CRISPR/Cas9 Induced shank3 Zebrafish Mutants Display Autism-like Behaviors
Human genetics and genomics studies have supported a strong causal role of SHANK3 deficiency in autism spectrum disorder (ASD). The molecular mechanism underlying SHANK3 deficiency causing ASD is not fully understood. Recently, zebrafish become a popular organism to model ASD because of its high efficiency of genetic manipulation and robust behavioral phenotypes. However, a stable ASD zebrafish mutant model for shank3 has not been reported. Human SHANK3 is duplicated in zebrafish genome and has two homologs: shank3a and shank3b. Previous studies have reported shank3 morphants in zebrafish using morphlino method. Here we report generation using CRISPR/Cas9 genome editing technique and characterization of shank3 mutant zebrafish at larva and adult age.
We used CRISPR/Cas9 to generate a shank3 loss-of-function mutant (shank3a-/-, shank3b-/- and shank3a&b-/-) in zebrafish. A series of morphological measurements, behavioral tests and molecular analyses were performed to systematically characterize the behavioral and molecular changes in shank3 mutant zebrafish.
shank3a-/-, shank3b-/- and shank3a&b-/- zebrafish exhibited abnormal morphology at early developmental stage. They displayed reduced locomotor activity both at larva and adult age. They also showed multiple autism-like behaviors in adulthood, including reduced social interaction, reduced time spent near conspecifics, loose schools and significant repetitive behaviors. Additionally, the levels of both postsynaptic homer1 and presynaptic synaptophysin were significantly reduced in the adult brains of shank3 deficient zebrafish.
We generated the first inheritable shank3 mutant zebrafish model (shank3a-/-, shank3b-/- and shank3a&b-/-) using CRISPR/Cas9 gene editing approach. All shank3 mutant zebrafish displayed robust autism-like behaviors and altered synaptic proteins of homer1 and synaptophysin. The versatility of zebrafish as a model of studying neurodevelopment and conducting drug screen will likely have a significant contribution to future studies of examining human SHANK3 function and ASD.