Project description:Immune checkpoint bloackade (ICB)-based or natural cancer immune responses largely eliminate tumours. Yet, they require additional mechanisms to arrest those cancer cells that are not rejected. Cytokine-induced senescence (CIS) can stably arrest cancer cells, suggesting that interferon-dependent induction of senescence-inducing cell cycle regulators is needed to control those cancer cells that escape from killing. Here we report in two different cancers sensitive to T cell-mediated rejection, we show that deletion of the senescence-inducing cell cycle regulators p16Ink4a/p19Arf (Cdkn2a) or p21Cip1 (Cdkn1a) in the tumour cells abrogated both, the natural and the ICB-induced cancer immune control. Also in humans, melanoma metastases that progressed rapidly during ICB have losses of senescence-inducing genes and amplifications of senescence inhibitors. Metastatic cells also resist CIS. Such genetic and functional alterations are infrequent in metastatic melanomas regressing during ICB. Thus, activation of tumour-intrinsic, senescence-inducing cell cycle regulators is required to stably arrest those cancer cells that escape from eradication.
Project description:Cellular senescence disables the proliferation of damaged cells and it is relevant for cancer and aging. Here, we show that cellular senescence occurs during mammalian embryonic development. Specifically, we have focused on the mouse regressing mesonephros and the endolymphatic sac of the inner ear. Senescence is characterized by SAM-NM-2G activity, heterochromatinization, and proliferative arrest. Mechanistically, developmentally-programmed senescence at the mesonephros and endolymphatic sac is strictly dependent on p21, but independent of DNA damage, p53 or other cell cycle inhibitors, and it is regulated by the TGFM-NM-2/SMAD and PI3K/FOXO pathways. Developmentally-programmed senescence is followed by macrophage infiltration and clearance of senescent cells. Abrogation of senescence by p21 deletion is only partially compensated by apoptosis and originates detectable developmental abnormalities. Importantly, high levels of p21 are also associated to the regressing mesonephros and endolymphatic sac in human embryos. These findings place cellular senescence as a relevant morphogenic process during embryonic development. We microdissected mesonephric tubules from senescent (WT) and non-senescent (p21-null) embryos to get information about this new senescence that occurs during embryogenesis.
Project description:Although CD4 T cell senescence plays an important role in immunosenescence, the mechanisms remain unclear. We found that T cell-specific Menin deficiency results in the premature senescence of CD4 T cells, accompanied by the senescence-associated secretory phenotype (SASP) after antigenic stimulation. TH1 and TH2 differentiation was dysregulated in Menin-knockout CD4 T cells. Bach2, which regulates SASP and TH differentiation, was identified as a Menin target. Menin binds to the Bach2 locus, and controls its expression through maintenance of histone acetylation. These findings reveal a critical role of the Menin-Bach2 pathway in regulating CD4 T cell senescence and homeostasis, thus indicating the involvement of this pathway in the inhibition of age-associated development of inflammatory diseases, which are induced by immunosenescence. Examination of transcriptional factor Menin binding and histone modefications in Menin WT and KO CD4 T cells
Project description:Senescence in WI-38 cell context was induce by RASv12 over expression Cellular senescence is a permanent cell cycle arrest that is triggered by cancer- initiating or promoting events in mammalian cells and is now considered a major tumour suppressor mechanism. Here, we did a transcriptomic analysis and compared WI-38 contol wich is a human fibroblaste cell line and WI-38 that overexpressed RASv12 a G protein that induce senescence. The goal of our project is to compare transciptomic profile of human growing fibroblast (WI-38 control) and senescent human fibroblast (WI-38 OERAS) Comparaison WI-38 vs WI-38 OE RAS
Project description:Cellular senescence is an irreversible growth arrest with a highly dynamic secretome, termed the senescence-associated secretory phenotype (SASP). Senescence has been implicated in somatic reprogramming to pluripotency. The cell-intrinsic proliferation arrest is a barrier for reprogramming, whereas the SASP facilitates the cell fate conversion in nonsenescent cells. However, the mechanisms by which reprogramming-induced senescence regulates cell plasticity are not well understood. Here, we have further investigated how the heterogeneity of paracrine senescence impacts reprogramming. We show that senescence promotes in vitro reprogramming in a stress-dependent manner. We identified a catalog of SASP factors and pathways potentially involved in the cell fate conversion using an unbiased proteomic analysis. Amphiregulin (AREG), a growth factor frequently secreted by the senescent cells, promotes in vitro reprogramming by accelerating proliferation and MET via the EGFR signaling pathway. Of note, AREG treatment diminished the negative effect of donor age on reprogramming. Finally, AREG enhances in vivo reprogramming in the skeletal muscle. Hence, senescence could facilitate cellular plasticity via various SASP factors to promote reprogramming and tissue repair.
Project description:Long non-coding RNAs (lncRNAs) regulate diverse cellular processes and are associated with many age-associated diseases. However, the function of lncRNAs in cellular senescence remains largely unknown. Here we characterize the role of lncRNA H19 in senescence. We show that H19 levels decline as cells undergo senescence, and depletion of H19 results in premature senescence. We find that repression of H19 is triggered by the loss of CTCF and prolonged activation of p53 as part of the senescence pathway. Mechanistically, the loss of H19 drives senescence via increased let7b mediated targeting of EZH2. We further demonstrate that H19 is required for senescence inhibition by the mTOR inhibitor rapamycin, where it maintains lncRNA H19 levels throughout the cellular lifespan and thus prevents the reduction of EZH2 that would otherwise lead to cellular senescence. Therefore, lncRNA H19 is crucial in maintaining the balance between sustained cell growth and the onset of senescence.
Project description:In cell senescence, cultured cells cease proliferating and acquire aberrant gene expression patterns. MicroRNAs (miRNAs) modulate gene expression through translational repression or mRNA degradation, and have been implicated in senescence. We have used deep sequencing to carry out a comprehensive survey of miRNA expression and its involvement in cell senescence. Informatic analysis of small RNA sequence datasets from young and senescent IMR90 human fibroblasts identifies many known miRNAs, and a small number of novel miRNAs, that are regulated (either up or down) with cell senescence. Comparison with mRNA expression profiles revealed potential mRNA targets of the senescence-regulated miRNAs. The target mRNAs are enriched for genes involved in biological processes associated with cell senescence. This result greatly extends existing information on the role of miRNAs in cell senescence, and is consistent with miRNAs having a causal role in the process.
Project description:Sirtuin 3 (SIRT3) is an NAD+-dependent deacetylase involved in various physiological and pathological processes. However, the role of SIRT3 in regulating human stem cell senescence remains largely unknown. Here, we observed the downregulated expression of SIRT3 in senescent human mesenchymal stem cells (hMSCs). SIRT3 deficiency accelerated cellular senescence in hMSCs, along with compromised nuclear integrity, loss of heterochromatin and increased DNA damage. These aging-associated nuclear defects were attenuated by the reintroduction of SIRT3. Mechanistic studies demonstrated the interaction of SIRT3 with nuclear envelope proteins and heterochromatin-associated proteins. Further findings revealed that SIRT3 deficiency led to the loss of lamina-associated domains (LADs) from the nuclear lamina, increased chromatin accessibility and aberrant transcription of repetitive sequences. Meanwhile, the overexpression of nuclear-localized SIRT3 rescued the senescence phenotypes. Taken together, our study reveals a novel role of nuclear SIRT3 in stabilizing heterochromatin and counteracting hMSC senescence, which may provide new clinical therapeutic targets to ameliorate aging-related diseases.
Project description:In cell senescence, cultured cells cease proliferating and acquire aberrant gene expression patterns. MicroRNAs (miRNAs) modulate gene expression through translational repression or mRNA degradation, and have been implicated in senescence. We have used deep sequencing to carry out a comprehensive survey of miRNA expression and its involvement in cell senescence. Informatic analysis of small RNA sequence datasets from young and senescent IMR90 human fibroblasts identifies many known miRNAs, and a small number of novel miRNAs, that are regulated (either up or down) with cell senescence. Comparison with mRNA expression profiles revealed potential mRNA targets of the senescence-regulated miRNAs. The target mRNAs are enriched for genes involved in biological processes associated with cell senescence. This result greatly extends existing information on the role of miRNAs in cell senescence, and is consistent with miRNAs having a causal role in the process. Comprehensive survey of miRNA from young and senescent IMR90 fibroblasts using deep sequencing
Project description:Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders, the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown. Here, we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem cells (hMSCs). Genetic inactivation of 4E-BP1 in hMSCs accelerates cellular senescence, compromises mitochondrial respiration and increases mitochondrial ROS production. Mechanistically, the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes, especially several key subunits of the complex III including UQCRC2. Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs. These findings together demonstrate that 4E-BP1 functions as a geroprotector to alleviate human stem cell senescence and maintain mitochondrial homeostasis, particularly for the mitochondrial respiration complex III and provide a new potential target to counteract human stem cell senescence.