Disruption of the autism-related gene Pak1 causes stereocilia disorganization,hair cell loss,and deafness in mice

Several clinical studies have reported that hearing loss is correlated with autism in children.However,little is known about the underlying mechanism between hearing loss and autism.p21-activated kinases(PAKs)are a family of serine/threonine kinases that can be activated by multiple signaling molecules,particularly the Rho family of small GTPases.Previous studies have shown that Pak1 mutations are associated with autism.In the present study,we take advantage of Pak1 knockout(Pak1a/a)mice to investigate the role of PAK1 in hearing function.We find that PAK1 is highly expressed in the postnatal mouse cochlea and that PAK1 deficiency leads to hair cell(HC)apoptosis and severe hearing loss.Further investigation indicates that PAK1 deficiency downregulates the phosphorylation of cofilin and ezrin-radixin-moesin and the expression of b II-spectrin,which further decreases the HC synapse density in the basal turn of cochlea and disorganized the HC stereocilia in all three turns of cochlea in Pak1à/àmice.Overall,our work demonstrates that the autism-related gene Pak1 plays a crucial role in hearing function.As the first candidate gene linking autism and hearing loss,Pak1 may serve as a potential target for the clinical diagnosis of autism-related hearing loss.

Regulation of Social Memory by Lateral Entorhinal Cortical Projection to Dorsal Hippocampal CA2

Dear Editor,TSocial recognition memory is essential for proper conspecific interactions and its impairments are closely associated with many brain disorders,including autism,schizophrenia,and Alzheimer's disease[1-3].However,the mechanisms and neural circuits underlying social memory formation and retrieval are still unclear.Recent studies have revealed that several brain regions are involved in social memory formation,and the hippocampal dorsal CA2(dCA2)subregion appears to be its core locus[4,5].