The genome wide mapping of H3K9 and H3K23 acetylation in Moz+/+ and Moz-/- MOZ-TIF2 AML cells
Ontology highlight
ABSTRACT: Monocytic leukemia Zinc finger protein (MOZ) is a MYST-type acetyltransferase involved in chromosomal translocation in acute myelogenous leukemia (AML) and myelodysplastic syndrome. MOZ is established as essential for hematopoiesis; however, the role of MOZ in AML has not been addressed. We propose that MOZ is critical for AML development induced by MOZ-TIF2 fusions. Moz-deficient hematopoietic stem/progenitor cells (HSPCs) expressing MOZ-TIF2 could form colonies in vitro but could not induce AML in mice. By contrast, Moz was dispensable for colony formation by HOXA9-transduced cells and AML development caused by HOXA9 and MEIS1, suggesting a specific requirement for MOZ in AML induced by MOZ/MLL-fusions. Expression of the of Meis1, but not Hoxa9, was reduced in Moz-deficient MOZ-TIF2 AML cells. AML development induced by MOZ-TIF2 was rescued by introducing Meis1 into Moz-deficient cells carrying MOZ-TIF2. Meis1 deletion impaired MOZ-TIF2-mediated AML development. Active histone modifications were also severely reduced at the Meis1 locus in Moz-deficient MOZ-TIF2 AML cells. These results suggest that endogenous MOZ is critical for MOZ-fusion-induced AML development and maintains active chromatin signatures at target gene loci.
Project description:Eradication of chemotherapy-resistant leukemia stem cells is expected to improve treatment outcomes in patients with acute myelogenous leukemia (AML). In a mouse model of AML expressing the MOZ-TIF2 fusion, we found that Ring1A and Ring1B, components of Polycomb repressive complex 1, play crucial roles in maintaining AML stem cells. Deletion of Ring1A and Ring1B (Ring1A/B) from MOZ-TIF2 AML cells diminished self-renewal capacity and induced the expression of numerous genes including Gli-similar 2 (Glis2). Overexpression of Glis2 caused MOZ-TIF2 AML cells to differentiate into mature cells, whereas Glis2 knockdown in Ring1A/B-deficient MOZ-TIF2 cells inhibited differentiation. Thus, Ring1A/B regulates and maintains AML stem cells in part by repressing Glis2 expression, which promotes their differentiation. These findings provide new insights into the mechanism of AML stem cell homeostasis and reveal novel targets for cancer stem cell therapy.
Project description:Aberrant regulation of chromatin modifiers is a common occurrence across many cancer types, and a key priority is to determine how specific alteration of these proteins, often enzymes, can be targeted therapeutically. MOZ, a histone acyltransferase, is recurrently fused to coactivators CBP, p300, and TIF2 in cases of Acute Myeloid Leukemia (AML). Using either pharmacological inhibition or targeted protein degradation in a mouse model for MOZ-TIF2-driven leukemia, we show that KAT6 (MOZ/MORF) enzymatic activity and the MOZ-TIF2 protein are necessary for indefinite proliferation in cell culture. Interestingly, MOZ enzymatic activity is selectively required in MOZ-TIF2 cells, as murine MLL-AF9 leukemic cells show no sensitivity to the WM-1119 MOZ inhibitor. MOZ-TIF2 directly regulates a small subset of genes encoding developmental transcription factors, augmenting their high expression. Transcription levels of these genes positively correlate with enrichment of histone H3 propionylation at lysine 23 (H3K23pr), a recently appreciated histone acylation associated with gene activation. Unexpectedly, we also show that MOZ-TIF2 and MLL-AF9 regulate transcription of largely non-overlapping gene sets, and their cellular models exhibit distinct sensitivities to multiple small molecule inhibitors directed against AML pathways. This is despite the shared genetic pathways of wild-type MOZ and MLL. Overall, our data provide insight into how aberrant regulation of MOZ contributes to leukemogenesis. We anticipate these experiments will inform future work identifying targeted therapies in the treatment of AML and other diseases involving MOZ-induced transcriptional dysregulation.
Project description:Aberrant regulation of chromatin modifiers is a common occurrence across many cancer types, and a key priority is to determine how specific alteration of these proteins, often enzymes, can be targeted therapeutically. MOZ, a histone acyltransferase, is recurrently fused to coactivators CBP, p300, and TIF2 in cases of Acute Myeloid Leukemia (AML). Using either pharmacological inhibition or targeted protein degradation in a mouse model for MOZ-TIF2-driven leukemia, we show that KAT6 (MOZ/MORF) enzymatic activity and the MOZ-TIF2 protein are necessary for indefinite proliferation in cell culture. Interestingly, MOZ enzymatic activity is selectively required in MOZ-TIF2 cells, as murine MLL-AF9 leukemic cells show no sensitivity to the WM-1119 MOZ inhibitor. MOZ-TIF2 directly regulates a small subset of genes encoding developmental transcription factors, augmenting their high expression. Transcription levels of these genes positively correlate with enrichment of histone H3 propionylation at lysine 23 (H3K23pr), a recently appreciated histone acylation associated with gene activation. Unexpectedly, we also show that MOZ-TIF2 and MLL-AF9 regulate transcription of largely non-overlapping gene sets, and their cellular models exhibit distinct sensitivities to multiple small molecule inhibitors directed against AML pathways. This is despite the shared genetic pathways of wild-type MOZ and MLL. Overall, our data provide insight into how aberrant regulation of MOZ contributes to leukemogenesis. We anticipate these experiments will inform future work identifying targeted therapies in the treatment of AML and other diseases involving MOZ-induced transcriptional dysregulation.
Project description:Aberrant regulation of chromatin modifiers is a common occurrence across many cancer types, and a key priority is to determine how specific alteration of these proteins, often enzymes, can be targeted therapeutically. MOZ, a histone acyltransferase, is recurrently fused to coactivators CBP, p300, and TIF2 in cases of Acute Myeloid Leukemia (AML). Using either pharmacological inhibition or targeted protein degradation in a mouse model for MOZ-TIF2-driven leukemia, we show that KAT6 (MOZ/MORF) enzymatic activity and the MOZ-TIF2 protein are necessary for indefinite proliferation in cell culture. Interestingly, MOZ enzymatic activity is selectively required in MOZ-TIF2 cells, as murine MLL-AF9 leukemic cells show no sensitivity to the WM-1119 MOZ inhibitor. MOZ-TIF2 directly regulates a small subset of genes encoding developmental transcription factors, augmenting their high expression. Transcription levels of these genes positively correlate with enrichment of histone H3 propionylation at lysine 23 (H3K23pr), a recently appreciated histone acylation associated with gene activation. Unexpectedly, we also show that MOZ-TIF2 and MLL-AF9 regulate transcription of largely non-overlapping gene sets, and their cellular models exhibit distinct sensitivities to multiple small molecule inhibitors directed against AML pathways. This is despite the shared genetic pathways of wild-type MOZ and MLL. Overall, our data provide insight into how aberrant regulation of MOZ contributes to leukemogenesis. We anticipate these experiments will inform future work identifying targeted therapies in the treatment of AML and other diseases involving MOZ-induced transcriptional dysregulation.
Project description:Acute Myeloid Leukaemia (AML) is a highly heterogeneous disease characterised by an abnormal transcriptional landscape that results in a block in normal blood cell differentiation and aberrant self-renewal. Dysregulation of Homeobox A9 (HOXA9) expression is a hallmark of multiple AML subsets. Although HOXA9 is critical for maintaining leukaemic transformation, it has proven to be a challenging druggable target, and the underpinning molecular mechanisms through which it promotes leukaemogenesis remain elusive. Here, we report the existence of a dichotomous expression profile between sine oculis homeobox 1 SIX1 and the well known HOXA9 interactors MEIS1 in monocytic zinc finger (MOZ) and mixed-lineage leukaemia (MLL) rearranged AMLs. We employed ChIP-seq, together with RNA-seq, to identify regions bound and transcriptionally upregulated in a MOZ-TIF2 driven model of AML. Using RNA-seq, we demonstrated that SIX1 and EYA1 (the well known SIX1 partner) potentiates the transforming capacity of HOXA9 to confer a greater level of differentiation block via suppression of myelo-monocytic programmes. We next sought to define the impact of pharmacologically destabilising the EYA1/SIX1 complex using Benzarone. Through a single cell RNA-Seq timecourse following treatment of MOZ-TIF2 cells with Benzarone, we provide evidence that disruption of EYA1 and its interactions results in differentiation of these cells. To prove the specificity of Benzarone towards EYA1, we also conducted RNA-Seq on cells expressing EYA1 and HOXA9 or HOXA9 alone.
