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Science 319 (5861): 327-330

Copyright © 2008 by the American Association for the Advancement of Science

Smed-βcatenin-1 Is Required for Anteroposterior Blastema Polarity in Planarian Regeneration

Christian P. Petersen1, and Peter W. Reddien1,2*

Abstract: Planarian flatworms can regenerate heads at anterior-facing wounds and tails at posterior-facing wounds throughout the body. How this regeneration polarity is specified has been a classic problem for more than a century. We identified a planarian gene, Smed-βcatenin-1, that controls regeneration polarity. Posterior-facing blastemas regenerate a head instead of a tail in Smed-βcatenin-1(RNAi) animals. Smed-βcatenin-1 is required after wounding and at any posterior-facing wound for polarity. Additionally, intact Smed-βcatenin-1(RNAi) animals display anteriorization during tissue turnover. Five Wnt genes and a secreted Frizzled-related Wnt antagonist-like gene are expressed in domains along the anteroposterior axis that reset to new positions during regeneration, which suggests that Wnts control polarity through Smed-βcatenin-1. Our data suggest that β-catenin specifies the posterior character of the anteroposterior axis throughout the Bilateria and specifies regeneration polarity in planarians.

1 Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA.
2 Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

* To whom correspondence should be addressed. E-mail: reddien{at}wi.mit.edu

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