After Skin Wounding, Noncoding dsRNA Coordinates Prostaglandins and Wnts to Promote Regeneration

In a rare example akin to organogenesis in adult mammals, large wounds in mice lead to de novo morphogenesis of hair follicles. It is still not fully clear what controls this process, known as wound-induced hair neogenesis (WIHN). In other tissues, prostaglandin E₂ is an important effector of regeneration and has been shown to stimulate the Wnt/β-catenin pathway, which in turn is known to control WIHN. Previously, our group has shown that noncoding double-stranded RNA (dsRNA) released during wounding is both necessary and sufficient to stimulate WIHN through toll-like receptor 3. Here, we hypothesized that dsRNA similarly induces the β-catenin pathway through prostaglandin E₂. We found that WIHN levels correlate closely with Wnt7b production in vivo and that dsRNA potently induces Wnt7b in a manner that requires Ptgs2. The Ptgs2 inhibitor celecoxib reduces dsRNA-induced WIHN and Wnt7b, and exogenous prostaglandin E₂ can rescue WIHN and Wnt7b. Although other Wnts and pathways likely contribute, these results highlight noncoding dsRNA as an upstream coordinator of prostaglandin and Wnt levels in regeneration.