Cellular and functional characterization of aging-independent senescent-like cells that modulate tissue repair
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE253863 | GEO | 2024/06/20
REPOSITORIES: GEO
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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.
2013-11-14 | E-GEOD-49108 | biostudies-arrayexpress
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
2011-01-21 | E-GEOD-24810 | biostudies-arrayexpress
Project description:Genome-wide comparative gene expression analysis of callus tissue of osteoporotic mice (Col1a1-Krm2 and Lrp5-/-) and wild-type were performed to identify candidate genes that might be responsible for the impaired fracture healing observed in Col1a1-Krm2 and Lrp5-/- mice. To investigate bone healing in osteoporosis, we performed fracture healing studies in wild-type mice (C57BL/6 genetic background) and the low bone mass strains Col1a1-Krm2 and Lrp5-/- (Schulze et al., 2010; Kato et al., 2002). Osteotomy was set in femora of female mice and stabilized by a semi-rigid fixator to allow fast bone healing (RM-CM-6ntgen et al., 2010). 21 days post surgery we analyzed the fracture calli by biochemical/histological methods, as well as micro-computed tomography, and observed impaired fracture healing in Col1a1-Krm2 and Lrp5-/- mice in comparison to wild-type. To identify genes that may be responsible for the impaired healing in osteoporotic mice, we performed microarray analysis of three independent callus samples of each genotype. The callus tissue was taken 10 days after surgery, because extensive bone formation took place at this point.
2013-10-25 | E-GEOD-51686 | biostudies-arrayexpress
Project description:Traumatic brain injury (TBI) accelerates fracture healing, but the underlying mechanism remains largely unknown. Accumulating evidence indicates that the central nervous system plays a pivotal role in regulating immune system and skeleton, however, the impact of TBI on hematopoiesis commitment was overlooked. Here, we found that the dramatically elevated sympathetic tone accompanied with TBI-accelerated fracture healing; chemical sympathectomy blocks TBI-induced fracture healing. Importantly, the adrenergic hypersensitivity swiftly skews bone marrow hematopoietic lineage cells toward anti-inflammation myeloid cells within 14 days, which favor fracture healing. Knockout of β3- or β2-adrenergic receptors (ARs) eliminate TBI mediated anti-inflammation macrophage expansion and TBI-accelerated fracture healing. Moreover, β3- and β2-ARs agonists synergistically promote M2 macrophages infiltration in callus and accelerate bone healing process. Our results suggest that TBI shapes the anti-inflammation environment during early stage of fracture healing, implicating the sympathetic nerve system as a potential target that can be exploited to treat fracture.
2023-04-12 | GSE229258 | GEO
Project description:Immune cells are essential for proper fracture healing. The goal of this study was to compare the transcriptional profiles of the CD45+ immune cells isolated from the healing fracture callus of old (24 month) and young (3 month) mice (C57BL/6). Analysis of all CD45+ cells was completed via single cell RNAseq. Additional analysis of the macrophages involved in fracture healing in old and young mice was performed via bulk RNAseq. We show that there were multiple subpopulations of macrophages that were transcriptionally heterogenous and present simultaneously within the fracture callus tissue. Attenuated healing in the old mice was associated with a transcriptional profile that shifted towards more pro-inflammatory phenotypes.
2024-05-31 | GSE198666 | GEO
Project description:The accumulation of senescent cells promotes aging, but a molecular mechanism that senescent cells use to evade immune clearance and accumulate remains to be elucidated. Here, we report that p16-positive senescent cells upregulate the immune checkpoint protein programmed death-ligand 1 (PD-L1) to accumulate in aging and chronic inflammation. p16-mediated inhibition of CDK4/6 promotes PD-L1 stability in senescent cells via the downregulation of ubiquitin-dependent degradation. p16 expression in infiltrating macrophages induces an immunosuppressive environment that can contribute to an increased burden of senescent cells. Treatment with immunostimulatory anti-PD-L1 antibody enhances the cytotoxic T cell activity and leads to the elimination of p16, PD-L1-positive cells. Our study uncovers a molecular mechanism of p16-dependent regulation of PD-L1 protein stability in senescent cells and reveals the potential of PD-L1 as a target for treating senescence-mediated age-associated diseases.
2024-02-14 | GSE225286 | GEO
Project description:The accumulation of senescent cells promotes aging, but a molecular mechanism that senescent cells use to evade immune clearance and accumulate remains to be elucidated. Here, we report that p16-positive senescent cells upregulate the immune checkpoint protein programmed death-ligand 1 (PD-L1) to accumulate in aging and chronic inflammation. p16-mediated inhibition of CDK4/6 promotes PD-L1 stability in senescent cells via the downregulation of ubiquitin-dependent degradation. p16 expression in infiltrating macrophages induces an immunosuppressive environment that can contribute to an increased burden of senescent cells. Treatment with immunostimulatory anti-PD-L1 antibody enhances the cytotoxic T cell activity and leads to the elimination of p16, PD-L1-positive cells. Our study uncovers a molecular mechanism of p16-dependent regulation of PD-L1 protein stability in senescent cells and reveals the potential of PD-L1 as a target for treating senescence-mediated age-associated diseases.
2024-02-14 | GSE225285 | GEO
Project description:Fracture healing is a process that involves many cell populations. In this study we characterized gene expression in a subset of cells involved in fracture healing. αSMACreERT2 mice crossed with Ai9 reporter mice that express tdTomato fluorescent protein after Cre-mediated activation were used as an experimental model. αSMA-expressing cells were labeled by tamoxifen administration, then periosteal cells from the tibia were isolated two days later (controls), or tibial fractures were performed and periosteum/soft callus tissue was collected after 2 and 6 days. The tdTomato positive cell population was isolated by flow cytometry, and subjected to microarray analysis. Histology and cell surface marker analysis indicates that αSMACreERT2 labels a mainly mesenchymal population in the periosteum that expands after fracture, and contributes to both osteogenic and chondrogenic elements of the fracture callus. We were therefore able to examine gene expression in a defined population during the early stages of fracture healing. Total RNA was obtained from the tomato positive cells within the periosteal compartment of fractures from αSMACreERT2/Ai9 mice. Control animals were given 2 doses of tamoxifen, and periosteum was collected and labeled cells sorted (8-9 sex-matched mice per group). Fractures were performed after the second dose of tamoxifen, and tomato positive cells from periosteum/callus tissue were isolated 2 and 6 days after fracture (4-8 animals per sample pooled). 3 replicates for each sample are included.
2013-11-27 | E-GEOD-45156 | biostudies-arrayexpress
Project description:Bone fractures, the most common musculoskeletal injuries, heal through three main phases: inflammatory, repair, and remodeling. Around 10% of fracture patients suffer from impaired healing that requires surgical intervention, a huge burden on the healthcare system. The rate of impaired healing increases with metabolic diseases such as obesity-associated hyperglycemia/type 2 diabetes (T2D), an increasing concern given the growing incidence of obesity/T2D. Immune cells play pivotal roles in fracture healing, and obesity/T2D is associated with defective immune-cell functions. However, there is a gap in knowledge regarding the stoichiometry of immune cells that populate the callus and how that population changes during different phases of healing. Here, we used complementary global and single-cell techniques to characterize the repertoire of immune cells in the fracture callus and to identify populations specifically enriched in the fracture callus relative to the unfractured bone or bone marrow. Our analyses identified two clear waves of immune-cell infiltration into the callus: the first wave occurs during the early inflammatory phase of fracture healing, while the second takes place during the late repair/early remodeling phase. Innate immune cells were activated during the early inflammatory phase, but in later phases they returned to homeostatic numbers and activation levels. Of the innate immune cells, distinct subsets of activated dendritic cells were particularly enriched in the inflammatory healing hematoma. In contrast to innate cells, lymphocytes, including B and T cells, were enriched and activated in the callus primarily during the late repair phase. The Diet-Induced Obesity (DIO) mouse, an established model of obesity-associated hyperglycemia and insulin resistance, suffers from multiple healing defects. Our data demonstrate that DIO mice exhibit dysregulated innate immune responses during the inflammatory phase, and defects in all lymphocyte compartments during the late repair phase. Taken together, our data characterize, for the first time, immune populations that are enriched/activated in the callus during two distinct phases of fracture healing and identify defects in the healing-associated immune response in DIO mice, which will facilitate future development of immunomodulatory therapeutics for impaired fracture healing.
2023-09-01 | GSE240390 | GEO
Project description:Bone regeneration is a highly efficient process allowing scarless healing after injury. The periosteum, the outer layer of bones, is a critical source of skeletal stem/progenitor cells (SSPCs), as well as immune, endothelial and neural cells during bone repair. In our study, we generated a single-nuclei atlas of the murine periosteal response to bone fracture. We generated single nuclei datasets from uninjured periosteum and from injured periosteum and hematoma/fracture callus at days 5 and 7 post-injury from wild-type mice.
2024-04-01 | GSE234451 | GEO