TET2 catalyzes active DNA demethylation of the Sry promoter and enhances its expression

SRY is the master regulator of male sex determination in eutherian mammals. In mice, Sty expression is transcriptionally and epigenetically controlled in a developmental stage-specific manner. The Sry promoter undergoes demethylation in embryonic gonadal somatic cells at the sex-determining period. However, its molecular mechanism and in vivo significance remain unclear. Here, we report that the Sty promoter is actively demethylated during gonadal development, and TET2 plays a fundamental role in Sry demethylation. Tet2-deficient mice showed absence of 5-hydroxymethylcytosine in the Sty promoter. Furthermore, Tet2 deficiency diminished Sry expression, indicating that TET2-mediated DNA demethylation regulates Sty expression positively. We previously showed that the deficiency of the H3K9 demethylase Jmjd1a compromises Sty expression and induces male-to-female sex reversal. Tet2 deficiency enhanced the sex reversal phenotype of Jmjdla-deficient mice. Thus, TET2-mediated active DNA demethylation and JMJD1A-mediated H3K9 demethylation contribute synergistically to sex determination.