Faculty Profiles - MURATA Yoshiyuki

Papers - MURATA Yoshiyuki

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Involvement of OST1 Protein Kinase and PYR/PYL/RCAR Receptors in Methyl Jasmonate-Induced Stomatal Closure in Arabidopsis Guard Cells

Yin Ye, Adachi Yuji, Nakamura Yoshimasa, Munemasa Shintaro, Mori Izumi C., Murata Yoshiyuki

Plant and Cell Physiology 57 ( 8 ) 1779 - 1990 2016.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society of Plant Physiologists

Methyl jasmonate (MeJA) induces stomatal closure. It has been shown that stomata of many ABA-insensitive mutants are also insensitive to MeJA, and a low amount of ABA is a prerequisite for the MeJA response. However, the molecular mechanisms of the interaction between ABA and MeJA signaling remain to be elucidated. Here we studied the interplay of signaling of the two hormones in guard cells using the quadruple ABA receptor mutant pyr1 pyl1 pyl2 pyl4 and ABA-activated protein kinase mutants ost1-2 and srk2e. In the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, nitric oxide (NO) production, cytosolic alkalization and plasma membrane Ca(2+)-permeable current (ICa) activation were not impaired. At the same time, the inactivation of the inward-rectifying K(+) current was impaired. In contrast to the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, NO production and cytosolic alkalization were impaired in ost1-2 and srk2e as well as in aba2-2, the ABA-deficient mutant. The activation of ICa was also impaired in srk2e. Collectively, these results indicated that OST1 was essential for MeJA-induced stomatal closure, while PYR1, PYL1, PYL2 and PYL4 ABA receptors were not sufficient factors. MeJA did not appear to activate OST1 kinase activity. This implies that OST1 mediates MeJA signaling through an undetectable level of activity or a non-enzymatic action. MeJA induced the expression of an ABA synthesis gene, NCED3, and increased ABA contents only modestly. Taken together with previous reports, this study suggests that MeJA signaling in guard cells is primed by ABA and is not brought about through the pathway mediated by PYR1, PYL1 PYL2 and PYL4.

DOI： 10.1093/pcp/pcw102

GOLDEN 2-LIKE transcription factors for chloroplast development affect ozone tolerance through the regulation of stomatal movement Reviewed International journal

Yukari Nagatoshi, Nobutaka Mitsuda, Maki Hayashi, Shin-ichiro Inoue, Eiji Okuma, Akihiro Kubo, Yoshiyuki Murata, Mitsunori Seo, Hikaru Saji, Toshinori Kinoshita, Masaru Ohme-Takagi

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 113 ( 15 ) 4218 - 4223 2016.4

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL ACAD SCIENCES

Stomatal movements regulate gas exchange, thus directly affecting the efficiency of photosynthesis and the sensitivity of plants to air pollutants such as ozone. The GARP family transcription factors GOLDEN 2-LIKE1 (GLK1) and GLK2 have known functions in chloroplast development. Here, we show that Arabidopsis thaliana (A. thaliana) plants expressing the chimeric repressors for GLK1 and -2 (GLK1/2-SRDX) exhibited a closed-stomata phenotype and strong tolerance to ozone. By contrast, plants that overexpress GLK1/2 exhibited an open-stomata phenotype and higher sensitivity to ozone. The plants expressing GLK1-SRDX had reduced expression of the genes for inwardly rectifying K+ (K-in(+)) channels and reduced K-in(+) channel activity. Abscisic acid treatment did not affect the stomatal phenotype of 35S:GLK1/2-SRDX plants or the transcriptional activity for K-in(+) channel gene, indicating that GLK1/2 act independently of abscisic acid signaling. Our results indicate that GLK1/2 positively regulate the expression of genes for K-in(+) channels and promote stomatal opening. Because the chimeric GLK1-SRDX repressor driven by a guard cell-specific promoter induced a closed-stomata phenotype without affecting chloroplast development in mesophyll cells, modulating GLK1/2 activity may provide an effective tool to control stomatal movements and thus to confer resistance to air pollutants.

