Characterization of the rapidly-desensitizing α7 nicotinic acetylcholine receptor using the Qube

Alpha7 nicotinic acetylcholine receptor (α7 nAChR) is an integral part of the excitatory cholinergic receptors and serves as a primary immune response and highly expressed in the nervous system. Moreover, the ion channel has a direct link to schizophrenia and Alzheimer’s disease including several other classes of neurological ailments such as cognitive and memory impairment, therefore, making α7 a critical target of ion channel drug discovery. Several different subunits and combinations can comprise the pentameric ligand-gated ion channel. In the case of α7, five identical α7 homomeric subunits form a functional channel comprised of an extracellular ligand-binding domain, a transmembrane domain, containing the ion gate and the pore, and an intracellular regulatory domain. Binding of a single ligand is enough to activate the channel. α7 contain three major conformational states: closed (C), open (O), and desensitized (D). In the open state, the channel conducts Na+, K+, and Ca2+ ions with Ca2+ displaying highest permeability. The rapid agonist-induced channel activation and desensitization make α7 a challenging target to study, where the data are only limited by the temporal resolution of the protocol used to measure current. We tested the feasibility of the Sophion high-throughput screening (HTS) 384-well Qube in reliably recording α7 nAChR recombinantly expressed in HEK293 cells. Our results demonstrated the reliability of our automated patch-clamp (APC) system in studying the α7 nicotinic acetylcholine receptor with the use of Sophion microfluidics and custom-built fast-stacked predetermined wash protocols.