Homo sapiens
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PROVIDER: PRJNA234531 | ENA |
REPOSITORIES: ENA
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Project description:SIRT1 affects DNA methylation of polycomb group protein target genes (PCGTs), a hotspot of the epigenetic shift observed in ageing
| PRJNA232393 | ENA
Project description:Beneficial effects of SIRT1 on healthspan are likely to be pleiotropic and may include effects on DNA methylation. We demonstrated recently that manipulating SIRT1 in human cells affected DNA methylation of a panel of test genes, and that genes with expression modified by dietary restriction corresponded with genes that underwent changes in DNA methylation during ageing. Here we tested the hypothesis that genes particularly susceptible to SIRT1-induced effects on DNA methylation across the genome map to genes for which DNA methylation changes during ageing. We increased or reduced SIRT1 expression in human intestinal (Caco-2) and vascular endothelial (HuVEC) cells by transient transfection with an expression construct or with siRNA, respectively. Effects on DNA methylation were measured by enriching for the methylated fraction then either sequencing (HuVEC) or hybridising to a human promoter microarray (Caco-2). Effects using these two different cell lines and techniques for analysis were remarkably consistent. Genes with a DNA methylation status affected by SIRT1 manipulation were enriched for those that undergo age-dependent changes in DNA methylation, thus supporting our hypothesis. Polycomb group protein target genes (PCGTs), which are suppressed by epigenetic mechanisms in stem cells and have been shown previously to correspond with loci particularly susceptible to age-related changes in DNA methylation, were over-represented within the set of genes showing altered DNA methylation in response to SIRT1 manipulation in both cell lines. We thus propose that effects of SIRT1 to extend healthspan include influences on the DNA methylation status of genes affected during ageing, in particular PCGTs. Analysis of methylation profiles of Caco-2 cells meeting the following conditions: SIRT1 overexpressed by transfection with pCMV6-ENTRY-SIRT1 (2 replicates), corresponding vector control (2 replicates), each of the siRNAs that target SIRT1 (1 & 2 replicates, respectively) and control siRNA (2 replicates).
2014-03-31 | E-GEOD-53569 | biostudies-arrayexpress
Project description:Beneficial effects of SIRT1 on healthspan are likely to be pleiotropic and may include effects on DNA methylation. We demonstrated recently that manipulating SIRT1 in human cells affected DNA methylation of a panel of test genes, and that genes with expression modified by dietary restriction corresponded with genes that underwent changes in DNA methylation during ageing. Here we tested the hypothesis that genes particularly susceptible to SIRT1-induced effects on DNA methylation across the genome map to genes for which DNA methylation changes during ageing. We increased or reduced SIRT1 expression in human intestinal (Caco-2) and vascular endothelial (HuVEC) cells by transient transfection with an expression construct or with siRNA respectively. Effects on DNA methylation were measured by enriching for the methylated faction then either sequencing (HuVEC) or hybridising to a human promoter microarray (Caco-2). Effects using these two different cell lines and techniques for analysis were remarkably consistent. Genes with a DNA methylation status affected by SIRT1 manipulation were enriched for those that undergo age-dependent changes in DNA methylation, thus supporting our hypothesis. Polycomb group protein target genes (PCGTs), which are suppressed by epigenetic mechanisms in stem cells and have been shown previously to correspond with loci particularly susceptible to age-related changes in DNA methylation, were over-represented within the set of genes showing altered DNA methylation in response to SIRT1 manipulation in both cell lines. We thus propose that effects of SIRT1 to extend healthspan include influences on the DNA methylation status of genes affected during ageing, in particular PCGTs. MBD-Sequencing to ascertain effects of SIRT1 over & under expression on methylation, in presence and absence of TNF-alpha. One sample per condition.
2014-06-30 | E-GEOD-54072 | biostudies-arrayexpress
Project description:Beneficial effects of SIRT1 on healthspan are likely to be pleiotropic and may include effects on DNA methylation. We demonstrated recently that manipulating SIRT1 in human cells affected DNA methylation of a panel of test genes, and that genes with expression modified by dietary restriction corresponded with genes that underwent changes in DNA methylation during ageing. Here we tested the hypothesis that genes particularly susceptible to SIRT1-induced effects on DNA methylation across the genome map to genes for which DNA methylation changes during ageing. We increased or reduced SIRT1 expression in human intestinal (Caco-2) and vascular endothelial (HuVEC) cells by transient transfection with an expression construct or with siRNA respectively. Effects on DNA methylation were measured by enriching for the methylated faction then either sequencing (HuVEC) or hybridising to a human promoter microarray (Caco-2). Effects using these two different cell lines and techniques for analysis were remarkably consistent. Genes with a DNA methylation status affected by SIRT1 manipulation were enriched for those that undergo age-dependent changes in DNA methylation, thus supporting our hypothesis. Polycomb group protein target genes (PCGTs), which are suppressed by epigenetic mechanisms in stem cells and have been shown previously to correspond with loci particularly susceptible to age-related changes in DNA methylation, were over-represented within the set of genes showing altered DNA methylation in response to SIRT1 manipulation in both cell lines. We thus propose that effects of SIRT1 to extend healthspan include influences on the DNA methylation status of genes affected during ageing, in particular PCGTs.
2014-06-30 | GSE54072 | GEO
Project description:Beneficial effects of SIRT1 on healthspan are likely to be pleiotropic and may include effects on DNA methylation. We demonstrated recently that manipulating SIRT1 in human cells affected DNA methylation of a panel of test genes, and that genes with expression modified by dietary restriction corresponded with genes that underwent changes in DNA methylation during ageing. Here we tested the hypothesis that genes particularly susceptible to SIRT1-induced effects on DNA methylation across the genome map to genes for which DNA methylation changes during ageing. We increased or reduced SIRT1 expression in human intestinal (Caco-2) and vascular endothelial (HuVEC) cells by transient transfection with an expression construct or with siRNA, respectively. Effects on DNA methylation were measured by enriching for the methylated fraction then either sequencing (HuVEC) or hybridising to a human promoter microarray (Caco-2). Effects using these two different cell lines and techniques for analysis were remarkably consistent. Genes with a DNA methylation status affected by SIRT1 manipulation were enriched for those that undergo age-dependent changes in DNA methylation, thus supporting our hypothesis. Polycomb group protein target genes (PCGTs), which are suppressed by epigenetic mechanisms in stem cells and have been shown previously to correspond with loci particularly susceptible to age-related changes in DNA methylation, were over-represented within the set of genes showing altered DNA methylation in response to SIRT1 manipulation in both cell lines. We thus propose that effects of SIRT1 to extend healthspan include influences on the DNA methylation status of genes affected during ageing, in particular PCGTs.
2014-03-31 | GSE53569 | GEO
Project description:Cellular senescence plays a causal role in ageing and, in mouse, depletion of p16INK4a-expressing senescent cells delays ageing-associated disorders. Adenosine deaminases acting on RNA (ADARs) RNA editing enzymes are also implicated as important regulators of human ageing and ADAR inactivation causes age-associated pathologies such as neurodegeneration in model organisms. However, the role, if any, of ADARs in cellular senescence is unknown. Here we show that ADAR1 is post-transcriptionally downregulated by autophagic degradation to promote senescence through upregulating p16INK4a. ADAR1 is downregulated during senescence post-transcriptionally by autophagy-lysosomal pathway and the downregulation is sufficient to drive senescence in both in vitro and in vivo models. Senescence induced by ADAR1 downregulation is p16INK4a dependent and independent of its RNA editing function. Mechanistically, ADAR1 promotes SIRT1 expression by affecting its RNA stability through HuR, an RNA binding protein that increases the half-life and steady state levels of its target mRNAs. And SIRT1, in turn, antagonizes translation of mRNA encoding p16INK4a. Hence, downregulation of ADAR1 and SIRT1 mediates p16INK4aupregulation by enhancing its mRNA translation. Finally, Adar1 is downregulated during ageing of mouse tissues such as brain, ovary, and intestine, and Adar1 expression correlates with Sirt1 expression in these tissues in mice. Together, our study reveals an RNA-editing independent role of ADAR1 in regulating senescence by post-transcriptionally controlling p16INK4a expression.
2022-04-25 | GSE179423 | GEO
Project description:Polycomb group proteins play a critical role in silencing transcription during development. It is commonly proposed that Polycomb dependent changes in genome folding, which compact chromatin, contribute directly to repression by blocking binding of activating complexes. Recently, it has also been argued that liquid-liquid demixing of Polycomb proteins facilitates this compaction and repression by phase-separating target genes into a membraneless compartment. To test these models, we utilized Optical Reconstruction of Chromatin Architecture (ORCA) to trace the Hoxa gene cluster, a canonical Polycomb target, in thousands of single cells. Across multiple cell types, we find that Polycomb-bound chromatin frequently explores decompact states and partial mixing with neighboring chromatin, while remaining uniformly repressed, challenging the repression-by-compaction or phase-separation models. Using polymer simulations, we show that these observed flexible ensembles can be explained by “spatial feedback”: transient contacts that contribute to propagation of the epigenetic state, (epigenetic memory) without inducing a globular organization.
2024-02-08 | GSE237501 | GEO
Project description:Polycomb group (PcG) proteins dynamically define cellular identities through epigenetic repression of key developmental genes. PcG target gene repression can be stabilized through the interaction in the nucleus at PcG foci. Here, we report the results of a high-resolution microscopy genome-wide RNAi screen that identifies 129 genes that regulate the nuclear organization of Pc foci. Candidate genes include PcG components and chromatin factors, as well as many novel protein-modifying enzymes, including components of the SUMOylation pathway. In the absence of SUMO Pc foci coagulate into larger aggregates. Conversely, loss of function of the SUMO peptidase velo disperses Pc foci. Moreover, SUMO and velo colocalize with PcG proteins at PREs and Pc SUMOylation affects its chromatin targeting, suggesting that the dynamic regulation of Pc SUMOylation regulates PcG-mediated silencing by modulating the kinetics of Pc binding to chromatin as well as its ability to form Polycomb foci. ChIP-Seq mapping of Polycomb (PC), SUMO and Velo on Drosophila Melanogaster
2014-04-03 | E-GEOD-55303 | biostudies-arrayexpress
Project description:In metazoans, the largest sirtuin, SIRT1, is a nuclear protein implicated in epigenetic modifications, circadian signaling, DNA recombination, replication and repair. Our previous studies have demonstrated that SIRT1 binds replication origins and inhibits replication initiation from a group of potential initiation sites (dormant origins). We studied the effects of aging and SIRT1 activity on replication origin usage and the incidence of transcription-replication collisions (creating R-loop structures) in adult human cells obtained at different time points during chronological aging and in cancer cells. In primary, untransformed cells, SIRT1 activity declined, and the prevalence of R-loops rose with chronological aging. Both the reduction of SIRT1 activity and the increased abundance of R-loops were also observed during the passage of primary cells in culture. All cells, regardless of donor age or transformation status, reacted to short-term, acute chemical inhibition of SIRT1 with the activation of excessive replication initiation events coincident with an increased prevalence of R-loops. However, only cancer cells showed genome-wide activation of dormant origins during long-term proliferation with mutated or depleted SIRT1, whereas in primary cells, aging-associated SIRT1-mediated activation of dormant origins was restricted to rDNA loci. These observations suggest that chronological aging and the associated decline in SIRT1 activity relaxes the regulatory networks that protect cells against excess replication and that the mechanisms protecting from replication-transcription collisions at the rDNA loci manifest as a differentially enhanced sensitivity to SIRT1 decline and chronological aging.
2023-11-27 | GSE247469 | GEO
Project description:Improved understanding of mechanisms regulating myelodysplastic syndrome (MDS) hematopoietic stem/progenitor cell (HSPC) growth and self-renewal is critical for developing MDS therapy. We revealed a novel regulatory axis that SIRT1-deficiency induced TET2 hyperacetylation promotes MDS HSPC functions, and provide an approach to target MDS HSPCs by activating SIRT1 deacetylase. Four Groups: Group1: MDS-L cells transduced with lentiviral vector targeting non-silence squence (control shRNA for SIRT1); Group2: MDS-L cells transduced with lentiviral vector containing interference squence targeting SIRT1 (SIRT shRNA); Group 3: MDS-L cells transduced with lentiviral vector targeting non-silence squence (control shRNA for TET2); Group 4: MDS-L cells transduced with lentiviral vector containing interference squence targeting TET2 (TET2 shRNA).
2018-08-13 | GSE117272 | GEO