Faculty Profiles - TOYOKUNI Shinya

Papers - TOYOKUNI Shinya

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Comparison between high-performance liquid chromatography and enzyme-linked immunosorbent assay for the determination of 8-hydroxy-2'-deoxyguanosine in human urine. International journal

Kayoko Shimoi, Hiroshi Kasai, Naoko Yokota, Shinya Toyokuni, Naohide Kinae

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology Vol. 11 ( 8 ) page： 767 - 70 2002.8

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

8-Hydroxy-2'-deoxyguanosine (8-OH-dG), which has been regarded as a potential marker of oxidative DNA damage induced by reactive oxygen species, was measured in human urine by a commercial ELISA using a monoclonal antibody N45.1 and by high-performance liquid chromatography (HPLC) coupled to an electrochemical detector (HPLC-ECD) to evaluate whether the ELISA system is applicable to human monitoring studies. The urine samples were collected from 120 healthy men ages 18-58 in a steel-manufacturing company. A good correlation (r = 0.833; P < 0.0001) was observed between the two methods on HPLC-purified 8-OH-dG fractions from 23 urine samples. The mean value (+/-SD) of 8-OH-dG (microg/g creatinine) was 5.47 (+/-2.97) by HPLC-ECD assay and 5.50 (+/-2.36) by ELISA. However, the correlation (r) between the two methods on 120 original urine samples was 0.460 [P < 0.001; mean value (+/-SD) of 8-OH-dG (microg/g creatinine) was 4.46 (+/-2.03) by the HPLC assay and 9.33 (+/-3.23) by ELISA]. ELISA estimates were about 2-fold higher than the HPLC estimates on original urine. For an unknown reason, 10% of the urine samples showed more than a 4-fold increase in value by ELISA. It is suggested that the ELISA system is applicable for comparative human monitoring studies. Prepurification of 'samples is required to determine the absolute value of 8-OH-dG in individual urine samples by ELISA.

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Comparison between high-performance liquid chromatography and enzyme-linked immunosorbent assay for the determination of 8-hydroxy-2'-deoxyguanosine in human urine.

Shimoi K, Kasai H, Yokota N, Toyokuni S, Kinae N

Vitamin D receptor activity and prevention of colonic hyperproliferation and oxidative stress Reviewed International journal

Kallay E, Bareis P, Bajna E, Kriwanek S, Bonner E, Toyokuni S, Cross HS

FOOD AND CHEMICAL TOXICOLOGY Vol. 40 ( 8 ) page： 1191 - 1196 2002.8

Erratum: Protective effect of colored rice over white rice on fenton reaction-based renal lipid peroxidation in rats (Free Radical Research vol. 36 (5) (583-592)) Reviewed International journal

Toyokuni S., Itani T., Morimitsu Y., Okada K., Ozeki M., Kondo S., Uchida K., Osawa T., Hiai H., Tashiro T.

Free Radical Research Vol. 36 ( 8 ) 2002.8

Inhibition of gastric inhibitory polypeptide signaling prevents obesity. Reviewed International journal

Kazumasa Miyawaki, Yuichiro Yamada, Nobuhiro Ban, Yu Ihara, Katsushi Tsukiyama, Heying Zhou, Shimpei Fujimoto, Akira Oku, Kinsuke Tsuda, Shinya Toyokuni, Hiroshi Hiai, Wataru Mizunoya, Tohru Fushiki, Jens Juul Holst, Mitsuhiro Makino, Akira Tashita, Yukari Kobara, Yoshiharu Tsubamoto, Takayoshi Jinnouchi, Takahito Jomori, Yutaka Seino

Nature medicine Vol. 8 ( 7 ) page： 738 - 42 2002.7

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

Secretion of gastric inhibitory polypeptide (GIP), a duodenal hormone, is primarily induced by absorption of ingested fat. Here we describe a novel pathway of obesity promotion via GIP. Wild-type mice fed a high-fat diet exhibited both hypersecretion of GIP and extreme visceral and subcutaneous fat deposition with insulin resistance. In contrast, mice lacking the GIP receptor (Gipr(-/-)) fed a high-fat diet were clearly protected from both the obesity and the insulin resistance. Moreover, double-homozygous mice (Gipr(-/-), Lep(ob)/Lep(ob)) generated by crossbreeding Gipr(-/-) and obese ob/ob (Lep(ob)/Lep(ob)) mice gained less weight and had lower adiposity than Lep(ob)/Lep(ob) mice. The Gipr(-/-) mice had a lower respiratory quotient and used fat as the preferred energy substrate, and were thus resistant to obesity. Therefore, GIP directly links overnutrition to obesity and it is a potential target for anti-obesity drugs.

DOI： 10.1038/nm727

Vitamin D receptor activity and prevention of colonic hyperproliferation and oxidative stress

Kállay E., Bareis P., Bajna E., Kriwanek S., Bonner E., Toyokuni S., Cross H.

Food and Chemical Toxicology Vol. 40 ( 8 ) page： 1191 - 1196 2002.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Food and Chemical Toxicology

Unimpaired vitamin D action has been implicated in human cancer prevention. We have previously demonstrated the effectiveness of 1α-dihydroxyvitamin D3 (1,25-D3) to reduce proliferation and increase differentiation in human colon cancer cells. The aim of this study was to investigate, on the one hand, expression of the vitamin D receptor (VDR) and of 25-hydroxyvitamin D3-1α-hydroxylase (1α-hydroxylase) in human normal and malignant colonic tissue and, on the other hand, to determine consequences of reduced or lacking VDR action in a VDR knockout mouse model. In low-grade malignancies of the human colon we found increased VDR and 1α-hydroxylase mRNA expression. However, in late-stage high-grade tumors the vitamin D system is severely compromised. In the mouse colon we found an inverse relationship between VDR levels and proliferation in colon descendens, a tissue known to be specifically affected by nutrients during carcinogenesis. Expression of 8-hydroxy-2′-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, was significantly augmented with complete loss of VDR. These data suggest that genomic 1,25-D3 action is necessary to protect against nutrition-linked hyperproliferation and oxidative DNA damage. © 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0278-6915(02)00030-3

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Carvedilol decreases elevated oxidative stress in human failing myocardium Reviewed International journal Open Access

Nakamura, K; Kusano, K; Nakamura, Y; Kakishita, M; Ohta, K; Nagase, S; Yamamoto, M; Miyaji, K; Saito, H; Morita, H; Emori, T; Matsubara, H; Toyokuni, S; Ohe, T

CIRCULATION Vol. 105 ( 24 ) page： 2867 - 2871 2002.6

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

Background - Oxidative stress has been implicated in the pathogenesis of heart failure. However, direct evidence of oxidative stress generation in the human failing myocardium has not been obtained. Furthermore, the effect of carvedilol, a vasodilating β-blocker with antioxidant activity, on oxidative stress in human failing hearts has not been assessed. This study was therefore designed to determine whether levels of lipid peroxides are elevated in myocardia of patients with dilated cardiomyopathy (DCM) and whether carvedilol reduces the lipid peroxidation level. Methods and Results - Endomyocardial biopsy samples obtained from 23 patients with DCM and 13 control subjects with normal cardiac function were studied immunohistochemically for the expression of 4-hydroxy-2-nonenal (HNE)-modified protein, which is a major lipid peroxidation product. Expression of HNE-modified protein was found in all myocardial biopsy samples from patients with DCM. Expression was distinct in the cytosol of cardiac myocytes. Myocardial HNE-modified protein levels in patients with DCM were significantly increased compared with the levels in control subjects (P<0.0001). Endomyocardial biopsy samples from 11 patients with DCM were examined before and after treatment (mean, 9±4 months) with carvedilol (5 to 30 mg/d; mean dosage, 22±8 mg/d). After treatment with carvedilol, myocardial HNE-modified protein levels decreased by 40% (P<0.005) along with amelioration of heart failure. Conclusions - Oxidative stress is elevated in myocardia of patients with heart failure. Administration of carvedilol resulted in a decrease in the oxidative stress level together with amelioration of cardiac function.

DOI： 10.1161/01.CIR.0000018605.14470.DD

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Peroxynitrite-mediated stress is associated with proliferation of human metastatic colorectal carcinoma in the liver

Kondo S, Toyokuni S, Tsuruyama T, Ozeki M, Tachibana T, Echizenya M, Hiai H, Onodera H, Imamura M

CANCER LETTERS Vol. 179 ( 1 ) page： 87 - 93 2002.5

Peroxynitrite-mediated stress is associated with proliferation of human metastatic colorectal carcinoma in the liver.

Kondo S, Toyokuni S, Tsuruyama T, Ozeki M, Tachibana T, Echizenya M, Hiai H, Onodera H, Imamura M

Cancer letters Vol. 179 ( 1 ) page： 87 - 93 2002.5

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

3-Nitrotyrosine (3-NT), a product of peroxynitrite reaction, is abundantly observed in hepatocytes adjacent to human metastatic colorectal carcinoma. To elucidate its biological significance, we undertook to identify nitric oxide (NO)-producing cells and apoptosis under oxidative stress. We observed strong inducible NO-synthase (iNOS) immunoreactivity in the hepatocytes adjacent to metastatic tumor, revealing an identical pattern to 3-NT immunostaining. Furthermore, intense 3-NT immunostaining of hepatocytes was associated with apoptosis whereas carcinoma cells near those hepatocytes presented high proliferating-cell nuclear antigen. Our results suggest that contact of metastatic tumor induces apoptosis in adjacent hepatocytes through peroxynitrite, thus permitting the proliferation of cancer cells. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

DOI： 10.1016/s0304-3835(01)00859-x

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Peroxynitrite-mediated stress is associated with proliferation of human metastatic colorectal carcinoma in the liver. International journal

Shohei Kondo, Shinya Toyokuni, Tatsuaki Tsuruyama, Munetaka Ozeki, Tsuyoshi Tachibana, Michiko Echizenya, Hiroshi Hiai, Hisashi Onodera, Masayuki Imamura

Cancer letters Vol. 179 ( 1 ) page： 87 - 93 2002.5

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

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Isolation and characterization of annexin 2 pseudogene in Rattus norvegicus

Ozeki M, Hoshino S, Hiai H, Toyokuni S

GENE Vol. 289 ( 1-2 ) page： 185 - 190 2002.5

Isolation and characterization of annexin 2 pseudogene in Rattus norvegicus.

Ozeki M, Hoshino S, Hiai H, Toyokuni S

Gene Vol. 289 ( 1-2 ) page： 185 - 90 2002.5

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

Annexin 2 is a calcium-regulated, phospholipid-binding protein present in endothelial cells, macrophages and some tumor cells. Annexin 2 is a substrate for a variety of protein kinases, and plays roles in the regulation of endocytosis, exocytosis and thrombolysis. We have determined the nucleotide sequence of a rat genomic DNA fragment that hybridized to a rat annexin 2 DNA complementary to RNA (cDNA) probe. Sequence analysis revealed that it was an intronless rat annexin 2, consisting of a start-to-stop-codon-length copy of the processed transcript. This pseudogene contained 33 point mutations and two deletion sites in the coding region as compared with the cDNA, and thus displayed typical features of a retroposon. Transitions were more frequent than transversions, and the most frequent type of mutation was G to A transition. We isolated a phage clone that contained a functional rat annexin 2 genomic fragment including coding exons 3 and 4. Polymerase chain reaction and subsequent sequence analysis revealed an intron of approximately 4 kbp at the same site as in humans and mice. Whereas the annexin 2 gene or its cDNA homologues have been detected in various species from Xenopus to humans, its pseudogene has been reported only in humans. In the present study, we demonstrated the presence of an annexin 2 pseudogene in rats. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/s0378-1119(02)00549-8

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Isolation and characterization of annexin 2 pseudogene in Rattus norvegicus. International journal

Munetaka Ozeki, Shinsuke Hoshino, Hiroshi Hiai, Shinya Toyokuni

Gene Vol. 289 ( 1-2 ) page： 185 - 90 2002.5

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

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Hepatocyte nuclear factor-1 alpha recruits the transcriptional co-activator p300 on the GLUT2 gene promoter

Ban N, Yamada Y, Someya Y, Miyawaki K, Ihara Y, Hosokawa M, Toyokuni S, Tsuda K, Seino Y

DIABETES Vol. 51 ( 5 ) page： 1409 - 1418 2002.5

Inhibitory effect of a novel water-soluble vitamin E derivative on atherosclerosis in rabbits

Yoshida N, Murase H, Kunieda T, Toyokuni S, Tanaka T, Terao J, Naito Y, Tanigawa T, Yoshikawa T

