Meeting Abstract
Repetitive DNA has been implicated in chromatin organization, regulation of gene expression, genome replication, and the maintenance of genome integrity, but large repeats are often not found in reference genomes. Establishing the organization and distribution of repetitive DNA within a genome is crucial to fully understanding cellular function and for identifying new targets for therapeutic genome editing. Importantly, the process of regeneration depends on proper cell growth throughout the numerous cycles of cell division that, in turn, depends on the timely and flawless assembly of ribosomes. Hydractinia, a colonial marine cnidarian, is a proven model for the study of regeneration. Its stem cells are pluripotent and have homologs to human genes associated with the ability to self-renew and differentiate. We have identified a complete ribosomal gene consensus sequence in Hydractinia, and determined the genomic architecture of its rDNA repeats. A comprehensive protein domain structural analysis indicates that Hydractinia, does not possess the canonical UBF protein, a transcription factor that is known to bind to rDNA and is required for the recruitment of the Pol I transcription machinery during ribosome biogenesis. This opens the possibility that Hydractinia, might employ a different mechanism for regulating transcription of rDNA genes and nucleolar formation than that used by higher eukaryotes, perhaps providing important insight as to the regenerative capacity of this organism. This overall approach and comparison of these repeats and transcription factors between regenerative and non-regenerative organisms might reveal mechanisms that are primitive and shared among animals (or evolutionarily derived ones). This will help address key questions in regeneration and prompt the development of new clinical approaches to improve human health.
