Project description:Blocking of nucleocytoplasmic trafficking is an essential feature of replicative senescence (RS). However, whether nuclear barrier per se causes cellular senescence still remains elusive. Here, we show that nuclear barrier induced by blocking nucleocytoplasmic trafficking, especially nuclear export, elicits RS-like changes in SA-β-gal activity, DNA damage, and expression of cell cycle regulators. Comparative transcriptome analysis revealed that nuclear barrier-induced senescence (NBIS) was most similar in gene expression changes to RS compared to senescence induced by stresses (oxidative stress, DNA damage and oncogene), implying that nuclear barrier induces RS-like physiological senescence-associated changes. Shared senescence-related processes between NBIS and RS included lysosomal degradation, nuclear transport, and translation, resulting in coordinated reduction in transmission of extrinsic signals to nucleus and intracellular protein supply from nucleus. Notably, these processes were conserved in yeast aging. Therefore, we propose NBIS as a novel modality of cellular senescence, representing the fundamental nature of physiological aging in eukaryotes.
Project description:Senescent cells exhibit a reduced response to intrinsic and extrinsic stimuli. This reduction could be explained by disrupted nuclear transmission of signals. However, this hypothesis required more evidence to complete as a new modality of cellular senescence. Proteomic analysis of the cytoplasmic and nuclear fractions from young and senescent cells revealed disruption of nucleocytoplasmic trafficking (NCT) as an essential feature of replicative senescence (RS) at the global level. Blocking NCT either chemically or genetically induced RS-like senescence phenotypes, named as nuclear barrier-induced senescence (NBIS). Transcriptomic analysis revealed that NBIS had the most similar gene expression pattern to RS, compared with other stress-induced types of cellular senescence. Core proteomic and transcriptomic shared patterns between RS and NBIS included upregulation of endocytosis-lysosome network and downregulation of NCT in senescent cells, which were also conserved in yeast aging model. These results implicate an aging-dependent coordinated reduction in the transmission of extrinsic signals to the nucleus and in the nucleus-to-cytoplasm supply of proteins/RNAs. We further showed that the aging-associated decrease in Sp1 transcription factor expression was responsible for downregulation of NCT. Our results suggest that NBIS is a modality of cellular senescence that can represent the nature of physiological aging in eukaryotes.
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 is a stress response that activates innate immunity. However, the interplay between senescent cells and the adaptive immune system remains largely unexplored. Here, we show that senescent cells display enhanced MHC class I (MHC-I) antigen processing and presentation. Immunization of mice with senescent syngeneic fibroblasts generates CD8 T cells reactive against both normal and senescent fibroblasts, some of them targeting senescence-associated MHC-I-peptides. In the context of cancer, we demonstrate that senescent cancer cells trigger strong anti-tumor protection mediated by antigen-presenting cells and CD8 T cells. This response is superior to the protection elicited by cells undergoing immunogenic cell death. Finally, induction of senescence in patient-derived cancer cells exacerbates the activation of autologous tumor-reactive CD8 tumor-infiltrating lymphocytes (TILs) with no effect on non-reactive TILs. Our study indicates that immunization with senescent cancer cells strongly activates anti-tumor immunity, and this can be exploited for cancer therapy.
Project description:Senescence, the irreversible cell cycle arrest of damaged cells, is accompanied by a deleterious pro-inflammatory senescence-associated secretory phenotype (SASP). Senescence and the SASP are major factors in aging, cancer, and degenerative diseases, and interfere with the expansion of adult cells in vitro, yet little is known about how to counteract their induction and deleterious effects. Paracrine signals are increasingly recognized as important senescence triggers and understanding their regulation and mode of action may provide novel opportunities to reduce senescence-induced inflammation and improve cell-based therapies. Here, we show that the signalling protein WNT3A counteracts senescence in cultured human adult multipotent stromal cells (MSCs) by limiting paracrine senescence. We find that entry into senescence in a small subpopulation of MSCs triggers a secretome that causes a feed-forward signalling cascade that with increasing speed induces healthy cells into senescence. WNT signals interrupt this cascade by repressing cytokines that mediate this induction of senescence. Inhibition of those mediators by interference with NF-kB or interleukin 6 signalling reduced paracrine senescence in absence of WNT3A and promoted the expansion of MSCs. Our work reveals how WNT signals can antagonize senescence and has relevance not only for expansion of adult cells but can also provide new insights into senescence-associated inflammatory and degenerative diseases. // The RNAseq data in particular focusses on the transcriptome changes in MSCs occuring in vitro culture over four passages in presence or absence of growth factors WNT3A and FGF2.
Project description:To investigate the molecular basis of senescence-induced dedifferentiation, we performed RNAseq on control proliferating cells (DMSO only) and etoposide-induced senescent cells to profile senescence induction. Additionally, we performed RNAseq on purified populations of differentiated myotubes derived from untreated A1 cells to investigate differentiation, as well as myotubes subsequently induced to dedifferentiate, either by serum exposure (10% FCS) or by exposure to 48 hour conditioned media from senescent cells (including proliferating cell conditioned media controls). We then performed gene expression profiling analysis using data obtained from RNA-seq of all 6 populations in triplicate.