業績情報

• The deficiency of methylglyoxal synthase promotes cell proliferation in Synechocystis sp. PCC 6803 under mixotrophic conditions　　　　　　　　　　　　　　　
  Aikeranmu Kadeer; Yuuma Ishikawa; Kaushalya Dayarathne; Atsuko Miyagi; Toshiki Ishikawa; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Plant Biotechnology, 巻：41, 号：4, 開始ページ：393, 終了ページ：399, 2024年12月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.24.0718a
  DOI ID：10.5511/plantbiotechnology.24.0718a
• Accumulation of acyl plastoquinol and triacylglycerol in six cyanobacterial species with different sets of genes encoding type-2 diacylglycerol acyltransferase-like proteins
  Riko Tanikawa; Haruna Sakaguchi; Toshiki Ishikawa; Yukako Hihara
  Plant And Cell Physiology, 巻：66, 号：1, 開始ページ：15, 終了ページ：22, 2024年11月, ［査読有り］
  Abstract
  
  Recently, acyl plastoquinol (APQ) and plastoquinone-B (PQ-B), which are fatty acid esters of plastoquinol and plastoquinone-C respectively, have been identified as the major neutral lipids in cyanobacteria. In Synechocystis sp. PCC 6803, Slr2103 having homology with the eukaryotic enzyme for triacylglycerol (TAG) synthesis, diacylglycerol acyltransferase 2 (DGAT2), was identified as responsible for the synthesis of these plastoquinone-related lipids. On the other hand, TAG synthesis in cyanobacteria remains controversial due to the low accumulation level within cyanobacterial cells together with the high contamination level from the environment. In this study, to quantify more precisely and elucidate the relationship between the accumulation of neutral lipids and the presence or absence of DGAT2-like genes, plastoquinone-related lipids and TAG were analyzed directly from total lipids of six cyanobacterial species with different sets of genes encoding DGAT2-like proteins belonging to two distinct subclades. The results showed that the synthesis of these neutral lipids is highly dependent on clade A DGAT2-like proteins under the culture conditions used in this study, although accumulation level of TAG was quite low. In contrast to APQ highly abundant in saturated fatty acids, the fatty acid composition of TAG was species-specific and partly reflected the total lipid composition. Gloeobacter violaceus PCC 7421, which lacks a DGAT2-like gene, accumulated APQ with a high proportion of C18:0, suggesting APQ synthesis by an unidentified acyltransferase.
  Oxford University Press (OUP), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcae137
  DOI ID：10.1093/pcp/pcae137, ISSN：0032-0781, eISSN：1471-9053
• Arabidopsis DREB26/ERF12 and its close relatives regulate cuticular wax biosynthesis under drought stress condition.　　　　　　　　　　　　　　　
  Kaoru Urano; Yoshimi Oshima; Toshiki Ishikawa; Takuma Kajino; Shingo Sakamoto; Mayuko Sato; Kiminori Toyooka; Miki Fujita; Maki Kawai-Yamada; Teruaki Taji; Kyonoshin Maruyama; Kazuko Yamaguchi-Shinozaki; Kazuo Shinozaki
  The Plant journal : for cell and molecular biology, 2024年10月, ［査読有り］, ［国際誌］
  Land plants have evolved a hydrophobic cuticle on the surface of aerial organs as an adaptation to ensure survival in terrestrial environments. Cuticle is mainly composed of lipids, namely cutin and intracuticular wax, with epicuticular wax deposited on plant surface. The composition and permeability of cuticle have a large influence on its ability to protect plants against drought stress. However, the regulatory mechanisms underlying cuticular wax biosynthesis in response to drought stress have not been fully elucidated. Here, we identified three AP2/ERF transcription factors (DREB26/ERF12, ERF13 and ERF14) involved in the regulation of water permeability of the plant surface. Transmission electron microscopy revealed thicker cuticle on the leaves of DREB26-overexpressing (DREB26OX) plants, and thinner cuticle on the leaves of transgenic plants expressing SRDX repression domain-fused DREB26 (DREB26SR). Genes involved in cuticular wax formation were upregulated in DREB26OX and downregulated in DREB26SR. The levels of very-long chain (VLC) alkanes, which are a major wax component, increased in DREB26OX leaves and decreased in DREB26SR leaves. Under dehydration stress, water loss was reduced in DREB26OX and increased in DREB26SR. The erf12/13/14 triple mutant showed delayed growth, decreased leaf water content, and reduced drought-inducible VLC alkane accumulation. Taken together, our results indicate that the DREB26/ERF12 and its closed family members, ERF13 and ERF14, play an important role in cuticular wax biosynthesis in response to drought stress. The complex transcriptional cascade involved in the regulation of cuticular wax biosynthesis under drought stress conditions is discussed.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/tpj.17100
  DOI ID：10.1111/tpj.17100, PubMed ID：39466828
• The effect of light availability and light wavelength on growth, 2-MIB biosynthesis, and 2-MIB-related gene expression in Pseudanabaena foetida var. intermedia.　　　　　　　　　　　　　　　
  Kaushalya Dayarathne; Toshiki Ishikawa; Aikeranmu Kadeer; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Archives of microbiology, 巻：206, 号：9, 開始ページ：367, 終了ページ：367, 2024年08月, ［査読有り］, ［国際誌］
  2-methylisoborneol (2-MIB) is an odiferous metabolite mainly produced by cyanobacteria, contributing to taste and odor problems in drinking water. The mechanisms involved in 2-MIB biosynthesis in cyanobacteria are not yet completely understood. This study investigated the effect of light availability and wavelength on growth, 2-MIB synthesis, and related gene expression in Pseudanabaena foetida var. intermedia. A significantly lower 2-MIB production was observed in P. foetida var. intermedia during the dark period of a 12-h photoperiod. Exposure to green light resulted in a significant decrease in 2-MIB production compared to white light and red light. The relative expression levels of 2-MIB-related genes in P. foetida var. intermedia were significantly lower during the dark period of a 12-h photoperiod and when cultured under green light. The expression of 2-MIB-related genes in cyanobacteria appears to be light-dependent. This study suggests that the demand for photopigment synthesis under unfavorable light conditions affects the 2-MIB synthesis in cyanobacteria.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00203-024-04099-w
  DOI ID：10.1007/s00203-024-04099-w, PubMed ID：39105810
• Inhibitor of cardiolipin biosynthesis‐related enzyme MoGep4 confers broad‐spectrum anti‐fungal activity　　　　　　　　　　　　　　　
  Peng Sun; Juan Zhao; Gan Sha; Yaru Zhou; Mengfei Zhao; Renjian Li; Xiaojing Kong; Qiping Sun; Yun Li; Ke Li; Ruiqing Bi; Lei Yang; Ziting Qin; Wenzheng Huang; Yin Wang; Jie Gao; Guang Chen; Haifeng Zhang; Muhammad Adnan; Long Yang; Lu Zheng; Xiao‐Lin Chen; Guanghui Wang; Toshiki Ishikawa; Qiang Li; Jin‐Rong Xu; Guotian Li
  Plant, Cell & Environment, 巻：47, 号：11, 開始ページ：4259, 終了ページ：4274, 2024年07月, ［査読有り］
  Abstract
  
  Plant pathogens cause devastating diseases, leading to serious losses to agriculture. Mechanistic understanding of pathogenesis of plant pathogens lays the foundation for the development of fungicides for disease control. Mitophagy, a specific form of autophagy, is important for fungal virulence. The role of cardiolipin, mitochondrial signature phospholipid, in mitophagy and pathogenesis is largely unknown in plant pathogenic fungi. The functions of enzymes involved in cardiolipin biosynthesis and relevant inhibitors were assessed using a set of assays, including genetic deletion, plant infection, lipidomics, chemical‐protein interaction, chemical inhibition, and field trials. Our results showed that the cardiolipin biosynthesis‐related gene MoGEP4 of the rice blast fungus Magnaporthe oryzae regulates growth, conidiation, cardiolipin biosynthesis, and virulence. Mechanistically, MoGep4 regulated mitophagy and Mps1‐MAPK phosphorylation, which are required for virulence. Chemical alexidine dihydrochloride (AXD) inhibited the enzyme activity of MoGep4, cardiolipin biosynthesis and mitophagy. Importantly, AXD efficiently inhibited the growth of 10 plant pathogens and controlled rice blast and Fusarium head blight in the field. Our study demonstrated that MoGep4 regulates mitophagy, Mps1 phosphorylation and pathogenesis in M. oryzae. In addition, we found that the MoGep4 inhibitor, AXD, displays broad‐spectrum antifungal activity and is a promising candidate for fungicide development.
  Wiley, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/pce.15021
  DOI ID：10.1111/pce.15021, ISSN：0140-7791, eISSN：1365-3040, PubMed ID：38946254
• Characterization of Unique Eukaryotic Sphingolipids with Temperature-Dependent Δ8-Unsaturation from the Picoalga Ostreococcus tauri.　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Frédéric Domergue; Alberto Amato; Florence Corellou
  Plant & cell physiology, 巻：65, 号：6, 開始ページ：1029, 終了ページ：1046, 2024年06月, ［査読有り］, ［国内誌］
  Sphingolipids (SLs) are ubiquitous components of eukaryotic cell membranes and are found in some prokaryotic organisms and viruses. They are composed of a sphingoid backbone that may be acylated and glycosylated. Assembly of various sphingoid base, fatty acyl and glycosyl moieties results in highly diverse structures. The functional significance of variations in SL chemical diversity and abundance is still in the early stages of investigation. Among SL modifications, Δ8-desaturation of the sphingoid base occurs only in plants and fungi. In plants, SL Δ8-unsaturation is involved in cold hardiness. Our knowledge of the structure and functions of SLs in microalgae lags far behind that of animals, plants and fungi. Original SL structures have been reported from microalgae. However, functional studies are still missing. Ostreococcus tauri is a minimal microalga at the base of the green lineage and is therefore a key organism for understanding lipid evolution. In the present work, we achieved the detailed characterization of O. tauri SLs and unveiled unique glycosylceramides as sole complex SLs. The head groups are reminiscent of bacterial SLs, as they contain hexuronic acid residues and can be polyglycosylated. Ceramide backbones show a limited variety, and SL modification is restricted to Δ8-unsaturation. The Δ8-SL desaturase from O. tauri only produced E isomers. Expression of both Δ8-SL desaturase and Δ8-unsaturation of sphingolipids varied with temperature, with lower levels at 24°C than at 14°C. Overexpression of the Δ8-SL desaturase dramatically increases the level of Δ8 unsaturation at 24°C and is paralleled by a failure to increase cell size. Our work provides the first characterization of O. tauri SLs and functional evidence for the involvement of SL Δ8-unsaturation for temperature acclimation in microalgae, suggesting that this function is an ancestral feature in the green lineage.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcae007
  DOI ID：10.1093/pcp/pcae007, PubMed ID：38252418
• High Myristic Acid in Glycerolipids Enhances the Repair of Photodamaged Photosystem II under Strong Light.　　　　　　　　　　　　　　　
  Kazuki Kurima; Haruhiko Jimbo; Takashi Fujihara; Masakazu Saito; Toshiki Ishikawa; Hajime Wada
  Plant & cell physiology, 巻：65, 号：5, 開始ページ：790, 終了ページ：797, 2024年05月, ［査読有り］, ［国内誌］
  Cyanobacteria inhabit areas with a broad range of light, temperature and nutrient conditions. The robustness of cyanobacterial cells, which can survive under different conditions, may depend on the resilience of photosynthetic activity. Cyanothece sp. PCC 8801 (Cyanothece), a freshwater cyanobacterium isolated from a Taiwanese rice field, had a higher repair activity of photodamaged photosystem II (PSII) under intense light than Synechocystis sp. PCC 6803 (Synechocystis), another freshwater cyanobacterium. Cyanothece contains myristic acid (14:0) as the major fatty acid at the sn-2 position of the glycerolipids. To investigate the role of 14:0 in the repair of photodamaged PSII, we used a Synechocystis transformant expressing a T-1274 encoding a lysophosphatidic acid acyltransferase (LPAAT) from Cyanothece. The wild-type and transformant cells contained 0.2 and 20.1 mol% of 14:0 in glycerolipids, respectively. The higher content of 14:0 in the transformants increased the fluidity of the thylakoid membrane. In the transformants, PSII repair was accelerated due to an enhancement in the de novo synthesis of D1 protein, and the production of singlet oxygen (1O2), which inhibited protein synthesis, was suppressed. The high content of 14:0 increased transfer of light energy received by phycobilisomes to PSI and CP47 in PSII and the content of carotenoids. These results indicated that an increase in 14:0 reduced 1O2 formation and enhanced PSII repair. The higher content of 14:0 in the glycerolipids may be required as a survival strategy for Cyanothece inhabiting a rice field under direct sunlight.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcae021
  DOI ID：10.1093/pcp/pcae021, PubMed ID：38441322, PubMed Central ID：PMC11138363
• The phosphorylated pathway of serine biosynthesis affects sperm, embryo, and sporophyte development, and metabolism in Marchantia polymorpha　　　　　　　　　　　　　　　
  Mengyao Wang; Hiromitsu Tabeta; Kinuka Ohtaka; Ayuko Kuwahara; Ryuichi Nishihama; Toshiki Ishikawa; Kiminori Toyooka; Mayuko Sato; Mayumi Wakazaki; Hiromichi Akashi; Hiroshi Tsugawa; Tsubasa Shoji; Yozo Okazaki; Keisuke Yoshida; Ryoichi Sato; Ali Ferjani; Takayuki Kohchi; Masami Yokota Hirai
  Communications Biology, 巻：7, 号：1, 開始ページ：102, 終了ページ：102, 2024年01月, ［査読有り］, ［国際誌］
  Abstract
  
