The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
Tatsuya Oda - One of the best experts on this subject based on the ideXlab platform.
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comparative study on Modeccin and phytohemagglutinin pha induced secretion of cytokines and nitric oxide no in raw264 7 cells
Acta Biochimica et Biophysica Sinica, 2011Co-Authors: Daekyung Kim, Yasuhiro Yamasaki, Zedong Jiang, Yuki Nakayama, Tomohiro Yamanishi, Kenichi Yamaguchi, Tatsuya OdaAbstract:The effects of cytotoxic lectins, Modeccin and phytohemagglutinin (PHA) on mouse macrophage cell line RAW264.7 was studied by detecting the induction of inflammatory mediators. Results showed that Modeccin induced the release of tumor necrosis factor-α (TNF-α) from RAW264.7 cells with a bell-shape concentration-dependent profile. PHA that showed no significant cytotoxicity on RAW264.7 cells up to 100,000 ng/ml induced much higher level of TNF-α than Modeccin. PHA simultaneously induced the secretion of granulocyte colony stimulation factor (G-CSF) from RAW264.7 cells with even much higher level than that of TNF-α, whereas Modeccin did not. Furthermore, PHA induced the secretion of nitric oxide (NO) in RAW264.7 cells, while no significant level of NO was detected in the Modeccin-treated cells. NH₄Cl (a lysomotoropic agent) and cycloheximide (a ribosome inhibitor) strongly inhibited Modeccin-induced TNF-α secretion, but no significant inhibitory effects of these reagents on the PHA-induced TNF-α secretion were observed. Contrary to Modeccin-induced TNF-α secretion, even slightly increased TNF-α secretion was observed in PHA-treated cells in the presence of 10 mM NH₄Cl. In addition, the inhibition profiles of Modeccin-induced TNF-α secretion by various kinase inhibitors were different from those of PHA. These results suggested that the action mode of Modeccin to stimulate RAW264.7 cells leading to the secretion of inflammatory molecules, including TNF-α, is distinct from that of PHA. On the other hand, significantly increased translocation of activator protein-1 (AP-1), a crucial transcription factor involved in expression of inflammatory molecules, into nucleus was observed in RAW264.7 cells treated with PHA and Modeccin.
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induction of cytokines by toxins that have an identical rna n glycosidase activity shiga toxin ricin and Modeccin
Biochimica et Biophysica Acta, 2004Co-Authors: Chisato Yamasaki, Tatsuya Oda, Nobukazu Komatsu, Kiyotaka Nishikawa, Xunting Zeng, Yukie Katayama, Yumiko Natori, Yasuhiro NatoriAbstract:Shiga toxin (Stx) has an A1-B5 subunit structure, and the A subunit is an RNA N-glycosidase that inhibits cellular protein synthesis. We previously reported that in Caco-2 cells Stx induced cytokines and that the RNA N-glycosidase activity was essential for the cytokine induction. It is known that the binding of the Stx-B subunit to its receptor glycolipid, Gb3, mediates an A subunit-independent signal in some types of cells, but the involvement of this signal in the cytokine induction is unclear. In this study, we investigated whether RNA N-glycosidase itself induces cytokines. IL-8 production was enhanced by Stx, ricin, and Modeccin, three toxins that inhibit protein synthesis through an identical RNA N-glycosidase activity, but not by two other types of protein synthesis inhibitors, diphtheria toxin and cycloheximide. The RNA N-glycosidase-type toxins showed a similar induction pattern of cytokine mRNAs. Brefeldin A, a Golgi apparatus inhibitor, completely suppressed the cytokine induction by the toxins. Analysis by using inhibitors of toxin binding and also Stx-B subunit showed that the cytokine-inducing activity was independent of Gb3-mediated signaling. These results indicate that RNA N-glycosidase itself induces the cytokine production and that intracellular transport of toxins through the Golgi apparatus is essential for the activity.
