Ribosomal 18S RNA processing by the IGF-I-responsive WDR3 protein is integrated with p53 function in cancer cell proliferation.

M. McMahon, V. Ayllon, Konstantin Panov, R. O`Connor

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Insulin-like growth factor-I (IGF-I) signaling is strongly associated with cell growth and regulates the rate of synthesis of the rRNA precursor, the first and the key stage of ribosome biogenesis. In a screen for mediators of IGF-I signaling in cancer, we recently identified several ribosome-related proteins, including NEP1 (nucleolar essential protein 1) and WDR3 (WD repeat 3), whose homologues in yeast function in ribosome processing. The WDR3 gene and its locus on chromosome 1p12-13 have previously been linked with malignancy. Here we show that IGF-I induces expression of WDR3 in transformed cells. WDR3 depletion causes defects in ribosome biogenesis by affecting 18 S rRNA processing and also causes a transient down-regulation of precursor rRNA levels with moderate repression of RNA polymerase I activity. Suppression of WDR3 in cells expressing functional p53 reduced proliferation and arrested cells in the G1 phase of the cell cycle. This was associated with activation of p53 and sequestration of MDM2 by ribosomal protein L11. Cells lacking functional p53 did not undergo cell cycle arrest upon suppression of WDR3. Overall, the data indicate that WDR3 has an essential function in 40 S ribosomal subunit synthesis and in ribosomal stress signaling to p53-mediated regulation of cell cycle progression in cancer cells.
Original languageEnglish
Pages (from-to)18309-18318
Number of pages10
JournalJournal of Biological Chemistry
Issue number24
Early online date14 Apr 2010
Publication statusPublished - 11 Jun 2010

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology


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