Comparative RNA-seq analysis in the unsequenced axolotl: the oncogene burst highlights early gene expression in the blastema

PLoS Comput Biol. 2013;9(3):e1002936. doi: 10.1371/journal.pcbi.1002936. Epub 2013 Mar 7.

Abstract

The salamander has the remarkable ability to regenerate its limb after amputation. Cells at the site of amputation form a blastema and then proliferate and differentiate to regrow the limb. To better understand this process, we performed deep RNA sequencing of the blastema over a time course in the axolotl, a species whose genome has not been sequenced. Using a novel comparative approach to analyzing RNA-seq data, we characterized the transcriptional dynamics of the regenerating axolotl limb with respect to the human gene set. This approach involved de novo assembly of axolotl transcripts, RNA-seq transcript quantification without a reference genome, and transformation of abundances from axolotl contigs to human genes. We found a prominent burst in oncogene expression during the first day and blastemal/limb bud genes peaking at 7 to 14 days. In addition, we found that limb patterning genes, SALL genes, and genes involved in angiogenesis, wound healing, defense/immunity, and bone development are enriched during blastema formation and development. Finally, we identified a category of genes with no prior literature support for limb regeneration that are candidates for further evaluation based on their expression pattern during the regenerative process.

Publication types

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

MeSH terms

  • Ambystoma mexicanum / genetics
  • Ambystoma mexicanum / physiology*
  • Amputation, Surgical
  • Animals
  • Cluster Analysis
  • Extremities / injuries
  • Extremities / physiology
  • Gene Expression Profiling / methods*
  • Gene Expression Regulation*
  • Oncogenes*
  • Regeneration / genetics
  • Regeneration / physiology
  • Sequence Analysis, RNA / methods*
  • Up-Regulation
  • Wound Healing / genetics
  • Wound Healing / physiology