Yoshiro Saito - Academia.edu (original) (raw)

Papers by Yoshiro Saito

Neuroscience Letters, Nov 1, 2009

DJ-1 was initially identified as a novel oncogene and has recently been found to be a causative g... more DJ-1 was initially identified as a novel oncogene and has recently been found to be a causative gene for a familial form of Parkinson's disease (PD), viz, PARK7. Cysteine residue at position 106 (Cys-106) in DJ-1 was found to be oxidized preferentially under oxidative stress. In the present study, we developed specific antibodies against Cys-106-oxidized DJ-1 using baculovirus particles displaying the surface glycoprotein gp64-fusion protein as the immunizing agent. Western blot analysis combined with two-dimensional gel electrophoresis revealed that these antibodies specifically recognized oxidized DJ-1. Furthermore, we developed a competitive enzyme-linked immunosorbent assay (ELISA) for detecting oxidized DJ-1 and measured blood levels of oxidized DJ-1 in PD patients (n=15). It was observed that the levels of oxidized DJ-1 in erythrocytes of unmedicated PD patients were markedly higher without overlap than those of medicated PD patients and healthy subjects. No significant difference was observed in DJ-1 levels between mediated and unmediated PD patient. These results suggest the oxidative modification of DJ-1 in PD patients and the potential application of the antibody for diagnosis of PD at early-stage.

Scientific Reports, 2018

We aimed to test the hypothesis that selenoprotein P (SELENOP), a hepatokine involved in the deve... more We aimed to test the hypothesis that selenoprotein P (SELENOP), a hepatokine involved in the development of both insulin resistance and impaired insulin production in mice, is related to future onset of hyperglycemia in humans. 76 healthy non-pregnant human subjects without diabetes underwent oral glucose tolerance test (OGTT) at baseline and 4-years follow-up. Nine subjects developed either impaired glucose tolerance or type 2 diabetes at follow-up. At baseline, SELENOP concentrations correlated negatively with insulinogenic index, but not with homeostasis model assessment-estimated insulin resistance (HOMA-IR). Multivariate analysis showed that baseline SELENOP predicted fasting plasma glucose at follow-up independently of the other parameters. The receiver operating characteristic (ROC) curve analysis showed that baseline concentrations of serum SELENOP, but not of selenium, were a reliable test to predict future onset of glucose intolerance. In conclusion, elevation of circulati...

Reactive oxygen species (ROS) oxidize and activate the uncoupler protein 1 (UCP1) in brown adipos... more Reactive oxygen species (ROS) oxidize and activate the uncoupler protein 1 (UCP1) in brown adipose tissue (BAT) under physiological cold exposure and noradrenaline (NA) stimulation to increase thermogenesis. However, pathological significance and the endogenous regulator of the ROS-mediated BAT activation remain unclear. Here, we show that serum levels of selenoprotein P (SeP, encoded by Selenop) are negatively correlated with BAT activity in humans. SeP impairs UCP1 activity and thermogenesis. Physiological cold exposure downregulates Selenop in BAT. BAT-specific Selenop-deficient (BAT-Selenop KO) mice presented elevated NA-induced mitochondrial ROS production, sulfenylated UCP1, and enhanced thermogenesis and glucose uptake in BAT during cold exposure. SeP inhibits mitochondrial ROS by upregulating the expression of the antioxidant enzyme, glutathione peroxidase 4, and impairs glucose uptake in brown adipocytes. High fat/high sucrose diet upregulates Selenop in the liver and inhib...

Journal of Lipid Research, 2015

Supplementary key words selenocysteine insertion sequence-binding protein 2 • selenoprotein • ant... more Supplementary key words selenocysteine insertion sequence-binding protein 2 • selenoprotein • antioxidative defense • free radical • cholesterol • oxysterol • oxidized lipids Selenium is primarily incorporated into proteins in the form of selenocysteine (Sec). Sec is the 21st amino acid to be translated and is encoded by the UGA codon (1). The biological role of selenium is mediated through Sec-containing proteins, termed selenoproteins (2, 3). A stemloop RNA structure, called the Sec insertion sequence (SECIS), is located in the 3 ′-untranslated region of selenoprotein mRNAs and is essential for the incorporation of Sec during the biosynthesis of selenoproteins (4). The SECIS interacts with a multi-protein complex, including SECIS-binding protein 2 (SBP2), which promotes Sec incorporation into growing polypeptides through selenocysteyl-transfer RNA at the UGA codon (4, 5). Although UGA primarily encodes a stop codon, this protein complex ensures that UGA is translated to Sec. The interaction between the SECIS element and SBP2 is particularly important for this translational system. Thus, defects in SBP2 Abstract Selenocysteine (Sec) insertion sequence-binding protein 2 (SBP2) is essential for the biosynthesis of Sec-containing proteins, termed selenoproteins. Subjects with mutations in the SBP2 gene have decreased levels of several selenoproteins, resulting in a complex phenotype. Selenoproteins play a signifi cant role in antioxidative defense, and defi ciencies in these proteins can lead to increased oxidative stress. However, lipid peroxidation and the effects of antioxidants in subjects with SBP2 gene mutations have not been studied. In the present study, we evaluated the lipid peroxidation products in the blood of a subject (the proband) with mutations in the SBP2 gene. We found that the proband had higher levels of free radical-mediated lipid peroxidation products, such as 7 ␤-hydroxycholesterol, than the control subjects. Treatment of the proband with vitamin E (␣-tocopherol acetate, 100 mg/day), a lipid-soluble antioxidant, for 2 years reduced lipid peroxidation product levels to those of control subjects. Withdrawal of vitamin E treatment for 7 months resulted in an increase in lipid peroxidation products. Collectively, these results clearly indicate that free radical-mediated oxidative stress is increased in the subject with SBP2 gene mutations and that vitamin E treatment effectively inhibits the generation of lipid peroxidation products.-Saito, Y.

BPB Reports

We've previously shown that high levels of selenoprotein P (SeP), a major selenoprotein in plasma... more We've previously shown that high levels of selenoprotein P (SeP), a major selenoprotein in plasma, can be a risk factor of type 2 diabetes. It was also thought that inhibition of insulin secretion caused by over-supplementation of selenium by SeP to pancreatic β cells contributed to the progress of diabetes. On the other hand, methylmercury, which is an environmental pollutant, is known to cancel the action of selenium via the covalent modification. Therefore, we thought that the interaction between selenium and methylmercury could be associated with the pathogenesis of diabetes. To address the hypothesis, MIN6 cells, a mouse pancreatic β-cell line, were treated with selenocystine (as a selenium donner) and methylmercury then examined insulin release from the cells. Selenocystine (400-1200 nM), which corresponds to the concentration of selenium in SeP of diabetic patients, shows cytotoxicity and inhibited glucose-driven insulin secretion. Methylmercury rescued the cytotoxicity that induced by selenocystine, however it affected the insulin secretion that is depressed by selenocystine at little intense. These data indicate that the mechanisms underlying inhibition of insulin secretion by selenocystine are independent of cytotoxicity, and methylmercury cannot be expected to restore insulin secretion or suppress diabetes as selenium neutlizer.

Chemical Research in Toxicology, 2009

Many investigations about the cellular response by metal oxide nanoparticles in vitro have been r... more Many investigations about the cellular response by metal oxide nanoparticles in vitro have been reported. However, the influence of the adsorption ability of metal oxide nanoparticles toward cells is unknown. The aim of this study is to understand the influence of adsorption by metal oxide nanoparticles on the cell viability in vitro. The adsorption abilities of six kinds of metal oxide nanoparticles, namely, NiO, ZnO, TiO 2 , CeO 2 , SiO 2 , and Fe 2 O 3 , to Dulbecco's modified Eagle's medium supplemented with a 10% fetal bovine serum (DMEM-FBS) component such as serum proteins and Ca 2+ were estimated. All of the metal oxide nanoparticles adsorbed proteins and Ca 2+ in the DMEM-FBS; in particular, TiO 2 , CeO 2 , and ZnO showed strong adsorption abilities. Furthermore, the influence of the depletion of medium components by adsorption to metal oxide nanoparticles on cell viability and proliferation was examined. The particles were removed from the dispersion by centrifugation, and the supernatant was applied to the cells. Both the cell viability and the proliferation of human keratinocyte HaCaT cells and human lung carcinoma A549 cells were affected by the supernatant. In particular, cell proliferation was strongly inhibited by the supernatant of TiO 2 and CeO 2 dispersions. The supernatant showed depletion of serum proteins and Ca 2+ by adsorption to metal oxide nanoparticles. When the adsorption effect was blocked by the pretreatment of particles with FBS, the inhibitory effect was lost. However, in NiO and ZnO, which showed ion release, a decrease of inhibitory effect by pretreatment was not shown. Furthermore, the association of the primary particle size and adsorption ability was examined in TiO 2. The adsorption ability of TiO 2 depended on the primary particle size. The TiO 2 nanoparticles were size dependently absorbed with proteins and Ca 2+ , thereby inducing cytotoxicity. In conclusion, the adsorption ability of metal oxide nanoparticles is an important factor for the estimation of cytotoxicity in vitro for low-toxicity materials.

Redox Experimental Medicine

Graphical abstract The essential trace element selenium plays a significant role in redox homeost... more Graphical abstract The essential trace element selenium plays a significant role in redox homeostasis in the human body. Selenium is very reactive and has a potent toxicity; however, the living body cleverly utilizes its reactivity for redox reactions. The biological function of selenium is mainly mediated by selenoproteins, which contain selenocysteine, a cysteine analogue that possesses selenium instead of sulphur. Twenty-five types of human selenoproteins have been identified, including glutathione peroxidase (GPX; for the reduction of hydrogen peroxide and lipid hydroperoxide) and thioredoxin reductase (for redox regulation). Selenoprotein P (SELENOP), which is a major selenoprotein in the plasma, is mainly synthesized in the liver and secreted into the plasma. As a multifunctional protein with selenium-transporting activity, GPX-like activity, and metal-binding properties, SELENOP plays a vital role in selenium metabolism and redox regulation. This review focuses on the relatio...

Scientific reports, Jan 13, 2018

DJ-1 plays an important role in antioxidant defenses, and a reactive cysteine at position 106 (Cy... more DJ-1 plays an important role in antioxidant defenses, and a reactive cysteine at position 106 (Cys106) of DJ-1, a critical residue of its biological function, is oxidized under oxidative stress. DJ-1 oxidation has been reported in patients with Parkinson's disease (PD), but the relationship between DJ-1 oxidation and PD is still unclear. In the present study using specific antibody for Cys106-oxidized DJ-1 (oxDJ-1), we analyzed oxDJ-1 levels in the brain and peripheral tissues in young and aged mice and in a mouse model of PD induced using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). OxDJ-1 levels in the brain, heart, and skeletal muscle were high compared with other tissues. In the brain, oxDJ-1 was detected in PD-related brain sites such as the substantia nigra (SN) of the midbrain, olfactory bulb (OB), and striatum. In aged wild-type mice, oxDJ-1 levels in the OB, striatum, and heart tended to decrease, while those in the skeletal muscle increased significantly. Expre...

Nature communications, Nov 21, 2017

Selenoprotein P (SeP) functions as a selenium (Se)-supply protein. SeP is identified as a hepatok... more Selenoprotein P (SeP) functions as a selenium (Se)-supply protein. SeP is identified as a hepatokine, promoting insulin resistance in type 2 diabetes. Thus, the suppression of Se-supply activity of SeP might improve glucose metabolism. Here, we develop an anti-human SeP monoclonal antibody AE2 as with neutralizing activity against SeP. Administration of AE2 to mice significantly improves glucose intolerance and insulin resistance that are induced by human SeP administration. Furthermore, excess SeP administration significantly decreases pancreas insulin levels and high glucose-induced insulin secretion, which are improved by AE2 administration. Epitope mapping reveals that AE2 recognizes a region of human SeP adjacent to the first histidine-rich region (FHR). A polyclonal antibody against the mouse SeP FHR improves glucose intolerance and insulin secretion in a mouse model of diabetes. This report describes a novel molecular strategy for the development of type 2 diabetes therapeuti...

Genes to cells : devoted to molecular & cellular mechanisms, 2018

Chronic myeloid leukemia (CML) is caused by the chimeric protein p210 BCR-ABL encoded by a gene o... more Chronic myeloid leukemia (CML) is caused by the chimeric protein p210 BCR-ABL encoded by a gene on the Philadelphia chromosome. Although the kinase domain of p210 BCR-ABL is an active driver of CML, the pathological role of its pleckstrin homology (PH) domain remains unclear. Here, we carried out phospholipid vesicle-binding assays to show that cardiolipin (CL), a characteristic mitochondrial phospholipid, is a unique ligand of the PH domain. Arg726, a basic amino acid in the ligand-binding region, was crucial for ligand recognition. A subset of wild-type p210 BCR-ABL that was transiently expressed in HEK293 cells was dramatically translocated from the cytosol to mitochondria in response to carbonyl cyanide m-chlorophenylhydrazone (CCCP) treatment, which induces mitochondrial depolarization and subsequent externalization of CL to the organelle's outer membrane, whereas an R726A mutant of the protein was not translocated. Furthermore, only wild-type p210 BCR-ABL, but not the R726...

