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Turnell BR, Reinhardt K. Metabolic Rate and Oxygen Radical Levels Increase But Radical Generation Rate Decreases with Male Age in Drosophila melanogaster Sperm. J Gerontol A Biol Sci Med Sci 2020; 75:2278-2285. [DOI: 10.1093/gerona/glaa078] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Indexed: 01/17/2023] Open
Abstract
Abstract
Oxidative damage increases with age in a variety of cell types, including sperm, which are particularly susceptible to attack by reactive oxygen species (ROS). While mitochondrial respiration is the main source of cellular ROS, the relationship between the rates of aerobic metabolism and ROS production, and how this relationship may be affected by age, both in sperm and in other cell types, is unclear. Here, we investigate in Drosophila melanogaster sperm, the effects of male age on (i) the level of hydrogen peroxide in the mitochondria, using a transgenic H2O2 reporter line; (ii) the in situ rate of non-H2O2 ROS production, using a novel biophysical method; and (iii) metabolic rate, using fluorescent lifetime imaging microscopy. Sperm from older males had higher mitochondrial ROS levels and a higher metabolic rate but produced ROS at a lower rate. In comparison, a somatic tissue, the gut epithelium, also showed an age-related increase in mitochondrial ROS levels but a decrease in metabolic rate. These results support the idea of a tissue-specific optimal rate of aerobic respiration balancing the production and removal of ROS, with aging causing a shift away from this optimum and leading to increased ROS accumulation. Our findings also support the view that pathways of germline and somatic aging can be uncoupled, which may have implications for male infertility treatments.
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Affiliation(s)
- Biz R Turnell
- Applied Zoology, Faculty Biology, Technische Universität Dresden, Germany
| | - Klaus Reinhardt
- Applied Zoology, Faculty Biology, Technische Universität Dresden, Germany
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Xu W, Jia H, Zhang L, Wang H, Tang H, Zhang L. Effects of GSH1 and GSH2 Gene Mutation on Glutathione Synthetases Activity of Saccharomyces cerevisiae. Protein J 2017; 36:270-277. [PMID: 28669025 DOI: 10.1007/s10930-017-9731-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In this paper, three mutants from wild Saccharomyces cerevisiae HBU2.558, called U2.558, UN2.558, and UNA2.558, were screened by UV, sodium nitrite, Atmospheric and room temperature plasma, respectively. Glutathione production of the three mutants increased by 41.86, 72.09 and 56.76%, respectively. We detected the activity of glutathione synthetases and found that its activity was improved. Amino acid sequences of three mutant colonies were compared with HBU2.558. Four mutants: Leu51→Pro51 (L51P), Glu62→Val62 (E62V), Ala332→Glu332 (A332E) and Ser653→Gly653 (S653G) were found in the analysis of γ-glutamylcysteine ligase. L51 is located adjacently to the two active sites of GCL/E/Mg2+/ADP complex in the overall GCL structure. L51P mutant spread distortion on the β-sheet due to the fact that the φ was changed from -50.4° to -40.2°. A mutant Leu54→Pro54 (L54P) was found in the analysis of glutathione synthetase, and L54 was an amino acid located between an α-helix and a β-sheet. The results confirm that introduction of proline located at the middle of the β-sheet or at the N- or C-terminal between α-helix and β-sheet or, i.e., L51P and L54P, changed the φ, rigidity, hydrophobicity and conformational entropy, thus increased protein stability and improved the enzyme activity.
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Affiliation(s)
- Wen Xu
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province, Key Laboratory of Microbial Diversity Research and Application of Hebei Province, Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding, 071002, China
| | - Haiyan Jia
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province, Key Laboratory of Microbial Diversity Research and Application of Hebei Province, Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding, 071002, China
| | - Longmei Zhang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province, Key Laboratory of Microbial Diversity Research and Application of Hebei Province, Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding, 071002, China
| | - Haiyan Wang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province, Key Laboratory of Microbial Diversity Research and Application of Hebei Province, Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding, 071002, China
| | - Hui Tang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province, Key Laboratory of Microbial Diversity Research and Application of Hebei Province, Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding, 071002, China
| | - Liping Zhang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province, Key Laboratory of Microbial Diversity Research and Application of Hebei Province, Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding, 071002, China.
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3
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Moskalev A, Shaposhnikov M, Proshkina E, Belyi A, Fedintsev A, Zhikrivetskaya S, Guvatova Z, Sadritdinova A, Snezhkina A, Krasnov G, Kudryavtseva A. The influence of pro-longevity gene Gclc overexpression on the age-dependent changes in Drosophila transcriptome and biological functions. BMC Genomics 2016; 17:1046. [PMID: 28105938 PMCID: PMC5249042 DOI: 10.1186/s12864-016-3356-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background Transcriptional changes that contribute to the organism’s longevity and prevent the age-dependent decline of biological functions are not well understood. Here, we overexpressed pro-longevity gene encoding glutamate-cysteine ligase catalytic subunit (Gclc) and analyzed age-dependent changes in transcriptome that associated with the longevity, stress resistance, locomotor activity, circadian rhythmicity, and fertility. Results Here we reproduced the life extension effect of neuronal overexpression of the Gclc gene and investigated its influence on the age-depended dynamics of transcriptome and biological functions such as fecundity, spontaneous locomotor activity and circadian rhythmicity, as well as on the resistance to oxidative, proteotoxic and osmotic stresses. It was shown that Gclc overexpression reduces locomotor activity in the young and middle ages compared to control flies. Gclc overexpression slowed down the age-dependent decline of locomotor activity and circadian rhythmicity, and resistance to stress treatments. Gclc level demonstrated associations with the expression of genes involved in a variety of cellular processes including Jak-STAT, MAPK, FOXO, Notch, mTOR, TGF-beta signaling pathways, translation, protein processing in endoplasmic reticulum, proteasomal degradation, glycolysis, oxidative phosphorylation, apoptosis, regulation of circadian rhythms, differentiation of neurons, synaptic plasticity and transmission. Conclusions Our study revealed that Gclc overexpression induces transcriptional changes associated with the lifespan extension and uncovered pathways that may be associated with the age-dependent decline of biological functions. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3356-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexey Moskalev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia. .,Institute of Biology of Komi Science Center of Ural Branch of RAS, Syktyvkar, Russia. .,Moscow Institute of Physics and Technology, Dolgoprudny, Russia. .,Syktyvkar State University, Syktyvkar, Russia.
| | - Mikhail Shaposhnikov
- Institute of Biology of Komi Science Center of Ural Branch of RAS, Syktyvkar, Russia.,Syktyvkar State University, Syktyvkar, Russia
| | - Ekaterina Proshkina
- Institute of Biology of Komi Science Center of Ural Branch of RAS, Syktyvkar, Russia.,Syktyvkar State University, Syktyvkar, Russia
| | - Alexey Belyi
- Institute of Biology of Komi Science Center of Ural Branch of RAS, Syktyvkar, Russia.,Syktyvkar State University, Syktyvkar, Russia
| | | | | | - Zulfiya Guvatova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Asiya Sadritdinova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anastasia Snezhkina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - George Krasnov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anna Kudryavtseva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia.
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Zhang H, Davies KJA, Forman HJ. Oxidative stress response and Nrf2 signaling in aging. Free Radic Biol Med 2015; 88:314-336. [PMID: 26066302 PMCID: PMC4628850 DOI: 10.1016/j.freeradbiomed.2015.05.036] [Citation(s) in RCA: 570] [Impact Index Per Article: 63.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/29/2015] [Accepted: 05/31/2015] [Indexed: 12/20/2022]
Abstract
Increasing oxidative stress, a major characteristic of aging, has been implicated in a variety of age-related pathologies. In aging, oxidant production from several sources is increased, whereas antioxidant enzymes, the primary lines of defense, are decreased. Repair systems, including the proteasomal degradation of damaged proteins, also decline. Importantly, the adaptive response to oxidative stress declines with aging. Nrf2/EpRE signaling regulates the basal and inducible expression of many antioxidant enzymes and the proteasome. Nrf2/EpRE activity is regulated at several levels, including transcription, posttranslation, and interactions with other proteins. This review summarizes current studies on age-related impairment of Nrf2/EpRE function and discusses the changes in Nrf2 regulatory mechanisms with aging.
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Affiliation(s)
- Hongqiao Zhang
- Ethel Percy Andrus Gerontology Center, Leonard Davis School of Gerontology
| | - Kelvin J A Davies
- Ethel Percy Andrus Gerontology Center, Leonard Davis School of Gerontology; Division of Molecular & Computational Biology, Department of Biological Sciences, Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, CA 90089-0191, USA
| | - Henry Jay Forman
- Ethel Percy Andrus Gerontology Center, Leonard Davis School of Gerontology; School of Natural Science, University of California at Merced, Merced, CA 95344, USA.
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Klichko VI, Chow ES, Kotwica-Rolinska J, Orr WC, Giebultowicz JM, Radyuk SN. Aging alters circadian regulation of redox in Drosophila. Front Genet 2015; 6:83. [PMID: 25806044 PMCID: PMC4353305 DOI: 10.3389/fgene.2015.00083] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 02/17/2015] [Indexed: 12/27/2022] Open
Abstract
Circadian coordination of metabolism, physiology, and neural functions contributes to healthy aging and disease prevention. Clock genes govern the daily rhythmic expression of target genes whose activities underlie such broad physiological parameters as maintenance of redox homeostasis. Previously, we reported that glutathione (GSH) biosynthesis is controlled by the circadian system via effects of the clock genes on expression of the catalytic (Gclc) and modulatory (Gclm) subunits comprising the glutamate cysteine ligase (GCL) holoenzyme. The objective of this study was to determine whether and how aging, which leads to weakened circadian oscillations, affects the daily profiles of redox-active biomolecules. We found that fly aging is associated with altered profiles of Gclc and Gclm expression at both the mRNA and protein levels. Analysis of free aminothiols and GCL activity revealed that aging abolishes daily oscillations in GSH levels and alters the activity of glutathione biosynthetic pathways. Unlike GSH, its precursors and products of catabolism, methionine, cysteine and cysteinyl-glycine, were not rhythmic in young or old flies, while rhythms of the glutathione oxidation product, GSSG, were detectable. We conclude that the temporal regulation of GSH biosynthesis is altered in the aging organism and that age-related loss of circadian modulation of pathways involved in glutathione production is likely to impair temporal redox homeostasis.
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Affiliation(s)
- Vladimir I Klichko
- Department of Biological Sciences, Southern Methodist University, Dallas TX, USA
| | - Eileen S Chow
- Department of Integrative Biology, Oregon State University, Corvallis OR, USA
| | | | - William C Orr
- Department of Biological Sciences, Southern Methodist University, Dallas TX, USA
| | | | - Svetlana N Radyuk
- Department of Biological Sciences, Southern Methodist University, Dallas TX, USA
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6
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Hermann PM, Watson SN, Wildering WC. Phospholipase A2 - nexus of aging, oxidative stress, neuronal excitability, and functional decline of the aging nervous system? Insights from a snail model system of neuronal aging and age-associated memory impairment. Front Genet 2014; 5:419. [PMID: 25538730 PMCID: PMC4255604 DOI: 10.3389/fgene.2014.00419] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 11/13/2014] [Indexed: 02/02/2023] Open
Abstract
The aging brain undergoes a range of changes varying from subtle structural and physiological changes causing only minor functional decline under healthy normal aging conditions, to severe cognitive or neurological impairment associated with extensive loss of neurons and circuits due to age-associated neurodegenerative disease conditions. Understanding how biological aging processes affect the brain and how they contribute to the onset and progress of age-associated neurodegenerative diseases is a core research goal in contemporary neuroscience. This review focuses on the idea that changes in intrinsic neuronal electrical excitability associated with (per)oxidation of membrane lipids and activation of phospholipase A2 (PLA2) enzymes are an important mechanism of learning and memory failure under normal aging conditions. Specifically, in the context of this special issue on the biology of cognitive aging we portray the opportunities offered by the identifiable neurons and behaviorally characterized neural circuits of the freshwater snail Lymnaea stagnalis in neuronal aging research and recapitulate recent insights indicating a key role of lipid peroxidation-induced PLA2 as instruments of aging, oxidative stress and inflammation in age-associated neuronal and memory impairment in this model system. The findings are discussed in view of accumulating evidence suggesting involvement of analogous mechanisms in the etiology of age-associated dysfunction and disease of the human and mammalian brain.
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Affiliation(s)
- Petra M Hermann
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada ; Department of Physiology and Pharmacology, University of Calgary Calgary, AB, Canada
| | - Shawn N Watson
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
| | - Willem C Wildering
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada ; Department of Physiology and Pharmacology, University of Calgary Calgary, AB, Canada ; Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
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7
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Watson SN, Lee JR, Risling TE, Hermann PM, Wildering WC. Diminishing glutathione availability and age-associated decline in neuronal excitability. Neurobiol Aging 2013; 35:1074-85. [PMID: 24331753 DOI: 10.1016/j.neurobiolaging.2013.11.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 11/05/2013] [Accepted: 11/09/2013] [Indexed: 01/05/2023]
Abstract
Oxidative stress is frequently implicated in diminished electrical excitability of aging neurons yet the foundations of this phenomenon are poorly understood. This study explored links between alterations in cellular thiol-redox state and age-associated decline in electrical excitability in identified neurons (right pedal dorsal 1 [RPeD1]) of the gastropod Lymnaea stagnalis. Intracellular thiol redox state was modulated with either dithiothreitol or membrane permeable ethyl ester of the antioxidant glutathione (et-GSH). Neuronal antioxidant demand was manipulated through induction of lipid peroxidation with 2,2'-azobis-2-methyl-propanimidamide-dihydrochloride (AAPH). Glutathione synthesis was manipulated with buthionine sulfoximine (BSO). We show that; glutathione content of snail brains declines with age, whereas pyroglutamate content increases; treatment with AAPH and BSO alone aggravated the natural low excitability state of old RPeD1, but only the combination of AAPH + BSO affected electrical excitability of young RPeD1; et-GSH reversed this effect in young RPeD1; et-GSH and dithiothreitol treatment reversed age-associated low excitability of old RPeD1. Together, these data argue for a tight association between glutathione availability and the regulation of neuronal electrical excitability and indicate perturbation of cellular thiol-redox metabolism as a key factor in neuronal functional decline in this gastropod model of biological aging.
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Affiliation(s)
- Shawn N Watson
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Jonathon R Lee
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Tara E Risling
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Petra M Hermann
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Willem C Wildering
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Faculty of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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8
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Beaver LM, Klichko VI, Chow ES, Kotwica-Rolinska J, Williamson M, Orr WC, Radyuk SN, Giebultowicz JM. Circadian regulation of glutathione levels and biosynthesis in Drosophila melanogaster. PLoS One 2012; 7:e50454. [PMID: 23226288 PMCID: PMC3511579 DOI: 10.1371/journal.pone.0050454] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 10/22/2012] [Indexed: 11/19/2022] Open
Abstract
Circadian clocks generate daily rhythms in neuronal, physiological, and metabolic functions. Previous studies in mammals reported daily fluctuations in levels of the major endogenous antioxidant, glutathione (GSH), but the molecular mechanisms that govern such fluctuations remained unknown. To address this question, we used the model species Drosophila, which has a rich arsenal of genetic tools. Previously, we showed that loss of the circadian clock increased oxidative damage and caused neurodegenerative changes in the brain, while enhanced GSH production in neuronal tissue conferred beneficial effects on fly survivorship under normal and stress conditions. In the current study we report that the GSH concentrations in fly heads fluctuate in a circadian clock-dependent manner. We further demonstrate a rhythm in activity of glutamate cysteine ligase (GCL), the rate-limiting enzyme in glutathione biosynthesis. Significant rhythms were also observed for mRNA levels of genes encoding the catalytic (Gclc) and modulatory (Gclm) subunits comprising the GCL holoenzyme. Furthermore, we found that the expression of a glutathione S-transferase, GstD1, which utilizes GSH in cellular detoxification, significantly fluctuated during the circadian day. To directly address the role of the clock in regulating GSH-related rhythms, the expression levels of the GCL subunits and GstD1, as well as GCL activity and GSH production were evaluated in flies with a null mutation in the clock genes cycle and period. The rhythms observed in control flies were not evident in the clock mutants, thus linking glutathione production and utilization to the circadian system. Together, these data suggest that the circadian system modulates pathways involved in production and utilization of glutathione.
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Affiliation(s)
- Laura M. Beaver
- Department of Zoology, Oregon State University, Corvallis, Oregon, United States of America
| | - Vladimir I. Klichko
- Department of Biological Sciences, Southern Methodist University, Dallas, Texas, United States of America
| | - Eileen S. Chow
- Department of Zoology, Oregon State University, Corvallis, Oregon, United States of America
| | - Joanna Kotwica-Rolinska
- Department of Zoology, Oregon State University, Corvallis, Oregon, United States of America
- Department of Animal Physiology, Zoological Institute, University of Warsaw, Warsaw, Poland
| | - Marisa Williamson
- Department of Zoology, Oregon State University, Corvallis, Oregon, United States of America
| | - William C. Orr
- Department of Biological Sciences, Southern Methodist University, Dallas, Texas, United States of America
| | - Svetlana N. Radyuk
- Department of Biological Sciences, Southern Methodist University, Dallas, Texas, United States of America
- * E-mail: (SNR); (JMG)
| | - Jadwiga M. Giebultowicz
- Department of Zoology, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail: (SNR); (JMG)
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9
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Rebrin I, Forster MJ, Sohal RS. Association between life-span extension by caloric restriction and thiol redox state in two different strains of mice. Free Radic Biol Med 2011; 51:225-33. [PMID: 21530646 PMCID: PMC3109181 DOI: 10.1016/j.freeradbiomed.2011.04.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 03/14/2011] [Accepted: 04/04/2011] [Indexed: 10/18/2022]
Abstract
The hypothesis that the life-extending effect of caloric restriction (CR) is associated with an attenuation of the age-related pro-oxidant shift in the thiol redox state was tested employing a novel experimental design. Amounts of GSH, GSSG, and protein mixed disulfides (Pr-SSG) in the skeletal muscle and liver were compared between two strains of mice that have similar life spans when fed ad libitum (AL), but different life spans under the standard CR regimen. The life span of one strain, C57BL/6, is extended under CR, whereas it remains unaffected in the other strain, DBA/2. Mice were fed AL or 40% less food starting at 4 months and compared at 6 and 24 months of age. The amounts of GSSG and Pr-SSG increased and the GSH:GSSG ratios decreased with age in both strains of AL-fed mice. CR prevented these age-related changes in the C57BL/6, whose life span is extended by CR, but not in the DBA/2 mice, in which it remains unaffected. CR enhanced the activity of glutamate-cysteine ligase in the C57BL/6, but not in the DBA/2 mice. The results suggest that longevity extension by CR may be associated with the attenuation of age-related pro-oxidizing shifts in the thiol redox state.
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Affiliation(s)
- Igor Rebrin
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, California 90089
| | - Michael J. Forster
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas 76107
- Institute for Aging and Alzheimer's Disease Research, University of North Texas Health Science Center, Fort Worth, Texas 76107
| | - Rajindar S. Sohal
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, California 90089
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Cao X, Xiao H, Zhang Y, Zou L, Chu Y, Chu X. 1, 5-Dicaffeoylquinic acid-mediated glutathione synthesis through activation of Nrf2 protects against OGD/reperfusion-induced oxidative stress in astrocytes. Brain Res 2010; 1347:142-8. [DOI: 10.1016/j.brainres.2010.05.072] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 05/18/2010] [Accepted: 05/24/2010] [Indexed: 12/30/2022]
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11
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Chen Y, Johansson E, Fan Y, Shertzer HG, Vasiliou V, Nebert DW, Dalton TP. Early onset senescence occurs when fibroblasts lack the glutamate-cysteine ligase modifier subunit. Free Radic Biol Med 2009; 47:410-8. [PMID: 19427898 PMCID: PMC2773044 DOI: 10.1016/j.freeradbiomed.2009.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 05/05/2009] [Accepted: 05/05/2009] [Indexed: 12/23/2022]
Abstract
Cellular senescence is the irreversible entry of cells into growth arrest. Senescence of primary cells in culture has long been used as an in vitro model for aging. Glutamate-cysteine ligase (GCL) controls the synthetic rate of the important cellular antioxidant glutathione (GSH). The catalytic subunit of GCL, GCLC, is catalytically active and essential for life. By contrast the modifier subunit of GCL, GCLM, is dispensable in mice. Although it is recognized that GCLM increases the rate of GSH synthesis, its physiological role is unclear. Herein, we show that loss of Gclm leads to premature senescence of primary murine fibroblasts as characterized by: (a) diminished growth rate, (b) cell morphology consistent with senescence, (c) increases in senescence-associated beta-galactosidase activity, and (d) cell cycle arrest at the G(1)/S and G(2)/M boundaries. These changes are accompanied by increased intracellular ROS, accumulation of DNA damage, and induction of p53 and p21 proteins. We also found that N-acetylcysteine increases intracellular GSH and prevents premature senescence in Gclm(-/-) cells. These results suggest that the control of GCLM, which in turn controls aspects of the cellular redox environment via GSH, is important in determining the replicative capacity of the cell.
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Affiliation(s)
- Ying Chen
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, OH 45267-0056, USA.
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12
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Pro-oxidant shift in glutathione redox state during aging. Adv Drug Deliv Rev 2008; 60:1545-52. [PMID: 18652861 DOI: 10.1016/j.addr.2008.06.001] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2008] [Accepted: 06/10/2008] [Indexed: 11/22/2022]
Abstract
The GSH:GSSG ratio, which is the primary determinant of the cellular redox state, becomes progressively more pro-oxidizing during the aging process due to an elevation in the GSSG content and a decline in the ability for de novo GSH biosynthesis. The K(m) of glutamate-cysteine ligase (GCL), the rate-limiting enzyme in de novo GSH biosynthesis, significantly increases during aging, which would adversely affect the ability for rapid GSH biosynthesis, especially under stressful conditions. Experimental studies suggest that age-related accumulation of homocysteine, an intermediate in the trans-sulfuration pathway, may be responsible for causing the loss of affinity between GCL and its substrates. Over-expression of GCL has been shown to prolong the life span of Drosophila by up to 50%, suggesting that perturbations in glutathione metabolism play a causal role in the aging process.
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Abstract
The nature of the mechanisms underlying the age-related decline in glutathione (GSH) synthetic capacity is at present unclear. Steady-state kinetic parameters of mouse liver GCL (glutamate-cysteine ligase), the rate-limiting enzyme in GSH synthesis, and levels of hepatic GSH synthesis precursors from the trans-sulfuration pathway, such as homocysteine, cystathionine and cysteine, were compared between young and old C57BL/6 mice (6- and 24-month-old respectively). There were no agerelated differences in GCL V(max), but the apparent K(m) for its substrates, cysteine and glutamate, was higher in the old mice compared with the young mice (approximately 800 compared with approximately 300 microM, and approximately 710 compared with 450 microM, P<0.05 for cysteine and glutamate in young and old mice respectively). Amounts of cysteine, cystathionine and Cys-Gly increased with age by 91, 24 and 28% respectively. Glutathione (GSH) levels remained unchanged with age, whereas GSSG content showed an 84% increase, suggesting a significant pro-oxidizing shift in the 2GSH/GSSG ratio. The amount of the toxic trans-sulfuration/glutathione biosynthetic pathway intermediate, homocysteine, was 154% higher (P<0.005) in the liver of old mice compared with young mice. The conversion of homocysteine into cystathionine, a rate-limiting step in trans-sulfuration catalysed by cystathionine beta-synthase, was comparatively less efficient in the old mice, as indicated by cystathionine/homocysteine ratios. Incubation of tissue homogenates with physiological concentrations of homocysteine caused an up to 4.4-fold increase in the apparent K(m) of GCL for its glutamate substrate, but had no effect on V(max). The results suggest that perturbation of the catalytic efficiency of GCL and accumulation of homocysteine from the trans-sulfuration pathway may adversely affect de novo GSH synthesis during aging.
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Affiliation(s)
- Dikran Toroser
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089-9121, U.S.A
| | - Rajindar S. Sohal
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089-9121, U.S.A
- To whom correspondence should be addressed (email )
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Lee JI, Kang J, Stipanuk M. Differential regulation of glutamate-cysteine ligase subunit expression and increased holoenzyme formation in response to cysteine deprivation. Biochem J 2006; 393:181-90. [PMID: 16137247 PMCID: PMC1383676 DOI: 10.1042/bj20051111] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
GCL (glutamate-cysteine ligase) is a heterodimer of a GCLC (GCL catalytic subunit) that possesses all of the enzymatic activity and a GCLM (GCL modifier subunit) that alters the K(i) of GCLC for GSH. We hypothesized that the expression of GCLM and the association of GCLM with GCLC were responsible for the apparent increase in GCL activity state observed in the liver of rats fed low-protein diets or in hepatocytes cultured in low-sulphur amino acid-containing medium. Therefore we conducted a series of studies using rats and a human hepatoma (HepG2/C3A) cell line to assess the role of GCLM and holoenzyme formation in the regulation of GCL activity in response to sulphur amino acid intake or availability. Increases in GCL activity in rat liver, as well as in HepG2 cells, were due to the additive effects of changes in the amount of GCLC and the kcat for GCLC. The increase in the kcat for GCLC was associated with increased holoenzyme formation, which was associated with an increase in the molar ratio of GCLM to GCLC. Furthermore, our results indicate that the GCLM level in rat liver is always limiting and that up-regulation of the GCLM level results in increased holoenzyme formation and an increase in the kcat. This is the first report demonstrating that the catalytic efficiency of rat GCL is increased by holoenzyme formation and the first demonstration of differential up-regulation of the GCL subunits in response to cysteine deprivation.
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Affiliation(s)
- Jeong-In Lee
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, U.S.A
| | - Joann Kang
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, U.S.A
| | - Martha H. Stipanuk
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, U.S.A
- To whom correspondence should be addressed (email )
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Toroser D, Yarian CS, Orr WC, Sohal RS. Mechanisms of gamma-glutamylcysteine ligase regulation. BIOCHIMICA ET BIOPHYSICA ACTA 2006; 1760:233-44. [PMID: 16324789 PMCID: PMC2837077 DOI: 10.1016/j.bbagen.2005.10.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 10/17/2005] [Accepted: 10/23/2005] [Indexed: 01/21/2023]
Abstract
The principal objective of this study was to investigate the mechanisms regulating the activity of gamma-glutamylcysteine ligase (GCL; EC 6.3.2.2), the rate limiting enzyme in glutathione biosynthesis. Two phylogenetically divergent species, mouse and the fruitfly, Drosophila melanogaster were used to test the hypothesis that reversible protein phosphorylation and pyridine dinucleotide phosphate dependent allostery regulate GCL activity. GCL was almost completely inhibited under phosphorylating conditions, involving preincubations with MgATP and endogenous protein kinases. Maximal GCL inhibitions of 94%, 77%, 85%, 87%, 83%, 95% and 89% occurred, respectively, in mouse cerebellum, hippocampus, brainstem, striatum, cortex and heart, and Drosophila. These changes in GCL activity were detected using saturating levels of substrates, suggesting that V(max) was dramatically affected, whereas K(m) values showed no differences. In vitro activation of GCL, presumably due to dephosphorylation, was blocked by inhibitors of protein phosphatases, suggesting that GCL exists in vivo as a mixture of phosphorylated and dephosphorylated forms. The reversibility of the dephosphorylation-dependent activation was indicated by the time-dependent inactivation of the in vitro activated Drosophila GCL, by preincubation with MgATP. NADPH increased maximal GCL activity by up to 93%, whereas several other nucleotide analogues did not, thereby demonstrating specificity. Kinetic analysis using Hanes-Woolf replots of initial velocity data suggested that the NADPH-dependent stimulation of GCL activity is brought about by a change in the maximal activity, V(max), rather than changes in substrate affinity. Results of this study suggest that mechanisms of modulation of eukaryotic GCL enzymes may include specific binding of ligands such as pyridine dinucleotide phosphates and reversible protein phosphorylation.
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Affiliation(s)
- Dikran Toroser
- Department of Molecular Pharmacology and Toxicology, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089-9121, USA
| | - Connie S. Yarian
- Department of Molecular Pharmacology and Toxicology, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089-9121, USA
| | - William C. Orr
- Department of Biological Sciences, Dedman Life Sciences Building, Southern Methodist University, Dallas, TX 75275, USA
| | - Rajindar S. Sohal
- Department of Molecular Pharmacology and Toxicology, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089-9121, USA
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Orr WC, Radyuk SN, Prabhudesai L, Toroser D, Benes JJ, Luchak JM, Mockett RJ, Rebrin I, Hubbard JG, Sohal RS. Overexpression of glutamate-cysteine ligase extends life span in Drosophila melanogaster. J Biol Chem 2005; 280:37331-8. [PMID: 16148000 DOI: 10.1074/jbc.m508272200] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The hypothesis that overexpression of glutamate-cysteine ligase (GCL), which catalyzes the rate-limiting reaction in de novo glutathione biosynthesis, could extend life span was tested in the fruit fly, Drosophila melanogaster. The GAL4-UAS binary transgenic system was used to generate flies overexpressing either the catalytic (GCLc) or modulatory (GCLm) subunit of this enzyme, in a global or neuronally targeted pattern. The GCL protein content of the central nervous system was elevated dramatically in the presence of either global or neuronal drivers. GCL activity was increased in the whole body or in heads, respectively, of GCLc transgenic flies containing global or neuronal drivers. The glutathione content of fly homogenates was increased by overexpression of GCLc or GCLm, particularly in flies overexpressing either subunit globally, or in the heads of GCLc flies possessing neuronal drivers. Neuronal overexpression of GCLc in a long-lived background extended mean and maximum life spans up to 50%, without affecting the rate of oxygen consumption by the flies. In contrast, global overexpression of GCLm extended the mean life span only up to 24%. These results demonstrate that enhancement of the glutathione biosynthetic capability, particularly in neuronal tissues, can extend the life span of flies, and thus support the oxidative stress hypothesis of aging.
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Affiliation(s)
- William C Orr
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA.
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