Molecular Autism (Jan 2019)

Intestinal dysmotility in a zebrafish (Danio rerio) shank3a;shank3b mutant model of autism

  • David M. James,
  • Robert A. Kozol,
  • Yuji Kajiwara,
  • Adam L. Wahl,
  • Emily C. Storrs,
  • Joseph D. Buxbaum,
  • Mason Klein,
  • Baharak Moshiree,
  • Julia E. Dallman

DOI
https://doi.org/10.1186/s13229-018-0250-4
Journal volume & issue
Vol. 10, no. 1
pp. 1 – 15

Abstract

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Abstract Background and aims Autism spectrum disorder (ASD) is currently estimated to affect more than 1% of the world population. For people with ASD, gastrointestinal (GI) distress is a commonly reported but a poorly understood co-occurring symptom. Here, we investigate the physiological basis for GI distress in ASD by studying gut function in a zebrafish model of Phelan-McDermid syndrome (PMS), a condition caused by mutations in the SHANK3 gene. Methods To generate a zebrafish model of PMS, we used CRISPR/Cas9 to introduce clinically related C-terminal frameshift mutations in shank3a and shank3b zebrafish paralogues (shank3abΔC). Because PMS is caused by SHANK3 haploinsufficiency, we assessed the digestive tract (DT) structure and function in zebrafish shank3abΔC +/− heterozygotes. Human SHANK3 mRNA was then used to rescue DT phenotypes in larval zebrafish. Results Significantly slower rates of DT peristaltic contractions (p < 0.001) with correspondingly prolonged passage time (p < 0.004) occurred in shank3abΔC +/− mutants. Rescue injections of mRNA encoding the longest human SHANK3 isoform into shank3abΔC +/− mutants produced larvae with intestinal bulb emptying similar to wild type (WT), but still deficits in posterior intestinal motility. Serotonin-positive enteroendocrine cells (EECs) were significantly reduced in both shank3abΔC +/− and shank3abΔC −/− mutants (p < 0.05) while enteric neuron counts and overall structure of the DT epithelium, including goblet cell number, were unaffected in shank3abΔC +/− larvae. Conclusions Our data and rescue experiments support mutations in SHANK3 as causal for GI transit and motility abnormalities. Reductions in serotonin-positive EECs and serotonin-filled ENS boutons suggest an endocrine/neural component to this dysmotility. This is the first study to date demonstrating DT dysmotility in a zebrafish single gene mutant model of ASD.

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