Faculty Profiles - NAKAMURA Yoshimasa

Papers - NAKAMURA Yoshimasa

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Involvement of extracellular oxidative burst in salicylic acid-induced stomatal closure in Arabidopsis Reviewed

Md. Atiqur Rahman Khokon, Eiji Okuma, Mohammad Anowar Hossain, Shintaro Munemasa, Misugi Uraji, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

PLANT CELL AND ENVIRONMENT 34 ( 3 ) 434 - 443 2011.3

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL PUBLISHING, INC

Salicylic acid (SA), a ubiquitous phenolic phytohormone, is involved in many plant physiological processes including stomatal movement. We analysed SA-induced stomatal closure, production of reactive oxygen species (ROS) and nitric oxide (NO), cytosolic calcium ion ([Ca2+](cyt)) oscillations and inward-rectifying potassium (K+(in)) channel activity in Arabidopsis. SA-induced stomatal closure was inhibited by pre-treatment with catalase (CAT) and superoxide dismutase (SOD), suggesting the involvement of extracellular ROS. A peroxidase inhibitor, SHAM (salicylhydroxamic acid) completely abolished SA-induced stomatal closure whereas neither an inhibitor of NADPH oxidase (DPI) nor atrbohD atrbohF mutation impairs SA-induced stomatal closures. 3,3'-Diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) stainings demonstrated that SA induced H(2)O(2) and O(2)- production. Guard cell ROS accumulation was significantly increased by SA, but that ROS was suppressed by exogenous CAT, SOD and SHAM. NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) suppressed the SA-induced stomatal closure but did not suppress guard cell ROS accumulation whereas SHAM suppressed SA-induced NO production. SA failed to induce [Ca2+](cyt) oscillations in guard cells whereas K+(in) channel activity was suppressed by SA. These results indicate that SA induces stomatal closure accompanied with extracellular ROS production mediated by SHAM-sensitive peroxidase, intracellular ROS accumulation and K+(in) channel inactivation.

DOI： 10.1111/j.1365-3040.2010.02253.x

The Arabidopsis Calcium-Dependent Protein Kinase, CPK6, Functions as a Positive Regulator of Methyl Jasmonate Signaling in Guard Cells Reviewed

Shintaro Munemasa, Mohammad Anowar Hossain, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

PLANT PHYSIOLOGY 155 ( 1 ) 553 - 561 2011.1

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER SOC PLANT BIOLOGISTS

Previous studies have demonstrated that methyl jasmonate (MeJA) induces stomatal closure dependent on change of cytosolic free calcium concentration in guard cells. However, these molecular mechanisms of intracellular Ca2+ signal perception remain unknown. Calcium-dependent protein kinases (CDPKs) function as Ca2+ signal transducers in various plant physiological processes. It has been reported that four Arabidopsis (Arabidopsis thaliana) CDPKs, CPK3, CPK6, CPK4, and CPK11, are involved in abscisic acid signaling in guard cells. It is also known that there is an interaction between MeJA and abscisic acid signaling in guard cells. In this study, we examined the roles of these CDPKs in MeJA signaling in guard cells using Arabidopsis mutants disrupted in the CDPK genes. Disruption of the CPK6 gene impaired MeJA-induced stomatal closure, but disruption of the other CDPK genes did not. Despite the broad expression pattern of CPK6, we did not find other remarkable MeJA-insensitive phenotypes in the cpk6-1 mutant. The whole-cell patch-clamp analysis revealed that MeJA activation of nonselective Ca2+-permeable cation channels is impaired in the cpk6-1 mutant. Consistent with this result, MeJA-induced transient cytosolic free calcium concentration increments were reduced in the cpk6-1 mutant. MeJA failed to activate slow-type anion channels in the cpk6-1 guard cells. Production of early signal components, reactive oxygen species and nitric oxide, in guard cells was elicited by MeJA in the cpk6-1 mutant as in the wild type. These results provide genetic evidence that CPK6 has a different role from CPK3 and functions as a positive regulator of MeJA signaling in Arabidopsis guard cells.

