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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.

ORGANISM(S): Homo sapiens

PROVIDER: GSE73528 | GEO | 2016/07/01

SECONDARY ACCESSION(S): PRJNA297225

REPOSITORIES: GEO

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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. Investigation of multiple transcription factors and histone modification marks in MV4-11 human leukemia cells.

2016-07-01 | E-GEOD-73528 | biostudies-arrayexpress

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

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

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

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

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

The Trithorax protein Ash1L promotes myoblast fusion by activating Cdon expression

Project description:Myoblast fusion (MF) is a complex process required for muscle formation. During development, post-natal muscle growth and adult muscle regeneration, myoblasts proliferate and fuse to generate multinucleated fibers. MF defects have been described in an increasing number of muscle diseases. Moreover, MF plays also a relevant role in the delivery of therapeutics to muscle fibers. Hence, the identification of novel MF activators bears strong therapeutic relevance. Despite the central role of MF, the mechanisms governing this process are incompletely understood, and no epigenetic regulator has ever been described. Ash1L is a histone methyltransferase responsible for H3K36me2 and a member of the Trithorax group of epigenetic activators. It is involved in several diseases, including FSHD muscular dystrophy, autism and cancer. Nevertheless, its physiological role in skeletal muscle is unknown. For the first time, we found that Ash1L expression is regulated during skeletal muscle development, positively correlated with that of key MF genes and reduced in Duchenne muscular dystrophy. During physiological muscle differentiation or muscle regeneration, Ash1L shows a peak of expression coincident with the activation of MF. Loss-of-function experiments support a selective and evolutionary conserved requirement for Ash1L in MF. Accordingly, Ash1L KO mice display small and underdeveloped skeletal muscles due to a MF defect. By combining RNA- and ChIP-sequencing, we identified direct Ash1L targets in muscle. Intriguingly, nearly all of them are known Polycomb target genes suggesting that Ash1L is required to counteract Polycomb repressive activity to allow activation of key myogenesis genes. In particular, we found that Ash1L drives MF by directly activating the expression of the key MF gene Cdon. Our results promote Ash1L as the first epigenetic regulator of MF and suggest that its activity could be targeted to improve cell therapy for muscle diseases.

2018-10-02 | GSE110957 | GEO

Structure-function relationship of ASH1L and histone H3K36 and H3K4 methylation

Project description:The ASH1L lysine methyltransferase plays a critical role in development and is frequently dysregulated in cancer and neurodevelopmental diseases. ASH1L catalyzes mono- and dimethylation of histone H3K36 and contains a set of uncharacterized domains. Here, we report the structure-function relationships of the C-terminal cassette of ASH1L encompassing a bromodomain (BD), a PHD finger and a bromo-associated homology (BAH) domain and show that ASH1L co-localizes with H3K4me3 but not with H3K36me2 at transcription start sites genome-wide and is involved in embryonic stem cell differentiation and transcriptional regulation of differentiation marker genes. Our crystal and NMR structural data provide mechanistic details for the recognition of H3K4me3 by PHD, the DNA binding activities of BD and BAH, and crosstalk among these domains. We show that the PHD-H3K4me3 interaction is inhibitory to the catalytic activity of ASH1L and that the DNA binding function of BAH is necessary for ASH1L engagement with the nucleosome. Our findings suggest a mechanism by which the C-terminus of ASH1L associates with chromatin and provide molecular and structural insights that are essential in therapeutic targeting of ASH1L.

2023-04-23 | GSE199438 | 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

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

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

| PRJNA631054 | ENA