Project description:To understand the differentiation program in monocyte/macrophage differentiation, we performed ChIP-seq for IRF8 and H3K4me1 together with gene expression profiling during IRF8-induced monocyte differentiation. Both promoter-proximal and -distal binding of IRF8 associated with induction of the genes especially those related to monocytes/macrophages and immunity. DNA motif analysis for cis-regulatory elements of indirect IRF8 target genes predicted KLF4, essential for Ly6C+ monocyte development, to be a downstream transcription factor regulating the indirect target gene expression. Introduction of KLF4 into an Irf8-/- myeloid progenitor cell line induced a subset of IRF8 target genes and partially induced monocyte/macrophage differentiation. Together, this study revealed the genome-wide behavior of IRF8 and the IRF8-KLF4 axis during monocyte differentiation. Gene expressions in monocyte-like cells differentiated by IRF8 or KLF4 were measured at day 4 after retroviral transductions to myeloid progenitor cell line, Tot2. Two independent experiments were performed.
Project description:To understand the differentiation program in monocyte/macrophage differentiation, we performed ChIP-seq for IRF8 and H3K4me1 together with gene expression profiling during IRF8-induced monocyte differentiation. Both promoter-proximal and -distal binding of IRF8 associated with induction of the genes especially those related to monocytes/macrophages and immunity. DNA motif analysis for cis-regulatory elements of indirect IRF8 target genes predicted KLF4, essential for Ly6C+ monocyte development, to be a downstream transcription factor regulating the indirect target gene expression. Introduction of KLF4 into an Irf8-/- myeloid progenitor cell line induced a subset of IRF8 target genes and partially induced monocyte/macrophage differentiation. Together, this study revealed the genome-wide behavior of IRF8 and the IRF8-KLF4 axis during monocyte differentiation.
Project description:To understand the mechanism underlying monocyte and dendritic cell development through the regulation of Irf8 expression by the 56 kb downstream (+56 kb) Irf8 enhancer, we performed epigenetic profiling of bone marrow cells and splenocytes from wild-type, the Irf8 +56 kb enhancer-deficient, and IRF8-deficient mice. Taken together with the transcriptome analysis of mononuclear phagocyte lineage cells in these mice, the Irf8 +56 kb enhancer-mediated high Irf8 expression in hematopoietic progenitor cells promote type 1 classical dendritic cell (cDC1) differentiation, while low Irf8 expression in progenitors led to Ly6C+ monocyte development. In addition, IRF8 ChIP-seq of mature cDC1s and monocytes suggested that IRF8 regulates enhancers in cooperation with different transcription factors in each lineage in its expression level.
Project description:To understand the mechanism underlying monocyte and dendritic cell development through the regulation of Irf8 expression by the 56 kb downstream (+56 kb) Irf8 enhancer, we performed transcriptome analysis of bone marrow cells and splenocytes from wild-type, the Irf8 +56 kb enhancer-deficient, and IRF8-deficient mice. Taken together with the epigenetic profiling of mononuclear phagocyte lineage cells in these mice, the Irf8 +56 kb enhancer-mediated high Irf8 expression in hematopoietic progenitor cells promote type 1 classical dendritic cell (cDC1) differentiation, while low Irf8 expression in progenitors led to Ly6C+ monocyte development.
Project description:Chromatins were prepared from myeloid progenitor cell line Tot2 cells transduced with retrovirus for control MSCV or MSCV-IRF8. Chromatin immunoprecipitation (ChIP) was carried out by using anti-IRF8 antibody, anti-PU.1 antibody or anti-histone H3K4me1 antibody. ChIP-Seq peaks were identified using the FindPeaks tool in the HOMER package or SICER with input DNA tags as background distribution. Potential IRF8-direct target genes were identified based on ChIP-Seq and the alteration of expression by IRF8-induction. Examination of 2 transcription factor occupancy and 1 histone modifications in myeloid progenitor cells and monocyte-like cells differetiated by IRF8 expression
Project description:Currently, it is unclear if all monocyte subsets exhibit osteoclastogenic potential. Furthermore, the role of lineage determining TFs in regulating OC differentiation on a genome-wide scale remains poorly understood. In this study, we utilized a novel Irf8 conditional knockout (Irf8 cKO) mouse model to characterize the importance of IRF8 in OC progenitor development and epigenetic regulation of OC differentiation. To identify global transcriptional program governing the osteoclastogenic potential of Ly6Chi, Ly6Cint, and Ly6C– monocytes, and how it may be further influenced by IRF8 deficiency, we performed RNA-seq on sorted Ly6Chi, Ly6Cint, and Ly6C– cells from WT and Irf8 cKO mice. Cells were analyzed prior to (BMMs) and 4 days after RANKL stimulation (OCs). Here we show that WT Ly6Chi and Ly6Cint monocytes developmentally contain OC-specific transcripts, which are augmented upon RANKL stimulation. Additionally, in the absence of IRF8, OC-specific transcripts in all three monocyte subsets are primed to robustly respond to RANKL stimulation.
Project description:Currently, it is unclear if all monocyte subsets exhibit osteoclastogenic potential. Furthermore, the role of lineage determining TFs in regulating OC differentiation on a genome-wide scale remains poorly understood. In this study, we utilized a novel Irf8 conditional knockout (Irf8 cKO) mouse model to characterize the importance of IRF8 in OC progenitor development and epigenetic regulation of OC differentiation. We performed RNA-seq on Irf8 gWT, gKO, cWT and cKO BMMs, preosteoclasts (PreOCs), and OCs. Cells were analyzed prior to (BMMs) and 3 days (PreOCs) and 6 days (OCs) after RANKL stimulation. Here we show that greater a number of genes are significantly upregulated in Irf8 cKO OCs when compared to WT and Irf8 gKO OCs. Altogether, our data shows that Irf8 cKO mice provide more precise/reliable OC-specific transcriptomic results when compared to Irf8 gKO mice.
Project description:Alterations in myelopoiesis are common across various tumor types, resulting in immature populations termed myeloid-derived suppressor cells (MDSCs). MDSC burden correlates with poorer clinical outcomes, credited to their ability to suppress antitumor immunity. MDSCs consist of two major subsets, monocytic and polymorphonuclear (PMN). Intriguingly, the latter subset predominates in many patients and tumor models, though the mechanisms favoring PMN-MDSC responses remain poorly understood. Ordinarily, lineage-restricted transcription factors regulate myelopoiesis that collectively dictate cell fate. One integral player is interferon regulatory factor-8 (IRF8), which promotes monocyte/dendritic cell differentiation while limiting granulocyte development. We recently showed that IRF8 inversely controls MDSC burden in tumor models, particularly the PMN-MDSC subset. However, where IRF8 acts in the pathway of myeloid differentiation to influence PMN-MDSC production has remained unknown. Here, we showed that: 1) tumor growth was strongly associated with a selective expansion of newly defined IRF8lo granulocytic progenitors (GPs); 2) tumor-derived GPs had an increased ability to form PMN-MDSCs; 3) tumor-derived GPs shared gene expression patterns with IRF8-/- GPs, suggesting that IRF8 loss underlies GP expansion; and 4) enforced IRF8 overexpression in vivo selectively constrained tumor-induced GP expansion. These findings support the hypothesis that PMN-MDSCs result from selective expansion of IRF8lo GPs, and that strategies targeting IRF8 expression may limit their load to improve immunotherapy efficacy.