H3K9me3 controls epidermis development by repressing RNA Pol II activity on key promoters and enhancers

Here, we show that H3K9me3 deposition is dynamic during epidermis morphogenesis and essential for lineage diversification. We ablate Suv39h1, Suv39h2, and Setdb1 histone methyltransferases, in the embryonic mouse epidermis, to induce H3K9me3 loss.

This causes complete failure of keratinocyte differentiation, skin barrier formation, hair follicle development, and Merkel cell specification. Single-cell transcriptomics reveals aberrant cell fates with mixed epidermal subtype identities and dysregulated non-lineage and lineage-specific transcription programs. Affected pathways include differentiation, metabolism, cell cycle, cytoskeletal organization, and extracellular matrix.