DOI： 10.1104/pp.110.162750

The Involvement of Intracellular Glutathione in Methyl Jasmonate Signaling in Arabidopsis Guard Cells Reviewed

Nasima Akter, Muhammad Abdus Sobahan, Mohammad Anowar Hossain, Misugi Uraji, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 74 ( 12 ) 2504 - 2506 2010.12

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

We examined the involvement of intracellular glutathione (GSH) in methyl jasmonate (MeJA) signaling. The chlorinal-1 (ch1-1) mutation decreased GSH in guard cells and narrowed the stomata! aperture. GSH monoethyl ester increased intracellular GSH, diminishing this phenotype. GSH did not affect MeJA-induced reactive oxygen species production or cytosolic Ca2+ oscillation, suggesting that GSH modulates MeJA signaling downstream of production and oscillation.

DOI： 10.1271/bbb.100513

Covalent Binding of Tea Catechins to Protein Thiols: The Relationship between Stability and Electrophilic Reactivity Reviewed

Taiki Mori, Takeshi Ishii, Mitsugu Akagawa, Yoshimasa Nakamura, Tsutomu Nakayama

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 74 ( 12 ) 2451 - 2456 2010.12

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

In this study, we investigated the relationship between the stability of catechins and their electrophilic reactivity with proteins. The stability of catechins was evaluated by HPLC analysis. Catechol-type catechins were stable in a neutral buffer, but pyrogallol-type catechins, such as (-)-epigallocatechin gallate (EGCg), were unstable. The electrophilic reactivity of catechins with thiol groups in a model peptide and a protein was confirmed by both mass spectrometry and electrophoresis/blotting with redox-cycling staining. In a comparison of several catechins, pyrogallol-type catechins had higher reactivity with protein thiols than catechol-type catechins. The instability and reactivity of EGCg were enhanced in an alkaline pH buffer. The reactivity of EGCg was reduced by antioxidants due to their ability to prevent EGCg autoxidation. These results indicate that the instability against oxidation of catechins is profoundly related to their electrophilic reactivity. Consequently, the difference in these properties of tea catechins can contribute to the magnitude of their biological activities.

DOI： 10.1271/bbb.100509

Yeast Elicitor-Induced Stomatal Closure and Peroxidase-Mediated ROS Production in Arabidopsis Reviewed

Md. Atiqur Rahman Khokon, Mohammad Anowar Hossain, Shintaro Munemasa, Misugi Uraji, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

PLANT AND CELL PHYSIOLOGY 51 ( 11 ) 1915 - 1921 2010.11

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Yeast elicitor (YEL) induces stomatal closure. We investigated reactive oxygen species (ROS) production, nitric oxide (NO) production and [Ca(2+)](cyt) oscillations to clarify YEL signaling in Arabidopsis guard cells. YEL induced ROS accumulation in guard cells. A peroxidase inhibitor [salicylhydroxamic acid (SHAM)] inhibited the stomatal closure and the ROS accumulation, but neither the atrbohD atrbohF mutation nor an NADPH oxidase inhibitor [diphenylene iodonium chloride (DPI)] had any effect. An NO scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3oxide (cPTIO)] inhibited the YEL-induced stomatal closure and SHAM abolished NO production. YEL-elicited [Ca(2+)] cyt oscillations were inhibited by SHAM but not by the atrbohD atrbohF mutation. These results indicate that YEL induces stomatal closure accompanied by ROS production mediated by peroxidases and NO production.

DOI： 10.1093/pcp/pcq145

Chitosan-Induced Stomatal Closure Accompanied by Peroxidase-Mediated Reactive Oxygen Species Production in Arabidopsis Reviewed

Md Atiqur Rahman Khokon, Misugi Uraji, Shintaro Munemasa, Eiji Okuma, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 74 ( 11 ) 2313 - 2315 2010.11

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

Chitosan induced stomatal closure in wild type-plants and NADPH oxidase knock-out mutants (atrbohD atrbohF), and reactive oxygen species (ROS) production in wild-type guard cells. Closure and production were completely abolished by catalase and a peroxidase inhibitor. These results indicate that chitosan induces ROS production mediated by peroxidase, resulting in stomata! closure.

