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Smooth muscle caldesmon modulates peristalsis in the wild type and non‐innervated zebrafish intestine
Author(s) -
Abrams J.,
Davuluri G.,
Seiler C.,
Pack M.
Publication year - 2012
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/j.1365-2982.2011.01844.x
Subject(s) - zebrafish , biology , myosin , peristalsis , gene knockdown , caldesmon , mutant , microbiology and biotechnology , gene isoform , actin , biochemistry , gene , calmodulin , enzyme
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.