Single-cell transcriptomics defines Dot1L interacting partners and downstream target genes in the mouse molar dental pulp

Although histone methyltransferases are implicated in many key developmental processes, the contribution of individual chromatin modifiers in dental tissues is not well understood. Using single-cell RNA sequencing, we examined the expression profiles of the disruptor of telomeric silencing 1-like ( gene in the postnatal day 5 mouse molar dental pulp. Dot1L is the only known enzyme that methylates histone 3 on lysine 79, a modification associated with gene expression. Our research revealed 15 distinct clusters representing different populations of mesenchymal stromal cells (MSCs), immune cells, pericytes, ameloblasts and endothelial cells. We documented heterogeneity in gene expression across different subpopulations of MSCs, a good indicator that these stromal progenitors undergo different phases of osteogenic differentiation. Interestingly, although was broadly expressed across all cell clusters within the molar dental pulp, our analyses indicated specific enrichment of within two clusters of MSCs, as well as cell clusters characterized as ameloblasts and endothelial cells. Moreover, we detected co-expression with protein interactors involved in epigenetic activation such as and . In addition, was co-expressed with , and , which encode epigenetic factors associated with gene silencing and heterochromatin formation. was co-expressed with downstream targets of the insulin growth factor and WNT signaling pathways, as well as genes involved in cell cycle progression. Collectively, our results suggest that Dot1L may play key roles in orchestrating lineage-specific gene expression during MSC differentiation.