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Nucleolar Arf tumor suppressor inhibits ribosomal RNA processing
Masataka Sugimoto1, Mei-Ling Kuo, Martine F Roussel
1Howard Hughes Medical Institute, St. Jude Children's Research Hospital, 332 North Lauderdale, Memphis, TN 38105, USA.
Molecular Cell
|March 7, 2003
Summary
The p19(Arf) tumor suppressor inhibits ribosomal RNA production and processing, impacting cell proliferation independently of p53 and Mdm2. This suggests a primordial Arf function in regulating cell growth and ribosome biogenesis.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- p19(Arf) is a tumor suppressor that typically induces cell cycle arrest via Mdm2 and p53.
- Arf can inhibit proliferation even in cells lacking Mdm2 and p53, but less effectively.
Purpose of the Study:
- To investigate the mechanism by which p19(Arf) inhibits cell proliferation independently of p53 and Mdm2.
- To determine if Arf's role in cell cycle regulation is linked to ribosomal biogenesis.
Main Methods:
- Assessing the impact of p19(Arf) on ribosomal RNA (rRNA) synthesis and processing.
- Analyzing the effects of Arf mutants on rRNA biogenesis and cell proliferation.
- Comparing Arf's effects with those of p53.
Main Results:
- p19(Arf) inhibits rRNA production and processing of precursors (47/45S and 32S).
- These effects on rRNA are not strictly dependent on rRNA biosynthesis inhibition or cell cycle arrest.
- Arf mutants lacking residues 2-14 fail to inhibit rRNA synthesis/processing and cell proliferation, indicating these residues are crucial for Arf function.
Conclusions:
- p19(Arf) possesses a p53/Mdm2-independent function in inhibiting ribosomal biogenesis and cell proliferation.
- This independent function is mediated by conserved amino acid residues (2-14) in Arf.
- Evolution may have integrated this nucleolar Arf function with the Mdm2/p53 pathway to create a robust checkpoint for coordinating ribosomal biogenesis and cell cycle progression.