DOI： 10.1073/pnas.1513093113

Effects of Postharvest Near Infrared Light Exposure on Transpiration, Stomatal Aperture, and Appearance in Several Vegetables Reviewed

Ayako Kozuki, Yutaka. Ishida, Kazumasa Kakibuchi, Naoki Sakurai, Yoshiyuki Murata, Ryohei Nakano, Yasutaka Kubo

Horticultural Research (Japan) 15 ( 2 ) 197 - 206 2016.4

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Horticultural Science

The effects of postharvest short-term irradiation with near infrared (NIR, 850 nm at 100 mmol・m−2・s−1 for 5 min) on weight loss, stomata apertures, and appearance quality were investigated in three leaf vegetables. Leaf lettuce, spinach, and spinach mustard (Komatsuna) at commercial maturity were exposed to NIR for 5 min once before storage or every day, packaged in perforated or non-perforated polyethylene bags, and then stored at 10°C under dark conditions. In all three leaf vegetables under both storage conditions, packaged in perforated and non-perforated polyethylene bags, weight loss rates and stomata aperture after 3 days of storage were reduced in NIR-exposed crops, compared with non-treated controls, resulting in a better appearance quality. The beneficial effects were more distinct in everyday treated than in single treated crops. When leaf vegetables packaged in perforated polyethylene bags were treated with NIR and stored at 10°C under dark or light conditions, weight loss rates were reduced and the appearance quality was better under both conditions, compared with non-treated controls. The beneficial effects were more marked in everyday treated than in single treated crops. The greatest benefits were observed in spinach. These results suggest that postharvest short-term NIR radiation has a promising potential as an additional quality control technique during the storage and transportation of leaf vegetables.

DOI： 10.2503/hrj.15.197

OsHKT1;4-mediated Na⁺ transport in stems contributes to Na⁺ exclusion from leaf blades of rice at the reproductive growth stage upon salt stress International journal

Kei Suzuki, Naoki Yamaji, Alex Costa, Eiji Okuma, Natsuko I. Kobayashi, Tatsuhiko Kashiwagi, Maki Katsuhara, Cun Wang, Keitaro Tanoi, Yoshiyuki Murata, Julian I. Schroeder, Jian Feng Ma, Tomoaki Horie

BMC Plant Biology 16 ( 1 ) 22 - 22 2016.1

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

Background: Na+ exclusion from leaf blades is one of the key mechanisms for glycophytes to cope with salinity stress. Certain class I transporters of the high-affinity K+ transporter (HKT) family have been demonstrated to mediate leaf blade-Na+ exclusion upon salinity stress via Na+-selective transport. Multiple HKT1 transporters are known to function in rice (Oryza sativa). However, the ion transport function of OsHKT1;4 and its contribution to the Na+ exclusion mechanism in rice remain to be elucidated. Results: Here, we report results of the functional characterization of the OsHKT1;4 transporter in rice. OsHKT1;4 mediated robust Na+ transport in Saccharomyces cerevisiae and Xenopus laevis oocytes. Electrophysiological experiments demonstrated that OsHKT1;4 shows strong Na+ selectivity among cations tested, including Li+, Na+, K+, Rb+, Cs+, and NH4+, in oocytes. A chimeric protein, EGFP-OsHKT1;4, was found to be functional in oocytes and targeted to the plasma membrane of rice protoplasts. The level of OsHKT1;4 transcripts was prominent in leaf sheaths throughout the growth stages. Unexpectedly however, we demonstrate here accumulation of OsHKT1;4 transcripts in the stem including internode II and peduncle in the reproductive growth stage. Moreover, phenotypic analysis of OsHKT1;4 RNAi plants in the vegetative growth stage revealed no profound influence on the growth and ion accumulation in comparison with WT plants upon salinity stress. However, imposition of salinity stress on the RNAi plants in the reproductive growth stage caused significant Na+ overaccumulation in aerial organs, in particular, leaf blades and sheaths. In addition, 22Na+ tracer experiments using peduncles of RNAi and WT plants suggested xylem Na+ unloading by OsHKT1;4. Conclusions: Taken together, our results indicate a newly recognized function of OsHKT1;4 in Na+ exclusion in stems together with leaf sheaths, thus excluding Na+ from leaf blades of a japonica rice cultivar in the reproductive growth stage, but the contribution is low when the plants are in the vegetative growth stage.

