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Zaninello M, Schlegel T, Nolte H, Pirzada M, Savino E, Barth E, Klein I, Wüstenberg H, Uddin T, Wolff L, Wirth B, Lehmann HC, Cioni JM, Langer T, Rugarli EI. CLUH maintains functional mitochondria and translation in motoneuronal axons and prevents peripheral neuropathy. SCIENCE ADVANCES 2024; 10:eadn2050. [PMID: 38809982 PMCID: PMC11135423 DOI: 10.1126/sciadv.adn2050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Accepted: 04/24/2024] [Indexed: 05/31/2024]
Abstract
Transporting and translating mRNAs in axons is crucial for neuronal viability. Local synthesis of nuclear-encoded mitochondrial proteins protects long-lived axonal mitochondria from damage; however, the regulatory factors involved are largely unknown. We show that CLUH, which binds mRNAs encoding mitochondrial proteins, prevents peripheral neuropathy and motor deficits in the mouse. CLUH is enriched in the growth cone of developing spinal motoneurons and is required for their growth. The lack of CLUH affects the abundance of target mRNAs and the corresponding mitochondrial proteins more prominently in axons, leading to ATP deficits in the growth cone. CLUH interacts with ribosomal subunits, translation initiation, and ribosome recycling components and preserves axonal translation. Overexpression of the ribosome recycling factor ABCE1 rescues the mRNA and translation defects, as well as the growth cone size, in CLUH-deficient motoneurons. Thus, we demonstrate a role for CLUH in mitochondrial quality control and translational regulation in axons, which is essential for their development and long-term integrity and function.
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Affiliation(s)
- Marta Zaninello
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Tim Schlegel
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Hendrik Nolte
- Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
| | - Mujeeb Pirzada
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Elisa Savino
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Esther Barth
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Ines Klein
- Department of Neurology, University of Cologne, Cologne 50931, Germany
| | - Hauke Wüstenberg
- Department of Neurology, University of Cologne, Cologne 50931, Germany
| | - Tesmin Uddin
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
| | - Lisa Wolff
- Institute of Human Genetics, University of Cologne, Cologne 50931, Germany
| | - Brunhilde Wirth
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Institute of Human Genetics, University of Cologne, Cologne 50931, Germany
- Center for Molecular Medicine (CMMC), University of Cologne, Cologne 50931, Germany
- Center for Rare Diseases Cologne (CESEK), University Hospital of Cologne, Cologne 50937, Germany
| | - Helmar C. Lehmann
- Department of Neurology, University of Cologne, Cologne 50931, Germany
| | - Jean-Michel Cioni
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Thomas Langer
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
- Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
| | - Elena I. Rugarli
- Institute for Genetics, University of Cologne, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne 50931, Germany
- Center for Molecular Medicine (CMMC), University of Cologne, Cologne 50931, Germany
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2
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Smith G, Sweeney ST, O’Kane CJ, Prokop A. How neurons maintain their axons long-term: an integrated view of axon biology and pathology. Front Neurosci 2023; 17:1236815. [PMID: 37564364 PMCID: PMC10410161 DOI: 10.3389/fnins.2023.1236815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 07/06/2023] [Indexed: 08/12/2023] Open
Abstract
Axons are processes of neurons, up to a metre long, that form the essential biological cables wiring nervous systems. They must survive, often far away from their cell bodies and up to a century in humans. This requires self-sufficient cell biology including structural proteins, organelles, and membrane trafficking, metabolic, signalling, translational, chaperone, and degradation machinery-all maintaining the homeostasis of energy, lipids, proteins, and signalling networks including reactive oxygen species and calcium. Axon maintenance also involves specialised cytoskeleton including the cortical actin-spectrin corset, and bundles of microtubules that provide the highways for motor-driven transport of components and organelles for virtually all the above-mentioned processes. Here, we aim to provide a conceptual overview of key aspects of axon biology and physiology, and the homeostatic networks they form. This homeostasis can be derailed, causing axonopathies through processes of ageing, trauma, poisoning, inflammation or genetic mutations. To illustrate which malfunctions of organelles or cell biological processes can lead to axonopathies, we focus on axonopathy-linked subcellular defects caused by genetic mutations. Based on these descriptions and backed up by our comprehensive data mining of genes linked to neural disorders, we describe the 'dependency cycle of local axon homeostasis' as an integrative model to explain why very different causes can trigger very similar axonopathies, providing new ideas that can drive the quest for strategies able to battle these devastating diseases.
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Affiliation(s)
- Gaynor Smith
- Cardiff University, School of Medicine, College of Biomedical and Life Sciences, Cardiff, United Kingdom
| | - Sean T. Sweeney
- Department of Biology, University of York and York Biomedical Research Institute, York, United Kingdom
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Andreas Prokop
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, The University of Manchester, Manchester, United Kingdom
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Ahmad F, Ramamorthy S, Areeshi MY, Ashraf GM, Haque S. Isolated Mitochondrial Preparations and In organello Assays: A Powerful and Relevant Ex vivo Tool for Assessment of Brain (Patho)physiology. Curr Neuropharmacol 2023; 21:1433-1449. [PMID: 36872352 PMCID: PMC10324330 DOI: 10.2174/1570159x21666230303123555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 10/30/2022] [Accepted: 12/29/2022] [Indexed: 03/07/2023] Open
Abstract
Mitochondria regulate multiple aspects of neuronal development, physiology, plasticity, and pathology through their regulatory roles in bioenergetic, calcium, redox, and cell survival/death signalling. While several reviews have addressed these different aspects, a comprehensive discussion focussing on the relevance of isolated brain mitochondria and their utilities in neuroscience research has been lacking. This is relevant because the employment of isolated mitochondria rather than their in situ functional evaluation, offers definitive evidence of organelle-specificity, negating the interference from extra mitochondrial cellular factors/signals. This mini-review was designed primarily to explore the commonly employed in organello analytical assays for the assessment of mitochondrial physiology and its dysfunction, with a particular focus on neuroscience research. The authors briefly discuss the methodologies for biochemical isolation of mitochondria, their quality assessment, and cryopreservation. Further, the review attempts to accumulate the key biochemical protocols for in organello assessment of a multitude of mitochondrial functions critical for neurophysiology, including assays for bioenergetic activity, calcium and redox homeostasis, and mitochondrial protein translation. The purpose of this review is not to examine each and every method or study related to the functional assessment of isolated brain mitochondria, but rather to assemble the commonly used protocols of in organello mitochondrial research in a single publication. The hope is that this review will provide a suitable platform aiding neuroscientists to choose and apply the required protocols and tools to address their particular mechanistic, diagnostic, or therapeutic question dealing within the confines of the research area of mitochondrial patho-physiology in the neuronal perspective.
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Affiliation(s)
- Faraz Ahmad
- Department of Biotechnology, School of Bio Sciences and Technology (SBST), Vellore Institute of Technology, Vellore, 632014, India
| | - Siva Ramamorthy
- Department of Biotechnology, School of Bio Sciences and Technology (SBST), Vellore Institute of Technology, Vellore, 632014, India
| | - Mohammed Y. Areeshi
- Medical Laboratory Technology Department, College of Applied Medical Sciences, Jazan University, Jazan, 45142, Saudi Arabia
- Research and Scientific Studies Unit, College of Nursing and Allied Health Sciences, Jazan University, Jazan, 45142, Saudi Arabia
| | - Ghulam Md. Ashraf
- Department of Medical Laboratory Sciences, College of Health Sciences, and Sharjah Institute for Medical Research, University of Sharjah, Sharjah, 27272, United Arab Emirates
| | - Shafiul Haque
- Research and Scientific Studies Unit, College of Nursing and Allied Health Sciences, Jazan University, Jazan, 45142, Saudi Arabia
- Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Beirut, Lebanon
- Centre of Medical and Bio-Allied Health Sciences Research, Ajman University, Ajman, United Arab Emirates
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4
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Hewitt VL, Miller-Fleming L, Twyning MJ, Andreazza S, Mattedi F, Prudent J, Polleux F, Vagnoni A, Whitworth AJ. Decreasing pdzd8-mediated mito-ER contacts improves organismal fitness and mitigates Aβ 42 toxicity. Life Sci Alliance 2022; 5:5/11/e202201531. [PMID: 35831024 PMCID: PMC9279675 DOI: 10.26508/lsa.202201531] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/01/2022] [Accepted: 07/01/2022] [Indexed: 02/02/2023] Open
Abstract
Mitochondria-ER contact sites (MERCs) orchestrate many important cellular functions including regulating mitochondrial quality control through mitophagy and mediating mitochondrial calcium uptake. Here, we identify and functionally characterize the Drosophila ortholog of the recently identified mammalian MERC protein, Pdzd8. We find that reducing pdzd8-mediated MERCs in neurons slows age-associated decline in locomotor activity and increases lifespan in Drosophila. The protective effects of pdzd8 knockdown in neurons correlate with an increase in mitophagy, suggesting that increased mitochondrial turnover may support healthy aging of neurons. In contrast, increasing MERCs by expressing a constitutive, synthetic ER-mitochondria tether disrupts mitochondrial transport and synapse formation, accelerates age-related decline in locomotion, and reduces lifespan. Although depletion of pdzd8 prolongs the survival of flies fed with mitochondrial toxins, it is also sufficient to rescue locomotor defects of a fly model of Alzheimer's disease expressing Amyloid β42 (Aβ42). Together, our results provide the first in vivo evidence that MERCs mediated by the tethering protein pdzd8 play a critical role in the regulation of mitochondrial quality control and neuronal homeostasis.
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Affiliation(s)
- Victoria L Hewitt
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
| | - Leonor Miller-Fleming
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Madeleine J Twyning
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Simonetta Andreazza
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Francesca Mattedi
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, IoPPN, King's College London, London, UK
| | - Julien Prudent
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Franck Polleux
- Department of Neuroscience, Columbia University Medical Center, New York, NY, USA
- Mortimer B Zuckerman Mind Brain Behavior Institute, New York, NY, USA
- Kavli Institute for Brain Sciences, Columbia University Medical Center, New York, NY, USA
| | - Alessio Vagnoni
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, IoPPN, King's College London, London, UK
| | - Alexander J Whitworth
- Medical Research Council, Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
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5
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Hees JT, Harbauer AB. Metabolic Regulation of Mitochondrial Protein Biogenesis from a Neuronal Perspective. Biomolecules 2022; 12:1595. [PMID: 36358945 PMCID: PMC9687362 DOI: 10.3390/biom12111595] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 09/29/2023] Open
Abstract
Neurons critically depend on mitochondria for ATP production and Ca2+ buffering. They are highly compartmentalized cells and therefore a finely tuned mitochondrial network constantly adapting to the local requirements is necessary. For neuronal maintenance, old or damaged mitochondria need to be degraded, while the functional mitochondrial pool needs to be replenished with freshly synthesized components. Mitochondrial biogenesis is known to be primarily regulated via the PGC-1α-NRF1/2-TFAM pathway at the transcriptional level. However, while transcriptional regulation of mitochondrial genes can change the global mitochondrial content in neurons, it does not explain how a morphologically complex cell such as a neuron adapts to local differences in mitochondrial demand. In this review, we discuss regulatory mechanisms controlling mitochondrial biogenesis thereby making a case for differential regulation at the transcriptional and translational level. In neurons, additional regulation can occur due to the axonal localization of mRNAs encoding mitochondrial proteins. Hitchhiking of mRNAs on organelles including mitochondria as well as contact site formation between mitochondria and endolysosomes are required for local mitochondrial biogenesis in axons linking defects in any of these organelles to the mitochondrial dysfunction seen in various neurological disorders.
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Affiliation(s)
- Jara Tabitha Hees
- TUM Medical Graduate Center, Technical University of Munich, 81675 Munich, Germany
- Max Planck Institute for Biological Intelligence, in Foundation, 82152 Planegg-Martinsried, Germany
| | - Angelika Bettina Harbauer
- Max Planck Institute for Biological Intelligence, in Foundation, 82152 Planegg-Martinsried, Germany
- Institute of Neuronal Cell Biology, Technical University of Munich, 80802 Munich, Germany
- Munich Cluster for Systems Neurology, 81377 Munich, Germany
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6
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Harbauer AB, Schneider A, Wohlleber D. Analysis of Mitochondria by Single-Organelle Resolution. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2022; 15:1-16. [PMID: 35303775 DOI: 10.1146/annurev-anchem-061020-111722] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cellular organelles are highly specialized compartments with distinct functions. With the increasing resolution of detection methods, it is becoming clearer that same organelles may have different functions or properties not only within different cell populations of a tissue but also within the same cell. Dysfunction or altered function affects the organelle itself and may also lead to malignancies or undesirable cell death. To understand cellular function or dysfunction, it is therefore necessary to analyze cellular components at the single-organelle level. Here, we review the recent advances in analyzing cellular function at single-organelle resolution using high-parameter flow cytometry or multicolor confocal microscopy. We focus on the analysis of mitochondria, as they are organelles at the crossroads of various cellular signaling pathways and functions. However, most of the applied methods/technologies are transferable to any other organelle, such as the endoplasmic reticulum, lysosomes, or peroxisomes.
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Affiliation(s)
- Angelika B Harbauer
- Max Planck Institute of Neurobiology, Martinsried, Germany;
- Institute of Neuronal Cell Biology, TUM School of Medicine, Technical University of Munich, Munich, Germany
- Munich Cluster for Systems Neurology, Munich, Germany
| | - Annika Schneider
- Institute of Molecular Immunology and Experimental Oncology, TUM School of Medicine, Technical University of Munich, Munich, Germany; ,
| | - Dirk Wohlleber
- Institute of Molecular Immunology and Experimental Oncology, TUM School of Medicine, Technical University of Munich, Munich, Germany; ,
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7
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Harbauer AB, Hees JT, Wanderoy S, Segura I, Gibbs W, Cheng Y, Ordonez M, Cai Z, Cartoni R, Ashrafi G, Wang C, Perocchi F, He Z, Schwarz TL. Neuronal mitochondria transport Pink1 mRNA via synaptojanin 2 to support local mitophagy. Neuron 2022; 110:1516-1531.e9. [PMID: 35216662 PMCID: PMC9081165 DOI: 10.1016/j.neuron.2022.01.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 06/25/2021] [Accepted: 01/28/2022] [Indexed: 01/18/2023]
Abstract
PTEN-induced kinase 1 (PINK1) is a short-lived protein required for the removal of damaged mitochondria through Parkin translocation and mitophagy. Because the short half-life of PINK1 limits its ability to be trafficked into neurites, local translation is required for this mitophagy pathway to be active far from the soma. The Pink1 transcript is associated and cotransported with neuronal mitochondria. In concert with translation, the mitochondrial outer membrane proteins synaptojanin 2 binding protein (SYNJ2BP) and synaptojanin 2 (SYNJ2) are required for tethering Pink1 mRNA to mitochondria via an RNA-binding domain in SYNJ2. This neuron-specific adaptation for the local translation of PINK1 provides distal mitochondria with a continuous supply of PINK1 for the activation of mitophagy.
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Affiliation(s)
- Angelika B Harbauer
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany; Institute of Neuronal Cell Biology, Technical University of Munich, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster of Systems Neurology, Feodor-Lynen-Straße 17, 81377 Munich, Germany.
| | - J Tabitha Hees
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Simone Wanderoy
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Inmaculada Segura
- Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany; Ludwig-Maximilians-Universität München, Department of Cellular Physiology Biomedical Center Munich - BMC, Großhaderner Str. 9, 82152 Martinsried, Germany
| | - Whitney Gibbs
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Yiming Cheng
- Munich Cluster of Systems Neurology, Feodor-Lynen-Straße 17, 81377 Munich, Germany; Institute for Diabetes and Obesity, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Munich, Germany
| | - Martha Ordonez
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Zerong Cai
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Romain Cartoni
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Ghazaleh Ashrafi
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Chen Wang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Fabiana Perocchi
- Institute of Neuronal Cell Biology, Technical University of Munich, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster of Systems Neurology, Feodor-Lynen-Straße 17, 81377 Munich, Germany; Institute for Diabetes and Obesity, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Munich, Germany
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Thomas L Schwarz
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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Murali Mahadevan H, Hashemiaghdam A, Ashrafi G, Harbauer AB. Mitochondria in Neuronal Health: From Energy Metabolism to Parkinson's Disease. Adv Biol (Weinh) 2021; 5:e2100663. [PMID: 34382382 DOI: 10.1002/adbi.202100663] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 06/30/2021] [Indexed: 01/01/2023]
Abstract
Mitochondria are the main suppliers of neuronal adenosine triphosphate and play a critical role in brain energy metabolism. Mitochondria also serve as Ca2+ sinks and anabolic factories and are therefore essential for neuronal function and survival. Dysregulation of neuronal bioenergetics is increasingly implicated in neurodegenerative disorders, particularly Parkinson's disease. This review describes the role of mitochondria in energy metabolism under resting conditions and during synaptic transmission, and presents evidence for the contribution of neuronal mitochondrial dysfunction to Parkinson's disease.
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Affiliation(s)
| | - Arsalan Hashemiaghdam
- Department of Cell Biology and Physiology, Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Ghazaleh Ashrafi
- Department of Cell Biology and Physiology, Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Angelika Bettina Harbauer
- Max-Planck-Institute for Neurobiology, 82152, Martinsried, Germany.,Technical University of Munich, Institute of Neuronal Cell Biology, 80333, Munich, Germany.,Munich Cluster for Systems Neurology, Munich, Germany
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Bahr T, Welburn K, Donnelly J, Bai Y. Emerging model systems and treatment approaches for Leber's hereditary optic neuropathy: Challenges and opportunities. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165743. [PMID: 32105823 PMCID: PMC9252426 DOI: 10.1016/j.bbadis.2020.165743] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/17/2020] [Accepted: 02/21/2020] [Indexed: 12/24/2022]
Abstract
Leber's hereditary optic neuropathy (LHON) is a mitochondrial disease mainly affecting retinal ganglion cells (RGCs). The pathogenesis of LHON remains ill-characterized due to a historic lack of effective disease models. Promising models have recently begun to emerge; however, less effective models remain popular. Many such models represent LHON using non-neuronal cells or assume that mutant mtDNA alone is sufficient to model the disease. This is problematic because context-specific factors play a significant role in LHON pathogenesis, as the mtDNA mutation itself is necessary but not sufficient to cause LHON. Effective models of LHON should be capable of demonstrating processes that distinguish healthy carrier cells from diseased cells. In light of these considerations, we review the pathophysiology of LHON as it relates to old, new and future models. We further discuss treatments for LHON and unanswered questions that might be explored using these new model systems.
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Affiliation(s)
- Tyler Bahr
- University of Texas Health Science Center at San Antonio 7703 Floyd Curl Drive San Antonio, Texas 78229. First Author
| | - Kyle Welburn
- University of the Incarnate Word School of Medicine 7615 Kennedy Hill Drive, San Antonio, Texas 78235 Contributing Author
| | - Jonathan Donnelly
- University of Texas Health Science Center at San Antonio 7703 Floyd Curl Drive San Antonio, Texas 78229. Contributing author
| | - Yidong Bai
- University of Texas Health Science Center at San Antonio 7703 Floyd Curl Drive San Antonio, Texas 78229
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10
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Anagnostou ME, Hepple RT. Mitochondrial Mechanisms of Neuromuscular Junction Degeneration with Aging. Cells 2020; 9:cells9010197. [PMID: 31941062 PMCID: PMC7016881 DOI: 10.3390/cells9010197] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle deteriorates with aging, contributing to physical frailty, poor health outcomes, and increased risk of mortality. Denervation is a major driver of changes in aging muscle. This occurs through transient denervation-reinnervation events throughout the aging process that remodel the spatial domain of motor units and alter fiber type. In advanced age, reinnervation wanes, leading to persistent denervation that accelerates muscle atrophy and impaired muscle contractility. Alterations in the muscle fibers and motoneurons are both likely involved in driving denervation through destabilization of the neuromuscular junction. In this respect, mitochondria are implicated in aging and age-related neurodegenerative disorders, and are also likely key to aging muscle changes through their direct effects in muscle fibers and through secondary effects mediated by mitochondrial impairments in motoneurons. Indeed, the large abundance of mitochondria in muscle fibers and motoneurons, that are further concentrated on both sides of the neuromuscular junction, likely renders the neuromuscular junction especially vulnerable to age-related mitochondrial dysfunction. Manifestations of mitochondrial dysfunction with aging include impaired respiratory function, elevated reactive oxygen species production, and increased susceptibility to permeability transition, contributing to reduced ATP generating capacity, oxidative damage, and apoptotic signaling, respectively. Using this framework, in this review we summarize our current knowledge, and relevant gaps, concerning the potential impact of mitochondrial impairment on the aging neuromuscular junction, and the mechanisms involved.
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Smith GA, Lin TH, Sheehan AE, Van der Goes van Naters W, Neukomm LJ, Graves HK, Bis-Brewer DM, Züchner S, Freeman MR. Glutathione S-Transferase Regulates Mitochondrial Populations in Axons through Increased Glutathione Oxidation. Neuron 2019; 103:52-65.e6. [PMID: 31101394 PMCID: PMC6616599 DOI: 10.1016/j.neuron.2019.04.017] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/13/2018] [Accepted: 04/10/2019] [Indexed: 01/14/2023]
Abstract
Mitochondria are essential in long axons to provide metabolic support and sustain neuron integrity. A healthy mitochondrial pool is maintained by biogenesis, transport, mitophagy, fission, and fusion, but how these events are regulated in axons is not well defined. Here, we show that the Drosophila glutathione S-transferase (GST) Gfzf prevents mitochondrial hyperfusion in axons. Gfzf loss altered redox balance between glutathione (GSH) and oxidized glutathione (GSSG) and initiated mitochondrial fusion through the coordinated action of Mfn and Opa1. Gfzf functioned epistatically with the thioredoxin peroxidase Jafrac1 and the thioredoxin reductase 1 TrxR-1 to regulate mitochondrial dynamics. Altering GSH:GSSG ratios in mouse primary neurons in vitro also induced hyperfusion. Mitochondrial changes caused deficits in trafficking, the metabolome, and neuronal physiology. Changes in GSH and oxidative state are associated with neurodegenerative diseases like Alzheimer's. Our demonstration that GSTs are key in vivo regulators of axonal mitochondrial length and number provides a potential mechanistic link.
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Affiliation(s)
- Gaynor A Smith
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA; UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK.
| | - Tzu-Huai Lin
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Amy E Sheehan
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | | | - Lukas J Neukomm
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne VD, Switzerland
| | - Hillary K Graves
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dana M Bis-Brewer
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Stephan Züchner
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Marc R Freeman
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
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12
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Corti O. Neuronal Mitophagy: Lessons from a Pathway Linked to Parkinson's Disease. Neurotox Res 2019; 36:292-305. [PMID: 31102068 DOI: 10.1007/s12640-019-00060-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 04/17/2019] [Accepted: 05/06/2019] [Indexed: 02/06/2023]
Abstract
Neurons are specialized cells with complex and extended architecture and high energy requirements. Energy in the form of adenosine triphosphate, produced essentially by mitochondrial respiration, is necessary to preserve neuronal morphology, maintain resting potential, fire action potentials, and ensure neurotransmission. Pools of functional mitochondria are required in all neuronal compartments, including cell body and dendrites, nodes of Ranvier, growth cones, axons, and synapses. The mechanisms by which old or damaged mitochondria are removed and replaced in neurons remain to be fully understood. Mitophagy has gained considerable interest since the discovery of familial forms of Parkinson's disease caused by dysfunction of PINK1 and Parkin, two multifunctional proteins cooperating in the regulation of this process. Over the past 10 years, the molecular mechanisms by which PINK1 and Parkin jointly promote the degradation of defective mitochondria by autophagy have been dissected. However, our understanding of the relevance of mitophagy to mitochondrial homeostasis in neurons remains poor. Insight has been recently gained thanks to the development of fluorescent reporter systems for tracking mitochondria in the acidic compartment of the lysosome. Using these tools, mitophagy events have been visualized in primary neurons in culture and in vivo, under basal conditions and in response to toxic insults. Despite these advances, whether PINK1 and Parkin play a major role in promoting neuronal mitophagy under physiological conditions in adult animals and during aging remains a matter of debate. Future studies will have to clarify in how far dysfunction of neuronal mitophagy is central to the pathophysiology of Parkinson's disease.
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Affiliation(s)
- Olga Corti
- Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France.
- Inserm, U1127, F-75013, Paris, France.
- CNRS, UMR 7225, F-75013, Paris, France.
- Sorbonne Universités, F-75013, Paris, France.
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13
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Barna J, Dimén D, Puska G, Kovács D, Csikós V, Oláh S, Udvari EB, Pál G, Dobolyi Á. Complement component 1q subcomponent binding protein in the brain of the rat. Sci Rep 2019; 9:4597. [PMID: 30872665 PMCID: PMC6418184 DOI: 10.1038/s41598-019-40788-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/19/2019] [Indexed: 12/17/2022] Open
Abstract
Complement component 1q subcomponent binding protein (C1qbp) is a multifunctional protein involved in immune response, energy homeostasis of cells as a plasma membrane receptor, and a nuclear, cytoplasmic or mitochondrial protein. Recent reports suggested its neuronal function, too, possibly in axon maintenance, synaptic function, and neuroplasticity. Therefore, we addressed to identify C1qbp in the rat brain using in situ hybridization histochemistry and immunolabelling at light and electron microscopic level. C1qbp has a topographical distribution in the brain established by the same pattern of C1qbp mRNA-expressing and protein-containing neurons with the highest abundance in the cerebral cortex, anterodorsal thalamic nucleus, hypothalamic paraventricular (PVN) and arcuate nuclei, spinal trigeminal nucleus. Double labelling of C1qbp with the neuronal marker NeuN, with the astrocyte marker S100, and the microglia marker Iba1 demonstrated the presence of C1qbp in neurons but not in glial cells in the normal brain, while C1qbp appeared in microglia following their activation induced by focal ischemic lesion. Only restricted neurons expressed C1qbp, for example, in the PVN, magnocellular neurons selectively contained C1qbp. Further double labelling by using the mitochondria marker Idh3a antibody suggested the mitochondrial localization of C1qbp in the brain, confirmed by correlated light and electron microscopy at 3 different brain regions. Post-embedding immunoelectron microscopy also suggested uneven C1qbp content of mitochondria in different brain areas but also heterogeneity within single neurons. These data suggest a specific function of C1qbp in the brain related to mitochondria, such as the regulation of local energy supply in neuronal cells.
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Affiliation(s)
- János Barna
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Diána Dimén
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary
| | - Gina Puska
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary
| | - Dávid Kovács
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary
| | - Vivien Csikós
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary
| | - Szilvia Oláh
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary
| | - Edina B Udvari
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary
| | - Gabriella Pál
- Hungarian Defence Forces Military Hospital, Budapest, Hungary
| | - Árpád Dobolyi
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest, Hungary.
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14
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Rangaraju V, Lauterbach M, Schuman EM. Spatially Stable Mitochondrial Compartments Fuel Local Translation during Plasticity. Cell 2019; 176:73-84.e15. [PMID: 30612742 DOI: 10.1016/j.cell.2018.12.013] [Citation(s) in RCA: 174] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/19/2018] [Accepted: 12/07/2018] [Indexed: 12/11/2022]
Abstract
Local translation meets protein turnover and plasticity demands at synapses, however, the location of its energy supply is unknown. We found that local translation in neurons is powered by mitochondria and not by glycolysis. Super-resolution microscopy revealed that dendritic mitochondria exist as stable compartments of single or multiple filaments. To test if these mitochondrial compartments can serve as local energy supply for synaptic translation, we stimulated individual synapses to induce morphological plasticity and visualized newly synthesized proteins. Depletion of local mitochondrial compartments abolished both the plasticity and the stimulus-induced synaptic translation. These mitochondrial compartments serve as spatially confined energy reserves, as local depletion of a mitochondrial compartment did not affect synaptic translation at remote spines. The length and stability of dendritic mitochondrial compartments and the spatial functional domain were altered by cytoskeletal disruption. These results indicate that cytoskeletally tethered local energy compartments exist in dendrites to fuel local translation during synaptic plasticity.
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Affiliation(s)
- Vidhya Rangaraju
- Max Planck Institute for Brain Research, Frankfurt 60438, Germany
| | | | - Erin M Schuman
- Max Planck Institute for Brain Research, Frankfurt 60438, Germany.
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15
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Ježek J, Cooper KF, Strich R. Reactive Oxygen Species and Mitochondrial Dynamics: The Yin and Yang of Mitochondrial Dysfunction and Cancer Progression. Antioxidants (Basel) 2018; 7:E13. [PMID: 29337889 PMCID: PMC5789323 DOI: 10.3390/antiox7010013] [Citation(s) in RCA: 284] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 01/02/2018] [Accepted: 01/09/2018] [Indexed: 12/11/2022] Open
Abstract
Mitochondria are organelles with a highly dynamic ultrastructure maintained by a delicate equilibrium between its fission and fusion rates. Understanding the factors influencing this balance is important as perturbations to mitochondrial dynamics can result in pathological states. As a terminal site of nutrient oxidation for the cell, mitochondrial powerhouses harness energy in the form of ATP in a process driven by the electron transport chain. Contemporaneously, electrons translocated within the electron transport chain undergo spontaneous side reactions with oxygen, giving rise to superoxide and a variety of other downstream reactive oxygen species (ROS). Mitochondrially-derived ROS can mediate redox signaling or, in excess, cause cell injury and even cell death. Recent evidence suggests that mitochondrial ultrastructure is tightly coupled to ROS generation depending on the physiological status of the cell. Yet, the mechanism by which changes in mitochondrial shape modulate mitochondrial function and redox homeostasis is less clear. Aberrant mitochondrial morphology may lead to enhanced ROS formation, which, in turn, may deteriorate mitochondrial health and further exacerbate oxidative stress in a self-perpetuating vicious cycle. Here, we review the latest findings on the intricate relationship between mitochondrial dynamics and ROS production, focusing mainly on its role in malignant disease.
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Affiliation(s)
- Jan Ježek
- Department of Molecular Biology, Rowan University Graduate School of Biomedical Sciences, Stratford, NJ 08084, USA.
| | - Katrina F Cooper
- Department of Molecular Biology, Rowan University Graduate School of Biomedical Sciences, Stratford, NJ 08084, USA.
| | - Randy Strich
- Department of Molecular Biology, Rowan University Graduate School of Biomedical Sciences, Stratford, NJ 08084, USA.
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