Identification of FUSE-binding protein 1 as a regulatory mRNA-binding protein that represses nucleophosmin translation

Nucleophosmin (NPM/B23) is a multifunctional oncoprotein whose protein expression levels dictate cellular growth and proliferation rates. NPM is translationally responsive to hyperactive mammalian target of rapamycin (mTOR) signals, but the mechanism of this regulation is not understood. Using chimeric translational reporters, we found that the 30 untranslated region (UTR) of the NPM messenger (m) RNA is sufficient to mediate its translational modulation by mTOR signalling. We show that far upstream element (FUSE)-binding protein 1 (FBP1) interacts specifically with the 30 UTR of NPM to repress translation. Overexpression of FBP1 resulted in translational repression of NPM mRNAs, whereas depletion of FBP1 caused a dramatic increase in NPM translation and resulted in enhanced overall cell proliferation. Thus, we propose that FBP1 is a key regulator of cell growth and proliferation through its ability to selectively bind the NPM 30 UTR and repress NPM translation. Oncogene (2011) 30, 77-86; doi: 10.1038/onc.2010.404; published online 30 August 2010