MLL4

Epigenetic status-altering mutations in chromatin-modifying enzymes are a feature of human diseases, including many cancers. However, the functional outcomes and cellular dependencies arising from these mutations remain unresolved. In this study, we investigated cellular dependencies, or vulnerabilities, that arise when enhancer function is compromised by loss of the frequently mutated COMPASS family members MLL3 and MLL4. CRISPR dropout screens in MLL3/4-depleted mouse embryonic stem cells (mESCs) revealed synthetic lethality upon suppression of purine and pyrimidine nucleotide synthesis pathways...

The spatial folding of eukaryotic genome plays a key role in genome function. We report here that our recently developed method, Hi-TrAC, which specializes in detecting chromatin loops among accessible genomic regions, can detect active sub-TADs with a median size of 100 kb, most of which harbor one or two cell specifically expressed genes and regulatory elements such as super-enhancers organized into nested interaction domains. These active sub-TADs are characterized by highly enriched histone mark H3K4me1 and chromatin-binding proteins, including Cohesin complex...

Somatic stem cells contribute to normal tissue homeostasis, and their epigenomic features play an important role in regulating tissue identities or developing disease states. Enhancers are one of the key players controlling chromatin context-specific gene expression in a spatial and temporal manner while maintaining tissue homeostasis, and their dysregulation leads to tumorigenesis. Here, epigenomic and transcriptomic analyses reveal that forkhead box protein D2 (FOXD2) is a hub for the gene regulatory network exclusive to large intestinal stem cells, and its overexpression plays a significant role in colon cancer regression...

Understanding the molecular mechanism(s) of small compounds in cellular growth control are essential for using those against the disease(s). Oral cancers exhibit a very high mortality rate due to higher metastatic potential. Aberrant EGFR, RAR, HH signalling, enhanced [Ca2+ ] and oxidative stress are some of the important characteristics of oral cancer. So, we target these for our study. Herein, we tested the effect of fendiline hydrochloride (FH) as an LTCC Ca2+ -channel inhibitor, erismodegib (a SMO inhibitor of HH-signalling) and all-trans retinoic acid (RA) inducer of RAR signalling that causes cellular differentiation...

H3K4me1 methyltransferases MLL3 (KMT2C) and MLL4 (KMT2D) are critical for enhancer activation, cell differentiation and development. However, roles of MLL3/4 enzymatic activities and MLL3/4-mediated enhancer H3K4me1 in these processes remain unclear. Here we report that constitutive elimination of both MLL3 and MLL4 enzymatic activities prevents initiation of gastrulation and leads to early embryonic lethality in mice. However, selective elimination of MLL3/4 enzymatic activities in embryonic, but not extraembryonic, lineages leaves gastrulation largely intact...

UNLABELLED: The high frequency of aberrant PI3K pathway activation in hormone receptor-positive (HR+ ) breast cancer has led to the development, clinical testing, and approval of the p110α-selective PI3K inhibitor alpelisib. The limited clinical efficacy of alpelisib and other PI3K inhibitors is partially attributed to the functional antagonism between PI3K and estrogen receptor (ER) signaling, which is mitigated via combined PI3K inhibition and endocrine therapy. We and others have previously demonstrated chromatin-associated mechanisms by which PI3K supports cancer development and antagonizes ER signaling through the modulation of the H3K4 methylation axis, inhibition of KDM5A promoter H3K4 demethylation and KMT2D/MLL4-directed enhancer H3K4 methylation...

Angiogenesis occurred after myocardial infarction (MI) protects heart failure (HF). The aim of our study was to explore function of histone methyltransferase KMT2D (MLL4, mixed-lineage leukemia 4) in angiogenesis post-MI. Western blotting showed that KMT2D protein expression was elevated in MI mouse myocardial. Cardiomyocyte-specific Kmt2d-knockout (Kmt2d-cKO) mice were generated, and echocardiography and immunofluorescence staining detected significantly attenuated cardiac function and insufficient angiogenesis following MI in Kmt2d-cKO mice...

BACKGROUND: Enhancers are essential in defining cell fates through the control of cell-type-specific gene expression. Enhancer activation is a multi-step process involving chromatin remodelers and histone modifiers including the monomethylation of H3K4 (H3K4me1) by MLL3 (KMT2C) and MLL4 (KMT2D). MLL3/4 are thought to be critical for enhancer activation and cognate gene expression including through the recruitment of acetyltransferases for H3K27. RESULTS: Here we test this model by evaluating the impact of MLL3/4 loss on chromatin and transcription during early differentiation of mouse embryonic stem cells...

PURPOSE: Mixed-lineage leukemia protein 4 (MLL4/KMT2D) is a histone methyltransferase, and its mutation has been reported to be associated with a poor prognosis in many cancers, including lung cancer. We investigated the function of MLL4 in lung carcinogenesis. MATERIALS AND METHODS: RNA sequencing (RNA-seq) in A549 cells transfected with control siRNA or MLL4 siRNA was performed. Also, we used EdU incorporation assay, colony formation assays, growth curve analysis, transwell invasion assays, immunohistochemical staining and in vivo bioluminescence assay to investigate the function of MLL4 in lung carcinogenesis...

Hepatitis B virus (HBV) DNA integration is an incidental event in the virus replication cycle and occurs in less than 1% of infected hepatocytes during viral infection. However, HBV DNA is present in the genome of approximately 90% of HBV-related HCCs and is the most common somatic mutation. Whole genome sequencing of liver tissues from chronic hepatitis B patients showed integration occurring at random positions in human chromosomes; however, in the genomes of HBV-related HCC patients, there are integration hotspots...

