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Functional T cells are capable of supernumerary cell division and longevity. Nature 2023; 614:762-766. [PMID: 36653453 DOI: 10.1038/s41586-022-05626-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/05/2022] [Indexed: 01/20/2023]
Abstract
Differentiated somatic mammalian cells putatively exhibit species-specific division limits that impede cancer but may constrain lifespans1-3. To provide immunity, transiently stimulated CD8+ T cells undergo unusually rapid bursts of numerous cell divisions, and then form quiescent long-lived memory cells that remain poised to reproliferate following subsequent immunological challenges. Here we addressed whether T cells are intrinsically constrained by chronological or cell-division limits. We activated mouse T cells in vivo using acute heterologous prime-boost-boost vaccinations4, transferred expanded cells to new mice, and then repeated this process iteratively. Over 10 years (greatly exceeding the mouse lifespan)5 and 51 successive immunizations, T cells remained competent to respond to vaccination. Cells required sufficient rest between stimulation events. Despite demonstrating the potential to expand the starting population at least 1040-fold, cells did not show loss of proliferation control and results were not due to contamination with young cells. Persistent stimulation by chronic infections or cancer can cause T cell proliferative senescence, functional exhaustion and death6. We found that although iterative acute stimulations also induced sustained expression and epigenetic remodelling of common exhaustion markers (including PD1, which is also known as PDCD1, and TOX) in the cells, they could still proliferate, execute antimicrobial functions and form quiescent memory cells. These observations provide a model to better understand memory cell differentiation, exhaustion, cancer and ageing, and show that functionally competent T cells can retain the potential for extraordinary population expansion and longevity well beyond their organismal lifespan.
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2
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Glaberman S, Bulls SE, Vazquez JM, Chiari Y, Lynch VJ. Concurrent evolution of anti-aging gene duplications and cellular phenotypes in long-lived turtles. Genome Biol Evol 2021; 13:6430984. [PMID: 34792580 PMCID: PMC8688777 DOI: 10.1093/gbe/evab244] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2021] [Indexed: 11/23/2022] Open
Abstract
There are many costs associated with increased body size and longevity in animals, including the accumulation of genotoxic and cytotoxic damage that comes with having more cells and living longer. Yet, some species have overcome these barriers and have evolved remarkably large body sizes and long lifespans, sometimes within a narrow window of evolutionary time. Here, we demonstrate through phylogenetic comparative analysis that multiple turtle lineages, including Galapagos giant tortoises, concurrently evolved large bodies, long lifespans, and reduced cancer risk. We also show through comparative genomic analysis that Galapagos giant tortoises have gene duplications related to longevity and tumor suppression. To examine the molecular basis underlying increased body size and lifespan in turtles, we treated cell lines from multiple species, including Galapagos giant tortoises, with drugs that induce different types of cytotoxic stress. Our results indicate that turtle cells, in general, are resistant to oxidative stress related to aging, whereas Galapagos giant tortoise cells, specifically, are sensitive to endoplasmic reticulum stress, which may give this species an ability to mitigate the effects of cellular stress associated with increased body size and longevity.
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Affiliation(s)
- Scott Glaberman
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA.,Department of Biology, University of South Alabama, Mobile, AL, USA
| | | | - Juan Manuel Vazquez
- Department of Integrative Biology, University of California - Berkeley, Berkeley, CA, USA
| | - Ylenia Chiari
- Department of Biology, George Mason University, Fairfax, VA, USA
| | - Vincent J Lynch
- Department of Biological Sciences, University at Buffalo, SUNY, Buffalo, NY, USA
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Mikuła-Pietrasik J, Pakuła M, Markowska M, Uruski P, Szczepaniak-Chicheł L, Tykarski A, Książek K. Nontraditional systems in aging research: an update. Cell Mol Life Sci 2020; 78:1275-1304. [PMID: 33034696 PMCID: PMC7904725 DOI: 10.1007/s00018-020-03658-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 09/15/2020] [Accepted: 09/28/2020] [Indexed: 12/19/2022]
Abstract
Research on the evolutionary and mechanistic aspects of aging and longevity has a reductionist nature, as the majority of knowledge originates from experiments on a relatively small number of systems and species. Good examples are the studies on the cellular, molecular, and genetic attributes of aging (senescence) that are primarily based on a narrow group of somatic cells, especially fibroblasts. Research on aging and/or longevity at the organismal level is dominated, in turn, by experiments on Drosophila melanogaster, worms (Caenorhabditis elegans), yeast (Saccharomyces cerevisiae), and higher organisms such as mice and humans. Other systems of aging, though numerous, constitute the minority. In this review, we collected and discussed a plethora of up-to-date findings about studies of aging, longevity, and sometimes even immortality in several valuable but less frequently used systems, including bacteria (Caulobacter crescentus, Escherichia coli), invertebrates (Turritopsis dohrnii, Hydra sp., Arctica islandica), fishes (Nothobranchius sp., Greenland shark), reptiles (giant tortoise), mammals (blind mole rats, naked mole rats, bats, elephants, killer whale), and even 3D organoids, to prove that they offer biogerontologists as much as the more conventional tools. At the same time, the diversified knowledge gained owing to research on those species may help to reconsider aging from a broader perspective, which should translate into a better understanding of this tremendously complex and clearly system-specific phenomenon.
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Affiliation(s)
- Justyna Mikuła-Pietrasik
- Department of Pathophysiology of Ageing and Civilization Diseases, Poznań University of Medical Sciences, Długa 1/2 Str., 61-848 Poznań, Poland
| | - Martyna Pakuła
- Department of Hypertensiology, Poznań University of Medical Sciences, Długa 1/2 Str., 61-848 Poznań, Poland
| | - Małgorzata Markowska
- Department of Hypertensiology, Poznań University of Medical Sciences, Długa 1/2 Str., 61-848 Poznań, Poland
| | - Paweł Uruski
- Department of Hypertensiology, Poznań University of Medical Sciences, Długa 1/2 Str., 61-848 Poznań, Poland
| | | | - Andrzej Tykarski
- Department of Hypertensiology, Poznań University of Medical Sciences, Długa 1/2 Str., 61-848 Poznań, Poland
| | - Krzysztof Książek
- Department of Pathophysiology of Ageing and Civilization Diseases, Poznań University of Medical Sciences, Długa 1/2 Str., 61-848 Poznań, Poland
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Lorenzini A, Maier AB. Influence of Donor Age and Species Longevity on Replicative Cellular Senescence. CELLULAR AGEING AND REPLICATIVE SENESCENCE 2016. [DOI: 10.1007/978-3-319-26239-0_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Haines DD, Juhasz B, Tosaki A. Management of multicellular senescence and oxidative stress. J Cell Mol Med 2013; 17:936-57. [PMID: 23789967 PMCID: PMC3780549 DOI: 10.1111/jcmm.12074] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/18/2013] [Indexed: 12/15/2022] Open
Abstract
Progressively sophisticated understanding of cellular and molecular processes that contribute to age-related physical deterioration is being gained from ongoing research into cancer, chronic inflammatory syndromes and other serious disorders that increase with age. Particularly valuable insight has resulted from characterization of how senescent cells affect the tissues in which they form in ways that decrease an organism's overall viability. Increasingly, the underlying pathophysiology of ageing is recognized as a consequence of oxidative damage. This leads to hyperactivity of cell growth pathways, prominently including mTOR (mammalian target of rapamycin), that contribute to a build-up in cells of toxic aggregates such as progerin (a mutant nuclear cytoskeletal protein), lipofuscin and other cellular debris, triggering formation of senescent cellular phenotypes, which interact destructively with surrounding tissue. Indeed, senescent cell ablation dramatically inhibits physical deterioration in progeroid (age-accelerated) mice. This review explores ways in which oxidative stress creates ageing-associated cellular damage and triggers induction of the cell death/survival programs' apoptosis, necrosis, autophagy and 'necroapoptophagy'. The concept of 'necroapoptophagy' is presented here as a strategy for varying tissue oxidative stress intensity in ways that induce differential activation of death versus survival programs, resulting in enhanced and sustained representation of healthy functional cells. These strategies are discussed in the context of specialized mesenchymal stromal cells with the potential to synergize with telocytes in stabilizing engrafted progenitor cells, thereby extending periods of healthy life. Information and concepts are summarized in a hypothetical approach to suppressing whole-organism senescence, with methods drawn from emerging understandings of ageing, gained from Cnidarians (jellyfish, corals and anemones) that undergo a unique form of cellular regeneration, potentially conferring open-ended lifespans.
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Affiliation(s)
- David D Haines
- Department of Pharmacology, Faculty of Pharmacy, Health and Science Center, University of Debrecen, Debrecen, Hungary
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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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Affiliation(s)
- Jeffrey Powell
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520-8105, USA
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9
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Abstract
Since ageing is a universal human feature, it is not surprising that, from the Babylonian epic of Gilgamesh to Ponce de Leon seeking the "Fountain of Youth," countless people have dreamed of finding a way to avoid ageing, to no avail. Yet the search continues. In this review, we present one of the latest candidates: the enzyme telomerase, capable of elongating the tips of chromosomes, the telomeres. Research into the causes of cellular ageing established the telomeres as the molecular clock that counts the number of times cells divide and triggers cellular senescence. Herein, we review arguments both in favor and against the use of telomerase as an anti-ageing therapy. The importance of the telomeres in cellular ageing, the low or non-existent levels of telomerase activity in human tissues, and the ability of telomerase to immortalize human cells suggest that telomerase can be used as an anti-ageing therapy. On the other hand, recent experiments in mice have raised doubts whether telomerase affects organismal ageing. Results from human cells expressing telomerase have also suggested telomerase may promote tumorigenesis. We conclude that, though telomerase may be used in regenerative medicine and to treat specific diseases, it is unlikely to become a source of anti-ageing therapies.
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Affiliation(s)
- João Pedro de Magalhães
- Research Unit on Cellular Biology, Department of Biology, University of Namur (FUNDP), Namur, Belgium.
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Abstract
The incidence of aging is different between mammals and their closer ancestors (e.g. reptiles and amphibians). While all studied mammals express a well-defined aging phenotype, many amphibians and reptiles fail to show signs of aging. In addition, mammalian species show great similarities in their aging phenotype, suggesting that a common origin might be at work. The proposed hypothesis is that mammalian aging evolved together with the ancestry of modern mammals. In turn, this suggests that the fundamental cause of human aging is common to most, if not all, mammals and might be a unique phenomenon. Experimental procedures capable of testing these theories and how to map the causes of mammalian and thus, human aging, are predicted.
