Objective

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease in which 20% of familial cases are caused by mutations in the superoxide dismutase 1 (SOD1) gene. There is a well-established link between mutant SOD1 expression levels and disease pathology. Accordingly, small molecules reducing SOD1 transcription have potential to be of therapeutic benefit in ALS. A novel cell based assay was developed using HEK293 cells expressing 1) a luciferase based SOD1 promoter reporter gene and 2) a CMV promoter-driven full length SOD1 gene fused to GFP. The second construct was required because SOD1 reduction in certain cell lines can cause cell senescence or cell death. This circumvented ‘hit’ compounds interfering with cell growth and potentially being falsely excluded for toxicity, something problematic in previous SOD1 reporter gene screens. A 384-well assay was optimised to identify inhibitors of the SOD1 promoter and 10k novel compounds initially screened. Good screening statistics were observed and structural analysis allowed hit expansion of lead compounds using the full LifeArc collection. Quantitative PCR assays were designed to measure endogenous SOD1 in the neuronal SH-SY5Y cell line and a significant reduction of SOD1 expression was observed by a subset of compounds. Thus, further validating the use of this assay to identify SOD1 transcription inhibitors.