alexa Myeloid leukemia-associated nucleophosmin mutants perturb p53-dependent and independent activities of the Arf tumor suppressor protein.
Haematology

Haematology

Journal of Bone Research

Author(s): Willem den Besten, MeiLing Kuo, Richard T Williams, Charles J Sherr

Abstract Share this page

Nucleophosmin (NPM or B23) plays key roles in ribosome biogenesis, centrosome duplication, and maintenance of genomic integrity. Mutations affecting the carboxylterminal domain of NPM occur in a significant percentage of adult patients with acute myeloid leukemia (AML), and these alterations create an additional nuclear export signal that relocalizes much of the protein from its normal nucleolar stores to the cytoplasm. When induced by oncogenic stress, the Arf tumor suppressor protein accumulates within the nucleolus, where it is physically associated with, and stabilized by, NPM. Ectopic overexpression of an NPM cytoplasmic mutant (NPMc) relocalized p19Arf and the endogenous NPM protein to the cytoplasm. NPMc-dependent export of p19Arf from the nucleus inhibited its functional interaction with the p53 negative regulator, Mdm2, and blunted Arf-induced activation of the p53 transcriptional program. Cytoplasmic NPM relocalization also attenuated Arf-induced sumoylation of Mdm2 and NPM and prevented wild type NPM from inhibiting p19Arf protein turnover. However, despite the ability of NPMc to interfere with these p53-dependent and independent activities of Arf, NPMc exhibited anti-proliferative activity in Arf-null NIH-3T3 cells. Overexpression of wild type NPM, but not NPMc, overcame premature senescence of Atm-null cells, a phenotype that can be rescued by inactivation of Arf or p53. Therefore, perturbation of Arf function appears to be insufficient to explain the oncogenic effects of the NPMc mutation. We favor the idea that NPMc also contributes to AML by dominantly perturbing other functions of the wild type NPM protein.

This article was published in Cell Cycle. and referenced in Journal of Bone Research

Relevant Expert PPTs

Relevant Speaker PPTs

Recommended Conferences

Relevant Topics

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

 
© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version
adwords