G9a plays distinct roles in maintaining DNA methylation, retrotransposon silencing and chromatin looping
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ABSTRACT:
PROVIDER: PRJNA574621 | ENA |
REPOSITORIES: ENA
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Project description:G9a is a lysine methyltransferase that regulates epigenetic modifications, transcription and genome organization. However, whether these properties are dependent on one another or represent distinct functions of G9a remains unclear. In this study, we observe widespread DNA methylation loss in G9a depleted and catalytic mutant embryonic stem cells. Furthermore, we define how G9a regulates chromatin accessibility, epigenetic modifications and transcriptional silencing in both catalytic dependent and independent manners. Reactivated retrotransposons provide alternative promoters and splice sites leading to upregulation of neighboring genes and production of chimeric transcripts. Moreover, while topologically associated domains and compartments A/B definitions are largely unaffected, the loss of G9a leads to altered chromatin states, aberrant CTCF and cohesin binding, and differential chromatin looping especially at retrotransposons. Taken together, our findings reveal how G9a regulates the epigenome, transcriptome and higher-order chromatin structures in distinct mechanisms.
2020-10-26 | GSE138102 | GEO
Project description:Epithelial EP4 plays an essential role in maintaining homeostasis in colon
| PRJNA560350 | ENA
Project description:Lysine methyltransferases G9a and GLP (G9a- Like Protein) form functional heterodimeric complexes that establish mono- and dimethylation on histone H3 lysine 9 (H3K9me1, H3K9me2) in euchromatin. Here we describe unexpected opposite individual roles for G9a and GLP during skeletal muscle terminal differentiation. Indeed, gain- or loss-of-function assays in myoblasts showed that in consistency with previous reports that G9a inhibits terminal differentiation. But GLP plays a more complicated role in muscle differentiation since both knockdown and overexpression inhibits terminal differentiation. Unexpectedly, in contrast to G9a, we show that GLP overexpression promotes abnormal expression of muscle differentiationspecific genes in proliferating myoblasts. Transcriptomic analysis indicates that G9a and GLP regulate different sets of genes. GLP, but not G9a, inhibits at the transcriptional level proteasome subunit-encoding genes resulting in an inhibition of the proteasome activities. Subsequently, GLP, but not G9a, overexpression stabilizes MyoD that is likely to be responsible for muscle markers expression in proliferating myoblasts.
2016-02-01 | GSE72626 | GEO
Project description:Background:Pulmonary arterial hypertension (PAH) is a severe condition characterized by progressive vascular remodeling of small pulmonary arteries (PAs) causing sustained elevation of PA pressure, right ventricular failure and death. Similar to cancer cells, PA smooth muscle cells (PASMCs), which play a key role in pulmonary vascular remodeling, have adopted multiple mechanisms to sustain their survival and proliferation in the presence of stress. The histone methyltransferase G9a has been shown to exert oncogenic effects and to serve as a buffer against an exaggerated transcriptional response. Therefore, we hypothesized that G9a up-regulation in PAH plays a pivotal role in pulmonary vascular remodeling by maintaining the abnormal phenotype of PAH-PASMCs. Methods: G9alevels were measured in PAs and isolated PASMCs of PAH patients and animal models. Selective G9a pharmacological inhibitors were used in human PAH-PASMCs and in rodent PAH models (i.e.Fawn-Hooded rats and Sugen/Hypoxia-exposed mice). Results: We present evidence of increased expression of G9a in PASMCs from PAH patients as well as in remodeled PAs from animal models. We found that pharmacological inhibition of G9a activity using BIX01294 and UNC0642significantly reduces the prosurvival and proproliferative potentials of cultured PAH-PASMCs. Using RNA sequencing, further exploration revealed that G9a promotes extracellular matrix production and affords protection against the negative effects of an overactive stress response. Finally, we found that therapeutic treatment with BIX01294 reduced pulmonary vascular remodeling and lowered mean PA pressure in Fawn-Hooded rats. Treatment of Sugen/hypoxia-challenged mice with BIX01294 also improved pulmonary hemodynamics and right ventricular function. Conclusions:These findings suggest that G9a inhibition may represent a new therapeutic approach in PAH.
2023-01-20 | GSE200821 | GEO
Project description:Retrotransposable elements are genomic parasites that are both key drivers of evolution and the ancestors of retroviruses. Although host cells have developed numerous mechanisms to keep these elements in check, there is also evidence from yeast to mammals that stressed cells sometimes activate transposition. Here we show that the fission yeast tf2 retrotransposons are regulated by alternative transcription start site (TSS) usage. Which TSS is used is determined by nucleosome positioning, which is in turn controlled by the Fun30 chromatin remodelers Fft2 and Fft3. By maintaining a high level of nucleosome occupancy at retrotransposon-flanking Long Terminal Repeat (LTR) elements, Fft2 and Fft3 promote the use of a downstream TSS and the production of RNA incapable of reverse transcription and retrotransposition. More generally, we show that Fft2 and Fft3 are involved in repressing the transcriptional response to stress, of which retrotransposon activation is a part. Finally, we show that in stressed cells retrotransposon TSS usage switches, allowing the production of full-length retrotransposon RNA. We propose that allowing retrotransposon transcription from a nonproductive TSS allows for the rapid activation of these elements in times of stress, while preventing their uncontrolled proliferation in the genome.
2016-03-03 | GSE57067 | GEO
Project description:Posttranslational modifications of histone N-terminal tails influence the status of chromatin and eventually control the transcriptional outcome of a particular gene. As a histone H3K9 methyltransferase (HMTase) in higher eukaryotes, G9a-mediated transcriptional repression is the major epigenetic silencing machinery. UHRF1 (ubiquitin-like with PHD and ring finger domains I) binds to hemi-methylated DNA and plays essential role in maintenance of DNA methylation by recruiting DNMT1. Here, we provide evidence that UHRF1 is transcriptionally downregulated by H3K9 HMTase G9a. We found that increased expression of G9a along with transcription factor YY1 specifically represses UHRF1 transcription. We uncovered showed that G9a regulates UHRF1-mediated H3K23 ubiquitylation and proper DNA replication maintenance by FACS analysis and propose that H3K9 HMTase G9a is a specific epigenetic regulator of UHRF1.
2018-12-31 | GSE63149 | GEO
Project description:Retrotransposable elements are genomic parasites that are both key drivers of evolution and the ancestors of retroviruses. Although host cells have developed numerous mechanisms to keep these elements in check, there is also evidence from yeast to mammals that stressed cells sometimes activate transposition. Here we show that the fission yeast tf2 retrotransposons are regulated by alternative transcription start site (TSS) usage. Which TSS is used is determined by nucleosome positioning, which is in turn controlled by the Fun30 chromatin remodelers Fft2 and Fft3. By maintaining a high level of nucleosome occupancy at retrotransposon-flanking Long Terminal Repeat (LTR) elements, Fft2 and Fft3 promote the use of a downstream TSS and the production of RNA incapable of reverse transcription and retrotransposition. More generally, we show that Fft2 and Fft3 are involved in repressing the transcriptional response to stress, of which retrotransposon activation is a part. Finally, we show that in stressed cells retrotransposon TSS usage switches, allowing the production of full-length retrotransposon RNA. We propose that allowing retrotransposon transcription from a nonproductive TSS allows for the rapid activation of these elements in times of stress, while preventing their uncontrolled proliferation in the genome.
2016-03-03 | GSE57068 | GEO
Project description:G9a (EHMT2) and the G9a-like protein GLP (EHMT1) form a stable G9a/GLP heterodimer in embryonic stem cells and function cooperatively to establish and maintain the abundant repressive H3K9me2 modification, in addition to modifying several non-histone proteins. The G9a-dependent H3K9me2 is implicated in lineage-specific gene silencing and covers large chromosomal domains. While the mechanism of H3K9me2maintenance by G9a/GLP is known, how new patterns of this modification are established is not well understood. With this in mind, we used FLAG affinity purification of G9a under two different stringency conditions (150 and 300 mM NaCl) coupled with mass spectrometry to identify proteins stably associated with G9a/GLP, which could serve as potential recruiters of the complex to unmodified chromatin.
2016-03-16 | PXD003466 | Pride
Project description:Gene expression in eukaryotes is tightly linked to the methylation state of specific lysine residues within the N-terminal region of the core histone proteins. While the mechanisms connecting histone lysine methylation to effector protein recruitment and control of gene activity are increasingly well understood, it remains unknown whether non-histone chromatin proteins are targets for similar modification-recognition systems. Here we show that histone H3 and the H3 methyltransferase G9a share a conserved methylation motif that is both necessary and sufficient to mediate in vivo interaction with the potent epigenetic regulator Heterochromatin Protein 1 (HP1). As with H3, G9a-HP1 interaction is dependent on lysine methylation and can be reversed by adjacent phosphorylation. NMR analysis demonstrates that the HP1 chromodomain recognizes methyl-G9a through a binding mode similar to that used in recognition of methyl-H3, and that adjacent phosphorylation directly antagonizes G9a-HP1 interaction. In addition to uncovering the chromodomain as a generalized methyl-lysine binding module, these data identify histone-like modification cassettes (or âhistone mimicsâ) as an entirely new class of non-histone methylation targets, and directly demonstrate the relevance of the principles underlying the histone code to the regulation of non-histone proteins. Experiment Overall Design: Two independent Affymetrix gene expression microarray analyses were performed on samples from G9a-deleted MEFs reconstituted with empty vector (delta), wild type FLAG-G9a (WT), FLAG-G9a K165A (K165A) or FLAG-G9a H1093K catalytic mutant (H1093K).
2008-06-15 | E-GEOD-8011 | biostudies-arrayexpress
Project description:We report a novel translation-regulatory function of G9a, a histone methyltransferase and well-understood transcriptional repressor, in promoting hyperinflammation and lymphopenia; two hallmarks of endotoxin tolerance (ET)-associated chronic inflammatory complications. Using multiple approaches, we demonstrate that G9a interacts with multiple translation regulators during ET, particularly the N6-methyladenosine (m6A) RNA methyltransferase METTL3, to co-upregulate expression of certain m6A-modified mRNAs that encode immune-checkpoint and anti-inflammatory proteins. Mechanistically, G9a promotes m6A methyltransferase activity of METTL3 at translational/post-translational level by regulating its expression, its methylation, and its cytosolic localization during ET. Additionally, from a broader view extended from the G9a-METTL3-m6A translation regulatory axis, our translatome proteomics approach identified numerous “G9a-translated” proteins that unite the networks associated with inflammation dysregulation, T cell dysfunction, and systemic cytokine response. In sum, we identified a previously unrecognized function of G9a in protein-specific translation that can be leveraged to treat ET-related chronic inflammatory diseases.
2023-10-20 | PXD044382 | Pride