DOI： 10.1186/s12870-016-0709-4

Regulation of stomatal responses to abiotic and biotic stresses by redox state

Murata, Y., Munemasa, S., Mori, I.C.

Redox State as a Central Regulator of Plant-Cell Stress Responses 2016

Microbe Associated Molecular Pattern Signaling in Guard Cells. International journal

Wenxiu Ye, Yoshiyuki Murata

Frontiers in plant science 7 583 - 583 2016

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

Stomata, formed by pairs of guard cells in the epidermis of terrestrial plants, regulate gas exchange, thus playing a critical role in plant growth and stress responses. As natural openings, stomata are exploited by microbes as an entry route. Recent studies reveal that plants close stomata upon guard cell perception of molecular signatures from microbes, microbe associated molecular patterns (MAMPs), to prevent microbe invasion. The perception of MAMPs induces signal transduction including recruitment of second messengers, such as Ca(2+) and H2O2, phosphorylation events, and change of transporter activity, leading to stomatal movement. In the present review, we summarize recent findings in signaling underlying MAMP-induced stomatal movement by comparing with other signalings.

DOI： 10.3389/fpls.2016.00583

Effect of postharvest short-term radiation of near infrared light on transpiration of lettuce leaf Reviewed

Ayako Kozuki, Yutaka Ishida, Kazumasa Kakibuchi, Toshihiro Mishima, Naoki Sakurai, Yoshiyuki Murata, Ryohei Nakano, Koichiro Ushijima, Yasutaka Kubo

POSTHARVEST BIOLOGY AND TECHNOLOGY 108 78 - 85 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We investigated the physiological effects of short-term postharvest near infrared (NIR) radiation on relative transpiration rates, stomatal apertures, and reactive oxygen species (ROS) levels in guard cells on excised young lettuce leaves and on transpiration of leaf lettuce at commercial maturity. When the young leaves were radiated by NIR of wavelengths longer than 850 nm at 100 mu mol m(-2) s(-1) for short duration (10-60) min, relative transpiration rates during subsequent storage were reduced, but not by visible light radiation and by longer radiation (180 min) of NIR. The reduction in transpiration rates by the short-term NIR radiation was greater at 10 degrees C than at 25 degrees C under both dark and light conditions during subsequent storage. The short-term NIR radiation enhanced stomatal closure and ROS accumulation in guard cells of young lettuce leaves. These results indicate that the suppression of transpiration by short-term NIR radiation is likely to be mediated through stomatal closure due to NIR-induced ROS accumulation. The reduction of transpiration by short-term NIR radiation was obtained not only in excised young leaves but also in leaf lettuce at commercial maturity, resulting in keeping freshness. The short-term NIR radiation could be an additional means to extend shelf life of leaf vegetables. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.postharvbio.2015.05.010

Two guard cell mitogen-activated protein kinases, MPK9 and MPK12, function in methyl jasmonate-induced stomatal closure in Arabidopsis thaliana Reviewed

Md. A. R. Khokon, M. A. Salam, F. Jammes, W. Ye, M. A. Hossain, M. Uraji, Y. Nakamura, I. C. Mori, J. M. Kwak, Y. Murata

PLANT BIOLOGY 17 ( 5 ) 946 - 952 2015.9

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

Methyl jasmonate (MeJA) and abscisic acid (ABA) signalling cascades share several signalling components in guard cells. We previously showed that two guard cell-preferential mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signalling in Arabidopsis thaliana. In this study, we examined whether these two MAP kinases function in MeJA signalling using genetic mutants for MPK9 and MPK12 combined with a pharmacological approach. MeJA induced stomatal closure in mpk9-1 and mpk12-1 single mutants as well as wild-type plants, but not in mpk9-1 mpk12-1 double mutants. Consistently, the MAPKK inhibitor PD98059 inhibited the MeJA-induced stomatal closure in wild-type plants. MeJA elicited reactive oxygen species (ROS) production and cytosolic alkalisation in guard cells of the mpk9-1, mpk12-1 and mpk9-1 mpk12-1 mutants, as well in wild-type plants. Furthermore, MeJA triggered elevation of cytosolic Ca2+ concentration ([Ca2+](cyt)) in the mpk9-1 mpk12-1 double mutant as well as wild-type plants. Activation of S-type anion channels by MeJA was impaired in mpk9-1 mpk12-1. Together, these results indicate that MPK9 and MPK12 function upstream of S-type anion channel activation and downstream of ROS production, cytosolic alkalisation and [Ca2+](cyt) elevation in guard cell MeJA signalling, suggesting that MPK9 and MPK12 are key regulators mediating both ABA and MeJA signalling in guard cells.