Project description:HOXA9/MEIS1 plays a synergistic causative role and overexpresses frequently in acute myeloid leukemia (AML). Hoxa9/Meis1 transgenic murine results in rapid leukemic transformation of primary bone marrow cells. However, murine model is not suitable to perform a high-throughput phenotypic screen in vivo and identify compounds for AML therapy. A transgenic zebrafish overexpresses hoxa9/meis1 need to generate. We have engineered an inducible transgenic line Tg (drl:hoxa9;hsp70:meis1) harboring hoxa9/meis1 under the draculin (drl) promoter. The downregulation of runx1, c-myb, mpx, mfap4, and gata1 in Tg (drl:hoxa9;hsp70:meis1) embryos indicated enforced hoxa9/meis1 perturbs embryonic hematopoiesis. Importantly, adult Tg (drl:hoxa9;hsp70:meis1) develops malignant myeloid disease with an abundance of myeloid precursor cells, anemia, and high mortality after a latency period (~5-months-aged) with comparable to murine model and human AML patients. Genome-wide transcription changes analysis indicated arrested differentiation genes such as gata2b, notch1b, and gfi1ab are upregulated. Leflunomide, inhibitor of enzyme dihydroorotate dehydrogenase (DHODH) which is a potential option for differentiation therapy of AML, relieves defective hematopoiesis in transgenic embryos and larvae. Collectively, we have identified an inducible malignant myeloid disease transgenic zebrafish model similar to AML and provided a unique opportunity for high-throughput in vivo chemical screening for AML therapy and study the related mechanisms.
Project description:OBJECTIVE: The microRNA miR-155 is upregulated in Hoxa9 and Meis1 leukemia inducing cells (LIC) , and miR-155 accelerates the onset of acute myeloid leukemia (AML) together with Hoxa9 but through largely unknown molecular mechanisms. The impact of miR-155 on accelerated onset of leukemia in the context of Hoxa9 and Meis1 is also unclear. To further resolve this, we performed a gene expression profiling, in the context of Hoxa9 and Meis1 leukemogenesis with miR-155 knocked out. RESULTS: Gene expression profiling of Hoxa9/Meis1 LIC without miR-155 does not delay the onset of AML and the gene expression changes are small
Project description:Human acetyltransferases MOZ and MORF are implicated in chromosomal translocations associated with aggressive leukemias. Oncogenic translocations involve the far amino terminus of MOZ/MORF, the function of which remains unclear. Here, we identified and characterized two structured winged helix domains, WH1 and WH2, in MORF and MOZ. WHs bind DNA in a cooperative manner, with WH1 specifically recognizing unmethylated CpG sequences. Structural and genomic analyses show that the DNA binding function of WHs targets MORF/MOZ to gene promoters, stimulating transcription and H3K23 acetylation, and WH1 recruits oncogenic fusions to HOXA genes that trigger leukemogenesis. Cryo-EM, NMR, mass spectrometry and mutagenesis studies provide mechanistic insight into the DNA-binding mechanism, which includes the association of WH1 with the linker DNA and binding of WH2 to the dyad of the nucleosome, with the latter being further modulated by the neighboring domain DPF and autoacetylation of MORF. The discovery of WHs in MORF and MOZ and their DNA binding functions could open a new avenue in developing therapeutics to treat diseases associated with aberrant MOZ/MORF acetyltransferase activities.