ATHEROSCLEROSIS Vol. 162 ( 1 ) page： 111 - 117 2002.5

Protective effect of colored rice over white rice on Fenton reaction-based renal lipid peroxidation in rats. International journal

Shinya Toyokuni, Tomio Itani, Yasujiro Morimitsu, Kunihiko Okada, Munetaka Ozeki, Shohei Kondo, Koji Uchida, Toshihiko Osawa, Hiroshi Hiai, Toru Tashiro

Free radical research Vol. 36 ( 5 ) page： 583 - 92 2002.5

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

Rice has been one of the most important grains. While polished white rice is favored, colored strains of rice, red, or black, have been maintained for religious purposes in Japan. We studied whether feeding of unpolished colored rice instead of white rice ameliorates oxidative renal tubular damage in rats induced by ferric nitrilotriacetate. Whereas renal lipid peroxidation was exacerbated in white rice-fed group in comparison with standard chow group, this exacerbation was not observed in red or black rice-fed groups. These changes were dependent on the proportion of colored rice to standard chow in the diet. Cyanidin 3-O-beta-D-glucoside was detectable neither in the serum nor kidney after one week of colored rice diet, but serum protocatechuic acid was significantly increased after black rice diet. There was a generalized decrease in the renal glutathione peroxidase activity in rice diet groups. Renal enzymatic activities of superoxide dismutase, glutathione S-transferase and NAD(P)H quinone reductase were not associated with the levels of lipid peroxidation. However, renal catalase activity was significantly increased in black rice-fed groups. These may partly explain the antioxidative effect. Furthermore, colored strains of rice are rich in proteins. Thus, our data warrants further investigation of the antioxidative effect of colored rice.

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Protective effect of colored rice over white rice on Fenton reaction-based renal lipid peroxidation in rats

Toyokuni S, Itani T, Morimitsu Y, Okada K, Ozeki M, Kondo S, Uchida K, Osawa T, Hiai H, Tashiro T

FREE RADICAL RESEARCH Vol. 36 ( 5 ) page： 583 - 592 2002.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Free Radical Research

Rice has been one of the most important grains. While polished white rice is favored, colored strains of rice, red, or black, have been maintained for religious purposes in Japan. We studied whether feeding of unpolished colored rice instead of white rice ameliorates oxidative renal tubular damage in rats induced by ferric nitrilotriacetate. Whereas renal lipid peroxidation was exacerbated in white rice-fed group in comparison with standard chow group, this exacerbation was not observed in red or black rice-fed groups. These changes were dependent on the proportion of colored rice to standard chow in the diet. Cyanidin 3-O-β-D-glucoside was detectable neither in the serum nor kidney after one week of colored rice diet, but serum protocatechuic acid was significantly increased after black rice diet. There was a generalized decrease in the renal glutathione peroxidase activity in rice diet groups. Renal enzymatic activities of superoxide dismutase, glutathione S-transferase and NAD(P)H quinone reductase were not associated with the levels of lipid peroxidation. However, renal catalase activity was significantly increased in black rice-fed groups. These may partly explain the antioxidative effect. Furthermore, colored strains of rice are rich in proteins. Thus, our data warrants further investigation of the antioxidative effect of colored rice.

DOI： 10.1080/10715760290025960

Web of Science

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PubMed

Inhibitory effect of a novel water-soluble vitamin E derivative on atherosclerosis in rabbits.

Yoshida N, Murase H, Kunieda T, Toyokuni S, Tanaka T, Terao J, Naito Y, Tanigawa T, Yoshikawa T

Atherosclerosis Vol. 162 ( 1 ) page： 111 - 7 2002.5

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

A novel vitamin E derivative that is freely soluble in water, 2-(α-D-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol (TMG), was evaluated for ability to inhibit development of atherosclerosis in Watanabe heritable hyperlipidemic (WHHL) rabbits or cholesterol-loaded New Zealand White rabbits. Although TMG rapidly entered the circulation blood after oral administration, the blood TMG concentration remained low, while neither TMG nor its metabolites appeared in the low-density lipoprotein (LDL) fraction. TMG did not decrease serum total cholesterol and the various lipoprotein-associated cholesterol fractions (very LDL-, or high-density lipoprotein- (HDL) cholesterol). TMG reduced the serum concentration of thiobarbituric acid-reactive substances (TBARS; an index of lipid peroxidation) in cholesterol-loaded rabbits but not WHHL rabbits. Nonetheless, TMG inhibited aortic atherosclerosis as effectively as probucol in both models. Our results indicate that TMG opposes progression of atherosclerosis not only by preventing oxidation of LDL, but also by presently unknown mechanisms. Even an antioxidant with no uptake by LDL apparently can inhibit development of atherosclerosis despite a very low serum concentration. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

