Transcriptome analysis of Shank2-heterozygous and -homozygous mice in different brain regions

Shank2 is an abundant excitatory postsynaptic scaffolding protein implicated in neurodevelopmental disorders, including autism spectrum disorders (ASD), intellectual disability, developmental delay, and schizophrenia. Shank2-mutant mice with a homozygous deletion of exons 6 and 7 (Shank2-HM mice) show ASD-like behavioral deficits and altered synaptic functions, although little is known about how different brain regions contribute to Shank2-mutant phenotypes. Here we attempted transcriptomic analyses of the prefrontal cortex, hippocampus, and striatum in adult Shank2-heterozygous/HT and Shank2-homozygous/HM mice. The mutant cortex, hippocampus, and striatum displayed distinct sets of differentially expressed genes associated with neuronal and synaptic functions in a gene dosage-differential manner. Gene set enrichment analyses of cortical Shank2-HT transcripts revealed increased synaptic gene expression and transcriptomic changes that are opposite to those observed in ASD (reverse-ASD), whereas cortical Shank2-HM transcripts displayed decreased synaptic gene expression and ASD-like transcriptomic patterns. The hippocampal Shank2-HT transcripts displayed minimally altered synaptic gene expression and mixed ASD-like and reverse-ASD patterns, whereas the Shank2-HM-hippocampus showed increased synaptic gene expression and reverse-ASD patterns. The striatal Shank2-HT/HM transcriptomes were largely similar to the hippocampal transcriptomes, although the main changes were observed in cell-type-specific genes, unlike the hippocampal changes mainly involving ASD-related/risk genes. These results indicate that heterozygous and homozygous Shank2 deletions in mice lead to brain region- and gene dosage-differential transcriptomic changes. Transcriptome analysis of Shank2-heterozygous and -homozygous mice in prefrontal cortex, hippocampus, and striatum