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Sayehmiri F, Motamedi F, Batool Z, Naderi N, Shaerzadeh F, Zoghi A, Rezaei O, Khodagholi F, Pourbadie HG. Mitochondrial plasticity and synaptic plasticity crosstalk; in health and Alzheimer's disease. CNS Neurosci Ther 2024; 30:e14897. [PMID: 39097920 PMCID: PMC11298206 DOI: 10.1111/cns.14897] [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: 01/05/2024] [Revised: 06/19/2024] [Accepted: 07/18/2024] [Indexed: 08/06/2024] Open
Abstract
Synaptic plasticity is believed to underlie the cellular and molecular basis of memory formation. Mitochondria are one of the main organelles involved in metabolism and energy maintenance as plastic organelles that change morphologically and functionally in response to cellular needs and regulate synaptic function and plasticity through multiple mechanisms, including ATP generation, calcium homeostasis, and biogenesis. An increased neuronal activity enhances synaptic efficiency, during which mitochondria's spatial distribution and morphology change significantly. These organelles build up in the pre-and postsynaptic zones to produce ATP, which is necessary for several synaptic processes like neurotransmitter release and recycling. Mitochondria also regulate calcium homeostasis by buffering intracellular calcium, which ensures proper synaptic activity. Furthermore, mitochondria in the presynaptic terminal have distinct morphological properties compared to dendritic or postsynaptic mitochondria. This specialization enables precise control of synaptic activity and plasticity. Mitochondrial dysfunction has been linked to synaptic failure in many neurodegenerative disorders, like Alzheimer's disease (AD). In AD, malfunctioning mitochondria cause delays in synaptic vesicle release and recycling, ionic gradient imbalances, and mostly synaptic failure. This review emphasizes mitochondrial plasticity's contribution to synaptic function. It also explores the profound effect of mitochondrial malfunction on neurodegenerative disorders, focusing on AD, and provides an overview of how they sustain cellular health under normal conditions and how their malfunction contributes to neurodegenerative diseases, highlighting their potential as a therapeutic target for such conditions.
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Affiliation(s)
- Fatemeh Sayehmiri
- Neuroscience Research Center, Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
| | - Fereshteh Motamedi
- Neuroscience Research Center, Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
- Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
| | - Zehra Batool
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological SciencesUniversity of KarachiKarachiPakistan
| | - Nima Naderi
- Department of Pharmacology and Toxicology, Faculty of PharmacyShahid Beheshti University of Medical SciencesTehranIran
| | | | - Anahita Zoghi
- Department of Neurology, Loghman Hakim HospitalShahid Beheshti University of Medical SciencesTehranIran
| | - Omidvar Rezaei
- Skull Base Research CenterLoghman Hakim Hospital, Shahid Beheshti University of Medical SciencesTehranIran
| | - Fariba Khodagholi
- Neuroscience Research Center, Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
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Dithmar S, Zare A, Salehi S, Briese M, Sendtner M. hnRNP R regulates mitochondrial movement and membrane potential in axons of motoneurons. Neurobiol Dis 2024; 193:106454. [PMID: 38408684 DOI: 10.1016/j.nbd.2024.106454] [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: 12/12/2023] [Revised: 02/12/2024] [Accepted: 02/23/2024] [Indexed: 02/28/2024] Open
Abstract
Axonal mitochondria defects are early events in the pathogenesis of motoneuron disorders such as spinal muscular atrophy and amyotrophic lateral sclerosis. The RNA-binding protein hnRNP R interacts with different motoneuron disease-related proteins such as SMN and TDP-43 and has important roles in axons of motoneurons, including axonal mRNA transport. However, whether hnRNP R also modulates axonal mitochondria is currently unknown. Here, we show that axonal mitochondria exhibit altered function and motility in hnRNP R-deficient motoneurons. Motoneurons lacking hnRNP R show decreased anterograde and increased retrograde transport of mitochondria in axons. Furthermore, hnRNP R-deficiency leads to mitochondrial hyperpolarization, caused by decreased complex I and reversed complex V activity within the respiratory chain. Taken together, our data indicate a role for hnRNP R in regulating transport and maintaining functionality of axonal mitochondria in motoneurons.
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Affiliation(s)
- Sophia Dithmar
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Abdolhossein Zare
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Saeede Salehi
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Wuerzburg, Wuerzburg, Germany.
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3
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Nolte DD. Coherent light scattering from cellular dynamics in living tissues. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:036601. [PMID: 38433567 DOI: 10.1088/1361-6633/ad2229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/24/2024] [Indexed: 03/05/2024]
Abstract
This review examines the biological physics of intracellular transport probed by the coherent optics of dynamic light scattering from optically thick living tissues. Cells and their constituents are in constant motion, composed of a broad range of speeds spanning many orders of magnitude that reflect the wide array of functions and mechanisms that maintain cellular health. From the organelle scale of tens of nanometers and upward in size, the motion inside living tissue is actively driven rather than thermal, propelled by the hydrolysis of bioenergetic molecules and the forces of molecular motors. Active transport can mimic the random walks of thermal Brownian motion, but mean-squared displacements are far from thermal equilibrium and can display anomalous diffusion through Lévy or fractional Brownian walks. Despite the average isotropic three-dimensional environment of cells and tissues, active cellular or intracellular transport of single light-scattering objects is often pseudo-one-dimensional, for instance as organelle displacement persists along cytoskeletal tracks or as membranes displace along the normal to cell surfaces, albeit isotropically oriented in three dimensions. Coherent light scattering is a natural tool to characterize such tissue dynamics because persistent directed transport induces Doppler shifts in the scattered light. The many frequency-shifted partial waves from the complex and dynamic media interfere to produce dynamic speckle that reveals tissue-scale processes through speckle contrast imaging and fluctuation spectroscopy. Low-coherence interferometry, dynamic optical coherence tomography, diffusing-wave spectroscopy, diffuse-correlation spectroscopy, differential dynamic microscopy and digital holography offer coherent detection methods that shed light on intracellular processes. In health-care applications, altered states of cellular health and disease display altered cellular motions that imprint on the statistical fluctuations of the scattered light. For instance, the efficacy of medical therapeutics can be monitored by measuring the changes they induce in the Doppler spectra of livingex vivocancer biopsies.
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Affiliation(s)
- David D Nolte
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, United States of America
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Reiss AB, Gulkarov S, Jacob B, Srivastava A, Pinkhasov A, Gomolin IH, Stecker MM, Wisniewski T, De Leon J. Mitochondria in Alzheimer's Disease Pathogenesis. Life (Basel) 2024; 14:196. [PMID: 38398707 PMCID: PMC10890468 DOI: 10.3390/life14020196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/25/2024] Open
Abstract
Alzheimer's disease (AD) is a progressive and incurable neurodegenerative disorder that primarily affects persons aged 65 years and above. It causes dementia with memory loss and deterioration in thinking and language skills. AD is characterized by specific pathology resulting from the accumulation in the brain of extracellular plaques of amyloid-β and intracellular tangles of phosphorylated tau. The importance of mitochondrial dysfunction in AD pathogenesis, while previously underrecognized, is now more and more appreciated. Mitochondria are an essential organelle involved in cellular bioenergetics and signaling pathways. Mitochondrial processes crucial for synaptic activity such as mitophagy, mitochondrial trafficking, mitochondrial fission, and mitochondrial fusion are dysregulated in the AD brain. Excess fission and fragmentation yield mitochondria with low energy production. Reduced glucose metabolism is also observed in the AD brain with a hypometabolic state, particularly in the temporo-parietal brain regions. This review addresses the multiple ways in which abnormal mitochondrial structure and function contribute to AD. Disruption of the electron transport chain and ATP production are particularly neurotoxic because brain cells have disproportionately high energy demands. In addition, oxidative stress, which is extremely damaging to nerve cells, rises dramatically with mitochondrial dyshomeostasis. Restoring mitochondrial health may be a viable approach to AD treatment.
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Affiliation(s)
- Allison B. Reiss
- Department of Medicine and Biomedical Research Institute, NYU Grossman Long Island School of Medicine, Mineola, NY 11501, USA; (S.G.); (B.J.); (A.S.); (A.P.); (I.H.G.); (J.D.L.)
| | - Shelly Gulkarov
- Department of Medicine and Biomedical Research Institute, NYU Grossman Long Island School of Medicine, Mineola, NY 11501, USA; (S.G.); (B.J.); (A.S.); (A.P.); (I.H.G.); (J.D.L.)
| | - Benna Jacob
- Department of Medicine and Biomedical Research Institute, NYU Grossman Long Island School of Medicine, Mineola, NY 11501, USA; (S.G.); (B.J.); (A.S.); (A.P.); (I.H.G.); (J.D.L.)
| | - Ankita Srivastava
- Department of Medicine and Biomedical Research Institute, NYU Grossman Long Island School of Medicine, Mineola, NY 11501, USA; (S.G.); (B.J.); (A.S.); (A.P.); (I.H.G.); (J.D.L.)
| | - Aaron Pinkhasov
- Department of Medicine and Biomedical Research Institute, NYU Grossman Long Island School of Medicine, Mineola, NY 11501, USA; (S.G.); (B.J.); (A.S.); (A.P.); (I.H.G.); (J.D.L.)
| | - Irving H. Gomolin
- Department of Medicine and Biomedical Research Institute, NYU Grossman Long Island School of Medicine, Mineola, NY 11501, USA; (S.G.); (B.J.); (A.S.); (A.P.); (I.H.G.); (J.D.L.)
| | - Mark M. Stecker
- The Fresno Institute of Neuroscience, Fresno, CA 93730, USA;
| | - Thomas Wisniewski
- Center for Cognitive Neurology, Departments of Neurology, Pathology and Psychiatry, New York University Grossman School of Medicine, New York, NY 10016, USA;
| | - Joshua De Leon
- Department of Medicine and Biomedical Research Institute, NYU Grossman Long Island School of Medicine, Mineola, NY 11501, USA; (S.G.); (B.J.); (A.S.); (A.P.); (I.H.G.); (J.D.L.)
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5
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Jeong Y, Davis CHO, Muscarella AM, Deshpande V, Kim KY, Ellisman MH, Marsh-Armstrong N. Glaucoma-associated Optineurin mutations increase transmitophagy in a vertebrate optic nerve. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.26.542507. [PMID: 37398269 PMCID: PMC10312487 DOI: 10.1101/2023.05.26.542507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
We previously described a process referred to as transmitophagy where mitochondria shed by retinal ganglion cell (RGC) axons are transferred to and degraded by surrounding astrocytes in the optic nerve head of mice. Since the mitophagy receptor Optineurin (OPTN) is one of few large-effect glaucoma genes and axonal damage occurs at the optic nerve head in glaucoma, here we explored whether OPTN mutations perturb transmitophagy. Live-imaging of Xenopus laevis optic nerves revealed that diverse human mutant but not wildtype OPTN increase stationary mitochondria and mitophagy machinery and their colocalization within, and in the case of the glaucoma-associated OPTN mutations also outside of, RGC axons. These extra-axonal mitochondria are degraded by astrocytes. Our studies support the view that in RGC axons under baseline conditions there are low levels of mitophagy, but that glaucoma-associated perturbations in OPTN result in increased axonal mitophagy involving the shedding and astrocytic degradation of the mitochondria.
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Affiliation(s)
- Yaeram Jeong
- Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, CA 95817, USA
| | | | - Aaron M. Muscarella
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, Department of Neurosciences, University of California San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Viraj Deshpande
- Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, CA 95817, USA
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, Department of Neurosciences, University of California San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Mark H. Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, Department of Neurosciences, University of California San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Nicholas Marsh-Armstrong
- Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, CA 95817, USA
- Lead contact
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Canty JT, Hensley A, Aslan M, Jack A, Yildiz A. TRAK adaptors regulate the recruitment and activation of dynein and kinesin in mitochondrial transport. Nat Commun 2023; 14:1376. [PMID: 36914620 PMCID: PMC10011603 DOI: 10.1038/s41467-023-36945-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 02/23/2023] [Indexed: 03/16/2023] Open
Abstract
Mitochondrial transport along microtubules is mediated by Miro1 and TRAK adaptors that recruit kinesin-1 and dynein-dynactin. To understand how these opposing motors are regulated during mitochondrial transport, we reconstitute the bidirectional transport of Miro1/TRAK along microtubules in vitro. We show that the coiled-coil domain of TRAK activates dynein-dynactin and enhances the motility of kinesin-1 activated by its cofactor MAP7. We find that TRAK adaptors that recruit both motors move towards kinesin-1's direction, whereas kinesin-1 is excluded from binding TRAK transported by dynein-dynactin, avoiding motor tug-of-war. We also test the predictions of the models that explain how mitochondrial transport stalls in regions with elevated Ca2+. Transport of Miro1/TRAK by kinesin-1 is not affected by Ca2+. Instead, we demonstrate that the microtubule docking protein syntaphilin induces resistive forces that stall kinesin-1 and dynein-driven motility. Our results suggest that mitochondrial transport stalls by Ca2+-mediated recruitment of syntaphilin to the mitochondrial membrane, not by disruption of the transport machinery.
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Affiliation(s)
- John T Canty
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, 94720, USA.
- Department of Cancer Immunology, Genentech Inc., 1 DNA Way, 94080, South San Francisco, CA, USA.
| | - Andrew Hensley
- Physics Department, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Merve Aslan
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Amanda Jack
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Ahmet Yildiz
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, 94720, USA.
- Physics Department, University of California at Berkeley, Berkeley, CA, 94720, USA.
- Department of Molecular and Cellular Biology, University of California at Berkeley, Berkeley, CA, 94720, USA.
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7
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Imbriani P, Martella G, Bonsi P, Pisani A. Oxidative stress and synaptic dysfunction in rodent models of Parkinson's disease. Neurobiol Dis 2022; 173:105851. [PMID: 36007757 DOI: 10.1016/j.nbd.2022.105851] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 08/02/2022] [Accepted: 08/20/2022] [Indexed: 11/26/2022] Open
Abstract
Parkinson's disease (PD) is a multifactorial disorder involving a complex interplay between a variety of genetic and environmental factors. In this scenario, mitochondrial impairment and oxidative stress are widely accepted as crucial neuropathogenic mechanisms, as also evidenced by the identification of PD-associated genes that are directly involved in mitochondrial function. The concept of mitochondrial dysfunction is closely linked to that of synaptic dysfunction. Indeed, compelling evidence supports the role of mitochondria in synaptic transmission and plasticity, although many aspects have not yet been fully elucidated. Here, we will provide a brief overview of the most relevant evidence obtained in different neurotoxin-based and genetic rodent models of PD, focusing on mitochondrial impairment and synaptopathy, an early central event preceding overt nigrostriatal neurodegeneration. The identification of early deficits occurring in PD pathogenesis is crucial in view of the development of potential disease-modifying therapeutic strategies.
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Affiliation(s)
- Paola Imbriani
- Laboratory of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Giuseppina Martella
- Laboratory of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Paola Bonsi
- Laboratory of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Antonio Pisani
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy; IRCCS Mondino Foundation, Pavia, Italy.
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8
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mtIF3 is locally translated in axons and regulates mitochondrial translation for axonal growth. BMC Biol 2022; 20:12. [PMID: 34996455 PMCID: PMC8742369 DOI: 10.1186/s12915-021-01215-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 11/09/2021] [Indexed: 11/13/2022] Open
Abstract
Background The establishment and maintenance of functional neural connections relies on appropriate distribution and localization of mitochondria in neurites, as these organelles provide essential energy and metabolites. In particular, mitochondria are transported to axons and support local energy production to maintain energy-demanding neuronal processes including axon branching, growth, and regeneration. Additionally, local protein synthesis is required for structural and functional changes in axons, with nuclear-encoded mitochondrial mRNAs having been found localized in axons. However, it remains unclear whether these mRNAs are locally translated and whether the potential translated mitochondrial proteins are involved in the regulation of mitochondrial functions in axons. Here, we aim to further understand the purpose of such compartmentalization by focusing on the role of mitochondrial initiation factor 3 (mtIF3), whose nuclear-encoded transcripts have been shown to be present in axonal growth cones. Results We demonstrate that brain-derived neurotrophic factor (BDNF) induces local translation of mtIF3 mRNA in axonal growth cones. Subsequently, mtIF3 protein is translocated into axonal mitochondria and promotes mitochondrial translation as assessed by our newly developed bimolecular fluorescence complementation sensor for the assembly of mitochondrial ribosomes. We further show that BDNF-induced axonal growth requires mtIF3-dependent mitochondrial translation in distal axons. Conclusion We describe a previously unknown function of mitochondrial initiation factor 3 (mtIF3) in axonal protein synthesis and development. These findings provide insight into the way neurons adaptively control mitochondrial physiology and axonal development via local mtIF3 translation. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01215-w.
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Gowda P, Reddy PH, Kumar S. Deregulated mitochondrial microRNAs in Alzheimer's disease: Focus on synapse and mitochondria. Ageing Res Rev 2022; 73:101529. [PMID: 34813976 PMCID: PMC8692431 DOI: 10.1016/j.arr.2021.101529] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/17/2021] [Accepted: 11/16/2021] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia and is currently one of the biggest public health concerns in the world. Mitochondrial dysfunction in neurons is one of the major hallmarks of AD. Emerging evidence suggests that mitochondrial miRNAs potentially play important roles in the mitochondrial dysfunctions, focusing on synapse in AD progression. In this meta-analysis paper, a comprehensive literature review was conducted to identify and discuss the (1) role of mitochondrial miRNAs that regulate mitochondrial and synaptic functions; (2) the role of various factors such as mitochondrial dynamics, biogenesis, calcium signaling, biological sex, and aging on synapse and mitochondrial function; (3) how synapse damage and mitochondrial dysfunctions contribute to AD; (4) the structure and function of synapse and mitochondria in the disease process; (5) latest research developments in synapse and mitochondria in healthy and disease states; and (6) therapeutic strategies that improve synaptic and mitochondrial functions in AD. Specifically, we discussed how differences in the expression of mitochondrial miRNAs affect ATP production, oxidative stress, mitophagy, bioenergetics, mitochondrial dynamics, synaptic activity, synaptic plasticity, neurotransmission, and synaptotoxicity in neurons observed during AD. However, more research is needed to confirm the locations and roles of individual mitochondrial miRNAs in the development of AD.
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Affiliation(s)
- Prashanth Gowda
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - P. Hemachandra Reddy
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Neuroscience & Pharmacology, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Neurology, Departments of School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Public Health Department of Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Department of Speech, Language and Hearing Sciences, School Health Professions, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Subodh Kumar
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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Mitochondria in Myelinating Oligodendrocytes: Slow and Out of Breath? Metabolites 2021; 11:metabo11060359. [PMID: 34198810 PMCID: PMC8226700 DOI: 10.3390/metabo11060359] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/23/2022] Open
Abstract
Myelin is a lipid-rich membrane that wraps around axons and facilitates rapid action potential propagation. In the brain, myelin is synthesized and maintained by oligodendrocytes. These cells have a high metabolic demand that requires mitochondrial ATP production during the process of myelination, but they rely less on mitochondrial respiration after myelination is complete. Mitochondria change in morphology and distribution during oligodendrocyte development. Furthermore, the morphology and dynamic properties of mitochondria in mature oligodendrocytes seem different from any other brain cell. Here, we first give a brief introduction to oligodendrocyte biology and function. We then review the current knowledge on oligodendrocyte metabolism and discuss how the available data on mitochondrial morphology and mobility as well as transcriptome and proteome studies can shed light on the metabolic properties of oligodendrocytes.
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11
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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: 12] [Impact Index Per Article: 4.0] [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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12
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Khan H, Beck C, Kunze A. Multi-curvature micropatterns unveil distinct calcium and mitochondrial dynamics in neuronal networks. LAB ON A CHIP 2021; 21:1164-1174. [PMID: 33543185 PMCID: PMC7990709 DOI: 10.1039/d0lc01205j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Tangential curvatures are a key geometric feature of tissue folds in the human cerebral cortex. In the brain, these smoother and firmer bends are called gyri and sulci and form distinctive curved tissue patterns imposing a mechanical stimulus on neuronal networks. This stimulus is hypothesized to be essential for proper brain cell function but lacks in most standard neuronal cell assays. A variety of soft lithographic micropatterning techniques can be used to integrate round geometries in cell assays. Most microfabricated patterns, however, focus only on a small set of defined curvatures. In contrast, curvatures in the brain span a wide physical range, leaving it unknown which precise role distinct curvatures may play on neuronal cell signaling. Here we report a hydrogel-based multi-curvature design consisting of over twenty bands of distinct parallel curvature ranges to precisely engineer neuronal networks' growth and signaling under patterns of arcs. Monitoring calcium and mitochondrial dynamics in primary rodent neurons grown over two weeks in the multi-curvature patterns, we found that static calcium signaling was locally attenuated under higher curvatures (k > 0.01 μm-1). In contrast, to randomize growth, transient calcium signaling showed higher synchronicity when neurons formed networks in confined multi-curvature patterns. Additionally, we found that mitochondria showed lower motility under high curvatures (k > 0.01 μm-1) than under lower curvatures (k < 0.01 μm-1). Our results demonstrate how sensitive neuronal cell function may be linked and controlled through specific curved geometric features. Furthermore, the hydrogel-based multi-curvature design possesses high compatibility with various surfaces, allowing a flexible integration of geometric features into next-generation neuro devices, cell assays, tissue engineering, and implants.
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Affiliation(s)
- Hammad Khan
- Department of Electrical and Computer Engineering, Montana State University, Bozeman, Montana 59717, USA.
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13
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Roberts RC. Mitochondrial dysfunction in schizophrenia: With a focus on postmortem studies. Mitochondrion 2021; 56:91-101. [PMID: 33221354 PMCID: PMC7810242 DOI: 10.1016/j.mito.2020.11.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/23/2020] [Accepted: 11/11/2020] [Indexed: 12/13/2022]
Abstract
Among the many brain abnormalities in schizophrenia are those related to mitochondrial functions such as oxidative stress, energy metabolism and synaptic efficacy. The aim of this paper is to provide a brief review of mitochondrial structure and function and then to present abnormalities in mitochondria in postmortem brain in schizophrenia with a focus on anatomy. Deficits in expression of various mitochondrial genes have been found in multiple schizophrenia cohorts. Decreased activity of complexes I and IV are prominent as well as abnormal levels of individual subunits that comprise the complexes of the electron transport chain. Ultrastructural studies have shown layer, input and cell specific decreases in mitochondria. In cortex, there are fewer mitochondria in axon terminals, neuronal somata of pyramidal neurons and oligodendrocytes in both grey and white matter. In the caudate and putamen mitochondrial number is linked with symptoms and symptom severity. While there is a decrease in the number of mitochondria in astrocytes, mitochondria are smaller in oligodendrocytes. In the nucleus accumbens and substantia nigra, mitochondria are similar in density, size and structural integrity in schizophrenia compared to controls. Mitochondrial production of ATP and calcium buffering are essential in maintaining synaptic strength and abnormalities in these processes could lead to decreased metabolism and defective synaptic activity. Abnormalities in mitochondria in oligodendrocytes might contribute to myelin pathology and underlie dysconnectivity in the brain. In schizophrenia, mitochondria are affected differentially depending on the brain region, cell type in which they reside, subcellular location, treatment status, treatment response and predominant symptoms.
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Affiliation(s)
- Rosalinda C Roberts
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham, AL 35294, United States.
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Smith GA, Lin TH, Sheehan AE, Van der Goes van Naters W, Neukomm LJ, Graves HK, Bis-Brewer DM, Züchner S, Freeman MR. Glutathione S-Transferase Regulates Mitochondrial Populations in Axons through Increased Glutathione Oxidation. Neuron 2019; 103:52-65.e6. [PMID: 31101394 PMCID: PMC6616599 DOI: 10.1016/j.neuron.2019.04.017] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/13/2018] [Accepted: 04/10/2019] [Indexed: 01/14/2023]
Abstract
Mitochondria are essential in long axons to provide metabolic support and sustain neuron integrity. A healthy mitochondrial pool is maintained by biogenesis, transport, mitophagy, fission, and fusion, but how these events are regulated in axons is not well defined. Here, we show that the Drosophila glutathione S-transferase (GST) Gfzf prevents mitochondrial hyperfusion in axons. Gfzf loss altered redox balance between glutathione (GSH) and oxidized glutathione (GSSG) and initiated mitochondrial fusion through the coordinated action of Mfn and Opa1. Gfzf functioned epistatically with the thioredoxin peroxidase Jafrac1 and the thioredoxin reductase 1 TrxR-1 to regulate mitochondrial dynamics. Altering GSH:GSSG ratios in mouse primary neurons in vitro also induced hyperfusion. Mitochondrial changes caused deficits in trafficking, the metabolome, and neuronal physiology. Changes in GSH and oxidative state are associated with neurodegenerative diseases like Alzheimer's. Our demonstration that GSTs are key in vivo regulators of axonal mitochondrial length and number provides a potential mechanistic link.
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Affiliation(s)
- Gaynor A Smith
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA; UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK.
| | - Tzu-Huai Lin
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Amy E Sheehan
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | | | - Lukas J Neukomm
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne VD, Switzerland
| | - Hillary K Graves
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dana M Bis-Brewer
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Stephan Züchner
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Marc R Freeman
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
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15
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Peters DT, Kay L, Eswaran J, Lakey JH, Soundararajan M. Human Miro Proteins Act as NTP Hydrolases through a Novel, Non-Canonical Catalytic Mechanism. Int J Mol Sci 2018; 19:ijms19123839. [PMID: 30513825 PMCID: PMC6321465 DOI: 10.3390/ijms19123839] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 01/13/2023] Open
Abstract
Mitochondria are highly dynamic organelles that play a central role in multiple cellular processes, including energy metabolism, calcium homeostasis and apoptosis. Miro proteins (Miros) are “atypical” Ras superfamily GTPases that display unique domain architecture and subcellular localisation regulating mitochondrial transport, autophagy and calcium sensing. Here, we present systematic catalytic domain characterisation and structural analyses of human Miros. Despite lacking key conserved catalytic residues (equivalent to Ras Y32, T35, G60 and Q61), the Miro N-terminal GTPase domains display GTPase activity. Surprisingly, the C-terminal GTPase domains previously assumed to be “relic” domains were also active. Moreover, Miros show substrate promiscuity and function as NTPases. Molecular docking and structural analyses of Miros revealed unusual features in the Switch I and II regions, facilitating promiscuous substrate binding and suggesting the usage of a novel hydrolytic mechanism. The key substitution in position 13 in the Miros leads us to suggest the existence of an “internal arginine finger”, allowing an unusual catalytic mechanism that does not require GAP protein. Together, the data presented here indicate novel catalytic functions of human Miro atypical GTPases through altered catalytic mechanisms.
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Affiliation(s)
- Daniel T Peters
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
| | - Laura Kay
- Department of Applied Sciences Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK.
| | - Jeyanthy Eswaran
- Northern Institute for Cancer Research, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU, UK.
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
| | - Meera Soundararajan
- Department of Applied Sciences Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK.
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16
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Rumora AE, LoGrasso G, Haidar JA, Dolkowski JJ, Lentz SI, Feldman EL. Chain length of saturated fatty acids regulates mitochondrial trafficking and function in sensory neurons. J Lipid Res 2018; 60:58-70. [PMID: 30442656 DOI: 10.1194/jlr.m086843] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/17/2018] [Indexed: 12/21/2022] Open
Abstract
Dyslipidemia associated with T2D leads to diabetic neuropathy, a complication characterized by sensory neuronal dysfunction and peripheral nerve damage. Sensory dorsal root ganglion (DRG) neurons are dependent on axonal mitochondrial energy production facilitated by mitochondrial transport mechanisms that distribute mitochondria throughout the axon. Because long-chain saturated FAs (SFAs) damage DRG neurons and medium-chain SFAs are reported to improve neuronal function, we evaluated the impact of SFA chain length on mitochondrial trafficking, mitochondrial function, and apoptosis. DRG neurons were exposed to SFAs with C12:0-C18:0 chain lengths and evaluated for changes in mitochondrial trafficking, mitochondrial polarization, and apoptosis. DRG neurons treated with C16:0 and C18:0 SFAs showed a significant decrease in the percentage of motile mitochondria and velocity of mitochondrial trafficking, whereas C12:0 and C14:0 SFAs had no impact on motility. Treatment with C16:0 and C18:0 SFAs exhibited mitochondrial depolarization correlating with impaired mitochondrial motility; the C12:0- and C14:0-treated neurons retained mitochondrial polarization. The reduction in mitochondrial trafficking and function in C16:0- and C18:0-treated DRG neurons correlated with apoptosis that was blocked in C12:0 and C14:0 SFA treatments. These results suggest that SFA chain length plays an important role in regulating axonal mitochondrial trafficking and function in DRG neurons.
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Affiliation(s)
- Amy E Rumora
- Departments of Neurology University of Michigan, Ann Arbor, MI 48109
| | - Giovanni LoGrasso
- Departments of Neurology University of Michigan, Ann Arbor, MI 48109
| | - Julia A Haidar
- Departments of Neurology University of Michigan, Ann Arbor, MI 48109
| | - Justin J Dolkowski
- Departments of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Stephen I Lentz
- Departments of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Eva L Feldman
- Departments of Neurology University of Michigan, Ann Arbor, MI 48109
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17
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Mariano V, Domínguez-Iturza N, Neukomm LJ, Bagni C. Maintenance mechanisms of circuit-integrated axons. Curr Opin Neurobiol 2018; 53:162-173. [PMID: 30241058 DOI: 10.1016/j.conb.2018.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 08/14/2018] [Indexed: 12/21/2022]
Abstract
Adult, circuit-integrated neurons must be maintained and supported for the life span of their host. The attenuation of either maintenance or plasticity leads to impaired circuit function and ultimately to neurodegenerative disorders. Over the last few years, significant discoveries of molecular mechanisms were made that mediate the formation and maintenance of axons. Here, we highlight intrinsic and extrinsic mechanisms that ensure the health and survival of axons. We also briefly discuss examples of mutations associated with impaired axonal maintenance identified in specific neurological conditions. A better understanding of these mechanisms will therefore help to define targets for therapeutic interventions.
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Affiliation(s)
- Vittoria Mariano
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland; Department of Neurosciences KU Leuven, VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Nuria Domínguez-Iturza
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland; Department of Neurosciences KU Leuven, VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Lukas J Neukomm
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland.
| | - Claudia Bagni
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland; Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy.
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18
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MCU Interacts with Miro1 to Modulate Mitochondrial Functions in Neurons. J Neurosci 2018; 38:4666-4677. [PMID: 29686046 DOI: 10.1523/jneurosci.0504-18.2018] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 04/11/2018] [Accepted: 04/17/2018] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial Ca2+ uptake is gated by the mitochondrial calcium uniplex, which is comprised of mitochondrial calcium uniporter (MCU), the Ca2+ pore-forming subunit of the complex, and its regulators. Ca2+ influx through MCU affects both mitochondrial function and movement in neurons, but its direct role in mitochondrial movement has not been explored. In this report, we show a link between MCU and Miro1, a membrane protein known to regulate mitochondrial movement. We find that MCU interacts with Miro1 through MCU's N-terminal domain, previously thought to be the mitochondrial targeting sequence. Our results show that the N-terminus of MCU has a transmembrane domain that traverses the outer mitochondrial membrane, which is dispensable for MCU localization into mitochondria. However, this domain is required for Miro1 interaction and is critical for Miro1 directed movement. Together, our findings reveal Miro1 as a new component of the MCU complex, and that MCU is an important regulator of mitochondrial transport.SIGNIFICANCE STATEMENT Mitochondrial calcium level is critical for mitochondrial metabolic activity and mitochondrial transport in neurons. While it has been established that calcium influx into mitochondria is modulated by mitochondrial calcium uniporter (MCU) complex, how MCU regulates mitochondrial movement still remains unclear. Here, we discover that the N-terminus of MCU plays a different role than previously thought; it is not required for mitochondrial targeting but is essential for interaction with Miro1, an outer mitochondrial membrane protein important for mitochondrial movement. Furthermore, we show that MCU-Miro1 interaction is required to maintain mitochondrial transport. Our data identify that Miro1 is a novel component of the mitochondrial calcium uniplex and demonstrate that coupling between MCU and Miro1 as a novel mechanism modulating both mitochondrial Ca2+ uptake and mitochondrial transport.
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19
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Gumy LF, Hoogenraad CC. Local mechanisms regulating selective cargo entry and long-range trafficking in axons. Curr Opin Neurobiol 2018; 51:23-28. [PMID: 29510294 DOI: 10.1016/j.conb.2018.02.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/14/2018] [Indexed: 02/02/2023]
Abstract
The polarized long-distance transport of neuronal cargoes depends on the presence of functional and structural axonal subcompartments. Given the heterogeneity of neuronal cargoes, selective sorting and entry occurs in the proximal axon where multiple subcellular specializations such as the axon initial segment, the pre-axonal exclusion zone, the MAP2 pre-axonal filtering zone and the Tau diffusion barrier provide different levels of regulation. Cargoes allowed to pass through the proximal axon spread into the more distal parts. Recent findings show that diverse cargo distributions along the axon depend on the compartmentalized organization of the cytoskeleton and the local regulation of multiple motor proteins by microtubule associated proteins. In this review, we focus on the local mechanisms that control cargo motility and discuss how they play a role in the overall circulation of axonal cargoes.
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Affiliation(s)
- Laura F Gumy
- Department of Anatomy, University of Otago, Dunedin, New Zealand.
| | - Casper C Hoogenraad
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
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20
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Smith GM, Gallo G. The role of mitochondria in axon development and regeneration. Dev Neurobiol 2017; 78:221-237. [PMID: 29030922 DOI: 10.1002/dneu.22546] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/12/2017] [Accepted: 10/08/2017] [Indexed: 12/26/2022]
Abstract
Mitochondria are dynamic organelles that undergo transport, fission, and fusion. The three main functions of mitochondria are to generate ATP, buffer cytosolic calcium, and generate reactive oxygen species. A large body of evidence indicates that mitochondria are either primary targets for neurological disease states and nervous system injury, or are major contributors to the ensuing pathologies. However, the roles of mitochondria in the development and regeneration of axons have just begun to be elucidated. Advances in the understanding of the functional roles of mitochondria in neurons had been largely impeded by insufficient knowledge regarding the molecular mechanisms that regulate mitochondrial transport, stalling, fission/fusion, and a paucity of approaches to image and analyze mitochondria in living axons at the level of the single mitochondrion. However, technical advances in the imaging and analysis of mitochondria in living neurons and significant insights into the mechanisms that regulate mitochondrial dynamics have allowed the field to advance. Mitochondria have now been attributed important roles in the mechanism of axon extension, regeneration, and axon branching. The availability of new experimental tools is expected to rapidly increase our understanding of the functions of axonal mitochondria during both development and later regenerative attempts. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 221-237, 2018.
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Affiliation(s)
- George M Smith
- Department of Neuroscience, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140.,Shriners Hospitals Pediatric Research Center, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Gianluca Gallo
- Department of Anatomy and Cell Biology, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140.,Shriners Hospitals Pediatric Research Center, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140
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21
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Roberts RC. Postmortem studies on mitochondria in schizophrenia. Schizophr Res 2017; 187:17-25. [PMID: 28189530 PMCID: PMC5550365 DOI: 10.1016/j.schres.2017.01.056] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 01/02/2023]
Abstract
The aim of this paper is to provide a brief review of mitochondrial structure as it relates to function and then present abnormalities in mitochondria in postmortem schizophrenia with a focus on ultrastructure. Function, morphology, fusion, fission, motility, ΔΨmem, ATP production, mitochondrial derived vesicles, and mitochondria-associated ER membranes will be briefly covered. Pathology in mitochondria has long been implicated in schizophrenia, as shown by genetic, proteomic, enzymatic and anatomical abnormalities. The cortex and basal ganglia will be reviewed. In the anterior cingulate cortex, the number of mitochondria per neuronal somata in layers 5/6 in schizophrenia is decreased by 43%. There are also fewer mitochondria in terminals forming axospinous synapses. In the caudate and putamen the number of mitochondria is abnormal in both glial cells and neurons in schizophrenia subjects, the extent of which depends on treatment, response and predominant lifetime symptoms. Treatment-responsive schizophrenia subjects had about a 40% decrease in the number of mitochondria per synapse in the caudate nucleus and putamen, while treatment resistant cases had normal values. A decrease in mitochondrial density in the neuropil distinguishes paranoid from undifferentiated schizophrenia. The appearance, size and density of mitochondria were normal in the nucleus accumbens. In the substantia nigra, COX subunits were affected in rostral regions. Mitochondrial hyperplasia occurs within axon terminals that synapse onto dopamine neurons, but mitochondria in dopamine neuronal somata are similar in size and number. In schizophrenia, mitochondria are differentially affected depending on the brain region, cell type, subcellular location, treatment status, treatment response and symptoms.
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Affiliation(s)
- Rosalinda C. Roberts
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham, AL 35294
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22
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Hafner AE, Santen L, Rieger H, Shaebani MR. Run-and-pause dynamics of cytoskeletal motor proteins. Sci Rep 2016; 6:37162. [PMID: 27849013 PMCID: PMC5111058 DOI: 10.1038/srep37162] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 10/25/2016] [Indexed: 11/23/2022] Open
Abstract
Cytoskeletal motor proteins are involved in major intracellular transport processes which are vital for maintaining appropriate cellular function. When attached to cytoskeletal filaments, the motor exhibits distinct states of motility: active motion along the filaments, and pause phase in which it remains stationary for a finite time interval. The transition probabilities between motion and pause phases are asymmetric in general, and considerably affected by changes in environmental conditions which influences the efficiency of cargo delivery to specific targets. By considering the motion of individual non-interacting molecular motors on a single filament as well as a dynamic filamentous network, we present an analytical model for the dynamics of self-propelled particles which undergo frequent pause phases. The interplay between motor processivity, structural properties of filamentous network, and transition probabilities between the two states of motility drastically changes the dynamics: multiple transitions between different types of anomalous diffusive dynamics occur and the crossover time to the asymptotic diffusive or ballistic motion varies by several orders of magnitude. We map out the phase diagrams in the space of transition probabilities, and address the role of initial conditions of motion on the resulting dynamics.
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Affiliation(s)
- Anne E. Hafner
- Department of Theoretical Physics, Saarland University, 66041 Saarbrücken, Germany
| | - Ludger Santen
- Department of Theoretical Physics, Saarland University, 66041 Saarbrücken, Germany
| | - Heiko Rieger
- Department of Theoretical Physics, Saarland University, 66041 Saarbrücken, Germany
| | - M. Reza Shaebani
- Department of Theoretical Physics, Saarland University, 66041 Saarbrücken, Germany
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