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

Mol Autism. 2019 Jan 31;10:3. doi: 10.1186/s13229-018-0250-4. eCollection 2019.

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.

Keywords: Digestive transit; Enteroendocrine; Peristaltic rate; Phelan-McDermid syndrome.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autistic Disorder / genetics*
  • Autistic Disorder / physiopathology
  • Enteric Nervous System / cytology
  • Enteric Nervous System / metabolism
  • Enteroendocrine Cells / metabolism
  • Gastrointestinal Motility*
  • Intestinal Mucosa / metabolism
  • Intestines / cytology
  • Intestines / growth & development
  • Intestines / physiology
  • Mutation
  • Nerve Tissue Proteins / genetics*
  • Neurons / metabolism
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Serotonin / metabolism
  • Zebrafish
  • Zebrafish Proteins / genetics*

Substances

  • Nerve Tissue Proteins
  • Protein Isoforms
  • SHANK3 protein, zebrafish
  • Zebrafish Proteins
  • Serotonin