Seiichiro Himeno

Tokushima Bunri University, Tokusima, Tokushima, Japan

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Publications (90)246.2 Total impact

  • Daigo Sumi · Masashi Asao · Hideta Okada · Kuniko Yogi · Hideki Miyataka · Seiichiro Himeno ·
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    ABSTRACT: Chronic arsenic exposure causes cutaneous diseases such as hyperkeratosis and skin cancer. However, little information has been available regarding the molecular mechanisms underlying these symptoms. Because extracellular ATP and interleukin-6 (IL-6) are involved in pathological aspects of cutaneous diseases, we examined whether sodium arsenite (As(III)) affects ATP-induced IL-6 production in human epidermal keratinocyte HaCaT cells. The results showed that the addition of As(III) into the medium of HaCaT cells dose dependently increased the production of IL-6 induced by extracellular ATP, although As(III) alone had no effect on IL-6 production. To elucidate the mechanism of the synergistic effect of As(III) on IL-6 production by extracellular ATP, we next examined the phosphorylation of p38, ERK and epidermal growth factor receptor (EGFR), since we found that these signaling molecules were stimulated by exposure to extracellular ATP. The results indicated that ATP-induced phosphorylation of p38, ERK and EGFR was synergistically enhanced by co-exposure to As(III). To clarify the mechanisms underlying the enhanced phosphorylation of p38, ERK and EGFR by As(III), we explored two possible mechanisms: the inhibition of extracellular ATP degradation and the inhibition of protein tyrosine phosphatases (PTPs) activity by As(III). The degradation of extracellular ATP was not changed by As(III), whereas the activity of PTPs was significantly inhibited by As(III). Our results suggest that As(III) augments ATP-induced IL-6 production in HaCaT cells through enhanced phosphorylation of the EGFR and p38/ERK pathways, which is associated with the inhibition of PTPs activity.
    Archives of Toxicology 06/2015; DOI:10.1007/s00204-015-1553-2 · 5.98 Impact Factor
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    ABSTRACT: Arsenic exposure is associated with cancer and vascular diseases. Angiogenesis is an important step for the pathological development of cancer and vascular diseases. Vascular endothelial growth factor (VEGF) is a specific marker for angiogenesis. However, human study showing the association between arsenic exposure and serum VEGF levels has not yet been documented. This study was aimed to investigate the association between arsenic exposure and serum VEGF levels in the arsenic-endemic individuals in Bangladesh. A total of 260 individuals were recruited for this study. Arsenic exposure levels were measured by ICP-MS and VEGF levels were quantified using VEGF immunoassay kit. The study subjects were stratified into tertile (low, medium and high) groups based on the arsenic in water, hair and nails. Serum VEGF levels were correlated with water (rs = 0.363, p < 0.001), hair (rs = 0.205, p < 0.01) and nail (rs = 0.190, p < 0.01) arsenic. Further, VEGF levels showed dose–response relationships with water, hair and nail arsenic. Mean VEGF levels in 6 10 lg L�1, 10.1–50 lg L�1 and >50 lg L�1 groups were 91.84, 129.54, and 169.86 pg mL�1, respectively, however, significant (p < 0.01) difference in VEGF levels was only found in >50 lg L�1 versus 610 lg L�1 groups. Significant associations of arsenic exposure with VEGF levels were found even after adjusting with relevant covariates. Therefore, these results provide evidence that arsenic exposure has a pro-angiogenic effect on humans, which may be implicated in arsenic-induced tumorigenesis and vascular diseases.
    Chemosphere 02/2015; 120:336–342. DOI:10.1016/j.chemosphere.2014.08.003 · 3.34 Impact Factor
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    ABSTRACT: Arsenic-induced toxicity appears to be dependent on the tissue- or cell-specific accumulation of this metalloid. An early study showed that arsenic was retained in the esophagus as well as the liver, kidney cortex and skin of marmosets after intraperitoneal administration of (74)As-arsenite. However, there is little available information regarding the distribution of arsenic in the esophagus. Here, we compared the retention of arsenic in the esophagus, liver, lung, kidney and heart in mice intraperitoneally administered 1 or 5 mg/kg sodium arsenite (As(III)) daily for 3 or 7 days. The results showed that the arsenic concentration was highest in the esophagus. We compared the mRNA levels of aquaglyceroporin (AQP) 3, AQP7 and AQP9, which are responsible for arsenic influx, and those of multidrug-resistance protein (MRP) 1 and MRP2, which are responsible for arsenic efflux. The levels of AQP3 mRNA in the esophagus were much higher than those in liver, lung and heart, while the mRNA levels of MRP2 were very low in the esophagus. In addition, we found extremely low expression of Nrf2 in the esophagus at the basal and under the activated conditions, which might have resulted in low levels of glutamyl-cysteine ligase catalytic and modulatory subunits, and subsequently in the low levels of glutathione. Thus, the highest retention of arsenic was detected in the esophagus after intraperitoneal administration of As(III) to mice, and this appeared to result from multiple factors, including high expression of AQP3, low expression of MRP2, low capacity of glutathione synthesis and low activation of Nrf2.
    Archive für Toxikologie 08/2014; 89(10). DOI:10.1007/s00204-014-1326-3 · 5.98 Impact Factor
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    ABSTRACT: The humoral immune response, also called the antibody-mediated immune response, is one of the main adaptive immune systems. The essential micronutrient zinc (Zn) is known to modulate adaptive immune responses, and dysregulated Zn homeostasis leads to immunodeficiency. However, the molecular mechanisms underlying this Zn-mediated modulation are largely unknown. Here, we show that the Zn transporter SLC39A10/ZIP10 plays an important role in B-cell antigen receptor (BCR) signal transduction. Zip10-deficiency in mature B cells attenuated both T-cell-dependent and -independent immune responses in vivo. The Zip10-deficient mature B cells proliferated poorly in response to BCR cross-linking, as a result of dysregulated BCR signaling. The perturbed signaling was found to be triggered by a reduction in CD45R phosphatase activity and consequent hyperactivation of LYN, an essential protein kinase in BCR signaling. Our data suggest that ZIP10 functions as a positive regulator of CD45R to modulate the BCR signal strength, thereby setting a threshold for BCR signaling in humoral immune responses.
    Proceedings of the National Academy of Sciences 07/2014; 111(32). DOI:10.1073/pnas.1323557111 · 9.67 Impact Factor
  • Hitomi Fujishiro · Mari Yoshida · Yuka Nakano · Seiichiro Himeno ·
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    ABSTRACT: Exposure to an excess amount of manganese causes neurological symptoms similar to Parkinson's disease. Zinc transporters such as Zrt, Irt-related protein 8 (ZIP8), and ZIP14 have been shown to have affinities for Mn(2+) as well as Zn(2+), but their roles in Mn(2+) uptake in neuronal cells remain unclear. Recent studies have shown that another zinc transporter ZnT10 may be involved in manganese excretion. Here we examined the roles of ZIP8, ZIP14, and ZnT10 in the transport of manganese in human SH-SY5Y neuroblastoma cells. The introduction of siRNA of ZIP14 decreased the uptake of Mn(2+), suggesting a significant role of ZIP14 in Mn(2+) uptake in SH-SY5Y cells. The pretreatment of SH-SY5Y cells with interleukin-6 (IL-6) markedly increased the accumulation of manganese to approx. 3-fold that of the control, which could be partly explained by the increased uptake of Mn(2+) due to the up-regulation of ZIP14 by IL-6. The treatment of SH-SH5Y cells with IL-6 clearly decreased both the mRNA and protein levels of ZnT10 with a concomitant decrease in the manganese excretion efficiency. These results suggest that both the up-regulation of ZIP14 and the down-regulation of ZnT10 by IL-6 might have enhanced the accumulation of manganese in SH-SY5Y cells. Our results provide new insight into the roles of zinc transporters in the aberrant manganese accumulation in neuronal cells, particularly in the presence of inflammatory cytokines such as IL-6.
