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:To test if there is a physical interaction between the IRF8 promoter and the rs2280381-containing region, we conducted circular chromatin conformation capture assay in the U937 cell. For the IRF8 viewpoint group, we used CSP6I as the first digested enzyme and NlaIII as the second enzyme. For the rs2280381-containing region, we used MboI as the first digested enzyme and NlaIII as the second enzyme. We use 4C-PCR primer to construct IRF8 point view and rs2280381-containing region 4C library.
Project description:To test if lncRNA AC092723.1 play a role in physical interaction between the IRF8 promoter and the rs2280381-containing region, we conducted circular chromatin conformation capture assay in the human primary monocyte. We knock down lncRNA AC092723.1 by electro-transfecting ASOs, the control group is transfected negtive ASOs with no impact on lncRNA AC092723.1.We used CSP6I as the first digested enzyme and NlaIII as the second enzyme. After constructing 4C library,we then utilize 4C-PCR primer to construct IRF8 point view 4C library.
Project description:Long-range interactions of ribososomal DNA (rDNA) identified by 4C-seq in mouse wildtype, premalignant and malignant Eμ-Myc cells and tissue culture adapated Eμ-Myc-shUbtf and Eμ-Myc-LMP (empty vector) cells.
Project description:A switch from MYC expression in bone marrow progenitors to MYCL expression in terminal dendrtitic cell (DC) subsets occurs during DC development. The present study identifies the precise stage during DC development when this switch occurs, and identifies a role for IRF8 in control of this switch. IRF8 is found to be required for both MYC repression and MYCL induction during DC specification in vivo.
Project description:We used RNA-Seq, ChIP-Seq and 4C-Seq to assess the role of MYC in the transcriptional repression induced by DHT in prostate cancer.
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: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 cells frequently depend on chromatin regulatory activities to maintain a malignant phenotype. Here, we show that leukemia cells require the mammalian SWI/SNF chromatin remodeling complex for their survival and aberrant self-renewal potential. While Brg1, an ATPase subunit of SWI/SNF, is known to suppress tumor formation in several cancer types, we found that leukemia cells instead rely on Brg1 to support their oncogenic transcriptional program, which includes Myc as one of its key targets. To account for this context-specific function, we identify a cluster of lineage-specific enhancers located 1.7 megabases downstream of Myc that are occupied by SWI/SNF, as well as the BET protein Brd4. Brg1 is required at these distal elements to maintain transcription factor occupancy and for long-range chromatin looping interactions with the Myc promoter. Notably, these distal Myc enhancers coincide with a region that is focally amplified in 3% of acute myeloid leukemia. Together, these findings define a leukemia maintenance function for SWI/SNF that is linked to enhancer-mediated gene regulation, providing general insights into how cancer cells exploit transcriptional coactivators to maintain oncogenic gene expression programs Enhancer usually regulates its targets through physical contact/interaction. In order to study chromosome conformation of Myc locus and potential distal enhancer E1-E5 region in murine AML cells, we utilize the high resolution 4C-seq and analysis pipeline to search cis elements that physical interact with Myc and E1-E5 region through setting up two individual viewpoints in these two regions.