Cognitive and Synaptic Impairment Induced by Deficiency of Autism Risk GeneSmarcc2and its Rescue by Histone Deacetylase Inhibition

SMARCC2, which encodes BAF170, a core subunit of chromatin remodeling BAF complex, is one of the top-ranking risk genes for autism spectrum disorder (ASD). However, the mechanisms linkingSMARCC2haploinsufficiency to ASD remain poorly understood. Genome-wide RNA-seq analysis revealed thatSMARCC2was significantly diminished in iPSC-derived neurons from idiopathic ASD patients. ChIP-seq ofSMARCC2demonstrated its binding to many other ASD risk genes involved in transcriptional regulation.Smarcc2deficiency in prefrontal cortex (PFC) of adolescent mice led to impaired working memory, with largely intact social and anxiety-like behaviors. Significant downregulation of genes enriched in synaptic transmission were found in PFC of Smarcc2-deficient mice by RNA-seq and qPCR profiling. In parallel, electrophysiological recordings uncovered the significant impairment of GABAergic and glutamatergic synaptic currents in Smarcc2-deficient PFC pyramidal neurons. Smarcc2 bound to HDAC2, andSmarcc2deficiency led to the reduced global histone acetylation and H3K9ac enrichment at synaptic geneSlc1a3(EAAT1),Slc6a1(GAT1), andSlc32a1(VGAT) promoters. Treatment of Smarcc2-deficient mice with romidepsin, a class I HDAC inhibitor, restored histone acetylation, working memory and some synaptic gene expression. These findings highlight the critical role of Smarcc2 in regulating cognitive and synaptic function, suggesting that targeting HDAC could alleviate deficits in Smarcc2-associated neurodevelopmental disorders.