title: Potential role of the rice OsCCS52A gene in endoreduplication.
abstract: In eukaryotes, the cell cycle consists of four distinct phases: G1, S, G2 and M. In certain condition, the cells skip M-phase and undergo endoreduplication. Endoreduplication, occurring during a modified cell cycle, duplicates the entire genome without being followed by M-phase. A cycle of endoreduplication is common in most of the differentiated cells of plant vegetative tissues and it occurs extensively in cereal endosperm cells. Endoreduplication occurs when CDK/Cyclin complex low or inactive caused by ubiquitin-mediated degradation by APC and their activators. In this study, rice cell cycle switch 52 A (OsCCS52A), an APC activator, is functionally characterized using the reverse genetic approach. In rice, OsCCS52A is highly expressed in seedlings, flowers, immature panicles and 15 DAP kernels. Localization studies revealed that OsCCS52A is a nuclear protein. OsCCS52A interacts with OsCdc16 in yeast. In addition, overexpression of OsCCS52A inhibits mitotic cell division and induces endoreduplication and cell elongation in fission yeast. The homozygous mutant exhibits dwarfism and smaller seeds. Further analysis demonstrated that endoreduplication cycles in the endosperm of mutant seeds were disturbed, evidenced by reduced nuclear and cell sizes. Taken together, these results suggest that OsCCS52A is involved in maintaining normal seed size formation by mediating the exit from mitotic cell division to enter the endoreduplication cycles in rice endosperm.
authors.affiliation: Division of Applied Life Science, BK21 Program, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Mukhamad
authors.initials: M
authors.lastname: Su'udi
authors.forename: Joon-Yung
authors.initials: JY
authors.lastname: Cha
authors.forename: Min Hee
authors.initials: MH
authors.lastname: Jung
authors.forename: Netty
authors.initials: N
authors.lastname: Ermawati
authors.forename: Chang-deok
authors.initials: CD
authors.lastname: Han
authors.forename: Min Gab
authors.initials: MG
authors.lastname: Kim
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Woo
authors.forename: Daeyoung
authors.initials: D
authors.lastname: Son
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D049108:Cell Enlargement; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D048429:Cell Size; D003001:Cloning, Molecular; D018556:Crops, Agricultural / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D056625:Endosperm / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008938:Mitosis; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames; D012275:Oryza / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D035261:Plant Components, Aerial / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D054817:Pollination; D018749:RNA, Plant / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D014170:Transformation, Genetic; D020798:Two-Hybrid System Techniques; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D010940:Plant Proteins; D018749:RNA, Plant; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome