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Coppé JP, Desprez PY, Krtolica A, Campisi J. The senescence-associated secretory phenotype: the dark side of tumor suppression. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2010; 5:99-118. [PMID: 20078217 DOI: 10.1146/annurev-pathol-121808-102144] [Citation(s) in RCA: 3304] [Impact Index Per Article: 236.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cellular senescence is a tumor-suppressive mechanism that permanently arrests cells at risk for malignant transformation. However, accumulating evidence shows that senescent cells can have deleterious effects on the tissue microenvironment. The most significant of these effects is the acquisition of a senescence-associated secretory phenotype (SASP) that turns senescent fibroblasts into proinflammatory cells that have the ability to promote tumor progression.
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Affiliation(s)
- Jean-Philippe Coppé
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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152
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Abstract
SUMOylation is a highly transient post-translational protein modification. Attachment of SUMO to target proteins occurs via a number of specific activating and ligating enzymes that form the SUMO-substrate complex, and other SUMO-specific proteases that cleave the covalent bond, thus leaving both SUMO and target protein free for the next round of modification. SUMO modification has major effects on numerous aspects of substrate function, including subcellular localisation, regulation of their target genes, and interactions with other molecules. The modified SUMO-protein complex is a very transient state, and it thus facilitates rapid response and actions by the cell, when needed. Like phosphorylation, acetylation and ubiquitination, SUMOylation has been associated with a number of cellular processes. In addition to its nuclear role, important sides of mitochondrial activity, stress response signalling and the decision of cells to undergo senescence or apoptosis, have now been shown to involve the SUMO pathway. With ever increasing numbers of reports linking SUMO to human disease, like neurodegeneration and cancer metastasis, it is highly likely that novel and equally important functions of components of the SUMOylation process in cell signalling pathways will be elucidated in the near future.
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Affiliation(s)
- Artemisia M Andreou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Crete, Greece
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153
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Gruber HE, Hoelscher GL, Ingram JA, Zinchenko N, Hanley EN. Senescent vs. non-senescent cells in the human annulus in vivo: cell harvest with laser capture microdissection and gene expression studies with microarray analysis. BMC Biotechnol 2010; 10:5. [PMID: 20109216 PMCID: PMC2828399 DOI: 10.1186/1472-6750-10-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 01/28/2010] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Senescent cells are well-recognized in the aging/degenerating human disc. Senescent cells are viable, cannot divide, remain metabolically active and accumulate within the disc over time. Molecular analysis of senescent cells in tissue offers a special challenge since there are no cell surface markers for senescence which would let one use fluorescence-activated cell sorting as a method for separating out senescent cells. METHODS We employed a novel laser capture microdissection (LCM) design to selectively harvest senescent and non-senescent annulus cells in paraffin-embedded tissue, and compared their gene expression with microarray analysis. LCM was used to separately harvest senescent and non-senescent cells from 11 human annulus specimens. RESULTS Microarray analysis revealed significant differences in expression levels in senescent cells vs non-senescent cells: 292 genes were upregulated, and 321 downregulated. Genes with established relationships to senescence were found to be significantly upregulated in senescent cells vs. non-senescent cells: p38 (MPAK14), RB-Associated KRAB zinc finger, Discoidin, CUB and LCCL domain, growth arrest and DNA-damage inducible beta, p28ING5, sphingosine-1-phosphate receptor 2 and somatostatin receptor 3; cyclin-dependent kinase 8 showed significant downregulation in senescent cells. Nitric oxidase synthase 1, and heat shock 70 kDa protein 6, both of which were significantly down-regulated in senescent cells, also showed significant changes. Additional genes related to cytokines, cell proliferation, and other processes were also identified. CONCLUSIONS Our LCM-microarray analyses identified a set of genes associated with senescence which were significantly upregulated in senescent vs non-senescent cells in the human annulus. These genes include p38 MAP kinase, discoidin, inhibitor of growth family member 5, and growth arrest and DNA-damage-inducible beta. Other genes, including genes associated with cell proliferation, extracellular matrix formation, cell signaling and other cell functions also showed significant modulation in senescent vs non-senescent cells. The aging/degenerating disc undergoes a well-recognized loss of cells; understanding senescent cells is important since their presence further reduces the disc's ability to generate new cells to replace those lost to necrosis or apoptosis.
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Affiliation(s)
- Helen E Gruber
- Department of Orthopaedic Surgery, Carolinas Medical Center, Charlotte, NC, USA.
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154
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Werth D, Grassi G, Konjer N, Dapas B, Farra R, Giansante C, Kandolf R, Guarnieri G, Nordheim A, Heidenreich O. Proliferation of human primary vascular smooth muscle cells depends on serum response factor. Eur J Cell Biol 2010; 89:216-24. [PMID: 20096952 DOI: 10.1016/j.ejcb.2009.12.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Smooth muscle cells (SMCs) can switch between a differentiated/contractile and an alternative proliferative phenotype. The transcription factor serum response factor (SRF) has been implicated in the regulation of gene expression profiles determining both phenotypes. Whereas strong evidence exists for a role of SRF in SMC differentiation, the contribution of SRF to SMC proliferation is less well defined. For primary human vascular SMCs in particular, existing data are non-conclusive. To study SRF functions in primary human vascular SMCs, we used an siRNA approach. siRNA-mediated SRF suppression affected the expression of established SRF target genes such as smooth muscle alpha-actin (ACTA2) or SM22alpha (TAGLN) and decreased both F-actin formation and cell migration. Furthermore, SRF knockdown caused a cell-cycle arrest in G1 associated with reduced hyperphosphorylated pRB, cyclin A and SKP2 levels, and increased p27(kip1) (CDKN1B) protein levels. SRF-depleted cells expressed senescence-associated beta-galactosidase indicating an irreversible G1 arrest. siRNA-mediated suppression of SKP2 triggered senescence to a similar extent as SRF depletion, indicating that SRF knockdown-induced senescence may be dependent on a decrease in SKP2. Thus, SRF is an essential regulator of primary human vascular SMC proliferation and senescence. Interfering with SRF function may therefore be a promising strategy for the treatment of hyperproliferative SMC disorders such as atherosclerosis and in-stent restenosis.
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Affiliation(s)
- Daniela Werth
- Department of Molecular Biology, Interfaculty Institute for Cell Biology, Eberhard Karls University of Tübingen, Germany
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155
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Roles for SUMO modification during senescence. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 694:160-71. [PMID: 20886763 DOI: 10.1007/978-1-4419-7002-2_12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
SUMOylation is a reversible post-translational modification, where a small peptide (SUMO) is covalently attached to a target protein and changes its activity, subcellular localization and/or interaction with other macromolecules. SUMOylation substrates are numerous and diverse and modification by SUMO is involved in many biological functions, including the response to stress. The SUMO pathway has recently been implicated in the process of cellular senescence, the irreversible loss of cell replication potential that occurs during aging in vivo and in vitro. SUMO peptides, a SUMO E3 ligase and a SUMO-specific peptidase can induce or hinder the onset of senescence, thus supporting an association of SUMOylation with cell growth arrest and organismal aging. Preliminary results on comparative analysis ofproteomics and mRNA levels between young and old human and murine tissues show elevated levels of global protein SUMOylation and a decrease in components of the SUMOylation process with age. Further connections between the SUMO pathway and the aging process remain to be elucidated.
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156
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Abstract
Cellular senescence is a mechanism that induces an irreversible growth arrest in all somatic cells. Senescent cells are metabolically active but lack the capacity to replicate. Evolutionary theories suggest that cellular senescence is related to the organismal decline occurring in aging organisms. Also, such theories describe senescence as an antagonistically pleiotropic process that can have beneficial or detrimental effect on the organism. Cellular senescence is believed to be involved in the cellular changes observed as aging progresses. Accumulation of senescent cells appears to occur widely as the organism ages. Furthermore, senescence is a key element of the tumor suppressor pathways. Therefore, it is part of the natural barrier against the uncontrolled proliferation observed in cellular development of malignancies in multicellular organisms. Activation of the senescence process guarantees a limited number of cellular replications. The genetic network led by p53 is responsible for activation of senescence in response to DNA damage and genomic instability that could lead to cancer. A better comprehension of the genetic networks that control the cell cycle and induce senescence is important to analyze the association of senescence to longevity and diseases related to aging. For these reasons, experimental research both in vitro and in vivo aims to develop anticancer therapies based on senescence activation. The last decade of research on role and function of senescence in aging and cancer are discussed in this paper.
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Affiliation(s)
- Angela Grimes
- Department of Biological, Chemical and Physical Sciences, Roosevelt University, Chicago, IL 60605, USA
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157
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Lukandu O, Neppelberg E, Vintermyr O, Johannessen A, Costea D. Khat Alters the Phenotype of in vitro-reconstructed Human Oral Mucosa. J Dent Res 2009; 89:270-5. [DOI: 10.1177/0022034509354980] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Khat-chewing has been associated with oral lesions including oral cancer, but the mechanisms leading to their development are not known. We hypothesized that khat interferes with the physiological processes of the oral mucosa, such as cell proliferation and differentiation, and aimed at investigating the effects of khat exposure on in vitro-reconstructed human normal buccal mucosa. Khat decreased cell proliferation, epithelial thickness, and cytokeratin 13 expression, while inducing premature expression of p21Waf1/Cip1, transglutaminases, involucrin, and filaggrin. This suggests that khat is able to induce abnormal differentiation of the buccal epithelium. Khat-induced alterations were accompanied by increased levels of p38 and were reversed by p38 inhibition, pointing to p38 as the key player in this process. The morphological changes described herein mirror the in vivo changes previously described in khat users, and demonstrate for the first time that khat induces pathological alterations in human buccal mucosa, providing evidence that raises concerns about the effects of khat use on oral health.
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Affiliation(s)
- O.M. Lukandu
- Section for Pathology, The Gade Institute, University of Bergen, Norway
- Centre for International Health, University of Bergen, Norway
- Institute of Clinical Odontology, University of Bergen, Norway; and
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - E. Neppelberg
- Section for Pathology, The Gade Institute, University of Bergen, Norway
- Centre for International Health, University of Bergen, Norway
- Institute of Clinical Odontology, University of Bergen, Norway; and
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - O.K. Vintermyr
- Section for Pathology, The Gade Institute, University of Bergen, Norway
- Centre for International Health, University of Bergen, Norway
- Institute of Clinical Odontology, University of Bergen, Norway; and
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - A.C. Johannessen
- Section for Pathology, The Gade Institute, University of Bergen, Norway
- Centre for International Health, University of Bergen, Norway
- Institute of Clinical Odontology, University of Bergen, Norway; and
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - D.E. Costea
- Section for Pathology, The Gade Institute, University of Bergen, Norway
- Centre for International Health, University of Bergen, Norway
- Institute of Clinical Odontology, University of Bergen, Norway; and
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
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158
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António N, Fernandes R, Rodriguez-Losada N, Jiménez-Navarro MF, Paiva A, de Teresa Galván E, Gonçalves L, Ribeiro CF, Providência LA. Stimulation of endothelial progenitor cells: a new putative effect of several cardiovascular drugs. Eur J Clin Pharmacol 2009; 66:219-30. [PMID: 20012029 DOI: 10.1007/s00228-009-0764-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Accepted: 11/12/2009] [Indexed: 01/04/2023]
Abstract
The role of vascular endothelium in cardiovascular disorders is well recognized. Mature endothelial cells contribute to the repair of endothelial injury, but they only have a limited capacity to do so. This has led to growing interest and further investigation into circulating endothelial progenitor cells (EPCs) and their role in vascular healing, repair, and postnatal neovascularization. The current perception of vascular health is that of a balance between ongoing injury and resultant vascular repair, mediated at least in part by circulating EPCs. Circulating EPCs play an important role in accelerating endothelialization at areas of vascular damage, and EPC enumeration is a viable strategy for assessing reparative capacity. Recent studies have shown that EPCs are affected both in number and function by several cardiovascular risk factors as well as various cardiovascular disease states, such as hypertension, hypercholesterolemia, and coronary artery disease. The present review summarizes the most relevant studies on the effects of cardiovascular drugs on vascular function and EPCs, focusing on their mechanisms of action.
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Affiliation(s)
- Natália António
- Cardiology Department, Coimbra University Hospital and Medical School, Coimbra, Portugal.
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159
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Spallarossa P, Altieri P, Pronzato P, Aloi C, Ghigliotti G, Barsotti A, Brunelli C. Sublethal doses of an anti-erbB2 antibody leads to death by apoptosis in cardiomyocytes sensitized by low prosenescent doses of epirubicin: the protective role of dexrazoxane. J Pharmacol Exp Ther 2009; 332:87-96. [PMID: 19841470 DOI: 10.1124/jpet.109.159525] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cardiotoxic synergism resulting from the sequential treatment with anthracyclines and trastuzumab has been attributed to the trastuzumab-induced loss of the erbB2-related functions that serve as a salvage pathway against the damaging effects of anthracyclines. Cellular senescence is a novel mechanism of cardiotoxicity induced by subapoptotic doses of anthracyclines. After having identified prosenescent and proapoptotic doses of epirubicin and rat MAb c-erbB2/Her-2/neu Ab-9 clone B10 (B10), an anti-erbB2 monoclonal antibody, we investigated the effects of the sequential treatment with prosenescent doses of both drugs on H9c2 cells and neonatal rat cardiomyocytes pretreated with or without the cardioprotective agent dexrazoxane. Cells were analyzed by senescence-associated beta-galactosidase, single-stranded DNA, annexin/propidium double staining, F-actin, and mitochondrial transmembrane potential. ErbB2 expression levels, AKT activation, and the effects of the inhibition of nicotinamide adenine dinucleotide phosphate oxidase [NAD(P)H oxidase] and phosphoinositide-3-OH kinase (PI3K) were also assessed. Data demonstrate that 1) the toxic effects of epirubicin mainly occur through NAD(P)H oxidase activation; 2) the erbB2 overexpression induced by epirubicin is a redox-sensitive mechanism largely dependent on NAD(P)H oxidase; 3) the loss of erbB2-related functions caused by B10 determines marginal cellular changes in untreated cells, but causes massive death by apoptosis in cells previously exposed to a prosenescent dose of epirubicin, 4) dexrazoxane promotes survival pathways, as demonstrated by the activation of Akt and the PI3K-dependent erbB2 overexpression; and 5) it also prevents epirubicin-induced senescence and renders epirubicin-treated cells more resistant to treatment with B10. Data underline the importance of NAD(P)H oxidase in epirubicin-induced cardiotoxicity and shed new light on the protective mechanisms of dexrazoxane.
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Affiliation(s)
- Paolo Spallarossa
- Research Center of Cardiovascular Biology, Division of Cardiology, Department of Internal Medicine, University of Genova, Genova, Italy
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160
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Wang D, Jang DJ. Protein kinase CK2 regulates cytoskeletal reorganization during ionizing radiation-induced senescence of human mesenchymal stem cells. Cancer Res 2009; 69:8200-7. [PMID: 19826041 DOI: 10.1158/0008-5472.can-09-1976] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Human mesenchymal stem cells (hMSC) are critical for tissue regeneration. How hMSC respond to genotoxic stresses and potentially contribute to aging and cancer remain underexplored. We showed that ionizing radiation induced cellular senescence of hMSC over a period of 10 days, showing a critical transition between days 3 and 6. This was confirmed by senescence-associated beta-galactosidase staining, protein expression profiles of key cell cycle regulators (retinoblastoma protein, p53, p21(waf1/Cip1), and p16(INK4A)), and senescence-associated secretory phenotypes (interleukin-8, interleukin-12, GRO, and MDC). We observed dramatic cytoskeletal reorganization of hMSC through reduction of myosin-10, redistribution of myosin-9, and secretion of profilin-1. Using a SILAC-based phosphoproteomics method, we detected significant reduction of myosin-9 phosphorylation at Ser(1943), coinciding with its redistribution. Importantly, through treatment with cell-permeable inhibitors (4,5,6,7-tetrabromo-1H-benzotriazole and 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole) and gene knockdown using RNA interference, we identified CK2, a kinase responsible for myosin-9 phosphorylation at Ser(1943), as a key factor contributing to the radiation-induced senescence of hMSC. We showed that individual knockdown of CK2 catalytic subunits CK2alpha and CK2alpha' induced hMSC senescence. However, only knockdown of CK2alpha resulted in morphologic phenotypes resembling those of radiation-induced senescence. These results suggest that CK2alpha and CK2alpha' play differential roles in hMSC senescence progression, and their relative expression might represent a novel regulatory mechanism for CK2 activity.
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Affiliation(s)
- Daojing Wang
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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161
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Abstract
Senescence is a general cellular process that occurs as a response to stress and damage. It forms an alternative response of cells to damage that might otherwise cause programmed cell death. Whereas telomere shortening leading to telomere dysfunction was the first described cause of senescence, it is now known that senescence can result from many sources of damage. Senescent cells are found in tissues in vivo, but the cause of senescence in these cells is mostly unknown. In many cases, senescence may be the result of the action of activated oncogenes in cells. By preventing activated oncogenes from initiating a clone of neoplastic cells, senescence acts as a protective mechanism against cancer development. Until recently, the fate of senescent cells in vivo was unknown, but new evidence indicates that they are cleared by components of the innate immune system. In this way, senescence and apoptosis act as parallel pathways by which severely damaged cells are eliminated from the body. Some senescent cells persist in tissues, in some cases increasing in frequency as a function of age. It is hypothesized that these persistent senescent cells have adverse effects on tissue function. If so, senescence may be an example of antagonistic pleiotropy, providing an anticancer mechanism in early life but having adverse effects on tissue function in late life. Much more research is needed to address the broader question of the overall impact of senescence on life span.
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162
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Walter M. Interrelationships Among HDL Metabolism, Aging, and Atherosclerosis. Arterioscler Thromb Vasc Biol 2009; 29:1244-50. [DOI: 10.1161/atvbaha.108.181438] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Michael Walter
- From the Charité-Universitätsmedizin Berlin, Department of Laboratory Medicine and Pathobiochemistry, Germany and the Unfallkranken haus Berlin, Germany
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163
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Dekker P, Maier AB, van Heemst D, de Koning-Treurniet C, Blom J, Dirks RW, Tanke HJ, Westendorp RGJ. Stress-induced responses of human skin fibroblasts in vitro reflect human longevity. Aging Cell 2009; 8:595-603. [PMID: 19681808 DOI: 10.1111/j.1474-9726.2009.00506.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Unlike various model organisms, cellular responses to stress have not been related to human longevity. We investigated cellular responses to stress in skin fibroblasts that were isolated from young and very old subjects, and from offspring of nonagenarian siblings and their partners, representatives of the general population. Fibroblasts were exposed to rotenone and hyperglycemia and assessed for senescence-associated beta-galactosidase (SA-beta-gal) activity by flow cytometry. Apoptosis/cell death was measured with the Annexin-V/PI assay and cell-cycle analysis (Sub-G1 content) and growth potential was determined by the colony formation assay. Compared with fibroblasts from young subjects, baseline SA-beta-gal activity was higher in fibroblasts from old subjects (P = 0.004) as were stress-induced increases (rotenone: P < 0.001, hyperglycemia: P = 0.027). For measures of apoptosis/cell death, fibroblasts from old subjects showed higher baseline levels (Annexin V+/PI+ cells: P = 0.040, Sub-G1: P = 0.014) and lower stress-induced increases (Sub-G1: P = 0.018) than fibroblasts from young subjects. Numbers and total size of colonies under nonstressed conditions were higher for fibroblasts from young subjects (P = 0.017 and 0.006, respectively). Baseline levels of SA-beta-gal activity and apoptosis/cell death were not different between fibroblasts from offspring and partner. Stress-induced increases were lower for SA-beta-gal activity (rotenone: P = 0.064, hyperglycemia: P < 0.001) and higher for apoptosis/cell death (Annexin V+/PI- cells: P = 0.041, Annexin V+/PI+ cells: P = 0.008). Numbers and total size of colonies under nonstressed conditions were higher for fibroblasts from offspring (P = 0.001 and 0.024, respectively) whereas rotenone-induced decreases were lower (P = 0.008 and 0.004, respectively). These data provide strong support for the hypothesis that in vitro cellular responses to stress reflect the propensity for human longevity.
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Affiliation(s)
- Pim Dekker
- Department of Gerontology and Geriatrics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
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164
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Chen Y, Johansson E, Fan Y, Shertzer HG, Vasiliou V, Nebert DW, Dalton TP. Early onset senescence occurs when fibroblasts lack the glutamate-cysteine ligase modifier subunit. Free Radic Biol Med 2009; 47:410-8. [PMID: 19427898 PMCID: PMC2773044 DOI: 10.1016/j.freeradbiomed.2009.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 05/05/2009] [Accepted: 05/05/2009] [Indexed: 12/23/2022]
Abstract
Cellular senescence is the irreversible entry of cells into growth arrest. Senescence of primary cells in culture has long been used as an in vitro model for aging. Glutamate-cysteine ligase (GCL) controls the synthetic rate of the important cellular antioxidant glutathione (GSH). The catalytic subunit of GCL, GCLC, is catalytically active and essential for life. By contrast the modifier subunit of GCL, GCLM, is dispensable in mice. Although it is recognized that GCLM increases the rate of GSH synthesis, its physiological role is unclear. Herein, we show that loss of Gclm leads to premature senescence of primary murine fibroblasts as characterized by: (a) diminished growth rate, (b) cell morphology consistent with senescence, (c) increases in senescence-associated beta-galactosidase activity, and (d) cell cycle arrest at the G(1)/S and G(2)/M boundaries. These changes are accompanied by increased intracellular ROS, accumulation of DNA damage, and induction of p53 and p21 proteins. We also found that N-acetylcysteine increases intracellular GSH and prevents premature senescence in Gclm(-/-) cells. These results suggest that the control of GCLM, which in turn controls aspects of the cellular redox environment via GSH, is important in determining the replicative capacity of the cell.
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Affiliation(s)
- Ying Chen
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, OH 45267-0056, USA.
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165
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Kim KW, Chung HN, Ha KY, Lee JS, Kim YY. Senescence mechanisms of nucleus pulposus chondrocytes in human intervertebral discs. Spine J 2009; 9:658-66. [PMID: 19540815 DOI: 10.1016/j.spinee.2009.04.018] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 03/14/2009] [Accepted: 04/14/2009] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT The population of senescent disc cells has been shown to increase in degenerated or herniated discs. However, the mechanism and signaling pathway involved in the senescence of nucleus pulposus (NP) chondrocytes are unknown. PURPOSE To demonstrate the mechanisms involved in the senescence of NP chondrocytes. STUDY DESIGN/SETTING Senescence-related markers were assessed in the surgically obtained human NP specimens. PATIENT SAMPLE NP specimens remaining in the central region of the intervertebral disc were obtained from 25 patients (mean: 49 years, range: 20-75 years) undergoing discectomy. Based on the preoperative magnetic resonance images, there were 3 patients with Grade II degeneration, 17 patients with Grade III degeneration, and 5 patients with Grade IV degeneration. OUTCOME MEASURES We examined cell senescence markers (senescence-associated beta-galactosidase [SA-beta-gal], telomere length, telomerase activity, p53, p21, pRB, and p16) and the hydrogen peroxide (H(2)O(2)) content as a marker for an oxidative stress in the human NP specimens. METHODS SA-beta-gal expression, telomere length, telomerase activity, and H(2)O(2) content as well as their relationships with age and degeneration grades were analyzed. For the mechanism involved in the senescence of NP chondrocytes, expressions of p53, p21, pRB, and p16 in these cells were assessed with immunohistochemistry and Western blotting. RESULTS The percentages of SA-beta-gal-positive NP chondrocytes increased with age (r=.82, p<.001), whereas the telomere length and telomerase activity declined (r=-.41, p=.045; r=-.52, p=.008, respectively) However, there was no significant correlation between age and H(2)O(2) contents (p=.18). The NP specimens with Grade III or Grade IV degeneration showed significantly higher percentages of SA-beta-gal-positive NP chondrocytes than those with Grade II degeneration (p=.01 and p=.025, respectively). Immunohistochemistry showed that the senescent NP chondrocytes in all the specimens expressed p53, p21, and pRB, but a few NP chondrocytes in only two specimens expressed p16. Western blotting showed that the expressions of p53, p21, and pRB displayed a corresponding pattern, that is, a strong p53 expression led to strong p21 and pRB expressions and vice versa. CONCLUSIONS Our in vivo study demonstrated that senescent NP chondrocytes increased or accumulated in the NP with increasing age and advancing disc degeneration. The NP chondrocytes in the aging discs exhibited characteristic senescent features such as an increased SA-beta-gal expression, shortened telomeres, and decreased telomerase activity. We further demonstrated that the telomere-based p53-p21-pRB pathway, rather than the stress-based p16-pRB pathway, plays a more important role in the senescence of NP chondrocytes in an in vivo condition. Our results suggest that prevention or reversal of the senescence of NP chondrocytes can be a novel therapeutic target for human disc degeneration.
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Affiliation(s)
- Ki-Won Kim
- Department of Orthopedic Surgery, St. Mary's Hospital, The Catholic University of Korea, 62 Yoido-dong, Youngdeungpo-ku, Seoul, Republic of Korea.
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166
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López-Vicente L, Armengol G, Pons B, Coch L, Argelaguet E, Lleonart M, Hernández-Losa J, de Torres I, Ramon y Cajal S. Regulation of replicative and stress-induced senescence by RSK4, which is down-regulated in human tumors. Clin Cancer Res 2009; 15:4546-53. [PMID: 19584160 DOI: 10.1158/1078-0432.ccr-08-3159] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The control of senescence and its biochemical pathways is a crucial factor for understanding cell transformation. In a large RNA interference screen, the RSK4 gene was found to be related to p53-dependent arrest. The purpose of the present study was to investigate the potential role of RSK4 as a tumor suppressor gene. EXPERIMENTAL DESIGN RSK4 expression was determined by quantitative real-time PCR and immunoblot in 30 colon and 20 renal carcinomas, and in 7 colon adenomas. Two HCT116 colon carcinoma cell lines (p53 wt and p53 null), IMR90 human fibroblasts, and E1A-expressing IMR90 cells were infected with RSK4 cDNA and/or shRNA. RSK4 expression levels were analyzed in HCT116 p53 wt or p53 null and IMR90 after senescence induction by quantitative real-time PCR and Western blot. RESULTS The RSK4 gene was down-regulated in 27 of 30 colon carcinomas (P < 0.001), 16 of 20 renal cell carcinomas (P < 0.01), and 6 of 7 colon adenomas (P < 0.01). In vitro overexpression of RSK4 induced cell arrest and senescence features in normal fibroblasts and malignant colon carcinoma cell lines. Interestingly, in these cell lines RSK4 mRNA levels were increased both in replicative and stress-induced senescence. Moreover, IMR90 partially immortalized by RSK4 shRNA and HCT116 with this short hairpin RNA were more resistant to cisplatin treatment. Finally, cells expressing E1A or Rb short interfering RNA were resistant to RSK4-mediated senescence. CONCLUSION These results support the concept that RSK4 may be an important tumor suppressor gene by modulating senescence induction and contributing to cell proliferation control in colon carcinogenesis and renal cell carcinomas.
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Affiliation(s)
- Laura López-Vicente
- Department of Pathology, Vall d'Hebron University Hospital, and Department of Biochemistry and Molecular Biology, and Unit of Biological Anthropology, Universitat Autònoma de Barcelona, Barcelona 08035, Spain
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Sharp CA, Roberts S, Evans H, Brown SJ. Disc cell clusters in pathological human intervertebral discs are associated with increased stress protein immunostaining. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2009; 18:1587-94. [PMID: 19517141 DOI: 10.1007/s00586-009-1053-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 05/07/2009] [Accepted: 05/21/2009] [Indexed: 02/07/2023]
Abstract
Intervertebral disc (IVD) cells within the annulus fibrosus (AF) and nucleus pulposus (NP) maintain distinct functional extracellular matrices and operate within a potentially noxious and stressful environment. How disc cells respond to stress and whether stress is responsible for triggering degeneration is unknown. Disc cell proliferation and cluster formation are most marked in degenerate IVDs, possibly indicating attempts at matrix repair. In other tissues, stress proteins increase rapidly after stress protecting cell function and, although implicated in degeneration of articular cartilage, have received little attention in degenerative IVD pathologies. We have compared the distribution of stress protein immunolocalization in pathological and control IVDs. Disc tissues were obtained at surgery from 43 patients with degenerative disc disease (DDD) and herniation, and 12 controls at postmortem. Tissues were immunostained with a polyclonal antibody for heat shock factor 1 (HSF-1) and monoclonal antibodies for the heat shock proteins, Hsp27 and Hsp72, using an indirect immunoperoxidase method. Positively stained cells were expressed as a percentage of the total. Cell cluster formation was also assessed. The proportion of cells in clusters was similar in the AF (both 2%) and NP (8 and 9%) of control and DDD samples, whereas in herniated tissues this was increased (AF 12%, NP 14%). Stress antigen staining tended to be more frequent in clustered rather than in single/doublet cells, and this was significant (P < 0.005) in both the AF and NP of herniated discs. Clustered cells, which are most common in herniated discs, may be mounting a protective response to abnormal environmental factors associated with disc degeneration. A better understanding of the stress response in IVD cells may allow its utilization in disc cell therapies.
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Affiliation(s)
- Christopher A Sharp
- Charles Salt Centre for Human Metabolism, Robert Jones and Agnes Hunt Orthopaedic and District Hospital NHS Trust, Oswestry, Shropshire SY10 7AG, UK.
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Hao H, Nancai Y, Lei F, Wen S, Guofu H, yanxia W, Hanju H, Qian L. Retracted:Antiaging effect of purslane herb aqueous extracts and its mechanism of Action. Phytother Res 2009; 23:i-vii. [DOI: 10.1002/ptr.2835] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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169
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Farhat N, Thorin-Trescases N, Voghel G, Villeneuve L, Mamarbachi M, Perrault LP, Carrier M, Thorin E. Stress-induced senescence predominates in endothelial cells isolated from atherosclerotic chronic smokers. Can J Physiol Pharmacol 2009; 86:761-9. [PMID: 19011671 DOI: 10.1139/y08-082] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Age-associated telomere shortening leads to replicative senescence of human endothelial cells (EC). Risk factors for cardiovascular disease (CVD) accelerate ageing, while there is a concomitant rise in oxidative stress known to promote stress-induced senescence (SIS) in vitro. Of all risk factors for CVD, smoking is most associated with the development of inflammation and accelerated atherosclerosis due to a prooxidant-antioxidant imbalance. We tested the hypothesis that SIS predominates in EC isolated from chronic smokers with premature atherosclerosis undergoing coronary artery bypass graft surgery (CABG). We isolated and cultured EC from segments of internal mammary arteries from smoker, former smoker, and nonsmoker coronary patients. Senescence of EC was induced by serial passage and quantified by the measurement of telomere length and senescence-associated beta-galactosidase activity. Compared with nonsmokers, smoker patients were 10 years younger at the time of CABG, evidence of premature atherosclerosis. Cellular senescence was independent of telomere length and directly related to oxidative damage. EC exhibited higher expression levels of markers of oxidative stress (lipid peroxydation level and caveolin-1 mRNA), inflammation (angiopoietin-like 2 mRNA), hypoxia (vascular endothelial growth factor (VEGF)-A mRNA), and cell damage (p53 mRNA). In conclusion, a high oxidative stress environment in EC isolated from atherosclerotic chronic smokers predisposes to SIS rather than replicative senescence.
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Affiliation(s)
- Nada Farhat
- Department of Surgery and Research Center, Institut de Cardiologie de Montreal, Universite de Montreal, 5000, rue Belanger, Montreal, QC H1T1C8, Canada
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Gruber HE, Ingram JA, Davis DE, Hanley EN. Increased cell senescence is associated with decreased cell proliferation in vivo in the degenerating human annulus. Spine J 2009; 9:210-5. [PMID: 18440281 DOI: 10.1016/j.spinee.2008.01.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 01/18/2008] [Accepted: 01/30/2008] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT During disc degeneration, there is a well-recognized loss of cells. This puts the remaining cell population at high risk for any further decrease in cell function or cell numbers. Cell senescence has recently been shown to be present in the aging/degenerating human disc. Senescent cell are viable, metabolically active, persist, and accumulate over time, but cannot divide. Little is known about the relationship between renewal of the disc cell population via cell proliferation and disc cell senescence. PURPOSE To determine the percentage of senescent cells and proliferating cells in the human annulus in vivo. STUDY DESIGN/SETTING Human annulus specimens were obtained from surgical subjects and control donors in a study approved by the authors' Human Subjects Institutional Review Board. PATIENT SAMPLE One Thompson Grade I disc, 4 Grade II discs, 9 Grade III discs, and 12 Grade IV discs were studied. OUTCOME MEASURES The percentages of senescent cells and the percentage of proliferating cells. METHODS Immunohistochemistry was used to detect senescent cells using an antisenescence-associated beta-galactosidase antibody, and an antiproliferation antibody (Ki67). An average of 410 cells/specimens was counted to determine the percent senescence, and an average of 229 cells was counted to determine the percent proliferation. RESULTS Cell proliferation was low in both surgical and control normal donor annulus tissue (4.09%+1.77 (26), mean+SD (n)). There was no significant difference in the percentage of proliferating cells for more degenerate discs versus healthier discs (4.7%+1.6 (21) for Grades III and IV vs. 5.3%+1.9 (5) for Grades I and II). More degenerated Grades III and IV discs contained significantly greater percentages of senescent annulus cells than did the healthier Grades I and II discs (44.4%+20.0 (21) vs. 18.8%+11.0 (5), respectively; p=.011). A significant negative correlation was present between the percentage of senescent cells versus the percentage of proliferating cells, r=-0.013, p=.013. No correlation was present between age and the percentage of senescent cells or age and the percentage of proliferating cells. CONCLUSIONS Because senescent cells cannot divide, senescence may reduce the disc's ability to generate new cells to replace cells lost to necrosis or apoptosis. Senescent cells also accumulate in the disc over time, such that their metabolic patterns may contribute to the pathologic changes seen in degenerating discs. Novel data presented here show a significant negative correlation between the percentage of senescent cells and the percentage of proliferating cells during disc degeneration. Molecular work is underway in our lab to help us determine whether senescent cells in the disc secrete factors that can result in decreased proliferation in neighboring cells.
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Affiliation(s)
- Helen E Gruber
- Department of Orthopaedic Surgery, Carolinas Medical Center, PO Box 32861, Cannon Research., Room 304, Charlotte, NC 28232, USA.
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171
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Abstract
SIRT1 is a multifaceted, NAD(+)-dependent protein deacetylase that is involved in a wide variety of cellular processes from cancer to ageing. The function of SIRT1 in cancer is complex: SIRT1 has been shown to have oncogenic properties by downregulating p53 activity, but recent studies indicate that SIRT1 acts as a tumour suppressor in a mutated p53 background, raising intriguing questions regarding its mechanism of action. Here we discuss the current understanding of how SIRT1 functions in light of recent discoveries and propose that the net outcome of the seemingly opposite oncogenic and tumour-suppressive effects of SIRT1 depends on the status of p53.
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Affiliation(s)
- Christopher L Brooks
- Institute for Cancer Genetics and Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, 1130 St Nicholas Avenue, New York, New York 10032, USA
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172
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Kim KI, Baek SH. Small ubiquitin-like modifiers in cellular malignancy and metastasis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 273:265-311. [PMID: 19215907 DOI: 10.1016/s1937-6448(08)01807-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Small ubiquitin-like modifiers (SUMOs) mediate a variety of cellular functions of protein targets mainly in the nucleus but in other cellular compartments as well, and thereby participate in maintaining cellular homeostasis. SUMO system plays important roles in transcriptional regulation, DNA damage responses, maintaining genome integrity, and signaling pathways. Thus, in some cases, loss of regulated control on SUMOylation/deSUMOylation processes causes a defect in maintaining homeostasis and hence gives a cue to cancer development and progression. Furthermore, recent studies have revealed that SUMO system is involved in cancer metastasis. In this review, we will summarize the possible role of SUMO system in cancer development, progression, and metastasis and discuss future directions.
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Affiliation(s)
- Keun Il Kim
- Department of Biological Sciences, Research Center for Women's Disease, Sookmyung Women's University, Seoul, Korea
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Muller M. Cellular senescence: molecular mechanisms, in vivo significance, and redox considerations. Antioxid Redox Signal 2009; 11:59-98. [PMID: 18976161 DOI: 10.1089/ars.2008.2104] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cellular senescence is recognized as a critical cellular response to prolonged rounds of replication and environmental stresses. Its defining characteristics are arrested cell-cycle progression and the development of aberrant gene expression with proinflammatory behavior. Whereas the mechanistic events associated with senescence are generally well understood at the molecular level, the impact of senescence in vivo remains to be fully determined. In addition to the role of senescence as an antitumor mechanism, this review examines cellular senescence as a factor in organismal aging and age-related diseases, with particular emphasis on aberrant gene expression and abnormal paracrine signaling. Senescence as an emerging factor in tissue remodeling, wound repair, and infection is considered. In addition, the role of oxidative stress as a major mediator of senescence and the role of NAD(P)H oxidases and changes to intracellular GSH/GSSG status are reviewed. Recent findings indicate that senescence and the behavior of senescent cells are amenable to therapeutic intervention. As the in vivo significance of senescence becomes clearer, the challenge will be to modulate the adverse effects of senescence without increasing the risks of other diseases, such as cancer. The uncoupled relation between cell-cycle arrest and the senescent phenotype suggests that this is an achievable outcome.
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Affiliation(s)
- Michael Muller
- Centre for Education and Research on Ageing, ANZAC Research Institute, University of Sydney, Concord RG Hospital, Concord, Sydney, Australia.
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Mecanismos implicados en la disfunción endotelial asociada al envejecimiento. Med Clin (Barc) 2009; 132:62-9. [DOI: 10.1016/j.medcli.2008.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Accepted: 09/17/2008] [Indexed: 11/21/2022]
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175
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Shan W, Yang G, Liu J. The inflammatory network: bridging senescent stroma and epithelial tumorigenesis. FRONT BIOSCI-LANDMRK 2009; 14:4044-57. [PMID: 19273333 PMCID: PMC2858971 DOI: 10.2741/3511] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Cellular senescence or aging, defined by permanent cell cycle arrest, is well known for its evolutionary advantage in protecting the organism from developing cancer; however, it is also acknowledged that aged stromal cells can significantly expedite epithelial tumorigenesis, although exactly how they function to augment tumor formation remains elusive. Recent evidence suggests that this tumor-promoting effect is likely mediated by diffusible pro-inflammatory molecules synthesized and released by senescent stromal fibroblasts, acting in a paracrine fashion on adjacent tumor epithelium. Mobilization of the inflammatory network by senescent fibroblasts has bifurcated roles on the epithelial and stromal compartments, converging on the promotion of epithelial tumorigenesis. A thorough understanding of the regulatory mechanisms underlying these events may lead to improved approaches in cancer treatment.
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Affiliation(s)
- Weiwei Shan
- Department of Pathology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030
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176
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Phospholipase C delta 1 regulates cell proliferation and cell-cycle progression from G1- to S-phase by control of cyclin E-CDK2 activity. Biochem J 2008; 415:439-48. [PMID: 18588506 DOI: 10.1042/bj20080233] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present study, we examined the role of PLC delta 1 (phospholipase C delta 1) in the regulation of cellular proliferation. We demonstrate that RNAi (RNA interference)-mediated knockdown of endogenous PLC delta 1, but not PLC beta 3 or PLC epsilon, induces a proliferation defect in Rat-1 and NIH 3T3 fibroblasts. The decreased proliferation was not due to an induction of apoptosis or senescence, but was associated with an approx. 60% inhibition of [(3)H]thymidine incorporation. Analysis of the cell cycle with BrdU (bromodeoxyuridine)/propidium iodide-labelled FACS (fluorescence-activated cell sorting) demonstrated an accumulation of cells in G(0)/G(1)-phase and a corresponding decrease in cells in S-phase. Further examination of the cell cycle after synchronization by serum-starvation demonstrated normal movement through G(1)-phase but delayed entry into S-phase. Consistent with these findings, G(1) cyclin (D2 and D3) and CDK4 (cyclin-dependent kinase 4) levels and associated kinase activity were not affected. However, cyclin E-associated CDK2 activity, responsible for G(1)-to-S-phase progression, was inhibited. This decreased activity was accompanied by unchanged CDK2 protein levels and paradoxically elevated cyclin E and cyclin E-associated CDK2 levels, suggesting inhibition of the cyclin E-CDK2 complex. This inhibition was not due to altered stimulatory or inhibitory phosphorylation of CDK2. However, p27, a Cip/Kip family CKI (CDK inhibitor)-binding partner, was elevated and showed increased association with CDK2 in PLC delta 1-knockdown cells. The result of the present study demonstrate a novel and critical role for PLC delta 1 in cell-cycle progression from G(1)-to-S-phase through regulation of cyclin E-CDK2 activity and p27 levels.
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177
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Nakamura AJ, Chiang YJ, Hathcock KS, Horikawa I, Sedelnikova OA, Hodes RJ, Bonner WM. Both telomeric and non-telomeric DNA damage are determinants of mammalian cellular senescence. Epigenetics Chromatin 2008; 1:6. [PMID: 19014415 PMCID: PMC2584625 DOI: 10.1186/1756-8935-1-6] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 11/03/2008] [Indexed: 01/03/2023] Open
Abstract
Background Cellular senescence is a state reached by normal mammalian cells after a finite number of cell divisions and is characterized by morphological and physiological changes including terminal cell-cycle arrest. The limits on cell division imposed by senescence may play an important role in both organismal aging and in preventing tumorigenesis. Cellular senescence and organismal aging are both accompanied by increased DNA damage, seen as the formation of γ-H2AX foci (γ-foci), which may be found on uncapped telomeres or at non-telomeric sites of DNA damage. However, the relative importance of telomere- and non-telomere-associated DNA damage to inducing senescence has never been demonstrated. Here we present a new approach to determine accurately the chromosomal location of γ-foci and quantify the number of telomeric versus non-telomeric γ-foci associated with senescence in both human and mouse cells. This approach enables researchers to obtain accurate values and to avoid various possible misestimates inherent in earlier methods. Results Using combined immunofluorescence and telomere fluorescence in situ hybridization on metaphase chromosomes, we show that human cellular senescence is not solely determined by telomeric DNA damage. In addition, mouse cellular senescence is not solely determined by non-telomeric DNA damage. By comparing cells from different generations of telomerase-null mice with human cells, we show that cells from late generation telomerase-null mice, which have substantially short telomeres, contain mostly telomeric γ-foci. Most notably, we report that, as human and mouse cells approach senescence, all cells exhibit similar numbers of total γ-foci per cell, irrespective of chromosomal locations. Conclusion Our results suggest that the chromosome location of senescence-related γ-foci is determined by the telomere length rather than species differences per se. In addition, our data indicate that both telomeric and non-telomeric DNA damage responses play equivalent roles in signaling the initiation of cellular senescence and organismal aging. These data have important implications in the study of mechanisms to induce or delay cellular senescence in different species.
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Affiliation(s)
- Asako J Nakamura
- Laboratory of Molecular Pharmacology, National Cancer Institute, National Institutes of Health, Rockville Pike, Bethesda, MD 20892, USA.
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Verzola D, Gandolfo MT, Gaetani G, Ferraris A, Mangerini R, Ferrario F, Villaggio B, Gianiorio F, Tosetti F, Weiss U, Traverso P, Mji M, Deferrari G, Garibotto G. Accelerated senescence in the kidneys of patients with type 2 diabetic nephropathy. Am J Physiol Renal Physiol 2008; 295:F1563-73. [DOI: 10.1152/ajprenal.90302.2008] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the hypothesis that senescence represents a proximate mechanism by which the kidney is damaged in type 2 diabetic nephropathy (DN). As a first step, we studied whether the senescence-associated β-galactosidase (SA-β-Gal) and the cell cycle inhibitor p16INK4A are induced in renal biopsies from patients with type 2 DN. SA-β-Gal staining was approximately threefold higher ( P < 0.05) than in controls in the tubular compartment of diabetic kidneys and correlated directly with body mass index and blood glucose. P16INK4A expression was significantly increased in tubules ( P < 0.005) and in podocytes ( P = 0.04). Nuclear p16INK4A in glomeruli was associated with proteinuria ( P < 0.002), while tubular p16INK4A was directly associated with body mass index, LDL cholesterol, and HbA1c ( P < 0.001–0.05). In a parallel set of experiments, proximal tubule cells passaged under high glucose presented a limited life span and an approximately twofold increase in SA-β-Gal and p16INK4A protein. Mean telomere lengths decreased ∼20% as an effect of replicative senescence. In addition, mean telomere decreased further by ∼30% in cells cultivated under high glucose. Our results show that the kidney with type 2 diabetic nephropathy displays an accelerated senescent phenotype in defined renal cell types, mainly tubule cells and, to a lesser extent, podocytes. A similar senescent pattern was observed when proximal tubule cell cultures where incubated under high-glucose media. These changes are associated with shortening tubular telomere length in vitro. These findings indicate that diabetes may boost common pathways involving kidney cell senescence, thus reinforcing the role of the metabolic syndrome on biological aging of tissues.
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179
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Grindon C, Combes R, Cronin MT, Roberts DW, Garrod JF. An Integrated Decision-tree Testing Strategy for Repeat Dose Toxicity with Respect to the Requirements of the EU REACH Legislation. Altern Lab Anim 2008; 36 Suppl 1:139-47. [DOI: 10.1177/026119290803601s11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This paper presents some results of a joint research project conducted by FRAME and Liverpool John Moores University, and sponsored by Defra, on the status of alternatives to animal testing with regard to the European Union REACH (Registration, Evaluation and Authorisation of Chemicals) system for the safety testing and risk assessment of chemicals. The project covered all the main toxicity end-points associated with REACH. This paper focuses on the use of alternative (non-animal) methods (both in vitro and in silico) for repeat dose (sub-acute, sub-chronic and chronic) toxicity testing. It reviews the limited number of in silico and in vitro tests available for this endpoint, and outlines new technologies which could be used in the future, e.g. the use of biomarkers and the ‘omics’ technologies. An integrated testing strategy is proposed, which makes use of as much non-animal data as possible, before any essential in vivo studies are performed. Although none of the non-animal tests are currently undergoing validation, their results could help to reduce the number of animals required for testing for repeat dose toxicity.
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Affiliation(s)
| | | | - Mark T.D. Cronin
- School of Pharmacy and Chemistry, Liverpool John Moores University, Liverpool, UK
| | - David W. Roberts
- School of Pharmacy and Chemistry, Liverpool John Moores University, Liverpool, UK
| | - John F. Garrod
- Chemicals and Nanotechnologies Division, Defra, London, UK
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Hayashi T, Yano K, Matsui-Hirai H, Yokoo H, Hattori Y, Iguchi A. Nitric oxide and endothelial cellular senescence. Pharmacol Ther 2008; 120:333-9. [PMID: 18930078 DOI: 10.1016/j.pharmthera.2008.09.002] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 09/03/2008] [Indexed: 11/15/2022]
Abstract
Cellular senescence is characterized by permanent exit from the cell cycle and the appearance of distinct morphological and functional changes associated with an impairment of cellular homeostasis. Many studies support the occurrence of vascular endothelial cell senescence in vivo, and the senescent phenotype of endothelial cells can be transformed from anti-atherosclerotic to pro-atherosclerotic. Thus, endothelial cell senescence promotes endothelial dysfunction and may contribute to the pathogenesis of age-associated vascular disorders. Emerging evidence suggests that increasing nitric oxide (NO) bioavailability or endothelial NO synthase (eNOS) activity activates telomerase and delays endothelial cell senescence. In this review, we discuss the potential mechanisms underlying the ability of NO to prevent endothelial cell senescence and describe the possible changes in the NO-mediated anti-senescence effect under pathophysiological conditions, including oxidative stress and hyperglycemia. Further understanding of the mechanisms underlying the anti-senescence effect of NO in endothelial cells will provide insights into the potential of eNOS-based anti-senescence therapy for age-associated vascular disorders.
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Affiliation(s)
- Toshio Hayashi
- Department of Geriatrics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
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181
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Ohshima S. Abnormal mitosis in hypertetraploid cells causes aberrant nuclear morphology in association with H2O2-induced premature senescence. Cytometry A 2008; 73:808-15. [DOI: 10.1002/cyto.a.20604] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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182
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Gruber HE, Ingram J, Leslie K, Hanley EN. Gene expression of types I, II, and VI collagen, aggrecan, and chondroitin-6-sulfotransferase in the human annulus: in situ hybridization findings. Spine J 2008; 8:810-7. [PMID: 18024225 DOI: 10.1016/j.spinee.2007.07.387] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 07/12/2007] [Accepted: 07/13/2007] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Within each lamellar bundle in the annulus, disc cells produce a complex and sophisticated architectural organization which acts to meet the unique biomechanical needs of the disc. How cells coordinate expression of genes throughout the disc is an important but as yet poorly understood process. For the annulus, such coordination probably involves cell-cell communication as well as growth factor and mechanoreceptor signaling to appropriately maintain the disc extracellular matrix (ECM) for the prevention of annular tears. PURPOSE To determine the percentage and patterns of gene expression for types I, II, and VI collagen, aggrecan, and chondroitin-6-sulfotransferase in the human annulus. STUDY DESIGN/SETTING Human annulus specimens were obtained from surgical subjects and a control donor in a study approved by the authors' Human Subjects Institutional Review Board. PATIENT SAMPLE Four Thompson grade II, three grade III, and four grade IV annulus specimens were evaluated with in situ hybridization to determine gene expression. OUTCOME MEASURES The percentages of cells in the human annulus expressing type I, II, and VI collagen, aggrecan, and chondroitin-6-sulfotransferase. METHODS In situ hybridization, a technique with high temporal and spatial resolution, was used to detect gene expression of types I, II, and VI collagen, aggrecan, and chondroitin-6 sulfotransferase in cells in adjacent sections of annulus from discs with Thompson grades of II, III, and IV. RESULTS Overall, 30.8% of cells expressed aggrecan, 38.4% type I collagen, 45.6% type II collagen, 48.1% type VI collagen, and 57.7% chondroitin-6-sulfotransferase. An important finding was that adjacent cells could be expressing, or not expressing, the gene of interest. These data could not have been gained from other global molecular techniques such as microarray analysis or reverse transcription polymerase chain reaction (RT-PCR). Information on gene expression by individual disc cells is important to better understand disc matrix homeostasis, the pathogenesis of disc degeneration, and to formulate potential biologic therapies for disc degeneration. CONCLUSIONS This in situ hybridization study revealed the important finding that adjacent cells differ in their gene expression patterns for specific genes. Factors that could contribute to this difference in adjacent cell gene expression include cellular heterogeneity within the annulus, the presence of senescent cells with altered gene expression, and/or loss of coordinated disc cell function as a result of disruption of cell-cell communication.
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Affiliation(s)
- Helen E Gruber
- Department of Orthopaedic Surgery, Orthopaedic Research Biology, Cannon Research 304, Carolinas Medical Center, Charlotte, NC 28232, USA.
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183
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Dicarbonyl-induced accelerated aging in vitro in human skin fibroblasts. Biogerontology 2008; 10:203-11. [DOI: 10.1007/s10522-008-9172-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 08/14/2008] [Indexed: 10/21/2022]
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184
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Kortlever RM, Brummelkamp TR, van Meeteren LA, Moolenaar WH, Bernards R. Suppression of the p53-dependent replicative senescence response by lysophosphatidic acid signaling. Mol Cancer Res 2008; 6:1452-60. [PMID: 18723828 DOI: 10.1158/1541-7786.mcr-08-0066] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lysophosphatidic acid (LPA) is a lipid mediator of a large number of biological processes, including wound healing, brain development, vascular remodeling, and tumor progression. Its role in tumor progression is probably linked to its ability to induce cell proliferation, migration, and survival. In particular, the ascites of ovarian cancers is rich in LPA and has been implicated in growth and invasion of ovarian tumor cells. LPA binds to specific G protein-coupled receptors and thereby activates multiple signal transduction pathways, including those initiated by the small GTPases Ras, Rho, and Rac. We report here a genetic screen with retroviral cDNA expression libraries to identify genes that allow bypass of the p53-dependent replicative senescence response in mouse neuronal cells, conditionally immortalized by a temperature-sensitive mutant of SV40 large T antigen. Using this approach, we identified the LPA receptor type 2 (LPA(2)) and the Rho-specific guanine nucleotide exchange factor Dbs as potent inducers of senescence bypass. Enhanced expression of LPA(2) or Dbs also results in senescence bypass in primary mouse embryo fibroblasts in the presence of wild-type p53, in a Rho GTPase-dependent manner. Our results reveal a novel and unexpected link between LPA signaling and the p53 tumor-suppressive pathway.
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Affiliation(s)
- Roderik M Kortlever
- Division of Molecular Carcinogenesis, Center for Cancer Genomics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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185
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Liang S, Kahlenberg MS, Rousseau DL, Hornsby PJ. Neoplastic conversion of human colon smooth muscle cells: No requirement for telomerase. Mol Carcinog 2008; 47:478-84. [PMID: 18085530 DOI: 10.1002/mc.20405] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The role of telomerase as an essential requirement for the neoplastic conversion of human cells has been controversial. In the model of conversion of normal human cells to cancer cells by the combination of simian virus 40 (SV40) early region genes and oncogenic Ras (H-Ras(G12V)), telomerase (hTERT) was originally described as essential in conjunction with these other genes. Here we used primary cultures of colon smooth muscle cells isolated from surgical specimens. SV40 large T antigen (TAg) and oncogenic Ras(G12V) were introduced into the cells by retroviral transduction and cells were rapidly transplanted into the subrenal capsule space in immunodeficient mice, without selection in culture. Malignant tumors were formed from transduced cells. Extensive invasion into the kidney occurred even when tumors were small; in contrast, at the same tumor size, oncogene-expressing fibroblasts did not show much invasion. Increased invasiveness was also observed in vitro. However, cells in these cancers showed morphological evidence of crisis, consistent with their lack of telomerase. These experiments on human colon smooth muscle cells support the concept that Ras(G12V) and SV40 TAg form a minimal set of genes that can convert normal human cells to cancer cells without a requirement for hTERT.
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Affiliation(s)
- Sitai Liang
- Department of Physiology, Sam and Ann Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center, San Antonio, Texas 78245, USA
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186
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Koppelstaetter C, Schratzberger G, Perco P, Hofer J, Mark W, Ollinger R, Oberbauer R, Schwarz C, Mitterbauer C, Kainz A, Karkoszka H, Wiecek A, Mayer B, Mayer G. Markers of cellular senescence in zero hour biopsies predict outcome in renal transplantation. Aging Cell 2008; 7:491-7. [PMID: 18462273 DOI: 10.1111/j.1474-9726.2008.00398.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Although chronological donor age is the most potent predictor of long-term outcome after renal transplantation, it does not incorporate individual differences of the aging-process itself. We therefore hypothesized that an estimate of biological organ age as derived from markers of cellular senescence in zero hour biopsies would be of higher predictive value. Telomere length and mRNA expression levels of the cell cycle inhibitors CDKN2A (p16INK4a) and CDKN1A (p21WAF1) were assessed in pre-implantation biopsies of 54 patients and the association of these and various other clinical parameters with serum creatinine after 1 year was determined. In a linear regression analysis, CDKN2A turned out to be the best single predictor followed by donor age and telomere length. A multiple linear regression analysis revealed that the combination of CDKN2A values and donor age yielded even higher predictive values for serum creatinine 1 year after transplantation. We conclude that the molecular aging marker CDKN2A in combination with chronological donor age predict renal allograft function after 1 year significantly better than chronological donor age alone.
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Affiliation(s)
- Christian Koppelstaetter
- Division of Nephrology, Department of Internal Medicine, Medical University Innsbruck, Innsbruck, Austria
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187
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Gruber HE, Hoelscher GL, Ingram JA, Bethea S, Hanley EN. IGF-1 rescues human intervertebral annulus cells from in vitro stress-induced premature senescence. Growth Factors 2008; 26:220-5. [PMID: 19021034 DOI: 10.1080/08977190802273814] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The aging human intervertebral disc contains a sizeable population of senescent cells. Since senescent cells cannot divide, senescence reduces the disc's ability to generate new cells to replace existing ones lost to necrosis or apoptosis. The objectives of the present work were: (1) to develop a reliable in vitro model for stress-induced premature senescence in human annulus cells, and (2) to investigate the potential for insulin-like growth factor-1 (IGF-1) to prevent or ameliorate senescence in vitro. The developed experimental model employs a 2 h exposure to 50 microM hydrogen peroxide; immunocytochemical localization of senescence associated-beta-galactosidase at pH 6.0 was used as the marker for senescent cells, and the percentage of senescent cells quantified after 3 days of culture. Nine sets of annulus cells were obtained from eight human surgical disc specimens; cells were tested with 0, 50, 100 or 500 ng/ml IGF-1. Although 50 or 100 ng/ml IGF-1 did not significantly alter the percentage of senescent cells, a significant reduction was present following exposure to 500 ng/ml IGF-1 (control, 56.3% +/- 8.5 (9); mean +/- SEM, (n) vs. treated, 39.6% +/- 6.6 (9), p = 0.0009). These novel findings point to the value of continued research towards development of future biologic therapies designed to reduce cell senescence in degenerating human discs.
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Affiliation(s)
- Helen E Gruber
- Department of Orthopaedic Surgery, Carolinas Medical Center, PO Box 32861, Charlotte, NC 28232, USA.
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188
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Abstract
Study Design Senescence-related markers were assessed in surgically obtained human nucleus pulposus (NP) specimens. Purpose To demonstrate the mechanism and signaling pathway involved in the senescence of NP chondrocytes. Overview of Literature The population of senescent disc cells has been shown to be increased in degenerated or herniated discs. However, the mechanism and signaling pathway involved in the senescence of NP chondrocytes are unknown. Methods We examined cell senescence markers [senescence-associated β-galactosidase (SA-β-gal), telomere length, telomerase activity, p53, p21, pRB and p16] and the hydrogen peroxide (H2O2) content in human NP specimens. Results The percentage of SA-β-gal-positive NP chondrocytes increased with age, while the telomere length and telomerase activity declined. However, there was no significant correlation between age and H2O2 content. The NP specimens with grade III or IV degeneration showed significantly higher percentages of SA-β-gal-positive NP chondrocytes than those with grade II degeneration. Immunohistochemistry showed that senescent NP chondrocytes in all specimens expressed p53, p21, and pRB, while a few NP chondrocytes in only two specimens expressed p16. Conclusions The present study demonstrates that, with increasing age and advancing disc degeneration, senescent NP chondrocytes increase or accumulate in the NP. Furthermore, the telomere-based p53, p21, pRB pathway, rather than the stress-based p16, pRB pathway, plays a more important role in the senescence of NP chondrocytes in in vivo conditions. Our results suggest that prevention or reversal of senescence of NP chondrocytes can be a novel mechanism by which to prevent human disc degeneration.
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189
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Abstract
The terms 'antioxidant', 'oxidative stress' and 'oxidative damage' are widely used but rarely defined. This brief review attempts to define them and to examine the ways in which oxidative stress and oxidative damage can affect cell behaviour both in vivo and in cell culture, using cancer as an example.
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190
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Grindon C, Combes R, Cronin MT, Roberts DW, Garrod JF. An Integrated Decision-tree Testing Strategy for Repeat Dose Toxicity with Respect to the Requirements of the EU REACH Legislation. Altern Lab Anim 2008; 36:93-101. [DOI: 10.1177/026119290803600110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This paper presents some results of a joint research project conducted by FRAME and Liverpool John Moores University, and sponsored by Defra, on the status of alternatives to animal testing with regard to the European Union REACH (Registration, Evaluation and Authorisation of Chemicals) system for the safety testing and risk assessment of chemicals. The project covered all the main toxicity end-points associated with REACH. This paper focuses on the use of alternative (non-animal) methods (both in vitro and in silico) for repeat dose (sub-acute, sub-chronic and chronic) toxicity testing. It reviews the limited number of in silico and in vitro tests available for this endpoint, and outlines new technologies which could be used in the future, e.g. the use of biomarkers and the ‘omics’ technologies. An integrated testing strategy is proposed, which makes use of as much non-animal data as possible, before any essential in vivo studies are performed. Although none of the non-animal tests are currently undergoing validation, their results could help to reduce the number of animals required for testing for repeat dose toxicity.
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Affiliation(s)
| | | | - Mark T.D. Cronin
- School of Pharmacy and Chemistry, Liverpool John Moores University, Liverpool, UK
| | - David W. Roberts
- School of Pharmacy and Chemistry, Liverpool John Moores University, Liverpool, UK
| | - John F. Garrod
- Chemicals and Nanotechnologies Division, Defra, London, UK
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191
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Tsirpanlis G. Cellular senescence, cardiovascular risk, and CKD: a review of established and hypothetical interconnections. Am J Kidney Dis 2008; 51:131-44. [PMID: 18155543 DOI: 10.1053/j.ajkd.2007.07.035] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 07/31/2007] [Indexed: 01/26/2023]
Abstract
Cellular senescence is associated with shortened or damaged telomeres and is characterized by permanent exit from the cell cycle, morphological changes, and altered function. It develops after repeated cell divisions and also can be induced prematurely by stress conditions. The senescent phenotype, depending on cell type and atherosclerosis phase, seems to be a proatherosclerotic one: it promotes endothelial dysfunction and appears to be implicated in plaque destabilization, as well as in endothelial progenitor cell alteration. Many traditional and nontraditional cardiovascular disease risk factors induce senescence in a variety of vascular cells. Several of these factors, such as diabetes, hypertension, oxidative stress, and inflammation, are clustered in patients with chronic kidney disease. In a limited number of recent studies, stress-induced premature cellular senescence in this biologically aged population also was described. The hypothesis that premature cellular senescence might be considered an additional atherosclerosis-inducing factor in patients with chronic kidney disease is proposed.
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Affiliation(s)
- George Tsirpanlis
- Department of Nephrology, General Hospital of Athens, Athens, Greece.
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192
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Shawi M, Autexier C. Telomerase, senescence and ageing. Mech Ageing Dev 2007; 129:3-10. [PMID: 18215413 DOI: 10.1016/j.mad.2007.11.007] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 11/23/2007] [Accepted: 11/30/2007] [Indexed: 10/22/2022]
Abstract
Telomeres serve to camouflage chromosome ends from the DNA damage response machinery. Telomerase activity is required to maintain telomeres. One consequence of telomere dysfunction is cellular senescence, a permanent growth arrest state. We review the key regulators of cellular senescence and recent in vivo evidence which supports p53-dependent senescence induced by short telomeres as a potent tumor suppressor pathway. The in vivo link between cellular senescence and tumor regression is also discussed. The relationship between short telomere length and ageing or disease states in various cells of the body is increasingly reported. Paradoxically, the introduction of telomerase is proposed as a method to combat ageing via cell therapy and a possible method to regenerate tissue, while telomerase inhibition and telomere shortening is suggested as a possible therapy to defeat cancers with intact p53. Researchers thus face the challenge of understanding the complex processes which regulate the potential benefits of both telomerase inhibition and activation.
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Affiliation(s)
- May Shawi
- Department of Medicine, Division of Experimental Medicine, McGill University, Canada
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193
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Hongxing Z, Nancai Y, Guofu H, Jianbo S, Yanxia W, Hanju H, Qian L, Wei M, Yandong Y, Hao H. Neuroprotective effects of purslane herb aquenous extracts against d-galactose induced neurotoxicity. Chem Biol Interact 2007; 170:145-52. [PMID: 17764668 DOI: 10.1016/j.cbi.2007.07.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2007] [Revised: 07/20/2007] [Accepted: 07/20/2007] [Indexed: 10/23/2022]
Abstract
In order to evaluate mechanisms of natural plant purslane herb aquenous extracts (PHAS) for neuroprotective, we assessed neuroprotective effects of PHAS at doses of 2.5, 5 and 10 mg/(kg day) on SD mice injected daily with D-gal (50 mg/(kg day)) by behavioral tests. PHAS-fed mice showed higher activity upon induction by new environmental stimuli, lower anxiety and higher novelty-seeking behavior in the open field tasks, and significantly improved learning and memory ability in step-through compared with D-gal-treated mice. We further examined the mechanisms involved in neuroprotective effects of PHAS on mouse brain. PHAS significantly increased superoxide dismutase (SOD) activity and decreased the malondialdehyde (MDA) level. Meanwhile, PHAS also could up-regulate telomere lengths and telomerase activity in PHAS-fed groups. Furthermore, we examined the expression of p21(waf1) and p53 mRNA and protein in mouse brain by western blot analysis and real-time RT-PCR. We found that p21(waf1)was down-regulated by PHAS without changing the expression of p53. The results of this study suggested that the PHAS might be a primary target of p21(waf1)and the neuroprotective effect of PHAS might be carried out through a p21(waf1)-dependent and p53-independent pathway.
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Affiliation(s)
- Zhang Hongxing
- Center of Experimental Medicine, Wuhan First Hospital, Wuhan City 430022, PR China
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194
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Ota H, Akishita M, Eto M, Iijima K, Kaneki M, Ouchi Y. Sirt1 modulates premature senescence-like phenotype in human endothelial cells. J Mol Cell Cardiol 2007; 43:571-9. [DOI: 10.1016/j.yjmcc.2007.08.008] [Citation(s) in RCA: 345] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 08/09/2007] [Accepted: 08/10/2007] [Indexed: 01/10/2023]
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195
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Iancu EM, Speiser DE, Rufer N. Assessing ageing of individual T lymphocytes: mission impossible? Mech Ageing Dev 2007; 129:67-78. [PMID: 18048082 DOI: 10.1016/j.mad.2007.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 10/15/2007] [Accepted: 10/23/2007] [Indexed: 12/22/2022]
Abstract
Effector T lymphocytes are the progeny of a limited number of antigen-specific precursor cells and it has been estimated that clonotypic human T cells may expand million fold on their way reaching high cell numbers that are sufficient for immune protection. Moreover, memory T cell responses are characterized by repetitive expansion of antigen-specific T cell clonotypes, and limitations in the proliferative capacity could lead to immune senescence. Because telomeres progressively shorten as a function of cell division, telomere length is a powerful indicator of the replicative in vivo history of human T lymphocytes. In this review, we summarize observations made over the last decade on telomere length dynamics of well-defined T cell populations derived from healthy donors and patients with infectious disease or cancer. We focus on T cell differentiation, T cell ageing, and natural and vaccine induced immune responses. We also discuss the scientific evidence for in vivo replicative senescence of antigen-specific T cells, and evaluate the available methods for measuring telomere lengths and telomerase activity, and their potential and limitations to increase our understanding of T cell physiology.
