Aging is associated with increased chromatin accessibility and reduced polymerase pausing in liver [NET-seq]
Ontology highlight
ABSTRACT: Regulation of gene expression is linked to the organization of the genome. With age, chromatin alterations occur on all levels of genome organization, accompanied by changes in the gene expression profile. However, little is known about the changes on the level of transcriptional regulation. Here, we used a multi-omics approach and integrated ATAC-, RNA- and NET-seq to identify age-related changes in the chromatin landscape of murine liver and to investigate how these are linked to transcriptional regulation. We provide the first systematic inventory of the connection between aging, chromatin accessibility and transcriptional regulation in a whole tissue. Aging in murine liver is characterized by an increase in chromatin accessibility at promoter regions, but not in an increase of transcriptional output. Instead, aging is accompanied by a decrease of promoter-proximal pausing of RNA polymerase II (Pol II), while initiation of transcription is not decreased as assessed by RNA polymerase mapping using CUT&RUN. Based on the data reported we propose that these age-related changes in transcriptional regulation are due to a reduced stability of the pausing complex.
Project description:Regulation of gene expression is linked to the organization of the genome. With age, chromatin alterations occur on all levels of genome organization, accompanied by changes in the gene expression profile. However, little is known about the changes on the level of transcriptional regulation. Here, we used a multi-omics approach and integrated ATAC-, RNA- and NET-seq to identify age-related changes in the chromatin landscape of murine liver and to investigate how these are linked to transcriptional regulation. We provide the first systematic inventory of the connection between aging, chromatin accessibility and transcriptional regulation in a whole tissue. Aging in murine liver is characterized by an increase in chromatin accessibility at promoter regions, but not in an increase of transcriptional output. Instead, aging is accompanied by a decrease of promoter-proximal pausing of RNA polymerase II (Pol II). We propose that these changes in transcriptional regulation are due to a reduced stability of the pausing complex and may represent a mechanism to compensate for the age-related increase in chromatin accessibility in order to prevent aberrant transcription.
Project description:Regulation of gene expression is linked to the organization of the genome. With age, chromatin alterations occur on all levels of genome organization, accompanied by changes in the gene expression profile. However, little is known about the changes on the level of transcriptional regulation. Here, we used a multi-omics approach and integrated ATAC-, RNA- and NET-seq to identify age-related changes in the chromatin landscape of murine liver and to investigate how these are linked to transcriptional regulation. We provide the first systematic inventory of the connection between aging, chromatin accessibility and transcriptional regulation in a whole tissue. Aging in murine liver is characterized by an increase in chromatin accessibility at promoter regions, but not in an increase of transcriptional output. Instead, aging is accompanied by a decrease of promoter-proximal pausing of RNA polymerase II (Pol II), while initiation of transcription is not decreased as assessed by RNA polymerase mapping using CUT&RUN. Based on the data reported we propose that these age-related changes in transcriptional regulation are due to a reduced stability of the pausing complex.
Project description:Regulation of gene expression is linked to the organization of the genome. With age, chromatin alterations occur on all levels of genome organization, accompanied by changes in the gene expression profile. However, little is known about the changes on the level of transcriptional regulation. Here, we used a multi-omics approach and integrated ATAC-, RNA- and NET-seq to identify age-related changes in the chromatin landscape of murine liver and to investigate how these are linked to transcriptional regulation. We provide the first systematic inventory of the connection between aging, chromatin accessibility and transcriptional regulation in a whole tissue. Aging in murine liver is characterized by an increase in chromatin accessibility at promoter regions, but not in an increase of transcriptional output. Instead, aging is accompanied by a decrease of promoter-proximal pausing of RNA polymerase II (Pol II), while initiation of transcription is not decreased as assessed by RNA polymerase mapping using CUT&RUN. Based on the data reported we propose that these age-related changes in transcriptional regulation are due to a reduced stability of the pausing complex.
Project description:Regulation of gene expression is linked to the organization of the genome. With age, chromatin alterations occur on all levels of genome organization, accompanied by changes in the gene expression profile. However, little is known about the changes on the level of transcriptional regulation. Here, we used a multi-omics approach and integrated ATAC-, RNA- and NET-seq to identify age-related changes in the chromatin landscape of murine liver and to investigate how these are linked to transcriptional regulation. We provide the first systematic inventory of the connection between aging, chromatin accessibility and transcriptional regulation in a whole tissue. Aging in murine liver is characterized by an increase in chromatin accessibility at promoter regions, but not in an increase of transcriptional output. Instead, aging is accompanied by a decrease of promoter-proximal pausing of RNA polymerase II (Pol II), while initiation of transcription is not decreased as assessed by RNA polymerase mapping using CUT&RUN. Based on the data reported we propose that these age-related changes in transcriptional regulation are due to a reduced stability of the pausing complex.
Project description:Regulation of gene expression is linked to the organization of the genome. With age, chromatin alterations occur on all levels of genome organization, accompanied by changes in the gene expression profile. However, little is known about the changes on the level of transcriptional regulation. Here, we used a multi-omics approach and integrated ATAC-, RNA- and NET-seq to identify age-related changes in the chromatin landscape of murine liver and to investigate how these are linked to transcriptional regulation. We provide the first systematic inventory of the connection between aging, chromatin accessibility and transcriptional regulation in a whole tissue. Aging in murine liver is characterized by an increase in chromatin accessibility at promoter regions, but not in an increase of transcriptional output. Instead, aging is accompanied by a decrease of promoter-proximal pausing of RNA polymerase II (Pol II), while initiation of transcription is not decreased as assessed by RNA polymerase mapping using CUT&RUN. Based on the data reported we propose that these age-related changes in transcriptional regulation are due to a reduced stability of the pausing complex.
Project description:Promoter-proximal RNA polymerase II (Pol II) pausing is implicated in the regulation of gene transcription. However, the mechanisms of pausing including its dynamics during transcriptional responses remain to be fully understood. We performed global analysis of short capped RNAs and Pol II Chromatin Immunoprecipitation sequencing in MCF-7 breast cancer cells to map Pol II pausing across the genome, and used permanganate footprinting to specifically follow pausing during transcriptional activation of several genes involved in the Epithelial to Mesenchymal Transition (EMT). We find that the gene for EMT master regulator Snail (SNAI1), but not Slug (SNAI2), shows evidence of Pol II pausing before activation. Transcriptional activation of the paused SNAI1 gene is accompanied by a further increase in Pol II pausing signal whereas activation of non-paused SNAI2 gene results in the acquisition of a typical pausing signature. The increase in pausing signal reflects increased transcription initiation without changes in Pol II pausing. Activation of the heat shock HSP70 gene involves pausing release that speeds up Pol II turnover, but does not change pausing location. We suggest that Pol II pausing is retained during transcriptional activation and can further undergo regulated release in a signal-specific manner. Untreated MCF-7 cells were analyzed for the distribution of Pol II using ChIP-sequencing with Anti-Pol II N-20 antibody (two independent biological replicates, A, B), and for the distribution of paused RNA polymerase II by sequencing of short capped RNAs (scRNAs) prepared from nuclei (three independent biological replicates, 1-3). All samples were sequenced on a MiSeq instrument in paired-end format
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.