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resistance against ricin induced apoptosis in a brefeldin a resistant mutant cell line ber 40 of vero cells
Journal of Biochemistry, 2002Co-Authors: Tadashi Tamura, Tatsuya Oda, Tsuyoshi MuramatsuAbstract:We have found that a brefeldin A (BFA)-resistant mutant cell line derived from Vero cells (BER-40) is highly resistant to ricin-induced apoptosis as compared with parental Vero cells. In BER-40 cells, all apoptotic eventscaused by ricin including cytolysis, nuclear morphological changes, and DNA fragmentation occur to a lesser extent than in Vero cells, even though both cell lines show similar sensitivities to ricin-mediated inhibition of protein synthesis. Furthermore, no significant apoptotic signaling events, such as increases in caspase-3 and -9-like activities, release of cytochrome c from mitochondria, or the cleavage of PARP, were observed in BER-40 cells under the conditions at which these changes were evident in Vero cells. Intracellular biochemical changes associated with ricin-induced apoptosis, such as the depletion of glutathione and an increase in free Zn 2 + , were also less apparent in BER-40 cells than in Vero cells. BER-40 cells were also found to be highly resistant to apoptosis induced by other toxins with different intoxication mechanisms such as diphtheria toxin, Modeccin, and anisomycin. These results suggest that the entire apoptotic signal transduction mechanism in BER-40 cells, which may be triggered after the inhibition of protein synthesis by toxins, becomes resistant. Since MDCK cells, a naturally BFA resistant cell line, are highly sensitive to ricin-induced apoptosis, it seems likely that the BFA resistance phenotype may not necessarily lead to resistance to apoptotic cell death. Probably the underlaying BFA-resistance mechanism in BER-40 cells is distinct from that in MDCK cells, and the resistance to ricin-induced apoptosis of BER-40 cells may be a unique phenotype acquired concomitantly with BFA-resistance.
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involvement of both caspase like proteases and serine proteases in apoptotic cell death induced by ricin Modeccin diphtheria toxin and pseudomonas toxin
Journal of Biochemistry, 1998Co-Authors: Nobukazu Komatsu, Tatsuya Oda, Tsuyoshi MuramatsuAbstract:We investigated the involvement of caspases and serine proteases in apoptotic cell death induced by ricin, Modeccin, diphtheria toxin, and Pseudomonas toxin in U937 cells. We found that caspase-3- and caspase-6-like activities, but not caspase-1-like activity, increased during toxin-induced apoptosis. Z-D-CH2-DCB, a caspase-like inhibitor, completely inhibited the generation of caspase-3- and caspase-6-like activities and blocked all features of apoptosis induced by toxins: nuclear morphological changes, DNA fragmentation, and cytotoxicity. However, three caspase-specific inhibitors, Ac-YVAD-CHO, Ac-DEVD-CHO, and Ac-VEID-CHO, had no effect, even though Ac-DEVD-CHO and Ac-VEID-CHO inhibited the increased caspase-3- and caspase-6-like activity, respectively. These results suggest that the generation of caspase-3- and caspase-6-like activities is redundant, and other caspases distinct from caspase-3 and -6 may be important in toxin-induced apoptosis. Furthermore, serine protease inhibitor, 3,4-dichloroisocoumarine (DCI), abolished the apoptotic cell death and DNA fragmentation caused by toxins, without affecting the increased caspase-3- and caspase-6-like activities. Our results suggest that multiple proteases with different preferences for apoptotic substrates participate in toxin-induced apoptotic death of U937 cells.