PloS one, 2016

Oxidative stress is correlated with the incidence of several diseases such as atherosclerosis and... more Oxidative stress is correlated with the incidence of several diseases such as atherosclerosis and cancer, and oxidized biomolecules have been determined as biomarkers of oxidative stress; however, the detailed molecular relationship between generated oxidation products and the promotion of diseases has not been fully elucidated. In the present study, to clarify the role of serum oxidation products in vessel cell proliferation, which is related to the incidence of atherosclerosis and cancer, the major vessel cell proliferator in oxidized human serum was investigated. Oxidized human serum was prepared by free radical exposure, separated using gel chromatography, and then each fraction was added to several kinds of vessel cells including endothelial cells and smooth muscle cells. It was found that a high molecular weight fraction in oxidized human serum specifically induced vessel cell proliferation. Oxidized lipids were contained in this high molecular weight fraction, while cell prol...

Free Radical Biol Med, 2011

JOURNAL OF HEALTH SCIENCE, 2000

Selenoprotein P (SeP: the "P" denotes its presence in plasma) is the major selenoprotein in plasm... more Selenoprotein P (SeP: the "P" denotes its presence in plasma) is the major selenoprotein in plasma. All selenoproteins so far reported contain one atom of selenium (Se) as selenocysteine per molecule except SeP, which is thought to contain ten atoms of Se as selenocysteine per molecule. SeP contains 50% of the total Se in plasma. The function of SeP is currently unknown, although several indirect lines of evidence suggest that SeP is a free radical scavenger or Se transporter. Recently, we reported that SeP is capable of reducing phospholipid hydroperoxide in the presence of glutathione, and characterized the enzymatic nature of SeP. SeP is also reported to function as a peroxynitrite scavenger or cell survival factor in primary culture of neurons. In this minireview, we discuss the relationship between the structure and function of SeP.

Free Radical Biology and Medicine, 2010

Biological & Pharmaceutical Bulletin, 2003

Toxics

Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress r... more Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress response has rarely been examined. We previously reported that knockdown of HOXB13 reduces the cytotoxicity caused by various oxidative stress inducers. Here, we studied the role of HOXB13 in cytotoxicity caused by hydrogen peroxide in human lung epithelial A549 cells. The knockdown of HOXB13 reduced hydrogen peroxide-induced cytotoxicity; however, this phenomenon was largely absent in the presence of antioxidants (Trolox or N-acetyl cysteine (NAC)). This suggests that HOXB13 may be involved in the cytotoxicity caused by hydrogen peroxide via the production of reactive oxygen species (ROS). Hydrogen peroxide also increased both the mRNA and protein levels of HOXB13. However, these increases were rarely observed in the presence of a transcriptional inhibitor, which suggests that hydrogen peroxide increases protein levels via increased transcription of HOXB13. Furthermore, cell death occurr...

Toxics, 2020

Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress r... more Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress response has rarely been examined. We previously reported that knockdown of HOXB13 reduces the cytotoxicity caused by various oxidative stress inducers. Here, we studied the role of HOXB13 in cytotoxicity caused by hydrogen peroxide in human lung epithelial A549 cells. The knockdown of HOXB13 reduced hydrogen peroxide-induced cytotoxicity; however, this phenomenon was largely absent in the presence of antioxidants (Trolox or N-acetyl cysteine (NAC)). This suggests that HOXB13 may be involved in the cytotoxicity caused by hydrogen peroxide via the production of reactive oxygen species (ROS). Hydrogen peroxide also increased both the mRNA and protein levels of HOXB13. However, these increases were rarely observed in the presence of a transcriptional inhibitor, which suggests that hydrogen peroxide increases protein levels via increased transcription of HOXB13. Furthermore, cell death occurr...

Nucleic Acids Research

Selenoprotein P (SELENOP) is a major plasma selenoprotein that contains 10 Sec residues, which is... more Selenoprotein P (SELENOP) is a major plasma selenoprotein that contains 10 Sec residues, which is encoded by the UGA stop codon. The mRNA for SELENOP has the unique property of containing two Sec insertion sequence (SECIS) elements, which is located in the 3′ untranslated region (3′UTR). Here, we coincidentally identified a novel gene, CCDC152, by sequence analysis. This gene was located in the antisense region of the SELENOP gene, including the 3′UTR region in the genome. We demonstrated that this novel gene functioned as a long non-coding RNA (lncRNA) that decreased SELENOP protein levels via translational rather than transcriptional, regulation. We found that the CCDC152 RNA interacted specifically and directly with the SELENOP mRNA and inhibited its binding to the SECIS-binding protein 2, resulting in the decrease of ribosome binding. We termed this novel gene product lncRNA inhibitor of SELENOP translation (L-IST). Finally, we found that epigallocatechin gallate upregulated L-I...

