151
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Overexpression of endophilin A1 exacerbates synaptic alterations in a mouse model of Alzheimer's disease. Nat Commun 2018; 9:2968. [PMID: 30061577 PMCID: PMC6065365 DOI: 10.1038/s41467-018-04389-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 04/27/2018] [Indexed: 02/05/2023] Open
Abstract
Endophilin A1 (EP) is a protein enriched in synaptic terminals that has been linked to Alzheimer's disease (AD). Previous in vitro studies have shown that EP can bind to a variety of proteins, which elicit changes in synaptic transmission of neurotransmitters and spine formation. Additionally, we previously showed that EP protein levels are elevated in AD patients and AD transgenic animal models. Here, we establish the in vivo consequences of upregulation of EP expression in amyloid-β peptide (Aβ)-rich environments, leading to changes in both long-term potentiation and learning and memory of transgenic animals. Specifically, increasing EP augmented cerebral Aβ accumulation. EP-mediated signal transduction via reactive oxygen species (ROS)/p38 mitogen-activated protein (MAP) kinase contributes to Aβ-induced mitochondrial dysfunction, synaptic injury, and cognitive decline, which could be rescued by blocking either ROS or p38 MAP kinase activity.
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152
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le Feber J, Dummer A, Hassink GC, van Putten MJAM, Hofmeijer J. Evolution of Excitation-Inhibition Ratio in Cortical Cultures Exposed to Hypoxia. Front Cell Neurosci 2018; 12:183. [PMID: 30018536 PMCID: PMC6037832 DOI: 10.3389/fncel.2018.00183] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/11/2018] [Indexed: 11/24/2022] Open
Abstract
In the core of a brain infarct, neuronal death occurs within minutes after loss of perfusion. In the penumbra, a surrounding area with some residual perfusion, neurons initially remain structurally intact, but hypoxia-induced synaptic failure impedes neuronal activity. Penumbral activity may recover or further deteriorate, reflecting cell death. Mechanisms leading to either outcome remain ill-understood, but may involve changes in the excitation to inhibition (E/I) ratio. The E/I ratio is determined by structural (relative densities of excitatory and inhibitory synapses) and functional factors (synaptic strengths). Clinical studies demonstrated excitability alterations in regions surrounding the infarct core. These may be related to structural E/I changes, but the effects of hypoxia /ischemia on structural connectivity have not yet been investigated, and the role of structural connectivity changes in excitability alterations remains unclear. We investigated the evolution of the structural E/I ratio and associated network excitability in cortical cultures exposed to severe hypoxia of varying duration. 6–12 h of hypoxia reduced the total synaptic density. In particular, the inhibitory synaptic density dropped significantly, resulting in an elevated E/I ratio. Initially, this does not lead to increased excitability due to hypoxia-induced synaptic failure. Increased excitability becomes apparent upon reoxygenation after 6 or 12 h, but not after 24 h. After 24 h of hypoxia, structural patterns of vesicular glutamate stainings change. This possibly reflects disassembly of excitatory synapses, and may account for the irreversible reduction of activity and stimulus responses seen after 24 h.
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Affiliation(s)
- Joost le Feber
- Clinical Neurophysiology, TechMed Centre, University of Twente, Enschede, Netherlands
| | - Anneloes Dummer
- Clinical Neurophysiology, TechMed Centre, University of Twente, Enschede, Netherlands
| | - Gerco C Hassink
- Clinical Neurophysiology, TechMed Centre, University of Twente, Enschede, Netherlands.,Biomedical Signals and Systems, TechMed Centre, University of Twente, Enschede, Netherlands
| | - Michel J A M van Putten
- Clinical Neurophysiology, TechMed Centre, University of Twente, Enschede, Netherlands.,Department of Clinical Neurophysiology, Medisch Spectrum Twente, Enschede, Netherlands
| | - Jeannette Hofmeijer
- Clinical Neurophysiology, TechMed Centre, University of Twente, Enschede, Netherlands.,Department of Neurology, Rijnstate Hospital, Arnhem, Netherlands
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153
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Watts ME, Pocock R, Claudianos C. Brain Energy and Oxygen Metabolism: Emerging Role in Normal Function and Disease. Front Mol Neurosci 2018; 11:216. [PMID: 29988368 PMCID: PMC6023993 DOI: 10.3389/fnmol.2018.00216] [Citation(s) in RCA: 202] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 06/01/2018] [Indexed: 01/09/2023] Open
Abstract
Dynamic metabolic changes occurring in neurons are critically important in directing brain plasticity and cognitive function. In other tissue types, disruptions to metabolism and the resultant changes in cellular oxidative state, such as increased reactive oxygen species (ROS) or induction of hypoxia, are associated with cellular stress. In the brain however, where drastic metabolic shifts occur to support physiological processes, subsequent changes to cellular oxidative state and induction of transcriptional sensors of oxidative stress likely play a significant role in regulating physiological neuronal function. Understanding the role of metabolism and metabolically-regulated genes in neuronal function will be critical in elucidating how cognitive functions are disrupted in pathological conditions where neuronal metabolism is affected. Here, we discuss known mechanisms regulating neuronal metabolism as well as the role of hypoxia and oxidative stress during normal and disrupted neuronal function. We also summarize recent studies implicating a role for metabolism in regulating neuronal plasticity as an emerging neuroscience paradigm.
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Affiliation(s)
- Michelle E Watts
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD, Australia
| | - Roger Pocock
- Development and Stem Cells Program, Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Charles Claudianos
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD, Australia.,Centre for Mental Health Research, The Australian National University, Canberra, ACT, Australia
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154
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Vdac1 Downregulation Causes Mitochondrial Disintegration Leading to Hippocampal Neurodegeneration in Scopolamine-Induced Amnesic Mice. Mol Neurobiol 2018; 56:1707-1718. [PMID: 29916145 DOI: 10.1007/s12035-018-1164-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/30/2018] [Indexed: 01/16/2023]
Abstract
Our previous report on hippocampal proteome analysis suggested the involvement of voltage-dependent anion channel (Vdac) 1 in scopolamine-induced amnesia. Further silencing of Vdac1 in young mice reduced the recognition memory. Vdac1 is a porin protein present abundantly on outer mitochondrial membrane. It acts as a transporter of energy metabolites ATP/ADP and Ca2+ ions and helps in communication between mitochondrial matrix and cytosol. As Vdac1-associated energy metabolism may be affected during amnesia, we determined the downstream function of Vdac1 in the present study. The expression of Vdac1 and total ATP level was decreased in the hippocampus of scopolamine-induced amnesic mice. Also, the mitochondrial membrane potential, cristae organization, and morphology were disrupted leading to increased ROS generation and reduced SOD and catalase activity. On the other hand, there was increase in the expression of pro-apoptotic marker proteins (Bax, Bad, Casp 3), leading to rising degenerated neuronal cells in the dentate gyrus and Cornu ammonis 3 and 1 subregions of the hippocampus during amnesia. Further, to check whether Vdac1 downregulation is associated with neurodegeneration, we infused Vdac1 siRNA stereotaxically in the hippocampus of normal young mice. As compared to control, Vdac1 silencing decreased ATP level and mitochondrial membrane potential leading to increase in the number of degenerated neuronal cells in subregions of the hippocampus. Taken together, our study shows that downregulation of Vdac1 causes neurodegeneration through mitochondrial disintegration in the hippocampus of scopolamine-induced amnesic mice.
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155
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Nesterov SV, Skorobogatova YA, Panteleeva AA, Pavlik LL, Mikheeva IB, Yaguzhinsky LS, Nartsissov YR. NMDA and GABA receptor presence in rat heart mitochondria. Chem Biol Interact 2018; 291:40-46. [PMID: 29883723 DOI: 10.1016/j.cbi.2018.06.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/30/2018] [Accepted: 06/05/2018] [Indexed: 11/19/2022]
Abstract
The purpose of this study is to demonstrate the presence of three more receptors in mitochondria. Two N-methyl-d-aspartate receptor (NMDAR) subunits (NR1 and NR2B) are found by protein immunoblot and immunogold labeling in mitochondria fraction isolated from rat heart. These data allow supposing NMDAR presence and functioning in the inner mitochondrial membrane. There are no signs of receptor presence obtained in heart tissue lysate, that indicates the receptor localization exactly in mitochondria. The possible receptor functions discussed are its participation in calcium transport and in excitation-metabolism coupling. Besides, preliminary evidence is obtained of GABAA and GABAB receptors presence in heart mitochondria. One can surmise their role in metabolism regulation and their possible co-operation with NMDAR just as in the nervous system.
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Affiliation(s)
- Semen V Nesterov
- Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny, 141700, Russia.
| | - Yulia A Skorobogatova
- Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny, 141700, Russia.
| | - Alisa A Panteleeva
- Belozersky Research Institute for Physico Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
| | - Lyubov L Pavlik
- Institute of Theoretical and Experimental Biophisics Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| | - Irina B Mikheeva
- Institute of Theoretical and Experimental Biophisics Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| | - Lev S Yaguzhinsky
- Institute of Cytochemistry and Molecular Pharmacology, 6-th Radialnaya str. 24-14, Moscow, 115404, Russia; Belozersky Research Institute for Physico Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
| | - Yaroslav R Nartsissov
- Institute of Cytochemistry and Molecular Pharmacology, 6-th Radialnaya str. 24-14, Moscow, 115404, Russia.
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156
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Lee A, Hirabayashi Y, Kwon SK, Lewis TL, Polleux F. Emerging roles of mitochondria in synaptic transmission and neurodegeneration. CURRENT OPINION IN PHYSIOLOGY 2018; 3:82-93. [PMID: 30320242 PMCID: PMC6178220 DOI: 10.1016/j.cophys.2018.03.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mitochondria play numerous critical physiological functions in neurons including ATP production, Ca2+ regulation, lipid synthesis, ROS signaling, and the ability to trigger apoptosis. Recently developed technologies, including in vivo 2-photon imaging in awake behaving mice revealed that unlike in the peripheral nervous system (PNS), mitochondrial transport decreases strikingly along the axons of adult neurons of the central nervous system (CNS). Furthermore, the improvements of genetically-encoded biosensors have enabled precise monitoring of the spatial and temporal impact of mitochondria on Ca2+, ATP and ROS homeostasis in a compartment-specific manner. Here, we discuss recent findings that begin to unravel novel physiological and pathophysiological properties of neuronal mitochondria at synapses. We also suggest new directions in the exploration of mitochondrial function in synaptic transmission, plasticity and neurodegeneration.
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Affiliation(s)
- Annie Lee
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute
| | - Yusuke Hirabayashi
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute
| | - Seok-Kyu Kwon
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute
| | - Tommy L. Lewis
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute
| | - Franck Polleux
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
- Mortimer B. Zuckerman Mind Brain Behavior Institute
- Kavli Institute for Brain Science at Columbia University
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157
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Metabolic regulation of synaptic activity. Rev Neurosci 2018; 29:825-835. [DOI: 10.1515/revneuro-2017-0090] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/16/2018] [Indexed: 12/20/2022]
Abstract
Abstract
Brain tissue is bioenergetically expensive. In humans, it composes approximately 2% of body weight and accounts for approximately 20% of calorie consumption. The brain consumes energy mostly for ion and neurotransmitter transport, a process that occurs primarily in synapses. Therefore, synapses are expensive for any living creature who has brain. In many brain diseases, synapses are damaged earlier than neurons start dying. Synapses may be considered as vulnerable sites on a neuron. Ischemic stroke, an acute disturbance of blood flow in the brain, is an example of a metabolic disease that affects synapses. The associated excessive glutamate release, called excitotoxicity, is involved in neuronal death in brain ischemia. Another example of a metabolic disease is hypoglycemia, a complication of diabetes mellitus, which leads to neuronal death and brain dysfunction. However, synapse function can be corrected with “bioenergetic medicine”. In this review, a ketogenic diet is discussed as a curative option. In support of a ketogenic diet, whereby carbohydrates are replaced for fats in daily meals, epileptic seizures can be terminated. In this review, we discuss possible metabolic sensors in synapses. These may include molecules that perceive changes in composition of extracellular space, for instance, ketone body and lactate receptors, or molecules reacting to changes in cytosol, for instance, KATP channels or AMP kinase. Inhibition of endocytosis is believed to be a universal synaptic mechanism of adaptation to metabolic changes.
