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ASH1L links histone H3 lysine 36 di-methylation to leukemia

ABSTRACT: The histone methyltransferases MLL and ASH1L are trithorax-group proteins that interact genetically through undefined molecular mechanisms to regulate developmental and hematopoietic gene expression. Here we show that the lysine 36-dimethyl mark of histone H3 (H3K36me2) written by ASH1L is preferentially bound in vivo by LEDGF, an MLL-associated protein that co-localizes with MLL, ASH1L and H3K36me2 on chromatin genome wide. Furthermore, ASH1L facilitates recruitment of LEDGF and wild type MLL proteins to chromatin at key leukemia target genes, and is a crucial regulator of MLL-dependent transcription and leukemic transformation. Conversely KDM2A, an H3K36me2 demethylase and Polycomb-group silencing protein, antagonizes MLL-associated leukemogenesis. Our studies illuminate the molecular mechanisms underlying epigenetic interactions wherein placement, interpretation and removal of H3K36me2 contribute to the regulation of gene expression and MLL leukemia, and suggest ASH1L as a target for therapeutic intervention. Investigation of multiple transcription factors and histone modification marks in MV4-11 human leukemia cells.

ORGANISM(S): Homo sapiens

SUBMITTER: Li Zhu

PROVIDER: E-GEOD-73528 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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ASH1L links histone H3 lysine 36 di-methylation to leukemia

Project description:The histone methyltransferases MLL and ASH1L are trithorax-group proteins that interact genetically through undefined molecular mechanisms to regulate developmental and hematopoietic gene expression. Here we show that the lysine 36-dimethyl mark of histone H3 (H3K36me2) written by ASH1L is preferentially bound in vivo by LEDGF, an MLL-associated protein that co-localizes with MLL, ASH1L and H3K36me2 on chromatin genome wide. Furthermore, ASH1L facilitates recruitment of LEDGF and wild type MLL proteins to chromatin at key leukemia target genes, and is a crucial regulator of MLL-dependent transcription and leukemic transformation. Conversely KDM2A, an H3K36me2 demethylase and Polycomb-group silencing protein, antagonizes MLL-associated leukemogenesis. Our studies illuminate the molecular mechanisms underlying epigenetic interactions wherein placement, interpretation and removal of H3K36me2 contribute to the regulation of gene expression and MLL leukemia, and suggest ASH1L as a target for therapeutic intervention.

2016-07-01 | GSE73528 | GEO

Histone H3K36me2-specific methyltransferase ASH1L promotes the MLL-AF9-induced leukemogenesis

Project description:ASH1L and MLL1 are two histone methyltransferases that facilitate transcriptional activation during normal development. However, the roles of ASH1L and its enzymatic activity in the development of MLL-rearranged leukemias are not fully elucidated in Ash1L gene knockout animal models. In this study, we used an Ash1L conditional knockout mouse model to show that loss of ASH1L in hematopoietic progenitor cells impaired the initiation of MLL-AF9-induced leukemic transformation in vitro. Furthermore, genetic deletion of ASH1L in the MLL-AF9-transformed cells impaired the maintenance of leukemic cells in vitro and largely blocked the leukemia progression in vivo. Importantly, the loss of ASH1L function in the Ash1L-deleted cells could be rescued by wild-type but not the catalytic-dead mutant ASH1L, suggesting the enzymatic activity of ASH1L was required for its function in promoting MLL-AF9-induced leukemic transformation. At the molecular level, ASH1L enhanced the MLL-AF9 target gene expression by directly binding to the gene promoters and modifying the local histone H3K36me2 levels. Thus, our study revealed the critical functions of ASH1L in promoting the MLL-AF9-induced leukemogenesis, which provides a molecular basis for targeting ASH1L and its enzymatic activity to treat MLL-arranged leukemias.

