Cell-Based Potassium Ion Channel Screening Using the FluxOR™ Assay

• Published in: Journal of biomolecular screening Vol. 15; no. 4; pp. 441 - 446
• Main Authors: Beacham, Daniel W., Blackmer, Trillium, O’ Grady, Michael, Hanson, George T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2010
• Subjects: BacMam; Biological Assay - methods; Cell Line, Tumor; Cyclic Nucleotide-Gated Cation Channels - metabolism; Dose-Response Relationship, Drug; Fluorescent Dyes - metabolism; flux; FluxOR; high-throughput screening; Humans; Inhibitory Concentration 50; Potassium Channels - analysis; Potassium Channels, Inwardly Rectifying - metabolism; potassium ion channel; Small Molecule Libraries - pharmacology; Transduction, Genetic; FluxOR; potassium ion channel; BacMam; flux; high-throughput screening
• ISSN: 2472-5552; 2472-5560; 1552-454X
• DOI: 10.1177/1087057109359807

FluxOR™ technology is a cell-based assay used for high-throughput screening measurements of potassium channel activity. Using thallium influx as a surrogate indicator of potassium ion channel activity, the FluxOR™ Potassium Ion Channel Assay is based on the activation of a novel fluorescent dye. This indicator reports channel activity with a large fluorogenic response and is proportional to the number of open potassium channels on the cell, making it extremely useful for studying K+ channel targets. In contrast to BTC-AM ester, FluxOR™ dye is roughly 10-fold more thallium sensitive, requiring much lower thallium for a larger signal window. This also means that the assay is carried out in a physiological, normal-chloride saline. In this article, the authors describe how they used BacMam gene delivery to express Kv7.2 and 7.3 (KCNQ), Kir2.1, or Kv11.1 (hERG) potassium ion channels in U2-OS cells. Using these cells, they ran the FluxOR™ assay to identify and characterize channel-specific inhibitory compounds discovered within the library (Tocriscreen™ Mini 1200 and Sigma Sodium/Potassium Modulators Ligand set). The FluxOR™ assay was able to identify several known specific inhibitors of Kv7.2/7.3 or hERG, highlighting its potential to identify novel and more efficacious small-molecule modulators.