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Zhong R, Rua MT, Wei-LaPierre L. Targeting mitochondrial Ca 2+ uptake for the treatment of amyotrophic lateral sclerosis. J Physiol 2024; 602:1519-1549. [PMID: 38010626 PMCID: PMC11032238 DOI: 10.1113/jp284143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/31/2023] [Indexed: 11/29/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a rare adult-onset neurodegenerative disease characterized by progressive motor neuron (MN) loss, muscle denervation and paralysis. Over the past several decades, researchers have made tremendous efforts to understand the pathogenic mechanisms underpinning ALS, with much yet to be resolved. ALS is described as a non-cell autonomous condition with pathology detected in both MNs and non-neuronal cells, such as glial cells and skeletal muscle. Studies in ALS patient and animal models reveal ubiquitous abnormalities in mitochondrial structure and function, and disturbance of intracellular calcium homeostasis in various tissue types, suggesting a pivotal role of aberrant mitochondrial calcium uptake and dysfunctional calcium signalling cascades in ALS pathogenesis. Calcium signalling and mitochondrial dysfunction are intricately related to the manifestation of cell death contributing to MN loss and skeletal muscle dysfunction. In this review, we discuss the potential contribution of intracellular calcium signalling, particularly mitochondrial calcium uptake, in ALS pathogenesis. Functional consequences of excessive mitochondrial calcium uptake and possible therapeutic strategies targeting mitochondrial calcium uptake or the mitochondrial calcium uniporter, the main channel mediating mitochondrial calcium influx, are also discussed.
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Affiliation(s)
- Renjia Zhong
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
- Department of Emergency Medicine, the First Affiliated Hospital of China Medical University, Shenyang, Liaoning, China, 110001
| | - Michael T. Rua
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
| | - Lan Wei-LaPierre
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
- Myology Institute, University of Florida, Gainesville, FL 32611
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2
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Kruglov AG, Romshin AM, Nikiforova AB, Plotnikova A, Vlasov II. Warm Cells, Hot Mitochondria: Achievements and Problems of Ultralocal Thermometry. Int J Mol Sci 2023; 24:16955. [PMID: 38069275 PMCID: PMC10707128 DOI: 10.3390/ijms242316955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/27/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
Temperature is a crucial regulator of the rate and direction of biochemical reactions and cell processes. The recent data indicating the presence of local thermal gradients associated with the sites of high-rate thermogenesis, on the one hand, demonstrate the possibility for the existence of "thermal signaling" in a cell and, on the other, are criticized on the basis of thermodynamic calculations and models. Here, we review the main thermometric techniques and sensors developed for the determination of temperature inside living cells and diverse intracellular compartments. A comparative analysis is conducted of the results obtained using these methods for the cytosol, nucleus, endo-/sarcoplasmic reticulum, and mitochondria, as well as their biological consistency. Special attention is given to the limitations, possible sources of errors and ambiguities of the sensor's responses. The issue of biological temperature limits in cells and organelles is considered. It is concluded that the elaboration of experimental protocols for ultralocal temperature measurements that take into account both the characteristics of biological systems, as well as the properties and limitations of each type of sensor is of critical importance for the generation of reliable results and further progress in this field.
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Affiliation(s)
- Alexey G. Kruglov
- Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Alexey M. Romshin
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia;
| | - Anna B. Nikiforova
- Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Arina Plotnikova
- Institute for Physics and Engineering in Biomedicine, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute MEPhI), 115409 Moscow, Russia;
| | - Igor I. Vlasov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia;
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3
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Barrett JN, Barrett EF, Rajguru SM. Mitochondrial responses to intracellular Ca 2+ release following infrared stimulation. J Neurophysiol 2023; 129:700-716. [PMID: 36752512 PMCID: PMC10026987 DOI: 10.1152/jn.00293.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
Many studies of Ca2+ effects on mitochondrial respiration in intact cells have used electrical and/or chemical stimulation to elevate intracellular [Ca2+], and have reported increases in [NADH] and increased ADP/ATP ratios as dominant controllers of respiration. This study tested a different form of stimulation: brief temperature increases produced by pulses of infrared light (IR, 1,863 nm, 8-10°C for ∼5 s). Fluorescence imaging techniques applied to single PC-12 cells in low µM extracellular [Ca2+] revealed IR stimulation-induced increases in both cytosolic (fluo5F) and mitochondrial (rhod2) [Ca2+]. IR stimulation increased O2 consumption (porphyrin fluorescence), and produced an alkaline shift in mitochondrial matrix pH (Snarf1), indicating activation of the electron transport chain (ETC). The increase in O2 consumption persisted in oligomycin, and began during a decrease in NADH, suggesting that the initial increase in ETC activity was not driven by increased ATP synthase activity or an increased fuel supply to ETC complex I. Imaging with two potentiometric dyes [tetramethyl rhodamine methyl ester (TMRM) and R123] indicated a depolarizing shift in ΔΨm that persisted in high [K+] medium. High-resolution fluorescence imaging disclosed large, reversible mitochondrial depolarizations that were inhibited by cyclosporin A (CSA), consistent with the opening of transient mitochondrial permeability transition pores. IR stimulation also produced a Ca2+-dependent increase in superoxide production (MitoSox) that was not inhibited by CSA, indicating that the increase in superoxide did not require transition pore opening. Thus, the intracellular Ca2+ release that follows pulses of infrared light offers new insights into Ca2+-dependent processes controlling respiration and reactive oxygen species in intact cells.NEW & NOTEWORTHY Pulses of infrared light (IR) provide a novel method for rapidly transferring Ca2+ from the endoplasmic reticulum to mitochondria in intact cells. In PC12 cells the resulting ETC activation was not driven by increased ATP synthase activity or NADH. IR stimulation produced a Ca2+-dependent, reversible depolarization of ΔΨm that was partially blocked by cyclosporin A, and a Ca2+-dependent increase in superoxide that did not require transition pore opening.
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Affiliation(s)
- John N Barrett
- Department of Physiology and Biophysics, University of Miami, Florida, United States
- Neuroscience Program, University of Miami, Florida, United States
| | - Ellen F Barrett
- Department of Physiology and Biophysics, University of Miami, Florida, United States
- Neuroscience Program, University of Miami, Florida, United States
| | - Suhrud M Rajguru
- Department of Biomedical Engineering, University of Miami, Florida, United States
- Department of Otolaryngology, University of Miami, Florida, United States
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4
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Walters GC, Usachev YM. Mitochondrial calcium cycling in neuronal function and neurodegeneration. Front Cell Dev Biol 2023; 11:1094356. [PMID: 36760367 PMCID: PMC9902777 DOI: 10.3389/fcell.2023.1094356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/12/2023] [Indexed: 01/26/2023] Open
Abstract
Mitochondria are essential for proper cellular function through their critical roles in ATP synthesis, reactive oxygen species production, calcium (Ca2+) buffering, and apoptotic signaling. In neurons, Ca2+ buffering is particularly important as it helps to shape Ca2+ signals and to regulate numerous Ca2+-dependent functions including neuronal excitability, synaptic transmission, gene expression, and neuronal toxicity. Over the past decade, identification of the mitochondrial Ca2+ uniporter (MCU) and other molecular components of mitochondrial Ca2+ transport has provided insight into the roles that mitochondrial Ca2+ regulation plays in neuronal function in health and disease. In this review, we discuss the many roles of mitochondrial Ca2+ uptake and release mechanisms in normal neuronal function and highlight new insights into the Ca2+-dependent mechanisms that drive mitochondrial dysfunction in neurologic diseases including epilepsy, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. We also consider how targeting Ca2+ uptake and release mechanisms could facilitate the development of novel therapeutic strategies for neurological diseases.
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Affiliation(s)
- Grant C. Walters
- Department of Neuroscience and Pharmacology, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
| | - Yuriy M. Usachev
- Department of Neuroscience and Pharmacology, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
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5
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Interaction of Mitochondrial Calcium and ROS in Neurodegeneration. Cells 2022; 11:cells11040706. [PMID: 35203354 PMCID: PMC8869783 DOI: 10.3390/cells11040706] [Citation(s) in RCA: 67] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/05/2022] [Accepted: 02/14/2022] [Indexed: 02/06/2023] Open
Abstract
Neurodegenerative disorders are currently incurable devastating diseases which are characterized by the slow and progressive loss of neurons in specific brain regions. Progress in the investigation of the mechanisms of these disorders helped to identify a number of genes associated with familial forms of these diseases and a number of toxins and risk factors which trigger sporadic and toxic forms of these diseases. Recently, some similarities in the mechanisms of neurodegenerative diseases were identified, including the involvement of mitochondria, oxidative stress, and the abnormality of Ca2+ signaling in neurons and astrocytes. Thus, mitochondria produce reactive oxygen species during metabolism which play a further role in redox signaling, but this may also act as an additional trigger for abnormal mitochondrial calcium handling, resulting in mitochondrial calcium overload. Combinations of these factors can be the trigger of neuronal cell death in some pathologies. Here, we review the latest literature on the crosstalk of reactive oxygen species and Ca2+ in brain mitochondria in physiology and beyond, considering how changes in mitochondrial metabolism or redox signaling can convert this interaction into a pathological event.
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6
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Lopez-Manzaneda M, Franco-Espin J, Tejero R, Cano R, Tabares L. Calcium is reduced in presynaptic mitochondria of motor nerve terminals during neurotransmission in SMA mice. Hum Mol Genet 2021; 30:629-643. [PMID: 33693569 PMCID: PMC8127408 DOI: 10.1093/hmg/ddab065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/21/2021] [Accepted: 02/23/2021] [Indexed: 01/17/2023] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive degenerative motor neuron disease characterized by symmetrical muscle weakness and atrophy of limb and trunk muscles being the most severe genetic disease in children. In SMA mouse models, motor nerve terminals display neurotransmitter release reduction, endocytosis decrease and mitochondria alterations. The relationship between these changes is, however, not well understood. In the present study, we investigated whether the endocytosis impairment could be related to the functional alteration of the presynaptic mitochondria during action potential (AP) firing. To this aim, we generated a Synaptophysin-pHluorin (SypHy) transgenic mouse, crossed it with Taiwanese SMA mice, and recorded exo- and endocytosis and mitochondria Ca2+ signaling in real-time at ex vivo motor nerve terminals of Taiwanese-SypHy mice. The experiments were performed at the beginning of the motor symptoms to get an integrated view of the nerve terminal’s functional state before degeneration. Our electrophysiological and live imaging results demonstrated that the mitochondria’s capacity to increase matrix-free Ca2+ in SMA mice was significantly limited during nerve AP firing, except when the rate of Ca2+ entry to the cytosol was considerably reduced. These results indicate that both the mitochondrial Ca2+ signaling alterations and the secretion machinery defects are significant players in the dysfunction of the presynaptic terminal in SMA.
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Affiliation(s)
- Mario Lopez-Manzaneda
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Julio Franco-Espin
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Rocio Tejero
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Raquel Cano
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Lucia Tabares
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
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7
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Shteinfer-Kuzmine A, Argueti S, Gupta R, Shvil N, Abu-Hamad S, Gropper Y, Hoeber J, Magrì A, Messina A, Kozlova EN, Shoshan-Barmatz V, Israelson A. A VDAC1-Derived N-Terminal Peptide Inhibits Mutant SOD1-VDAC1 Interactions and Toxicity in the SOD1 Model of ALS. Front Cell Neurosci 2019; 13:346. [PMID: 31474832 PMCID: PMC6702328 DOI: 10.3389/fncel.2019.00346] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 07/15/2019] [Indexed: 12/12/2022] Open
Abstract
Mutations in superoxide dismutase (SOD1) are the second most common cause of familial amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease caused by the death of motor neurons in the brain and spinal cord. SOD1 neurotoxicity has been attributed to aberrant accumulation of misfolded SOD1, which in its soluble form binds to intracellular organelles, such as mitochondria and ER, disrupting their functions. Here, we demonstrate that mutant SOD1 binds specifically to the N-terminal domain of the voltage-dependent anion channel (VDAC1), an outer mitochondrial membrane protein controlling cell energy, metabolic and survival pathways. Mutant SOD1G93A and SOD1G85R, but not wild type SOD1, directly interact with VDAC1 and reduce its channel conductance. No such interaction with N-terminal-truncated VDAC1 occurs. Moreover, a VDAC1-derived N-terminal peptide inhibited mutant SOD1-induced toxicity. Incubation of motor neuron-like NSC-34 cells expressing mutant SOD1 or mouse embryonic stem cell-derived motor neurons with different VDAC1 N-terminal peptides resulted in enhanced cell survival. Taken together, our results establish a direct link between mutant SOD1 toxicity and the VDAC1 N-terminal domain and suggest that VDAC1 N-terminal peptides targeting mutant SOD1 provide potential new therapeutic strategies for ALS.
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Affiliation(s)
- Anna Shteinfer-Kuzmine
- Department of Life Sciences, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Shirel Argueti
- Department of Physiology and Cell Biology, Faculty of Health Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Rajeev Gupta
- Department of Life Sciences, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Neta Shvil
- Department of Physiology and Cell Biology, Faculty of Health Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Salah Abu-Hamad
- Department of Physiology and Cell Biology, Faculty of Health Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Yael Gropper
- Department of Physiology and Cell Biology, Faculty of Health Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Jan Hoeber
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Andrea Magrì
- Department of Biological, Geological and Environmental Sciences, University of Catania, Catania, Italy
| | - Angela Messina
- Department of Biological, Geological and Environmental Sciences, University of Catania, Catania, Italy
| | - Elena N Kozlova
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Varda Shoshan-Barmatz
- Department of Life Sciences, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Adrian Israelson
- Department of Physiology and Cell Biology, Faculty of Health Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel
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8
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Zhou J, Li A, Li X, Yi J. Dysregulated mitochondrial Ca 2+ and ROS signaling in skeletal muscle of ALS mouse model. Arch Biochem Biophys 2019; 663:249-258. [PMID: 30682329 PMCID: PMC6506190 DOI: 10.1016/j.abb.2019.01.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/24/2018] [Accepted: 01/18/2019] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neuromuscular disease characterized by motor neuron loss and prominent skeletal muscle wasting. Despite more than one hundred years of research efforts, the pathogenic mechanisms underlying neuromuscular degeneration in ALS remain elusive. While the death of motor neuron is a defining hallmark of ALS, accumulated evidences suggested that in addition to being a victim of motor neuron axonal withdrawal, the intrinsic skeletal muscle degeneration may also actively contribute to ALS disease pathogenesis and progression. Examination of spinal cord and muscle autopsy/biopsy samples of ALS patients revealed similar mitochondrial abnormalities in morphology, quantity and disposition, which are accompanied by defective mitochondrial respiratory chain complex and elevated oxidative stress. Detailing the molecular/cellular mechanisms and the role of mitochondrial dysfunction in ALS relies on ALS animal model studies. This review article discusses the dysregulated mitochondrial Ca2+ and reactive oxygen species (ROS) signaling revealed in live skeletal muscle derived from ALS mouse models, and a potential role of the vicious cycle formed between the dysregulated mitochondrial Ca2+ signaling and excessive ROS production in promoting muscle wasting during ALS progression.
