Whole genome bisulfite sequencing (WGBS) of Tex15 wt, Tex15 ht, and Tex15 ko male germ cells at postnatal day 2.5

DNA methylation is a major silencing mechanism of transposable elements (TEs). Here we report that TEX15, a testis-specific protein, is required for TE silencing. Through WGBS, we find that Tex15 mutant germ cells exhibit DNA hypomethylation in TEs. Our results identify TEX15 as a new essential epigenetic regulator that appears to function independently or downstream of the piRNA biogenesis machineries to silence TEs by DNA methylation in male germ cells. We report hypomethylation in retrotransposons in Tex15-/- male germ cells at day 2.5 WGBS-seq of Tex15+/+, Tex15+/-, and Tex15-/- male germ cells at postnatal day 2.5 in biological duplicates (75PE-HiSeq4000); Germ cells were FACS-sorted (Oct4-GFP) from testes of pups from Tex15+/- x Tex15+/- matings.

DNA甲基化是转座因子（transposable elements, TEs）的主要沉默机制。本研究报道，睾丸特异性蛋白TEX15是转座因子沉默所必需的。通过全基因组亚硫酸氢盐测序（whole-genome bisulfite sequencing, WGBS），我们发现Tex15突变的生殖细胞在转座因子区域呈现DNA低甲基化特征。本研究结果证实，TEX15是一种全新的关键表观遗传调控因子，其可独立于piRNA生成通路或在其下游发挥功能，通过DNA甲基化在雄性生殖细胞中实现转座因子的沉默。本研究同时报道了出生后第2.5天的Tex15纯合敲除（Tex15-/-）雄性生殖细胞中反转录转座子的低甲基化现象；该数据集包含出生后第2.5天的Tex15野生型（Tex15+/+）、杂合子（Tex15+/-）与纯合敲除（Tex15-/-）雄性生殖细胞的全基因组亚硫酸氢盐测序数据（WGBS-seq），采用双生物学重复，测序平台为75PE-HiSeq4000。实验所用生殖细胞通过荧光激活细胞分选（fluorescence-activated cell sorting, FACS），以Oct4-GFP为标记，从Tex15+/-与Tex15+/-交配产生的幼鼠睾丸中分离获得。