  Serine metabolism is involved in various biological processes. Here we investigate primary functions of the phosphorylated pathway of serine biosynthesis in a non-vascular plant Marchantia polymorpha by analyzing knockout mutants of MpPGDH encoding 3-phosphoglycerate dehydrogenase in this pathway. Growth phenotypes indicate that serine from the phosphorylated pathway in the dark is crucial for thallus growth. Sperm development requires serine from the phosphorylated pathway, while egg formation does not. Functional MpPGDH in the maternal genome is necessary for embryo and sporophyte development. Under high CO₂ where the glycolate pathway of serine biosynthesis is inhibited, suppressed thallus growth of the mutants is not fully recovered by exogenously-supplemented serine, suggesting the importance of serine homeostasis involving the phosphorylated and glycolate pathways. Metabolomic phenotypes indicate that the phosphorylated pathway mainly influences the tricarboxylic acid cycle, the amino acid and nucleotide metabolism, and lipid metabolism. These results indicate the importance of the phosphorylated pathway of serine biosynthesis in the dark, in the development of sperm, embryo, and sporophyte, and metabolism in M. polymorpha.
  Springer Science and Business Media LLC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1038/s42003-023-05746-6
  DOI ID：10.1038/s42003-023-05746-6, eISSN：2399-3642, PubMed ID：38267515, PubMed Central ID：PMC10808223
• Degradation of glycosylinositol phosphoceramide during plant tissue homogenization.　　　　　　　　　　　　　　　
  Yoshimichi Takai; Rumana Yesmin Hasi; Naoko Matsumoto; Chiho Fujita; Hanif Ali; Junji Hayashi; Ryushi Kawakami; Mutsumi Aihara; Toshiki Ishikawa; Hiroyuki Imai; Mayuko Wakida; Kazuya Ando; Tamotsu Tanaka
  Journal of biochemistry, 巻：175, 号：1, 開始ページ：115, 終了ページ：124, 2023年12月, ［国際誌］
  A convenient method for the determination of plant sphingolipids (glycosylinositol phosphoceramide, GIPC; glucosylceramide, GluCer; phytoceramide 1-phosphate, PC1P and phytoceramide, PCer) was developed. This method includes the extraction of lipids using 1-butanol, alkali hydrolysis with methylamine and separation by TLC. The amounts of sphingolipids in the sample were determined based on the relative intensities of standard sphingolipids visualized by primulin/UV on TLC. Using this method, we found that almost all GIPCs were degraded in response to tissue homogenization in cruciferous plants (cabbage, broccoli and Arabidopsis thaliana). The decrease in GIPCs was compensated for by increases in PC1P and PCer, indicating that GIPC was degraded by hydrolysis at the D and C positions of GIPC, respectively. In carrot roots and leaves, most of GIPC degradation was compensated for by an increase in PCer. In rice roots, the decrease in GIPCs was not fully explained by the increases in PC1P and PCer, indicating that enzymes other than phospholipase C and D activities operated. As the visualization of lipids on TLC is useful for detecting the appearance or disappearance of lipids, this method will be available for the characterization of metabolism of sphingolipids in plants.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/jb/mvad080
  DOI ID：10.1093/jb/mvad080, PubMed ID：37827526
• MHP1 and MHL generate odd-chain fatty acids from 2-hydroxy fatty acids in sphingolipids and are related to immunity in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Marina Ushio; Toshiki Ishikawa; Takakazu Matsuura; Izumi C. Mori; Maki Kawai-Yamada; Yoichiro Fukao; Minoru Nagano
  Plant Science, 巻：336, 開始ページ：111840, 終了ページ：111840, 2023年11月, ［国際誌］
  In plants, the 2-hydroxy fatty acids (HFAs) of sphingolipids are important for plant growth and stress responses. Although the synthetic pathway of HFAs is well understood, their degradation has not yet been elucidated. In Saccharomyces cerevisiae, Mpo1 has been identified as a dioxygenase that degrades HFAs. This study examined the functions of two homologs of yeast Mpo1, MHP1 and MHL, in Arabidopsis thaliana. The mhp1 and mhp1mhl mutants showed a dwarf phenotype compared to that of the wild type. Lipid analysis of the mutants revealed the involvement of MHP1 and MHL in synthesizing odd-chain fatty acids (OCFAs), possibly by the degradation of HFAs. OCFAs are present in trace amounts in plants; however, their physiological significance is largely unknown. RNA sequence analysis of the mhp1mhl mutant revealed that growth-related genes decreased, whereas genes involved in stress response increased. Additionally, the mhp1mhl mutant had increased expression of defense-related genes and increased resistance to infection by Pseudomonas syringae pv. tomato DC3000 (Pto), and Pto carrying the effector AvrRpt2. Phytohormone analysis demonstrated that jasmonic acid in mhp1mhl was higher than that in the wild type. These results indicate that MHP1 and MHL are involved in synthesizing OCFAs and immunity in Arabidopsis.
  Elsevier BV, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.plantsci.2023.111840
  DOI ID：10.1016/j.plantsci.2023.111840, ISSN：0168-9452, PubMed ID：37619867
• Heterologous expression of mtf and mtc genes of Pseudanabaena foetida var. intermedia is sufficient to produce 2-methylisoborneol in Escherichia coli.　　　　　　　　　　　　　　　
  Kaushalya Dayarathne; Toshiki Ishikawa; Satoru Watanabe; Yuuma Ishikawa; Kadeer Aikeranmu; Hina Kitagawaa; Natsumi Komatsubara; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Microbiology spectrum, 巻：11, 号：5, 開始ページ：e0256123, 2023年09月, ［国際誌］
  Microbial volatile metabolite 2-methylisoborneol (2-MIB) causes odor and taste issues in drinking water, making it unappealing for human consumption. It has been suggested that 2-MIB biosynthesis consists of two main steps, namely, methylation of geranyl diphosphate into 2-methyl geranyl diphosphate by geranyl diphosphate methyl transferase (GPPMT) and subsequent cyclization into 2-MIB by 2-MIB synthase (MIBS). Pseudanabaena foetida var. intermedia is a 2-MIB-producing cyanobacterium whose GPPMT and MIBS enzymes are encoded by adjacent mtf and mtc genes. The present study identified a 2-MIB-related gene cluster composed of cnbA, mtf, mtc, and cnbB genes in P. foetida var. intermedia. The two homologous cyclic nucleotide-binding protein genes, cnbA and cnbB, were detected adjacent to the mtf and mtc genes, respectively. The nucleotide sequence of the cnbA-mtf-mtc-cnbB gene cluster showed 99.55% identity with 2-MIB synthesis-associated gene cluster of Pseudanabaena sp. dqh15. RT-PCR results revealed that mtf and mtc genes are co-expressed, while cnbA and cnbB genes are expressed independently in P. foetida var. intermedia. To investigate whether only mtf and mtc genes are sufficient for 2-MIB synthesis, the two-gene unit (mtf-mtc) was introduced into Escherichia coli strain JM109 via overexpression vector pYS1C. Gas chromatograph-mass spectrometry results showed that the E. coli strain transformed with mtf-mtc was able to produce 2-MIB. The intracellular 2-MIB level in P. foetida var. intermedia was higher than the extracellular 2-MIB level, while the transformed E. coli strain showed an opposite trend. Growth inhibition was observed in the 2-MIB-producing transformed E. coli strain. IMPORTANCE Contamination of drinking water with odiferous microbial metabolite 2-MIB is a worldwide concern. Removal of 2-MIB from drinking water burdens the water purification process. Therefore, it is important to search for alternative methods, such as suppressing the production of 2-MIB by aquatic microorganisms. For that, it is necessary to expand the current knowledge about the mechanism of 2-MIB synthesis at the genetic level. This study revealed that mtf and mtc genes of the 2-MIB-related gene cluster are transcribed as a single unit in P. foetida var. intermedia, and the expression of both mtf and mtc genes is essential and sufficient for 2-MIB synthesis in E. coli heterologous gene expression system.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1128/spectrum.02561-23
  DOI ID：10.1128/spectrum.02561-23, PubMed ID：37732762, PubMed Central ID：PMC10580876
• NAC domain transcription factors VNI2 and ATAF2 form protein complexes and regulate leaf senescence　　　　　　　　　　　　　　　
  Isura Sumeda Priyadarshana Nagahage; Kohei Matsuda; Kyoko Miyashita; Sumire Fujiwara; Chanaka Mannapperuma; Takuya Yamada; Shingo Sakamoto; Toshiki Ishikawa; Minoru Nagano; Misato Ohtani; Ko Kato; Hirofumi Uchimiya; Nobutaka Mitsuda; Maki Kawai‐Yamada; Taku Demura; Masatoshi Yamaguchi
  Plant Direct, 巻：7, 号：9, 開始ページ：e529, 2023年09月, ［査読有り］, ［国際誌］
  Abstract
  
  The NAM, ATAF1/2, and CUC2 (NAC) domain transcription factor VND‐INTERACTING2 (VNI2) negatively regulates xylem vessel formation by interacting with another NAC domain transcription factor, VASCULAR‐RELATED NAC‐DOMAIN7 (VND7), a master regulator of xylem vessel formation. Here, we screened interacting proteins with VNI2 using yeast two‐hybrid assay and isolated two NAC domain transcription factors, Arabidopsis thaliana ACTIVATION FACTOR 2 (ATAF2) and NAC DOMAIN CONTAINING PROTEIN 102 (ANAC102). A transient gene expression assay showed that ATAF2 upregulates the expression of genes involved in leaf senescence, and VNI2 effectively inhibits the transcriptional activation activity of ATAF2. vni2 mutants accelerate leaf senescence, whereas ataf2 mutants delay leaf senescence. In addition, the accelerated leaf senescence phenotype of the vni2 mutant is recovered by simultaneous mutation of ATAF2. Our findings strongly suggest that VNI2 interacts with and inhibits ATAF2, resulting in negatively regulating leaf senescence.
  Wiley, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pld3.529
  DOI ID：10.1002/pld3.529, ISSN：2475-4455, eISSN：2475-4455, PubMed ID：37731912, PubMed Central ID：PMC10507225
• Metabolic changes associated with dark-induced leaf senescence in Arabidopsis nadk2 mutants　　　　　　　　　　　　　　　
  Chaomurilege; Atsuko Miyagi; Toshiki Ishikawa; Masatoshi Yamaguchi; Hideki Murayama; Maki Kawai-Yamada
  Plant Signaling and Behavior, 巻：18, 号：1, 開始ページ：e2215618, 終了ページ：2215618, 2023年05月, ［査読有り］, ［国際誌］
  Arabidopsis NADK2 (NAD kinase 2) is a chloroplast-localized enzyme involved in NADP+ synthesis, which acts as the final electron acceptor in the photosynthetic electron transfer chain. The NADK2-deficient mutant (nadk2) was used to analyze the effect of NAD(P)(H) unbalance in the dark-induced leaf senescence. During senescence, WT plants and nadk2 mutants showed a similar reduction in chlorophyll content. NAD(P)(H) quantification showed that the amount of total NAD(P)(H) decreased on the day 7 in WT but on the day 3 in nadk2. The phosphorylation ratio (i.e. NADP(H)/NAD(H)) decreased on day 1 in WT. In contrast, the nadk2 showed lower phosphorylation ratio at 0 day and no change throughout the aging process. Metabolome analysis showed that the metabolic profiles of both WT plants and nadk2 mutants subjected to dark-induced senescence adopted similar patterns as the senescence progressed. However, the changes in individual metabolites in the nadk2 mutants were different from those of the WT during dark-induced senescence.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15592324.2023.2215618
  DOI ID：10.1080/15592324.2023.2215618, PubMed ID：37272565, PubMed Central ID：PMC10324968
• Functions of serine from the phosphorylated pathway on growth, male gametogenesis, and metabolism in Marchantia polymorpha
  Masami Hirai; Mengyao Wang; Hiromitsu Tabeta; Kinuka Ohtaka; Ayuko Kuwahara; Ryuichi Nishihama; Toshiki Ishikawa; Kiminori Toyooka; Mayuko Sato; Mayumi Wakazaki; Hiromichi Akashi; Hiroshi Tsugawa; Tsubasa Shoji; Yozo Okazaki; Keisuke Yoshida; Ryoichi Sato; Ali Ferjani; Takayuki Kohchi
  2023年04月
  Abstract
  
  Serine is an important precursor of various biomolecules. Here, we investigated the role of the phosphorylated pathway of serine biosynthesis in a non-vascular plant Marchantia polymorpha by analyzing knockout mutants of MpPGDH, a single gene encoding the first committed enzyme 3-phosphoglycerate dehydrogenase (PGDH), to assess functions of this pathway in relation to those of the other two pathways. Growth phenotypes of the mutants indicated that serine supply from the phosphorylated pathway in the dark was crucial for vegetative growth. Sperm formation required serine from this pathway, while egg formation did not depend on it. Knockout of MpPGDH in the maternal genome disrupted sporophyte development. When the mutants were grown in high CO₂ where the photorespiratory glycolate pathway for serine biosynthesis is inhibited, thallus growth was suppressed and not fully recovered to wild-type level by exogenous serine supplement, suggesting that serine homeostasis involving both the phosphorylated and glycolate pathways was essential. Metabolome and lipidome analyses indicated that the phosphorylated pathway mainly influenced the tricarboxylic acid cycle, the amino acid and nucleotide metabolism, and lack of serine significantly perturbed lipid metabolism. Our results indicate the importance of serine from the phosphorylated pathway for sperm formation, sporophyte development, and metabolism in M. polymorpha.
  Research Square Platform LLC
  DOI：https://doi.org/10.21203/rs.3.rs-2663856/v1
  DOI ID：10.21203/rs.3.rs-2663856/v1
• Chloroplastic Sec14-like proteins modulate growth and phosphate deficiency responses in Arabidopsis and rice　　　　　　　　　　　　　　　
  Mailun Yang; Yasuhito Sakruaba; Toshiki Ishikawa; Namie Ohtsuki; Maki Kawai-Yamada; Shuichi Yanagisawa
  Plant Physiology, 巻：192, 号：4, 開始ページ：3030, 終了ページ：3048, 2023年04月, ［査読有り］, ［国際誌］
  Abstract
  
  Phosphorus is an essential nutrient acquired from soil as phosphate (Pi), and its deficiency severely reduces plant growth and crop yield. Here, we show that single nucleotide polymorphisms (SNPs) at the PHOSPHATIDYLINOSITOL TRANSFER PROTEIN7 (AtPITP7) locus, which encodes a chloroplastic Sec14-like protein, are associated with genetic diversity regarding Pi uptake activity in Arabidopsis (Arabidopsis thaliana). Inactivation of AtPITP7 and its rice (Oryza sativa) homolog (OsPITP6) through T-DNA insertion and CRISPR/Cas9-mediated gene editing, respectively, decreased Pi uptake and plant growth, regardless of Pi availability. By contrast, overexpression of AtPITP7 and OsPITP6 enhanced Pi uptake and plant growth, especially under limited Pi supply. Importantly, overexpression of OsPITP6 increased the tiller number and grain yield in rice. Targeted metabolome analysis of glycerolipids in leaves and chloroplasts revealed that inactivation of OsPITP6 alters phospholipid contents, independent of Pi availability, diminishing the reduction in phospholipid content and increase in glycolipid content induced by Pi deficiency; meanwhile, overexpression of OsPITP6 enhanced Pi deficiency-induced metabolic alterations. Together with transcriptome analysis of ospitp6 rice plants and phenotypic analysis of grafted Arabidopsis chimeras, these results suggest that chloroplastic Sec14-like proteins play an essential role in growth modulations in response to changes in Pi availability, although their function is critical for plant growth under any Pi condition. The superior traits of OsPITP6-overexpressing rice plants also highlight the potential of OsPITP6 and its homologs in other crops as additional tools for improving Pi uptake and plant growth in low Pi environments.
  Oxford University Press (OUP), 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/plphys/kiad212
  DOI ID：10.1093/plphys/kiad212, ISSN：0032-0889, eISSN：1532-2548, PubMed ID：37021761, PubMed Central ID：PMC10400038
• Acylated plastoquinone is a novel neutral lipid accumulated in cyanobacteria　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Shunya Takano; Riko Tanikawa; Takashi Fujihara; Kimie Atsuzawa; Yasuko Kaneko; Yukako Hihara
  PNAS Nexus, 巻：2, 号：5, 開始ページ：pgad092, 2023年03月, ［査読有り］, ［筆頭著者］, ［国際誌］
  Abstract
  
  Although cyanobacteria do not possess bacterial triacylglycerol (TAG) synthesizing enzymes, accumulation of TAGs and/or lipid droplets has been repeatedly reported in a wide range of species. In most cases, identification of TAG has been based on the detection of the spot showing the mobility similar to the TAG standard in thin-layer chromatography of neutral lipids. In this study, we identified monoacyl plastoquinol (acyl PQH) as the predominant molecular species in the TAG-like spot from the unicellular Synechocystis sp. PCC 6803 (S.6803) as well as the filamentous Nostocales species, Nostoc punctiforme PCC 73102 and Anabaena sp. PCC 7120. In S.6803, the accumulation level of acyl PQH but not TAG was affected by deletion or overexpression of slr2103, indicating that acyl PQH is the physiological product of Slr2103 having homology with the eukaryotic diacylglycerol acyltransferase-2 (DGAT2). Electron microscopy revealed that cyanobacterial strains used in this study do not accumulate lipid droplet structures such as those observed in oleaginous microorganisms. Instead, they accumulate polyhydroxybutyrate (PHB) granules and/or aggregates of alkane, free C16 and C18 saturated fatty acids and low amounts of TAG in the cytoplasmic area, which can be detected by staining with a fluorescent dye specific to neutral lipids. Unlike these lipophilic materials, acyl PQH is exclusively localized in the membrane fraction. There must be DGAT2-like enzymatic activity esterifying de novo-synthesized C16 and C18 fatty acids to PQH2 in the thylakoid membranes.
  Oxford University Press (OUP), 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pnasnexus/pgad092
  DOI ID：10.1093/pnasnexus/pgad092, eISSN：2752-6542, PubMed ID：37152674, PubMed Central ID：PMC10156143
• Loss of peroxisomal NAD kinase 3 (NADK3) affects photorespiration metabolism in Arabidopsis　　　　　　　　　　　　　　　
  Shota Suzuki; Daimu Tanaka; Atsuko Miyagi; Kentaro Takahara; Masaru Kono; Chaomurilege; Ko Noguchi; Toshiki Ishikawa; Minoru Nagano; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Journal of Plant Physiology, 巻：283, 開始ページ：153950, 終了ページ：153950, 2023年03月, ［査読有り］, ［国際誌］
  Nicotinamide adenine dinucleotides (NAD+ and NADP+) are electron mediators involved in various metabolic pathways. NADP(H) are produced by NAD kinase (NADK) through the phosphorylation of NAD(H). The Arabidopsis NADK3 (AtNADK3) is reported to preferentially phosphorylate NADH to NADPH and is localized in the peroxisome. To elucidate the biological function of AtNADK3 in Arabidopsis, we compared metabolites of nadk1, nadk2 and nadk3 Arabidopsis T-DNA inserted mutants. Metabolome analysis revealed that glycine and serine, which are intermediate metabolites of photorespiration, both increased in the nadk3 mutants. Plants grown for 6 weeks under short-day conditions showed increased NAD(H), indicating a decrease in the phosphorylation ratio in the NAD(P)(H) equilibrium. Furthermore, high CO2 (0.15%) treatment induced a decrease in glycine and serine in nadk3 mutants. The nadk3 showed a significant decrease in post-illumination CO2 burst, suggesting that the photorespiratory flux was disrupted in the nadk3 mutant. In addition, an increase in CO2 compensation points and a decrease in CO2 assimilation rate were observed in the nadk3 mutants. These results indicate that the lack of AtNADK3 causes a disruption in the intracellular metabolism, such as in amino acid synthesis and photorespiration.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2023.153950
  DOI ID：10.1016/j.jplph.2023.153950, PubMed ID：36889102
• Metabolomic analysis of rice brittle culm mutants reveals each mutant- specific metabolic pattern in each organ　　　　　　　　　　　　　　　
  Atsuko Miyagi; Kazuhisa Mori; Toshiki Ishikawa; Satoshi Ohkubo; Shunsuke Adachi; Masatoshi Yamaguchi; Taiichiro Ookawa; Toshihisa Kotake; Maki Kawai-Yamada
  Metabolomics, 巻：18, 号：12, 開始ページ：95, 終了ページ：95, 2022年11月, ［査読有り］, ［国際誌］
  INTRODUCTION: Plant cell walls play an important role in providing physical strength and defence against abiotic stress. Rice brittle culm (bc) mutants are a strength-decreased mutant because of abnormal cell walls, and it has been reported that the causative genes of bc mutants affect cell wall composition. However, the metabolic alterations in each organ of bc mutants have remained unknown. OBJECTIVES: To evaluate the metabolic changes in rice bc mutants, comparative analysis of the primary metabolites was conducted. METHODS: The primary metabolites in leaves, internodes, and nodes of rice bc mutants and wild-type control were measured using CE- and LC-MS/MS. Multivariate analyses using metabolomic data was performed. RESULTS: We found that mutations in each bc mutant had different effects on metabolism. For example, higher oxalate content was observed in bc3 and bc1 bc3 mutants, suggesting that surplus carbon that was not used for cell wall components might be used for oxalate synthesis. In addition, common metabolic alterations such as a decrease of sugar nucleotides in nodes were found in bc1 and Bc6, in which the causative genes are involved in cellulose accumulation. CONCLUSION: These results suggest that metabolic analysis of the bc mutants could elucidate the functions of causative gene and improve the cell wall components for livestock feed or bioethanol production.
  Springer Science and Business Media LLC, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11306-022-01958-9
  DOI ID：10.1007/s11306-022-01958-9, eISSN：1573-3890, PubMed ID：36409428
• Loss of chloroplast-localized NAD kinase causes ROS stress in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Chaomurilege; Yanhui Zu; Atsuko Miyagi; Shin-Nosuke Hashida; Toshiki Ishikawa; Masatoshi Yamaguchi; Maki Kawai-Yamada
  Journal of Plant Research, 巻：in press, 号：1, 開始ページ：97, 終了ページ：106, 2022年11月, ［査読有り］, ［国際誌］
  Chloroplast-localized NAD kinase (NADK2) is responsible for the production of NADP+, which is an electron acceptor in the linear electron flow of photosynthesis. The Arabidopsis T-DNA-inserted mutant of NADK2 (nadk2) showed delayed growth and pale-green leaves under continuous light conditions. Under short-day conditions (8 h light / 16 h dark), the nadk2 mutant showed more severe growth inhibition.The genomic fragment containing the promoter and coding region of NADK2 complemented the phenotypes of nadk2 obtained under continuous light and short-day conditions. The nadk2 mutant produced higher amounts of H2O2 and O2-, which were reduced in the complementary line. Under short-day conditions, the nadk2 mutant accumulated more H2O2 than under continuous light conditions. The accumulation of ascorbate and up-regulation of the PDF1.2 and PR1 genes indicated that the nadk2 mutant is under ROS stress and responding to keep its living activities.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s10265-022-01420-w
  DOI ID：10.1007/s10265-022-01420-w, PubMed ID：36367584
• Nonspecific phospholipase C3 of radish has phospholipase D activity towards glycosylinositol phosphoceramide　　　　　　　　　　　　　　　
  Rumana Yesmin Hasi; Toshiki Ishikawa; Keigo Sunagawa; Yoshimichi Takai; Hanif Ali; Junji Hayashi; Ryushi Kawakami; Keizo Yuasa; Mutsumi Aihara; Kaori Kanemaru; Hiroyuki Imai; Tamotsu Tanaka
  FEBS Letters, 巻：596, 号：23, 開始ページ：3024, 終了ページ：3036, 2022年10月, ［査読有り］, ［国際誌］
  Glycosylinositol phosphoceramide (GIPC) is a major sphingolipid in the plasma membranes of plants. Previously, we found an enzyme activity that produces phytoceramide 1-phosphate (PC1P) by hydrolysis of the D position of GIPC in cabbage and named this activity as GIPC-phospholipase D (PLD). Here, we purified GIPC-PLD by sequential chromatography from radish roots. Peptide mass fingerprinting analysis revealed that the potential candidate for GIPC-PLD protein was nonspecific phospholipase C3 (NPC3), which has not been characterized as a PLD. The recombinant NPC3 protein obtained by heterologous expression system in Escherichia coli produced PC1P from GIPC and showed essentially the same enzymatic properties as those we characterized as GIPC-PLD in cabbage, radish and Arabidopsis thaliana. From these results, we conclude that NPC3 is one of the enzymes that degrade GIPC.
  Wiley, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/1873-3468.14520
  DOI ID：10.1002/1873-3468.14520, ISSN：0014-5793, eISSN：1873-3468, PubMed ID：36266963
• Sphingolipids with 2-hydroxy fatty acids aid in plasma membrane nanodomain organization and oxidative burst　　　　　　　　　　　　　　　
  Tomomi Ukawa; Fumihiko Banno; Toshiki Ishikawa; Kota Kasahara; Yuuta Nishina; Rika Inoue; Keigo Tsujii; Masatoshi Yamaguchi; Takuya Takahashi; Yoichiro Fukao; Maki Kawai-Yamada; Minoru Nagano
  Plant Physiology, 巻：189, 号：2, 開始ページ：839, 終了ページ：857, 2022年06月, ［査読有り］, ［国際誌］
  Abstract
  
  Plant sphingolipids mostly possess 2-hydroxy fatty acids (HFA), the synthesis of which is catalyzed by FA 2-hydroxylases (FAHs). In Arabidopsis (Arabidopsis thaliana), two FAHs (FAH1 and FAH2) have been identified. However, the functions of FAHs and sphingolipids with HFAs (2-hydroxy sphingolipids) are still unknown because of the lack of Arabidopsis lines with the complete deletion of FAH1. In this study, we generated a FAH1 mutant (fah1c) using CRISPR/Cas9-based genome editing. Sphingolipid analysis of fah1c, fah2, and fah1cfah2 mutants revealed that FAH1 hydroxylates very long-chain FAs (VLCFAs), whereas the substrates of FAH2 are VLCFAs and palmitic acid. However, 2-hydroxy sphingolipids are not completely lost in the fah1cfah2 double mutant, suggesting the existence of other enzymes catalyzing the hydroxylation of sphingolipid FAs. Plasma membrane (PM) analysis and molecular dynamics simulations revealed that hydroxyl groups of sphingolipid acyl chains play a crucial role in the organization of nanodomains, which are nanoscale liquid-ordered domains mainly formed by sphingolipids and sterols in the PM, through hydrogen bonds. In the PM of the fah1cfah2 mutant, the expression levels of 26.7% of the proteins, including defense-related proteins such as the pattern recognition receptors (PRRs) brassinosteroid insensitive 1-associated receptor kinase 1 and chitin elicitor receptor kinase 1, NADPH oxidase respiratory burst oxidase homolog D (RBOHD), and heterotrimeric G proteins, were lower than that in the wild-type. In addition, reactive oxygen species (ROS) burst was suppressed in the fah1cfah2 mutant after treatment with the pathogen-associated molecular patterns flg22 and chitin. These results indicated that 2-hydroxy sphingolipids are necessary for the organization of PM nanodomains and ROS burst through RBOHD and PRRs during pattern-triggered immunity.
  Oxford University Press (OUP), 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/plphys/kiac134
  DOI ID：10.1093/plphys/kiac134, ISSN：0032-0889, eISSN：1532-2548, PubMed ID：35312013, PubMed Central ID：PMC9157162
• VNI2 effectively inhibits transcriptional activities of VND7 through a conserved sequence　　　　　　　　　　　　　　　
  Aili Ailizati; Isura Sumeda Priyadarshana Nagahage; Atsuko Miyagi; Toshiki Ishikawa; Maki Kawai-Yamada; Taku Demura; Masatoshi Yamaguchi
  Plant Biotechnology, 巻：39, 号：2, 開始ページ：147, 終了ページ：153, 2022年06月, ［査読有り］, ［国際共著］, ［国内誌］
  An Arabidopsis NAC domain transcription factor VND-INTERACTING2 (VNI2) was originally isolated as an interacting protein with another NAC domain transcription factor, VASCULAR-RELATED NAC-DOMAIN7 (VND7), a master regulator of xylem vessel element differentiation. VNI2 inhibits transcriptional activation activity of VND7 by forming a protein complex. Here, to obtain insights into how VNI2 regulates VND7, we tried to identify the amino acid region of VNI2 required for inhibition of VND7. VNI2 has an amino acid sequence similar to the ETHYLENE-RESPONSIVE ELEMENT BINDING FACTOR (ERF)-associated amphiphilic repression (EAR) motif, conserved in transcriptional repressors, at the C-terminus. A transient expression assay showed that the EAR-like motif of VNI2 was not required for inhibition of VND7. The C-terminal deletion series of VNI2 revealed that 10 amino acid residues, highly conserved in the VNI2 orthologs contributed to effective repression of the transcriptional activation activity of VND7. Observation of transgenic plants ectopically expressing VNI2 showed that the identified 10 amino acid sequence strongly affected xylem vessel formation and plant growth. These data indicated that the 10 amino acid sequence of VNI2 has an important role in its transcriptional repression activity and negative regulation of xylem vessel formation.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.22.0122a
  DOI ID：10.5511/plantbiotechnology.22.0122a, PubMed ID：35937523, PubMed Central ID：PMC9300430
• An Arabidopsis NAC domain transcriptional activator VND7 negatively regulates VNI2 expression　　　　　　　　　　　　　　　
  Aili Ailizati; Isura Sumeda Priyadarshana Nagahage; Atsuko Miyagi; Toshiki Ishikawa; Maki Kawai-Yamada; Taku Demura; Masatoshi Yamaguchi
  Plant Biotechnology, 巻：38, 号：4, 開始ページ：415, 終了ページ：420, 2021年12月, ［査読有り］, ［国際共著］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.21.1013a
  DOI ID：10.5511/plantbiotechnology.21.1013a
• Change in expression levels of NAD kinase-encoding genes in Flaveria species　　　　　　　　　　　　　　　
  Masami Tanaka; Yuuma Ishikawa; Sayaka Suzuki; Takako Ogawa; Yukimi Y. Taniguchi; Atsuko Miyagi; Toshiki Ishikawa; Masatoshi Yamaguchi; Yuri N. Munekage; Maki Kawai-Yamada
  Journal of Plant Physiology, 巻：265, 開始ページ：153495, 終了ページ：153495, 2021年10月, ［査読有り］
  Elsevier BV, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2021.153495
  DOI ID：10.1016/j.jplph.2021.153495, ISSN：0176-1617
• The NAD Kinase Slr0400 Functions as a Growth Repressor in Synechocystis sp. PCC 6803　　　　　　　　　　　　　　　
  Yuuma Ishikawa; Cedric Cassan; Aikeranmu Kadeer; Koki Yuasa; Nozomu Sato; Kintake  Sonoike; Yasuko Kaneko; Atsuko Miyagi; Hiroko Takahashi; Toshiki Ishikawa; Masatoshi Yamaguchi; Yoshitaka Nishiyama; Yukako Hihara; Yves Gibon; Maki Kawai-Yamada
  Plant and Cell Physiology, 巻：62, 号：4, 開始ページ：668, 終了ページ：677, 2021年09月, ［査読有り］
  
