https://scholar.dgist.ac.kr/handle/20.500.11750/11725 2026-04-04T14:49:50Z https://scholar.dgist.ac.kr/handle/20.500.11750/58316 Title: The kinase ATM delays Arabidopsis leaf senescence by stabilizing the phosphatase MKP2 in a phosphorylation-dependent manner Author(s): Zhang, Yi; Tan, Shuya; Kim, Jin Hee; Cao, Jie; Zhao, Yaning; Pang, Zhenpei; Liu, Junjie; Lv, Yonglun; Ding, Feng; Kim, Jeongsik; Woo, Hye Ryun; Xia, Xinli; Guo, Hongwei; Li, Zhonghai Abstract: Arabidopsis thaliana (Arabidopsis) Ataxia Telangiectasia Mutated (ATM) kinase plays a vital role in orchestrating leaf senescence; however, the precise mechanisms remain elusive. Here, our study demonstrates that ATM kinase activity is essential for mitigating age- and reactive oxygen species-induced senescence, as restoration of wild-type ATM reverses premature senescence in the atm mutant, while a kinase-dead ATM variant is ineffective. ATM physically interacts with and phosphorylates Mitogen-Activated Protein Kinase Phosphatase 2 (MKP2) to enhance stability under oxidative stress. Mutations in putative phosphorylation sites S15/154 on MKP2 disrupt its phosphorylation, stability, and senescence-delaying function. Moreover, mutation of mitogen-activated protein kinase 6, a downstream target of MKP2, alleviates the premature senescence phenotype of the atm mutant. Notably, the dual-specificity protein phosphatase 19 (HsDUSP19), a predicted human counter protein of MPK2, interacts with both ATM and HsATM and extends leaf longevity in Arabidopsis when overexpressed. These findings elucidate the molecular mechanisms underlying the role of ATM in leaf senescence and suggest that the ATM-MKP2 module is likely evolutionarily conserved in regulating the aging process across eukaryotes. © The Author(s) 2025. 2025-03-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58242 Title: Emerging Regulatory Mechanisms of Leaf Senescence: Insights into Epigenetic Regulators, Non-Coding RNAs, and Peptide Hormones Author(s): Jeong, Ukcheol; Lim, Pyung Ok; Woo, Hye Ryun Abstract: Leaf senescence, the final phase of leaf development, plays a crucial role in plant fitness and crop improvement, as it enables nutrient remobilization from leaves to reproductive organs like developing seeds. This process involves extensive reprogramming of gene expression, governed by intricate regulatory networks operating across multiple layers of control. The employment of systems approaches using omics-based technologies and the characterization of key regulators has been instrumental in uncovering newly emerging regulatory mechanisms, providing valuable insights into how this orderly degeneration process is fine-tuned. In this review, we present a comprehensive overview of the current research on epigenetic mechanisms as a key layer within regulatory networks, influencing transcription factor activity and modulating the expression of senescence-associated genes. We also discuss recent advances in identifying the role of non-coding RNAs, RNA methylation, and peptide hormones during leaf senescence, which contributes to a deeper understanding of the complex regulatory pathways involved. 2025-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/56879 Title: Exploring the feasibility of a single-protoplast proteomic analysis Author(s): Vu, Minh Hung; Lee, Ju Yeon; Kim, Yongmin; Park, Sanghoon; Izaguirre, Fabiana; Lee, Juhyeon; Lee, Jung-Hyun; Jo, Minjoung; Woo, Hye Ryun; Kim, Jin Young; Lim, Pyung Ok; Kim, Min-Sik Abstract: Background: Recent advances in high-resolution mass spectrometry have now enabled the study of proteomes at the single-cell level, offering the potential to unveil novel aspects of cellular processes. Remarkably, there has been no prior attempt to investigate single-plant cell proteomes. In this study, we aimed to explore the feasibility of conducting a proteomic analysis on individual protoplasts. Findings: As a result, our analysis identified 978 proteins from the 180 protoplasts, aligning with well-known biological processes in plant leaves, such as photosynthetic electron transport in photosystem II. Employing the SCP package in the SCoPE2 workflow revealed a notable batch effect and extensive missing values in the data. Following correction, we observed the heterogeneity in single-protoplast proteome expression. Comparing the results of single-protoplast proteomics with those of bulk leaf proteomics, we noted that only a small fraction of bulk data was detected in the single-protoplast proteomics data, highlighting a technical limitation of the current single-cell proteomics method. Conclusions: In summary, we demonstrated the feasibility of conducting a single-protoplast proteomic experiment, revealing heterogeneity in plant cellular proteome expression. This underscores the importance of analyzing a substantial number of plant cells to discern statistically significant changes in plant cell proteomes upon perturbation such as abscisic acid treatment in future studies. We anticipate that our study will contribute to advancing single-protoplast proteomics in the near future. © The Author(s) 2024. 2024-06-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/46546 Title: Histone variant HTB4 delays leaf senescence by epigenetic control of Ib bHLH transcription factor-mediated iron homeostasis Author(s): Yang, Qi; Wang, Ting; Cao, Jie; Wang, Hou-Ling; Tan, Shuya; Zhang, Yuan; Park, Sanghoon; Park, Hyunsoo; Woo, Hye Ryun; Li, Xiaojuan; Xia, Xinli; Guo, Hongwei; Li, Zhonghai Abstract: Leaf senescence is an orderly process regulated by multiple internal factors and diverse environmental stresses including nutrient deficiency. Histone variants are involved in regulating plant growth and development. However, their functions and underlying regulatory mechanisms in leaf senescence remain largely unclear. Here, we found that H2B histone variant HTB4 functions as a negative regulator of leaf senescence. Loss of function of HTB4 led to early leaf senescence phenotypes that were rescued by functional complementation. RNA-seq analysis revealed that several Ib subgroup basic helix–loop–helix (bHLH) transcription factors (TFs) involved in iron (Fe) homeostasis, including bHLH038, bHLH039, bHLH100, and bHLH101, were suppressed in the htb4 mutant, thereby compromising the expressions of FERRIC REDUCTION OXIDASE 2 (FRO2) and IRON-REGULATED TRANSPORTER (IRT1), two important components of the Fe uptake machinery. Chromatin immunoprecipitation-quantitative polymerase chain reaction analysis revealed that HTB4 could bind to the promoter regions of Ib bHLH TFs and enhance their expression by promoting the enrichment of the active mark H3K4me3 near their transcriptional start sites. Moreover, overexpression of Ib bHLH TFs or IRT1 suppressed the premature senescence phenotype of the htb4 mutant. Our work established a signaling pathway, HTB4-bHLH TFs-FRO2/IRT1-Fe homeostasis, which regulates the onset and progression of leaf senescence. © 2023 The Authors New Phytologist © 2023 New Phytologist Foundation. 2023-09-30T15:00:00Z