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.
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.
Project description:Methylation of histone 3 lysine 36 (H3K36me) has emerged as an essential epigenetic component for the faithful regulation of gene expression. Despite its demonstrated importance in development, disease, and cancer, the molecular agents responsible for the deposition of H3K36me are not yet well understood. Here, we use a mouse mesenchymal stem cell model to comprehensively perturb the components of the H3K36me deposition machinery and infer the activities of the five most prominent players: SETD2, NSD1, NSD2, NSD3, and ASH1L. We find that H3K36me2 is the most abundant of the three methylation states and that it is predominantly deposited at intergenic regions by NSD1, and in part by NSD2. In contrast, H3K36me1/3 are most abundant within exons and have a positive correlation with gene expression. We further demonstrate that while SETD2 is responsible for depositing most H3K36me3, it also deposits a modest amount of H3K36me2 within transcribed genes. Additionally, loss of SETD2 results in an increase of exonic H3K36me1, suggesting that other H3K36 methyltransferases may prime gene bodies with lower methylation states ahead of transcription. Through a reductive approach, we uncover the genome-wide distribution patterns of NSD3- and ASH1L-catalyzed H3K36me2. While NSD1/2 establish broad intergenic H3K36me2 domains, NSD3 deposits broad H3K36me2 peaks centered on active promoter and enhancer regions. Meanwhile, the activity of ASH1L is focused primarily on the promoters of developmentally relevant genes, and our analyses implicate PBX2 as a potential recruitment factor for ASH1L to these regions. Overall, our study provides new insights into the regulation of H3K36me by the H3K36 methyltransferase family and helps to consolidate the wealth of previous observations in the context of a structured analysis.
Project description:Histone post-translational modifications (PTMs) alter chromatin structure by promoting the interaction of chromatin-modifying complexes with nucleosomes. The majority of chromatin-modifying complexes contain multiple domains that preferentially interact with modified histones, leading to speculation that these domains function in concert to target nucleosomes with distinct combinations of histone PTMs. In S. cerevisiae, the NuA3 histone acetyltransferase complex contains three domains, the PHD finger in Yng1, the PWWP domain in Pdp3, and the YEATS domain in Taf14, which in vitro bind to H3K4 methylation, H3K36 methylation, and acetylated and crotonylated H3K9 respectively. However the relative in vivo contributions of these histone PTMs in targeting NuA3 is unknown. Here we show that in vivo H4K4 and H3K36 methylation, but not acetylated or crotonylated H3K9, recruit NuA3 to transcribed genes. Through genome-wide colocalization and by mutational interrogation, we demonstrate that the PHD finger of Yng1, and the PWWP domain of Pdp3 independently target NuA3 to H3K4 and H3K36 methylated chromatin respectively. In contrast, we find no evidence to support the YEATS domain of Taf14 functioning in NuA3 recruitment. Collectively our results suggest that the presence of multiple histone-PTM binding domains within NuA3, rather than restricting it to nucleosomes containing distinct combinations of histone PTMs, can serve to increase the range of nucleosomes bound by the complex. Interestingly however, the simple presence of NuA3 is insufficient to ensure acetylation of the associated nucleosomes, suggesting a secondary level of acetylation regulation that does not involve control of HAT-nucleosome interactions.
Project description:Ash1l encodes a histone methyltransferase, a member of the trithorax group proteins, which regulates developmental essential gene expression by catalyzing H3K36 methylation and counteracting polycomb silencing. Accumulating reports suggest the loss-of-function mutants in Ash1l gene are associated with intellectual disability (ID), attention-deficit/hyperactivity (ADHD), autism spectrum disorder (ASD), Tourette syndrome (TS) and multiple congenital anomalies (MCA). We performed transcriptional profiling of dorsal striatum in 1-year-old Ash1l mutant brain via RNA sequencing (RNA-seq). Ash1l haploinsufficiency induces transcription alternation of genes involved in synaptic function and cortical development, implicating the deficits in synapse pruning and behavior in adult mice.
Project description:Mammalian genetic recombination is concentrated at hotspots, specialized 1-2 Kb sites separated by long stretches of DNA lacking recombination. Mammalian hotspot locations depend on PRDM9, a zinc finger protein that binds at hotspots and uses its SET domain to locally trimethylate histone H3K4. Here we find that PRDM9 also locally trimethylates H3K36 at hotspots. Using ChIP-seq and immunoprecipitation data for H3K36me3 in murine spermatocytes, we show that H3K4me3 and H3K36me3 coincide only at hotspots in germ cells, and that this H3K4me3/H3K36me3-double-positive signature is almost entirely dependent on PRDM9. We performed ChIP-seq with an antibody against H3K36me3, using chromatin extracted from murine spermatocytes, and compared it to previously generated ChIP-seq data for H3K4me3 in the same cell type. ---------------------------------- This dataset represents the H3K36 component only
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.
Project description:Methylation of histone 3 lysine 36 (H3K36me) has emerged as an essential epigenetic component for the faithful regulation of gene expression. Despite its importance in development, disease, and cancer, how the molecular agents collectively shape the genome-wide deposition of H3K36me is unclear. Here, we use mouse mesenchymal stem cells to comprehensively perturb the components of the H3K36me deposition machinery and infer the activities of the five most prominent players: SETD2, NSD1, NSD2, NSD3, and ASH1L. We find that H3K36me2 is the most abundant of the three methylation states and that it is predominantly deposited at intergenic regions by NSD1, and in part by NSD2. In contrast, H3K36me1/3 are most abundant within exons and are positively correlated with gene expression. We demonstrate that while SETD2 is responsible for depositing most H3K36me3, it also deposits H3K36me2 within transcribed genes. Additionally, loss of SETD2 results in an increase of exonic H3K36me1, suggesting that other H3K36 methyltransferases may prime gene bodies with lower methylation states ahead of transcription. Through a reductive approach, we uncover the distribution patterns of NSD3- and ASH1L-catalyzed H3K36me2. While NSD1/2 establish broad intergenic H3K36me2 domains, NSD3 deposits H3K36me2 peaks centered on active promoter and enhancer regions. Meanwhile, the activity of ASH1L is restricted to regulatory elements of developmentally relevant genes, and our analyses implicate PBX2 as a potential recruitment factor. Overall, our study provides new insights into the regulation of H3K36me and helps to consolidate the wealth of previous observations in the context of structured analyses.
Project description:Ash1l encodes a histone methyltransferase, a member of the trithorax group proteins, which regulates developmental essential gene expression by catalyzing H3K36 methylation and counteracting polycomb silencing. Accumulating reports suggest the loss-of-function mutants in Ash1l gene are associated with intellectual disability (ID), attention-deficit/hyperactivity (ADHD), autism spectrum disorder (ASD), Tourette syndrome (TS) and multiple congenital anomalies (MCA). We performed transcriptome analysis of auditory cortex in 1-month-old and 1-year-old Ash1l Ash1l heterozygous mice with their age-matched WT littermates via RNA sequencing (RNA-seq). Ash1l haploinsufficiency induces transcription alternation of genes involved in synaptic function and cortical development, implicating the deficits in synapse pruning and behavior in adult mice.
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.