Developmental deficits, synapse and dendritic abnormalities in a Clcn4 KO autism mice model : Endophenotypic target for ASD

Abstract

Chloride voltage-gated channel-4 (Clcn4) deletion is associated with autism spectrum disorder (ASD) in humans. Previous studies reported that Clcn4 knockout (KO) mice do not exhibit neurological alterations in the brain. In the present study, Clcn 4 KO C57BL/6 mice was assessed using three chamber test and marble burying test at 7 to 8 weeks of age, KO mice showed reduction in social interaction and an increase in repetitive behavior mimicking ASD. RNA expression analysis from Clcn4 knockdown mice neural progenitor cells (NPCs) showed significant decreases in genes related to neuronal projection and synapse development, suggesting aberrance in the early stage of neuronal differentiation from NPCs. In primary cortical neurons, the cell viability, the length of dendritic branches, the number of MAP2 positive cells and the phosphorylation levels of Synapsin 1 and PSD95 were decreased in Clcn4 KO mice compared to wild-type mice, all of which were reversed by Risperidone. In the prefrontal cortex of Clcn4 KO mouse, the phosphorylation levels of Synapsin 1, ERK, CREB and PSD 95 were decreased. Risperidone treatment for 2 weeks in Clcn4 KO mouse at 5 weeks of age, reversed the cognitive impairment in the Y maze test and the passive avoidance test and improved ASD associated behaviors in three chamber test and marble burying test. Risperidone treatment increased the expression levels of PSD95 and CDK5 and the phosphorylation level of Synapsin 1 in the KO mice brain. Finally, risperidone restored the number of dendritic branches in human neurons derived from CLCN4 KD NPCs. In conclusion, the results show that CLCN4 affect early social development through regulation of dendritic outgrowth and synapse remodeling. Moreover, risperidone can reverse the Clcn4 KO induced aberration in early development in addition to synapse and dendrite deficits suggesting an endophenotypic targets for drug development in ASD.