    Metallomics 02/2014; 6(4). DOI:10.1039/c3mt00362k · 3.59 Impact Factor
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    ABSTRACT: Objectives: Previous investigations on chronic kidney disease of unknown etiology characterized by tubulointerstitial damages (CKDu) in the North Central Region (NCR) of Sri Lanka have supported the involvement of social, environmental and genetic factors in its pathogenesis. Methods: We conducted a social-environmental-and-genetic epidemiology study on a male population in NCR to investigate the genetic and environmental contributors. We recruited 311 case-series patients and 504 control candidates. Of the 504 control candidates, 218 (43%) were eliminated because of the presence of hypertension, proteinuria, high HbA1c, high serum creatinine or high alpha-1 microglobulin in urine. Results and discussion: None of 18 metals measured (μg//) in urine, including Cd, As and Pb, showed significantly higher concentrations in cases compared with controls. As speciation results showed that 75-80% of total urinary As was in the form of arsenobetaine, which is non-toxic to humans. None of the metal concentrations in drinking water samples exceeded guideline values. A genome-wide association study (GWAS) was conducted to determine the genetic contributors. The GWAS yielded a genome-wide significant association with CKDu for a single nucleotide polymorphism (SNP; rs6066043; p=5.23 × 10(-9) in quantitative trait locus analysis; p=3.73 × 10(-9) in dichotomous analysis) in SLC13A3 (sodium-dependent dicarboxylate transporter member 3). The population attributable fraction and odds ratio for this SNP were 50% and 2.13. Genetic susceptibility was identified as the major risk factor for CKDu. However, 43% of the apparently healthy male population suffers from non-communicable diseases, suggesting their possible influence on CKDu progression.
    Journal of Occupational Health 12/2013; 56(1). DOI:10.1539/joh.13-0172-OA · 1.11 Impact Factor
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    ABSTRACT: Exposure to arsenic and subsequent development of atherosclerosis has been suggested to be responsible for increased mortality. However, biochemical events for arsenic exposue-related atherosclerosis remain unknown. This study was aimed at investigating the associations of circulating biomarkers for atherosclerosis with arsenic exposure in the individuals exposed to arsenic in Bangladesh. A total of 324 study subjects from arsenicendemic and non-endemic areas in Bangladesh were recruited. Total cholesterol, LDL and HDL levels were lower in arsenic-endemic subjects than in non-endemic subjects. Oxidized LDL, CRP, ICAM- 1 and VCAM-1 levels were significantly higher in arsenic-endemic subjects than in non-endemic subjects. These circulating molecules also showed significant correlations with arsenic exposure metrics. Further, HDL, oxidized LDL and CRP showed dose-response relationships with arsenic exposure. All these associations may be the major features of arsenic-related atherosclerosis.
    Trace Element Research on Health and Diseases, KEIO PLAZA HOTEL TOKYO, TOKYO, JAPAN; 11/2013
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    ABSTRACT: Quantum dots (QDs) are semiconductor nanocrystals with unique optical properties. Different proteins or polymers are commonly bound to their surfaces to improve biocompatibility. However, such surface modifications may not provide sufficient protection from cytotoxicity due to photodegradation and oxidative degradation. In this study, the cytotoxic effects of QDs, CdTe, and CdSe/ZnS were investigated using cadmium-resistant cells. CdTe QDs significantly reduced cell viability, whereas, CdSe/ZnS treatment did not markedly decrease the cell number. CdTe QDs were cytotoxic in cadmium-resistant cells suggesting that internalized QDs degraded and cadmium ions contributed to the cytotoxic effects. CdTe QDs were consistently more cytotoxic than CdSe/ZnS QDs, but both QDs as well as cadmium ions activated heat shock protein 70B' promoter. QDs themselves are likely to contribute to HSP70B' promoter activation in cadmium-resistant cells, because CdSe/ZnS QDs do not release sufficient cadmium to activate this promoter.
