CFP1 Regulates Histone H3K4 Trimethylation and Developmental Potential in Mouse Oocytes

Through RNA-seq of wildtype and CFP1-deleted GV oocytes of different ages, zygotes and 2-cell embryos and whole genome bisulfite sequencing of GV oocytes, We show here that CFP1 is responsible for epigenetic maturation in oocytes. Deletion of CFP1 directly decreased histone H3K4 trimethylation and caused global down-regulation of gene expression in oocytes.These genes are involved in cytoplasmic lattice formation, maternal-zygotic transition and epigenetic maturation. Maternal CFP1-deleted oocytes had fewer CPLs in the cytoplasm and the organelles were severely aggregated, which further caused defects in α-tubulin polymerization and aneuploidy in meiosis II. The genome was less methylated and methylation of maternal DNA was impaired after CFP1 deletion. Therefore CFP1-deleted oocytes fail to complete epigenetic maturation as well as cytoplasmic maturation and nuclear maturation and unable to gain developmental competence during oogenesis. GV oocyte, zygote and 2-cell embryonic transcriptome profiles wild type (WT) and CFP1-depleted mice were generated by deep sequencing, in duplicate or triplicate on Illumina platform.本研究通过对不同年龄的野生型与CFP1缺失型GV卵母细胞（GV oocyte）、受精卵及2细胞胚胎进行RNA测序（RNA-seq），并对GV卵母细胞开展全基因组亚硫酸氢盐测序（whole genome bisulfite sequencing），证实CFP1介导卵母细胞的表观成熟过程。CFP1的缺失会直接降低组蛋白H3K4三甲基化水平，并导致卵母细胞内基因表达整体下调。上述差异表达基因参与细胞质晶格形成、母源-合子转换（maternal-zygotic transition）以及表观成熟调控。携带母源CFP1缺失的卵母细胞，其细胞质内CPLs数量减少，细胞器发生严重聚集，进而引发Ⅱ期减数分裂（meiosis II）中α-微管蛋白（α-tubulin）聚合缺陷与非整倍体现象。CFP1缺失后，基因组整体甲基化水平降低，母源DNA甲基化过程受损。因此，CFP1敲除的卵母细胞无法完成表观成熟、细胞质成熟与核成熟，亦无法在卵发生过程中获得发育潜能。本研究通过深度测序技术，在Illumina平台上以双份或三份生物学重复的方式，构建了野生型（WT）与CFP1缺失型小鼠的GV卵母细胞、受精卵及2细胞胚胎的转录组图谱。