2021-09-07 | GSE183413 | GEO

Role of LEDGF/p75 in MLL chemoresistance

Project description:The study has been focused on the characterization of the role of LEDGF/p75 in chemiresistance in pediatric leukemia Abstract: MLL is an aggressive subtype of leukemia with a poor prognosis that mostly affects pediatric patients. MLL-rearranged fusion proteins (MLLr) induce aberrant target gene expression resulting in leukemogenesis. MLL and its fusions are tethered to chromatin by LEDGF/p75, a transcriptional co-activator that specifically recognizes H3K36me2/3. LEDGF/p75 is ubiquitously expressed and associated with regulation of gene expression, autoimmune responses and HIV replication. LEDGF/p75 was proven to be essential for leukemogenesis in MLL. Apart from MLL, LEDGF/p75 has been linked to lung, breast and prostate cancer. Intriguingly, LEDGF/p75 interacts with Med-1, which co-localizes with BRD4. Both are known as co-activators of super-enhancers. Here, we describe LEDGF/p75-dependent chemoresistance of MLLr cell lines. Investigation of the underlying mechanism revealed a role of LEDGF/p75 in the cell cycle and in survival pathways and showed that LEDGF/p75 protects against apoptosis during chemotherapy. Remarkably, LEDGF/p75 levels also affected expression of BRD4 and Med1. Altogether, our data suggest a role of LEDGF/p75 in cancer survival, stem cell renewal, and activation of nuclear super enhancers.

2021-01-14 | GSE164751 | GEO

LEDGF/p75 is Dispensable for Hematopoiesis but Essential for MLL-rearranged Leukemogenesis

Project description:Mixed-lineage leukemia (MLL) represents a genetically distinct and aggressive subset of human acute leukemia carrying chromosomal translocations of the MLL gene. These translocations result in oncogenic fusions that mediate aberrant recruitment of transcription machinery to MLL target genes. The N-terminus of MLL and MLL-fusions form a complex with Lens Epithelium-Derived Growth Factor (LEDGF/p75; encoded by the Psip1 gene) and MENIN. This complex contributes to the association of MLL and MLL-fusion multiprotein complexes with chromatin. Several studies have shown that both MENIN and LEDGF/p75 are required for efficient MLL fusion-mediated transformation and for the expression of downstream MLL-regulated genes like HOXA9 and MEIS1. In light of the development of a therapeutic strategy targeting this complex, understanding the function of LEDGF/p75 in normal hematopoiesis is crucial. We generated a conditional Psip1 knockout mouse model in the hematopoietic compartment and examined the effects of LEDGF/p75 depletion in postnatal hematopoiesis and the initiation of MLL leukemogenesis. Psip1 knockout mice were viable but showed several defects in hematopoiesis, reduced colony-forming activity in vitro, decreased expression of Hox genes in hematopoietic stem cells and decreased MLL occupancy at MLL target genes. Finally, in vitro and in vivo experiments showed that LEDGF/p75 is dispensable for steady state hematopoiesis but essential for the initiation of MLL-mediated leukemia. These data corroborate the MLL-LEDGF/p75 interaction as novel target for the treatment of MLL-rearranged leukemia.

2017-09-30 | GSE104138 | GEO

Histone H3K36me2-specific methyltransferase ASH1L promotes the MLL-AF9-induced leukemogenesis

Project description:Histone H3K36me2-specific methyltransferase ASH1L promotes the MLL-AF9-induced leukemogenesis

| PRJNA760532 | ENA

The H3K4-methyl epigenome regulates MLL leukemia stem cell oncogenic potential

Project description:The genetic programs that maintain leukemia stem cell (LSC) self-renewal and oncogenic potential have been well defined, however the epigenetic landscape that determines their cellular identity and functionality has not been established. We report that LSCs in MLL-associated leukemia are maintained in an epigenetic state defined by relative genome-wide high-level H3K4me3 methylation and low level H3K79me2. LSC differentiation is associated with dynamic reversal of these broad epigenetic profiles and concomitant down-regulation of the LSC maintenance transcriptional program. LSCs also share with embryonic stem cells a large subset of genes with bivalent histone marks related to embryonic development. The histone demethylase KDM5B negatively regulates MLL-induced leukemogenesis demonstrating the crucial role of the H3K4 global methylome for determining leukemia stem cell fate. Investigation of multiple histone modification marks and RNA Pol II in ckit+ and ckit- cells isolated and fractionated from MLL leukemia mice.

