Project description:Cancer cell type-selective addiction of transcription-chromatin regulatory program provides opportunities for therapeutic interventions. Here, we uncovered an IRF8-MEF2D transcription factor (TF) regulatory circuit as an acute myeloid leukemia (AML)-biased dependency. Combining CRISPR-based genetic screens, transcriptional analysis, and chromatin profiling, we demonstrated that a chromatin regulator, ZMYND8, directly regulates IRF8 and MYC expression through occupying AML-specific enhancer regions. ZMYND8 was essential for AML proliferation both in vitro and in vivo. The ZMYND8-occupied IRF8 enhancer was further characterized using Circular Chromosome Conformation Capture and CRISPRi-based perturbation assays and was observed in primary patient cells. Importantly, mutagenesis experiments revealed that the PHD/Bromodomain/PWWP reader module is required for ZMYND8 tethering to leukemia-essential co-activator BRD4 for enhancer-mediated gene regulation. Our results rationalize ZMYND8 as a potential selective therapeutic target for modulating the IRF8/MYC transcriptional networks in AML.
Project description:Cancer cell type-selective addiction of transcription-chromatin regulatory program provides opportunities for therapeutic interventions. Here, we uncovered an IRF8-MEF2D transcription factor (TF) regulatory circuit as an acute myeloid leukemia (AML)-biased dependency. Combining CRISPR-based genetic screens, transcriptional analysis, and chromatin profiling, we demonstrated that a chromatin regulator, ZMYND8, directly regulates IRF8 and MYC expression through occupying AML-specific enhancer regions. ZMYND8 was essential for AML proliferation both in vitro and in vivo. The ZMYND8-occupied IRF8 enhancer was further characterized using Circular Chromosome Conformation Capture and CRISPRi-based perturbation assays and was observed in primary patient cells. Importantly, mutagenesis experiments revealed that the PHD/Bromodomain/PWWP reader module is required for ZMYND8 tethering to leukemia-essential co-activator BRD4 for enhancer-mediated gene regulation. Our results rationalize ZMYND8 as a potential selective therapeutic target for modulating the IRF8/MYC transcriptional networks in AML.
Project description:Personalized treatment of acute myeloid leukemia (AML) that target individual aberrations strongly improved the survival of AML patients. However, AML is still one of the most lethal cancer diseases of the 21st century, demonstrating the need to find novel drug targets and to explore alternative treatment strategies. Upon investigation of public perturbation data, we identified the transcription factor IRF8 as a novel AML-specific susceptibility gene in humans. IRF8 is upregulated in a subset of AML cells and its deletion leads to impaired proliferation in those cells. Consistently, high IRF8 expression is associated with poorer patients’ prognoses. Combining gene expression changes upon IRF8 deletion and the genome-wide localization of IRF8 in the AML cell line MV4-11, we demon-strate that IRF8 directly regulates key signaling molecules, such as the kinases SRC and FAK, the transcription factors RUNX1 and IRF5, and the cell cycle regulator Cyclin D1. IRF8 loss impairs AML-driving signaling pathways, including the WNT, Chemokine, and VEGF signaling pathways. Additionally, many members of the focal adhesion pathway showed reduced expression, providing a putative link between high IRF8 expression and poor prognosis. Thus, this study suggests that IRF8 could serve as a biomarker and potential molecular target in a subset of human AMLs.
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:Cancer cell type-selective addiction of transcription-chromatin regulatory program provides opportunities for therapeutic interventions. Here, we uncovered an IRF8-MEF2D transcription factor (TF) regulatory circuit as an acute myeloid leukemia (AML)-biased dependency. Combining CRISPR-based genetic screens, transcriptional analysis, and chromatin profiling, we demonstrated that a chromatin regulator, ZMYND8, directly regulates IRF8 and MYC expression through occupying AML-specific enhancer regions. ZMYND8 was essential for AML proliferation both in vitro and in vivo. The ZMYND8-occupied IRF8 enhancer was further characterized using Circular Chromosome Conformation Capture and CRISPRi-based perturbation assays and was observed in primary patient cells. Importantly, mutagenesis experiments revealed that the PHD/Bromodomain/PWWP reader module is required for ZMYND8 tethering to leukemia-essential co-activator BRD4 for enhancer-mediated gene regulation. Our results rationalize ZMYND8 as a potential selective therapeutic target for modulating the IRF8/MYC transcriptional networks in AML.
Project description:Cancer cell type-selective addiction of transcription-chromatin regulatory program provides opportunities for therapeutic interventions. Here, we uncovered an IRF8-MEF2D transcription factor (TF) regulatory circuit as an acute myeloid leukemia (AML)-biased dependency. Combining CRISPR-based genetic screens, transcriptional analysis, and chromatin profiling, we demonstrated that a chromatin regulator, ZMYND8, directly regulates IRF8 and MYC expression through occupying AML-specific enhancer regions. ZMYND8 was essential for AML proliferation both in vitro and in vivo. The ZMYND8-occupied IRF8 enhancer was further characterized using Circular Chromosome Conformation Capture and CRISPRi-based perturbation assays and was observed in primary patient cells. Importantly, mutagenesis experiments revealed that the PHD/Bromodomain/PWWP reader module is required for ZMYND8 tethering to leukemia-essential co-activator BRD4 for enhancer-mediated gene regulation. Our results rationalize ZMYND8 as a potential selective therapeutic target for modulating the IRF8/MYC transcriptional networks in AML.
Project description:Transcriptional dysregulation is a prominent feature in leukemia. Here, we systematically surveyed the transcription factor (TF) vulnerabilities in leukemia, and uncovered TF clusters that exhibit context-specific addictions within and between different subtypes of leukemia. We focused on and validated MEF2D as a requirement exclusively in AML with high IRF8 expression. Transcriptomic and chromatin-binding profiling revealed a key TF circuit composed of MEF2D-IRF8 vital for AML maintenance. AML can acquire dependence on this circuit through various mechanisms, including enhancer activation of the circuit via MLL-rearrangement. IRF8 cooperates with PU.1 to control PU.1/MEIS1 co-regulated transcriptional outputs, meanwhile coordinating with MEF2D to directly regulate genes in a non-redundant manner. Collectively, our study nominates a TF circuit in support of the pathogenesis of AML.
Project description:Transcriptional dysregulation is a prominent feature in leukemia. Here, we systematically surveyed the transcription factor (TF) vulnerabilities in leukemia, and uncovered TF clusters that exhibit context-specific addictions within and between different subtypes of leukemia. We focused on and validated MEF2D as a requirement exclusively in AML with high IRF8 expression. Transcriptomic and chromatin-binding profiling revealed a key TF circuit composed of MEF2D-IRF8 vital for AML maintenance. AML can acquire dependence on this circuit through various mechanisms, including enhancer activation of the circuit via MLL-rearrangement. IRF8 cooperates with PU.1 to control PU.1/MEIS1 co-regulated transcriptional outputs, meanwhile coordinating with MEF2D to directly regulate genes in a non-redundant manner. Collectively, our study nominates a TF circuit in support of the pathogenesis of AML.
Project description:Transcriptional dysregulation is a prominent feature in leukemia. Here, we systematically surveyed the transcription factor (TF) vulnerabilities in leukemia, and uncovered TF clusters that exhibit context-specific addictions within and between different subtypes of leukemia. We focused on and validated MEF2D as a requirement exclusively in AML with high IRF8 expression. Transcriptomic and chromatin-binding profiling revealed a key TF circuit composed of MEF2D-IRF8 vital for AML maintenance. AML can acquire dependence on this circuit through various mechanisms, including enhancer activation of the circuit via MLL-rearrangement. IRF8 cooperates with PU.1 to control PU.1/MEIS1 co-regulated transcriptional outputs, meanwhile coordinating with MEF2D to directly regulate genes in a non-redundant manner. Collectively, our study nominates a TF circuit in support of the pathogenesis of AML.