Project description:Chromosomal rearrangements are a frequent cause of oncogene deregulation in human malignancies. Overexpression of EVI1 is found in a subgroup of acute myeloid leukemia (AML) with 3q26 chromosomal rearrangements which are often therapy resistant. In a cohort of primary t(3;8)(q26;q24) AML samples we observed the translocation of a MYC super-enhancer to EVI1. We generated a patient-based t(3;8)(q26;q24) model in vitro using CRISPR-Cas9 technology and demonstrated hyper-activation of EVI1 by the hijacked MYC super-enhancer. One MYC super-enhancer element in particular, which recruits early hematopoietic regulators, is critical for EVI1 expression and enhancer-promoter interaction. This interaction is facilitated by a CTCF-bound motif upstream of the EVI1 promoter that acts as an enhancer-docking site in t(3;8) AML. Genomic analyses of 3q26-rearranged AML samples point to a common mechanism by which EVI1 uses this CTCF-bound enhancer-docking site to hijack early hematopoietic enhancers.
Project description:Chromosome Conformation Capture Sequencing (4C-seq) was performed to assess interaction between the MYC super-enhancer and the EVI1 promoter under different conditions. Sample preparation was performed as previously described (van de Werken et al., 2012). In short, genomic regions that are spatially proximal in the cell nucleus were fixated by formaldehyde-induced crosslinks. The DNA was fragmented with DpnII as a primary restriction enzyme, Csp6I as a secondary 4 bp-cutter. To identify and quantify fragments that were ligated to the genomic region of interest, a two-step PCR was performed as previously described (Krijger et al., 2020). In the second PCR step, universal primers were used that contain the Illumina adapters. The amplicons were analyzed using next generation sequencing on the IIlumina NovaSeq platform.
Project description:Super-enhancers may regulate target genes through chromatin looping. We connected super-enhancers in the K562 chronic myelogenous leukemia cell line with chromatin interactions identified from Chromatin Interaction Analysis with Paired-End Tag (ChIA-PET) data. Gene expression at proximal elements that are connected with distal super-enhancers showed significantly higher cell-type specificity than at proximal elements connected with other elements or not involved in interaction. 4C and Episwitch analysis of chromatin interactions showed that certain chromatin interactions are cell-specific, but others are more general. While super-enhancers upstream of c-MYC at the MYC-335 element can be found in other cancers, only super-enhancers downstream of c-MYC can be found in K562. 4C analysis of the c-MYC promoter revealed no chromatin interactions that are directed upstream of c-MYC, but only downstream of c-MYC, in the PVT1 long non-coding RNA gene. Cell-specific usage of super-enhancers could explain why the MYC-335 element that is associated with many solid cancers such as colorectal cancer and breast cancer, but not with leukemia. Surprisingly, we found that a chromatin interaction between c-MYC and a c-MYC super-enhancer is lost in chronic myelogenous leukemia patient blood as compared with blood from individuals without the disease through Oxford Biodynamicsâ?? Episwitch analysis. These results provide evidence for fine-tuning of expression patterns, such as cell-specific regulation of target genes by distal super-enhancers through chromatin interactions and an association between chromatin interactions and disease, and highlight that super-enhancers are more complex than previously described. Examination of several chromatin interactions involving super-enhancers using 4C-Seq and Episwitch (TM)
Project description:To infer enhancers and super enhancers in Acute Myeloid Leukemia (AML) Cell lines with a 3q-aberration we determined regions enriched for H3K27AC, H3K4ME3, H3K4ME1, P300, and BRD4 in MOLM1. Additionally we determined regions enriched for P300 and BRD4 in the cell line Mutz3 which also harbors a 3q-aberration. As an control we performed Chip-Seq to determine enrichment for BRD4 in K562, which overexpresses the proto-oncogene EVI1, but has no apparent 3q-aberration. Ultimately, the ChipSeq experiments were utilized to infer which enhancer or super enhancer drives the overexpression of EVI1 in AMLs with a 3q-aberration. Finally, the effect of the compound JQ1 on the inferred super enhancers and the overexpression of EVI1 is tested by treating the cell line MOLM1 for 6 hours and determining the residual binding of BRD4.
