SENP1 in the Retrosplenial Agranular Cortex Regulates Core Autistic-Like Symptoms in Mice

Autism spectrum disorder (ASD) is a highly heritable neurodevelopmental disorder, in which core symptoms are defects of social interaction and evidently repetitive behaviors. Although around 50-70 % of ASD patients have comorbidity of intellectual disabilities (ID) or developmental delay (DD), there are some ASD patients who exhibit only core symptoms but without ID/DD, raising the question whether there are genetic components and neural circuits specific for core symptoms of ASD. Here, by focusing on ASD patients who do not show compound ID or DD, we identified a de novo heterozygous gene-truncating mutation of the Sentrin-specific peptidase1 (SENP1) gene, coding the small ubiquitin-like modifiers (SUMO) deconjugating enzyme, as a potentially new candidate gene for ASD. We found that Senp1 haploinsufficient mice exhibited core symptoms of autism such as deficits in social interaction and repetitive behaviors, but normal learning and memory ability. Moreover, we found that the inhibitory and excitatory synaptic functions were severely affected in the retrosplenial agranular (RSA) cortex of Senp1 haploinsufficient mice. Lack of Senp1 led to over SUMOylation and degradation of fragile X mental retardation protein (FMRP) proteins, which is coded by the FMR1 gene, also implicated in syndromic ASD. Importantly, re-introducing SENP1 or FMRP specifically in RSA fully rescued the defects of synaptic functions and core autistic-like symptoms of Senp1 haploinsufficient mice. Together, these results demonstrated that disruption of the SENP1-FMRP regulatory axis in the RSA may cause core autistic symptoms, which provide a candidate brain region of ASD for potential therapeutic intervene by neural modulation approaches.