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Affiliation(s)
- João Pedro de Magalhães
- Department of Biology, Unit of Cellular Biochemistry and Biology, University of Namur (FUNDP), Rue de Bruxelles 61, 5000 Namur, Belgium.
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Abstract
Can studying cultured cells inform us about the biology of aging? The idea that this may be was stimulated by the first formal description of replicative senescence. Replicative senescence limits the proliferation of normal human cells in culture, causing them to irreversibly arrest growth and adopt striking changes in cell function. We now know that telomere shortening, which occurs in most somatic cells as a consequence of DNA replication, drives replicative senescence in human cells. However, rodent cells also undergo replicative senescence, despite very long telomeres, and DNA damage, the action of certain oncogenes and changes in chromatin induce a phenotype similar to that of replicatively senescent cells. Thus, replicative senescence is an example of the more general process of cellular senescence, indicating that the telomere hypothesis of aging is a misnomer, Cellular senescence appears to be a response to potentially oncogenic insults, including oxidative stress. The growth arrest almost certainly suppresses tumorigenesis, at least in young organisms, whereas the functional changes may contribute to aging, although this has yet to be critically tested. Thus, cellular senescence may be an example of antagonistic pleiotropy. Cross-species comparisons suggest there is a relationship between the senescence of cells in culture and organismal life span, but the relationship is neither quantitative nor direct.
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Affiliation(s)
- J Campisi
- Life Sciences Division, Lawrence Berkeley National Laboratory, Mailstop 84-171, 1 Cyclotron Road, Berkeley, CA 94720, USA.
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Kondo T, Sakaguchi M, Namba M. Two-dimensional gel electrophoretic studies on the cellular aging: accumulation of alpha-2-macroglobulin in human fibroblasts with aging. Exp Gerontol 2001; 36:487-95. [PMID: 11250120 DOI: 10.1016/s0531-5565(00)00256-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To understand the mechanisms that control life span and age-related phenotypes, we used two-dimensional (2D) gel electrophoresis to study the intracellular proteins whose amounts change during the process of cellular aging. We found that the amount of an alpha-2-macroglobulin (A2M) fragment derived from culture medium increased in the cells with aging. A2M is linked to Alzheimer's disease both genetically and functionally. This is the first report of accumulation of an A2M fragment in senescent fibroblasts. We also studied 2D gel profiles of human fibroblasts immortalized by treatment with either 60Co gamma rays or 4-nitroquinoline 1-oxide. As immortalized cells overcome cellular senescence to gain an unlimited life span, the proteins whose amounts change after immortalization may be relevant to the age-related phenotypes. 2D gel analysis revealed that the A2M fragment was down-regulated in the immortalized cells, compared with their normal counterparts, regardless of their passage. We also found that the other four proteins increased in amount with aging and decreased in amount after immortalization. Our results suggest: (1) the A2M incorporation into the cells is increased in the process of cellular aging; and (2) A2M may be linked to the age-related phenotypes that were lost during the process of immortalization of human cells.
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Affiliation(s)
- T Kondo
- Department of Cell Biology, Institute of Cellular and Molecular Biology, Okayama University Medical School, 2-5-1 Shikata-Cho, 700-8558, Okayama, Japan
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Grillari J, Hohenwarter O, Grabherr RM, Katinger H. Subtractive hybridization of mRNA from early passage and senescent endothelial cells. Exp Gerontol 2000; 35:187-97. [PMID: 10767578 DOI: 10.1016/s0531-5565(00)00080-2] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Regulation of cellular processes that eventually lead to a state of growth arrest is an important manifestation of in vitro cellular senescence caused and accompanied by variations of the gene expression pattern. Whereas these changes at the mRNA level have been studied mainly in fibroblast cultures, we concentrated on endothelial cells that represent an accepted model for vascular systems and may be involved in the pathogenesis of diseases related to aging. To isolate differentially expressed genes, we created a subtractive cDNA library using mRNA from senescent (35 passages) and young (five passages) human umbilical vein endothelial cells (HUVECs). Candidate clones were isolated from the cDNA library, differential expression was confirmed by Northern blot analyses and sequences were compared with a genbank data base. Because many mRNAs were below the detection limit of Northern blot analysis, we were forced to establish a more sensitive PCR based method (ATAC-PCR) to quantify and confirm altered levels of gene expression. Several mRNAs were found to be upregulated in senescent HUVECs including two components of the extracellular matrix (ECM): plasminogen activator inhibitor and fibronectin. Elevated expression of both has already been described in senescent cells. The mRNAs of TGF-beta-inducible gene H3 (beta-IG-H3; ECM protein), insulin-like growth factor binding protein (IGFBP-3), p53-inducible gene (PIG3) a protein involved in vesicular transport (SEC13R) and ribosomal protein L28 have likewise been shown to be preferentially expressed in senescent cells. Because studies support the involvement of ECM components, TGF-beta and p53 in tumor suppressing mechanisms, our data supports the hypothesis that cellular senescence and upregulation of ECM proteins may be associated with tumor preventive functions.
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Affiliation(s)
- J Grillari
- Institute of Applied Microbiology, University of Agricultural Sciences, Muthgasse 18, Vienna, Austria.
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Sedivy JM. Can ends justify the means?: telomeres and the mechanisms of replicative senescence and immortalization in mammalian cells. Proc Natl Acad Sci U S A 1998; 95:9078-81. [PMID: 9689036 PMCID: PMC33878 DOI: 10.1073/pnas.95.16.9078] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Finite replicative lifespan, or senescence, of mammalian cells in culture is a phenomenon that has generated much curiosity since its description. The obvious significance of senescence to organismal aging and the development of cancer has engendered a long-lasting and lively debate about its mechanisms. Recent discoveries concerning the phenotypes of telomerase knockout mice, the consequences of telomerase reexpression in somatic cells, and genes that regulate senescence have provided striking molecular insights but also have uncovered important new questions. The objective of this review is to reconcile old observations with new molecular details and to focus attention on the key remaining puzzles.
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Affiliation(s)
- J M Sedivy
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, USA.
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Hekimi S, Lakowski B, Barnes TM, Ewbank JJ. Molecular genetics of life span in C. elegans: how much does it teach us? Trends Genet 1998; 14:14-20. [PMID: 9448461 DOI: 10.1016/s0168-9525(97)01299-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Several loci have been identified in the nematode worm Caenorhabditis elegans that, when mutated, can increase life span. Three of these genes, age-1, daf-2 and clk-1, have now been cloned. Mutations in these three genes are highly pleiotropic and affect many aspects of worm development and behaviour, age-1 and daf-2 act in the same genetic pathway and have similar effects on the worm, age-1 encodes a homologue of the p110 subunit of phosphatidylinositol 3-kinase and daf-2 encodes an insulin receptor family member, clk-1 encodes a protein of unknown biochemical function similar to the yeast metabolic regulator Cat5p/Coq7p. The implications of these findings for our understanding of organismal ageing are discussed.
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Affiliation(s)
- S Hekimi
- Department of Biology, McGill University, Montréal, Québec, Canada.
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Wheaton K, Atadja P, Riabowol K. Regulation of transcription factor activity during cellular aging. Biochem Cell Biol 1996; 74:523-34. [PMID: 8960358 DOI: 10.1139/o96-056] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Several lines of evidence suggest that the limited replication potential of normal human cells is due to the presence of an intrinsic genetic programme. This "senescence programme" is believed to reduce the incidence of cancer by limiting the growth of most of the transformed cells arising in vivo, although some cells do escape senescence becoming both immortalized and transformed. Here we review the literature that describes the senescence process in terms of gene expression and the regulation of gene expression by a variety of mechanisms affecting transcription factor activity. We focus on regulation of the c-fos gene through posttranslational modification of the serum response factor (SRF) as an example of altered gene expression during cellular aging.
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Affiliation(s)
- K Wheaton
- Department of Medical Biochemistry, University of Calgary Health Sciences Centre, AB, Canada
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Henderson S, Allsopp R, Spector D, Wang SS, Harley C. In situ analysis of changes in telomere size during replicative aging and cell transformation. J Cell Biol 1996; 134:1-12. [PMID: 8698806 PMCID: PMC2120915 DOI: 10.1083/jcb.134.1.1] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Telomeres have been shown to gradually shorten during replicative aging in human somatic cells by Southern analysis. This study examines telomere shortening at the single cell level by fluorescence in situ hybridization (FISH). FISH and confocal microscopy of interphase human diploid fibroblasts (HDFs) demonstrate that telomeres are distributed throughout the nucleus with an interchromosomal heterogeneity in size. Analysis of HDFs at increasing population doubling levels shows a gradual decrease in spot size, intensity, and detectability of telomeric signal. FISH of metaphase chromosomes prepared from young and old HDFs shows a heterogeneity in detection frequency for telomeres on chromosomes 1, 9, 15, and Y. The interchromosomal distribution of detection frequencies was similar for cells at early and late passage. The telomeric detection frequency for metaphase chromosomes also decreased with age. These observations suggest that telomeres shorten at similar rates in normal human somatic cels. T-antigen transformed HDFs near crisis contained telomere signals that were low compared to nontransformed HDFs. A large intracellular heterogeneity in telomere lengths was detected in two telomerase-negative cell lines compared to normal somatic cells and the telomerase-positive 293 cell line. Many telomerase-negative immortal cells had telomeric signals stronger than those in young HDFs, suggesting a different mechanism for telomere length regulation in telomerase-negative immortal cells. These studies provide an in situ demonstration of interchromosomal heterogeneity in telomere lengths. Furthermore, FISH is a reliable and sensitive method for detecting changes in telomere size at the single cell level.
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Affiliation(s)
- S Henderson
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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Vojta PJ, Barrett JC. Genetic analysis of cellular senescence. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1242:29-41. [PMID: 7626653 DOI: 10.1016/0304-419x(95)00002-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- P J Vojta
- National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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21
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Goletz TJ, Hensler PJ, Ning Y, Adami GR, Pereira-Smith OM. Evidence for a genetic basis for the model system of cellular senescence. J Am Geriatr Soc 1993; 41:1255-8. [PMID: 8227901 DOI: 10.1111/j.1532-5415.1993.tb07311.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- T J Goletz
- Roy M. and Phyllis Gough Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030
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Macieira-Coelho A. Contributions made by the studies of cells in vitro for understanding of the mechanisms of aging. Exp Gerontol 1993; 28:1-16. [PMID: 8436202 DOI: 10.1016/0531-5565(93)90016-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Allsopp RC, Vaziri H, Patterson C, Goldstein S, Younglai EV, Futcher AB, Greider CW, Harley CB. Telomere length predicts replicative capacity of human fibroblasts. Proc Natl Acad Sci U S A 1992; 89:10114-8. [PMID: 1438199 PMCID: PMC50288 DOI: 10.1073/pnas.89.21.10114] [Citation(s) in RCA: 1506] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
When human fibroblasts from different donors are grown in vitro, only a small fraction of the variation in their finite replicative capacity is explained by the chronological age of the donor. Because we had previously shown that telomeres, the terminal guanine-rich sequences of chromosomes, shorten throughout the life-span of cultured cells, we wished to determine whether variation in initial telomere length would account for the unexplained variation in replicative capacity. Analysis of cells from 31 donors (aged 0-93 yr) indicated relatively weak correlations between proliferative ability and donor age (m = -0.2 doubling per yr; r = -0.42; P = 0.02) and between telomeric DNA and donor age (m = -15 base pairs per yr; r = -0.43; P = 0.02). However, there was a striking correlation, valid over the entire age range of the donors, between replicative capacity and initial telomere length (m = 10 doublings per kilobase pair; r = 0.76; P = 0.004), indicating that cell strains with shorter telomeres underwent significantly fewer doublings than those with longer telomeres. These observations suggest that telomere length is a biomarker of somatic cell aging in humans and are consistent with a causal role for telomere loss in this process. We also found that fibroblasts from Hutchinson-Gilford progeria donors had short telomeres, consistent with their reduced division potential in vitro. In contrast, telomeres from sperm DNA did not decrease with age of the donor, suggesting that a mechanism for maintaining telomere length, such as telomerase expression, may be active in germ-line tissue.
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Affiliation(s)
- R C Allsopp
- Department of Biochemistry, McMaster University, Hamilton, ON, Canada
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Irving J, Feng J, Wistrom C, Pikaart M, Villeponteau B. An altered repertoire of fos/jun (AP-1) at the onset of replicative senescence. Exp Cell Res 1992; 202:161-6. [PMID: 1511730 DOI: 10.1016/0014-4827(92)90415-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
With multiple divisions in culture, normal diploid cells suffer a loss of growth potential that leads to replicative senescence and a finite replicative capacity. Using quantitative RT-PCR, we have monitored mRNA expression levels of c-fos, c-jun, JunB, c-myc, p53, H-ras, and histone H4 during the replicative senescence of human fibroblasts. The earliest and the largest changes in gene expression occurred in c-fos and junB at mid-senescence prior to the first slowing in cell growth rates. The basal level of c-fos mRNA decreased to one-ninth that of the early-passage levels, while junB declined to one-third and c-jun expression remained constant. The decline in the basal c-fos mRNA level in mid-senescence should lead to an increase in Jun/Jun AP-1 homodimers at the expense of Fos/Jun heterodimers and may trigger a cascade of further changes in c-myc, p53, and H-ras expression in late-passage senescent fibroblasts.
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Affiliation(s)
- J Irving
- Department of Biological Chemistry, University of Michigan, Ann Arbor 48105-2007
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25
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Hou L, Takeuchi T. Differentiation of reptilian neural crest cells in vitro. IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY : JOURNAL OF THE TISSUE CULTURE ASSOCIATION 1992; 28A:348-54. [PMID: 1317837 DOI: 10.1007/bf02877058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
An attempt was made to culture neural crest cells of the turtle embryo in vitro. Trunk neural tubes from the St. 9/10 embryos were explanted in culture dishes. The developmental potency of the turtle neural crest cells in vitro was shown to be essentially similar to that of avian neural crest cells, although they seem to be more sensitive to melanocyte-stimulating hormone (MSH) stimulation. We describe conditions under which explanted neural tube gives rise to neural crest cells that differentiate into neuronal cells and melanocytes. The potency of melanocyte differentiation was found to vary according to the concentration of fetal bovine serum (FBS, from 5 to 20%). Melanization of neural crest cells cultured in the medium containing FBS and alpha-MSH was more extensive than those cultured with FBS alone, combinations of FBS and chick embryo extract, or turtle embryo extract. These culture conditions seem to be useful for the study of the developmental potency of the neural crest cells as well as for investigating local environmental factors.
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Affiliation(s)
- L Hou
- Biological Institute, Faculty of Science, Tohoku University, Sendai, Japan
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26
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Riabowol K, Schiff J, Gilman MZ. Transcription factor AP-1 activity is required for initiation of DNA synthesis and is lost during cellular aging. Proc Natl Acad Sci U S A 1992; 89:157-61. [PMID: 1729683 PMCID: PMC48195 DOI: 10.1073/pnas.89.1.157] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Activation of the AP-1 complex of transcription factors is one of the earliest nuclear responses to mitogenic stimuli. We demonstrate directly that AP-1 activity is required for human cells to proliferate in response to serum. We also find that activity of the AP-1 complex is selectively reduced in old human fibroblasts prior to their entering a fully senescent state. Levels of Fos protein induced through diverse signal transduction pathways, the amount of AP-1 DNA binding activity in vitro, and the activity of an AP-1-dependent reporter gene in vivo are substantially decreased as fibroblasts age. Moreover, the composition of the AP-1 complex changes, so that old cells produce predominantly Jun-Jun homodimers instead of Fos-Jun heterodimers. Changes in AP-1 activity may be due in part to changes in posttranslational modification of Fos protein that impair its ability to form active DNA-binding heterodimers with Jun. These data suggest that changes in AP-1 activity may contribute to the inability of senescent cells to proliferate in response to mitogens.
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27
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Abstract
Normal cells in culture exhibit limited division potential, which is used as a model for cellular aging. In contrast, tumor-derived, carcinogen- or virus-transformed cells are capable of dividing indefinitely (immortal). Fusion of normal with immortal human cells yielded hybrids having limited life span, indicating that cellular senescence is a dominant phenotype and that immortality is recessive. Fusions of various immortal human cell lines with each other led to the identification of four complementation groups for indefinite division. In order to identify the chromosomes and genes involved in growth regulation, that had been modified in immortal cells, we used the technique of microcell fusion to introduce either a normal human chromosome 11 or 4 into cell lines representative of the different complementation groups. Chromosome 11 had no effect on the in vitro life span of the different immortal human tumor lines. However, when a normal human chromosome 4 was introduced into cell lines assigned to complementation group B, the cells lost the immortal phenotype. No effect on the proliferation potential of cell lines representative of the other complementation groups was observed. These results suggest that a gene(s) on human chromosome 4 has been modified in immortal cell lines assigned to complementation group B, to allow escape from senescence. They also provide evidence for a genetic basis for cellular aging.
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Affiliation(s)
- Y Ning
- Roy M. and Phyllis Gough Huffington Center on Aging, Division of Molecular Virology, Baylor College of Medicine, Houston, TX 77030
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28
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Abstract
The Holy Grail of gerontologists investigating cellular senescence is the mechanism responsible for the finite proliferative capacity of somatic cells. In 1973, Olovnikov proposed that cells lose a small amount of DNA following each round of replication due to the inability of DNA polymerase to fully replicate chromosome ends (telomeres) and that eventually a critical deletion causes cell death. Recent observations showing that telomeres of human somatic cells act as a mitotic clock, shortening with age both in vitro and in vivo in a replication dependent manner, support this theory's premise. In addition, since telomeres stabilize chromosome ends against recombination, their loss could explain the increased frequency of dicentric chromosomes observed in late passage (senescent) fibroblasts and provide a checkpoint for regulated cell cycle exit. Sperm telomeres are longer than somatic telomeres and are maintained with age, suggesting that germ line cells may express telomerase, the ribonucleoprotein enzyme known to maintain telomere length in immortal unicellular eukaryotes. As predicted, telomerase activity has been found in immortal, transformed human cells and tumour cell lines, but not in normal somatic cells. Telomerase activation may be a late, obligate event in immortalization since many transformed cells and tumour tissues have critically short telomeres. Thus, telomere length and telomerase activity appear to be markers of the replicative history and proliferative potential of cells; the intriguing possibility remains that telomere loss is a genetic time bomb and hence causally involved in cell senescence and immortalization.
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Affiliation(s)
- C B Harley
- Department of Biochemistry, McMaster University, Hamilton, Ont., Canada
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29
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Abstract
Human diploid fibroblasts undergo replicative senescence predominantly because of arrest at the G1/S boundary of the cell cycle. Senescent arrest resembles a process of terminal differentiation that appears to involve repression of proliferation-promoting genes with reciprocal new expression of antiproliferative genes, although post-transcriptional factors may also be involved. Identification of participating genes and clarification of their mechanisms of action will help to elucidate the universal cellular decline of biological aging and an important obverse manifestation, the rare escape of cells from senescence leading to immortalization and oncogenesis.
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Affiliation(s)
- S Goldstein
- Department of Medicine, University of Arkansas for Medical Sciences, Little Rock
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31
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Abstract
Procaine is a local anesthetic, also used in experimental gerontology and has been tested in cultivated human WI-38 fibroblasts. This molecule was found to enhance growth rate and cell densities in actively dividing cultures. As the cells aged, however, this stimulatory effect diminished and finally vanished. In a long term experiment the enhancement of growth of procaine treated cultures was finally replaced by a toxic effect even at low concentration. The amount of the thermolabile enzyme found in phase III cells did not change when procaine was added to the culture medium. In this cellular aging model, procaine behaved like a metabolic stimulator of actively dividing cells but not as an "antiaging" molecule as it is sometimes assumed.
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Affiliation(s)
- E Pigeolet
- Laboratoire de Biochime Cellulaire, Facultés Universitaires, Namur, Belgium
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32
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Abstract
The field of cellular senescence (cytogerontology) is reviewed. The historical precedence for investigation in this field is summarized, and placed in the context of more recent studies of the regulation of cellular proliferation and differentiation. The now-classical embryonic lung fibroblast model is compared to models utilizing other cell types as well as cells from donors of different ages and phenotypes. Modulation of cellular senescence by growth factors, hormones, and genetic manipulation is contrasted, but newer studies in oncogene involvement are omitted. A current consensus would include the view that the life span of normal diploid cells in culture is limited, is under genetic control, and is capable of being modified. Finally, embryonic cells aging in vitro share certain characteristics with early passage cells derived from donors of increasing age.
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34
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Abstract
Cultures of mouse cells of various population doubling levels (PDL) were examined for DNA-repair capabilities as estimated by (i) the excision of pyrimidine dimers; (ii) unscheduled DNA synthesis (UDS) in response to UV-irradiation or N-methyl-N'-nitrosoguanidine (MNNG) treatment; (iii) the levels of two DNA-repair enzyme activities, uracil DNA glycosylase and AP endonuclease. The responses to ultraviolet light and MNNG decreased rapidly within the first two PDL and more slowly thereafter until essentially no repair was detected by PDL 12. A continuous cell line which emerged from the cultured cells after a crises period had some restoration of repair capability. The amount of uracil DNA glycosylase activity decreased by approximately 40% before the crises period then decreased by 90% in the continuous cell line. In contrast, the amount of AP endonuclease activity present in the precrises cells showed no significant change until PDL 12, then increased 6-7-fold in the continuous cell line.
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35
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Kondo H, Ide H. Long-term cultivation of amphibian melanophores. In vitro ageing and spontaneous transformation to a continuous cell line. Exp Cell Res 1983; 149:247-56. [PMID: 6315460 DOI: 10.1016/0014-4827(83)90396-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Pure melanophore populations isolated from the tail skin of the tadpole, Rana catesbeiana, were mass cultured for a period of 2-3 years. All cell lines of amphibian melanophores studied exhibited growth crisis (in vitro ageing) followed by spontaneous transformation to a continuous cell line, as shown by changes in growth characteristics in mass culture and in clone culture, by the appearance of the cells, and by measurements of cell volumes. Even after becoming a continuous cell line, amphibian melanophores continued to have a diploid chromosome number (2n = 26) in three of four cell lines examined. The chromosome mode in one cell line, however, changed to thirty. Measurement of melanin dispersion after the addition of alpha-melanocyte-stimulating hormone suggested that the mechanism for melanin dispersion in melanophores changed during in vitro ageing.
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37
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Cristofalo VJ, Stanulis-Praeger BM. Cellular Senescence in Vitro. ACTA ACUST UNITED AC 1982. [DOI: 10.1016/b978-0-12-007902-5.50007-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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38
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Macieira-Coelho A. Tissue culture in aging research: present status and prospects. EXPERIENTIA 1981; 37:1050-3. [PMID: 7308385 DOI: 10.1007/bf02085004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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39
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Meek RL, Rebeiro T, Daniel CW. Patterns of unscheduled DNA synthesis in mouse embryo cells associated with in vitro aging and with spontaneous transformation to a continuous cell line. Exp Cell Res 1980; 129:265-71. [PMID: 7428819 DOI: 10.1016/0014-4827(80)90492-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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40
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Meek RL, Bowman PD, Daniel CW. Establishment of rat embryonic cells in vitro. Relationship of DNA synthesis, senescence, and acquisition of unlimited growth potential. Exp Cell Res 1980; 127:127-32. [PMID: 7379860 DOI: 10.1016/0014-4827(80)90420-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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41
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Müller I, Zimmermann M, Becker D, Flömer M. Calendar life span versus budding life span of Saccharomyces cerevisiae. Mech Ageing Dev 1980; 12:47-52. [PMID: 6986516 DOI: 10.1016/0047-6374(80)90028-7] [Citation(s) in RCA: 141] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This investigation is concerned with the internal factors governing the life span of individual yeast cells. The life span may be limited either by the number of buds a cell can produce or by internal measurement of metabolic time. The natural relationship between the number of cells a single cell can produce and the passage of time was modified by three different kinds of treatment: (1) by cooling the cells for several hours each day; (2) by preculturing the cells in media which inhibit cell division before allowing logarithmic growth; and (3) by culturing the cells in a medium which reduces the rate of budding. All these methods led to a prolongation of chronological life span, but the life span measured by the number of buddings remained remarkably constant. We therefore conclude that there is some kind of factor involved in the budding process which determines life span.
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42
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Blumenthal GH, Kasbekar DK. Nonreplicating cultures of frog gastric tubular cells. INTERNATIONAL REVIEW OF CYTOLOGY. SUPPLEMENT 1979:191-212. [PMID: 391744 DOI: 10.1016/s0074-7696(08)60621-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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43
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Macierira-Coelho A, Diatloff C, Billard M, Fertil B, Malaise E, Fries D. Effects of low dose rate irradiation on the division potential of cells in vitro. IV. Embryonic and adult human lung fibroblast-like cells. J Cell Physiol 1978; 95:235-8. [PMID: 649663 DOI: 10.1002/jcp.1040950213] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Early and late passage human embryonic lung fibroblasts were compared with early passage adult lung fibroblasts with regards to their survival (number of population doublings), after low dose rate ionizing radiation. It was found that early passage embryonic cells are quite resistant to this type of radiation. Late passage embryonic and early passage adult fibroblasts are more sensitive to ionizing radiations. The results suggest that cell aging is accompanied by an increased sensitivity to low dose rate ionizing radiation and favor the idea that aging in vitro, expressed as a function of the fibroblast division potential, is correlated with aging in vivo.
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44
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Kaftory A, Hershko A, Fry M. Protein turnover in senescent cultured chick embryo fibroblasts. J Cell Physiol 1978; 94:147-60. [PMID: 621215 DOI: 10.1002/jcp.1040940204] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The over-all rates of protein synthesis, degradation and net accumulation were estimated in rapidly growing young and slowly doubling old cultures of chick fibroblasts. We find that not only the rate of protein synthesis is reduced in senescent cultures, but the average rate of protein degradation is also slowed down considerably. This decrease in the rate of protein breakdown in aging cells stands in contrast with the previously observed acceleration of this process by other conditions (such as serum deprivation or overcrowding) that lead to the cessation of cellular growth. Though the retarded protein degradation may contribute to the acculation of abnormal proteins in senescent cells we find that the breakdown of grossly abnormal puromycin peptides proceeds equally rapidly in young and old cultures. The protein content of senescent cells increases by 1.8-fold as compared to young cells, while the average cell volume is increased even more (almost 5-fold). By contrast, consideration of the over-all balance of protein metabolism in these cells indicates that the average concentration of metabolically turning-over proteins is somewhat higher in senescent than in young fibroblasts.
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45
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Miller RC, Nichols WW, Pottash J, Aronson MM. In vitro aging. Cytogenetic comparison of diploid human fibroblast and epithelioid cell lines. Exp Cell Res 1977; 110:63-73. [PMID: 923666 DOI: 10.1016/0014-4827(77)90270-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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46
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Schneider EL, Mitsui Y, Au KS, Shorr SS. Tissue-specific differences in cultured human diploid fibroblasts. Exp Cell Res 1977; 108:1-6. [PMID: 891625 DOI: 10.1016/s0014-4827(77)80002-5] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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47
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Fry M, Weisman-Shomer P. Altered nuclear deoxyribonucleic acid alpha-polymerases in senescent cultured chick embryo fibroblasts. Biochemistry 1976; 15:4319-29. [PMID: 986831 DOI: 10.1021/bi00664a028] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
DNA alpha-polymerase has been partially purified from nuclei of cultured chic, fibroblasts and separated on phosphocellulose columns into two distinct activities designated DNA polymerases alpha(a) and alpha(b), respectively. The enzyme preparations were devoid of activities of DNA beta,gamma-polymerases terminal deoxyribonucleoside transferase, DNase, DNA-dependent RNA polymerase, and phosphatase. DNA polymerases alpha(a) and alpha(b) both having molecular weights of 160 000, constitute 35-50 and 65-50%, respectively, of the activity of alpha-polymerase in the nucleus. These enzymes differ in their requirements for maximal activity, their relative ability to copy oligo(dG)-poly(dC), their response to ribonucleoside triphosphates, and their kinetics of heat inactivation. When the properties of alpha polymerases derived from early or late passage cultures have been compared, no difference could be detected as a function of cell age in the specific activities of the polymerases in crude cell extracts, their chromatographic behavior on diethylaminoethylcellulose and phosphocellulose columns, and their relative abilities to utilize single deoxyribonucleoside triphosphates with activated DNA template. On the other hand, both enzymes become partially heat labile in aging cells. Also, the activity of DNA polymerase alpha(a) from young cells was stimulated by 2--10 mM adenosine or cytidine triphosphates, whereas the same enzyme from old cultures was inhibited by these agents. Conversely, these ribonucleoside triphosphates inhibited the activity of polymerase alpha(b) in young cells but slightly stimulated this enzyme derived from senescent fibroblasts. In addition, the relative ability of DNA polymerase alpha(a) to copy oligo(dG)-poly(dC) decreased in aged cells, whereas that of DNA polymerase alpha(b) increased. We have also observed significant differences in the effects of potassium chloride and N-ethylmaleimide on the activity of DNA polymerase alpha(a) from old cells as compared to young cells. These age-related alterations in the properties of the two avian DNA polymerases may reflect structural or conformational changes in these enzymes.
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48
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Lipetz J, Boswell RE. Cell types originating from kidney explants of young and old mice. EXPERIENTIA 1976; 32:48-50. [PMID: 1248587 DOI: 10.1007/bf01932617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Explants from young and old mouse kidneys give rise to two different cell types when placed in organ culture dishes. The two cell types differ in morphology and ability to grow in vitro. Explants from young mice give rise to one predominant cell type; those from old mice give rise to another. Our data supports the mosaic theory of aging.
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49
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Waters BK, Wallace RB, Freeman KB. Characterization of cytosol and mitochondrial rRNA of reptiles in relation to evolution. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1976; 53:283-6. [PMID: 1253564 DOI: 10.1016/0305-0491(76)90326-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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50
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Wright WE, Hayflick L. Nuclear control of cellular aging demonstrated by hybridization of anucleate and whole cultured normal human fibroblasts. Exp Cell Res 1975; 96:113-21. [PMID: 172352 DOI: 10.1016/s0014-4827(75)80043-7] [Citation(s) in RCA: 82] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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