Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1104/pp.114.242628

Language：English   Publishing type：Research paper (scientific journal)  

DOI： Lacking chloroplasts in guard cells of crumpled leaf attenuates

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Endomitosis and endoreplication are atypical modes of cell cycle that results in genome duplication in single nucleus. Because the cell size of given cell type is generally proportional to the nuclear DNA content, endoreplication and endomitosis are effective strategy of cell growth, which are widespread in multicellular organisms, especially those in plant kingdom. We found that these processes might be differently regulated by GIGAS CELL1 (GIG1) and its paralog UV-INSENSITIVE4 (UVI4) in Arabidopsis thaliana. GIG1 and UVI4 may negatively regulate activities of anaphase-promoting complex or cyclosome (APC/C) ubiquitin ligase that acts as an important mitotic regulator. The gig1 mutation induced ectopic occurrence of endomitosis during somatic cell division, while it has been reported that uvi4 mutation resulted in premature occurrence of endoreplication during organ development. Overexpression of GIG1 and UVI4 dramatically increased the amount of mitotic cyclin, CYCB1;1, a well-known substrate of APC/C. Ectopic endomitosis in gig1 was enhanced by mutation in CYCB2;2 and suppressed by downregulation of APC10 encoding a core subunit of APC/C. Overexpression of CDC20.1, an activator protein of APC/C, further promoted the ectopic endomitosis in gig1. These findings suggest that endomitosis and endoreplication are regulated by similar molecular mechanisms, in which two related proteins, GIG1 and UVI4, may inhibit APC/C in different ways.

Language：English   Publishing type：Research paper (scientific journal)  

Plastid division is controlled by numerous nuclear genes. Arabidopsis thaliana CRUMPLED LEAF (AtCRL) is a plastid division-related gene, and the crl mutant exhibits a dwarf phenotype with abnormal cell division and a significant re- duction in plastid numbers. However, the function of AtCRL is not fully understood. Here, we identified and character- ized two AtCRL homologs, PpCRL1 and PpCRL2, in the moss Physcomitrella patens. PpCRL1 and PpCRL2 shared 77% amino acid identity with each other and 47% identity with AtCRL. Single PpCRL1 or -2 gene knockout (KO) mutants could not be distinguished from the wild-type mosses, but PpCRL1 and -2 double KO mutants displayed growth retard- ation of protonemata and gametophores and harbored ap- proximately 10 large chloroplasts per cell. This indicates that PpCRL1 and PpCRL2 have redundant functions in chloroplast division and plant growth. Unlike the A. thaliana crl mu- tants, however, the PpCRL double KO mutants did not dis- play abnormal orientation of the cell division plane. Complementation experiments showed that AtCRL partially rescued the defects in chloroplast size and number of the PpCRL double KO mutant. This suggests that PpCRL has a similar, but not identical, function to AtCRL. Time-lapse microscopic observation of the double PpCRL KO mutants revealed that some dumbbell-shaped chloroplasts failed to complete division at the late stage of plastid division; enlarged chloroplasts were thus generated. This strongly suggests that PpCRLs are involved in the complete separ- ation of dividing chloroplasts.

Language：English   Publishing type：Research paper (scientific journal)  

Occurrence of increased cellular ploidy is widespread in 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 cycle lacking M phase entirely or partially. We have identified GIGAS CELL1 (GIG1)/OMISSION OF SECOND DIVISION1 (OSD1) whose mutation triggered ectopic endomitosis, whereas it has been reported that its paralog, UV-INSENSITIVE4 (UVI4), negatively regulates endoreplication onset in Arabidopsis thaliana. We showed that GIG1/OSD1 and UVI4 encode novel plant-specific inhibitors of anaphase-promoting complex or 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 two related proteins, GIG1/OSD1 and UVI4, may prevent unscheduled increase of cellular ploidy by preferentially inhibiting APC/CCDC20 and APC/CFZR, respectively. Generation of cells with a mixed identity in gig1/osd1 further suggested that APC/C may have an unexpected role for cell fate determination in addition to its role for proper mitotic progression.

