ADNP Modulates SINE B2-Derived CTCF-Binding Sites during Blastocyst Formation in Mouse

During early embryo development, the nuclear factor CTCF plays a vital role in organizing chromatin structure and regulating transcription. Recent studies have examined the establishment of nucleosome profiles around the CTCF motif sites shortly after fertilization. However, the kinetics of CTCF chromatin occupation in pre-implantation embryos have remained unclear. In this study, we utilized CUT&RUN technology to investigate CTCF occupancy in mouse pre-implantation development. Our findings revealed that CTCF begins binding to the genome prior to zygotic genome activation (ZGA), with a preference for CTCF anchored chromatin loops. Although the majority of CTCF occupancy is consistently maintained, we identified a specific set of binding sites enriched in the mouse-specific short-interspersed element (SINE) family B2, which are restricted to the cleavage stages. Notably, our data suggested that the neuroprotective protein ADNP may counteract the stable association of CTCF at SINE B2-derived CTCF-binding sites.