Smooth muscle caldesmon modulates peristalsis in the wild type and non-innervated zebrafish intestine

Abrams, J., Davuluri, G., Seiler, C., and Pack, M.
Neurogastroenterology and motility   24(3): 288-299 (Journal)
Registered Authors
Abrams, Joshua, Pack, Michael, Seiler, Christoph
enteric nervous system, gastrointestinal motility, hypomotility, myosin light chain, zebrafish
MeSH Terms
  • Actins/metabolism
  • Alternative Splicing
  • Animals
  • Animals, Genetically Modified
  • Calmodulin-Binding Proteins/genetics
  • Calmodulin-Binding Proteins/metabolism*
  • Humans
  • Intestines/innervation*
  • Intestines/physiology*
  • Muscle Contraction/physiology
  • Muscle, Smooth/innervation
  • Muscle, Smooth/physiology*
  • Myosins/metabolism
  • Peristalsis/physiology*
  • Protein Isoforms/genetics
  • Protein Isoforms/metabolism
  • Zebrafish/anatomy & histology*
  • Zebrafish/physiology*
22316291 Full text @ Neurogastroenterol. Motil.

Background The high molecular weight isoform of the actin-binding protein Caldesmon (h-CaD) regulates smooth muscle contractile function by modulating cross-bridge cycling of myosin heads. The normal inhibitory activity of h-CaD is regulated by the enteric nervous system; however, the role of h-CaD during intestinal peristalsis has never been studied.

Methods We identified a zebrafish paralog of the human CALD1 gene that encodes an h-CaD isoform expressed in intestinal smooth muscle. We examined the role of h-CaD during intestinal peristalsis in zebrafish larvae by knocking down the h-CaD protein using an antisense morpholino oligonucleotide. We also developed transgenic zebrafish that express inhibitory peptides derived from the h-CaD myosin and actin-binding domains, and examined their effect on peristalsis in wild-type zebrafish larvae and sox10 colourless mutant larvae that lack enteric nerves.

Key Results Genomic analyses identified two zebrafish Caldesmon paralogs. The cald1a ortholog encoded a high molecular weight isoform generated by alternative splicing whose intestinal expression was restricted to smooth muscle. Propulsive intestinal peristalsis was increased in wild-type zebrafish larvae by h-CaD knockdown and by expression of transgenes encoding inhibitory myosin and actin-binding domain peptides. Peristalsis in the non-innervated intestine of sox10 colourless larvae was partially restored by h-CaD knockdown and expression of the myosin-binding peptide.

Conclusions & Inferences Disruption of the normal inhibitory function of h-CaD enhances intestinal peristalsis in both wild-type zebrafish larvae and mutant larvae that lack enteric nerves, thus confirming a physiologic role for regulation of smooth muscle contraction at the actin filament.

Genes / Markers
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Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes