
Development of a QPatch-Automated Electrophysiology Assay for Identifying TMEM16A Small-Molecule Inhibitors
Author(s) -
Kathryn Henckels,
David Fong,
Jonathan E. Phillips
Publication year - 2020
Publication title -
assay and drug development technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.402
H-Index - 56
eISSN - 1557-8127
pISSN - 1540-658X
DOI - 10.1089/adt.2019.962
Subject(s) - electrophysiology , patch clamp , small molecule , bronchoconstriction , chemistry , safety pharmacology , pharmacology , drug development , biophysics , drug discovery , drug , biology , neuroscience , biochemistry , medicine , anesthesia , airway
The calcium-activated chloride channel, TMEM16A, is involved in airway hydration and bronchoconstriction and is a promising target for respiratory disease. Drug development efforts around channels require an electrophysiology-based assay for identifying inhibitors or activators. TMEM16A has proven to be a difficult channel to record on automated electrophysiology platforms due to its propensity for rundown. We developed an automated, whole-cell, electrophysiology assay on the QPatch-48 to evaluate small-molecule inhibitors of TMEM16A. In this assay, currents remained stable for a duration of roughly 11 min, allowing for the cumulative addition of five concentrations of compounds and resulted in reproducible IC 50 s. The absence of rundown was likely due to a low internal free-calcium level of 250 nM, which was high enough to produce large currents, but also maintained the voltage dependence of the channel. Current amplitude averaged 6 nA using the single-hole QPlate and the channel maintained outward rectification throughout the recording. Known TMEM16A inhibitors were tested and their IC 50 s aligned with those reported in the literature using manual patch-clamp. Once established, this assay was used to validate novel TMEM16A inhibitors that were identified in our high-throughput fluorescent-based assay, as well as to assist in structure-activity relationship efforts by the chemists. Overall, we demonstrate an easy to operate, reproducible, automated electrophysiology assay using the QPatch-48 for TMEM16A drug development efforts.