MLL3

Epigenetic deregulation is a critical theme which needs further investigation in bladder cancer research. One of the most highly mutated genes in bladder cancer is KDM6A , which functions as an H3K27 demethylase and is one of the MLL3/4 complexes. To decipher the role of KDM6A in normal versus tumor settings, we identified the genomic landscape of KDM6A in normal, immortalized, and cancerous bladder cells. Our results showed differential KDM6A occupancy in the genes involved in cell differentiation, chromatin organization, and Notch signaling depending on the cell type and the mutation status of KDM6A ...

Deep sequencing of human tumours has uncovered a previously unappreciated role for epigenetic regulators in tumorigenesis. H3K4 methyltransferase KMT2C/MLL3 is mutated in several solid malignancies, including more than 10% of breast tumours. To study the tumour suppressor role of KMT2C in breast cancer, we generated mouse models of Erbb2/Neu, Myc or PIK3CA-driven tumorigenesis, in which the Kmt2c locus is knocked out specifically in the luminal lineage of mouse mammary glands using the Cre recombinase. Kmt2c knock out mice develop tumours earlier, irrespective of the oncogene, assigning a bona fide tumour suppressor role for KMT2C in mammary tumorigenesis...

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...

The number of cases of pancreatic cancers in 2019 in Poland was 3852 (approx. 2% of all cancers). The course of the disease is very fast, and the average survival time from the diagnosis is 6 months. Only <2% of patients live for 5 years from the diagnosis, 8% live for 2 years, and almost half live for only about 3 months. A family predisposition to pancreatic cancer occurs in about 10% of cases. Several oncogenes in which somatic changes lead to the development of tumours, including genes BRCA1/2 and PALB2, TP53, CDKN2A, SMAD4, MLL3, TGFBR2, ARID1A and SF3B1, are involved in pancreatic cancer...

PURPOSE: Approximately, 45-65% stage I non-small cell lung cancer (NSCLC) patients with surgical resection relapse within 5 years. Therefore, it is urgent to identify the predictors involved in the relapse of stage I NSCLC. METHODS/PATIENTS: Targeted sequencing was used to examine the mutation of tumor tissues and matched adjacent normal tissues from 35 patients with stage I lung adenocarcinoma (LUAD). Then, tissue microarrays containing tumor tissues from 149 stage I LUAD patients were used to assess protein expression of frequently mutated genes by immunohistochemistry...

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Phenotypic plasticity associated with the hybrid epithelial-mesenchymal transition (EMT) is crucial to metastatic seeding and outgrowth. However, the mechanisms governing the hybrid EMT state remain poorly defined. Here we showed that deletion of the epigenetic regulator MLL3, a tumour suppressor frequently altered in human cancer, promoted the acquisition of hybrid EMT in breast cancer cells. Distinct from other EMT regulators that mediate only unidirectional changes, MLL3 loss enhanced responses to stimuli inducing EMT and mesenchymal-epithelial transition in epithelial and mesenchymal cells, respectively...

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...

UNLABELLED: Menin interacts with oncogenic MLL1-fusion proteins, and small molecules that disrupt these associations are in clinical trials for leukemia treatment. By integrating chromatin-focused and genome-wide CRISPR screens with genetic, pharmacologic, and biochemical approaches, we discovered a conserved molecular switch between the MLL1-Menin and MLL3/4-UTX chromatin-modifying complexes that dictates response to Menin-MLL inhibitors. MLL1-Menin safeguards leukemia survival by impeding the binding of the MLL3/4-UTX complex at a subset of target gene promoters...

An imbalance in the activities of the Polycomb and Trithorax complexes underlies numerous human pathologies, including cancer. The BRCA1 associated protein-1 (BAP1) deubiquitinase negatively regulates Polycomb activity and recruits the Trithorax histone H3K4 methyltransferase, mixed-lineage leukemia protein 3 (MLL3) within Complex Proteins Associated with Set1 (COMPASS), to the enhancers of tumor suppressor genes. We previously demonstrated that the BAP1-MLL3 pathway is mutated in several cancers, yet how BAP1 recruits MLL3 to its target loci remains an important unanswered question...

