title: Genome-wide expression profile of the response to spinal cord injury in Xenopus laevis reveals extensive differences between regenerative and non-regenerative stages.
abstract: BACKGROUND
  Xenopus laevis has regenerative and non-regenerative stages. As a tadpole, it is fully capable of functional recovery after a spinal cord injury, while its juvenile form (froglet) loses this capability during metamorphosis. We envision that comparative studies between regenerative and non-regenerative stages in Xenopus could aid in understanding why spinal cord regeneration fails in human beings.
  
  
  RESULTS
  To identify the mechanisms that allow the tadpole to regenerate and inhibit regeneration in the froglet, we obtained a transcriptome-wide profile of the response to spinal cord injury in Xenopus regenerative and non-regenerative stages. We found extensive transcriptome changes in regenerative tadpoles at 1 day after injury, while this was only observed by 6 days after injury in non-regenerative froglets. In addition, when comparing both stages, we found that they deployed a very different repertoire of transcripts, with more than 80% of them regulated in only one stage, including previously unannotated transcripts. This was supported by gene ontology enrichment analysis and validated by RT-qPCR, which showed that transcripts involved in metabolism, response to stress, cell cycle, development, immune response and inflammation, neurogenesis, and axonal regeneration were regulated differentially between regenerative and non-regenerative stages.
  
  
  CONCLUSIONS
  We identified differences in the timing of the transcriptional response and in the inventory of regulated transcripts and biological processes activated in response to spinal cord injury when comparing regenerative and non-regenerative stages. These genes and biological processes provide an entry point to understand why regeneration fails in mammals. Furthermore, our results introduce Xenopus laevis as a genetic model organism to study spinal cord regeneration.
authors.forename: Dasfne
authors.initials: D
authors.lastname: Lee-Liu
authors.forename: Mauricio
authors.initials: M
authors.lastname: Moreno
authors.forename: Leonardo I
authors.initials: LI
authors.lastname: Almonacid
authors.forename: Víctor S
authors.initials: VS
authors.lastname: Tapia
authors.forename: Rosana
authors.initials: R
authors.lastname: Muñoz
authors.forename: Javier
authors.initials: J
authors.lastname: von Marées
authors.forename: Marcia
authors.initials: M
authors.lastname: Gaete
authors.forename: Francisco
authors.initials: F
authors.lastname: Melo
authors.affiliation: Center for Aging and Regeneration, Millennium Nucleus for Regenerative Biology, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile. jlarrain@bio.puc.cl.
authors.forename: Juan
authors.initials: J
authors.lastname: Larraín
mesh_terms: D000818:Animals; D055495:Neurogenesis / Q000235:genetics; D013119:Spinal Cord Injuries / Q000235:genetics*; D058630:Spinal Cord Regeneration / Q000235:genetics*; D059467:Transcriptome; D014982:Xenopus laevis