title: Nucleophosmin is essential for ribosomal protein L5 nuclear export.
abstract: Nucleophosmin (NPM/B23) is a key regulator in the regulation of a number of processes including centrosome duplication, maintenance of genomic integrity, and ribosome biogenesis. While the mechanisms underlying NPM function are largely uncharacterized, NPM loss results in severe dysregulation of developmental and growth-related events. We show that NPM utilizes a conserved CRM1-dependent nuclear export sequence in its amino terminus to enable its shuttling between the nucleolus/nucleus and cytoplasm. In search of NPM trafficking targets, we biochemically purified NPM-bound protein complexes from HeLa cell lysates. Consistent with NPM's proposed role in ribosome biogenesis, we isolated ribosomal protein L5 (rpL5), a known chaperone for the 5S rRNA. Direct interaction of NPM with rpL5 mediated the colocalization of NPM with maturing nuclear 60S ribosomal subunits, as well as newly exported and assembled 80S ribosomes and polysomes. Inhibition of NPM shuttling or loss of NPM blocked the nuclear export of rpL5 and 5S rRNA, resulting in cell cycle arrest and demonstrating that NPM and its nuclear export provide a unique and necessary chaperoning activity to rpL5/5S.
authors.affiliation: Department of Internal Medicine, Division of Molecular Oncology, Siteman Cancer Center, Washington University School of Medicine, Campus Box 8069, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Yu
authors.forename: Leonard B
authors.initials: LB
authors.lastname: Maggi
authors.forename: Suzanne N
authors.initials: SN
authors.lastname: Brady
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Apicelli
authors.forename: Mu-Shui
authors.initials: MS
authors.lastname: Dai
authors.forename: Hua
authors.initials: H
authors.lastname: Lu
authors.forename: Jason D
authors.initials: JD
authors.lastname: Weber
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D002853:Chromatography, Liquid; D016384:Consensus Sequence; D017124:Conserved Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D019143:Evolution, Molecular; D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007211:Indoles; D028884:Karyopherins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D000090243:Nucleophosmin; D011233:Precipitin Tests; D020543:Proteome / Q000032:analysis; D040901:Proteomics; D034622:RNA Interference; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D012235:Rhodamines; D012269:Ribosomal Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013347:Subcellular Fractions / Q000737:chemistry; D000097606:Exportin 1 Protein
chemical_list: D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D007211:Indoles; D028884:Karyopherins; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D020543:Proteome; D018160:Receptors, Cytoplasmic and Nuclear; D012235:Rhodamines; D012269:Ribosomal Proteins; D000097606:Exportin 1 Protein; C000716967:NPM1 protein, human; C000715570:Npm1 protein, mouse; C029742:ribosomal protein L5; C009434:tetramethylrhodamine isothiocyanate; C007293:DAPI