Sonic Hedgehog (SHH) expression in developing and regenerating axolotl limbs

Maureen A. Torok, David M. Gardiner, Juan Carlos Izpisúa-Belmonte, Susan V. Bryant*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

97 Scopus citations


Sonic hedgehog (shh) expression is detectable in the posterior mesenchyme of many developing vertebrate limbs. We have isolated an RT-PCR fragment from the axolotl, Arabystoma mexicanum, that has high identity to other vertebrate shh genes. We describe the localization of this transcript during development and regeneration and in response to tissue grafts and retinoic acid (RA) exposure in the axolotl. Even though axolotl digits show a reversed polarity of differentiation (anterior [A] to posterior [P]) when compared to other tetrapods (P to A), shh is nevertheless expressed on the posterior margin of developing and regenerating limb buds. When A cells are grafted adjacent to P cells, an ectopic domain of shh is induced. Exposure to retinoic acid (RA), a molecule known to alter pattern in all three limb axes in urodeles, results in ectopic expression of shh in anterior cells of the regeneration blastema. Prior to this induced expression in response to RA, there is an earlier response by the endogenous domain of shh, which is downregulated within the first few hours of exposure.

Original languageEnglish (US)
Pages (from-to)197-206
Number of pages10
JournalJournal of Experimental Zoology
Issue number2
StatePublished - Jul 1 1999
Externally publishedYes

ASJC Scopus subject areas

  • Animal Science and Zoology


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