DOI： 10.1271/bbb.100340

The Effects of Methylglyoxal on Glutathione S-Transferase from Nicotiana tabacum Reviewed

Md Anamul Hoque, Misugi Uraji, Mst Nasrin Akhter Banu, Izumi C. Mori, Yoshimasa Nakamura, Yoshiyuki Murata

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 74 ( 10 ) 2124 - 2126 2010.10

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

Methylglyoxal (MG) is one of the aldehydes that accumulate in plants under environmental stress. Glutathione S-transferases (GSTs) play important roles, including detoxification, in the stress tolerance systems of plants. To determine the effects of MG, we characterized recombinant GST. MG decreased GST activity and thiol contents with increasing Km. GST can serve as a target of MG modification, which is suppressed by application of reduced glutathione.

DOI： 10.1271/bbb.100393

Cytosolic Alkalization and Cytosolic Calcium Oscillation in Arabidopsis Guard Cells Response to ABA and MeJA Reviewed

Mohammad Mahbub Islam, Mohammad Anowar Hossain, Rayhanur Jannat, Shintaro Munemasa, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

PLANT AND CELL PHYSIOLOGY 51 ( 10 ) 1721 - 1730 2010.10

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Abscisic acid (ABA)- and methyl jasmonate (MeJA)-induced stomatal closure are accompanied by cytosolic alkalization in guard cells. However, it remains to be clarified how the alkalization functions in not only ABA signaling but also MeJA. We investigated cytosolic alkalization in guard cells during ABA-, MeJA- and Ca(2+)-induced stomatal closure of wild type, abi1-1, abi2-1, ost1-2 and coi1 using a pH-sensitive fluorescent dye, BCECF-AM. ABA induced cytosolic alkalization in guard cells of wild-type and coi1 but not in ost1-2 guard cells whereas MeJA elicited cytosolic alkalization in wild-type and ost1-2 guard cells but not in coi1. Neither ABA nor MeJA induced cytosolic alkalization in abi1-1 and abi2-1 guard cells. Exogenous Ca(2+) induced stomatal closure accompanied by cytosolic alkalization in guard cells of wild-type, abi1-1, abi2-1, ost1-2 and coi1 plants. An agent to acidify cytosol, butyrate, suppressed Ca(2+) -induced cytosolic alkalization and ABA-, MeJA- and Ca(2+) -induced cytosolic Ca(2+) oscillation in wild-type guard cells to prevent stomatal closure. These results indicate that cytosolic alkalization and cytosolic Ca(2+) oscillation coordinately function in ABA and MeJA signaling in Arabidopsis guard cells.

DOI： 10.1093/pcp/pcq131

Proline and Glycinebetaine Ameliorated NaCl Stress via Scavenging of Hydrogen Peroxide and Methylglyoxal but Not Superoxide or Nitric Oxide in Tobacco Cultured Cells Reviewed

Mst Nasrin Akhter Banu, Md Anamul Hoque, Megumi Watanabe-Sugimoto, Mohammad Muzahidul Islam, Misugi Uraji, Ken Matsuoka, Yoshimasa Nakamura, Yoshiyuki Murata

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 74 ( 10 ) 2043 - 2049 2010.10

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

Efficient detoxification of the reactive oxygen species, nitric oxide (NO) and methylglyoxal (MG), provides protection against NaCl-induced damage in plants. To elucidate the protective mechanisms of proline and glycinebetaine (betaine) against NaCl stress, intracellular levels of hydrogen peroxide (H2O2), superoxide (O-2(-)), NO, and MG were investigated in tobacco Bright Yellow-2 cells. The Levels of H2O2, O-2(-), NO and MG were higher in the short-term and long-term NaCl-stressed cells than in the non-stressed cells, whereas the O-2(-) level was higher in the long-term stressed cells. Exogenous proline and betaine decreased the H2O2 level in both the short-term and the long-term NaCl-stressed cells and the MG level in the long-term NaCl-stressed cells, but did not change the O-2(-) or NO levels. Under salt stress, both proline and betaine increased the transcription levels of glutathione peroxidase, which can contribute to the reduction of H2O2. In conclusion, proline and betaine mitigated salt stress via reduction of H2O2 accumulation during short-term incubation and via reduction of the accumulation of H2O2 and MG during long-term incubation.

