title: Nucleophosmin mutations alter its nucleolar localization by impairing G-quadruplex binding at ribosomal DNA.
abstract: Nucleophosmin (NPM1) is an abundant nucleolar protein implicated in ribosome maturation and export, centrosome duplication and response to stress stimuli. NPM1 is the most frequently mutated gene in acute myeloid leukemia. Mutations at the C-terminal domain led to variant proteins that aberrantly and stably translocate to the cytoplasm. We have previously shown that NPM1 C-terminal domain binds with high affinity G-quadruplex DNA. Here, we investigate the structural determinants of NPM1 nucleolar localization. We show that NPM1 interacts with several G-quadruplex regions found in ribosomal DNA, both in vitro and in vivo. Furthermore, the most common leukemic NPM1 variant completely loses this activity. This is the consequence of G-quadruplex-binding domain destabilization, as mutations aimed at refolding the leukemic variant also result in rescuing the G-quadruplex-binding activity and nucleolar localization. Finally, we show that treatment of cells with a G-quadruplex selective ligand results in wild-type NPM1 dislocation from nucleoli into nucleoplasm. In conclusion, this work establishes a direct correlation between NPM1 G-quadruplex binding at rDNA and its nucleolar localization, which is impaired in the acute myeloid leukemia-associated protein variants.
authors: Department of Biochemical Sciences, 'Sapienza' University of Rome, 00185 Rome, Italy.
authors: Sara
authors: S
authors: Chiarella
authors: Antonella
authors: A
authors: De Cola
authors: Giovanni Luca
authors: GL
authors: Scaglione
authors: Erminia
authors: E
authors: Carletti
authors: Vincenzo
authors: V
authors: Graziano
authors: Daniela
authors: D
authors: Barcaroli
authors: Carlo
authors: C
authors: Lo Sterzo
authors: Adele
authors: A
authors: Di Matteo
authors: Carmine
authors: C
authors: Di Ilio
authors: Brunangelo
authors: B
authors: Falini
authors: Alessandro
authors: A
authors: Arcovito
authors: Vincenzo
authors: V
authors: De Laurenzi
authors: Luca
authors: L
authors: Federici
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D001667:Binding, Competitive; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D054856:G-Quadruplexes; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000090243:Nucleophosmin; D009841:Oligonucleotides / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport
chemical_list: D004275:DNA, Ribosomal; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D009841:Oligonucleotides; D011166:Porphyrins; D000090243:Nucleophosmin; C021096:tetra(4-N-methylpyridyl)porphine