title: The mitotic inhibitor ccs52 is required for endoreduplication and ploidy-dependent cell enlargement in plants.
abstract: Plant organs develop mostly post-embryonically from persistent or newly formed meristems. After cell division arrest, differentiation frequently involves endoreduplication and cell enlargement. Factors controlling transition from mitotic cycles to differentiation programmes have not been identified yet in plants. Here we describe ccs52, a plant homologue of APC activators involved in mitotic cyclin degradation. The ccs52 cDNA clones were isolated from Medicago sativa root nodules, which exhibit the highest degree of endopolyploidy in this plant. ccs52 represents a small multigenic family and appears to be conserved in plants. Overexpression of ccs52 in yeast triggered mitotic cyclin degradation, cell division arrest, endoreduplication and cell enlargement. In Medicago, enhanced expression of ccs52 was found in differentiating cells undergoing endoreduplication. In transgenic M.truncatula plants, overexpression of the ccs52 gene in the antisense orientation resulted in partial suppression of ccs52 expression and decreased the number of endocycles and the volume of the largest cells. Thus, the ccs52 product may switch proliferating cells to differentiation programmes which, in the case of endocycles, result in cell size increments.
authors.affiliation: Institut des Sciences Végétales, CNRS, Avenue de la Terrasse, 91198 Gif sur Yvette, France.
authors.forename: A
authors.initials: A
authors.lastname: Cebolla
authors.forename: J M
authors.initials: JM
authors.lastname: Vinardell
authors.forename: E
authors.initials: E
authors.lastname: Kiss
authors.forename: B
authors.initials: B
authors.lastname: Oláh
authors.forename: F
authors.initials: F
authors.lastname: Roudier
authors.forename: A
authors.initials: A
authors.lastname: Kondorosi
authors.forename: E
authors.initials: E
authors.lastname: Kondorosi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002454:Cell Differentiation; D002455:Cell Division; D048429:Cell Size; D019926:Cyclin B / Q000378:metabolism; D005656:Fungal Proteins / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006801:Humans; D000455:Medicago sativa / Q000235:genetics; D008938:Mitosis; D008969:Molecular Sequence Data; D005810:Multigene Family; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified; D011003:Ploidies; D012091:Repetitive Sequences, Nucleic Acid; D012568:Schizosaccharomyces; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: D018797:Cell Cycle Proteins; D019926:Cyclin B; D005656:Fungal Proteins; D010940:Plant Proteins; D029702:Schizosaccharomyces pombe Proteins; C121327:ccs52 protein, Medicago sativa; C113000:srw1 protein, S pombe