DOI： 10.1271/bbb.100334

Artificial Food Colorants Inhibit Superoxide Production in Differentiated HL-60 Cells Reviewed

Hang Qi, Machiko Kawagishi, Motoko Yoshimoto, Hiroshi Takano, Beiwei Zhu, Yasuaki Shimoishi, Mikiro Tada, Yoshiyuki Murata, Yoshimasa Nakamura

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 74 ( 8 ) 1725 - 1728 2010.8

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

We tested synthetic food colorants for their antioxidative potential by the in vitro superoxide generation assay in differentiated HL-60 cells in response to phorbol ester. Among the 12 colorants tested, such fluorescein-type red colorants as rose bengal showed potent inhibitory activity without any cytotoxicity under dark conditions. The intracellular accumulation and superoxide anion scavenging effect of rose bengal were at least partly involved in the inhibitory activity.

DOI： 10.1271/bbb.100314

Roles of AtTPC1, Vacuolar Two Pore Channel 1, in Arabidopsis Stomatal Closure Reviewed

Mohammad Mahbub Islam, Shintaro Munemasa, Mohammad Anowar Hossain, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

PLANT AND CELL PHYSIOLOGY 51 ( 2 ) 302 - 311 2010.2

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Abscisic acid (ABA) induces production of reactive oxygen species (ROS) and nitric oxide (NO), elevation of the cytosolic free calcium ion concentration ([Ca(2+)](cyt)) and cytosolic pH (pH(cyt)), and activation of S-type anion channels in guard cells, causing stomatal closure. To investigate whether Arabidopsis Two pore channel 1 (AtTPC1) that encodes the slow vacuolar (SV) channel is involved in stomatal closure, we examined stomatal movements and mobilization of second messengers in the attpc1-2 loss-of-function mutant in response to ABA, methyl jasmonate (MeJA) and Ca(2+). Both ABA and MeJA elicited production of ROS and NO, [Ca(2+)] cyt oscillations, cytosolic alkalization and activation of S-type anion channel currents to lead to stomatal closure in the attpc1-2 mutant as well as the wild type. Unlike the wild type, in the attpc1-2 mutant exogenous Ca(2+) neither induced stomatal closure nor activated plasma membrane S-type anion channel currents despite [Ca(2+)] cyt elevation. These results indicate that AtTPC1 functions in response to external Ca(2+) but not to ABA and MeJA in Arabidopsis guard cells and suggest that AtTPC1 could be involved in priming of plasma membrane S-type anion channels by external Ca(2+) in Arabidopsis guard cells.

DOI： 10.1093/pcp/pcq001

A fraction of unripe kiwi fruit extract regulates adipocyte differentiation and function in 3T3-L1 cells Reviewed

Daigo Abe, Takeshi Saito, Yasutaka Kubo, Yoshimasa Nakamura, Keizo Sekiya

BIOFACTORS 36 ( 1 ) 52 - 59 2010.1

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

Adipocyte dysfunction is strongly associated with the development of insulin resistance and diabetes, and regulation of adipogenesis is important in prevention of diabetes. We prepared a 100% methanol fraction of methanolic extract from unripe kiwi fruit (Actinidia deliciosa), designated KMF (kiwi fruit methanol fraction) When applied to 3T3-L1 preadipocyte cells, KMF promoted adipocyte differentiation, increased glycerol-3-phosphate dehydrogenase (GPDH) activity, and increased triglyceride (TG) content. KMF markedly increased mRNA expression of peroxisome proliferator-activated receptor gamma (PPAR gamma)-the master adipogenic transcription factor-and its target genes. Moreover, KMF increased mRNA expression and protein secretion of adiponectin, whereas mRNA expression and secretion of monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) were decreased. Compared with troglitazone, KMF decreased the production of reactive oxygen species (ROS) and nuclear factor-kappaB (NF kappa B) activation. Glucose uptake was stimulated by KMF in differentiated 3T3-L1 adipocytes. Taken together, these results indicate that KMF may exert beneficial effects against diabetes via its ability to regulate adipocyte differentiation and function. (C) 2010 International Union of Biochemistry and Molecular Biology, Inc.