DOI： 10.1111/plb.12321

Open Stomata 1 Kinase is Essential for Yeast Elicitor-Induced Stomatal Closure in Arabidopsis

Wenxiu Ye, Yuji Adachi, Shintaro Munemasa, Yoshimasa Nakamura, Izumi C. Mori, Yoshiyuki Murata

Plant and Cell Physiology 56 ( 6 ) 1239 - 1248 2015.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Oxford University Press (OUP)

We recently demonstrated that yeast elicitor (YEL)-induced stomatal closure requires a Ca(2+)-dependent kinase, CPK6. A Ca(2+)-independent kinase, Open Stomata 1 (OST1), is involved in stomatal closure induced by various stimuli including ABA. In the present study, we investigated the role of OST1 in YEL-induced stomatal closure in Arabidopsis using a knock-out mutant, ost1-3, and a kinase-deficient mutant, ost1-2. YEL did not induce stomatal closure or activation of guard cell S-type anion channels in the ost1 mutants unlike in wild-type plants. However, YEL did not increase OST1 kinase activity in wild-type guard cells. The YEL-induced stomatal closure and activation of S-type anion channels were also impaired in a gain-of-function mutant of a clade A type 2C protein phosphatase (ABA INSENSITIVE 1), abi1-1C. In the ost1 mutants like in the wild type, YEL induced H2O2 accumulation, activation of non-selective Ca(2+)-permeable cation (ICa) channels and transient elevations in cytosolic free Ca(2+) concentration ([Ca(2+)]cyt) in guard cells. These results suggest that OST1 kinase is essential for stomatal closure and activation of S-type anion channels induced by YEL and that OST1 is not involved in H2O2 accumulation, ICa channel activation or [Ca(2+)]cyt elevations in guard cells induced by YEL.

DOI： 10.1093/pcp/pcv051

Inhibition by acrolein of light-induced stomatal opening through inhibition of inward-rectifying potassium channels in Arabidopsis thaliana International journal

Md Moshiul Islam, Wenxiu Ye, Daiki Matsushima, Md Atiqur Rahman Khokon, Shintaro Munemasa, Yoshimasa Nakamura, Yoshiyuki Murata

Bioscience, Biotechnology, and Biochemistry 79 ( 1 ) 59 - 62 2015.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Oxford University Press (OUP)

<title>Abstract</title>
Acrolein is a reactive α,β-unsaturated aldehyde derived from lipid peroxides, which are produced in plants under a variety of stress. We investigated effects of acrolein on light-induced stomatal opening using Arabidopsis thaliana. Acrolein inhibited light-induced stomatal opening in a dose-dependent manner. Acrolein at 100 μM inhibited plasma membrane inward-rectifying potassium (Kin) channels in guard cells. Acrolein at 100 μM inhibited Kin channel KAT1 expressed in a heterologous system using Xenopus leaves oocytes. These results suggest that acrolein inhibits light-induced stomatal opening through inhibition of Kin channels in guard cells.

DOI： 10.1080/09168451.2014.951028

Diverse Stomatal Signaling and the Signal Integration Mechanism International journal

Yoshiyuki Murata, Izumi C. Mori, Shintaro Munemasa

ANNUAL REVIEW OF PLANT BIOLOGY, VOL 66 66 369 - 392 2015

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

Guard cells perceive a variety of chemicals produced metabolically in response to abiotic and biotic stresses, integrate the signals into reactive oxygen species and calcium signatures, and convert these signatures into stomatal movements by regulating turgor pressure. Guard cell behaviors in response to such complex signals are critical for plant growth and sustenance in stressful, ever-changing environments. The key open question is how guard cells achieve the signal integration to optimize stomatal aperture. Abscisic acid is responsible for stomatal closure in plants in response to drought, and its signal transduction has been well studied. Other plant hormones and low-molecular-weight compounds function as inducers of stomatal closure and mediators of signaling in guard cells. In this review, we summarize recent advances in research on the diverse stomatal signaling pathways, with specific emphasis on signal integration and signal interaction in guard cell movement.

