Analysis of Pluripotency Genes in Spinal Cord Regeneration of the Sea Lamprey (Petromyzon marinus)

Sea lampreys (Petromyzon marinus) are basal vertebrates with the ability to regenerate axons after spinal cord injury (SCI) and fully recover locomotor function 10-12 weeks post-injury. During the early stages of development, sea lamprey embryos undergo developmentally programmed genome rearrangement (PGR), which facilitates the deletion of ~20% of DNA from the germline genome and significantly differentiates the germline from the somatic genome. Recent studies provide evidence that these deletions limit pluripotency functions such as maintenance of cell fate, cell proliferation, and oncogenesis/tumorgenesis to the germline.

SCI provides a novel organismal context that is expected to promote the division and expansion of adult stem cell populations. To further investigate the role of eliminated pluripotency genes in lamprey, we tested for expression of several known germline-specific genes over the timecourse of regeneration after SCI. Analysis of this data has identified several “germline specific” genes that are highly expressed during regeneration and are presumed to be cells that possess stem-cell like characteristics. To further validate germline specificity, PCR amplification of these candidate genes is being performed from DNA extracted from canonical germline and several somatic tissues. These studies further reveal the extent to which PGR limits the somatic expression of pluripotency functions and increase our understanding of the genetic mechanisms underlying vertebrate spinal cord regeneration.