Project description:The transcription factor IRF8 is a critical regulator of plasmacytoid dendritic cell (pDC) and classical dendritic cell (cDC) development in both mouse and man. Yet the downstream molecular targets that regulate DC homeostasis and development are largely unknown. A recent study using gene expression analysis of IRF8-deficient myeloid and lymphoid progenitors identified the Myc paralog Mycl1 as a potential transcriptional target of IRF8. We report here that Mycl1 is a mediator of DC homeostasis at steady state and during inflammation, and its expression is regulated by IRF8 in multiple DC lineages. We have further validated these observations with ChIP-Seq of IRF8 binding to the Mycl1 locus. Notably, IRF8 binding to Mycl1 locus is independent of an interaction with the AP1 factor, BATF3. Additionally, our genome-wide survey of IRF8 binding identified both EICE and AICE motifs. Examination of IRF8 binding in dendritic cells
Project description:The transcription factor (TF) interferon regulatory factor 8 (IRF8) controls both developmental and inflammatory stimulus-inducible genes in macrophages, but the mechanisms underlying these two different functions are largely unknown. One possibility is that these different roles are linked to the ability of IRF8 to bind alternative DNA sequences. We found that IRF8 is recruited to distinct sets of DNA consensus sequences before and after lipopolysaccharide (LPS) stimulation. In resting cells, IRF8 was mainly bound to composite sites together with the master regulator of myeloid development PU.1. Basal IRF8M-bM-^@M-^SPU.1 binding maintained the expression of a broad panel of genes essential for macrophage functions (such as microbial recognition and response to purines) and contributed to basal expression of many LPS-inducible genes. After LPS stimulation, increased expression of IRF8, other IRFs, and AP-1 family TFs enabled IRF8 binding to thousands of additional regions containing low-affinity multimerized IRF sites and composite IRFM-bM-^@M-^SAP-1 sites, which were not premarked by PU.1 and did not contribute to the basal IRF8 cistrome. While constitutively expressed IRF8-dependent genes contained only sites mediating basal IRF8/PU.1 recruitment, inducible IRF8-dependent genes contained variable combinations of constitutive and inducible sites. Overall, these data show at the genome scale how the same TF can be linked to constitutive and inducible gene regulation via distinct combinations of alternative DNA-binding sites. Chromatin immuno-precipitations of transcription factors IRF8, IRF1, PU.1, STAT1, STAT2 and of H3 lysine 27 acetylated followed by multiparallel sequencing, performed in bone marrow-derived macrophages from wild type (WT) and BXH2/TyJ mice. Cells were treated with lipopolysaccharide (LPS) for 2 or 4 hours, or interferon b (IFNb) for 30 or 60 minutes, 2 or 4 hours, or left unstimulated.
Project description:We describe an assay for transposase-accessible chromatin using sequencing (ATAC-seq), based on direct in vitro transposition of sequencing adaptors into native chromatin, as a rapid and sensitive method for integrative epigenomic analysis. ATAC-seq captures open chromatin sites using a simple two-step protocol with 1000–50,000 cells and reveals the interplay between genomic locations of open chromatin, DNA-binding proteins, individual nucleosomes and chromatin compaction at nucleotide resolution. We discovered classes of DNA-binding factors that strictly avoided, could tolerate or tended to overlap with the nucleosome. Using ATAC-seq maps of chromatin accessibility in Irf8+/+ and Irf8-/- LT-HSC cells, we demonstrated the genome-wide activity of cis-regulatory elements (CREs) perturbation in IRF8 deficient mice bone marrow LT-HSC.
Project description:The role of the lineage-determining transcription factor Interferon regulatory factor 8 (IRF8) in microglia remains elucidated. Here we report the genome-wide IRF8 binding profiles in microglia at various ages. CUT&RUN methodology revealed that IRF8 starts to bind to the genome around postnatal day 9 (P9), and its number increases with age. In comparison to peritoneal macrophages, microglia IRF8 showed a cell-intrinsic binding pattern. By co-occurrence analysis, most IRF8 was H3K4me1/H3K27ac-marked enhancers, and many of them bind to the H3K27ac(high) super-enhancer regions. In IRF8KO microglia, H3K4me1 and H3K27ac profiles were altered and deposited aberrantly on the genome. This study provides a novel insight into understanding epigenetic regulation in microglia.
Project description:The transcription factor (TF) interferon regulatory factor 8 (IRF8) controls both developmental and inflammatory stimulus-inducible genes in macrophages, but the mechanisms underlying these two different functions are largely unknown. One possibility is that these different roles are linked to the ability of IRF8 to bind alternative DNA sequences. We found that IRF8 is recruited to distinct sets of DNA consensus sequences before and after lipopolysaccharide (LPS) stimulation. In resting cells, IRF8 was mainly bound to composite sites together with the master regulator of myeloid development PU.1. Basal IRF8–PU.1 binding maintained the expression of a broad panel of genes essential for macrophage functions (such as microbial recognition and response to purines) and contributed to basal expression of many LPS-inducible genes. After LPS stimulation, increased expression of IRF8, other IRFs, and AP-1 family TFs enabled IRF8 binding to thousands of additional regions containing low-affinity multimerized IRF sites and composite IRF–AP-1 sites, which were not premarked by PU.1 and did not contribute to the basal IRF8 cistrome. While constitutively expressed IRF8-dependent genes contained only sites mediating basal IRF8/PU.1 recruitment, inducible IRF8-dependent genes contained variable combinations of constitutive and inducible sites. Overall, these data show at the genome scale how the same TF can be linked to constitutive and inducible gene regulation via distinct combinations of alternative DNA-binding sites.
Project description:The transcription factor IRF8 is a critical regulator of plasmacytoid dendritic cell (pDC) and classical dendritic cell (cDC) development in both mouse and man. Yet the downstream molecular targets that regulate DC homeostasis and development are largely unknown. A recent study using gene expression analysis of IRF8-deficient myeloid and lymphoid progenitors identified the Myc paralog Mycl1 as a potential transcriptional target of IRF8. We report here that Mycl1 is a mediator of DC homeostasis at steady state and during inflammation, and its expression is regulated by IRF8 in multiple DC lineages. We have further validated these observations with ChIP-Seq of IRF8 binding to the Mycl1 locus. Notably, IRF8 binding to Mycl1 locus is independent of an interaction with the AP1 factor, BATF3. Additionally, our genome-wide survey of IRF8 binding identified both EICE and AICE motifs.
Project description:IThe transcription factor (TF) interferon regulatory factor 8 (IRF8) controls both developmental and inflammatory stimulus-inducible genes in macrophages, but the mechanisms underlying these two different functions are largely unknown. One possibility is that these different roles are linked to the ability of IRF8 to bind alternative DNA sequences. We found that IRF8 is recruited to distinct sets of DNA consensus sequences before and after lipopolysaccharide (LPS) stimulation. In resting cells, IRF8 was mainly bound to composite sites together with the master regulator of myeloid development PU.1. Basal IRF8–PU.1 binding maintained the expression of a broad panel of genes essential for macrophage functions (such as microbial recognition and response to purines) and contributed to basal expression of many LPS-inducible genes. After LPS stimulation, increased expression of IRF8, other IRFs, and AP-1 family TFs enabled IRF8 binding to thousands of additional regions containing low-affinity multimerized IRF sites and composite IRF–AP-1 sites, which were not premarked by PU.1 and did not contribute to the basal IRF8 cistrome. While constitutively expressed IRF8-dependent genes contained only sites mediating basal IRF8/PU.1 recruitment, inducible IRF8-dependent genes contained variable combinations of constitutive and inducible sites. Overall, these data show at the genome scale how the same TF can be linked to constitutive and inducible gene regulation via distinct combinations of alternative DNA-binding sites.