| Abstract: | Myosin XVIIIA, or MYO18 A, is a unique PDZ domain-containing unconventional myosin and is evolutionarily conserved from Drosophila to vertebrates. Although there is evidence indicating its expression in the somites, whether it regulates muscle function remains unclear. We show that the two zebrafish myo18 a genes(myo18aa and myo18ab) are predominantly expressed at somite borders during early developmental stages. Knockdown of these genes or overexpression of the MYO18 A PDZ domain disrupts myofiber integrity, induces myofiber lesions, and compromises the localization of dystrophin, a-dystroglycan(a-DG) and laminin at the myotome boundaries. Cell transplantation experiments indicate that myo18 a morphant myoblasts fail to form elongated myofibers in the myotomes of wild-type embryos, which can be rescued by the full-length MYO18 A protein. These results suggest that MYO18 A likely functions in the adhesion process that maintains the stable attachment of myofibers to ECM(extracellular matrix) and muscle integrity during early development. |
