Submitted on August 30, 2007
Accepted on November 27, 2007
Smed-
catenin-1 Is Required for Anteroposterior Blastema Polarity in Planarian Regeneration
Christian P. Petersen 1 and Peter W. Reddien 2*
1 Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA.
2 Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA.; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
* To whom correspondence should be addressed.
Peter W. Reddien , E-mail: reddien{at}wi.mit.edu
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 over a century. We identified a planarian gene, Smed-
catenin-1, that controls regeneration polarity. Posterior-facing blastemas regenerate a head instead of a tail in Smed-catenin-1(RNAi) animals. Smed-catenin-1 is required after wounding and at any posterior-facing wound for polarity. Additionally, intact Smed-catenin-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, suggesting Wnts control polarity through Smed-catenin-1. Our data suggest -catenin specifies the posterior character of the anteroposterior axis throughout the Bilateria and specifies regeneration polarity in planarians.
