Canonical Wnt Signaling Pathway Is Involved in Muscle Regeneration after Tongue Injury

Introduction:

The signaling pathways involved in the repair process after a mechanical tongue injury are still unclear. Canonical Wnt signaling could promote tissue regeneration in several adult tissues.¹ Also it plays crucial roles in embryonic tongue development.² The aim of this project is to investigate the molecular mechanisms underlying new muscle formation process after tongue injury.

Method:

A 2 mm punch was used to generate an acute penetration injury to mouse oral tongue. Tongue samples were analyzed at different time points following the injury with HE staining to evaluate the wound repair process. Satellite cells were analyzed for the molecular marker Pax7 using immunochemistry staining. Tamoxifen-inducible Pax7 Cre ERT2; R26RF/+ reporter mice were used to analyze the contribution of satellite cells to newly formed muscle fibers. Double antigen staining was performed to analyze the relationship between the behavior of satellite cells and the Wnt signaling pathway.

Results:

New muscle formation started as early as three days after injury as Pax7(+) cells started to proliferate. One week after injury, newly formed muscle fibers derived from Pax7(+) cells were evident. Two weeks after injury, the boundary between the injured and uninjured regions could not be clearly distinguished as the Pax7(+) cell distribution normalized to its previous state. Also, active β-catenin and Pax7(+) showed co-localization of their expression in tongue three days post-injury. The expression of active β-catenin was not restricted to Pax7(+) but also was seen in cranial neural crest cells.

Conclusion:

Canonical Wnt signaling may play an important role in satellite cell proliferation in new muscle regeneration after a tongue injury.

References

1. Minear S, Helms JA, et al: Wnt proteins promote bone regeneration. Sci Transl Med 28;2(29):29ra30, 2010

2. Hutcheson DA, Kardon G, et al: Embryonic and fetal limb myogenic cells are derived from developmentally distinct progenitors and have different requirements for beta-catenin. Genes Dev 15;23(8):997-1013, 2009