  NADP+, the phosphorylated form of nicotinamide adenine dinucleotide (NAD), plays an essential role in many cellular processes. NAD kinase (NADK), which is conserved in all living organisms, catalyzes the phosphorylation of NAD+ to NADP+. However, the physiological role of phosphorylation of NAD+ to NADP+ in the cyanobacterium Synechocystis remains unclear. In this study, we report that slr0400, an NADK-encoding gene in Synechocystis, functions as a growth repressor under light-activated heterotrophic growth conditions and light and dark cycle conditions in the presence of glucose. We show, via characterization of NAD(P)(H) content and enzyme activity, that NAD+ accumulation in slr0400-deficient mutant results in the unsuppressed activity of glycolysis and tricarboxylic acid (TCA) cycle enzymes. In determining whether Slr0400 functions as a typical NADK, we found that constitutive expression of slr0400 in an Arabidopsis nadk2-mutant background complements the pale-green phenotype. Moreover, to determine the physiological background behind the growth advantage of mutants lacking slr04000, we investigated the photobleaching phenotype of slr0400-deficient mutant under high-light conditions. Photosynthetic analysis found in the slr0400-deficient mutant resulted from malfunctions in the Photosystem II (PSII) photosynthetic machinery. Overall, our results suggest that NADP(H)/NAD(H) maintenance by slr0400 plays a significant role in modulating glycolysis and the TCA cycle to repress the growth rate and maintain the photosynthetic capacity.
  Oxford University Press (OUP), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcab023
  DOI ID：10.1093/pcp/pcab023, ISSN：0032-0781, eISSN：1471-9053, PubMed ID：33210985, PubMed Central ID：PMC7781788
• Reprogramming sphingolipid glycosylation is required for endosymbiont persistence in Medicago truncatula　　　　　　　　　　　　　　　
  William M. Moore; Candace Chan; Toshiki Ishikawa; Emilie A. Rennie; Heidi M.-L. Wipf; Veronica Benites; Maki Kawai-Yamada; Jenny C. Mortimer; Henrik V. Scheller
  Current Biology, 巻：31, 号：11, 開始ページ：2374, 終了ページ：2385.e4, 2021年06月
  Cell Press, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.cub.2021.03.067
  DOI ID：10.1016/j.cub.2021.03.067, ISSN：1879-0445, PubMed ID：33857428, SCOPUS ID：85104939324
• The Arabidopsis thaliana nucleotide sugar transporter GONST2 is a functional homolog of GONST1.　　　　　　　　　　　　　　　
  Beibei Jing; Toshiki Ishikawa; Nicole Soltis; Noriko Inada; Yan Liang; Gosia Murawska; Lin Fang; Fekadu Andeberhan; Ramana Pidatala; Xiaolan Yu; Edward Baidoo; Maki Kawai-Yamada; Dominique Loque; Daniel J Kliebenstein; Paul Dupree; Jenny C Mortimer
  Plant direct, 巻：5, 号：3, 開始ページ：e00309, 2021年03月, ［査読有り］, ［国際誌］
  Glycosylinositolphosphorylceramides (GIPCs) are the predominant lipid in the outer leaflet of the plasma membrane. Characterized GIPC glycosylation mutants have severe or lethal plant phenotypes. However, the function of the glycosylation is unclear. Previously, we characterized Arabidopsis thaliana GONST1 and showed that it was a nucleotide sugar transporter which provides GDP-mannose for GIPC glycosylation. gonst1 has a severe growth phenotype, as well as a constitutive defense response. Here, we characterize a mutant in GONST1's closest homolog, GONST2. The gonst2-1 allele has a minor change to GIPC headgroup glycosylation. Like other reported GIPC glycosylation mutants, gonst1-1gonst2-1 has reduced cellulose, a cell wall polymer that is synthesized at the plasma membrane. The gonst2-1 allele has increased resistance to a biotrophic pathogen Golovinomyces orontii but not the necrotrophic pathogen Botrytis cinerea. Expression of GONST2 under the GONST1 promoter can rescue the gonst1 phenotype, indicating that GONST2 has a similar function to GONST1 in providing GDP-D-Man for GIPC mannosylation.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pld3.309
  DOI ID：10.1002/pld3.309, PubMed ID：33763627, PubMed Central ID：PMC7980081
• The NAD kinase Slr0400 functions as a growth repressor in Synechocystis sp. PCC 6803.　　　　　　　　　　　　　　　
  Yuuma Ishikawa; Cedric Cassan; Aikeranmu Kadeer; Koki Yuasa; Nozomu Sato; Kintake Sonoike; Yasuko Kaneko; Atsuko Miyagi; Hiroko Takahashi; Toshiki Ishikawa; Masatoshi Yamaguchi; Yoshitaka Nishiyama; Yukako Hihara; Yves Gibon; Maki Kawai-Yamada
  Plant & cell physiology, 2021年02月, ［査読有り］, ［国内誌］
  NADP+, the phosphorylated form of nicotinamide adenine dinucleotide (NAD), plays an essential role in many cellular processes. NAD kinase (NADK), which is conserved in all living organisms, catalyzes the phosphorylation of NAD+ to NADP+. However, the physiological role of phosphorylation of NAD+ to NADP+ in the cyanobacterium Synechocystis remains unclear. In this study, we report that slr0400, an NADK-encoding gene in Synechocystis, functions as a growth repressor under light-activated heterotrophic growth conditions and light and dark cycle conditions in the presence of glucose. We show, via characterization of NAD(P)(H) content and enzyme activity, that NAD+ accumulation in slr0400-deficient mutant results in unsuppressed activity of glycolysis and tricarboxylic acid (TCA) cycle enzymes. In determining whether Slr0400 functions as a typical NADK, we found that constitutive expression of slr0400 in an Arabidopsis nadk2-mutant background complements the pale-green phenotype. Moreover, to determine the physiological background behind the growth advantage of mutants lacking slr04000, we investigated the photobleaching phenotype of slr0400-deficient mutant under high-light conditions. Photosynthetic analysis found in the slr0400-deficient mutant resulted from malfunctions in the PSII photosynthetic machinery. Overall, our results suggest that NADP(H)/NAD(H) maintenance by slr0400 plays a significant role in modulating glycolysis and the TCA cycle to repress the growth rate and maintain photosynthetic capacity.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcab023
  DOI ID：10.1093/pcp/pcab023, PubMed ID：33560438
• Ceramides mediate positional signals in Arabidopsis thaliana protoderm differentiation.　　　　　　　　　　　　　　　
  Kenji Nagata; Toshiki Ishikawa; Maki Kawai-Yamada; Taku Takahashi; Mitsutomo Abe
  Development (Cambridge, England), 巻：148, 号：2, 2021年01月, ［査読有り］, ［国際誌］
  The differentiation of distinct cell types in appropriate patterns is a fundamental process in the development of multicellular organisms. In Arabidopsis thaliana, protoderm/epidermis differentiates as a single cell layer at the outermost position. However, little is known about the molecular nature of the positional signals that achieve correct epidermal cell differentiation. Here, we propose that very-long-chain fatty acid-containing ceramides (VLCFA-Cers) mediate positional signals by stimulating the function of ARABIDOPSIS THALIANA MERISTEM LAYER1 (ATML1), a master regulator of protoderm/epidermis differentiation, during lateral root development. We show that VLCFA-Cers, which are synthesized predominantly in the outermost cells, bind to the lipid-binding domain of ATML1. Importantly, this cell type-specific protein-lipid association alters the activity of ATML1 protein and consequently restricts its expression to the protoderm/epidermis through a transcriptional feedback loop. Furthermore, establishment of a compartment, enriched with VLCFA-containing sphingolipids, at the outer lateral membrane facing the external environment may function as a determinant of protodermal cell fate. Taken together, our results indicate that VLCFA-Cers play a pivotal role in directing protoderm/epidermis differentiation by mediating positional signals to ATML1.This article has an associated 'The people behind the papers' interview.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1242/dev.194969
  DOI ID：10.1242/dev.194969, PubMed ID：33495212
• Altered metabolism of chloroplastic NAD kinase-overexpressing Arabidopsis in response to magnesium sulfate supplementation.　　　　　　　　　　　　　　　
  Maki Kawai-Yamada; Atsuko Miyagi; Yuki Sato; Yuki Hosoi; Shin-Nosuke Hashida; Toshiki Ishikawa; Masatoshi Yamaguchi
  Plant signaling & behavior, 巻：16, 号：1, 開始ページ：1844509, 終了ページ：1844509, 2021年01月, ［査読有り］, ［国際誌］
  Nicotinamide adenine dinucleotide (NAD)/NAD phosphate (NADPH) is essential for numerous redox reactions and serve as co-factors in multiple metabolic processes in all organisms. NAD kinase (NADK) is an enzyme involved in the synthesis of NADP+ from NAD+ and ATP. Arabidopsis NADK2 (AtNADK2) is a chloroplast-localizing enzyme that provides recipients of reducing power in photosynthetic electron transfer. When Arabidopsis plants were grown on MS medium supplemented with 5 mM MgSO4, an AtNADK2-overexpressing line exhibited higher glutathione and total sulfur accumulation than control plants. Metabolomic analysis of major amino acids and organic acids using capillary electrophoresis-mass spectrometry demonstrated that overexpression of AtNADK2 affected a range of metabolic processes in response to MgSO4 supplementation.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1080/15592324.2020.1844509
  DOI ID：10.1080/15592324.2020.1844509, PubMed ID：33210985, PubMed Central ID：PMC7781788
• An Arabidopsis NAC domain transcription factor, ATAF2, promotes age-dependent and dark-induced leaf senescence.　　　　　　　　　　　　　　　
  Isura Sumeda Priyadarshana Nagahage; Shingo Sakamoto; Minoru Nagano; Toshiki Ishikawa; Nobutaka Mitsuda; Maki Kawai-Yamada; Masatoshi Yamaguchi
  Physiologia plantarum, 巻：170, 号：2, 開始ページ：299, 終了ページ：308, 2020年10月, ［査読有り］, ［国際誌］
  Leaf senescence is controlled developmentally and environmentally and is affected by numerous genes, including transcription factors. An Arabidopsis NAC domain transcription factor, ATAF2, is known to regulate biotic stress responses. Recently, we have demonstrated that ATAF2 upregulates ORE1, a key regulator of leaf senescence. Here, to investigate the function of ATAF2 in leaf senescence further, we generated and analyzed overexpressing transgenic and T-DNA inserted mutant lines. Transient expression analysis indicated that ATAF2 upregulates several NAC domain transcription factors that regulate senescence. Indeed, ATAF2 overexpression induced the expression of senescence-related genes, thereby accelerating leaf senescence, whereas the expression of such genes in ataf2 mutants was lower than that of wild-type plants. Furthermore, the ataf2 mutants exhibited significant delays in dark-induced leaf senescence. It was also found that ATAF2 induces the expression of transcription factors, which both promotes and represses leaf senescence. The present study demonstrates that ATAF2 promotes leaf senescence in response to developmental and environmental signals.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/ppl.13156
  DOI ID：10.1111/ppl.13156, PubMed ID：32579231
• Quantitative and Qualitative Analyses of Triacylglycerol Production in the Wild-Type Cyanobacterium Synechocystis sp. PCC 6803 and the Strain Expressing AtfA from Acinetobacter baylyi ADP1.　　　　　　　　　　　　　　　
  Motoki Tanaka; Toshiki Ishikawa; So Tamura; Yujiro Saito; Maki Kawai-Yamada; Yukako Hihara
  Plant & cell physiology, 巻：61, 号：9, 開始ページ：1537, 終了ページ：1547, 2020年09月, ［査読有り］, ［国内誌］
  Although cyanobacteria do not possess wax ester synthase/acyl-CoA:diacylglycerol acyltransferase (WS/DGAT), the bacterial enzyme for triacylglycerol (TAG) production, there have been several studies reporting the accumulation of TAG-like compounds in cyanobacteria. In this study, we aimed to evaluate TAG productivity of the ΔrecJ::atfA strain of Synechocystis sp. PCC 6803 generated by inserting atfA encoding WS/DGAT from Acinetobacter baylyi ADP1 into recJ (sll1354), together with the wild type (WT) and the gene-disrupted strain of slr2103 having homology with eukaryotic DGAT2 gene family (Δ2103). Thin-layer chromatography (TLC) of neutral lipids or isolation of the neutral lipid-enriched fraction followed by gas chromatography or liquid chromatography-tandem mass spectrometry was employed for analyses. The ΔrecJ::atfA strain accumulated 0.508 nmol ml-1OD730-1 of TAG after a week of incubation at 100 μmol photons m-2 s-1. The saturated fatty acids C16:0 and C18:0 accounted for about 50% and 20% of the TAG fatty acids, respectively, suggesting that de novo-synthesized fatty acids were preferentially incorporated into TAG molecules. When the neutral lipid profile of the lipid extracts was examined by TLC, a spot located in a slightly lower position compared with the TAG standard was detected in WT but not in the Δ2103 strain. TAG accumulation levels of both strains was only 0.01-0.03 nmol ml-1OD730-1, but the fatty acid composition was substantially different from that of the background. These results suggest that trace amounts of TAG can be produced in Synechocystis cells by enzymes other than Slr2103, and major constituents of the TAG-like spot are unknown lipid species produced by Slr2103.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcaa069
  DOI ID：10.1093/pcp/pcaa069, PubMed ID：32433767
• Plant-unique cis/trans isomerism of long-chain base unsaturation is selectively required for aluminum tolerance resulting from glucosylceramide-dependent plasma membrane fluidity　　　　　　　　　　　　　　　
  Masaya Sato; Minoru Nagano; Song Jin; Atsuko Miyagi; Masatoshi Yamaguchi; Maki Kawai-Yamada; Toshiki Ishikawa
  Plants, 巻：9, 号：1, 開始ページ：19, 2020年01月, ［査読有り］, ［国際誌］
  Cis/trans isomerism of the Δ8 unsaturation of long-chain base (LCB) is found only in plant sphingolipids. This unique geometry is generated by sphingolipid LCB Δ8 desaturase SLD which produces both isomers at various ratios, resulting in diverse cis/trans ratios in plants. However, the biological significance of this isomeric diversity remains controversial. Here, we show that the plant-specific cis unsaturation of LCB selectively contributes to glucosylceramide (GlcCer)-dependent tolerance to aluminum toxicity. We established three transgenic rice lines with altered LCB unsaturation profiles. Overexpression of SLD from rice (OsSLD-OX), which preferentially exhibits cis-activity, or Arabidopsis (AtSLD-OX), showing preference for trans-activity, facilitated Δ8 unsaturation in different manners: a slight increase of cis-unsaturated glycosylinositolphosphoceramide (GIPC) in OsSLD-OX, and a drastic increase of trans-unsaturated GlcCer and GIPC in AtSLD-OX. Disruption of LCB Δ4 desaturase (des) significantly decreased the content of GlcCer. Fluorescence imaging analysis revealed that OsSLD-OX and AtSLD-OX showed increased plasma membrane fluidity, whereas des had less fluidity, demonstrating that the isomers universally contributed to increasing membrane fluidity. However, the results of a hydroponic assay showed decreased aluminum tolerance in AtSLD-OX and des compared to OsSLD-OX and the control plants, which did not correlate with membrane fluidity. These results suggest that cis-unsaturated GlcCer, not GIPC, selectively serves to maintain the membrane fluidity specifically associated with aluminum tolerance.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.3390/plants9010019
  DOI ID：10.3390/plants9010019, PubMed ID：31877922, PubMed Central ID：PMC7020186
• Glycosylinositol phosphoceramide-specific phospholipase D activity catalyzes transphosphatidylation.　　　　　　　　　　　　　　　
  Rumana Yesmin Hasi; Makoto Miyagi; Katsuya Morito; Toshiki Ishikawa; Maki Kawai-Yamada; Hiroyuki Imai; Tatsuya Fukuta; Kentaro Kogure; Kaori Kanemaru; Junji Hayashi; Ryushi Kawakami; Tamotsu Tanaka
  Journal of biochemistry, 巻：166, 号：5, 開始ページ：441, 終了ページ：448, 2019年11月, ［査読有り］, ［国際誌］
  Glycosylinositol phosphoceramide (GIPC) is the most abundant sphingolipid in plants and fungi. Recently, we detected GIPC-specific phospholipase D (GIPC-PLD) activity in plants. Here, we found that GIPC-PLD activity in young cabbage leaves catalyzes transphosphatidylation. The available alcohol for this reaction is a primary alcohol with a chain length below C4. Neither secondary alcohol, tertiary alcohol, choline, serine nor glycerol serves as an acceptor for transphosphatidylation of GIPC-PLD. We also found that cabbage GIPC-PLD prefers GIPC containing two sugars. Neither inositol phosphoceramide, mannosylinositol phosphoceramide nor GIPC with three sugar chains served as substrate. GIPC-PLD will become a useful catalyst for modification of polar head group of sphingophospholipid.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/jb/mvz056
  DOI ID：10.1093/jb/mvz056, PubMed ID：31504617
• One of the NAD kinases, sll1415, is required for the glucose metabolism of Synechocystis sp. PCC 6803.　　　　　　　　　　　　　　　
  Yuuma Ishikawa; Atsuko Miyagi; Toshiki Ishikawa; Minoru Nagano; Masatoshi Yamaguchi; Yukako Hihara; Yasuko Kaneko; Maki Kawai-Yamada
  The Plant journal : for cell and molecular biology, 巻：98, 号：4, 開始ページ：654, 終了ページ：666, 2019年05月, ［査読有り］, ［国際誌］
  Pyridine nucleotides (NAD(P)(H)) are electron carriers that are the driving forces in various metabolic pathways. Phosphorylation of NAD(H) to NADP(H) is performed by the enzyme NAD kinase (NADK). Synechocystis sp. PCC 6803 harbors two genes (sll1415 and slr0400) that encode proteins with NADK homology. When genetic mutants for sll1415 and slr0400 (Δ1415 and Δ0400, respectively) were cultured under photoheterotrophic growth conditions only the Δ1415 cells showed a growth defect. In wild-type cells, the sll1415 transcript accumulated after the cells were transferred to photoheterotrophic conditions. Furthermore, NAD(P)(H) measurements demonstrated that a dynamic metabolic conversion was implemented during the adaptation from photoautotrophic to photoheterotrophic conditions. Electron microscopy observation and biochemistry quantification demonstrated the accumulation of glycogen in the Δ1415 cells under photoheterotrophic conditions at 96 h. Quantitative real-time reverse transcription PCR (qRT-PCR) demonstrated the accumulation of mRNAs that encoded glycogen biosynthesis-related enzymes in photoheterotrophic Δ1415 cells. At 96 h, enzyme activity measurement in the photoheterotrophic Δ1415 cells demonstrated that the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were decreased, but the activities of glucose dehydrogenase were increased. Furthermore, metabolomics analysis demonstrated that the Δ1415 cells showed increased glucose-6-phosphate and 6-phosphogluconate content at 96 h. Therefore, sll1415 has a significant function in the oxidative pentose phosphate (OPP) pathway for catabolism of glucose under photoheterotrophic conditions. Additionally, it is presumed that the slr0400 had a different role in glucose catabolism during growth. These results suggest that the two Synechocystis sp. PCC 6803 NADKs (Sll1415 and Slr0400) have distinct functions in photoheterotrophic cyanobacterial metabolism.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/tpj.14262
