Bolli N, De Marco M F, Martelli M P, Bigerna B, Pucciarini A, Rossi R, Mannucci R, Manes N, Pettirossi V, Pileri S A, Nicoletti I, Falini B
Section of Haematology and Immunology, Department of Clinical and Experimental Medicine, University of Perugia, IBiT Foundation, Fondazione IRCCS Biotecnologie nel Trapianto, Perugia, Italy.
Leukemia. 2009 Mar;23(3):501-9. doi: 10.1038/leu.2008.326. Epub 2008 Nov 13.
In acute myeloid leukaemia (AML), nucleophosmin-1 (NPM1) mutations create a nuclear export signal (NES) motif and disrupt tryptophans at NPM1 C-terminus, leading to nucleophosmin accumulation in leukaemic cell cytoplasm. We investigated how nucleophosmin NES motifs (two physiological and one created by the mutation) regulate traffic and interaction of mutated NPM1, NPM1wt and p14(ARF). Nucleophosmin export into cytoplasm was maximum when the protein contained all three NES motifs, as naturally occurs in NPM1-mutated AML. The two physiological NES motifs mediated NPM1 homo/heterodimerization, influencing subcellular distribution of NPM1wt, mutated NPM1 and p14(ARF) in a 'dose-dependent tug of war' fashion. In transfected cells, excess doses of mutant NPM1 relocated completely NPM1wt (and p14(ARF)) from the nucleoli to the cytoplasm. This distribution pattern was also observed in a proportion of NPM1-mutated AML patients. In transfected cells, excess of NPM1wt (and p14(ARF)) relocated NPM1 mutant from the cytoplasm to the nucleoli. Notably, this distribution pattern was not observed in AML patients where the mutant was consistently cytoplasmic restricted. These findings reinforce the concept that NPM1 mutants are naturally selected for most efficient cytoplasmic export, pointing to this event as critical for leukaemogenesis. Moreover, they provide a rationale basis for designing small molecules acting at the interface between mutated NPM1 and other interacting proteins.
在急性髓系白血病（AML）中，核磷蛋白-1（NPM1）突变产生一个核输出信号（NES）基序，并破坏NPM1 C末端的色氨酸，导致核磷蛋白在白血病细胞质中积累。我们研究了核磷蛋白NES基序（两个生理性的和一个由突变产生的）如何调节突变型NPM1、野生型NPM1和p14（ARF）的转运和相互作用。当蛋白质包含所有三个NES基序时，核磷蛋白向细胞质的输出最大，这在NPM1突变的AML中自然发生。两个生理性NES基序介导NPM1同源/异源二聚化，以“剂量依赖性拔河”方式影响野生型NPM1、突变型NPM1和p14（ARF）的亚细胞分布。在转染细胞中，过量的突变型NPM1将野生型NPM1（和p14（ARF））从核仁完全重新定位到细胞质中。在一部分NPM1突变的AML患者中也观察到这种分布模式。在转染细胞中，过量的野生型NPM1（和p14（ARF））将NPM1突变体从细胞质重新定位到核仁。值得注意的是，在突变体始终局限于细胞质的AML患者中未观察到这种分布模式。这些发现强化了这样的概念，即NPM1突变体是为了最有效的细胞质输出而自然选择的，表明这一事件对白血病发生至关重要。此外，它们为设计作用于突变型NPM1与其他相互作用蛋白之间界面的小分子提供了理论基础。