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158
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Asaro RJ, Zhu Q, Lin K. Diffusion-advection within dynamic biological gaps driven by structural motion. Phys Rev E 2018; 97:042401. [PMID: 29758721 DOI: 10.1103/physreve.97.042401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Indexed: 11/07/2022]
Abstract
To study the significance of advection in the transport of solutes, or particles, within thin biological gaps (channels), we examine theoretically the process driven by stochastic fluid flow caused by random thermal structural motion, and we compare it with transport via diffusion. The model geometry chosen resembles the synaptic cleft; this choice is motivated by the cleft's readily modeled structure, which allows for well-defined mechanical and physical features that control the advection process. Our analysis defines a Péclet-like number, A^{D}, that quantifies the ratio of time scales of advection versus diffusion. Another parameter, A^{M}, is also defined by the analysis that quantifies the full potential extent of advection in the absence of diffusion. These parameters provide a clear and compact description of the interplay among the well-defined structural, geometric, and physical properties vis-a[over ̀]-vis the advection versus diffusion process. For example, it is found that A^{D}∼1/R^{2}, where R is the cleft diameter and hence diffusion distance. This curious, and perhaps unexpected, result follows from the dependence of structural motion that drives fluid flow on R. A^{M}, on the other hand, is directly related (essentially proportional to) the energetic input into structural motion, and thereby to fluid flow, as well as to the mechanical stiffness of the cleftlike structure. Our model analysis thus provides unambiguous insight into the prospect of competition of advection versus diffusion within biological gaplike structures. The importance of the random, versus a regular, nature of structural motion and of the resulting transient nature of advection under random motion is made clear in our analysis. Further, by quantifying the effects of geometric and physical properties on the competition between advection and diffusion, our results clearly demonstrate the important role that metabolic energy (ATP) plays in this competitive process.
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Affiliation(s)
- Robert J Asaro
- Department of Structural Engineering, University of California, San Diego, La Jolla, California 92093, USA
| | - Qiang Zhu
- Department of Structural Engineering, University of California, San Diego, La Jolla, California 92093, USA
| | - Kuanpo Lin
- Department of Structural Engineering, University of California, San Diego, La Jolla, California 92093, USA
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159
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Lucas SJ, Michel CB, Marra V, Smalley JL, Hennig MH, Graham BP, Forsythe ID. Glucose and lactate as metabolic constraints on presynaptic transmission at an excitatory synapse. J Physiol 2018; 596:1699-1721. [PMID: 29430661 PMCID: PMC5924824 DOI: 10.1113/jp275107] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 02/02/2018] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Synapses have high energy demands which increase during intense activity. We show that presynaptic terminals can utilise extracellular glucose or lactate to generate energy to maintain synaptic transmission. Reducing energy substrates induces a metabolic stress: presynaptic ATP depletion impaired synaptic transmission through a reduction in the number of functional synaptic vesicle release sites and a slowing of vesicle pool replenishment, without a consistent change in release probability. Metabolic function is compromised in many pathological conditions (e.g. stroke, traumatic brain injury and neurodegeneration). Knowledge of how synaptic transmission is constrained by metabolic stress, especially during intense brain activity, will provide insights to improve cognition following pathological insults. ABSTRACT The synapse has high energy demands, which increase during intense activity. Presynaptic ATP production depends on substrate availability and usage will increase during activity, which in turn could influence transmitter release and information transmission. We investigated transmitter release at the mouse calyx of Held synapse using glucose or lactate (10, 1 or 0 mm) as the extracellular substrates while inducing metabolic stress. High-frequency stimulation (HFS) and recovery paradigms evoked trains of EPSCs monitored under voltage-clamp. Whilst postsynaptic intracellular ATP was stabilised by diffusion from the patch pipette, depletion of glucose increased EPSC depression during HFS and impaired subsequent recovery. Computational modelling of these data demonstrated a reduction in the number of functional release sites and slowed vesicle pool replenishment during metabolic stress, with little change in release probability. Directly depleting presynaptic terminal ATP impaired transmitter release in an analogous manner to glucose depletion. In the absence of glucose, presynaptic terminal metabolism could utilise lactate from the aCSF and this was blocked by inhibition of monocarboxylate transporters (MCTs). MCT inhibitors significantly suppressed transmission in low glucose, implying that lactate is a presynaptic substrate. Additionally, block of glycogenolysis accelerated synaptic transmission failure in the absence of extracellular glucose, consistent with supplemental supply of lactate by local astrocytes. We conclude that both glucose and lactate support presynaptic metabolism and that limited availability, exacerbated by high-intensity firing, constrains presynaptic ATP, impeding transmission through a reduction in functional presynaptic release sites as vesicle recycling slows when ATP levels are low.
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Affiliation(s)
- Sarah J. Lucas
- Department of Neuroscience, Psychology & BehaviourUniversity of LeicesterLeicesterLE1 9HNUK
| | - Christophe B. Michel
- Computing Science & Mathematics, Faculty of Natural SciencesUniversity of StirlingStirlingFK9 4LAUK
| | - Vincenzo Marra
- Department of Neuroscience, Psychology & BehaviourUniversity of LeicesterLeicesterLE1 9HNUK
| | - Joshua L. Smalley
- Department of Neuroscience, Psychology & BehaviourUniversity of LeicesterLeicesterLE1 9HNUK
| | - Matthias H. Hennig
- Institute for Adaptive and Neural Computation, School of InformaticsUniversity of EdinburghEdinburghEH8 9ABUK
| | - Bruce P. Graham
- Computing Science & Mathematics, Faculty of Natural SciencesUniversity of StirlingStirlingFK9 4LAUK
| | - Ian D. Forsythe
- Department of Neuroscience, Psychology & BehaviourUniversity of LeicesterLeicesterLE1 9HNUK
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160
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Monday HR, Younts TJ, Castillo PE. Long-Term Plasticity of Neurotransmitter Release: Emerging Mechanisms and Contributions to Brain Function and Disease. Annu Rev Neurosci 2018; 41:299-322. [PMID: 29709205 DOI: 10.1146/annurev-neuro-080317-062155] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Long-lasting changes of brain function in response to experience rely on diverse forms of activity-dependent synaptic plasticity. Chief among them are long-term potentiation and long-term depression of neurotransmitter release, which are widely expressed by excitatory and inhibitory synapses throughout the central nervous system and can dynamically regulate information flow in neural circuits. This review article explores recent advances in presynaptic long-term plasticity mechanisms and contributions to circuit function. Growing evidence indicates that presynaptic plasticity may involve structural changes, presynaptic protein synthesis, and transsynaptic signaling. Presynaptic long-term plasticity can alter the short-term dynamics of neurotransmitter release, thereby contributing to circuit computations such as novelty detection, modifications of the excitatory/inhibitory balance, and sensory adaptation. In addition, presynaptic long-term plasticity underlies forms of learning and its dysregulation participates in several neuropsychiatric conditions, including schizophrenia, autism, intellectual disabilities, neurodegenerative diseases, and drug abuse.
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Affiliation(s)
- Hannah R Monday
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA;
| | - Thomas J Younts
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA;
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161
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Perouansky M, Hemmings HC. Bioblasts, anaesthesia, and power failure: rein in the excitement. Br J Anaesth 2018; 120:891-895. [PMID: 29661404 DOI: 10.1016/j.bja.2018.02.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 02/19/2018] [Indexed: 11/30/2022] Open
Affiliation(s)
- M Perouansky
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
| | - H C Hemmings
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
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162
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Robinson SW, Bourgognon JM, Spiers JG, Breda C, Campesan S, Butcher A, Mallucci GR, Dinsdale D, Morone N, Mistry R, Smith TM, Guerra-Martin M, Challiss RAJ, Giorgini F, Steinert JR. Nitric oxide-mediated posttranslational modifications control neurotransmitter release by modulating complexin farnesylation and enhancing its clamping ability. PLoS Biol 2018; 16:e2003611. [PMID: 29630591 PMCID: PMC5890968 DOI: 10.1371/journal.pbio.2003611] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 02/20/2018] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) regulates neuronal function and thus is critical for tuning neuronal communication. Mechanisms by which NO modulates protein function and interaction include posttranslational modifications (PTMs) such as S-nitrosylation. Importantly, cross signaling between S-nitrosylation and prenylation can have major regulatory potential. However, the exact protein targets and resulting changes in function remain elusive. Here, we interrogated the role of NO-dependent PTMs and farnesylation in synaptic transmission. We found that NO compromises synaptic function at the Drosophila neuromuscular junction (NMJ) in a cGMP-independent manner. NO suppressed release and reduced the size of available vesicle pools, which was reversed by glutathione (GSH) and occluded by genetic up-regulation of GSH-generating and de-nitrosylating glutamate-cysteine-ligase and S-nitroso-glutathione reductase activities. Enhanced nitrergic activity led to S-nitrosylation of the fusion-clamp protein complexin (cpx) and altered its membrane association and interactions with active zone (AZ) and soluble N-ethyl-maleimide-sensitive fusion protein Attachment Protein Receptor (SNARE) proteins. Furthermore, genetic and pharmacological suppression of farnesylation and a nitrosylation mimetic mutant of cpx induced identical physiological and localization phenotypes as caused by NO. Together, our data provide evidence for a novel physiological nitrergic molecular switch involving S-nitrosylation, which reversibly suppresses farnesylation and thereby enhances the net-clamping function of cpx. These data illustrate a new mechanistic signaling pathway by which regulation of farnesylation can fine-tune synaptic release.
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Affiliation(s)
- Susan W. Robinson
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - Jereme G. Spiers
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Carlo Breda
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Susanna Campesan
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Adrian Butcher
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Giovanna R. Mallucci
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - David Dinsdale
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Nobuhiro Morone
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Raj Mistry
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Tim M. Smith
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | - R. A. John Challiss
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Joern R. Steinert
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- * E-mail:
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163
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Ambient but not local lactate underlies neuronal tolerance to prolonged glucose deprivation. PLoS One 2018; 13:e0195520. [PMID: 29617444 PMCID: PMC5884621 DOI: 10.1371/journal.pone.0195520] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/23/2018] [Indexed: 11/19/2022] Open
Abstract
Neurons require a nearly constant supply of ATP. Glucose is the predominant source of brain ATP, but the direct effects of prolonged glucose deprivation on neuronal viability and function remain unclear. In sparse rat hippocampal microcultures, neurons were surprisingly resilient to 16 h glucose removal in the absence of secondary excitotoxicity. Neuronal survival and synaptic transmission were unaffected by prolonged removal of exogenous glucose. Inhibition of lactate transport decreased microculture neuronal survival during concurrent glucose deprivation, suggesting that endogenously released lactate is important for tolerance to glucose deprivation. Tandem depolarization and glucose deprivation also reduced neuronal survival, and trace glucose concentrations afforded neuroprotection. Mass cultures, in contrast to microcultures, were insensitive to depolarizing glucose deprivation, a difference attributable to increased extracellular lactate levels. Removal of local astrocyte support did not reduce survival in response to glucose deprivation or alter evoked excitatory transmission, suggesting that on-demand, local lactate shuttling is not necessary for neuronal tolerance to prolonged glucose removal. Taken together, these data suggest that endogenously produced lactate available globally in the extracellular milieu sustains neurons in the absence of glucose. A better understanding of resilience mechanisms in reduced preparations could lead to therapeutic strategies aimed to bolster these mechanisms in vulnerable neuronal populations.