  DOI ID：10.1111/tpj.14262, PubMed ID：30693583
• DSH5, a dihydrosphingosine C4 hydroxylase gene family member, shows spatially restricted expression in rice and is lethal when expressed ectopically.　　　　　　　　　　　　　　　
  Imamura T; Obata C; Yoneyama K; Ichikawa M; Ikura A; Mutsuro-Aoki H; Ishikawa T; Kawai-Yamada M; Sasaki T; Kusano H; Shimada H
  Genes Genet. Syst., 巻：93, 号：4, 開始ページ：135, 終了ページ：142, 2018年, ［査読有り］, ［国内誌］
  Dihydrosphingosine C4 hydroxylase (DSH), a diiron-binding membrane enzyme, catalyzes the hydration of dihydrosphingosine and acyl-sphinganine to produce phytosphingosine and phytoceramide, respectively. Rice has two types of DSH homologs: general DSHs, namely DSH1, DSH2 and DSH4, and others that show spatial expression profiles, namely DSH3 and DSH5. The general DSHs exist in many plant species. These DSHs showed similarity in their functions and complemented the yeast sur2D mutation. In contrast, homologs of DSH3 and DSH5 were found only in monocot plants. Phylogenetic analysis placed these DSHs in different clades that are evolutionarily divergent from those of the general DSHs. DSH3 and DSH5 showed low-level expression. DSH5 expression was specifically in vascular bundle tissues. Ectopic expression of DSH5 induced a dwarf phenotype characterized by severe growth inhibition and an increase in the thickness of the leaf body caused by enlargement of bulliform cells in the leaves. However, no significant difference was observed in the amount of sphingolipid species. DSH5 did not complement the yeast sur2D mutation, implying that DSH5 has little effect on sphingolipid metabolism. These findings suggested that DSH3 and DSH5 originated and diverged in monocot plants.
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1266/ggs.17-00054
  DOI ID：10.1266/ggs.17-00054, PubMed ID：30185720
• An NAC domain transcription factor ATAF2 acts as transcriptional activator or repressor dependent on promoter context.　　　　　　　　　　　　　　　
  Nagahage ISP; Sakamoto S; Nagano M; Ishikawa T; Kawai-Yamada M; Mitsuda N; Yamaguchi M
  Plant Biotech., 巻：35, 開始ページ：285, 終了ページ：289, 2018年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.18.0507a
  DOI ID：10.5511/plantbiotechnology.18.0507a
• Effects of inactivation of the cyAbrB2 transcription factor together with glycogen synthesis on cellular metabolism and free fatty acid production in the cyanobacterium Synechocystis sp. PCC 6803.　　　　　　　　　　　　　　　
  Kodama Y; Kawahara A; Miyagi A; Ishikawa T; Kawai-Yamada M; Kaneko Y; Takimura Y; Hihara Y
  Biotech. Bioeng., 巻：115, 開始ページ：2974, 終了ページ：2985, 2018年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/bit.26842
  DOI ID：10.1002/bit.26842
• Suppressing Arabidopsis GGLT1 affects growth by reducing the L-galactose content and borate cross-linking of rhamnogalacturonan II.　　　　　　　　　　　　　　　
  Sechet J; Htwe S; Urbanowicz B; Agyeman A; Feng W; Ishikawa T; Dinneny J; Colomes M; Satish Kumar K; Kawai-Yamada M; O'Neill M; Mortimer JC
  Plant J., 巻：96, 開始ページ：1036, 終了ページ：1050, 2018年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/tpj.14088
  DOI ID：10.1111/tpj.14088
• GLUCOSAMINE INOSITOLPHOSPHORYLCERAMIDE TRANSFERASE1 (GINT1) is a GlcNAc-containing glycosylinositol phosphorylceramide glycosyltransferase.　　　　　　　　　　　　　　　
  Ishikawa T; Fang L; Rennie EA; Sechet J; Yan J; Jing B; Moore W; Cahoon EB; Scheller HV; Kawai-Yamada M; Mortimer JC
  Plant Physiol., 巻：177, 開始ページ：938, 終了ページ：952, 2018年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.18.00396
  DOI ID：10.1104/pp.18.00396
• Synthesis and degradation of long-chain base phosphates affect fumonisin B-1-induced cell death in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Daiki Yanagawa; Toshiki Ishikawa; Hiroyuki Imai
  JOURNAL OF PLANT RESEARCH, 巻：130, 号：3, 開始ページ：571, 終了ページ：585, 2017年05月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s10265-017-0923-7
  DOI ID：10.1007/s10265-017-0923-7, ISSN：0918-9440, eISSN：1618-0860, Web of Science ID：WOS:000400234200018
• Loss of Inositol Phosphorylceramide Sphingolipid Mannosylation Induces Plant Immune Responses and Reduces Cellulose Content in Arabidopsis　　　　　　　　　　　　　　　
  Lin Fang; Toshiki Ishikawa; Emilie A. Rennie; Gosia M. Murawska; Jeemeng Lao; Jingwei Yan; Alex Yi-Lin Tsai; Edward E. K. Baidoo; Jun Xu; Jay D. Keasling; Taku Demura; Maki Kawai-Yamada; Henrik V. Scheller; Jenny C. Mortimer
  PLANT CELL, 巻：28, 号：12, 開始ページ：2991, 終了ページ：3004, 2016年12月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1105/tpc.16.00186
  DOI ID：10.1105/tpc.16.00186, ISSN：1040-4651, eISSN：1532-298X, Web of Science ID：WOS:000393167800009
• Molecular characterization and targeted quantitative profiling of the sphingolipidome in rice　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Yukihiro Ito; Maki Kawai-Yamada
  PLANT JOURNAL, 巻：88, 号：4, 開始ページ：681, 終了ページ：693, 2016年11月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/tpj.13281
  DOI ID：10.1111/tpj.13281, ISSN：0960-7412, eISSN：1365-313X, Web of Science ID：WOS:000389928200013
• Metabolomic analysis of NAD kinase-deficient mutants of the cyanobacterium Synechocystis sp PCC 6803　　　　　　　　　　　　　　　
  Yuuma Ishikawa; Atsuko Miyagi; Yuto Haishima; Toshiki Ishikawa; Minoru Nagano; Masatoshi Yamaguchi; Yukako Hihara; Maki Kawai-Yamada
  JOURNAL OF PLANT PHYSIOLOGY, 巻：205, 開始ページ：105, 終了ページ：112, 2016年10月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2016.09.002
  DOI ID：10.1016/j.jplph.2016.09.002, ISSN：0176-1617, eISSN：1618-1328, Web of Science ID：WOS:000385858600014
• Plasma Membrane Microdomains Are Essential for Rac1-RbohB/H-Mediated Immunity in Rice　　　　　　　　　　　　　　　
  Minoru Nagano; Toshiki Ishikawa; Masayuki Fujiwara; Yoichiro Fukao; Yoji Kawano; Maki Kawai-Yamada; Ko Shimamoto
  PLANT CELL, 巻：28, 号：8, 開始ページ：1966, 終了ページ：1983, 2016年08月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1105/tpc.16.00201
  DOI ID：10.1105/tpc.16.00201, ISSN：1040-4651, eISSN：1532-298X, Web of Science ID：WOS:000386169200016
• KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect L-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis　　　　　　　　　　　　　　　
  Shota Sawake; Noriaki Tajima; Jenny C. Mortimer; Jeemeng Lao; Toshiki Ishikawa; Xiaolan Yu; Yukiko Yamanashi; Yoshihisa Yoshimi; Maki Kawai-Yamada; Paul Dupree; Yoichi Tsumuraya; Toshihisa Kotake
  PLANT CELL, 巻：27, 号：12, 開始ページ：3397, 終了ページ：3409, 2015年12月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1105/tpc.15.00379
  DOI ID：10.1105/tpc.15.00379, ISSN：1040-4651, eISSN：1532-298X, Web of Science ID：WOS:000368297100010
• Glycosylated sphingolipid biosynthesis and function in Arabidopsis
  Jenny C. Mortimer; Toshiki Ishikawa; Lin Fang; Beibei Jing; Emilie Rennie; Noriko Inada; Xiaolan Yu; Jeemeng Lao; Taku Demura; Maki Kawai-Yamada; Henrik Scheller; Paul Dupree
  GLYCOBIOLOGY, 巻：25, 号：11, 開始ページ：1266, 終了ページ：1267, 2015年11月, ［査読有り］
  英語
  ISSN：0959-6658, eISSN：1460-2423, ORCID：45646360, Web of Science ID：WOS:000362991500108
• Overexpression of BAX INHIBITOR-1 Links Plasma Membrane Microdomain Proteins to Stress　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Toshihiko Aki; Shuichi Yanagisawa; Hirofumi Uchimiya; Maki Kawai-Yamada
  PLANT PHYSIOLOGY, 巻：169, 号：2, 開始ページ：1333, 終了ページ：1343, 2015年10月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1104/pp.15.00445
  DOI ID：10.1104/pp.15.00445, ISSN：0032-0889, eISSN：1532-2548, Web of Science ID：WOS:000365401000038
• Arabidopsis NAC domain proteins VND-INTERACTING1 and ANAC103 interact with multiple NAC domain proteins　　　　　　　　　　　　　　　
  Masatoshi Yamaguchi; Isura Sumeda Priyadarshana Nagahage; Misato Ohtani; Toshiki Ishikawa; Hirofumi Uchimiya; Maki Kawai-Yamada; Taku Demura
  PLANT BIOTECHNOLOGY, 巻：32, 号：2, 開始ページ：119, 終了ページ：U14, 2015年06月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.15.0208a
  DOI ID：10.5511/plantbiotechnology.15.0208a, ISSN：1342-4580, Web of Science ID：WOS:000356970600002
• Does the Upstream Region Possessing MULE-Like Sequence in Rice Upregulate PsbS1 Gene Expression?　　　　　　　　　　　　　　　
  Mohammed Nuruzzaman; Tatsuo Kanno; Rika Amada; Yoshiki Habu; Ichiro Kasajima; Toshiki Ishikawa; Maki Kawai-Yamada; Hirofumi Uchimiya
  PLOS ONE, 巻：9, 号：9, 開始ページ：e102742, 2014年09月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1371/journal.pone.0102742
  DOI ID：10.1371/journal.pone.0102742, ISSN：1932-6203, Web of Science ID：WOS:000342685600002
• Arabidopsis Bax inhibitor-1 promotes sphingolipid synthesis during cold stress by interacting with ceramide-modifying enzymes　　　　　　　　　　　　　　　
  Minoru Nagano; Toshiki Ishikawa; Yoshie Ogawa; Mitsuru Iwabuchi; Akari Nakasone; Ko Shimamoto; Hirofumi Uchimiya; Maki Kawai-Yamada
  PLANTA, 巻：240, 号：1, 開始ページ：77, 終了ページ：89, 2014年07月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00425-014-2065-7
  DOI ID：10.1007/s00425-014-2065-7, ISSN：0032-0935, eISSN：1432-2048, Web of Science ID：WOS:000338318300005
• Development of an LC-MS/MS Method for the Analysis of Free Sphingoid Bases Using 4-Fluoro-7-nitrobenzofurazan (NBD-F)　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Hiroyuki Imai; Maki Kawai-Yamada
  LIPIDS, 巻：49, 号：3, 開始ページ：295, 終了ページ：304, 2014年03月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s11745-013-3871-6
  DOI ID：10.1007/s11745-013-3871-6, ISSN：0024-4201, eISSN：1558-9307, Web of Science ID：WOS:000332665600009
• Culture temperature affects gene expression and metabolic pathways in the 2-methylisoborneol-producing cyanobacterium Pseudanabaena galeata　　　　　　　　　　　　　　　
  Masayuki Kakimoto; Toshiki Ishikawa; Atsuko Miyagi; Kazuaki Saito; Motonobu Miyazaki; Takashi Asaeda; Masatoshi Yamaguchi; Hirofumi Uchimiya; Maki Kawai-Yamada
  JOURNAL OF PLANT PHYSIOLOGY, 巻：171, 号：3-4, 開始ページ：292, 終了ページ：300, 2014年02月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jplph.2013.09.005
  DOI ID：10.1016/j.jplph.2013.09.005, ISSN：0176-1617, Web of Science ID：WOS:000332052200013
• Advanced LC-MS/MS techniques dissecting diverse isomers of plant sphingolipid species.　　　　　　　　　　　　　　　
  Ishikawa T; Yanagawa D; Kawai-Yamada M; Imai H
  J. Anal. Bioanal. Tech., 巻：S5, 開始ページ：7, 2014年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.4172/2155-9872.S5-007
  DOI ID：10.4172/2155-9872.S5-007
• Arabidopsis glycerol-3-phosphate permease 4 is localized in the plastids and involved in the accumulation of seed oil　　　　　　　　　　　　　　　
  Hiromitsu Kawai; Toshiki Ishikawa; Toshiaki Mitsui; Shin Kore-eda; Maki Kawai-Yamada; Jun-ichi Ohnishi
  PLANT BIOTECHNOLOGY, 巻：31, 号：2, 開始ページ：159, 終了ページ：U80, 2014年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.5511/plantbiotechnology.14.0222a
  DOI ID：10.5511/plantbiotechnology.14.0222a, ISSN：1342-4580, Web of Science ID：WOS:000339501900009
• Rapid Induction of Lipid Droplets in Chlamydomonas reinhardtii and Chlorella vulgaris by Brefeldin A　　　　　　　　　　　　　　　
  Sangwoo Kim; Hanul Kim; Donghwi Ko; Yasuyo Yamaoka; Masumi Otsuru; Maki Kawai-Yamada; Toshiki Ishikawa; Hee-Mock Oh; Ikuo Nishida; Yonghua Li-Beisson; Youngsook Lee
  PLOS ONE, 巻：8, 号：12, 開始ページ：e81978, 2013年12月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1371/journal.pone.0081978
  DOI ID：10.1371/journal.pone.0081978, ISSN：1932-6203, Web of Science ID：WOS:000328734200021
• The role of plant bax inhibitor-1 in suppressing H2O 2-induced cell death　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Hirofumi Uchimiya; Maki Kawai-Yamada
  Methods in Enzymology, 巻：527, 開始ページ：239, 終了ページ：256, 2013年, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/B978-0-12-405882-8.00013-1
  DOI ID：10.1016/B978-0-12-405882-8.00013-1, ISSN：0076-6879, ORCID：45646377, PubMed ID：23830635, SCOPUS ID：84879857652, Web of Science ID：WOS:000322846400014
• Nitrate Addition Alleviates Ammonium Toxicity Without Lessening Ammonium Accumulation, Organic Acid Depletion and Inorganic Cation Depletion in Arabidopsis thaliana Shoots　　　　　　　　　　　　　　　
  Takushi Hachiya; Chihiro K. Watanabe; Masaru Fujimoto; Toshiki Ishikawa; Kentaro Takahara; Maki Kawai-Yamada; Hirofumi Uchimiya; Yukifumi Uesono; Ichiro Terashima; Ko Noguchi
  PLANT AND CELL PHYSIOLOGY, 巻：53, 号：3, 開始ページ：577, 終了ページ：591, 2012年03月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcs012
  DOI ID：10.1093/pcp/pcs012, ISSN：0032-0781, eISSN：1471-9053, Web of Science ID：WOS:000301359500008
• Midgut juice of Plutella xylostella highly resistant to Bacillus thuringiensis Cry1Ac contains a three times larger amount of glucosinolate sulfatase which binds to Cry1Ac compared to that of susceptible strain　　　　　　　　　　　　　　　
  Takanori Yamazaki; Toshiki Ishikawa; Ganesh N. Pandian; Keiichi Okazaki; Kohsuke Haginoya; Yuka Tachikawa; Toshiaki Mitsui; Kazuhisa Miyamoto; Chanan Angusthanasombat; Hidetaka Hori
  PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY, 巻：101, 号：2, 開始ページ：125, 終了ページ：131, 2011年10月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.pestbp.2011.09.001
  DOI ID：10.1016/j.pestbp.2011.09.001, ISSN：0048-3575, eISSN：1095-9939, Web of Science ID：WOS:000296401900010
• Bax inhibitor-1: a highly conserved endoplasmic reticulum-resident cell death suppressor　　　　　　　　　　　　　　　
  T. Ishikawa; N. Watanabe; M. Nagano; M. Kawai-Yamada; E. Lam
  CELL DEATH AND DIFFERENTIATION, 巻：18, 号：8, 開始ページ：1271, 終了ページ：1278, 2011年08月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1038/cdd.2011.59
  DOI ID：10.1038/cdd.2011.59, ISSN：1350-9047, Web of Science ID：WOS:000292634000006
• Bax inhibitor-1による細胞膜マイクロドメインを介した細胞死抑制機構の解析　　　　　　　　　　　　　　　
  石川 寿樹; 秋 利彦; 柳澤 修一; 内宮 博文; 川合 真紀
  日本植物生理学会年会およびシンポジウム 講演要旨集, 巻：2011, 開始ページ：0404, 終了ページ：0404, 2011年
  Bax inhibitor-1 (BI-1) は高等動植物が共通に持つ小胞体局在の細胞死制御因子であり、様々な環境ストレス下における酸化ストレス誘導性細胞死の抑制に寄与する。シロイヌナズナのBI-1 (AtBI-1) は小胞体においてスフィンゴ脂質代謝酵素と相互作用することから、スフィンゴ脂質がBI-1の作用機構に重要な役割を持つことが示唆されている。スフィンゴ脂質は細胞膜マイクロドメインの主要構成因子であり、その分子組成の変化はマイクロドメイン機能に影響を及ぼすことが予想される。そこでAtBI-1過剰発現イネ培養細胞の細胞膜マイクロドメイン構成成分を解析したところ、スフィンゴ糖脂質の増加とタンパク質プロファイルの変化が見出され、AtBI-1によるスフィンゴ脂質代謝の亢進が細胞膜マイクロドメイン構造に影響を及ぼすことが明らかとなった。さらにショットガンプロテオーム解析により、AtBI-1過剰発現細胞で顕著に減少しているタンパク質として過敏感細胞死関連因子やシグナル伝達複合体形成に関与する因子が同定され、これらを介した細胞死抑制メカニズムがBI-1の下流で機能していることが示唆された。本発表では、同定したマイクロドメイン局在タンパク質のストレス誘導性細胞死における機能について報告し、植物の細胞死制御機構における細胞膜マイクロドメインの役割について議論したい。
  日本植物生理学会
  DOI：https://doi.org/10.14841/jspp.2011.0.0404.0
  DOI ID：10.14841/jspp.2011.0.0404.0, CiNii Articles ID：130006997013
• ショットガンプロテオミクスによる植物のストレス誘導性細胞死制御に関わる細胞膜マイクロドメインタンパク質の探索　　　　　　　　　　　　　　　
  石川 寿樹; 秋 利彦; 柳澤 修一; 長野 稔; 内宮 博文; 川合 真紀
  日本プロテオーム学会大会要旨集, 巻：2011, 開始ページ：215, 終了ページ：215, 2011年
  日本プロテオーム学会（日本ヒトプロテオーム機構）, 日本語
  DOI：https://doi.org/10.14889/jhupo.2011.0.215.0
  DOI ID：10.14889/jhupo.2011.0.215.0, CiNii Articles ID：130005454359
• Formation of Macromolecule Complex with Bacillus thuringiensis Cry1A Toxins and Chlorophyllide Binding 252-kDa Lipocalin-Like Protein Locating on Bombyx mori Midgut Membrane　　　　　　　　　　　　　　　
  Ganesh N. Pandian; Toshiki Ishikawa; Thangavel Vaijayanthi; Delwar M. Hossain; Shuhei Yamamoto; Tadayuki Nishiumi; Chanan Angsuthanasombat; Kohsuke Haginoya; Toshiaki Mitsui; Hidetaka Hori
  JOURNAL OF MEMBRANE BIOLOGY, 巻：237, 号：2-3, 開始ページ：125, 終了ページ：136, 2010年10月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00232-010-9314-x
  DOI ID：10.1007/s00232-010-9314-x, ISSN：0022-2631, Web of Science ID：WOS:000284542200007
• Isoform-Specific Localization of Brassica rapa Nitrilases in Root Infected with Plasmodiophora brassicae Revealed Using In Situ Hybridization Probes Improved with Locked Nucleic Acids　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Keiichi Okazaki; Tomohiko Nagaoka; Kimiko Itoh; Toshiaki Mitsui; Hidetaka Hori
  JOURNAL OF PLANT GROWTH REGULATION, 巻：29, 号：2, 開始ページ：210, 終了ページ：222, 2010年06月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00344-009-9131-6
  DOI ID：10.1007/s00344-009-9131-6, ISSN：0721-7595, Web of Science ID：WOS:000277939500008
• Identification of QTLs that control clubroot resistance in Brassica oleracea and comparative analysis of clubroot resistance genes between B. rapa and B. oleracea　　　　　　　　　　　　　　　
  T. Nagaoka; M. A. U. Doullah; S. Matsumoto; S. Kawasaki; T. Ishikawa; H. Hori; K. Okazaki
  THEORETICAL AND APPLIED GENETICS, 巻：120, 号：7, 開始ページ：1335, 終了ページ：1346, 2010年05月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s00122-010-1259-z
  DOI ID：10.1007/s00122-010-1259-z, ISSN：0040-5752, Web of Science ID：WOS:000276674500005
• Metabolome Analysis of Response to Oxidative Stress in Rice Suspension Cells Overexpressing Cell Death Suppressor Bax Inhibitor-1　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Kentaro Takahara; Takayuki Hirabayashi; Hideo Matsumura; Shizuko Fujisawa; Ryohei Terauchi; Hirofumi Uchimiya; Maki Kawai-Yamada
  PLANT AND CELL PHYSIOLOGY, 巻：51, 号：1, 開始ページ：9, 終了ページ：20, 2010年01月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1093/pcp/pcp162
  DOI ID：10.1093/pcp/pcp162, ISSN：0032-0781, eISSN：1471-9053, Web of Science ID：WOS:000273704500002
• Loss of Calmodulin Binding to Bax Inhibitor-1 Affects Pseudomonas-mediated Hypersensitive Response-associated Cell Death in Arabidopsis thaliana　　　　　　　　　　　　　　　
  Maki Kawai-Yamada; Zenta Hori; Taro Ogawa; Yuri Ihara-Ohori; Katsunori Tamura; Minoru Nagano; Toshiki Ishikawa; Hirofumi Uchimiya
  JOURNAL OF BIOLOGICAL CHEMISTRY, 巻：284, 号：41, 開始ページ：27998, 終了ページ：28003, 2009年10月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1074/jbc.M109.037234
  DOI ID：10.1074/jbc.M109.037234, ISSN：0021-9258, Web of Science ID：WOS:000270676300028
• Bombyx mori midgut membrane protein P252, which binds to Bacillus thuringiensis Cry1A, is a chlorophyllide-binding protein, and the resulting complex has antimicrobial activity　　　　　　　　　　　　　　　
  Ganesh N. Pandian; Toshiki Ishikawa; Makoto Togashi; Yasuyuki Shitomi; Kohsuke Haginoya; Shuhei Yamamoto; Tadayuki Nishiumi; Hidetaka Hori
  APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 巻：74, 号：5, 開始ページ：1324, 終了ページ：1331, 2008年03月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1128/AEM.01901-07
  DOI ID：10.1128/AEM.01901-07, ISSN：0099-2240, eISSN：1098-5336, Web of Science ID：WOS:000253792700004
• Molecular cloning of Brassica rapa nitrilases and their expression during clubroot development　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Keiichi Okazaki; Haruka Kuroda; Kimiko Itoh; Toshiaki Mitsui; Hidetaka Hori
  MOLECULAR PLANT PATHOLOGY, 巻：8, 号：5, 開始ページ：623, 終了ページ：637, 2007年09月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/J.1364-3703.2007.00414.X
  DOI ID：10.1111/J.1364-3703.2007.00414.X, ISSN：1464-6722, Web of Science ID：WOS:000249160800007
• Plasmodiophora brassicae-induced cell death and medium alkalization in clubroot-resistant cultured roots of Brassica rapa　　　　　　　　　　　　　　　
  H Takahashi; T Ishikawa; M Kaido; K Takita; T Hayakawa; K Okazaki; K Itoh; T Mitsui; H Hori
  JOURNAL OF PHYTOPATHOLOGY, 巻：154, 号：3, 開始ページ：156, 終了ページ：162, 2006年03月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1111/j.1439-0434.2006.01076.x
  DOI ID：10.1111/j.1439-0434.2006.01076.x, ISSN：0931-1785, Web of Science ID：WOS:000235357600005