DOI： 10.1002/biof.70

Identification and Characterization of Sesaminol Metabolites in the Liver Reviewed

Mika Mochizuki, Yoshikazu Tsuchie, Yoshimasa Nakamura, Toshihiko Osawa

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 57 ( 21 ) 10429 - 10434 2009.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Sesame seeds contain a number of antioxidants, such as sesamin, sesamolin, sesaminol, and sesaminol glucosides. Sesaminol triglucoside was reported to suppress oxidative stress in vivo, but little is known about the metabolism of this potentially important compound. Therefore, we have studied the metabolites of sesaminol formed in the rat liver S9 mix and excreted in the liver of rats ingesting sesaminol triglucoside for 24 h. Nuclear magnetic resonance (NMR) and mass spectrometry (MS) analyses revealed that rat liver S9 mix transformed the sesaminol into a catechol-type metabolite. On the basis of a previous study with sesame lignans by culturing the genus Aspergillus, sesaminol-6-catechol was identified as the major metabolite. Sesaminol was further converted into 5 ''-methylated sesaminol-6-catechol by catechol-O-methyltransferase. Moreover, we successfully detected these metabolites in the liver of rats ingesting the sesaminol triglucoside.

DOI： 10.1021/jf901939m

Proline and Glycinebetaine Confer Cadmium Tolerance on Tobacco Bright Yellow-2 Cells by Increasing Ascorbate-Glutathione Cycle Enzyme Activities Reviewed

Mohammad Muzahidul Islam, Md. Anamul Hoque, Eiji Okuma, Rayhanur Jannat, Mst. Nasrin Akhter Banu, Md. Sarwar Jahan, Yoshimasa Nakamura, Yoshiyuki Murata

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 73 ( 10 ) 2320 - 2323 2009.10

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

Cadmium (Cd) stress significantly decreased membrane integrity and impaired the ascorbate (ASC)-glutathione (GSH) cycle in tobacco Bright Yellow-2 cells. Exogenous application of proline and glycinebetaine (betaine) significantly restored the membrane integrity and increased the activities of ASC-GSH cycle enzymes under Cd stress without maintenance of the rich ASC or GSH pools. Moreover, proline offered more efficient protection against Cd stress than betaine.

DOI： 10.1271/bbb.90305

Catechol Type Polyphenol Is a Potential Modifier of Protein Sulfhydryls: Development and Application of a New Probe for Understanding the Dietary Polyphenol Actions Reviewed

Takeshi Ishii, Miki Ishikawa, Noriyuki Miyoshi, Mayuko Yasunaga, Mitsugu Akagawa, Koji Uchida, Yoshimasa Nakamura

CHEMICAL RESEARCH IN TOXICOLOGY 22 ( 10 ) 1689 - 1698 2009.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

The oxidation of dietary polyphenols with a catechol structure leads to the formation of an o-quinone structure, which rapidly reacts with sulfhydryls such as glutathione and protein cysteine residues. This modification may be important for understanding the redox regulation of cell functions by polyphenols. In this study, to investigate the catechol modification of protein sulthydryls, we used 3,4-dihydroxyphenyl acetic acid (DPA) as a model catechol compound and developed a new probe to directly detect protein modification by catechol type polyphenols using a biotinylated DPA (Bio-DPA). The oxidation-dependent electrophilic reactivity of DPA with peptide sulfhydryls was confirmed by both mass spectrometry and nuclear magnetic resonance spectroscopy. When RL34 cells were treated with Bio-DPA, the significant incorporation of Bio-DPA into a 40 kDa protein was observed by Western blot analysis. The band was identified by mass spectrometry as the cytoskeletal protein, beta-actin. This identification was confirmed by the pull-down assay with anti-beta-actin antibody. To examine the reactivity of the catechol type polyphenols, such as flavonoids, to endogenous beta-actin, RL34 cells were coexposed to Bio-DPA and the flavonoids quercetin, (-)-epicatechin, and (-)-epicatechin gallate. Upon exposure of the cells to Bio-DPA in the presence of the flavonoids, we observed a significant decrease in the DPA-modified beta-actin. These results indicate that beta-actin is one of the major targets of protein modification by catechol type polyphenols and that Bio-DPA is an useful probe for understanding the redox regulation by dietary polyphenols. Furthermore, Keap1, a scaffold protein to the actin cytoskeleton controlling cytoprotective enzyme genes, was also identified as another plausible target of the catechol type polyphenols by oxidative modification of the intracellular sulfhydryls. These results provide an alternative approach to understand that catechol type polyphenol is a potential modifier of redox-dependent cellular events through sulfhydryl modification.

DOI： 10.1021/tx900148k

Exogenous Proline and Glycinebetaine Suppress Apoplastic Flow to Reduce Na+ Uptake in Rice Seedlings Reviewed

Muhammad Abdus Sobahan, Carlos Raul Arias, Eiji Okuma, Yasuaki Shimoishi, Yoshimasa Nakamura, Yoshihiko Hirai, Izumi C. Mori, Yoshiyuki Murata

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 73 ( 9 ) 2037 - 2042 2009.9

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

The application of exogenous proline and glycinebetaine (betaine) confers salt tolerance on plants under salt stress. The effects of exogenous proline and betaine on apoplastic How in rice plants under saline conditions were investigated using trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), an apoplastic tracer. Rice plants took up more PTS under light conditions than under dark conditions. Salt stress increased PTS uptake and Na+ content of rice leaves, but did not affect K+ content, resulting in a lower K+/Na+ ratio. Addition of proline or betaine to the saline medium suppressed Na+-induced PTS uptake and Na+ accumulation, while the K+ content was slightly increased, which led to a high K+/Na+ ratio under saline conditions. These results suggest that exogenous proline and betaine suppressed Na+-enhanced apoplastic flow to reduce Na+ uptake in rice plants.

DOI： 10.1271/bbb.90244

Myrosinases, TGG1 and TGG2, Redundantly Function in ABA and MeJA Signaling in Arabidopsis Guard Cells Reviewed

Mohammad Mahbub Islam, Chiharu Tani, Megumi Watanabe-Sugimoto, Misugi Uraji, Md. Sarwar Jahan, Choji Masuda, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

PLANT AND CELL PHYSIOLOGY 50 ( 6 ) 1171 - 1175 2009.6

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Thioglucoside glucohydrolase (myrosinase), TGG1, is a strikingly abundant protein in Arabidopsis guard cells. We investigated responses of tgg1-3, tgg2-1 and tgg1-3 tgg2-1 mutants to abscisic acid (ABA) and methyl jasmonate (MeJA) to clarify whether two myrosinases, TGG1 and TGG2, function during stomatal closure. ABA, MeJA and H2O2 induced stomatal closure in wild type, tgg1-3 and tgg2-1, but failed to induce stomatal closure in tgg1-3 tgg2-1. All mutants and wild type showed Ca-2-induced stomatal closure and ABA-induced reactive oxygen species (ROS)production. A model is discussed in which two myrosinases redundantly function downstream of ROS production and upstream of cytosolic Ca-2 elevation in ABA and MeJA signaling in guard cells.

DOI： 10.1093/pcp/pcp066

Induction of Apoptosis by beta-Carotene and Dimethyl Tetrasulfide Assisted by UVA Irradiation in HL-60 Cells Reviewed

Gongliang Zhang, Haitao Wu, Beiwei Zhu, Yasuaki Shimoishi, Yoshimasa Nakamura, Yoshiyuki Murata

BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY 73 ( 5 ) 1014 - 1020 2009.5

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

Cellular phototoxicity induced by UVA irradiation and its potential application to therapy has been reported. In the present study, the induction of apoptosis induced by beta-carotene and dimethyl tetrasulfide (Me2S4) assisted by UVA irradiation in HL-60 cells was assessed. beta-carotene assisted by UVA significantly decreased the cell viability and induced DNA fragmentation in HL-60 cells. Me2S4 combined with beta-carotene and assisted by UVA significantly inhibited the cell viability, and enhanced the caspase-3 activity which was completely inhibited by N-acety-L-cysteine. beta-carotene was significantly degraded by UVA, but this was not accellerated by Me2S4 in a cell culture system. The photodegradation products of beta-carotene prepared by UVA irradiation regardless of the addition of Me2S4 showed lower cytotoxicity than beta-carotene itself in HL-60 cells. These results suggest that the ROS- and caspase-3-dependent apoptosis induced by beta-carotene and Me2S4 assisted by UVA was due to a synergistic action rather than to the sole effect of the photodegradation products of beta-carotene in HL-60 cells.

