Developmental profiling of ASD-related shank3 transcripts and their differential regulation by valproic acid in zebrafish.

Chun-Xue Liu,Xiao-Lan Peng,Chun-Chun Hu,Xiu Xu,Qiang Li,Chun-Yang Li

doi:10.1007/s00427-016-0561-4

Abstract

SHANK3 is a scaffolding protein that binds to various synaptic proteins at the postsynaptic density (PSD) of excitatory glutamatergic synapses. SHANK3 is not only strongly implicated in autism spectrum disorders (ASD) but also plays a critical role in human Phelan-McDermid syndrome (22q13.3 deletion syndrome). Accumulated experimental evidence demonstrates that the zebrafish model system is useful for studying the functions of ASD-related gene during early development. However, many basic features of shank3 transcript expression in zebrafish remain poorly understood. Here, we investigated temporal, spatial, and isoform-specific expression patterns of shank3 during zebrafish development on the basis of previous researches and the differential effects of each shank3 transcript expression after exposure to valproic acid (VPA), an ASD-associated drug. At first, we observed that both shank3a and shank3b were barely expressed at very early ages (before 24 h post-fertilization (hpf)), whereas their expression levels were increased and mainly enriched in the nervous system after 24 hpf. Secondly, all of the six shank3 transcripts gradually increased during the first 7 hpf and then decreased. Subsequently, they exhibited a second increasing peak between 1 month post-fertilization (mpf) and adulthood. Thirdly, VPA treatment affected the isoform-specific expression of zebrafish shank3. In particular, the mRNA expression levels of those isoforms that contain a SAM domain were significantly increased, whereas the mRNA expression level of those which contained an ANK domain but without a SAM domain was decreased. To conclude, our findings support the molecular diversity of shank3 in zebrafish and provide a molecular framework to understand the isoform-specific function of shank3 in zebrafish.Electronic supplementary materialThe online version of this article (doi:10.1007/s00427-016-0561-4) contains supplementary material, which is available to authorized users.

Highlights

Communicated by Matthias HammerschmidtElectronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Synaptogenesis is a key process that occurs during brain circuitry development, and inappropriate synapse formation or structure is thought to underlie a variety of neurodevelopmental disorders
The data were presented as the percentages of embryos with each defect, and the results were calculated by dividing the total number of embryos with the shank3 is a conserved gene in the vertebrate lineage that possesses multiple transcripts
Our study demonstrated that zebrafish shank3 was unique to the vertebrate lineage (Fig. 2a) and possessed an ortholog of human SHANK3 that has retained the conserved ANK, SH3, PDZ and SAM domains (Supple mentary Material, Fig. S2)

Summary

Introduction

Communicated by Matthias HammerschmidtElectronic supplementary material The online version of this article (doi:10.1007/s00427-016-0561-4) contains supplementary material, which is available to authorized users.Synaptogenesis is a key process that occurs during brain circuitry development, and inappropriate synapse formation or structure is thought to underlie a variety of neurodevelopmental disorders (van Spronsen and Hoogenraad, 2010; Guo et al, 2015). Accumulating human genetic evidence supports a strong causal relationship between molecular defects in the SHANK3 gene and ASD, which is a heritable, debilitating neurodevelopmental disorder (Grzadzinski et al, 2013; McGuinness and Johnson, 2013; Wang et al, 2014). Much experimental evidence has demonstrated that zebrafish (Danio rerio) is a valuable model organism to model human brain disorders, normal and pathological social phenotypes and other ASD-like symptoms. Zebrafish can be used to explore the genetic or pharmacological modulation of those diseases (Gerlai, 2010; Kalueff et al, 2013; Stewart et al, 2013; Stewart et al, 2014), making zebrafish a strong potential model organism for studying ASD gene function early in development (Pather and Gerlai, 2009; Gerlai, 2010; Gerlai, 2011; Stewart et al, 2013)

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