Project description:The Interferon Regulatory Factors (IRFs) are essential regulators of the innate immune response to viruses. IRFs 3, 5, and 7 drive type-1-interferon and cytokine production in a cell-type and stimulus-specific manner, suggesting regulatory complexity. IRFs 3, 5 and 7 bind DNA as phosphorylation-activated dimers and are classically described as binding a doublet of the canonical IRF binding site: 5'-AANNGAAA-3’. IRF3/5/7 have both common and distinct gene targets and the simple canonical motif does not capture the regulatory complexity of IRF-dependent gene expression. Previous studies, both low and high throughput, have refined our understanding of IRF regulation, yet a systematic comparison of DNA binding preferences for active, dimeric IRF complexes has not been performed. To address this, we designed an IRF-specific, custom protein-binding microarray (PBM) that includes synthetic IRF binding sites as well as type-1-interferon and cytokine promoters. Using constitutively active, phosphomimetic IRF3, 5 and 7 dimers, we find key DNA binding differences for these factors with implications for IRF-dependent gene regulation.
Project description:The interferon regulatory factors IRF3 and IRF7 are key players in the regulation of type I and III IFN genes. In this study, we analyzed the role of IRF3 and IRF7 for the host response to influenza A virus infections in Irf3-/-, Irf7-/- and Irf3-/-Irf7-/- knock-out mice.
Project description:To discover the key determinants of IRF-specific enhancer selection, we identified and characterized IRF binding regions. Using chromatin immunoprecipitation coupled with deep sequencing (ChIP-seq), we mapped the binding regions of IRF3, IRF5, and IRF9 in murine dendritic cells (DCs) stimulated with TLR3 and TLR9 agonists, as well as IFNβ, respectively. We comprehensively analysed the IRF cistromes to identify characteristic features, including DNA motifs for IRFs and other transcription factors, and chromatin status.
Project description:Transcriptomic analyses of pDCs show that the partitioning of TLR/IRF5 and RLR/IRF3 pathways confers differential gene expression and immune cytokine production in pDCs, linking IRF5 with immune regulatory and proinflammatory gene expression.
Project description:To investigate the role of the IRF family in the regulation of interferon stimulated genes, we conducted CRISPR/Cas9 mediated genome editing of Irf3, Irf7 or Irf9 in sgScd2 Th1 cells. We then performed gene expression profiling analysis using data obtained from RNA-seq of control, sgScd2, sgScd2/sgIrf3, sgScd2/sgIrf7 or sgScd2/sgIrf9 Th1 cells.
Project description:Transcription factors IRF3, IRF5 and IRF7 (IRF3/5/7) have overlapping, yet distinct, roles in the mammalian response to pathogens. To examine the role that DNA-binding specificity plays in delineating IRF3/5/7-specific gene regulation we used protein-binding microarrays (PBMs) to characterize the DNA binding of IRF3/5/7 homodimers. We identified both common and dimer-specific DNA binding sites, and show that DNA-binding differences can translate into dimer-specific gene regulation. Central to the antiviral response, IRF3/5/7 regulate type I interferon (IFN) genes. We show that IRF3 and IRF7 bind to many interferon-stimulated response element (ISRE)-type sites in the virus-response elements (VREs) of IFN promoters. However, strikingly, IRF5 does not bind the VREs, suggesting evolutionary selection against IRF5 homodimer binding. Mutational analysis reveals a critical specificity-determining residue that inhibits IRF5 binding to the ISRE-variants present in the IFN gene promoters. Integrating PBM and reporter gene data we find that both DNA-binding affinity and affinity-independent mechanisms determine the function of DNA-bound IRF dimers, suggesting that DNA-based allostery plays a role in IRF binding site function. Our results provide new insights into the role and limitations of DNA-binding affinity in delineating IRF3/5/7-specific gene expression.
Project description:Interferon-regulatory factors (IRFs) are a family of transcription factors (TFs) that play critical roles in translating viral recognition into antiviral responses, including type I IFN production. Dengue virus (DENV) and other clinically important flaviviruses are controlled by functional type I interferon (IFN) responses. Using an experimental model of DENV infection that recapitulates key aspects of the human disease in mice, we demonstrate that while mice lacking the type I IFN receptor (Ifnar1-/-) succumb to DENV infection, mice that are deficient in IRF-3, IRF-5, and IRF-7 – the three transcription factors thought to regulate type I IFN production – survive DENV challenge. Genome-wide RNA-seq analysis of WT, Irf3(-/-)×Irf7(-/-) (DKO), Irf3-/-xIrf5-/-xIrf7-/- (TKO), and Ifnar1-/- (AB6) splenocytes identified minimal type I IFN production but a robust type II IFN (IFN-γ) response in DKO and TKO mice later shown to be dependent on IRF-1. These results reveal a key role for IRF-1 in antiviral defense by activating both type I and II IFN responses during DENV infection.
Project description:Flag-taged IRF3-binding RNAs were analyzed by imprinting RNA-sequencing of anti-flag antibody-retrieved complexes from macrophages lysate.