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Bao S, Yin T, Liu S. Ovarian aging: energy metabolism of oocytes. J Ovarian Res 2024; 17:118. [PMID: 38822408 PMCID: PMC11141068 DOI: 10.1186/s13048-024-01427-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 04/30/2024] [Indexed: 06/03/2024] Open
Abstract
In women who are getting older, the quantity and quality of their follicles or oocytes and decline. This is characterized by decreased ovarian reserve function (DOR), fewer remaining oocytes, and lower quality oocytes. As more women choose to delay childbirth, the decline in fertility associated with age has become a significant concern for modern women. The decline in oocyte quality is a key indicator of ovarian aging. Many studies suggest that age-related changes in oocyte energy metabolism may impact oocyte quality. Changes in oocyte energy metabolism affect adenosine 5'-triphosphate (ATP) production, but how related products and proteins influence oocyte quality remains largely unknown. This review focuses on oocyte metabolism in age-related ovarian aging and its potential impact on oocyte quality, as well as therapeutic strategies that may partially influence oocyte metabolism. This research aims to enhance our understanding of age-related changes in oocyte energy metabolism, and the identification of biomarkers and treatment methods.
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Affiliation(s)
- Shenglan Bao
- Reproductive Medical Center, Renmin Hospital of Wuhan University, Wuhan, China
| | - Tailang Yin
- Reproductive Medical Center, Renmin Hospital of Wuhan University, Wuhan, China.
| | - Su Liu
- Shenzhen Key Laboratory of Reproductive Immunology for Peri-Implantation, , Shenzhen Zhongshan Institute for Reproductive Medicine and Genetics, Shenzhen Zhongshan Obstetrics & Gynecology Hospital (Formerly Shenzhen Zhongshan Urology Hospital), Shenzhen, China.
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2
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King DE, Sparling AC, Joyce AS, Ryde IT, DeSouza B, Ferguson PL, Murphy SK, Meyer JN. Lack of detectable sex differences in the mitochondrial function of Caenorhabditis elegans. BMC Ecol Evol 2024; 24:55. [PMID: 38664688 PMCID: PMC11046947 DOI: 10.1186/s12862-024-02238-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND Sex differences in mitochondrial function have been reported in multiple tissue and cell types. Additionally, sex-variable responses to stressors including environmental pollutants and drugs that cause mitochondrial toxicity have been observed. The mechanisms that establish these differences are thought to include hormonal modulation, epigenetic regulation, double dosing of X-linked genes, and the maternal inheritance of mtDNA. Understanding the drivers of sex differences in mitochondrial function and being able to model them in vitro is important for identifying toxic compounds with sex-variable effects. Additionally, understanding how sex differences in mitochondrial function compare across species may permit insight into the drivers of these differences, which is important for basic biology research. This study explored whether Caenorhabditis elegans, a model organism commonly used to study stress biology and toxicology, exhibits sex differences in mitochondrial function and toxicant susceptibility. To assess sex differences in mitochondrial function, we utilized four male enriched populations (N2 wild-type male enriched, fog-2(q71), him-5(e1490), and him-8(e1498)). We performed whole worm respirometry and determined whole worm ATP levels and mtDNA copy number. To probe whether sex differences manifest only after stress and inform the growing use of C. elegans as a mitochondrial health and toxicologic model, we also assessed susceptibility to a classic mitochondrial toxicant, rotenone. RESULTS We detected few to no large differences in mitochondrial function between C. elegans sexes. Though we saw no sex differences in vulnerability to rotenone, we did observe sex differences in the uptake of this lipophilic compound, which may be of interest to those utilizing C. elegans as a model organism for toxicologic studies. Additionally, we observed altered non-mitochondrial respiration in two him strains, which may be of interest to other researchers utilizing these strains. CONCLUSIONS Basal mitochondrial parameters in male and hermaphrodite C. elegans are similar, at least at the whole-organism level, as is toxicity associated with a mitochondrial Complex I inhibitor, rotenone. Our data highlights the limitation of using C. elegans as a model to study sex-variable mitochondrial function and toxicological responses.
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Affiliation(s)
- Dillon E King
- Nicholas School of Environment, Duke University, 308 Research Drive, A304, Durham, NC, 27708, USA
- Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA
| | - A Clare Sparling
- Nicholas School of Environment, Duke University, 308 Research Drive, A304, Durham, NC, 27708, USA
| | - Abigail S Joyce
- Pratt School of Engineering, Duke University, Durham, NC, USA
| | - Ian T Ryde
- Nicholas School of Environment, Duke University, 308 Research Drive, A304, Durham, NC, 27708, USA
| | - Beverly DeSouza
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA
| | - P Lee Ferguson
- Pratt School of Engineering, Duke University, Durham, NC, USA
| | - Susan K Murphy
- Nicholas School of Environment, Duke University, 308 Research Drive, A304, Durham, NC, 27708, USA
- Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA
| | - Joel N Meyer
- Nicholas School of Environment, Duke University, 308 Research Drive, A304, Durham, NC, 27708, USA.
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3
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Shaik HA, Mishra A. Influence of Asafoetida Extract on the Virulence of the Entomopathogenic Nematode Steinernema carpocapsae and Its Symbiotic Bacterium Xenorhabdus nematophila in the Host Pyrrhocoris apterus. Microorganisms 2023; 11:1678. [PMID: 37512851 PMCID: PMC10385281 DOI: 10.3390/microorganisms11071678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/11/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
Nematode-microbe symbiosis plays a key role in determining pathogenesis against pests. The modulation of symbiotic bacteria may affect the virulence of entomopathogenic nematodes (EPNs) and the biological management of pests. We tested the influence of asafoetida (ASF) extract on the virulence of Steinernema carpocapsae and its symbiotic bacterium, Xenorhabdus nematophila, in Pyrrhocoris apterus. A total of 100 mg of ASF killed 30% of EPNs in 48 h, while P. apterus remained unaffected. The EPNs pre-treated with 100 mg of ASF influenced P. apterus's mortality by 24-91.4% during a period of 24 to 72 h. The topical application of ASF acted as a deterrent to S. carpocapsae, lowering host invasion to 70% and delaying infectivity with 30% mortality for 168 h. Interestingly, Steinernema's symbiotic bacterium, Xenorhabdus, remained unaffected by ASF. An in vitro turbidity test containing 100 mg of ASF in a medium increased the growth rate of Xenorhabdus compared to a control. A disc diffusion assay confirmed the non-susceptibility of Xenorhabdus to ASF compared to a positive control, streptomycin. Pro-phenol oxidase (PPO) and phenol oxidase (PO) upregulation showed that ASF influences immunity, while EPN/ASF showed a combined immunomodulatory effect in P. apterus. We report that ASF modulated the virulence of S. carpocapsae but not that of its symbiotic bacterium, X. nematophila, against P. apterus.
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Affiliation(s)
- Haq Abdul Shaik
- Institute of Entomology, Biology Centre, CAS, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Archana Mishra
- South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, Institute of Aquaculture and Protection of Waters, University of South Bohemia in České Budějovice, Na Sádkách 1780, 37005 České Budějovice, Czech Republic
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4
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Lavorato M, Nakamaru-Ogiso E, Mathew ND, Herman E, Shah NK, Haroon S, Xiao R, Seiler C, Falk MJ. Dichloroacetate improves mitochondrial function, physiology, and morphology in FBXL4 disease models. JCI Insight 2022; 7:156346. [PMID: 35881484 PMCID: PMC9462489 DOI: 10.1172/jci.insight.156346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 07/20/2022] [Indexed: 11/17/2022] Open
Abstract
Pathogenic variants in the human F-box and leucine-rich repeat protein 4 (FBXL4) gene result in an autosomal recessive, multisystemic, mitochondrial disorder involving variable mitochondrial depletion and respiratory chain complex deficiencies with lactic acidemia. As no FDA-approved effective therapies for this disease exist, we sought to characterize translational C. elegans and zebrafish animal models, as well as human fibroblasts, to study FBXL4–/– disease mechanisms and identify preclinical therapeutic leads. Developmental delay, impaired fecundity and neurologic and/or muscular activity, mitochondrial dysfunction, and altered lactate metabolism were identified in fbxl-1(ok3741) C. elegans. Detailed studies of a PDHc activator, dichloroacetate (DCA), in fbxl-1(ok3741)C. elegans demonstrated its beneficial effects on fecundity, neuromotor activity, and mitochondrial function. Validation studies were performed in fbxl4sa12470 zebrafish larvae and in FBXL4–/– human fibroblasts; they showed DCA efficacy in preventing brain death, impairment of neurologic and/or muscular function, mitochondrial biochemical dysfunction, and stress-induced morphologic and ultrastructural mitochondrial defects. These data demonstrate that fbxl-1(ok3741) C. elegans and fbxl4sa12470 zebrafish provide robust translational models to study mechanisms and identify preclinical therapeutic candidates for FBXL4–/– disease. Furthermore, DCA is a lead therapeutic candidate with therapeutic benefit on diverse aspects of survival, neurologic and/or muscular function, and mitochondrial physiology that warrants rigorous clinical trial study in humans with FBXL4–/– disease.
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Affiliation(s)
- Manuela Lavorato
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, United States of America
| | - Eiko Nakamaru-Ogiso
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, United States of America
| | - Neal D Mathew
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, United States of America
| | - Elizabeth Herman
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, United States of America
| | - Nina K Shah
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, United States of America
| | - Suraiya Haroon
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, United States of America
| | - Rui Xiao
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, United States of America
| | - Christoph Seiler
- Aquatics Core Facility, Children's Hospital of Philadelphia, Philadelphia, United States of America
| | - Marni J Falk
- Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, United States of America
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5
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Mello DF, Bergemann CM, Fisher K, Chitrakar R, Bijwadia SR, Wang Y, Caldwell A, Baugh LR, Meyer JN. Rotenone Modulates Caenorhabditis elegans Immunometabolism and Pathogen Susceptibility. Front Immunol 2022; 13:840272. [PMID: 35273616 PMCID: PMC8902048 DOI: 10.3389/fimmu.2022.840272] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 01/31/2022] [Indexed: 11/21/2022] Open
Abstract
Mitochondria are central players in host immunometabolism as they function not only as metabolic hubs but also as signaling platforms regulating innate immunity. Environmental exposures to mitochondrial toxicants occur widely and are increasingly frequent. Exposures to these mitotoxicants may pose a serious threat to organismal health and the onset of diseases by disrupting immunometabolic pathways. In this study, we investigated whether the Complex I inhibitor rotenone could alter C. elegans immunometabolism and disease susceptibility. C. elegans embryos were exposed to rotenone (0.5 µM) or DMSO (0.125%) until they reached the L4 larval stage. Inhibition of mitochondrial respiration by rotenone and disruption of mitochondrial metabolism were evidenced by rotenone-induced detrimental effects on mitochondrial efficiency and nematode growth and development. Next, through transcriptomic analysis, we investigated if this specific but mild mitochondrial stress that we detected would lead to the modulation of immunometabolic pathways. We found 179 differentially expressed genes (DEG), which were mostly involved in detoxification, energy metabolism, and pathogen defense. Interestingly, among the down-regulated DEG, most of the known genes were involved in immune defense, and most of these were identified as commonly upregulated during P. aeruginosa infection. Furthermore, rotenone increased susceptibility to the pathogen Pseudomonas aeruginosa (PA14). However, it increased resistance to Salmonella enterica (SL1344). To shed light on potential mechanisms related to these divergent effects on pathogen resistance, we assessed the activation of the mitochondrial unfolded protein response (UPRmt), a well-known immunometabolic pathway in C. elegans which links mitochondria and immunity and provides resistance to pathogen infection. The UPRmt pathway was activated in rotenone-treated nematodes further exposed for 24 h to the pathogenic bacteria P. aeruginosa and S. enterica or the common bacterial food source Escherichia coli (OP50). However, P. aeruginosa alone suppressed UPRmt activation and rotenone treatment rescued its activation only to the level of DMSO-exposed nematodes fed with E. coli. Module-weighted annotation bioinformatics analysis was also consistent with UPRmt activation in rotenone-exposed nematodes consistent with the UPR being involved in the increased resistance to S. enterica. Together, our results demonstrate that the mitotoxicant rotenone can disrupt C. elegans immunometabolism in ways likely protective against some pathogen species but sensitizing against others.
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Affiliation(s)
- Danielle F Mello
- Nicholas School of the Environment, Duke University, Durham, NC, United States
| | | | - Kinsey Fisher
- Department of Biology, Duke University, Durham, NC, United States
| | - Rojin Chitrakar
- Department of Biology, Duke University, Durham, NC, United States
| | - Shefali R Bijwadia
- Nicholas School of the Environment, Duke University, Durham, NC, United States
| | - Yang Wang
- Nicholas School of the Environment, Duke University, Durham, NC, United States
| | - Alexis Caldwell
- Nicholas School of the Environment, Duke University, Durham, NC, United States
| | - Larry Ryan Baugh
- Department of Biology, Duke University, Durham, NC, United States.,Center for Genomic and Computational Biology, Duke University, Durham, NC, United States
| | - Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC, United States
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6
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A reversible mitochondrial complex I thiol switch mediates hypoxic avoidance behavior in C. elegans. Nat Commun 2022; 13:2403. [PMID: 35504873 PMCID: PMC9064984 DOI: 10.1038/s41467-022-30169-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 04/18/2022] [Indexed: 01/28/2023] Open
Abstract
C. elegans react to metabolic distress caused by mismatches in oxygen and energy status via distinct behavioral responses. At the molecular level, these responses are coordinated by under-characterized, redox-sensitive processes, thought to initiate in mitochondria. Complex I of the electron transport chain is a major site of reactive oxygen species (ROS) production and is canonically associated with oxidative damage following hypoxic exposure. Here, we use a combination of optogenetics and CRISPR/Cas9-mediated genome editing to exert spatiotemporal control over ROS production. We demonstrate a photo-locomotory remodeling of avoidance behavior by local ROS production due to the reversible oxidation of a single thiol on the complex I subunit NDUF-2.1. Reversible thiol oxidation at this site is necessary and sufficient for the behavioral response to hypoxia, does not respond to ROS produced at more distal sites, and protects against lethal hypoxic exposure. Molecular modeling suggests that oxidation at this thiol residue alters the ability for NDUF-2.1 to coordinate electron transfer to coenzyme Q by destabilizing the Q-binding pocket, causing decreased complex I activity. Overall, site-specific ROS production regulates behavioral responses and these findings provide a mechanistic target to suppress the detrimental effects of hypoxia.
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7
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Khatri D, Brugière T, Athale CA, Delattre M. Evolutionary divergence of anaphase spindle mechanics in nematode embryos constrained by antagonistic pulling and viscous forces. Mol Biol Cell 2022; 33:ar61. [PMID: 35235368 PMCID: PMC9265157 DOI: 10.1091/mbc.e21-10-0532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cellular functions like cell division are remarkably conserved across phyla. However the evolutionary principles of cellular organization that drive it are less well explored. Thus, an essential question remains: to what extent cellular parameters evolve without altering the basic function they sustain? Here we have observed 6 different nematode species for which the mitotic spindle is positioned asymmetrically during the first embryonic division. Whereas the C. elegans spindle undergoes oscillations during its displacement, the spindle elongates without oscillations in other species. We asked which evolutionary changes in biophysical parameters could explain differences in spindle motion while maintaining a constant output. Using laser microsurgery of the spindle we revealed that all species are subjected to cortical pulling forces, of varying magnitudes. Using a viscoelastic model to fit the recoil trajectories and with an independent measurement of cytoplasmic viscosity, we extracted the values of cytoplasmic drag, cortical pulling forces and spindle elasticity for all species. We found large variations in cytoplasmic viscosity whereas cortical pulling forces and elasticity were often more constrained. In agreement with previous simulations, we found that increased viscosity correlates with decreased oscillation speeds across species. However, the absence of oscillations despite low viscosity in some species, can only be explained by smaller pulling forces. Consequently, we find that spindle mobility across the species analyzed here is characterized by a tradeoff between cytoplasmic viscosity and pulling forces normalized by the size of the embryo. Our work provides a framework for understanding mechanical constraints on evolutionary diversification of spindle mobility.
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Affiliation(s)
- Dhruv Khatri
- Div. of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Thibault Brugière
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS, Inserm, UCBL, 69007 Lyon, France
| | - Chaitanya A Athale
- Div. of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Marie Delattre
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS, Inserm, UCBL, 69007 Lyon, France
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8
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Mello DF, Maurer LL, Ryde IT, Song DH, Marinakos SM, Jiang C, Wiesner MR, Hsu-Kim H, Meyer JN. In Vivo Effects of Silver Nanoparticles on Development, Behavior, and Mitochondrial Function are Altered by Genetic Defects in Mitochondrial Dynamics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:1113-1124. [PMID: 35038872 PMCID: PMC8802983 DOI: 10.1021/acs.est.1c05915] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Silver nanoparticles (AgNPs) are extensively used in consumer products and biomedical applications, thus guaranteeing both environmental and human exposures. Despite extensive research addressing AgNP safety, there are still major knowledge gaps regarding AgNP toxicity mechanisms, particularly in whole organisms. Mitochondrial dysfunction is frequently described as an important cytotoxicity mechanism for AgNPs; however, it is still unclear if mitochondria are the direct targets of AgNPs. To test this, we exposed the nematodeCaenorhabditis elegans to sublethal concentrations of AgNPs and assessed specific mitochondrial parameters as well as organismal-level endpoints that are highly reliant on mitochondrial function, such as development and chemotaxis behavior. All AgNPs tested significantly delayed nematode development, disrupted mitochondrial bioenergetics, and blocked chemotaxis. However, silver was not preferentially accumulated in mitochondria, indicating that these effects are likely not due to direct mitochondria-AgNP interactions. Mutant nematodes with deficiencies in mitochondrial dynamics displayed both greater and decreased susceptibility to AgNPs compared to wild-type nematodes, which was dependent on the assay and AgNP type. Our study suggests that AgNPs indirectly promote mitochondrial dysfunction, leading to adverse outcomes at the organismal level, and reveals a role of gene-environment interactions in the susceptibility to AgNPs. Finally, we propose a novel hypothetical adverse outcome pathway for AgNP effects to guide future research.
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Affiliation(s)
- Danielle F. Mello
- Center for the Environmental Implications of Nanotechnology, Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, United States
- To whom correspondence should be addressed: and
| | - Laura L. Maurer
- Center for the Environmental Implications of Nanotechnology, Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, United States
| | - Ian T. Ryde
- Center for the Environmental Implications of Nanotechnology, Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, United States
| | - Dong Hoon Song
- Simulation Group, Samsung SDI, Suwon-si, Gyeonggi-do, Republic of Korea
| | - Stella M. Marinakos
- Center for the Environmental Implications of Nanotechnology, Department of Civil & Environmental Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Chuanjia Jiang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, P. R. China
| | - Mark R. Wiesner
- Center for the Environmental Implications of Nanotechnology, Department of Civil & Environmental Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Heileen Hsu-Kim
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, P. R. China
| | - Joel N. Meyer
- Center for the Environmental Implications of Nanotechnology, Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, United States
- To whom correspondence should be addressed: and
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9
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Knapp-Wilson A, Pereira GC, Buzzard E, Ford HC, Richardson A, Corey RA, Neal C, Verkade P, Halestrap AP, Gold VAM, Kuwabara PE, Collinson I. Maintenance of complex I and its supercomplexes by NDUF-11 is essential for mitochondrial structure, function and health. J Cell Sci 2021; 134:jcs258399. [PMID: 34106255 PMCID: PMC8277142 DOI: 10.1242/jcs.258399] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 05/28/2021] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial supercomplexes form around a conserved core of monomeric complex I and dimeric complex III; wherein a subunit of the former, NDUFA11, is conspicuously situated at the interface. We identified nduf-11 (B0491.5) as encoding the Caenorhabditis elegans homologue of NDUFA11. Animals homozygous for a CRISPR-Cas9-generated knockout allele of nduf-11 arrested at the second larval (L2) development stage. Reducing (but not eliminating) expression using RNAi allowed development to adulthood, enabling characterisation of the consequences: destabilisation of complex I and its supercomplexes and perturbation of respiratory function. The loss of NADH dehydrogenase activity was compensated by enhanced complex II activity, with the potential for detrimental reactive oxygen species (ROS) production. Cryo-electron tomography highlighted aberrant morphology of cristae and widening of both cristae junctions and the intermembrane space. The requirement of NDUF-11 for balanced respiration, mitochondrial morphology and development presumably arises due to its involvement in complex I and supercomplex maintenance. This highlights the importance of respiratory complex integrity for health and the potential for its perturbation to cause mitochondrial disease. This article has an associated First Person interview with Amber Knapp-Wilson, joint first author of the paper.
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Affiliation(s)
| | | | - Emma Buzzard
- Living Systems Institute, Stocker Road, University of Exeter, Exeter EX4 4QD, UK
- College of Life and Environmental Sciences,Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Holly C. Ford
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | | | - Robin A. Corey
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Chris Neal
- Wolfson Bioimaging Facility, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | | | - Vicki A. M. Gold
- Living Systems Institute, Stocker Road, University of Exeter, Exeter EX4 4QD, UK
- College of Life and Environmental Sciences,Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | | | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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10
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Hershberger KA, Rooney JP, Turner EA, Donoghue LJ, Bodhicharla R, Maurer LL, Ryde IT, Kim JJ, Joglekar R, Hibshman JD, Smith LL, Bhatt DP, Ilkayeva OR, Hirschey MD, Meyer JN. Early-life mitochondrial DNA damage results in lifelong deficits in energy production mediated by redox signaling in Caenorhabditis elegans. Redox Biol 2021; 43:102000. [PMID: 33993056 PMCID: PMC8134077 DOI: 10.1016/j.redox.2021.102000] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 04/19/2021] [Accepted: 04/28/2021] [Indexed: 11/12/2022] Open
Abstract
The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mtDNA is more susceptible to damage resulting from some genotoxicants than nuclear DNA (nucDNA), and many environmental toxicants target the mitochondria. Reports from the toxicological literature suggest that exposure to early-life mitochondrial damage could lead to deleterious consequences later in life (the “Developmental Origins of Health and Disease” paradigm), but reports from other fields often report beneficial (“mitohormetic”) responses to such damage. Here, we tested the effects of low (causing no change in lifespan) levels of ultraviolet C (UVC)-induced, irreparable mtDNA damage during early development in Caenorhabditis elegans. This exposure led to life-long reductions in mtDNA copy number and steady-state ATP levels, accompanied by increased oxygen consumption and altered metabolite profiles, suggesting inefficient mitochondrial function. Exposed nematodes were also developmentally delayed, reached smaller adult size, and were rendered more susceptible to subsequent exposure to chemical mitotoxicants. Metabolomic and genetic analysis of key signaling and metabolic pathways supported redox and mitochondrial stress-response signaling during early development as a mechanism for establishing these persistent alterations. Our results highlight the importance of early-life exposures to environmental pollutants, especially in the context of exposure to chemicals that target mitochondria. Early life mtDNA damage led to lifelong deficits in mitochondrial function. C. elegans developed slowly and were sensitive to chemical exposures as adults. Redox signaling is a mechanism that establishes these persistent alterations. Data are consistent with the Developmental Origins of Health and Disease model.
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Affiliation(s)
- Kathleen A Hershberger
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - John P Rooney
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Elena A Turner
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Lauren J Donoghue
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Rakesh Bodhicharla
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Laura L Maurer
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Ian T Ryde
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Jina J Kim
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Rashmi Joglekar
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Jonathan D Hibshman
- Duke University Department of Biology and University Program in Genetics and Genomics, Durham, NC, USA
| | - Latasha L Smith
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | | | | | | | - Joel N Meyer
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA.
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11
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Network analysis in aged C. elegans reveals candidate regulatory genes of ageing. Biogerontology 2021; 22:345-367. [PMID: 33871732 DOI: 10.1007/s10522-021-09920-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/30/2021] [Indexed: 10/21/2022]
Abstract
Ageing is a biological process guided by genetic and environmental factors that ultimately lead to adverse outcomes for organismal lifespan and healthspan. Determination of molecular pathways that are affected with age and increase disease susceptibility is crucial. The gene expression profile of the ideal ageing model, namely the nematode Caenorhabditis elegans mapped with the microarray technology initially led to the identification of age-dependent gene expression alterations that characterize the nematode's ageing process. The list of differentially expressed genes was then utilized to construct a network of molecular interactions with their first neighbors/interactors using the interactions listed in the WormBase database. The subsequent network analysis resulted in the unbiased selection of 110 candidate genes, among which well-known ageing regulators appeared. More importantly, our approach revealed candidates that have never been linked to ageing before, thus suggesting promising potential targets/ageing regulators.
