Selenium status influences selenoprotein H interactions with other selenoproteins in the response to oxidative stress

Selenium (Se) is an essential trace element exerting its biological functions mainly through selenoproteins. Evidence suggests that selenoprotein H (SELONOH), a nuclear protein suppressing oxidative stress and cellular senescence, is the most prominent selenoprotein responding in parallel to dietary Se deficiency and age in telomere‐humanized mice. On the other hand, SELENOH is one of the few low‐hierarchy selenoproteins whose expression is very sensitive to fluctuations in Se status. The objective of this study was to explore impacts of SELENOH on the expression of other selenoproteins and redox regulation upon changes in Se status. A plasmids expressing wild‐type SELENOH was constructed and transfected into human HEK293T cells. Adding Se (Na 2 SeO 3 , 0–200 nM) to cell culture medium dose‐dependently increased protein levels of overexpressed SELENOH and other selenoproteins including glutathione peroxide 1 and thioredoxin reductase 1; however, their mRNA transcripts were not affected by Se status and SELENOH suppressed protein expression of the other two selenoproteins. Supplementing Se (100 nM) enabled overexpressed SELENOH to protect against paraquat‐induced senescence and declines in cellular viability. Analyses of SELENOH‐associated proteins through LC‐MS‐MS co‐identified nucleolar and glycosylation proteins. Altogether, these results suggest that SELENOH could compete with other selenoproteins for available Se but protects against oxidative stress together with them. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .