MIR139 is a tumor suppressor and is commonly silenced in acute myeloid leukemia (AML). However, the tumor-suppressing activities of miR-139 and molecular mechanisms of MIR139-silencing remain largely unknown. Here, we studied the poorly prognostic MLL-AF9 fusion protein-expressing AML. We show that MLL-AF9 expression in hematopoietic precursors caused epigenetic silencing of MIR139, whereas overexpression of MIR139 inhibited in vitro and in vivo AML outgrowth. We identified novel miR-139 targets that mediate the tumor-suppressing activities of miR-139 in MLL-AF9 AML. We revealed that two enhancer regions control MIR139 expression and found that the polycomb repressive complex 2 (PRC2) downstream of MLL-AF9 epigenetically silenced MIR139 in AML. Finally, a genome-wide CRISPR-Cas9 knockout screen revealed RNA Polymerase 2 Subunit M (POLR2M) as a novel MIR139-regulatory factor. Our findings elucidate the molecular control of tumor suppressor MIR139 and reveal a role for POLR2M in the MIR139-silencing mechanism, downstream of MLL-AF9 and PRC2 in AML. In addition, we confirmed these findings in human AML cell lines with different oncogenic aberrations, suggesting that this is a more common oncogenic mechanism in AML. Our results may pave the way for new targeted therapy in AML.

• MeSH
• akutní myeloidní leukemie genetika   MeSH
• epigeneze genetická MeSH
• fúzní onkogenní proteiny genetika   MeSH
• karcinogeneze genetika   MeSH
• lidé MeSH
• mikro RNA genetika   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• nádorové buněčné linie MeSH
• protoonkogenní protein MLL genetika   MeSH
• regulace genové exprese u leukemie MeSH
• RNA-polymerasa II genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Epigenetic modifications are inherited differences in cellular phenotypes, such as cell gene expression alterations, that occur during somatic cell divisions (also, in rare circumstances, in germ line transmission), but no alterations to the DNA sequence are involved. Histone alterations, polycomb/trithorax associated proteins, short non-coding or short RNAs, long non-coding RNAs (lncRNAs), & DNA methylation are just a few biological processes involved in epigenetic events. These various modifications are intricately linked. The transcriptional potential of genes is closely conditioned by epigenetic control, which is crucial in normal growth and development. Epigenetic mechanisms transmit genomic adaptation to an environment, resulting in a specific phenotype. The purpose of this systematic review is to glance at the roles of Estrogen signalling, polycomb/trithorax associated proteins, DNA methylation in breast cancer progression, as well as epigenetic mechanisms in breast cancer therapy, with an emphasis on functionality, regulatory factors, therapeutic value, and future challenges.

• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Polycomb repressive complex 2 (PRC2) is involved in maintaining transcriptionally silent chromatin states through methylating lysine 27 of histone H3 by the catalytic subunit enhancer of zeste [E(z)]. Here, we report the diversity of PRC2 core subunit proteins in different eukaryotic supergroups with emphasis on the early-diverged lineages and explore the molecular evolution of PRC2 subunits by phylogenetics. For the first time, we identify the putative ortholog of E(z) in Discoba, a lineage hypothetically proximal to the eukaryotic root, strongly supporting emergence of PRC2 before the diversification of eukaryotes. Analyzing 283 species, we robustly detect a common presence of E(z) and ESC, indicating a conserved functional core. Full-length Su(z)12 orthologs were identified in some lineages and species only, indicating, nonexclusively, high divergence of VEFS-Box-containing Su(z)12-like proteins, functional convergence of sequence-unrelated proteins, or Su(z)12 dispensability. Our results trace E(z) evolution within the SET-domain protein family, proposing a substrate specificity shift during E(z) evolution based on SET-domain and H3 histone interaction prediction.

• MeSH
• fylogeneze MeSH
• histony genetika   metabolismus   MeSH
• lysin metabolismus   MeSH
• PRC2 * genetika   metabolismus   MeSH
• proteiny Drosophily * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Polycomb repressive complexes 1 and 2 play important roles in epigenetic gene regulation by posttranslationally modifying specific histone residues. Polycomb repressive complex 2 is responsible for the trimethylation of lysine 27 on histone H3; Polycomb repressive complex 1 catalyzes the monoubiquitination of histone H2A at lysine 119. Both complexes have been thoroughly studied in Arabidopsis, but the evolution of polycomb group gene families in monocots, particularly those with complex allopolyploid origins, is unknown. RESULTS: Here, we present the in silico identification of the Polycomb repressive complex 1 and 2 (PRC2, PRC1) subunits in allohexaploid bread wheat, the reconstruction of their evolutionary history and a transcriptional analysis over a series of 33 developmental stages. We identified four main subunits of PRC2 [E(z), Su(z), FIE and MSI] and three main subunits of PRC1 (Pc, Psc and Sce) and determined their chromosomal locations. We found that most of the genes coding for subunit proteins are present as paralogs in bread wheat. Using bread wheat RNA-seq data from different tissues and developmental stages throughout plant ontogenesis revealed variable transcriptional activity for individual paralogs. Phylogenetic analysis showed a high level of protein conservation among temperate cereals. CONCLUSIONS: The identification and chromosomal location of the Polycomb repressive complex 1 and 2 core components in bread wheat may enable a deeper understanding of developmental processes, including vernalization, in commonly grown winter wheat.

• MeSH
• chromozomy rostlin MeSH
• fylogeneze MeSH
• mapování chromozomů MeSH
• molekulární evoluce MeSH
• počítačová simulace MeSH
• PRC1 genetika   MeSH
• PRC2 genetika   MeSH
• pšenice genetika   MeSH
• RNA rostlin MeSH
• sekvenování transkriptomu MeSH
• stanovení celkové genové exprese MeSH
• Publikační typ
• časopisecké články MeSH

Mutation of SMARCA4 (BRG1), the ATPase of BAF (mSWI/SNF) and PBAF complexes, contributes to a range of malignancies and neurologic disorders. Unfortunately, the effects of SMARCA4 missense mutations have remained uncertain. Here we show that SMARCA4 cancer missense mutations target conserved ATPase surfaces and disrupt the mechanochemical cycle of remodeling. We find that heterozygous expression of mutants alters the open chromatin landscape at thousands of sites across the genome. Loss of DNA accessibility does not directly overlap with Polycomb accumulation, but is enriched in 'A compartments' at active enhancers, which lose H3K27ac but not H3K4me1. Affected positions include hundreds of sites identified as superenhancers in many tissues. Dominant-negative mutation induces pro-oncogenic expression changes, including increased expression of Myc and its target genes. Together, our data suggest that disruption of enhancer accessibility represents a key source of altered function in disorders with SMARCA4 mutations in a wide variety of tissues.

• MeSH
• adenosintrifosfatasy metabolismus   MeSH
• chromatin chemie   MeSH
• DNA-helikasy genetika   MeSH
• dominantní geny * MeSH
• epigenomika MeSH
• genotyp MeSH
• heterozygot MeSH
• jaderné proteiny genetika   MeSH
• kultivační média MeSH
• lidé MeSH
• missense mutace MeSH
• multivariační analýza MeSH
• mutace * MeSH
• myší embryonální kmenové buňky cytologie   MeSH
• myši transgenní MeSH
• myši MeSH
• nádory genetika   MeSH
• polycomb proteiny genetika   MeSH
• restrukturace chromatinu MeSH
• sekvenční analýza RNA MeSH
• transkripční faktory genetika   MeSH
• zesilovače transkripce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Polycomb repressive complexes maintain transcriptional repression of genes encoding crucial developmental regulators through chromatin modification. Here we investigated the role of Polycomb repressive complex 2 (PRC2) in retinal development by inactivating its key components Eed and Ezh2. Conditional deletion of Ezh2 resulted in a partial loss of PRC2 function and accelerated differentiation of Müller glial cells. In contrast, inactivation of Eed led to the ablation of PRC2 function at early postnatal stage. Cell proliferation was reduced and retinal progenitor cells were significantly decreased in this mutant, which subsequently caused depletion of Müller glia, bipolar, and rod photoreceptor cells, primarily generated from postnatal retinal progenitor cells. Interestingly, the proportion of amacrine cells was dramatically increased at postnatal stages in the Eed-deficient retina. In accordance, multiple transcription factors controlling amacrine cell differentiation were upregulated. Furthermore, ChIP-seq analysis showed that these deregulated genes contained bivalent chromatin (H3K27me3+ H3K4me3+). Our results suggest that PRC2 is required for proliferation in order to maintain the retinal progenitor cells at postnatal stages and for retinal differentiation by controlling amacrine cell generation.

