Human Amyotrophic Lateral Sclerosis Excitability Phenotype Screen: Target Discovery and Validation

Drug development is hampered by poor target selection. Phenotypic screens using cells differentiated from patient stem cells offer the possibility to validate known and discover novel disease targets in an unbiased fashion. To identify targets for managing hyperexcitability, a pathological feature of amyotrophic lateral sclerosis (ALS), we designed a multi-step screening funnel using patient-derived motor neurons. High content live cell imaging was used to evaluate neuronal excitability, and from a chemogenomic library of 2899 target-annotated compounds, 67 reduced hyperexcitability of ALS motor neurons carrying the SOD1(A4V) mutation, without cytotoxicity. Bioinformatic deconvolution identified thirteen targets that modulate motor neuron excitability, including two known ALS excitability modulators; AMPA receptors and Kv7.2/3 ion channels, constituting target validation. We also identified D2 dopamine receptors as contributing to ALS motor neuron excitability, a novel discovery. This screen demonstrates the power of human disease cell based phenotypic screens for identifying clinically relevant targets for neurological disorders.