2015-06-26 | E-GEOD-60193 | biostudies-arrayexpress

The H3K36me2 writer-reader dependency in H3K27M-DIPG

Project description:The lysine-to-methionine mutation at residue 27 of histone H3 (H3K27M) is a driving mutation in Diffuse Intrinsic Pontine Glioma (DIPG), a highly aggressive form of pediatric brain tumor with no effective treatment and little chance of survival. H3K27M reshapes the epigenome through a global inhibition of PRC2 catalytic activity, displacement of methylation at lysine 27 of histone H3 (H3K27me2/3), and thus promoting oncogenesis of DIPG. As a consequence, a histone modification H3K36me2, antagonistic to H3K27me2/3, is aberrantly elevated. Here, we investigate the role of H3K36me2 in H3K27M-DIPG by tackling its upstream catalyzing enzymes (writers) and downstream binding factors (readers). We determine that NSD1 and NSD2 are the key writers for H3K36me2. Loss of NSD1/2 in H3K27M-DIPG impedes cellular proliferation in vitro and tumorigenesis in vivo, and disrupts tumor-promoting gene expression programs. Further, we demonstrate that LEDGF and HDGF2 are the main readers that mediate the pro-tumorigenic effects downstream of NSD1/2-H3K36me2. Treatment with a chemically modified peptide mimicking endogenous H3K36me2 dislodges LEDGF/HDGF2 from chromatin and specifically inhibits the proliferation of H3K27M-DIPG. Together, our results indicate a functional pathway of NSD1/2-H3K36me2-LEDGF/HDGF2 as an acquired dependency in H3K27M-DIPG and suggest a possibility to target this pathway for therapeutic interventions.

2021-07-21 | GSE174006 | GEO

ChIP-seq BHT-101 cells and BHT-101 ASH1L KO cell lines

Project description:The goal of this study is to assess the role of ASH1 like histone lysine methyltransferase (ASH1L) in the biology of anaplastic thyroid cancer. CRISPR-Cas9 was used to create cell lines derived from BHT-101 anaplastic thyroid cancer cells with premature stop codons prior to the catalytic domain within both alleles of ASH1L. ChIP-seq for H3K36me2, the histone mark catalyzed by ASH1L, was performed on two KO cell lines, and compared to wild type BHT-101 cells.

2020-05-09 | GSE147074 | GEO

Role of HRP2 in mixed lineage leukemia compared to its paralog LEDGF/p75

Project description:Mixed lineage leukemia-rearranged (MLLr) leukemia is a genetically distinct subtype of leukemia driven by a reciprocal chromosomal translocation or partial tandem duplications of internal coding regions of the MLL gene KMT2A. These rearrangements result in in-frame genes, translated to oncogenic fusion proteins deregulating the MLL target genes (e.g. HoxA family, Meis1, Cdk6), promoting leukemogenesis and tumor progression. To regulate gene expression, unstructured N-terminal motifs found in MLL form a ternary complex with menin and the integrase binding domain (IBD) of the p75 splice variant of Lens Epithelium Derived Growth Factor (LEDGF/p75). Formation of the ternary complex is crucial for MLL-r leukemogenesis. Hepatoma derived growth factor related protein 2 (HRP2) is the only human paralog of LEDGF/p75 with identical functional domains. We investigated its role in normal hematopoiesis and leukemia. We demonstrate that adult Hrp2 knockout mice can be distinguished from their wild type littermates by increased neutrophils in the hematopoietic system. Colony formation experiments and Gene Set Enrichment Analysis on lin- HSC hinted towards a stem-like state supported by HRP2. In context of leukemia, we observe a more general role for HRP2 in the survival of leukemic cells independently of MLL.

2020-07-11 | GSE154202 | GEO

Genome-wide distribution of ASH1L and H3K36me2 in human MV4;11 leukemia cell line

Project description:The H3K36me2 and ASH1L levels are compared in the presence or absence of the inhibitor of the ASH1L activity.

2021-02-24 | GSE150086 | GEO