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inhibitory effect of dideoxyforskolin on cell death induced by ricin Modeccin diphtheria toxin and pseudomonas toxin in mdck cells
Cell Structure and Function, 1997Co-Authors: Tatsuya Oda, Nobukazu Komatsu, Tsuyoshi MuramatsuAbstract:We have found that 1, 9-DideoxyforskoIin (DDF) strongly inhibited the cell death induced by ricin, Modeccin, Pseudomonas toxin, and diphtheria toxin in MDCK cells, suggesting that these protein toxins have a DDF-sensitive common pathway leading to cell death. However, no significant effect of forskolin on these toxins was observed, implying that cAMP-independent DDF specific mechanism is responsible for the inhibitory effect. The protective effect of DDF against ricin-induced cell death was significantly reversed by the increase in extracellular Ca2+ concentrations. The addition of brefeldin A (BFA) also reversed the protective effect of DDF, while BFA alone slightly increased the cytotoxicity of ricin. The protein synthesis inhibitory activity of Modeccin was strongly inhibited by DDF, while only partial inhibition of the activities of ricin and diphtheria toxin was observed. However, the activity of Pseudomonas toxin was enhanced by DDF rather than inhibited. Thus, the process leading to cell death and protein synthesis inhibition by these toxins may be separately affected by DDF, and the protective effect of DDF against toxin-induced cell death is distinct from its effect on protein synthesis inhibition by toxins. Forskolin and DDF slightly increased rather than inhibited the binding and the internalization of ricin to MDCK cells. Despite the strong inhibitory effect of DDF on toxin-induced cell death, DDF did not block toxin-induced DNA fragmentation. These results suggest that DNA fragmentation and cell death may be triggered through separate pathways during apoptosis caused by these toxins, and that a DDF-sensitive specific step may be present in the pathway leading to cell death.
Tsuyoshi Muramatsu - One of the best experts on this subject based on the ideXlab platform.
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resistance against ricin induced apoptosis in a brefeldin a resistant mutant cell line ber 40 of vero cells
Journal of Biochemistry, 2002Co-Authors: Tadashi Tamura, Tatsuya Oda, Tsuyoshi MuramatsuAbstract:We have found that a brefeldin A (BFA)-resistant mutant cell line derived from Vero cells (BER-40) is highly resistant to ricin-induced apoptosis as compared with parental Vero cells. In BER-40 cells, all apoptotic eventscaused by ricin including cytolysis, nuclear morphological changes, and DNA fragmentation occur to a lesser extent than in Vero cells, even though both cell lines show similar sensitivities to ricin-mediated inhibition of protein synthesis. Furthermore, no significant apoptotic signaling events, such as increases in caspase-3 and -9-like activities, release of cytochrome c from mitochondria, or the cleavage of PARP, were observed in BER-40 cells under the conditions at which these changes were evident in Vero cells. Intracellular biochemical changes associated with ricin-induced apoptosis, such as the depletion of glutathione and an increase in free Zn 2 + , were also less apparent in BER-40 cells than in Vero cells. BER-40 cells were also found to be highly resistant to apoptosis induced by other toxins with different intoxication mechanisms such as diphtheria toxin, Modeccin, and anisomycin. These results suggest that the entire apoptotic signal transduction mechanism in BER-40 cells, which may be triggered after the inhibition of protein synthesis by toxins, becomes resistant. Since MDCK cells, a naturally BFA resistant cell line, are highly sensitive to ricin-induced apoptosis, it seems likely that the BFA resistance phenotype may not necessarily lead to resistance to apoptotic cell death. Probably the underlaying BFA-resistance mechanism in BER-40 cells is distinct from that in MDCK cells, and the resistance to ricin-induced apoptosis of BER-40 cells may be a unique phenotype acquired concomitantly with BFA-resistance.
