201
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Lesage S, Drouet V, Majounie E, Deramecourt V, Jacoupy M, Nicolas A, Cormier-Dequaire F, Hassoun S, Pujol C, Ciura S, Erpapazoglou Z, Usenko T, Maurage CA, Sahbatou M, Liebau S, Ding J, Bilgic B, Emre M, Erginel-Unaltuna N, Guven G, Tison F, Tranchant C, Vidailhet M, Corvol JC, Krack P, Leutenegger AL, Nalls M, Hernandez D, Heutink P, Gibbs J, Hardy J, Wood N, Gasser T, Durr A, Deleuze JF, Tazir M, Destée A, Lohmann E, Kabashi E, Singleton A, Corti O, Brice A, Lesage S, Tison F, Vidailhet M, Corvol JC, Agid Y, Anheim M, Bonnet AM, Borg M, Broussolle E, Damier P, Destée A, Dürr A, Durif F, Krack P, Klebe S, Lohmann E, Martinez M, Pollak P, Rascol O, Tranchant C, Vérin M, Viallet F, Brice A, Lesage S, Majounie E, Tison F, Vidailhet M, Corvol J, Nalls M, Hernandez D, Gibbs J, Dürr A, Arepalli S, Barker R, Ben-Shlomo Y, Berg D, Bettella F, Bhatia K, de Bie R, Biffi A, Bloem B, Bochdanovits Z, Bonin M, Lesage S, Tison F, Vidailhet M, Corvol JC, Agid Y, Anheim M, Bonnet AM, Borg M, Broussolle E, Damier P, Destée A, Dürr A, Durif F, Krack P, Klebe S, Lohmann E, Martinez M, Pollak P, Rascol O, Tranchant C, Vérin M, Bras J, Brockmann K, Brooks J, Burn D, Charlesworth G, Chen H, Chinnery P, Chong S, Clarke C, Cookson M, Counsell C, Damier P, Dartigues JF, Deloukas P, Deuschl G, Dexter D, van Dijk K, Dillman A, Dong J, Durif F, Edkins S, Escott-Price V, Evans J, Foltynie T, Gao J, Gardner M, Goate A, Gray E, Guerreiro R, Harris C, van Hilten J, Hofman A, Hollenbeck A, Holmans P, Holton J, Hu M, Huang X, Huber H, Hudson G, Hunt S, Huttenlocher J, Illig T, Jónsson P, Kilarski L, Jansen I, Lambert JC, Langford C, Lees A, Lichtner P, Limousin P, Lopez G, Lorenz D, Lubbe S, Lungu C, Martinez M, Mätzler W, McNeill A, Moorby C, Moore M, Morrison K, Mudanohwo E, O’Sullivan S, Owen M, Pearson J, Perlmutter J, Pétursson H, Plagnol V, Pollak P, Post B, Potter S, Ravina B, Revesz T, Riess O, Rivadeneira F, Rizzu P, Ryten M, Saad M, Simón-Sánchez J, Sawcer S, Schapira A, Scheffer H, Schulte C, Sharma M, Shaw K, Sheerin UM, Shoulson I, Shulman J, Sidransky E, Spencer C, Stefánsson H, Stefánsson K, Stockton J, Strange A, Talbot K, Tanner C, Tashakkori-Ghanbaria A, Trabzuni D, Traynor B, Uitterlinden A, Velseboer D, Walker R, van de Warrenburg B, Wickremaratchi M, Williams-Gray C, Winder-Rhodes S, Wurster I, Williams N, Morris H, Heutink P, Hardy J, Wood N, Gasser T, Singleton A, Brice A. Loss of VPS13C Function in Autosomal-Recessive Parkinsonism Causes Mitochondrial Dysfunction and Increases PINK1/Parkin-Dependent Mitophagy. Am J Hum Genet 2016; 98:500-513. [PMID: 26942284 DOI: 10.1016/j.ajhg.2016.01.014] [Citation(s) in RCA: 284] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/20/2016] [Indexed: 11/29/2022] Open
Abstract
Autosomal-recessive early-onset parkinsonism is clinically and genetically heterogeneous. The genetic causes of approximately 50% of autosomal-recessive early-onset forms of Parkinson disease (PD) remain to be elucidated. Homozygozity mapping and exome sequencing in 62 isolated individuals with early-onset parkinsonism and confirmed consanguinity followed by data mining in the exomes of 1,348 PD-affected individuals identified, in three isolated subjects, homozygous or compound heterozygous truncating mutations in vacuolar protein sorting 13C (VPS13C). VPS13C mutations are associated with a distinct form of early-onset parkinsonism characterized by rapid and severe disease progression and early cognitive decline; the pathological features were striking and reminiscent of diffuse Lewy body disease. In cell models, VPS13C partly localized to the outer membrane of mitochondria. Silencing of VPS13C was associated with lower mitochondrial membrane potential, mitochondrial fragmentation, increased respiration rates, exacerbated PINK1/Parkin-dependent mitophagy, and transcriptional upregulation of PARK2 in response to mitochondrial damage. This work suggests that loss of function of VPS13C is a cause of autosomal-recessive early-onset parkinsonism with a distinctive phenotype of rapid and severe progression.
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202
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Mäkelä J, Tselykh TV, Kukkonen JP, Eriksson O, Korhonen LT, Lindholm D. Peroxisome proliferator-activated receptor-γ (PPARγ) agonist is neuroprotective and stimulates PGC-1α expression and CREB phosphorylation in human dopaminergic neurons. Neuropharmacology 2016; 102:266-75. [DOI: 10.1016/j.neuropharm.2015.11.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 11/10/2015] [Accepted: 11/22/2015] [Indexed: 12/16/2022]
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203
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Snoeck HW. Can Metabolic Mechanisms of Stem Cell Maintenance Explain Aging and the Immortal Germline? Cell Stem Cell 2016; 16:582-4. [PMID: 26046756 DOI: 10.1016/j.stem.2015.04.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The mechanisms underlying the aging process are not understood. Even tissues endowed with somatic stem cells age while the germline appears immortal. I propose that this paradox may be explained by the pervasive use of glycolysis by somatic stem cells as opposed to the predominance of mitochondrial respiration in gametes.
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Affiliation(s)
- Hans-Willem Snoeck
- Columbia Center for Translational Immunology, Department of Medicine, Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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204
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Rainbolt TK, Lebeau J, Puchades C, Wiseman RL. Reciprocal Degradation of YME1L and OMA1 Adapts Mitochondrial Proteolytic Activity during Stress. Cell Rep 2016; 14:2041-2049. [PMID: 26923599 DOI: 10.1016/j.celrep.2016.02.011] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 12/21/2015] [Accepted: 01/29/2016] [Indexed: 12/31/2022] Open
Abstract
The mitochondrial inner membrane proteases YME1L and OMA1 are critical regulators of essential mitochondrial functions, including inner membrane proteostasis maintenance and mitochondrial dynamics. Here, we show that YME1L and OMA1 are reciprocally degraded in response to distinct types of cellular stress. OMA1 is degraded through a YME1L-dependent mechanism in response to toxic insults that depolarize the mitochondrial membrane. Alternatively, insults that depolarize mitochondria and deplete cellular ATP stabilize active OMA1 and promote YME1L degradation. We show that the differential degradation of YME1L and OMA1 alters their proteolytic processing of the dynamin-like GTPase OPA1, a critical regulator of mitochondrial inner membrane morphology, which influences the recovery of tubular mitochondria following membrane-depolarization-induced fragmentation. Our results reveal the differential stress-induced degradation of YME1L and OMA1 as a mechanism for sensitively adapting mitochondrial inner membrane protease activity and function in response to distinct types of cellular insults.
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Affiliation(s)
- T Kelly Rainbolt
- Department of Molecular and Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Justine Lebeau
- Department of Molecular and Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Cristina Puchades
- Department of Molecular and Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - R Luke Wiseman
- Department of Molecular and Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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205
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Mäkelä J, Mudò G, Pham DD, Di Liberto V, Eriksson O, Louhivuori L, Bruelle C, Soliymani R, Baumann M, Korhonen L, Lalowski M, Belluardo N, Lindholm D. Peroxisome proliferator-activated receptor-γ coactivator-1α mediates neuroprotection against excitotoxic brain injury in transgenic mice: role of mitochondria and X-linked inhibitor of apoptosis protein. Eur J Neurosci 2016; 43:626-39. [PMID: 26741810 DOI: 10.1111/ejn.13157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 12/03/2015] [Accepted: 12/29/2015] [Indexed: 01/08/2023]
Abstract
Peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) is a transcriptional coactivator involved in the regulation of mitochondrial biogenesis and cell defense. The functions of PGC-1α in physiology of brain mitochondria are, however, not fully understood. To address this we have studied wild-type and transgenic mice with a two-fold overexpression of PGC-1α in brain neurons. Data showed that the relative number and basal respiration of brain mitochondria were increased in PGC-1α transgenic mice compared with wild-type mitochondria. These changes occurred concomitantly with altered levels of proteins involved in oxidative phosphorylation (OXPHOS) as studied by proteomic analyses and immunoblottings. Cultured hippocampal neurons from PGC-1α transgenic mice were more resistant to cell degeneration induced by the glutamate receptor agonist kainic acid. In vivo kainic acid induced excitotoxic cell death in the hippocampus at 48 h in wild-type mice but significantly less so in PGC-1α transgenic mice. However, at later time points cell degeneration was also evident in the transgenic mouse hippocampus, indicating that PGC-1α overexpression can induce a delay in cell death. Immunoblotting showed that X-linked inhibitor of apoptosis protein (XIAP) was increased in PGC-1α transgenic hippocampus with no significant changes in Bcl-2 or Bcl-X. Collectively, these results show that PGC-1α overexpression contributes to enhanced neuronal viability by stimulating mitochondria number and respiration and increasing levels of OXPHOS proteins and the anti-apoptotic protein XIAP.
