title: Leukemia-Associated Mutations in Nucleophosmin Alter Recognition by CRM1: Molecular Basis of Aberrant Transport.
abstract: Nucleophosmin (NPM) is a nucleocytoplasmic shuttling protein, normally enriched in nucleoli, that performs several activities related to cell growth. NPM mutations are characteristic of a subtype of acute myeloid leukemia (AML), where mutant NPM seems to play an oncogenic role. AML-associated NPM mutants exhibit altered subcellular traffic, being aberrantly located in the cytoplasm of leukoblasts. Exacerbated export of AML variants of NPM is mediated by the nuclear export receptor CRM1, and due, in part, to a mutationally acquired novel nuclear export signal (NES). To gain insight on the molecular basis of NPM transport in physiological and pathological conditions, we have evaluated the export efficiency of NPM in cells, and present new data indicating that, in normal conditions, wild type NPM is weakly exported by CRM1. On the other hand, we have found that AML-associated NPM mutants efficiently form complexes with CRM1HA (a mutant CRM1 with higher affinity for NESs), and we have quantitatively analyzed CRM1HA interaction with the NES motifs of these mutants, using fluorescence anisotropy and isothermal titration calorimetry. We have observed that the affinity of CRM1HA for these NESs is similar, which may help to explain the transport properties of the mutants. We also describe NPM recognition by the import machinery. Our combined cellular and biophysical studies shed further light on the determinants of NPM traffic, and how it is dramatically altered by AML-related mutations.
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
authors.forename: Igor
authors.initials: I
authors.lastname: Arregi
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Falces
authors.affiliation: Department of Genetics, Physical Anthropology and Animal Physiology, University of the Basque Country, Leioa, Spain.
authors.forename: Anne
authors.initials: A
authors.lastname: Olazabal-Herrero
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
authors.forename: Marián
authors.initials: M
authors.lastname: Alonso-Mariño
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
authors.forename: Stefka G
authors.initials: SG
authors.lastname: Taneva
authors.affiliation: Department of Genetics, Physical Anthropology and Animal Physiology, University of the Basque Country, Leioa, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Rodríguez
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
authors.forename: María A
authors.initials: MA
authors.lastname: Urbaneja
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Bañuelos
mesh_terms: D021581:Active Transport, Cell Nucleus; D002151:Calorimetry; D002466:Cell Nucleolus / Q000378:metabolism; D002942:Circular Dichroism; D003593:Cytoplasm / Q000378:metabolism; D005454:Fluorescence Polarization; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000473:pathology; D049790:Nuclear Export Signals; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000090243:Nucleophosmin; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D013816:Thermodynamics; D000097606:Exportin 1 Protein
chemical_list: D028884:Karyopherins; D049790:Nuclear Export Signals; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D000097606:Exportin 1 Protein; C000716967:NPM1 protein, human