Maternal Rest/Nrsf Regulates Zebrafish Behavior through snap25a/b

During embryonic development, regulation of gene expression is key to creating the many subtypes of cells that an organism needs throughout its lifetime. Recent work has shown that maternal genetics and environmental factors have lifelong consequences on diverse processes ranging from immune function to stress responses. The RE1-silencing transcription factor (Rest) is a transcriptional repressor that interacts with chromatin-modifying complexes to repress transcription of neural-specific genes during early development. Here we show that in zebrafish, maternally supplied rest regulates expression of target genes during larval development and has lifelong impacts on behavior. Larvae deprived of maternal rest are hyperactive and show atypical spatial preferences. Adult male fish deprived of maternal rest present with atypical spatial preferences in a novel environment assay. Transcriptome sequencing revealed 158 genes that are repressed by maternal rest in blastula stage embryos. Furthermore, we found that maternal rest is required for target gene repression until at least 6 dpf. Importantly, disruption of the RE1 sites in either snap25a or snap25b resulted in behaviors that recapitulate the hyperactivity phenotype caused by absence of maternal rest Both maternal rest mutants and snap25a RE1 site mutants have altered primary motor neuron architecture that may account for the enhanced locomotor activity. These results demonstrate that maternal rest represses snap25a/b to modulate larval behavior and that early Rest activity has lifelong behavioral impacts.

Maternal factors deposited in the oocyte have well-established roles during embryonic development. We show that, in zebrafish, maternal rest (RE1-silencing transcription factor) regulates expression of target genes during larval development and has lifelong impacts on behavior. The Rest transcriptional repressor interacts with chromatin-modifying complexes to limit transcription of neural genes. We identify several synaptic genes that are repressed by maternal Rest and demonstrate that snap25a/b are key targets of maternal rest that modulate larval locomotor activity. These results reveal that zygotic rest is unable to compensate for deficits in maternally supplied rest and uncovers novel temporal requirements for Rest activity, which has implications for the broad roles of Rest-mediated repression during neural development and in disease states.