Tetsuro Kamiya
Research interests
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InterestsPCR, Gene Expression, Gene Regulation, Epigenetics, DNA Methylation
Publications
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2.22Impact points
TPA induces the expression of EC-SOD in human monocytic THP-1 cells: Involvement of PKC, MEK/ERK and NOX-derived ROS.
Free radical research. 03/2012; 46(5):637-44.
Abstract Extracellular-superoxide dismutase (EC-SOD) is a major SOD isozyme mainly present in the vascular wall. EC-SOD is also observed in monocytes/macrophages, and its high expression contributes to the suppression of atherosclerosis by scavenging superoxide. The molecular mechanisms governing ce... [more] Abstract Extracellular-superoxide dismutase (EC-SOD) is a major SOD isozyme mainly present in the vascular wall. EC-SOD is also observed in monocytes/macrophages, and its high expression contributes to the suppression of atherosclerosis by scavenging superoxide. The molecular mechanisms governing cell-specific expression of EC-SOD are mostly unknown, while the anti-oxidative effect of EC-SOD is well recognized. In this study, we investigated the expression of EC-SOD during 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced monocytic differentiation of THP-1 cells, which is not expressing its gene in the basal phase. We confirmed the significant induction of EC-SOD in a TPA time-dependent manner, and that induction was completely blocked by pre-treatment with GF109203X, an inhibitor of protein kinase C, U0126 and PD98059, inhibitors of mitogen-activated protein kinase kinase/extracellular-signal regulated kinase. Moreover, we determined the involvement of NADPH oxidase-derived reactive oxygen species in that induction. Overall, we considered that these results may contribute to clarify the cell-specific expression of EC-SOD.
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3.05Impact points
Contribution of p38 MAPK, NF-κB and glucocorticoid signaling pathways to ER stress-induced increase in retinal endothelial permeability.
Archives of biochemistry and biophysics. 01/2012; 520(1):30-5.
Diabetic retinopathy (DR) is characterized by the development of intraretinal microvascular abnormalities. Endoplasmic reticulum (ER) stress is known to play a pathogenic role in vascular impairment in DR. The present study demonstrated that the treatment of human retinal endothelial cells with ER s... [more] Diabetic retinopathy (DR) is characterized by the development of intraretinal microvascular abnormalities. Endoplasmic reticulum (ER) stress is known to play a pathogenic role in vascular impairment in DR. The present study demonstrated that the treatment of human retinal endothelial cells with ER stress inducers such as thapsigargin (Tg) and tunicamycin (Tm) significantly increased the permeability of exogenously added FITC-dextran, accompanied by a decrease of transendothelial electrical resistance (TEER). The expression of claudin-5 among tight junction proteins was significantly decreased by the treatment with Tg or Tm. A p38 MAPK inhibitor, SB203580, and an NF-κB inhibitor, dexamethasone, significantly suppressed the Tg-induced down-regulation of claudin-5, decrease of TEER and leakage of added FITC-dextran. The translocation of NF-κB p65 subunit to the nucleus was also inhibited by the addition of SB203580 or dexamethasone. The effects of dexamethasone are thought to be due to the transrepression of the above signaling and direct regulation of claudin-5 gene.
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2.22Impact points
Endoplasmic reticulum stress induces retinal endothelial permeability of extracellular-superoxide dismutase.
Free radical research. 09/2011; 45(9):1083-92.
The aim of this study was to determine the reasons why the intravitreal level of extracellular-superoxide dismutase (EC-SOD) increases in proliferative diabetic retinopathy patients by the investigation of two possibilities: first, change of EC-SOD expression in the retina; and secondly, leakage of ... [more] The aim of this study was to determine the reasons why the intravitreal level of extracellular-superoxide dismutase (EC-SOD) increases in proliferative diabetic retinopathy patients by the investigation of two possibilities: first, change of EC-SOD expression in the retina; and secondly, leakage of EC-SOD through the endothelial monolayer by the treatment with endoplasmic reticulum (ER) stress inducers because ER stress is known to be involved in the vascular impairment in diabetic retinopathy. Intravitreous injection of tunicamycin in mice increased the permeability of tracer dye across retinal blood vessels while the retinal EC-SOD mRNA level was not changed. The leakage of EC-SOD through the retinal endothelial cell layer was elevated by the treatment with thapsigargin or tunicamycin. The expression of claudin-5 was significantly decreased by the treatment with the ER stress inducers. These phenomena were significantly suppressed by the pre-treatment of endothelial cells with a chemical chaperone 4-phenylbutyric acid. Our observations suggest that ER stress leads to the down-regulation of claudin-5 among tight junction proteins and may induce the elevation of endothelial permeability and leakage of EC-SOD into the vitreous body.
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2.82Impact points
Inhibitory effects of chalcone glycosides isolated from Brassica rapa L. 'hidabeni' and their synthetic derivatives on LPS-induced NO production in microglia.
Bioorganic & medicinal chemistry. 07/2011; 19(18):5559-68.
Activation of microglia induces the production of various inflammatory mediators including nitric oxide (NO), leading to neurodegeneration in many central nervous system diseases. In this study, we examined the effects of chalcone glycosides isolated from Brassica rapa L. 'hidabeni' on lipop... [more] Activation of microglia induces the production of various inflammatory mediators including nitric oxide (NO), leading to neurodegeneration in many central nervous system diseases. In this study, we examined the effects of chalcone glycosides isolated from Brassica rapa L. 'hidabeni' on lipopolysaccharide (LPS)-induced NO production using rat immortalized microglia HAPI cells. 4'-O-β-D-Glucopyranosyl-3',4-dimethoxychalcone (A2) inhibited LPS-induced inducible NO synthase (iNOS) expression and NO production. However, A2 did not affect nuclear factor-κB and mitogen-activated protein kinase pathways. The signal transduction and activator of transcription 1 (STAT1), which is activated via production of IFN-β by LPS, is an important transcription factor responsible for LPS-induced iNOS expression. A2 suppressed LPS-induced phosphorylation and nuclear translocation of STAT1, although it had no effects on LPS-induced IFN-β expression. These results indicate that the inhibitory effect of A2 is due to the prevention of STAT signaling. Moreover, structure-activity relationship studies on newly synthesized 'hidabeni' chalcone derivatives showed that 4'-O-β-D-glucopyranosyl-3'-methoxychalcone (A11), which has no functional groups in the B-ring, inhibits LPS-induced NO production more potently than A2.
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2.22Impact points
ER stress inducer, thapsigargin, decreases extracellular-superoxide dismutase through MEK/ERK signalling cascades in COS7 cells.
Free radical research. 03/2011; 45(6):692-8.
It has been reported that tubular cells suffer an endoplasmic reticulum (ER) stress during the development of chronic kidney disease, which is a potent risk factor of cardiovascular disease. Moreover, under these conditions, reactive oxygen species are generated and induce cell injury. Extracellular... [more] It has been reported that tubular cells suffer an endoplasmic reticulum (ER) stress during the development of chronic kidney disease, which is a potent risk factor of cardiovascular disease. Moreover, under these conditions, reactive oxygen species are generated and induce cell injury. Extracellular-superoxide dismutase (EC-SOD) is a member of SODs and protects the cells from oxidative stress. Here, it is demonstrated that thapsigargin, an ER stress inducer, decreased EC-SOD expression, whereas the expression of Cu,Zn-SOD and Mn-SOD was not changed. On the other hand, another ER stress inducer, tunicamycin, did not affect the expression of EC-SOD. Further, it was shown that thapsigargin has the ability to activate extracellular-signal regulated kinase (ERK), but tunicamycin does not. Moreover, pre-treatment with U0126, an inhibitor of mitogen-activated protein kinase kinase (MEK)/ERK, suppressed thapsigargin-triggered EC-SOD reduction, suggesting that MEK/ERK signalling should play an important role in the regulation of EC-SOD in COS7 cells under ER stress conditions.
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1.81Impact points
Extracellular-superoxide dismutase expression in COS7 cells exposed to cadmium chloride.
Biological & pharmaceutical bulletin. 01/2011; 34(9):1443-7.
Cadmium (Cd), an industrial and environmental pollutant, preferentially accumulates in the kidney, a major target for Cd-related toxicity. It has been reported that Cd exposure produces reactive oxygen species (ROS) and induces cytotoxicity. Extracellular-superoxide dismutase (EC-SOD) is an antioxid... [more] Cadmium (Cd), an industrial and environmental pollutant, preferentially accumulates in the kidney, a major target for Cd-related toxicity. It has been reported that Cd exposure produces reactive oxygen species (ROS) and induces cytotoxicity. Extracellular-superoxide dismutase (EC-SOD) is an antioxidant enzyme that protects the cells from damaging effects of ROS; however, the effect of Cd on the expression of EC-SOD in COS7 cells remains unclear. In this study, exposure to cadmium chloride (CdCl₂) enhanced intracellular ROS generation and induced COS7 cell death. Moreover, exposure to Cd decreased the expression of EC-SOD at mRNA and protein levels, but not of other SOD isozymes, copper-and zinc-containing SOD and manganese-containing SOD. The reduction of EC-SOD and cell viability was partially attenuated by pretreatment with an antioxidant, N-acetylcysteine. Further, we determined the involvement of p38-mitogen-activated protein kinase (p38-MAPK) in the reduction of EC-SOD. From these observations, p38-MAPK signaling cascades activated by ROS play a pivotal role in the reduction of EC-SOD, and it is concluded that the reduction of EC-SOD leads to a decrease in the resistance to oxidative stress of Cd-exposed COS7 cells.
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1.81Impact points
Effect of hypoxia mimetic cobalt chloride on the expression of extracellular-superoxide dismutase in retinal pericytes.
Biological & pharmaceutical bulletin. 01/2011; 34(8):1297-300.
The initial clinical stage of diabetic retinopathy (DR) is characterized by the development of intraretinal microvascular abnormalities. The increased formation of reactive oxygen species (ROS) is thought to be a key event in the pathogenesis of DR. Extracellular-superoxide dismutase (EC-SOD) is an ... [more] The initial clinical stage of diabetic retinopathy (DR) is characterized by the development of intraretinal microvascular abnormalities. The increased formation of reactive oxygen species (ROS) is thought to be a key event in the pathogenesis of DR. Extracellular-superoxide dismutase (EC-SOD) is an anti-inflammatory enzyme that is distributed mainly in vascular cells and protects cells from ROS by scavenging superoxide anion. Treatment with cobalt chloride (CoCl(2)) decreased the expression of EC-SOD but not other SOD isozymes in pericytes accompanied with an increase of intracellular ROS production. Pre-treatment with N-acetylcysteine (NAC) significantly suppressed the ROS production and down-regulation of EC-SOD. We observed the activation of caspase-3 and DNA fragmentation as signs of apoptotic process by CoCl(2) treatment. In addition, these phenomena were significantly inhibited by pre-treatment with NAC. EC-SOD enhancer 4-phenyl butyric acid also suppressed the caspase-3 activation. It is known that the presence of a high level of EC-SOD throughout the vessel walls might have an important protective role against superoxide in the vascular system. The decrease in EC-SOD expression accompanied with elevation of ROS level in pericytes under hypoxia might induce and/or promote the ROS-triggered apoptosis of pericytes and the development of pathogenesis in DR.
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2.94Impact points
Extracellular-superoxide dismutase expression during monocytic differentiation of U937 cells.
Journal of cellular biochemistry. 11/2010; 112(1):244-55.
Leukemic cell lines, such as U937, THP-1, and HL60 cells, can differentiate into macrophages following exposure to various agents including 12-O-tetradecanoylphorbol-13-acetate (TPA) in vitro. It is well known that TPA enhances reactive oxygen species (ROS) generation through the activation of NADPH... [more] Leukemic cell lines, such as U937, THP-1, and HL60 cells, can differentiate into macrophages following exposure to various agents including 12-O-tetradecanoylphorbol-13-acetate (TPA) in vitro. It is well known that TPA enhances reactive oxygen species (ROS) generation through the activation of NADPH oxidase (NOX), and ROS act as mediators in TPA signaling. Extracellular-superoxide dismutase (EC-SOD) is a major anti-oxidative enzyme that protects the cells from damaging effects of superoxide. Recently, the reduction of Cu/Zn-SOD and the induction of Mn-SOD by TPA in leukemic cells have been reported; however, the regulation of EC-SOD by TPA remains poorly understood. Here, we explored the regulation of EC-SOD during the monocytic differentiation of U937 cells by TPA. We observed the reduction of EC-SOD and Cu/Zn-SOD, whereas the induction of Mn-SOD during the differentiation of U937 cells. The reduction of EC-SOD and Cu/Zn-SOD was attenuated by pretreatments with GF109203X (an inhibitor of protein kinase C, PKC), diphenyleneiodonium (an inhibitor of NOX), and U0126 (an inhibitor of mitogen-activated protein kinase kinase, MEK/extracellular-signal regulated kinase, ERK). Interestingly, pretreatment with BAY11-7082 (an inhibitor of nuclear factor-κB, NF-κB) suppressed the reduction of Cu/Zn-SOD, but not of EC-SOD. Furthermore, we also determined the involvement of newly synthesized protein and the instability of mRNA in the reduction of EC-SOD. Overall, our results suggest that the expression of EC-SOD is decreased by TPA through intracellular signaling consisting of PKC, NOX-derived ROS and MEK/ERK, but not of NF-κB signaling.
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3.54Impact points
Endoplasmic reticulum stress inducers provide protection against 6-hydroxydopamine-induced cytotoxicity.
Neurochemistry international. 10/2010; 58(1):35-43.
6-Hydroxydopamine (6-OHDA) is a neurotoxin used to establish experimental models of Parkinson's disease. Exposure to 6-OHDA results in cell death associated with oxidative stress. Pretreatments with sublethal oxidative stress and some pharmacological drugs have been shown to exert preconditionin... [more] 6-Hydroxydopamine (6-OHDA) is a neurotoxin used to establish experimental models of Parkinson's disease. Exposure to 6-OHDA results in cell death associated with oxidative stress. Pretreatments with sublethal oxidative stress and some pharmacological drugs have been shown to exert preconditioning effects on cytotoxicity caused by 6-OHDA. In this study, we investigated whether endoplasmic reticulum (ER) stress exerts preconditioning effects on 6-OHDA-induced cytotoxicity in human neuroblastoma SH-SY5Y cells. Pretreatment with ER stress inducers, thapsigargin (Tg) and tunicamycin (Tm), promoted GRP78 mRNA induction and ATF4 translation, which are ER stress markers, under our experimental conditions and protected against the cytotoxicity. The protective effect of Tg was more potent than that of Tm. We also found that Tg induced the expression of the antioxidant gene heme oxygenase-1 (HO-1) in a dose-dependent manner, whereas Tm had a weak effect on HO-1 induction. Flow cytometric analysis revealed that reactive oxygen species generated by 6-OHDA were more effectively suppressed in cells pretreated with Tg than with Tm. Therefore, it is likely that Tg enhances antioxidative defenses in SH-SY5Y cells compared with Tm. Because actinomycin D inhibited HO-1 induction by Tg, the induction of HO-1 may be regulated at the transcriptional level. Moreover, the specific eIF2α phosphatase inhibitor salubrinal augmented Tg-induced HO-1 expression. Therefore, the downstream signaling pathway of eIF2α might be involved in Tg-induced HO-1 expression. On the other hand, the reporter assay revealed that Tg stimulated the antioxidant response element (ARE) that is located in regulatory regions of antioxidant genes such as HO-1. Taken together, our data suggest that preconditioning effects induced by Tg mediate an adaptive response to 6-OHDA-induced cytotoxicity via phosphorylation of eIF2α and activation of the ARE.
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1.51Impact points
Regulation of extracellular-superoxide dismutase in rat retina pericytes.
Redox report : communications in free radical research. 01/2010; 15(6):250-8.
Diabetic retinopathy (DR) is regarded as a disease of the retinal microvascular system and metabolic abnormalities that are characteristic of oxidative stress and endoplasmic reticulum (ER) stress have been identified in the retina. Pericytes are known to be susceptible to oxidative stress and selec... [more] Diabetic retinopathy (DR) is regarded as a disease of the retinal microvascular system and metabolic abnormalities that are characteristic of oxidative stress and endoplasmic reticulum (ER) stress have been identified in the retina. Pericytes are known to be susceptible to oxidative stress and selective dropout of pericytes is one of the earliest pathological changes in DR. Extracellular-superoxide dismutase (EC-SOD) is a major antioxidative enzyme and protects vascular cells from the damaging effects of superoxide. Treatment with own conditioned medium significantly decreased EC-SOD expression in pericytes, while the expression of vascular endothelial growth factor and tumor necrosis factor-α were elevated. The addition of chemical chaperone 4-phenyl butyric acid significantly suppressed the effects of conditioned medium on EC-SOD and GRP78, a prominent ER-resident chaperone. Moreover, the cell viability of pericytes changed in a manner similar to that of EC-SOD expression. These results suggest that the expressions of EC-SOD should be regulated, at least partially, through ER stress. Continuous flow of culture media neutralized the ER-stress triggered decrease of EC-SOD expression. The stagnation of factors related to ER-stress around pericytes might reduce EC-SOD expression under pathophysiological conditions such as retinal edema, and this could induce and/or promote the intraretinal microvascular impairment and development of pathogenesis in DR.
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1.51Impact points
The effect of hypoxia mimetic cobalt chloride on the expression of EC-SOD in 3T3-L1 adipocytes.
Redox report : communications in free radical research. 01/2010; 15(3):131-7.
It is well known that adipose tissue is not only a passive reservoir for energy storage but also produces and secretes a variety of bioactive molecules called adipocytokines, including adiponectin and tumor necrosis factor-alpha (TNF-alpha). Recently, it has been reported that adipose tissue can suf... [more] It is well known that adipose tissue is not only a passive reservoir for energy storage but also produces and secretes a variety of bioactive molecules called adipocytokines, including adiponectin and tumor necrosis factor-alpha (TNF-alpha). Recently, it has been reported that adipose tissue can suffer a chronic hypoxic condition during hypertrophy of adipocytes, and this condition leads to the dysregulation of adipocytokines. Further, hypoxic adipocytes are in an increased oxidative stress. Extracellular-superoxide dismutase (EC-SOD) is an anti-inflammatory enzyme that protects cells from reactive oxygen species (ROS) by scavenging superoxide anion. Previous reports showed that plasma EC-SOD levels in type 2 diabetes patients were significantly and inversely related to the body mass index, homeostasis model assessment-insulin resistance index; however, the mechanisms of EC-SOD and adiponectin reductions during hypoxia remain poorly understood. Here, we demonstrate that cobalt chloride (CoCl(2)), a hypoxia mimetic, decreases EC-SOD and adiponectin in 3T3-L1 adipocytes by intracellular ROS-independent, but TNF-alpha and c-jun N-terminal kinase (JNK)-dependent mechanisms. From these results, it is possible that TNF-alpha is a key regulator of the reduction of EC-SOD and adiponectin in CoCl(2)-treated 3T3-L1 adipocytes, and we speculated that the reduction of EC-SOD and adiponectin would lead to and/or promote metabolic disorders.
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3.24Impact points
Nitric oxide mitigates apoptosis in human endothelial cells induced by 9,10-phenanthrenequinone: Role of proteasomal function.
Toxicology. 12/2009;
It has been widely recognized that nitric oxide (NO) suppresses oxidative damage of endothelial cell, but little is known about its pathophysiological role in apoptotic induction by 9,10-phenanthrenequinone (9,10-PQ), a major quinone component in diesel exhaust particles. Here, we have investigated ... [more] It has been widely recognized that nitric oxide (NO) suppresses oxidative damage of endothelial cell, but little is known about its pathophysiological role in apoptotic induction by 9,10-phenanthrenequinone (9,10-PQ), a major quinone component in diesel exhaust particles. Here, we have investigated the change in NO level in human aortic endothelial cells and the effect of NO in each step of apoptotic signaling initiated by 9,10-PQ. Treatment with 9,10-PQ evoked a bell-shaped production of NO, which was presumably due to increase in an active form of endothelial NO synthase. Pretreatment with exogenous NO decreased the susceptibility of the cells to 9,10-PQ, and retrieved from apoptotic signaling (reactive oxygen species generation, glutathione depletion and caspase activation) induced during exposure to high concentrations of 9,10-PQ. In addition, inhibition of endogenous NO production augmented the toxicity of 9,10-PQ. Interestingly, the 9,10-PQ treatment resulted in marked decreases in the proteasomal activities, which were partially abrogated by NO and a cell-permeable cGMP analog. These results indicate that proteasomal dysfunction by oxidative stress participates in the 9,10-PQ-induced apoptotic signaling and is ameliorated by NO via a cGMP-dependent pathway, thereby suggesting the protective role of NO in vascular damage caused by 9,10-PQ.
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2.46Impact points
Involvement of an aldo-keto reductase (AKR1C3) in redox cycling of 9,10-phenanthrenequinone leading to apoptosis in human endothelial cells.
Chemico-biological interactions. 06/2009;
9,10-Phenanthrenequinone (9,10-PQ), a major quinone found in diesel exhaust particles, is considered to generate reactive oxygen species (ROS) through its redox cycling. Here, we show that 9,10-PQ evokes apoptosis in human aortic endothelial cells (HAECs) and its apoptotic signaling includes ROS gen... [more] 9,10-Phenanthrenequinone (9,10-PQ), a major quinone found in diesel exhaust particles, is considered to generate reactive oxygen species (ROS) through its redox cycling. Here, we show that 9,10-PQ evokes apoptosis in human aortic endothelial cells (HAECs) and its apoptotic signaling includes ROS generation and caspase activation. The 9,10-PQ-induced cytotoxicity was inhibited by ROS scavengers, indicating that intracellular ROS generation is responsible for the 9,10-PQ-induced apoptosis. Comparison of mRNA expression levels and kinetic constants in the 9,10-PQ reduction among ten human reductases suggests that aldo-keto reductase 1C3 (AKR1C3) is a 9,10-PQ reductase in HAECs. In in vitro 9,10-PQ reduction by AKR1C3, the reduced product 9,10-dihydroxyphenathrene and superoxide anions were formed, suggesting the enzymatic two-electron reduction of 9,10-PQ that thereby causes oxidative stress through its redox cycling. In addition, the participation of AKR1C3 in 9,10-PQ redox cycling was confirmed by the data that AKR1C3 overexpression in endothelial cells augmented the ROS generation and cytotoxicity by 9,10-PQ, and the ROS scavengers inhibited the toxic effects. Pretreatment of the overexpressing cells with AKR1C3 inhibitors, flufenamic acid and indomethacin, suppressed the 9,10-PQ-induced GSH depletion. These results suggest that AKR1C3 is a key enzyme in the initial step of 9,10-PQ-induced cytotoxicity in HAECs.
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2.72Impact points
Zinc Induces Expression of the BH3-only Protein PUMA Through p53 and ERK Pathways in SH-SY5Y Neuroblastoma Cells.
Neurochemical research. 03/2009;
Accumulating evidence suggests that zinc (Zn(2+)) contributes to neuronal death in pathologic states such as ischemia. p53-upregulated modulator of apoptosis (PUMA), which is a BH3-only protein, is known to promote apoptosis through a tumor suppressor p53-dependent and -independent mechanism. In thi... [more] Accumulating evidence suggests that zinc (Zn(2+)) contributes to neuronal death in pathologic states such as ischemia. p53-upregulated modulator of apoptosis (PUMA), which is a BH3-only protein, is known to promote apoptosis through a tumor suppressor p53-dependent and -independent mechanism. In this study, we examined the effect of Zn(2+) on the induction of the PUMA gene in human neuroblastoma SH-SY5Y cells. The expression of PUMA was induced by Zn(2+) in a dose- and time-dependent manner. A reporter assay revealed that Zn(2+) activated the PUMA promoter. In addition, the mutation of the p53 binding site in the PUMA promoter region reduced promoter activation by Zn(2+). These findings suggest that p53 participates in Zn(2+)-induced PUMA expression. Furthermore, we also demonstrated here that Zn(2+) stimulates the phosphorylation of ERK and that the MEK-ERK pathway inhibitor, U0126, suppressed Zn(2+)-induced PUMA expression. Taken together, these results indicate that Zn(2+) regulates the induction of PUMA through p53 and ERK pathways.
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0.37Impact points
An Effort to Improve Advanced Problem-based Learning Tutorial.
Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan. 02/2009; 129(1):177-82.
To prepare for the introduction of the advanced problem-based learning (PBL) tutorial for higher-grade students under the six-year pharmacy curriculum, a trial of the tutorial was performed in a fourth-grade class under the former four-year curriculum in 2007. A questionnaire survey conducted to ide... [more] To prepare for the introduction of the advanced problem-based learning (PBL) tutorial for higher-grade students under the six-year pharmacy curriculum, a trial of the tutorial was performed in a fourth-grade class under the former four-year curriculum in 2007. A questionnaire survey conducted to identify any problems in performing the tutorial revealed: 1) the number of students in each group was too large; 2) the contents of presentations seemed to overlap due to the limited number of task cases, which forced more than one group to address a particular case; and 3) the time-line from the day of product presentation to that of periodic examination was too short to hold a sufficient group discussion. In 2008, to resolve these problems: 1) the number of groups was increased to reduce the number of students in each group; 2) new task cases were added to decrease the number of groups addressing a particular case; and 3) an adequate time period was arranged between the days of product presentation and periodic examination. The survey conducted this year demonstrated that students' learning environment had been improved by these changes in the method of performing the tutorial, but also revealed new problems such as prolongation of the time required for product presentation and the difficulty levels of task cases. In addition, the usefulness of customer satisfaction (CS) analysis was demonstrated as a result of applying it to the data analysis of evaluation performed on group presentations.
