Characterization of innexin gene expression and functional roles of gap-junctional communication in planarian regeneration

Dev Biol. 2005 Nov 15;287(2):314-35. doi: 10.1016/j.ydbio.2005.09.002. Epub 2005 Oct 21.


Planaria possess remarkable powers of regeneration. After bisection, one blastema regenerates a head, while the other forms a tail. The ability of previously-adjacent cells to adopt radically different fates could be due to long-range signaling allowing determination of position relative to, and the identity of, remaining tissue. However, this process is not understood at the molecular level. Following the hypothesis that gap-junctional communication (GJC) may underlie this signaling, we cloned and characterized the expression of the Innexin gene family during planarian regeneration. Planarian innexins fall into 3 groups according to both sequence and expression. The concordance between expression-based and phylogenetic grouping suggests diversification of 3 ancestral innexin genes into the large family of planarian innexins. Innexin expression was detected throughout the animal, as well as specifically in regeneration blastemas, consistent with a role in long-range signaling relevant to specification of blastema positional identity. Exposure to a GJC-blocking reagent which does not distinguish among gap junctions composed of different Innexin proteins (is not subject to compensation or redundancy) often resulted in bipolar (2-headed) animals. Taken together, the expression data and the respecification of the posterior blastema to an anteriorized fate by GJC loss-of-function suggest that innexin-based GJC mediates instructive signaling during regeneration.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Body Patterning / physiology
  • Connexins / genetics
  • Connexins / metabolism*
  • Gap Junctions / physiology*
  • In Situ Hybridization
  • Intestines / physiology
  • Molecular Sequence Data
  • Nervous System Physiological Phenomena
  • Photoreceptor Cells, Invertebrate / physiology
  • Phylogeny
  • Planarians / physiology*
  • Regeneration / physiology
  • Signal Transduction


  • Connexins