suggesting an important impact of α6* -nAChRs in modulating mesolimbic functions. However, the function and pharmacology of α6* -nAChRs remain poorly understood because of the lack of selective agonists for α6* -nAChRs and the challenging heterologous expression of functional α6* -nAChRs in mammalian cell lines. In particular, the α6 subunit is commonly co-expressed with α4* -nAChRs in the midbrain, which masks α6* -nAChR (without α4) function and pharmacology. In this study, we systematically profiled the pharmacology and function of α6* -nAChRs and compared these properties with those of α4β2 nAChRs expressed in the same cell line. Heterologously expressed human α6/α3 chimeric subunits (α6 N-terminal domain joined with α3 trans-membrane domains and intracellular loops) with β2 and β3 subunits in the human SH-EP1 cell line (α6* -nAChRs) were used. Patch-clamp whole-cell recordings were performed to measure these receptor-mediated currents. Functionally, the heterologously expressed α6* -nAChRs exhibited excellent function and showed distinct nicotine-induced current responses, such as kinetics, inward rectification and recovery from desensitization, compared with α4β2-nAChRs. Pharmacologically, α6* -nAChR was highly sensitive to the α6 subunit-selective antagonist α-conotoxin MII but had lower sensitivity to mecamylamine and dihydro-β-erythroidine. Nicotine and acetylcholine were found to be full agonists for α6* -nAChRs, whereas epibatidine and cytisine were determined to be partial agonists. Heterologously expressed α6* -nAChRs exhibited pharmacology and function distinct from those of α4β2-nAChRs, suggesting that α6* -nAChRs may mediate different cholinergic signals. Our α6* -nAChR expression system can be used as an excellent cell model for future investigations of α6* -nAChR function and pharmacology.