• メタボローム解析から探るイネのカマイラズ変異体の代謝変動　　　　　　　　　　　　　　　
  宮城敦子; 宮城敦子; 森和久; 石川寿樹; 大久保智司; 安達俊輔; 大川泰一郎; 山口雅利; 小竹敬久; 川合真紀
  日本植物生理学会年会(Web), 巻：64th, 2023年
  J-Global ID：202302234679567567
• イネのカマイラズ変異体における代謝変動　　　　　　　　　　　　　　　
  宮城敦子; 森和久; 大久保智司; 安達俊輔; 大川泰一郎; 石川寿樹; 山口雅利; 小竹敬久; 川合真紀
  日本植物学会大会研究発表記録(CD-ROM), 巻：85th, 2021年
  J-Global ID：202302210880983493
• シロイヌナズナVND遺伝子群の遺伝学的解析
  伊藤敦也; 久保稔; 大谷美沙都; 石川寿樹; 川合真紀; 出村拓; 山口雅利
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：36th, 開始ページ：153, 2018年08月15日
  日本語
  J-Global ID：201802264094945466
• 植物に見出されたグリコシルイノシトールホスホセラミド特異的ホスホリパーゼDの性質　　　　　　　　　　　　　　　
  田中保; 宮城諒; 辻和樹; 藤原美奈; 森戸克弥; 石川寿樹; 今井博之; 川合真紀; 福田達也; 小暮健太朗
  日本農芸化学会中四国支部講演会講演要旨集(Web), 巻：51st, 2018年
  J-Global ID：201802215895962288
• 植物に見出されたグリコシルイノシトールホスホセラミド特異的ホスホリパーゼDの性質　　　　　　　　　　　　　　　
  宮城諒; 辻和樹; 藤原美奈; 森戸克弥; 石川寿樹; 今井博之; 川合真紀; 福田達也; 小暮健太朗; 田中保
  日本生化学会大会(Web), 巻：91st, 2018年
  J-Global ID：201902296826129470
• NAD(P)代謝改変シロイヌナズナの作出および代謝解析　　　　　　　　　　　　　　　
  鈴木渉太; 宮城敦子; 石川寿樹; 刑部敬史; 長野稔; 山口雅利; 川合真紀
  日本植物細胞分子生物学会大会・シンポジウム講演要旨集, 巻：33rd, 開始ページ：140, 2015年07月20日
  日本語
  J-Global ID：201502202919376033
• カブ根こぶ病感染組織におけるエチレン合成　　　　　　　　　　　　　　　
  石川 寿樹; 岡崎 桂一; 伊藤 紀美子; 三ツ井 敏明; 堀 秀隆; 石川 寿樹; 岡崎 桂一; 伊藤 紀美子; 三ツ井 敏明; 堀 秀隆
  新潟大学農学部研究報告, 巻：63, 号：2, 開始ページ：83, 終了ページ：87, 2011年03月
  Auxin and cytokinin play a crucial role for initiation stage of clubroot development in Plasmodiophora brassicaeinfectedcruciferous plants. On the other hand, the roles of phytohormones in a later maturation stage of clubroot remainunclear, regardless of significant accumulation of endogenous auxin indole-3-acetic acid (IAA) in fully developed clubrootgetting deteriorated. Here we analyzed the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) contents andACC oxidase (ACO) activity during clubroot development in turnip (Brassica rapa) to evaluate involvement of ethylene inclubroot development. Ethylene biosynthesis capacity estimated from endogenous ACC contents and ACO activity wasnot significantly affected in early growing clubroot but was elevated in later maturating tissues. This result suggests thatethylene biosynthesis is affected by P. brassicae infection and its level was coordinated with IAA during the maturationphase. Real-time PCR analysis of nitrilase, an IAA biosynthetic enzyme, demonstrated that treatment of turnip roots withACC inhibits nitrilase expression, whereas ACC-dependent ethylene biosynthesis is well-known to be upregulated by IAA.These insights imply that IAA biosynthesis via nitrilase precedes and induces ethylene production in the maturatingclubroot. This is the first report that ethylene could be involved in the maturation and deterioration of clubroot.Plasmodiophora brassicae 感染による根こぶ組織形成の初期段階におけるオーキシンやサイトカイニンといった植物ホルモンの関与がよく知られる一方で、根こぶ組織の成熟、腐熟段階における植物ホルモンの関与はほとんどわかっていない。本研究では、根こぶ組織成熟過程へのエチレンの関与に着目し、根こぶ病の進行に伴うエチレン前駆体1- アミノシクロプロパン-1- カルボン酸（ACC）含量とACC 酸化酵素（ACO）活性の変動を解析した。ACC 含量とACO 活性から推定されるエチレン生合成活性は、肥大初期の根こぶ組織で大きな変化は無かったが、肥大後期から腐熟期にある根こぶ組織では大きく増加していることが示された。リアルタイム定量PCR 解析の結果、ACC はオーキシン合成酵素ニトリラーゼのmRNA 発現を強く抑制することが明らかとなり、根こぶ成熟期におけるオーキシンの増加はエチレンの蓄積に先立って起こることが示唆された。
  新潟大学農学部, 英語
  ISSN：0385-8634, CiNii Articles ID：120005068686, CiNii Books ID：AN00183393
• Locked nucleic acid(LNA)を利用した高性能ハイブリダイゼーションプローブの作製　　　　　　　　　　　　　　　
  石川 寿樹; 岡崎 桂一; 伊藤 紀美子; 三ツ井 敏明; 堀 秀隆; Ishikawa Toshiki; Okazaki Keiichi; Itoh Kimiko; Mitsui Toshiaki; Hori Hidetaka
  新潟大学農学部研究報告, 巻：63, 号：1, 開始ページ：35, 終了ページ：39, 2010年08月
  高度に保存された塩基配列を有するmRNA のin situ hybridization（ISH）による特異的検出を目的として、locked nucleicacid（LNA）を利用したキメラオリゴヌクレオチドプローブを作製し、その実用性を評価した。塩基配列で90％以上の相同性を示すカブのニトリラーゼアイソフォームBrNIT-T1及びBrNIT-T2との間で相同性の低い24～25塩基の領域に相補的なオリゴヌクレオチドを設計し、両者間で異なる塩基（９～10塩基）をLNA に置換したLNA-DNA キメラオリゴヌクレオチドを作製した。配列中にLNA を部分的に導入することにより、DNA のみでは55～57℃であったオリゴヌクレオチドのTm 値は78～82℃に上昇し、ISH 解析に十分な値を示した。BrNIT-T1及びBrNIT-T2の全長転写産物に対する結合性をドットブロットノザンハイブリダイゼーションにより調査したところ、BrNIT-T1及びBrNIT-T2のそれぞれの配列に対応するLNA-DNA キメラプローブは互いの転写産物に非特異的に結合することなく、目的の転写産物のみを検出できることが確認された。さらにこれらのキメラプローブをカブ根こぶ病組織のISH 解析に応用し、従来のcRNA プローブを用いた解析では得られなかった、BrNIT-T1とBrNIT-T2の時空間的な発現特異性を明らかにすることに成功した。To achieve specific detection of highly-conserved sequences by in situ hybridization (ISH), locked nucleic acid(LNA)-containing oligonucleotide probes were designed and assessed. Two isoforms of turnip nitrilases, BrNIT-T1 andBrNIT-T2, that possess more than 90% homology at the nucleotide level, were targeted in this study. Oligonucleotidescorresponding to a relatively different region between BrNIT-T1 and BrNIT-T2 were generated to contain LNAs in placeof DNA bases different between the two sequences. The partial incorporation of LNA into DNA oligonucleotides providedsufficient Tm values for ISH analysis. Dot-blot hybridization assay confirmed that the two LNA-modified oligonucleotideprobes corresponding to sequences of BrNIT-T1 and BrNIT-T2 specifically hybridized with the desired RNA sequencebut not with another one. Advantages of the LNA-modified probes in ISH analysis were also observed as specific andsensitive detection of BrNIT-T localization. Based on these results, we here report that partial incorporation of LNA intooligonucleotide probe is useful for highly specific detection of similar genes in ISH analysis.
  新潟大学農学部, 日本語
  ISSN：0385-8634, CiNii Articles ID：120005067423, CiNii Books ID：AN00183393
• 根こぶ病罹病カブのオーキシン生合成とホルモンクロストークにおけるニトリラーゼの役割　　　　　　　　　　　　　　　
  石川 寿樹; 岡崎 桂一; 堀 秀隆
  植物の生長調節 = Regulation of plant growth & development, 巻：42, 開始ページ：25, 終了ページ：25, 2007年10月05日
  Plasmodiophora brassicae parasitizes cruciferous plant roots and manipulates indole-3-acetic acid (IAA) biosynthesis system of host plants to induce hypertrophy, called clubroot. We isolated three cDNAs encoding nitrilase from Brassica rapa (turnip), i.e. BrNIT-T1, BrNIT-T2 and BrNIT-T4. Enzyme analysis of recombinant proteins showed that BrNIT-T1 and BrNIT-T2 possess IAA synthetic activity, but BrNIT-T4 is involved in the plant cyanide detoxification pathway downstream of ethylene production. Realtime PCR analysis revealed specific involvement of BrNIT-T1 in clubroot initiation phase: in early-growing clubroot, BrNIT-T1 was strongly up-regulated but BrNIT-T2 and BrNIT-T4 were down-regulated. In maturing clubroot, not only BrNIT-T1 but also BrNIT-T2 and BrNIT-T4 were up-regulated. Free IAA level was transiently elevated at the early and later phases, despite a high IAA conjugation activity throughout disease development. Ethylene-forming activity was reduced during clubroot formation but subsequently increased, just like BrNIT-T4 expression. These results indicate a close relationship of the nitrilases to auxin and ethylene biosynthesis. Treatment of roots with cytokinin or jasmonic acid activated BrNIT-T1 or BrNIT-T2 expression, respectively. Thus, the two phytohormones may trigger IAA production in clubroot. Based on these observations, we propose a scheme regarding individual roles of the nitrilases in hormone crosstalk during clubroot initiation and maturation in turnip.
  植物化学調節学会, 日本語
  ISSN：1346-5406, CiNii Articles ID：110006474705, CiNii Books ID：AA11550064
• カイコアミノペプチダーゼNの培養昆虫細胞膜への発現提示と殺虫性毒素Cry トキシン受容体機能の解析　　　　　　　　　　　　　　　
  野口 理恵子; 石川 寿樹; 萩野谷 功輔; 蔀 泰幸; 佐藤 令一; 早川 徹; 堀 秀隆
  新潟大学農学部研究報告, 巻：60, 号：1, 開始ページ：73, 終了ページ：81, 2007年08月
  カイコガ(Bombyx mori)幼虫の中腸上皮細胞アピカル膜上のブラシ状膜(Brush Border Membrane;BBM)に存在するタンパク質のアミノペプチダーゼN1(BmAPN1)は、鱗翅目昆虫を特異的に殺す毒素Cry1Aa の受容体と考えられているが、その確証は未だ示されていない。BmAPN1が毒性発揮へ関与するかを確認するために、BmAPN1を培養昆虫細胞膜に発現させCry1Aa との相互作用を調査した。昆虫培養細胞株のHigh Five 細胞を用いたバキュロウイルス発現系を構築した。組換ウイルスの感染により、感染処理から48時間後には110 kDa のBmAPN1が発現し細胞膜上に提示された。アミノペプチダーゼ活性は非感染細胞の10倍あり、BmAPN1の活性が保持されていることが示された。High Five 細胞に発現したBmAPN1の分子サイズは、BBM 上に存在するBmAPN1と同程度で、細胞膜上に存在した。組換BmAPN1が活性を持ちしかも細胞膜上に提示されたことで、この発現システムは、アミノペプチダーゼとCry1Aa との相互作用を解析する上で非常に役立つと期待された。
  新潟大学, 日本語
  ISSN：0385-8634, CiNii Articles ID：110006387670, CiNii Books ID：AN00183393
• Brassica rapa 培養根の根こぶ病病原菌Plasmodiophora brassicae に対する抵抗反応のプロテオーム解析　　　　　　　　　　　　　　　
  海道 正和; 石川 寿樹; 堀 秀隆
  新潟大学農学部研究報告, 巻：60, 号：1, 開始ページ：67, 終了ページ：71, 2007年08月
  根こぶ病菌感染初期反応を解明するため、根こぶ病菌感受性と抵抗性の2系統のカブから誘導した培養根に根こぶ病菌Plasmodiophora brassicae の胞子を処理し、タンパク質の消長を2-D PAGE で検出した。無処理区及び胞子処理区の感受性、抵抗性両系統由来培養根からは、251スポットのタンパク質が検出された。無処理区で比較すると、251のうち11スポットは抵抗性系統で強発現し、8スポットは感受性系統で強発現していた。感受性培養根では胞子処理で6スポットの発現量が増大し、逆に7スポットでは低下した。これらのタンパク質はおそらく、根毛での感染に必要な反応あるいは病原菌非特異的な防御反応に関与していると思われる。一方胞子処理区の抵抗性培養根では、10スポットの発現が増大し13スポットで減少した。これら抵抗性培養根における胞子処理に対するタンパク質の消長は感受性のそれとは明らかに異なっており、この中に抵抗性反応特異的なタンパク質があると考えられた。
  新潟大学, 英語
  ISSN：0385-8634, CiNii Articles ID：110006387666, CiNii Books ID：AN00183393
• インドール-3-アセトアミドをインドール-3-酢酸に変換する酵素アミダーゼのカブ根こぶ病における役割の評価　　　　　　　　　　　　　　　
  石川 寿樹; 黒田 春香; 岡崎 桂一; 伊藤 紀美子; 三ツ井 敏明; 堀 秀隆
  新潟大学農学部研究報告, 巻：60, 号：1, 開始ページ：53, 終了ページ：60, 2007年08月
  Amidase was investigated if it was one of auxin-producing enzymes of Brassica rapa. We found amidase activity to convert indole-3-acetamide to indole-3-acetic acid in soluble protein extracts from B. rapa. Optimum condition for the enzyme activity was searched and two optimum temperatures were obtained at 45 and 55℃. Search for the heat stability of the enzyme strongly suggested that the two summits of the optimum temperatures were resulted from occurrence of variant amidases showing different temperature stabilities. The possibility of the presence of several amidase isoforms was supported by the following two observations, i.e., firstly, amidase activities at 45 and 55℃ had different pH optimums, 8.5 and 7.5, respectively. Secondly, the enzyme activities at the two temperatures were differentially fluctuated during the vegetative growth of turnip and clubroot development. Fluctuation of the amidase activity and IAA contents observed in various turnip tissues such as healthy turnip leaf, hypocotyl and roots suggested that the enzyme had a constitutive role for keeping IAA homeostasis in those tissues. Interestingly, the amidase in turnip was shown to have high activity in hypocotyl and root rather than leaf, unlike Arabidopsis one. Changes of the enzyme activity during development of B. rapa was analyzed using the tissues of clubrootdiseased turnips. The activities fluctuated differently from each other in the temperature at 45 and 55℃ in infected tissues. In addition, activity at 45℃ was specifically enhanced in a later phase of clubroot development, whereas one at 55℃ increased only in an early phase in the infected root tissues. These results indicated that the amidase played an important role in turnip growth and clubroot development. 根こぶ病菌Plasmodiophora brassicae による根こぶ形成の分子機構解明を目的にオーキシン合成酵素の1つアミダーゼ活性を、カブ組織から可溶性粗酵素画分を調製し測定した。活性最適温度は45及び55℃であり、最適pH は、反応温度45℃でpH 8.5、55℃でpH 7.5付近であった。熱安定性を調べる為、粗酵素画分を45または55℃で加熱し、その後45及び55℃の反応温度で残存活性を測定した。45℃熱処理では、両測定温度で失活パターンは同一であった。55℃熱処理では、45℃での活性は70% 失活し、55℃では60％の活性が残存した。発芽後20～40日の間５日毎に健全カブと根こぶ病感染カブの葉、胚軸、根のアミダーゼ活性とIAA 含量を測定し根こぶ病とアミダーゼの関係を調べた。健全カブでは、上記全組織で安定なアミダーゼ活性があり恒常的な機能が推測された。一方感染カブの根で初期に55℃での活性が、後期には45℃の活性がそれぞれ健全カブより増加した。本研究で、複数のアミダーゼが存在し、それらが独立で根こぶ病発現に関与する可能性が初めて示唆された。
  新潟大学農学部, 英語
  ISSN：0385-8634, CiNii Articles ID：110006387205, CiNii Books ID：AN00183393
• 根こぶ病抵抗性カブ(Brassica rapa L.)培養根へのFura-2の導入と細胞内Ca2+ 濃度の測定　　　　　　　　　　　　　　　
  高橋 秀行; 石川 寿樹; 早川 徹; 伊藤 紀美子; 三ツ井 敏明; 堀 秀隆
  新潟大学農学部研究報告, 巻：60, 号：1, 開始ページ：61, 終了ページ：66, 2007年08月
  我々は以前の研究において、カブ(Brassica rapa L.)幼根から誘導した培養根を用い、根こぶ病菌Plasmodiophora brassicaeに対する初期抵抗反応の誘導にCa2+ が必要であることを示した(Takahashi et al., 2006)。本研究では、根こぶ病抵抗反応におけるカブ培養根の細胞内Ca2+ 濃度([Ca2+]cyt)の変動を調査するため、Ca2+ の蛍光指示薬Fura-2のアセトキシメチルエステル(Fura-2/AM)をカブ培養根に導入し、蛍光顕微鏡により[Ca2+]cyt を定量的に解析することを試みた。蛍光顕微鏡下で細胞質内にFura-2が導入されたことが確認できたカブ培養根に、カルシウムイオノフォアA23187とCa2+ を同時に処理すると、直ちに[Ca2+]cyt の相対値を示すFura-2蛍光比が上昇したことから、Fura-2/AM を用いた本手法は、培養根における[Ca2+]cyt の変化を観察するのに適していることが示された。さらに[Ca2+]cyt を増加させることが知られている外的刺激として、マンニトール及びNaCl の高濃度処理を行ったところ、同様なFura-2蛍光比の急激な増加が観察され、本手法の汎用性が示された。次に、我々は本来の目的である根こぶ病抵抗反応における[Ca2+]cyt の解析に本手法を応用した。Fura-2/AM を導入した根こぶ病抵抗性カブ培養根にP. brassicae の休眠胞子を処理しても、500秒の測定時間内に[Ca2+]cyt が変化することは無かった。しかし休眠胞子を発芽促進液(GES: germination enhancing suspension)で前処理し、同様の実験を行ったところ、非常にわずかであったものの、再現性ある[Ca2+]cyt の上昇が観察された。根こぶ病に対する初期抵抗反応におけるCa2+ の重要性を立証するためには、今後さらなる解析が必要であるが、その過程において本手法は大きく貢献するものと期待される。
  新潟大学, 英語
  ISSN：0385-8634, CiNii Articles ID：110006387665, CiNii Books ID：AN00183393

