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 : the official journal of the European Gastrointestinal Motility Society 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
- Alternative Splicing
- Animals, Genetically Modified
- Calmodulin-Binding Proteins/genetics
- Calmodulin-Binding Proteins/metabolism*
- Muscle Contraction/physiology
- Muscle, Smooth/innervation
- Muscle, Smooth/physiology*
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Zebrafish/anatomy & histology*
- 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.