Gse1, a component of the CoREST complex, is required for placenta development in the mouse

Gse1 is a component of the CoREST complex that acts as an H3K4 and H3K9 demethylase and regulates gene expression. Here, we examined the expression and role of Gse1 in mouse development. Gse1 is expressed in male and female germ cells and plays both maternal and zygotic roles. Thus, maternal deletion of Gse1 results in a high incidence of prenatal death, and zygotic deletion leads to embryonic lethality from embryonic day 12.5 (E12.5) and perinatal death. Gse1 is expressed in the junctional zone and the labyrinth of the developing placenta. Gse1 mutant (Gse1^Δex3/Δex3) placenta begins to exhibit histological defects from E14.5, being deficient in MCT4⁺ syncytiotrophoblast II. The number of various cell types was largely maintained in the mutant placenta at E10.5, but several genes were upregulated in giant trophoblasts at E10.5. Placenta-specific deletion of Gse1 with Tat-Cre suggested that defects in Gse1^Δex3/Δex3 embryos are due to placental function deficiency. These results suggest that Gse1 is required for placental development in mice, and in turn, is essential for embryonic development.