    In Vitro Cellular & Developmental Biology - Animal 10/2013; 50(4). DOI:10.1007/s11626-013-9693-2 · 1.15 Impact Factor
  • Hitomi Fujishiro · Toshinao Ohashi · Miki Takuma · Seiichiro Himeno ·
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    ABSTRACT: Exposure to excess amounts of manganese causes toxic effects, including neurological symptoms such as Parkinsonism. However, endogenous factors involved in the protection against manganese toxicity remain unclear. Previously, we showed that rat basophilic leukemia RBL-2H3 cells are highly sensitive to MnCl2 compared with other rat cell lines. To identify the genes involved in resistance to manganese toxicity, two lines of Mn-resistant cells showing resistance to 300 µM MnCl2 (RBL-Mnr300) and 1200 µM MnCl2 (RBL-Mnr1200) were developed from RBL-2H3 cells by a stepwise increase in MnCl2 concentration in the medium. Microarray analyses were carried out to compare gene expression between parental RBL-2H3 cells and RBL-Mnr300 or RBL-Mnr1200 cells. Five genes exhibited more than 10-fold up-regulation in both RBL-Mnr300 and RBL-Mnr1200 cells, and 24 genes exhibited less than 0.1-fold down-regulation in both Mn-resistant cell lines. The S100a9 and S100a10 genes, encoding the calcium-binding S100A9 and S100A10 proteins, respectively, were found among the three most down-regulated genes in both Mn-resistant cell lines. The marked decreases in mRNA levels of S100a9 and S100a10 were confirmed by real-time RT-PCR analyses. Further characterization and comparison of these Mn-resistant cells may enable the identification of novel genes that play important roles in the modification of manganese toxicity.
    The Journal of Toxicological Sciences 09/2013; 38(5):753-7. DOI:10.2131/jts.38.753 · 1.29 Impact Factor

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    ABSTRACT: Elevated exposure to arsenic has been suggested to be associated with atherosclerosis leading to cardiovascular disease (CVD). However, biochemical events underlying the arsenic-induced atherosclerosis have not yet been fully documented. The aim of this study was to investigate the associations of circulating molecules involved in atherosclerosis with arsenic exposure in the individuals exposed to arsenic in Bangladesh. A total of 324 study subjects, 218 from arsenic-endemic areas and 106 from non-endemic area in Bangladesh were recruited. Drinking water, hair, nail and blood samples were collected from the study subjects for analysis. Total cholesterol (TC), low density lipoprotein (LDL) and high density lipoprotein (HDL) levels were lower in arsenic-endemic subjects than those of non-endemic subjects. Oxidized low density lipoprotein (Ox-LDL), C-reactive protein (CRP), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels were significantly higher in arsenic-endemic subjects than those of non-endemic subjects. All these circulating molecules showed significant correlations with arsenic exposure (water, hair and nail arsenic concentrations) and all these relations were significant before and after adjusting for relevant covariates. Among the circulating molecules tested in this study, HDL, Ox-LDL and CRP showed dose-response relationships with arsenic exposure. Ox-LDL/HDL ratios were increased with the increasing concentrations of arsenic in the water, hair and nails. Furthermore, non-HDL cholesterol and TC/HDL ratios were significantly correlated with arsenic exposure before and after adjusting for relevant covariates. Thus all the observed associations may be the major features of arsenic exposure related atherosclerosis leading to CVD.