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Affiliation(s)
- Johanna Mäkelä
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland.,Minerva Medical Research Institute, Biomedicum-2 Helsinki, Tukholmankatu 8, FIN-00290 Helsinki, Finland
| | - Giuseppa Mudò
- Department of Experimental Biomedicine and Clinical Neuroscience, Division of Human Physiology, University of Palermo, Corso Tukory 129, I-90134 Palermo, Italy
| | - Dan Duc Pham
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland.,Minerva Medical Research Institute, Biomedicum-2 Helsinki, Tukholmankatu 8, FIN-00290 Helsinki, Finland
| | - Valentina Di Liberto
- Department of Experimental Biomedicine and Clinical Neuroscience, Division of Human Physiology, University of Palermo, Corso Tukory 129, I-90134 Palermo, Italy
| | - Ove Eriksson
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland
| | - Lauri Louhivuori
- Medicum, Department of Physiology, University of Helsinki, Helsinki, Finland
| | - Céline Bruelle
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland.,Minerva Medical Research Institute, Biomedicum-2 Helsinki, Tukholmankatu 8, FIN-00290 Helsinki, Finland
| | - Rabah Soliymani
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland
| | - Marc Baumann
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland
| | - Laura Korhonen
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland.,Clinicum, Division of Child Psychiatry, Helsinki University Central Hospital, Helsinki, Finland
| | - Maciej Lalowski
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland
| | - Natale Belluardo
- Department of Experimental Biomedicine and Clinical Neuroscience, Division of Human Physiology, University of Palermo, Corso Tukory 129, I-90134 Palermo, Italy
| | - Dan Lindholm
- Medicum, Department of Biochemistry and Developmental Biology, Medical Faculty, University of Helsinki, POB 63, 00014, Haartmaninkatu 8, FIN-00290, Helsinki, Finland.,Minerva Medical Research Institute, Biomedicum-2 Helsinki, Tukholmankatu 8, FIN-00290 Helsinki, Finland
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206
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Cross Talk of Proteostasis and Mitostasis in Cellular Homeodynamics, Ageing, and Disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:4587691. [PMID: 26977249 PMCID: PMC4763003 DOI: 10.1155/2016/4587691] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/24/2015] [Accepted: 12/31/2015] [Indexed: 12/26/2022]
Abstract
Mitochondria are highly dynamic organelles that provide essential metabolic functions and represent the major bioenergetic hub of eukaryotic cell. Therefore, maintenance of mitochondria activity is necessary for the proper cellular function and survival. To this end, several mechanisms that act at different levels and time points have been developed to ensure mitochondria quality control. An interconnected highly integrated system of mitochondrial and cytosolic chaperones and proteases along with the fission/fusion machinery represents the surveillance scaffold of mitostasis. Moreover, nonreversible mitochondrial damage targets the organelle to a specific autophagic removal, namely, mitophagy. Beyond the organelle dynamics, the constant interaction with the ubiquitin-proteasome-system (UPS) has become an emerging aspect of healthy mitochondria. Dysfunction of mitochondria and UPS increases with age and correlates with many age-related diseases including cancer and neurodegeneration. In this review, we discuss the functional cross talk of proteostasis and mitostasis in cellular homeodynamics and the impairment of mitochondrial quality control during ageing, cancer, and neurodegeneration.
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207
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Wiemerslage L, Lee D. Quantification of mitochondrial morphology in neurites of dopaminergic neurons using multiple parameters. J Neurosci Methods 2016; 262:56-65. [PMID: 26777473 DOI: 10.1016/j.jneumeth.2016.01.008] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 12/12/2015] [Accepted: 01/02/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND Studies of mitochondrial morphology vary in techniques. Most use one morphological parameter while others describe mitochondria qualitatively. Because mitochondria are so dynamic, a single parameter does not capture the true state of the network and may lead to erroneous conclusions. Thus, a gestalt method of analysis is warranted. NEW METHOD This work describes a method combining immunofluorescence assays with computerized image analysis to measure the mitochondrial morphology within neuritic projections of a specific population of neurons. Six parameters of mitochondrial morphology were examined utilizing ImageJ to analyze colocalized signals. RESULTS Using primary neuronal cultures from Drosophila, we tested mitochondrial morphology in neurites of dopaminergic (DA) neurons. We validate our model using mutants with known defects in mitochondrial morphology. Furthermore, we show a difference in mitochondrial morphology between cells treated as control or with a neurotoxin inducing PD (Parkinson's Disease in humans)-like pathology. We also show interactions between morphological parameters and experimental treatment. COMPARISON WITH EXISTING METHODS Our method is a significant improvement of previously described methods. Six morphometric parameters are quantified, providing a gestalt analysis of mitochondrial morphology. Also it can target specific populations of mitochondria using immunofluorescence assay and image analysis. CONCLUSIONS We found that our method adequately detects differences in mitochondrial morphology between treatment groups. We conclude that some parameters may be unique to a mutation or a disease state, and the relationship between parameters is altered by experimental treatment. We suggest at least four variables should be considered when using mitochondrial structure as an experimental endpoint.
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Affiliation(s)
- Lyle Wiemerslage
- Functional Pharmacology, Department of Neuroscience, Biomedicinska Centrum, Uppsala University, Husargatan 3, Box 593, 75124 Uppsala, Sweden.
| | - Daewoo Lee
- Neuroscience Program, Department of Biological Sciences, Ohio University, Athens, OH 45701, United States.
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208
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Mukherjee R, Chakrabarti O. Ubiquitin mediated regulation of the E3 ligase GP78 by Mahogunin in trans affects mitochondrial homeostasis. J Cell Sci 2016; 129:757-73. [DOI: 10.1242/jcs.176537] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 12/29/2015] [Indexed: 12/29/2022] Open
Abstract
Cellular quality control provides an efficient surveillance system to regulate mitochondrial turn-over. This study elucidates a novel interaction of the cytosolic E3 ligase, MGRN1 with the ER ubiquitin E3 ligase, GP78. Loss of Mgrn1 function has been implicated in late-onset spongiform neurodegeneration, congenital heart defects amongst several developmental defects. MGRN1 ubiquitinates GP78 in trans via non-canonical K11 linkages. This helps maintain constitutively low levels of GP78 in healthy cells, in turn downregulating mitophagy. GP78, however, does not regulate MGRN1. When mitochondria are stressed, cytosolic Ca2+ increases.This leads to reduced interaction between MGRN1 and GP78 and its compromised ubiquitination. Chelating Ca2+ restores association between the two ligases and the trans ubiquitination. Catalytic inactivation of MGRN1 results in elevated levels of GP78 and consequential increase in the initiation of mitophagy. This is significant because functional depletion of MGRN1 by membrane-associated disease causing prion protein, CtmPrP affects polyubiquitination and degradation of GP78, also leading to an increase in mitophagy events. This suggests that MGRN1 participates in mitochondrial quality control and could contribute to neurodegeneration in a sub-set of CtmPrP mediated prion diseases.
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Affiliation(s)
- Rukmini Mukherjee
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata – 700064, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata – 700064, India
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209
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Zsurka G, Kunz WS. Mitochondrial dysfunction and seizures: the neuronal energy crisis. Lancet Neurol 2015; 14:956-66. [PMID: 26293567 DOI: 10.1016/s1474-4422(15)00148-9] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/19/2015] [Accepted: 06/24/2015] [Indexed: 12/21/2022]
Abstract
Seizures are often the key manifestation of neurological diseases caused by pathogenic mutations in 169 of the genes that have so far been identified to affect mitochondrial function. Mitochondria are the main producers of ATP needed for normal electrical activities of neurons and synaptic transmission. Additionally, they have a central role in neurotransmitter synthesis, calcium homoeostasis, redox signalling, production and modulation of reactive oxygen species, and neuronal death. Hypotheses link mitochondrial failure to seizure generation through changes in calcium homoeostasis, oxidation of ion channels and neurotransmitter transporters by reactive oxygen species, a decrease in neuronal plasma membrane potential, and reduced network inhibition due to interneuronal dysfunction. Seizures, irrespective of their origin, represent an excessive acute energy demand in the brain. Accordingly, secondary mitochondrial dysfunction has been described in various epileptic disorders, including disorders that are mainly of non-mitochondrial origin. An understanding of the reciprocal relation between mitochondrial dysfunction and epilepsy is crucial to select appropriate anticonvulsant treatment and has the potential to open up new therapeutic approaches in the subset of epileptic disorders caused by mitochondrial dysfunction.
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Affiliation(s)
- Gábor Zsurka
- Division of Neurochemistry, Department of Epileptology, and Life & Brain Center, University of Bonn, Bonn, Germany
| | - Wolfram S Kunz
- Division of Neurochemistry, Department of Epileptology, and Life & Brain Center, University of Bonn, Bonn, Germany.
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210
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Lionaki E, Markaki M, Palikaras K, Tavernarakis N. Mitochondria, autophagy and age-associated neurodegenerative diseases: New insights into a complex interplay. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1412-23. [DOI: 10.1016/j.bbabio.2015.04.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/10/2015] [Accepted: 04/20/2015] [Indexed: 12/22/2022]
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211
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Shadel GS, Horvath TL. Mitochondrial ROS signaling in organismal homeostasis. Cell 2015; 163:560-9. [PMID: 26496603 DOI: 10.1016/j.cell.2015.10.001] [Citation(s) in RCA: 831] [Impact Index Per Article: 92.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 02/07/2023]
Abstract
Generation, transformation, and utilization of organic molecules in support of cellular differentiation, growth, and maintenance are basic tenets that define life. In eukaryotes, mitochondrial oxygen consumption plays a central role in these processes. During the process of oxidative phosphorylation, mitochondria utilize oxygen to generate ATP from organic fuel molecules but in the process also produce reactive oxygen species (ROS). While ROS have long been appreciated for their damage-promoting, detrimental effects, there is now a greater understanding of their roles as signaling molecules. Here, we review mitochondrial ROS-mediated signaling pathways with an emphasis on how they are involved in various basal and adaptive physiological responses that control organismal homeostasis.
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Affiliation(s)
- Gerald S Shadel
- Department of Pathology, Yale School of Medicine, New Haven CT 06520; Department of Genetics, Yale School of Medicine, New Haven CT 06520; Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale School of Medicine, New Haven CT 06520.
| | - Tamas L Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale School of Medicine, New Haven CT 06520; Section of Comparative Medicine, Yale School of Medicine, New Haven CT 06520; Department of Neurobiology, Yale School of Medicine, New Haven CT 06520.
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212
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Sakakibara K, Eiyama A, Suzuki SW, Sakoh-Nakatogawa M, Okumura N, Tani M, Hashimoto A, Nagumo S, Kondo-Okamoto N, Kondo-Kakuta C, Asai E, Kirisako H, Nakatogawa H, Kuge O, Takao T, Ohsumi Y, Okamoto K. Phospholipid methylation controls Atg32-mediated mitophagy and Atg8 recycling. EMBO J 2015; 34:2703-19. [PMID: 26438722 DOI: 10.15252/embj.201591440] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 09/04/2015] [Indexed: 12/15/2022] Open
Abstract
Degradation of mitochondria via selective autophagy, termed mitophagy, contributes to mitochondrial quality and quantity control whose defects have been implicated in oxidative phosphorylation deficiency, aberrant cell differentiation, and neurodegeneration. How mitophagy is regulated in response to cellular physiology remains obscure. Here, we show that mitophagy in yeast is linked to the phospholipid biosynthesis pathway for conversion of phosphatidylethanolamine to phosphatidylcholine by the two methyltransferases Cho2 and Opi3. Under mitophagy-inducing conditions, cells lacking Opi3 exhibit retardation of Cho2 repression that causes an anomalous increase in glutathione levels, leading to suppression of Atg32, a mitochondria-anchored protein essential for mitophagy. In addition, loss of Opi3 results in accumulation of phosphatidylmonomethylethanolamine (PMME) and, surprisingly, generation of Atg8-PMME, a mitophagy-incompetent lipid conjugate of the autophagy-related ubiquitin-like modifier. Amelioration of Atg32 expression and attenuation of Atg8-PMME conjugation markedly rescue mitophagy in opi3-null cells. We propose that proper regulation of phospholipid methylation is crucial for Atg32-mediated mitophagy.
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Affiliation(s)
- Kaori Sakakibara
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Akinori Eiyama
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Sho W Suzuki
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan Frontier Research Center, Tokyo Institute of Technology, Kanagawa, Japan
| | | | - Nobuaki Okumura
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Motohiro Tani
- Department of Chemistry, Kyushu University, Fukuoka, Japan
| | - Ayako Hashimoto
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Sachiyo Nagumo
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | | | - Chika Kondo-Kakuta
- Frontier Research Center, Tokyo Institute of Technology, Kanagawa, Japan
| | - Eri Asai
- Frontier Research Center, Tokyo Institute of Technology, Kanagawa, Japan
| | - Hiromi Kirisako
- Frontier Research Center, Tokyo Institute of Technology, Kanagawa, Japan
| | - Hitoshi Nakatogawa
- Frontier Research Center, Tokyo Institute of Technology, Kanagawa, Japan
| | - Osamu Kuge
- Department of Chemistry, Kyushu University, Fukuoka, Japan
| | - Toshifumi Takao
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Yoshinori Ohsumi
- Frontier Research Center, Tokyo Institute of Technology, Kanagawa, Japan
| | - Koji Okamoto
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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213
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Xavier JM, Morgado AL, Rodrigues CM, Solá S. Tauroursodeoxycholic acid increases neural stem cell pool and neuronal conversion by regulating mitochondria-cell cycle retrograde signaling. Cell Cycle 2015; 13:3576-89. [PMID: 25483094 DOI: 10.4161/15384101.2014.962951] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The low survival and differentiation rates of stem cells after either transplantation or neural injury have been a major concern of stem cell-based therapy. Thus, further understanding long-term survival and differentiation of stem cells may uncover new targets for discovery and development of novel therapeutic approaches. We have previously described the impact of mitochondrial apoptosis-related events in modulating neural stem cell (NSC) fate. In addition, the endogenous bile acid, tauroursodeoxycholic acid (TUDCA) was shown to be neuroprotective in several animal models of neurodegenerative disorders by acting as an anti-apoptotic and anti-oxidant molecule at the mitochondrial level. Here, we hypothesize that TUDCA might also play a role on NSC fate decision. We found that TUDCA prevents mitochondrial apoptotic events typical of early-stage mouse NSC differentiation, preserves mitochondrial integrity and function, while enhancing self-renewal potential and accelerating cell cycle exit of NSCs. Interestingly, TUDCA prevention of mitochondrial alterations interfered with NSC differentiation potential by favoring neuronal rather than astroglial conversion. Finally, inhibition of mitochondrial reactive oxygen species (mtROS) scavenger and adenosine triphosphate (ATP) synthase revealed that the effect of TUDCA is dependent on mtROS and ATP regulation levels. Collectively, these data underline the importance of mitochondrial stress control of NSC fate decision and support a new role for TUDCA in this process.
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Key Words
- ATP
- ATP, adenosine triphosphate
- BrdU, bromodeoxyuridine
- CsA, cyclosporin A
- DiOC6(3), 3, 3′-dihexyloxacarbocyanine iodide
- FACS, fluorescence-activated cell sorting analysis
- GAPDH, glyceraldehyde 3-phosphate dehydrogenase
- GFAP, glial fibrillary acidic protein
- MnSOD, manganese superoxide dismutase
- NSC, neural stem cells
- OGG1, 8-oxoguanine DNA glycosylase
- OligA, oligomycin A
- ROS, reactive oxygen species
- Sox2, sex determining region Y- box 2
- TUDCA, tauroursodeoxycholic acid
- UDCA, ursodeoxycholic acid
- VDAC, voltage-dependent anion channel
- cdk, cyclin-dependent kinase
- cell cycle
- mitochondrial oxidative stress
- mtDNA, mitochondrial DNA
- mtROS, mitochondrial reactive oxygen species
- neural stem cell fate
- tauroursodeoxycholic acid
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Affiliation(s)
- Joana M Xavier
- a Research Institute for Medicines (iMed.ULisboa) ; Faculty of Pharmacy ; Universidade de Lisboa ; Lisbon , Portugal
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The Organization of Mitochondrial Quality Control and Life Cycle in the Nervous System In Vivo in the Absence of PINK1. J Neurosci 2015; 35:9391-401. [PMID: 26109662 DOI: 10.1523/jneurosci.1198-15.2015] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Maintenance of healthy mitochondria is crucial in cells, such as neurons, with high metabolic demands, and dysfunctional mitochondria are thought to be selectively degraded. Studies of chemically uncoupled cells have implicated PINK1 mitochondrial kinase, and Parkin E3 ubiquitin ligase in targeting depolarized mitochondria for degradation. However, the role of the PINK1/Parkin pathway in mitochondrial turnover is unclear in the nervous system under normal physiological conditions, and we understand little about the changes that occur in the mitochondrial life cycle when turnover is disrupted. Here, we evaluated the nature, location, and regulation of quality control in vivo using quantitative measurements of mitochondria in Drosophila nervous system, with deletion and overexpression of genes in the PINK1/Parkin pathway. We tested the hypotheses that impairment of mitochondrial quality control via suppression of PINK1 function should produce failures of turnover, accumulation of senescent mitochondria in the axon, defects in mitochondrial traffic, and a significant shift in the mitochondrial fission-fusion steady state. Although mitochondrial membrane potential was diminished by PINK1 deletion, we did not observe the predicted increases in mitochondrial density or length in axons. Loss of PINK1 also produced specific, directionally balanced defects in mitochondrial transport, without altering the balance between stationary and moving mitochondria. Somatic mitochondrial morphology was also compromised. These results strongly circumscribe the possible mechanisms of PINK1 action in the mitochondrial life cycle and also raise the possibility that mitochondrial turnover events that occur in cultured embryonic axons might be restricted to the cell body in vivo, in the intact nervous system.
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215
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Controlled and Impaired Mitochondrial Quality in Neurons: Molecular Physiology and Prospective Pharmacology. Pharmacol Res 2015; 99:410-24. [DOI: 10.1016/j.phrs.2015.03.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 03/27/2015] [Accepted: 03/27/2015] [Indexed: 01/08/2023]
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216
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Arnould T, Michel S, Renard P. Mitochondria Retrograde Signaling and the UPR mt: Where Are We in Mammals? Int J Mol Sci 2015; 16:18224-51. [PMID: 26258774 PMCID: PMC4581242 DOI: 10.3390/ijms160818224] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 06/26/2015] [Accepted: 07/24/2015] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial unfolded protein response is a form of retrograde signaling that contributes to ensuring the maintenance of quality control of mitochondria, allowing functional integrity of the mitochondrial proteome. When misfolded proteins or unassembled complexes accumulate beyond the folding capacity, it leads to alteration of proteostasis, damages, and organelle/cell dysfunction. Extensively studied for the ER, it was recently reported that this kind of signaling for mitochondrion would also be able to communicate with the nucleus in response to impaired proteostasis. The mitochondrial unfolded protein response (UPRmt) is activated in response to different types and levels of stress, especially in conditions where unfolded or misfolded mitochondrial proteins accumulate and aggregate. A specific UPRmt could thus be initiated to boost folding and degradation capacity in response to unfolded and aggregated protein accumulation. Although first described in mammals, the UPRmt was mainly studied in Caenorhabditis elegans, and accumulating evidence suggests that mechanisms triggered in response to a UPRmt might be different in C. elegans and mammals. In this review, we discuss and integrate recent data from the literature to address whether the UPRmt is relevant to mitochondrial homeostasis in mammals and to analyze the putative role of integrated stress response (ISR) activation in response to the inhibition of mtDNA expression and/or accumulation of mitochondrial mis/unfolded proteins.