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164
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Zimin PI, Woods CB, Kayser EB, Ramirez JM, Morgan PG, Sedensky MM. Isoflurane disrupts excitatory neurotransmitter dynamics via inhibition of mitochondrial complex I. Br J Anaesth 2018; 120:1019-1032. [PMID: 29661379 DOI: 10.1016/j.bja.2018.01.036] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 01/08/2018] [Accepted: 02/09/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The mechanisms of action of volatile anaesthetics are unclear. Volatile anaesthetics selectively inhibit complex I in the mitochondrial respiratory chain. Mice in which the mitochondrial complex I subunit NDUFS4 is knocked out [Ndufs4(KO)] either globally or in glutamatergic neurons are hypersensitive to volatile anaesthetics. The volatile anaesthetic isoflurane selectively decreases the frequency of spontaneous excitatory events in hippocampal slices from Ndufs4(KO) mice. METHODS Complex I inhibition by isoflurane was assessed with a Clark electrode. Synaptic function was measured by stimulating Schaffer collateral fibres and recording field potentials in the hippocampus CA1 region. RESULTS Isoflurane specifically inhibits complex I dependent respiration at lower concentrations in mitochondria from Ndufs4(KO) than from wild-type mice. In hippocampal slices, after high frequency stimulation to increase energetic demand, short-term synaptic potentiation is less in KO compared with wild-type mice. After high frequency stimulation, both Ndufs4(KO) and wild-type hippocampal slices exhibit striking synaptic depression in isoflurane at twice the 50% effective concentrations (EC50). The pattern of synaptic depression by isoflurane indicates a failure in synaptic vesicle recycling. Application of a selective A1 adenosine receptor antagonist partially eliminates isoflurane-induced short-term depression in both wild-type and Ndufs4(KO) slices, implicating an additional mitochondria-dependent effect on exocytosis. When mitochondria are the sole energy source, isoflurane completely eliminates synaptic output in both mutant and wild-type mice at twice the (EC50) for anaesthesia. CONCLUSIONS Volatile anaesthetics directly inhibit mitochondrial complex I as a primary target, limiting synaptic ATP production, and excitatory vesicle endocytosis and exocytosis.
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Affiliation(s)
- P I Zimin
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA.
| | - C B Woods
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - E B Kayser
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - J M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Neurological Surgery, University of Washington, Seattle, WA, USA
| | - P G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
| | - M M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
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165
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Endoplasmic reticulum and mitochondria in diseases of motor and sensory neurons: a broken relationship? Cell Death Dis 2018; 9:333. [PMID: 29491369 PMCID: PMC5832431 DOI: 10.1038/s41419-017-0125-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 09/25/2017] [Accepted: 10/10/2017] [Indexed: 12/13/2022]
Abstract
Recent progress in the understanding of neurodegenerative diseases revealed that multiple molecular mechanisms contribute to pathological changes in neurons. A large fraction of these alterations can be linked to dysfunction in the endoplasmic reticulum (ER) and mitochondria, affecting metabolism and secretion of lipids and proteins, calcium homeostasis, and energy production. Remarkably, these organelles are interacting with each other at specialized domains on the ER called mitochondria-associated membranes (MAMs). These membrane structures rely on the interaction of several complexes of proteins localized either at the mitochondria or at the ER interface and serve as an exchange platform of calcium, metabolites, and lipids, which are critical for the function of both organelles. In addition, recent evidence indicates that MAMs also play a role in the control of mitochondria dynamics and autophagy. MAMs thus start to emerge as a key element connecting many changes observed in neurodegenerative diseases. This review will focus on the role of MAMs in amyotrophic lateral sclerosis (ALS) and hereditary motor and sensory neuropathy, two neurodegenerative diseases particularly affecting neurons with long projecting axons. We will discuss how defects in MAM signaling may impair neuronal calcium homeostasis, mitochondrial dynamics, ER function, and autophagy, leading eventually to axonal degeneration. The possible impact of MAM dysfunction in glial cells, which may affect the capacity to support neurons and/or axons, will also be described. Finally, the possible role of MAMs as an interesting target for development of therapeutic interventions aiming at delaying or preventing neurodegeneration will be highlighted.
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166
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Age-related effects of X-ray irradiation on mouse hippocampus. Oncotarget 2018; 7:28040-58. [PMID: 27057631 PMCID: PMC5053708 DOI: 10.18632/oncotarget.8575] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 03/27/2016] [Indexed: 12/31/2022] Open
Abstract
Therapeutic irradiation of pediatric and adult patients can profoundly affect adult neurogenesis, and cognitive impairment manifests as a deficit in hippocampal-dependent functions. Age plays a major role in susceptibility to radiation, and younger children are at higher risk of cognitive decay when compared to adults. Cranial irradiation affects hippocampal neurogenesis by induction of DNA damage in neural progenitors, through the disruption of the neurogenic microenvironment, and defective integration of newborn neurons into the neuronal network. Our goal here was to assess cellular and molecular alterations induced by cranial X-ray exposure to low/moderate doses (0.1 and 2 Gy) in the hippocampus of mice irradiated at the postnatal ages of day 10 or week 10, as well as the dependency of these phenomena on age at irradiation. To this aim, changes in the cellular composition of the dentate gyrus, mitochondrial functionality, proteomic profile in the hippocampus, as well as cognitive performance were evaluated by a multidisciplinary approach. Our results suggest the induction of specific alterations in hippocampal neurogenesis, microvascular density and mitochondrial functions, depending on age at irradiation. A better understanding of how irradiation impairs hippocampal neurogenesis at low and moderate doses is crucial to minimize adverse effects of therapeutic irradiation, contributing also to radiation safety regulations.
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167
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Therapeutic Potential of Novel Twin Compounds Containing Tetramethylpyrazine and Carnitine Substructures in Experimental Ischemic Stroke. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:7191856. [PMID: 29387294 PMCID: PMC5745738 DOI: 10.1155/2017/7191856] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Revised: 07/16/2017] [Accepted: 08/13/2017] [Indexed: 02/07/2023]
Abstract
Although studies have seen dramatic advances in the understanding of the pathogenesis of stroke such as oxidative stress, inflammation, excitotoxicity, calcium overload and apoptosis, the delivery of stroke therapies is still a great challenge. In this study, we designed and synthesized a series of novel twin compounds containing tetramethylpyrazine and carnitine substructures and explored their therapeutic potential and mechanism in stroke-related neuronal injury. We first screened the neuroprotective effects of candidate compounds and found that among the tested compounds, LR134 and LR143 exhibited significant neuroprotection as evidenced by reducing cerebral infarct and edema, improving neurological function as well as blood-brain barrier integrity in rats after cerebral ischemia/reperfusion injury. We further demonstrated that the neuroprotective effects of compounds LR134 and LR143 were associated with the reduced inflammatory responses and NADPH oxidase- (NOX2-) mediated oxidative stress and the protection of mitochondria accompanied by the improvement of energy supply. In summary, this study provides direct evidence showing that the novel twin compounds containing tetramethylpyrazine and carnitine substructures have neuroprotective effects with multiple therapeutic targets, suggesting that modulation of these chemical structures may be an innovative therapeutic strategy for treating patients with stroke.
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168
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Regional knockdown of NDUFS4 implicates a thalamocortical circuit mediating anesthetic sensitivity. PLoS One 2017; 12:e0188087. [PMID: 29136012 PMCID: PMC5685608 DOI: 10.1371/journal.pone.0188087] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 10/31/2017] [Indexed: 12/28/2022] Open
Abstract
Knockout of the mitochondrial complex I protein, NDUFS4, profoundly increases sensitivity of mice to volatile anesthetics. In mice carrying an Ndufs4lox/lox gene, adeno-associated virus expressing Cre recombinase was injected into regions of the brain postulated to affect sensitivity to volatile anesthetics. These injections generated otherwise phenotypically wild type mice with region-specific, postnatal inactivation of Ndufs4, minimizing developmental effects of gene loss. Sensitivities to the volatile anesthetics isoflurane and halothane were measured using loss of righting reflex (LORR) and movement in response to tail clamp (TC) as endpoints. Knockdown (KD) of Ndufs4 in the vestibular nucleus produced resistance to both anesthetics for movement in response to TC. Ndufs4 loss in the central and dorsal medial thalami and in the parietal association cortex increased anesthetic sensitivity to both TC and LORR. Knockdown of Ndufs4 only in the parietal association cortex produced striking hypersensitivity for both endpoints, and accounted for half the total change seen in the global KO (Ndufs4(KO)). Excitatory synaptic transmission in the parietal association cortex in slices from Ndufs4(KO) animals was hypersensitive to isoflurane compared to control slices. We identified a direct neural circuit between the parietal association cortex and the central thalamus, consistent with a model in which isoflurane sensitivity is mediated by a thalamic signal relayed through excitatory synapses to the parietal association cortex. We postulate that the thalamocortical circuit is crucial for maintenance of consciousness and is disrupted by the inhibitory effects of isoflurane/halothane on mitochondria.
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169
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Silm K, Edwards RH. One Cycle Fuels Another: The Energetics of Neurotransmitter Release. Neuron 2017; 93:470-472. [PMID: 28182901 DOI: 10.1016/j.neuron.2017.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In this issue of Neuron, Ashrafi et al. (2017) show that activity induces translocation of the insulin-regulated glucose transporter GLUT4 to the plasma membrane, where it sustains the ATP production required for synaptic vesicle cycling. However, translocation occurs from presynaptic membranes other than synaptic vesicles and involves a distinct molecular mechanism.
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Affiliation(s)
- Katlin Silm
- Kavli Institute for Fundamental Neuroscience, UCSF Weill Institute for Neurosciences, University of California, San Francisco, 600 16th Street, GH-N272B, San Francisco, CA 94143, USA; Departments of Neurology and Physiology, UCSF School of Medicine, University of California, San Francisco, 600 16th Street, GH-N272B, San Francisco, CA 94143, USA
| | - Robert H Edwards
- Kavli Institute for Fundamental Neuroscience, UCSF Weill Institute for Neurosciences, University of California, San Francisco, 600 16th Street, GH-N272B, San Francisco, CA 94143, USA; Departments of Neurology and Physiology, UCSF School of Medicine, University of California, San Francisco, 600 16th Street, GH-N272B, San Francisco, CA 94143, USA.
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170
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Barber CN, Huganir RL, Raben DM. Phosphatidic acid-producing enzymes regulating the synaptic vesicle cycle: Role for PLD? Adv Biol Regul 2017; 67:141-147. [PMID: 28986032 DOI: 10.1016/j.jbior.2017.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/25/2017] [Accepted: 09/26/2017] [Indexed: 02/03/2023]
Abstract
In cortical and hippocampal neurons of the mammalian brain, the synaptic vesicle cycle is a series of steps that tightly regulate exo- and endocytosis of vesicles. Many proteins contribute to this regulation, but lipids have recently emerged as critical regulators as well. Of all the many lipid signaling molecules, phosphatidic acid is important to the physical processes of membrane fusion. Therefore, the lipid-metabolizing enzymes that produce phosphatidic acid are vital to the regulation of the cycle. Our lab is particularly interested in the potential regulatory mechanisms and neuronal roles of two phosphatidic acid-producing enzymes: diacylglycerol kinase theta (DGKθ) and phospholipase D (PLD). We recently discovered a regulatory role of DGKθ on evoked endocytosis (Goldschmidt et al., 2016). In addition to this enzyme, studies implicate PLD1 in neurotransmission, although its precise role is of some debate. Altogether, the production of phosphatidic acid by these enzymes offer an interesting and novel pathway for the regulation of the synaptic vesicle cycle.
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Affiliation(s)
- Casey N Barber
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA
| | - Richard L Huganir
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA
| | - Daniel M Raben
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725North Wolfe St, Baltimore, MD 21205, USA.
