DOT1L is essential for corneal epithelial identity and homeostasis

Epigenetic regulation is critical for corneal homeostasis, yet the role of histone methyltransferase DOT1L, the sole enzyme catalyzing H3K79 methylation, remains unexplored. Here, we show that DOT1L is indispensable for corneal epithelial differentiation, postnatal development, and wound healing.

Using conditional knockout mice (Dot1lflox/flox; K14-Cre), we find that DOT1L deficiency causes progressive corneal opacification, squamous metaplasia, and pathological angiogenesis. Immunofluorescence and histochemical analyses reveal that DOT1L deficiency impedes corneal epithelial differentiation, consequently inhibiting both postnatal corneal development and wound-induced corneal repair. Single-cell RNA sequencing of WT and Dot1l-KO corneas demonstrates that DOT1L loss disrupts the LSC-to-superficial-cell differentiation trajectory, and identifies Pax6, the master regulator of corneal epithelial identity, as one of the differentially expressed genes.