Neuroscience Letters, Nov 1, 2009

DJ-1 was initially identified as a novel oncogene and has recently been found to be a causative g... more DJ-1 was initially identified as a novel oncogene and has recently been found to be a causative gene for a familial form of Parkinson's disease (PD), viz, PARK7. Cysteine residue at position 106 (Cys-106) in DJ-1 was found to be oxidized preferentially under oxidative stress. In the present study, we developed specific antibodies against Cys-106-oxidized DJ-1 using baculovirus particles displaying the surface glycoprotein gp64-fusion protein as the immunizing agent. Western blot analysis combined with two-dimensional gel electrophoresis revealed that these antibodies specifically recognized oxidized DJ-1. Furthermore, we developed a competitive enzyme-linked immunosorbent assay (ELISA) for detecting oxidized DJ-1 and measured blood levels of oxidized DJ-1 in PD patients (n=15). It was observed that the levels of oxidized DJ-1 in erythrocytes of unmedicated PD patients were markedly higher without overlap than those of medicated PD patients and healthy subjects. No significant difference was observed in DJ-1 levels between mediated and unmediated PD patient. These results suggest the oxidative modification of DJ-1 in PD patients and the potential application of the antibody for diagnosis of PD at early-stage.

Scientific Reports, 2018

We aimed to test the hypothesis that selenoprotein P (SELENOP), a hepatokine involved in the deve... more We aimed to test the hypothesis that selenoprotein P (SELENOP), a hepatokine involved in the development of both insulin resistance and impaired insulin production in mice, is related to future onset of hyperglycemia in humans. 76 healthy non-pregnant human subjects without diabetes underwent oral glucose tolerance test (OGTT) at baseline and 4-years follow-up. Nine subjects developed either impaired glucose tolerance or type 2 diabetes at follow-up. At baseline, SELENOP concentrations correlated negatively with insulinogenic index, but not with homeostasis model assessment-estimated insulin resistance (HOMA-IR). Multivariate analysis showed that baseline SELENOP predicted fasting plasma glucose at follow-up independently of the other parameters. The receiver operating characteristic (ROC) curve analysis showed that baseline concentrations of serum SELENOP, but not of selenium, were a reliable test to predict future onset of glucose intolerance. In conclusion, elevation of circulati...

Reactive oxygen species (ROS) oxidize and activate the uncoupler protein 1 (UCP1) in brown adipos... more Reactive oxygen species (ROS) oxidize and activate the uncoupler protein 1 (UCP1) in brown adipose tissue (BAT) under physiological cold exposure and noradrenaline (NA) stimulation to increase thermogenesis. However, pathological significance and the endogenous regulator of the ROS-mediated BAT activation remain unclear. Here, we show that serum levels of selenoprotein P (SeP, encoded by Selenop) are negatively correlated with BAT activity in humans. SeP impairs UCP1 activity and thermogenesis. Physiological cold exposure downregulates Selenop in BAT. BAT-specific Selenop-deficient (BAT-Selenop KO) mice presented elevated NA-induced mitochondrial ROS production, sulfenylated UCP1, and enhanced thermogenesis and glucose uptake in BAT during cold exposure. SeP inhibits mitochondrial ROS by upregulating the expression of the antioxidant enzyme, glutathione peroxidase 4, and impairs glucose uptake in brown adipocytes. High fat/high sucrose diet upregulates Selenop in the liver and inhib...

