Chromatin remodeller CHD7 is required for GABAergic neuron development by promoting PAQR3 expression

Mutations in the chromatin remodeller-coding gene CHD7 cause CHARGE syndrome (CS). CS features include moderate to severe neurological and behavioural problems, clinically characterized by intellectual disability, attention-deficit/hyperactivity disorder and autism spectrum disorder. To investigate the poorly characterized neurobiological role of CHD7, we here generate a zebrafish chd7^-/- model. chd7^-/- mutants have less GABAergic neurons and exhibit a hyperactivity behavioural phenotype. The GABAergic neuron defect is at least in part due to downregulation of the CHD7 direct target gene paqr3b, and subsequent upregulation of MAPK/ERK signalling, which is also dysregulated in CHD7 mutant human cells. Through a phenotype-based screen in chd7^-/- zebrafish and Caenorhabditis elegans, we show that the small molecule ephedrine restores normal levels of MAPK/ERK signalling and improves both GABAergic defects and behavioural anomalies. We conclude that chd7 promotes paqr3b expression and that this is required for normal GABAergic network development. This work provides insight into the neuropathogenesis associated with CHD7 deficiency and identifies a promising compound for further preclinical studies.