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Affiliation(s)
- Thierry Arnould
- Laboratory of Biochemistry and Cell Biology (URBC), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium.
| | - Sébastien Michel
- Laboratory of Biochemistry and Cell Biology (URBC), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium.
- Department of Physiology, University of Lausanne, Rue du Bugnon 7, CH-1005 Lausanne, Switzerland.
| | - Patricia Renard
- Laboratory of Biochemistry and Cell Biology (URBC), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium.
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217
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Diot A, Hinks-Roberts A, Lodge T, Liao C, Dombi E, Morten K, Brady S, Fratter C, Carver J, Muir R, Davis R, Green CJ, Johnston I, Hilton-Jones D, Sue C, Mortiboys H, Poulton J. A novel quantitative assay of mitophagy: Combining high content fluorescence microscopy and mitochondrial DNA load to quantify mitophagy and identify novel pharmacological tools against pathogenic heteroplasmic mtDNA. Pharmacol Res 2015. [PMID: 26196248 DOI: 10.1016/j.phrs.2015.07.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mitophagy is a cellular mechanism for the recycling of mitochondrial fragments. This process is able to improve mitochondrial DNA (mtDNA) quality in heteroplasmic mtDNA disease, in which mutant mtDNA co-exists with normal mtDNA. In disorders where the load of mutant mtDNA determines disease severity it is likely to be an important determinant of disease progression. Measuring mitophagy is technically demanding. We used pharmacological modulators of autophagy to validate two techniques for quantifying mitophagy. First we used the IN Cell 1000 analyzer to quantify mitochondrial co-localisation with LC3-II positive autophagosomes. Unlike conventional fluorescence and electron microscopy, this high-throughput system is sufficiently sensitive to detect transient low frequency autophagosomes. Secondly, because mitophagy preferentially removes pathogenic heteroplasmic mtDNA mutants, we developed a heteroplasmy assay based on loss of m.3243A>G mtDNA, during culture conditions requiring oxidative metabolism ("energetic stress"). The effects of the pharmacological modulators on these two measures were consistent, confirming that the high throughput imaging output (autophagosomes co-localising with mitochondria) reflects mitochondrial quality control. To further validate these methods, we performed a more detailed study using metformin, the most commonly prescribed antidiabetic drug that is still sometimes used in Maternally Inherited Diabetes and Deafness (MIDD). This confirmed our initial findings and revealed that metformin inhibits mitophagy at clinically relevant concentrations, suggesting that it may have novel therapeutic uses.
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Affiliation(s)
- Alan Diot
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Alex Hinks-Roberts
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Tiffany Lodge
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Chunyan Liao
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Eszter Dombi
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Karl Morten
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Stefen Brady
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Carl Fratter
- Oxford Medical Genetics Laboratory, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK
| | - Janet Carver
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Rebecca Muir
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Ryan Davis
- Department of Neurogenetics, Kolling Institute of Medical Research, University of Sydney and Royal North Shore Hospital, Sydney, Australia
| | - Charlotte J Green
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Iain Johnston
- Department of Mathematics, Imperial College London, London, UK
| | | | - Carolyn Sue
- Department of Neurogenetics, Kolling Institute of Medical Research, University of Sydney and Royal North Shore Hospital, Sydney, Australia
| | - Heather Mortiboys
- Department of Neuroscience, Sheffield Institute of Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK.
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218
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The complex crosstalk between mitochondria and the nucleus: What goes in between? Int J Biochem Cell Biol 2015; 63:10-5. [DOI: 10.1016/j.biocel.2015.01.026] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 01/21/2015] [Accepted: 01/29/2015] [Indexed: 12/22/2022]
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219
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Abstract
Recent advances in mitochondrial biology have revealed the high diversity and complexity of proteolytic enzymes that regulate mitochondrial function. We have classified mitochondrial proteases, or mitoproteases, on the basis of their function and location, and defined the human mitochondrial degradome as the complete set of mitoproteases that are encoded by the human genome. In addition to their nonspecific degradative functions, mitoproteases perform highly regulated proteolytic reactions that are important in mitochondrial function, integrity and homeostasis. These include protein synthesis, quality control, mitochondrial biogenesis and dynamics, mitophagy and apoptosis. Impaired or dysregulated function of mitoproteases is associated with ageing and with many pathological conditions such as neurodegenerative disorders, metabolic syndromes and cancer. A better understanding of the mitochondrial proteolytic landscape and its modulation may contribute to improving human lifespan and 'healthspan'.
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220
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Abstract
Mitochondria are organelles derived from primitive symbiosis between archeon ancestors and prokaryotic α-proteobacteria species, which lost the capacity of synthetizing most proteins encoded the bacterial DNA, along the evolutionary process of eukaryotes. Nowadays, mitochondria are constituted by small circular mitochondrial DNA of 16 kb, responsible for the control of several proteins, including polypeptides of the electron transport chain. Throughout evolution, these organelles acquired the capacity of regulating energy production and metabolism, thus becoming central modulators of cell fate. In fact, mitochondria are crucial for a variety of cellular processes, including adenosine triphosphate production by oxidative phosphorylation, intracellular Ca(2+) homeostasis, generation of reactive oxygen species, and also cellular specialization in a variety of tissues that ultimately relies on specific mitochondrial specialization and maturation. In this review, we discuss recent evidence extending the importance of mitochondrial function and energy metabolism to the context of neuronal development and adult neurogenesis.
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Affiliation(s)
- Joana M Xavier
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Cecília M P Rodrigues
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Susana Solá
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
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221
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Bohovych I, Chan SS, Khalimonchuk O. Mitochondrial protein quality control: the mechanisms guarding mitochondrial health. Antioxid Redox Signal 2015; 22:977-94. [PMID: 25546710 PMCID: PMC4390190 DOI: 10.1089/ars.2014.6199] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 12/20/2014] [Indexed: 12/20/2022]
Abstract
SIGNIFICANCE Mitochondria are complex dynamic organelles pivotal for cellular physiology and human health. Failure to maintain mitochondrial health leads to numerous maladies that include late-onset neurodegenerative diseases and cardiovascular disorders. Furthermore, a decline in mitochondrial health is prevalent with aging. A set of evolutionary conserved mechanisms known as mitochondrial quality control (MQC) is involved in recognition and correction of the mitochondrial proteome. RECENT ADVANCES Here, we review current knowledge and latest developments in MQC. We particularly focus on the proteolytic aspect of MQC and its impact on health and aging. CRITICAL ISSUES While our knowledge about MQC is steadily growing, critical gaps remain in the mechanistic understanding of how MQC modules sense damage and preserve mitochondrial welfare, particularly in higher organisms. FUTURE DIRECTIONS Delineating how coordinated action of the MQC modules orchestrates physiological responses on both organellar and cellular levels will further elucidate the current picture of MQC's role and function in health, cellular stress, and degenerative diseases.
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Affiliation(s)
- Iryna Bohovych
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska
- Nebraska Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Sherine S.L. Chan
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina
| | - Oleh Khalimonchuk
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska
- Nebraska Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska
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222
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Schulz AM, Haynes CM. UPR(mt)-mediated cytoprotection and organismal aging. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1448-56. [PMID: 25857997 DOI: 10.1016/j.bbabio.2015.03.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 03/25/2015] [Accepted: 03/28/2015] [Indexed: 12/20/2022]
Abstract
Time- or age-dependent accumulation of mitochondrial damage and dysfunction is strongly associated with aging [1]. Thus, a major biomedical goal is to identify and therapeutically manipulate those inherent programs that protect against mitochondrial dysfunction to promote cell survival and organismal health. The mitochondrial unfolded protein response (UPR(mt)) is such a protective transcriptional response mediated by mitochondrial-to-nuclear signaling that includes mitochondrial proteostasis genes to stabilize mitochondrial function, metabolic adaptations, as well as an innate immunity program. Here, we review the UPR(mt) and its role during a variety of forms of mitochondrial dysfunction including those caused by mutations in respiratory chain genes as well as upon exposure to pathogens that produce mitochondrial toxins. We also review recent data in support of and against the emerging role of the UPR(mt) during aging and longevity. This article is part of a Special Issue entitled: Mitochondrial Dysfunction in Aging.
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Affiliation(s)
- Anna M Schulz
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
| | - Cole M Haynes
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; BCMB Allied Program, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA.
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223
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Biochemical properties of the kinase PINK1 as sensor protein for mitochondrial damage signalling. Biochem Soc Trans 2015; 43:287-91. [DOI: 10.1042/bst20150005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Defects of mitochondrial functions have been implicated in many different human diseases, in particular neurodegenerative diseases. The kinase PINK1 [phosphatase and tensin homologue (PTEN)-induced kinase 1] has been identified as a crucial player in a specific damage signalling pathway, eliminating defective mitochondria by an autophagic process. Mutations in PINK1 have been shown to cause familial cases of Parkinson's disease. In this review, we summarize the biochemical mechanisms that underlie the association of PINK1 with mitochondria under normal and pathological conditions. This unconventional mitochondrial localization pathway is discussed in the context of the role of PINK1 as a sensor of mitochondrial damage and a causative factor in Parkinson's disease.
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224
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Nargund AM, Fiorese CJ, Pellegrino MW, Deng P, Haynes CM. Mitochondrial and nuclear accumulation of the transcription factor ATFS-1 promotes OXPHOS recovery during the UPR(mt). Mol Cell 2015; 58:123-33. [PMID: 25773600 DOI: 10.1016/j.molcel.2015.02.008] [Citation(s) in RCA: 306] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 11/11/2014] [Accepted: 02/03/2015] [Indexed: 12/29/2022]
Abstract
Mitochondrial diseases and aging are associated with defects in the oxidative phosphorylation machinery (OXPHOS), which are the only complexes composed of proteins encoded by separate genomes. To better understand genome coordination and OXPHOS recovery during mitochondrial dysfunction, we examined ATFS-1, a transcription factor that regulates mitochondria-to-nuclear communication during the mitochondrial UPR, via ChIP-sequencing. Surprisingly, in addition to regulating mitochondrial chaperone, OXPHOS complex assembly factor, and glycolysis genes, ATFS-1 bound directly to OXPHOS gene promoters in both the nuclear and mitochondrial genomes. Interestingly, atfs-1 was required to limit the accumulation of OXPHOS transcripts during mitochondrial stress, which required accumulation of ATFS-1 in the nucleus and mitochondria. Because balanced ATFS-1 accumulation promoted OXPHOS complex assembly and function, our data suggest that ATFS-1 stimulates respiratory recovery by fine-tuning OXPHOS expression to match the capacity of the suboptimal protein-folding environment in stressed mitochondria, while simultaneously increasing proteostasis capacity.
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Affiliation(s)
- Amrita M Nargund
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Christopher J Fiorese
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; BCMB Allied Program, Weill Cornell Medical College, New York, NY 10065, USA
| | - Mark W Pellegrino
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Pan Deng
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; BCMB Allied Program, Weill Cornell Medical College, New York, NY 10065, USA
| | - Cole M Haynes
- Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; BCMB Allied Program, Weill Cornell Medical College, New York, NY 10065, USA.
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225
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Eiyama A, Okamoto K. PINK1/Parkin-mediated mitophagy in mammalian cells. Curr Opin Cell Biol 2015; 33:95-101. [PMID: 25697963 DOI: 10.1016/j.ceb.2015.01.002] [Citation(s) in RCA: 373] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 01/09/2015] [Indexed: 12/11/2022]
Abstract
Mitochondria-specific autophagy (mitophagy) is a fundamental process critical for maintaining mitochondrial fitness in a myriad of cell types. Particularly, mitophagy contributes to mitochondrial quality control by selectively eliminating dysfunctional mitochondria. In mammalian cells, the Ser/Thr kinase PINK1 and the E3 ubiquitin ligase Parkin act cooperatively in sensing mitochondrial functional state and marking damaged mitochondria for disposal via the autophagy pathway. Notably, ubiquitin and deubiquitinases play vital roles in modulating Parkin activity and mitophagy efficiency. In this review, we highlight recent breakthroughs addressing the key issues of how PINK1 activates Parkin in response to mitochondrial malfunction, how Parkin localizes specifically to impaired mitochondria, and how ubiquitination and deubiquitination regulate PINK1/Parkin-mediated mitophagy.
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Affiliation(s)
- Akinori Eiyama
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Koji Okamoto
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan.
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226
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Iommarini L, Peralta S, Torraco A, Diaz F. Mitochondrial Diseases Part II: Mouse models of OXPHOS deficiencies caused by defects in regulatory factors and other components required for mitochondrial function. Mitochondrion 2015; 22:96-118. [PMID: 25640959 DOI: 10.1016/j.mito.2015.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/22/2015] [Indexed: 01/21/2023]
Abstract
Mitochondrial disorders are defined as defects that affect the oxidative phosphorylation system (OXPHOS). They are characterized by a heterogeneous array of clinical presentations due in part to a wide variety of factors required for proper function of the components of the OXPHOS system. There is no cure for these disorders owing to our poor knowledge of the pathogenic mechanisms of disease. To understand the mechanisms of human disease numerous mouse models have been developed in recent years. Here we summarize the features of several mouse models of mitochondrial diseases directly related to those factors affecting mtDNA maintenance, replication, transcription, translation as well as other proteins that are involved in mitochondrial dynamics and quality control which affect mitochondrial OXPHOS function without being intrinsic components of the system. We discuss how these models have contributed to our understanding of mitochondrial diseases and their pathogenic mechanisms.
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Affiliation(s)
- Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40128 Bologna, Italy.
| | - Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Alessandra Torraco
- Unit for Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15 - 00146, Rome, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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227
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Busch KB, Kowald A, Spelbrink JN. Quality matters: how does mitochondrial network dynamics and quality control impact on mtDNA integrity? Philos Trans R Soc Lond B Biol Sci 2015; 369:20130442. [PMID: 24864312 DOI: 10.1098/rstb.2013.0442] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Mammalian mtDNA encodes for 13 core proteins of oxidative phosphorylation. Mitochondrial DNA mutations and deletions cause severe myopathies and neuromuscular diseases. Thus, the integrity of mtDNA is pivotal for cell survival and health of the organism. We here discuss the possible impact of mitochondrial fusion and fission on mtDNA maintenance as well as positive and negative selection processes. Our focus is centred on the important question of how the quality of mtDNA nucleoids can be assured when selection and mitochondrial quality control works on functional and physiological phenotypes constituted by oxidative phosphorylation proteins. The organelle control theory suggests a link between phenotype and nucleoid genotype. This is discussed in the light of new results presented here showing that mitochondrial transcription factor A/nucleoids are restricted in their intramitochondrial mobility and probably have a limited sphere of influence. Together with recent published work on mitochondrial and mtDNA heteroplasmy dynamics, these data suggest first, that single mitochondria might well be internally heterogeneous and second, that nucleoid genotypes might be linked to local phenotypes (although the link might often be leaky). We discuss how random or site-specific mitochondrial fission can isolate dysfunctional parts and enable their elimination by mitophagy, stressing the importance of fission in the process of mtDNA quality control. The role of fusion is more multifaceted and less understood in this context, but the mixing and equilibration of matrix content might be one of its important functions.
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Affiliation(s)
- Karin B Busch
- Division of Mitochondrial Dynamics, School of Biology and Chemistry, University of Osnabrück, 49069 Osnabrück, Germany
| | - Axel Kowald
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
| | - Johannes N Spelbrink
- Department of Pediatrics, Nijmegen Centre for Mitochondrial Disorders, Radboud University Medical Centre, Geert Grooteplein 10, PO Box 9101, 6500 HB Nijmegen, The Netherlands FinMIT Centre of Excellence, Institute of Biomedical Technology and Tampere University Hospital, Pirkanmaa Hospital District, 33014 Tampere, Finland
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228
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Chiang H, Ohno N, Hsieh YL, Mahad DJ, Kikuchi S, Komuro H, Hsieh ST, Trapp BD. Mitochondrial fission augments capsaicin-induced axonal degeneration. Acta Neuropathol 2015; 129:81-96. [PMID: 25322817 PMCID: PMC4282704 DOI: 10.1007/s00401-014-1354-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 10/01/2014] [Accepted: 10/02/2014] [Indexed: 12/31/2022]
Abstract
Capsaicin, an agonist of transient receptor potential vanilloid receptor 1, induces axonal degeneration of peripheral sensory nerves and is commonly used to treat painful sensory neuropathies. In this study, we investigated the role of mitochondrial dynamics in capsaicin-induced axonal degeneration. In capsaicin-treated rodent sensory axons, axonal swellings, decreased mitochondrial stationary site length and reduced mitochondrial transport preceded axonal degeneration. Increased axoplasmic Ca(2+) mediated the alterations in mitochondrial length and transport. While sustaining mitochondrial transport did not reduce axonal swellings in capsaicin-treated axons, preventing mitochondrial fission by overexpression of mutant dynamin-related protein 1 increased mitochondrial length, retained mitochondrial membrane potentials and reduced axonal loss upon capsaicin treatment. These results establish that mitochondrial stationary site size significantly affects axonal integrity and suggest that inhibition of Ca(2+)-dependent mitochondrial fission facilitates mitochondrial function and axonal survival following activation of axonal cationic channels.
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Affiliation(s)
- Hao Chiang
- Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, 10051 Taiwan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
| | - Nobuhiko Ohno
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- Present Address: Department of Anatomy and Molecular Histology, University of Yamanashi, Chuo, Yamanashi 409-3898 Japan
| | - Yu-Lin Hsieh
- Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, 10051 Taiwan
- Present Address: Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708 Taiwan
| | - Don J. Mahad
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- Present Address: Centre for Neuroregeneration, University of Edinburgh, Chancellor’s Building, Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB UK
| | - Shin Kikuchi
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
- Present Address: Department of Anatomy 1, Sapporo Medical University School of Medicine, West 17, South 1, Chuo-ku, Sapporo, 060-8556 Japan
| | - Hitoshi Komuro
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
| | - Sung-Tsang Hsieh
- Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, 10051 Taiwan
- Department of Neurology, National Taiwan University Hospital, Taipei, 10002 Taiwan
| | - Bruce D. Trapp
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195 USA
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229
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230
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Celardo I, Martins LM, Gandhi S. Unravelling mitochondrial pathways to Parkinson's disease. Br J Pharmacol 2014; 171:1943-57. [PMID: 24117181 PMCID: PMC3976614 DOI: 10.1111/bph.12433] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 09/09/2013] [Accepted: 09/17/2013] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are essential for cellular function due to their role in ATP production, calcium homeostasis and apoptotic signalling. Neurons are heavily reliant on mitochondrial integrity for their complex signalling, plasticity and excitability properties, and to ensure cell survival over decades. The maintenance of a pool of healthy mitochondria that can meet the bioenergetic demands of a neuron, is therefore of critical importance; this is achieved by maintaining a careful balance between mitochondrial biogenesis, mitochondrial trafficking, mitochondrial dynamics and mitophagy. The molecular mechanisms that underlie these processes are gradually being elucidated. It is widely recognized that mitochondrial dysfunction occurs in many neurodegenerative diseases, including Parkinson's disease. Mitochondrial dysfunction in the form of reduced bioenergetic capacity, increased oxidative stress and reduced resistance to stress, is observed in several Parkinson's disease models. However, identification of the recessive genes implicated in Parkinson's disease has revealed a common pathway involving mitochondrial dynamics, transport, turnover and mitophagy. This body of work has led to the hypothesis that the homeostatic mechanisms that ensure a healthy mitochondrial pool are key to neuronal function and integrity. In this paradigm, impaired mitochondrial dynamics and clearance result in the accumulation of damaged and dysfunctional mitochondria, which may directly induce neuronal dysfunction and death. In this review, we consider the mechanisms by which mitochondrial dysfunction may lead to neurodegeneration. In particular, we focus on the mechanisms that underlie mitochondrial homeostasis, and discuss their importance in neuronal integrity and neurodegeneration in Parkinson's disease.
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231
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Rainbolt TK, Saunders JM, Wiseman RL. YME1L degradation reduces mitochondrial proteolytic capacity during oxidative stress. EMBO Rep 2014; 16:97-106. [PMID: 25433032 DOI: 10.15252/embr.201438976] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Mitochondrial proteostasis is maintained by a network of ATP-dependent quality control proteases including the inner membrane protease YME1L. Here, we show that YME1L is a stress-sensitive mitochondrial protease that is rapidly degraded in response to acute oxidative stress. This degradation requires reductions in cellular ATP and involves the activity of the ATP-independent protease OMA1. Oxidative stress-dependent reductions in YME1L inhibit protective YME1L-dependent functions and increase cellular sensitivity to oxidative insult. Collectively, our results identify stress-induced YME1L degradation as a biologic process that attenuates protective regulation of mitochondrial proteostasis and promotes cellular death in response to oxidative stress.
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Affiliation(s)
- T Kelly Rainbolt
- Department of Molecular & Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Jaclyn M Saunders
- Department of Molecular & Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - R Luke Wiseman
- Department of Molecular & Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
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232
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Schatten H, Sun QY, Prather R. The impact of mitochondrial function/dysfunction on IVF and new treatment possibilities for infertility. Reprod Biol Endocrinol 2014; 12:111. [PMID: 25421171 PMCID: PMC4297407 DOI: 10.1186/1477-7827-12-111] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 09/04/2014] [Indexed: 11/12/2022] Open
Abstract
Mitochondria play vital roles in oocyte functions and they are critical indicators of oocyte quality which is important for fertilization and development into viable offspring. Quality-compromised oocytes are correlated with infertility, developmental disorders, reduced blastocyst cell number and embryo loss in which mitochondrial dysfunctions play a significant role. Increasingly, women affected by metabolic disorders such as diabetes or obesity and oocyte aging are seeking treatment in IVF clinics to overcome the effects of adverse metabolic conditions on mitochondrial functions and new treatments have become available to restore oocyte quality. The past decade has seen enormous advances in potential therapies to restore oocyte quality and includes dietary components and transfer of mitochondria from cells with mitochondrial integrity into mitochondria-impaired oocytes. New technologies have opened up new possibilities for therapeutic advances which will increase the success rates for IVF of oocytes from women with compromised oocyte quality.
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Affiliation(s)
- Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO USA
| | - Qing-Yuan Sun
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, 100080 Beijing, China
| | - Randall Prather
- National Swine Resource and Research Center, University of Missouri, 65211 Columbia, USA
- Division of Animal Science, University of Missouri, 65211 Columbia, USA
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233
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Plum S, Steinbach S, Abel L, Marcus K, Helling S, May C. Proteomics in neurodegenerative diseases: Methods for obtaining a closer look at the neuronal proteome. Proteomics Clin Appl 2014; 9:848-71. [DOI: 10.1002/prca.201400030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/25/2014] [Accepted: 09/03/2014] [Indexed: 12/12/2022]
Affiliation(s)
- Sarah Plum
- Medizinisches Proteom-Center; Funktionelle Proteomik; Ruhr-Universität Bochum; Bochum Germany
| | - Simone Steinbach
- Medizinisches Proteom-Center; Medical Proteomics/Bioanalytics; Ruhr-Universität Bochum; Bochum Germany
| | - Laura Abel
- Medizinisches Proteom-Center; Medical Proteomics/Bioanalytics; Ruhr-Universität Bochum; Bochum Germany
| | - Katrin Marcus
- Medizinisches Proteom-Center; Funktionelle Proteomik; Ruhr-Universität Bochum; Bochum Germany
| | - Stefan Helling
- Medizinisches Proteom-Center; Funktionelle Proteomik; Ruhr-Universität Bochum; Bochum Germany
| | - Caroline May
- Medizinisches Proteom-Center; Medical Proteomics/Bioanalytics; Ruhr-Universität Bochum; Bochum Germany
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234
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A neuronal aging pattern unique to humans and common chimpanzees. Brain Struct Funct 2014; 221:647-64. [DOI: 10.1007/s00429-014-0931-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 10/24/2014] [Indexed: 12/27/2022]
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235
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Sekine S, Ichijo H. Mitochondrial proteolysis: its emerging roles in stress responses. Biochim Biophys Acta Gen Subj 2014; 1850:274-80. [PMID: 25459516 DOI: 10.1016/j.bbagen.2014.10.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 10/09/2014] [Accepted: 10/13/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Mitochondria are multifunctional organelles that not only serve as cellular energy stores but are also actively involved in several cellular stress responses, including apoptosis. In addition, mitochondria themselves are also continuously challenged by stresses such as reactive oxygen species (ROS), an inevitable by-product of oxidative phosphorylation. To exert various functions against these stresses, mitochondria must be equipped with appropriate stress responses that monitor and maintain their quality. SCOPE OF REVIEW Interestingly, increasing evidence indicates that mitochondrial proteolysis has important roles in mitochondrial and cellular stress responses. In this review, we summarize current advances in mitochondrial proteolysis-mediated stress responses. MAJOR CONCLUSIONS Mitochondrial proteases do not only function as surveillance systems of protein quality control by degrading unfolded proteins but also regulate mitochondrial stress responses by processing specific mitochondrial proteins. GENERAL SIGNIFICANCE Studies on the regulation of mitochondrial proteolysis-mediated stress responses will provide the novel mechanistic insights into the stress response research fields.
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Affiliation(s)
- Shiori Sekine
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hidenori Ichijo
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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236
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A viral peptide that targets mitochondria protects against neuronal degeneration in models of Parkinson’s disease. Nat Commun 2014; 5:5181. [DOI: 10.1038/ncomms6181] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 09/05/2014] [Indexed: 12/27/2022] Open
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237
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Rainbolt TK, Saunders JM, Wiseman RL. Stress-responsive regulation of mitochondria through the ER unfolded protein response. Trends Endocrinol Metab 2014; 25:528-37. [PMID: 25048297 DOI: 10.1016/j.tem.2014.06.007] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/18/2014] [Accepted: 06/19/2014] [Indexed: 12/31/2022]
Abstract
The endoplasmic reticulum (ER) and mitochondria form physical interactions involved in the regulation of biologic functions including mitochondrial bioenergetics and apoptotic signaling. To coordinate these functions during stress, cells must coregulate ER and mitochondria through stress-responsive signaling pathways such as the ER unfolded protein response (UPR). Although the UPR is traditionally viewed as a signaling pathway responsible for regulating ER proteostasis, it is becoming increasingly clear that the protein kinase RNA (PKR)-like endoplasmic reticulum kinase (PERK) signaling pathway within the UPR can also regulate mitochondria proteostasis and function in response to pathologic insults that induce ER stress. Here, we discuss the contributions of PERK in coordinating ER-mitochondrial activities and describe the mechanisms by which PERK adapts mitochondrial proteostasis and function in response to ER stress.
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Affiliation(s)
- T Kelly Rainbolt
- Department of Molecular and Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jaclyn M Saunders
- Department of Molecular and Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - R Luke Wiseman
- Department of Molecular and Experimental Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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238
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Lazarou M. Keeping the immune system in check: a role for mitophagy. Immunol Cell Biol 2014; 93:3-10. [DOI: 10.1038/icb.2014.75] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 08/18/2014] [Accepted: 08/18/2014] [Indexed: 12/21/2022]
Affiliation(s)
- Michael Lazarou
- Department of Biochemistry and Molecular Biology, Monash UniversityClaytonMelbourneAustralia
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239
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Abstract
Mitochondrial dysfunction is the underlying cause of many neurological disorders, including peripheral neuropathies. Mitochondria rely on a proton gradient to generate ATP and interfering with electron transport chain function can lead to the deleterious accumulation of reactive oxygen species (ROS). Notably, loss of mitochondrial potential precedes cellular demise in several programmed cell destruction pathways, including axons undergoing Wallerian degeneration. Here, we demonstrate that mitochondrial depolarization triggers axon degeneration and cell death in primary mouse sensory neurons. These degenerative events are not blocked by inhibitors of canonical programmed cell death pathways such as apoptosis, necroptosis, and parthanatos. Instead, the axodestructive factor Sarm1 is required for this axon degeneration and cell death. In the absence of Sarm1, the mitochondrial poison CCCP still induces depolarization of mitochondria, ATP depletion, calcium influx, and the accumulation of ROS, yet cell death and axon degeneration are blocked. The survival of these neurons despite the accumulation of ROS indicates that Sarm1 acts downstream of ROS generation. Indeed, loss of Sarm1 protects sensory neurons and their axons from prolonged exposure to ROS. Therefore, Sarm1 functions downstream of ROS to induce neuronal cell death and axon degeneration during oxidative stress. These findings highlight the central role for Sarm1 in a novel form of programmed cell destruction that we term sarmoptosis.
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240
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Zorov DB, Juhaszova M, Sollott SJ. Mitochondrial reactive oxygen species (ROS) and ROS-induced ROS release. Physiol Rev 2014; 94:909-50. [PMID: 24987008 DOI: 10.1152/physrev.00026.2013] [Citation(s) in RCA: 3187] [Impact Index Per Article: 318.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Byproducts of normal mitochondrial metabolism and homeostasis include the buildup of potentially damaging levels of reactive oxygen species (ROS), Ca(2+), etc., which must be normalized. Evidence suggests that brief mitochondrial permeability transition pore (mPTP) openings play an important physiological role maintaining healthy mitochondria homeostasis. Adaptive and maladaptive responses to redox stress may involve mitochondrial channels such as mPTP and inner membrane anion channel (IMAC). Their activation causes intra- and intermitochondrial redox-environment changes leading to ROS release. This regenerative cycle of mitochondrial ROS formation and release was named ROS-induced ROS release (RIRR). Brief, reversible mPTP opening-associated ROS release apparently constitutes an adaptive housekeeping function by the timely release from mitochondria of accumulated potentially toxic levels of ROS (and Ca(2+)). At higher ROS levels, longer mPTP openings may release a ROS burst leading to destruction of mitochondria, and if propagated from mitochondrion to mitochondrion, of the cell itself. The destructive function of RIRR may serve a physiological role by removal of unwanted cells or damaged mitochondria, or cause the pathological elimination of vital and essential mitochondria and cells. The adaptive release of sufficient ROS into the vicinity of mitochondria may also activate local pools of redox-sensitive enzymes involved in protective signaling pathways that limit ischemic damage to mitochondria and cells in that area. Maladaptive mPTP- or IMAC-related RIRR may also be playing a role in aging. Because the mechanism of mitochondrial RIRR highlights the central role of mitochondria-formed ROS, we discuss all of the known ROS-producing sites (shown in vitro) and their relevance to the mitochondrial ROS production in vivo.
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Affiliation(s)
- Dmitry B Zorov
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Magdalena Juhaszova
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Steven J Sollott
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia; and Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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241
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Abstract
Mitochondrial disease resulting in reduced bioenergetic output can be due to mutations in either nuclear DNA-encoded or mitochondrial DNA-encoded gene products. We summarize some of the underlying principles of mitochondrial genetics that impact the diagnosis and pathogenesis of mitochondrial disorders. In addition, we present a brief overview of a new frontier in the field, namely, mitochondrial "dynamics," which controls organellar fusion, fission, trafficking, and positioning, and exerts mitochondrial "quality control" by maintaining organellar integrity and viability. Analysis of mutations in gene products associated with this latter area has opened up new vistas in the study of disorders associated with compromised energy production.
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Affiliation(s)
- Estela Area-Gomez
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Eric A Schon
- Department of Neurology, Columbia University Medical Center, New York, NY, USA Department of Genetics and Development, Columbia University Medical Center, New York, NY, USA
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242
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Xavier JM, Morgado AL, Solá S, Rodrigues CMP. Mitochondrial translocation of p53 modulates neuronal fate by preventing differentiation-induced mitochondrial stress. Antioxid Redox Signal 2014; 21:1009-24. [PMID: 24329038 PMCID: PMC4123470 DOI: 10.1089/ars.2013.5417] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIMS Apoptosis regulatory proteins, such as p53, play a pivotal role in neural differentiation, through mechanisms independent of cell death. In addition, p53 has been identified as an important regulator of mitochondrial survival response, maintaining mitochondrial DNA (mtDNA) integrity and oxidative protection. The aim of this study was to determine the role of mitochondrial p53 in organelle damage and neural differentiation. RESULTS Our results show that mitochondrial apoptotic events such as reactive oxygen species production, mitochondrial membrane permeabilization, and cytochrome c release are typical of early-stage mouse neural stem cell differentiation, which occurs 3-18 h after induction of differentiation, with no evidence of cell death. In addition, decreased mtDNA content, lipidated LC3 (LC3-II), colocalization of mitochondria and LC3-II puncta, and mitochondria-associated Parkin are consistent with activation of mitophagy. Importantly, at early stages of neural differentiation, p53 was actively translocated to mitochondria and attenuated mitochondrial oxidative stress, cytochrome c release, and mitophagy. Forced mitochondrial translocation of p53 increased neurogenic potential and neurite outgrowth. INNOVATION AND CONCLUSION In conclusion, our results reveal a novel role for mitochondrial p53, which modulates mitochondrial damage and apoptosis-related events in the context of neural differentiation, thus enhancing neuronal fate.
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Affiliation(s)
- Joana M Xavier
- Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa , Lisboa, Portugal
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243
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Purnell PR, Fox HS. Efavirenz induces neuronal autophagy and mitochondrial alterations. J Pharmacol Exp Ther 2014; 351:250-8. [PMID: 25161171 DOI: 10.1124/jpet.114.217869] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Efavirenz (EFV) is a non-nucleoside reverse-transcriptase inhibitor in wide use for the treatment of human immunodeficiency virus infection. Although EFV is generally well tolerated, neuropsychiatric toxicity has been well documented. The toxic effects of EFV in hepatocytes and keratinocytes have been linked to mitochondrial perturbations and changes in autophagy. Here, we studied the effect of EFV on mitochondria and autophagy in neuronal cell lines and primary neurons. In SH-SY5Y cells, EFV induced a drop in ATP production, which coincided with increased autophagy, mitochondrial fragmentation, and mitochondrial depolarization. EFV-induced mitophagy was also detected by colocalization of mitochondria and autophagosomes and use of an outer mitochondrial membrane tandem fluorescent vector. Pharmacologic inhibition of autophagy with 3-methyladenine increased the cytotoxic effect of EFV, suggesting that autophagy promotes cell survival. EFV also reduces ATP production in primary neurons, induces autophagy, and changes mitochondrial morphology. Overall, EFV is able to acutely induce autophagy and mitochondrial changes in neurons. These changes may be involved in the mechanism leading to central nervous system toxicity observed in clinical EFV use.
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Affiliation(s)
- Phillip R Purnell
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska
| | - Howard S Fox
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska
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244
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González-Mariscal I, García-Testón E, Padilla S, Martín-Montalvo A, Pomares Viciana T, Vazquez-Fonseca L, Gandolfo Domínguez P, Santos-Ocaña C. The regulation of coenzyme q biosynthesis in eukaryotic cells: all that yeast can tell us. Mol Syndromol 2014; 5:107-18. [PMID: 25126044 DOI: 10.1159/000362897] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Coenzyme Q (CoQ) is a mitochondrial lipid, which functions mainly as an electron carrier from complex I or II to complex III at the mitochondrial inner membrane, and also as antioxidant in cell membranes. CoQ is needed as electron acceptor in β-oxidation of fatty acids and pyridine nucleotide biosynthesis, and it is responsible for opening the mitochondrial permeability transition pore. The yeast model has been very useful to analyze the synthesis of CoQ, and therefore, most of the knowledge about its regulation was obtained from the Saccharomyces cerevisiae model. CoQ biosynthesis is regulated to support 2 processes: the bioenergetic metabolism and the antioxidant defense. Alterations of the carbon source in yeast, or in nutrient availability in yeasts or mammalian cells, upregulate genes encoding proteins involved in CoQ synthesis. Oxidative stress, generated by chemical or physical agents or by serum deprivation, modifies specifically the expression of some COQ genes by means of stress transcription factors such as Msn2/4p, Yap1p or Hsf1p. In general, the induction of COQ gene expression produced by metabolic changes or stress is modulated downstream by other regulatory mechanisms such as the protein import to mitochondria, the assembly of a multi-enzymatic complex composed by Coq proteins and also the existence of a phosphorylation cycle that regulates the last steps of CoQ biosynthesis. The CoQ biosynthetic complex assembly starts with the production of a nucleating lipid such as HHB by the action of the Coq2 protein. Then, the Coq4 protein recognizes the precursor HHB acting as the nucleus of the complex. The activity of Coq8p, probably as kinase, allows the formation of an initial pre-complex containing all Coq proteins with the exception of Coq7p. This pre-complex leads to the synthesis of 5-demethoxy-Q6 (DMQ6), the Coq7p substrate. When de novo CoQ biosynthesis is required, Coq7p becomes dephosphorylated by the action of Ptc7p increasing the synthesis rate of CoQ6. This critical model is needed for a better understanding of CoQ biosynthesis. Taking into account that patients with CoQ10 deficiency maintain to some extent the machinery to synthesize CoQ, new promising strategies for the treatment of CoQ10 deficiency will require a better understanding of the regulation of CoQ biosynthesis in the future.
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Affiliation(s)
| | - Elena García-Testón
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide - CSIC, and CIBERER Instituto de Salud Carlos III, Seville, Spain
| | - Sergio Padilla
- Sanford Children's Health Research Center, Sanford Research USD, Sioux Falls, S. Dak., USA
| | | | - Teresa Pomares Viciana
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide - CSIC, and CIBERER Instituto de Salud Carlos III, Seville, Spain
| | - Luis Vazquez-Fonseca
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide - CSIC, and CIBERER Instituto de Salud Carlos III, Seville, Spain
| | - Pablo Gandolfo Domínguez
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide - CSIC, and CIBERER Instituto de Salud Carlos III, Seville, Spain
| | - Carlos Santos-Ocaña
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide - CSIC, and CIBERER Instituto de Salud Carlos III, Seville, Spain
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245
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Nunn AVW, Guy GW, Bell JD. The intelligence paradox; will ET get the metabolic syndrome? Lessons from and for Earth. Nutr Metab (Lond) 2014; 11:34. [PMID: 25089149 PMCID: PMC4118160 DOI: 10.1186/1743-7075-11-34] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 07/18/2014] [Indexed: 12/21/2022] Open
Abstract
Mankind is facing an unprecedented health challenge in the current pandemic of obesity and diabetes. We propose that this is the inevitable (and predictable) consequence of the evolution of intelligence, which itself could be an expression of life being an information system driven by entropy. Because of its ability to make life more adaptable and robust, intelligence evolved as an efficient adaptive response to the stresses arising from an ever-changing environment. These adaptive responses are encapsulated by the epiphenomena of "hormesis", a phenomenon we believe to be central to the evolution of intelligence and essential for the maintenance of optimal physiological function and health. Thus, as intelligence evolved, it would eventually reach a cognitive level with the ability to control its environment through technology and have the ability remove all stressors. In effect, it would act to remove the very hormetic factors that had driven its evolution. Mankind may have reached this point, creating an environmental utopia that has reduced the very stimuli necessary for optimal health and the evolution of intelligence - "the intelligence paradox". One of the hallmarks of this paradox is of course the rising incidence in obesity, diabetes and the metabolic syndrome. This leads to the conclusion that wherever life evolves, here on earth or in another part of the galaxy, the "intelligence paradox" would be the inevitable side-effect of the evolution of intelligence. ET may not need to just "phone home" but may also need to "phone the local gym". This suggests another possible reason to explain Fermi's paradox; Enrico Fermi, the famous physicist, suggested in the 1950s that if extra-terrestrial intelligence was so prevalent, which was a common belief at the time, then where was it? Our suggestion is that if advanced life has got going elsewhere in our galaxy, it can't afford to explore the galaxy because it has to pay its healthcare costs.
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Affiliation(s)
- Alistair V W Nunn
- School of Pharmacy, University of Reading, Whiteknights, Reading, Berks RG6 6AP, UK
| | - Geoffrey W Guy
- GW pharmaceuticals, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Jimmy D Bell
- Metabolic and Molecular Imaging Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, London W12 0NN, UK
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246
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ATP-dependent Lon protease controls tumor bioenergetics by reprogramming mitochondrial activity. Cell Rep 2014; 8:542-56. [PMID: 25017063 DOI: 10.1016/j.celrep.2014.06.018] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 03/19/2014] [Accepted: 06/12/2014] [Indexed: 12/22/2022] Open
Abstract
We generated mice deficient in Lon protease (LONP1), a major enzyme of the mitochondrial quality control machinery. Homozygous deletion of Lonp1 causes early embryonic lethality, whereas its haploinsufficiency protects against colorectal and skin tumors. Furthermore, LONP1 knockdown inhibits cellular proliferation and tumor and metastasis formation, whereas its overexpression increases tumorigenesis. Clinical studies indicate that high levels of LONP1 are a poor prognosis marker in human colorectal cancer and melanoma. Additionally, functional analyses show that LONP1 plays a key role in metabolic reprogramming by remodeling OXPHOS complexes and protecting against senescence. Our findings demonstrate the relevance of LONP1 for cellular and organismal viability and identify this protease as a central regulator of mitochondrial activity in oncogenesis.
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247
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Mottis A, Jovaisaite V, Auwerx J. The mitochondrial unfolded protein response in mammalian physiology. Mamm Genome 2014; 25:424-33. [PMID: 24898297 DOI: 10.1007/s00335-014-9525-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 05/06/2014] [Indexed: 12/27/2022]
Abstract
Mitochondria, the main site of cellular energy harvesting, are derived from proteobacteria that evolved within our cells in endosymbiosis. Mitochondria retained vestiges of their proteobacterial genome, the circular mitochondrial DNA, which encodes 13 subunits of the oxidative phosphorylation multiprotein complexes in the electron transport chain (ETC), while the remaining ~80 ETC components are encoded in the nuclear DNA (nDNA). A further ~1,400 proteins, which are essential for mitochondrial function are also encoded in nDNA. Thus, a majority of mitochondrial proteins are translated in the cytoplasm, then imported, processed, and assembled in the mitochondria. An intricate protein quality control (PQC) network, constituted of chaperones and proteases that refold or degrade defective proteins, maintains mitochondrial proteostasis and ensures the cell and organism health. The mitochondrial unfolded protein response is a relatively recently discovered PQC pathway, which senses the proteostatic disturbances specifically in the mitochondria and resolves the stress by retrograde signaling to the nucleus and consequent transcriptional activation of protective genes. This PQC system does not only transiently resolve the local stress but also can have long-lasting effects on whole body metabolism, fitness, and longevity. A delicate tuning of its activation levels might constitute a treatment of various diseases, such as metabolic diseases, cancer, and neurodegenerative disorders.
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Affiliation(s)
- Adrienne Mottis
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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248
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da Silva AF, Mariotti FR, Máximo V, Campello S. Mitochondria dynamism: of shape, transport and cell migration. Cell Mol Life Sci 2014; 71:2313-24. [PMID: 24442478 PMCID: PMC11113703 DOI: 10.1007/s00018-014-1557-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/06/2013] [Accepted: 01/02/2014] [Indexed: 10/25/2022]
Abstract
Mitochondria are highly dynamic and functionally versatile organelles that continuously fragment and fuse in response to different physiological needs of the cell. The list of proteins that strictly regulate the morphology of these organelles is constantly growing, adding new players every day and new pieces to the comprehension and elucidation of this complex machinery. The structural complexity of mitochondria is only paralled by their functional versatility. Indeed, changes in mitochondria shape play critical roles in vertebrate development programmed cell death and in various processes of normal cell physiology, such as calcium signaling, reactive oxygen species production, and lifespan. Here, we present the latest findings on the regulation of mitochondrial dynamics and some of their physiological roles, focusing on cell migration. In cells where migration represents a crucial function in their physiology, such as T and tumoral metastatic cells, mitochondria need to be fragmented and recruited to specific subcellular regions to make movement possible. In depth analysis of this role of mitochondrial dynamics should help in identifying potential targeted therapy against cancer or in improving the immune system's efficiency.
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Affiliation(s)
- André Ferreira da Silva
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4200 Porto, Portugal
- Department of Pathology and Oncology, Medical Faculty of the University of Porto, 4200 Porto, Portugal
| | - Francesca Romana Mariotti
- Laboratory of Mitochondrial Dynamics in Neuropathology, Department of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Valdemar Máximo
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4200 Porto, Portugal
- Department of Pathology and Oncology, Medical Faculty of the University of Porto, 4200 Porto, Portugal
| | - Silvia Campello
- Laboratory of Mitochondrial Dynamics in Neuropathology, Department of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
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249
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Chen YC, Umanah GKE, Dephoure N, Andrabi SA, Gygi SP, Dawson TM, Dawson VL, Rutter J. Msp1/ATAD1 maintains mitochondrial function by facilitating the degradation of mislocalized tail-anchored proteins. EMBO J 2014; 33:1548-64. [PMID: 24843043 DOI: 10.15252/embj.201487943] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The majority of ER-targeted tail-anchored (TA) proteins are inserted into membranes by the Guided Entry of Tail-anchored protein (GET) system. Disruption of this system causes a subset of TA proteins to mislocalize to mitochondria. We show that the AAA+ ATPase Msp1 limits the accumulation of mislocalized TA proteins on mitochondria. Deletion of MSP1 causes the Pex15 and Gos1 TA proteins to accumulate on mitochondria when the GET system is impaired. Likely as a result of failing to extract mislocalized TA proteins, yeast with combined mutation of the MSP1 gene and the GET system exhibit strong synergistic growth defects and severe mitochondrial damage, including loss of mitochondrial DNA and protein and aberrant mitochondrial morphology. Like yeast Msp1, human ATAD1 limits the mitochondrial mislocalization of PEX26 and GOS28, orthologs of Pex15 and Gos1, respectively. GOS28 protein level is also increased in ATAD1(-/-) mouse tissues. Therefore, we propose that yeast Msp1 and mammalian ATAD1 are conserved members of the mitochondrial protein quality control system that might promote the extraction and degradation of mislocalized TA proteins to maintain mitochondrial integrity.
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Affiliation(s)
- Yu-Chan Chen
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City UT, USA
| | - George K E Umanah
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Noah Dephoure
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Shaida A Andrabi
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Ted M Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA Departments of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Valina L Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jared Rutter
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City UT, USA
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250
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Mitochondrial hyperpolarization during chronic complex I inhibition is sustained by low activity of complex II, III, IV and V. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1247-56. [PMID: 24769419 DOI: 10.1016/j.bbabio.2014.04.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 04/11/2014] [Accepted: 04/18/2014] [Indexed: 02/01/2023]
Abstract
The mitochondrial oxidative phosphorylation (OXPHOS) system consists of four electron transport chain (ETC) complexes (CI-CIV) and the FoF1-ATP synthase (CV), which sustain ATP generation via chemiosmotic coupling. The latter requires an inward-directed proton-motive force (PMF) across the mitochondrial inner membrane (MIM) consisting of a proton (ΔpH) and electrical charge (Δψ) gradient. CI actively participates in sustaining these gradients via trans-MIM proton pumping. Enigmatically, at the cellular level genetic or inhibitor-induced CI dysfunction has been associated with Δψ depolarization or hyperpolarization. The cellular mechanism of the latter is still incompletely understood. Here we demonstrate that chronic (24h) CI inhibition in HEK293 cells induces a proton-based Δψ hyperpolarization in HEK293 cells without triggering reverse-mode action of CV or the adenine nucleotide translocase (ANT). Hyperpolarization was associated with low levels of CII-driven O2 consumption and prevented by co-inhibition of CII, CIII or CIV activity. In contrast, chronic CIII inhibition triggered CV reverse-mode action and induced Δψ depolarization. CI- and CIII-inhibition similarly reduced free matrix ATP levels and increased the cell's dependence on extracellular glucose to maintain cytosolic free ATP. Our findings support a model in which Δψ hyperpolarization in CI-inhibited cells results from low activity of CII, CIII and CIV, combined with reduced forward action of CV and ANT.
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