Expression of secreted Wnt pathway components reveals unexpected complexity of the planarian amputation response

Dev Biol. 2010 Nov 1;347(1):24-39. doi: 10.1016/j.ydbio.2010.08.007. Epub 2010 Aug 10.


Regeneration is widespread throughout the animal kingdom, but our molecular understanding of this process in adult animals remains poorly understood. Wnt/β-catenin signaling plays crucial roles throughout animal life from early development to adulthood. In intact and regenerating planarians, the regulation of Wnt/β-catenin signaling functions to maintain and specify anterior/posterior (A/P) identity. Here, we explore the expression kinetics and RNAi phenotypes for secreted members of the Wnt signaling pathway in the planarian Schmidtea mediterranea. Smed-wnt and sFRP expression during regeneration is surprisingly dynamic and reveals fundamental aspects of planarian biology that have been previously unappreciated. We show that after amputation, a wounding response precedes rapid re-organization of the A/P axis. Furthermore, cells throughout the body plan can mount this response and reassess their new A/P location in the complete absence of stem cells. While initial stages of the amputation response are stem cell independent, tissue remodeling and the integration of a new A/P address with anatomy are stem cell dependent. We also show that WNT5 functions in a reciprocal manner with SLIT to pattern the planarian mediolateral axis, while WNT11-2 patterns the posterior midline. Moreover, we perform an extensive phylogenetic analysis on the Smed-wnt genes using a method that combines and integrates both sequence and structural alignments, enabling us to place all nine genes into Wnt subfamilies for the first time.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amputation, Surgical
  • Animals
  • Body Patterning / genetics
  • Frizzled Receptors / genetics
  • Frizzled Receptors / metabolism
  • Gene Expression Regulation, Developmental
  • Humans
  • Models, Biological
  • Nerve Tissue Proteins / metabolism
  • Phylogeny
  • Planarians / embryology
  • Planarians / genetics
  • Planarians / physiology*
  • Regeneration / physiology*
  • Signal Transduction*
  • Solubility
  • Stem Cells / cytology
  • Stem Cells / metabolism
  • Tail
  • Wnt Proteins / genetics
  • Wnt Proteins / metabolism*


  • Frizzled Receptors
  • Nerve Tissue Proteins
  • Wnt Proteins