• MeSH
• buněčná diferenciace fyziologie   MeSH
• chromatin metabolismus   MeSH
• EZH2 protein metabolismus   MeSH
• histony metabolismus   MeSH
• kmenové buňky cytologie   metabolismus   MeSH
• metylace MeSH
• myši MeSH
• neurogeneze MeSH
• neuroglie metabolismus   MeSH
• PRC2 metabolismus   MeSH
• proliferace buněk MeSH
• retina metabolismus   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Východiska: Výzkum posledního desetiletí potvrdil význam epigenetických procesů při vzniku, vývoji a léčbě nádorových onemocnění. Především sekvenování nové generace umožnilo zmapovat lidský epigenom a sledovat jeho změny během kancerogeneze. Tento přístup odhalil přímá napojení epigenetických abnormalit na mutace genů, které kontrolují metylaci DNA, sbalování a funkci DNA v chromatinu, nebo na metabolizmus buněk. Epigenetické změny DNA se vyskytují už v časných fázích vývoje nádorových onemocnění, a jsou tedy slibnými kandidáty na diagnostické a prognostické markery a současně epigenetické procesy představují vhodné cíle pro vývoj nových terapeutických látek. Získané poznatky o aberantní metylaci DNA umožňují dva různé pohledy na to, jak daná modifikace přispívá k vývoji nádorového onemocnění. První pohled předpokládá, že normální buňky podléhají transformaci vlivem řídicích mutací, kdy následné metylace de novo a demetylace DNA přispívají k řadě programových změn genové exprese. Alternativní přístup pohlíží na změny v metylaci DNA jako na důsledek např. stárnutí buněk. A právě tyto získané změny zvyšují citlivost DNA ke vzniku mutací a k následné onkogenní transformaci. Cíle: Cílem přehledového článku je shrnout dosud známé úlohy abnormální metylace DNA při vývoji nádorového onemocnění a představit již publikovanou alternativní teorii, která k dané problematice přistupuje méně obvyklým způsobem.

Background: Research in the last decade has confirmed the importance of epigenetic processes for the onset, development, and treatment of cancer. Next generation sequencing has allowed the inspection and mapping of the human epigenome and its monitoring for changes during carcinogenesis, which has revealed direct links between epigenetic abnormalities and mutations in genes that control DNA methylation and packing and those that function in chromatin dynamics and metabolism. Epigenetic changes that occur in the early stages of tumor progression thus represent promising candidates for diagnostic and prognostic markers, and epigenetic processes are suitable targets for the development of new therapeutic strategies. There are two contrasting views on how aberrant DNA methylation contributes to the development of cancer. The first view assumes that normal cells undergo transformation due to driver mutations and subsequent de novo methylation and DNA demethylation, resulting in global changes in gene expression. The second view considers changes in DNA methylation to be a consequence of cell aging, for example, and that the acquired changes increase the sensitivity of DNA to mutations and oncogenic transformation. Aims: The aim of the review article is to briefly summarize the role of abnormal DNA methylation in the development of cancer, and to present an alternative theory that considers the role of aberrant DNA methylation patterns in cancer from a new and unconventional perspective.

• MeSH
• CpG ostrůvky MeSH
• lidé MeSH
• metylace DNA * MeSH
• nádory * etiologie   genetika   MeSH
• polycomb proteiny MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• přehledy MeSH

Many plant cells can be reprogrammed into a pluripotent state that allows ectopic organ development. Inducing totipotent states to stimulate somatic embryo (SE) development is, however, challenging due to insufficient understanding of molecular barriers that prevent somatic cell dedifferentiation. Here we show that Polycomb repressive complex 2 (PRC2)-activity imposes a barrier to hormone-mediated transcriptional reprogramming towards somatic embryogenesis in vegetative tissue of Arabidopsis thaliana. We identify factors that enable SE development in PRC2-depleted shoot and root tissue and demonstrate that the establishment of embryogenic potential is marked by ectopic co-activation of crucial developmental regulators that specify shoot, root and embryo identity. Using inducible activation of PRC2 in PRC2-depleted cells, we demonstrate that transient reduction of PRC2 activity is sufficient for SE formation. We suggest that modulation of PRC2 activity in plant vegetative tissue combined with targeted activation of developmental pathways will open possibilities for novel approaches to cell reprogramming.

• MeSH
• Arabidopsis účinky léků   genetika   růst a vývoj   MeSH
• kořeny rostlin růst a vývoj   metabolismus   MeSH
• kyseliny indoloctové farmakologie   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• represorové proteiny genetika   metabolismus   MeSH
• somatická embryogeneze rostlin * MeSH
• výhonky rostlin růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

Lung cancer is the most common cause of cancer deaths. The expression of the transcription factor C/EBPα (CCAAT/enhancer binding protein α) is frequently lost in non-small cell lung cancer, but the mechanisms by which C/EBPα suppresses tumor formation are not fully understood. In addition, no pharmacological therapy is available to specifically target C/EBPα expression. We discovered a subset of pulmonary adenocarcinoma patients in whom negative/low C/EBPα expression and positive expression of the oncogenic protein BMI1 (B lymphoma Mo-MLV insertion region 1 homolog) have prognostic value. We also generated a lung-specific mouse model of C/EBPα deletion that develops lung adenocarcinomas, which are prevented by Bmi1 haploinsufficiency. BMI1 activity is required for both tumor initiation and maintenance in the C/EBPα-null background, and pharmacological inhibition of BMI1 exhibits antitumor effects in both murine and human adenocarcinoma lines. Overall, we show that C/EBPα is a tumor suppressor in lung cancer and that BMI1 is required for the oncogenic process downstream of C/EBPα loss. Therefore, anti-BMI1 pharmacological inhibition may offer a therapeutic benefit for lung cancer patients with low expression of C/EBPα and high BMI1.

• MeSH
• adenokarcinom genetika   metabolismus   patologie   terapie   MeSH
• lidé MeSH
• mutace genetika   MeSH
• myši knockoutované MeSH
• myši MeSH
• nádory plic genetika   metabolismus   patologie   terapie   MeSH
• PRC1 genetika   metabolismus   MeSH
• protein alfa vázající zesilovač transkripce CCAAT genetika   metabolismus   MeSH
• protoonkogenní proteiny genetika   metabolismus   MeSH
• regulace genové exprese u nádorů genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

In mammals, the noncoding Xist RNA triggers transcriptional silencing of one of the two X chromosomes in female cells. Here, we report a genetic screen for silencing factors in X chromosome inactivation using haploid mouse embryonic stem cells (ESCs) that carry an engineered selectable reporter system. This system was able to identify several candidate factors that are genetically required for chromosomal repression by Xist. Among the list of candidates, we identify the RNA-binding protein Spen, the homolog of split ends. Independent validation through gene deletion in ESCs confirms that Spen is required for gene repression by Xist. However, Spen is not required for Xist RNA localization and the recruitment of chromatin modifications, including Polycomb protein Ezh2. The identification of Spen opens avenues for further investigation into the gene-silencing pathway of Xist and shows the usefulness of haploid ESCs for genetic screening of epigenetic pathways.

• MeSH
• embryonální kmenové buňky metabolismus   MeSH
• haploidie MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• kultivované buňky MeSH
• myši MeSH
• PRC2 genetika   metabolismus   MeSH
• RNA dlouhá nekódující genetika   MeSH
• umlčování genů * MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH