Global analysis of gene expression in Xenopus limbs during stage‐dependent complete and incomplete regeneration

Abstract

We have examined genes expressed during hindlimb regeneration using the Affymetrix Xenopus genome genechip, specifically comparing expression at two stages of larval development, NF 53 (when an essentially normal limb regenerates) and NF 57 (when only a pattern-deficient outgrowth forms.) RNA was harvested from regenerating limbs at the wound healing and initiation (1 day post-amputation, PA) and the rapid growth (5 days PA) phases of regeneration. Genechip analysis revealed nearly 3000 genes displaying statistically significant (p<0.05) differential expression at these two larval stages. The genes were then grouped by known function (dedifferentiation, epigenetics, immune activity, patterning, etc.) The data confirm results of previous gene expression studies of Xenopus regeneration and provide significant new insights into both the molecular mechanism of limb regeneration and its failure in phylogenetically more advanced vertebrates. Many genes involved in either inflammation or immunotolerance are differentially expressed, a result consistent with the view that immunological and fibrotic mechanisms produce the decline in regenerative capacity which characterizes limbs during the transition to the adult stage. RT-PCR and Q-PCR for selected genes confirms the gene array data. Indiana 21st Century Research and Technology Fund.