Transcription factor polyomavirus enhancer activator protein 3 (PEA3) is induced in adult rats following muscle injury

Following muscle damage, activation of adult myoblasts (also called satellite cells) is an important aspect of muscle regeneration. Upon activation, satellite cells proliferate, migrate to the site of injury, and become competent to fuse and differentiate, thereby regenerating damaged fibers. We show here that the transcription factor polyomavirus enhancer activator protein 3 (PEA3) is expressed in adult myoblasts in vitro when they are proliferative and during the early stages of differentiation. In young adult rat muscle in vivo, PEA3 is detectable in satellite cells only following muscle damage, suggesting that PEA3 is involved in regulating activated satellite cell gene expression. In contrast, PEA3 is expressed in undamaged muscle from aged rats and demonstrates a more dramatic increase following muscle injury. Thus, during muscle aging, satellite cells may become chronically activated but are still able to respond to signals resulting from muscle damage.