title: Nucleophosmin modulates stability, activity, and nucleolar accumulation of base excision repair proteins.
abstract: Nucleophosmin (NPM1) is a multifunctional protein that controls cell growth and genome stability via a mechanism that involves nucleolar-cytoplasmic shuttling. It is clear that NPM1 also contributes to the DNA damage response, yet its exact function is poorly understood. We recently linked NPM1 expression to the functional activation of the major abasic endonuclease in mammalian base excision repair (BER), apurinic/apyrimidinic endonuclease 1 (APE1). Here we unveil a novel role for NPM1 as a modulator of the whole BER pathway by 1) controlling BER protein levels, 2) regulating total BER capacity, and 3) modulating the nucleolar localization of several BER enzymes. We find that cell treatment with the genotoxin cisplatin leads to concurrent relocalization of NPM1 and BER components from nucleoli to the nucleoplasm, and cellular experiments targeting APE1 suggest a role for the redistribution of nucleolar BER factors in determining cisplatin toxicity. Finally, based on the use of APE1 as a representative protein of the BER pathway, our data suggest a function for BER proteins in the regulation of ribogenesis.
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine 33100, Italy.
authors.forename: Mattia
authors.initials: M
authors.lastname: Poletto
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine 33100, Italy.
authors.forename: Lisa
authors.initials: L
authors.lastname: Lirussi
authors.affiliation: Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224.
authors.forename: David M
authors.initials: DM
authors.lastname: Wilson
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine 33100, Italy gianluca.tell@uniud.it.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Tell
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000235:genetics; D002945:Cisplatin / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004249:DNA Damage / Q000235:genetics; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000096:biosynthesis / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D004318:Doxycycline / Q000494:pharmacology; D045585:Flap Endonucleases / Q000096:biosynthesis / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D000090243:Nucleophosmin; D021381:Protein Transport / Q000235:genetics; D034622:RNA Interference; D034741:RNA, Small Interfering; D012270:Ribosomes / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: D003432:Cross-Linking Reagents; C000716967:NPM1 protein, human; C000715570:Npm1 protein, mouse; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D000090243:Nucleophosmin; C572473:Fen1 protein, mouse; D045585:Flap Endonucleases; C486216:Apex1 protein, mouse; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D011088:DNA Ligases; D000072481:DNA Ligase ATP; D004318:Doxycycline; D002945:Cisplatin