title: Increased level of polyploidy1, a conserved repressor of CYCLINA2 transcription, controls endoreduplication in Arabidopsis.
abstract: Endoreduplication is a type of cell cycle in which DNA replication continues without cell division. We have isolated several dominant mutants from Arabidopsis thaliana activation tagging lines by flow cytometry. One of the mutants, increased level of polyploidy1-1D (ilp1-1D), showed increased polyploidy in both light- and dark-grown hypocotyls. The corresponding gene of ilp1-1D encodes a protein homologous to the C-terminal region of mammalian GC binding factor. We demonstrate that this protein functions as a transcriptional repressor in vivo. The expression of all members of the CYCLINA2 (CYCA2) family was reduced in an ILP1 overexpressing line, and the mouse (Mus musculus) homolog of ILP1 repressed cyclin A2 expression in mouse NIH3T3 cells. T-DNA insertion mutants of ILP1 showed reduced polyploidy and upregulated all CYCA2 expression. Furthermore, loss of CYCA2;1 expression induces an increase in polyploidy in Arabidopsis. We demonstrate that this protein regulates endoreduplication through control of CYCA2 expression in Arabidopsis.
authors.affiliation: Plant Functional Genomics Research Team, Plant Functional Genomics Research Group, Plant Science Center RIKEN Yokohama Institute, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yoshizumi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tsumoto
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takiguchi
authors.forename: Noriko
authors.initials: N
authors.lastname: Nagata
authors.forename: Yoshiharu Y
authors.initials: YY
authors.lastname: Yamamoto
authors.forename: Mika
authors.initials: M
authors.lastname: Kawashima
authors.forename: Takanari
authors.initials: T
authors.lastname: Ichikawa
authors.forename: Miki
authors.initials: M
authors.lastname: Nakazawa
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Minami
authors.initials: M
authors.lastname: Matsui
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D017931:DNA Primers; D004261:DNA Replication; D003624:Darkness; D008027:Light; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D012097:Repressor Proteins / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; D012097:Repressor Proteins