title: Cytokinins promote onset of endoreplication by controlling cell cycle machinery.
abstract: The endocycle is a modified cell cycle in which DNA replication is repeated without mitosis or cytokinesis. The resultant DNA polyploidization, termed endoreplication, is usually associated with an increase in cell volume, and it plays an important role in sustaining plant growth and development. The onset the endocycle is caused by a reduction of mitotic CDK activity through selective degradation of mitotic cyclins. In Arabidopsis, CCS52A1 is a substrate-specific activator of an E3 ubiquitin ligase that mediates proteasomal degradation of mitotic cyclins, thereby playing an essential role in transition from the mitotic cell cycle to the endocycle. We have recently reported that the cytokinin-activated transcription factor ARABIDOPSIS RESPONSE REGULATOR 2 (ARR2) binds to and activates the CCS52A1 promoter, and promotes the onset of the endocycle in roots. This regulation is not associated with auxin signaling, demonstrating that cytokinins have a crucial function in programmed induction of endoreplication by directly controlling the cell cycle machinery.
authors.affiliation: a Graduate School of Biological Sciences; Nara Institute of Science and Technology; Takayama, Ikoma, Nara, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Masaaki
authors.initials: M
authors.lastname: Umeda
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002455:Cell Division; D016213:Cyclins / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D004261:DNA Replication; D018744:DNA, Plant / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D062951:Endoreduplication; D018506:Gene Expression Regulation, Plant; D008938:Mitosis; D018517:Plant Roots; D011123:Polyploidy; D011401:Promoter Regions, Genetic; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism
chemical_list: C117139:ARR2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D016213:Cyclins; D003583:Cytokinins; D018744:DNA, Plant; D004268:DNA-Binding Proteins; C540491:FZR2 protein, Arabidopsis; D014157:Transcription Factors; D043743:Ubiquitin-Protein Ligase Complexes; D046988:Proteasome Endopeptidase Complex
keywords: APC/C; CCS52A1; DNA polyploidization; cell cycle; cytokinin; endoreplication; response regulator