DOI： 10.1146/annurev-arplant-043014-114707

Allyl isothiocyanate induces stomatal closure in Vicia faba. International journal

Muhammad Abdus Sobahan, Nasima Akter, Eiji Okuma, Misugi Uraji, Wenxiu Ye, Izumi C Mori, Yoshimasa Nakamura, Yoshiyuki Murata

Bioscience, biotechnology, and biochemistry 79 ( 10 ) 1737 - 42 2015

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

Isothiocyanates are enzymatically produced from glucosinolates in plants, and allyl isothiocyanate (AITC) induces stomatal closure in Arabidopsis thaliana. In this study, we investigated stomatal responses to AITC in Vicia faba. AITC-induced stomatal closure accompanied by reactive oxygen species (ROS) and NO production, cytosolic alkalization and glutathione (GSH) depletion in V. faba. GSH monoethyl ester induced stomatal reopening and suppressed AITC-induced GSH depletion in guard cells. Exogenous catalase and a peroxidase inhibitor, salicylhydroxamic acid, inhibited AITC-induced stomatal closure, unlike an NAD(P)H oxidase inhibitor, diphenylene iodonium chloride. The peroxidase inhibitor also abolished the AITC-induced ROS production, NO production, and cytosolic alkalization. AITC-induced stomatal closure was suppressed by an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and an agent to acidify cytosol, butyrate. These results indicate that AITC-induced stomatal closure in V. faba as well as in A. thaliana and suggest that AITC signaling in guard cells is conserved in both plants.

DOI： 10.1080/09168451.2015.1045827

Benzyl isothiocyanate inhibits IL-13 expression in human basophilic KU812 cells. International journal

Yue Tang, Naomi Abe, Motoko Yoshimoto, Beiwei Zhu, Yoshiyuki Murata, Yoshimasa Nakamura

Bioscience, biotechnology, and biochemistry 79 ( 1 ) 159 - 63 2015

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

An allergen-stimulating cytokine, interleukin-13 (IL-13), plays a significant role in allergic inflammation. Benzyl isothiocyanate (BITC), derived from several cruciferous vegetables, significantly suppressed the IL-13 expression in the calcium ionophore-stimulated human basophilic KU812 cells. Down-regulation of phosphorylated mitogen-activated protein kinases as well as nuclear transcriptional factors might be involved in the underlying mechanism.

DOI： 10.1080/09168451.2014.963503

Cyclic adenosine 5 '-diphosphoribose (cADPR) cyclic guanosine 3 ',5 '-monophosphate positively function in Ca2+ elevation in methyl jasmonate-induced stomatal closure, cADPR is required for methyl jasmonate-induced ROS accumulation NO production in guard cells Reviewed

M. A. Hossain, W. Ye, S. Munemasa, Y. Nakamura, I. C. Mori, Y. Murata

PLANT BIOLOGY 16 ( 6 ) 1140 - 1144 2014.11

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

Methyl jasmonate (MeJA) signalling shares several signal components with abscisic acid (ABA) signalling in guard cells. Cyclic adenosine 5-diphosphoribose (cADPR) and cyclic guanosine 3,5-monophosphate (cGMP) are second messengers in ABA-induced stomatal closure. In order to clarify involvement of cADPR and cGMP in MeJA-induced stomatal closure in Arabidopsis thaliana (Col-0), we investigated effects of an inhibitor of cADPR synthesis, nicotinamide (NA), and an inhibitor of cGMP synthesis, LY83583 (LY, 6-anilino-5,8-quinolinedione), on MeJA-induced stomatal closure. Treatment with NA and LY inhibited MeJA-induced stomatal closure. NA inhibited MeJA-induced reactive oxygen species (ROS) accumulation and nitric oxide (NO) production in guard cells. NA and LY suppressed transient elevations elicited by MeJA in cytosolic free Ca2+ concentration ([Ca2+](cyt)) in guard cells. These results suggest that cADPR and cGMP positively function in [Ca2+](cyt) elevation in MeJA-induced stomatal closure, are signalling components shared with ABA-induced stomatal closure in Arabidopsis, and that cADPR is required for MeJA-induced ROS accumulation and NO production in Arabidopsis guard cells.