Project description:To determine whether a TP63/KLF5-regulated super-enhancer region can impact SREBF1 transcription, circularized chromosome conformation capture (4C) assays were performed. 4C assays identified complex, extensive interactions between the SREBF1 promoter and the super-enhancer region Moreover, these DNA-DNA contacts were strictly confined within the super-enhancer region, highlighting the specificity of chromatin interactions
Project description:Super-enhancers may regulate target genes through chromatin looping. We connected super-enhancers in the K562 chronic myelogenous leukemia cell line with chromatin interactions identified from Chromatin Interaction Analysis with Paired-End Tag (ChIA-PET) data. Gene expression at proximal elements that are connected with distal super-enhancers showed significantly higher cell-type specificity than at proximal elements connected with other elements or not involved in interaction. 4C and Episwitch analysis of chromatin interactions showed that certain chromatin interactions are cell-specific, but others are more general. While super-enhancers upstream of c-MYC at the MYC-335 element can be found in other cancers, only super-enhancers downstream of c-MYC can be found in K562. 4C analysis of the c-MYC promoter revealed no chromatin interactions that are directed upstream of c-MYC, but only downstream of c-MYC, in the PVT1 long non-coding RNA gene. Cell-specific usage of super-enhancers could explain why the MYC-335 element that is associated with many solid cancers such as colorectal cancer and breast cancer, but not with leukemia. Surprisingly, we found that a chromatin interaction between c-MYC and a c-MYC super-enhancer is lost in chronic myelogenous leukemia patient blood as compared with blood from individuals without the disease through Oxford Biodynamics’ Episwitch analysis. These results provide evidence for fine-tuning of expression patterns, such as cell-specific regulation of target genes by distal super-enhancers through chromatin interactions and an association between chromatin interactions and disease, and highlight that super-enhancers are more complex than previously described.
Project description:We examined the effects of targeting the GATA2 super-enhancer on EVI1 expression in MUTZ3. To that end, we conducted genome editing with CRISPR and assessed H3K27 acetylation with Cut&Run. The protocol described by the Henikoff group was used to generate these data.
Project description:Open chromatin regions in the MYC super-enhancer region were investigated by ATAC-seq in t(3;8) AML. ATAC-seq was performed as described (Buenrostro et al, 2013) with a modification in the lysis buffer (0.30 M sucrose, 10 mM Tris pH 7.5, 60 mM KCl, 15 mM NaCl, 5 mM MgCl2, 0.1 mM EGTA, 0.1% NP40, 0.15 mM Spermine, 0.5 mM Spermidine, 2 mM 6AA) to reduce mitochondrial DNA contamination.
Project description:Super-enhancers are principal determinants of cell transcription, development, phenotype, and oncogenesis, not yet implicated in host-pathogen interactions. We found four Epstein-Barr virus (EBV) oncoproteins and five EBV-activated NF-M-oM-^AM-+B subunits co-occupying thousand of enhancer sites in EBV-transformed lymphoblastoid cells (LCLs). Of these, 187 had markedly higher and broader histone H3K27ac signals characteristic of super-enhancer formation, and were designated M-bM-^@M-^\EBV super-enhancersM-bM-^@M-^]. EBV super-enhancer associated genes included MYC and BCL2, which enable LCL proliferation and survival. EBV super-enhancers were enriched for specific B cell transcription factor motifs and had high STAT5 and NFAT co-occupancy. EBV super-enhancer associated genes were more highly expressed than other LCL genes. Disruption of EBV super-enhancers by the bromo-domain inhibitor, JQ1, by conditional inactivation of an EBV oncoprotein or NF-M-oM-^AM-+B, decreased MYC or BCL2 gene expression and arrested LCL growth. These findings provide novel insights into the mechanisms by which EBV causes lymphoproliferation and identify opportunities for therapeutic intervention. ChIP-seq was used to define the BRD4 genome-wide landscape in GM12878 lymphoblastoid cells.