PLoS Genetics (Aug 2008)

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

  • Norimasa Iwanami,
  • Tomokazu Higuchi,
  • Yumi Sasano,
  • Toshinobu Fujiwara,
  • Vu Q Hoa,
  • Minoru Okada,
  • Sadiqur R Talukder,
  • Sanae Kunimatsu,
  • Jie Li,
  • Fumi Saito,
  • Chitralekha Bhattacharya,
  • Angabin Matin,
  • Takashi Sasaki,
  • Nobuyoshi Shimizu,
  • Hiroshi Mitani,
  • Heinz Himmelbauer,
  • Akihiro Momoi,
  • Hisato Kondoh,
  • Makoto Furutani-Seiki,
  • Yousuke Takahama

DOI
https://doi.org/10.1371/journal.pgen.1000171
Journal volume & issue
Vol. 4, no. 8
p. e1000171

Abstract

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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.