    Toxicological Sciences 06/2013; 135(1). DOI:10.1093/toxsci/kft130 · 3.85 Impact Factor
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    Daigo Sumi · Kazusa Abe · Seiichiro Himeno ·
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    ABSTRACT: It is well known that exposure to inorganic arsenic through groundwater leads not only to cancer and cardiovascular disease, but also to detrimental effects on development. In this study, we investigated the effects of arsenite on the cardiac differentiation of rat myoblast H9c2 cells. The cardiac differentiation of H9c2 cells cultured in media containing 1% fetal bovine serum and all-trans retinoic acid was confirmed by enhanced expression of cardiac troponin T (cTnT), the appearance of multinucleated cells, and cell cycle arrest at G0/G1 phase. Exposure of H9c2 cells to inorganic arsenite (As(III)) during cardiac differentiation suppressed the appearance of the morphological and biological characteristics observed in the cardiac phenotype of H9c2 cells. In addition, As(III) inhibited PKCδ phosphorylation, which is detected in early-stage differentiation. These results suggest that As(III) retards the cardiac differentiation of H9c2 cells, at least partly, via the inhibition of PKCδ phosphorylation.
    Biochemical and Biophysical Research Communications 05/2013; 436(2). DOI:10.1016/j.bbrc.2013.05.069 · 2.30 Impact Factor
  • Hitomi Fujishiro · Toshinao Ohashi · Miki Takuma · Seiichiro Himeno ·
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    ABSTRACT: Rat basophilic leukemia RBL-2H3 cells show markedly high sensitivity to both CdCl2 and MnCl2 compared with other rat cell lines, due to efficient accumulation of cadmium and manganese. To clarify the roles of metal transporters in hyperaccumulation of cadmium and manganese in RBL-2H3 cells, Cd-resistant and Mn-resistant cells were developed from RBL-2H3 cells by continuous exposure to CdCl2 and MnCl2, respectively. The established Cd-resistant (RBL-Cdr) and Mn-resistant (RBL-Mnr) cells exhibited about 20 times higher LC50 values of CdCl2 and MnCl2, respectively, than parental RBL-2H3 cells, and showed cross-resistance to each metal. The resistance to cadmium and manganese was primarily conferred by a marked decrease in the uptake of both metals. RBL-Cdr cells also showed cross-resistance to HgCl2 and AgNO3 probably due to enhanced expression of metallothionein. Among the possible transporters involved in the uptake of Cd(2+) and Mn(2+), the expression of ZIP8 (Zrt-, Irt-related protein 8), encoded by Slc39a8, showed a marked suppression in both RBL-Cdr and RBL-Mnr cells. These results suggest that ZIP8 plays a pivotal role in the transport and toxicity of Cd(2+) and Mn(2+) in RBL-2H3 cells.
    Metallomics 04/2013; 5(5). DOI:10.1039/c3mt00003f · 3.59 Impact Factor
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    ABSTRACT: Trehalose 6,6'-dicorynomycolate (TDCM) was first characterized in 1963 as a cell surface glycolipid of Corynebacterium spp. by Ioneda and co-workers. TDCM shows potent anti-tumor activity due to its immunoadjuvant properties. Furthermore, the toxicity of TDCM in mice is much weaker than the related trehalose diester of mycolic acid; trehalose 6,6'-dimycolate (TDM, formerly known as cord factor). We have investigated the chemical modification of this class of compound to generate novel agents that display increased immunoadjuvant activity with minimal associated toxicity. During the course of this work we recently developed 6,6'-bis-O-(3-nonyldodecanoyl)-α,α'-trehalose (designated as vizantin). Our results show that vizantin exhibited a potent prophylactic effect on experimental lung metastasis of B16-F0 melanoma cells without a loss of body weight and death in mice. Furthermore, vizantin effectively stimulated human macrophages in an in vitro model, making it a promising candidate for a safe adjuvant in clinical applications. In order to elucidate the pharmacokinetics of vizantin, a probe molecule with similar activity was developed on the basis of a structure-activity relationship (SAR) study with vizantin. The distribution of the probe molecule after intravenous administration into a mouse was assessed by macro confocal microscopy, where it was found to accumulate in the lungs and liver.
    Chemical & pharmaceutical bulletin 04/2013; 61(4):452-9. DOI:10.1248/cpb.c13-00006 · 1.16 Impact Factor
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    ABSTRACT: Metallothionein (MT), a low-molecular-weight protein with a high affinity for divalent heavy metal ions, is involved in many pathophysiological processes, including metal homeostasis, detoxification, cell proliferation and protection against oxidative damage. We previously found that MT in gastric mucosa plays a role in protecting against Helicobacter pylori (H. pylori)-induced gastritis at the early stage of infection. H. pylori-induced chronic gastric inflammation is shown to be associated with gastric carcinogenesis. Thus, to examine whether gastric MT contributes to protection against H. pylori-induced chronic inflammation, we compared histological changes in the gastric mucosa of MT-null and the wild-type mice at 53 weeks after inoculation three times with H. pylori SS1. As a result, we observed disruption of the gastric mucosa in MT-null mice, but not in the wild-type mice, even at the late stage of H. pylori-infection. Evaluation of pathological changes in gastric specimens by the updated Sydney grading system revealed that scores related to chronic inflammation and polymorphonuclear cell activity were higher in infected MT-null mice than those in the wild-type mice. Furthermore, a higher score for metaplasia was also observed in the MT-null stomach. These results suggested that MT might be involved in protecting against H. pylori-induced gastric chronic inflammation associated with carcinogenesis.
    The Journal of Toxicological Sciences 12/2012; 37(6):1261-5. DOI:10.2131/jts.37.1261 · 1.29 Impact Factor
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    ABSTRACT: Vizantin, 6,6'-bis-O-(3-nonyldodecanoyl)-α,α'-trehalose, was developed as a safe immunostimulator on the basis of a structure-activity relationship (SAR) study with trehalose 6,6'-dicorynomycolate (TDCM). It was possible to synthesize vizantin on a large scale more easily than in the case of TDCM, and the compound exhibited more potent prophylactic effect on experimental lung metastasis of B16-F0 melanoma cells. Since vizantin stimulated human macrophages, it is a promising candidate for clinical application.
    Journal of Medicinal Chemistry 12/2012; 56(1). DOI:10.1021/jm3016443 · 5.45 Impact Factor
  • Daigo Sumi · Yuri Shimizu · Seiichiro Himeno ·
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    ABSTRACT: This study examined whether S100A8 and S100A9, which comprise a complex called calprotectin, are upregulated by exposure to sodium arsenite [As(III)] in nine lines of human-derived cells. HaCaT skin keratinocyte cells, U937 leukemic monocyte cells, and UROtsa urothelial cells showed increased mRNA levels of S100A8 and S100A9 after a 2-week exposure to As(III). To understand the mechanisms regulating S100A9 upregulation in response to As(III), we tested S100A9 promoter-dependent luciferase activity in HaCaT cells transfected with S100A9 promoter (-1000/+429)-fused luciferase cDNA. The results indicated that exposure to As(III) stimulated S100A9 promoter-dependent luciferase activity. In addition, the transcription NF-E2-related factor 2 (Nrf2) was strongly activated in HaCaT cells exposed to As(III). Since two putative antioxidant response elements were found in the S100A9 promoter (ARE1, 5'-ACAGGCAGGG-3' from -897 to -887; ARE2, 5'-ATCTTCCGGAG-3' from -78 to -67), we constructed deletion mutants of each ARE on S100A9 promoter-fused luciferase cDNA. The results indicated that ARE2 is the responsible element for the activation of S100A9 transcription in response to As(III). This report is the first to demonstrate that As(III) enhanced S100A8 and S100A9 expression in human-derived cells and As(III)-induced S100A9 expression is dependent on Nrf2 activation.
