1
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Sabui A, Biswas M, Somvanshi PR, Kandagiri P, Gorla M, Mohammed F, Tammineni P. Decreased anterograde transport coupled with sustained retrograde transport contributes to reduced axonal mitochondrial density in tauopathy neurons. Front Mol Neurosci 2022; 15:927195. [PMID: 36245925 PMCID: PMC9561864 DOI: 10.3389/fnmol.2022.927195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
Mitochondria are essential organelle required for neuronal homeostasis. Mitochondria supply ATP and buffer calcium at synaptic terminals. However, the complex structural geometry of neurons poses a unique challenge in transporting mitochondria to synaptic terminals. Kinesin motors supply mitochondria to the axonal compartments, while cytoplasmic dynein is required for retrograde transport. Despite the importance of presynaptic mitochondria, how and whether axonal mitochondrial transport and distribution are altered in tauopathy neurons remain poorly studied. In the current study, we have shown that anterograde transport of mitochondria is reduced in P301L neurons, while there is no change in the retrograde transport. Consistently, axonal mitochondrial abundance is reduced in P301L neurons. We further studied the possible role of two opposing motor proteins on mitochondrial transport and found that mitochondrial association of kinesin is decreased significantly in P301L cells. Interestingly, fitting our experimental data into mathematical equations suggested a possible rise in dynein activity to maintain retrograde flux in P301L cells. Our data indicate that decreased kinesin-mediated transport coupled with sustained retrograde transport might reduce axonal mitochondria in tauopathy neurons, thus contributing to the synaptic deficits in Alzheimer’s disease (AD) and other tauopathies.
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Affiliation(s)
- Anusruti Sabui
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Mitali Biswas
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | | | - Preethi Kandagiri
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Madhavi Gorla
- Centre for Biotechnology, Institute of Science and Technology (IST), Jawaharlal Nehru Technological University Hyderabad, Hyderabad, India
| | - Fareed Mohammed
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Prasad Tammineni
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
- *Correspondence: Prasad Tammineni,
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2
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Kim YJ, Cho MJ, Yu WD, Kim MJ, Kim SY, Lee JH. Links of Cytoskeletal Integrity with Disease and Aging. Cells 2022; 11:cells11182896. [PMID: 36139471 DOI: 10.3390/cells11182896] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/09/2022] [Accepted: 09/10/2022] [Indexed: 11/16/2022] Open
Abstract
Aging is a complex feature and involves loss of multiple functions and nonreversible phenotypes. However, several studies suggest it is possible to protect against aging and promote rejuvenation. Aging is associated with many factors, such as telomere shortening, DNA damage, mitochondrial dysfunction, and loss of homeostasis. The integrity of the cytoskeleton is associated with several cellular functions, such as migration, proliferation, degeneration, and mitochondrial bioenergy production, and chronic disorders, including neuronal degeneration and premature aging. Cytoskeletal integrity is closely related with several functional activities of cells, such as aging, proliferation, degeneration, and mitochondrial bioenergy production. Therefore, regulation of cytoskeletal integrity may be useful to elicit antiaging effects and to treat degenerative diseases, such as dementia. The actin cytoskeleton is dynamic because its assembly and disassembly change depending on the cellular status. Aged cells exhibit loss of cytoskeletal stability and decline in functional activities linked to longevity. Several studies reported that improvement of cytoskeletal stability can recover functional activities. In particular, microtubule stabilizers can be used to treat dementia. Furthermore, studies of the quality of aged oocytes and embryos revealed a relationship between cytoskeletal integrity and mitochondrial activity. This review summarizes the links of cytoskeletal properties with aging and degenerative diseases and how cytoskeletal integrity can be modulated to elicit antiaging and therapeutic effects.
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Affiliation(s)
- Yu Jin Kim
- CHA Fertility Center Seoul Station, Jung-gu, Seoul 04637, Korea
| | - Min Jeong Cho
- CHA Fertility Center Seoul Station, Jung-gu, Seoul 04637, Korea
| | - Won Dong Yu
- Department of Biomedical Sciences, College of Life Science, CHA University, Pochen 11160, Korea
| | - Myung Joo Kim
- CHA Fertility Center Seoul Station, Jung-gu, Seoul 04637, Korea
| | - Sally Yunsun Kim
- National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Jae Ho Lee
- CHA Fertility Center Seoul Station, Jung-gu, Seoul 04637, Korea
- Department of Biomedical Sciences, College of Life Science, CHA University, Pochen 11160, Korea
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3
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Garcia G, Pinto S, Cunha M, Fernandes A, Koistinaho J, Brites D. Neuronal Dynamics and miRNA Signaling Differ between SH-SY5Y APPSwe and PSEN1 Mutant iPSC-Derived AD Models upon Modulation with miR-124 Mimic and Inhibitor. Cells 2021; 10:cells10092424. [PMID: 34572073 PMCID: PMC8465877 DOI: 10.3390/cells10092424] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 08/30/2021] [Accepted: 09/09/2021] [Indexed: 12/31/2022] Open
Abstract
Neuronal miRNA dysregulation may have a role in the pathophysiology of Alzheimer's disease (AD). miRNA(miR)-124 is largely abundant and a critical player in many neuronal functions. However, the lack of models reliably recapitulating AD pathophysiology hampers our understanding of miR-124's role in the disease. Using the classical human SH-SY5Y-APP695 Swedish neuroblastoma cells (SH-SWE) and the PSEN1 mutant iPSC-derived neurons (iNEU-PSEN), we observed a sustained upregulation of miR-124/miR-125b/miR-21, but only miR-124 was consistently shuttled into their exosomes. The miR-124 mimic reduced APP gene expression in both AD models. While miR-124 mimic in SH-SWE neurons led to neurite outgrowth, mitochondria activation and small Aβ oligomer reduction, in iNEU-PSEN cells it diminished Tau phosphorylation, whereas miR-124 inhibitor decreased dendritic spine density. In exosomes, cellular transfection with the mimic predominantly downregulated miR-125b/miR-21/miR-146a/miR-155. The miR-124 inhibitor upregulated miR-146a in the two experimental cell models, while it led to distinct miRNA signatures in cells and exosomes. In sum, though miR-124 function may be dependent on the neuronal AD model, data indicate that keeping miR-124 level strictly controlled is crucial for proper neuronal function. Moreover, the iNEU-PSEN cellular model stands out as a useful tool for AD mechanistic studies and perhaps for the development of personalized therapeutic strategies.
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Affiliation(s)
- Gonçalo Garcia
- Neuroinflammation, Signaling and Neuroregeneration Laboratory, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal; (G.G.); (S.P.); (M.C.)
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal;
| | - Sara Pinto
- Neuroinflammation, Signaling and Neuroregeneration Laboratory, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal; (G.G.); (S.P.); (M.C.)
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-003 Lisboa, Portugal
| | - Mar Cunha
- Neuroinflammation, Signaling and Neuroregeneration Laboratory, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal; (G.G.); (S.P.); (M.C.)
| | - Adelaide Fernandes
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal;
- Central Nervous System, Blood and Peripheral Inflammation, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal
| | - Jari Koistinaho
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211 Kuopio, Finland; or
- Neuroscience Center, Helsinki Institute of Life Science (HiLIFE), University of Helsinki, FI-00014 Helsinki, Finland
| | - Dora Brites
- Neuroinflammation, Signaling and Neuroregeneration Laboratory, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal; (G.G.); (S.P.); (M.C.)
- Correspondence: ; Tel.: +351-217946450
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Chen YC, Huang HR, Hsu CH, Ou CY. CRMP/UNC-33 organizes microtubule bundles for KIF5-mediated mitochondrial distribution to axon. PLoS Genet 2021; 17:e1009360. [PMID: 33571181 PMCID: PMC7904166 DOI: 10.1371/journal.pgen.1009360] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 02/24/2021] [Accepted: 11/11/2020] [Indexed: 12/13/2022] Open
Abstract
Neurons are highly specialized cells with polarized cellular processes and subcellular domains. As vital organelles for neuronal functions, mitochondria are distributed by microtubule-based transport systems. Although the essential components of mitochondrial transport including motors and cargo adaptors are identified, it is less clear how mitochondrial distribution among somato-dendritic and axonal compartment is regulated. Here, we systematically study mitochondrial motors, including four kinesins, KIF5, KIF17, KIF1, KLP-6, and dynein, and transport regulators in C. elegans PVD neurons. Among all these motors, we found that mitochondrial export from soma to neurites is mainly mediated by KIF5/UNC-116. Interestingly, UNC-116 is especially important for axonal mitochondria, while dynein removes mitochondria from all plus-end dendrites and the axon. We surprisingly found one mitochondrial transport regulator for minus-end dendritic compartment, TRAK-1, and two mitochondrial transport regulators for axonal compartment, CRMP/UNC-33 and JIP3/UNC-16. While JIP3/UNC-16 suppresses axonal mitochondria, CRMP/UNC-33 is critical for axonal mitochondria; nearly no axonal mitochondria present in unc-33 mutants. We showed that UNC-33 is essential for organizing the population of UNC-116-associated microtubule bundles, which are tracks for mitochondrial trafficking. Disarrangement of these tracks impedes mitochondrial transport to the axon. In summary, we identified a compartment-specific transport regulation of mitochondria by UNC-33 through organizing microtubule tracks for different kinesin motors other than microtubule polarity.
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Affiliation(s)
- Ying-Chun Chen
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hao-Ru Huang
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Hao Hsu
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chan-Yen Ou
- Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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5
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Quintanilla RA, Tapia-Monsalves C, Vergara EH, Pérez MJ, Aranguiz A. Truncated Tau Induces Mitochondrial Transport Failure Through the Impairment of TRAK2 Protein and Bioenergetics Decline in Neuronal Cells. Front Cell Neurosci 2020; 14:175. [PMID: 32848607 PMCID: PMC7406829 DOI: 10.3389/fncel.2020.00175] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 05/22/2020] [Indexed: 12/22/2022] Open
Abstract
Mitochondria are highly specialized organelles essential for the synapse, and their impairment contributes to the neurodegeneration in Alzheimer's disease (AD). Previously, we studied the role of caspase-3-cleaved tau in mitochondrial dysfunction in AD. In neurons, the presence of this AD-relevant tau form induced mitochondrial fragmentation with a concomitant reduction in the expression of Opa1, a mitochondrial fission regulator. More importantly, we showed that caspase-cleaved tau affects mitochondrial transport, decreasing the number of moving mitochondria in the neuronal processes without affecting their velocity rate. However, the molecular mechanisms involved in these events are unknown. We studied the possible role of motor proteins (kinesin 1 and dynein) and mitochondrial protein adaptors (RhoT1/T2, syntaphilin, and TRAK2) in the mitochondrial transport failure induced by caspase-cleaved tau. We expressed green fluorescent protein (GFP), GFP-full-length, and GPF-caspase-3-cleaved tau proteins in rat hippocampal neurons and immortalized cortical neurons (CN 1.4) and analyzed the expression and localization of these proteins involved in mitochondrial transport regulation. We observed that hippocampal neurons expressing caspase-cleaved tau showed a significant accumulation of a mitochondrial population in the soma. These changes were accompanied by evident mitochondrial bioenergetic deficits, including depolarization, oxidative stress, and a significant reduction in ATP production. More critically, caspase-cleaved tau significantly decreased the expression of TRAK2 in immortalized and primary hippocampal neurons without affecting RhoT1/T2 and syntaphilin levels. Also, when we analyzed the expression of motor proteins-Kinesin 1 (KIF5) and Dynein-we did not detect changes in their expression, localization, and binding to the mitochondria. Interestingly, the expression of truncated tau significantly increases the association of TRAK2 with mitochondria compared with neuronal cells expressing full-length tau. Altogether these results indicate that caspase-cleaved tau may affect mitochondrial transport through the increase of TRAK2-mitochondria binding and reduction of ATP production available for the process of movement of these organelles. These observations are novel and represent a set of exciting findings whereby tau pathology could affect mitochondrial distribution in neurons, an event that may contribute to synaptic failure observed in AD.
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Affiliation(s)
- Rodrigo A. Quintanilla
- Laboratory of Neurodegenerative Diseases, Facultad de Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile
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6
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Liu J, Li L, Yang Y, Hong B, Chen X, Xie Q, Han H. Automatic Reconstruction of Mitochondria and Endoplasmic Reticulum in Electron Microscopy Volumes by Deep Learning. Front Neurosci 2020; 14:599. [PMID: 32792893 PMCID: PMC7394701 DOI: 10.3389/fnins.2020.00599] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 05/15/2020] [Indexed: 02/06/2023] Open
Abstract
Together, mitochondria and the endoplasmic reticulum (ER) occupy more than 20% of a cell's volume, and morphological abnormality may lead to cellular function disorders. With the rapid development of large-scale electron microscopy (EM), manual contouring and three-dimensional (3D) reconstruction of these organelles has previously been accomplished in biological studies. However, manual segmentation of mitochondria and ER from EM images is time consuming and thus unable to meet the demands of large data analysis. Here, we propose an automated pipeline for mitochondrial and ER reconstruction, including the mitochondrial and ER contact sites (MAMs). We propose a novel recurrent neural network to detect and segment mitochondria and a fully residual convolutional network to reconstruct the ER. Based on the sparse distribution of synapses, we use mitochondrial context information to rectify the local misleading results and obtain 3D mitochondrial reconstructions. The experimental results demonstrate that the proposed method achieves state-of-the-art performance.
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Affiliation(s)
- Jing Liu
- National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, China.,School of Artificial Intelligence, School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Linlin Li
- National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, China
| | - Yang Yang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Bei Hong
- National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, China.,School of Artificial Intelligence, School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Xi Chen
- National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, China
| | - Qiwei Xie
- National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, China.,Data Mining Lab, Beijing University of Technology, Beijing, China
| | - Hua Han
- National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, China.,School of Artificial Intelligence, School of Future Technology, University of Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai, China
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7
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Chen F, Danladi J, Wegener G, Madsen TM, Nyengaard JR. Sustained Ultrastructural Changes in Rat Hippocampal Formation After Repeated Electroconvulsive Seizures. Int J Neuropsychopharmacol 2020; 23:446-458. [PMID: 32215561 PMCID: PMC7387769 DOI: 10.1093/ijnp/pyaa021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 03/03/2020] [Accepted: 03/20/2020] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Electroconvulsive therapy (ECT) is a highly effective and fast-acting treatment for depression used in the clinic. Its mechanism of therapeutic action remains uncertain. Previous studies have focused on documenting neuroplasticity in the early phase following electroconvulsive seizures (ECS), an animal model of ECT. Here, we investigate whether changes in synaptic plasticity and nonneuronal plasticity (vascular and mitochondria) are sustained 3 months after repeated ECS trials. METHODS ECS or sham treatment was given daily for 1 day or 10 days to a genetic animal model of depression: the Flinders Sensitive and Resistant Line rats. Stereological principles were employed to quantify numbers of synapses and mitochondria as well as length of microvessels in the hippocampus 24 hours after a single ECS. Three months after 10 ECS treatments (1 per day for 10 days) and sham-treatment, brain-derived neurotrophic factor and vascular endothelial growth factor protein levels were quantified with immunohistochemistry. RESULTS A single ECS treatment significantly increased the volume of hippocampal CA1-stratum radiatum, the total length of microvessels, mitochondria number, and synapse number. Observed changes were sustained as shown in the multiple ECS treatment group analyzed 3 months after the last of 10 ECS treatments. CONCLUSION A single ECS caused rapid effects of synaptic plasticity and nonneuronal plasticity, while repeated ECS induced long-lasting changes in the efficacy of synaptic plasticity and nonneuronal plasticity at least up to 3 months after ECS.
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Affiliation(s)
- Fenghua Chen
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Correspondence: Fenghua Chen, MD, PhD, Department of Clinical Medicine - Translational Neuropsychiatry Unit, Nørrebrogade 44, Building 2B, 8000 Aarhus C, Denmark ()
| | - Jibrin Danladi
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Gregers Wegener
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Center of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa,AUGUST Centre, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Torsten M Madsen
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Jens R Nyengaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark
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8
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Bermúdez-Guzmán L, Leal A. DNA repair deficiency in neuropathogenesis: when all roads lead to mitochondria. Transl Neurodegener 2019; 8:14. [PMID: 31110700 PMCID: PMC6511134 DOI: 10.1186/s40035-019-0156-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/24/2019] [Indexed: 12/18/2022] Open
Abstract
Mutations in DNA repair enzymes can cause two neurological clinical manifestations: a developmental impairment and a degenerative disease. Polynucleotide kinase 3'-phosphatase (PNKP) is an enzyme that is actively involved in DNA repair in both single and double strand break repair systems. Mutations in this protein or others in the same pathway are responsible for a complex group of diseases with a broad clinical spectrum. Besides, mitochondrial dysfunction also has been consolidated as a hallmark of brain degeneration. Here we provide evidence that supports a shared role between mitochondrial dysfunction and DNA repair defects in the pathogenesis of the nervous system. As models, we analyze PNKP-related disorders, focusing on Charcot-Marie-Tooth disease and ataxia. A better understanding of the molecular dynamics of this relationship could provide improved diagnosis and treatment for neurological diseases.