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Affiliation(s)
- Jingsong Zhou
- Kansas City University of Medicine and Bioscience, Kansas City, MO 64106, USA; College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, TX 76019, USA.
| | - Ang Li
- Kansas City University of Medicine and Bioscience, Kansas City, MO 64106, USA; College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Xuejun Li
- Kansas City University of Medicine and Bioscience, Kansas City, MO 64106, USA; College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Jianxun Yi
- Kansas City University of Medicine and Bioscience, Kansas City, MO 64106, USA; College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, TX 76019, USA.
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9
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Verma M, Wills Z, Chu CT. Excitatory Dendritic Mitochondrial Calcium Toxicity: Implications for Parkinson's and Other Neurodegenerative Diseases. Front Neurosci 2018; 12:523. [PMID: 30116173 PMCID: PMC6083050 DOI: 10.3389/fnins.2018.00523] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 07/12/2018] [Indexed: 12/22/2022] Open
Abstract
Dysregulation of calcium homeostasis has been linked to multiple neurological diseases. In addition to excitotoxic neuronal cell death observed following stroke, a growing number of studies implicate excess excitatory neuronal activity in chronic neurodegenerative diseases. Mitochondria function to rapidly sequester large influxes of cytosolic calcium through the activity of the mitochondrial calcium uniporter (MCU) complex, followed by more gradual release via calcium antiporters, such as NCLX. Increased cytosolic calcium levels almost invariably result in increased mitochondrial calcium uptake. While this response may augment mitochondrial respiration, limiting classic excitotoxic injury in the short term, recent studies employing live calcium imaging and molecular manipulation of calcium transporter activities suggest that mitochondrial calcium overload plays a key role in Parkinson’s disease (PD), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), and related dementias [PD with dementia (PDD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD)]. Herein, we review the literature on increased excitatory input, mitochondrial calcium dysregulation, and the transcriptional or post-translational regulation of mitochondrial calcium transport proteins, with an emphasis on the PD-linked kinases LRRK2 and PINK1. The impact on pathological dendrite remodeling and neuroprotective effects of manipulating MCU, NCLX, and LETM1 are reviewed. We propose that shortening and simplification of the dendritic arbor observed in neurodegenerative diseases occur through a process of excitatory mitochondrial toxicity (EMT), which triggers mitophagy and perisynaptic mitochondrial depletion, mechanisms that are distinct from classic excitotoxicity.
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Affiliation(s)
- Manish Verma
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Zachary Wills
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Charleen T Chu
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Pittsburgh Institute for Neurodegenerative Diseases, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,McGowan Institute for Regenerative Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Protein Conformational Diseases, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Neuroscience, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
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10
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Esterberg R, Linbo T, Pickett SB, Wu P, Ou HC, Rubel EW, Raible DW. Mitochondrial calcium uptake underlies ROS generation during aminoglycoside-induced hair cell death. J Clin Invest 2016; 126:3556-66. [PMID: 27500493 DOI: 10.1172/jci84939] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 06/09/2016] [Indexed: 12/11/2022] Open
Abstract
Exposure to aminoglycoside antibiotics can lead to the generation of toxic levels of reactive oxygen species (ROS) within mechanosensory hair cells of the inner ear that have been implicated in hearing and balance disorders. Better understanding of the origin of aminoglycoside-induced ROS could focus the development of therapies aimed at preventing this event. In this work, we used the zebrafish lateral line system to monitor the dynamic behavior of mitochondrial and cytoplasmic oxidation occurring within the same dying hair cell following exposure to aminoglycosides. The increased oxidation observed in both mitochondria and cytoplasm of dying hair cells was highly correlated with mitochondrial calcium uptake. Application of the mitochondrial uniporter inhibitor Ru360 reduced mitochondrial and cytoplasmic oxidation, suggesting that mitochondrial calcium drives ROS generation during aminoglycoside-induced hair cell death. Furthermore, targeting mitochondria with free radical scavengers conferred superior protection against aminoglycoside exposure compared with identical, untargeted scavengers. Our findings suggest that targeted therapies aimed at preventing mitochondrial oxidation have therapeutic potential to ameliorate the toxic effects of aminoglycoside exposure.
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11
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Edens BM, Miller N, Ma YC. Impaired Autophagy and Defective Mitochondrial Function: Converging Paths on the Road to Motor Neuron Degeneration. Front Cell Neurosci 2016; 10:44. [PMID: 26973461 PMCID: PMC4776126 DOI: 10.3389/fncel.2016.00044] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/08/2016] [Indexed: 12/12/2022] Open
Abstract
Selective motor neuron degeneration is a hallmark of amyotrophic lateral sclerosis (ALS). Around 10% of all cases present as familial ALS (FALS), while sporadic ALS (SALS) accounts for the remaining 90%. Diverse genetic mutations leading to FALS have been identified, but the underlying causes of SALS remain largely unknown. Despite the heterogeneous and incompletely understood etiology, different types of ALS exhibit overlapping pathology and common phenotypes, including protein aggregation and mitochondrial deficiencies. Here, we review the current understanding of mechanisms leading to motor neuron degeneration in ALS as they pertain to disrupted cellular clearance pathways, ATP biogenesis, calcium buffering and mitochondrial dynamics. Through focusing on impaired autophagic and mitochondrial functions, we highlight how the convergence of diverse cellular processes and pathways contributes to common pathology in motor neuron degeneration.
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Affiliation(s)
- Brittany M. Edens
- Departments of Pediatrics, Neurology, and Physiology, Northwestern University Feinberg School of MedicineChicago, IL, USA
- Lurie Children’s Hospital of ChicagoChicago, IL, USA
| | - Nimrod Miller
- Departments of Pediatrics, Neurology, and Physiology, Northwestern University Feinberg School of MedicineChicago, IL, USA
- Lurie Children’s Hospital of ChicagoChicago, IL, USA
| | - Yong-Chao Ma
- Departments of Pediatrics, Neurology, and Physiology, Northwestern University Feinberg School of MedicineChicago, IL, USA
- Lurie Children’s Hospital of ChicagoChicago, IL, USA
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12
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Kaus A, Sareen D. ALS Patient Stem Cells for Unveiling Disease Signatures of Motoneuron Susceptibility: Perspectives on the Deadly Mitochondria, ER Stress and Calcium Triad. Front Cell Neurosci 2015; 9:448. [PMID: 26635528 PMCID: PMC4652136 DOI: 10.3389/fncel.2015.00448] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/02/2015] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a largely sporadic progressive neurodegenerative disease affecting upper and lower motoneurons (MNs) whose specific etiology is incompletely understood. Mutations in superoxide dismutase-1 (SOD1), TAR DNA-binding protein 43 (TARDBP/TDP-43) and C9orf72, have been identified in subsets of familial and sporadic patients. Key associated molecular and neuropathological features include ubiquitinated TDP-43 inclusions, stress granules, aggregated dipeptide proteins from mutant C9orf72 transcripts, altered mitochondrial ultrastructure, dysregulated calcium homeostasis, oxidative and endoplasmic reticulum (ER) stress, and an unfolded protein response (UPR). Such impairments have been documented in ALS animal models; however, whether these mechanisms are initiating factors or later consequential events leading to MN vulnerability in ALS patients is debatable. Human induced pluripotent stem cells (iPSCs) are a valuable tool that could resolve this “chicken or egg” causality dilemma. Relevant systems for probing pathophysiologically affected cells from large numbers of ALS patients and discovering phenotypic disease signatures of early MN susceptibility are described. Performing unbiased ‘OMICS and high-throughput screening in relevant neural cells from a cohort of ALS patient iPSCs, and rescuing mitochondrial and ER stress impairments, can identify targeted therapeutics for increasing MN longevity in ALS.
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Affiliation(s)
- Anjoscha Kaus
- Board of Governors-Regenerative Medicine Institute, Cedars-Sinai Medical Center Los Angeles, CA, USA ; Department of Biomedical Sciences, Cedars-Sinai Medical Center Los Angeles, CA, USA
| | - Dhruv Sareen
- Board of Governors-Regenerative Medicine Institute, Cedars-Sinai Medical Center Los Angeles, CA, USA ; Department of Biomedical Sciences, Cedars-Sinai Medical Center Los Angeles, CA, USA ; iPSC Core, The David and Janet Polak Stem Cell Laboratory, Cedars-Sinai Medical Center Los Angeles, CA, USA
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13
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Machado MD, Lopes AR, Soares EV. Responses of the alga Pseudokirchneriella subcapitata to long-term exposure to metal stress. JOURNAL OF HAZARDOUS MATERIALS 2015; 296:82-92. [PMID: 25913674 DOI: 10.1016/j.jhazmat.2015.04.022] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 03/07/2015] [Accepted: 04/08/2015] [Indexed: 06/04/2023]
Abstract
The green alga Pseudokirchneriella subcapitata has been widely used in ecological risk assessment, usually based on the impact of the toxicants in the alga growth. However, the physiological causes that lead algal growth inhibition are not completely understood. This work aimed to evaluate the biochemical and structural modifications in P. subcapitata after exposure, for 72 h, to three nominal concentrations of Cd(II), Cr(VI), Cu(II) and Zn(II), corresponding approximately to 72 h-EC10 and 72 h-EC50 values and a high concentration (above 72 h-EC90 values). The incubation of algal cells with the highest concentration of Cd(II), Cr(VI) or Cu(II) resulted in a loss of membrane integrity of ~16, 38 and 55%, respectively. For all metals tested, an inhibition of esterase activity, in a dose-dependent manner, was observed. Reduction of chlorophyll a content, decrease of maximum quantum yield of photosystem II and modification of mitochondrial membrane potential was also verified. In conclusion, the exposure of P. subcapitata to metals resulted in a perturbation of the cell physiological status. Principal component analysis revealed that the impairment of esterase activity combined with the reduction of chlorophyll a content were related with the inhibition of growth caused by a prolonged exposure to the heavy metals.
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Affiliation(s)
- Manuela D Machado
- Bioengineering Laboratory, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, Porto, Portugal; CEB-Centre of Biological Engineering, University of Minho, Braga, Portugal
| | - Ana R Lopes
- LEPABE, Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Porto, Portugal
| | - Eduardo V Soares
- Bioengineering Laboratory, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, Porto, Portugal; CEB-Centre of Biological Engineering, University of Minho, Braga, Portugal.
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14
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Quinlan KA, Lamano JB, Samuels J, Heckman CJ. Comparison of dendritic calcium transients in juvenile wild type and SOD1(G93A) mouse lumbar motoneurons. Front Cell Neurosci 2015; 9:139. [PMID: 25914627 PMCID: PMC4392694 DOI: 10.3389/fncel.2015.00139] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 03/23/2015] [Indexed: 12/14/2022] Open
Abstract
Previous studies of spinal motoneurons in the SOD1 mouse model of amyotrophic lateral sclerosis have shown alterations long before disease onset, including increased dendritic branching, increased persistent Na+ and Ca2+ currents, and impaired axonal transport. In this study dendritic Ca2+ entry was investigated using two photon excitation fluorescence microscopy and whole-cell patch-clamp of juvenile (P4-11) motoneurons. Neurons were filled with both Ca2+ Green-1 and Texas Red dextrans, and line scans performed throughout. Steps were taken to account for different sources of variability, including (1) dye filling and laser penetration, (2) dendritic anatomy, and (3) the time elapsed from the start of recording. First, Ca2+ Green-1 fluorescence was normalized by Texas Red; next, neurons were reconstructed so anatomy could be evaluated; finally, time was recorded. Customized software detected the largest Ca2+ transients (area under the curve) from each line scan and matched it with parameters above. Overall, larger dendritic diameter and shorter path distance from the soma were significant predictors of larger transients, while time was not significant up to 2 h (data thereafter was dropped). However, Ca2+ transients showed additional variability. Controlling for previous factors, significant variation was found between Ca2+ signals from different processes of the same neuron in 3/7 neurons. This could reflect differential expression of Ca2+ channels, local neuromodulation or other variations. Finally, Ca2+ transients in SOD1G93A motoneurons were significantly smaller than in non-transgenic motoneurons. In conclusion, motoneuron processes show highly variable Ca2+ transients, but these transients are smaller overall in SOD1G93A motoneurons.
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Affiliation(s)
- Katharina A Quinlan
- Department of Physiology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA
| | - Jonathan B Lamano
- Department of Physiology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA
| | - Julienne Samuels
- Department of Physiology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA
| | - C J Heckman
- Department of Physiology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA ; Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University Chicago, IL, USA ; Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University Chicago, IL, USA
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15
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Brown R, Hynes-Allen A, Swan AJ, Dissanayake KN, Gillingwater TH, Ribchester RR. Activity-dependent degeneration of axotomized neuromuscular synapses in Wld S mice. Neuroscience 2015; 290:300-20. [PMID: 25617654 PMCID: PMC4362769 DOI: 10.1016/j.neuroscience.2015.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 01/10/2015] [Accepted: 01/12/2015] [Indexed: 12/12/2022]
Abstract
Use and disuse may influence synaptic maintenance but so far evidence for this has been indirect. We tested whether stimulation or disuse of neuromuscular junctions in adult WldS mice altered vulnerability to axotomy. Moderate activity optimized resistance to axotomy while disuse or stimulation increased the rate of synaptic degeneration.
Activity and disuse of synapses are thought to influence progression of several neurodegenerative diseases in which synaptic degeneration is an early sign. Here we tested whether stimulation or disuse renders neuromuscular synapses more or less vulnerable to degeneration, using axotomy as a robust trigger. We took advantage of the slow synaptic degeneration phenotype of axotomized neuromuscular junctions in flexor digitorum brevis (FDB) and deep lumbrical (DL) muscles of Wallerian degeneration-Slow (WldS) mutant mice. First, we maintained ex vivo FDB and DL nerve-muscle explants at 32 °C for up to 48 h. About 90% of fibers from WldS mice remained innervated, compared with about 36% in wild-type muscles at the 24-h checkpoint. Periodic high-frequency nerve stimulation (100 Hz: 1 s/100 s) reduced synaptic protection in WldS preparations by about 50%. This effect was abolished in reduced Ca2+ solutions. Next, we assayed FDB and DL innervation after 7 days of complete tetrodotoxin (TTX)-block of sciatic nerve conduction in vivo, followed by tibial nerve axotomy. Five days later, only about 9% of motor endplates remained innervated in the paralyzed muscles, compared with about 50% in 5 day-axotomized muscles from saline-control-treated WldS mice with no conditioning nerve block. Finally, we gave mice access to running wheels for up to 4 weeks prior to axotomy. Surprisingly, exercising WldS mice ad libitum for 4 weeks increased about twofold the amount of subsequent axotomy-induced synaptic degeneration. Together, the data suggest that vulnerability of mature neuromuscular synapses to axotomy, a potent neurodegenerative trigger, may be enhanced bimodally, either by disuse or by hyperactivity.
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Affiliation(s)
- R Brown
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - A Hynes-Allen
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - A J Swan
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - K N Dissanayake
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - T H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK
| | - R R Ribchester
- Euan MacDonald Centre for Motor Neurone Disease Research, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
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16
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Mühling T, Duda J, Weishaupt JH, Ludolph AC, Liss B. Elevated mRNA-levels of distinct mitochondrial and plasma membrane Ca(2+) transporters in individual hypoglossal motor neurons of endstage SOD1 transgenic mice. Front Cell Neurosci 2014; 8:353. [PMID: 25452714 PMCID: PMC4231948 DOI: 10.3389/fncel.2014.00353] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/08/2014] [Indexed: 12/13/2022] Open
Abstract
Disturbances in Ca2+ homeostasis and mitochondrial dysfunction have emerged as major pathogenic features in familial and sporadic forms of Amyotrophic Lateral Sclerosis (ALS), a fatal degenerative motor neuron disease. However, the distinct molecular ALS-pathology remains unclear. Recently, an activity-dependent Ca2+ homeostasis deficit, selectively in highly vulnerable cholinergic motor neurons in the hypoglossal nucleus (hMNs) from a common ALS mouse model, the endstage superoxide dismutase SOD1G93A transgenic mouse, was described. This functional deficit was defined by a reduced hMN mitochondrial Ca2+ uptake capacity and elevated Ca2+ extrusion across the plasma membrane. To address the underlying molecular mechanisms, here we quantified mRNA-levels of respective potential mitochondrial and plasma membrane Ca2+ transporters in individual, choline-acetyltransferase (ChAT) positive hMNs from wildtype (WT) and endstage SOD1G93A mice, by combining UV laser microdissection with RT-qPCR techniques, and specific data normalization. As ChAT cDNA levels as well as cDNA and genomic DNA levels of the mitochondrially encoded NADH dehydrogenase ND1 were not different between hMNs from WT and endstage SOD1G93A mice, these genes were used to normalize hMN-specific mRNA-levels of plasma membrane and mitochondrial Ca2+ transporters, respectively. We detected about 2-fold higher levels of the mitochondrial Ca2+ transporters MCU/MICU1, Letm1, and UCP2 in remaining hMNs from endstage SOD1G93A mice. These higher expression-levels of mitochondrial Ca2+ transporters in individual hMNs were not associated with a respective increase in number of mitochondrial genomes, as evident from hMN specific ND1 DNA quantification. Normalized mRNA-levels for the plasma membrane Na+/Ca2+ exchanger NCX1 were also about 2-fold higher in hMNs from SOD1G93A mice. Thus, pharmacological stimulation of Ca2+ transporters in highly vulnerable hMNs might offer a neuroprotective strategy for ALS.
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Affiliation(s)
- Tobias Mühling
- Department of Applied Physiology, Institute of Applied Physiology, Ulm University Ulm, Germany
| | - Johanna Duda
- Department of Applied Physiology, Institute of Applied Physiology, Ulm University Ulm, Germany
| | | | | | - Birgit Liss
- Department of Applied Physiology, Institute of Applied Physiology, Ulm University Ulm, Germany
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17
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Abstract
Mechanosensory hair cells are vulnerable to environmental insult, resulting in hearing and balance disorders. We demonstrate that directional compartmental flow of intracellular Ca(2+) underlies death in zebrafish lateral line hair cells after exposure to aminoglycoside antibiotics, a well characterized hair cell toxin. Ca(2+) is mobilized from the ER and transferred to mitochondria via IP3 channels with little cytoplasmic leakage. Pharmacological agents that shunt ER-derived Ca(2+) directly to cytoplasm mitigate toxicity, indicating that high cytoplasmic Ca(2+) levels alone are not cytotoxic. Inhibition of the mitochondrial transition pore sensitizes hair cells to the toxic effects of aminoglycosides, contrasting with current models of excitotoxicity. Hair cells display efficient ER-mitochondrial Ca(2+) flow, suggesting that tight coupling of these organelles drives mitochondrial activity under physiological conditions at the cost of increased susceptibility to toxins.
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18
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Barrett EF, Barrett JN, David G. Dysfunctional mitochondrial Ca(2+) handling in mutant SOD1 mouse models of fALS: integration of findings from motor neuron somata and motor terminals. Front Cell Neurosci 2014; 8:184. [PMID: 25071445 PMCID: PMC4085874 DOI: 10.3389/fncel.2014.00184] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/16/2014] [Indexed: 01/01/2023] Open
Abstract
Abundant evidence indicates that mitochondrial dysfunction and Ca(2+) dysregulation contribute to the muscle denervation and motor neuron death that occur in mouse models of familial amyotrophic lateral sclerosis (fALS). This perspective considers measurements of mitochondrial function and Ca(2+) handling made in both motor neuron somata and motor nerve terminals of SOD1-G93A mice at different disease stages. These complementary studies are integrated into a model of how mitochondrial dysfunction disrupts handling of stimulation-induced Ca(2+) loads in presymptomatic and end-stages of this disease. Also considered are possible mechanisms underlying the findings that some treatments that preserve motor neuron somata fail to postpone degeneration of motor axons and terminals.
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Affiliation(s)
- Ellen F Barrett
- Department of Physiology and Biophysics, and Neuroscience Program, University of Miami Miller School of Medicine Miami, FL, USA
| | - John N Barrett
- Department of Physiology and Biophysics, and Neuroscience Program, University of Miami Miller School of Medicine Miami, FL, USA
| | - Gavriel David
- Department of Physiology and Biophysics, and Neuroscience Program, University of Miami Miller School of Medicine Miami, FL, USA
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Rocha MC, Pousinha PA, Correia AM, Sebastião AM, Ribeiro JA. Early changes of neuromuscular transmission in the SOD1(G93A) mice model of ALS start long before motor symptoms onset. PLoS One 2013; 8:e73846. [PMID: 24040091 PMCID: PMC3764017 DOI: 10.1371/journal.pone.0073846] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 07/24/2013] [Indexed: 12/24/2022] Open
Abstract
Amyotrophic lateral sclerosis is characterized by a progressive degeneration of the corticospinal tract motor neurons. Growing evidence suggests that degeneration may begin at the distal axon proceeding in a dying-back pattern. It seemed therefore of interest to investigate synaptic transmission at the neuromuscular junction (NMJ) in pre- and symptomatic phases of the disease. Endplate potentials (EPPs), miniatures endplate potentials (MEPPs) and giant MEPPs (GMEPPs) were recorded from innervated diaphragm muscle fibers from 4-6 and 12-15 weeks-old SOD1(G93A) mice and non-transgenic aged-matched littermates (WT). In the pre-symptomatic phase, SOD1(G93A) mice exhibited a significant increase in the mean amplitude of EPPs together with an increase in the mean quantal content of EPPs, suggesting that more acetylcholine is being released into the synaptic cleft. SOD1(G93A) mice presented a higher frequency of GMEPPs, suggestive of intracellular Ca(2+) deregulation in nerve terminals. The increase in the mean amplitude of MEPPs and the decreased mean rise-time of MEPPs in SOD1(G93A) mice point to post-synaptic related changes. In the symptomatic phase, electrophysiological data showed evidence for two NMJ groups in SOD1(G93A) mice: SOD1a and SOD1b. SOD1a group presented reduced mean amplitude of both EPPs and MEPPs. The mean rise-time of MEPPs was increased, when compared to WT and to SOD1b group, indicating impairments in the neuromuscular transmission. In contrast, the neuromuscular transmission of SOD1b group was not different from age-matched WT nor pre-symptomatic SOD1(G93A) mice, being somehow in between both groups. Altogether these results show that the neuromuscular transmission of SOD1(G93A) mice is enhanced in the pre-symptomatic phase. In the symptomatic phase our results are consistent with the hypothesis that the diaphragm of SOD1(G93A) mice is undergoing cycles of denervation/re-innervation supported by mixed neuromuscular junction populations. These early changes in the neuromuscular transmission of SOD1(G93A) mice suggest that the ALS associated events start long before symptoms onset.
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Affiliation(s)
- Mariana C. Rocha
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Paula A. Pousinha
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Alexandra M. Correia
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
- Museu Nacional de História Natural e da Ciência, University of Lisbon, Lisbon, Portugal
| | - Ana M. Sebastião
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Joaquim A. Ribeiro
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
- * E-mail:
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20
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Fuchs A, Kutterer S, Mühling T, Duda J, Schütz B, Liss B, Keller BU, Roeper J. Selective mitochondrial Ca2+ uptake deficit in disease endstage vulnerable motoneurons of the SOD1G93A mouse model of amyotrophic lateral sclerosis. J Physiol 2013; 591:2723-45. [PMID: 23401612 PMCID: PMC3678052 DOI: 10.1113/jphysiol.2012.247981] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 02/04/2013] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that targets some somatic motoneuron populations, while others, e.g. those of the oculomotor system, are spared. The pathophysiological basis of this pattern of differential vulnerability, which is preserved in a transgenic mouse model of amyotrophic lateral sclerosis (SOD1(G93A)), and the mechanism of neurodegeneration in general are unknown. Hyperexcitability and calcium dysregulation have been proposed by others on the basis of data from juvenile mice that are, however, asymptomatic. No studies have been done with symptomatic mice following disease progression to the disease endstage. Here, we developed a new brainstem slice preparation for whole-cell patch-clamp recordings and single cell fura-2 calcium imaging to study motoneurons in adult wild-type and SOD1(G93A) mice up to disease endstage. We analysed disease-stage-dependent electrophysiological properties and intracellular Ca(2+) handling of vulnerable hypoglossal motoneurons in comparison to resistant oculomotor neurons. Thereby, we identified a transient hyperexcitability in presymptomatic but not in endstage vulnerable motoneurons. Additionally, we revealed a remodelling of intracellular Ca(2+) clearance within vulnerable but not resistant motoneurons at disease endstage characterised by a reduction of uniporter-dependent mitochondrial Ca(2+) uptake and enhanced Ca(2+) extrusion across the plasma membrane. Our study challenged the notion that hyperexcitability is a direct cause of neurodegeneration in SOD1(G93A) mice, but molecularly identified a Ca(2+) clearance deficit in motoneurons and an adaptive Ca(2+) handling strategy that might be targeted by future therapeutic strategies.
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Affiliation(s)
- Andrea Fuchs
- Mammalian Locomotor Laboratory, Department of Neuroscience, Karolinska Institutet, Retzius Väg 8, 17177 Stockholm, Sweden.
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21
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Tarasov AI, Semplici F, Ravier MA, Bellomo EA, Pullen TJ, Gilon P, Sekler I, Rizzuto R, Rutter GA. The mitochondrial Ca2+ uniporter MCU is essential for glucose-induced ATP increases in pancreatic β-cells. PLoS One 2012; 7:e39722. [PMID: 22829870 PMCID: PMC3400633 DOI: 10.1371/journal.pone.0039722] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 05/25/2012] [Indexed: 01/09/2023] Open
Abstract
Glucose induces insulin release from pancreatic β-cells by stimulating ATP synthesis, membrane depolarisation and Ca2+ influx. As well as activating ATP-consuming processes, cytosolic Ca2+ increases may also potentiate mitochondrial ATP synthesis. Until recently, the ability to study the role of mitochondrial Ca2+ transport in glucose-stimulated insulin secretion has been hindered by the absence of suitable approaches either to suppress Ca2+ uptake into these organelles, or to examine the impact on β-cell excitability. Here, we have combined patch-clamp electrophysiology with simultaneous real-time imaging of compartmentalised changes in Ca2+ and ATP/ADP ratio in single primary mouse β-cells, using recombinant targeted (Pericam or Perceval, respectively) as well as entrapped intracellular (Fura-Red), probes. Through shRNA-mediated silencing we show that the recently-identified mitochondrial Ca2+ uniporter, MCU, is required for depolarisation-induced mitochondrial Ca2+ increases, and for a sustained increase in cytosolic ATP/ADP ratio. By contrast, silencing of the mitochondrial Na+-Ca2+ exchanger NCLX affected the kinetics of glucose-induced changes in, but not steady state values of, cytosolic ATP/ADP. Exposure to gluco-lipotoxic conditions delayed both mitochondrial Ca2+ uptake and cytosolic ATP/ADP ratio increases without affecting the expression of either gene. Mitochondrial Ca2+ accumulation, mediated by MCU and modulated by NCLX, is thus required for normal glucose sensing by pancreatic β-cells, and becomes defective in conditions mimicking the diabetic milieu.
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Affiliation(s)
- Andrei I. Tarasov
- Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, United Kingdom
| | - Francesca Semplici
- Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, United Kingdom
| | - Magalie A. Ravier
- Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, United Kingdom
- Institut de Génomique Fonctionnelle, INSERM U661, CNRS UMR5203, Université Montpellier I et II, Montpellier, France
| | - Elisa A. Bellomo
- Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, United Kingdom
| | - Timothy J. Pullen
- Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, United Kingdom
| | - Patrick Gilon
- Pole of Endocrinology, Diabetes and Nutrition, Faculty of Medicine, Université Catholique de Louvain, Brussels, Belgium
| | - Israel Sekler
- Department of Physiology, Faculty of Health Sciences, Ben Gurion University, Beer-Sheva, Israel
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Guy A. Rutter
- Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, United Kingdom
- * E-mail:
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22
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Abstract
A growing body of evidence suggests that mitochondrial dysfunctions play a crucial role in the pathogenesis of various neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting both upper and lower motor neurons. Although ALS is predominantly a sporadic disease, approximately 10% of cases are familial. The most frequent familial form is caused by mutations in the gene encoding Cu/Zn superoxide dismutase 1 (SOD1). A dominant toxic gain of function of mutant SOD1 has been considered as the cause of the disease and mitochondria are thought to be key players in the pathogenesis. However, the exact nature of the link between mutant SOD1 and mitochondrial dysfunctions remains to be established. Here, we briefly review the evidence for mitochondrial dysfunctions in familial ALS and discuss a possible link between mutant SOD1 and mitochondrial dysfunction.
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Mitochondria in motor nerve terminals: function in health and in mutant superoxide dismutase 1 mouse models of familial ALS. J Bioenerg Biomembr 2012; 43:581-6. [PMID: 22089637 DOI: 10.1007/s10863-011-9392-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
Mitochondria contribute to neuronal function not only via their ability to generate ATP, but also via their ability to buffer large Ca(2+) loads. This review summarizes evidence that mitochondrial Ca(2+) sequestration is especially important for sustaining the function of vertebrate motor nerve terminals during repetitive stimulation. Motor terminal mitochondria can sequester large amounts of Ca(2+) because they have mechanisms for limiting both the mitochondrial depolarization and the increase in matrix free [Ca(2+)] associated with Ca(2+) influx. In mice expressing mutations of human superoxide dismutase -1 (SOD1) that cause some cases of familial amyotrophic lateral sclerosis (fALS), motor terminals degenerate well before the death of motor neuron cell bodies. This review presents evidence for early and progressive mitochondrial dysfunction in motor terminals of mutant SOD1 mice (G93A, G85R). This dysfunction would impair mitochondrial ability to sequester stimulation-associated Ca(2+) loads, and thus likely contributes to the early degeneration of motor terminals.
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24
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Abstract
Amyotrophic lateral sclerosis (ALS) is the third most common human adult-onset neurodegenerative disease. Some forms of ALS are inherited, and disease-causing genes have been identified. Nevertheless, the mechanisms of neurodegeneration in ALS are unresolved. Genetic, biochemical, and morphological analyses of human ALS as well as cell and animal models of ALS reveal that mitochondria could have roles in this neurodegeneration. The varied functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and overlying genetic variations. Changes occur in mitochondrial respiratory chain enzymes and mitochondrial programmed cell death proteins in ALS. Transgenic mouse models of ALS reveal possible principles governing the biology of neurodegeneration that implicate mitochondria and the mitochondrial permeability transition pore. This paper reviews how mitochondrial pathobiology might contribute to the mechanisms of neurodegeneration in ALS.
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Affiliation(s)
- Lee J Martin
- Department of Pathology, Division of Neuropathology, and the Pathobiology Graduate Program, Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205-2196, USA.
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25
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Mitochondrial dynamics and bioenergetic dysfunction is associated with synaptic alterations in mutant SOD1 motor neurons. J Neurosci 2012; 32:229-42. [PMID: 22219285 DOI: 10.1523/jneurosci.1233-11.2012] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mutations in Cu,Zn superoxide dismutase (SOD1) cause familial amyotrophic lateral sclerosis (FALS), a rapidly fatal motor neuron disease. Mutant SOD1 has pleiotropic toxic effects on motor neurons, among which mitochondrial dysfunction has been proposed as one of the contributing factors in motor neuron demise. Mitochondria are highly dynamic in neurons; they are constantly reshaped by fusion and move along neurites to localize at sites of high-energy utilization, such as synapses. The finding of abnormal mitochondria accumulation in neuromuscular junctions, where the SOD1-FALS degenerative process is though to initiate, suggests that impaired mitochondrial dynamics in motor neurons may be involved in pathogenesis. We addressed this hypothesis by live imaging microscopy of photo-switchable fluorescent mitoDendra in transgenic rat motor neurons expressing mutant or wild-type human SOD1. We demonstrate that mutant SOD1 motor neurons have impaired mitochondrial fusion in axons and cell bodies. Mitochondria also display selective impairment of retrograde axonal transport, with reduced frequency and velocity of movements. Fusion and transport defects are associated with smaller mitochondrial size, decreased mitochondrial density, and defective mitochondrial membrane potential. Furthermore, mislocalization of mitochondria at synapses among motor neurons, in vitro, correlates with abnormal synaptic number, structure, and function. Dynamics abnormalities are specific to mutant SOD1 motor neuron mitochondria, since they are absent in wild-type SOD1 motor neurons, they do not involve other organelles, and they are not found in cortical neurons. Together, these results suggest that impaired mitochondrial dynamics may contribute to the selective degeneration of motor neurons in SOD1-FALS.
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26
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Biology of mitochondria in neurodegenerative diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 107:355-415. [PMID: 22482456 DOI: 10.1016/b978-0-12-385883-2.00005-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal degeneration in these familial diseases, and in the more common idiopathic (sporadic) diseases, are unresolved. Genetic, biochemical, and morphological analyses of human AD, PD, and ALS, as well as their cell and animal models, reveal that mitochondria could have roles in this neurodegeneration. The varied functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and the overlying genetic variations. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial programmed cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This chapter reviews several aspects of mitochondrial biology and how mitochondrial pathobiology might contribute to the mechanisms of neurodegeneration in AD, PD, and ALS.
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27
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Naumenko N, Pollari E, Kurronen A, Giniatullina R, Shakirzyanova A, Magga J, Koistinaho J, Giniatullin R. Gender-Specific Mechanism of Synaptic Impairment and Its Prevention by GCSF in a Mouse Model of ALS. Front Cell Neurosci 2011; 5:26. [PMID: 22180738 PMCID: PMC3238042 DOI: 10.3389/fncel.2011.00026] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 11/25/2011] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of motoneurons which progresses differentially in males and females for unknown reason. Here we measured gender differences in pre- and post-synaptic parameters of the neuromuscular transmission in a mutant G93A-SOD1 mouse model of ALS. Using intracellular microelectrode technique we recorded miniature and evoked end-plate potentials (MEPPs and EPPs) in the diaphragm muscle of G93A-SOD1 mice at early symptomatic stage. While no evident alterations in the amplitude of MEPPs was observed in male or female G93A-SOD1 mice, G93A-SOD1 mice displayed dramatically reduced probability of spontaneous acetylcholine release. In contrast, the EPPs evoked by single nerve stimulation had unchanged amplitude and quantal content. In males, but not females, this was accompanied by reduced readily releasable transmitter pool. Transmitter release in both sexes was sensitive to the inhibitory action of reactive oxygen species (ROS), but the production of ROS was increased in the spinal cords of male but not female G93A-SOD1 mice. Treatment with granulocyte colony stimulating factor (GCSF), which we previously found to be beneficial in males, attenuated the increased ROS production indicating involvement of the antioxidant mechanisms and improved ALS-induced synaptic dysfunctions only in males being ineffective in females. Consistent with our findings at synaptic level, GCSF did not change the survival rate or motor performance of female ALS mice. In summary, neuromuscular transmission in ALS mice is impaired at early symptomatic stage when a dramatic presynaptic decline of spontaneous release occurs. Beneficial effects of GCSF treatment on survival in males may be explained by GCSF-improved presynaptic functions in male G93A-SOD1 mice. Development of efficient treatment strategies for ALS may need to be directed in a gender-specific manner.
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Affiliation(s)
- Nikolay Naumenko
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland Kuopio, Finland
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Quinlan KA. Links between electrophysiological and molecular pathology of amyotrophic lateral sclerosis. Integr Comp Biol 2011; 51:913-25. [PMID: 21989221 DOI: 10.1093/icb/icr116] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Multiple deficits have been described in amyotrophic lateral sclerosis (ALS), from the first changes in normal functioning of the motoneurons and glia to the eventual loss of spinal and cortical motoneurons. In this review, current results, including changes in size, and electrical properties of motoneurons, glutamate excitotoxicity, calcium buffering, deficits in mitochondrial and cellular transport, impediments to proteostasis which lead to stress of the endoplasmic reticulum (ER), and glial contributions to motoneuronal vulnerability are recapitulated. Results are mainly drawn from the mutant SOD1 mouse model of ALS, and emphasis is placed on early changes that precede the onset of symptoms and the interplay between molecular and electrical processes.