Journal of Lipid Research, 2015

Supplementary key words selenocysteine insertion sequence-binding protein 2 • selenoprotein • ant... more Supplementary key words selenocysteine insertion sequence-binding protein 2 • selenoprotein • antioxidative defense • free radical • cholesterol • oxysterol • oxidized lipids Selenium is primarily incorporated into proteins in the form of selenocysteine (Sec). Sec is the 21st amino acid to be translated and is encoded by the UGA codon (1). The biological role of selenium is mediated through Sec-containing proteins, termed selenoproteins (2, 3). A stemloop RNA structure, called the Sec insertion sequence (SECIS), is located in the 3 ′-untranslated region of selenoprotein mRNAs and is essential for the incorporation of Sec during the biosynthesis of selenoproteins (4). The SECIS interacts with a multi-protein complex, including SECIS-binding protein 2 (SBP2), which promotes Sec incorporation into growing polypeptides through selenocysteyl-transfer RNA at the UGA codon (4, 5). Although UGA primarily encodes a stop codon, this protein complex ensures that UGA is translated to Sec. The interaction between the SECIS element and SBP2 is particularly important for this translational system. Thus, defects in SBP2 Abstract Selenocysteine (Sec) insertion sequence-binding protein 2 (SBP2) is essential for the biosynthesis of Sec-containing proteins, termed selenoproteins. Subjects with mutations in the SBP2 gene have decreased levels of several selenoproteins, resulting in a complex phenotype. Selenoproteins play a signifi cant role in antioxidative defense, and defi ciencies in these proteins can lead to increased oxidative stress. However, lipid peroxidation and the effects of antioxidants in subjects with SBP2 gene mutations have not been studied. In the present study, we evaluated the lipid peroxidation products in the blood of a subject (the proband) with mutations in the SBP2 gene. We found that the proband had higher levels of free radical-mediated lipid peroxidation products, such as 7 ␤-hydroxycholesterol, than the control subjects. Treatment of the proband with vitamin E (␣-tocopherol acetate, 100 mg/day), a lipid-soluble antioxidant, for 2 years reduced lipid peroxidation product levels to those of control subjects. Withdrawal of vitamin E treatment for 7 months resulted in an increase in lipid peroxidation products. Collectively, these results clearly indicate that free radical-mediated oxidative stress is increased in the subject with SBP2 gene mutations and that vitamin E treatment effectively inhibits the generation of lipid peroxidation products.-Saito, Y.

BPB Reports

We've previously shown that high levels of selenoprotein P (SeP), a major selenoprotein in plasma... more We've previously shown that high levels of selenoprotein P (SeP), a major selenoprotein in plasma, can be a risk factor of type 2 diabetes. It was also thought that inhibition of insulin secretion caused by over-supplementation of selenium by SeP to pancreatic β cells contributed to the progress of diabetes. On the other hand, methylmercury, which is an environmental pollutant, is known to cancel the action of selenium via the covalent modification. Therefore, we thought that the interaction between selenium and methylmercury could be associated with the pathogenesis of diabetes. To address the hypothesis, MIN6 cells, a mouse pancreatic β-cell line, were treated with selenocystine (as a selenium donner) and methylmercury then examined insulin release from the cells. Selenocystine (400-1200 nM), which corresponds to the concentration of selenium in SeP of diabetic patients, shows cytotoxicity and inhibited glucose-driven insulin secretion. Methylmercury rescued the cytotoxicity that induced by selenocystine, however it affected the insulin secretion that is depressed by selenocystine at little intense. These data indicate that the mechanisms underlying inhibition of insulin secretion by selenocystine are independent of cytotoxicity, and methylmercury cannot be expected to restore insulin secretion or suppress diabetes as selenium neutlizer.

Chemical Research in Toxicology, 2009

Many investigations about the cellular response by metal oxide nanoparticles in vitro have been r... more Many investigations about the cellular response by metal oxide nanoparticles in vitro have been reported. However, the influence of the adsorption ability of metal oxide nanoparticles toward cells is unknown. The aim of this study is to understand the influence of adsorption by metal oxide nanoparticles on the cell viability in vitro. The adsorption abilities of six kinds of metal oxide nanoparticles, namely, NiO, ZnO, TiO 2 , CeO 2 , SiO 2 , and Fe 2 O 3 , to Dulbecco's modified Eagle's medium supplemented with a 10% fetal bovine serum (DMEM-FBS) component such as serum proteins and Ca 2+ were estimated. All of the metal oxide nanoparticles adsorbed proteins and Ca 2+ in the DMEM-FBS; in particular, TiO 2 , CeO 2 , and ZnO showed strong adsorption abilities. Furthermore, the influence of the depletion of medium components by adsorption to metal oxide nanoparticles on cell viability and proliferation was examined. The particles were removed from the dispersion by centrifugation, and the supernatant was applied to the cells. Both the cell viability and the proliferation of human keratinocyte HaCaT cells and human lung carcinoma A549 cells were affected by the supernatant. In particular, cell proliferation was strongly inhibited by the supernatant of TiO 2 and CeO 2 dispersions. The supernatant showed depletion of serum proteins and Ca 2+ by adsorption to metal oxide nanoparticles. When the adsorption effect was blocked by the pretreatment of particles with FBS, the inhibitory effect was lost. However, in NiO and ZnO, which showed ion release, a decrease of inhibitory effect by pretreatment was not shown. Furthermore, the association of the primary particle size and adsorption ability was examined in TiO 2. The adsorption ability of TiO 2 depended on the primary particle size. The TiO 2 nanoparticles were size dependently absorbed with proteins and Ca 2+ , thereby inducing cytotoxicity. In conclusion, the adsorption ability of metal oxide nanoparticles is an important factor for the estimation of cytotoxicity in vitro for low-toxicity materials.

