Core transcription regulatory circuitry orchestrates corneal epithelial homeostasis

Abstract

Adult stem cell identity, plasticity, and homeostasis are precisely orchestrated by lineage-restricted epigenetic and transcriptional regulatory networks. Here, by integrating super-enhancer and chromatin accessibility landscapes, we delineate core transcription regulatory circuitries (CRCs) of limbal stem/progenitor cells (LSCs) and find that RUNX1 and SMAD3 are required for maintenance of corneal epithelial identity and homeostasis. RUNX1 or SMAD3 depletion inhibits PAX6 and induces LSCs to differentiate into epidermal-like epithelial cells. RUNX1, PAX6, and SMAD3 (RPS) interact with each other and synergistically establish a CRC to govern the lineage-specific cis-regulatory atlas. Moreover, RUNX1 shapes LSC chromatin architecture via modulating H3K27ac deposition. Disturbance of RPS cooperation results in cell identity switching and dysfunction of the corneal epithelium, which is strongly linked to various human corneal diseases. Our work highlights CRC TF cooperativity for establishment of stem cell identity and lineage commitment, and provides comprehensive regulatory principles for human stratified epithelial homeostasis and pathogenesis.