Fig. 2. Copper is a fast inhibitor of SELENOP excretion.

a–c Extracellular SELENOP and intracellular Se concentrations of HepG2 cells which were co-incubated with Cu and Se for indicated time points, analyzed using dot blot and normalized to Ponceau (P) staining or by TXRF (n = 3). d Extracellular SELENOP of HepG2 cells treated for 72 h with 0 or 100 µM CuSO₄ in combination with or without 50 nM selenite. In addition, 24 h prior to harvest the Cu chelators BCS or TTM were added. Samples were analyzed by Western Blot, normalized to Ponceau staining, and selenite-treated cells were set as 1 (n = 3). e Extra- and intracellular SELENOP (n = 4) and selenium concentration (n = 3) of HepG2 cells treated with 50 nM selenite in combination with either 100 µM Cu, Zn or Fe for 72 h or with 600 µM H₂O₂ for 6 h (in selenite supplied cells) presented as fold change to selenite only treated cells. Respective cells without further treatment were set as 1 (indicated by the dotted line). Data are depicted as mean ± SD. Biological replicates are indicated by individual dots. Statistical analyses were based on two-way ANOVA with Bonferroni’s post-test (a, c, d) or on two-tailed t test compared to untreated cells (e). *p < 0.05; **p < 0.01; ***p < 0.001 vs. -Cu (a, c, d) or other treatments such as -Zn, -Fe or -H₂O₂ (e), ^#p < 0.05; ^##p < 0.01; ^###p < 0.001 vs. 6 h; ⁺⁺p < 0.01; ⁺⁺⁺p < 0.001 vs. -chelator. Source data are provided as a source Data file.