Treatment donor cells with UNC0638 modify the abnormal histone H3K9 dimethylation and gene expression in cloned goat embryos

Epigenetic modifications are considered crucial to the reprogramming of somatic cell nuclear transfer (SCNT) embryos and subsequent in vitro development. The abnormal histone H3K9 dimethylation (H3K9me2) status has recently been reported in SCNT embryos. The present study was designed to evaluate the effect of treatment donor cells with UNC0638, a specific inhibitor of H3K9 methyltransferase G9A, on in vitro development, H3K9me2 levels and gene expression in goat SCNT embryos. Different concentration of UNC0638 was applied to treat goat fetal fibroblasts (GFFs), and the treated GFFs were used as donor cells for SCNT. The results showed that 0.2 μM UNC0638 decreased significantly the level of H3K9me2 in treated GFFs (P < 0.05), and did not influence the cell viability (P > 0.05). Compared with intracytoplasmic sperm injection (ICSI) embryos, SCNT embryos derived from untreated GFFs (C-SCNT) presented higher level of H3K9me2 (P < 0.05). Although the in vitro developmental rate was not improved, the abnormal H3K9me2 level was corrected in SCNT embryos from UNC0638-treated GFFs (T-SCNT) compared with C-SCNT embryos. Furthermore, UNC0638 treatment could promote the mRNA expression of key developmental genes Nanog and Oct4 (P < 0.05), but did not affect the imprinted genes H19 and IGF2R expression in goat SCNT embryos (P > 0.05). In conclusion, these results indicated that treatment donor cells with UNC0638 may have beneficial effects in terms of modifying the abnormal H3K9me2 status and gene expression in cloned goat embryos.