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Affiliation(s)
- Emanuela M Iancu
- Division of Experimental Oncology, Multidisciplinary Oncology Center CePO, Avenue Pierre-Decker 4, CH-1005 Lausanne, Switzerland
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196
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Betts DH, Perrault SD, King WA. Low oxygen delays fibroblast senescence despite shorter telomeres. Biogerontology 2007; 9:19-31. [PMID: 17952625 DOI: 10.1007/s10522-007-9113-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 10/09/2007] [Indexed: 01/29/2023]
Abstract
It has been widely accepted that telomere shortening acts as a cell division counting mechanism that beyond a set critical length signals cells to enter replicative senescence. In this study, we demonstrate that by simply lowering the oxygen content of the cell culture environment 10-fold (20-2%) extends the replicative lifespan of fetal bovine fibroblasts at least five-times (30-150 days). Although, low oxygen fibroblasts display a slightly slower rate (P > 0.05) of telomere attrition than their high oxygen counterparts (171 bp versus 182 bp/PD), late passage fibroblasts (>50 PD) that have extended their replicative capacity under low oxygen conditions exhibited significantly (P < 0.05) shorter telomere lengths (11,135 +/- 467 bp) compared to senescent cells (25-34 PD) cultured under high oxygen conditions (14,827 +/- 1173 bp). There was a significant increase (P < 0.05) in chromosomal abnormalities with continual cell division under both high and low oxygen environments, however, fibroblasts displayed a significant reduction (P < 0.001) in chromosomal abnormalities at low oxygen tensions compared to those under 20% oxygen. These apparent protective effects on telomere shortening, delayed senescence and reduced chromosomal aberrations may be attributed to the up-regulation of telomerase activity observed for fibroblasts cultured under low oxygen. These results are consistent with the idea that a critically short telomere length may not be the sole trigger of replicative senescence, but may be regulated by the integrity of telomere structure itself and/or the amount of oxidative DNA damage in the cell.
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Affiliation(s)
- Dean H Betts
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada, N1G 2W1.
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197
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Osanai M, Murata M, Nishikiori N, Chiba H, Kojima T, Sawada N. Occludin-mediated premature senescence is a fail-safe mechanism against tumorigenesis in breast carcinoma cells. Cancer Sci 2007; 98:1027-34. [PMID: 17459053 PMCID: PMC11159030 DOI: 10.1111/j.1349-7006.2007.00494.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We have previously demonstrated that epigenetic silencing of occludin, a tight junction-associated membrane protein, results in the acquisition of apoptotic resistance to various apoptogenic stimuli, causally contributing to the enhanced tumorigenicity of cancer cells. However, it remains to be examined whether occludin expression in transformed cells has an alternative impact that is important for cancer progression. Here we show that forced expression of occludin induces anoikis and promotes oxidative stress-induced premature senescence in breast carcinoma cells, which is accompanied by upregulation of negative cell cycle regulators such as p16(INK4A), p21(Waf1/Cip1) and p27(Kip1) but not p53. The senescent phenotype is reversed by specific inhibition of mitogen-activated protein kinase. Endogenous reexpression of occludin mediated by a synergistic effect with a demethylator and histone deacetylase inhibitor or retinoids that stimulate retinoic acid receptor alpha is also sufficient for provoking the senescent phenotype. In addition, tumors that developed from occludin-expressing cells in mice showed a feature of cellular senescence that has not been described as a consequence of occludin signaling. These findings suggest that the loss of occludin expression is at least partially involved in the senescence-escape program during mammary tumorigenesis.
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Affiliation(s)
- Makoto Osanai
- Department of Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan.
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198
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Grafi G, Ben-Meir H, Avivi Y, Moshe M, Dahan Y, Zemach A. Histone methylation controls telomerase-independent telomere lengthening in cells undergoing dedifferentiation. Dev Biol 2007; 306:838-46. [PMID: 17448460 DOI: 10.1016/j.ydbio.2007.03.023] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Revised: 03/09/2007] [Accepted: 03/18/2007] [Indexed: 11/21/2022]
Abstract
Cellular dedifferentiation underlies topical issues in biology such as regeneration and nuclear cloning and has common features in plants and animals. In plants, this process characterizes the transition of differentiated leaf cells to protoplasts (plant cells devoid of cell walls) and is accompanied by global chromatin reorganization associated with reprogramming of gene expression. A screen for mutants defective in proliferation and callus formation identified kyp-2-a mutant in the KRYPTONITE (KYP)/SUVH4 gene encoding a histone H3 lysine 9 (H3K9) methyltransferase. Analysis of telomere length revealed stochastic telomerase-independent lengthening of telomeres in wild type but not in kyp-2 protoplasts. In kyp-2 mutant, telomeric repeats were no longer associated with dimethylated H3K9. The Arabidopsis telomerase reverse transcriptase (tert) mutant displayed accelerated proliferation despite its short telomeres, though it also showed accelerated cell death. Microarray analysis uncovered several components of the ubiquitin proteolytic system, which are downregulated in kyp-2 compared to wild-type protoplasts. Thus, our results suggest that histone methylation activity is required for the establishment/maintenance of the dedifferentiated state and/or reentry into the cell cycle, at least partly, through activation of genes whose products are involved in the ubiquitin proteolytic pathway. In addition, our results illuminate the complexity of cellular dedifferentiation, particularly the occurrence of DNA recombination that can lead to genome instability.
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Affiliation(s)
- Gideon Grafi
- Albert Katz Department of Dryland Biotechnologies, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
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199
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M'kacher R, Bennaceur-Griscelli A, Girinsky T, Koscielny S, Delhommeau F, Dossou J, Violot D, Leclercq E, Courtier MH, Béron-Gaillard N, Assaf E, Ribrag V, Bourhis J, Feneux D, Bernheim A, Parmentier C, Carde P. Telomere Shortening and Associated Chromosomal Instability in Peripheral Blood Lymphocytes of Patients With Hodgkin’s Lymphoma Prior to Any Treatment Are Predictive of Second Cancers. Int J Radiat Oncol Biol Phys 2007; 68:465-71. [PMID: 17418962 DOI: 10.1016/j.ijrobp.2007.01.050] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 01/10/2007] [Accepted: 01/24/2007] [Indexed: 10/23/2022]
Abstract
PURPOSE To investigate a potential link between telomere length, chromosomal instability, and the advent of a second cancer (SC) in patients with Hodgkin's lymphoma (HL), who are known to be at risk for SCs. This study was premised on the finding that telomere dysfunction and DNA repair pathways were related to many pathologic conditions. METHODS AND MATERIALS Three cohorts of patients with HL were studied: 73 who were prospectively followed >5 years after diagnosis (prospective HL cohort), 28 who developed a SC (SC HL cohort), and 18 long-term survivors with no evidence of disease or complication since their initial treatment (NED HL cohort). Telomere length was analyzed by a telomeric restriction fragment assay in peripheral blood lymphocytes. Thirty healthy donors and 70 patients with a newly diagnosed solid tumor were the control population. RESULTS Compared with controls, patients from the prospective HL cohort, before any treatment, showed age-independent shorter telomeres (mean, 8.3 vs. 11.7 kb in healthy donors; <6 kb in 18% in HL patients), increased spontaneous chromosomal abnormalities, and increased in vitro radiation sensitivity (p < 10(-4) each). After treatment, telomere shortening was associated with cytogenetic profiles characterized by the persistence of complex chromosomal rearrangement and clonal aberrations. Moreover, the two cases of SC in the prospective HL patients had short telomeres and CCR initially. In addition, the SC HL cohort was characterized by markedly short telomeres (6.6 vs. 9.7 kb in the NED HL cohort), the presence of complex chromosome rearrangements, and increased in vitro radiation sensitivity. CONCLUSIONS An intimate relationship between pre-treatment telomere shortening, chromosomal instability, radiation sensitivity and occurrence of SC was found in HL patients.
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Affiliation(s)
- Radhia M'kacher
- Laboratoire de la Radiosensibilité des Tumeurs et des Tissus Sains, UPRES EA 27-10, Institut Gustave Roussy, Villejuif, France.
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200
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Lee S, Jeong SY, Lim WC, Kim S, Park YY, Sun X, Youle RJ, Cho H. Mitochondrial fission and fusion mediators, hFis1 and OPA1, modulate cellular senescence. J Biol Chem 2007; 282:22977-83. [PMID: 17545159 DOI: 10.1074/jbc.m700679200] [Citation(s) in RCA: 229] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The number and morphology of mitochondria within a cell are precisely regulated by the mitochondrial fission and fusion machinery. The human protein, hFis1, participates in mitochondrial fission by recruiting the Drp1 into the mitochondria. Using short hairpin RNA, we reduced the expression levels of hFis1 in mammalian cells. Cells lacking hFis1 showed sustained elongation of mitochondria and underwent significant cellular morphological changes, including enlargement, flattening, and increased cellular granularity. In these cells, staining for acidic senescence-associated beta-galactosidase activity was elevated, and the rate of cell proliferation was greatly reduced, indicating that cells lacking hFis1 undergo senescence-associated phenotypic changes. Reintroduction of the hFis1 gene into hFis1-depleted cells restored mitochondrial fragmentation and suppressed senescence-associated beta-galactosidase activity. Moreover, depletion of both hFis1 and OPA1, a critical component of mitochondrial fusion, resulted in extensive mitochondrial fragmentation and markedly rescued cells from senescence-associated phenotypic changes. Intriguingly, sustained elongation of mitochondria was associated with decreased mitochondrial membrane potential, increased reactive oxygen species production, and DNA damage. The data indicate that sustained mitochondrial elongation induces senescence-associated phenotypic changes that can be neutralized by mitochondrial fragmentation. Thus, one of the key functions of mitochondrial fission might be prevention of the sustained extensive mitochondrial elongation that triggers cellular senescence.
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Affiliation(s)
- Seungmin Lee
- Department of Biochemistry, Ajou University School of Medicine, Ajou University, 5 Wonchon-dong, Yeongtong-gu, Suwon 443-721, Korea
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