Rapid Assessment of the Temporal Function and Phenotypic Reversibility of Neurodevelopmental Disorder Risk Genes in C. elegans

Hundreds of genes have been implicated in neurodevelopmental disorders. Previous studies have indicated that some phenotypes caused by decreased developmental function of select risk genes can be reversed by restoring gene function in adulthood. However, very few risk genes have been assessed for adult reversibility. We developed a strategy to rapidly assess the temporal requirements and phenotypic reversibility of neurodevelopmental disorder risk gene orthologs using a conditional protein degradation system and machine vision phenotypic profiling in Caenorhabditis elegans. Using this approach, we measured the effects of degrading and re- expressing orthologs of 3 neurodevelopmental risk genes EBF3, BRN3A, and DYNC1H1 across 30 morphological, locomotor, sensory, and learning phenotypes at multiple timepoints throughout development. We found some degree of phenotypic reversibility was possible for each gene studied. However, the temporal requirements of gene function and degree of phenotypic reversibility varied by gene and phenotype. The data reflects the dynamic nature of gene function and the importance of using multiple time windows of degradation and re-expression to understand the many roles a gene can play over developmental time. This work also demonstrates a strategy of using a high-throughput model system to investigate temporal requirements of gene function across a large number of phenotypes to rapidly prioritize neurodevelopmental disorder genes for re-expression studies in other organisms. SUMMARY STATEMENTWe developed a strategy that combines a conditional and reversible protein degradation system with our high-throughput machine vision tracking system to assess the temporal windows of gene function and reversibility of phenotypic disruptions associated with neurodevelopmental disorder risk gene orthologs using C. elegans. Using this approach, we assessed 3 genes (unc- 3, unc-86, and dhc-1) and found that post-embryonic rescue was possible for each gene and each phenotypic feature class assessed. Re-activation of certain genes was able to reverse multiple phenotypic disruptions late into development without inducing novel phenotypes, prioritizing them for further study.