DOI： 10.1111/plb.12175

Nuclear factor-kappaB sensitizes to benzyl isothiocyanate-induced antiproliferation in p53-deficient colorectal cancer cells Reviewed

N. Abe, D-X Hou, S. Munemasa, Y. Murata, Y. Nakamura

CELL DEATH & DISEASE 5 2014.11

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Benzyl isothiocyanate (BITC), a dietary isothiocyanate derived from cruciferous vegetables, inhibits the proliferation of colorectal cancer cells, most of which overexpress beta-catenin as a result of mutations in the genes for adenomatous polyposis coli or mutations in beta-catenin itself. Because nuclear factor-kappa B (NF-kappa B) is a plausible target of BITC signaling in inflammatory cell models, we hypothesized that it is also involved in BITC-inhibited proliferation of colorectal cancer cells. siRNA-mediated knockdown of the NF-kappa B p65 subunit significantly decreased the BITC sensitivity of human colorectal cancer HT-29 cells with mutated p53 tumor suppressor protein. Treating HT-29 cells with BITC induced the phosphorylation of I kappa B kinase, I kappa B-alpha and p65, the degradation of I kappa B-a, the translocation of p65 to the nucleus and the upregulation of NF-kappa B transcriptional activity. BITC also decreased alpha-catenin binding to a positive cis element of the cyclin D1 promoter and thus inhibited beta-catenin-dependent cyclin D1 transcription, possibly through a direct interaction between p65 and alpha-catenin. siRNA-mediated knockdown of p65 confirmed that p65 negatively affects cyclin D1 expression. On the other hand, when human colorectal cancer HCT-116 cells with wild-type p53 were treated with BITC, translocation of p65 to the nucleus was inhibited rather than enhanced. p53 knockout increased the BITC sensitivity of HCT-116 cells in a p65-dependent manner, suggesting that p53 negatively regulates p65-dependent effects. Together, these results identify BITC as a novel type of antiproliferative agent that regulates the NF-kappa B pathway in p53-deficient colorectal cancer cells.

DOI： 10.1038/cddis.2014.495

(-)-Epigallocatechin-3-gallate ameliorates photodynamic therapy responses in an in vitro T lymphocyte model. International journal

Hang Qi, Naomi Abe, Beiwei Zhu, Yoshiyuki Murata, Yoshimasa Nakamura

Phytotherapy research : PTR 28 ( 10 ) 1486 - 91 2014.10

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

(-)-Epigallocatechin-3-gallate (EGCG), the most abundant polyphenolic constituent in green tea, is known as a powerful antioxidant but concomitantly possesses a prooxidant property. We investigated the effect of EGCG on phloxine B (PhB)-induced photocytotoxicity in human T lymphocytic leukemia Jurkat cells. EGCG significantly potentiated PhB-induced photocytotoxic effects, including the inhibition of cell proliferation, DNA fragmentation, and caspase-3 activity induction in Jurkat cells. Catalase attenuated the enhanced cytotoxicity by EGCG, suggesting the involvement of extracellularly produced hydrogen peroxide. Indeed, EGCG significantly enhanced extracellular hydrogen peroxide formation induced by photo-irradiated PhB. The EGCG also enhanced intracellular reactive oxygen species accumulation, c-Jun N-terminal kinase (JNK) phosphorylation, and interferon-γ (IFN-γ) gene expression, all of which are involved in PhB-induced apoptosis. Taken together, our data suggest that EGCG is capable of potentiating photodynamic therapy responses, presumably through the intracellular oxidative stress-sensitive JNK/IFN-γ pathway by exogenous hydrogen peroxide formation.

DOI： 10.1002/ptr.5152

Purification and partial characterisation of a cathepsin L-like proteinase from sea cucumber (Stichopus japonicus) and its tissue distribution in body wall. International journal

Da-Yong Zhou, Xian-Na Chang, Sha-Sha Bao, Liang Song, Bei-Wei Zhu, Xiu-Ping Dong, Yuan Zong, Dong-Mei Li, Mao-Mao Zhang, Yu-Xin Liu, Yoshiyuki Murata

Food chemistry 158 192 - 9 2014.9

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

A cathepsin L-like proteinase (CLP) with molecular weight of 30.9 kDa from the gut of sea cucumber (Stichopus japonicas, S. japonicus) was isolated and purified to homogeneity by several chromatographic procedures. The enzyme exhibited optimum activity at pH 5.0-5.5 and 50 °C, and showed thermostability up to 40 °C. The enzyme activity was completely inhibited by Zn(2+), strongly inhibited by Fe(2+) and Cu(2+), drastically reduced by cysteine proteinase inhibitors, but slightly enhanced by thiol-activating agents. The enzyme efficiently hydrolysed the specific substrate of cathepsin L, but hardly hydrolysed the specific substrates for cathepsin B, cathepsin H and cathepsin K. Immunohistochemical studies indicated that the CLP was more abundant in the epidermis rather than in the dermis of S. japonicus body wall. The distribution of CLP showed positive correlation with autolysis rate. Therefore, the relationship between CLP and autolysis deserved further study.

DOI： 10.1016/j.foodchem.2014.02.105

Ascorbic acid synergistically potentiates phloxine b-induced photocytotoxicity in human acute promyelocytic leukemia cells. International journal

Hang Qi, Qian Wu, Naomi Abe, Shunya Saiki, Beiwei Zhu, Yoshiyuki Murata, Yoshimasa Nakamura

Journal of biochemical and molecular toxicology 28 ( 4 ) 167 - 73 2014.4

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

Ascorbic acid (AsA) is known as an antioxidant but concomitantly possesses a pro-oxidant property. Because the impact of AsA on photodynamic therapy response is unclear, we investigated the effect of AsA on photocytotoxicity induced by phloxine B in human acute promyelocytic leukemia HL-60 cells. AsA synergistically enhanced phloxine B-induced photocytotoxic effects, including inhibition of cell proliferation, DNA ladder formation, and caspase-3 activation, whereas AsA itself showed no photocytotoxicity. AsA also enhanced the consumption of the reduced glutathione level compared with the cells treated with phloxine B alone under the light condition. Combination of AsA with phloxine B under the light condition enhanced the phosphorylation of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK). These effects were completely cancelled by catalase. These results suggest that AsA synergistically enhances phloxine B-induced photocytotoxicity, possibly through the extracellular oxidative stress-dependent MAPK pathway activation.

DOI： 10.1002/jbt.21549

Accumulation of endogenous salicylic acid confers drought tolerance to Arabidopsis Reviewed International journal

Okuma, Eiji, Nozawa, Rieko, Murata, Yoshiyuki, Miura, Kenji

Plant Signaling & Behavior 9 ( 3 ) e28085 2014

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

We investigated stomatal phenotype and drought tolerance of Arabidopsis salicylic acid-accumulating mutants, acd6 and cpr5. In these mutants, the light-induced stomatal opening was impaired and the impairment of stomatal opening was restored by peroxidase inhibitors, salicylhydroxamic acid, and azide. The acd6 and cpr5 mutant plants were more tolerant to drought stress than wild-type plants. Introduction of nahG gene into the acd6 and cpr5 mutants removed the inhibition of stomatal opening and reduced the drought tolerance. Drought tolerance-related genes were more highly expressed in the cpr5 and acd6 mutant plants than in the wild-type plants. These results suggest that accumulation of salicylic acid improves drought tolerance through inhibition of light-induced stomatal opening in Arabidopsisc 2014 Landes Bioscience. © 2014 Landes Bioscience.

DOI： 10.4161/psb.28085

Thiol modification by bioactivated polyphenols and its potential role in skin inflammation. International journal

Yoshimasa Nakamura, Takeshi Ishii, Naomi Abe, Yoshiyuki Murata

Bioscience, biotechnology, and biochemistry 78 ( 6 ) 1067 - 70 2014

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

In the present study, we evaluated the modifying behavior of simple phenolic compounds on the sulfhydryl groups of glutathione and proteins. The catechol-type polyphenols, including protocatechuic acid, but neither the monophenols nor O-methylated catechol, can modify the sulfhydryl groups in a phenol oxidase-dependent manner. The possible involvement of polyphenol bioactivation in the enhancement of skin inflammation was also suggested.

DOI： 10.1080/09168451.2014.905190

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