WDR55 is a nucleolar modulator of ribosomal RNA synthesis, cell cycle progression, and teleost organ development

PLoS Genet. 2008 Aug 29;4(8):e1000171. doi: 10.1371/journal.pgen.1000171.


The thymus is a vertebrate-specific organ where T lymphocytes are generated. Genetic programs that lead to thymus development are incompletely understood. We previously screened ethylnitrosourea-induced medaka mutants for recessive defects in thymus development. Here we report that one of those mutants is caused by a missense mutation in a gene encoding the previously uncharacterized protein WDR55 carrying the tryptophan-aspartate-repeat motif. We find that WDR55 is a novel nucleolar protein involved in the production of ribosomal RNA (rRNA). Defects in WDR55 cause aberrant accumulation of rRNA intermediates and cell cycle arrest. A mutation in WDR55 in zebrafish also leads to analogous defects in thymus development, whereas WDR55-null mice are lethal before implantation. These results indicate that WDR55 is a nuclear modulator of rRNA synthesis, cell cycle progression, and embryonic organogenesis including teleost thymus development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Cycle*
  • Cell Nucleolus / genetics
  • Cell Nucleolus / metabolism
  • Fish Proteins / genetics
  • Fish Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Molecular Sequence Data
  • Mutation, Missense
  • NIH 3T3 Cells
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Oryzias / genetics
  • Oryzias / growth & development*
  • Oryzias / metabolism*
  • Phenotype
  • RNA Processing, Post-Transcriptional
  • RNA, Ribosomal / biosynthesis*
  • RNA, Ribosomal / genetics
  • Sequence Alignment
  • Thymus Gland / growth & development*
  • Thymus Gland / metabolism
  • Zebrafish / genetics
  • Zebrafish / growth & development
  • Zebrafish / metabolism


  • Fish Proteins
  • Nuclear Proteins
  • RNA, Ribosomal

Associated data

  • GENBANK/AB372859
  • GENBANK/AB372860
  • GENBANK/AB372861
  • GENBANK/AB372862