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Osiewacz HD. Impact of Mitochondrial Architecture, Function, Redox Homeostasis, and Quality Control on Organismic Aging: Lessons from a Fungal Model System. Antioxid Redox Signal 2024; 40:948-967. [PMID: 38019044 DOI: 10.1089/ars.2023.0487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
Significance: Mitochondria are eukaryotic organelles with various essential functions. They are both the source and the targets of reactive oxygen species (ROS). Different branches of a mitochondrial quality control system (mQCS), such as ROS balancing, degradation of damaged proteins, or whole mitochondria, can mitigate the adverse effects of ROS stress. However, the capacity of mQCS is limited. Overwhelming this capacity leads to dysfunctions and aging. Strategies to interfere into mitochondria-dependent human aging with the aim to increase the healthy period of life, the health span, rely on the precise knowledge of mitochondrial functions. Experimental models such as Podospora anserina, a filamentous fungus with a clear mitochondrial aging etiology, proved to be instrumental to reach this goal. Recent Advances: Investigations of the P. anserina mQCS revealed that it is constituted by a complex network of different branches. Moreover, mitochondrial architecture and lipid homeostasis emerged to affect aging. Critical Issues: The regulation of the mQCS is only incompletely understood. Details about the involved signaling molecules and interacting pathways remain to be elucidated. Moreover, most of the currently generated experimental data were generated in well-controlled experiments that do not reflect the constantly changing natural life conditions and bear the danger to miss relevant aspects leading to incorrect conclusions. Future Directions: In P. anserina, the precise impact of redox signaling as well as of molecular damaging for aging remains to be defined. Moreover, natural fluctuation of environmental conditions needs to be considered to generate a realistic picture of aging mechanisms as they developed during evolution.
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Relationship between oxidative stress and lifespan in Daphnia pulex. Sci Rep 2022; 12:2354. [PMID: 35149730 PMCID: PMC8837783 DOI: 10.1038/s41598-022-06279-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 01/04/2022] [Indexed: 11/23/2022] Open
Abstract
Macromolecular damage leading to cell, tissue and ultimately organ dysfunction is a major contributor to aging. Intracellular reactive oxygen species (ROS) resulting from normal metabolism cause most damage to macromolecules and the mitochondria play a central role in this process as they are the principle source of ROS. The relationship between naturally occurring variations in the mitochondrial (MT) genomes leading to correspondingly less or more ROS and macromolecular damage that changes the rate of aging associated organismal decline remains relatively unexplored. MT complex I, a component of the electron transport chain (ETC), is a key source of ROS and the NADH dehydrogenase subunit 5 (ND5) is a highly conserved core protein of the subunits that constitute the backbone of complex I. Using Daphnia as a model organism, we explored if the naturally occurring sequence variations in ND5 correlate with a short or long lifespan. Our results indicate that the short-lived clones have ND5 variants that correlate with reduced complex I activity, increased oxidative damage, and heightened expression of ROS scavenger enzymes. Daphnia offers a unique opportunity to investigate the association between inherited variations in components of complex I and ROS generation which affects the rate of aging and lifespan.
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Mitochondrial Phospholipid Homeostasis Is Regulated by the i-AAA Protease PaIAP and Affects Organismic Aging. Cells 2021; 10:cells10102775. [PMID: 34685755 PMCID: PMC8534651 DOI: 10.3390/cells10102775] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 11/27/2022] Open
Abstract
Mitochondria are ubiquitous organelles of eukaryotic organisms with a number of essential functions, including synthesis of iron-sulfur clusters, amino acids, lipids, and adenosine triphosphate (ATP). During aging of the fungal aging model Podospora anserina, the inner mitochondrial membrane (IMM) undergoes prominent morphological alterations, ultimately resulting in functional impairments. Since phospholipids (PLs) are key components of biological membranes, maintenance of membrane plasticity and integrity via regulation of PL biosynthesis is indispensable. Here, we report results from a lipidomic analysis of isolated mitochondria from P. anserina that revealed an age-related reorganization of the mitochondrial PL profile and the involvement of the i-AAA protease PaIAP in proteolytic regulation of PL metabolism. The absence of PaIAP enhances biosynthesis of characteristic mitochondrial PLs, leads to significant alterations in the acyl composition of the mitochondrial signature PL cardiolipin (CL), and induces mitophagy. These alterations presumably cause the lifespan increase of the PaIap deletion mutant under standard growth conditions. However, PaIAP is required at elevated temperatures and for degradation of superfluous CL synthase PaCRD1 during glycolytic growth. Overall, our study uncovers a prominent role of PaIAP in the regulation of PL homeostasis in order to adapt membrane plasticity to fluctuating environmental conditions as they occur in nature.
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Proteomic analysis demonstrates the role of the quality control protease LONP1 in mitochondrial protein aggregation. J Biol Chem 2021; 297:101134. [PMID: 34461102 PMCID: PMC8503632 DOI: 10.1016/j.jbc.2021.101134] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/23/2021] [Accepted: 08/26/2021] [Indexed: 11/20/2022] Open
Abstract
The mitochondrial matrix protease LONP1 is an essential part of the organellar protein quality control system. LONP1 has been shown to be involved in respiration control and apoptosis. Furthermore, a reduction in LONP1 level correlates with aging. Up to now, the effects of a LONP1 defect were mostly studied by utilizing transient, siRNA-mediated knockdown approaches. We generated a new cellular model system for studying the impact of LONP1 on mitochondrial protein homeostasis by a CRISPR/Cas-mediated genetic knockdown (gKD). These cells showed a stable reduction of LONP1 along with a mild phenotype characterized by absent morphological differences and only small negative effects on mitochondrial functions under normal culture conditions. To assess the consequences of a permanent LONP1 depletion on the mitochondrial proteome, we analyzed the alterations of protein levels by quantitative mass spectrometry, demonstrating small adaptive changes, in particular with respect to mitochondrial protein biogenesis. In an additional proteomic analysis, we determined the temperature-dependent aggregation behavior of mitochondrial proteins and its dependence on a reduction of LONP1 activity, demonstrating the important role of the protease for mitochondrial protein homeostasis in mammalian cells. We identified a significant number of mitochondrial proteins that are affected by a reduced LONP1 activity especially with respect to their stress-induced solubility. Taken together, our results suggest a very good applicability of the LONP1 gKD cell line as a model system for human aging processes.
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Nesci S, Trombetti F, Pagliarani A, Ventrella V, Algieri C, Tioli G, Lenaz G. Molecular and Supramolecular Structure of the Mitochondrial Oxidative Phosphorylation System: Implications for Pathology. Life (Basel) 2021; 11:242. [PMID: 33804034 PMCID: PMC7999509 DOI: 10.3390/life11030242] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 02/07/2023] Open
Abstract
Under aerobic conditions, mitochondrial oxidative phosphorylation (OXPHOS) converts the energy released by nutrient oxidation into ATP, the currency of living organisms. The whole biochemical machinery is hosted by the inner mitochondrial membrane (mtIM) where the protonmotive force built by respiratory complexes, dynamically assembled as super-complexes, allows the F1FO-ATP synthase to make ATP from ADP + Pi. Recently mitochondria emerged not only as cell powerhouses, but also as signaling hubs by way of reactive oxygen species (ROS) production. However, when ROS removal systems and/or OXPHOS constituents are defective, the physiological ROS generation can cause ROS imbalance and oxidative stress, which in turn damages cell components. Moreover, the morphology of mitochondria rules cell fate and the formation of the mitochondrial permeability transition pore in the mtIM, which, most likely with the F1FO-ATP synthase contribution, permeabilizes mitochondria and leads to cell death. As the multiple mitochondrial functions are mutually interconnected, changes in protein composition by mutations or in supercomplex assembly and/or in membrane structures often generate a dysfunctional cascade and lead to life-incompatible diseases or severe syndromes. The known structural/functional changes in mitochondrial proteins and structures, which impact mitochondrial bioenergetics because of an impaired or defective energy transduction system, here reviewed, constitute the main biochemical damage in a variety of genetic and age-related diseases.
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Affiliation(s)
- Salvatore Nesci
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Fabiana Trombetti
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Alessandra Pagliarani
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Vittoria Ventrella
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Cristina Algieri
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Gaia Tioli
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
| | - Giorgio Lenaz
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
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Heinz D, Krotova E, Hamann A, Osiewacz HD. Simultaneous Ablation of the Catalytic AMPK α-Subunit SNF1 and Mitochondrial Matrix Protease CLPP Results in Pronounced Lifespan Extension. Front Cell Dev Biol 2021; 9:616520. [PMID: 33748105 PMCID: PMC7969656 DOI: 10.3389/fcell.2021.616520] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/27/2021] [Indexed: 12/21/2022] Open
Abstract
Organismic aging is known to be controlled by genetic and environmental traits. Pathways involved in the control of cellular metabolism play a crucial role. Previously, we identified a role of PaCLPP, a mitochondrial matrix protease, in the control of the mitochondrial energy metabolism, aging, and lifespan of the fungal aging model Podospora anserina. Most surprisingly, we made the counterintuitive observation that the ablation of this component of the mitochondrial quality control network leads to lifespan extension. In the current study, we investigated the role of energy metabolism of P. anserina. An age-dependent metabolome analysis of the wild type and a PaClpP deletion strain verified differences and changes of various metabolites in cultures of the PaClpP mutant and the wild type. Based on these data, we generated and analyzed a PaSnf1 deletion mutant and a ΔPaSnf1/ΔPaClpP double mutant. In both mutants PaSNF1, the catalytic α-subunit of AMP-activated protein kinase (AMPK) is ablated. PaSNF1 was found to be required for the development of fruiting bodies and ascospores and the progeny of sexual reproduction of this ascomycete and impact mitochondrial dynamics and autophagy. Most interestingly, while the single PaSnf1 deletion mutant is characterized by a slight lifespan increase, simultaneous deletion of PaSnf1 and PaClpP leads to a pronounced lifespan extension. This synergistic effect is strongly reinforced in the presence of the mating-type "minus"-linked allele of the rmp1 gene. Compared to the wild type, culture temperature of 35°C instead of the standard laboratory temperature of 27°C leads to a short-lived phenotype of the ΔPaSnf1/ΔPaClpP double mutant. Overall, our study provides novel evidence for complex interactions of different molecular pathways involved in mitochondrial quality control, gene expression, and energy metabolism in the control of organismic aging.
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Affiliation(s)
| | | | | | - Heinz D. Osiewacz
- Institute of Molecular Biosciences, J.W. Goethe University, Frankfurt am Main, Germany
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Trivedi R, Jurivich DA. A molecular perspective on age-dependent changes to the heat shock axis. Exp Gerontol 2020; 137:110969. [PMID: 32407864 DOI: 10.1016/j.exger.2020.110969] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 04/13/2020] [Accepted: 05/05/2020] [Indexed: 12/20/2022]
Abstract
Aging is a complex process associated with progressive damage that leads to cellular dysfunction often accompanied by frailty and age-related diseases. Coping with all types of physiologic stress declines with age. While representing a primordial, cross-species response in poikilo- and homeotherms, the age-dependent perturbation of the stress response is more complex than previously thought. This short review examines how age influences the stress axis at multiple levels that involve both activating and attenuating pathways.
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Affiliation(s)
- Rachana Trivedi
- Department of Geriatrics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, USA.
| | - Donald A Jurivich
- Department of Geriatrics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, USA.
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Valentine C, Ohnishi K, Irie K, Murakami A. Curcumin may induce lipolysis via proteo-stress in Huh7 human hepatoma cells. J Clin Biochem Nutr 2019; 65:91-98. [PMID: 31592057 DOI: 10.3164/jcbn.19-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/02/2019] [Indexed: 12/25/2022] Open
Abstract
Curcumin has been shown to have anti-obesity effects in animal studies. Although several molecular mechanisms of action have been reported, the initial or upstream molecular events remain to be revealed. In this study, we found that curcumin or heat shock treatment up-regulated the expression of adipose triglyceride lipase (ATGL) in Huh7 hepatoma cells, which resulted in acceleration of lipolysis. Interestingly, perturbation of protein homeostasis was seen in curcumin-treated cells, as detected by formation of numerous ubiquitinated proteins and conjugated proteins with p62 (SQSTM). Curcumin activated the protein expression of molecular chaperones, such as heat shock protein (HSP)40 and HSP70. Pre-treatment of the cells with 4-phenylbutyric acid, a chemical chaperone, suppressed proteo-stress induced by curcumin and reduced its lipolysis effect. Importantly, the cytotoxicity of curcumin was markedly alleviated when intracellular triglyceride was consumed by the polyphenol. Thus, energy supplementation from lipolysis may play substantial roles in adaptation and survival of curcumin-exposed cells. To support this notion, the cytotoxicity of curcumin was aggravated in ATGL-knockdown cells. Curcumin decreased intracellular ATP for activating AMP-activated protein kinase, which initiates catabolic pathways including ATGL-dependent lipolysis. Taken together, we propose a hypothesis that curcumin induces lipolysis to compensate for ATP reduction due to its proteo-stress effects.
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Affiliation(s)
- Cindy Valentine
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kohta Ohnishi
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kazuhiro Irie
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Akira Murakami
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
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9
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Bhaskaran S, Pharaoh G, Ranjit R, Murphy A, Matsuzaki S, Nair BC, Forbes B, Gispert S, Auburger G, Humphries KM, Kinter M, Griffin TM, Deepa SS. Loss of mitochondrial protease ClpP protects mice from diet-induced obesity and insulin resistance. EMBO Rep 2018; 19:embr.201745009. [PMID: 29420235 DOI: 10.15252/embr.201745009] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 12/08/2017] [Accepted: 12/22/2017] [Indexed: 01/08/2023] Open
Abstract
Caseinolytic peptidase P (ClpP) is a mammalian quality control protease that is proposed to play an important role in the initiation of the mitochondrial unfolded protein response (UPRmt), a retrograde signaling response that helps to maintain mitochondrial protein homeostasis. Mitochondrial dysfunction is associated with the development of metabolic disorders, and to understand the effect of a defective UPRmt on metabolism, ClpP knockout (ClpP-/-) mice were analyzed. ClpP-/- mice fed ad libitum have reduced adiposity and paradoxically improved insulin sensitivity. Absence of ClpP increased whole-body energy expenditure and markers of mitochondrial biogenesis are selectively up-regulated in the white adipose tissue (WAT) of ClpP-/- mice. When challenged with a metabolic stress such as high-fat diet, despite similar caloric intake, ClpP-/- mice are protected from diet-induced obesity, glucose intolerance, insulin resistance, and hepatic steatosis. Our results show that absence of ClpP triggers compensatory responses in mice and suggest that ClpP might be dispensable for mammalian UPRmt initiation. Thus, we made an unexpected finding that deficiency of ClpP in mice is metabolically beneficial.
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Affiliation(s)
- Shylesh Bhaskaran
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Gavin Pharaoh
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.,Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Rojina Ranjit
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Ashley Murphy
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Satoshi Matsuzaki
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Binoj C Nair
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Brittany Forbes
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Suzana Gispert
- Experimental Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Kenneth M Humphries
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Michael Kinter
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Timothy M Griffin
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Sathyaseelan S Deepa
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
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Martin-Jiménez CA, García-Vega Á, Cabezas R, Aliev G, Echeverria V, González J, Barreto GE. Astrocytes and endoplasmic reticulum stress: A bridge between obesity and neurodegenerative diseases. Prog Neurobiol 2017; 158:45-68. [DOI: 10.1016/j.pneurobio.2017.08.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/22/2017] [Accepted: 08/04/2017] [Indexed: 12/13/2022]
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Hipkiss AR. On the Relationship between Energy Metabolism, Proteostasis, Aging and Parkinson's Disease: Possible Causative Role of Methylglyoxal and Alleviative Potential of Carnosine. Aging Dis 2017; 8:334-345. [PMID: 28580188 PMCID: PMC5440112 DOI: 10.14336/ad.2016.1030] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 10/30/2016] [Indexed: 12/25/2022] Open
Abstract
Recent research shows that energy metabolism can strongly influence proteostasis and thereby affect onset of aging and related disease such as Parkinson's disease (PD). Changes in glycolytic and proteolytic activities (influenced by diet and development) are suggested to synergistically create a self-reinforcing deleterious cycle via enhanced formation of triose phosphates (dihydroxyacetone-phosphate and glyceraldehyde-3-phosphate) and their decomposition product methylglyoxal (MG). It is proposed that triose phosphates and/or MG contribute to the development of PD and its attendant pathophysiological symptoms. MG can induce many of the macromolecular modifications (e.g. protein glycation) which characterise the aged-phenotype. MG can also react with dopamine to generate a salsolinol-like product, 1-acetyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinaline (ADTIQ), which accumulates in the Parkinson's disease (PD) brain and whose effects on mitochondria, analogous to MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), closely resemble changes associated with PD. MG can directly damage the intracellular proteolytic apparatus and modify proteins into non-degradable (cross-linked) forms. It is suggested that increased endogenous MG formation may result from either, or both, enhanced glycolytic activity and decreased proteolytic activity and contribute to the macromolecular changes associated with PD. Carnosine, a naturally-occurring dipeptide, may ameliorate MG-induced effects due, in part, to its carbonyl-scavenging activity. The possibility that ingestion of highly glycated proteins could also contribute to age-related brain dysfunction is briefly discussed.
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Affiliation(s)
- Alan R. Hipkiss
- Aston Research Centre for Healthy Ageing (ARCHA), School of Health and Life Sciences, Aston University, Birmingham B4 7ET, United Kingdom
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12
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Zhang YY, Gong JP, Li ZM. Autophagy and hepatic lipid metabolism. Shijie Huaren Xiaohua Zazhi 2017; 25:491-497. [DOI: 10.11569/wcjd.v25.i6.491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Autophagy is initially thought to be a non-selective process in which intracellular proteins or damaged organelles are degraded. It is activated when cells lack nutrients and energy. Autophagy degrades cytoplasmic components within lysosomes and reuses the energy of amino acids to promote cell survival and maintain the cytoplasmic content. Current evidence implicates autophagy in the regulation of lipid stores within the two main organs involved in maintaining lipid homeostasis, the liver and adipose tissue. Upregulation of autophagy may lead to conversion of white adipose tissue into brown adipose tissue, thus regulating energy expenditure and obesity. Discovering new therapeutic interventions to treat lipid and lipoprotein disorders is of great interest and the discovery of autophagy as a regulator of lipid metabolism has opened up a new avenue for this area. In the liver, autophagy can play a role in some common metabolic disorders, which needs further research.
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The association between coenzyme Q10 concentrations in follicular fluid with embryo morphokinetics and pregnancy rate in assisted reproductive techniques. J Assist Reprod Genet 2017; 34:599-605. [PMID: 28185121 DOI: 10.1007/s10815-017-0882-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 01/24/2017] [Indexed: 10/20/2022] Open
Abstract
PURPOSE This study seeks to evaluate the association between follicular fluid (FF) coenzyme Q10 (CoQ10) levels, embryo morphokinetics, and pregnancy rate. METHODS Sixty infertile patients who underwent intracytoplasmic sperm injection (ICSI) cycles were included in the study. For each patient, CoQ10 level of the follicular fluid was measured by high-performance liquid chromatography system. After the ICSI of each oocyte, the relationship between the level of CoQ10 content of each follicular fluid, the subsequent embryo quality, and embryo morphokinetics was investigated. The relationship between the level of CoQ10 content of each follicle and optimal time-lapse parameters for the embryos of these follicles including t5, s2, and cc2 was also analyzed. The embryos were further classified into four categories, namely, grades A, B, C, and D, according to morphokinetic parameters using t5-t2 and t5-t3 (cc3). Each follicular fluid analysis was performed for a single oocyte of a single embryo which was transferred to the patients. Additionally, follicular fluid CoQ10 levels and pregnancy rates were evaluated. RESULTS Follicular fluid CoQ10 levels were significantly higher in grades A and B than grades C and D embryos (p < 0.05). The concentration of CoQ10 levels was significantly higher in the pregnant group (p < 0.05). There was no significant correlation between optimal t5 and s2 morphokinetic parameters and CoQ10 levels. However, CoQ10 levels were significantly higher in follicular fluid of embryos which had optimal cc2 (p < 0.05). CONCLUSION High follicular fluid CoQ10 level is associated with optimal embryo morphokinetic parameters and higher pregnancy rates.
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Deepa SS, Bhaskaran S, Ranjit R, Qaisar R, Nair BC, Liu Y, Walsh ME, Fok WC, Van Remmen H. Down-regulation of the mitochondrial matrix peptidase ClpP in muscle cells causes mitochondrial dysfunction and decreases cell proliferation. Free Radic Biol Med 2016; 91:281-92. [PMID: 26721594 PMCID: PMC5584630 DOI: 10.1016/j.freeradbiomed.2015.12.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 12/14/2015] [Accepted: 12/19/2015] [Indexed: 12/22/2022]
Abstract
The caseinolytic peptidase P (ClpP) is the endopeptidase component of the mitochondrial matrix ATP-dependent ClpXP protease. ClpP degrades unfolded proteins to maintain mitochondrial protein homeostasis and is involved in the initiation of the mitochondrial unfolded protein response (UPR(mt)). Outside of an integral role in the UPR(mt), the cellular function of ClpP is not well characterized in mammalian cells. To investigate the role of ClpP in mitochondrial function, we generated C2C12 muscle cells that are deficient in ClpP using siRNA or stable knockdown using lentiviral transduction. Reduction of ClpP levels by ~70% in C2C12 muscle cells resulted in a number of mitochondrial alterations including reduced mitochondrial respiration and reduced oxygen consumption rate in response to electron transport chain (ETC) complex I and II substrates. The reduction in ClpP altered mitochondrial morphology, changed the expression level of mitochondrial fission protein Drp1 and blunted UPR(mt) induction. In addition, ClpP deficient cells showed increased generation of reactive oxygen species (ROS) and decreased membrane potential. At the cellular level, reduction of ClpP impaired myoblast differentiation, cell proliferation and elevated phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α) suggesting an inhibition of translation. Our study is the first to define the effects of ClpP deficiency on mitochondrial function in muscle cells in vitro. In addition, we have uncovered novel effects of ClpP on mitochondrial morphology, cell proliferation and protein translation pathways in muscle cells.
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Affiliation(s)
- Sathyaseelan S Deepa
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
| | - Shylesh Bhaskaran
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Rojina Ranjit
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Rizwan Qaisar
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Binoj C Nair
- The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yuhong Liu
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78245, USA
| | - Michael E Walsh
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78245, USA
| | - Wilson C Fok
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78245, USA
| | - Holly Van Remmen
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; Oklahoma City VA Medical Center, Oklahoma City, OK 73104, USA
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15
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Mitochondrial proteases and protein quality control in ageing and longevity. Ageing Res Rev 2015; 23:56-66. [PMID: 25578288 DOI: 10.1016/j.arr.2014.12.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/23/2014] [Accepted: 12/27/2014] [Indexed: 11/23/2022]
Abstract
Mitochondria have been implicated in the ageing process and the lifespan modulation of model organisms. Mitochondria are the main providers of energy in eukaryotic cells but also represent both a major source of reactive oxygen species and targets for protein oxidative damage. Since protein damage can impair mitochondrial function, mitochondrial proteases are critically important for protein maintenance and elimination of oxidized protein. In the mitochondrial matrix, protein quality control is mainly achieved by the Lon and Clp proteases which are also key players in damaged mitochondrial proteins degradation. Accumulation of damaged macromolecules resulting from oxidative stress and failure of protein maintenance constitutes a hallmark of cellular and organismal ageing and is believed to participate to the age-related decline of cellular function. Hence, age-related impairment of mitochondrial protein quality control may therefore contribute to the age-associated build-up of oxidized protein and alterations of mitochondrial redox and protein homeostasis.
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Masotti A, Celluzzi A, Petrini S, Bertini E, Zanni G, Compagnucci C. Aged iPSCs display an uncommon mitochondrial appearance and fail to undergo in vitro neurogenesis. Aging (Albany NY) 2015; 6:1094-108. [PMID: 25567319 PMCID: PMC4298368 DOI: 10.18632/aging.100708] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Reprogramming of human fibroblasts into induced pluripotent stem cells (iPSCs) leads to mitochondrial rejuvenation, making iPSCs a candidate model to study the mitochondrial biology during stemness and differentiation. At present, it is generally accepted that iPSCs can be maintained and propagated indefinitely in culture, but no specific studies have addressed this issue. In our study, we investigated features related to the 'biological age' of iPSCs, culturing and analyzing iPSCs kept for prolonged periods in vitro. We have demonstrated that aged iPSCs present an increased number of mitochondria per cell with an altered mitochondrial membrane potential and fail to properly undergo in vitro neurogenesis. In aged iPSCs we have also found an altered expression of genes relevant to mitochondria biogenesis. Overall, our results shed light on the mitochondrial biology of young and aged iPSCs and explore how an altered mitochondrial status may influence neuronal differentiation. Our work suggests to deepen the understanding of the iPSCs biology before considering their use in clinical applications.
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Abstract
SIGNIFICANCE The molecular mechanism of aging is still vigorously debated, although a general consensus exists that mitochondria are significantly involved in this process. However, the previously postulated role of mitochondrial-derived reactive oxygen species (ROS) as the damaging agents inducing functional loss in aging has fallen out of favor in the recent past. In this review, we critically examine the role of ROS in aging in the light of recent advances on the relationship between mitochondrial structure and function. RECENT ADVANCES The functional mitochondrial respiratory chain is now recognized as a reflection of the dynamic association of respiratory complexes in the form of supercomplexes (SCs). Besides providing kinetic advantage (channeling), SCs control ROS generation by the respiratory chain, thus providing a means to regulate ROS levels in the cell. Depending on their concentration, these ROS are either physiological signals essential for the life of the cell or toxic species that damage cell structure and functions. CRITICAL ISSUES We propose that under physiological conditions the dynamic nature of SCs reversibly controls the generation of ROS as signals involved in mitochondrial-nuclear communication. During aging, there is a progressive loss of control of ROS generation so that their production is irreversibly enhanced, inducing a vicious circle in which signaling is altered and structural damage takes place. FUTURE DIRECTIONS A better understanding on the forces affecting SC association would allow the manipulation of ROS generation, directing these species to their physiological signaling role.
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Affiliation(s)
- Maria Luisa Genova
- Dipartimento di Scienze Biomediche e Neuromotorie, Alma Mater Studiorum-Università di Bologna , Bologna, Italy
| | - Giorgio Lenaz
- Dipartimento di Scienze Biomediche e Neuromotorie, Alma Mater Studiorum-Università di Bologna , Bologna, Italy
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Bernhardt D, Hamann A, Osiewacz HD. The role of mitochondria in fungal aging. Curr Opin Microbiol 2014; 22:1-7. [PMID: 25299751 DOI: 10.1016/j.mib.2014.09.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/08/2014] [Accepted: 09/12/2014] [Indexed: 10/24/2022]
Abstract
Time-dependent impairments of mitochondrial function play a key role in biological aging. Work on fungal aging models has been instrumental in unraveling basic mechanisms leading to mitochondrial dysfunction and the identification of different pathways active in keeping mitochondria 'healthy' over time. Pathways including those involved in reactive oxygen scavenging, repair of damage, proteostasis, mitochondrial dynamics, and biogenesis, are interconnected and part of a complex quality control system. The individual components of this network are limited in capacity. However, if the capacity of one pathway is overwhelmed, another one may be activated. The mechanisms controlling the underlying cross-talk are poorly understood and subject of intensive investigation.
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Affiliation(s)
- Dominik Bernhardt
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes, Department of Biosciences, J.W. Goethe University, Frankfurt, Germany
| | - Andrea Hamann
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes, Department of Biosciences, J.W. Goethe University, Frankfurt, Germany
| | - Heinz D Osiewacz
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes, Department of Biosciences, J.W. Goethe University, Frankfurt, Germany.
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Gibellini L, Pinti M, Boraldi F, Giorgio V, Bernardi P, Bartolomeo R, Nasi M, De Biasi S, Missiroli S, Carnevale G, Losi L, Tesei A, Pinton P, Quaglino D, Cossarizza A. Silencing of mitochondrial Lon protease deeply impairs mitochondrial proteome and function in colon cancer cells. FASEB J 2014; 28:5122-35. [DOI: 10.1096/fj.14-255869] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Lara Gibellini
- Department of Surgery, Medicine, Dentistry, and Morphological SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Marcello Pinti
- Department of Life SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Federica Boraldi
- Department of Life SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | | | - Paolo Bernardi
- Department of Biomedical SciencesUniversity of PadovaPaduaItaly
| | - Regina Bartolomeo
- Department of Surgery, Medicine, Dentistry, and Morphological SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Milena Nasi
- Department of Surgery, Medicine, Dentistry, and Morphological SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Sara De Biasi
- Department of Surgery, Medicine, Dentistry, and Morphological SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Sonia Missiroli
- Department of Morphology, Surgery, and Experimental MedicineUniversity of FerraraFerraraItaly
| | - Gianluca Carnevale
- Department of Surgery, Medicine, Dentistry, and Morphological SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Lorena Losi
- Department of Life SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Anna Tesei
- Biosciences LaboratoryIRCCS Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST)MeldolaItaly
| | - Paolo Pinton
- Department of Morphology, Surgery, and Experimental MedicineUniversity of FerraraFerraraItaly
| | - Daniela Quaglino
- Department of Life SciencesUniversity of Modena and Reggio EmiliaModenaItaly
| | - Andrea Cossarizza
- Department of Surgery, Medicine, Dentistry, and Morphological SciencesUniversity of Modena and Reggio EmiliaModenaItaly
- Dipartimento Sperimentale Interaziendale, Campus San LazzaroUniversity of Modena and Reggio EmiliaReggio EmiliaItaly
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20
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El Refaeey A, Selem A, Badawy A. Combined coenzyme Q10 and clomiphene citrate for ovulation induction in clomiphene-citrate-resistant polycystic ovary syndrome. Reprod Biomed Online 2014; 29:119-24. [PMID: 24813752 DOI: 10.1016/j.rbmo.2014.03.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 03/06/2014] [Accepted: 03/12/2014] [Indexed: 10/25/2022]
Abstract
This prospective randomized controlled trial evaluated the effect of combined oral coenzyme Q10 (CoQ10) and clomiphene citrate for ovulation induction in clomiphene-citrate-resistant polycystic ovary syndrome (PCOS). A total of 101 infertile women with PCOS resistant to clomiphene citrate were randomized either to combined CoQ10 and clomiphene citrate (51 patients, 82 cycles) or to clomiphene citrate alone (50 patients, 71 cycles). The outcome measures were number of follicles, serum oestradiol, serum progesterone, endometrial thickness and ovulation, clinical pregnancy and miscarriage rates. Numbers of follicles >14 mm and ≥18 mm were significantly higher in the CoQ10 group. Endometrial thickness on the day of human chorionic gonadotrophin was significantly greater in the CoQ10 group (8.82 ± 0.27 mm versus 7.03 ± 0.74 mm). Ovulation occurred in 54/82 cycles (65.9%) in the CoQ10 group and 11/71 cycles (15.5%) in the control group. Clinical pregnancy rate was significantly higher in the CoQ10 group (19/51, 37.3%) versus the control group (3/50, 6.0%). Combination of CoQ10 and clomiphene citrate in the treatment of clomiphene-citrate-resistant PCOS patients improves ovulation and clinical pregnancy rates. It is an effective and safe option and can be considered before gonadotrophin therapy or laparoscopic ovarian drilling.
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Affiliation(s)
| | - Amal Selem
- Medical Biochemistry and Molecular Biology, Faculty of Medicine, Mansoura University, Egypt
| | - Ahmed Badawy
- Department of Obstetrics and Gynecology, Mansoura University, Egypt.
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21
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Knuppertz L, Hamann A, Pampaloni F, Stelzer E, Osiewacz HD. Identification of autophagy as a longevity-assurance mechanism in the aging model Podospora anserina. Autophagy 2014; 10:822-34. [PMID: 24584154 PMCID: PMC5119060 DOI: 10.4161/auto.28148] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 02/07/2014] [Accepted: 02/07/2014] [Indexed: 12/28/2022] Open
Abstract
The filamentous ascomycete Podospora anserina is a well-established aging model in which a variety of different pathways, including those involved in the control of respiration, ROS generation and scavenging, DNA maintenance, proteostasis, mitochondrial dynamics, and programmed cell death have previously been demonstrated to affect aging and life span. Here we address a potential role of autophagy. We provide data demonstrating high basal autophagy levels even in strains cultivated under noninduced conditions. By monitoring an N-terminal fusion of EGFP to the fungal LC3 homolog PaATG8 over the lifetime of the fungus on medium with and without nitrogen supplementation, respectively, we identified a significant increase of GFP puncta in older and in nitrogen-starved cultures suggesting an induction of autophagy during aging. This conclusion is supported by the demonstration of an age-related and autophagy-dependent degradation of a PaSOD1-GFP reporter protein. The deletion of Paatg1, which leads to the lack of the PaATG1 serine/threonine kinase active in early stages of autophagy induction, impairs ascospore germination and development and shortens life span. Under nitrogen-depleted conditions, life span of the wild type is increased almost 4-fold. In contrast, this effect is annihilated in the Paatg1 deletion strain, suggesting that the ability to induce autophagy is beneficial for this fungus. Collectively, our data identify autophagy as a longevity-assurance mechanism in P. anserina and as another surveillance pathway in the complex network of pathways affecting aging and development. These findings provide perspectives for the elucidation of the mechanisms involved in the regulation of individual pathways and their interactions.
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Affiliation(s)
- Laura Knuppertz
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes; Department of Biosciences; J W Goethe University; Frankfurt, Germany
| | - Andrea Hamann
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes; Department of Biosciences; J W Goethe University; Frankfurt, Germany
| | - Francesco Pampaloni
- Physical Biology Group; Buchmann Institute of Molecular Life Sciences; Cluster of Excellence Frankfurt Macromolecular Complexes; Frankfurt, Germany
| | - Ernst Stelzer
- Physical Biology Group; Buchmann Institute of Molecular Life Sciences; Cluster of Excellence Frankfurt Macromolecular Complexes; Frankfurt, Germany
| | - Heinz D Osiewacz
- Institute of Molecular Biosciences and Cluster of Excellence Frankfurt Macromolecular Complexes; Department of Biosciences; J W Goethe University; Frankfurt, Germany
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22
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Al-Khalili L, de Castro Barbosa T, Östling J, Massart J, Katayama M, Nyström AC, Oscarsson J, Zierath JR. Profiling of human myotubes reveals an intrinsic proteomic signature associated with type 2 diabetes. TRANSLATIONAL PROTEOMICS 2014. [DOI: 10.1016/j.trprot.2013.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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23
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Calvani R, Joseph AM, Adhihetty PJ, Miccheli A, Bossola M, Leeuwenburgh C, Bernabei R, Marzetti E. Mitochondrial pathways in sarcopenia of aging and disuse muscle atrophy. Biol Chem 2013; 394:393-414. [PMID: 23154422 DOI: 10.1515/hsz-2012-0247] [Citation(s) in RCA: 210] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 11/13/2012] [Indexed: 12/18/2022]
Abstract
Muscle loss during aging and disuse is a highly prevalent and disabling condition, but knowledge about cellular pathways mediating muscle atrophy is still limited. Given the postmitotic nature of skeletal myocytes, the maintenance of cellular homeostasis relies on the efficiency of cellular quality control mechanisms. In this scenario, alterations in mitochondrial function are considered a major factor underlying sarcopenia and muscle atrophy. Damaged mitochondria are not only less bioenergetically efficient, but also generate increased amounts of reactive oxygen species, interfere with cellular quality control mechanisms, and display a greater propensity to trigger apoptosis. Thus, mitochondria stand at the crossroad of signaling pathways that regulate skeletal myocyte function and viability. Studies on these pathways have sometimes provided unexpected and counterintuitive results, which suggests that they are organized into a complex, heterarchical network that is currently insufficiently understood. Untangling the complexity of such a network will likely provide clinicians with novel and highly effective therapeutics to counter the muscle loss associated with aging and disuse. In this review, we summarize the current knowledge on the mechanisms whereby mitochondrial dysfunction intervenes in the pathogenesis of sarcopenia and disuse atrophy, and highlight the prospect of targeting specific processes to treat these conditions.
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Affiliation(s)
- Riccardo Calvani
- Institute of Crystallography, Italian National Research Council (CNR), Bari 70126, Italy
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24
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Paoli P, Giannoni E, Chiarugi P. Anoikis molecular pathways and its role in cancer progression. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3481-3498. [PMID: 23830918 DOI: 10.1016/j.bbamcr.2013.06.026] [Citation(s) in RCA: 725] [Impact Index Per Article: 65.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/21/2013] [Accepted: 06/22/2013] [Indexed: 02/07/2023]
Abstract
Anoikis is a programmed cell death induced upon cell detachment from extracellular matrix, behaving as a critical mechanism in preventing adherent-independent cell growth and attachment to an inappropriate matrix, thus avoiding colonizing of distant organs. As anchorage-independent growth and epithelial-mesenchymal transition, two features associated with anoikis resistance, are vital steps during cancer progression and metastatic colonization, the ability of cancer cells to resist anoikis has now attracted main attention from the scientific community. Cancer cells develop anoikis resistance due to several mechanisms, including change in integrins' repertoire allowing them to grow in different niches, activation of a plethora of inside-out pro-survival signals as over-activation of receptors due to sustained autocrine loops, oncogene activation, growth factor receptor overexpression, or mutation/upregulation of key enzymes involved in integrin or growth factor receptor signaling. In addition, tumor microenvironment has also been acknowledged to contribute to anoikis resistance of bystander cancer cells, by modulating matrix stiffness, enhancing oxidative stress, producing pro-survival soluble factors, triggering epithelial-mesenchymal transition and self-renewal ability, as well as leading to metabolic deregulations of cancer cells. All these events help cancer cells to inhibit the apoptosis machinery and sustain pro-survival signals after detachment, counteracting anoikis and constituting promising targets for anti-metastatic pharmacological therapy. This article is part of a Special Section entitled: Cell Death Pathways.
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Affiliation(s)
- Paolo Paoli
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
| | - Elisa Giannoni
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
| | - Paola Chiarugi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy; Tuscany Tumor Institute and "Center for Research, Transfer and High Education, DENOTHE", 50134 Florence, Italy.
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25
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Tang G, Gutierrez Rios P, Kuo SH, Akman HO, Rosoklija G, Tanji K, Dwork A, Schon EA, Dimauro S, Goldman J, Sulzer D. Mitochondrial abnormalities in temporal lobe of autistic brain. Neurobiol Dis 2013; 54:349-61. [PMID: 23333625 DOI: 10.1016/j.nbd.2013.01.006] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/25/2012] [Accepted: 01/10/2013] [Indexed: 12/18/2022] Open
Abstract
Autism spectrum disorder (ASD) consists of a group of complex developmental disabilities characterized by impaired social interactions, deficits in communication and repetitive behavior. Multiple lines of evidence implicate mitochondrial dysfunction in ASD. In postmortem BA21 temporal cortex, a region that exhibits synaptic pathology in ASD, we found that compared to controls, ASD patients exhibited altered protein levels of mitochondria respiratory chain protein complexes, decreased Complex I and IV activities, decreased mitochondrial antioxidant enzyme SOD2, and greater oxidative DNA damage. Mitochondrial membrane mass was higher in ASD brain, as indicated by higher protein levels of mitochondrial membrane proteins Tom20, Tim23 and porin. No differences were observed in either mitochondrial DNA or levels of the mitochondrial gene transcription factor TFAM or cofactor PGC1α, indicating that a mechanism other than alterations in mitochondrial genome or mitochondrial biogenesis underlies these mitochondrial abnormalities. We further identified higher levels of the mitochondrial fission proteins (Fis1 and Drp1) and decreased levels of the fusion proteins (Mfn1, Mfn2 and Opa1) in ASD patients, indicating altered mitochondrial dynamics in ASD brain. Many of these changes were evident in cortical pyramidal neurons, and were observed in ASD children but were less pronounced or absent in adult patients. Together, these findings provide evidence that mitochondrial function and intracellular redox status are compromised in pyramidal neurons in ASD brain and that mitochondrial dysfunction occurs during early childhood when ASD symptoms appear.
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Affiliation(s)
- Guomei Tang
- Department of Neurology, Columbia University, NY 10032, USA
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26
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Voos W, Ward LA, Truscott KN. The role of AAA+ proteases in mitochondrial protein biogenesis, homeostasis and activity control. Subcell Biochem 2013; 66:223-263. [PMID: 23479443 DOI: 10.1007/978-94-007-5940-4_9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Mitochondria are specialised organelles that are structurally and functionally integrated into cells in the vast majority of eukaryotes. They are the site of numerous enzymatic reactions, some of which are essential for life. The double lipid membrane of the mitochondrion, that spatially defines the organelle and is necessary for some functions, also creates a physical but semi-permeable barrier to the rest of the cell. Thus to ensure the biogenesis, regulation and maintenance of a functional population of proteins, an autonomous protein handling network within mitochondria is required. This includes resident mitochondrial protein translocation machinery, processing peptidases, molecular chaperones and proteases. This review highlights the contribution of proteases of the AAA+ superfamily to protein quality and activity control within the mitochondrion. Here they are responsible for the degradation of unfolded, unassembled and oxidatively damaged proteins as well as the activity control of some enzymes. Since most knowledge about these proteases has been gained from studies in the eukaryotic microorganism Saccharomyces cerevisiae, much of the discussion here centres on their role in this organism. However, reference is made to mitochondrial AAA+ proteases in other organisms, particularly in cases where they play a unique role such as the mitochondrial unfolded protein response. As these proteases influence mitochondrial function in both health and disease in humans, an understanding of their regulation and diverse activities is necessary.
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Affiliation(s)
- Wolfgang Voos
- Institut für Biochemie und Molekularbiologie (IBMB), Universität Bonn, Nussallee 11, 53115, Bonn, Germany,
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27
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Abstract
Podospora anserina is an extensively studied model organism to unravel the mechanism of organismal aging. This filamentous fungus is short-lived and accessible to experimentation. Aging and lifespan are controlled by genetic and environmental traits and, in this model, have a strong mitochondrial etiology. Here, we describe methods and protocols to manipulate and study the aging process in P. anserina at different levels including biochemistry, cell biology, genetics, and physiology.
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28
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Anand R, Langer T, Baker MJ. Proteolytic control of mitochondrial function and morphogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:195-204. [PMID: 22749882 DOI: 10.1016/j.bbamcr.2012.06.025] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 06/08/2012] [Accepted: 06/15/2012] [Indexed: 12/18/2022]
Abstract
Mitochondrial proteostasis depends on a hierarchical system of tightly controlled quality surveillance mechanisms. Proteases within mitochondria take center stage in this network. They eliminate misfolded and damaged proteins and ensure the biogenesis and morphogenesis of mitochondria by processing or degrading short-lived regulatory proteins. Mitochondrial gene expression, the mitochondrial phospholipid metabolism and the fusion of mitochondrial membranes are under proteolytic control. Furthermore, in response to stress and mitochondrial dysfunction, proteolysis inhibits fusion and facilitates mitophagy and apoptosis. Defining these versatile activities of mitochondrial proteases will be pivotal for understanding the pathogenesis of various neurodegenerative disorders associated with defective mitochondria-associated proteolysis. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology.
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Voos W. Chaperone-protease networks in mitochondrial protein homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:388-99. [PMID: 22705353 DOI: 10.1016/j.bbamcr.2012.06.005] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 05/31/2012] [Accepted: 06/05/2012] [Indexed: 12/22/2022]
Abstract
As essential organelles, mitochondria are intimately integrated into the metabolism of a eukaryotic cell. The maintenance of the functional integrity of the mitochondrial proteome, also termed protein homeostasis, is facing many challenges both under normal and pathological conditions. First, since mitochondria are derived from bacterial ancestor cells, the proteins in this endosymbiotic organelle have a mixed origin. Only a few proteins are encoded on the mitochondrial genome, most genes for mitochondrial proteins reside in the nuclear genome of the host cell. This distribution requires a complex biogenesis of mitochondrial proteins, which are mostly synthesized in the cytosol and need to be imported into the organelle. Mitochondrial protein biogenesis usually therefore comprises complex folding and assembly processes to reach an enzymatically active state. In addition, specific protein quality control (PQC) processes avoid an accumulation of damaged or surplus polypeptides. Mitochondrial protein homeostasis is based on endogenous enzymatic components comprising a diverse set of chaperones and proteases that form an interconnected functional network. This review describes the different types of mitochondrial proteins with chaperone functions and covers the current knowledge of their roles in protein biogenesis, folding, proteolytic removal and prevention of aggregation, the principal reactions of protein homeostasis. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Affiliation(s)
- Wolfgang Voos
- Institut für Biochemie und Molekularbiologie IBMB, Universität Bonn, Nussallee 11, 53115 Bonn, Germany.
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30
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Abstract
Mitochondria have a crucial role in cellular bioenergetics and apoptosis, and thus are important to support cell function and in determination of cell death pathways. Inherited mitochondrial diseases can be caused by mutations of mitochondrial DNA or of nuclear genes that encode mitochondrial proteins. Although many mitochondrial disorders are multisystemic, some are tissue specific--eg, optic neuropathy, sensorineural deafness, and type 2 diabetes mellitus. In the past few years, several disorders have been associated with mutations of nuclear genes responsible for mitochondrial DNA maintenance and function, and the potential contribution of mitochondrial abnormalities to progressive neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease has been recognised. The process of mitochondrial fission-fusion has become a focus of attention in human disease. Importantly, the mitochondrion is now a target for therapeutic interventions that encompass small molecules, transcriptional regulation, and genetic manipulation, offering opportunities to treat a diverse range of diseases.
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Affiliation(s)
- Anthony H V Schapira
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London, UK.
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31
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Michel S, Wanet A, De Pauw A, Rommelaere G, Arnould T, Renard P. Crosstalk between mitochondrial (dys)function and mitochondrial abundance. J Cell Physiol 2012; 227:2297-310. [PMID: 21928343 DOI: 10.1002/jcp.23021] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A controlled regulation of mitochondrial mass through either the production (biogenesis) or the degradation (mitochondrial quality control) of the organelle represents a crucial step for proper mitochondrial and cell function. Key steps of mitochondrial biogenesis and quality control are overviewed, with an emphasis on the role of mitochondrial chaperones and proteases that keep mitochondria fully functional, provided the mitochondrial activity impairment is not excessive. In this case, the whole organelle is degraded by mitochondrial autophagy or "mitophagy." Beside the maintenance of adequate mitochondrial abundance and functions for cell homeostasis, mitochondrial biogenesis might be enhanced, through discussed signaling pathways, in response to various physiological stimuli, like contractile activity, exposure to low temperatures, caloric restriction, and stem cells differentiation. In addition, mitochondrial dysfunction might also initiate a retrograde response, enabling cell adaptation through increased mitochondrial biogenesis.
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Affiliation(s)
- Sébastien Michel
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (FUNDP), Namur, Belgium
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Nicotinamide, NAD(P)(H), and Methyl-Group Homeostasis Evolved and Became a Determinant of Ageing Diseases: Hypotheses and Lessons from Pellagra. Curr Gerontol Geriatr Res 2012; 2012:302875. [PMID: 22536229 PMCID: PMC3318212 DOI: 10.1155/2012/302875] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 12/19/2011] [Indexed: 01/22/2023] Open
Abstract
Compartmentalized redox faults are common to ageing diseases. Dietary constituents are catabolized to NAD(H) donating electrons producing proton-based bioenergy in coevolved, cross-species and cross-organ networks. Nicotinamide and NAD deficiency from poor diet or high expenditure causes pellagra, an ageing and dementing disorder with lost robustness to infection and stress. Nicotinamide and stress induce Nicotinamide-N-methyltransferase (NNMT) improving choline retention but consume methyl groups. High NNMT activity is linked to Parkinson's, cancers, and diseases of affluence. Optimising nicotinamide and choline/methyl group availability is important for brain development and increased during our evolution raising metabolic and methylome ceilings through dietary/metabolic symbiotic means but strict energy constraints remain and life-history tradeoffs are the rule. An optimal energy, NAD and methyl group supply, avoiding hypo and hyper-vitaminoses nicotinamide and choline, is important to healthy ageing and avoids utilising double-edged symbionts or uncontrolled autophagy or reversions to fermentation reactions in inflammatory and cancerous tissue that all redistribute NAD(P)(H), but incur high allostatic costs.
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Kowald A, Hamann A, Zintel S, Ullrich S, Klipp E, Osiewacz HD. A systems biological analysis links ROS metabolism to mitochondrial protein quality control. Mech Ageing Dev 2012; 133:331-7. [PMID: 22449407 DOI: 10.1016/j.mad.2012.03.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 01/16/2012] [Accepted: 03/06/2012] [Indexed: 12/17/2022]
Abstract
The analyses of previously generated Podospora anserina strains in which the mitochondrial superoxide dismutase, PaSOD3, is increased in abundance, revealed unexpected results, which, at first glance, are contradictory to the 'free radical theory of aging' (FRTA). To re-analyze these results, we performed additional experiments and developed a mathematical model consisting of a set of differential equations describing the time course of various ROS (reactive oxygen species), components of the cellular antioxidant system (PaSOD3 and mitochondrial peroxiredoxin, PaPRX1), and PaCLPP, a mitochondrial matrix protease involved in protein quality control. Incorporating these components we could identify a positive feed-back loop and demonstrate that the role of superoxide as the primary ROS responsible for age-related molecular damage is more complicated than originally stated by the FRTA. Our study is a first step towards the integration of the various pathways known to be involved in the control of biological aging.
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Affiliation(s)
- Axel Kowald
- Humboldt-Universität zu Berlin, Institute for Biology, Theoretical Biophysics, Invalidenstrasse 42, 10115 Berlin, Germany
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Guadamillas MC, Cerezo A, Del Pozo MA. Overcoming anoikis--pathways to anchorage-independent growth in cancer. J Cell Sci 2012; 124:3189-97. [PMID: 21940791 DOI: 10.1242/jcs.072165] [Citation(s) in RCA: 300] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Anoikis (or cell-detachment-induced apoptosis) is a self-defense strategy that organisms use to eliminate 'misplaced' cells, i.e. cells that are in an inappropriate location. Occasionally, detached or misplaced cells can overcome anoikis and survive for a certain period of time in the absence of the correct signals from the extracellular matrix (ECM). If cells are able to adapt to their new environment, then they have probably become anchorage-independent, which is one of the hallmarks of cancer cells. Anoikis resistance and anchorage-independency allow tumor cells to expand and invade adjacent tissues, and to disseminate through the body, giving rise to metastasis. Thus, overcoming anoikis is a crucial step in a series of changes that a tumor cell undergoes during malignant transformation. Tumor cells have developed a variety of strategies to bypass or overcome anoikis. Some strategies consist of adaptive cellular changes that allow the cells to behave as they would in the correct environment, so that induction of anoikis is aborted. Other strategies aim to counteract the negative effects of anoikis induction by hyperactivating survival and proliferative cascades. The recently discovered processes of autophagy and entosis also highlight the contribution of these mechanisms to rendering the cells in a dormant state until they receive a signal initiated at the ECM, thereby circumventing anoikis. In all situations, the final outcome is the ability of the tumor to grow and metastasize. A better understanding of the mechanisms underlying anoikis resistance could help to counteract tumor progression and prevent metastasis formation.
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Affiliation(s)
- Marta C Guadamillas
- Integrin Signaling Laboratory, Department of Vascular Biology and Inflammation, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
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Kriegenburg F, Ellgaard L, Hartmann-Petersen R. Molecular chaperones in targeting misfolded proteins for ubiquitin-dependent degradation. FEBS J 2012; 279:532-42. [PMID: 22177318 DOI: 10.1111/j.1742-4658.2011.08456.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The accumulation of misfolded proteins presents a considerable threat to the health of individual cells and has been linked to severe diseases, including neurodegenerative disorders. Considering that, in nature, cells often are exposed to stress conditions that may lead to aberrant protein conformational changes, it becomes clear that they must have an efficient quality control apparatus to refold or destroy misfolded proteins. In general, cells rely on molecular chaperones to seize and refold misfolded proteins. If the native state is unattainable, misfolded proteins are targeted for degradation via the ubiquitin-proteasome system. The specificity of this proteolysis is generally provided by E3 ubiquitin-protein ligases, hundreds of which are encoded in the human genome. However, rather than binding the misfolded proteins directly, most E3s depend on molecular chaperones to recognize the misfolded protein substrate. Thus, by delegating substrate recognition to chaperones, E3s deftly utilize a pre-existing cellular system for selectively targeting misfolded proteins. Here, we review recent advances in understanding the interplay between molecular chaperones and the ubiquitin-proteasome system in the cytosol, nucleus, endoplasmic reticulum and mitochondria.
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Weil A, Luce K, Dröse S, Wittig I, Brandt U, Osiewacz HD. Unmasking a temperature-dependent effect of the P. anserina i-AAA protease on aging and development. Cell Cycle 2011; 10:4280-90. [PMID: 22134244 PMCID: PMC3272260 DOI: 10.4161/cc.10.24.18560] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 10/27/2011] [Indexed: 12/15/2022] Open
Abstract
Different molecular pathways involved in maintaining mitochondrial function are of fundamental importance to control cellular homeostasis. Mitochondrial i-AAA protease is part of such a surveillance system and PaIAP is the putative ortholog in the fungal aging model Podospora anserina. Here we investigated the role of PaIAP in aging and development. Deletion of the gene encoding PaIAP resulted in a specific phenotype. When incubated at 27°C, spore germination and fruiting body formation are not different from that of the corresponding wild-type strain. Unexpectedly, the lifespan of the deletion strain is strongly increased. In contrast, cultivation at an elevated temperature of 37°C leads to impairments in spore germination and fruiting body formation, and to a reduced lifespan. The higher PaIAP abundance in wild-type strains of the fungus grown at elevated temperature and the phenotype of the deletion strain unmasks a temperature-related role of the protein. The protease appears to be part of a molecular system that has evolved to allow survival under changing temperatures as they characteristically occur in nature.
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Affiliation(s)
- Andrea Weil
- Goethe University, Faculty for Biosciences & Cluster of Excellence Macromolecular Complexes Frankfurt, Institute of Molecular Biosciences, Frankfurt, Germany
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p53-TIGAR axis attenuates mitophagy to exacerbate cardiac damage after ischemia. J Mol Cell Cardiol 2011; 52:175-84. [PMID: 22044588 DOI: 10.1016/j.yjmcc.2011.10.008] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 10/02/2011] [Accepted: 10/10/2011] [Indexed: 11/23/2022]
Abstract
Inhibition of tumor suppressor p53 is cardioprotective against ischemic injury and provides resistance to subsequent cardiac remodeling. We investigated p53-mediated expansion of ischemic damage with a focus on mitochondrial integrity in association with autophagy and apoptosis. p53(-/-) heart showed that autophagic flux was promoted under ischemia without a change in cardiac tissue ATP content. Electron micrographs revealed that ischemic border zone in p53(-/-) mice had 5-fold greater numbers of autophagic vacuoles containing mitochondria, indicating the occurrence of mitophagy, with an apparent reduction of abnormal mitochondria compared with those in WT mice. Analysis of autophagic mediators acting downstream of p53 revealed that TIGAR (TP53-induced glycolysis and apoptosis regulator) was exclusively up-regulated in ischemic myocardium. TIGAR(-/-) mice exhibited the promotion of mitophagy followed by decrease of abnormal mitochondria and resistance to ischemic injury, consistent with the phenotype of p53(-/-) mice. In p53(-/-) and TIGAR(-/-) ischemic myocardium, ROS production was elevated and followed by Bnip3 activation which is an initiator of mitophagy. Furthermore, the activation of Bnip3 and mitophagy due to p53/TIGAR inhibition were reversed with antioxidant N-acetyl-cysteine, indicating that this adaptive response requires ROS signal. Inhibition of mitophagy using chloroquine in p53(-/-) or TIGAR(-/-) mice exacerbated accumulation of damaged mitochondria to the level of wild-type mice and attenuated cardioprotective action. These findings indicate that p53/TIGAR-mediated inhibition of myocyte mitophagy is responsible for impairment of mitochondrial integrity and subsequent apoptosis, the process of which is closely involved in p53-mediated ventricular remodeling after myocardial infarction.
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Jones AWE, Yao Z, Vicencio JM, Karkucinska-Wieckowska A, Szabadkai G. PGC-1 family coactivators and cell fate: roles in cancer, neurodegeneration, cardiovascular disease and retrograde mitochondria-nucleus signalling. Mitochondrion 2011; 12:86-99. [PMID: 21983689 DOI: 10.1016/j.mito.2011.09.009] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 09/08/2011] [Accepted: 09/16/2011] [Indexed: 12/29/2022]
Abstract
Over the past two decades, a complex nuclear transcriptional machinery controlling mitochondrial biogenesis and function has been described. Central to this network are the PGC-1 family coactivators, characterised as master regulators of mitochondrial biogenesis. Recent literature has identified a broader role for PGC-1 coactivators in both cell death and cellular adaptation under conditions of stress, here reviewed in the context of the pathology associated with cancer, neurodegeneration and cardiovascular disease. Moreover, we propose that these studies also imply a novel conceptual framework on the general role of mitochondrial dysfunction in disease. It is now well established that the complex nuclear transcriptional control of mitochondrial biogenesis allows for adaptation of mitochondrial mass and function to environmental conditions. On the other hand, it has also been suggested that mitochondria alter their function according to prevailing cellular energetic requirements and thus function as sensors that generate signals to adjust fundamental cellular processes through a retrograde mitochondria-nucleus signalling pathway. Therefore, altered mitochondrial function can affect cell fate not only directly by modifying cellular energy levels or redox state, but also indirectly, by altering nuclear transcriptional patterns. The current literature on such retrograde signalling in both yeast and mammalian cells is thus reviewed, with an outlook on its potential contribution to disease through the regulation of PGC-1 family coactivators. We propose that further investigation of these pathways will lead to the identification of novel pharmacological targets and treatment strategies to combat disease.
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Affiliation(s)
- Aleck W E Jones
- Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London, UK
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Bentov Y, Yavorska T, Esfandiari N, Jurisicova A, Casper RF. The contribution of mitochondrial function to reproductive aging. J Assist Reprod Genet 2011; 28:773-83. [PMID: 21617930 DOI: 10.1007/s10815-011-9588-7] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 05/18/2011] [Indexed: 12/30/2022] Open
Abstract
PURPOSE The number of women attempting to conceive between the ages of 36 and 44 has increased significantly in the last decade. While it is well established that women's reproductive success dramatically declines with age, the underlying physiological changes responsible for this phenomenon are not well understood. With assisted reproductive technologies, it is clear that oocyte quality is a likely cause since women over 40 undergoing in vitro fertilization (IVF) with oocytes donated by younger women have success rates comparable to young patients. Apart from oocyte donation, there is no known intervention to improve the pregnancy outcome of older patients. The aim of this paper was the review the relevant data on the potential role of mitochondria in reproductive aging. METHOD Review of current literature on the subject. RESULTS We present the current evidence that associate mitochondrial dysfunction with age related decrease in female reproductive outcome. CONCLUSIONS The aging process is complex, driven by a multitude of factors thought to modulate cellular and organism life span. Although the factors responsible for diminished oocyte quality remain to be elucidated, the present review focuses on the potential role of impaired mitochondrial function.
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Affiliation(s)
- Yaakov Bentov
- Toronto Centre for Advanced Reproductive Technology, University of Toronto, Toronto, Ontario, Canada.
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