Redox Experimental Medicine

Graphical abstract The essential trace element selenium plays a significant role in redox homeost... more Graphical abstract The essential trace element selenium plays a significant role in redox homeostasis in the human body. Selenium is very reactive and has a potent toxicity; however, the living body cleverly utilizes its reactivity for redox reactions. The biological function of selenium is mainly mediated by selenoproteins, which contain selenocysteine, a cysteine analogue that possesses selenium instead of sulphur. Twenty-five types of human selenoproteins have been identified, including glutathione peroxidase (GPX; for the reduction of hydrogen peroxide and lipid hydroperoxide) and thioredoxin reductase (for redox regulation). Selenoprotein P (SELENOP), which is a major selenoprotein in the plasma, is mainly synthesized in the liver and secreted into the plasma. As a multifunctional protein with selenium-transporting activity, GPX-like activity, and metal-binding properties, SELENOP plays a vital role in selenium metabolism and redox regulation. This review focuses on the relatio...

Scientific reports, Jan 13, 2018

DJ-1 plays an important role in antioxidant defenses, and a reactive cysteine at position 106 (Cy... more DJ-1 plays an important role in antioxidant defenses, and a reactive cysteine at position 106 (Cys106) of DJ-1, a critical residue of its biological function, is oxidized under oxidative stress. DJ-1 oxidation has been reported in patients with Parkinson's disease (PD), but the relationship between DJ-1 oxidation and PD is still unclear. In the present study using specific antibody for Cys106-oxidized DJ-1 (oxDJ-1), we analyzed oxDJ-1 levels in the brain and peripheral tissues in young and aged mice and in a mouse model of PD induced using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). OxDJ-1 levels in the brain, heart, and skeletal muscle were high compared with other tissues. In the brain, oxDJ-1 was detected in PD-related brain sites such as the substantia nigra (SN) of the midbrain, olfactory bulb (OB), and striatum. In aged wild-type mice, oxDJ-1 levels in the OB, striatum, and heart tended to decrease, while those in the skeletal muscle increased significantly. Expre...

Nature communications, Nov 21, 2017

Selenoprotein P (SeP) functions as a selenium (Se)-supply protein. SeP is identified as a hepatok... more Selenoprotein P (SeP) functions as a selenium (Se)-supply protein. SeP is identified as a hepatokine, promoting insulin resistance in type 2 diabetes. Thus, the suppression of Se-supply activity of SeP might improve glucose metabolism. Here, we develop an anti-human SeP monoclonal antibody AE2 as with neutralizing activity against SeP. Administration of AE2 to mice significantly improves glucose intolerance and insulin resistance that are induced by human SeP administration. Furthermore, excess SeP administration significantly decreases pancreas insulin levels and high glucose-induced insulin secretion, which are improved by AE2 administration. Epitope mapping reveals that AE2 recognizes a region of human SeP adjacent to the first histidine-rich region (FHR). A polyclonal antibody against the mouse SeP FHR improves glucose intolerance and insulin secretion in a mouse model of diabetes. This report describes a novel molecular strategy for the development of type 2 diabetes therapeuti...

Genes to cells : devoted to molecular & cellular mechanisms, 2018

Chronic myeloid leukemia (CML) is caused by the chimeric protein p210 BCR-ABL encoded by a gene o... more Chronic myeloid leukemia (CML) is caused by the chimeric protein p210 BCR-ABL encoded by a gene on the Philadelphia chromosome. Although the kinase domain of p210 BCR-ABL is an active driver of CML, the pathological role of its pleckstrin homology (PH) domain remains unclear. Here, we carried out phospholipid vesicle-binding assays to show that cardiolipin (CL), a characteristic mitochondrial phospholipid, is a unique ligand of the PH domain. Arg726, a basic amino acid in the ligand-binding region, was crucial for ligand recognition. A subset of wild-type p210 BCR-ABL that was transiently expressed in HEK293 cells was dramatically translocated from the cytosol to mitochondria in response to carbonyl cyanide m-chlorophenylhydrazone (CCCP) treatment, which induces mitochondrial depolarization and subsequent externalization of CL to the organelle's outer membrane, whereas an R726A mutant of the protein was not translocated. Furthermore, only wild-type p210 BCR-ABL, but not the R726...

