Project description:Type 1 classical dendritic cells (cDC1s) development requires the transcription factor IRF8, and IRF8 mutations cause severe combined immunodeficiency, including disseminated bacille Calmette-Guérin (BCG) disease. IRF8 regulated enhancers are required for Irf8 expression in early DC progenitors and mature cDC1s. The E-protein-dependent +41 kb enhancer gains accessibility and activates transcription in common DC progenitors (CDPs), and its depletion abrogated pre-cDC1s specification. The Batf3-dependent +32 kb enhancer gains accessibility and activates transcription in pre-cDC1 progenitors, and its depletion impaired cDC1 maturation. The +32 kb Irf8 enhancer locus bears an enhancer transcript, and the production of enhancer RNA (eRNA) Gm39266 is dependent on +41 kb Irf8 enhancer. It was unclear whether the +32 kb and +41 kb enhancers act independently or cooperate to regulate Irf8 expression. We dissected the mechanisms using +32/+41 compound heterozygous mice, and found that while the +41 kb enhancer suffices for pre-cDC1 progenitor specification, the +32 kb and +41 kb enhancers must reside on one allele to support cDC1 maturation. The +41 kb enhancer cis-regulates chromatin accessibility and BATF3 binding at +32 kb enhancer, independent of eRNA Gm39266 transcripts or transcription across +32 kb Irf8 enhancer.
Project description:Type 1 classical dendritic cells (cDC1s) development requires the transcription factor IRF8, and IRF8 mutations cause severe combined immunodeficiency, including disseminated bacille Calmette-Guérin (BCG) disease. IRF8 regulated enhancers are required for Irf8 expression in early DC progenitors and mature cDC1s. The E-protein-dependent +41 kb enhancer gains accessibility and activates transcription in common DC progenitors (CDPs), and its depletion abrogated pre-cDC1s specification. The Batf3-dependent +32 kb enhancer gains accessibility and activates transcription in pre-cDC1 progenitors, and its depletion impaired cDC1 maturation. The +32 kb Irf8 enhancer locus bears an enhancer transcript, and the production of enhancer RNA (eRNA) Gm39266 is dependent on +41 kb Irf8 enhancer. It was unclear whether the +32 kb and +41 kb enhancers act independently or cooperate to regulate Irf8 expression. We dissected the mechanisms using +32/+41 compound heterozygous mice, and found that while the +41 kb enhancer suffices for pre-cDC1 progenitor specification, the +32 kb and +41 kb enhancers must reside on one allele to support cDC1 maturation. The +41 kb enhancer cis-regulates chromatin accessibility and BATF3 binding at +32 kb enhancer, independent of eRNA Gm39266 transcripts or transcription across +32 kb Irf8 enhancer.
Project description:Classical type 1 dendritic cells (cDC1s) are required for antiviral and antitumor immunity, which necessitates an understanding of their development. Development of the cDC1 progenitor requires an E-protein-dependent enhancer located 41 kilobases downstream of the transcription start site of the transcription factor Irf8 (+41-kb Irf8 enhancer), but its maturation instead requires the Batf3-dependent +32-kb Irf8 enhancer. To understand this switch, we performed single-cell RNA sequencing of the common dendritic cell progenitor (CDP) and identified a cluster of cells that expressed transcription factors that influence cDC1 development, such as Nfil3, Id2 and Zeb2. Genetic epistasis among these factors revealed that Nfil3 expression is required for the transition from Zeb2hi and Id2lo CDPs to Zeb2lo and Id2hi CDPs, which represent the earliest committed cDC1 progenitors. This genetic circuit blocks E-protein activity to exclude plasmacytoid dendritic cell potential and explains the switch in Irf8 enhancer usage during cDC1 development.