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involvement of both caspase like proteases and serine proteases in apoptotic cell death induced by ricin Modeccin diphtheria toxin and pseudomonas toxin
Journal of Biochemistry, 1998Co-Authors: Nobukazu Komatsu, Tatsuya Oda, Tsuyoshi MuramatsuAbstract:We investigated the involvement of caspases and serine proteases in apoptotic cell death induced by ricin, Modeccin, diphtheria toxin, and Pseudomonas toxin in U937 cells. We found that caspase-3- and caspase-6-like activities, but not caspase-1-like activity, increased during toxin-induced apoptosis. Z-D-CH2-DCB, a caspase-like inhibitor, completely inhibited the generation of caspase-3- and caspase-6-like activities and blocked all features of apoptosis induced by toxins: nuclear morphological changes, DNA fragmentation, and cytotoxicity. However, three caspase-specific inhibitors, Ac-YVAD-CHO, Ac-DEVD-CHO, and Ac-VEID-CHO, had no effect, even though Ac-DEVD-CHO and Ac-VEID-CHO inhibited the increased caspase-3- and caspase-6-like activity, respectively. These results suggest that the generation of caspase-3- and caspase-6-like activities is redundant, and other caspases distinct from caspase-3 and -6 may be important in toxin-induced apoptosis. Furthermore, serine protease inhibitor, 3,4-dichloroisocoumarine (DCI), abolished the apoptotic cell death and DNA fragmentation caused by toxins, without affecting the increased caspase-3- and caspase-6-like activities. Our results suggest that multiple proteases with different preferences for apoptotic substrates participate in toxin-induced apoptotic death of U937 cells.
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inhibitory effect of dideoxyforskolin on cell death induced by ricin Modeccin diphtheria toxin and pseudomonas toxin in mdck cells
Cell Structure and Function, 1997Co-Authors: Tatsuya Oda, Nobukazu Komatsu, Tsuyoshi MuramatsuAbstract:We have found that 1, 9-DideoxyforskoIin (DDF) strongly inhibited the cell death induced by ricin, Modeccin, Pseudomonas toxin, and diphtheria toxin in MDCK cells, suggesting that these protein toxins have a DDF-sensitive common pathway leading to cell death. However, no significant effect of forskolin on these toxins was observed, implying that cAMP-independent DDF specific mechanism is responsible for the inhibitory effect. The protective effect of DDF against ricin-induced cell death was significantly reversed by the increase in extracellular Ca2+ concentrations. The addition of brefeldin A (BFA) also reversed the protective effect of DDF, while BFA alone slightly increased the cytotoxicity of ricin. The protein synthesis inhibitory activity of Modeccin was strongly inhibited by DDF, while only partial inhibition of the activities of ricin and diphtheria toxin was observed. However, the activity of Pseudomonas toxin was enhanced by DDF rather than inhibited. Thus, the process leading to cell death and protein synthesis inhibition by these toxins may be separately affected by DDF, and the protective effect of DDF against toxin-induced cell death is distinct from its effect on protein synthesis inhibition by toxins. Forskolin and DDF slightly increased rather than inhibited the binding and the internalization of ricin to MDCK cells. Despite the strong inhibitory effect of DDF on toxin-induced cell death, DDF did not block toxin-induced DNA fragmentation. These results suggest that DNA fragmentation and cell death may be triggered through separate pathways during apoptosis caused by these toxins, and that a DDF-sensitive specific step may be present in the pathway leading to cell death.
Nobukazu Komatsu - One of the best experts on this subject based on the ideXlab platform.
