Kentaro Matsumura

Bio: Kentaro Matsumura is an academic researcher from Chuo University. The author has contributed to research in topics: Selenium deficiency & Excretion. The author has an hindex of 2, co-authored 2 publications receiving 51 citations.

Dynamic pathways of selenium metabolism and excretion in mice under different selenium nutritional statuses

Abstract: The selenoprotein, cellular glutathione peroxidase (cGPx), has an important role in protecting organisms from oxidative damage through reducing levels of harmful peroxides The liver and kidney in particular, have important roles in selenium (Se) metabolism and Se is excreted predominantly in urine and feces In order to characterize the dynamics of these pathways we have measured the time-dependent changes in the quantities of hepatic, renal, urinary, and fecal Se species in mice fed Se-adequate and Se-deficient diets after injection of (82)Se-enriched selenite Exogenous (82)Se was transformed to cGPx in both the liver and kidney within 1 h after injection and the synthesis of cGPx decreased 1 to 6 h and continued at a constant level from 6 to 72 h after injection The total amount of Se associated with cGPx in mice fed Se-deficient diets was found to be less than in mice fed Se-adequate diets This finding indicated that cGPx synthesis was suppressed under Se-deficient conditions and did not recover with selenite injection Excess Se was associated with selenosugar in liver and transported to the kidney within 1 h after injection, and then excreted in urine and feces within 6 h after injection Any excess amount of Se was excreted mainly as a selenosugar in urine

Distribution and Dynamic Pathway of Selenium Species in Selenium-deficient Mice Injected with 82Se-enriched Selenite

Abstract: In order to elucidate Se metabolism in a living body, (82)Se-enriched selenite was injected intravenously into mice fed Se-adequate and -deficient diets. We studied the time-dependent changes in the distribution of the labeled Se in organs, red blood cells, and plasma. The total Se was determined by flow-injection ICPMS, and Se speciation analysis was conducted by micro-affinity chromatography coupled with low-flow ICPMS. Total Se in almost all organs, including liver, showed the maximum at 1 h after injection. From speciation analysis, exogenous (82)Se as Se-containing proteins other than selenoprotein P (Sel-P) (selenium containing albumin (SeAlb) and extra cellular glutathione peroxidase (eGPx)), peaked at 1 h and quickly decreased from 1 to 6 h after injection, whereas that as Sel-P, peaked at 6 h, and gradually decreased from 6 to 72 h after injection. We found that there were two pathways for the transfer of Se in mice; one was as SeAlb until 1 h after injection, and the other was as Sel-P from 6 to 72 h after injection.

Selenium biochemistry and its role for human health

Abstract: Despite its very low level in humans, selenium plays an important and unique role among the (semi)metal trace essential elements because it is the only one for which incorporation into proteins is genetically encoded, as the constitutive part of the 21st amino acid, selenocysteine. Twenty-five selenoproteins have been identified so far in the human proteome. The biological functions of some of them are still unknown, whereas for others there is evidence for a role in antioxidant defence, redox state regulation and a wide variety of specific metabolic pathways. In relation to these functions, the selenoproteins emerged in recent years as possible biomarkers of several diseases such as diabetes and several forms of cancer. Comprehension of the selenium biochemical pathways under normal physiological conditions is therefore an important requisite to elucidate its preventing/therapeutic effect for human diseases. This review summarizes the most recent findings on the biochemistry of active selenium species in humans, and addresses the latest evidence on the link between selenium intake, selenoproteins functionality and beneficial health effects. Primary emphasis is given to the interpretation of biochemical mechanisms rather than epidemiological/observational data. In this context, the review includes the following sections: (1) brief introduction; (2) general nutritional aspects of selenium; (3) global view of selenium metabolic routes; (4) detailed characterization of all human selenoproteins; (5) detailed discussion of the relation between selenoproteins and a variety of human diseases.

The human selenoproteome: recent insights into functions and regulation

Abstract: Selenium (Se) is a nutritional trace mineral essential for various aspects of human health that exerts its effects mainly through its incorporation into selenoproteins as the amino acid, selenocysteine. Twenty-five selenoprotein genes have been identified in humans and several selenoproteins are broadly classified as antioxidant enzymes. As progress is made on characterizing the individual members of this protein family, however, it is becoming clear that their properties and functions are quite diverse. This review summarizes recent insights into properties of individual selenoproteins such as tissue distribution, subcellular localization, and regulation of expression. Also discussed are potential roles the different selenoproteins play in human health and disease.

Regulation of Selenium Metabolism and Transport

Abstract: Selenium is regulated in the body to maintain vital selenoproteins and to avoid toxicity. When selenium is limiting, cells utilize it to synthesize the selenoproteins most important to them, creating a selenoprotein hierarchy in the cell. The liver is the central organ for selenium regulation and produces excretory selenium forms to regulate whole-body selenium. It responds to selenium deficiency by curtailing excretion and secreting selenoprotein P (Sepp1) into the plasma at the expense of its intracellular selenoproteins. Plasma Sepp1 is distributed to tissues in relation to their expression of the Sepp1 receptor apolipoprotein E receptor-2, creating a tissue selenium hierarchy. N-terminal Sepp1 forms are taken up in the renal proximal tubule by another receptor, megalin. Thus, the regulated whole-body pool of selenium is shifted to needy cells and then to vital selenoproteins in them to supply selenium where it is needed, creating a whole-body selenoprotein hierarchy.

Selenium nanoparticles as a nutritional supplement

Abstract: Selenium is an essential trace element in the diet, required for maintenance of health and growth; however, its toxicity could cause serious damage depending on dose and chemical form. Selenium nanoparticles (SeNPs) represent what we believe to be a novel prospect for nutritional supplementation because of their lower toxicity and ability to gradually release selenium after ingestion. In this review, we discuss various forms and types of SeNPs, as well as the way they are synthesized. We also discuss absorption and bioavailability of nanoparticles within the organism. SeNPs demonstrate anticancer and antimicrobial properties that may contribute to human health, not only as dietary supplements, but also as therapeutic agents.

Current knowledge in species-related bioavailability of selenium in food

Abstract: Selenium is an essential trace element that has raised interest because of its antioxidant and anticancer properties. The beneficial or toxic effect of Se is not only dose-dependent, but also relates to the chemical form of the element and its bioavailability. In this review, recently published data is summarised concerning both Se speciation and Se relative bioavailability in various foodstuffs. In addition, Se bioavailability is discussed in relation to the species-dependent metabolism in humans. In this way, the understanding of the potential health impact of Se species in commonly consumed food is aimed to be improved. It is strongly suggested on the basis of a higher retention and a lower toxicity, that organic Se (especially SeMet, the major species in food) is more recommendable than inorganic Se in the frame of a balanced diet. Further research is however desirable concerning the characterisation of unidentified Se species and determination of their health effects.