• セラミド研究の新展開　　　　　　　　　　　　　　　
  石川 寿樹; 今井 博之, ［共著］, 総論編・第７章「植物のセラミド関連脂質」
  食品化学新聞社, 2019年06月
• The role of plant Bax inhibitor-1 in suppressing H2O2-induced cell death.　　　　　　　　　　　　　　　
  石川 寿樹, ［共著］
  Methods in Enzymol., 2013年

• 植物GIPCの構造多様性と代謝機構：リピドミクスからのアプローチ　　　　　　　　　　　　　　　
  第15回セラミド研究会学術集会, 2022年10月, ［招待有り］
  口頭発表（招待・特別）
  共同研究・競争的資金等ID：13207319;12237085
• 植物スフィンゴ脂質のターゲットメタボロミクス　　　　　　　　　　　　　　　
  石川寿樹
  第16回メタボロームシンポジウム, 2022年09月, ［招待有り］
  口頭発表（招待・特別）
  共同研究・競争的資金等ID：12237085;13207319
• 分子進化から読み解く植物独自のスフィンゴ脂質多様化戦略　　　　　　　　　　　　　　　
  石川寿樹
  日本植物学会第84回大会, 2020年09月, ［招待有り］
  2020年09月 - 2020年09月, 日本語, 口頭発表（招待・特別）
• The Evolutionary Journey of Plant-Unique Long-Chain Base Unsaturation　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Maki Kawai-Yamada
  The 23rd International Symposium on Plant Lipids, 2018年07月, ［国際会議］
  英語, 口頭発表（一般）
• New insights into molecular evolution of sphingolipid unsaturation in plants　　　　　　　　　　　　　　　
  Toshiki Ishikawa; Maki Kawai-Yamada
  7th Asian Symposium on Plant Lipid, 2017年11月
  2017年11月 - 2017年12月, 英語, 口頭発表（一般）
• 長鎖塩基不飽和化を介したスフィンゴ脂質合成制御とストレス耐性　　　　　　　　　　　　　　　
  石川 寿樹; 川合真紀
  日本植物学会第78回年会, 2014年09月, ［招待有り］, ［国内会議］
  日本語, シンポジウム・ワークショップパネル（指名）
• ショットガンプロテオミクスによる植物のストレス誘導性細胞死制御に関わる細胞膜マイクロドメインタンパク質の探索　　　　　　　　　　　　　　　
  石川寿樹; 秋利彦; 柳澤修一; 長野稔; 内宮博文; 川合真紀
  日本プロテオーム学会2011年大会, 2011年07月, ［招待有り］, ［国内会議］
  日本語, シンポジウム・ワークショップパネル（指名）

