Project description:Induction of the transcription factor Irf8 in the common dendritic cell progenitor (CDP) is required for classical type 1 dendritic cell (cDC1) fate specification, but the mechanisms controlling this induction are unclear. Here we identified Irf8 enhancers and used CRISPR/Cas9 genome editing to assess their roles in Irf8 regulation. An enhancer 32 kilobases downstream of the Irf8 transcriptional start site (+32 kb Irf8) that was active in mature cDC1s was required for the development of this lineage, but not for its specification. Instead, a +41 kb Irf8 enhancer previously thought to be active only in plasmacytoid DCs (pDCs) was found to also be transiently accessible in cDC1 progenitors. Deletion of this enhancer reduced Irf8 expression in pDCs as expected, but also surprisingly prevented the induction of Irf8 in CDPs and abolished cDC1 specification. Thus, cryptic activation of the +41 kb Irf8 enhancer in DC progenitors is responsible for cDC1 fate specification.
Project description:To compare the gene expression profiles of Macrophage & Dendritic cell Progenitors (MDPs), Common Dendritic cell Progenitors (CDPs), committed dendritic cell precursors (pre-DCs), and Ly6Chi monocytes from mouse bone marrow Four samples (MDPs, CDPs, pre-DCs, and monocytes) were collected in triplicate
Project description:During hematopoiesis, cells originating from the same stem cell reservoir differentiate into distinct cell types. The mechanisms enabling common progenitors to differentiate into distinct cell fates are not fully understood. Here, we identify chromatin-regulating and cell-fate-determining transcription factors (TF) governing dendritic cell (DC) development by annotating the enhancer and promoter landscapes of the DC lineage. Combining these analyses with detailed over-expression, knockdown and ChIP-Seq studies, we show that Irf8 functions as a plasmacytoid DC epigenetic and fate-determining TF, regulating massive, cell-specific chromatin changes in thousands of pDC enhancers. Importantly, Irf8 forms a negative feedback loop with Cebpb, a monocyte-derived DC epigenetic fate-determining TF. We show that using this circuit logic, differential activity of TF can stably define epigenetic and transcriptional states, regardless of the microenvironment. More broadly, our study proposes a general paradigm that allows closely related cells with a similar set of signal-dependent factors to generate differential and persistent enhancer landscapes. Here we profiled accessible chromatin of moDC and pDC using ATAC-seq assay, developed by Buenrostro et al. (2013)
Project description:We have used ATAC-seq to track cell state changes that occur during the differentiation of mouse embryonic stem cells to defined neural progenitor fates. We have performed ATAC-seq every 24 hours in cells en route to 3 distinct neural progenitors fates, anterior, hindbrain and spinal cord. This has allowed us to define how cells transition to a neural state, based on their enhancer usage. We identified regions distinct to different anterior-posterior neural progenitors, and validated their relevance by performing in vivo ATAC-seq on neural progenitors isolated from different axial levels of mouse embryos.