西亚试剂：Polarized notum Activation at Wounds Inhibits Wnt Function

Polarized notum Activation at Wounds Inhibits Wnt Function to Promote Planarian Head Regeneration

Petersen, Christian P.; Reddien, Peter W.

Regeneration requires initiation of programs tailored to the identity of missing parts. Head-versus-tail regeneration in planarianspresents a paradigm for study of this phenomenon. After injury, Wnt signaling promotes tail regeneration. We report that woundingelicits expression of the Wnt inhibitor notum preferentially at anterior-facing wounds. This expression asymmetry occurs at essentially any wound, even if the anteriorpole is intact. Inhibition of notum with RNA interference (RNAi) causes regeneration of an anterior-facing tail instead of a head, and double-RNAi experimentsindicate that notum inhibits Wnt signaling to promote head regeneration. notum expression is itself controlled by Wnt signaling, suggesting that regulation of feedback inhibition controls the binary head-tailregeneration outcome. We conclude that local detection of wound orientation with respect to tissue axes results in distinctsignaling environments that initiate appropriate regeneration responses.