DYRK2 displays muscle fiber type specific function during zebrafish early somitogenesis.

Dual specificity tyrosine-phosphorylation regulated kinase 2 (DYRK2) is a serine/threonine kinase. In zebrafish, DYRK2 is expressed in the lateral somites and adaxial cells at the early stage of embryo development. However, its role in early myogenesis had not been elucidated yet. Here, we report that DYRK2 mRNA and MyoD mRNA were colocalized in the muscle progenitor cells in somites, including both the posterior compartment of the lateral somites and adaxial cells. Knockdown of DYRK2 reduced the levels of MyoD transcripts in the muscle progenitor cells in somites. In contrast, overexpression of DYRK2 increased the levels of MyoD transcripts in the muscle progenitor cells in somites. The effects of knockdown and overexpression of DYRK2 on the expression of MyoD in the posterior compartment of the lateral somites were much greater than in the adaxial cells. Further studies indicated that forced expression of DYRK2 increased the levels of fast-twitch skeletal myosin RNA. Moreover, knockdown or forced expression of DYRK2 affected the levels of fast-twitch skeletal myosin protein. Together, these data indicate that DYRK2 is expressed in the developing muscle progenitor cells in somites and that it positively regulates fast-twitch muscle differentiation, at least at the early stages.