Induction of cellular totipotency by NACC1-driven feed-forward regulation.

Mammalian embryo development begins with totipotent cells. Despite its significance, gene regulatory mechanisms controlling the totipotent cell stage are poorly understood. Based on single-cell proteomics and transcriptomics, we identified nucleus accumbens-associated 1 (NACC1) as a critical regulator of totipotent-like cell state in mouse embryonic stem cells. Using a combination of genomics approaches, we found that NACC1 directly binds to gene-regulatory regions and favours chromatin accessibility to induce the expression of totipotency and zygotic genome activation genes, as well as retrotransposons associated with totipotency. In parallel, NACC1-regulated retrotransposons further modulate the expression of proximal totipotency genes, forming a coherent feed-forward mechanism that regulates totipotent-like cells. Furthermore, NACC1 is crucial for the progression of embryogenesis beyond the totipotency stage. Thus, we uncover a genome-level NACC1-driven feed-forward gene regulatory mechanism that governs totipotent-like cells and has a crucial role during embryonic development.