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Povea-Cabello S, Villanueva-Paz M, Suárez-Rivero JM, Álvarez-Córdoba M, Villalón-García I, Talaverón-Rey M, Suárez-Carrillo A, Munuera-Cabeza M, Sánchez-Alcázar JA. Advances in mt-tRNA Mutation-Caused Mitochondrial Disease Modeling: Patients' Brain in a Dish. Front Genet 2021; 11:610764. [PMID: 33510772 PMCID: PMC7835939 DOI: 10.3389/fgene.2020.610764] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/26/2020] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial diseases are a heterogeneous group of rare genetic disorders that can be caused by mutations in nuclear (nDNA) or mitochondrial DNA (mtDNA). Mutations in mtDNA are associated with several maternally inherited genetic diseases, with mitochondrial dysfunction as a main pathological feature. These diseases, although frequently multisystemic, mainly affect organs that require large amounts of energy such as the brain and the skeletal muscle. In contrast to the difficulty of obtaining neuronal and muscle cell models, the development of induced pluripotent stem cells (iPSCs) has shed light on the study of mitochondrial diseases. However, it is still a challenge to obtain an appropriate cellular model in order to find new therapeutic options for people suffering from these diseases. In this review, we deepen the knowledge in the current models for the most studied mt-tRNA mutation-caused mitochondrial diseases, MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) and MERRF (myoclonic epilepsy with ragged red fibers) syndromes, and their therapeutic management. In particular, we will discuss the development of a novel model for mitochondrial disease research that consists of induced neurons (iNs) generated by direct reprogramming of fibroblasts derived from patients suffering from MERRF syndrome. We hypothesize that iNs will be helpful for mitochondrial disease modeling, since they could mimic patient’s neuron pathophysiology and give us the opportunity to correct the alterations in one of the most affected cellular types in these disorders.
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Affiliation(s)
- Suleva Povea-Cabello
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Marina Villanueva-Paz
- Instituto de Investigación Biomédica de Málaga, Departamento de Farmacología y Pediatría, Facultad de Medicina, Universidad de Málaga, Málaga, Spain
| | - Juan M Suárez-Rivero
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Mónica Álvarez-Córdoba
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Irene Villalón-García
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Marta Talaverón-Rey
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Alejandra Suárez-Carrillo
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Manuel Munuera-Cabeza
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - José A Sánchez-Alcázar
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
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Targeting metabolic pathways for extension of lifespan and healthspan across multiple species. Ageing Res Rev 2020; 64:101188. [PMID: 33031925 DOI: 10.1016/j.arr.2020.101188] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/20/2020] [Accepted: 09/21/2020] [Indexed: 12/16/2022]
Abstract
Metabolism plays a significant role in the regulation of aging at different levels, and metabolic reprogramming represents a major driving force in aging. Metabolic reprogramming leads to impaired organismal fitness, an age-dependent increase in susceptibility to diseases, decreased ability to mount a stress response, and increased frailty. The complexity of age-dependent metabolic reprogramming comes from the multitude of levels on which metabolic changes can be connected to aging and regulation of lifespan. This is further complicated by the different metabolic requirements of various tissues, cross-organ communication via metabolite secretion, and direct effects of metabolites on epigenetic state and redox regulation; however, not all of these changes are causative to aging. Studies in yeast, flies, worms, and mice have played a crucial role in identifying mechanistic links between observed changes in various metabolic traits and their effects on lifespan. Here, we review how changes in the organismal and organ-specific metabolome are associated with aging and how targeting of any one of over a hundred different targets in specific metabolic pathways can extend lifespan. An important corollary is that restriction or supplementation of different metabolites can change activity of these metabolic pathways in ways that improve healthspan and extend lifespan in different organisms. Due to the high levels of conservation of metabolism in general, translating findings from model systems to human beings will allow for the development of effective strategies for human health- and lifespan extension.
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Coppa A, Guha S, Fourcade S, Parameswaran J, Ruiz M, Moser AB, Schlüter A, Murphy MP, Lizcano JM, Miranda-Vizuete A, Dalfó E, Pujol A. The peroxisomal fatty acid transporter ABCD1/PMP-4 is required in the C. elegans hypodermis for axonal maintenance: A worm model for adrenoleukodystrophy. Free Radic Biol Med 2020; 152:797-809. [PMID: 32017990 PMCID: PMC7611262 DOI: 10.1016/j.freeradbiomed.2020.01.177] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/20/2020] [Accepted: 01/20/2020] [Indexed: 02/07/2023]
Abstract
Adrenoleukodystrophy is a neurometabolic disorder caused by a defective peroxisomal ABCD1 transporter of very long-chain fatty acids (VLCFAs). Its pathogenesis is incompletely understood. Here we characterize a nematode model of X-ALD with loss of the pmp-4 gene, the worm orthologue of ABCD1. These mutants recapitulate the hallmarks of X-ALD: i) VLCFAs accumulation and impaired mitochondrial redox homeostasis and ii) axonal damage coupled to locomotor dysfunction. Furthermore, we identify a novel role for PMP-4 in modulating lipid droplet dynamics. Importantly, we show that the mitochondria targeted antioxidant MitoQ normalizes lipid droplets size, and prevents axonal degeneration and locomotor disability, highlighting its therapeutic potential. Moreover, PMP-4 acting solely in the hypodermis rescues axonal and locomotion abnormalities, suggesting a myelin-like role for the hypodermis in providing essential peroxisomal functions for the nematode nervous system.
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Affiliation(s)
- Andrea Coppa
- Neurometabolic Diseases Laboratory, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Duran i Reynals, L'Hospitalet de Llobregat, Spain
| | - Sanjib Guha
- Neurometabolic Diseases Laboratory, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Duran i Reynals, L'Hospitalet de Llobregat, Spain
| | - Stéphane Fourcade
- Neurometabolic Diseases Laboratory, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Duran i Reynals, L'Hospitalet de Llobregat, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Spain
| | - Janani Parameswaran
- Neurometabolic Diseases Laboratory, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Duran i Reynals, L'Hospitalet de Llobregat, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Spain
| | - Montserrat Ruiz
- Neurometabolic Diseases Laboratory, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Duran i Reynals, L'Hospitalet de Llobregat, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Spain
| | - Ann B Moser
- Peroxisomal Diseases Laboratory, Kennedy Krieger Institute, 707 N. Broadway, Baltimore, MD, 21205, USA
| | - Agatha Schlüter
- Neurometabolic Diseases Laboratory, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Duran i Reynals, L'Hospitalet de Llobregat, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Spain
| | | | - Jose Miguel Lizcano
- Departament de Bioquímica i Biologia Molecular, Institut de Neurociències, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra (Barcelona), Spain
| | - Antonio Miranda-Vizuete
- Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío /CSIC/ Universidad de Sevilla, E-41013, Sevilla, Spain
| | - Esther Dalfó
- Departament de Bioquímica i Biologia Molecular, Institut de Neurociències, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra (Barcelona), Spain; Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), 08500, Vic, Spain.
| | - Aurora Pujol
- Neurometabolic Diseases Laboratory, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Duran i Reynals, L'Hospitalet de Llobregat, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Spain; ICREA (Institució Catalana de Recerca i Estudis Avançats), Barcelona, Spain.
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15
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Goncalves J, Wan Y, Guo X, Rha K, LeBoeuf B, Zhang L, Estler K, Garcia LR. Succinate Dehydrogenase-Regulated Phosphoenolpyruvate Carboxykinase Sustains Copulation Fitness in Aging C. elegans Males. iScience 2020; 23:100990. [PMID: 32240955 PMCID: PMC7115159 DOI: 10.1016/j.isci.2020.100990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/18/2020] [Accepted: 03/11/2020] [Indexed: 01/02/2023] Open
Abstract
Dysregulated metabolism accelerates reduced decision-making and locomotor ability during aging. To identify mechanisms for delaying behavioral decline, we investigated how C. elegans males sustain their copulatory behavior during early to mid-adulthood. We found that in mid-aged males, gluco-/glyceroneogenesis, promoted by phosphoenolpyruvate carboxykinase (PEPCK), sustains competitive reproductive behavior. C. elegans' PEPCK paralogs, pck-1 and pck-2, increase in expression during the first 2 days of adulthood. Insufficient PEPCK expression correlates with reduced egl-2-encoded ether-a-go-go K+ channel expression and premature hyper-excitability of copulatory circuits. For copulation, pck-1 is required in neurons, whereas pck-2 is required in the epidermis. However, PCK-2 is more essential, because we found that epidermal PCK-2 likely supplements the copulation circuitry with fuel. We identified the subunit A of succinate dehydrogenase SDHA-1 as a potent modulator of PEPCK expression. We postulate that during mid-adulthood, reduction in mitochondrial physiology signals the upregulation of cytosolic PEPCK to sustain the male's energy demands. C. elegans upregulates pck-1- and pck-2-encoded PEPCK during early adulthood Loss of PEPCK causes premature male copulatory behavior decline Epidermal PEPCK is required to sustain the copulatory fitness Subunit A of succinate dehydrogenase antagonizes PEPCK expression
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Affiliation(s)
- Jimmy Goncalves
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Yufeng Wan
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Xiaoyan Guo
- Institute for Neurodegenerative Diseases, University of California, San Francisco, CA 94158, USA
| | - Kyoungsun Rha
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Brigitte LeBoeuf
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Liusuo Zhang
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China
| | - Kerolayne Estler
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - L René Garcia
- Department of Biology, Texas A&M University, College Station, TX 77843, USA.
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16
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Ozkurede U, Miller RA. Improved mitochondrial stress response in long-lived Snell dwarf mice. Aging Cell 2019; 18:e13030. [PMID: 31423721 PMCID: PMC6826134 DOI: 10.1111/acel.13030] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 07/31/2019] [Accepted: 08/06/2019] [Indexed: 12/20/2022] Open
Abstract
Prolonged lifespan and improved health in late adulthood can be achieved by partial inhibition of mitochondrial proteins in yeast, worms, fruit flies, and mice. Upregulation of the mitochondrial unfolded protein response (mtUPR) has been proposed as a common pathway in lifespan extension induced by mitochondrial defects. However, it is not known whether mtUPR is elevated in long‐lived mouse models. Here, we report that Snell dwarf mice, which show 30%–40% lifespan extension and prolonged healthspan, exhibit augmented mitochondrial stress responses. Cultured cells from Snell mice show elevated levels of the mitochondrial chaperone HSP60 and mitochondrial protease LONP1, two components of the mtUPR. In response to mitochondrial stress, the increase in Tfam (mitochondrial transcription factor A), a regulator of mitochondrial transcription, is higher in Snell cells, while Pgc‐1α, the main regulator of mitochondrial biogenesis, is upregulated only in Snell cells. Consistent with these differences, Snell cells maintain oxidative respiration rate, ATP content, and expression of mitochondrial‐DNA‐encoded genes after exposure to doxycycline stress. In vivo, compared to normal mice, Snell mice show stronger hepatic mtUPR induction and maintain mitochondrial protein stoichiometry after mitochondrial stress exposure. Overall, our work demonstrates that a long‐lived mouse model exhibits improved mitochondrial stress response, and provides a rationale for future mouse lifespan studies involving compounds that induce mtUPR. Further research on mitochondrial homeostasis in long‐lived mice may facilitate development of interventions that blunt mitochondrial deterioration in neurodegenerative diseases such as Alzheimer's and Parkinson's and postpone diseases of aging in humans.
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Affiliation(s)
- Ulas Ozkurede
- Department of Molecular and Cellular Pathology, University of Michigan Geriatrics Center University of Michigan School of Medicine Ann Arbor MI USA
| | - Richard A. Miller
- Department of Molecular and Cellular Pathology, University of Michigan Geriatrics Center University of Michigan School of Medicine Ann Arbor MI USA
- Department of Pathology, University of Michigan Geriatrics Center University of Michigan School of Medicine Ann Arbor MI USA
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17
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Chuaijit S, Boonyatistan W, Boonchuay P, Metheetrairut C, Suthammarak W. Identification of a novel mitochondrial complex I assembly factor ACDH-12 in Caenorhabditis elegans. Mitochondrion 2019. [DOI: 10.1016/j.mito.2018.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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18
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Henis-Korenblit S, Meléndez A. Methods to Determine the Role of Autophagy Proteins in C. elegans Aging. Methods Mol Biol 2019; 1880:561-586. [PMID: 30610723 DOI: 10.1007/978-1-4939-8873-0_37] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
This chapter describes methods for the analysis of autophagy proteins in C. elegans aging. We discuss the strains to be considered, the methods for the delivery of double-stranded RNA, and the methods to measure autophagy levels, autophagic flux, and degradation by autophagy.
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Affiliation(s)
- Sivan Henis-Korenblit
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
| | - Alicia Meléndez
- Department of Biology, Queens College, The City University of New York, Flushing, NY, USA.
- Biology and Biochemistry PhD Programs, The Graduate Center of the City University of New York, New York, NY, USA.
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19
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Genetic inhibition of an ATP synthase subunit extends lifespan in C. elegans. Sci Rep 2018; 8:14836. [PMID: 30287841 PMCID: PMC6172204 DOI: 10.1038/s41598-018-32025-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 08/31/2018] [Indexed: 12/16/2022] Open
Abstract
Mild inhibition of mitochondrial respiration leads to longevity. Disruption of mitochondrial respiratory components extends lifespan in Caenorhabditis elegans, but the effects appear to be complex and the underlying mechanism for lifespan regulation by mitochondrial respiratory genes is still not fully understood. Here, we investigated the role of Y82E9BR.3, a worm homolog of the ATP synthase subunit C, in modulating longevity in C. elegans. We found that the Y82E9BR.3 protein is localized in mitochondria and expressed in various tissues throughout development. RNAi knockdown of Y82E9BR.3 extends lifespan, decreases the accumulation of lipofuscin, and affects various physiological processes, including development delay, reproduction impairment and slow behavior. Further tissue-specific RNAi analysis showed that the intestine is a crucial organ for the longevity effects conferred by Y82E9BR.3 RNAi. Moreover, we demonstrated that lifespan extension by Y82E9BR.3 RNAi is associated with reduced mitochondrial function, as well as the suppression of complex I activity in mitochondria. Unexpectedly, Y82E9BR.3 RNAi knock down did not influence the whole-worm ATP level. Our findings first reveal the crucial role of Y82E9BR.3 in mitochondrial function and the underlying mechanism of how Y82E9BR.3 regulates lifespan in C. elegans.
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Dalton HM, Curran SP. Hypodermal responses to protein synthesis inhibition induce systemic developmental arrest and AMPK-dependent survival in Caenorhabditis elegans. PLoS Genet 2018; 14:e1007520. [PMID: 30020921 PMCID: PMC6066256 DOI: 10.1371/journal.pgen.1007520] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/30/2018] [Accepted: 06/27/2018] [Indexed: 01/08/2023] Open
Abstract
Across organisms, manipulation of biosynthetic capacity arrests development early in life, but can increase health- and lifespan post-developmentally. Here we demonstrate that this developmental arrest is not sickness but rather a regulated survival program responding to reduced cellular performance. We inhibited protein synthesis by reducing ribosome biogenesis (rps-11/RPS11 RNAi), translation initiation (ifg-1/EIF3G mutation and egl-45/EIF3A RNAi), or ribosome progression (cycloheximide treatment), all of which result in a specific arrest at larval stage 2 of C. elegans development. This quiescent state can last for weeks—beyond the normal C. elegans adult lifespan—and is reversible, as animals can resume reproduction and live a normal lifespan once released from the source of protein synthesis inhibition. The arrest state affords resistance to thermal, oxidative, and heavy metal stress exposure. In addition to cell-autonomous responses, reducing biosynthetic capacity only in the hypodermis was sufficient to drive organism-level developmental arrest and stress resistance phenotypes. Among the cell non-autonomous responses to protein synthesis inhibition is reduced pharyngeal pumping that is dependent upon AMPK-mediated signaling. The reduced pharyngeal pumping in response to protein synthesis inhibition is recapitulated by exposure to microbes that generate protein synthesis-inhibiting xenobiotics, which may mechanistically reduce ingestion of pathogen and toxin. These data define the existence of a transient arrest-survival state in response to protein synthesis inhibition and provide an evolutionary foundation for the conserved enhancement of healthy aging observed in post-developmental animals with reduced biosynthetic capacity. Protein synthesis is an essential cellular process, but post-developmental reduction of protein synthesis across multiple species leads to improved health- and lifespan. To better understand the physiological responses to impaired protein synthesis, we characterize a novel developmental arrest state that occurs when reducing protein synthesis during C. elegans development. Arrested animals have multiple survival-promoting phenotypes that are all dependent on the cellular energy sensor, AMP kinase. This survival response acts through the hypodermis and causes a reduction in pharyngeal pumping, indicating that the animal is responding to a perceived external threat, even in adults. Furthermore, exposing animals to pathogens, or xenobiotics they produce, can recapitulate these phenotypes, providing a potential evolutionary explanation for how a beneficial response in adults could evolve through the inhibition of an essential biological process such as protein synthesis.
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Affiliation(s)
- Hans M. Dalton
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, United States of America
- Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Sean P. Curran
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, United States of America
- Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California, United States of America
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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21
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Palmisano NJ, Meléndez A. Autophagy in C. elegans development. Dev Biol 2018; 447:103-125. [PMID: 29709599 DOI: 10.1016/j.ydbio.2018.04.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 03/19/2018] [Accepted: 04/12/2018] [Indexed: 12/11/2022]
Abstract
Autophagy involves the sequestration of cytoplasmic contents in a double-membrane structure referred to as the autophagosome and the degradation of its contents upon delivery to lysosomes. Autophagy activity has a role in multiple biological processes during the development of the nematode Caenorhabditis elegans. Basal levels of autophagy are required to remove aggregate prone proteins, paternal mitochondria, and spermatid-specific membranous organelles. During larval development, autophagy is required for the remodeling that occurs during dauer development, and autophagy can selectively degrade components of the miRNA-induced silencing complex, and modulate miRNA-mediated silencing. Basal levels of autophagy are important in synapse formation and in the germ line, to promote the proliferation of proliferating stem cells. Autophagy activity is also required for the efficient removal of apoptotic cell corpses by promoting phagosome maturation. Finally, autophagy is also involved in lipid homeostasis and in the aging process. In this review, we first describe the molecular complexes involved in the process of autophagy, its regulation, and mechanisms for cargo recognition. In the second section, we discuss the developmental contexts where autophagy has been shown to be important. Studies in C. elegans provide valuable insights into the physiological relevance of this process during metazoan development.
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Affiliation(s)
- Nicholas J Palmisano
- Biology Department, Queens College, CUNY, Flushing, NY, USA; Biology Ph.D. Program, The Graduate Center of the City University of New York, NK, USA
| | - Alicia Meléndez
- Biology Department, Queens College, CUNY, Flushing, NY, USA; Biology Ph.D. Program, The Graduate Center of the City University of New York, NK, USA; Biochemistry Ph.D. Program, The Graduate Center of the City University of New York, NY, USA.
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22
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Larrick JW, Larrick JW, Mendelsohn AR. ATP Synthase, a Target for Dementia and Aging? Rejuvenation Res 2018; 21:61-66. [DOI: 10.1089/rej.2018.2056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- James W. Larrick
- Panorama Research Institute, Sunnyvale, California
- Regenerative Sciences Institute, Sunnyvale, California
| | | | - Andrew R. Mendelsohn
- Panorama Research Institute, Sunnyvale, California
- Regenerative Sciences Institute, Sunnyvale, California
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23
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van der Bliek AM, Sedensky MM, Morgan PG. Cell Biology of the Mitochondrion. Genetics 2017; 207:843-871. [PMID: 29097398 PMCID: PMC5676242 DOI: 10.1534/genetics.117.300262] [Citation(s) in RCA: 241] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/05/2017] [Indexed: 01/19/2023] Open
Abstract
Mitochondria are best known for harboring pathways involved in ATP synthesis through the tricarboxylic acid cycle and oxidative phosphorylation. Major advances in understanding these roles were made with Caenorhabditiselegans mutants affecting key components of the metabolic pathways. These mutants have not only helped elucidate some of the intricacies of metabolism pathways, but they have also served as jumping off points for pharmacology, toxicology, and aging studies. The field of mitochondria research has also undergone a renaissance, with the increased appreciation of the role of mitochondria in cell processes other than energy production. Here, we focus on discoveries that were made using C. elegans, with a few excursions into areas that were studied more thoroughly in other organisms, like mitochondrial protein import in yeast. Advances in mitochondrial biogenesis and membrane dynamics were made through the discoveries of novel functions in mitochondrial fission and fusion proteins. Some of these functions were only apparent through the use of diverse model systems, such as C. elegans Studies of stress responses, exemplified by mitophagy and the mitochondrial unfolded protein response, have also benefitted greatly from the use of model organisms. Recent developments include the discoveries in C. elegans of cell autonomous and nonautonomous pathways controlling the mitochondrial unfolded protein response, as well as mechanisms for degradation of paternal mitochondria after fertilization. The evolutionary conservation of many, if not all, of these pathways ensures that results obtained with C. elegans are equally applicable to studies of human mitochondria in health and disease.
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Affiliation(s)
- Alexander M van der Bliek
- Department of Biological Chemistry, Jonsson Comprehensive Cancer Center and Molecular Biology Institute, David Geffen School of Medicine at UCLA, Los Angeles, California 90024
| | - Margaret M Sedensky
- Department of Anesthesiology and Pain Medicine, University of Washington and Center for Developmental Therapeutics, Seattle Children's Research Institute, Washington 98101
| | - Phil G Morgan
- Department of Anesthesiology and Pain Medicine, University of Washington and Center for Developmental Therapeutics, Seattle Children's Research Institute, Washington 98101
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24
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Shemesh N, Meshnik L, Shpigel N, Ben-Zvi A. Dietary-Induced Signals That Activate the Gonadal Longevity Pathway during Development Regulate a Proteostasis Switch in Caenorhabditis elegans Adulthood. Front Mol Neurosci 2017; 10:254. [PMID: 28848390 PMCID: PMC5552676 DOI: 10.3389/fnmol.2017.00254] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/27/2017] [Indexed: 12/13/2022] Open
Abstract
Cell-non-autonomous signals dictate the functional state of cellular quality control systems, remodeling the ability of cells to cope with stress and maintain protein homeostasis (proteostasis). One highly regulated cell-non-autonomous switch controls proteostatic capacity in Caenorhabditis elegans adulthood. Signals from the reproductive system down-regulate cyto-protective pathways, unless countered by signals reporting on germline proliferation disruption. Here, we utilized dihomo-γ-linolenic acid (DGLA) that depletes the C. elegans germline to ask when cell-non-autonomous signals from the reproductive system determine somatic proteostasis and whether such regulation is reversible. We found that diet supplementation of DGLA resulted in the maintenance of somatic proteostasis after the onset of reproduction. DGLA-dependent proteostasis remodeling was only effective if animals were exposed to DGLA during larval development. A short exposure of 16 h during the second to fourth larval stages was sufficient and required to maintain somatic proteostasis in adulthood but not to extend lifespan. The reproductive system was required for DGLA-dependent remodeling of proteostasis in adulthood, likely via DGLA-dependent disruption of germline stem cells. However, arachidonic acid (AA), a somatic regulator of this pathway that does not require the reproductive system, presented similar regulatory timing. Finally, we showed that DGLA- and AA-supplementation led to activation of the gonadal longevity pathway but presented differential regulatory timing. Proteostasis and stress response regulators, including hsf-1 and daf-16, were only activated if exposed to DGLA and AA during development, while other gonadal longevity factors did not show this regulatory timing. We propose that C. elegans determines its proteostatic fate during development and is committed to either reproduction, and thus present restricted proteostasis, or survival, and thus present robust proteostasis. Given the critical role of proteostatic networks in the onset and progression of many aging-related diseases, such a choice could impact susceptibility to protein misfolding diseases later in life.
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Affiliation(s)
- Netta Shemesh
- Department of Life Sciences, The National Institute for Biotechnology in the NegevBen-Gurion University of the Negev, Beer Sheva, Israel
| | - Lana Meshnik
- Department of Life Sciences, The National Institute for Biotechnology in the NegevBen-Gurion University of the Negev, Beer Sheva, Israel
| | - Nufar Shpigel
- Department of Life Sciences, The National Institute for Biotechnology in the NegevBen-Gurion University of the Negev, Beer Sheva, Israel
| | - Anat Ben-Zvi
- Department of Life Sciences, The National Institute for Biotechnology in the NegevBen-Gurion University of the Negev, Beer Sheva, Israel
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25
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Luz AL, Godebo TR, Smith LL, Leuthner TC, Maurer LL, Meyer JN. Deficiencies in mitochondrial dynamics sensitize Caenorhabditis elegans to arsenite and other mitochondrial toxicants by reducing mitochondrial adaptability. Toxicology 2017; 387:81-94. [PMID: 28602540 PMCID: PMC5535741 DOI: 10.1016/j.tox.2017.05.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 05/10/2017] [Accepted: 05/30/2017] [Indexed: 01/06/2023]
Abstract
Mitochondrial fission, fusion, and mitophagy are interlinked processes that regulate mitochondrial shape, number, and size, as well as metabolic activity and stress response. The fundamental importance of these processes is evident in the fact that mutations in fission (DRP1), fusion (MFN2, OPA1), and mitophagy (PINK1, PARK2) genes can cause human disease (collectively >1/10,000). Interestingly, however, the age of onset and severity of clinical manifestations varies greatly between patients with these diseases (even those harboring identical mutations), suggesting a role for environmental factors in the development and progression of certain mitochondrial diseases. Using the model organism Caenorhabditis elegans, we screened ten mitochondrial toxicants (2, 4-dinitrophenol, acetaldehyde, acrolein, aflatoxin B1, arsenite, cadmium, cisplatin, doxycycline, paraquat, rotenone) for increased or decreased toxicity in fusion (fzo-1, eat-3)-, fission (drp-1)-, and mitophagy (pdr-1, pink-1)-deficient nematodes using a larval growth assay. In general, fusion-deficient nematodes were the most sensitive to toxicants, including aflatoxin B1, arsenite, cisplatin, paraquat, and rotenone. Because arsenite was particularly potent in fission- and fusion-deficient nematodes, and hundreds of millions of people are chronically exposed to arsenic, we investigated the effects of these genetic deficiencies on arsenic toxicity in more depth. We found that deficiencies in fission and fusion sensitized nematodes to arsenite-induced lethality throughout aging. Furthermore, low-dose arsenite, which acted in a "mitohormetic" fashion by increasing mitochondrial function (in particular, basal and maximal oxygen consumption) in wild-type nematodes by a wide range of measures, exacerbated mitochondrial dysfunction in fusion-deficient nematodes. Analysis of multiple mechanistic changes suggested that disruption of pyruvate metabolism and Krebs cycle activity underlie the observed arsenite-induced mitochondrial deficits, and these disruptions are exacerbated in the absence of mitochondrial fusion. This research demonstrates the importance of mitochondrial dynamics in limiting arsenite toxicity by permitting mitochondrial adaptability. It also suggests that individuals suffering from deficiencies in mitodynamic processes may be more susceptible to the mitochondrial toxicity of arsenic and other toxicants.
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Affiliation(s)
- Anthony L Luz
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Tewodros R Godebo
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Latasha L Smith
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Tess C Leuthner
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Laura L Maurer
- ExxonMobil Biomedical Sciences, Inc., Annandale, NJ, 08801-3059, USA
| | - Joel N Meyer
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA.
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26
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Mitochondrial form, function and signalling in aging. Biochem J 2017; 473:3421-3449. [PMID: 27729586 DOI: 10.1042/bcj20160451] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 06/17/2016] [Indexed: 02/07/2023]
Abstract
Aging is often accompanied by a decline in mitochondrial mass and function in different tissues. Additionally, cell resistance to stress is frequently found to be prevented by higher mitochondrial respiratory capacity. These correlations strongly suggest mitochondria are key players in aging and senescence, acting by regulating energy homeostasis, redox balance and signalling pathways central in these processes. However, mitochondria display a wide array of functions and signalling properties, and the roles of these different characteristics are still widely unexplored. Furthermore, differences in mitochondrial properties and responses between tissues and cell types, and how these affect whole body metabolism are also still poorly understood. This review uncovers aspects of mitochondrial biology that have an impact upon aging in model organisms and selected mammalian cells and tissues.
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27
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Livshits L, Chatterjee AK, Karbian N, Abergel R, Abergel Z, Gross E. Mechanisms of defense against products of cysteine catabolism in the nematode Caenorhabditis elegans. Free Radic Biol Med 2017; 104:346-359. [PMID: 28179109 DOI: 10.1016/j.freeradbiomed.2017.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/29/2017] [Accepted: 02/03/2017] [Indexed: 12/13/2022]
Abstract
Cysteine catabolism presents cells with a double-edged sword. On the one hand, cysteine degradation provides cells with essential molecules such as taurine and sulfide. The formation of sulfide in cells is thought to regulate important and diverse physiological processes including blood circulation, synaptic activity and inflammation. On the other hand, the catabolism of cysteine by gut microbiota can release high levels of sulfide that may underlie the development or relapse of ulcerative colitis, an inflammatory bowel disease affecting millions of people worldwide. Here, we have used the nematode C. elegans to explore how cells tolerate high levels of sulfide produced by cysteine degradation in bacteria. We have identified mutations in genes coding for thioredoxin family proteins, mitochondrial proteins, and collagens that confer tolerance to sulfide toxicity. Exposure to sulfide induces the unfolded protein response in the endoplasmic reticulum and mitochondria. Moreover, our results suggest that sulfide toxicity is mediated by reactive oxygen species (ROS). Indeed, pre-treatment of worms with antioxidants increases their tolerance to sulfide toxicity. Intriguingly, sub-toxic levels of the superoxide generator paraquat can also increase the tolerance of worms to sulfide. Therefore, it appears that activation of ROS detoxification pathway prior to the exposure to sulfide, can increase the tolerance to sulfide toxicity. Our results suggest that these detoxification pathways are mediated by the hypoxia inducible factor HIF-1. Finally, we show that sulfide resistance varies among wild C. elegans and other nematode species, suggesting that tolerance to sulfide was naturally selected in certain habitats.
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Affiliation(s)
- Leonid Livshits
- The Hebrew University of Jerusalem, Faculty of Medicine, IMRIC, Dept. of Biochemistry & Molecular Biology, Jerusalem, Israel
| | - Arijit Kumar Chatterjee
- The Hebrew University of Jerusalem, Faculty of Medicine, IMRIC, Dept. of Biochemistry & Molecular Biology, Jerusalem, Israel
| | - Netanel Karbian
- The Hebrew University of Jerusalem, Faculty of Medicine, IMRIC, Dept. of Biochemistry & Molecular Biology, Jerusalem, Israel
| | - Rachel Abergel
- The Hebrew University of Jerusalem, Faculty of Medicine, IMRIC, Dept. of Biochemistry & Molecular Biology, Jerusalem, Israel
| | - Zohar Abergel
- The Hebrew University of Jerusalem, Faculty of Medicine, IMRIC, Dept. of Biochemistry & Molecular Biology, Jerusalem, Israel
| | - Einav Gross
- The Hebrew University of Jerusalem, Faculty of Medicine, IMRIC, Dept. of Biochemistry & Molecular Biology, Jerusalem, Israel.
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28
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Kim DK, Kim TH, Lee SJ. Mechanisms of aging-related proteinopathies in Caenorhabditis elegans. Exp Mol Med 2016; 48:e263. [PMID: 27713398 PMCID: PMC5099420 DOI: 10.1038/emm.2016.109] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/05/2016] [Accepted: 07/12/2016] [Indexed: 12/24/2022] Open
Abstract
Aging is the most important risk factor for human neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Pathologically, these diseases are characterized by the deposition of specific protein aggregates in neurons and glia, representing the impairment of neuronal proteostasis. However, the mechanism by which aging affects the proteostasis system and promotes protein aggregation remains largely unknown. The short lifespan and ample genetic resources of Caenorhabditis elegans (C. elegans) have made this species a favorite model organism for aging research, and the development of proteinopathy models in this organism has helped us to understand how aging processes affect protein aggregation and neurodegeneration. Here, we review the recent literature on proteinopathies in C. elegans models and discuss the insights we have gained into the mechanisms of how aging processes are integrated into the pathogenesis of various neurodegenerative diseases.
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Affiliation(s)
- Dong-Kyu Kim
- Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
- Department of Biomedical Science and Technology, Konkuk University, Seoul, Korea
| | - Tae Ho Kim
- Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
- Department of Medicine, Inha University School of Medicine, Incheon, Korea
| | - Seung-Jae Lee
- Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
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29
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Luz AL, Meyer JN. Effects of reduced mitochondrial DNA content on secondary mitochondrial toxicant exposure in Caenorhabditis elegans. Mitochondrion 2016; 30:255-64. [PMID: 27566481 PMCID: PMC5023498 DOI: 10.1016/j.mito.2016.08.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 07/12/2016] [Accepted: 08/22/2016] [Indexed: 01/21/2023]
Abstract
The mitochondrial genome (mtDNA) is intimately linked to cellular and organismal health, as demonstrated by the fact that mutations in and depletion of mtDNA result in severe mitochondrial disease in humans. However, cells contain hundreds to thousands of copies of mtDNA, which provides genetic redundancy, and creates a threshold effect in which a large percentage of mtDNA must be lost prior to clinical pathogenesis. As certain pharmaceuticals and genetic mutations can result in depletion of mtDNA, and as many environmental toxicants target mitochondria, it is important to understand whether reduced mtDNA will sensitize an individual to toxicant exposure. Here, using ethidium bromide (EtBr), which preferentially inhibits mtDNA replication, we reduced mtDNA 35-55% in the in vivo model organism Caenorhabditis elegans. Chronic, lifelong, low-dose EtBr exposure did not disrupt nematode development or lifespan, and induced only mild alterations in mitochondrial respiration, while having no effect on steady-state ATP levels. Next, we exposed nematodes with reduced mtDNA to the known and suspected mitochondrial toxicants aflatoxin B1, arsenite, paraquat, rotenone or ultraviolet C radiation (UVC). EtBr pre-exposure resulted in mild sensitization of nematodes to UVC and arsenite, had no effect on AfB1 and paraquat, and provided some protection from rotenone toxicity. These mixed results provide a first line of evidence suggesting that reduced mtDNA content may sensitize an individual to certain environmental exposures.
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Affiliation(s)
- Anthony L Luz
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, United States.
| | - Joel N Meyer
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, United States.
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30
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Behl M, Rice JR, Smith MV, Co CA, Bridge MF, Hsieh JH, Freedman JH, Boyd WA. Editor's Highlight: Comparative Toxicity of Organophosphate Flame Retardants and Polybrominated Diphenyl Ethers to Caenorhabditis elegans. Toxicol Sci 2016; 154:241-252. [PMID: 27566445 DOI: 10.1093/toxsci/kfw162] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
With the phasing-out of the polybrominated diphenyl ether (PBDE) flame retardants due to concerns regarding their potential developmental toxicity, the use of replacement compounds such as organophosphate flame retardants (OPFRs) has increased. Limited toxicity data are currently available to estimate the potential adverse health effects of the OPFRs. The toxicological effects of 4 brominated flame retardants, including 3 PBDEs and 3,3',5,5'-tetrabromobisphenol A, were compared with 6 aromatic OPFRs and 2 aliphatic OPFRs. The effects of these chemicals were determined using 3 biological endpoints in the nematode Caenorhabditis elegans (feeding, larval development, and reproduction). Because C. elegans development was previously reported to be sensitive to mitochondrial function, results were compared with those from an in vitro mitochondrial membrane permeabilization (MMP) assay. Overall 11 of the 12 flame retardants were active in 1 or more C. elegans biological endpoints, with only tris(2-chloroethyl) phosphate inactive across all endpoints including the in vitro MMP assay. For 2 of the C. elegans endpoints, at least 1 OPFR had similar toxicity to the PBDEs: triphenyl phosphate (TPHP) inhibited larval development at levels comparable to the 3 PBDEs; whereas TPHP and isopropylated phenol phosphate (IPP) affected C. elegans reproduction at levels similar to the PBDE commercial mixture, DE-71. The PBDEs reduced C. elegans feeding at lower concentrations than any OPFR. In addition, 9 of the 11 chemicals that inhibited C. elegans larval development also caused significant mitochondrial toxicity. These results suggest that some of the replacement aromatic OPFRs may have levels of toxicity comparable to PBDEs.
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Affiliation(s)
- Mamta Behl
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina
| | - Julie R Rice
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina
| | - Marjo V Smith
- Social & Scientific Systems, Inc., Durham, North Carolina
| | - Caroll A Co
- Social & Scientific Systems, Inc., Durham, North Carolina
| | | | - Jui-Hua Hsieh
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina
| | - Jonathan H Freedman
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, Kentucky
| | - Windy A Boyd
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina
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31
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Luz AL, Godebo TR, Bhatt DP, Ilkayeva OR, Maurer LL, Hirschey MD, Meyer JN. From the Cover: Arsenite Uncouples Mitochondrial Respiration and Induces a Warburg-like Effect in Caenorhabditis elegans. Toxicol Sci 2016; 152:349-62. [PMID: 27208080 PMCID: PMC4960910 DOI: 10.1093/toxsci/kfw093] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Millions of people worldwide are chronically exposed to arsenic through contaminated drinking water. Despite decades of research studying the carcinogenic potential of arsenic, the mechanisms by which arsenic causes cancer and other diseases remain poorly understood. Mitochondria appear to be an important target of arsenic toxicity. The trivalent arsenical, arsenite, can induce mitochondrial reactive oxygen species production, inhibit enzymes involved in energy metabolism, and induce aerobic glycolysis in vitro, suggesting that metabolic dysfunction may be important in arsenic-induced disease. Here, using the model organism Caenorhabditis elegans and a novel metabolic inhibition assay, we report an in vivo induction of aerobic glycolysis following arsenite exposure. Furthermore, arsenite exposure induced severe mitochondrial dysfunction, including altered pyruvate metabolism; reduced steady-state ATP levels, ATP-linked respiration and spare respiratory capacity; and increased proton leak. We also found evidence that induction of autophagy is an important protective response to arsenite exposure. Because these results demonstrate that mitochondria are an important in vivo target of arsenite toxicity, we hypothesized that deficiencies in mitochondrial electron transport chain genes, which cause mitochondrial disease in humans, would sensitize nematodes to arsenite. In agreement with this, nematodes deficient in electron transport chain complexes I, II, and III, but not ATP synthase, were sensitive to arsenite exposure, thus identifying a novel class of gene-environment interactions that warrant further investigation in the human populace.
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Affiliation(s)
- Anthony L Luz
- *Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Tewodros R Godebo
- *Nicholas School of the Environment, Duke University, Durham, North Carolina
| | | | - Olga R Ilkayeva
- Duke Molecular Physiology Institute Sarah W. Stedman Nutrition and Metabolism Center
| | - Laura L Maurer
- *Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Matthew D Hirschey
- Duke Molecular Physiology Institute Sarah W. Stedman Nutrition and Metabolism Center Departments of Medicine and Pharmacology & Cancer Biology, Duke University School of Medicine, Durham, North Carolina
| | - Joel N Meyer
- *Nicholas School of the Environment, Duke University, Durham, North Carolina
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32
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C. elegans screening strategies to identify pro-longevity interventions. Mech Ageing Dev 2016; 157:60-9. [PMID: 27473404 DOI: 10.1016/j.mad.2016.07.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 02/07/2023]
Abstract
Drugs screenings in search of enhancers or suppressors of selected readout(s) are nowadays mainly carried out in single cells systems. These approaches are however limited when searching for compounds with effects at the organismal level. To overcome this drawback the use of different model organisms to carry out modifier screenings has exponentially grown in the past decade. Unique characteristics such as easy manageability, low cost, fast reproductive cycle, short lifespan, simple anatomy and genetic amenability, make the nematode Caenorhabditis elegans especially suitable for this purpose. Here we briefly review the different high-throughput and high-content screenings which exploited the nematode to identify new compounds extending healthy lifespan. In this context, we describe our recently developed screening strategy to search for pro-longevity interventions taking advantage of the very reproducible phenotypes observed in C. elegans upon different degrees of mitochondrial stress. Indeed, in Mitochondrial mutants, the processes induced to cope with mild mitochondrial alterations during development, and ultimately extending animal lifespan, lead to reduced size and induction of specific stress responses. Instead, upon strong mitochondrial dysfunction, worms arrest their development. Exploiting these automatically quantifiable phenotypic readouts, we developed a new screening approach using the Cellomics ArrayScanVTI-HCS Reader and identified a new pro-longevity drug.
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33
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Maglioni S, Ventura N. C. elegans as a model organism for human mitochondrial associated disorders. Mitochondrion 2016; 30:117-25. [PMID: 26906059 DOI: 10.1016/j.mito.2016.02.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 02/05/2016] [Accepted: 02/17/2016] [Indexed: 12/16/2022]
Abstract
Mitochondria are small cytoplasmic organelles whose most important function is to provide the energy required by our cells and organism to live. To maintain an adequate mitochondrial homeostasis cells possess numerous mitochondrial quality controls and protective compensatory pathways, which can be activated to cope with a certain degree of mitochondrial dysfunction. However, when the mitochondrial damage is too severe and these defensive mechanisms are not anymore sufficient to deal with it, pathological signs arise. In the past few decades numerous genetic disorders ascribed to severe mitochondrial defects have been recognized with variable onset and symptomatology ranging from neuromuscular degeneration to cancer syndromes. Unfortunately, to date, only symptomatic and no curative therapies exist for most of these devastating, life-threatening disorders. Model organisms, and especially the nematode Caenorhabditis elegans, with its sequenced and highly conserved genome, and a simple but well-characterized nervous system, have enormously contributed in the past years to gain insight into the pathogenesis and treatment of different diseases. Here, we will summarize some of the advantages offered by the nematode system to model neurodegenerative diseases associated with mitochondrial electron transport chain defects and screen for therapeutic interventions.
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Affiliation(s)
- Silvia Maglioni
- IUF - Leibniz Research Institute for Environmental Medicine, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
| | - Natascia Ventura
- Institute for Clinical Chemistry and Laboratory Diagnostic, Medical Faculty of the Heinrich Heine University, Moorenstrasse 5, 40225 Düsseldorf, Germany; IUF - Leibniz Research Institute for Environmental Medicine, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
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34
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Wu N, Yang M, Gaur U, Xu H, Yao Y, Li D. Alpha-Ketoglutarate: Physiological Functions and Applications. Biomol Ther (Seoul) 2016; 24:1-8. [PMID: 26759695 PMCID: PMC4703346 DOI: 10.4062/biomolther.2015.078] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/21/2015] [Accepted: 08/28/2015] [Indexed: 11/05/2022] Open
Abstract
Alpha-ketoglutarate (AKG) is a key molecule in the Krebs cycle determining the overall rate of the citric acid cycle of the organism. It is a nitrogen scavenger and a source of glutamate and glutamine that stimulates protein synthesis and inhibits protein degradation in muscles. AKG as a precursor of glutamate and glutamine is a central metabolic fuel for cells of the gastrointestinal tract as well. AKG can decrease protein catabolism and increase protein synthesis to enhance bone tissue formation in the skeletal muscles and can be used in clinical applications. In addition to these health benefits, a recent study has shown that AKG can extend the lifespan of adult Caenorhabditis elegans by inhibiting ATP synthase and TOR. AKG not only extends lifespan, but also delays age-related disease. In this review, we will summarize the advances in AKG research field, in the content of its physiological functions and applications.
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Affiliation(s)
- Nan Wu
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, P.R. China
| | - Mingyao Yang
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, P.R. China
| | - Uma Gaur
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, P.R. China
| | - Huailiang Xu
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, P.R. China
| | - Yongfang Yao
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, P.R. China
| | - Diyan Li
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, P.R. China
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35
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Dancy BM, Brockway N, Ramadasan-Nair R, Yang Y, Sedensky MM, Morgan PG. Glutathione S-transferase mediates an ageing response to mitochondrial dysfunction. Mech Ageing Dev 2015; 153:14-21. [PMID: 26704446 DOI: 10.1016/j.mad.2015.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 12/03/2015] [Accepted: 12/10/2015] [Indexed: 12/30/2022]
Abstract
To understand primary mitochondrial disease, we utilized a complex I-deficient Caenorhabditis elegans mutant, gas-1. These animals strongly upregulate the expression of gst-14 (encoding a glutathione S-transferase). Knockdown of gst-14 dramatically extends the lifespan of gas-1 and increases hydroxynonenal (HNE) modified mitochondrial proteins without improving complex I function. We observed no change in reactive oxygen species levels as measured by Mitosox staining, consistent with a potential role of GST-14 in HNE clearance. The upregulation of gst-14 in gas-1 animals is specific to the pharynx. These data suggest that an HNE-mediated response in the pharynx could be beneficial for lifespan extension in the context of complex I dysfunction in C. elegans. Thus, whereas HNE is typically considered damaging, our work is consistent with recent reports of its role in signaling, and that in this case, the signal is pro-longevity in a model of mitochondrial dysfunction.
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Affiliation(s)
- Beverley M Dancy
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Nicole Brockway
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Renjini Ramadasan-Nair
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Yoing Yang
- Department of Genetics, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Margaret M Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, BB-1469, Seattle, WA 98195, USA.
| | - Philip G Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, BB-1469, Seattle, WA 98195, USA.
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36
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Cossard R, Esposito M, Sellem CH, Pitayu L, Vasnier C, Delahodde A, Dassa EP. Caenorhabditis elegans expressing the Saccharomyces cerevisiae NADH alternative dehydrogenase Ndi1p, as a tool to identify new genes involved in complex I related diseases. Front Genet 2015; 6:206. [PMID: 26124772 PMCID: PMC4463008 DOI: 10.3389/fgene.2015.00206] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 05/26/2015] [Indexed: 11/17/2022] Open
Abstract
Isolated complex I deficiencies are one of the most commonly observed biochemical features in patients suffering from mitochondrial disorders. In the majority of these clinical cases the molecular bases of the diseases remain unknown suggesting the involvement of unidentified factors that are critical for complex I function. The Saccharomyces cerevisiae NDI1 gene, encoding the mitochondrial internal NADH dehydrogenase was previously shown to complement a complex I deficient strain in Caenorhabditis elegans with notable improvements in reproduction and whole organism respiration. These features indicate that Ndi1p can functionally integrate the respiratory chain, allowing complex I deficiency complementation. Taking into account the Ndi1p ability to bypass complex I, we evaluate the possibility to extend the range of defects/mutations causing complex I deficiencies that can be alleviated by NDI1 expression. We report here that NDI1 expressing animals unexpectedly exhibit a slightly shortened lifespan, a reduction in the progeny, and a depletion of the mitochondrial genome. However, Ndi1p is expressed and targeted to the mitochondria as a functional protein that confers rotenone resistance to those animals without affecting their respiration rate and ATP content. We show that the severe embryonic lethality level caused by the RNAi knockdowns of complex I structural subunit encoding genes (e.g., NDUFV1, NDUFS1, NDUFS6, NDUFS8, or GRIM-19 human orthologs) in wild type animals is significantly reduced in the Ndi1p expressing worm. All together these results open up the perspective to identify new genes involved in complex I function, assembly, or regulation by screening an RNAi library of genes leading to embryonic lethality that should be rescued by NDI1 expression.
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Affiliation(s)
- Raynald Cossard
- I2BC, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud Orsay, France
| | - Michela Esposito
- I2BC, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud Orsay, France
| | - Carole H Sellem
- I2BC, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud Orsay, France
| | - Laras Pitayu
- I2BC, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud Orsay, France
| | - Christelle Vasnier
- I2BC, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud Orsay, France
| | - Agnès Delahodde
- I2BC, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud Orsay, France
| | - Emmanuel P Dassa
- I2BC, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud Orsay, France
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Neves A, Busso C, Gönczy P. Cellular hallmarks reveal restricted aerobic metabolism at thermal limits. eLife 2015; 4:e04810. [PMID: 25929283 PMCID: PMC4415524 DOI: 10.7554/elife.04810] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 04/02/2015] [Indexed: 12/24/2022] Open
Abstract
All organisms live within a given thermal range, but little is known about the mechanisms setting the limits of this range. We uncovered cellular features exhibiting signature changes at thermal limits in Caenorhabditis elegans embryos. These included changes in embryo size and shape, which were also observed in Caenorhabditis briggsae, indicating evolutionary conservation. We hypothesized that such changes could reflect restricted aerobic capacity at thermal limits. Accordingly, we uncovered that relative respiration in C. elegans embryos decreases at the thermal limits as compared to within the thermal range. Furthermore, by compromising components of the respiratory chain, we demonstrated that the reliance on aerobic metabolism is reduced at thermal limits. Moreover, embryos thus compromised exhibited signature changes in size and shape already within the thermal range. We conclude that restricted aerobic metabolism at the thermal limits contributes to setting the thermal range in a metazoan organism.
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Affiliation(s)
- Aitana Neves
- Swiss Institute of Experimental Cancer Research, Swiss Federal Institute of Technology, Lausanne, Switzerland
| | - Coralie Busso
- Swiss Institute of Experimental Cancer Research, Swiss Federal Institute of Technology, Lausanne, Switzerland
| | - Pierre Gönczy
- Swiss Institute of Experimental Cancer Research, Swiss Federal Institute of Technology, Lausanne, Switzerland
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38
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González-Hunt CP, Leung MCK, Bodhicharla RK, McKeever MG, Arrant AE, Margillo KM, Ryde IT, Cyr DD, Kosmaczewski SG, Hammarlund M, Meyer JN. Exposure to mitochondrial genotoxins and dopaminergic neurodegeneration in Caenorhabditis elegans. PLoS One 2014; 9:e114459. [PMID: 25486066 PMCID: PMC4259338 DOI: 10.1371/journal.pone.0114459] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 10/31/2014] [Indexed: 12/12/2022] Open
Abstract
Neurodegeneration has been correlated with mitochondrial DNA (mtDNA) damage and exposure to environmental toxins, but causation is unclear. We investigated the ability of several known environmental genotoxins and neurotoxins to cause mtDNA damage, mtDNA depletion, and neurodegeneration in Caenorhabditis elegans. We found that paraquat, cadmium chloride and aflatoxin B1 caused more mitochondrial than nuclear DNA damage, and paraquat and aflatoxin B1 also caused dopaminergic neurodegeneration. 6-hydroxydopamine (6-OHDA) caused similar levels of mitochondrial and nuclear DNA damage. To further test whether the neurodegeneration could be attributed to the observed mtDNA damage, C. elegans were exposed to repeated low-dose ultraviolet C radiation (UVC) that resulted in persistent mtDNA damage; this exposure also resulted in dopaminergic neurodegeneration. Damage to GABAergic neurons and pharyngeal muscle cells was not detected. We also found that fasting at the first larval stage was protective in dopaminergic neurons against 6-OHDA-induced neurodegeneration. Finally, we found that dopaminergic neurons in C. elegans are capable of regeneration after laser surgery. Our findings are consistent with a causal role for mitochondrial DNA damage in neurodegeneration, but also support non mtDNA-mediated mechanisms.
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Affiliation(s)
- Claudia P. González-Hunt
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Maxwell C. K. Leung
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Rakesh K. Bodhicharla
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Madeline G. McKeever
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Andrew E. Arrant
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Kathleen M. Margillo
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Ian T. Ryde
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
| | - Derek D. Cyr
- Center for Applied Genomics and Technology, Duke University, Durham, North Carolina, United States of America
| | - Sara G. Kosmaczewski
- Department of Genetics, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Marc Hammarlund
- Department of Genetics, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Joel N. Meyer
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
- * E-mail: mailto:
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39
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Effects of the mitochondrial respiratory chain on longevity in C. elegans. Exp Gerontol 2014; 56:245-55. [DOI: 10.1016/j.exger.2014.03.028] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/27/2014] [Accepted: 03/28/2014] [Indexed: 12/21/2022]
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40
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Hur JH, Stork DA, Walker DW. Complex-I-ty in aging. J Bioenerg Biomembr 2014; 46:329-35. [PMID: 24961226 DOI: 10.1007/s10863-014-9553-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 06/02/2014] [Indexed: 01/02/2023]
Abstract
The role of mitochondrial complex I in aging has been studied in both C. elegans and Drosophila, where RNAi knock down of specific complex I subunits has been shown to extend lifespan. More recently, studies in Drosophila have shown that an increase in mitochondrial activity, including complex I-like activity, can also slow aging. In this review, we discuss this apparent paradox. Improved maintenance of mitochondrial activity, mitochondrial homeostasis, may be responsible for lifespan extension in both cases. Decreased electron transport chain activity caused by reducing complex I subunit expression prompts an increase in stress response signaling that leads to enhanced mitochondrial homeostasis during aging. Increased complex I activity, as well as mitochondrial biogenesis, is expected to both directly counteract the decline in mitochondrial health that occurs during aging and may also increase cellular NAD(+) levels, which have been linked to mitochondrial homeostatic mechanisms through activation of sirtuins. We suggest that manipulations that increase or decrease complex I activity both converge on improved mitochondrial homeostasis during aging, resulting in prolonged lifespan.
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Affiliation(s)
- Jae H Hur
- Department of Biology, Harvey Mudd College, Claremont, CA, 91711, USA,
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41
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A method to identify and validate mitochondrial modulators using mammalian cells and the worm C. elegans. Sci Rep 2014; 4:5285. [PMID: 24923838 PMCID: PMC4055904 DOI: 10.1038/srep05285] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 05/21/2014] [Indexed: 12/21/2022] Open
Abstract
Mitochondria are semi-autonomous organelles regulated by a complex network of proteins that are vital for many cellular functions. Because mitochondrial modulators can impact many aspects of cellular homeostasis, their identification and validation has proven challenging. It requires the measurement of multiple parameters in parallel to understand the exact nature of the changes induced by such compounds. We developed a platform of assays scoring for mitochondrial function in two complementary models systems, mammalian cells and C. elegans. We first optimized cell culture conditions and established the mitochondrial signature of 1,200 FDA-approved drugs in liver cells. Using cell-based and C. elegans assays, we further defined the metabolic effects of two pharmacological classes that emerged from our hit list, i.e. imidazoles and statins. We found that these two drug classes affect respiration through different and cholesterol-independent mechanisms in both models. Our screening strategy enabled us to unequivocally identify compounds that have toxic or beneficial effects on mitochondrial activity. Furthermore, the cross-species approach provided novel mechanistic insight and allowed early validation of hits that act on mitochondrial function.
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42
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Chin RM, Fu X, Pai MY, Vergnes L, Hwang H, Deng G, Diep S, Lomenick B, Meli VS, Monsalve GC, Hu E, Whelan SA, Wang JX, Jung G, Solis GM, Fazlollahi F, Kaweeteerawat C, Quach A, Nili M, Krall AS, Godwin HA, Chang HR, Faull KF, Guo F, Jiang M, Trauger SA, Saghatelian A, Braas D, Christofk HR, Clarke CF, Teitell MA, Petrascheck M, Reue K, Jung ME, Frand AR, Huang J. The metabolite α-ketoglutarate extends lifespan by inhibiting ATP synthase and TOR. Nature 2014; 510:397-401. [PMID: 24828042 DOI: 10.1038/nature13264] [Citation(s) in RCA: 414] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 03/17/2014] [Indexed: 12/11/2022]
Abstract
Metabolism and ageing are intimately linked. Compared with ad libitum feeding, dietary restriction consistently extends lifespan and delays age-related diseases in evolutionarily diverse organisms. Similar conditions of nutrient limitation and genetic or pharmacological perturbations of nutrient or energy metabolism also have longevity benefits. Recently, several metabolites have been identified that modulate ageing; however, the molecular mechanisms underlying this are largely undefined. Here we show that α-ketoglutarate (α-KG), a tricarboxylic acid cycle intermediate, extends the lifespan of adult Caenorhabditis elegans. ATP synthase subunit β is identified as a novel binding protein of α-KG using a small-molecule target identification strategy termed drug affinity responsive target stability (DARTS). The ATP synthase, also known as complex V of the mitochondrial electron transport chain, is the main cellular energy-generating machinery and is highly conserved throughout evolution. Although complete loss of mitochondrial function is detrimental, partial suppression of the electron transport chain has been shown to extend C. elegans lifespan. We show that α-KG inhibits ATP synthase and, similar to ATP synthase knockdown, inhibition by α-KG leads to reduced ATP content, decreased oxygen consumption, and increased autophagy in both C. elegans and mammalian cells. We provide evidence that the lifespan increase by α-KG requires ATP synthase subunit β and is dependent on target of rapamycin (TOR) downstream. Endogenous α-KG levels are increased on starvation and α-KG does not extend the lifespan of dietary-restricted animals, indicating that α-KG is a key metabolite that mediates longevity by dietary restriction. Our analyses uncover new molecular links between a common metabolite, a universal cellular energy generator and dietary restriction in the regulation of organismal lifespan, thus suggesting new strategies for the prevention and treatment of ageing and age-related diseases.
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Affiliation(s)
- Randall M Chin
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Xudong Fu
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Melody Y Pai
- 1] Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA [2]
| | - Laurent Vergnes
- 1] Department of Human Genetics, University of California Los Angeles, Los Angeles, California 90095, USA [2]
| | - Heejun Hwang
- 1] Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA [2]
| | - Gang Deng
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Simon Diep
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Brett Lomenick
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Vijaykumar S Meli
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Gabriela C Monsalve
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Eileen Hu
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Stephen A Whelan
- Department of Surgery, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Jennifer X Wang
- Small Molecule Mass Spectrometry Facility, FAS Division of Science, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Gwanghyun Jung
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Gregory M Solis
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Farbod Fazlollahi
- Pasarow Mass Spectrometry Laboratory, Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Chitrada Kaweeteerawat
- Department of Environmental Health Sciences, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Austin Quach
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Mahta Nili
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Abby S Krall
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Hilary A Godwin
- Department of Environmental Health Sciences, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Helena R Chang
- Department of Surgery, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Kym F Faull
- Pasarow Mass Spectrometry Laboratory, Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Feng Guo
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Meisheng Jiang
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Sunia A Trauger
- Small Molecule Mass Spectrometry Facility, FAS Division of Science, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Alan Saghatelian
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Daniel Braas
- 1] Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA [2] UCLA Metabolomics Center, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Heather R Christofk
- 1] Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA [2] UCLA Metabolomics Center, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Catherine F Clarke
- 1] Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA [2] Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Michael A Teitell
- 1] Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA [2] Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Michael Petrascheck
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Karen Reue
- 1] Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA [2] Department of Human Genetics, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Michael E Jung
- 1] Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA [2] Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Alison R Frand
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Jing Huang
- 1] Molecular Biology Institute, University of California Los Angeles, Los Angeles, California 90095, USA [2] Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California 90095, USA
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43
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Segref A, Kevei É, Pokrzywa W, Schmeisser K, Mansfeld J, Livnat-Levanon N, Ensenauer R, Glickman MH, Ristow M, Hoppe T. Pathogenesis of human mitochondrial diseases is modulated by reduced activity of the ubiquitin/proteasome system. Cell Metab 2014; 19:642-52. [PMID: 24703696 DOI: 10.1016/j.cmet.2014.01.016] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/29/2013] [Accepted: 01/22/2014] [Indexed: 11/18/2022]
Abstract
Mitochondria maintain cellular homeostasis by coordinating ATP synthesis with metabolic activity, redox signaling, and apoptosis. Excessive levels of mitochondria-derived reactive oxygen species (ROS) promote mitochondrial dysfunction, triggering numerous metabolic disorders. However, the molecular basis for the harmful effects of excessive ROS formation is largely unknown. Here, we identify a link between mitochondrial stress and ubiquitin-dependent proteolysis, which supports cellular surveillance both in Caenorhabditis elegans and humans. Worms defective in respiration with elevated ROS levels are limited in turnover of a GFP-based substrate protein, demonstrating that mitochondrial stress affects the ubiquitin/proteasome system (UPS). Intriguingly, we observed similar proteolytic defects for disease-causing IVD and COX1 mutations associated with mitochondrial failure in humans. Together, these results identify a conserved link between mitochondrial metabolism and ubiquitin-dependent proteostasis. Reduced UPS activity during pathological conditions might potentiate disease progression and thus provides a valuable target for therapeutic intervention.
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Affiliation(s)
- Alexandra Segref
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany
| | - Éva Kevei
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany
| | - Wojciech Pokrzywa
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany
| | - Kathrin Schmeisser
- Department of Human Nutrition, Institute of Nutrition, University of Jena, 07743 Jena, Germany
| | - Johannes Mansfeld
- Department of Human Nutrition, Institute of Nutrition, University of Jena, 07743 Jena, Germany; Energy Metabolism Laboratory, ETH Zürich, Schwerzenbach/Zürich, CH 8603, Switzerland
| | - Nurit Livnat-Levanon
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Regina Ensenauer
- Research Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, 80337 Munich, Germany
| | - Michael H Glickman
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Michael Ristow
- Department of Human Nutrition, Institute of Nutrition, University of Jena, 07743 Jena, Germany; Energy Metabolism Laboratory, ETH Zürich, Schwerzenbach/Zürich, CH 8603, Switzerland
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany.
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44
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Rawson RL, Yam L, Weimer RM, Bend EG, Hartwieg E, Horvitz HR, Clark SG, Jorgensen EM. Axons degenerate in the absence of mitochondria in C. elegans. Curr Biol 2014; 24:760-5. [PMID: 24631238 DOI: 10.1016/j.cub.2014.02.025] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 01/07/2014] [Accepted: 02/11/2014] [Indexed: 01/21/2023]
Abstract
Many neurodegenerative disorders are associated with mitochondrial defects [1-3]. Mitochondria can play an active role in degeneration by releasing reactive oxygen species and apoptotic factors [4-7]. Alternatively, mitochondria can protect axons from stress and insults, for example by buffering calcium [8]. Recent studies manipulating mitochondria lend support to both of these models [9-13]. Here, we identify a C. elegans mutant, ric-7, in which mitochondria are unable to exit the neuron cell bodies, similar to the kinesin-1/unc-116 mutant. When axons lacking mitochondria are cut with a laser, they rapidly degenerate. Some neurons even spontaneously degenerate in ric-7 mutants. Degeneration can be suppressed by forcing mitochondria into the axons of the mutants. The protective effect of mitochondria is also observed in the wild-type: a majority of axon fragments containing a mitochondrion survive axotomy, whereas those lacking mitochondria degenerate. Thus, mitochondria are not required for axon degeneration and serve a protective role in C. elegans axons.
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Affiliation(s)
- Randi L Rawson
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Lung Yam
- Molecular Neurobiology Program, Department of Pharmacology, Skirball Institute, NYU School of Medicine, New York, NY 10016, USA
| | - Robby M Weimer
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Eric G Bend
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Erika Hartwieg
- Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - H Robert Horvitz
- Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Scott G Clark
- Molecular Neurobiology Program, Department of Pharmacology, Skirball Institute, NYU School of Medicine, New York, NY 10016, USA
| | - Erik M Jorgensen
- Department of Biology and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-0840, USA.
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45
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Pathological Mutations of the Mitochondrial Human Genome: the Instrumental Role of the Yeast S. cerevisiae. Diseases 2014. [DOI: 10.3390/diseases2010024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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46
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Bodhicharla R, Ryde IT, Prasad GL, Meyer JN. The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces mitochondrial and nuclear DNA damage in Caenorhabditis elegans. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2014; 55:43-50. [PMID: 24014178 DOI: 10.1002/em.21815] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 08/09/2013] [Accepted: 08/09/2013] [Indexed: 06/02/2023]
Abstract
The metabolites of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) form DNA adducts in animal models. While there are many reports of formation of nuclear DNA adducts, one report also detected NNK-induced damage to the mitochondrial genome in rats. Using a different DNA damage detection technology, we tested whether this finding could be repeated in the nematode Caenorhabditis elegans. We treated N2 strain (wild-type) nematodes with NNK in liquid culture, and applied quantitative PCR to analyze NNK-induced nuclear and mitochondrial DNA (mtDNA) damage. Our results confirm that NNK causes both nuclear and mtDNA damage. However, we did not detect a difference in the level of nuclear versus mtDNA damage in C. elegans. To test whether the mtDNA damage was associated with mitochondrial dysfunction, we used a transgenic nematode strain that permits in vivo measurement of ATP levels and found lower levels of ATP in NNK-exposed animals when compared with the unexposed controls. To test whether the lower levels of ATP could be attributed to inhibition of respiratory chain components, we investigated oxygen consumption in whole C. elegans and found reduced oxygen consumption in exposed animals when compared with the unexposed controls. Our data suggest a model in which NNK exposure causes damage to both C. elegans nuclear and mitochondrial genomes, and support the hypothesis that the mitochondrial damage is functionally important in this model. These results also represent a first step in developing this genetically tractable organism as a model for assessing NNK toxicity.
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Affiliation(s)
- Rakesh Bodhicharla
- Nicholas School of the Environment, Duke University, Durham, North Carolina
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47
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Rolland SG, Motori E, Memar N, Hench J, Frank S, Winklhofer KF, Conradt B. Impaired complex IV activity in response to loss of LRPPRC function can be compensated by mitochondrial hyperfusion. Proc Natl Acad Sci U S A 2013; 110:E2967-76. [PMID: 23878239 PMCID: PMC3740885 DOI: 10.1073/pnas.1303872110] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial morphology changes in response to various stimuli but the significance of this is unclear. In a screen for mutants with abnormal mitochondrial morphology, we identified MMA-1, the Caenorhabditis elegans homolog of the French Canadian Leigh Syndrome protein LRPPRC (leucine-rich pentatricopeptide repeat containing). We demonstrate that reducing mma-1 or LRPPRC function causes mitochondrial hyperfusion. Reducing mma-1/LRPPRC function also decreases the activity of complex IV of the electron transport chain, however without affecting cellular ATP levels. Preventing mitochondrial hyperfusion in mma-1 animals causes larval arrest and embryonic lethality. Furthermore, prolonged LRPPRC knock-down in mammalian cells leads to mitochondrial fragmentation and decreased levels of ATP. These findings indicate that in a mma-1/LRPPRC-deficient background, hyperfusion allows mitochondria to maintain their functions despite a reduction in complex IV activity. Our data reveal an evolutionary conserved mechanism that is triggered by reduced complex IV function and that induces mitochondrial hyperfusion to transiently compensate for a drop in the activity of the electron transport chain.
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Affiliation(s)
- Stéphane G. Rolland
- Department Biology II, Center for Integrated Protein Science, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Elisa Motori
- Department of Neurobiochemistry, Adolf Butenandt Institute, Ludwig-Maximilians-University, 80336 Munich, Germany
- Department of Life Quality Studies–Alma Mater Studiorum, University of Bologna, 40126 Bologna, Italy
| | - Nadin Memar
- Department Biology II, Center for Integrated Protein Science, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Jürgen Hench
- Department of Neuropathology, Institute for Pathology, University Hospitals Basel, CH-4031 Basel, Switzerland
| | - Stephan Frank
- Department of Neuropathology, Institute for Pathology, University Hospitals Basel, CH-4031 Basel, Switzerland
| | - Konstanze F. Winklhofer
- Department of Neurobiochemistry, Adolf Butenandt Institute, Ludwig-Maximilians-University, 80336 Munich, Germany
- German Center for Neurodegenerative Diseases, 80336 Munich, Germany
- Munich Cluster for Systems Neurology, 80336 Munich, Germany; and
- Department of Molecular Cell Biology, Institute of Physiological Chemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Barbara Conradt
- Department Biology II, Center for Integrated Protein Science, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
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Molecular characterisation of the recovery process in the entomopathogenic nematode Heterorhabditis bacteriophora. Int J Parasitol 2013; 43:843-52. [PMID: 23806512 DOI: 10.1016/j.ijpara.2013.05.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/13/2013] [Accepted: 05/14/2013] [Indexed: 11/21/2022]
Abstract
In Heterorhabditis bacteriophora, an insect-parasitic nematode, the third juvenile is the infective, developmentally arrested form. When it infects a suitable host, the infective juvenile recovers from developmental arrest and resumes growth and development. This process is called recovery and it is the first outcome of the host-parasite interaction. Recovery is also very important from a commercial point of view. To characterise the recovery in H. bacteriophora, we sought to identify genes involved in this process. A large-scale bioassay for recovery was established and subtraction libraries of recovering infective juvenile from arrested infective juvenile transcripts were constructed at different time points. Most of the genes identified as differentially expressed between recovering and developmentally arrested infective juveniles belonged to metabolic pathways. Elevated expression levels of 23 selected genes during recovery were confirmed by quantitative PCR. For eight of these genes, transcription silencing in H. bacteriophora resulted in a significant decline in infective juvenile recovery rates, suggesting that these genes are critical to the recovery process. Two of the genes were associated with the insulin-like growth factor-1 (insulin/IGF-1) pathway, known to regulate dauer formation in the free-living nematode Caenorhabditis elegans, whereas the other six genes were associated with pathways not previously associated with recovery in nematodes. These results suggest that although little is known about parasitism-unique genes, the pathways regulating recovery in H. bacteriophora include those activated in C. elegans and those that might be unique to parasitic nematodes; the latter may be activated in response to host signals and enable the parasite to recognise its host.
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Maxwell S, Harding J, Brabin C, Appleford PJ, Brown R, Delaney C, Brown G, Woollard A. The SFT-1 and OXA-1 respiratory chain complex assembly factors influence lifespan by distinct mechanisms in C. elegans. LONGEVITY & HEALTHSPAN 2013; 2:9. [PMID: 24472117 PMCID: PMC3922957 DOI: 10.1186/2046-2395-2-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 03/25/2013] [Indexed: 01/09/2023]
Abstract
Background C. elegans mitochondrial (Mit) mutants have disrupted mitochondrial electron transport chain function, yet, surprisingly, they are often long-lived, a property that has offered unique insights into the molecular mechanisms of aging. In this study, we examine the phenotypic consequences of reducing the expression of the respiratory chain complex assembly factors sft-1 (homologous to human SURF1) and oxa-1 (homologous to human OXA1) by RNA interference (RNAi). Mutations in human SURF1 are associated with Leigh syndrome, a neurodegenerative condition of the brain caused by cytochrome oxidase (COX) deficiency. Both SURF1 and OXA1 are integral proteins of the inner mitochondrial membrane, functioning in the COX assembly pathway. Results RNAi of both of these genes in C. elegans is associated with increased longevity, but the mechanism by which lifespan is extended is different in each case. sft-1(RNAi) animals display lifespan extension that is dependent on the daf-16 insulin-like signaling pathway, and associated with sensitivity to oxidative stress. oxa-1(RNAi) animals, in contrast, exhibit increased longevity that is at least partially independent of daf-16, and associated with a reduced developmental rate and increased resistance to oxidative stress. Conclusions This study further delineates the consequences of mitochondrial dysfunction within a whole organism that will ultimately help provide new models for human mitochondrial-associated diseases. The difference in phenotype observed upon down-regulation of these two COX assembly factors, as well as phenotypic differences between these factors and other respiratory chain components analyzed thus far, illustrates the complex inter-relationships that exist among energy metabolism, reproduction and aging even in this simplest of metazoan model organisms.
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Affiliation(s)
| | | | | | | | | | | | | | - Alison Woollard
- Biochemistry Department, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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Meyer JN, Leung MCK, Rooney JP, Sendoel A, Hengartner MO, Kisby GE, Bess AS. Mitochondria as a target of environmental toxicants. Toxicol Sci 2013; 134:1-17. [PMID: 23629515 PMCID: PMC3693132 DOI: 10.1093/toxsci/kft102] [Citation(s) in RCA: 350] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Enormous strides have recently been made in our understanding of the biology and pathobiology of mitochondria. Many diseases have been identified as caused by mitochondrial dysfunction, and many pharmaceuticals have been identified as previously unrecognized mitochondrial toxicants. A much smaller but growing literature indicates that mitochondria are also targeted by environmental pollutants. We briefly review the importance of mitochondrial function and maintenance for health based on the genetics of mitochondrial diseases and the toxicities resulting from pharmaceutical exposure. We then discuss how the principles of mitochondrial vulnerability illustrated by those fields might apply to environmental contaminants, with particular attention to factors that may modulate vulnerability including genetic differences, epigenetic interactions, tissue characteristics, and developmental stage. Finally, we review the literature related to environmental mitochondrial toxicants, with a particular focus on those toxicants that target mitochondrial DNA. We conclude that the fields of environmental toxicology and environmental health should focus more strongly on mitochondria.
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Affiliation(s)
- Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC, USA.
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