DOI： 10.1016/s0021-9150(01)00702-x

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Hepatocyte nuclear factor-1alpha recruits the transcriptional co-activator p300 on the GLUT2 gene promoter. International journal

Nobuhiro Ban, Yuichiro Yamada, Yoshimichi Someya, Kazumasa Miyawaki, Yu Ihara, Masaya Hosokawa, Shinya Toyokuni, Kinsuke Tsuda, Yutaka Seino

Diabetes Vol. 51 ( 5 ) page： 1409 - 18 2002.5

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

Mutations in the hepatocyte nuclear factor (HNF)-1alpha gene have been linked to subtype 3 of maturity-onset diabetes of the young (MODY), a disease characterized by a primary defect in insulin secretion. Here we show that the human GLUT2 gene is closely regulated by HNF-1alpha via sequences downstream of the transcriptional start site by interaction with transcriptional co-activator p300. The promoter region of the human GLUT2 gene was subcloned into luciferase expression plasmids that were transfected together with HNF-1alpha expression plasmid into a pancreatic beta-cell line, HIT-T15, to evaluate transcriptional activities. HNF-1alpha enhanced human GLUT2 promoter activity sixfold. Site-direct mutagenesis and footprint analyses showed that the HNF-1alpha binding site (+200 to +218) is critical in human GLUT2 gene expression. Furthermore, mammalian two-hybrid and immunoprecipitation studies revealed the transactivation domain of HNF-1alpha (amino acids 391-540) to interact with both the NH(2)-terminal region (amino acids 180-662) and the COOH-terminal region (amino acids 1,818-2,079) of p300. These findings demonstrated that HNF-1alpha binds to the 5'-untranslated region of GLUT2 and that p300 acts as a transcriptional co-activator for HNF-1alpha. In addition, these results provided new insight into the regulatory function of HNF-1alpha by suggesting a molecular basis for human GLUT2 gene expression.

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Hepatocyte nuclear factor-1alpha recruits the transcriptional co-activator p300 on the GLUT2 gene promoter.

Ban N, Yamada Y, Someya Y, Miyawaki K, Ihara Y, Hosokawa M, Toyokuni S, Tsuda K, Seino Y

Diabetes Vol. 51 ( 5 ) page： 1409 - 18 2002.5

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

Mutations in the hepatocyte nuclear factor (HNF)-1α gene have been linked to subtype 3 of maturity-onset diabetes of the young (MODY), a disease characterized by a primary defect in insulin secretion. Here we show that the human GLUT2 gene is closely regulated by HNF-1α via sequences downstream of the transcriptional start site by interaction with transcriptional co-activator p300. The promoter region of the human GLUT2 gene was subcloned into luciferase expression plasmids that were transfected together with HNF-1α expression plasmid into a pancreatic β-cell line, HIT-T15, to evaluate transcriptional activities. HNF-1α enhanced human GLUT2 promoter activity sixfold. Site-direct mutagenesis and footprint analyses showed that the HNF-1α binding site (+200 to +218) is critical in human GLUT2 gene expression. Furthermore, mammalian two-hybrid and immunoprecipitation studies revealed the transactivation domain of HNF-1α (amino acids 391-540) to interact with both the NH2-terminal region (amino acids 180-662) and the COOH-terminal region (amino acids 1,818-2,079) of p300. These findings demonstrated that HNF-1α binds to the 5′-untranslated region of GLUT2 and that p300 acts as a transcriptional co-activator for HNF-1α. In addition, these results provided new insight into the regulatory function of HNF-1α by suggesting a molecular basis for human GLUT2 gene expression.

DOI： 10.2337/diabetes.51.5.1409

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Papers - TOYOKUNI Shinya