Background: Microarray analysis and 454 cDNA sequencing were used to investigate a centuries-old problem in regenerative biology: The basis of nerve-dependent limb regeneration in salamanders. Innervated (NR) and denervated (DL) forelimbs of Mexican axolotls were amputated and transcripts were sampled after 0, 5, and 14 days of regeneration. Results: Considerable similarity was observed between NR and DL transcriptional programs at 5 and 14 days post amputation (dpa). Genes with extracellular functions that are critical to wound healing were upregulated while muscle-specific genes were downregulated. Thus, many processes that are regulated during early limb regeneration do not depend upon nerve-derived factors. The majority of the transcriptional differences between NR and DL limbs were correlated with blastema formation; cell numbers increased in NR limbs after 5 dpa and this yielded distinct transcriptional signatures of cell proliferation in NR limbs at 14 dpa. These transcriptional signatures were not observed in DL limbs. Instead, gene expression changes within DL limbs suggest more diverse and protracted wound-healing responses. 454 cDNA sequencing complemented the microarray analysis by providing deeper sampling of transcriptional programs and associated biological processes. Assembly of new 454 cDNA sequences with existing expressed sequence tag (EST) contigs from the Ambystoma EST database more than doubled (3935 to 9411) the number of non-redundant human-A. mexicanum orthologous sequences. Conclusion: Many new candidate gene sequences were discovered for the first time and these will greatly enable future studies of wound healing, epigenetics, genome stability, and nerve-dependent blastema formation and outgrowth using the axolotl model.
|State||Published - Jan 13 2009|
Bibliographical noteFunding Information:
This project was supported by grants R24-RR016344 and P20-RR016741 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NCRR or NIH. The project was also supported by a Roche genome sequencing award, funding from the Kentucky Spinal Cord and Brain Injury Research Trust, the California Institute for Regenerative Medicine, and the Kentucky Bioinformatics Research Infrastructure Network. The Spinal Cord and Brain Injury Research Center and the NSF supported Ambystoma Genetic Stock Center (DBI-0443496) provided resources and facilities. We thank Ananth Kalyanaraman for running PaCE clustering at Washington State University. Arnold Stromberg and Phil Crowly provided statistical advice.
ASJC Scopus subject areas
- Structural Biology
- Ecology, Evolution, Behavior and Systematics
- Biochemistry, Genetics and Molecular Biology (all)
- Agricultural and Biological Sciences (all)
- Plant Science
- Developmental Biology
- Cell Biology