MLL3, also known as KMT2C, is a lysine mono-methyltransferase in charge of the writing of an epigenetic mark on lysine 4 from histone 3. The catalytic site of MLL3 is composed of four tyrosines, namely, Y44, Y69, Y128, and Y130. Tyrosine residues are highly conserved among lysine methyltransferases' catalytic sites, although their complete function is still unclear. The exploration of how modifications on these residues from the enzymatic machinery impact the enzymatic activity of MLL3 could shed light transversally into the inner functioning of enzymes with similar characteristics...

PURPOSE: Wilms' tumor is the most-frequent malignant-kidney tumor in children under 3-4 years of age and is caused by genetic alterations of oncogenes (OG) and tumor-suppressor genes (TG). Wilms' tumor has been linked to many OG-&-TG. However, only WT1 has a proven role in the development of this embryonic-tumor. METHODS: The study investigates the level of mRNA expression of 16 OGs and 20 TGs involved in key-signaling pathways, including chromatin modification; RAS; APC; Cell Cycle/Apoptosis; Transcriptional Regulation; PI3K; NOTCH-&-HH; PI3K & RAS of 24-fresh Wilms'-tumor cases by capture-and-reporter probe Code-Sets chemistry, as CNVs in these pathway genes have been reported...

Posttranslational modification of histones plays a critical role in regulation of gene expression. These modifications include methylation and acetylation that work in combination to establish transcriptionally active or repressive chromatin states. Histone methyltransferases (HMTs) often have variable levels of activity in vitro depending on the form of substrate used. For example, certain HMTs prefer nucleosomes extracted from human or chicken cells as substrate compared to recombinant nucleosomes reconstituted from bacterially produced histones...

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...

PTIP-associated protein 1 (PA1) is a unique component of MLL3/4 complexes, which are important mammalian histone 3 lysine 4 (H3K4) methyltransferases. PA1 has generated research interest due to its involvement in many essential biological processes such as adipogenesis, B cell class switch recombination, spermatogenesis, and embryonic development. In addition to the classical role of PA1 in H3K4 methylation, non-classical functions have also been discovered in recent studies. In this review, we systematically summarize the expression pattern of PA1 protein in humans and sort the specific molecular mechanism of PA1 in various biological processes...

The circadian clock controls the physiological function of tissues through the regulation of thousands of genes in a cell-type-specific manner. The core cellular circadian clock is a transcription-translation negative feedback loop, which can recruit epigenetic regulators to facilitate temporal control of gene expression. Histone methyltransferase, mixed lineage leukemia gene 3 (MLL3) was reported to be required for the maintenance of circadian oscillations in cultured cells. Here, we test the role of MLL3 in circadian organization in whole animals...

Hypopharyngeal cancer is a poorly characterized type of head and neck squamous cell carcinoma (HNSCC) with bleak prognosis and only few studies focusing specifically on the genomic profile of this type of cancer. We performed molecular profiling of 48 HPV (Human Papilloma Virus)-negative tumor samples including 23 originating from the hypopharynx and 25 from the larynx using a targeted next-generation sequencing approach. Among genes previously described as significantly mutated, TP53, FAT1, NOTCH1, KMT2C , and CDKN2A were found to be most frequently mutated...

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)...

Kleefstra Syndrome (KS) is a genetic, neurodevelopmental disorder characterized by intellectual disability, infantile hypotonia, severe expressive language delay, and characteristic facial appearance, with a spectrum of other distinct clinical manifestations. Pathogenic mutations in the epigenetic modifier, type 2 lysine methyltransferase (KMT2C), are attributed to cause KS core features in individuals who are Euchromatic Histone Lysine Methyltransferase 1, EHMT1, mutation negative. These individuals are designated as having KS type 2...

Anaplastic lymphoma kinase tyrosine kinase inhibitors (ALK-TKIs) have been found to significantly improve the quality of life and survival in ALK -positive non-small cell lung cancer (NSCLC) patients. However, the duration of responses is limited by drug resistance. Genetic heterogeneity of ALK -positive tumors could potentially explain the differences in individual patient outcomes. We performed next-generation sequencing (NGS) on plasma samples, pleural effusion samples, and tissue re-biopsy obtained at various treatment milestones from an ALK rearrangement lung adenocarcinoma patient undergoing targeted therapy...