Host: The Japanese Society of Toxicology
Name : The 47th Annual Meeting of the Japanese Society of Toxicology
Date : 2020 -
Selenium, an essential trace element, is highly reactive and toxic, but the living body takes in the properties of selenium and uses it for biological defense. Selenium is mainly incorporated into the proteins in the form of selenocysteine (Sec: an analog of cysteine that contains selenium instead of sulfur) and forms the active site of glutathione peroxidase and thioredoxin reductase. Selenium is essential for the antioxidative defense. However, in recent years, it has been revealed that the disorder of selenium metabolism is involved in lifestyle-related diseases such as diabetes. The plasma selenium-containing protein selenoprotein P (SeP) induced by high glucose and high fat worsens insulin resistance and insulin secretion, acting as a “bad guy” in the onset and development of diabetes.
Selenium contained in food is digested, absorbed from the gastrointestinal tract, and then enters the synthesis pathway of selenium-containing proteins. The metabolic pathway differs depending on the form of selenium. Sec is recognized by the living body as "selenium", cleaved by Sec lyase, and then inorganic selenium enters the Sec synthesis pathway. On the other hand, selenomethionine (SeMet: an analog of methionine that contains selenium instead of sulfur) absorbed in the body is metabolized in vivo without distinction between selenium and sulfur, and a part is incorporated into proteins, directly. In this presentation, the interaction between selenium and sulfur metabolism, especially the metabolic pathway of amino acids containing each element and the discrimination mechanism of each element in vivo, is outlined. Further, the cross-talk between selenium and sulfur metabolism, especially the biological response against electrophile and its detoxication, are discussed.
