24.1 HIGH-THROUGHPUT FUNCTIONAL ANALYSIS OF RISK GENES OF AUTISM SPECTRUM DISORDER IN ZEBRAFISH

Abstract

Advances in whole-exome sequencing have led to the identification of a growing number of high-confidence risk genes in autism spectrum disorder (ASD). However, our understanding of the mechanisms by which gene disruption leads to alterations in specific cell types and neural circuits predisposing to behavioral dysfunction, remains limited. The objective of this research is to investigate the extent to which ASD risk genes might converge on common pathways in the developing vertebrate brain as a path toward identifying potential pharmacological targets. We leveraged the advantages of zebrafish to perform high-throughput functional assays of multiple ASD risk genes. Using CRISPR/Cas9, we generated zebrafish mutants lacking the function of 10 high-confidence ASD risk genes. We performed large-scale pharmaco-behavioral profiling assays and targeted drug screens. To identify how gene disruption leads to alterations in brain signaling, we performed whole-brain activity mapping, which allows for the identification of regional differences in baseline brain activity. Using a quantitative behavioral profiling approach, we characterized the behavioral “fingerprints” of 10 zebrafish ASD risk gene mutants. We identified points of convergence and divergence across mutant behavioral profiles of the following risk genes: CHD8, CNTNAP2, CUL3, DYRK1A, GRIN2B, KATNAL2, KDM5B, POGZ, SCN2A, and TBR1. In addition, we screened 775 FDA-approved drugs in wild-type fish and used these behavioral profiles to predict potential suppressors of the mutant behavioral phenotypes. Using pharmaco-behavioral profiling, we previously showed that estrogenic compounds selectively rescue the behavioral phenotype of zebrafish mutants of the ASD and epilepsy-associated gene, CNTNAP2. In addition, using whole-brain activity mapping, we identified differences in baseline brain activity in zebrafish ASD risk gene mutants. These studies highlight the potential of high-throughput functional screens in zebrafish to identify potential points of convergence across ASD risk genes.