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Event date： 2020.3

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン  

Event date： 2019.10

Language：English   Presentation type：Symposium, workshop panel (nominated)  

Country：Indonesia  

Event date： 2019.10

Language：English   Presentation type：Poster presentation  

Country：Indonesia  

Event date： 2019.10

Language：English   Presentation type：Oral presentation (general)  

Country：Indonesia  

Event date： 2019.10

Language：English   Presentation type：Oral presentation (general)  

Country：Indonesia  

Event date： 2019.3

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋大学  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場   Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋大学  

Event date： 2017.12

Language：English   Presentation type：Oral presentation (general)  

Venue：神戸市  

Event date： 2017.3

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

PpCRL1 and PpCRL2 genes of Physcomitrella patens function redundantly in progression of chloroplast division and plants' growth. To reveal the role of these genes in chloroplast division, we conducted a time-lapse live-imaging of chloroplast division in Ppcrl1 Ppcrl2 double knock out line (Δ1/2). We observed chloroplasts in gametophores every hour under a confocal microscope and found that chloroplasts in Δ1/2 divided in a similar fashion to wild type. However, divided two chloroplasts were interconnected via a filamentous structure that was visualized by an envelop-localized GFP. We also observed that chloroplasts interconnected via the filamentous structures were fused and became a round shape chloroplast. The frequency of chloroplast fusion in Δ1/2 was 0.13 cell^-1 hr^-1. Neither filamentous structures nor chloroplast fusion were observed both in wild type and a PpFtsZ2-1 knock out line that is defective in chloroplast division. These results suggest that chloroplasts of Δ1/2 can divide but fail to separate into two daughter chloroplasts, thereby enlarging. PpCRL genes may be involved in the separation process of two daughter chloroplasts.

Event date： 2017.3

Language：English   Presentation type：Poster presentation  

Country：Japan  

Abiotic stresses affect chloroplast division and morphology of chloroplasts in the moss, Physcomitrella patens. Previous data and also our observation showed that ampicillin, an inhibitor of peptidoglycan synthesis, inhibited chloroplast division and resulted in the appearance of macrochloroplasts in the moss. The results suggest that the peptidoglycan synthesis positively regulates chloroplast division. Interestingly, chloroplast division in the bryophytes may be an intermediate between the cyanobacteria and the vascular plants, but the mechanisms are still unclear.
In this work we examined the relationship between ABA and peptidoglycan synthesis on chloroplast division of the moss, P. patens. We found that chloroplast numbers in the wild type increased under ABA plus ampicillin treatment. Moreover, ABA also increased the number of chloroplasts in the peptidoglycan knockout mutants and the mid-chloroplast FtsZ rings knockout mutant. The results suggest that ABA may act independently of peptidoglycan synthesis pathway and FtsZ to control chloroplast division. To prove our hypothesis and find a novel pathway of chloroplast division, observation of ABA signaling overexpression lines is in progress.

Event date： 2016.3

Language：Japanese   Presentation type：Poster presentation  

Venue：岩手大学（岩手県）   Country：Japan  

シロイヌナズナのCRUMPLED LEAF (CRL)は、色素体分裂、植物の生長・形態形成に関与する陸上 植物に保存された遺伝子であり、色素体外包膜とミトコンドリアとに局在するタンパク質をコードしている。これまでに我々はin vivoプルダウンアッセイによってCRL-GFPと相互作用するタンパク質候補として、atTOC75-IIIとPROHIBITIN3(PHB3)とを同定した。今回、我々はAlphaScreenによってCRLとPHB3, atTOC75-IIIとの相互作用を確認した。また、atTOC75-III-GFPの過剰発現によってcrl-1の地上部の成長と稔性が部分的に回復する事を見いだした。atTOC75-IIIは葉緑体へのタンパク質輸送に関与する外包膜局在タンパク質であるが、この結果から、atTOC75-IIIの機能低下がcrl-1における稔性低下と成長阻害の原因の１つである可能性が考えられる。PHB3は過酸化水素による一酸化窒素(NO)の生成誘導に関与するミトコンドリア局在タンパク質であり、低濃度のNOは細胞分裂を促進することが報告されている。我々は昨年の本年会において過酸化水素によるNOの生成誘導および内在NO量が、crl-1変異体では野生型に比べて低下していること、および、NO供与剤SNPの添加によって、crl-1の根におけるG2/M期のマーカー遺伝子CYCB1;1-GUS発現が野生型とほぼ同程度に回復する事を報告している。以上の事からcrl-1で観察される成長阻害には葉緑体とミトコンドリアの両方の要因が関与すると考えられる。

Event date： 2015.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東京農業大学（東京都）   Country：Japan  

Event date： 2013.3

Language：Japanese   Presentation type：Poster presentation  

Venue：岡山大学   Country：Japan  

Event date： 2013.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山大学   Country：Japan  

Event date： 2012.3

Language：Japanese   Presentation type：Poster presentation  

Venue：京都産業大学   Country：Japan  

Event date： 2012.3

Language：Japanese   Presentation type：Poster presentation  

Venue：京都産業大学   Country：Japan  

Event date： 2011.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京大学駒場キャンパス   Country：Japan  

Event date： 2011.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：要旨集   Country：Japan  

Event date： 2011.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：要旨集   Country：Japan  

Event date： 2011.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：要旨集   Country：Japan  

Event date： 2011.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：要旨集   Country：Japan  

Event date： 2010.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2010.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan