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Alugoju P, Tencomnao T. Effect of levan polysaccharide on chronological aging in the yeast Saccharomyces cerevisiae. Int J Biol Macromol 2024; 266:131307. [PMID: 38574907 DOI: 10.1016/j.ijbiomac.2024.131307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 03/28/2024] [Accepted: 03/30/2024] [Indexed: 04/06/2024]
Abstract
Levan is a fructose-based biopolymer with diverse applications in the medicinal, pharmaceutical, and food industries. However, despite its extensive biological and pharmacological actions, including antioxidant, anti-inflammatory, and antidiabetic properties, research on its anti-aging potential is limited. This study explored levan's impact on the chronological lifespan (CLS) of yeast Saccharomyces cerevisiae for the first time. The results show that levan treatment significantly extended the CLS of wild-type (WT) yeast by preventing the accumulation of oxidative stress markers (reactive oxygen species, malondialdehyde, and protein carbonyl content) and ameliorating apoptotic features such as reduced mitochondrial membrane potential, loss of plasma membrane integrity, and externalization of phosphatidylserine. By day 40 of the CLS, a significant increase in yeast viability of 6.8 % (p < 0.01), 11.9 % (p < 0.01), and 20.8 % (p < 0.01) was observed at 0.25, 0.5, and 1 mg/mL of levan concentrations, respectively, compared to control (0 %). This study's results indicate that levan treatment substantially modulates the expression of genes involved in the TORC1/Sch9 pathway. Moreover, levan treatment significantly extended the CLS of yeast antioxidant-deficient mutant sod2Δ and antiapoptotic gene-deficient mutant pep4Δ. Levan also extended the CLS of signaling pathway gene-deficient mutants such as pkh2Δ, rim15Δ, atg1, and ras2Δ, while not affecting the CLS of tor1Δ and sch9Δ.
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Affiliation(s)
- Phaniendra Alugoju
- Natural Products for Neuroprotection and Anti-Ageing Research Unit, Chulalongkorn University, Bangkok 10330, Thailand; Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Tewin Tencomnao
- Natural Products for Neuroprotection and Anti-Ageing Research Unit, Chulalongkorn University, Bangkok 10330, Thailand; Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand.
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Stankova T, Piepkorn L, Bayer TA, Jahn O, Tirard M. SUMO1-conjugation is altered during normal aging but not by increased amyloid burden. Aging Cell 2018; 17:e12760. [PMID: 29633471 PMCID: PMC6052395 DOI: 10.1111/acel.12760] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2018] [Indexed: 01/09/2023] Open
Abstract
A proper equilibrium of post-translational protein modifications is essential for normal cell physiology, and alteration in these processes is key in neurodegenerative disorders such as Alzheimer's disease. Recently, for instance, alteration in protein SUMOylation has been linked to amyloid pathology. In this work, we aimed to elucidate the role of protein SUMOylation during aging and increased amyloid burden in vivo using a His6 -HA-SUMO1 knock-in mouse in the 5XFAD model of Alzheimer's disease. Interestingly, we did not observe any alteration in the levels of SUMO1-conjugation related to Alzheimer's disease. SUMO1 conjugates remained localized to neuronal nuclei upon increased amyloid burden and during aging and were not detected in amyloid plaques. Surprisingly however, we observed age-related alterations in global levels of SUMO1 conjugation and at the level of individual substrates using quantitative proteomic analysis. The identified SUMO1 candidate substrates are dominantly nuclear proteins, mainly involved in RNA processing. Our findings open novel directions of research for studying a functional link between SUMOylation and its role in guarding nuclear functions during aging.
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Affiliation(s)
- Trayana Stankova
- Department of Molecular Neurobiology; Max Planck Institute of Experimental Medicine; Göttingen Germany
| | - Lars Piepkorn
- Max Planck Institute of Experimental Medicine; Proteomics Group; Göttingen Germany
| | - Thomas A. Bayer
- Division of Molecular Psychiatry; Department of Psychiatry and Psychotherapy; University Medical Center Göttingen (UMG); Göttingen Germany
| | - Olaf Jahn
- Max Planck Institute of Experimental Medicine; Proteomics Group; Göttingen Germany
| | - Marilyn Tirard
- Department of Molecular Neurobiology; Max Planck Institute of Experimental Medicine; Göttingen Germany
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3
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Handee W, Li X, Hall KW, Deng X, Li P, Benning C, Williams BL, Kuo MH. An Energy-Independent Pro-longevity Function of Triacylglycerol in Yeast. PLoS Genet 2016; 12:e1005878. [PMID: 26907989 PMCID: PMC4764362 DOI: 10.1371/journal.pgen.1005878] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/27/2016] [Indexed: 01/09/2023] Open
Abstract
Intracellular triacylglycerol (TAG) is a ubiquitous energy storage lipid also involved in lipid homeostasis and signaling. Comparatively, little is known about TAG’s role in other cellular functions. Here we show a pro-longevity function of TAG in the budding yeast Saccharomyces cerevisiae. In yeast strains derived from natural and laboratory environments a correlation between high levels of TAG and longer chronological lifespan was observed. Increased TAG abundance through the deletion of TAG lipases prolonged chronological lifespan of laboratory strains, while diminishing TAG biosynthesis shortened lifespan without apparently affecting vegetative growth. TAG-mediated lifespan extension was independent of several other known stress response factors involved in chronological aging. Because both lifespan regulation and TAG metabolism are conserved, this cellular pro-longevity function of TAG may extend to other organisms. Triacylglycerol (TAG) is a ubiquitous lipid species well-known for its roles in storing surplus energy, providing insulation, and maintaining cellular lipid homeostasis. Here we present evidence for a novel pro-longevity function of TAG in the budding yeast, a model organism for aging research. Yeast cells that are genetically engineered to store more TAG live significantly longer without suffering obvious growth defects, whereas those lean cells that are depleted of TAG die early. Yeast strains isolated from the wild in general contain more fat and also display longer lifespan. One of the approaches taken here to force the increase of intracellular TAG is to delete lipases responsible for lipid hydrolysis. Energy extraction from TAG thus is unlikely an underlying cause of the observed lifespan extension. Our results are reminiscent of certain animal studies linking higher body fat to longer lifespan. Potential mechanisms for the connection of TAG and yeast lifespan regulation are discussed.
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Affiliation(s)
- Witawas Handee
- Department of Cell and Molecular Biology, Michigan State University. East Lansing, Michigan, United States of America
| | - Xiaobo Li
- DOE-Plant Research Laboratory, Michigan State University. East Lansing, Michigan, United States of America
- Department of Plant Biology, Michigan State University. East Lansing, Michigan, United States of America
| | - Kevin W. Hall
- Department of Integrative Biology, Michigan State University. East Lansing, Michigan, United States of America
| | - Xiexiong Deng
- Department of Biochemistry and Molecular Biology, Michigan State University. East Lansing, Michigan, United States of America
| | - Pan Li
- Department of Biochemistry and Molecular Biology, Michigan State University. East Lansing, Michigan, United States of America
| | - Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University. East Lansing, Michigan, United States of America
| | - Barry L. Williams
- Department of Integrative Biology, Michigan State University. East Lansing, Michigan, United States of America
| | - Min-Hao Kuo
- Department of Biochemistry and Molecular Biology, Michigan State University. East Lansing, Michigan, United States of America
- * E-mail:
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4
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Taormina G, Mirisola MG. Longevity: epigenetic and biomolecular aspects. Biomol Concepts 2016; 6:105-17. [PMID: 25883209 DOI: 10.1515/bmc-2014-0038] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 03/04/2015] [Indexed: 12/28/2022] Open
Abstract
Many aging theories and their related molecular mechanisms have been proposed. Simple model organisms such as yeasts, worms, fruit flies and others have massively contributed to their clarification, and many genes and pathways have been associated with longevity regulation. Among them, insulin/IGF-1 plays a key and evolutionary conserved role. Interestingly, dietary interventions can modulate this pathway. Calorie restriction (CR), intermittent fasting, and protein and amino acid restriction prolong the lifespan of mammals by IGF-1 regulation. However, some recent findings support the hypothesis that the long-term effects of diet also involve epigenetic mechanisms. In this review, we describe the best characterized aging pathways and highlight the role of epigenetics in diet-mediated longevity.
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Differential regulation of antagonistic pleiotropy in synthetic and natural populations suggests its role in adaptation. G3-GENES GENOMES GENETICS 2015; 5:699-709. [PMID: 25711830 PMCID: PMC4426359 DOI: 10.1534/g3.115.017020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Antagonistic pleiotropy (AP), the ability of a gene to show opposing effects in different phenotypes, has been identified in various life history traits and complex disorders, indicating its fundamental role in balancing fitness over the course of evolution. It is intuitive that natural selection might maintain AP to allow organisms phenotypic flexibility in different environments. However, despite several attempts, little evidence exists for its role in adaptation. We performed a meta-analysis in yeast to identify the genetic basis of AP in bi-parental segregants, natural isolates, and a laboratory strain genome-wide deletion collection, by comparing growth in favorable and stress conditions. We found that whereas AP was abundant in the synthetic populations, it was absent in the natural isolates. This finding indicated resolution of trade-offs, i.e., mitigation of trade-offs over evolutionary history, probably through accumulation of compensatory mutations. In the deletion collection, organizational genes showed AP, suggesting ancient resolutions of trade-offs in the basic cellular pathways. We find abundant AP in the segregants, greater than estimated in the deletion collection or observed in previous studies, with IRA2, a negative regulator of the Ras/PKA signaling pathway, showing trade-offs across diverse environments. Additionally, IRA2 and several other Ras/PKA pathway genes showed balancing selection in isolates of S. cerevisiae and S. paradoxus, indicating that multiple alleles maintain AP in this pathway in natural populations. We propose that during AP resolution, retaining the ability to vary signaling pathways such as Ras/PKA, may provide organisms with phenotypic flexibility. However, with increasing organismal complexity AP resolution may become difficult. A partial resolution of AP could manifest as complex human diseases, and the inability to resolve AP may play a role in speciation. Our findings suggest that testing a universal phenomenon like AP across multiple experimental systems may elucidate mechanisms underlying its regulation and evolution.
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Conserved mechanisms of tumorigenesis in the Drosophila adult midgut. PLoS One 2014; 9:e88413. [PMID: 24516653 PMCID: PMC3916428 DOI: 10.1371/journal.pone.0088413] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 01/06/2014] [Indexed: 11/19/2022] Open
Abstract
Whereas the series of genetic events leading to colorectal cancer (CRC) have been well established, the precise functions that these alterations play in tumor progression and how they disrupt intestinal homeostasis remain poorly characterized. Activation of the Wnt/Wg signaling pathway by a mutation in the gene APC is the most common trigger for CRC, inducing benign lesions that progress to carcinomas due to the accumulation of other genetic alterations. Among those, Ras mutations drive tumour progression in CRC, as well as in most epithelial cancers. As mammalian and Drosophila's intestines share many similarities, we decided to explore the alterations induced in the Drosophila midgut by the combined activation of the Wnt signaling pathway with gain of function of Ras signaling in the intestinal stem cells. Here we show that compound Apc-Ras clones, but not clones bearing the individual mutations, expand as aggressive intestinal tumor-like outgrowths. These lesions reproduce many of the human CRC hallmarks such as increased proliferation, blockade of cell differentiation and cell polarity and disrupted organ architecture. This process is followed by expression of tumoral markers present in human lesions. Finally, a metabolic behavioral assay shows that these flies suffer a progressive deterioration in intestinal homeostasis, providing a simple readout that could be used in screens for tumor modifiers or therapeutic compounds. Taken together, our results illustrate the conservation of the mechanisms of CRC tumorigenesis in Drosophila, providing an excellent model system to unravel the events that, upon mutation in Apc and Ras, lead to CRC initiation and progression.
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Pospelova TV, Bykova TV, Zubova SG, Katolikova NV, Yartzeva NM, Pospelov VA. Rapamycin induces pluripotent genes associated with avoidance of replicative senescence. Cell Cycle 2013; 12:3841-51. [PMID: 24296616 DOI: 10.4161/cc.27396] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Primary rodent cells undergo replicative senescence, independent from telomere shortening. We have recently shown that treatment with rapamycin during passages 3-7 suppressed replicative senescence in rat embryonic fibroblasts (REFs), which otherwise occurred by 10-14 passages. Here, we further investigated rapamycin-primed cells for an extended number of passages. Rapamycin-primed cells continued to proliferate without accumulation of senescent markers. Importantly, these cells retained the ability to undergo serum starvation- and etoposide-induced cell cycle arrest. The p53/p21 pathway was functional. This indicates that rapamycin did not cause either transformation or loss of cell cycle checkpoints. We found that rapamycin activated transcription of pluripotent genes, oct-4, sox-2, nanog, as well as further upregulated telomerase (tert) gene. The rapamycin-derived cells have mostly non-rearranged, near-normal karyotype. Still, when cultivated for a higher number of passages, these cells acquired a chromosomal marker within the chromosome 3. We conclude that suppression mTORC1 activity may prevent replicative senescence without transformation of rodent cells.
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Affiliation(s)
- Tatiana V Pospelova
- Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; St.Petersburg State University; St. Petersburg, Russia
| | - Tatiana V Bykova
- Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; St.Petersburg State University; St. Petersburg, Russia
| | - Svetlana G Zubova
- Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; St.Petersburg State University; St. Petersburg, Russia
| | | | - Natalia M Yartzeva
- Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia
| | - Valery A Pospelov
- Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; St.Petersburg State University; St. Petersburg, Russia
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Blagosklonny MV. Aging is not programmed: genetic pseudo-program is a shadow of developmental growth. Cell Cycle 2013; 12:3736-42. [PMID: 24240128 PMCID: PMC3905065 DOI: 10.4161/cc.27188] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Aging is not and cannot be programmed. Instead, aging is a continuation of developmental growth, driven by genetic pathways such as mTOR. Ironically, this is often misunderstood as a sort of programmed aging. In contrast, aging is a purposeless quasi-program or, figuratively, a shadow of actual programs. “The brightest flame casts the darkest shadow.” -George Martin
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Benisch P, Schilling T, Klein-Hitpass L, Frey SP, Seefried L, Raaijmakers N, Krug M, Regensburger M, Zeck S, Schinke T, Amling M, Ebert R, Jakob F. The transcriptional profile of mesenchymal stem cell populations in primary osteoporosis is distinct and shows overexpression of osteogenic inhibitors. PLoS One 2012; 7:e45142. [PMID: 23028809 PMCID: PMC3454401 DOI: 10.1371/journal.pone.0045142] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/13/2012] [Indexed: 12/11/2022] Open
Abstract
Primary osteoporosis is an age-related disease characterized by an imbalance in bone homeostasis. While the resorptive aspect of the disease has been studied intensely, less is known about the anabolic part of the syndrome or presumptive deficiencies in bone regeneration. Multipotent mesenchymal stem cells (MSC) are the primary source of osteogenic regeneration. In the present study we aimed to unravel whether MSC biology is directly involved in the pathophysiology of the disease and therefore performed microarray analyses of hMSC of elderly patients (79–94 years old) suffering from osteoporosis (hMSC-OP). In comparison to age-matched controls we detected profound changes in the transcriptome in hMSC-OP, e.g. enhanced mRNA expression of known osteoporosis-associated genes (LRP5, RUNX2, COL1A1) and of genes involved in osteoclastogenesis (CSF1, PTH1R), but most notably of genes coding for inhibitors of WNT and BMP signaling, such as Sclerostin and MAB21L2. These candidate genes indicate intrinsic deficiencies in self-renewal and differentiation potential in osteoporotic stem cells. We also compared both hMSC-OP and non-osteoporotic hMSC-old of elderly donors to hMSC of ∼30 years younger donors and found that the transcriptional changes acquired between the sixth and the ninth decade of life differed widely between osteoporotic and non-osteoporotic stem cells. In addition, we compared the osteoporotic transcriptome to long term-cultivated, senescent hMSC and detected some signs for pre-senescence in hMSC-OP. Our results suggest that in primary osteoporosis the transcriptomes of hMSC populations show distinct signatures and little overlap with non-osteoporotic aging, although we detected some hints for senescence-associated changes. While there are remarkable inter-individual variations as expected for polygenetic diseases, we could identify many susceptibility genes for osteoporosis known from genetic studies. We also found new candidates, e.g. MAB21L2, a novel repressor of BMP-induced transcription. Such transcriptional changes may reflect epigenetic changes, which are part of a specific osteoporosis-associated aging process.
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Affiliation(s)
- Peggy Benisch
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Tatjana Schilling
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Ludger Klein-Hitpass
- Institute of Cell Biology (Tumor Research), University Hospital Essen, Essen, Germany
| | - Sönke P. Frey
- Department of Trauma, Hand-, Plastic- and Reconstructive Surgery, University Hospital of Wuerzburg, Wuerzburg, Germany
| | - Lothar Seefried
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Nadja Raaijmakers
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Melanie Krug
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Martina Regensburger
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Sabine Zeck
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Regina Ebert
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
| | - Franz Jakob
- Orthopedic Center for Musculoskeletal Research, University of Wuerzburg, Wuerzburg, Germany
- * E-mail:
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Abstract
Ageing, also called as senescence, is one of the most complex, intrinsic, biological processes of growing older and resulting into reduced functional ability of the organism. Telomerase, environment, low calorie diets, free radicals, etc., are all believed to affect this ageing process. A number of genetic components of ageing have been identified using model organisms. Genes, mainly the sirtuins, regulate the ageing speed by indirection and controlling organism resistance to damages by exogenous and endogenous stresses. In higher organisms, ageing is likely to be regulated, in part, through the insulin/insulin-like growth factor 1 pathway. Besides this, the induction of apoptosis in stem and progenitor cells, increased p53 activity, and autophagy is also thought to trigger premature organismal ageing. Ageing has also been shown to upregulate expression of inflammatory mediators in mouse adipose tissue. The understanding of pathophysiology of ageing over the past few years has posed tremendous challenges for the development of anti-ageing medicine for targeted therapy. Future research areas must include targeted role of systemic inflammatory markers such as C-reactive protein and interleukin 6 and other biochemical and genetic studies including gene signaling pathways, gene microarray analysis, gene modulation, gene therapy, and development of animal/human models for potential therapeutic measures and evaluations.
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Affiliation(s)
- Anjana Nigam
- Department of Surgery, Pt. J. N. M. Medical College, Raipur, CG, India
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11
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Abstract
Lifespan prolongation is a common desire of the human race. With advances in biotechnology, the mechanism of aging has been gradually unraveled, laying the theoretical basis of nucleic acid therapy for lifespan prolongation. Regretfully, clinically applicable interventions do not exist without the efforts of converting theory into action, and it is the latter that has been far from adequately addressed at the moment. This was demonstrated by a database search on PubMed and Web of Science, from which only seven studies published between 2000 and 2010 were found to directly touch on the development of nucleic acid therapy for anti-aging and/or longevity enhancing purposes. In light of this, the objective of this article is to overview the current understanding of the intimate association between genes and longevity, and to bring the prospect of nucleic acid therapy for lifespan prolongation to light.
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Affiliation(s)
- Wing-Fu Lai
- Department of Chemistry, The University of Hong Kong, Hong Kong Special Administrative Region, China.
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12
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Aris JP, Fishwick LK, Marraffini ML, Seo AY, Leeuwenburgh C, Dunn WA. Amino acid homeostasis and chronological longevity in Saccharomyces cerevisiae. Subcell Biochem 2011; 57:161-86. [PMID: 22094422 DOI: 10.1007/978-94-007-2561-4_8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Understanding how non-dividing cells remain viable over long periods of time, which may be decades in humans, is of central importance in understanding mechanisms of aging and longevity. The long-term viability of non-dividing cells, known as chronological longevity, relies on cellular processes that degrade old components and replace them with new ones. Key among these processes is amino acid homeostasis. Amino acid homeostasis requires three principal functions: amino acid uptake, de novo synthesis, and recycling. Autophagy plays a key role in recycling amino acids and other metabolic building blocks, while at the same time removing damaged cellular components such as mitochondria and other organelles. Regulation of amino acid homeostasis and autophagy is accomplished by a complex web of pathways that interact because of the functional overlap at the level of recycling. It is becoming increasingly clear that amino acid homeostasis and autophagy play important roles in chronological longevity in yeast and higher organisms. Our goal in this chapter is to focus on mechanisms and pathways that link amino acid homeostasis, autophagy, and chronological longevity in yeast, and explore their relevance to aging and longevity in higher eukaryotes.
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Affiliation(s)
- John P Aris
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL, 32610-0235, USA,
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Fabrizio P, Hoon S, Shamalnasab M, Galbani A, Wei M, Giaever G, Nislow C, Longo VD. Genome-wide screen in Saccharomyces cerevisiae identifies vacuolar protein sorting, autophagy, biosynthetic, and tRNA methylation genes involved in life span regulation. PLoS Genet 2010; 6:e1001024. [PMID: 20657825 PMCID: PMC2904796 DOI: 10.1371/journal.pgen.1001024] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 06/14/2010] [Indexed: 11/18/2022] Open
Abstract
The study of the chronological life span of Saccharomyces cerevisiae, which measures the survival of populations of non-dividing yeast, has resulted in the identification of homologous genes and pathways that promote aging in organisms ranging from yeast to mammals. Using a competitive genome-wide approach, we performed a screen of a complete set of approximately 4,800 viable deletion mutants to identify genes that either increase or decrease chronological life span. Half of the putative short-/long-lived mutants retested from the primary screen were confirmed, demonstrating the utility of our approach. Deletion of genes involved in vacuolar protein sorting, autophagy, and mitochondrial function shortened life span, confirming that respiration and degradation processes are essential for long-term survival. Among the genes whose deletion significantly extended life span are ACB1, CKA2, and TRM9, implicated in fatty acid transport and biosynthesis, cell signaling, and tRNA methylation, respectively. Deletion of these genes conferred heat-shock resistance, supporting the link between life span extension and cellular protection observed in several model organisms. The high degree of conservation of these novel yeast longevity determinants in other species raises the possibility that their role in senescence might be conserved.
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Affiliation(s)
- Paola Fabrizio
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
- Laboratoire de Biologie Moléculaire de la Cellule, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université de Lyon, Lyon, France
| | - Shawn Hoon
- Department of Genetics, Stanford University, Palo Alto, California, United States of America
| | - Mehrnaz Shamalnasab
- Laboratoire de Biologie Moléculaire de la Cellule, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université de Lyon, Lyon, France
| | - Abdulaye Galbani
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Min Wei
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Guri Giaever
- Department of Genetics, Stanford University, Palo Alto, California, United States of America
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Corey Nislow
- Department of Genetics, Stanford University, Palo Alto, California, United States of America
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (VDL); (CN)
| | - Valter D. Longo
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
- * E-mail: (VDL); (CN)
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14
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Parrella E, Longo VD. Insulin/IGF-I and related signaling pathways regulate aging in nondividing cells: from yeast to the mammalian brain. ScientificWorldJournal 2010; 10:161-77. [PMID: 20098959 PMCID: PMC4405166 DOI: 10.1100/tsw.2010.8] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Mutations that reduce glucose or insulin/insulin-like growth factor-I (IGF-I) signaling increase longevity in organisms ranging from yeast to mammals. Over the past 10 years, several studies confirmed this conserved molecular strategy of longevity regulation, and many more have been added to the complex mosaic that links stress resistance and aging. In this review, we will analyze the similarities that have emerged over the last decade between longevity regulatory pathways in organisms ranging from yeast, nematodes, and fruit flies to mice. We will focus on the role of yeast signal transduction proteins Ras, Tor, Sch9, Sir2, their homologs in higher organisms, and their association to oxidative stress and protective systems. We will discuss how the “molecular strategy” responsible for life span extension in response to dietary and genetic manipulations appears to be remarkably conserved in various organisms and cells, including neuronal cells in different organisms. Taken together, these studies indicate that simple model systems will contribute to our comprehension of aging of the mammalian nervous system and will stimulate novel neurotherapeutic strategies in humans.
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Affiliation(s)
- Edoardo Parrella
- Division of Neurogerontology Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.
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15
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Aamodt RM. Age-and caste-dependent decrease in expression of genes maintaining DNA and RNA quality and mitochondrial integrity in the honeybee wing muscle. Exp Gerontol 2009; 44:586-93. [PMID: 19563879 DOI: 10.1016/j.exger.2009.06.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 06/07/2009] [Accepted: 06/18/2009] [Indexed: 11/26/2022]
Abstract
I report here an investigation of the age- and caste-specific expression patterns of nine honeybee orthologs of genes involved in repair of oxidative and methylation damage of DNA, and possibly RNA, in wing muscle tissue of the honeybee Apis mellifera. mRNA expression levels were measured in a comparative study of queens and ageing workers. Two of these genes, both potentially involved in repair and prevention of oxidative damage, showed higher expression in queens than workers and a distinct downregulation during the ageing trajectory in workers. These were an ortholog of mammalian NTH1 and a gene encoding a fusion protein which seems to be unique for the honeybee, consisting of one domain homologous to mammalian MTH1/Nudix/bacterial mutT and another domain homologous to the mitochondrial ribosomal protein gene S23. Orthologs of aag, apn1, msh6, ogg1, smug1 and two orthologs of human ABH/E. coli alkB, had stable expression levels during the ageing trajectory except high apn1 levels in overwintering workers. To estimate eventual age-dependent mitochondrial maintenance, batches of mitochondrial DNA from young and old workers and young queens were re-sequenced using Solexa/Illumina high-throughput sequencing. The results indicate at least a 50% reduction of intact mitochondrial fragments in foragers compared to young workers, winter bees and queens.
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Affiliation(s)
- Randi M Aamodt
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway.
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16
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Wei M, Fabrizio P, Madia F, Hu J, Ge H, Li LM, Longo VD. Tor1/Sch9-regulated carbon source substitution is as effective as calorie restriction in life span extension. PLoS Genet 2009; 5:e1000467. [PMID: 19424415 PMCID: PMC2669710 DOI: 10.1371/journal.pgen.1000467] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 04/06/2009] [Indexed: 11/19/2022] Open
Abstract
The effect of calorie restriction (CR) on life span extension, demonstrated in organisms ranging from yeast to mice, may involve the down-regulation of pathways, including Tor, Akt, and Ras. Here, we present data suggesting that yeast Tor1 and Sch9 (a homolog of the mammalian kinases Akt and S6K) is a central component of a network that controls a common set of genes implicated in a metabolic switch from the TCA cycle and respiration to glycolysis and glycerol biosynthesis. During chronological survival, mutants lacking SCH9 depleted extracellular ethanol and reduced stored lipids, but synthesized and released glycerol. Deletion of the glycerol biosynthesis genes GPD1, GPD2, or RHR2, among the most up-regulated in long-lived sch9Delta, tor1Delta, and ras2Delta mutants, was sufficient to reverse chronological life span extension in sch9Delta mutants, suggesting that glycerol production, in addition to the regulation of stress resistance systems, optimizes life span extension. Glycerol, unlike glucose or ethanol, did not adversely affect the life span extension induced by calorie restriction or starvation, suggesting that carbon source substitution may represent an alternative to calorie restriction as a strategy to delay aging.
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Affiliation(s)
- Min Wei
- Andrus Gerontology Center, University of Southern California, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Paola Fabrizio
- Andrus Gerontology Center, University of Southern California, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Federica Madia
- Andrus Gerontology Center, University of Southern California, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Jia Hu
- Andrus Gerontology Center, University of Southern California, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Huanying Ge
- Department of Molecular and Computational Biology, University of Southern California, Los Angeles, California, United States of America
| | - Lei M. Li
- Department of Molecular and Computational Biology, University of Southern California, Los Angeles, California, United States of America
| | - Valter D. Longo
- Andrus Gerontology Center, University of Southern California, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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17
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Shen J, Curtis C, Tavaré S, Tower J. A screen of apoptosis and senescence regulatory genes for life span effects when over-expressed in Drosophila. Aging (Albany NY) 2009; 1:191-211. [PMID: 20157509 PMCID: PMC2806004 DOI: 10.18632/aging.100018] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Accepted: 01/29/2009] [Indexed: 12/01/2022]
Abstract
Conditional expression of
transgenes in Drosophila was produced using the Geneswitch system,
wherein feeding the drug RU486/Mifepristone activates the artificial
transcription factor Geneswitch. Geneswitch was expressed using the Actin5C
promoter and this was found to yield conditional, tissue-general expression
of a target transgene (UAS-GFP) in both larvae and adult flies. Nervous
system-specific (Elav-GS) and fat body-specific Geneswitch drivers were
also characterized using UAS-GFP. Fourteen genes implicated in growth,
apoptosis and senescence regulatory pathways were over-expressed in adult
flies or during larval development, and assayed for effects on adult fly
life span. Over-expression of a dominant p53 allele (p53-259H)
in adult flies using the ubiquitous driver produced increased life span in
females but not males, consistent with previous studies. Both wingless
and Ras activated form transgenes were lethal when expressed in
larvae, and reduced life span when expressed in adults, consistent with
results from other model systems indicating that the wingless and Ras
pathways can promote senescence. Over-expression of the caspase inhibitor baculovirus
p35 during larval development reduced the mean life span of male and
female adults, and also produced a subset of females with increased life
span. These experiments suggest that baculovirus p35 and the wingless
and Ras pathways can have sex-specific and developmental
stage-specific effects on adult Drosophila life span, and these
reagents should be useful for the further analysis of the role of these
conserved pathways in aging.
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Affiliation(s)
- Jie Shen
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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18
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Smith DL, McClure JM, Matecic M, Smith JS. Calorie restriction extends the chronological lifespan of Saccharomyces cerevisiae independently of the Sirtuins. Aging Cell 2007; 6:649-62. [PMID: 17711561 DOI: 10.1111/j.1474-9726.2007.00326.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Calorie restriction (CR) extends the mean and maximum lifespan of a wide variety of organisms ranging from yeast to mammals, although the molecular mechanisms of action remain unclear. For the budding yeast Saccharomyces cerevisiae reducing glucose in the growth medium extends both the replicative and chronological lifespans (CLS). The conserved NAD(+)-dependent histone deacetylase, Sir2p, promotes replicative longevity in S. cerevisiae by suppressing recombination within the ribosomal DNA locus and has been proposed to mediate the effects of CR on aging. In this study, we investigated the functional relationships of the yeast Sirtuins (Sir2p, Hst1p, Hst2p, Hst3p and Hst4p) with CLS and CR. SIR2, HST2, and HST4 were not major regulators of CLS and were not required for the lifespan extension caused by shifting the glucose concentration from 2 to 0.5% (CR). Deleting HST1 or HST3 moderately shortened CLS, but did not prevent CR from extending lifespan. CR therefore works through a Sirtuin-independent mechanism in the chronological aging system. We also show that low temperature or high osmolarity additively extends CLS when combined with CR, suggesting that these stresses and CR act through separate pathways. The CR effect on CLS was not specific to glucose. Restricting other simple sugars such as galactose or fructose also extended lifespan. Importantly, growth on nonfermentable carbon sources that force yeast to exclusively utilize respiration extended lifespan at nonrestricted concentrations and provided no additional benefit when restricted, suggesting that elevated respiration capacity is an important determinant of chronological longevity.
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Affiliation(s)
- Daniel L Smith
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, School of Medicine, Charlottesville, VA 22908, USA
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19
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Abstract
Initial observations that the budding yeast Saccharomyces cerevisiae can be induced to undergo a form of cell death exhibiting typical markers of apoptosis has led to the emergence of a thriving new field of research. Since this discovery, a number of conserved pro- and antiapoptotic proteins have been identified in yeast. Indeed, early experiments have successfully validated yeasts as a powerful genetic tool with which to investigate mechanisms of apoptosis. However, we still have little understanding as to why programmes of cell suicide exist in unicellular organisms and how they may be benefit such organisms. Recent research has begun to elucidate pathways that regulate yeast apoptosis in response to environmental stimuli. These reports strengthen the idea that physiologically relevant mechanisms of programmed cell death are present, and that these function as important regulators of yeast cell populations.
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Affiliation(s)
- Campbell W Gourlay
- Department of Molecular Biology and Biotechnology, Firth Court, Western Bank, University of Sheffield, Sheffield S10 2TN, UK
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20
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Fernández-Arenas E, Cabezón V, Bermejo C, Arroyo J, Nombela C, Diez-Orejas R, Gil C. Integrated Proteomics and Genomics Strategies Bring New Insight into Candida albicans Response upon Macrophage Interaction. Mol Cell Proteomics 2007; 6:460-78. [PMID: 17164403 DOI: 10.1074/mcp.m600210-mcp200] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The interaction of Candida albicans with macrophages is considered a crucial step in the development of an adequate immune response in systemic candidiasis. An in vitro model of phagocytosis that includes a differential staining procedure to discriminate between internalized and non-internalized yeast was developed. Upon optimization of a protocol to obtain an enriched population of ingested yeasts, a thorough genomics and proteomics analysis was carried out on these cells. Both proteins and mRNA were obtained from the same sample and analyzed in parallel. The combination of two-dimensional PAGE with MS revealed a total of 132 differentially expressed yeast protein species upon macrophage interaction. Among these species, 67 unique proteins were identified. This is the first time that a proteomics approach has been used to study C. albicans-macrophage interaction. We provide evidence of a rapid protein response of the fungus to adapt to the new environment inside the phagosome by changing the expression of proteins belonging to different pathways. The clear down-regulation of the carbon-compound metabolism, plus the up-regulation of lipid, fatty acid, glyoxylate, and tricarboxylic acid cycles, indicates that yeast shifts to a starvation mode. There is an important activation of the degradation and detoxification protein machinery. The complementary genomics approach led to the detection of specific pathways related to the virulence of Candida. Network analyses allowed us to generate a hypothetical model of Candida cell death after macrophage interaction, highlighting the interconnection between actin cytoskeleton, mitochondria, and autophagy in the regulation of apoptosis. In conclusion, the combination of genomics, proteomics, and network analyses is a powerful strategy to better understand the complex host-pathogen interactions.
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Affiliation(s)
- Elena Fernández-Arenas
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain
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21
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Chiocchetti A, Zhou J, Zhu H, Karl T, Haubenreisser O, Rinnerthaler M, Heeren G, Oender K, Bauer J, Hintner H, Breitenbach M, Breitenbach-Koller L. Ribosomal proteins Rpl10 and Rps6 are potent regulators of yeast replicative life span. Exp Gerontol 2006; 42:275-86. [PMID: 17174052 DOI: 10.1016/j.exger.2006.11.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 10/27/2006] [Accepted: 11/07/2006] [Indexed: 11/17/2022]
Abstract
The yeast ribosome is composed of two subunits, the large 60S subunit (LSU) and the small 40S subunit (SSU) and harbors 78 ribosomal proteins (RPs), 59 of which are encoded by duplicate genes. Recently, deletions of the LSU paralogs RPL31A and RPL6B were found to increase significantly yeast replicative life span (RLS). RPs Rpl10 and Rps6 are known translational regulators. Here, we report that heterozygosity for rpl10Delta but not for rpl25Delta, both LSU single copy RP genes, increased RLS by 24%. Deletion of the SSU RPS6B paralog, but not of the RPS6A paralog increased replicative life span robustly by 45%, while deletion of both the SSU RPS18A, and RPS18B paralogs increased RLS moderately, but significantly by 15%. Altering the gene dosage of RPL10 reduced the translating ribosome population, whereas deletion of the RPS6A, RPS6B, RPS18A, and RPS18B paralogs produced a large shift in free ribosomal subunit stoichiometry. We observed a reduction in growth rate in all deletion strains and reduced cell size in the SSU RPS6B, RPS6A, and RPS18B deletion strains. Thus, reduction of gene dosage of RP genes belonging to both the 60S and the 40S subunit affect lifespan, possibly altering the aging process by modulation of translation.
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Affiliation(s)
- Andreas Chiocchetti
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
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22
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Gourlay CW, Ayscough KR. Actin-induced hyperactivation of the Ras signaling pathway leads to apoptosis in Saccharomyces cerevisiae. Mol Cell Biol 2006; 26:6487-501. [PMID: 16914733 PMCID: PMC1592845 DOI: 10.1128/mcb.00117-06] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent research has revealed a conserved role for the actin cytoskeleton in the regulation of aging and apoptosis among eukaryotes. Here we show that the stabilization of the actin cytoskeleton caused by deletion of Sla1p or End3p leads to hyperactivation of the Ras signaling pathway. The consequent rise in cyclic AMP (cAMP) levels leads to the loss of mitochondrial membrane potential, accumulation of reactive oxygen species (ROS), and cell death. We have established a mechanistic link between Ras signaling and actin by demonstrating that ROS production in actin-stabilized cells is dependent on the G-actin binding region of the cyclase-associated protein Srv2p/CAP. Furthermore, the artificial elevation of cAMP directly mimics the apoptotic phenotypes displayed by actin-stabilized cells. The effect of cAMP elevation in inducing actin-mediated apoptosis functions primarily through the Tpk3p subunit of protein kinase A. This pathway represents the first defined link between environmental sensing, actin remodeling, and apoptosis in Saccharomyces cerevisiae.
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Affiliation(s)
- C W Gourlay
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom.
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23
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Boldogh IR, Pon LA. Interactions of mitochondria with the actin cytoskeleton. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:450-62. [PMID: 16624426 DOI: 10.1016/j.bbamcr.2006.02.014] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 02/19/2006] [Accepted: 02/23/2006] [Indexed: 11/26/2022]
Abstract
Interactions between mitochondria and the cytoskeleton are essential for normal mitochondrial morphology, motility and distribution. While microtubules and their motors have been established as important factors for mitochondrial transport, emerging evidence indicates that mitochondria interact with the actin cytoskeleton in many cell types. In certain fungi, such as the budding yeast and Aspergillus, or in plant cells mitochondrial motility is largely actin-based. Even in systems such as neurons, where microtubules are the primary means of long-distance mitochondrial transport, the actin cytoskeleton is required for short-distance mitochondrial movements and for immobilization of the organelle at the cell cortex. The actin cytoskeleton is also involved in the immobilization of mitochondria at the cortex in cultured tobacco cells and in budding yeast. While the exact nature of these immobilizations is not known, they may be important for retaining mitochondria at sites of high ATP utilization or at other cellular locations where they are needed. Recent findings also indicate that mutations in actin or actin-binding proteins can influence mitochondrial pathways leading to cell death. Thus, mitochondria-actin interactions contribute to apoptosis.
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Affiliation(s)
- Istvan R Boldogh
- Department of Anatomy and Cell Biology, Columbia University College of Physicians and Surgeons, 12-425, 630 West 168th Street, New York, NY 10032, USA
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24
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Powers RW, Kaeberlein M, Caldwell SD, Kennedy BK, Fields S. Extension of chronological life span in yeast by decreased TOR pathway signaling. Genes Dev 2006; 20:174-84. [PMID: 16418483 PMCID: PMC1356109 DOI: 10.1101/gad.1381406] [Citation(s) in RCA: 704] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Chronological life span (CLS) in Saccharomyces cerevisiae, defined as the time cells in a stationary phase culture remain viable, has been proposed as a model for the aging of post-mitotic tissues in mammals. We developed a high-throughput assay to determine CLS for approximately 4800 single-gene deletion strains of yeast, and identified long-lived strains carrying mutations in the conserved TOR pathway. TOR signaling regulates multiple cellular processes in response to nutrients, especially amino acids, raising the possibility that decreased TOR signaling mediates life span extension by calorie restriction. In support of this possibility, removal of either asparagine or glutamate from the media significantly increased stationary phase survival. Pharmacological inhibition of TOR signaling by methionine sulfoximine or rapamycin also increased CLS. Decreased TOR activity also promoted increased accumulation of storage carbohydrates and enhanced stress resistance and nuclear relocalization of the stress-related transcription factor Msn2. We propose that up-regulation of a highly conserved response to starvation-induced stress is important for life span extension by decreased TOR signaling in yeast and higher eukaryotes.
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Affiliation(s)
- R Wilson Powers
- Department of Genome Sciences and Medicine, The Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
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25
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Nanji M, Hopper NA, Gems D. LET-60 RAS modulates effects of insulin/IGF-1 signaling on development and aging in Caenorhabditis elegans. Aging Cell 2005; 4:235-45. [PMID: 16164423 DOI: 10.1111/j.1474-9726.2005.00166.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The DAF-2 insulin/insulin-like growth factor 1 (IGF-1) receptor signals via a phosphatidylinositol 3-kinase (PI3K) pathway to control dauer larva formation and adult longevity in Caenorhabditis elegans. Yet epistasis analysis suggests signal bifurcation downstream of DAF-2. We have used epistasis analysis to test whether the Ras pathway (which plays a role in signaling from mammalian insulin receptors) acts downstream of DAF-2. We find that an activated Ras mutation, let-60(n1046gf), weakly suppresses constitutive dauer diapause in daf-2 and age-1 (PI3K) mutants. Moreover, increased Ras pathway signaling partially suppresses the daf-2 mutant feeding defect, while reduced Ras pathway signaling enhances it. By contrast, activated Ras extends the longevity induced by mutation of daf-2, while reduced Ras pathway signaling partially suppresses it. Thus, Ras pathway signaling appears to act with insulin/IGF-1 signaling during larval development, but against it during aging.
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Affiliation(s)
- Manoj Nanji
- Department of Biology, University College London, London WC1E 6BT, UK
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26
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Abstract
As the population of industrial nations ages, the incidence of cancer and cancer mortality is increasing. Intuitively, older organisms may be less able to cope with accumulated damage and thus be more prone to develop cancer. However, so far, the links between aging and cancer have been only partially explored. Strikingly, four recent studies now indicate that premature senescence accompanied by cell cycle arrest occurs in tumors initiated by an oncogenic mutation. Thus, senescence may act as a key tumor suppressor mechanism in young tumors in vivo.
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Affiliation(s)
- Julien Sage
- Stanford University School of Medicine, CA 94305, USA.
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