Status of estrogen receptor expression and epigenetic methylation in Leydig cells after exposure to metalloestrogen - selenium

The trace element selenium (Se) is essential for the maintenance of spermatogenesis and fertility. A growing volume of evidence shows that Se is necessary for testosterone synthesis, and Se can stimulate Leydig cell proliferation. However, Se can also act as a metalloestrogen, which can mimic estrogen and activate the estrogen receptors. This study aimed to investigate Se effect on estrogen signaling and the epigenetic status of Leydig cells. Mouse Leydig cells (MA-10) were cultured in a medium supplemented with different Se concentrations (4, 8 µM) for 24 h. Next, cells were assessed for morphological and molecular (qRT PCR, western blot, immunofluorescence) analyses. Immunofluorescence revealed strong immunosignal for 5-methylcytosine in both control and treated cells, with a stronger signal in the 8 μM treated group. qRT-PCR confirmed an increased expression of methyltransferase 3 beta (Dnmt3b) in 8 μM cells. Analysis of the expression of γH2AX (a marker for double-stranded DNA breaks) revealed an increase in the DNA breaks in cells exposed to 8 μM Se. Selenium exposure did not affect the expression of canonical estrogen receptors (ERα and ERβ), however, an increase in membrane estrogen receptor G-protein coupled (GPER) protein expression was observed.To sum up, in a high concentration (8 μM) Se affects GPER expression (non-genomic estrogen signaling) in Leydig cells possibly via acting on receptor protein and/or its binding. This causes DNA breaks and induces changes in Leydig cell methylation status, especially in de novo methylation which is mediated by Dnmt3b. •Administration of 8 µM of sodium selenite has negative effect on mouse Leydig cells.•Leydig cells methylation status change due to higher expression of Dnmt3a.•Selenium affects expression of GPER, mediating non genomic estrogen signaling.•Excessive selenium administration causes DNA breaks.