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induction of cytokines by toxins that have an identical rna n glycosidase activity shiga toxin ricin and Modeccin
Biochimica et Biophysica Acta, 2004Co-Authors: Chisato Yamasaki, Tatsuya Oda, Nobukazu Komatsu, Kiyotaka Nishikawa, Xunting Zeng, Yukie Katayama, Yumiko Natori, Yasuhiro NatoriAbstract:Shiga toxin (Stx) has an A1-B5 subunit structure, and the A subunit is an RNA N-glycosidase that inhibits cellular protein synthesis. We previously reported that in Caco-2 cells Stx induced cytokines and that the RNA N-glycosidase activity was essential for the cytokine induction. It is known that the binding of the Stx-B subunit to its receptor glycolipid, Gb3, mediates an A subunit-independent signal in some types of cells, but the involvement of this signal in the cytokine induction is unclear. In this study, we investigated whether RNA N-glycosidase itself induces cytokines. IL-8 production was enhanced by Stx, ricin, and Modeccin, three toxins that inhibit protein synthesis through an identical RNA N-glycosidase activity, but not by two other types of protein synthesis inhibitors, diphtheria toxin and cycloheximide. The RNA N-glycosidase-type toxins showed a similar induction pattern of cytokine mRNAs. Brefeldin A, a Golgi apparatus inhibitor, completely suppressed the cytokine induction by the toxins. Analysis by using inhibitors of toxin binding and also Stx-B subunit showed that the cytokine-inducing activity was independent of Gb3-mediated signaling. These results indicate that RNA N-glycosidase itself induces the cytokine production and that intracellular transport of toxins through the Golgi apparatus is essential for the activity.
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involvement of both caspase like proteases and serine proteases in apoptotic cell death induced by ricin Modeccin diphtheria toxin and pseudomonas toxin
Journal of Biochemistry, 1998Co-Authors: Nobukazu Komatsu, Tatsuya Oda, Tsuyoshi MuramatsuAbstract:We investigated the involvement of caspases and serine proteases in apoptotic cell death induced by ricin, Modeccin, diphtheria toxin, and Pseudomonas toxin in U937 cells. We found that caspase-3- and caspase-6-like activities, but not caspase-1-like activity, increased during toxin-induced apoptosis. Z-D-CH2-DCB, a caspase-like inhibitor, completely inhibited the generation of caspase-3- and caspase-6-like activities and blocked all features of apoptosis induced by toxins: nuclear morphological changes, DNA fragmentation, and cytotoxicity. However, three caspase-specific inhibitors, Ac-YVAD-CHO, Ac-DEVD-CHO, and Ac-VEID-CHO, had no effect, even though Ac-DEVD-CHO and Ac-VEID-CHO inhibited the increased caspase-3- and caspase-6-like activity, respectively. These results suggest that the generation of caspase-3- and caspase-6-like activities is redundant, and other caspases distinct from caspase-3 and -6 may be important in toxin-induced apoptosis. Furthermore, serine protease inhibitor, 3,4-dichloroisocoumarine (DCI), abolished the apoptotic cell death and DNA fragmentation caused by toxins, without affecting the increased caspase-3- and caspase-6-like activities. Our results suggest that multiple proteases with different preferences for apoptotic substrates participate in toxin-induced apoptotic death of U937 cells.
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inhibitory effect of dideoxyforskolin on cell death induced by ricin Modeccin diphtheria toxin and pseudomonas toxin in mdck cells
Cell Structure and Function, 1997Co-Authors: Tatsuya Oda, Nobukazu Komatsu, Tsuyoshi MuramatsuAbstract:We have found that 1, 9-DideoxyforskoIin (DDF) strongly inhibited the cell death induced by ricin, Modeccin, Pseudomonas toxin, and diphtheria toxin in MDCK cells, suggesting that these protein toxins have a DDF-sensitive common pathway leading to cell death. However, no significant effect of forskolin on these toxins was observed, implying that cAMP-independent DDF specific mechanism is responsible for the inhibitory effect. The protective effect of DDF against ricin-induced cell death was significantly reversed by the increase in extracellular Ca2+ concentrations. The addition of brefeldin A (BFA) also reversed the protective effect of DDF, while BFA alone slightly increased the cytotoxicity of ricin. The protein synthesis inhibitory activity of Modeccin was strongly inhibited by DDF, while only partial inhibition of the activities of ricin and diphtheria toxin was observed. However, the activity of Pseudomonas toxin was enhanced by DDF rather than inhibited. Thus, the process leading to cell death and protein synthesis inhibition by these toxins may be separately affected by DDF, and the protective effect of DDF against toxin-induced cell death is distinct from its effect on protein synthesis inhibition by toxins. Forskolin and DDF slightly increased rather than inhibited the binding and the internalization of ricin to MDCK cells. Despite the strong inhibitory effect of DDF on toxin-induced cell death, DDF did not block toxin-induced DNA fragmentation. These results suggest that DNA fragmentation and cell death may be triggered through separate pathways during apoptosis caused by these toxins, and that a DDF-sensitive specific step may be present in the pathway leading to cell death.
F G Grillo - One of the best experts on this subject based on the ideXlab platform.
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brefeldin a enhancement of ricin a chain immunotoxins and blockade of intact ricin Modeccin and abrin
Journal of Biological Chemistry, 1991Co-Authors: T H Hudson, F G GrilloAbstract:Abstract After binding, the protein toxins ricin, abrin, and Modeccin are endocytosed and processed through the cell's vesicular system in a poorly understood fashion, prior to translocation to the cytosol. The role of the Golgi apparatus in toxin processing was studied using brefeldin-A (BFA), a fungal metabolite which blocks Golgi function. At concentrations that inhibit secretion of interleukin-2 (IL-2), BFA blocks ricin, Modeccin, and abrin intoxication of a lymphocyte derived cell line (Jurkat). Paradoxically, BFA enhances the toxicity of two ricin A-chain immunotoxins targeted against distinct cell surface determinants. BFA concentrations which are optimal for immunotoxin enhancement are below those needed to affect ricin intoxication or IL-2 secretion. BFA blockade of ricin does not involve effects on ricin endocytosis, toxin translocation to the cytosol, or the enzymatic activity of toxin A-chain. In contrast, BFA has no effect on immunotoxin processing but does enhance the immunotoxin translocation step. It is concluded that: 1) intact Golgi function is required for holotoxin processing. 2) Intact Golgi function is not required for holotoxin translocation. 3) Golgi function is tightly linked to immunotoxin translocation. 4) BFA has effects on vesicular routing in addition to the block of Golgi function in secretion which has been reported.
Andrea Bolognesi - One of the best experts on this subject based on the ideXlab platform.
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binding and intracellular routing of the plant toxic lectins lanceolin and stenodactylin
Biochimica et Biophysica Acta, 2010Co-Authors: Maria Giulia Battelli, Luigi Barbieri, Vittoria Scicchitano, Letizia Polito, Valentina Farini, Andrea BolognesiAbstract:Abstract Background The present research studied the interaction of two ribosome-inactivating proteins (RIPs) from Adenia genus with HeLa cells. Namely, lanceolin and stenodactylin were examined in comparison to volkensin, another toxic two-chain RIP from Adenia genus. Methods The binding, endocytosis, intracellular routing, degradation and exocytosis were investigated by measuring the distribution of radiolabelled RIP and by determining its cytotoxicity. Results Stenodactylin was the most toxic, resulting in the greater inhibition of protein synthesis and cell death. Lanceolin and stenodactylin bound to cells with comparable affinity and have a similar number of binding sites (105/cell). The uptake of lanceolin and stenodactylin was 13 and 36 times greater, respectively, than that reported for volkensin. The two toxins bound to cell membrane receptors via their lectin B chain, were endocytosed through a clathrin-independent pathway, were internalised in a manner independent from endosomal acidification, and required routing through the Golgi apparatus, as reported for Modeccin and volkensin. Stenodactylin showed greater uptake, exocytosis and re-uptake of non-degraded RIP than lanceolin and volkensin, whereas volkensin had the highest residual activity after being released from the cell. Conclusions The high cytotoxicity of RIPs from the Adenia genus may depend on the following: high affinity binding to the cell and efficient endocytosis, intracellular routing that appears similar to that of other ricin-like toxic RIPs, partial resistance to proteolysis, and, regarding stenodactylin, high accumulation in cell. General significance The data provide a model that could lead to new strategies for anti-cancer therapy and neuroscience studies.