Expression profile of ankrd1a during repair of injured zebrafish skeletal muscle

Abstract

In our previous work, using transgenic zebrafish line TgBAC(ankrd1a:EGFP), we showed activation of the zebrafish ankrd1a gene in border zone cardiomyocytes of cryoinjured heart and in close proximity of needle-stab wounds in skeletal muscle, indicating its involvement in muscle regeneration. Our results implicated ankrd1a in zebrafish skeletal muscle tissue repair and remodeling, as a sensor of stressed muscle. Here we take a closer look at the spatio-temporal expression profile of the ankrd1a gene in injured zebrafish skeletal muscle by analyzing cryosections prepared from wounded tissue of TgBAC(ankrd1a:EGFP) adults at 1, 3, 5, 7 and 10 days post-injury (dpi). The expression of the fluorescent reporter was observed from 3 dpi and remained until 10 dpi. At 3dpi, new GFP-positive muscle cells emerged inside the injury zone, at the site of needle entry, while in the later days (5, 7 and 10 dpi), newly formed GFP-positive myofibers were visible in the deeper tissue layers within the injury, indicating active repair of the injured tissue. To identify cells in which ankrd1a is activated after injury, we stained the sections for markers of satellite-like cells, undifferentiated and differentiated muscle cells, and mature myofibers. Since the reporter was detected both in the newly formed myofibers that invade the wound and in the apparently uninjured tissue surrounding the injury, we hypothesize that ankrd1a is not only involved in satellite celldependent tissue repair, but its expression might be a hallmark of adaptive process in undamaged myofibers surrounding the physical injury.