The ZBTB24-CDCA7-HELLS axis suppresses the totipotent 2C-like reprogramming by maintaining Dux methylation and repression

Two-cell-like cells (2CLCs), a rare population (~0.5%) in murine embryonic stem cell (mESC) cultures, are in a transient totipotent-like state resembling that of 2C-stage embryos, and their discovery and characterization have greatly facilitated the study of early developmental events, such as zygotic genome activation. However, the molecular determinants governing 2C-like reprogramming remains to be elucidated. Here, we show that ZBTB24, CDCA7 and HELLS, components of a molecular pathway that is involved in the pathogenesis of immunodeficiency, centromeric instability and facial anomalies (ICF) syndrome, function as negative regulators of 2C-like reprogramming by maintaining DNA methylation of the Dux cluster, a master inducer of the 2C-like state. Disruption of the ZBTB24-CDCA7-HELLS axis results in Dux hypomethylation and derepression, leading to dramatic upregulation of 2C-specific genes, which can be reversed by site-specific re-methylation in the Dux promoter. We also provide evidence that CDCA7 is enriched at the Dux cluster and recruits the CDCA7-HELLS chromatin remodeling complex to constitutive heterochromatin, perhaps including the perinucleolar heterochromatin, where the Dux cluster resides. Our study uncovers a key role for the ZBTB24-CDCA7-HELLS axis in safeguarding the mESC state by suppressing the 2C-like reprogramming. HA-CDCA7 was stably expressed in Cdca7-knockout (KO) mouse embryonic stem cells (mESCs), and ChIP-seq was performed with HA antibody. Two stables clones (biological replicates), Cdca7_10 and Cdca7_11, were used.