Individual effects of different selenocompounds on the hepatic proteome and energy metabolism of mice

Abstract

Background: Selenium (Se) exerts its biological activity largely via selenoproteins, which are key enzymes for maintaining the cellular redox homeostasis. However, besides these beneficial effects there is also evidence that an oversupply of Se might increase the risk towards developing metabolic disorders. To address this in more detail, we directly compared effects of feeding distinct Se compounds and concentrations on hepatic metabolism and expression profiles of mice. Methods: Male C57BL6/J mice received either a selenium-deficient diet or diets enriched with adequate or high doses of selenite, selenate or selenomethionine for 20 weeks. Subsequently, metabolic parameters, enzymatic activities and expression levels of hepatic selenoproteins, Nrf2 targets, and additional redox-sensitive proteins were analyzed. Furthermore, 2D-DIGE-based proteomic profiling revealed Se compound-specific differentially expressed proteins. Results: Whereas heterogeneous effects between high concentrations of the Se compounds were observed with regard to body weight and metabolic activities, selenoproteins were only marginally increased by high Se concentrations in comparison to the respective adequate feeding. In particular the high-SeMet group showed a unique response compromising higher hepatic Se levels in comparison to all other groups. Accordingly, hepatic glutathione (GSH) levels, glutathione S-transferase (GST) activity, and GSTpi1 expression were comparably high in the high-SeMet and Se-deficient group, indicating that compound-specific effects of high doses appear to be independent of selenoproteins. Conclusions: Not only the nature, but also the concentration of Se compounds differentially affect biological processes. General significance: Thus, it is important to consider Se compound-specific effects when supplementing with selenium.