ATP depletion affects NPM translocation and exportation of rRNA from nuclei.
Nucleophosmin/B23 (NPM) is a nucleolar phosphoprotein which shifts from nucleoli to the nucleoplasm in cells treated with certain cytotoxic agents (NPM-translocation). NPM requires GTP for localization into nucleoli (J. Biol. Chem. 268, 5823-5827, 1993). To understand more about NPM's dynamic localization, the effects of lowering ATP on NPM-translocation and rRNA synthesis were studied. When the ATP level in HeLa cells was reduced by sodium azide, NPM-translocation was blocked. Similar results were obtained when ATP was depleted by other agents, suggesting that ATP depletion was responsible for the blocking of NPM-translocation. It was found that newly synthesized rRNA accumulated in the nuclei during ATP-depletion. Significantly larger than normal nucleoli were also observed. These results indicate that NPM may be involved in the transportation of newly synthesized ribosomes.
Finch
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Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030, USA.
Chan
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D019297:2,4-Dinitrophenol; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000409:Alanine / Q000031:analogs & derivatives / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004140:Dinitrophenols / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D009173:Mycophenolic Acid / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism*; D009697:Nucleolus Organizer Region / Q000378:metabolism*; D000090243:Nucleophosmin; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012270:Ribosomes / Q000378:metabolism; D019810:Sodium Azide
D000903:Antibiotics, Antineoplastic; D001386:Azides; D004140:Dinitrophenols; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; D000090243:Nucleophosmin; C000082:alanosine; D000255:Adenosine Triphosphate; D019810:Sodium Azide; D009173:Mycophenolic Acid; D000409:Alanine; D019297:2,4-Dinitrophenol