PloS one, 2016

Oxidative stress is correlated with the incidence of several diseases such as atherosclerosis and... more Oxidative stress is correlated with the incidence of several diseases such as atherosclerosis and cancer, and oxidized biomolecules have been determined as biomarkers of oxidative stress; however, the detailed molecular relationship between generated oxidation products and the promotion of diseases has not been fully elucidated. In the present study, to clarify the role of serum oxidation products in vessel cell proliferation, which is related to the incidence of atherosclerosis and cancer, the major vessel cell proliferator in oxidized human serum was investigated. Oxidized human serum was prepared by free radical exposure, separated using gel chromatography, and then each fraction was added to several kinds of vessel cells including endothelial cells and smooth muscle cells. It was found that a high molecular weight fraction in oxidized human serum specifically induced vessel cell proliferation. Oxidized lipids were contained in this high molecular weight fraction, while cell prol...

Free Radical Biol Med, 2011

JOURNAL OF HEALTH SCIENCE, 2000

Selenoprotein P (SeP: the "P" denotes its presence in plasma) is the major selenoprotein in plasm... more Selenoprotein P (SeP: the "P" denotes its presence in plasma) is the major selenoprotein in plasma. All selenoproteins so far reported contain one atom of selenium (Se) as selenocysteine per molecule except SeP, which is thought to contain ten atoms of Se as selenocysteine per molecule. SeP contains 50% of the total Se in plasma. The function of SeP is currently unknown, although several indirect lines of evidence suggest that SeP is a free radical scavenger or Se transporter. Recently, we reported that SeP is capable of reducing phospholipid hydroperoxide in the presence of glutathione, and characterized the enzymatic nature of SeP. SeP is also reported to function as a peroxynitrite scavenger or cell survival factor in primary culture of neurons. In this minireview, we discuss the relationship between the structure and function of SeP.

Free Radical Biology and Medicine, 2010

Biological & Pharmaceutical Bulletin, 2003

Toxics

Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress r... more Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress response has rarely been examined. We previously reported that knockdown of HOXB13 reduces the cytotoxicity caused by various oxidative stress inducers. Here, we studied the role of HOXB13 in cytotoxicity caused by hydrogen peroxide in human lung epithelial A549 cells. The knockdown of HOXB13 reduced hydrogen peroxide-induced cytotoxicity; however, this phenomenon was largely absent in the presence of antioxidants (Trolox or N-acetyl cysteine (NAC)). This suggests that HOXB13 may be involved in the cytotoxicity caused by hydrogen peroxide via the production of reactive oxygen species (ROS). Hydrogen peroxide also increased both the mRNA and protein levels of HOXB13. However, these increases were rarely observed in the presence of a transcriptional inhibitor, which suggests that hydrogen peroxide increases protein levels via increased transcription of HOXB13. Furthermore, cell death occurr...

Toxics, 2020

Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress r... more Although homeobox protein B13 (HOXB13) is an oncogenic transcription factor, its role in stress response has rarely been examined. We previously reported that knockdown of HOXB13 reduces the cytotoxicity caused by various oxidative stress inducers. Here, we studied the role of HOXB13 in cytotoxicity caused by hydrogen peroxide in human lung epithelial A549 cells. The knockdown of HOXB13 reduced hydrogen peroxide-induced cytotoxicity; however, this phenomenon was largely absent in the presence of antioxidants (Trolox or N-acetyl cysteine (NAC)). This suggests that HOXB13 may be involved in the cytotoxicity caused by hydrogen peroxide via the production of reactive oxygen species (ROS). Hydrogen peroxide also increased both the mRNA and protein levels of HOXB13. However, these increases were rarely observed in the presence of a transcriptional inhibitor, which suggests that hydrogen peroxide increases protein levels via increased transcription of HOXB13. Furthermore, cell death occurr...

Nucleic Acids Research

Selenoprotein P (SELENOP) is a major plasma selenoprotein that contains 10 Sec residues, which is... more Selenoprotein P (SELENOP) is a major plasma selenoprotein that contains 10 Sec residues, which is encoded by the UGA stop codon. The mRNA for SELENOP has the unique property of containing two Sec insertion sequence (SECIS) elements, which is located in the 3′ untranslated region (3′UTR). Here, we coincidentally identified a novel gene, CCDC152, by sequence analysis. This gene was located in the antisense region of the SELENOP gene, including the 3′UTR region in the genome. We demonstrated that this novel gene functioned as a long non-coding RNA (lncRNA) that decreased SELENOP protein levels via translational rather than transcriptional, regulation. We found that the CCDC152 RNA interacted specifically and directly with the SELENOP mRNA and inhibited its binding to the SECIS-binding protein 2, resulting in the decrease of ribosome binding. We termed this novel gene product lncRNA inhibitor of SELENOP translation (L-IST). Finally, we found that epigallocatechin gallate upregulated L-I...