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Affiliation(s)
- Luis Bermúdez-Guzmán
- Section of Genetics and Biotechnology, School of Biology, Universidad de Costa Rica, San José, 11501 Costa Rica
| | - Alejandro Leal
- Section of Genetics and Biotechnology, School of Biology, Universidad de Costa Rica, San José, 11501 Costa Rica
- Neuroscience Research Center, Universidad de Costa Rica, San José, Costa Rica
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9
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Chen F, Danladi J, Ardalan M, Elfving B, Müller HK, Wegener G, Sanchez C, Nyengaard JR. A Critical Role of Mitochondria in BDNF-Associated Synaptic Plasticity After One-Week Vortioxetine Treatment. Int J Neuropsychopharmacol 2018; 21. [PMID: 29514282 PMCID: PMC6007239 DOI: 10.1093/ijnp/pyy022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Preclinical studies have indicated that antidepressant effect of vortioxetine involves increased synaptic plasticity and promotion of spine maturation. Mitochondria dysfunction may contribute to the pathophysiological basis of major depressive disorder. Taking into consideration that vortioxetine increases spine number and dendritic branching in hippocampus CA1 faster than fluoxetine, we hypothesize that new spines induced by vortioxetine can rapidly form functional synapses by mitochondrial support, accompanied by increased brain-derived neurotrophic factor signaling. METHODS Rats were treated for 1 week with vortioxetine or fluoxetine at pharmacologically relevant doses. Number of synapses and mitochondria in hippocampus CA1 were quantified by electron microscopy. Brain-derived neurotrophic factor protein levels were visualized with immunohistochemistry. Gene and protein expression of synapse and mitochondria-related markers were investigated with real-time quantitative polymerase chain reaction and immunoblotting. RESULTS Vortioxetine increased number of synapses and mitochondria significantly, whereas fluoxetine had no effect after 1-week dosing. BDNF levels in hippocampus DG and CA1 were significantly higher after vortioxetine treatment. Gene expression levels of Rac1 after vortioxetine treatment were significantly increased. There was a tendency towards increased gene expression levels of Drp1 and protein levels of Rac1. However, both gene and protein levels of c-Fos were significantly decreased. Furthermore, there was a significant positive correlation between BDNF levels and mitochondria and synapse numbers. CONCLUSION Our results imply that mitochondria play a critical role in synaptic plasticity accompanied by increased BDNF levels. Rapid changes in BDNF levels and synaptic/mitochondria plasticity of hippocampus following vortioxetine compared with fluoxetine may be ascribed to vortioxetine's modulation of serotonin receptors.
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Affiliation(s)
- Fenghua Chen
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Correspondence: Fenghua Chen, Department of Clinical Medicine - Translational Neuropsychiatry Unit, Skovagervej 2, 8240 Risskov, Denmark ()
| | - Jibrin Danladi
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | - Maryam Ardalan
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
- Department of Clinical Medicine - Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Betina Elfving
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | - Heidi K Müller
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | - Gregers Wegener
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
- Center of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
- AUGUST Centre, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | - Connie Sanchez
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
- Alkermes, Biotechnology, Waltham, MA
| | - Jens R Nyengaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark
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10
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Chen F, Ardalan M, Elfving B, Wegener G, Madsen TM, Nyengaard JR. Mitochondria Are Critical for BDNF-Mediated Synaptic and Vascular Plasticity of Hippocampus following Repeated Electroconvulsive Seizures. Int J Neuropsychopharmacol 2017; 21:291-304. [PMID: 29228215 PMCID: PMC5838811 DOI: 10.1093/ijnp/pyx115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 12/05/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Electroconvulsive therapy is a fast-acting and efficient treatment of depression used in the clinic. The underlying mechanism of its therapeutic effect is still unclear. However, recovery of synaptic connections and synaptic remodeling is thought to play a critical role for the clinical efficacy obtained from a rapid antidepressant response. Here, we investigated the relationship between synaptic changes and concomitant nonneuronal changes in microvasculature and mitochondria and its relationship to brain-derived neurotrophic factor level changes after repeated electroconvulsive seizures, an animal model of electroconvulsive therapy. METHODS Electroconvulsive seizures or sham treatment was given daily for 10 days to rats displaying a genetically driven phenotype modelling clinical depression: the Flinders Sensitive and Resistant Line rats. Stereological principles were employed to quantify numbers of synapses and mitochondria, and the length of microvessels in the hippocampus. The brain-derived neurotrophic factor protein levels were quantified with immunohistochemistry. RESULTS In untreated controls, a lower number of synapses and mitochondria was accompanied by shorter microvessels of the hippocampus in "depressive" phenotype (Flinders Sensitive Line) compared with the "nondepressed" phenotype (Flinders Resistant Line). Electroconvulsive seizure administration significantly increased the number of synapses and mitochondria, and length of microvessels both in Flinders Sensitive Line-electroconvulsive seizures and Flinders Resistant Line-electroconvulsive seizures rats. In addition, the amount of brain-derived neurotrophic factor protein was significantly increased in Flinders Sensitive Line and Flinders Resistant Line rats after electroconvulsive seizures. Furthermore, there was a significant positive correlation between brain-derived neurotrophic factor level and mitochondria/synapses. CONCLUSION Our results indicate that rapid and efficient therapeutic effect of electroconvulsive seizures may be related to synaptic plasticity, accompanied by brain-derived neurotrophic factor protein level elevation and mitochondrial and vascular support.
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Affiliation(s)
- Fenghua Chen
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Correspondence: Fenghua Chen, MD, PhD, Department of Clinical Medicine, Translational Neuropsychiatry Unit, Skovagervej 2, building 14K, 0.15, 8240 Risskov, Denmark ()
| | - Maryam Ardalan
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark,Center of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa,Department of Clinical Medicine, Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Betina Elfving
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | - Gregers Wegener
- AUGUST Centre, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | | | - Jens R Nyengaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark
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11
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Aouacheria A, Baghdiguian S, Lamb HM, Huska JD, Pineda FJ, Hardwick JM. Connecting mitochondrial dynamics and life-or-death events via Bcl-2 family proteins. Neurochem Int 2017; 109:141-161. [PMID: 28461171 DOI: 10.1016/j.neuint.2017.04.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 04/17/2017] [Indexed: 12/12/2022]
Abstract
The morphology of a population of mitochondria is the result of several interacting dynamical phenomena, including fission, fusion, movement, elimination and biogenesis. Each of these phenomena is controlled by underlying molecular machinery, and when defective can cause disease. New understanding of the relationships between form and function of mitochondria in health and disease is beginning to be unraveled on several fronts. Studies in mammals and model organisms have revealed that mitochondrial morphology, dynamics and function appear to be subject to regulation by the same proteins that regulate apoptotic cell death. One protein family that influences mitochondrial dynamics in both healthy and dying cells is the Bcl-2 protein family. Connecting mitochondrial dynamics with life-death pathway forks may arise from the intersection of Bcl-2 family proteins with the proteins and lipids that determine mitochondrial shape and function. Bcl-2 family proteins also have multifaceted influences on cells and mitochondria, including calcium handling, autophagy and energetics, as well as the subcellular localization of mitochondrial organelles to neuronal synapses. The remarkable range of physical or functional interactions by Bcl-2 family proteins is challenging to assimilate into a cohesive understanding. Most of their effects may be distinct from their direct roles in apoptotic cell death and are particularly apparent in the nervous system. Dual roles in mitochondrial dynamics and cell death extend beyond BCL-2 family proteins. In this review, we discuss many processes that govern mitochondrial structure and function in health and disease, and how Bcl-2 family proteins integrate into some of these processes.
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Affiliation(s)
- Abdel Aouacheria
- Institute of Evolutionary Sciences of Montpellier (ISEM), CNRS UMR 5554, University of Montpellier, Place Eugène Bataillon, 34095 Montpellier, France
| | - Stephen Baghdiguian
- Institute of Evolutionary Sciences of Montpellier (ISEM), CNRS UMR 5554, University of Montpellier, Place Eugène Bataillon, 34095 Montpellier, France
| | - Heather M Lamb
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - Jason D Huska
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - Fernando J Pineda
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA; Department of Biostatistics, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - J Marie Hardwick
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA.
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Beck K, Ehmann N, Andlauer TFM, Ljaschenko D, Strecker K, Fischer M, Kittel RJ, Raabe T. Loss of the Coffin-Lowry syndrome-associated gene RSK2 alters ERK activity, synaptic function and axonal transport in Drosophila motoneurons. Dis Model Mech 2015; 8:1389-400. [PMID: 26398944 PMCID: PMC4631788 DOI: 10.1242/dmm.021246] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/27/2015] [Indexed: 01/06/2023] Open
Abstract
Plastic changes in synaptic properties are considered as fundamental for adaptive behaviors. Extracellular-signal-regulated kinase (ERK)-mediated signaling has been implicated in regulation of synaptic plasticity. Ribosomal S6 kinase 2 (RSK2) acts as a regulator and downstream effector of ERK. In the brain, RSK2 is predominantly expressed in regions required for learning and memory. Loss-of-function mutations in human RSK2 cause Coffin-Lowry syndrome, which is characterized by severe mental retardation and low IQ scores in affected males. Knockout of RSK2 in mice or the RSK ortholog in Drosophila results in a variety of learning and memory defects. However, overall brain structure in these animals is not affected, leaving open the question of the pathophysiological consequences. Using the fly neuromuscular system as a model for excitatory glutamatergic synapses, we show that removal of RSK function causes distinct defects in motoneurons and at the neuromuscular junction. Based on histochemical and electrophysiological analyses, we conclude that RSK is required for normal synaptic morphology and function. Furthermore, loss of RSK function interferes with ERK signaling at different levels. Elevated ERK activity was evident in the somata of motoneurons, whereas decreased ERK activity was observed in axons and the presynapse. In addition, we uncovered a novel function of RSK in anterograde axonal transport. Our results emphasize the importance of fine-tuning ERK activity in neuronal processes underlying higher brain functions. In this context, RSK acts as a modulator of ERK signaling.
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Affiliation(s)
- Katherina Beck
- University of Würzburg, Institute of Medical Radiation and Cell Research, Versbacherstraße 5, Würzburg D-97078, Germany
| | - Nadine Ehmann
- University of Würzburg, Institute of Physiology, Department of Neurophysiology, Röntgenring 9, Würzburg D-97070, Germany
| | - Till F M Andlauer
- University of Würzburg, Rudolf Virchow Center, DFG Research Center for Experimental Biomedicine, Josef-Schneider-Straße 2, Würzburg D-97080, Germany Freie Universität Berlin, Institute of Biology, Takusstraße 6, Berlin D-14195, Germany Max Planck Institute of Colloidals and Interfaces, Am Mühlenberg 1, Potsdam D-14476, Germany
| | - Dmitrij Ljaschenko
- University of Würzburg, Institute of Physiology, Department of Neurophysiology, Röntgenring 9, Würzburg D-97070, Germany
| | - Katrin Strecker
- University of Würzburg, Institute of Medical Radiation and Cell Research, Versbacherstraße 5, Würzburg D-97078, Germany
| | - Matthias Fischer
- University Hospital Würzburg, Department of Psychiatry, Psychosomatics and Psychotherapy, Füchsleinstraße 15, Würzburg 97080, Germany
| | - Robert J Kittel
- University of Würzburg, Institute of Physiology, Department of Neurophysiology, Röntgenring 9, Würzburg D-97070, Germany
| | - Thomas Raabe
- University of Würzburg, Institute of Medical Radiation and Cell Research, Versbacherstraße 5, Würzburg D-97078, Germany
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13
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Miro's N-terminal GTPase domain is required for transport of mitochondria into axons and dendrites. J Neurosci 2015; 35:5754-71. [PMID: 25855186 DOI: 10.1523/jneurosci.1035-14.2015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Mitochondria are dynamically transported in and out of neuronal processes to maintain neuronal excitability and synaptic function. In higher eukaryotes, the mitochondrial GTPase Miro binds Milton/TRAK adaptor proteins linking microtubule motors to mitochondria. Here we show that Drosophila Miro (dMiro), which has previously been shown to be required for kinesin-driven axonal transport, is also critically required for the dynein-driven distribution of mitochondria into dendrites. In addition, we used the loss-of-function mutations dMiroT25N and dMiroT460N to determine the significance of dMiro's N-terminal and C-terminal GTPase domains, respectively. Expression of dMiroT25N in the absence of endogenous dMiro caused premature lethality and arrested development at a pupal stage. dMiroT25N accumulated mitochondria in the soma of larval motor and sensory neurons, and prevented their kinesin-dependent and dynein-dependent distribution into axons and dendrites, respectively. dMiroT25N mutant mitochondria also were severely fragmented and exhibited reduced kinesin and dynein motility in axons. In contrast, dMiroT460N did not impair viability, mitochondrial size, or the distribution of mitochondria. However, dMiroT460N reduced dynein motility during retrograde mitochondrial transport in axons. Finally, we show that substitutions analogous to the constitutively active Ras-G12V mutation in dMiro's N-terminal and C-terminal GTPase domains cause neomorphic phenotypic effects that are likely unrelated to the normal function of each GTPase domain. Overall, our analysis indicates that dMiro's N-terminal GTPase domain is critically required for viability, mitochondrial size, and the distribution of mitochondria out of the neuronal soma regardless of the employed motor, likely by promoting the transition from a stationary to a motile state.
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Smalheiser NR. The RNA-centred view of the synapse: non-coding RNAs and synaptic plasticity. Philos Trans R Soc Lond B Biol Sci 2015; 369:rstb.2013.0504. [PMID: 25135965 PMCID: PMC4142025 DOI: 10.1098/rstb.2013.0504] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
If mRNAs were the only RNAs made by a neuron, there would be a simple mapping of mRNAs to proteins. However, microRNAs and other non-coding RNAs (ncRNAs; endo-siRNAs, piRNAs, BC1, BC200, antisense and long ncRNAs, repeat-related transcripts, etc.) regulate mRNAs via effects on protein translation as well as transcriptional and epigenetic mechanisms. Not only are genes ON or OFF, but their ability to be translated can be turned ON or OFF at the level of synapses, supporting an enormous increase in information capacity. Here, I review evidence that ncRNAs are expressed pervasively within dendrites in mammalian brain; that some are activity-dependent and highly enriched near synapses; and that synaptic ncRNAs participate in plasticity responses including learning and memory. Ultimately, ncRNAs can be viewed as the post-it notes of the neuron. They have no literal meaning of their own, but derive their functions from where (and to what) they are stuck. This may explain, in part, why ncRNAs differ so dramatically from protein-coding genes, both in terms of the usual indicators of functionality and in terms of evolutionary constraints. ncRNAs do not appear to be direct mediators of synaptic transmission in the manner of neurotransmitters or receptors, yet they orchestrate synaptic plasticity—and may drive species-specific changes in cognition.
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Affiliation(s)
- Neil R Smalheiser
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL 60612, USA
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15
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Campbell DS, Okamoto H. Local caspase activation interacts with Slit-Robo signaling to restrict axonal arborization. ACTA ACUST UNITED AC 2014; 203:657-72. [PMID: 24385488 PMCID: PMC3840933 DOI: 10.1083/jcb.201303072] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In addition to being critical for apoptosis, components of the apoptotic pathway, such as caspases, are involved in other physiological processes in many types of cells, including neurons. However, very little is known about their role in dynamic, nonphysically destructive processes, such as axonal arborization and synaptogenesis. We show that caspases were locally active in vivo at the branch points of young, dynamic retinal ganglion cell axonal arbors but not in the cell body or in stable mature arbors. Caspase activation, dependent on Caspase-3, Caspase-9, and p38 mitogen-activated protein kinase (MAPK), rapidly increased at branch points corresponding with branch tip addition. Time-lapse imaging revealed that knockdown of Caspase-3 and Caspase-9 led to more stable arbors and presynaptic sites. Genetic analysis showed that Caspase-3, Caspase-9, and p38 MAPK interacted with Slit1a-Robo2 signaling, suggesting that localized activation of caspases lie downstream of a ligand receptor system, acting as key promoters of axonal branch tip and synaptic dynamics to restrict arbor growth in vivo in the central nervous system.
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Affiliation(s)
- Douglas S Campbell
- Laboratory for Developmental Gene Regulation, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
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16
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Abstract
Mitochondria are the power houses of the cell, but unlike the static structures portrayed in textbooks, they are dynamic organelles that move about the cell to deliver energy to locations in need. These organelles fuse with each other then split apart; some appear anchored and others more free to move around, and when damaged they are engulfed by autophagosomes. Together, these processes—mitochondrial trafficking, fusion and fission, and mitophagy—are best described by the term “mitochondrial dynamics”. The molecular machineries behind these events are relatively well known yet the precise dynamics in neurons remains under debate. Neurons pose a peculiar logistical challenge to mitochondria; how do these energy suppliers manage to traffic down long axons to deliver the requisite energy supply to distant parts of the cell? To date, the majority of neuronal mitochondrial dynamics studies have used cultured neurons, Drosophila larvae, zebrafish embryos, with occasional experiments in resting mouse nerves. However, a new study in this issue of PLOS Biology from Marija Sajic and colleagues provides an in vivo look at mitochondrial dynamics along resting and electrically active neurons of live anaesthetized mice.
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Affiliation(s)
- Dzhamilja Safiulina
- Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, Estonia
| | - Allen Kaasik
- Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, Estonia
- * E-mail:
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17
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Belekhova MG, Chudinova TV, Kenigfest NB. Calcium-binding proteins and cytochrome oxidase activity in the turtle optic tectum with special reference to the tectofugal visual pathway. J EVOL BIOCHEM PHYS+ 2013. [DOI: 10.1134/s0022093013050083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Hill SE, Parmar M, Gheres KW, Guignet MA, Huang Y, Jackson FR, Rolls MM. Development of dendrite polarity in Drosophila neurons. Neural Dev 2012; 7:34. [PMID: 23111238 PMCID: PMC3570434 DOI: 10.1186/1749-8104-7-34] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 09/14/2012] [Indexed: 11/10/2022] Open
Abstract
Background Drosophila neurons have dendrites that contain minus-end-out microtubules. This microtubule arrangement is different from that of cultured mammalian neurons, which have mixed polarity microtubules in dendrites. Results To determine whether Drosophila and mammalian dendrites have a common microtubule organization during development, we analyzed microtubule polarity in Drosophila dendritic arborization neuron dendrites at different stages of outgrowth from the cell body in vivo. As dendrites initially extended, they contained mixed polarity microtubules, like mammalian neurons developing in culture. Over a period of several days this mixed microtubule array gradually matured to a minus-end-out array. To determine whether features characteristic of dendrites were localized before uniform polarity was attained, we analyzed dendritic markers as dendrites developed. In all cases the markers took on their characteristic distribution while dendrites had mixed polarity. An axonal marker was also quite well excluded from dendrites throughout development, although this was perhaps more efficient in mature neurons. To confirm that dendrite character could be acquired in Drosophila while microtubules were mixed, we genetically disrupted uniform dendritic microtubule organization. Dendritic markers also localized correctly in this case. Conclusions We conclude that developing Drosophila dendrites initially have mixed microtubule polarity. Over time they mature to uniform microtubule polarity. Dendrite identity is established before the mature microtubule arrangement is attained, during the period of mixed microtubule polarity.
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Affiliation(s)
- Sarah E Hill
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
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19
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Van Laar VS, Berman SB. The interplay of neuronal mitochondrial dynamics and bioenergetics: implications for Parkinson's disease. Neurobiol Dis 2012; 51:43-55. [PMID: 22668779 DOI: 10.1016/j.nbd.2012.05.015] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 05/07/2012] [Accepted: 05/24/2012] [Indexed: 12/15/2022] Open
Abstract
The dynamic properties of mitochondria (mitochondrial fission, fusion, transport biogenesis and degradation) are critical for neuronal function and health, and dysregulation of mitochondrial dynamics has been increasingly linked to the pathogenesis of Parkinson's disease (PD). Mitochondrial dynamics and bioenergetics are interconnected, and this is of particular importance in neurons, which have a unique bioenergetic profile due to their energetic dependence on mitochondria and specialized, compartmentalized energetic needs. In this review, we summarize the interplay of mitochondrial dynamics and bioenergetics, and its particular relevance for neurodegeneration. Evidence linking dysregulation of mitochondrial dynamics to PD is presented from both toxin and genetic models, including newly emerging details of how PD-relevant genes PTEN-induced kinase 1 (PINK1) and Parkin regulate fission, fusion, mitophagy and transport. Finally, we discuss how neuronal bioenergetics may impact PD-relevant regulation of mitochondrial dynamics, and possible implications for understanding the role of mitochondrial dynamics in PD.
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Affiliation(s)
- Victor S Van Laar
- University of Pittsburgh Department of Neurology, Pittsburgh Institute for Neurodegenerative Diseases, Pittsburgh, PA 15213, USA
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20
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Abstract
Vigorous transport of cytoplasmic components along axons over substantial distances is crucial for the maintenance of neuron structure and function. The transport of mitochondria, which serves to distribute mitochondrial functions in a dynamic and non-uniform fashion, has attracted special interest in recent years following the discovery of functional connections among microtubules, motor proteins and mitochondria, and their influences on neurodegenerative diseases. Although the motor proteins that drive mitochondrial movement are now well characterized, the mechanisms by which anterograde and retrograde movement are coordinated with one another and with stationary axonal mitochondria are not yet understood. In this Commentary, we review why mitochondria move and how they move, focusing particularly on recent studies of transport regulation, which implicate control of motor activity by specific cell-signaling pathways, regulation of motor access to transport tracks and static microtubule-mitochondrion linkers. A detailed mechanism for modulating anterograde mitochondrial transport has been identified that involves Miro, a mitochondrial Ca(2+)-binding GTPase, which with associated proteins, can bind and control kinesin-1. Elements of the Miro complex also have important roles in mitochondrial fission-fusion dynamics, highlighting questions about the interdependence of biogenesis, transport, dynamics, maintenance and degradation.
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Affiliation(s)
- William M Saxton
- Department of Molecular Cell and Developmental Biology, University of California, Cruz, CA 95060, USA.
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21
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Costa V, Scorrano L. Shaping the role of mitochondria in the pathogenesis of Huntington's disease. EMBO J 2012; 31:1853-64. [PMID: 22446390 DOI: 10.1038/emboj.2012.65] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 02/20/2012] [Indexed: 12/28/2022] Open
Abstract
Intense research on the pathogenesis of Huntington's disease (HD), a genetic neurodegenerative disease caused by a polyglutamine expansion in the Huntingtin (Htt) protein, revealed multiple potential mechanisms, among which mitochondrial alterations had emerged as key determinants of the natural history of the disease. Pharmacological and genetic animal models of mitochondrial dysfunction in the striatum, which is mostly affected in HD corroborated a key role for these organelles in the pathogenesis of the disease. Here, we will give an account of the recent evidence indicating that the mitochondria-shaping machinery is altered in HD models and patients. Since its correction can counteract HD mitochondrial dysfunction and cellular damage, drugs impacting on mitochondrial shape are emerging as a new possibility of treatment for this devastating condition.
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Affiliation(s)
- Veronica Costa
- Department of Cell Physiology and Medicine, University of Geneva, Genève, Switzerland
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Affiliation(s)
- L W Enquist
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America.
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23
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Cell signaling and mitochondrial dynamics: Implications for neuronal function and neurodegenerative disease. Neurobiol Dis 2012; 51:13-26. [PMID: 22297163 DOI: 10.1016/j.nbd.2012.01.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/09/2012] [Accepted: 01/12/2012] [Indexed: 11/22/2022] Open
Abstract
Nascent evidence indicates that mitochondrial fission, fusion, and transport are subject to intricate regulatory mechanisms that intersect with both well-characterized and emerging signaling pathways. While it is well established that mutations in components of the mitochondrial fission/fusion machinery can cause neurological disorders, relatively little is known about upstream regulators of mitochondrial dynamics and their role in neurodegeneration. Here, we review posttranslational regulation of mitochondrial fission/fusion enzymes, with particular emphasis on dynamin-related protein 1 (Drp1), as well as outer mitochondrial signaling complexes involving protein kinases and phosphatases. We also review recent evidence that mitochondrial dynamics has profound consequences for neuronal development and synaptic transmission and discuss implications for clinical translation.
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24
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Borgne FL, Demarquoy J. Interaction between peroxisomes and mitochondria in fatty acid metabolism. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/ojmip.2012.21005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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PKA/AKAP1 and PP2A/Bβ2 regulate neuronal morphogenesis via Drp1 phosphorylation and mitochondrial bioenergetics. J Neurosci 2011; 31:15716-26. [PMID: 22049414 DOI: 10.1523/jneurosci.3159-11.2011] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial shape is determined by fission and fusion reactions, perturbation of which can contribute to neuronal injury and disease. Mitochondrial fission is catalyzed by dynamin-related protein 1 (Drp1), a large GTPase of the dynamin family that is highly expressed in neurons and regulated by various posttranslational modifications, including phosphorylation. We report here that reversible phosphorylation of Drp1 at a conserved Ser residue by an outer mitochondrial kinase (PKA/AKAP1) and phosphatase (PP2A/Bβ2) impacts dendrite and synapse development in cultured rat hippocampal neurons. PKA/AKAP1-mediated phosphorylation of Drp1 at Ser656 increased mitochondrial length and dendrite occupancy, enhancing dendritic outgrowth but paradoxically decreasing synapse number and density. Opposing PKA/AKAP1, PP2A/Bβ2-mediated dephosphorylation of Drp1 at Ser656 fragmented and depolarized mitochondria and depleted them from dendrites, stunting dendritic outgrowth but augmenting synapse formation. Raising and lowering intracellular calcium reproduced the effects of dephospho-Drp1 and phospho-Drp1on dendrite and synapse development, respectively, while boosting mitochondrial membrane potential with l-carnitine-fostered dendrite at the expense of synapse formation without altering mitochondrial size or distribution. Thus, outer mitochondrial PKA and PP2A regulate neuronal development by inhibiting and promoting mitochondrial division, respectively. We propose that the bioenergetic state of mitochondria, rather than their localization or shape per se, is the key effector of Drp1, altering calcium homeostasis to modulate neuronal morphology and connectivity.
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Abstract
Adult-onset neurodegenerative disorders are disabling and often fatal diseases of the nervous system whose underlying mechanisms of cell death remain unknown. Defects in mitochondrial respiration had previously been proposed to contribute to the occurrence of many, if not all, of the most common neurodegenerative disorders. However, the discovery of genes mutated in hereditary forms of these enigmatic diseases has additionally suggested defects in mitochondrial dynamics. Such disturbances can lead to changes in mitochondrial trafficking, in interorganellar communication, and in mitochondrial quality control. These new mechanisms by which mitochondria may also be linked to neurodegeneration will likely have far-reaching implications for our understanding of the pathophysiology and treatment of adult-onset neurodegenerative disorders.
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Cheng A, Hou Y, Mattson MP. Mitochondria and neuroplasticity. ASN Neuro 2010; 2:e00045. [PMID: 20957078 PMCID: PMC2949087 DOI: 10.1042/an20100019] [Citation(s) in RCA: 295] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 08/06/2010] [Accepted: 08/13/2010] [Indexed: 12/22/2022] Open
Abstract
The production of neurons from neural progenitor cells, the growth of axons and dendrites and the formation and reorganization of synapses are examples of neuroplasticity. These processes are regulated by cell-autonomous and intercellular (paracrine and endocrine) programs that mediate responses of neural cells to environmental input. Mitochondria are highly mobile and move within and between subcellular compartments involved in neuroplasticity (synaptic terminals, dendrites, cell body and the axon). By generating energy (ATP and NAD(+)), and regulating subcellular Ca(2+) and redox homoeostasis, mitochondria may play important roles in controlling fundamental processes in neuroplasticity, including neural differentiation, neurite outgrowth, neurotransmitter release and dendritic remodelling. Particularly intriguing is emerging data suggesting that mitochondria emit molecular signals (e.g. reactive oxygen species, proteins and lipid mediators) that can act locally or travel to distant targets including the nucleus. Disturbances in mitochondrial functions and signalling may play roles in impaired neuroplasticity and neuronal degeneration in Alzheimer's disease, Parkinson's disease, psychiatric disorders and stroke.
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Key Words
- AD, Alzheimer's disease
- AP, adaptor protein
- APP, amyloid precursor protein
- Aβ, amyloid β-peptide
- BDNF, brain-derived neurotrophic factor
- CR, caloric restriction
- CREB, cAMP-response-element-binding protein
- CaMK, Ca2+/calmodulin-dependent protein kinase
- ES, embryonic stem
- ETC, electron transport chain
- HD, Huntington's disease
- LRRK2, leucine-rich repeat kinase 2
- LTP, long-term potentiation
- MAPK, mitogen-activated protein kinase
- Mn-SOD, manganese superoxide dismutase
- NGF, nerve growth factor
- NMDA, N-methyl-d-aspartate
- Nrf1, nuclear respiratory factor 1
- OPA1, Optic Atrophy-1
- PD, Parkinson's disease
- PGC1α, peroxisome-proliferator-activated receptor γ co-activator 1α
- PINK1, PTEN (phosphatase and tensin homologue deleted on chromosome 10)-induced kinase 1
- PPAR, peroxisome-proliferator-activated receptor
- UCP, uncoupling protein
- mitochondria biogenesis
- mitochondria fission and fusion
- neural progenitor cell
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Affiliation(s)
- Aiwu Cheng
- *Laboratory of Neurosciences, National Institute of Aging Intramural Research Program, Baltimore, MD 21224, U.S.A
| | - Yan Hou
- *Laboratory of Neurosciences, National Institute of Aging Intramural Research Program, Baltimore, MD 21224, U.S.A
| | - Mark P Mattson
- *Laboratory of Neurosciences, National Institute of Aging Intramural Research Program, Baltimore, MD 21224, U.S.A
- †Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
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Nerve growth factor induces axonal filopodia through localized microdomains of phosphoinositide 3-kinase activity that drive the formation of cytoskeletal precursors to filopodia. J Neurosci 2010; 30:12185-97. [PMID: 20826681 DOI: 10.1523/jneurosci.1740-10.2010] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The initiation of axonal filopodia is the first step in the formation of collateral branches and synaptic structures. In sensory neurons, nerve growth factor (NGF) promotes the formation of axonal filopodia and branches. However, the signaling and cytoskeletal mechanisms of NGF-induced initiation of axonal filopodia are not clear. Axonal filopodia arise from precursor axonal cytoskeletal structures termed filamentous actin (F-actin) patches. Patches form spontaneously and are transient. Although filopodia emerge from patches, only a fraction of patches normally gives rise to filopodia. Using chicken sensory neurons and live imaging of enhanced yellow fluorescent protein (eYFP)-actin dynamics, we report that NGF promotes the formation of axonal filopodia by increasing the rate of F-actin patch formation but not the fraction of patches that give rise to filopodia. We also demonstrate that activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway is sufficient and required for driving the formation of axonal F-actin patches, filopodia, and axon branches. Using the green fluorescent protein-plekstrin homology domain of Akt, which targets to PI3K-generated phosphatidylinositol-3,4,5-triphosphate (PIP(3)), we report localized microdomains of PIP(3) accumulation that form in synchrony with F-actin patches and that NGF promotes the formation of microdomains of PIP(3) and patches. Finally, we find that, in NGF, F-actin patches form in association with axonal mitochondria and oxidative phosphorylation is required for patch formation. This investigation demonstrates that surprisingly NGF promotes formation of axonal filopodia by increasing the formation of cytoskeletal filopodial precursors (patches) through localized microdomains of PI3K signaling but not the emergence of filopodia from patches.
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