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171
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Kallenberger SM, Unger AL, Legewie S, Lymperopoulos K, Klingmüller U, Eils R, Herten DP. Correlated receptor transport processes buffer single-cell heterogeneity. PLoS Comput Biol 2017; 13:e1005779. [PMID: 28945754 PMCID: PMC5659801 DOI: 10.1371/journal.pcbi.1005779] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 10/27/2017] [Accepted: 09/19/2017] [Indexed: 11/25/2022] Open
Abstract
Cells typically vary in their response to extracellular ligands. Receptor transport processes modulate ligand-receptor induced signal transduction and impact the variability in cellular responses. Here, we quantitatively characterized cellular variability in erythropoietin receptor (EpoR) trafficking at the single-cell level based on live-cell imaging and mathematical modeling. Using ensembles of single-cell mathematical models reduced parameter uncertainties and showed that rapid EpoR turnover, transport of internalized EpoR back to the plasma membrane, and degradation of Epo-EpoR complexes were essential for receptor trafficking. EpoR trafficking dynamics in adherent H838 lung cancer cells closely resembled the dynamics previously characterized by mathematical modeling in suspension cells, indicating that dynamic properties of the EpoR system are widely conserved. Receptor transport processes differed by one order of magnitude between individual cells. However, the concentration of activated Epo-EpoR complexes was less variable due to the correlated kinetics of opposing transport processes acting as a buffering system. Cell surface receptors translate extracellular ligand concentrations to intracellular responses. Receptor transport between the plasma membrane and other cellular compartments regulates the number of accessible receptors at the plasma membrane that determines the strength of downstream pathway activation at a given ligand concentration. In cell populations, pathway activation strength and cellular responses vary between cells. Understanding origins of cell-to-cell variability is highly relevant for cancer research, motivated by the problem of fractional killing by chemotherapies and development of resistance in subpopulations of tumor cells. The erythropoietin receptor (EpoR) is a characteristic example of a receptor system that strongly depends on receptor transport processes. It is involved in several cellular processes, such as differentiation or proliferation, regulates the renewal of erythrocytes, and is expressed in several tumors. To investigate the involvement of receptor transport processes in cell-to-cell variability, we quantitatively characterized trafficking of EpoR in individual cells by combining live-cell imaging with mathematical modeling. Thereby, we found that EpoR dynamics was strongly dependent on rapid receptor transport and turnover. Interestingly, although transport processes largely differed between individual cells, receptor concentrations in cellular compartments were robust to variability in trafficking processes due to the correlated kinetics of opposing transport processes.
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Affiliation(s)
- Stefan M. Kallenberger
- Department for Bioinformatics and Functional Genomics, Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Institute for Pharmacy and Molecular Biotechnology (IPMB) and BioQuant, Heidelberg University, Heidelberg, Germany
| | - Anne L. Unger
- Cellnetworks Cluster and Institute of Physical Chemistry, BioQuant, Heidelberg University, Heidelberg, Germany
| | | | - Konstantinos Lymperopoulos
- Cellnetworks Cluster and Institute of Physical Chemistry, BioQuant, Heidelberg University, Heidelberg, Germany
| | - Ursula Klingmüller
- Division Systems Biology of Signal Transduction, DKFZ-ZMBH Alliance, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Translational Lung Research Center (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany
- * E-mail: (DPH); (RE); (UK)
| | - Roland Eils
- Department for Bioinformatics and Functional Genomics, Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Institute for Pharmacy and Molecular Biotechnology (IPMB) and BioQuant, Heidelberg University, Heidelberg, Germany
- * E-mail: (DPH); (RE); (UK)
| | - Dirk-Peter Herten
- Cellnetworks Cluster and Institute of Physical Chemistry, BioQuant, Heidelberg University, Heidelberg, Germany
- * E-mail: (DPH); (RE); (UK)
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172
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Yue HY, Bieberich E, Xu J. Promotion of endocytosis efficiency through an ATP-independent mechanism at rat calyx of Held terminals. J Physiol 2017; 595:5265-5284. [PMID: 28555839 DOI: 10.1113/jp274275] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 05/15/2017] [Indexed: 01/14/2023] Open
Abstract
KEY POINTS At rat calyx of Held terminals, ATP was required not only for slow endocytosis, but also for rapid phase of compensatory endocytosis. An ATP-independent form of endocytosis was recruited to accelerate membrane retrieval at increased activity and temperature. ATP-independent endocytosis primarily involved retrieval of pre-existing membrane, which depended on Ca2+ and the activity of neutral sphingomyelinase but not clathrin-coated pit maturation. ATP-independent endocytosis represents a non-canonical mechanism that can efficiently retrieve membrane at physiological conditions without competing for the limited ATP at elevated neuronal activity. ABSTRACT Neurotransmission relies on membrane endocytosis to maintain vesicle supply and membrane stability. Endocytosis has been generally recognized as a major ATP-dependent function, which efficiently retrieves more membrane at elevated neuronal activity when ATP consumption within nerve terminals increases drastically. This paradox raises the interesting question of whether increased activity recruits ATP-independent mechanism(s) to accelerate endocytosis at the same time as preserving ATP availability for other tasks. To address this issue, we studied ATP requirement in three typical forms of endocytosis at rat calyx of Held terminals by whole-cell membrane capacitance measurements. At room temperature, blocking ATP hydrolysis effectively abolished slow endocytosis and rapid endocytosis but only partially inhibited excess endocytosis following intense stimulation. The ATP-independent endocytosis occurred at calyces from postnatal days 8-15, suggesting its existence before and after hearing onset. This endocytosis was not affected by a reduction of exocytosis using the light chain of botulinum toxin C, nor by block of clathrin-coat maturation. It was abolished by EGTA, which preferentially blocked endocytosis of retrievable membrane pre-existing at the surface, and was impaired by oxidation of cholesterol and inhibition of neutral sphingomyelinase. ATP-independent endocytosis became more significant at 34-35°C, and recovered membrane by an amount that, on average, was close to exocytosis. The results of the present study suggest that activity and temperature recruit ATP-independent endocytosis of pre-existing membrane (in addition to ATP-dependent endocytosis) to efficiently retrieve membrane at nerve terminals. This less understood endocytosis represents a non-canonical mechanism regulated by lipids such as cholesterol and sphingomyelinase.
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Affiliation(s)
- Hai-Yuan Yue
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA
| | - Erhard Bieberich
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA
| | - Jianhua Xu
- Departments of Neuroscience and Regenerative Medicine, Augusta University, USA.,Department of Neurology, Medical College of Georgia, Augusta University, USA
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173
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Martí Y, Matthaeus F, Lau T, Schloss P. Methyl-4-phenylpyridinium (MPP+) differentially affects monoamine release and re-uptake in murine embryonic stem cell-derived dopaminergic and serotonergic neurons. Mol Cell Neurosci 2017; 83:37-45. [PMID: 28673772 DOI: 10.1016/j.mcn.2017.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 06/06/2017] [Accepted: 06/26/2017] [Indexed: 11/19/2022] Open
Abstract
1-Methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) is known to selectively damage dopaminergic (DA) cells in the substantia nigra and to produce symptoms which are alike to those observed in Parkinson's disease (PD). Based on the similarity between MPTP-induced neurotoxicity and PD-related neuropathology, application of MPTP or its metabolite methyl-4-phenylpyridinium (MPP+) was successfully established in experimental rodent models to study PD-related neurodegenerative events. MPP+ is taken up by the dopamine transporter (DAT) into DA neurons where it exerts its neurotoxic action on mitochondria by affecting complex I of the respiratory chain. MPP+ is also a high affinity substrate for the serotonin transporter (SERT), however little is known about possible toxic effects of MPP+ on serotonergic (5-HT) neurons. In order to compare cell type-specific effects of MPP+ treatment, we have differentiated mouse embryonic stem (ES) cells into DA and 5-HT neurons and studied the impact of MPP+ treatment on both types of monoaminergic neurons in vitro. MPP+ treatment impacts on mitochondrial membrane potential in DA as well as 5-HT ES cell-derived neurons. Although mitochondria metabolisms are similarly affected, synaptic vesicle cycling is only impaired in DA ES cell-derived neurons. Most importantly we show that MPP+ induces DAT externalization in DA neurons, but internalization of SERT in 5-HT neurons. This diverse MPP+-induced transporter trafficking is reflected by elevated substrate uptake in DA neurons, and diminished substrate uptake in 5-HT neurons. In summary, our experimental data point toward differential effects of MPP+ intoxication on neurotransmitter release and re-uptake in different types of monoaminergic neurons.
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Affiliation(s)
- Yasmina Martí
- Biochemical Laboratory, Dept. Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany; Hector Institute for Translational Brain Research, Central Institute for Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Friederike Matthaeus
- Biochemical Laboratory, Dept. Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Thorsten Lau
- Hector Institute for Translational Brain Research, Central Institute for Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany.
| | - Patrick Schloss
- Biochemical Laboratory, Dept. Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Germany
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174
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A molecular hypothesis to explain direct and inverse co-morbidities between Alzheimer's Disease, Glioblastoma and Lung cancer. Sci Rep 2017; 7:4474. [PMID: 28667284 PMCID: PMC5493619 DOI: 10.1038/s41598-017-04400-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 05/25/2017] [Indexed: 11/27/2022] Open
Abstract
Epidemiological studies indicate that patients suffering from Alzheimer’s disease have a lower risk of developing lung cancer, and suggest a higher risk of developing glioblastoma. Here we explore the molecular scenarios that might underlie direct and inverse co-morbidities between these diseases. Transcriptomic meta-analyses reveal significant numbers of genes with inverse patterns of expression in Alzheimer’s disease and lung cancer, and with similar patterns of expression in Alzheimer’s disease and glioblastoma. These observations support the existence of molecular substrates that could at least partially account for these direct and inverse co-morbidity relationships. A functional analysis of the sets of deregulated genes points to the immune system, up-regulated in both Alzheimer’s disease and glioblastoma, as a potential link between these two diseases. Mitochondrial metabolism is regulated oppositely in Alzheimer’s disease and lung cancer, indicating that it may be involved in the inverse co-morbidity between these diseases. Finally, oxidative phosphorylation is a good candidate to play a dual role by decreasing or increasing the risk of lung cancer and glioblastoma in Alzheimer’s disease.
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175
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Tao J, Bulgari D, Deitcher DL, Levitan ES. Limited distal organelles and synaptic function in extensive monoaminergic innervation. J Cell Sci 2017; 130:2520-2529. [PMID: 28600320 DOI: 10.1242/jcs.201111] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 06/05/2017] [Indexed: 12/20/2022] Open
Abstract
Organelles such as neuropeptide-containing dense-core vesicles (DCVs) and mitochondria travel down axons to supply synaptic boutons. DCV distribution among en passant boutons in small axonal arbors is mediated by circulation with bidirectional capture. However, it is not known how organelles are distributed in extensive arbors associated with mammalian dopamine neuron vulnerability, and with volume transmission and neuromodulation by monoamines and neuropeptides. Therefore, we studied presynaptic organelle distribution in Drosophila octopamine neurons that innervate ∼20 muscles with ∼1500 boutons. Unlike in smaller arbors, distal boutons in these arbors contain fewer DCVs and mitochondria, although active zones are present. Absence of vesicle circulation is evident by proximal nascent DCV delivery, limited impact of retrograde transport and older distal DCVs. Traffic studies show that DCV axonal transport and synaptic capture are not scaled for extensive innervation, thus limiting distal delivery. Activity-induced synaptic endocytosis and synaptic neuropeptide release are also reduced distally. We propose that limits in organelle transport and synaptic capture compromise distal synapse maintenance and function in extensive axonal arbors, thereby affecting development, plasticity and vulnerability to neurodegenerative disease.
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Affiliation(s)
- Juan Tao
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Dinara Bulgari
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - David L Deitcher
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Edwin S Levitan
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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176
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Sheng ZH. The Interplay of Axonal Energy Homeostasis and Mitochondrial Trafficking and Anchoring. Trends Cell Biol 2017; 27:403-416. [PMID: 28228333 PMCID: PMC5440189 DOI: 10.1016/j.tcb.2017.01.005] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/15/2017] [Accepted: 01/20/2017] [Indexed: 01/02/2023]
Abstract
Mitochondria are key cellular power plants essential for neuronal growth, survival, function, and regeneration after injury. Given their unique morphological features, neurons face exceptional challenges in maintaining energy homeostasis at distal synapses and growth cones where energy is in high demand. Efficient regulation of mitochondrial trafficking and anchoring is critical for neurons to meet altered energy requirements. Mitochondrial dysfunction and impaired transport have been implicated in several major neurological disorders. Thus, research into energy-mediated regulation of mitochondrial recruitment and redistribution is an important emerging frontier. In this review, I discuss new insights into the mechanisms regulating mitochondrial trafficking and anchoring, and provide an updated overview of how mitochondrial motility maintains energy homeostasis in axons, thus contributing to neuronal growth, regeneration, and synaptic function.
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Affiliation(s)
- Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA.
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177
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Fedorovich SV, Waseem TV, Puchkova LV. Biogenetic and morphofunctional heterogeneity of mitochondria: the case of synaptic mitochondria. Rev Neurosci 2017; 28:363-373. [DOI: 10.1515/revneuro-2016-0077] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 12/29/2016] [Indexed: 12/26/2022]
Abstract
AbstractThe mitochondria of different cells are different in their morphological and biochemical properties. These organelles generate free radicals during activity, leading inevitably to mitochondrial DNA damage. It is not clear how this problem is addressed in long-lived cells, such as neurons. We propose the hypothesis that mitochondria within the same cell also differ in lifespan and ability to divide. According to our suggestion, cells have a pool of ‘stem’ mitochondria with low metabolic activity and a pool of ‘differentiated’ mitochondria with significantly shorter lifespans and high metabolic activity. We consider synaptic mitochondria as a possible example of ‘differentiated’ mitochondria. They are significantly smaller than mitochondria from the cell body, and they are different in key enzyme activity levels, proteome, and lipidome. Synaptic mitochondria are more sensitive to different damaging factors. It has been established that neurons have a sorting mechanism that sends mitochondria with high membrane potential to presynaptic endings. This review describes the properties of synaptic mitochondria and their role in the regulation of synaptic transmission.
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Affiliation(s)
- Sergei V. Fedorovich
- Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk 220072, Belarus
| | - Tatyana V. Waseem
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Ludmila V. Puchkova
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya str., 29, St. Petersburg 195251, Russia
- ITMO University, Kronverksky av., 49, St.Petersburg 197101, Russia
- Institute of Experimental Medicine, Pavlova str., 12, St.Petersburg 197376, Russia
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178
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Orr AL, Rutaganira FU, de Roulet D, Huang EJ, Hertz NT, Shokat KM, Nakamura K. Long-term oral kinetin does not protect against α-synuclein-induced neurodegeneration in rodent models of Parkinson's disease. Neurochem Int 2017; 109:106-116. [PMID: 28434973 DOI: 10.1016/j.neuint.2017.04.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 03/20/2017] [Accepted: 04/11/2017] [Indexed: 12/21/2022]
Abstract
Mutations in the mitochondrial kinase PTEN-induced putative kinase 1 (PINK1) cause Parkinson's disease (PD), likely by disrupting PINK1's kinase activity. Although the mechanism(s) underlying how this loss of activity causes degeneration remains unclear, increasing PINK1 activity may therapeutically benefit some forms of PD. However, we must first learn whether restoring PINK1 function prevents degeneration in patients harboring PINK1 mutations, or whether boosting PINK1 function can offer protection in more common causes of PD. To test these hypotheses in preclinical rodent models of PD, we used kinetin triphosphate, a small-molecule that activates both wild-type and mutant forms of PINK1, which affects mitochondrial function and protects neural cells in culture. We chronically fed kinetin, the precursor of kinetin triphosphate, to PINK1-null rats in which PINK1 was reintroduced into their midbrain, and also to rodent models overexpressing α-synuclein. The highest tolerated dose of oral kinetin increased brain levels of kinetin for up to 6 months, without adversely affecting the survival of nigrostriatal dopamine neurons. However, there was no degeneration of midbrain dopamine neurons lacking PINK1, which precluded an assessment of neuroprotection and raised questions about the robustness of the PINK1 KO rat model of PD. In two rodent models of α-synuclein-induced toxicity, boosting PINK1 activity with oral kinetin provided no protective effects. Our results suggest that oral kinetin is unlikely to protect against α-synuclein toxicity, and thus fail to provide evidence that kinetin will protect in sporadic models of PD. Kinetin may protect in cases of PINK1 deficiency, but this possibility requires a more robust PINK1 KO model that can be validated by proof-of-principle genetic correction in adult animals.
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Affiliation(s)
- Adam L Orr
- Gladstone Institute of Neurological Disease, Gladstone Institutes, San Francisco, CA, USA
| | - Florentine U Rutaganira
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | | | - Eric J Huang
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
| | | | - Kevan M Shokat
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA; Mitokinin LLC, 2 Wall Street, 4th Floor, New York, NY, USA
| | - Ken Nakamura
- Gladstone Institute of Neurological Disease, Gladstone Institutes, San Francisco, CA, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA, USA.
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179
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Trevisiol A, Saab AS, Winkler U, Marx G, Imamura H, Möbius W, Kusch K, Nave KA, Hirrlinger J. Monitoring ATP dynamics in electrically active white matter tracts. eLife 2017; 6. [PMID: 28414271 PMCID: PMC5415357 DOI: 10.7554/elife.24241] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 04/16/2017] [Indexed: 11/24/2022] Open
Abstract
In several neurodegenerative diseases and myelin disorders, the degeneration profiles of myelinated axons are compatible with underlying energy deficits. However, it is presently impossible to measure selectively axonal ATP levels in the electrically active nervous system. We combined transgenic expression of an ATP-sensor in neurons of mice with confocal FRET imaging and electrophysiological recordings of acutely isolated optic nerves. This allowed us to monitor dynamic changes and activity-dependent axonal ATP homeostasis at the cellular level and in real time. We find that changes in ATP levels correlate well with compound action potentials. However, this correlation is disrupted when metabolism of lactate is inhibited, suggesting that axonal glycolysis products are not sufficient to maintain mitochondrial energy metabolism of electrically active axons. The combined monitoring of cellular ATP and electrical activity is a novel tool to study neuronal and glial energy metabolism in normal physiology and in models of neurodegenerative disorders. DOI:http://dx.doi.org/10.7554/eLife.24241.001 The brain contains an intricate network of nerve cells that receive, process, send and store information. This information travels as electrical impulses along a long, thin part of each nerve cell known as the nerve fiber or axon. The act of sending these electrical signals requires a lot of energy, and energy in cells is most often stored within molecules of adenosine triphosphate (called ATP for short). Importantly, a better understanding of how the production and consumption of ATP in nerve cells relates to electrical activity would help scientists to better understand how a shortage of energy in the brain contributes to diseases like multiple sclerosis. However, to date, it has been challenging to study the dynamics of ATP in nerve cells that are active. Now, Trevisiol et al. describe a new system that allows changes in ATP levels to be seen within active nerve cells. First, mice were genetically engineered to produce a molecule that works like an ATP sensor only in their nerve cells. This made it possible to visualize the amount of ATP inside the axons in real-time using a microscope. Measuring ATP levels and recording the electrical signals moving along an axon at the same time allowed Trevisiol et al. to see how ATP content and electrical activity correlate and regulate each other. The experiments reveal that strong electrical activity reduces the ATP content of the axon. Trevisiol et al. also discovered that nerve cells are unable to generate enough energy on their own to sustain their electrical activity. These results provide evidence that other cells in the brain – most likely non-nerve cells called oligodendrocytes – play an active role in delivering energy-rich substances to the axons of nerve cells. In the future, the same tools and approaches could be used to monitor ATP levels and electrical activity in mice that model neurological disorders. Such experiments could tell scientists more about how disturbing energy production in nerve cells affects these diseases. DOI:http://dx.doi.org/10.7554/eLife.24241.002
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Affiliation(s)
- Andrea Trevisiol
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
| | - Aiman S Saab
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany.,Institute of Pharmacology & Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland
| | - Ulrike Winkler
- Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Grit Marx
- Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Hiromi Imamura
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Wiebke Möbius
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany.,Center Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany
| | - Kathrin Kusch
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
| | - Johannes Hirrlinger
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany.,Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
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180
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Rangaraju V, Tom Dieck S, Schuman EM. Local translation in neuronal compartments: how local is local? EMBO Rep 2017; 18:693-711. [PMID: 28404606 DOI: 10.15252/embr.201744045] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/15/2017] [Accepted: 03/15/2017] [Indexed: 12/18/2022] Open
Abstract
Efficient neuronal function depends on the continued modulation of the local neuronal proteome. Local protein synthesis plays a central role in tuning the neuronal proteome at specific neuronal regions. Various aspects of translation such as the localization of translational machinery, spatial spread of the newly translated proteins, and their site of action are carried out in specialized neuronal subcompartments to result in a localized functional outcome. In this review, we focus on the various aspects of these local translation compartments such as size, biochemical and organelle composition, structural boundaries, and temporal dynamics. We also discuss the apparent absence of definitive components of translation in these local compartments and the emerging state-of-the-art tools that could help dissecting these conundrums in greater detail in the future.
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Affiliation(s)
- Vidhya Rangaraju
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | | | - Erin M Schuman
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
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181
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Tsuyama T, Tsubouchi A, Usui T, Imamura H, Uemura T. Mitochondrial dysfunction induces dendritic loss via eIF2α phosphorylation. J Cell Biol 2017; 216:815-834. [PMID: 28209644 PMCID: PMC5346966 DOI: 10.1083/jcb.201604065] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 11/30/2016] [Accepted: 01/19/2017] [Indexed: 12/25/2022] Open
Abstract
Mitochondria are key contributors to the etiology of diseases associated with neuromuscular defects or neurodegeneration. How changes in cellular metabolism specifically impact neuronal intracellular processes and cause neuropathological events is still unclear. We here dissect the molecular mechanism by which mitochondrial dysfunction induced by Prel aberrant function mediates selective dendritic loss in Drosophila melanogaster class IV dendritic arborization neurons. Using in vivo ATP imaging, we found that neuronal cellular ATP levels during development are not correlated with the progression of dendritic loss. We searched for mitochondrial stress signaling pathways that induce dendritic loss and found that mitochondrial dysfunction is associated with increased eIF2α phosphorylation, which is sufficient to induce dendritic pathology in class IV arborization neurons. We also observed that eIF2α phosphorylation mediates dendritic loss when mitochondrial dysfunction results from other genetic perturbations. Furthermore, mitochondrial dysfunction induces translation repression in class IV neurons in an eIF2α phosphorylation-dependent manner, suggesting that differential translation attenuation among neuron subtypes is a determinant of preferential vulnerability.
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Affiliation(s)
- Taiichi Tsuyama
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Asako Tsubouchi
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Tadao Usui
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Hiromi Imamura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Tadashi Uemura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
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182
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Worsening of memory deficit induced by energy-dense diet in a rat model of early-Alzheimer's disease is associated to neurotoxic Aβ species and independent of neuroinflammation. Biochim Biophys Acta Mol Basis Dis 2017; 1863:731-743. [DOI: 10.1016/j.bbadis.2016.12.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 12/07/2016] [Accepted: 12/23/2016] [Indexed: 01/20/2023]
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183
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Pathak D, Berthet A, Bendor JT, Yu K, Sellnow RC, Orr AL, Nguyen MK, Edwards RH, Manfredsson FP, Nakamura K. Loss of α-Synuclein Does Not Affect Mitochondrial Bioenergetics in Rodent Neurons. eNeuro 2017; 4:ENEURO.0216-16.2017. [PMID: 28462393 PMCID: PMC5409983 DOI: 10.1523/eneuro.0216-16.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 04/02/2017] [Accepted: 04/06/2017] [Indexed: 12/28/2022] Open
Abstract
Increased α-synuclein (αsyn) and mitochondrial dysfunction play central roles in the pathogenesis of Parkinson's disease (PD), and lowering αsyn is under intensive investigation as a therapeutic strategy for PD. Increased αsyn levels disrupt mitochondria and impair respiration, while reduced αsyn protects against mitochondrial toxins, suggesting that interactions between αsyn and mitochondria influences the pathologic and physiologic functions of αsyn. However, we do not know if αsyn affects normal mitochondrial function or if lowering αsyn levels impacts bioenergetic function, especially at the nerve terminal where αsyn is enriched. To determine if αsyn is required for normal mitochondrial function in neurons, we comprehensively evaluated how lowering αsyn affects mitochondrial function. We found that αsyn knockout (KO) does not affect the respiration of cultured hippocampal neurons or cortical and dopaminergic synaptosomes, and that neither loss of αsyn nor all three (α, β and γ) syn isoforms decreased mitochondria-derived ATP levels at the synapse. Similarly, neither αsyn KO nor knockdown altered the capacity of synaptic mitochondria to meet the energy requirements of synaptic vesicle cycling or influenced the localization of mitochondria to dopamine (DA) synapses in vivo. Finally, αsyn KO did not affect overall energy metabolism in mice assessed with a Comprehensive Lab Animal Monitoring System. These studies suggest either that αsyn has little or no significant physiological effect on mitochondrial bioenergetic function, or that any such functions are fully compensated for when lost. These results implicate that αsyn levels can be reduced in neurons without impairing (or improving) mitochondrial bioenergetics or distribution.
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Affiliation(s)
- Divya Pathak
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158
| | - Amandine Berthet
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158
| | - Jacob T. Bendor
- Department of Neurology and Graduate Programs in Neuroscience and Biomedical Sciences, University of California, San Francisco, San Francisco, California 94158
| | - Katharine Yu
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158
| | - Rhyomi C. Sellnow
- Department of Translational Science & Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503
- Mercy Health Hauenstein Neuroscience Center, Grand Rapids, MI 49503
| | - Adam L. Orr
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158
| | - Mai K Nguyen
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158
| | - Robert H. Edwards
- Department of Neurology and Graduate Programs in Neuroscience and Biomedical Sciences, University of California, San Francisco, San Francisco, California 94158
| | - Fredric P. Manfredsson
- Department of Translational Science & Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503
- Mercy Health Hauenstein Neuroscience Center, Grand Rapids, MI 49503
| | - Ken Nakamura
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158
- Department of Neurology and Graduate Programs in Neuroscience and Biomedical Sciences, University of California, San Francisco, San Francisco, California 94158
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184
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Fedorovich S, Hofmeijer J, van Putten MJAM, le Feber J. Reduced Synaptic Vesicle Recycling during Hypoxia in Cultured Cortical Neurons. Front Cell Neurosci 2017; 11:32. [PMID: 28261063 PMCID: PMC5311063 DOI: 10.3389/fncel.2017.00032] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/01/2017] [Indexed: 01/08/2023] Open
Abstract
Improvement of neuronal recovery in the ischemic penumbra, an area around the core of a brain infarct with some remaining perfusion, has a large potential for the development of therapy against acute ischemic stroke. However, mechanisms that lead to either recovery or secondary damage in the penumbra largely remain unclear. Recent studies in cultured networks of cortical neurons showed that failure of synaptic transmission (referred to as synaptic failure) is a critical factor in the penumbral area, but the mechanisms that lead to synaptic failure are still under investigation. Here we used a Styryl dye, FM1-43, to quantify endocytosis and exocytosis in cultures of rat cortical neurons under normoxic and hypoxic conditions. Hypoxia in cultured cortical networks rapidly depressed endocytosis and, to a lesser extent, exocytosis. These findings support electrophysiological findings that synaptic failure occurs quickly after the induction of hypoxia, and confirms that the failing processes are at least in part presynaptic.
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Affiliation(s)
- Sergei Fedorovich
- Laboratory of Biophysics and Cellular Engineering, Institute of Biophysics and Cell Engineering, National Academy of Sciences of Belarus Minsk, Belarus
| | - Jeannette Hofmeijer
- Clinical Neurophysiology, University of TwenteEnschede, Netherlands; Department of Neurology, Rijnstate HospitalArnhem, Netherlands
| | - Michel J A M van Putten
- Clinical Neurophysiology, University of TwenteEnschede, Netherlands; Department of Neurology and Clinical Neurophysiology, Medisch Spectrum TwenteEnschede, Netherlands
| | - Joost le Feber
- Clinical Neurophysiology, University of Twente Enschede, Netherlands
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185
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Winkler U, Seim P, Enzbrenner Y, Köhler S, Sicker M, Hirrlinger J. Activity-dependent modulation of intracellular ATP in cultured cortical astrocytes. J Neurosci Res 2017; 95:2172-2181. [PMID: 28151554 DOI: 10.1002/jnr.24020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/15/2016] [Accepted: 12/21/2016] [Indexed: 01/21/2023]
Abstract
Brain function is absolutely dependent on an appropriate supply of energy. A shortfall in supply-as occurs, for instance, following stroke-can lead rapidly to irreversible damage to this vital organ. While the consequences of pathophysiological energy depletion have been well documented, much less is known about the physiological energy dynamics of brain cells, although changes in the intracellular concentration of adenosine triphosphate (ATP), the major energy carrier of cells, have been postulated to contribute to cellular signaling. To address this issue more closely, we have investigated intracellular ATP in cultured primary cortical astrocytes by time-lapse microscopy using a genetically encoded fluorescent sensor for ATP. The cytosolic ATP sensor signal decreased after application of the neurotransmitter glutamate in a manner dependent on both glutamate concentration and glutamate transporter activity, but independent of glutamate receptors. The application of dopamine did not affect ATP levels within astrocytes. These results confirm that intracellular ATP levels in astrocytes do indeed respond to changes in physiological activity and pave the way for further studies addressing factors that affect regulation of ATP. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Ulrike Winkler
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Pauline Seim
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Yvonne Enzbrenner
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Susanne Köhler
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Marit Sicker
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, Leipzig, Germany.,Department of Neurogenetics, Max Planck Institute for Experimental Medicine, Göttingen, Germany
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186
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Differential Presynaptic ATP Supply for Basal and High-Demand Transmission. J Neurosci 2017; 37:1888-1899. [PMID: 28093477 DOI: 10.1523/jneurosci.2712-16.2017] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 01/10/2017] [Accepted: 01/13/2017] [Indexed: 11/21/2022] Open
Abstract
The relative contributions of glycolysis and oxidative phosphorylation to neuronal presynaptic energy demands are unclear. In rat hippocampal neurons, ATP production by either glycolysis or oxidative phosphorylation alone sustained basal evoked synaptic transmission for up to 20 min. However, combined inhibition of both ATP sources abolished evoked transmission. Neither action potential propagation failure nor depressed Ca2+ influx explained loss of evoked synaptic transmission. Rather, inhibition of ATP synthesis caused massive spontaneous vesicle exocytosis, followed by arrested endocytosis, accounting for the disappearance of evoked postsynaptic currents. In contrast to its weak effects on basal transmission, inhibition of oxidative phosphorylation alone depressed recovery from vesicle depletion. Local astrocytic lactate shuttling was not required. Instead, either ambient monocarboxylates or neuronal glycolysis was sufficient to supply requisite substrate. In summary, basal transmission can be sustained by glycolysis, but strong presynaptic demands are met preferentially by oxidative phosphorylation, which can be maintained by bulk but not local monocarboxylates or by neuronal glycolysis.SIGNIFICANCE STATEMENT Neuronal energy levels are critical for proper CNS function, but the relative roles for the two main sources of ATP production, glycolysis and oxidative phosphorylation, in fueling presynaptic function in unclear. Either glycolysis or oxidative phosphorylation can fuel low-frequency synaptic function and inhibiting both underlies loss of synaptic transmission via massive vesicle release and subsequent failure to endocytose lost vesicles. Oxidative phosphorylation, fueled by either glycolysis or endogenously released monocarboxylates, can fuel more metabolically demanding tasks such as vesicle recovery after depletion. Our work demonstrates the flexible nature of fueling presynaptic function to maintain synaptic function.
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187
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Martino Adami PV, Quijano C, Magnani N, Galeano P, Evelson P, Cassina A, Do Carmo S, Leal MC, Castaño EM, Cuello AC, Morelli L. Synaptosomal bioenergetic defects are associated with cognitive impairment in a transgenic rat model of early Alzheimer's disease. J Cereb Blood Flow Metab 2017; 37:69-84. [PMID: 26661224 PMCID: PMC5363729 DOI: 10.1177/0271678x15615132] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 10/05/2015] [Accepted: 10/08/2015] [Indexed: 12/12/2022]
Abstract
Synaptic bioenergetic deficiencies may be associated with early Alzheimer's disease (AD). To explore this concept, we assessed pre-synaptic mitochondrial function in hemizygous (+/-)TgMcGill-R-Thy1-APP rats. The low burden of Aβ and the wide array of behavioral and cognitive impairments described in 6-month-old hemizygous TgMcGill-R-Thy1-APP rats (Tg(+/-)) support their use to investigate synaptic bioenergetics deficiencies described in subjects with early Alzheimer's disease (AD). In this report, we show that pre-synaptic mitochondria from Tg(+/-) rats evidence a decreased respiratory control ratio and spare respiratory capacity associated with deficits in complex I enzymatic activity. Cognitive impairments were prevented and bioenergetic deficits partially reversed when Tg(+/-) rats were fed a nutritionally complete diet from weaning to 6-month-old supplemented with pyrroloquinoline quinone, a mitochondrial biogenesis stimulator with antioxidant and neuroprotective effects. These results provide evidence that, as described in AD brain and not proven in Tg mice models with AD-like phenotype, the mitochondrial bioenergetic capacity of synaptosomes is not conserved in the Tg(+/-) rats. This animal model may be suitable for understanding the basic biochemical mechanisms involved in early AD.
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Affiliation(s)
- Pamela V Martino Adami
- Laboratory of Amyloidosis and Neurodegeneration, Fundación Instituto Leloir-IIBBA-CONICET, Buenos Aires, Argentina
| | - Celia Quijano
- Department of Biochemistry and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Natalia Magnani
- IBIMOL-UBA-CONICET, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pablo Galeano
- Laboratory of Amyloidosis and Neurodegeneration, Fundación Instituto Leloir-IIBBA-CONICET, Buenos Aires, Argentina.,ININCA- UBA-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pablo Evelson
- IBIMOL-UBA-CONICET, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Adriana Cassina
- Department of Biochemistry and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Sonia Do Carmo
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - María C Leal
- Laboratory of Protective and Regenerative Therapies of the CNS, Fundación Instituto Leloir-IIBBA-CONICET, Buenos Aires, Argentina
| | - Eduardo M Castaño
- Laboratory of Amyloidosis and Neurodegeneration, Fundación Instituto Leloir-IIBBA-CONICET, Buenos Aires, Argentina
| | - A Claudio Cuello
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Laura Morelli
- Laboratory of Amyloidosis and Neurodegeneration, Fundación Instituto Leloir-IIBBA-CONICET, Buenos Aires, Argentina
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188
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Vaccaro V, Devine MJ, Higgs NF, Kittler JT. Miro1-dependent mitochondrial positioning drives the rescaling of presynaptic Ca2+ signals during homeostatic plasticity. EMBO Rep 2016; 18:231-240. [PMID: 28039205 PMCID: PMC5286383 DOI: 10.15252/embr.201642710] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 11/16/2016] [Accepted: 11/28/2016] [Indexed: 11/27/2022] Open
Abstract
Mitochondrial trafficking is influenced by neuronal activity, but it remains unclear how mitochondrial positioning influences neuronal transmission and plasticity. Here, we use live cell imaging with the genetically encoded presynaptically targeted Ca2+ indicator, SyGCaMP5, to address whether presynaptic Ca2+ responses are altered by mitochondria in synaptic terminals. We find that presynaptic Ca2+ signals, as well as neurotransmitter release, are significantly decreased in terminals containing mitochondria. Moreover, the localisation of mitochondria at presynaptic sites can be altered during long‐term activity changes, dependent on the Ca2+‐sensing function of the mitochondrial trafficking protein, Miro1. In addition, we find that Miro1‐mediated activity‐dependent synaptic repositioning of mitochondria allows neurons to homeostatically alter the strength of presynaptic Ca2+ signals in response to prolonged changes in neuronal activity. Our results support a model in which mitochondria are recruited to presynaptic terminals during periods of raised neuronal activity and are involved in rescaling synaptic signals during homeostatic plasticity.
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Affiliation(s)
- Victoria Vaccaro
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Michael J Devine
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Nathalie F Higgs
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Josef T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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189
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Smith HL, Bourne JN, Cao G, Chirillo MA, Ostroff LE, Watson DJ, Harris KM. Mitochondrial support of persistent presynaptic vesicle mobilization with age-dependent synaptic growth after LTP. eLife 2016; 5. [PMID: 27991850 PMCID: PMC5235352 DOI: 10.7554/elife.15275] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 12/16/2016] [Indexed: 12/22/2022] Open
Abstract
Mitochondria support synaptic transmission through production of ATP, sequestration of calcium, synthesis of glutamate, and other vital functions. Surprisingly, less than 50% of hippocampal CA1 presynaptic boutons contain mitochondria, raising the question of whether synapses without mitochondria can sustain changes in efficacy. To address this question, we analyzed synapses from postnatal day 15 (P15) and adult rat hippocampus that had undergone theta-burst stimulation to produce long-term potentiation (TBS-LTP) and compared them to control or no stimulation. At 30 and 120 min after TBS-LTP, vesicles were decreased only in presynaptic boutons that contained mitochondria at P15, and vesicle decrement was greatest in adult boutons containing mitochondria. Presynaptic mitochondrial cristae were widened, suggesting a sustained energy demand. Thus, mitochondrial proximity reflected enhanced vesicle mobilization well after potentiation reached asymptote, in parallel with the apparently silent addition of new dendritic spines at P15 or the silent enlargement of synapses in adults. DOI:http://dx.doi.org/10.7554/eLife.15275.001
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Affiliation(s)
- Heather L Smith
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, United States
| | - Jennifer N Bourne
- Department of Cell and Developmental Biology, University of Colorado Denver - Anschutz Medical Campus, Aurora, United States
| | - Guan Cao
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, United States
| | - Michael A Chirillo
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, United States
| | - Linnaea E Ostroff
- Center for Neural Science, New York University, Washington, New York
| | - Deborah J Watson
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, United States
| | - Kristen M Harris
- Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, United States
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190
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Patergnani S, Fossati V, Bonora M, Giorgi C, Marchi S, Missiroli S, Rusielewicz T, Wieckowski MR, Pinton P. Mitochondria in Multiple Sclerosis: Molecular Mechanisms of Pathogenesis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 328:49-103. [PMID: 28069137 DOI: 10.1016/bs.ircmb.2016.08.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mitochondria, the organelles that function as the powerhouse of the cell, have been increasingly linked to the pathogenesis of many neurological disorders, including multiple sclerosis (MS). MS is a chronic inflammatory demyelinating disease of the central nervous system (CNS) and a leading cause of neurological disability in young adults in the western world. Its etiology remains unknown, and while the inflammatory component of MS has been heavily investigated and targeted for therapeutic intervention, the failure of remyelination and the process of axonal degeneration are still poorly understood. Recent studies suggest a role of mitochondrial dysfunction in the neurodegenerative aspects of MS. This review is focused on mitochondrial functions under physiological conditions and the consequences of mitochondrial alterations in various CNS disorders. Moreover, we summarize recent findings linking mitochondrial dysfunction to MS and discuss novel therapeutic strategies targeting mitochondria-related pathways as well as emerging experimental approaches for modeling mitochondrial disease.
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Affiliation(s)
- S Patergnani
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - V Fossati
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - M Bonora
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - C Giorgi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - S Marchi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - S Missiroli
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - T Rusielewicz
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - M R Wieckowski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - P Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy.
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191
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Lujan B, Kushmerick C, Banerjee TD, Dagda RK, Renden R. Glycolysis selectively shapes the presynaptic action potential waveform. J Neurophysiol 2016; 116:2523-2540. [PMID: 27605535 DOI: 10.1152/jn.00629.2016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/05/2016] [Indexed: 11/22/2022] Open
Abstract
Mitochondria are major suppliers of cellular energy in neurons; however, utilization of energy from glycolysis vs. mitochondrial oxidative phosphorylation (OxPhos) in the presynaptic compartment during neurotransmission is largely unknown. Using presynaptic and postsynaptic recordings from the mouse calyx of Held, we examined the effect of acute selective pharmacological inhibition of glycolysis or mitochondrial OxPhos on multiple mechanisms regulating presynaptic function. Inhibition of glycolysis via glucose depletion and iodoacetic acid (1 mM) treatment, but not mitochondrial OxPhos, rapidly altered transmission, resulting in highly variable, oscillating responses. At reduced temperature, this same treatment attenuated synaptic transmission because of a smaller and broader presynaptic action potential (AP) waveform. We show via experimental manipulation and ion channel modeling that the altered AP waveform results in smaller Ca2+ influx, resulting in attenuated excitatory postsynaptic currents (EPSCs). In contrast, inhibition of mitochondria-derived ATP production via extracellular pyruvate depletion and bath-applied oligomycin (1 μM) had no significant effect on Ca2+ influx and did not alter the AP waveform within the same time frame (up to 30 min), and the resultant EPSC remained unaffected. Glycolysis, but not mitochondrial OxPhos, is thus required to maintain basal synaptic transmission at the presynaptic terminal. We propose that glycolytic enzymes are closely apposed to ATP-dependent ion pumps on the presynaptic membrane. Our results indicate a novel mechanism for the effect of hypoglycemia on neurotransmission. Attenuated transmission likely results from a single presynaptic mechanism at reduced temperature: a slower, smaller AP, before and independent of any effect on synaptic vesicle release or receptor activity.
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Affiliation(s)
- Brendan Lujan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Christopher Kushmerick
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil; and
| | - Tania Das Banerjee
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Ruben K Dagda
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Robert Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada;
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192
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Zimin PI, Woods CB, Quintana A, Ramirez JM, Morgan PG, Sedensky MM. Glutamatergic Neurotransmission Links Sensitivity to Volatile Anesthetics with Mitochondrial Function. Curr Biol 2016; 26:2194-201. [PMID: 27498564 DOI: 10.1016/j.cub.2016.06.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/28/2016] [Accepted: 06/14/2016] [Indexed: 12/31/2022]
Abstract
An enigma of modern medicine has persisted for over 150 years. The mechanisms by which volatile anesthetics (VAs) produce their effects (loss of consciousness, analgesia, amnesia, and immobility) remain an unsolved mystery. Many attractive putative molecular targets have failed to produce a significant effect when genetically tested in whole-animal models [1-3]. However, mitochondrial defects increase VA sensitivity in diverse organisms from nematodes to humans [4-6]. Ndufs4 knockout (KO) mice lack a subunit of mitochondrial complex I and are strikingly hypersensitive to VAs yet resistant to the intravenous anesthetic ketamine [7]. The change in VA sensitivity is the largest reported for a mammal. Limiting NDUFS4 loss to a subset of glutamatergic neurons recapitulates the VA hypersensitivity of Ndufs4(KO) mice, while loss in GABAergic or cholinergic neurons does not. Baseline electrophysiologic function of CA1 pyramidal neurons does not differ between Ndufs4(KO) and control mice. Isoflurane concentrations that anesthetize only Ndufs4(KO) mice (0.6%) decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) only in Ndufs4(KO) CA1 neurons, while concentrations effective in control mice (1.2%) decreased sEPSC frequencies in both control and Ndufs4(KO) CA1 pyramidal cells. Spontaneous inhibitory postsynaptic currents (sIPSCs) were not differentially affected between genotypes. The effects of isoflurane were similar on evoked field excitatory postsynaptic potentials (fEPSPs) and paired pulse facilitation (PPF) in KO and control hippocampal slices. We propose that CA1 presynaptic excitatory neurotransmission is hypersensitive to isoflurane in Ndufs4(KO) mice due to the inhibition of pre-existing reduced complex I function, reaching a critical reduction that can no longer meet metabolic demands.
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Affiliation(s)
- Pavel I Zimin
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA.
| | - Christian B Woods
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Albert Quintana
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Philip G Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Margaret M Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
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193
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Bindu S, Pillai VB, Gupta MP. Role of Sirtuins in Regulating Pathophysiology of the Heart. Trends Endocrinol Metab 2016; 27:563-573. [PMID: 27210897 DOI: 10.1016/j.tem.2016.04.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 04/26/2016] [Accepted: 04/28/2016] [Indexed: 11/28/2022]
Abstract
Cardiovascular diseases (CVDs) are expanding at an alarming rate and people's propensity to develop them increases with age. Growing evidence indicates that sirtuins play a pivotal role in regulating a multitude of age-related diseases. Sirtuins are versatile molecules conserved from archaea to mammals. They are regulated by various metabolic and environmental stimuli. Seven sirtuin homologs (SIRT1-7) are present in mammals, with diverse cellular locations. Recent studies have delineated roles of sirtuins in regulating cardiac pathophysiological conditions under various stressors. SIRT1 is the most extensively studied sirtuin, while the role of other sirtuins in maintaining cardiac growth and function is still emerging. In this review we discuss the present understanding of the role of sirtuins in regulating pathophysiological conditions of the heart.
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Affiliation(s)
- Samik Bindu
- Department of Surgery, Committee on Molecular Medicine and Pathology, Basic Science Division, University of Chicago, Chicago, IL, USA
| | - Vinodkumar B Pillai
- Department of Surgery, Committee on Molecular Medicine and Pathology, Basic Science Division, University of Chicago, Chicago, IL, USA
| | - Mahesh P Gupta
- Department of Surgery, Committee on Molecular Medicine and Pathology, Basic Science Division, University of Chicago, Chicago, IL, USA.
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194
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Roland BP, Zeccola AM, Larsen SB, Amrich CG, Talsma AD, Stuchul KA, Heroux A, Levitan ES, VanDemark AP, Palladino MJ. Structural and Genetic Studies Demonstrate Neurologic Dysfunction in Triosephosphate Isomerase Deficiency Is Associated with Impaired Synaptic Vesicle Dynamics. PLoS Genet 2016; 12:e1005941. [PMID: 27031109 PMCID: PMC4816394 DOI: 10.1371/journal.pgen.1005941] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 02/24/2016] [Indexed: 01/05/2023] Open
Abstract
Triosephosphate isomerase (TPI) deficiency is a poorly understood disease characterized by hemolytic anemia, cardiomyopathy, neurologic dysfunction, and early death. TPI deficiency is one of a group of diseases known as glycolytic enzymopathies, but is unique for its severe patient neuropathology and early mortality. The disease is caused by missense mutations and dysfunction in the glycolytic enzyme, TPI. Previous studies have detailed structural and catalytic changes elicited by disease-associated TPI substitutions, and samples of patient erythrocytes have yielded insight into patient hemolytic anemia; however, the neuropathophysiology of this disease remains a mystery. This study combines structural, biochemical, and genetic approaches to demonstrate that perturbations of the TPI dimer interface are sufficient to elicit TPI deficiency neuropathogenesis. The present study demonstrates that neurologic dysfunction resulting from TPI deficiency is characterized by synaptic vesicle dysfunction, and can be attenuated with catalytically inactive TPI. Collectively, our findings are the first to identify, to our knowledge, a functional synaptic defect in TPI deficiency derived from molecular changes in the TPI dimer interface.
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Affiliation(s)
- Bartholomew P. Roland
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- The Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Alison M. Zeccola
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- The Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Samantha B. Larsen
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- The Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Christopher G. Amrich
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Aaron D. Talsma
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- The Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Kimberly A. Stuchul
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- The Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Annie Heroux
- Energy Sciences Directorate/Photon Science Division, Brookhaven National Laboratory, Upton, New York, United States of America
| | - Edwin S. Levitan
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Andrew P. VanDemark
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Michael J. Palladino
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- The Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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195
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Körber C, Kuner T. Molecular Machines Regulating the Release Probability of Synaptic Vesicles at the Active Zone. Front Synaptic Neurosci 2016; 8:5. [PMID: 26973506 PMCID: PMC4773589 DOI: 10.3389/fnsyn.2016.00005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/17/2016] [Indexed: 11/13/2022] Open
Abstract
The fusion of synaptic vesicles (SVs) with the plasma membrane of the active zone (AZ) upon arrival of an action potential (AP) at the presynaptic compartment is a tightly regulated probabilistic process crucial for information transfer. The probability of a SV to release its transmitter content in response to an AP, termed release probability (Pr), is highly diverse both at the level of entire synapses and individual SVs at a given synapse. Differences in Pr exist between different types of synapses, between synapses of the same type, synapses originating from the same axon and even between different SV subpopulations within the same presynaptic terminal. The Pr of SVs at the AZ is set by a complex interplay of different presynaptic properties including the availability of release-ready SVs, the location of the SVs relative to the voltage-gated calcium channels (VGCCs) at the AZ, the magnitude of calcium influx upon arrival of the AP, the buffering of calcium ions as well as the identity and sensitivity of the calcium sensor. These properties are not only interconnected, but can also be regulated dynamically to match the requirements of activity patterns mediated by the synapse. Here, we review recent advances in identifying molecules and molecular machines taking part in the determination of vesicular Pr at the AZ.
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Affiliation(s)
- Christoph Körber
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
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196
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Kayser EB, Sedensky MM, Morgan PG. Region-Specific Defects of Respiratory Capacities in the Ndufs4(KO) Mouse Brain. PLoS One 2016; 11:e0148219. [PMID: 26824698 PMCID: PMC4732614 DOI: 10.1371/journal.pone.0148219] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/14/2016] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Lack of NDUFS4, a subunit of mitochondrial complex I (NADH:ubiquinone oxidoreductase), causes Leigh syndrome (LS), a progressive encephalomyopathy. Knocking out Ndufs4, either systemically or in brain only, elicits LS in mice. In patients as well as in KO mice distinct regions of the brain degenerate while surrounding tissue survives despite systemic complex I dysfunction. For the understanding of disease etiology and ultimately for the development of rationale treatments for LS, it appears important to uncover the mechanisms that govern focal neurodegeneration. RESULTS Here we used the Ndufs4(KO) mouse to investigate whether regional and temporal differences in respiratory capacity of the brain could be correlated with neurodegeneration. In the KO the respiratory capacity of synaptosomes from the degeneration prone regions olfactory bulb, brainstem and cerebellum was significantly decreased. The difference was measurable even before the onset of neurological symptoms. Furthermore, neither compensating nor exacerbating changes in glycolytic capacity of the synaptosomes were found. By contrast, the KO retained near normal levels of synaptosomal respiration in the degeneration-resistant/resilient "rest" of the brain. We also investigated non-synaptic mitochondria. The KO expectedly had diminished capacity for oxidative phosphorylation (state 3 respiration) with complex I dependent substrate combinations pyruvate/malate and glutamate/malate but surprisingly had normal activity with α-ketoglutarate/malate. No correlation between oxidative phosphorylation (pyruvate/malate driven state 3 respiration) and neurodegeneration was found: Notably, state 3 remained constant in the KO while in controls it tended to increase with time leading to significant differences between the genotypes in older mice in both vulnerable and resilient brain regions. Neither regional ROS damage, measured as HNE-modified protein, nor regional complex I stability, assessed by blue native gels, could explain regional neurodegeneration. CONCLUSION Our data suggests that locally insufficient respiration capacity of the nerve terminals may drive focal neurodegeneration.
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Affiliation(s)
- Ernst-Bernhard Kayser
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
- * E-mail:
| | - Margaret M. Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, United States of America
| | - Philip G. Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, United States of America
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197
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β-Hydroxybutyrate supports synaptic vesicle cycling but reduces endocytosis and exocytosis in rat brain synaptosomes. Neurochem Int 2016; 93:73-81. [PMID: 26748385 DOI: 10.1016/j.neuint.2015.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/28/2015] [Accepted: 12/29/2015] [Indexed: 01/04/2023]
Abstract
The ketogenic diet is used as a prophylactic treatment for different types of brain diseases, such as epilepsy or Alzheimer's disease. In such a diet, carbohydrates are replaced by fats in everyday food, resulting in an elevation of blood-borne ketone bodies levels. Despite clinical applications of this treatment, the molecular mechanisms by which the ketogenic diet exerts its beneficial effects are still uncertain. In this study, we investigated the effect of replacing glucose by the ketone body β-hydroxybutyrate as the main energy substrate on synaptic vesicle recycling in rat brain synaptosomes. First, we observed that exposing presynaptic terminals to nonglycolytic energy substrates instead of glucose did not alter the plasma membrane potential. Next, we found that synaptosomes were able to maintain the synaptic vesicle cycle monitored with the fluorescent dye acridine orange when glucose was replaced by β-hydroxybutyrate. However, in presence of β-hydroxybutyrate, synaptic vesicle recycling was modified with reduced endocytosis. Replacing glucose by pyruvate also led to a reduced endocytosis. Addition of β-hydroxybutyrate to glucose-containing incubation medium was without effect. Reduced endocytosis in presence of β-hydroxybutyrate as sole energy substrate was confirmed using the fluorescent dye FM2-10. Also we found that replacement of glucose by ketone bodies leads to inhibition of exocytosis, monitored by FM2-10. However this reduction was smaller than the effect on endocytosis under the same conditions. Using both acridine orange in synaptosomes and the genetically encoded sensor synaptopHluorin in cortical neurons, we observed that replacing glucose by β-hydroxybutyrate did not modify the pH gradient of synaptic vesicles. In conclusion, the nonglycolytic energy substrates β-hydroxybutyrate and pyruvate are able to support synaptic vesicle recycling. However, they both reduce endocytosis. Reduction of both endocytosis and exocytosis together with misbalance between endocytosis and exocytosis could be involved in the anticonvulsant activity of the ketogenic diet.
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198
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Marland JRK, Hasel P, Bonnycastle K, Cousin MA. Mitochondrial Calcium Uptake Modulates Synaptic Vesicle Endocytosis in Central Nerve Terminals. J Biol Chem 2015; 291:2080-6. [PMID: 26644474 PMCID: PMC4732196 DOI: 10.1074/jbc.m115.686956] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 12/15/2022] Open
Abstract
Presynaptic calcium influx triggers synaptic vesicle (SV) exocytosis and modulates subsequent SV endocytosis. A number of calcium clearance mechanisms are present in central nerve terminals that regulate intracellular free calcium levels both during and after stimulation. During action potential stimulation, mitochondria rapidly accumulate presynaptic calcium via the mitochondrial calcium uniporter (MCU). The role of mitochondrial calcium uptake in modulating SV recycling has been debated extensively, but a definitive conclusion has not been achieved. To directly address this question, we manipulated the expression of the MCU channel subunit in primary cultures of neurons expressing a genetically encoded reporter of SV turnover. Knockdown of MCU resulted in ablation of activity-dependent mitochondrial calcium uptake but had no effect on the rate or extent of SV exocytosis. In contrast, the rate of SV endocytosis was increased in the absence of mitochondrial calcium uptake and slowed when MCU was overexpressed. MCU knockdown did not perturb activity-dependent increases in presynaptic free calcium, suggesting that SV endocytosis may be controlled by calcium accumulation and efflux from mitochondria in their immediate vicinity.
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Affiliation(s)
- Jamie Roslin Keynes Marland
- From the Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom
| | - Philip Hasel
- From the Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom
| | - Katherine Bonnycastle
- From the Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom
| | - Michael Alan Cousin
- From the Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom
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199
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Hjelm BE, Rollins B, Mamdani F, Lauterborn JC, Kirov G, Lynch G, Gall CM, Sequeira A, Vawter MP. Evidence of Mitochondrial Dysfunction within the Complex Genetic Etiology of Schizophrenia. MOLECULAR NEUROPSYCHIATRY 2015; 1:201-19. [PMID: 26550561 DOI: 10.1159/000441252] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/22/2015] [Indexed: 01/19/2023]
Abstract
Genetic evidence has supported the hypothesis that schizophrenia (SZ) is a polygenic disorder caused by the disruption in function of several or many genes. The most common and reproducible cellular phenotype associated with SZ is a reduction in dendritic spines within the neocortex, suggesting alterations in dendritic architecture may cause aberrant cortical circuitry and SZ symptoms. Here, we review evidence supporting a multifactorial model of mitochondrial dysfunction in SZ etiology and discuss how these multiple paths to mitochondrial dysfunction may contribute to dendritic spine loss and/or underdevelopment in some SZ subjects. The pathophysiological role of mitochondrial dysfunction in SZ is based upon genomic analyses of both the mitochondrial genome and nuclear genes involved in mitochondrial function. Previous studies and preliminary data suggest SZ is associated with specific alleles and haplogroups of the mitochondrial genome, and also correlates with a reduction in mitochondrial copy number and an increase in synonymous and nonsynonymous substitutions of mitochondrial DNA. Mitochondrial dysfunction has also been widely implicated in SZ by genome-wide association, exome sequencing, altered gene expression, proteomics, microscopy analyses, and induced pluripotent stem cell studies. Together, these data support the hypothesis that SZ is a polygenic disorder with an enrichment of mitochondrial targets.
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Affiliation(s)
- Brooke E Hjelm
- Departments of Psychiatry & Human Behavior, University of California, Irvine, Calif., USA
| | - Brandi Rollins
- Departments of Psychiatry & Human Behavior, University of California, Irvine, Calif., USA
| | - Firoza Mamdani
- Departments of Psychiatry & Human Behavior, University of California, Irvine, Calif., USA
| | - Julie C Lauterborn
- Departments of Anatomy & Neurobiology, University of California, Irvine, Calif., USA
| | - George Kirov
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, UK
| | - Gary Lynch
- Departments of Psychiatry & Human Behavior, University of California, Irvine, Calif., USA; Departments of Anatomy & Neurobiology, University of California, Irvine, Calif., USA
| | - Christine M Gall
- Departments of Anatomy & Neurobiology, University of California, Irvine, Calif., USA; Departments of Neurobiology & Behavior, University of California, Irvine, Calif., USA
| | - Adolfo Sequeira
- Departments of Psychiatry & Human Behavior, University of California, Irvine, Calif., USA
| | - Marquis P Vawter
- Departments of Psychiatry & Human Behavior, University of California, Irvine, Calif., USA
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200
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Haddad D, Nakamura K. Understanding the susceptibility of dopamine neurons to mitochondrial stressors in Parkinson's disease. FEBS Lett 2015; 589:3702-13. [PMID: 26526613 DOI: 10.1016/j.febslet.2015.10.021] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/14/2015] [Accepted: 10/15/2015] [Indexed: 12/21/2022]
Abstract
Mitochondria are undoubtedly changed in Parkinson's disease (PD), and mitochondrial functions are disrupted in genetic and pharmacologic models of PD. However, many of these changes might not truly drive neurodegeneration. PD is defined by the particular susceptibility of nigrostriatal dopamine (DA) neurons, but little is understood about the mitochondria in these cells. Here, we critically review the evidence that mitochondrial stressors cause PD. We then consider how changes in the intrinsic function of mitochondria and in their mass, distribution, and dynamics might synergize with an increased need for mitochondria and produce PD, and the importance of understanding how mitochondria contribute to its pathogenesis.
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Affiliation(s)
- Dominik Haddad
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Ken Nakamura
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Department of Neurology, and Graduate Programs in Neuroscience and Biomedical Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
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