title: LITTLE NUCLEI genes affecting nuclear morphology in Arabidopsis thaliana.
abstract: Efforts to understand nuclear organization in plant cells have received little assistance from the better-studied animal nuclei, because plant proteomes do not contain recognizable counterparts to the key animal proteins involved in nuclear organization, such as lamin nuclear intermediate filament proteins. Previous studies identified a plant-specific insoluble nuclear protein in carrot (Daucus carota), called Nuclear Matrix Constituent Protein1 (NMCP1), which contains extensive coiled-coil domains and localizes to the nuclear periphery. Here, we describe a genetic characterization of two NMCP1-related nuclear proteins in Arabidopsis thaliana, LITTLE NUCLEI1 (LINC1) and LINC2. Disruption of either gene caused a reduction in nuclear size and altered nuclear morphology. Moreover, combining linc1 and linc2 mutations had an additive effect on nuclear size and morphology but a synergistic effect on chromocenter number (reduction) and whole-plant morphology (dwarfing). The reduction in nuclear size in the linc1 linc2 double mutant was not accompanied by a corresponding change in endopolyploidy. Rather, the density of DNA packaging at all endopolyploid levels in the linc1 linc2 mutants was increased significantly. Our results indicate that the LINC coiled-coil proteins are important determinants of plant nuclear structure.
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA.
authors.forename: Travis A
authors.initials: TA
authors.lastname: Dittmer
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Stacey
authors.forename: Keiko
authors.initials: K
authors.lastname: Sugimoto-Shirasu
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Richards
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism*; D048429:Cell Size; D018744:DNA, Plant / Q000378:metabolism; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010940:Plant Proteins / Q000378:metabolism; D011123:Polyploidy; D021381:Protein Transport
chemical_list: D029681:Arabidopsis Proteins; C525566:At1g13220 protein, Arabidopsis; C525565:At1g67230 protein, Arabidopsis; D018744:DNA, Plant; C105993:NMCP1 protein, Daucus carota; D009687:Nuclear Proteins; D010940:Plant Proteins