Shank3 Mice Carrying the Human Q321R Mutation Display Enhanced Self-Grooming, Abnormal Electroencephalogram Patterns, and Suppressed Neuronal Excitability and Seizure Susceptibility.

Ye-Eun Yoo,Yong-Chul Bae,Seungjoon Lee,Jiseok Lee,Doyoun Kim,Taesun Yoo,Eunjoon Kim,Hye-Min Han

doi:10.3389/fnmol.2019.00155

Abstract

Shank3, a postsynaptic scaffolding protein involved in regulating excitatory synapse assembly and function, has been implicated in several brain disorders, including autism spectrum disorders (ASD), Phelan-McDermid syndrome, schizophrenia, intellectual disability, and mania. Here we generated and characterized a Shank3 knock-in mouse line carrying the Q321R mutation (Shank3Q321R mice) identified in a human individual with ASD that affects the ankyrin repeat region (ARR) domain of the Shank3 protein. Homozygous Shank3Q321R/Q321R mice show a selective decrease in the level of Shank3a, an ARR-containing protein variant, but not other variants. CA1 pyramidal neurons in the Shank3Q321R/Q321R hippocampus show decreased neuronal excitability but normal excitatory and inhibitory synaptic transmission. Behaviorally, Shank3Q321R/Q321R mice show moderately enhanced self-grooming and anxiolytic-like behavior, but normal locomotion, social interaction, and object recognition and contextual fear memory. In addition, these mice show abnormal electroencephalogram (EEG) patterns and decreased susceptibility to induced seizures. These results indicate that the Q321R mutation alters Shank3 protein stability, neuronal excitability, repetitive and anxiety-like behavior, EEG patterns, and seizure susceptibility in mice.

Highlights

These results suggest the possibility that these intra- and intermolecular interactions of the SPN and ankyrin repeat region (ARR) domains of Shank3 might underlie the effects of the Q321R mutation
We included the following additional autism spectrum disorders (ASD)-risk Shank3 mutations in SPN and ARR domains in our modeling (Durand et al, 2007; Moessner et al, 2007; Gauthier et al, 2010): L68P, which disrupts the interaction between the SPN and ARR domains and enhances the interactions of the ARR with Sharpin (Mameza et al, 2013); R12C, which affects excitatory synapse structure and function (Durand et al, 2012) and disrupts SPN binding to GTP-bound Ras and Rap small
We found that the Q321R mutation, unlike the L68P mutation, is located in the C-terminal region of the ARR domain, away from the interface of the SPN and ARR domains, and is unlikely to affect the SPN-ARR interaction (Figure 1A)

Summary

Introduction

A family of postsynaptic scaffolding proteins with three known members, have been implicated in the regulation of excitatory synapse assembly and function (Sheng and Kim, 2000, 2011; Sheng and Sala, 2001; Boeckers et al, 2002; Sheng and Hoogenraad, 2007; Grabrucker et al, 2011; Jiang and Ehlers, 2013; Sala et al, 2015; Monteiro and Feng, 2017; Mossa et al, 2017). With the exception of recent studies on two mouse lines carrying an ASD-linked InsG3680 mutation and a schizophrenia-linked R1117X mutation (Zhou et al, 2016) and a mouse line carrying the S685I mutation (Wang et al, 2019), mouse lines expressing point mutations of Shank identified in human individuals with ASD, PMS, or other disorders have not been reported

Methods

Results

Conclusion