title: Role for nucleolin/Nsr1 in the cellular localization of topoisomerase I.
abstract: Nucleolin functions in ribosome biogenesis and contains an acidic N terminus that binds nuclear localization sequences. In previous work we showed that human nucleolin associates with the N-terminal region of human topoisomerase I (Top1). We have now mapped the topoisomerase I interaction domain of nucleolin to the N-terminal 225 amino acids. We also show that the Saccharomyces cerevisiae nucleolin ortholog, Nsr1p, physically interacts with yeast topoisomerase I, yTop1p. Studies of isogenic NSR1(+) and Deltansr1 strains indicate that NSR1 is important in determining the cellular localization of yTop1p. Moreover, deletion of NSR1 reduces sensitivity to camptothecin, an antineoplastic topoisomerase I inhibitor. By contrast, Deltansr1 cells are hypersensitive to the topoisomerase II-targeting drug amsacrine. These findings indicate that nucleolin/Nsr1 is involved in the cellular localization of Top1 and that this localization may be important in determining sensitivity to drugs that target topoisomerases.
authors.affiliation: Departments of Medicine/Pharmacology, Cancer Institute of New Jersey/Robert Wood Johnson Medical School-University of Medicine and Dentistry of New Jersey, New Brunswick, New Jersey 08901, USA.
authors.forename: T K
authors.initials: TK
authors.lastname: Edwards
authors.forename: A
authors.initials: A
authors.lastname: Saleem
authors.forename: J A
authors.initials: JA
authors.lastname: Shaman
authors.forename: T
authors.initials: T
authors.lastname: Dennis
authors.forename: C
authors.initials: C
authors.lastname: Gerigk
authors.forename: E
authors.initials: E
authors.lastname: Oliveros
authors.forename: M R
authors.initials: MR
authors.lastname: Gartenberg
authors.forename: E H
authors.initials: EH
authors.lastname: Rubin
mesh_terms: D000677:Amsacrine / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D002166:Camptothecin / Q000494:pharmacology; D002455:Cell Division / Q000235:genetics; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004352:Drug Resistance, Microbial / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008856:Microscopy, Fluorescence; D009154:Mutation; D009687:Nuclear Proteins; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013347:Subcellular Fractions / Q000737:chemistry; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; D014170:Transformation, Genetic
chemical_list: D000970:Antineoplastic Agents; D005656:Fungal Proteins; C068036:NSR1 protein, S cerevisiae; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; D000677:Amsacrine; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D002166:Camptothecin