DOI： 10.1271/bbb.80794

(-)-Epigallocatechin-3-gallate induces up-regulation of Th1 and Th2 cytokine genes in Jurkat T cells Reviewed

Haitao Wu, Beiwei Zhu, Yasuaki Shimoishi, Yoshiyuki Murata, Yoshimasa Nakamura

ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS 483 ( 1 ) 99 - 105 2009.3

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE INC

In the present Study, we found that (-)-epigallocatechin-3-gallate (EGCG) significantly up-regulated the mRNA expression of the Th1/Th2 cytokines including IL-2, IFN-gamma, IL-5 and IL-13 in Jurkat T cells. The EGCG-induced mRNA Up-regulation of IL-2 and IL-5 was predominantly affected by the extracellular signal-regulated protein kinase (ERK) signalling, whereas IL-13 gene expression, the most responsive to the EGCG treatment, was dependent on neither ERK nor c-jun NH(2)-terminal kinase (JNK) signalling. IFN-gamma gene expression was partially mitigated by both inhibitors of the ERK and JNK pathways. Furthermore, catalase significantly attenuated the intracellular peroxide production, phosphorylation of ERK and JNK, and all cytokine gene expressions induced by EGCG. In addition, physiologically relevant concentrations of both EGCG and H(2)O(2)-induced up-regulation of IL-5 gene expression. Our findings provide biological evidence that EGCG induces Th1/Th2 cytokine mRNA expression via H(2)O(2). production followed by activation of ERK or JNK in Jurkat T cells. (C) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.abb.2008.12.010

Exogenous proline and glycinebetaine increase antioxidant enzyme activities and confer tolerance to cadmium stress in cultured tobacco cells Reviewed

Mohammad Muzahidul Islam, Anamul Hoque, Eiji Okuma, Mst. Nasrin, Akhter Banu, Yasuaki Shimoishi, Yoshimasa Nakamura, Yoshiyuki Murata

JOURNAL OF PLANT PHYSIOLOGY 166 ( 15 ) 1587 - 1597 2009

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER GMBH, URBAN & FISCHER VERLAG

Environmental stress, including heavy metal stress, can cause oxidative damage to plants. Up-regulation of the antioxidant defense system induced by proline and glycinebetaine (betaine) alleviates the damaging effects of oxidative stress in plants. Here, we investigated the protective effects of exogenously applied proline and betaine on growth, accumulation of proline and betaine, lipid peroxidation and activity of antioxidant enzymes in cultured tobacco Bright Yellow-2 (BY-2) cells exposed to cadmium (Cd) stress. Cadmium stress (at 100 mu M Cd) caused a significant inhibition of the growth of BY-2 cells, and both proline and betaine significantly mitigated this inhibition. In addition, the mitigating effect of proline was more pronounced than that of betaine. Cadmium stress leads to an accumulation of Cd and endogenous proline in cultured cells, increased lipid peroxidation and peroxidase (POX) activity, and decreased activity of superoxide dismutase (SOD) and catalase (CAT). Exogenous application of proline resulted in a decrease in lipid peroxidation and an increase in SOD and CAT activities without reducing Cd contents under Cd stress, while application of betaine resulted in a decrease in lipid peroxidation and an increase in CAT activity with reducing Cd accumulation. Furthermore, exogenous proline and betaine intensified the accumulation of proline and betaine in Cd-stressed BY-2 cells, respectively. The present study suggests that proline and betaine confer tolerance to Cd stress in tobacco BY-2 cells by different mechanisms. (C) 2009 Elsevier GrnbH. All rights reserved.

DOI： 10.1016/j.jplph.2009.04.002

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