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Wodrich APK, Harris BT, Giniger E. Changes in mitochondrial distribution occur at the axon initial segment in association with neurodegeneration in Drosophila. Biol Open 2024; 13:bio060335. [PMID: 38912559 DOI: 10.1242/bio.060335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/17/2024] [Indexed: 06/25/2024] Open
Abstract
Changes in mitochondrial distribution are a feature of numerous age-related neurodegenerative diseases. In Drosophila, reducing the activity of Cdk5 causes a neurodegenerative phenotype and is known to affect several mitochondrial properties. Therefore, we investigated whether alterations of mitochondrial distribution are involved in Cdk5-associated neurodegeneration. We find that reducing Cdk5 activity does not alter the balance of mitochondrial localization to the somatodendritic versus axonal neuronal compartments of the mushroom body, the learning and memory center of the Drosophila brain. We do, however, observe changes in mitochondrial distribution at the axon initial segment (AIS), a neuronal compartment located in the proximal axon involved in neuronal polarization and action potential initiation. Specifically, we observe that mitochondria are partially excluded from the AIS in wild-type neurons, but that this exclusion is lost upon reduction of Cdk5 activity, concomitant with the shrinkage of the AIS domain that is known to occur in this condition. This mitochondrial redistribution into the AIS is not likely due to the shortening of the AIS domain itself but rather due to altered Cdk5 activity. Furthermore, mitochondrial redistribution into the AIS is unlikely to be an early driver of neurodegeneration in the context of reduced Cdk5 activity.
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Affiliation(s)
- Andrew P K Wodrich
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC 20007, USA
- College of Medicine, University of Kentucky, Lexington, KY 40506, USA
| | - Brent T Harris
- Department of Pathology, Georgetown University, Washington, DC 20007, USA
- Department of Neurology, Georgetown University, Washington, DC 20007, USA
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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2
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Wai T. Is mitochondrial morphology important for cellular physiology? Trends Endocrinol Metab 2024:S1043-2760(24)00123-1. [PMID: 38866638 DOI: 10.1016/j.tem.2024.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/07/2024] [Accepted: 05/13/2024] [Indexed: 06/14/2024]
Abstract
Mitochondria are double membrane-bound organelles the network morphology of which in cells is shaped by opposing events of fusion and fission executed by dynamin-like GTPases. Mutations in these genes can perturb the form and functions of mitochondria in cell and animal models of mitochondrial diseases. An expanding array of chemical, mechanical, and genetic stressors can converge on mitochondrial-shaping proteins and disrupt mitochondrial morphology. In recent years, studies aimed at disentangling the multiple roles of mitochondrial-shaping proteins beyond fission or fusion have provided insights into the homeostatic relevance of mitochondrial morphology. Here, I review the pleiotropy of mitochondrial fusion and fission proteins with the aim of understanding whether mitochondrial morphology is important for cell and tissue physiology.
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Affiliation(s)
- Timothy Wai
- Institut Pasteur, Mitochondrial Biology, CNRS UMR 3691, Université Paris Cité, Paris, France.
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3
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Wodrich APK, Harris BT, Giniger E. Changes in mitochondrial distribution occur at the axon initial segment in association with neurodegeneration in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580288. [PMID: 38405730 PMCID: PMC10888798 DOI: 10.1101/2024.02.14.580288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Changes in mitochondrial distribution are a feature of numerous age-related neurodegenerative diseases. In Drosophila, reducing the activity of Cdk5 causes a neurodegenerative phenotype and is known to affect several mitochondrial properties. Therefore, we investigated whether alterations of mitochondrial distribution are involved in Cdk5-associated neurodegeneration. We find that reducing Cdk5 activity does not alter the balance of mitochondrial localization to the somatodendritic vs. axonal neuronal compartments of the mushroom body, the learning and memory center of the Drosophila brain. We do, however, observe changes in mitochondrial distribution at the axon initial segment (AIS), a neuronal compartment located in the proximal axon involved in neuronal polarization and action potential initiation. Specifically, we observe that mitochondria are partially excluded from the AIS in wild-type neurons, but that this exclusion is lost upon reduction of Cdk5 activity, concomitant with the shrinkage of the AIS domain that is known to occur in this condition. This mitochondrial redistribution into the AIS is not likely due to the shortening of the AIS domain itself but rather due to altered Cdk5 activity. Furthermore, mitochondrial redistribution into the AIS is unlikely to be an early driver of neurodegeneration in the context of reduced Cdk5 activity.
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Affiliation(s)
- Andrew P. K. Wodrich
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC
- College of Medicine, University of Kentucky, Lexington, KY
| | - Brent T. Harris
- Department of Pathology, Georgetown University, Washington, DC
- Department of Neurology, Georgetown University, Washington, DC
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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4
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Nusir A, Sinclair P, Kabbani N. Mitochondrial Proteomes in Neural Cells: A Systematic Review. Biomolecules 2023; 13:1638. [PMID: 38002320 PMCID: PMC10669788 DOI: 10.3390/biom13111638] [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: 10/10/2023] [Revised: 11/07/2023] [Accepted: 11/09/2023] [Indexed: 11/26/2023] Open
Abstract
Mitochondria are ancient endosymbiotic double membrane organelles that support a wide range of eukaryotic cell functions through energy, metabolism, and cellular control. There are over 1000 known proteins that either reside within the mitochondria or are transiently associated with it. These mitochondrial proteins represent a functional subcellular protein network (mtProteome) that is encoded by mitochondrial and nuclear genomes and significantly varies between cell types and conditions. In neurons, the high metabolic demand and differential energy requirements at the synapses are met by specific modifications to the mtProteome, resulting in alterations in the expression and functional properties of the proteins involved in energy production and quality control, including fission and fusion. The composition of mtProteomes also impacts the localization of mitochondria in axons and dendrites with a growing number of neurodegenerative diseases associated with changes in mitochondrial proteins. This review summarizes the findings on the composition and properties of mtProteomes important for mitochondrial energy production, calcium and lipid signaling, and quality control in neural cells. We highlight strategies in mass spectrometry (MS) proteomic analysis of mtProteomes from cultured cells and tissue. The research into mtProteome composition and function provides opportunities in biomarker discovery and drug development for the treatment of metabolic and neurodegenerative disease.
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Affiliation(s)
- Aya Nusir
- Interdisciplinary Program in Neuroscience, School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
| | - Patricia Sinclair
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
| | - Nadine Kabbani
- Interdisciplinary Program in Neuroscience, School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
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5
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Lu D, Feng Y, Liu G, Yang Y, Ren Y, Chen Z, Sun X, Guan Y, Wang Z. Mitochondrial transport in neurons and evidence for its involvement in acute neurological disorders. Front Neurosci 2023; 17:1268883. [PMID: 37901436 PMCID: PMC10600463 DOI: 10.3389/fnins.2023.1268883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/18/2023] [Indexed: 10/31/2023] Open
Abstract
Ensuring mitochondrial quality is essential for maintaining neuronal homeostasis, and mitochondrial transport plays a vital role in mitochondrial quality control. In this review, we first provide an overview of neuronal mitochondrial transport, followed by a detailed description of the various motors and adaptors associated with the anterograde and retrograde transport of mitochondria. Subsequently, we review the modest evidence involving mitochondrial transport mechanisms that has surfaced in acute neurological disorders, including traumatic brain injury, spinal cord injury, spontaneous intracerebral hemorrhage, and ischemic stroke. An in-depth study of this area will help deepen our understanding of the mechanisms underlying the development of various acute neurological disorders and ultimately improve therapeutic options.
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Affiliation(s)
- Dengfeng Lu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Yun Feng
- Suzhou Medical College of Soochow University, Suzhou, Jiangsu, China
| | - Guangjie Liu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Yayi Yang
- Suzhou Medical College of Soochow University, Suzhou, Jiangsu, China
| | - Yubo Ren
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Zhouqing Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Xiaoou Sun
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Yixiang Guan
- Department of Neurosurgery, Hai'an People's Hospital Affiliated of Nantong University, Nantong, Jiangsu, China
| | - Zhong Wang
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
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6
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Yang S, Park JH, Lu HC. Axonal energy metabolism, and the effects in aging and neurodegenerative diseases. Mol Neurodegener 2023; 18:49. [PMID: 37475056 PMCID: PMC10357692 DOI: 10.1186/s13024-023-00634-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 06/08/2023] [Indexed: 07/22/2023] Open
Abstract
Human studies consistently identify bioenergetic maladaptations in brains upon aging and neurodegenerative disorders of aging (NDAs), such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and Amyotrophic lateral sclerosis. Glucose is the major brain fuel and glucose hypometabolism has been observed in brain regions vulnerable to aging and NDAs. Many neurodegenerative susceptible regions are in the topological central hub of the brain connectome, linked by densely interconnected long-range axons. Axons, key components of the connectome, have high metabolic needs to support neurotransmission and other essential activities. Long-range axons are particularly vulnerable to injury, neurotoxin exposure, protein stress, lysosomal dysfunction, etc. Axonopathy is often an early sign of neurodegeneration. Recent studies ascribe axonal maintenance failures to local bioenergetic dysregulation. With this review, we aim to stimulate research in exploring metabolically oriented neuroprotection strategies to enhance or normalize bioenergetics in NDA models. Here we start by summarizing evidence from human patients and animal models to reveal the correlation between glucose hypometabolism and connectomic disintegration upon aging/NDAs. To encourage mechanistic investigations on how axonal bioenergetic dysregulation occurs during aging/NDAs, we first review the current literature on axonal bioenergetics in distinct axonal subdomains: axon initial segments, myelinated axonal segments, and axonal arbors harboring pre-synaptic boutons. In each subdomain, we focus on the organization, activity-dependent regulation of the bioenergetic system, and external glial support. Second, we review the mechanisms regulating axonal nicotinamide adenine dinucleotide (NAD+) homeostasis, an essential molecule for energy metabolism processes, including NAD+ biosynthetic, recycling, and consuming pathways. Third, we highlight the innate metabolic vulnerability of the brain connectome and discuss its perturbation during aging and NDAs. As axonal bioenergetic deficits are developing into NDAs, especially in asymptomatic phase, they are likely exaggerated further by impaired NAD+ homeostasis, the high energetic cost of neural network hyperactivity, and glial pathology. Future research in interrogating the causal relationship between metabolic vulnerability, axonopathy, amyloid/tau pathology, and cognitive decline will provide fundamental knowledge for developing therapeutic interventions.
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Affiliation(s)
- Sen Yang
- The Linda and Jack Gill Center for Biomolecular Sciences, Indiana University, Bloomington, IN, 47405, USA
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA
- Program in Neuroscience, Indiana University, Bloomington, IN, 47405, USA
| | - Jung Hyun Park
- The Linda and Jack Gill Center for Biomolecular Sciences, Indiana University, Bloomington, IN, 47405, USA
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA
- Program in Neuroscience, Indiana University, Bloomington, IN, 47405, USA
| | - Hui-Chen Lu
- The Linda and Jack Gill Center for Biomolecular Sciences, Indiana University, Bloomington, IN, 47405, USA.
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA.
- Program in Neuroscience, Indiana University, Bloomington, IN, 47405, USA.
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7
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Chen M, Yan R, Luo J, Ning J, Zhou R, Ding L. The Role of PGC-1α-Mediated Mitochondrial Biogenesis in Neurons. Neurochem Res 2023:10.1007/s11064-023-03934-8. [PMID: 37097395 DOI: 10.1007/s11064-023-03934-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 03/28/2023] [Accepted: 03/31/2023] [Indexed: 04/26/2023]
Abstract
Neurons are highly dependent on mitochondrial ATP production and Ca2+ buffering. Neurons have unique compartmentalized anatomy and energy requirements, and each compartment requires continuously renewed mitochondria to maintain neuronal survival and activity. Peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) is a key factor in the regulation of mitochondrial biogenesis. It is widely accepted that mitochondria are synthesized in the cell body and transported via axons to the distal end. However, axonal mitochondrial biogenesis is necessary to maintain axonal bioenergy supply and mitochondrial density due to limitations in mitochondrial axonal transport rate and mitochondrial protein lifespan. In addition, impaired mitochondrial biogenesis leading to inadequate energy supply and neuronal damage has been observed in neurological disorders. In this review, we focus on the sites where mitochondrial biogenesis occurs in neurons and the mechanisms by which it maintains axonal mitochondrial density. Finally, we summarize several neurological disorders in which mitochondrial biogenesis is affected.
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Affiliation(s)
- Mengjie Chen
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, 100010, China
| | - Ruyu Yan
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, 100010, China
| | - Jiansheng Luo
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, 100010, China
| | - Jiaqi Ning
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, 100010, China
| | - Ruiling Zhou
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, 100010, China
| | - Lingling Ding
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, 100010, China.
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8
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Tamada H. Three-dimensional ultrastructure analysis of organelles in injured motor neuron. Anat Sci Int 2023:10.1007/s12565-023-00720-y. [PMID: 37071350 DOI: 10.1007/s12565-023-00720-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/23/2023] [Indexed: 04/19/2023]
Abstract
Morphological analysis of organelles is one of the important clues for understanding the cellular conditions and mechanisms occurring in cells. In particular, nanoscale information within crowded intracellular organelles of tissues provide more direct implications when compared to analyses of cells in culture or isolation. However, there are some difficulties in detecting individual shape using light microscopy, including super-resolution microscopy. Transmission electron microscopy (TEM), wherein the ultrastructure can be imaged at the membrane level, cannot determine the whole structure, and analyze it quantitatively. Volume EM, such as focused ion beam/scanning electron microscopy (FIB/SEM), can be a powerful tool to explore the details of three-dimensional ultrastructures even within a certain volume, and to measure several parameters from them. In this review, the advantages of FIB/SEM analysis in organelle studies are highlighted along with the introduction of mitochondrial analysis in injured motor neurons. This would aid in understanding the morphological details of mitochondria, especially those distributed in the cell bodies as well as in the axon initial segment (AIS) in mouse tissues. These regions have not been explored thus far due to the difficulties encountered in accessing their images by conditional microscopies. Some mechanisms of nerve regeneration have also been discussed with reference to the obtained findings. Finally, future perspectives on FIB/SEM are introduced. The combination of biochemical and genetic understanding of organelle structures and a nanoscale understanding of their three-dimensional distribution and morphology will help to match achievements in genomics and structural biology.
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Affiliation(s)
- Hiromi Tamada
- Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-Ku, Nagoya, Aichi, 466-8550, Japan.
- Anatomy, Graduate School of Medicines, University of Fukui, Matsuokashimoaizuki, Eiheiji-Cho, Yoshida-Gun, Fukui, 910-1193, Japan.
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9
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Horvath R, Medina J, Reilly MM, Shy ME, Zuchner S. Peripheral neuropathy in mitochondrial disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 194:99-116. [PMID: 36813324 DOI: 10.1016/b978-0-12-821751-1.00014-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Mitochondria are essential for the health and viability of both motor and sensory neurons and their axons. Processes that disrupt their normal distribution and transport along axons will likely cause peripheral neuropathies. Similarly, mutations in mtDNA or nuclear encoded genes result in neuropathies that either stand alone or are part of multisystem disorders. This chapter focuses on the more common genetic forms and characteristic clinical phenotypes of "mitochondrial" peripheral neuropathies. We also explain how these various mitochondrial abnormalities cause peripheral neuropathy. In a patient with a neuropathy either due to a mutation in a nuclear or an mtDNA gene, clinical investigations aim to characterize the neuropathy and make an accurate diagnosis. In some patients, this may be relatively straightforward, where a clinical assessment and nerve conduction studies followed by genetic testing is all that is needed. In others, multiple investigations including a muscle biopsy, CNS imaging, CSF analysis, and a wide range of metabolic and genetic tests in blood and muscle may be needed to establish diagnosis.
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Affiliation(s)
- Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, John van Geest Centre for Brain Repair, Cambridge, United Kingdom.
| | - Jessica Medina
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, United States
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10
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Yang C, Zhao X, An X, Zhang Y, Sun W, Zhang Y, Duan Y, Kang X, Sun Y, Jiang L, Lian F. Axonal transport deficits in the pathogenesis of diabetic peripheral neuropathy. Front Endocrinol (Lausanne) 2023; 14:1136796. [PMID: 37056668 PMCID: PMC10086245 DOI: 10.3389/fendo.2023.1136796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
Diabetic peripheral neuropathy (DPN) is a chronic and prevalent metabolic disease that gravely endangers human health and seriously affects the quality of life of hyperglycemic patients. More seriously, it can lead to amputation and neuropathic pain, imposing a severe financial burden on patients and the healthcare system. Even with strict glycemic control or pancreas transplantation, peripheral nerve damage is difficult to reverse. Most current treatment options for DPN can only treat the symptoms but not the underlying mechanism. Patients with long-term diabetes mellitus (DM) develop axonal transport dysfunction, which could be an important factor in causing or exacerbating DPN. This review explores the underlying mechanisms that may be related to axonal transport impairment and cytoskeletal changes caused by DM, and the relevance of the latter with the occurrence and progression of DPN, including nerve fiber loss, diminished nerve conduction velocity, and impaired nerve regeneration, and also predicts possible therapeutic strategies. Understanding the mechanisms of diabetic neuronal injury is essential to prevent the deterioration of DPN and to develop new therapeutic strategies. Timely and effective improvement of axonal transport impairment is particularly critical for the treatment of peripheral neuropathies.
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11
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Green A, Hossain T, Eckmann DM. Mitochondrial dynamics involves molecular and mechanical events in motility, fusion and fission. Front Cell Dev Biol 2022; 10:1010232. [PMID: 36340034 PMCID: PMC9626967 DOI: 10.3389/fcell.2022.1010232] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/06/2022] [Indexed: 11/13/2022] Open
Abstract
Mitochondria are cell organelles that play pivotal roles in maintaining cell survival, cellular metabolic homeostasis, and cell death. Mitochondria are highly dynamic entities which undergo fusion and fission, and have been shown to be very motile in vivo in neurons and in vitro in multiple cell lines. Fusion and fission are essential for maintaining mitochondrial homeostasis through control of morphology, content exchange, inheritance of mitochondria, maintenance of mitochondrial DNA, and removal of damaged mitochondria by autophagy. Mitochondrial motility occurs through mechanical and molecular mechanisms which translocate mitochondria to sites of high energy demand. Motility also plays an important role in intracellular signaling. Here, we review key features that mediate mitochondrial dynamics and explore methods to advance the study of mitochondrial motility as well as mitochondrial dynamics-related diseases and mitochondrial-targeted therapeutics.
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Affiliation(s)
- Adam Green
- Department of Anesthesiology, The Ohio State University, Columbus, OH, United States
| | - Tanvir Hossain
- Department of Anesthesiology, The Ohio State University, Columbus, OH, United States
| | - David M. Eckmann
- Department of Anesthesiology, The Ohio State University, Columbus, OH, United States
- Center for Medical and Engineering Innovation, The Ohio State University, Columbus, OH, United States
- *Correspondence: David M. Eckmann,
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12
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Cheng XT, Huang N, Sheng ZH. Programming axonal mitochondrial maintenance and bioenergetics in neurodegeneration and regeneration. Neuron 2022; 110:1899-1923. [PMID: 35429433 PMCID: PMC9233091 DOI: 10.1016/j.neuron.2022.03.015] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/04/2022] [Accepted: 03/10/2022] [Indexed: 12/11/2022]
Abstract
Mitochondria generate ATP essential for neuronal growth, function, and regeneration. Due to their polarized structures, neurons face exceptional challenges to deliver mitochondria to and maintain energy homeostasis throughout long axons and terminal branches where energy is in high demand. Chronic mitochondrial dysfunction accompanied by bioenergetic failure is a pathological hallmark of major neurodegenerative diseases. Brain injury triggers acute mitochondrial damage and a local energy crisis that accelerates neuron death. Thus, mitochondrial maintenance defects and axonal energy deficits emerge as central problems in neurodegenerative disorders and brain injury. Recent studies have started to uncover the intrinsic mechanisms that neurons adopt to maintain (or reprogram) axonal mitochondrial density and integrity, and their bioenergetic capacity, upon sensing energy stress. In this review, we discuss recent advances in how neurons maintain a healthy pool of axonal mitochondria, as well as potential therapeutic strategies that target bioenergetic restoration to power neuronal survival, function, and regeneration.
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Affiliation(s)
- Xiu-Tang Cheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Ning Huang
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA.
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13
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Gould SA, Adalbert R, Milde S, Coleman M. Imaging Axonal Transport in Ex Vivo Central and Peripheral Nerves. Methods Mol Biol 2022; 2431:73-93. [PMID: 35412272 DOI: 10.1007/978-1-0716-1990-2_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Neurones are highly polarized cells with extensive axonal projections that rely on transport of proteins, RNAs, and organelles in a bidirectional manner to remain healthy. This process, known as axonal transport, can be imaged in real time through epifluorescent imaging of fluorescently labeled proteins, organelles, and other cargoes. While this is most conveniently done in primary neuronal cultures, it is more physiologically relevant when carried out in the context of a developed nerve containing both axons and glia. Here we outline how to image axonal transport ex vivo in sciatic and optic nerves, and the fimbria of the fornix. These methods could be altered to image other fluorescently labeled molecules, as well as different mechanisms of intracellular transport.
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Affiliation(s)
- Stacey Anne Gould
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK
| | - Robert Adalbert
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Stefan Milde
- The ALBORADA Drug Discovery Institute, University of Cambridge, Cambridge, UK
| | - Michael Coleman
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK.
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14
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Severe Acute Motor Axonal Neuropathy associated with Influenza-A (H1N1) Infection and Prolonged Respiratory Failure - A Case Report. J Crit Care Med (Targu Mures) 2021; 7:302-307. [PMID: 34934821 PMCID: PMC8647670 DOI: 10.2478/jccm-2021-0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 07/29/2021] [Indexed: 11/20/2022] Open
Abstract
Acute Motor Axonal Neuropathy (AMAN) is an immune-mediated disorder of the peripheral nervous system, part of the spectrum of the Guillain-Barre syndrome (GBS). An infectious event most often triggers it reported a few weeks before the onset. The reported case is of a 56 years-old woman who developed acute motor axonal neuropathy three weeks after respiratory infection with influenza A virus subtype H1N1. Despite early treatment with plasmapheresis and intravenous immunoglobulins, the patient remained tetraplegic, mechanically ventilated for five months, with repetitive unsuccessful weaning trails. The probable cause was considered to be phrenic nerve palsy in the context of acute motor axonal neuropathy. This case highlights that acute motor axonal neuropathy is a severe and life-threatening form of Guillain-Barre syndrome associated with significant mortality and morbidity. Neurological and physical recovery strongly depend on the inter-professional effort in an intensive care unit and neurology professionals.
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15
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Agrawal A, Koslover EF. Optimizing mitochondrial maintenance in extended neuronal projections. PLoS Comput Biol 2021; 17:e1009073. [PMID: 34106921 PMCID: PMC8216566 DOI: 10.1371/journal.pcbi.1009073] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/21/2021] [Accepted: 05/12/2021] [Indexed: 11/18/2022] Open
Abstract
Neurons rely on localized mitochondria to fulfill spatially heterogeneous metabolic demands. Mitochondrial aging occurs on timescales shorter than the neuronal lifespan, necessitating transport of fresh material from the soma. Maintaining an optimal distribution of healthy mitochondria requires an interplay between a stationary pool localized to sites of high metabolic demand and a motile pool capable of delivering new material. Interchange between these pools can occur via transient fusion / fission events or by halting and restarting entire mitochondria. Our quantitative model of neuronal mitostasis identifies key parameters that govern steady-state mitochondrial health at discrete locations. Very infrequent exchange between stationary and motile pools optimizes this system. Exchange via transient fusion allows for robust maintenance, which can be further improved by selective recycling through mitophagy. These results provide a framework for quantifying how perturbations in organelle transport and interactions affect mitochondrial homeostasis in neurons, a key aspect underlying many neurodegenerative disorders.
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Affiliation(s)
- Anamika Agrawal
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Elena F. Koslover
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
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16
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Sciaccaluga M, Megaro A, Bellomo G, Ruffolo G, Romoli M, Palma E, Costa C. An Unbalanced Synaptic Transmission: Cause or Consequence of the Amyloid Oligomers Neurotoxicity? Int J Mol Sci 2021; 22:ijms22115991. [PMID: 34206089 PMCID: PMC8199544 DOI: 10.3390/ijms22115991] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 12/18/2022] Open
Abstract
Amyloid-β (Aβ) 1-40 and 1-42 peptides are key mediators of synaptic and cognitive dysfunction in Alzheimer's disease (AD). Whereas in AD, Aβ is found to act as a pro-epileptogenic factor even before plaque formation, amyloid pathology has been detected among patients with epilepsy with increased risk of developing AD. Among Aβ aggregated species, soluble oligomers are suggested to be responsible for most of Aβ's toxic effects. Aβ oligomers exert extracellular and intracellular toxicity through different mechanisms, including interaction with membrane receptors and the formation of ion-permeable channels in cellular membranes. These damages, linked to an unbalance between excitatory and inhibitory neurotransmission, often result in neuronal hyperexcitability and neural circuit dysfunction, which in turn increase Aβ deposition and facilitate neurodegeneration, resulting in an Aβ-driven vicious loop. In this review, we summarize the most representative literature on the effects that oligomeric Aβ induces on synaptic dysfunction and network disorganization.
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Affiliation(s)
- Miriam Sciaccaluga
- Neurology Clinic, Department of Medicine and Surgery, University of Perugia, Santa Maria della Misericordia Hospital, 06132 Perugia, Italy; (A.M.); (G.B.)
- Correspondence: (M.S.); (C.C.); Tel.: +39-0755858180 (M.S.); +39-0755784233 (C.C.)
| | - Alfredo Megaro
- Neurology Clinic, Department of Medicine and Surgery, University of Perugia, Santa Maria della Misericordia Hospital, 06132 Perugia, Italy; (A.M.); (G.B.)
| | - Giovanni Bellomo
- Neurology Clinic, Department of Medicine and Surgery, University of Perugia, Santa Maria della Misericordia Hospital, 06132 Perugia, Italy; (A.M.); (G.B.)
| | - Gabriele Ruffolo
- Department of Physiology and Pharmacology, Istituto Pasteur—Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (G.R.); (E.P.)
- IRCCS San Raffaele Pisana, 00166 Rome, Italy
| | - Michele Romoli
- Neurology Unit, Rimini “Infermi” Hospital—AUSL Romagna, 47923 Rimini, Italy;
| | - Eleonora Palma
- Department of Physiology and Pharmacology, Istituto Pasteur—Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (G.R.); (E.P.)
| | - Cinzia Costa
- Neurology Clinic, Department of Medicine and Surgery, University of Perugia, Santa Maria della Misericordia Hospital, 06132 Perugia, Italy; (A.M.); (G.B.)
- Correspondence: (M.S.); (C.C.); Tel.: +39-0755858180 (M.S.); +39-0755784233 (C.C.)
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17
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Cheng XT, Sheng ZH. Developmental regulation of microtubule-based trafficking and anchoring of axonal mitochondria in health and diseases. Dev Neurobiol 2021; 81:284-299. [PMID: 32302463 PMCID: PMC7572491 DOI: 10.1002/dneu.22748] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/09/2020] [Accepted: 04/09/2020] [Indexed: 12/20/2022]
Abstract
Mitochondria are cellular power plants that supply most of the ATP required in the brain to power neuronal growth, function, and regeneration. Given their extremely polarized structures and extended long axons, neurons face an exceptional challenge to maintain energy homeostasis in distal axons, synapses, and growth cones. Anchored mitochondria serve as local energy sources; therefore, the regulation of mitochondrial trafficking and anchoring ensures that these metabolically active areas are adequately supplied with ATP. Chronic mitochondrial dysfunction is a hallmark feature of major aging-related neurodegenerative diseases, and thus, anchored mitochondria in aging neurons need to be removed when they become dysfunctional. Investigations into the regulation of microtubule (MT)-based trafficking and anchoring of axonal mitochondria under physiological and pathological circumstances represent an important emerging area. In this short review article, we provide an updated overview of recent in vitro and in vivo studies showing (1) how mitochondria are transported and positioned in axons and synapses during neuronal developmental and maturation stages, and (2) how altered mitochondrial motility and axonal energy deficits in aging nervous systems link to neurodegeneration and regeneration in a disease or injury setting. We also highlight a major role of syntaphilin as a key MT-based regulator of axonal mitochondrial trafficking and anchoring in mature neurons.
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Affiliation(s)
- Xiu-Tang Cheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, Maryland 20892-3706, USA
| | - Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, Maryland 20892-3706, USA
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18
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High Dietary Fat Consumption Impairs Axonal Mitochondrial Function In Vivo. J Neurosci 2021; 41:4321-4334. [PMID: 33785643 DOI: 10.1523/jneurosci.1852-20.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 02/11/2021] [Accepted: 03/15/2021] [Indexed: 01/25/2023] Open
Abstract
Peripheral neuropathy (PN) is the most common complication of prediabetes and diabetes. PN causes severe morbidity for Type 2 diabetes (T2D) and prediabetes patients, including limb pain followed by numbness resulting from peripheral nerve damage. PN in T2D and prediabetes is associated with dyslipidemia and elevated circulating lipids; however, the molecular mechanisms underlying PN development in prediabetes and T2D are unknown. Peripheral nerve sensory neurons rely on axonal mitochondria to provide energy for nerve impulse conduction under homeostatic conditions. Models of dyslipidemia in vitro demonstrate mitochondrial dysfunction in sensory neurons exposed to elevated levels of exogenous fatty acids. Herein, we evaluated the effect of dyslipidemia on mitochondrial function and dynamics in sensory axons of the saphenous nerve of a male high-fat diet (HFD)-fed murine model of prediabetes to identify mitochondrial alterations that correlate with PN pathogenesis in vivo We found that the HFD decreased mitochondrial membrane potential (MMP) in axonal mitochondria and reduced the ability of sensory neurons to conduct at physiological frequencies. Unlike mitochondria in control axons, which dissipated their MMP in response to increased impulse frequency (from 1 to 50 Hz), HFD mitochondria dissipated less MMP in response to axonal energy demand, suggesting a lack of reserve capacity. The HFD also decreased sensory axonal Ca2+ levels and increased mitochondrial lengthening and expression of PGC1α, a master regulator of mitochondrial biogenesis. Together, these results suggest that mitochondrial dysfunction underlies an imbalance of axonal energy and Ca2+ levels and impairs impulse conduction within the saphenous nerve in prediabetic PN.SIGNIFICANCE STATEMENT Diabetes and prediabetes are leading causes of peripheral neuropathy (PN) worldwide. PN has no cure, but development in diabetes and prediabetes is associated with dyslipidemia, including elevated levels of saturated fatty acids. Saturated fatty acids impair mitochondrial dynamics and function in cultured neurons, indicating a role for mitochondrial dysfunction in PN progression; however, the effect of elevated circulating fatty acids on the peripheral nervous system in vivo is unknown. In this study, we identify early pathogenic events in sensory nerve axons of mice with high-fat diet-induced PN, including alterations in mitochondrial function, axonal conduction, and intra-axonal calcium, that provide important insight into potential PN mechanisms associated with prediabetes and dyslipidemia in vivo.
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19
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Duncan GJ, Simkins TJ, Emery B. Neuron-Oligodendrocyte Interactions in the Structure and Integrity of Axons. Front Cell Dev Biol 2021; 9:653101. [PMID: 33763430 PMCID: PMC7982542 DOI: 10.3389/fcell.2021.653101] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/15/2021] [Indexed: 12/12/2022] Open
Abstract
The myelination of axons by oligodendrocytes is a highly complex cell-to-cell interaction. Oligodendrocytes and axons have a reciprocal signaling relationship in which oligodendrocytes receive cues from axons that direct their myelination, and oligodendrocytes subsequently shape axonal structure and conduction. Oligodendrocytes are necessary for the maturation of excitatory domains on the axon including nodes of Ranvier, help buffer potassium, and support neuronal energy metabolism. Disruption of the oligodendrocyte-axon unit in traumatic injuries, Alzheimer's disease and demyelinating diseases such as multiple sclerosis results in axonal dysfunction and can culminate in neurodegeneration. In this review, we discuss the mechanisms by which demyelination and loss of oligodendrocytes compromise axons. We highlight the intra-axonal cascades initiated by demyelination that can result in irreversible axonal damage. Both the restoration of oligodendrocyte myelination or neuroprotective therapies targeting these intra-axonal cascades are likely to have therapeutic potential in disorders in which oligodendrocyte support of axons is disrupted.
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Affiliation(s)
- Greg J Duncan
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
| | - Tyrell J Simkins
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States.,Vollum Institute, Oregon Health & Science University, Portland, OR, United States.,Department of Neurology, VA Portland Health Care System, Portland, OR, United States
| | - Ben Emery
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
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20
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Cyrino LAR, Delwing-de Lima D, Ullmann OM, Maia TP. Concepts of Neuroinflammation and Their Relationship With Impaired Mitochondrial Functions in Bipolar Disorder. Front Behav Neurosci 2021; 15:609487. [PMID: 33732117 PMCID: PMC7959852 DOI: 10.3389/fnbeh.2021.609487] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/18/2021] [Indexed: 12/24/2022] Open
Abstract
Bipolar disorder (BD) is a chronic psychiatric disease, characterized by frequent behavioral episodes of depression and mania, and neurologically by dysregulated neurotransmission, neuroplasticity, growth factor signaling, and metabolism, as well as oxidative stress, and neuronal apoptosis, contributing to chronic neuroinflammation. These abnormalities result from complex interactions between multiple susceptibility genes and environmental factors such as stress. The neurocellular abnormalities of BD can result in gross morphological changes, such as reduced prefrontal and hippocampal volume, and circuit reorganization resulting in cognitive and emotional deficits. The term "neuroprogression" is used to denote the progressive changes from early to late stages, as BD severity and loss of treatment response correlate with the number of past episodes. In addition to circuit and cellular abnormalities, BD is associated with dysfunctional mitochondria, leading to severe metabolic disruption in high energy-demanding neurons and glia. Indeed, mitochondrial dysfunction involving electron transport chain (ETC) disruption is considered the primary cause of chronic oxidative stress in BD. The ensuing damage to membrane lipids, proteins, and DNA further perpetuates oxidative stress and neuroinflammation, creating a perpetuating pathogenic cycle. A deeper understanding of BD pathophysiology and identification of associated biomarkers of neuroinflammation are needed to facilitate early diagnosis and treatment of this debilitating disorder.
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Affiliation(s)
- Luiz Arthur Rangel Cyrino
- Programa de Pós-Graduação em Saúde e Meio Ambiente, Laboratório de Práticas Farmacêuticas of Department of Pharmacy, University of Joinville Region—UNIVILLE, Joinville, Brazil
- Department of Psychology, University of Joinville—UNIVILLE, Joinville, Brazil
- Department of Pharmacy, University of Joinville—UNIVILLE, Joinville, Brazil
| | - Daniela Delwing-de Lima
- Programa de Pós-Graduação em Saúde e Meio Ambiente, Laboratório de Práticas Farmacêuticas of Department of Pharmacy, University of Joinville Region—UNIVILLE, Joinville, Brazil
- Department of Pharmacy, University of Joinville—UNIVILLE, Joinville, Brazil
- Department of Medicine, University of Joinville—UNIVILLE, Joinville, Brazil
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21
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Choi GE, Han HJ. Glucocorticoid impairs mitochondrial quality control in neurons. Neurobiol Dis 2021; 152:105301. [PMID: 33609641 DOI: 10.1016/j.nbd.2021.105301] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/20/2021] [Accepted: 02/14/2021] [Indexed: 12/17/2022] Open
Abstract
Neurons are particularly vulnerable to mitochondrial dysfunction due to high energy demand and an inability to proliferate. Therefore, dysfunctional mitochondria cause various neuropathologies. Mitochondrial damage induces maintenance pathways to repair or eliminate damaged organelles. This mitochondrial quality control (MQC) system maintains appropriate morphology, localization, and removal/replacement of mitochondria to sustain brain homeostasis and counter progression of neurological disorders. Glucocorticoid release is an essential response to stressors for adaptation; however, it often culminates in maladaptation if neurons are exposed to chronic and severe stress. Long-term exposure to high levels of glucocorticoids induces mitochondrial dysfunction via genomic and nongenomic mechanisms. Glucocorticoids induce abnormal mitochondrial morphology and dysregulate fusion and fission. Moreover, mitochondrial trafficking is arrested by glucocorticoids and dysfunctional mitochondria are subsequently accumulated around the soma. These alterations lead to energy deficiency, particularly for synaptic transmission that requires large amounts of energy. Glucocorticoids also impair mitochondrial clearance by preventing mitophagy of damaged organelle and suppress mitochondrial biogenesis, resulting in the reduced number of healthy mitochondria. Failure to maintain MQC degrades brain function and contributes to neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Huntington's disease. However, mechanisms of glucocorticoid action on the regulation of MQC during chronic stress conditions are not well understood. The present review discusses pathways involved in the impairment of MQC and the clinical significance of high glucocorticoid blood levels for neurodegenerative diseases.
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Affiliation(s)
- Gee Euhn Choi
- Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science, BK21 Four Future Veterinary Medicine Leading Education & Research Center, Seoul National University, Seoul 08826, Republic of Korea
| | - Ho Jae Han
- Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science, BK21 Four Future Veterinary Medicine Leading Education & Research Center, Seoul National University, Seoul 08826, Republic of Korea.
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22
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S Mogre S, Brown AI, Koslover EF. Getting around the cell: physical transport in the intracellular world. Phys Biol 2020; 17:061003. [PMID: 32663814 DOI: 10.1088/1478-3975/aba5e5] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eukaryotic cells face the challenging task of transporting a variety of particles through the complex intracellular milieu in order to deliver, distribute, and mix the many components that support cell function. In this review, we explore the biological objectives and physical mechanisms of intracellular transport. Our focus is on cytoplasmic and intra-organelle transport at the whole-cell scale. We outline several key biological functions that depend on physically transporting components across the cell, including the delivery of secreted proteins, support of cell growth and repair, propagation of intracellular signals, establishment of organelle contacts, and spatial organization of metabolic gradients. We then review the three primary physical modes of transport in eukaryotic cells: diffusive motion, motor-driven transport, and advection by cytoplasmic flow. For each mechanism, we identify the main factors that determine speed and directionality. We also highlight the efficiency of each transport mode in fulfilling various key objectives of transport, such as particle mixing, directed delivery, and rapid target search. Taken together, the interplay of diffusion, molecular motors, and flows supports the intracellular transport needs that underlie a broad variety of biological phenomena.
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Affiliation(s)
- Saurabh S Mogre
- Department of Physics, University of California, San Diego, San Diego, California 92093, United States of America
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23
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Rönkkö J, Molchanova S, Revah‐Politi A, Pereira EM, Auranen M, Toppila J, Kvist J, Ludwig A, Neumann J, Bultynck G, Humblet‐Baron S, Liston A, Paetau A, Rivera C, Harms MB, Tyynismaa H, Ylikallio E. Dominant mutations in ITPR3 cause Charcot-Marie-Tooth disease. Ann Clin Transl Neurol 2020; 7:1962-1972. [PMID: 32949214 PMCID: PMC7545616 DOI: 10.1002/acn3.51190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 08/24/2020] [Accepted: 08/24/2020] [Indexed: 01/09/2023] Open
Abstract
OBJECTIVE ITPR3, encoding inositol 1,4,5-trisphosphate receptor type 3, was previously reported as a potential candidate disease gene for Charcot-Marie-Tooth neuropathy. Here, we present genetic and functional evidence that ITPR3 is a Charcot-Marie-Tooth disease gene. METHODS Whole-exome sequencing of four affected individuals in an autosomal dominant family and one individual who was the only affected individual in his family was used to identify disease-causing variants. Skin fibroblasts from two individuals of the autosomal dominant family were analyzed functionally by western blotting, quantitative reverse transcription PCR, and Ca2+ imaging. RESULTS Affected individuals in the autosomal dominant family had onset of symmetrical neuropathy with demyelinating and secondary axonal features at around age 30, showing signs of gradual progression with severe distal leg weakness and hand involvement in the proband at age 64. Exome sequencing identified a heterozygous ITPR3 p.Val615Met variant segregating with the disease. The individual who was the only affected in his family had disease onset at age 4 with demyelinating neuropathy. His condition was progressive, leading to severe muscle atrophy below knees and atrophy of proximal leg and hand muscles by age 16. Trio exome sequencing identified a de novo ITPR3 variant p.Arg2524Cys. Altered Ca2+ -transients in p.Val615Met patient fibroblasts suggested that the variant has a dominant-negative effect on inositol 1,4,5-trisphosphate receptor type 3 function. INTERPRETATION Together with two previously identified variants, our report adds further evidence that ITPR3 is a disease-causing gene for CMT and indicates altered Ca2+ homeostasis in disease pathogenesis.
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Affiliation(s)
- Julius Rönkkö
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Svetlana Molchanova
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Molecular and Integrative Biosciences Research ProgramFaculty of Bio‐ and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
| | - Anya Revah‐Politi
- Institute for Genomic MedicineColumbia University Medical CenterNew YorkNew YorkUSA
- Precision Genomics LaboratoryColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Elaine M. Pereira
- Department of PediatricsColumbia University Irving Medical CenterNew YorkNew YorkUSA
| | - Mari Auranen
- Clinical NeurosciencesNeurologyUniversity of Helsinki and Helsinki University HospitalHelsinkiFinland
| | - Jussi Toppila
- Department of Clinical NeurophysiologyMedical Imaging CenterHelsinki University Central HospitalHelsinkiFinland
| | - Jouni Kvist
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Anastasia Ludwig
- Neuroscience CenterHelsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
| | - Julika Neumann
- Department of Microbiology and ImmunologyLaboratory of Adaptive ImmunityKU LeuvenLeuvenBelgium
- VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular SignalingDepartment of Cellular and Molecular Medicine & Leuven Kanker InstituutKU LeuvenLeuvenBelgium
| | | | - Adrian Liston
- Department of Microbiology and ImmunologyLaboratory of Adaptive ImmunityKU LeuvenLeuvenBelgium
- VIB‐KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- Laboratory of Lymphocyte Signalling and DevelopmentBabraham InstituteCambridgeUnited Kingdom
| | - Anders Paetau
- Department of PathologyHUSLAB and University of HelsinkiHelsinkiFinland
| | - Claudio Rivera
- Neuroscience CenterHelsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
- Institut de Neurobiologie de la Méditerranée INMED UMR901MarseilleFrance
| | | | - Henna Tyynismaa
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Neuroscience CenterHelsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
- Department of Medical and Clinical GeneticsUniversity of HelsinkiHelsinkiFinland
| | - Emil Ylikallio
- Stem Cells and Metabolism Research ProgramFaculty of MedicineUniversity of HelsinkiHelsinkiFinland
- Clinical NeurosciencesNeurologyUniversity of Helsinki and Helsinki University HospitalHelsinkiFinland
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24
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Nakamura DS, Lin YH, Khan D, Gothié JDM, de Faria O, Dixon JA, McBride HM, Antel JP, Kennedy TE. Mitochondrial dynamics and bioenergetics regulated by netrin-1 in oligodendrocytes. Glia 2020; 69:392-412. [PMID: 32910475 DOI: 10.1002/glia.23905] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 08/14/2020] [Accepted: 08/16/2020] [Indexed: 01/01/2023]
Abstract
Mitochondria are dynamic organelles that produce energy and molecular precursors that are essential for myelin synthesis. Unlike in neurons, mitochondria in oligodendrocytes increase intracellular movement in response to glutamatergic activation and are more susceptible to oxidative stress than in astrocytes or microglia. The signaling pathways that regulate these cell type-specific mitochondrial responses in oligodendrocytes are not understood. Here, we visualized mitochondria migrating through thin cytoplasmic channels crossing myelin basic protein-positive compacted membranes and localized within paranodal loop cytoplasm. We hypothesized that local extracellular enrichment of netrin-1 might regulate the recruitment and function of paranodal proteins and organelles, including mitochondria. We identified rapid recruitment of mitochondria and paranodal proteins, including neurofascin 155 (NF155) and the netrin receptor deleted in colorectal carcinoma (DCC), to sites of contact between oligodendrocytes and netrin-1-coated microbeads in vitro. We provide evidence that Src-family kinase activation and Rho-associated protein kinase (ROCK) inhibition downstream of netrin-1 induces mitochondrial elongation, hyperpolarization of the mitochondrial inner membrane, and increases glycolysis. Our findings identify a signaling mechanism in oligodendrocytes that is sufficient to locally recruit paranodal proteins and regulate the subcellular localization, morphology, and function of mitochondria.
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Affiliation(s)
- Diane S Nakamura
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Yun Hsuan Lin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Damla Khan
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Jean-David M Gothié
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Omar de Faria
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - James A Dixon
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Heidi M McBride
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Jack P Antel
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Timothy E Kennedy
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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25
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Joshi DC, Zhang CL, Babujee L, Vevea JD, August BK, Sheng ZH, Chapman ER, Gomez TM, Chiu SY. Inappropriate Intrusion of an Axonal Mitochondrial Anchor into Dendrites Causes Neurodegeneration. Cell Rep 2020; 29:685-696.e5. [PMID: 31618636 PMCID: PMC6884150 DOI: 10.1016/j.celrep.2019.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/30/2019] [Accepted: 09/05/2019] [Indexed: 01/21/2023] Open
Abstract
Syntaphilin (SNPH) is a major mitochondrial anchoring protein targeted to axons and excluded from dendrites. In this study, we provide in vivo evidence that this spatial specificity is lost in Shiverer (Shi) mice, a model for progressive multiple sclerosis (MS), resulting in inappropriate intrusion of SNPH into dendrites of cerebellar Purkinje cells with neurodegenerative consequences. Thus, reconstituting dendritic SNPH intrusion in SNPH-KO mice by viral transduction greatly sensitizes Purkinje cells to excitotoxicity when the glutamatergic climbing fibers are stimulated. Finally, we demonstrate in vitro that overexpression of SNPH in dendrites compromises neuronal viability by inducing N-methyl-D-aspartate (NMDA) excitotoxicity, reducing mitochondrial calcium uptake, and interfering with quality control of mitochondria by blocking somal mitophagy. Collectively, we propose that inappropriate immobilization of dendritic mitochondria by SNPH intrusion produces excitotoxicity and suggest that interception of dendritic SNPH intrusion is a therapeutic strategy to combat neurodegeneration.
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Affiliation(s)
- Dinesh C Joshi
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Chuan-Li Zhang
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Lavanya Babujee
- Department of Plant Pathology, College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI, USA
| | - Jason D Vevea
- Howard Hughes Medical Institute and Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Benjamin K August
- Medical School Electron Microscope Facility, University of Wisconsin, Madison, WI, USA
| | - Zu-Hang Sheng
- Synaptic Functions Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Edwin R Chapman
- Howard Hughes Medical Institute and Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Timothy M Gomez
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Shing Yan Chiu
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
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26
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Calió ML, Henriques E, Siena A, Bertoncini CRA, Gil-Mohapel J, Rosenstock TR. Mitochondrial Dysfunction, Neurogenesis, and Epigenetics: Putative Implications for Amyotrophic Lateral Sclerosis Neurodegeneration and Treatment. Front Neurosci 2020; 14:679. [PMID: 32760239 PMCID: PMC7373761 DOI: 10.3389/fnins.2020.00679] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/03/2020] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive and devastating multifactorial neurodegenerative disorder. Although the pathogenesis of ALS is still not completely understood, numerous studies suggest that mitochondrial deregulation may be implicated in its onset and progression. Interestingly, mitochondrial deregulation has also been associated with changes in neural stem cells (NSC) proliferation, differentiation, and migration. In this review, we highlight the importance of mitochondrial function for neurogenesis, and how both processes are correlated and may contribute to the pathogenesis of ALS; we have focused primarily on preclinical data from animal models of ALS, since to date no studies have evaluated this link using human samples. As there is currently no cure and no effective therapy to counteract ALS, we have also discussed how improving neurogenic function by epigenetic modulation could benefit ALS. In support of this hypothesis, changes in histone deacetylation can alter mitochondrial function, which in turn might ameliorate cellular proliferation as well as neuronal differentiation and migration. We propose that modulation of epigenetics, mitochondrial function, and neurogenesis might provide new hope for ALS patients, and studies exploring these new territories are warranted in the near future.
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Affiliation(s)
| | - Elisandra Henriques
- Department of Physiological Science, Santa Casa de São Paulo School of Medical Science, São Paulo, Brazil
| | - Amanda Siena
- Department of Physiological Science, Santa Casa de São Paulo School of Medical Science, São Paulo, Brazil
| | - Clélia Rejane Antonio Bertoncini
- CEDEME, Center of Development of Experimental Models for Medicine and Biology, Federal University of São Paulo, São Paulo, Brazil
| | - Joana Gil-Mohapel
- Division of Medical Sciences, Faculty of Medicine, University of Victoria and Island Medical Program, University of British Columbia, Victoria, BC, Canada
| | - Tatiana Rosado Rosenstock
- Department of Physiological Science, Santa Casa de São Paulo School of Medical Science, São Paulo, Brazil
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Jarjour AA, Velichkova AN, Boyd A, Lord KM, Torsney C, Henderson DJ, Ffrench-Constant C. The formation of paranodal spirals at the ends of CNS myelin sheaths requires the planar polarity protein Vangl2. Glia 2020; 68:1840-1858. [PMID: 32125730 DOI: 10.1002/glia.23809] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 02/16/2020] [Accepted: 02/19/2020] [Indexed: 12/13/2022]
Abstract
During axonal ensheathment, noncompact myelin channels formed at lateral edges of the myelinating process become arranged into tight paranodal spirals that resemble loops when cut in cross section. These adhere to the axon, concentrating voltage-dependent sodium channels at nodes of Ranvier and patterning the surrounding axon into distinct molecular domains. The signals responsible for forming and maintaining the complex structure of paranodal myelin are poorly understood. Here, we test the hypothesis that the planar cell polarity determinant Vangl2 organizes paranodal myelin. We show that Vangl2 is concentrated at paranodes and that, following conditional knockout of Vangl2 in oligodendrocytes, the paranodal spiral loosens, accompanied by disruption to the microtubule cytoskeleton and mislocalization of autotypic adhesion molecules between loops within the spiral. Adhesion of the spiral to the axon is unaffected. This results in disruptions to axonal patterning at nodes of Ranvier, paranodal axon diameter and conduction velocity. When taken together with our previous work showing that loss of the apico-basal polarity protein Scribble has the opposite phenotype-loss of axonal adhesion but no effect on loop-loop autotypic adhesion-our results identify a novel mechanism by which polarity proteins control the shape of nodes of Ranvier and regulate conduction in the CNS.
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Affiliation(s)
- Andrew A Jarjour
- MRC Centre for Regenerative Medicine and MS Society/University of Edinburgh Centre for Translational Research, Scottish Centre for Regenerative Medicine, The University of Edinburgh, Edinburgh, UK
| | - Atanaska N Velichkova
- Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Amanda Boyd
- MRC Centre for Regenerative Medicine and MS Society/University of Edinburgh Centre for Translational Research, Scottish Centre for Regenerative Medicine, The University of Edinburgh, Edinburgh, UK
| | - Kathryn M Lord
- MRC Centre for Regenerative Medicine and MS Society/University of Edinburgh Centre for Translational Research, Scottish Centre for Regenerative Medicine, The University of Edinburgh, Edinburgh, UK
| | - Carole Torsney
- Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Deborah J Henderson
- Institute of Genetic Medicine, Newcastle University, Centre for Life, Newcastle upon Tyne, UK
| | - Charles Ffrench-Constant
- MRC Centre for Regenerative Medicine and MS Society/University of Edinburgh Centre for Translational Research, Scottish Centre for Regenerative Medicine, The University of Edinburgh, Edinburgh, UK
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28
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Cardanho-Ramos C, Faria-Pereira A, Morais VA. Orchestrating mitochondria in neurons: Cytoskeleton as the conductor. Cytoskeleton (Hoboken) 2019; 77:65-75. [PMID: 31782907 PMCID: PMC7187307 DOI: 10.1002/cm.21585] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/01/2019] [Accepted: 11/05/2019] [Indexed: 12/12/2022]
Abstract
Mitochondria are crucial to support synaptic activity, particularly through ATP production and Ca2+ homeostasis. This implies that mitochondria need to be well distributed throughout the different neuronal sub-compartments. To achieve this, a tight and precise regulation of several neuronal cytoskeleton players is necessary to transport and dock mitochondria. As post-mitotic cells, neurons are highly dependent on mitochondrial quality control mechanisms and several cytoskeleton proteins have been implicated in mitophagy. Therefore, all of these processes are orchestrated by the crosstalk between mitochondria and the neuronal cytoskeleton to form a coordinated and tuned symphony.
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Affiliation(s)
- Carlos Cardanho-Ramos
- Instituto de Medicina Molecular - João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Andreia Faria-Pereira
- Instituto de Medicina Molecular - João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Vanessa Alexandra Morais
- Instituto de Medicina Molecular - João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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29
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Roads to Formation of Normal Myelin Structure and Pathological Myelin Structure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:257-264. [PMID: 31760649 DOI: 10.1007/978-981-32-9636-7_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Demyelination and axonal damage are responsible for neurological deficits in demyelinating diseases including multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system. However, the pathology of demyelination and axonal damage in MS is not fully understood. While immunologists have accumulated evidence, which is involved in many immunological events in these diseases, neuroscientists and anatomists have also investigated morphological changes of myelin in these diseases. In this chapter, a new concept of demyelination will be described.
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30
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Manganelli F, Parisi S, Nolano M, Miceli F, Tozza S, Pisciotta C, Iodice R, Provitera V, Cicatiello R, Zuchner S, Taglialatela M, Russo T, Santoro L. Insights into the pathogenesis of
ATP1A1
‐related CMT disease using patient‐specific iPSCs. J Peripher Nerv Syst 2019; 24:330-339. [DOI: 10.1111/jns.12357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 11/06/2019] [Accepted: 11/06/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Fiore Manganelli
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Silvia Parisi
- Department of Molecular Medicine and Medical BiotechnologiesUniversity of Naples “Federico II” Naples Italy
| | - Maria Nolano
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
- Department of NeurologyIstituti Clinici Scientifici Maugeri IRCCS, SpA SB Pavia Italy
| | - Francesco Miceli
- Section of Pharmacology, Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Stefano Tozza
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Chiara Pisciotta
- Rare Neurodegenerative and Neurometabolic Disease UnitFondazione IRCCS Istituto Neurologico Carlo Besta Milan Italy
| | - Rosa Iodice
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Vincenzo Provitera
- Department of NeurologyIstituti Clinici Scientifici Maugeri IRCCS, SpA SB Pavia Italy
| | - Rita Cicatiello
- Department of Molecular Medicine and Medical BiotechnologiesUniversity of Naples “Federico II” Naples Italy
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human GenomicsUniversity of Miami Miller School of Medicine Miami Florida
| | - Maurizio Taglialatela
- Section of Pharmacology, Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Tommaso Russo
- Department of Molecular Medicine and Medical BiotechnologiesUniversity of Naples “Federico II” Naples Italy
| | - Lucio Santoro
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
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31
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Mandal A, Drerup CM. Axonal Transport and Mitochondrial Function in Neurons. Front Cell Neurosci 2019; 13:373. [PMID: 31447650 PMCID: PMC6696875 DOI: 10.3389/fncel.2019.00373] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/30/2019] [Indexed: 12/31/2022] Open
Abstract
The complex and elaborate architecture of a neuron poses a great challenge to the cellular machinery which localizes proteins and organelles, such as mitochondria, to necessary locations. Proper mitochondrial localization in neurons is particularly important as this organelle provides energy and metabolites essential to form and maintain functional neural connections. Consequently, maintenance of a healthy pool of mitochondria and removal of damaged organelles are essential for neuronal homeostasis. Long distance transport of the organelle itself as well as components necessary for maintaining mitochondria in distal compartments are important for a constant supply of healthy mitochondria at the right time and place. Accordingly, many neurodegenerative diseases have been associated with mitochondrial abnormalities. Here, we review our current understanding on transport-dependent mechanisms that regulate mitochondrial replenishment. We focus on axonal transport and import of mRNAs and proteins destined for mitochondria as well as mitochondrial fusion and fission to maintain mitochondrial homeostasis in distal compartments of the neuron.
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Affiliation(s)
- Amrita Mandal
- Unit on Neuronal Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Catherine M Drerup
- Unit on Neuronal Cell Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
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32
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Knockdown of the neuronal gene Lim3 at the early stages of development affects mitochondrial function and lifespan in Drosophila. Mech Ageing Dev 2019; 181:29-41. [DOI: 10.1016/j.mad.2019.111121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 04/29/2019] [Accepted: 05/30/2019] [Indexed: 01/08/2023]
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33
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Campbell G, Licht-Mayer S, Mahad D. Targeting mitochondria to protect axons in progressive MS. Neurosci Lett 2019; 710:134258. [PMID: 31082453 DOI: 10.1016/j.neulet.2019.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 05/07/2019] [Accepted: 05/09/2019] [Indexed: 10/26/2022]
Abstract
Inflammatory demyelinating processes target the neuron, particularly axons and synapses, in multiple sclerosis (MS). There is a gathering body of evidence indicating molecular changes which converge on mitochondria within neurons in progressive forms of MS. The most reproducible changes are the increase in mitochondrial content within demyelinated axons and mitochondrial respiratory chain complex deficiency in neurons, which compromises the capacity to generate ATP. The resulting lack of ATP and the likely energy failure state and its coupling with an increase in demand for energy by the demyelinated axon, are particularly relevant to the long tracts such as corticospinal tracts with long projection axons. Recent work in our laboratory and that of our collaborators indicate the limited reflection of the mitochondrial changes within neurons in the experimental disease models. Enhancing the energy producing capacity of neurons to meet the increased energy demand of demyelinated axons is likely to be a novel neuroprotective strategy in progressive MS.
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Affiliation(s)
- Graham Campbell
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Simon Licht-Mayer
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Don Mahad
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
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34
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Anderson HE, Weir RFF. On the development of optical peripheral nerve interfaces. Neural Regen Res 2019; 14:425-436. [PMID: 30539808 PMCID: PMC6334609 DOI: 10.4103/1673-5374.245461] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 09/19/2018] [Indexed: 11/04/2022] Open
Abstract
Limb loss and spinal cord injury are two debilitating conditions that continue to grow in prevalence. Prosthetic limbs and limb reanimation present two ways of providing affected individuals with means to interact in the world. These techniques are both dependent on a robust interface with the peripheral nerve. Current methods for interfacing with the peripheral nerve tend to suffer from low specificity, high latency and insufficient robustness for a chronic implant. An optical peripheral nerve interface may solve some of these problems by decreasing invasiveness and providing single axon specificity. In order to implement such an interface three elements are required: (1) a transducer capable of translating light into a neural stimulus or translating neural activity into changes in fluorescence, (2) a means for delivering said transducer and (3) a microscope for providing the stimulus light and detecting the fluorescence change. There are continued improvements in both genetically encoded calcium and voltage indicators as well as new optogenetic actuators for stimulation. Similarly, improvements in specificity of viral vectors continue to improve expression in the axons of the peripheral nerve. Our work has recently shown that it is possible to virally transduce axons of the peripheral nerve for recording from small fibers. The improvements of these components make an optical peripheral nerve interface a rapidly approaching alternative to current methods.
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Affiliation(s)
- Hans E. Anderson
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
| | - Richard F. ff. Weir
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
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35
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Arend C, Ehrke E, Dringen R. Consequences of a Metabolic Glucose-Depletion on the Survival and the Metabolism of Cultured Rat Astrocytes. Neurochem Res 2019; 44:2288-2300. [PMID: 30788754 DOI: 10.1007/s11064-019-02752-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/08/2019] [Accepted: 02/12/2019] [Indexed: 11/29/2022]
Abstract
Brain astrocytes are considered to be highly glycolytic, but these cells also produce ATP via mitochondrial oxidative phosphorylation. To investigate how a metabolic depletion of glucose will affect the metabolism of astrocytes, we applied glucose at an initial concentration of 2 mM to cultured primary astrocytes and monitored the cell viability and various metabolic parameters during an incubation for up to 2 weeks. Already within 2 days of incubation the cells had completely consumed the applied glucose and lactate had accumulated in the medium to a concentration of around 3 mM. During the subsequent 10 days of incubation, the cell viability was not compromised while the extracellular lactate concentration declined to values of around 0.2 mM, before the cell viability was compromised. Application of known inhibitors of mitochondrial metabolism strongly accelerated glucose consumption and initial lactate production, while the lactate consumption was completely (antimycin A or 8-hydroxy efavirenz) and partially (efavirenz, metformin or tyrphostin 23) inhibited which caused rapid and delayed cell toxicity, respectively. The switch from glycolytic glucose metabolism to mitochondrial metabolism during the incubation was neither accompanied by alterations in the specific cytosolic lactate dehydrogenase activity or in the WST1 reduction capacity nor in the mitochondrial citrate synthase activity, but a cellular redistribution of mitochondria from a perinuclear to a more spread cytoplasmic localization was observed during the lactate consumption phase. These results demonstrate that cultured astrocytes survive a metabolism-induced glucose depletion very well by consuming lactate as fuel for mitochondrial ATP generation.
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Affiliation(s)
- Christian Arend
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| | - Eric Ehrke
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany.,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, P.O. Box 330440, 28334, Bremen, Germany. .,Centre for Environmental Research and Sustainable Technology, University of Bremen, Bremen, Germany.
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36
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Sui Y, Nguyen HB, Thai TQ, Ikenaka K, Ohno N. Mitochondrial Dynamics in Physiology and Pathology of Myelinated Axons. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:145-163. [PMID: 31760643 DOI: 10.1007/978-981-32-9636-7_10] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mitochondria play essential roles in neurons and abnormal functions of mitochondria have been implicated in neurological disorders including myelin diseases. Since mitochondrial functions are regulated and maintained by their dynamic behavior involving localization, transport, and fusion/fission, modulation of mitochondrial dynamics would be involved in physiology and pathology of myelinated axons. In fact, the integration of multimodal imaging in vivo and in vitro revealed that mitochondrial localization and transport are differentially regulated in nodal and internodal regions in response to the changes of metabolic demand in myelinated axons. In addition, the mitochondrial behavior in axons is modulated as adaptive responses to demyelination irrespective of the cause of myelin loss, and the behavioral modulation is partly through interactions with cytoskeletons and closely associated with the pathophysiology of demyelinating diseases. Furthermore, the behavior and functions of axonal mitochondria are modulated in congenital myelin disorders involving impaired interactions between axons and myelin-forming cells, and, together with the inflammatory environment, implicated in axonal degeneration and disease phenotypes. Further studies on the regulatory mechanisms of the mitochondrial dynamics in myelinated axons would provide deeper insights into axo-glial interactions mediated through myelin ensheathment, and effective manipulations of the dynamics may lead to novel therapeutic strategies protecting axonal and neuronal functions and survival in primary diseases of myelin.
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Affiliation(s)
- Yang Sui
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, Japan.,Departments of Anatomy and Structural Biology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan
| | - Huy Bang Nguyen
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, Japan.,Departments of Anatomy and Structural Biology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan
| | - Truc Quynh Thai
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, Japan.,Departments of Anatomy and Structural Biology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan
| | - Kazuhiro Ikenaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Nobuhiko Ohno
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, Japan. .,Department of Anatomy, Division of Histology and Cell Biology, Jichi Medical University, School of Medicine, Shimotsuke, Japan.
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37
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Agrawal A, Pekkurnaz G, Koslover EF. Spatial control of neuronal metabolism through glucose-mediated mitochondrial transport regulation. eLife 2018; 7:40986. [PMID: 30561333 PMCID: PMC6322862 DOI: 10.7554/elife.40986] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 12/17/2018] [Indexed: 01/01/2023] Open
Abstract
Eukaryotic cells modulate their metabolism by organizing metabolic components in response to varying nutrient availability and energy demands. In rat axons, mitochondria respond to glucose levels by halting active transport in high glucose regions. We employ quantitative modeling to explore physical limits on spatial organization of mitochondria and localized metabolic enhancement through regulated stopping of processive motion. We delineate the role of key parameters, including cellular glucose uptake and consumption rates, that are expected to modulate mitochondrial distribution and metabolic response in spatially varying glucose conditions. Our estimates indicate that physiological brain glucose levels fall within the limited range necessary for metabolic enhancement. Hence mitochondrial localization is shown to be a plausible regulatory mechanism for neuronal metabolic flexibility in the presence of spatially heterogeneous glucose, as may occur in long processes of projection neurons. These findings provide a framework for the control of cellular bioenergetics through organelle trafficking. Cells are equipped with power factories called mitochondria that turn nutrients into chemical energy to fuel processes in the cell. Hundreds of mitochondria move throughout the cell, shifting their positions in response to energy demands. This happens via molecular motors that pick the mitochondria up and carry them to new locations. Such movements enable the mitochondria to accumulate in parts of the cell with the greatest energy needs. Mitochondria of nerve cells or neurons have a particular challenging job, as neurons can be very long and different parts within the cells can have different energy needs. It has been shown that mitochondria stop in regions where nutrients such as sugar are most concentrated. So far, it has been unclear whether this regulated stopping helps control energy balance in neurons. Here, Agrawal et al. used a computational model of rat neurons to find out whether sugar levels are sufficient in guiding mitochondria. The results showed that the mitochondria only accumulated in high-nutrient regions when the sugar concentrations were moderate – not too low and not too high. A specific range of sugar levels was necessary to make this mechanism useful for increasing the efficiency of energy production. Such concentrations match the ones observed in healthy rat brains. When neurons are unable to meet their energy demands, they stop working and sometimes even die. This is the case in many diseases, including diabetes, dementia, and Alzheimer’s disease. Computer models allow us to explore the complex energy regulation in detail. A better understanding of how neurons regulate their energy production and demand may help us discover how they become faulty in these diseases.
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Affiliation(s)
- Anamika Agrawal
- Department of Physics, University of California, San Diego, San Diego, United States
| | - Gulcin Pekkurnaz
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, San Diego, United States
| | - Elena F Koslover
- Department of Physics, University of California, San Diego, San Diego, United States
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38
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Local Acceleration of Neurofilament Transport at Nodes of Ranvier. J Neurosci 2018; 39:663-677. [PMID: 30541916 DOI: 10.1523/jneurosci.2272-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/24/2018] [Accepted: 10/26/2018] [Indexed: 11/21/2022] Open
Abstract
Myelinated axons are constricted at nodes of Ranvier. These constrictions are important physiologically because they increase the speed of saltatory nerve conduction, but they also represent potential bottlenecks for the movement of axonally transported cargoes. One type of cargo are neurofilaments, which are abundant space-filling cytoskeletal polymers that function to increase axon caliber. Neurofilaments move bidirectionally along axons, alternating between rapid movements and prolonged pauses. Strikingly, axon constriction at nodes is accompanied by a reduction in neurofilament number that can be as much as 10-fold in the largest axons. To investigate how neurofilaments navigate these constrictions, we developed a transgenic mouse strain that expresses a photoactivatable fluorescent neurofilament protein in neurons. We used the pulse-escape fluorescence photoactivation technique to analyze neurofilament transport in mature myelinated axons of tibial nerves from male and female mice of this strain ex vivo Fluorescent neurofilaments departed the activated region more rapidly in nodes than in flanking internodes, indicating that neurofilament transport is faster in nodes. By computational modeling, we showed that this nodal acceleration can be explained largely by a local increase in the duty cycle of neurofilament transport (i.e., the proportion of the time that the neurofilaments spend moving). We propose that this transient acceleration functions to maintain a constant neurofilament flux across nodal constrictions, much as the current increases where a river narrows its banks. In this way, neurofilaments are prevented from piling up in the flanking internodes, ensuring a stable neurofilament distribution and uniform axonal morphology across these physiologically important axonal domains.SIGNIFICANCE STATEMENT Myelinated axons are constricted at nodes of Ranvier, resulting in a marked local decrease in neurofilament number. These constrictions are important physiologically because they increase the efficiency of saltatory nerve conduction, but they also represent potential bottlenecks for the axonal transport of neurofilaments, which move along axons in a rapid intermittent manner. Imaging of neurofilament transport in mature myelinated axons ex vivo reveals that neurofilament polymers navigate these nodal axonal constrictions by accelerating transiently, much as the current increases where a river narrows its banks. This local acceleration is necessary to ensure a stable axonal morphology across nodal constrictions, which may explain the vulnerability of nodes of Ranvier to neurofilament accumulations in animal models of neurotoxic neuropathies and neurodegenerative diseases.
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39
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Campbell G, Mahad D. Neurodegeneration in Progressive Multiple Sclerosis. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a028985. [PMID: 29440322 DOI: 10.1101/cshperspect.a028985] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The neuron is the target of inflammatory demyelinating processes in multiple sclerosis (MS). In progressive MS, however, there is a gathering body of evidence indicating molecular changes within neuronal cell bodies. All of these molecular changes to intrinsic neurons converge on mitochondria, and the most reproduced change relates to mitochondrial respiratory chain complex deficiency. This compromise in the capacity to generate ATP in the neuronal cell body is coupled with an increased demand for energy by the demyelinated axon, which is particularly relevant to the long tracts such as corticospinal tracts with long projection axons. Recent work in our laboratory and that of our collaborators indicate limited reflection of the molecular changes that are intrinsic neurons in the experimental disease models. The mitochondrial changes within neuronal compartments are an under-recognized aspect of progressive MS and likely to offer novel targets for the improvement of neuronal function as well as neuroprotection.
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Affiliation(s)
- Graham Campbell
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, United Kingdom
| | - Don Mahad
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, United Kingdom
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40
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Toglia P, Demuro A, Mak DOD, Ullah G. Data-driven modeling of mitochondrial dysfunction in Alzheimer's disease. Cell Calcium 2018; 76:23-35. [PMID: 30248575 DOI: 10.1016/j.ceca.2018.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 09/02/2018] [Accepted: 09/03/2018] [Indexed: 02/06/2023]
Abstract
Intracellular accumulation of oligomeric forms of β amyloid (Aβ) are now believed to play a key role in the earliest phase of Alzheimer's disease (AD) as their rise correlates well with the early symptoms of the disease. Extensive evidence points to impaired neuronal Ca2+ homeostasis as a direct consequence of the intracellular Aβ oligomers. However, little is known about the downstream effects of the resulting Ca2+ rise on the many intracellular Ca2+-dependent pathways. Here we use multiscale modeling in conjunction with patch-clamp electrophysiology of single inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) and fluorescence imaging of whole-cell Ca2+ response, induced by exogenously applied intracellular Aβ42 oligomers to show that Aβ42 inflicts cytotoxicity by impairing mitochondrial function. Driven by patch-clamp experiments, we first model the kinetics of IP3R, which is then extended to build a model for the whole-cell Ca2+ signals. The whole-cell model is then fitted to fluorescence signals to quantify the overall Ca2+ release from the endoplasmic reticulum by intracellular Aβ42 oligomers through G-protein-mediated stimulation of IP3 production. The estimated IP3 concentration as a function of intracellular Aβ42 content together with the whole-cell model allows us to show that Aβ42 oligomers impair mitochondrial function through pathological Ca2+ uptake and the resulting reduced mitochondrial inner membrane potential, leading to an overall lower ATP and increased production of reactive oxygen species and H2O2. We further show that mitochondrial function can be restored by the addition of Ca2+ buffer EGTA, in accordance with the observed abrogation of Aβ42 cytotoxicity by EGTA in our live cells experiments.
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Affiliation(s)
- Patrick Toglia
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Angelo Demuro
- Department of Neurobiology and Behavior and Physiology and Biophysics, University of California, Irvine, CA 92697, USA
| | - Don-On Daniel Mak
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33620, USA.
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41
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Packialakshmi B, Zhou X. Experimental autoimmune encephalomyelitis (EAE) up-regulates the mitochondrial activity and manganese superoxide dismutase (MnSOD) in the mouse renal cortex. PLoS One 2018; 13:e0196277. [PMID: 29689072 PMCID: PMC5916489 DOI: 10.1371/journal.pone.0196277] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 04/10/2018] [Indexed: 12/19/2022] Open
Abstract
Increases of the activity of mitochondrial electron transport chain generally lead to increases of production of ATP and reactive oxygen species (ROS) as by-products. MnSOD is the first line of defense against the stress induced by mitochondrial ROS. Our previous studies demonstrated that EAE progression increased Na,K-ATPase activity in the mouse kidney cortex. Since mitochondria are the major source of ATP, our present studies were sought to determine whether EAE progression increased mitochondrial activity. We found that severe EAE increased mitochondrial complex II and IV activities without significantly affecting complex I activity with corresponding increases of ROS in the isolated mitochondria and native kidney cortex. Severe EAE augmented both cytosolic and mitochondrial MnSOD protein levels and activities and decreased the specific activity of mitochondrial MnSOD when the total mitochondrial MnSOD activity was normalized to the protein level. Using HEK293 cells as a model free of interference from immune reactions, we found that activation of Na,K-ATPase by monensin for 24 hours increased complex II activity, mitochondrial ROS and MnSOD protein abundance, and decreased the specific activity of the mitochondrial MnSOD. Inhibition of Na,K-ATPase by ouabain or catalase attenuated the effects of monensin on the mitochondrial complex II activity, ROS, MnSOD protein level and specific activity. Kockdown of MnSOD by RNAi reduced the mitochondrial ability to generate ATP. In conclusion, EAE increases mitochondrial activity possibly to meet the energy demand from increased Na,K-ATPase activity. EAE increases mitochondrial MnSOD protein abundance to compensate for the loss of the specific activity of the enzyme, thus minimizing the harmful effects of ROS.
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Affiliation(s)
- Balamurugan Packialakshmi
- Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Xiaoming Zhou
- Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- * E-mail:
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42
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Campbell G, Mahad DJ. Mitochondrial dysfunction and axon degeneration in progressive multiple sclerosis. FEBS Lett 2018; 592:1113-1121. [PMID: 29453889 DOI: 10.1002/1873-3468.13013] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 01/23/2018] [Accepted: 01/24/2018] [Indexed: 11/11/2022]
Abstract
The neuron is the target of inflammatory demyelinating processes in multiple sclerosis (MS). In progressive MS, however, there is a gathering body of evidence indicating that molecular changes converge on mitochondria within neuronal cell bodies. The most reproducible change relates to mitochondrial respiratory chain complex deficiency, which compromises the capacity of neurons to generate ATP. The resulting energy failure state is coupled with an increase in demand for energy by the demyelinated axon, being particularly relevant to the long tracts such as corticospinal tracts with long projection axons. Recent work in our laboratory and that of our collaborators indicates the limited reflection of the mitochondria changes within neurons in experimental disease models. The mitochondrial changes within neuronal compartments are likely to offer novel targets for the improvement in neuronal function in patients with progressive MS.
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Affiliation(s)
- Graham Campbell
- The Centre for Clinical Brain Science, University of Edinburgh, UK
| | - Don J Mahad
- The Centre for Clinical Brain Science, University of Edinburgh, UK
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43
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Chandra G, Shenoi RA, Anand R, Rajamma U, Mohanakumar KP. Reinforcing mitochondrial functions in aging brain: An insight into Parkinson's disease therapeutics. J Chem Neuroanat 2017; 95:29-42. [PMID: 29269015 DOI: 10.1016/j.jchemneu.2017.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 12/16/2017] [Accepted: 12/17/2017] [Indexed: 12/19/2022]
Abstract
Mitochondria, the powerhouse of the neural cells in the brain, are also the seat of certain essential gene signaling pathways that control neuronal functions. Deterioration of mitochondrial functions has been widely reported in normal aging as well as in a spectrum of age-associated neurological diseases, including Parkinson's disease (PD). Evidences accumulated in the recent past provide not only advanced information on the causes of mitochondrial bioenergetics defects and redox imbalance in PD brains, but also much insight into mitochondrial biogenesis, quality control of mitochondrial proteins, and genes, which regulate intra- and extra-mitochondrial signaling that control the general health of neural cells. The mitochondrial quality control machinery is affected in aging and especially in PD, thus affecting intraneuronal protein transport and degradation, which are primarily responsible for accumulation of misfolded proteins and mitochondrial damage in sporadic as well as familial PD. Essentially we considered in the first half of this review, mitochondria-based targets such as mitochondrial oxidative stress and mitochondrial quality control pathways in PD, relevance of mitochondrial DNA mutations, mitophagy, mitochondrial proteases, mitochondrial flux, and finally mitochondria-based therapies possible for PD. Therapeutic aspects are considered in the later half and mitochondria-targeted antioxidant therapy, mitophagy enhancers, mitochondrial biogenesis boasters, mitochondrial dynamics modulators, and gene-based therapeutic approaches are discussed. The present review is a critical assessment of this information to distinguish some exemplary mitochondrial therapeutic targets, and provides a utilitarian perception of some avenues for therapeutic designs on identified mitochondrial targets for PD, a very incapacitating disorder of the geriatric population, world over.
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Affiliation(s)
- G Chandra
- Inter University Centre for Biomedical Research & Super Speciality Hospital, Mahatma Gandhi University Campus at Thalappady, Rubber Board P.O., Kottayam, Kerala - 686009, India.
| | - R A Shenoi
- Inter University Centre for Biomedical Research & Super Speciality Hospital, Mahatma Gandhi University Campus at Thalappady, Rubber Board P.O., Kottayam, Kerala - 686009, India
| | - R Anand
- Inter University Centre for Biomedical Research & Super Speciality Hospital, Mahatma Gandhi University Campus at Thalappady, Rubber Board P.O., Kottayam, Kerala - 686009, India
| | - U Rajamma
- Inter University Centre for Biomedical Research & Super Speciality Hospital, Mahatma Gandhi University Campus at Thalappady, Rubber Board P.O., Kottayam, Kerala - 686009, India
| | - K P Mohanakumar
- Inter University Centre for Biomedical Research & Super Speciality Hospital, Mahatma Gandhi University Campus at Thalappady, Rubber Board P.O., Kottayam, Kerala - 686009, India
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44
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Misgeld T, Schwarz TL. Mitostasis in Neurons: Maintaining Mitochondria in an Extended Cellular Architecture. Neuron 2017; 96:651-666. [PMID: 29096078 DOI: 10.1016/j.neuron.2017.09.055] [Citation(s) in RCA: 309] [Impact Index Per Article: 44.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 09/25/2017] [Accepted: 09/28/2017] [Indexed: 02/06/2023]
Abstract
Neurons have more extended and complex shapes than other cells and consequently face a greater challenge in distributing and maintaining mitochondria throughout their arbors. Neurons can last a lifetime, but proteins turn over rapidly. Mitochondria, therefore, need constant rejuvenation no matter how far they are from the soma. Axonal transport of mitochondria and mitochondrial fission and fusion contribute to this rejuvenation, but local protein synthesis is also likely. Maintenance of a healthy mitochondrial population also requires the clearance of damaged proteins and organelles. This involves degradation of individual proteins, sequestration in mitochondria-derived vesicles, organelle degradation by mitophagy and macroautophagy, and in some cases transfer to glial cells. Both long-range transport and local processing are thus at work in achieving neuronal mitostasis-the maintenance of an appropriately distributed pool of healthy mitochondria for the duration of a neuron's life. Accordingly, defects in the processes that support mitostasis are significant contributors to neurodegenerative disorders.
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Affiliation(s)
- Thomas Misgeld
- Technical University of Munich, Institute of Neuronal Cell Biology, Munich, Germany; German Center for Neurodegenerative Diseases, Munich, Germany; Munich Cluster for Systems Neurology, Munich, Germany; Center of Integrated Protein Science, Munich, Germany.
| | - Thomas L Schwarz
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA; F.M. Kirby Neurobiology Center, Children's Hospital, Boston, MA, USA.
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45
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Fontaine AK, Gibson EA, Caldwell JH, Weir RF. Optical Read-out of Neural Activity in Mammalian Peripheral Axons: Calcium Signaling at Nodes of Ranvier. Sci Rep 2017; 7:4744. [PMID: 28720792 PMCID: PMC5516017 DOI: 10.1038/s41598-017-03541-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/28/2017] [Indexed: 12/11/2022] Open
Abstract
Current neural interface technologies have serious limitations for advanced prosthetic and therapeutic applications due primarily to their lack of specificity in neural communication. An optogenetic approach has the potential to provide single cell/axon resolution in a minimally invasive manner by optical interrogation of light-sensitive reporters and actuators. Given the aim of reading neural activity in the peripheral nervous system, this work has investigated an activity-dependent signaling mechanism in the peripheral nerve. We demonstrate action potential evoked calcium signals in mammalian tibial nerve axons using an in vitro mouse model with a dextran-conjugated fluorescent calcium indicator. Spatial and temporal dynamics of the signal are presented, including characterization of frequency-modulated amplitude. Pharmacological experiments implicate T-type CaV channels and sodium-calcium exchanger (NCX) as predominant mechanisms of calcium influx. This work shows the potential of using calcium-associated optical signals for neural activity read-out in peripheral nerve axons.
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Affiliation(s)
- Arjun K Fontaine
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA.
| | - Emily A Gibson
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA
| | - John H Caldwell
- Department of Cell and Developmental Biology, University of Colorado - Anschutz Medical Campus, Colorado, USA
| | - Richard F Weir
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA
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Loss O, Stephenson FA. Developmental changes in trak-mediated mitochondrial transport in neurons. Mol Cell Neurosci 2017; 80:134-147. [PMID: 28300646 PMCID: PMC5400476 DOI: 10.1016/j.mcn.2017.03.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 01/23/2017] [Accepted: 03/09/2017] [Indexed: 01/04/2023] Open
Abstract
Previous studies established that the kinesin adaptor proteins, TRAK1 and TRAK2, play an important role in mitochondrial transport in neurons. They link mitochondria to kinesin motor proteins via a TRAK acceptor protein in the mitochondrial outer membrane, the Rho GTPase, Miro. TRAKs also associate with enzyme, O-linked N-acetylglucosamine transferase (OGT), to form a quaternary, mitochondrial trafficking complex. A recent report suggested that TRAK1 preferentially controls mitochondrial transport in axons of hippocampal neurons whereas TRAK2 controls mitochondrial transport in dendrites. However, it is not clear whether the function of any of these proteins is exclusive to axons or dendrites and if their mechanisms of action are conserved between different neuronal populations and also, during maturation. Here, a comparative study was carried out into TRAK-mediated mitochondrial mobility in axons and dendrites of hippocampal and cortical neurons during maturation in vitro using a shRNA gene knockdown approach. It was found that in mature hippocampal and cortical neurons, TRAK1 predominantly mediates axonal mitochondrial transport whereas dendritic transport is mediated via TRAK2. In young, maturing neurons, TRAK1 and TRAK2 contribute similarly in mitochondrial transport in both axons and dendrites in both neuronal types. These findings demonstrate maturation regulation of mitochondrial transport which is conserved between at least two distinct neuronal subtypes. Mitochondrial transport and velocity changes during neuronal maturation. TRAK1 and TRAK2 contribute to transport in axons and dendrites of immature neurons. In mature neurons TRAK1 controls axonal mitochondrial transport. In mature neurons TRAK2 controls dendritic mitochondrial transport.
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Affiliation(s)
- Omar Loss
- School of Pharmacy University College London, 29/39 Brunswick Square, London WC1N 1AX, United Kingdom
| | - F Anne Stephenson
- School of Pharmacy University College London, 29/39 Brunswick Square, London WC1N 1AX, United Kingdom.
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Griggs RB, Yermakov LM, Susuki K. Formation and disruption of functional domains in myelinated CNS axons. Neurosci Res 2016; 116:77-87. [PMID: 27717670 DOI: 10.1016/j.neures.2016.09.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/19/2016] [Accepted: 09/23/2016] [Indexed: 12/15/2022]
Abstract
Communication in the central nervous system (CNS) occurs through initiation and propagation of action potentials at excitable domains along axons. Action potentials generated at the axon initial segment (AIS) are regenerated at nodes of Ranvier through the process of saltatory conduction. Proper formation and maintenance of the molecular structure at the AIS and nodes are required for sustaining conduction fidelity. In myelinated CNS axons, paranodal junctions between the axolemma and myelinating oligodendrocytes delineate nodes of Ranvier and regulate the distribution and localization of specialized functional elements, such as voltage-gated sodium channels and mitochondria. Disruption of excitable domains and altered distribution of functional elements in CNS axons is associated with demyelinating diseases such as multiple sclerosis, and is likely a mechanism common to other neurological disorders. This review will provide a brief overview of the molecular structure of the AIS and nodes of Ranvier, as well as the distribution of mitochondria in myelinated axons. In addition, this review highlights important structural and functional changes within myelinated CNS axons that are associated with neurological dysfunction.
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Affiliation(s)
- Ryan B Griggs
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, United States
| | - Leonid M Yermakov
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, United States
| | - Keiichiro Susuki
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, OH, United States.
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48
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Imaging of neuronal mitochondria in situ. Curr Opin Neurobiol 2016; 39:152-63. [PMID: 27454347 DOI: 10.1016/j.conb.2016.06.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/04/2016] [Accepted: 06/07/2016] [Indexed: 11/21/2022]
Abstract
Neuronal mitochondria are receiving a rapidly increasing level of attention. This is to a significant part due to the ability to visualize neuronal mitochondria in novel ways, especially in vivo. Such an approach allows studying neuronal mitochondria in an intact tissue context, during different developmental states and in various genetic backgrounds and disease conditions. Hence, in vivo imaging of mitochondria in the nervous system can reveal aspects of the 'mitochondrial life cycle' in neurons that hitherto have remained obscure or could only be inferred indirectly. In this survey of the current literature, we review the new insights that have emerged from studies using mitochondrial imaging in intact neural preparations ranging from worms to mice.
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49
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Wong VS, Langley B. Epigenetic changes following traumatic brain injury and their implications for outcome, recovery and therapy. Neurosci Lett 2016; 625:26-33. [PMID: 27155457 PMCID: PMC4915732 DOI: 10.1016/j.neulet.2016.04.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/03/2016] [Accepted: 04/05/2016] [Indexed: 12/21/2022]
Abstract
Traumatic brain injury (TBI) contributes to nearly a third of all injury-related deaths in the United States. For survivors of TBI, depending on severity, patients can be left with devastating neurological disabilities that include impaired cognition or memory, movement, sensation, or emotional function. Despite the efforts to identify novel therapeutics, the only strategy to combat TBI is risk reduction (helmets, seatbelts, removal of fall hazards, etc.). Enormous heterogeneity exists within TBI, and it depends on the severity, the location, and whether the injury was focal or diffuse. Evidence from recent studies support the involvement of epigenetic mechanisms such as DNA methylation, chromatin post-translational modification, and miRNA regulation of gene expression in the post-injured brain. In this review, we discuss studies that have assessed epigenetic changes and mechanisms following TBI, how epigenetic changes might not only be limited to the nucleus but also impact the mitochondria, and the implications of these changes with regard to TBI recovery.
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Affiliation(s)
- Victor S Wong
- Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, United States
| | - Brett Langley
- Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, United States; Department of Neurology and Neuroscience, Weill Medical College of Cornell University, 525 E. 68th Street, New York, NY 10065, United States.
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50
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Astroglial glutamate transporters coordinate excitatory signaling and brain energetics. Neurochem Int 2016; 98:56-71. [PMID: 27013346 DOI: 10.1016/j.neuint.2016.03.014] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 12/22/2022]
Abstract
In the mammalian brain, a family of sodium-dependent transporters maintains low extracellular glutamate and shapes excitatory signaling. The bulk of this activity is mediated by the astroglial glutamate transporters GLT-1 and GLAST (also called EAAT2 and EAAT1). In this review, we will discuss evidence that these transporters co-localize with, form physical (co-immunoprecipitable) interactions with, and functionally couple to various 'energy-generating' systems, including the Na(+)/K(+)-ATPase, the Na(+)/Ca(2+) exchanger, glycogen metabolizing enzymes, glycolytic enzymes, and mitochondria/mitochondrial proteins. This functional coupling is bi-directional with many of these systems both being regulated by glutamate transport and providing the 'fuel' to support glutamate uptake. Given the importance of glutamate uptake to maintaining synaptic signaling and preventing excitotoxicity, it should not be surprising that some of these systems appear to 'redundantly' support the energetic costs of glutamate uptake. Although the glutamate-glutamine cycle contributes to recycling of neurotransmitter pools of glutamate, this is an over-simplification. The ramifications of co-compartmentalization of glutamate transporters with mitochondria for glutamate metabolism are discussed. Energy consumption in the brain accounts for ∼20% of the basal metabolic rate and relies almost exclusively on glucose for the production of ATP. However, the brain does not possess substantial reserves of glucose or other fuels. To ensure adequate energetic supply, increases in neuronal activity are matched by increases in cerebral blood flow via a process known as 'neurovascular coupling'. While the mechanisms for this coupling are not completely resolved, it is generally agreed that astrocytes, with processes that extend to synapses and endfeet that surround blood vessels, mediate at least some of the signal that causes vasodilation. Several studies have shown that either genetic deletion or pharmacologic inhibition of glutamate transport impairs neurovascular coupling. Together these studies strongly suggest that glutamate transport not only coordinates excitatory signaling, but also plays a pivotal role in regulating brain energetics.
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