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Project description: Not available
| S-EPMC10668985 | biostudies-literature
Project description:Abstract: (1) Background: The LEO1 (Left open reading frame 1) protein is a conserved subunit of the PAF1C complex (RNA polymerase II associated factor 1 complex). PAF1C has well-established mechanistic functions in elongation of transcription and RNA processing. We have previously shown, in fission yeast, that LEO1 is controlling histone H3K9 methylation levels by affecting the turnover of histone H3 in chromatin, and that it is essential for proper regulation of gene expression during cellular quiescence. Human fibroblasts enter a reversible quiescence state upon serum deprivation in the growth media. Here we investigate the function of LEO1 in human fibroblasts. (2) Methods: We knocked out the LEO1 gene using CRISPR/Cas9 methodology in human fibroblasts and verified that the LEO1 protein was undetectable by Western blot. We characterized the phenotype of the DLEO1 knockout cells with FACS analysis and cell growth assays. We used RNA-sequencing using spike-in controls to measure gene expression and spike-in controlled ChIP-sequencing experiments to measure the histone modification H3K9me2 genome-wide. (3) Results: Gene expression levels are altered in quiescent cells, however factors controlling chromatin and gene expression changes in quiescent human cells are largely unknown. The DLEO1 knockout fibroblasts are viable but have reduced metabolic activity compared to wild type cells. DLEO1 cells showed a slower entry into quiescence and a different morphology compared to wild type cells. Gene expression was generally reduced in quiescent wild type cells. The downregulated genes included genes involved in cell proliferation. A small number of genes were upregulated in quiescent wild type cells including several genes involved in ERK1/ERK2 and Wnt signaling. In quiescent DLEO1 cells many genes were mis-regulated compared to wild type cells. This included genes involved in Calcium ion transport and cell morphogenesis. Finally, spike-in controlled ChIP-sequencing experiments demonstrated that the histone modification H3K9me2 levels are globally increased in quiescent DLEO1 cells. (4) Conclusions: Thus, LEO1 is important for proper entry into cellular quiescence, control H3K9me2 levels and gene expression in human fibroblasts.
2023-11-29 | GSE247831 | GEO
Project description:Abstract: (1) Background: The LEO1 (Left open reading frame 1) protein is a conserved subunit of the PAF1C complex (RNA polymerase II associated factor 1 complex). PAF1C has well-established mechanistic functions in elongation of transcription and RNA processing. We have previously shown, in fission yeast, that LEO1 is controlling histone H3K9 methylation levels by affecting the turnover of histone H3 in chromatin, and that it is essential for proper regulation of gene expression during cellular quiescence. Human fibroblasts enter a reversible quiescence state upon serum deprivation in the growth media. Here we investigate the function of LEO1 in human fibroblasts. (2) Methods: We knocked out the LEO1 gene using CRISPR/Cas9 methodology in human fibroblasts and verified that the LEO1 protein was undetectable by Western blot. We characterized the phenotype of the DLEO1 knockout cells with FACS analysis and cell growth assays. We used RNA-sequencing using spike-in controls to measure gene expression and spike-in controlled ChIP-sequencing experiments to measure the histone modification H3K9me2 genome-wide. (3) Results: Gene expression levels are altered in quiescent cells, however factors controlling chromatin and gene expression changes in quiescent human cells are largely unknown. The DLEO1 knockout fibroblasts are viable but have reduced metabolic activity compared to wild type cells. DLEO1 cells showed a slower entry into quiescence and a different morphology compared to wild type cells. Gene expression was generally reduced in quiescent wild type cells. The downregulated genes included genes involved in cell proliferation. A small number of genes were upregulated in quiescent wild type cells including several genes involved in ERK1/ERK2 and Wnt signaling. In quiescent DLEO1 cells many genes were mis-regulated compared to wild type cells. This included genes involved in Calcium ion transport and cell morphogenesis. Finally, spike-in controlled ChIP-sequencing experiments demonstrated that the histone modification H3K9me2 levels are globally increased in quiescent DLEO1 cells. (4) Conclusions: Thus, LEO1 is important for proper entry into cellular quiescence, control H3K9me2 levels and gene expression in human fibroblasts.
2023-11-29 | GSE247829 | GEO
Project description:LEO1 Is Required for Efficient Entry into Quiescence, Control of H3K9 methylation and Gene Expression in Human Fibroblasts
| PRJNA1040789 | ENA
Project description:LEO1 Is Required for Efficient Entry into Quiescence, Control of H3K9 methylation and Gene Expression in Human Fibroblasts [ChIP-Seq]
| PRJNA1040795 | ENA
Project description:LEO1 Is Required for Efficient Entry into Quiescence, Control of H3K9 methylation and Gene Expression in Human Fibroblasts [RNA-Seq]
| PRJNA1040797 | ENA
Project description:GLP and G9a are major H3K9 dimethylases and are essential for mouse early embryonic development. GLP and G9a both harbor ankyrin repeat domains that are capable of binding H3K9 methylation. However, the functional significance of their recognition of H3K9 methylation is unknown. Here, we report that the histone methyltransferase activities of GLP and G9a are stimulated by neighboring nucleosomes that are premethylated at H3K9. These stimulation events function in cis and are dependent on the H3K9 methylation binding activities of ankyrin repeat domains of GLP and G9a. Disruption of the H3K9 methylation-binding activity of GLP in mice causes growth retardation of embryos, ossification defects of calvaria, and postnatal lethality due to starvation of the pups. In mouse embryonic stem cells (ESCs) harboring a mutant GLP that lacks H3K9me1-binding activity, critical pluripotent genes, including Oct4 and Nanog, display inefficient establishment of H3K9me2 and delayed gene silencing during differentiation. Collectively, our study reveals a new activation mechanism for GLP and G9a that plays an important role in ESC differentiation and mouse viability.
| S-EPMC4335294 | biostudies-literature
Project description:In most eukaryotes, histone methylation patterns regulate chromatin architecture and function: methylation of histone H3 lysine-9 (H3K9) demarcates heterochromatin, whereas H3K4 methylation demarcates euchromatin. We show here that the S. pombe JmjC-domain protein Lid2 is a trimethyl H3K4 demethylase responsible for H3K4 hypomethylation in heterochromatin. Lid2 interacts with the histone lysine-9 methyltransferase, Clr4, through the Dos1/Clr8-Rik1 complex, which also functions in the RNA interference pathway. Disruption of the JmjC domain alone results in severe heterochromatin defects and depletion of siRNA, whereas overexpressing Lid2 enhances heterochromatin silencing. The physical and functional link between H3K4 demethylation and H3K9 methylation suggests that the two reactions act in a coordinated manner. Surprisingly, crossregulation of H3K4 and H3K9 methylation in euchromatin also requires Lid2. We suggest that Lid2 enzymatic activity in euchromatin is regulated through a dynamic interplay with other histone-modification enzymes. Our findings provide mechanistic insight into the coordination of H3K4 and H3K9 methylation.
| S-EPMC2614271 | biostudies-literature
Project description:BackgroundCellular quiescence is a reversible differentiation state during which cells modify their gene expression program to inhibit metabolic functions and adapt to a new cellular environment. The epigenetic changes accompanying these alterations are not well understood. We used fission yeast cells as a model to study the regulation of quiescence. When these cells are starved for nitrogen, the cell cycle is arrested in G1, and the cells enter quiescence (G0). A gene regulatory program is initiated, including downregulation of thousands of genes-for example, those related to cell proliferation-and upregulation of specific genes-for example, autophagy genes-needed to adapt to the physiological challenge. These changes in gene expression are accompanied by a marked alteration of nuclear organization and chromatin structure.ResultsHere, we investigated the role of Leo1, a subunit of the conserved RNA polymerase-associated factor 1 (Paf1) complex, in the quiescence process using fission yeast as the model organism. Heterochromatic regions became very dynamic in fission yeast in G0 during nitrogen starvation. The reduction of heterochromatin in early G0 was correlated with reduced target of rapamycin complex 2 (TORC2) signaling. We demonstrated that cells lacking Leo1 show reduced survival in G0. In these cells, heterochromatic regions, including subtelomeres, were stabilized, and the expression of many genes, including membrane transport genes, was abrogated. TOR inhibition mimics the effect of nitrogen starvation, leading to the expression of subtelomeric genes, and this effect was suppressed by genetic deletion of leo1.ConclusionsWe identified a protein, Leo1, necessary for survival during quiescence. Leo1 is part of a conserved protein complex, Paf1C, linked to RNA polymerase II. We showed that Leo1, acting downstream of TOR, is crucial for the dynamic reorganization of chromosomes and the regulation of gene expression during cellular quiescence. Genes encoding membrane transporters are not expressed in quiescent leo1 mutant cells, and cells die after 2 weeks of nitrogen starvation. Taken together, our results suggest that Leo1 is essential for the dynamic regulation of heterochromatin and gene expression during cellular quiescence.
| S-EPMC6636030 | biostudies-literature
Project description:Posttranslational histone modifications are believed to allow the epigenetic transmission of distinct chromatin states, independently of associated DNA sequences. Histone H3 lysine 9 (H3K9) methylation is essential for heterochromatin formation; however, a demonstration of its epigenetic heritability is lacking. Fission yeast has a single H3K9 methyltransferase, Clr4, that directs all H3K9 methylation and heterochromatin. Using releasable tethered Clr4 reveals that an active process rapidly erases H3K9 methylation from tethering sites in wild-type cells. However, inactivation of the putative histone demethylase Epe1 allows H3K9 methylation and silent chromatin maintenance at the tethering site through many mitotic divisions, and transgenerationally through meiosis, after release of tethered Clr4. Thus, H3K9 methylation is a heritable epigenetic mark whose transmission is usually countered by its active removal, which prevents the unauthorized inheritance of heterochromatin.
| S-EPMC4397586 | biostudies-literature