The highly expressed ERV1 forms virus-like particles for regulating early embryonic development

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.