Gene Dosage- and Age-Dependent Differential Transcriptomic Changes in the Prefrontal Cortex of Shank2-Mutant Mice.

Seungjoon Lee,Hwajin Jung,Hyojin Kang,Eunee Lee,Eunjoon Kim

doi:10.3389/fnmol.2021.683196

Abstract

Shank2 is an abundant postsynaptic scaffolding protein that is known to regulate excitatory synapse assembly and synaptic transmission and has been implicated in various neurodevelopmental disorders, including autism spectrum disorders (ASD). Previous studies on Shank2-mutant mice provided mechanistic insights into their autistic-like phenotypes, but it remains unclear how transcriptomic patterns are changed in brain regions of the mutant mice in age- and gene dosage-dependent manners. To this end, we performed RNA-Seq analyses of the transcripts from the prefrontal cortex (PFC) of heterozygous and homozygous Shank2-mutant mice lacking exons 6 and 7 at juvenile (week 3) and adult (week 12) stages. Juvenile heterozygous Shank2-mutant mice showed upregulation of glutamate synapse-related genes, downregulation of ribosomal and mitochondrial genes, and transcriptomic changes that are opposite to those observed in ASD (anti-ASD) such as upregulation of ASD_down (downregulated in ASD), GABA neuron-related, and oligodendrocyte-related genes. Juvenile homozygous Shank2 mice showed upregulation of chromatin-related genes and transcriptomic changes that are in line with those occurring in ASD (pro-ASD) such as downregulation of ASD_down, GABA neuron-related, and oligodendrocyte-related genes. Adult heterozygous and homozygous Shank2-mutant mice both exhibited downregulation of ribosomal and mitochondrial genes and pro-ASD transcriptomic changes. Therefore, the gene dosage- and age-dependent effects of Shank2 deletions in mice include differential transcriptomic changes across distinct functional contexts, including synapses, chromatin, ribosomes, mitochondria, GABA neurons, and oligodendrocytes.

Highlights

We analyzed and compared the transcriptomic changes occurring in the prefrontal cortex (PFC) of four different Shank2-mutant mouse groups (W3-HT, W3-HM, W12-HT, and W12-HM) using differentially expressed genes (DEG) and Gene Set Enrichment Analysis (GSEA) analyses
Our goal was to provide insight into the molecular changes induced in the PFC by Shank2 heterozygous and homozygous deletions across juvenile and adult stages in mice
Our analyses identified differential transcriptomic changes in heterozygous and homozygous Shank2-mutant mice across juvenile and adult stages and interesting biological functions, including those associated with synapse, ribosome, mitochondria, chromatin, gamma amino butyric acid (GABA) neuron, and oligodendrocyte

Summary

Introduction

MATERIALS AND METHODSShank ( known as ProSAP1) is an abundant scaffolding protein known to regulate excitatory synapse assembly and synaptic transmission, plasticity, and signaling (Du et al, 1998; Boeckers et al, 1999; Lim et al, 1999; Naisbitt et al, 1999); reviewed in Boeckers et al (2002); Grabrucker et al (2011); Sala et al (2015); Mossa et al (2017); and Sheng and Kim (2000, 2011). We identified differential transcriptomic changes involving multiple biological functions and ASD-related genes, and found that they were distinct between W3-HT and W3HM mice, but largely similar between W12-HT and W12-HM mice. These analyses identified the potential involvement of genes associated with various functional contexts, including synapses, chromatin, ribosomes, mitochondria, GABA neurons, and oligodendrocytes

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