Browsing by Author "Jae Yong, Yoo"

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    CELL CYCLE ARREST MEDIATED BY WEE1 IS INVOLVED IN THE UNFOLDED PROTEIN RESPONSE IN PLANTS
    (2018-09-10) Ki Seong, Ko; Jae Yong, Yoo; Nirmal Kumar, Ramasamy; Rikno, Harmoko; Bích Ngọc, Thị Vũ; Ji Ye, Park; Kyun, Oh Lee
    Activation of the unfolded protein response (UPR) in mammalian cells leads to cell cycle arrest at the G1 phase (Thomas et al., J Biol Chem 288:7606–7617, 2013). However, how UPR signaling affects cell cycle arrest remains largely unknown in plants. Here, we examined UPR and endoreduplication in Col-0, wee1, and ER stress sensing-deficient ire1a&b plants during DNA replication and ER stress conditions. We found that WEE1, an essential negative regulator of the cell cycle, is involved in the maintenance of ER homeostasis during genotoxic stress and the ER stress hypersensitivity of ire1a&b is alleviated by loss-of-function mutation in WEE1. WEE1-mediated cell cycle arrest was required for IRE1–bZIP60 pathway activation during ER stress. In contrast, loss-of-function mutation in WEE1 caused increased expression of UPR-related genes during DNA replication stress. WEE1 and IRE1 were required for endoreduplication during DNA replication stress and ER stress, respectively. Taken together, these findings suggest that cell cycle regulation is associated with UPR activation in different manners during ER stress and DNA replication stress in Arabidopsis.
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    N-GLYCAN CONTAINING A CORE Α1,3-FUCOSE RESIDUE IS REQUIRED FOR BASIPETAL AUXIN TRANSPORT AND GRAVITROPIC RESPONSE IN RICE (ORYZA SATIVA)
    (2016-05-31) Rikno, Harmoko; Jae Yong, Yoo; Ki Seong, Ko; Nirmal Kumar, Ramasamy; Bo Young, Hwang; Eun, Ji Lee; Ho Soo, Kim; Kyung, Jin Lee; Doo-Byoung, Oh; Dool, -Yi Kim; Sanghun, Lee; Yang, Li; Sang Yeol, Lee; Kyun, Oh Lee
    In plants, α1,3-fucosyltransferase (FucT) catalyzes the transfer of fucose from GDP-fucose to asparagine-linked GlcNAc of the N-glycan core in the medial Golgi. To explore the physiological significance of this processing, we isolated two Oryza sativa (rice) mutants (fuct-1 and fuct-2) with loss of FucT function. Biochemical analyses of the N-glycan structure confirmed that α1,3-fucose is missing from the N-glycans of allelic fuct-1 and fuct-2. Compared with the wild-type cv Kitaake, fuct-1 displayed a larger tiller angle, shorter internode and panicle lengths, and decreased grain filling as well as an increase in chalky grains with abnormal shape. The mutant allele fuct-2 gave rise to similar developmental abnormalities, although they were milder than those of fuct-1. Restoration of a normal tiller angle in fuct-1 by complementation demonstrated that the phenotype is caused by the loss of FucT function. Both fuct-1 and fuct-2 plants exhibited reduced gravitropic responses. Expression of the genes involved in tiller and leaf angle control was also affected in the mutants. We demonstrate that reduced basipetal auxin transport and low auxin accumulation at the base of the shoot in fuct-1 account for both the reduced gravitropic response and the increased tiller angle.