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Clayton ZS, Craighead DH, Darvish S, Coppock M, Ludwig KR, Brunt VE, Seals DR, Rossman MJ. Promoting healthy cardiovascular aging: emerging topics. THE JOURNAL OF CARDIOVASCULAR AGING 2022; 2:43. [PMID: 36337728 PMCID: PMC9632540 DOI: 10.20517/jca.2022.27] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The development of age-related cardiovascular (CV) dysfunction increases the risk of CV disease as well as other chronic age-associated disorders, including chronic kidney disease, and Alzheimer's disease and related dementias. Major manifestations of age-associated CV dysfunction that increase disease risk are vascular dysfunction, primarily vascular endothelial dysfunction and arterial stiffening, and elevated systolic blood pressure. Declines in nitric oxide bioavailability secondary to increased oxidative stress and inflammation are established mechanisms of CV dysfunction with aging. Moreover, fundamental mechanisms of aging, termed the "hallmarks of aging" extend to the CV system and, as such, may be considered "hallmarks of CV aging". These mechanisms represent viable therapeutic targets for treating CV dysfunction with aging. Healthy lifestyle behaviors, such as regular aerobic exercise and certain dietary patterns, are considered "first-line" strategies to prevent and/or treat age-associated CV dysfunction. Despite the well-established benefits of these strategies, many older adults do not meet the recommended guidelines for exercise or consume a healthy diet. Therefore, it is important to establish alternative and/or complementary evidence-based approaches to prevent or reverse age-related CV dysfunction. Targeting fundamental mechanisms of CV aging with interventions such as time-efficient exercise training, food-derived molecules, termed nutraceuticals, or select synthetic pharmacological agents represents a promising approach. In the present review, we will highlight emerging topics in the field of healthy CV aging with a specific focus on how exercise, nutrition/dietary patterns, nutraceuticals and select synthetic pharmacological compounds may promote healthy CV aging, in part, by targeting the hallmarks of CV aging.
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Affiliation(s)
- Zachary S Clayton
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Daniel H Craighead
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Sanna Darvish
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - McKinley Coppock
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Katelyn R Ludwig
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Vienna E Brunt
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Douglas R Seals
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Matthew J Rossman
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
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Cohen AA, Ferrucci L, Fülöp T, Gravel D, Hao N, Kriete A, Levine ME, Lipsitz LA, Olde Rikkert MGM, Rutenberg A, Stroustrup N, Varadhan R. A complex systems approach to aging biology. NATURE AGING 2022; 2:580-591. [PMID: 37117782 DOI: 10.1038/s43587-022-00252-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 06/08/2022] [Indexed: 04/30/2023]
Abstract
Having made substantial progress understanding molecules, cells, genes and pathways, aging biology research is now moving toward integration of these parts, attempting to understand how their joint dynamics may contribute to aging. Such a shift of perspective requires the adoption of a formal complex systems framework, a transition being facilitated by large-scale data collection and new analytical tools. Here, we provide a theoretical framework to orient researchers around key concepts for this transition, notably emergence, interaction networks and resilience. Drawing on evolutionary theory, network theory and principles of homeostasis, we propose that organismal function is accomplished by the integration of regulatory mechanisms at multiple hierarchical scales, and that the disruption of this ensemble causes the phenotypic and functional manifestations of aging. We present key examples at scales ranging from sub-organismal biology to clinical geriatrics, outlining how this approach can potentially enrich our understanding of aging.
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Affiliation(s)
- Alan A Cohen
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, Quebec, Canada.
- Research Center on Aging and Research Center of Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec, Canada.
- Butler Columbia Aging Center and Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
| | - Luigi Ferrucci
- Intramural Research Program of the National Institute on Aging, Baltimore, MD, USA
| | - Tamàs Fülöp
- Research Center on Aging and Research Center of Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec, Canada
- Department of Medicine, Geriatric Division, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Dominique Gravel
- Department of Biology, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Nan Hao
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, San Diego, CA, USA
| | - Andres Kriete
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Morgan E Levine
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
| | - Lewis A Lipsitz
- Beth Israel Deaconess Medical Center, Hebrew SeniorLife, Hinda and Arthur Marcus Institute for Aging Research, and Harvard Medical School, Boston, MA, USA
| | | | - Andrew Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Nicholas Stroustrup
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Ravi Varadhan
- Department of Oncology, Quantitative Sciences Division, Johns Hopkins University, Baltimore, MD, USA
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Kern CC, Gems D. Semelparous Death as one Element of Iteroparous Aging Gone Large. Front Genet 2022; 13:880343. [PMID: 35754809 PMCID: PMC9218716 DOI: 10.3389/fgene.2022.880343] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/11/2022] [Indexed: 11/13/2022] Open
Abstract
The aging process in semelparous and iteroparous species is different, but how different? Death in semelparous organisms (e.g., Pacific salmon) results from suicidal reproductive effort (reproductive death). Aging (senescence) in iteroparous organisms such as humans is often viewed as a quite different process. Recent findings suggest that the nematode Caenorhabditis elegans, widely used to study aging, undergoes reproductive death. In post-reproductive C. elegans hermaphrodites, intestinal biomass is repurposed to produce yolk which when vented serves as a milk to support larval growth. This apparent benefit of lactation comes at the cost of intestinal atrophy in the mother. Germline removal and inhibition of insulin/IGF-1 signaling (IIS) suppress C. elegans reproductive pathology and greatly increase lifespan. Blocking sexual maturity, e.g., by gonadectomy, suppresses reproductive death thereby strongly increasing lifespan in semelparous organisms, but typically has little effect on lifespan in iteroparous ones. Similarly, reduced IIS causes relatively modest increases in lifespan in iteroparous organisms. We argue that the more regulated and plastic mechanisms of senescence in semelparous organisms, involving costly resource reallocation under endocrine control, exist as one extreme of an etiological continuum with mechanisms operative in iteroparous organisms. We suggest that reproductive death evolved by exaggeration of mechanisms operative in iteroparous species, where other mechanisms also promote senescence. Thus, knowledge of C. elegans senescence can guide understanding of mechanisms contributing to human aging.
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Affiliation(s)
- Carina C Kern
- Institute of Healthy Ageing, Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - David Gems
- Institute of Healthy Ageing, Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
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Blagosklonny MV. Hallmarks of cancer and hallmarks of aging. Aging (Albany NY) 2022; 14:4176-4187. [PMID: 35533376 PMCID: PMC9134968 DOI: 10.18632/aging.204082] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/02/2022] [Indexed: 11/28/2022]
Abstract
A thought-provoking article by Gems and de Magalhães suggests that canonic hallmarks of aging are superficial imitations of hallmarks of cancer. I took their work a step further and proposed hallmarks of aging based on a hierarchical principle and the hyperfunction theory. To do this, I first reexamine the hallmarks of cancer proposed by Hanahan and Weinberg in 2000. Although six hallmarks of cancer are genuine, they are not hierarchically arranged, i.e., molecular, intra-cellular, cellular, tissue, organismal and extra-organismal. (For example, invasion and angiogenesis are manifestations of molecular alterations on the tissue level; metastasis on the organismal level, whereas cell immortality is observed outside the host). The same hierarchical approach is applicable to aging. Unlike cancer, however, aging is not a molecular disease. The lowest level of its origin is normal intracellular signaling pathways such as mTOR that drive developmental growth and, later in life, become hyperfunctional, causing age-related diseases, whose sum is aging. The key hallmark of organismal aging, from worms to humans, are age-related diseases. In addition, hallmarks of aging can be arranged as a timeline, wherein initial hyperfunction is followed by dysfunction, organ damage and functional decline.
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Abstract
Biology of aging is an active and rapidly expanding area of biomedical research. Over the years, focus of work in this field has been gradually shifting from studying the effects and symptoms of aging to searching for mechanisms of the aging process. Progress of this work led to an additional shift from looking for "the mechanism" of aging and formulating the corresponding "theories of aging" to appreciation that aging represents a net result of multiple physiological changes and their intricate interactions. It was also shown that mechanisms of aging include nutrient-dependent signaling pathways which have been remarkably conserved in the course of the evolution. Another important development in this field is increased emphasis on searching for pharmacological and environmental interventions that can extend healthspan or influence other aspects of aging. Progress in understanding the key role of aging as a risk factor for chronic disease provides impetus for these studies. Data from the recent pandemic provided additional evidence for the impact of age on resilience. Progress of work in this area also was influenced by major analytical and technological advances, including greatly improved methods for the study of gene expression, protein, lipids, and metabolites profiles, enhanced ability to produce various genetic modifications and novel approaches to assessment of biological age. Progress in research on the biology of aging provides reasons for optimism about the chances that safe and widely applicable anti-aging interventions with significant benefits for both individual and public health will be developed in the not too distant future.
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Affiliation(s)
- Andrzej Bartke
- Department of Internal Medicine, Southern Illinois University School of Medicine, 801 N. Rutledge St., P. O. Box 19628, Springfield, IL, 62794-9628, USA.
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Schork NJ, Beaulieu-Jones B, Liang W, Smalley S, Goetz LH. Does Modulation of an Epigenetic Clock Define a Geroprotector? ADVANCES IN GERIATRIC MEDICINE AND RESEARCH 2022; 4:e220002. [PMID: 35466328 PMCID: PMC9022671 DOI: 10.20900/agmr20220002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There is growing interest in the development of interventions (e.g., drugs, diets, dietary supplements, behavioral therapies, etc.) that can enhance health during the aging process, prevent or delay multiple age-related diseases, and ultimately extend lifespan. However, proving that such 'geroprotectors' do what they are hypothesized to do in relevant clinical trials is not trivial. We briefly discuss some of the more salient issues surrounding the design and interpretation of clinical trials of geroprotectors, including, importantly, how one defines a geroprotector. We also discuss whether emerging surrogate endpoints, such as epigenetic clocks, should be treated as primary or secondary endpoints in such trials. Simply put, geroprotectors should provide overt health and disease prevention benefits but the time-dependent relationships between epigenetic clocks and health-related phenomena are complex and in need of further scrutiny. Therefore, studies that enable understanding of the relationships between epigenetic clocks and disease processes while simultaneously testing the efficacy of a candidate geroprotector are crucial to move the field forward.
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Affiliation(s)
- Nicholas J. Schork
- Department of Quantitative Medicine, The Translational Genomics Research Institute (TGen), 445 North Fifth Street, Phoenix, AZ 85004, USA
- Net.bio Inc, Los Angeles, CA 90403, USA
| | - Brett Beaulieu-Jones
- Net.bio Inc, Los Angeles, CA 90403, USA
- Department of Biomedical Informatics, Harvard University, Cambridge, MA 02115, USA
| | | | - Susan Smalley
- Net.bio Inc, Los Angeles, CA 90403, USA
- Department of Psychiatry and Biobehavioral Sciences, The University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Laura H. Goetz
- Department of Quantitative Medicine, The Translational Genomics Research Institute (TGen), 445 North Fifth Street, Phoenix, AZ 85004, USA
- Net.bio Inc, Los Angeles, CA 90403, USA
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Bronikowski AM, Meisel RP, Biga PR, Walters J, Mank JE, Larschan E, Wilkinson GS, Valenzuela N, Conard AM, de Magalhães JP, Duan J, Elias AE, Gamble T, Graze R, Gribble KE, Kreiling JA, Riddle NC. Sex-specific aging in animals: Perspective and future directions. Aging Cell 2022; 21:e13542. [PMID: 35072344 PMCID: PMC8844111 DOI: 10.1111/acel.13542] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/15/2021] [Accepted: 12/11/2021] [Indexed: 12/14/2022] Open
Abstract
Sex differences in aging occur in many animal species, and they include sex differences in lifespan, in the onset and progression of age-associated decline, and in physiological and molecular markers of aging. Sex differences in aging vary greatly across the animal kingdom. For example, there are species with longer-lived females, species where males live longer, and species lacking sex differences in lifespan. The underlying causes of sex differences in aging remain mostly unknown. Currently, we do not understand the molecular drivers of sex differences in aging, or whether they are related to the accepted hallmarks or pillars of aging or linked to other well-characterized processes. In particular, understanding the role of sex-determination mechanisms and sex differences in aging is relatively understudied. Here, we take a comparative, interdisciplinary approach to explore various hypotheses about how sex differences in aging arise. We discuss genomic, morphological, and environmental differences between the sexes and how these relate to sex differences in aging. Finally, we present some suggestions for future research in this area and provide recommendations for promising experimental designs.
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Affiliation(s)
- Anne M. Bronikowski
- Department of Ecology, Evolution, and Organismal BiologyIowa State UniversityAmesIowaUSA
| | - Richard P. Meisel
- Department of Biology and BiochemistryUniversity of HoustonHoustonTexasUSA
| | - Peggy R. Biga
- Department of BiologyThe University of Alabama at BirminghamBirminghamAlabamaUSA
| | - James R. Walters
- Department of Ecology and Evolutionary BiologyThe University of KansasLawrenceKansasUSA
| | - Judith E. Mank
- Department of ZoologyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Department of BioscienceUniversity of ExeterPenrynUK
| | - Erica Larschan
- Department of Molecular Biology, Cell Biology and BiochemistryBrown UniversityProvidenceRhode IslandUSA
| | | | - Nicole Valenzuela
- Department of Ecology, Evolution, and Organismal BiologyIowa State UniversityAmesIowaUSA
| | - Ashley Mae Conard
- Department of Computer ScienceCenter for Computational and Molecular BiologyBrown UniversityProvidenceRhode IslandUSA
| | - João Pedro de Magalhães
- Integrative Genomics of Ageing GroupInstitute of Ageing and Chronic DiseaseUniversity of LiverpoolLiverpoolUK
| | | | - Amy E. Elias
- Department of Molecular Biology, Cell Biology and BiochemistryBrown UniversityProvidenceRhode IslandUSA
| | - Tony Gamble
- Department of Biological SciencesMarquette UniversityMilwaukeeWisconsinUSA
- Milwaukee Public MuseumMilwaukeeWisconsinUSA
- Bell Museum of Natural HistoryUniversity of MinnesotaSaint PaulMinnesotaUSA
| | - Rita M. Graze
- Department of Biological SciencesAuburn UniversityAuburnAlabamaUSA
| | - Kristin E. Gribble
- Josephine Bay Paul Center for Comparative Molecular Biology and EvolutionMarine Biological LaboratoryWoods HoleMassachusettsUSA
| | - Jill A. Kreiling
- Department of Molecular Biology, Cell Biology and BiochemistryBrown UniversityProvidenceRhode IslandUSA
| | - Nicole C. Riddle
- Department of BiologyThe University of Alabama at BirminghamBirminghamAlabamaUSA
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58
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Cellular reprogramming and the rise of rejuvenation biotech. Trends Biotechnol 2022; 40:639-642. [DOI: 10.1016/j.tibtech.2022.01.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 11/22/2022]
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Gems D. The hyperfunction theory: An emerging paradigm for the biology of aging. Ageing Res Rev 2022; 74:101557. [PMID: 34990845 PMCID: PMC7612201 DOI: 10.1016/j.arr.2021.101557] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/24/2021] [Accepted: 12/30/2021] [Indexed: 12/13/2022]
Abstract
The process of senescence (aging) is predominantly determined by the action of wild-type genes. For most organisms, this does not reflect any adaptive function that senescence serves, but rather evolutionary effects of declining selection against genes with deleterious effects later in life. To understand aging requires an account of how evolutionary mechanisms give rise to pathogenic gene action and late-life disease, that integrates evolutionary (ultimate) and mechanistic (proximate) causes into a single explanation. A well-supported evolutionary explanation by G.C. Williams argues that senescence can evolve due to pleiotropic effects of alleles with antagonistic effects on fitness and late-life health (antagonistic pleiotropy, AP). What has remained unclear is how gene action gives rise to late-life disease pathophysiology. One ultimate-proximate account is T.B.L. Kirkwood's disposable soma theory. Based on the hypothesis that stochastic molecular damage causes senescence, this reasons that aging is coupled to reproductive fitness due to preferential investment of resources into reproduction, rather than somatic maintenance. An alternative and more recent ultimate-proximate theory argues that aging is largely caused by programmatic, developmental-type mechanisms. Here ideas about AP and programmatic aging are reviewed, particularly those of M.V. Blagosklonny (the hyperfunction theory) and J.P. de Magalhães (the developmental theory), and their capacity to make sense of diverse experimental findings is assessed.
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Affiliation(s)
- David Gems
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK.
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60
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Abstract
The classical evolutionary theories of aging suggest that aging evolves due to insufficient selective pressure against it. In these theories, declining selection pressure with age leads to aging through genes or resource allocations, implying that aging could potentially be stalled were genes, resource allocation, or selection pressure somewhat different. While these classical evolutionary theories are undeniably part of a description of the evolution of aging, they do not explain the diversity of aging patterns, and they do not constitute the only possible evolutionary explanation. Without denying selection pressure a role in the evolution of aging, we argue that the origin and diversity of aging should also be sought in the nature and evolution of organisms that are, from their very physiological make up, unmaintainable. Drawing on advances in developmental biology, genetics, biochemistry, and complex systems theory since the classical theories emerged, we propose a fresh evolutionary-mechanistic theory of aging, the Danaid theory. We argue that, in complex forms of life like humans, various restrictions on maintenance and repair may be inherent, and we show how such restrictions are laid out during development. We further argue that there is systematic variation in these constraints across taxa, and that this is a crucial factor determining variation in aging and lifespan across the tree of life. Accordingly, the core challenge for the field going forward is to map and understand the mosaic of constraints, trade-offs, chance events, and selective pressures that shape aging in diverse ways across diverse taxa.
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Affiliation(s)
- Maarten J Wensink
- Interdisciplinary Center on Population Dynamics, University of Southern Denmark, Odense, Denmark
| | - Alan A Cohen
- Department of Family Medicine, Research Centre on Aging, CHUS Research Centre, University of Sherbrooke, Sherbrooke, QC, Canada
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Hoffman JM, Hernandez CM, Hernandez AR, Bizon JL, Burke SN, Carter CS, Buford TW. Bridging the Gap: A Geroscience Primer for Neuroscientists With Potential Collaborative Applications. J Gerontol A Biol Sci Med Sci 2022; 77:e10-e18. [PMID: 34653247 PMCID: PMC8751800 DOI: 10.1093/gerona/glab314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Indexed: 11/13/2022] Open
Abstract
While neurodegenerative diseases can strike at any age, the majority of afflicted individuals are diagnosed at older ages. Due to the important impact of age in disease diagnosis, the field of neuroscience could greatly benefit from the many of the theories and ideas from the biology of aging-now commonly referred as geroscience. As discussed in our complementary perspective on the topic, there is often a "silo-ing" between geroscientists who work on understanding the mechanisms underlying aging and neuroscientists who are studying neurodegenerative diseases. While there have been some strong collaborations between the biology of aging and neuroscientists, there is still great potential for enhanced collaborative effort between the 2 fields. To this end, here, we review the state of the geroscience field, discuss how neuroscience could benefit from thinking from a geroscience perspective, and close with a brief discussion on some of the "missing links" between geroscience and neuroscience and how to remedy them. Notably, we have a corresponding, concurrent review from the neuroscience perspective. Our overall goal is to "bridge the gap" between geroscience and neuroscience such that more efficient, reproducible research with translational potential can be conducted.
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Affiliation(s)
- Jessica M Hoffman
- Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Caesar M Hernandez
- Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Abbi R Hernandez
- Department of Medicine, Division of Gerontology, Geriatrics and Palliative Care, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Bizon
- Department of Neuroscience and Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Sara N Burke
- Department of Neuroscience and Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Christy S Carter
- Department of Medicine, Division of Gerontology, Geriatrics and Palliative Care, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Nathan Shock Center for Excellence in the Basic Biology of Aging, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Thomas W Buford
- Department of Medicine, Division of Gerontology, Geriatrics and Palliative Care, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Geriatric Research Education and Clinical Center, Birmingham Veteran's Affairs Medical Center, Birmingham, Alabama, USA
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Ibañez-Solé O, Ascensión AM, Araúzo-Bravo MJ, Izeta A. Lack of evidence for increased transcriptional noise in aged tissues. eLife 2022; 11:80380. [PMID: 36576247 PMCID: PMC9934862 DOI: 10.7554/elife.80380] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
Aging is often associated with a loss of cell type identity that results in an increase in transcriptional noise in aged tissues. If this phenomenon reflects a fundamental property of aging remains an open question. Transcriptional changes at the cellular level are best detected by single-cell RNA sequencing (scRNAseq). However, the diverse computational methods used for the quantification of age-related loss of cellular identity have prevented reaching meaningful conclusions by direct comparison of existing scRNAseq datasets. To address these issues we created Decibel, a Python toolkit that implements side-to-side four commonly used methods for the quantification of age-related transcriptional noise in scRNAseq data. Additionally, we developed Scallop, a novel computational method for the quantification of membership of single cells to their assigned cell type cluster. Cells with a greater Scallop membership score are transcriptionally more stable. Application of these computational tools to seven aging datasets showed large variability between tissues and datasets, suggesting that increased transcriptional noise is not a universal hallmark of aging. To understand the source of apparent loss of cell type identity associated with aging, we analyzed cell type-specific changes in transcriptional noise and the changes in cell type composition of the mammalian lung. No robust pattern of cell type-specific transcriptional noise alteration was found across aging lung datasets. In contrast, age-associated changes in cell type composition of the lung were consistently found, particularly of immune cells. These results suggest that claims of increased transcriptional noise of aged tissues should be reformulated.
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Affiliation(s)
- Olga Ibañez-Solé
- Biodonostia Health Research Institute, Computational Biology and Systems Biomedicine GroupDonostia-San SebastiánSpain,Biodonostia Health Research Institute, Tissue Engineering groupDonostia-San SebastiánSpain
| | - Alex M Ascensión
- Biodonostia Health Research Institute, Computational Biology and Systems Biomedicine GroupDonostia-San SebastiánSpain,Biodonostia Health Research Institute, Tissue Engineering groupDonostia-San SebastiánSpain
| | - Marcos J Araúzo-Bravo
- Biodonostia Health Research Institute, Computational Biology and Systems Biomedicine GroupDonostia-San SebastiánSpain,Biodonostia Health Research Institute, Computational Biomedicine Data Analysis PlatformDonostia-San SebastiánSpain,CIBER of Frailty and Healthy Aging (CIBERfes)MadridSpain,IKERBASQUE, Basque Foundation for ScienceBilbaoSpain
| | - Ander Izeta
- Biodonostia Health Research Institute, Tissue Engineering groupDonostia-San SebastiánSpain,Tecnun-University of NavarraDonostia-San SebastiánSpain
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Douhard F, Douhard M, Gilbert H, Monget P, Gaillard J, Lemaître J. How much energetic trade-offs limit selection? Insights from livestock and related laboratory model species. Evol Appl 2021; 14:2726-2749. [PMID: 34950226 PMCID: PMC8674892 DOI: 10.1111/eva.13320] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/22/2021] [Accepted: 10/22/2021] [Indexed: 12/22/2022] Open
Abstract
