YY1-dependent transcriptional regulation manifests at the morula stage.

YY1 plays multifaceted roles in various cell types. We recently reported that YY1 regulates nucleosome organization in early mouse embryos. However, despite the impaired nucleosome organization in the absence of YY1, the transcriptome was minimally affected in eight-cell embryos. We then hypothesized that YY1 might prepare a chromatin environment to regulate gene expression at later stages. To test this possibility, we performed a transcriptome analysis at the morula stage. We found that a substantial number of genes are aberrantly expressed in the absence of YY1. Furthermore, our analysis revealed that YY1 is required for the transcription of LINE-1 retrotransposons.