    International Journal of Molecular Medicine 11/2012; 31(1). DOI:10.3892/ijmm.2012.1185 · 2.09 Impact Factor
  • Daigo Sumi · Seiichiro Himeno ·
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    ABSTRACT: The metabolism of arsenicals, including their reduction and methylation has been extensively studied, and both classical and novel pathways of arsenic methylation are proposed. Arsenic methylation has been considered to be a detoxification process of inorganic arsenicals, although recent studies have indicated that trivalent methylated arsenicals, the intermediate products of arsenic methylation, are more toxic than inorganic arsenicals. In 2002, arsenite (+3 oxidation state) methyltransferase (As3MT) was discovered to be an enzyme responsible for arsenic methylation. This review focuses on current information on the function, genetic polymorphism, and alternative splicing of As3MT, all of which contribute to arsenic metabolism and toxicity.
    Biological & Pharmaceutical Bulletin 11/2012; 35(11):1870-5. DOI:10.1248/bpb.b212015 · 1.83 Impact Factor
  • Seiichiro Himeno ·
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    ABSTRACT: The roles of trace elements have been extensively studied for decades. However, recent advances in both molecular and epidemiological studies on trace elements have provided new information and concepts on the actions of trace elements. Some of our fundamental knowledge on the roles of trace elements based on classical data should be replaced by new concept based on new findings. This series of "Re-evaluation of the Fundamentals of Trace Elements" aims to provide new fundamentals on trace elements by reviewing rapidly advancing knowledge in this study area. The first article is a critical review on the role of chromium in human nutrition.
    Nippon Eiseigaku Zasshi (Japanese Journal of Hygiene) 10/2012; 67(4):484. DOI:10.1265/jjh.67.484
  • Hitomi Fujishiro · Yu Yano · Yukina Takada · Maya Tanihara · Seiichiro Himeno ·
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    ABSTRACT: Chronic exposure to cadmium causes preferential accumulation of cadmium in the kidney, leading to nephrotoxicity. In the process of renal cadmium accumulation, the cadmium bound to a low-molecular-weight metal-binding protein, metallothionein, has been considered to play an important role in reabsorption by epithelial cells of proximal tubules in the kidney. However, the role and mechanism of the transport of Cd(2+) ions in proximal tubule cells remain unclear. Zinc transporters such as Zrt, Irt-related protein 8 (ZIP8) and ZIP14, and divalent metal transporter 1 (DMT1) have been reported to have affinities for Cd(2+) and Mn(2+). To examine the roles of these metal transporters in the absorption of luminal Cd(2+) and Mn(2+) into proximal tubule cells, we utilized a cell culture system, in which apical and basolateral transport of metals can be separately examined. The uptake of Cd(2+) and Mn(2+) from the apical side of proximal tubule cells was inhibited by simultaneous addition of Mn(2+) and Cd(2+), respectively. The knockdown of ZIP8, ZIP14 or DMT1 by siRNA transfection significantly reduced the uptake of Cd(2+) and Mn(2+) from the apical membrane. The excretion of Cd(2+) and Mn(2+) was detected predominantly in the apical side of the proximal tubule cells. In situ hybridization of these transporters revealed that ZIP8 and ZIP14 are highly expressed in the proximal tubules of the outer stripe of the outer medulla. These results suggest that ZIP8 and ZIP14 expressed in the S3 segment of proximal tubules play significant roles in the absorption of Cd(2+) and Mn(2+) in the kidney.
    Metallomics 04/2012; 4(7):700-8. DOI:10.1039/c2mt20024d · 3.59 Impact Factor

Publication Stats

1k Citations
246.20 Total Impact Points


  • 2004-2015
    • Tokushima Bunri University
      • Faculty of Pharmaceutical Sciences
      Tokusima, Tokushima, Japan
  • 1993-2007
    • Kitasato University
      • Department of Pharmaceutical Sciences
      Edo, Tōkyō, Japan
  • 2001
    • Wako University
      Edo, Tōkyō, Japan
  • 1989
    • The University of Tokyo
      • Department of International Health
      Edo, Tōkyō, Japan