Optogenetic and High-Throughput Drug Discovery

Optogenetics, a technique based on natural or genetically engineered light-sensitive proteins, combines genetic manipulation and optics offering unprecedented and reversible opportunities for controlling cell functions by light with a millisecond-scale temporal resolution, allowing the user to keep up with fast biological information. Optogenetics, applied to cell-based high-throughput screening (HTS) assays in the early stages of drug discovery, typically involves the generation of a recipient cell line stably expressing an optogenetic actuator (a light-sensitive ion channel, pump, or enzyme) together with the target of interest. The light-driven modulation of the target achieved triggers a biological response that can be followed by standard optical readouts and is easily detectable by HTS-compatible platforms. Herein we describe how a series of HTS-compatible platform working cellular assays applying optogenetics techniques was established at Axxam, including examples of fluorescence plate reader assays with improved control of cellular excitability over time. Moreover, we show how electrophysiology can be used to validate the optogenetics-induced mechanism of action of a cell line, validating the assay principle and mode of action before its final application in an HTS-compatible format. We also show how optogenetic vectors can be easily inserted into induced pluripotent stem-derived cells (iPSCs) to achieve fast control of specific cell events and develop relevant assays in a miniaturized format for drug discovery screening campaigns. Finally, we discuss how image-based optical approaches have also been shown to be more relevant for validating cellular signals when combined with fine-tuned optogenetic stimulation.