Early embryo sequence of goat

In mammals, the transcription of transposable elements (TEs) is important for maintaining early embryonic development. Here, we systematically analyzed the expression characteristics of TE-derived transcripts in early embryos by constructing a database of TEs and transcriptome data from goats and using it to study the function of endogenous retroviruses (ERVs) in regulating early embryo development. We found that ERV1 made up the highest proportion of TE sequences and exhibited a stage-specific expression pattern during early embryonic development. Among ERV elements, ERV1 had the potential to encode the Gag protein domain to form virus-like particles (VLPs) in early goat embryos. Knockdown of ERV1_1_574 significantly reduced the embryo development rate and the number of trophoblast cells (P< 0.05). Transcriptome sequencing analysis of morula embryos showed that ERV1_1_574 mainly regulated the expression of genes related to embryo compaction and trophoblast cell differentiation, such as CX43 and CDX2. In summary, we found that ERV1 expression was essential for early embryonic development in goats through regulation of trophoblast cell differentiation.

在哺乳动物中，转座因子（Transposable Elements，TEs）的转录对于维持早期胚胎发育至关重要。本研究通过构建山羊转座因子与转录组数据库，系统分析了早期胚胎中TE来源转录本的表达特征，并以此探究内源性逆转录病毒（Endogenous Retroviruses，ERVs）在早期胚胎发育调控中的功能。研究发现，ERV1在TE序列中占比最高，且在早期胚胎发育过程中呈现阶段特异性表达模式。在内源性逆转录病毒元件中，ERV1具备编码Gag蛋白结构域的能力，可在山羊早期胚胎中形成病毒样颗粒（Virus-Like Particles，VLPs）。敲低ERV1_1_574的表达可显著降低胚胎发育率及滋养层细胞数量（P<0.05）。对桑椹胚胚胎的转录组测序分析显示，ERV1_1_574主要调控与胚胎致密化及滋养层细胞分化相关的基因表达，例如CX43与CDX2。综上，本研究证实，山羊早期胚胎发育依赖ERV1的表达，其通过调控滋养层细胞分化发挥关键作用。