Multi-omics and low-input proteomics profiling reveals dynamic regulation driving pluripotency initiation in early mouse embryos.

Pre-implantation of a mouse embryo is a process of transitioning from totipotency to pluripotency. However, the regulatory mechanisms underlining this transition remain poorly understood. We combined single-cell transcriptomic analysis, epigenetic profiling, low-input proteomics and functional validation experiments with the aim of gaining insight into the dynamic regulatory networks underlying the transition from the eight-cell to the 16-cell stage of mouse development. Transcriptomic analysis and H3K4me3 modification profiling, combined with functional half of the blastomeres biopsy, revealed that eight-cell mouse embryos retained residual totipotency-related molecular features and developmental potential. Furthermore, we identified dynamic cytoskeletal remodeling, regulated in part by the ubiquitin-proteasome system, as a prominent molecular event during the transition from the eight-cell to the 16-cell stage. Collectively, our findings highlight the eight-cell stage as a critical developmental window characterized by gradual restriction of developmental potential, and also underscore cytoskeletal remodeling as a key molecular process coinciding with the onset of pluripotency. These results provide insight into the biological processes underlying totipotent features and how these are progressively attenuated during early mouse embryogenesis.