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1.51Impact points
Expression of extracellular superoxide dismutase during adipose differentiation in 3T3-L1 cells.
Redox report : communications in free radical research. 02/2009; 14(1):34-40.
Obesity is known to be the primary causal component in metabolic syndrome. Adipocytes in obese patients exhibit increased oxidative stress via the activation of reactive oxygen species (ROS)-producing systems and inactivation of antioxidant enzymes. Extracellular superoxide dismutase (EC-SOD) is an ... [more] Obesity is known to be the primary causal component in metabolic syndrome. Adipocytes in obese patients exhibit increased oxidative stress via the activation of reactive oxygen species (ROS)-producing systems and inactivation of antioxidant enzymes. Extracellular superoxide dismutase (EC-SOD) is an anti-inflammatory enzyme that protects cells from the damaging effects of ROS. An earlier report showed that plasma EC-SOD levels in type 2 diabetic patients were significantly and inversely related to body mass index and homeostasis model assessment-insulin resistance index. Moreover, the administration of pioglitazone, an antidiabetic agent, significantly increased the plasma level of EC-SOD. In this report, the expression of EC-SOD was compared to other adipocytokines in mice 3T3-L1 pre-adipocytes. EC-SOD expression levels were increased after the induction of differentiation and then declined, which was similar to adiponectin and transcription factors such as peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and CCAAT/enhancer-binding protein-alpha (C/EBP-alpha). On the other hand, the expression levels of pro-inflammatory adipocytokines, such as tumor necrosis factor-alpha (TNF-alpha) and monocyte chemo-attractant protein-1 (MCP-1), increased markedly in the development stage of cells. It was observed that the expression of EC-SOD in differentiated 3T3-L1 cells co-cultured with LPS-stimulated J774 macrophages was up-regulated, while the addition of TNF-alpha down-regulated EC-SOD and adiponectin expression in adipocytes. It is known that infiltrated and activated macrophages produce extracellular ROS at high levels in adipose tissue. It is possible that the expression of EC-SOD in adipocytes was stimulated to protect them from oxidative stress in the co-culture system.
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2.22Impact points
Cobalt chloride decreases EC-SOD expression through intracellular ROS generation and p38-MAPK pathways in COS7 cells.
Free radical research. 12/2008;
It is known that cells suffer a chronic hypoxic condition during the development of proximal tubulointerstitial disease. However, it is accepted that extracellular-superoxide dismutase (EC-SOD) protects the cells from oxidative stress. The purpose of this study was to elucidate the regulation of EC-... [more] It is known that cells suffer a chronic hypoxic condition during the development of proximal tubulointerstitial disease. However, it is accepted that extracellular-superoxide dismutase (EC-SOD) protects the cells from oxidative stress. The purpose of this study was to elucidate the regulation of EC-SOD expression in cells under hypoxia. The results show that the expressions of EC-SOD mRNA and protein in cobalt chloride (CoCl(2))-treated COS7 cells decreased in a dose- and time-dependent manner, whereas the expressions of other SOD isoforms (Cu/Zn-SOD and Mn-SOD) were not changed. The down-regulation of EC-SOD mRNA was suppressed by pre-treatment with the antioxidant trolox and the p38 mitogen-activated protein kinase (p38-MAPK) inhibitor SB203580. It is concluded that the expression of EC-SOD is decreased through ROS and p38-MAPK signalling cascades and that the down-regulation of EC-SOD leads to a decrease in the resistance to oxidative stress of COS7 cells under hypoxia induced by CoCl(2).
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6.08Impact points
L-Xylulose reductase is involved in 9,10-phenanthrenequinone-induced apoptosis in human T lymphoma cells.
Free radical biology & medicine. 04/2008; 44(6):1191-202.
9,10-Phenanthrenequinone (9,10-PQ), a major component in diesel exhaust particles, is suggested to generate reactive oxygen species (ROS) through its redox cycling, leading to cell toxicity. l-Xylulose reductase (XR), a NADPH-dependent enzyme in the uronate pathway, strongly reduces alpha-dicarbonyl... [more] 9,10-Phenanthrenequinone (9,10-PQ), a major component in diesel exhaust particles, is suggested to generate reactive oxygen species (ROS) through its redox cycling, leading to cell toxicity. l-Xylulose reductase (XR), a NADPH-dependent enzyme in the uronate pathway, strongly reduces alpha-dicarbonyl compounds and was thought to act as a detoxification enzyme against reactive carbonyl compounds. Here, we have investigated the role of intracellular ROS generation in apoptotic signaling in human acute T-lymphoblastic leukemia MOLT-4 cells treated with 9,10-PQ and the role of XR in the generation of ROS. Treatment with 9,10-PQ elicited not only apoptotic signaling, including mitochondrial membrane dysfunction and activation of caspases and poly(ADP-ribose) polymerase, but also intracellular ROS generation and consequent glutathione depletion. The apoptotic effects of 9,10-PQ were drastically mitigated by pretreatment with intracellular ROS scavengers, such as N-acetyl-l-cysteine, glutathione monoethyl ester, and polyethylene glycol-conjugated catalase, indicating that intracellular ROS generation is responsible for the 9,10-PQ-evoked apoptosis. Surprisingly, the ROS generation and cytotoxicity by 9,10-PQ were augmented in an XR-transformed cell line. XR indeed reduced 9,10-PQ and produced superoxide anion through redox cycling. In addition, the expression levels of XR and its mRNA in the T lymphoma cells were markedly enhanced after the exposure to 9,10-PQ, and the induction was completely abolished by the ROS scavengers. Moreover, the 9,10-PQ-induced apoptosis was partially inhibited by the pretreatment with XR-specific inhibitors. These results suggest that initially produced ROS induce XR, which accelerates the generation of ROS.
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Involvement of an aldo-keto reductase (AKR1C3) in redox cycling of 9,10-phenanthrenequinone leading to apoptosis in human endothelial cells
Chemico-Biological Interactions.
9,10-Phenanthrenequinone (9,10-PQ), a major quinone found in diesel exhaust particles, is considered to generate reactive oxygen species (ROS) through its redox cycling. Here, we show that 9,10-PQ evokes apoptosis in human aortic endothelial cells (HAECs) and its apoptotic signaling includes ROS gen... [more] 9,10-Phenanthrenequinone (9,10-PQ), a major quinone found in diesel exhaust particles, is considered to generate reactive oxygen species (ROS) through its redox cycling. Here, we show that 9,10-PQ evokes apoptosis in human aortic endothelial cells (HAECs) and its apoptotic signaling includes ROS generation and caspase activation. The 9,10-PQ-induced cytotoxicity was inhibited by ROS scavengers, indicating that intracellular ROS generation is responsible for the 9,10-PQ-induced apoptosis. Comparison of mRNA expression levels and kinetic constants in the 9,10-PQ reduction among 10 human reductases suggests that aldo-keto reductase 1C3 (AKR1C3) is a 9,10-PQ reductase in HAECs. In in vitro 9,10-PQ reduction by AKR1C3, the reduced product 9,10-dihydroxyphenanthrene and superoxide anions were formed, suggesting the enzymatic two-electron reduction of 9,10-PQ that thereby causes oxidative stress through its redox cycling. In addition, the participation of AKR1C3 in 9,10-PQ-redox cycling was confirmed by the data that AKR1C3 overexpression in endothelial cells augmented the ROS generation and cytotoxicity by 9,10-PQ, and the ROS scavengers inhibited the toxic effects. Pretreatment of the overexpressing cells with AKR1C3 inhibitors, flufenamic acid and indomethacin, suppressed the 9,10-PQ-induced GSH depletion. These results suggest that AKR1C3 is a key enzyme in the initial step of 9,10-PQ-induced cytotoxicity in HAECs.
Following (7)
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Hideaki Hara
Gifu Pharmaceutical University -
Hiroyuki Tanaka
Gifu Pharmaceutical University -
Satoshi Endo
Gifu Pharmaceutical University -
Abdallah Makhlof
Gifu Pharmaceutical University -
Masayuki Ninomiya
Gifu University
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