Distinct activity of Oct4 regulatory elements in naïve and primed pluripotency

Naïve and primed pluripotent stem cells (PSCs) and germ cells express the Pou5f1 (Oct4) gene. The Oct4 gene contains two cis-regulatory elements, the distal (DE) and proximal enhancer (PE), which differentially control Oct4 expression in a cell-type- and stage-specific manner. Here, we generated double transgenic mice carrying both Oct4-ΔPE-GFP and Oct4-ΔDE-tdTomato (RFP), enabling us to simultaneously monitor the activity of DE and PE. Oct4 expression is stage-specifically regulated by DE and PE during embryonic and germ cell development. Using this dual reporter system, we successfully cultured pure populations of naïve (GFP+RFP-) and primed (GFP-RFP+) PSCs. We found that GFP+RFP- cells were metastable in serum-containing medium; stable naïve pluripotent cells were observed in medium containing two inhibitors (Meki and GSKi) but lacking serum. Finally, we suggest that the activity of Oct4 DE and PE is regulated by the repressive histone marks H3K9me3 and DNA methylation. Total RNA obtained from sorted cells by FACS analysis