title: GIGAS CELL1, a novel negative regulator of the anaphase-promoting complex/cyclosome, is required for proper mitotic progression and cell fate determination in Arabidopsis.
abstract: Increased cellular ploidy is widespread during developmental processes of multicellular organisms, especially in plants. Elevated ploidy levels are typically achieved either by endoreplication or endomitosis, which are often regarded as modified cell cycles that lack an M phase either entirely or partially. We identified GIGAS CELL1 (GIG1)/OMISSION OF SECOND DIVISION1 (OSD1) and established that mutation of this gene triggered ectopic endomitosis. On the other hand, it has been reported that a paralog of GIG1/OSD1, UV-INSENSITIVE4 (UVI4), negatively regulates endoreplication onset in Arabidopsis thaliana. We showed that GIG1/OSD1 and UVI4 encode novel plant-specific inhibitors of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase. These proteins physically interact with APC/C activators, CDC20/FZY and CDH1/FZR, in yeast two-hybrid assays. Overexpression of CDC20.1 and CCS52B/FZR3 differentially promoted ectopic endomitosis in gig1/osd1 and premature occurrence of endoreplication in uvi4. Our data suggest that GIG1/OSD1 and UVI4 may prevent an unscheduled increase in cellular ploidy by preferentially inhibiting APC/C(CDC20) and APC/C(FZR), respectively. Generation of cells with a mixed identity in gig1/osd1 further suggested that the APC/C may have an unexpected role for cell fate determination in addition to its role for proper mitotic progression.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Iwata
authors.forename: Saki
authors.initials: S
authors.lastname: Ikeda
authors.forename: Sachihiro
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Mariko
authors.initials: M
authors.lastname: Kurata
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yoshioka
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Criqui
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Masaki
authors.initials: M
authors.lastname: Ito
mesh_terms: D000483:Alleles; D064173:Anaphase-Promoting Complex-Cyclosome; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D032461:Chromosomes, Plant / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D018548:Cotyledon / Q000235:genetics / Q000378:metabolism; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D048749:Cytokinesis; D004791:Enzyme Inhibitors / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008938:Mitosis; D009154:Mutation; D059828:Plant Cells / Q000378:metabolism; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011003:Ploidies; D011058:Pollen / Q000254:growth & development / Q000378:metabolism; D025941:Protein Interaction Mapping; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C577480:CDC20 protein, Arabidopsis; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D019926:Cyclin B; D004791:Enzyme Inhibitors; D014157:Transcription Factors; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome