The conservation landscape of the human ribosomal RNA gene repeats

PLoS One. 2018 Dec 5;13(12):e0207531. doi: 10.1371/journal.pone.0207531. eCollection 2018.

Abstract

Ribosomal RNA gene repeats (rDNA) encode ribosomal RNA, a major component of ribosomes. Ribosome biogenesis is central to cellular metabolic regulation, and several diseases are associated with rDNA dysfunction, notably cancer, However, its highly repetitive nature has severely limited characterization of the elements responsible for rDNA function. Here we make use of phylogenetic footprinting to provide a comprehensive list of novel, potentially functional elements in the human rDNA. Complete rDNA sequences for six non-human primate species were constructed using de novo whole genome assemblies. These new sequences were used to determine the conservation profile of the human rDNA, revealing 49 conserved regions in the rDNA intergenic spacer (IGS). To provide insights into the potential roles of these conserved regions, the conservation profile was integrated with functional genomics datasets. We find two major zones that contain conserved elements characterised by enrichment of transcription-associated chromatin factors, and transcription. Conservation of some IGS transcripts in the apes underpins the potential functional significance of these transcripts and the elements controlling their expression. Our results characterize the conservation landscape of the human IGS and suggest that noncoding transcription and chromatin elements are conserved and important features of this unique genomic region.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Conserved Sequence / genetics
  • DNA, Ribosomal / genetics
  • DNA, Ribosomal Spacer / genetics
  • Evolution, Molecular
  • Genes, rRNA / genetics*
  • Genetic Variation
  • Genomics / methods*
  • Humans
  • Phylogeny
  • Primates / genetics*
  • RNA, Ribosomal / genetics*
  • Repetitive Sequences, Nucleic Acid / genetics
  • Sequence Analysis, DNA
  • Transcriptome / genetics

Substances

  • DNA, Ribosomal
  • DNA, Ribosomal Spacer
  • RNA, Ribosomal

Grants and funding

This work was supported by grants from the Auckland Medical Research Foundation (4108008) and the New Zealand Marsden Fund (14-MAU-053) to ARDG, and a PhD scholarship from the Institute of Natural and Mathematical Sciences, Massey University to SA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.