PURPOSE: Oligometastatic non-small cell lung cancer (NSCLC) patients have been increasingly regarded as a distinct group that could benefit from local treatment to achieve a better clinical outcome. However, current definitions of oligometastasis are solely numerical, which are imprecise because of ignoring the biological heterogeneity caused by genomic characteristics. Our study aimed to profile the molecular alterations of oligometastatic NSCLC and elucidate its potential difference from polymetastasis...

Enhancer deregulation is a well-established pro-tumorigenic mechanism but whether it plays a regulatory role in tumor immunity is largely unknown. Here, we demonstrate that tumor cell ablation of mixed-lineage leukemia 3 and 4 (MLL3 and MLL4, also known as KMT2C and KMT2D, respectively), two enhancer-associated histone H3 lysine 4 (H3K4) mono-methyltransferases, increases tumor immunogenicity and promotes anti-tumor T cell response. Mechanistically, MLL4 ablation attenuates the expression of RNA-induced silencing complex (RISC) and DNA methyltransferases through decommissioning enhancers/super-enhancers, which consequently lead to transcriptional reactivation of the double-stranded RNA (dsRNA)-interferon response and gasdermin D (GSDMD)-mediated pyroptosis, respectively...

There is growing evidence supporting the implications of exosomes-shuttled microRNAs (miRs) in the phenotypes of glioblastoma stem cells (GSCs), whilst the role of exosomal miR-27b-3p remains to be established. Herein, the aim of this study was to investigate the effect of M2 tumor-associated macrophage (TAM)-derived exosomal miR-27b-3p on the function of GSCs. Clinical glioblastoma (GBM) specimens were obtained and GSCs and M2-TAMs were isolated by fluorescence-activated cell sorting (FACS), and exosomes were separated from M2-TAMs...

The mitotic deacetylase complex MiDAC has recently been shown to play a vital physiological role in embryonic development and neurite outgrowth. However, how MiDAC functionally intersects with other chromatin-modifying regulators is poorly understood. Here, we describe a physical interaction between the histone H3K27 demethylase UTX, a complex-specific subunit of the enhancer-associated MLL3/4 complexes, and MiDAC. We demonstrate that UTX bridges the association of the MLL3/4 complexes and MiDAC by interacting with ELMSAN1, a scaffolding subunit of MiDAC...

Kabuki syndrome (KS) is frequently caused by loss-of-function mutations in one allele of the H3K4 methyltransferase KMT2D and is associated with problems in neurological, immunological, and skeletal system development. We generated heterozygous KMT2D knock-out and Kabuki-patient derived cell models to investigate the role of KMT2D reduced dosage in stem cells. We discovered chromosomal locus-specific alterations in gene expression, specifically a 110Kb region containing SYT3, CLEC11A, C19ORF81, and SHANK1, suggesting locus-specific targeting of KMT2D...

The RE1 Silencing Transcription Factor (REST) is a major regulator of neurogenesis and brain development. Medulloblastoma (MB) is a pediatric brain cancer characterized by a blockade of neuronal specification. REST gene expression is aberrantly elevated in a subset of MBs that are driven by constitutive activation of sonic hedgehog (SHH) signaling in cerebellar granular progenitor cells (CGNPs), the cells of origin of this subgroup of tumors. To understand its transcriptional deregulation in MBs, we first studied control of Rest gene expression during neuronal differentiation of normal mouse CGNPs...

Enhancers control cell type-specific gene expression and are marked by H3K4me1. Active enhancers are further marked by H3K27ac. We identified MLL3/MLL4 as major H3K4me1 methyltransferases and CBP/p300 as the H3K27 acetyltransferases in mammalian cells (EMBO J 2011; eLife 2013). During differentiation of adipocytes, myocytes and ES cells, MLL3/MLL4 co-localize with lineage-determining transcription factors (LDTFs), CBP/p300, Brd4 and MED1 on active enhancers. MLL3/MLL4 are required for enhancer activation, enhancer-promoter interaction, cell type-specific gene expression, and cell differentiation (eLife 2013; PNAS 2016; Nat Comm 2017)...

Background: KMT2B -related dystonia is a primarily childhood-onset movement disorder characterized by progressive dystonia, spasticity, and developmental delay. A minority of individuals possess an inherited KMT2B variant. Case Report: As a child, the proband experienced mild developmental delay and laryngeal dystonia which progressed to generalized dystonia. Patellar hyperreflexia, postural tremor, and everted gait were documented. Whole exome sequencing identified a heterozygous pathogenic KMT2B variant in the proband, proband's sister, and proband's mother who had milder presentations...

The epigenetic regulator, MLL4 ( KMT2D ), has been described as an essential gene in both humans and mice. In addition, it is one of the most commonly mutated genes in all of cancer biology. Here, we identify a critical role for Mll4 in the promotion of epidermal differentiation and ferroptosis, a key mechanism of tumor suppression. Mice lacking epidermal Mll4 , but not the related enzyme Mll3 ( Kmt2c ), display features of impaired differentiation and human precancerous neoplasms, all of which progress with age...

Alterations of epigenetic modulators are extensively associated with cancer, but their key molecular activities in cancer regulation are often unclear. We discovered that lysine demethylase 6A (KDM6A, also known as UTX) suppresses cancer by forming liquid-like condensates with lysine methyltransferase 2D (KMT2D, also known as MLL4) and regulating chromatin activity at multiple levels.