Trade-offs between life history traits are expected to occur due to the limited amount of resources that organisms can obtain and share among biological functions, but are of least concern for selection responses in nutrient-rich or benign environments. In domestic animals, selection limits have not yet been reached despite strong selection for higher meat, milk or egg yields. Yet, negative genetic correlations between productivity traits and health or fertility traits have often been reported, supporting the view that trade-offs do occur in the context of nonlimiting resources. The importance of allocation mechanisms in limiting genetic changes can thus be questioned when animals are mostly constrained by their time to acquire and process energy rather than by feed availability. Selection for high productivity traits early in life should promote a fast metabolism with less energy allocated to self-maintenance (contributing to soma preservation and repair). Consequently, the capacity to breed shortly after an intensive period of production or to remain healthy should be compromised. We assessed those predictions in mammalian and avian livestock and related laboratory model species. First, we surveyed studies that compared energy allocation to maintenance between breeds or lines of contrasting productivity but found little support for the occurrence of an energy allocation trade-off. Second, selection experiments for lower feed intake per unit of product (i.e. higher feed efficiency) generally resulted in reduced allocation to maintenance, but this did not entail fitness costs in terms of survival or future reproduction. These findings indicate that the consequences of a particular selection in domestic animals are much more difficult to predict than one could anticipate from the energy allocation framework alone. Future developments to predict the contribution of time constraints and trade-offs to selection limits will be insightful to breed livestock in increasingly challenging environments.
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Affiliation(s)
| | - Mathieu Douhard
- Laboratoire de Biométrie & Biologie EvolutiveCNRSUMR 5558Université Lyon 1VilleurbanneFrance
| | - Hélène Gilbert
- GenPhySEINRAEENVTUniversité de ToulouseCastanet‐TolosanFrance
| | | | - Jean‐Michel Gaillard
- Laboratoire de Biométrie & Biologie EvolutiveCNRSUMR 5558Université Lyon 1VilleurbanneFrance
| | - Jean‐François Lemaître
- Laboratoire de Biométrie & Biologie EvolutiveCNRSUMR 5558Université Lyon 1VilleurbanneFrance
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Carlsson H, Ivimey-Cook E, Duxbury EML, Edden N, Sales K, Maklakov AA. Ageing as "early-life inertia": Disentangling life-history trade-offs along a lifetime of an individual. Evol Lett 2021; 5:551-564. [PMID: 34621540 PMCID: PMC8484722 DOI: 10.1002/evl3.254] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/19/2021] [Accepted: 08/13/2021] [Indexed: 11/10/2022] Open
Abstract
The theory that ageing evolves because of competitive resource allocation between the soma and the germline has been challenged by studies showing that somatic maintenance can be improved without impairing reproduction. However, it has been suggested that cost‐free improvement in somatic maintenance is possible only under a narrow range of benign conditions. Here, we show that experimental downregulation of insulin/IGF‐1 signaling (IIS) in C. elegans nematodes, a robustly reproducible life span‐ and health span‐extending treatment, reduces fitness in a complex variable environment when initiated during development but does not reduce fitness when initiated in adulthood. Thus, our results show that the costs and benefits of reduced IIS can be uncoupled when organisms inhabit variable environments, and, therefore, do not provide support for the resource allocation theory. Our findings support the theory that the force of natural selection on gene expression in evolutionarily conserved signaling pathways that shape life‐history traits declines after the onset of reproduction resulting in organismal senescence.
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Affiliation(s)
- Hanne Carlsson
- School of Biological Sciences University of East Anglia Norwich NR4 7TJ United Kingdom
| | - Edward Ivimey-Cook
- School of Biological Sciences University of East Anglia Norwich NR4 7TJ United Kingdom
| | - Elizabeth M L Duxbury
- School of Biological Sciences University of East Anglia Norwich NR4 7TJ United Kingdom
| | - Nathan Edden
- School of Biological Sciences University of East Anglia Norwich NR4 7TJ United Kingdom
| | - Kris Sales
- School of Biological Sciences University of East Anglia Norwich NR4 7TJ United Kingdom
| | - Alexei A Maklakov
- School of Biological Sciences University of East Anglia Norwich NR4 7TJ United Kingdom
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