Project description:Limited data exists regarding changes of microRNA (miRNA) expression during senescence in human cells and no reports correlate telomerase expression with regulation of senescence-related miRNAs. We used miRNA microarrays to provide a detailed account of miRNA profiles for early passage and senescent human foreskin (BJ) fibroblasts as well as early and late passage immortalized fibroblasts (BJ-hTERT) that stably express the human telomerase reverse transcriptase subunit hTERT. The revelation that miRNA expression changes with extended passaging in BJ-hTERT cells will contribute to a comprehensive understanding of the connections between telomerase expression, senescence and processes of cellular aging.
Project description:We utilized whole genome sequencing of mRNA (RNA-seq) to understand the extent to which the senescence-associated secretory phenotype is regulated by p38MAPK Examination of replicates of young, senescent or p38MAPK-inhibited senescent BJ human foreskin fibroblasts.
Project description:Quantitative analysis of global proteomic changes in proliferating and senescent BJ fibroblasts, treated with eIF5A hypusination inhibitor GC7 (10 uM) for 12h.
Project description:The expansion of repressive epigenetic marks has been implicated in heterochromatin formation during embryonic development, but the general applicability of this mechanism is unclear. Here we show that nuclear rearrangement of repressive histone marks H3K9me3 and H3K27me3 into non-overlapping structural layers characterizes senescence-associated heterochromatic foci (SAHF) formation in human fibroblasts. However, the global landscape of these repressive marks remains unchanged upon SAHF formation, suggesting that in somatic cells heterochromatin can be formed through the spatial repositioning of pre-existing repressively marked histones. This model is reinforced by the correlation of pre-senescent replication timing with both the subsequent layered structure of SAHFs and the global landscape of the repressive marks, allowing us to integrate microscopic and genomic information. Furthermore, modulation of SAHF structure does not affect the occupancy of these repressive marks nor vice versa. These experiments reveal that high-order heterochromatin formation and epigenetic remodeling of the genome can be discrete events. ChIP-seq for different histone marks in both growing and Ras-induced senescent fibroblasts, in the presence or absence of certain sh-RNAs K9me3Grow2.bed (growing) Chip Seq Analysis of H3K9me3 in ER:Ras expressing IMR90 human diploid fibroblasts d6 4OHT K9me3Sen2.bed (senescent) Chip Seq Analysis of H3K9me3 in ER:Ras expressing IMR90 human diploid fibroblasts with no treatment K9me2Grow3.bed (growing) Chip Seq Analysis of H3K9me2 in ER:Ras expressing IMR90 human diploid fibroblasts with no treatment K9me2Sen3.bed (senescent) Chip Seq Analysis of H3K9me2 in ER:Ras expressing IMR90 human diploid fibroblasts d6 4OHT K27me3Sen3.bed (senescent) Chip Seq Analysis of H3K27me3 in ER:Ras expressing IMR90 human diploid fibroblasts d6 4OHT K27me3Grow2.bed (growing) Chip Seq Analysis of H3K27me3 in ER:Ras expressing IMR90 human diploid fibroblasts with no treatment K36me3Grow2.bed (growing) Chip Seq Analysis of H3K36me3 in ER:Ras expressing IMR90 human diploid fibroblasts with no treatment K36me3Sen2.bed (senescent) Chip Seq Analysis of H3K36me3 in ER:Ras expressing IMR90 human diploid fibroblasts d6 4OHT K4me3Grow2.bed (growing) Chip Seq Analysis of H3K4me3 in ER:Ras expressing IMR90 human diploid fibroblasts with no treatment K4me3Sen3.bed (senescent) Chip Seq Analysis of H3K4me3 in ER:Ras expressing IMR90 human diploid fibroblasts d6 4OHT
Project description:Cellular senescence is a program of irreversible cell cycle arrest that normal cells undergo in response to progressive shortening of telomeres, changes in telomeric structure, oncogene activation or oxidative stress. The underlying signalling pathways, potentially of major clinicopathological relevance, are unknown. A major stumbling block to studying senescence has been the absence of suitable model systems because of the asynchrony of this process in heterogeneous cell populations. To simplify this process many investigators study oncogene-induced senescence due to expression of activated oncogenes where senescence occurs prematurely without telomere attrition and can be induced acutely in a variety of cell types. We have taken a different approach by making use of the finding that reconstitution of telomerase activity by introduction of the catalytic subunit of human telomerase alone is incapable of immortalising all human somatic cells, but inactivation of the p16-pRB and p53-p21 pathways are required in addition. The ability of SV40 large T antigen to inactivate the p16-pRB and p53-p21 pathways has enabled us to use a thermolabile mutant of LT antigen, in conjunction with hTERT, to develop conditionally immortalised human (HMF3A) fibroblasts that are immortal but undergo an irreversible growth arrest when the thermolabile LT antigen is inactivated leading to activation of pRB and p53. When these cells cease dividing, senescence-associated- b-galactosidase activity is induced and the growth-arrested cells have morphological features and express genes in common with senescent cells. Since these cells growth arrest in a synchronous manner they are an excellent starting point for dissecting the pathways that underlie cellular senescence and act downstream of p16-pRB and p53-p21 pathways. We have combined genome-wide expression profiling with genetic complementation to undertake identification of genes that are differentially expressed when these conditionally immortalised human fibroblasts undergo senescence upon activation of the p16-pRB and p53-p21 tumour suppressor pathways. Genes differentially expressed upon senescence will be identified by comparing arrays from growing versus senescent cells. Changes in gene expression due to the temperature shift will be eliminated by comparing with array data from the non-conditional HMF3S cells grown at 34°C ±0.5°C and 38°C ±0.5°C. To determine if the changes in gene expression upon senescence are specific and reversible, the set of differential genes will then be overlaid with array data from cells in which senescence has been bypassed by inactivation of the p16-pRB and p53-p21 tumour suppressor pathways
Project description:Human BJ fibroblasts were treated with FLI-06 and gene expression was compared to untreated fibroblasts. RNA-seq data comprises 2 groups: treated and untreated BJ fibroblasts. Jena Centre for Systems Biology of Ageing - JenAge (www.jenage.de)
Project description:Cellular senescence is described as an irreversible cell cycle arrest induced in response to various stresses. Senescent cells are characterised by heterogeneous signalling alterations, complex secretory phenotype, known as senescence-associated secretory phenotype (SASP), and diverse transcriptomic profile. With the aim to investigate senescence heterogeneity and identify conserved transctiptomic alterations and universal senescence markers, we performed RNA-seq and multiplex proteomic analysis in proteasome inhibition-induced and stress-induced premature senescence models of HFL1 and BJ human fibroblasts. Our data revealed diverse transcriptomic signatures, but also, 231 common differentially expressed genes related to cell division and ECM remodelling, and enriched pathways that remained conserved among the different models with senescence onset. Moreover, we identified a subset of proteins and validated them in replicative senescent models. These proteins are involved in cell cycle arrest and promote a pro-inflammatory environment in premature and replicative senescence models. We suggest that the simultaneous analysis of p21, p-c-JUN, BCL-xL and survivin in cellular lysates, and IL-8, GM-CSF, GDF-15 and GROa in culture supernatants can provide a powerful tool for the identification and monitoring of senescent cells and can support the assessment of the efficacy of potential senotherapeutic approaches.
Project description:Comparison of gene expression of human BJ fibroblasts at different population doublings (PD). RNA-seq data comprises 2 groups: 34 and 70 population doublings of BJ fibroblasts. Jena Centre for Systems Biology of Ageing - JenAge (www.jenage.de)