title: Characterization of nuclear compartments identified by ectopic markers in mammalian cells with distinctly different karyotype.
abstract: The functional organization of chromatin in cell nuclei is a fundamental question in modern cell biology. Individual chromosomes occupy distinct chromosome territories in interphase nuclei. Nuclear bodies localize outside the territories and colocalize with ectopically expressed proteins in a nuclear subcompartment, the interchromosomal domain compartment. In order to investigate the structure of this compartment in mammalian cells with distinctly different karyotypes, we analyzed human HeLa cells (3n+ = 71 chromosomes) and cells of two closely related muntjac species, the Chinese muntjac (2n = 46 chromosomes) and the Indian muntjac (2n = 6/7 chromosomes). The distribution of ectopically expressed intermediate filament proteins (vimentin and cytokeratins) engineered to contain a nuclear localization sequence (NLS) and a nuclear particle forming protein (murine Mx1) fused to a yellow fluorescent protein (YFP) was compared. The proteins were predominantly localized in regions with poor DAPI staining independent of the cells' karyotype. In contrast to NLS-vimentin, the NLS-modified cytokeratins were also found close to the nuclear periphery. In Indian muntjac cells, NLS-vimentin colocalized with Mx1-YFP as well as the NLS-cytokeratins. Since the distribution of the ectopically expressed protein markers is similar in cells with distinctly different chromosome numbers, the property of the delineated, limited compartment might indeed depend on chromatin organization.
authors.affiliation: Division of Molecular Genetics, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
authors.forename: Markus O
authors.initials: MO
authors.lastname: Scheuermann
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Murmann
authors.forename: Karsten
authors.initials: K
authors.lastname: Richter
authors.forename: Sabine M
authors.initials: SM
authors.lastname: Görisch
authors.forename: Harald
authors.initials: H
authors.lastname: Herrmann
authors.forename: Peter
authors.initials: P
authors.lastname: Lichter
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002451:Cell Compartmentation / Q000502:physiology*; D002467:Cell Nucleus / Q000502:physiology* / Q000648:ultrastructure; D002877:Chromosomes, Human / Q000502:physiology / Q000648:ultrastructure; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D007621:Karyotyping; D007633:Keratins / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000737:chemistry* / Q000235:genetics; D051379:Mice; D018668:Muntjacs / Q000235:genetics*; D064547:Myxovirus Resistance Proteins; D019913:Nuclear Localization Signals / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D014746:Vimentin / Q000235:genetics / Q000378:metabolism; D014981:Xenopus
chemical_list: D001426:Bacterial Proteins; D008164:Luminescent Proteins; C579070:Mx1 protein, mouse; D064547:Myxovirus Resistance Proteins; D019913:Nuclear Localization Signals; D011993:Recombinant Fusion Proteins; D014746:Vimentin; C054562:yellow fluorescent protein, Bacteria; D007633:Keratins; D019204:GTP-Binding Proteins