title: Lamin B1 maintains the functional plasticity of nucleoli.
abstract: The dynamic ability of genomes to interact with discrete nuclear compartments appears to be essential for chromatin function. However, the extent to which structural nuclear proteins contribute to this level of organization is largely unresolved. To test the links between structure and function, we evaluated how nuclear lamins contribute to the organization of a major functional compartment, the nucleolus. HeLa cells with compromised expression of the genes encoding lamins were analyzed using high-resolution imaging and pull-down assays. When lamin B1 expression was depleted, inhibition of RNA synthesis correlated with complex structural changes within the nucleolar active centers until, eventually, the nucleoli were dispersed completely. With normal lamin expression, the nucleoli were highly plastic, with dramatic and freely reversible structural changes correlating with the demand for ribosome biogenesis. Preservation of the nucleolar compartment throughout these structural transitions is shown to be linked to lamin B1 expression, with the lamin B1 protein interacting with the major nucleolar protein nucleophosmin/B23.
authors.affiliation: Faculty of Life Sciences, University of Manchester, MIB, 131 Princess Street, Manchester M1 7DN, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: Martin
authors.forename: Songbi
authors.initials: S
authors.lastname: Chen
authors.forename: Apolinar
authors.initials: A
authors.lastname: Maya-Mendoza
authors.forename: Josip
authors.initials: J
authors.lastname: Lovric
authors.forename: Paul F G
authors.initials: PF
authors.lastname: Sims
authors.forename: Dean A
authors.initials: DA
authors.lastname: Jackson
mesh_terms: D002466:Cell Nucleolus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006367:HeLa Cells; D006801:Humans; D034904:Lamin Type A / Q000378:metabolism; D034921:Lamin Type B / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D000090243:Nucleophosmin; D012313:RNA / Q000096:biosynthesis*; D034622:RNA Interference; D012335:RNA, Ribosomal / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D034904:Lamin Type A; D034921:Lamin Type B; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; D034741:RNA, Small Interfering; C440308:lamin C; D000090243:Nucleophosmin; D012313:RNA; D012321:DNA-Directed RNA Polymerases