• 2022年04月 - 現在
  基礎生化学, 埼玉大学
• 2021年04月 - 現在
  脂質生化学, 埼玉大学
• 生活と環境, 浦和大学
• 生き物の科学, 浦和大学
• 生物英語I, 埼玉大学
• 生物学基礎, 埼玉大学
• 生物学序説, 埼玉大学
• 化学序説, 埼玉大学
• 工学入門セミナー, 埼玉大学
• 植物生理学, 埼玉大学

• セラミド研究会
• 日本植物脂質研究会
• 日本植物学会
• 日本植物細胞分子生物学会
• 日本植物生理学会
• 日本脂質生化学会
• 日本生化学会

• 植物スフィンゴ脂質GIPCの加水分解を起点とする新奇植物免疫シグナル機構の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 挑戦的研究(萌芽), 2024年06月28日 - 2026年03月31日
  田中 秀則; 田中 保; 石川 寿樹; 長野 稔, 岐阜大学
  配分額（総額）：6500000, 配分額（直接経費）：5000000, 配分額（間接経費）：1500000
  課題番号：24K21848
• 食品成分として未開拓なホスホイノシトール含有スフィンゴ脂質の評価　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2023年04月01日 - 2026年03月31日
  菅原 達也; 安藤 晃規; 石川 寿樹; 真鍋 祐樹, 京都大学
  配分額（総額）：19110000, 配分額（直接経費）：14700000, 配分額（間接経費）：4410000
  課題番号：23H02158
• スフィンゴ脂質の糖鎖型に依存的な種子サイズ制御機構の解明とゲノム育種利用　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(C), 2022年04月 - 2025年03月
  石川 寿樹, 埼玉大学
  配分額（総額）：4290000, 配分額（直接経費）：3300000, 配分額（間接経費）：990000
  課題番号：22K05553
• 植物独自のスフィンゴ脂質糖鎖構造多様性が担う生物学的意義の解明　　　　　　　　　　　　　　　
  文部科学省, 科研費･基盤（C）, 2019年04月 - 2022年03月
  石川 寿樹, 研究代表者
  競争的資金
  講演・口頭発表等ID：42182940
• 植物固有なスフィンゴ脂質糖鎖の形成機構と生物学的機能の解明　　　　　　　　　　　　　　　
  文部科学省, 科研費・若手（B）, 2017年04月 - 2019年03月
  石川 寿樹, 研究代表者
  競争的資金
  講演・口頭発表等ID：42182940
• 植物スフィンゴ脂質の分子機能解明と代謝改変技術の確立　　　　　　　　　　　　　　　
  文部科学省, 科研費・若手（B）, 2015年04月 - 2017年03月
  石川 寿樹, 研究代表者
  競争的資金
• 植物スフィンゴ脂質代謝酵素の機能同定と分子育種への利用　　　　　　　　　　　　　　　
  日本学術振興会, 特別研究員奨励費, 2012年04月 - 2014年03月
  石川 寿樹, 研究代表者
  競争的資金
• リピドミクスを基盤とした植物スフィンゴ脂質分子種の機能解析と育種利用　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 若手研究(B), 2012年04月01日 - 2013年03月31日
  石川 寿樹, 埼玉大学
  配分額（総額）：4550000, 配分額（直接経費）：3500000, 配分額（間接経費）：1050000
  課題番号：24780328