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Affiliation(s)
- Katharina A Quinlan
- Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
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Cozzolino M, Carrì MT. Mitochondrial dysfunction in ALS. Prog Neurobiol 2011; 97:54-66. [PMID: 21827820 DOI: 10.1016/j.pneurobio.2011.06.003] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 06/13/2011] [Accepted: 06/14/2011] [Indexed: 12/11/2022]
Abstract
In the present article, we review the many facets of mitochondrial dysfunction in amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease due to loss of upper motor neurons in cerebral cortex and lower motor neurons in brainstem and spinal cord. Accumulating evidence from recent studies suggests that the many, interconnected facets of mitochondrial dysfunction may play a more significant role in the etiopathogenesis of this disorder than previously thought. This notion stems from our expanding knowledge of the complex physiology of mitochondria and of alteration of their properties that might confer an intrinsic susceptibility to long-lived, post-mitotic motor neurons to energy deficit, calcium mishandling and oxidative stress. The wealth of evidence implicating mitochondrial dysfunction as a major event in the pathology of ALS has prompted new studies aimed to the development of new mitochondria-targeted therapies. However, it is now clear that drugs targeting more than one aspect of mitochondrial dysfunction are needed to fight this devastating disease.
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Affiliation(s)
- Mauro Cozzolino
- Fondazione Santa Lucia IRCCS, c/o CERC, Via del Fosso di Fiorano 64, 00143 Rome, Italy
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Duffy LM, Chapman AL, Shaw PJ, Grierson AJ. Review: The role of mitochondria in the pathogenesis of amyotrophic lateral sclerosis. Neuropathol Appl Neurobiol 2011; 37:336-52. [DOI: 10.1111/j.1365-2990.2011.01166.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Rasola A, Bernardi P. Mitochondrial permeability transition in Ca(2+)-dependent apoptosis and necrosis. Cell Calcium 2011; 50:222-33. [PMID: 21601280 DOI: 10.1016/j.ceca.2011.04.007] [Citation(s) in RCA: 396] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 04/22/2011] [Accepted: 04/28/2011] [Indexed: 12/25/2022]
Abstract
A variety of stimuli utilize an increase of cytosolic free Ca(2+) concentration as a second messenger to transmit signals, through Ca(2+) release from the endoplasmic reticulum or opening of plasma membrane Ca(2+) channels. Mitochondria contribute to the tight spatiotemporal control of this process by accumulating Ca(2+), thus shaping the return of cytosolic Ca(2+) to resting levels. The rise of mitochondrial matrix free Ca(2+) concentration stimulates oxidative metabolism; yet, in the presence of a variety of sensitizing factors of pathophysiological relevance, the matrix Ca(2+) increase can also lead to opening of the permeability transition pore (PTP), a high conductance inner membrane channel. While transient openings may serve the purpose of providing a fast Ca(2+) release mechanism, persistent PTP opening is followed by deregulated release of matrix Ca(2+), termination of oxidative phosphorylation, matrix swelling with inner membrane unfolding and eventually outer membrane rupture with release of apoptogenic proteins and cell death. Thus, a rise in mitochondrial Ca(2+) can convey both apoptotic and necrotic death signals by inducing opening of the PTP. Understanding the signalling networks that govern changes in mitochondrial free Ca(2+) concentration, their interplay with Ca(2+) signalling in other subcellular compartments, and regulation of PTP has important implications in the fine comprehension of the main biological routines of the cell and in disease pathogenesis.
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Affiliation(s)
- Andrea Rasola
- Department of Biomedical Sciences and CNR Institute of Neuroscience, University of Padova, Italy.
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Zhu YB, Sheng ZH. Increased axonal mitochondrial mobility does not slow amyotrophic lateral sclerosis (ALS)-like disease in mutant SOD1 mice. J Biol Chem 2011; 286:23432-40. [PMID: 21518771 DOI: 10.1074/jbc.m111.237818] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Reduced axonal mitochondrial transport has been observed in major neurodegenerative diseases, including fALS patients and SOD1(G93A) mice. However, it is unclear whether this defect plays a critical role in axonal degeneration or simply reflects sequelae of general transport alteration. Using genetic mouse models combined with time-lapse imaging of live neurons, we previously discovered that axon-targeted syntaphilin (SNPH) acts as a docking receptor specific for axonal mitochondria. Deletion of the snph gene in mice results in a substantially higher proportion of axonal mitochondria in the mobile state without any effect on the transport of other axonal organelles. Here we address whether increased (rescued) axonal mitochondrial mobility changes the disease course by crossing fALS-linked transgenic SOD1(G93A) and snph(-/-) knock-out mice. We found that a 2-fold increase in axonal mitochondrial mobility in SOD1(G93A)/snph(-/-) mice did not affect the onset of ALS-like symptoms. Both SOD1(G93A) and SOD1(G93A)/snph(-/-) mice exhibit similar weight loss, deterioration in motor function and motor neuron loss, significant gliosis, and a lifespan of 152-154 days. Thus, for the first time, our study provides genetic and pathological evidence that the impairment of mitochondrial transport seen in SOD1(G93A) mice plays a minimal role in the rapid-onset of fALS-linked pathology.
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Affiliation(s)
- Yi-Bing Zhu
- Synaptic Function Section, The Porter Neuroscience Research Center, NINDS, National Institutes of Health, Bethesda, Maryland 20892-3706, USA
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Repetitive nerve stimulation transiently opens the mitochondrial permeability transition pore in motor nerve terminals of symptomatic mutant SOD1 mice. Neurobiol Dis 2011; 42:381-90. [PMID: 21310237 DOI: 10.1016/j.nbd.2011.01.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 12/17/2010] [Accepted: 01/28/2011] [Indexed: 11/20/2022] Open
Abstract
Mitochondria in motor nerve terminals temporarily sequester large Ca(2+) loads during repetitive stimulation. In wild-type mice this Ca(2+) uptake produces a small (<5 mV), transient depolarization of the mitochondrial membrane potential (Ψ(m), motor nerve stimulated at 100 Hz for 5s). We demonstrate that this stimulation-induced Ψ(m) depolarization attains much higher amplitudes in motor terminals of symptomatic mice expressing the G93A or G85R mutation of human superoxide dismutase 1 (SOD1), models of familial amyotrophic lateral sclerosis (fALS). These large Ψ(m) depolarizations decayed slowly and incremented with successive stimulus trains. Additional Ψ(m) depolarizations occurred that were not synchronized with stimulation. These large Ψ(m) depolarizations were reduced (a) by cyclosporin A (CsA, 1-2 μM), which inhibits opening of the mitochondrial permeability transition pore (mPTP), or (b) by replacing bath Ca(2+) with Sr(2+), which enters motor terminals and mitochondria but does not support mPTP opening. These results are consistent with the hypothesis that the large Ψ(m) depolarizations evoked by repetitive stimulation in motor terminals of symptomatic fALS mice result from mitochondrial dysfunction that increases the likelihood of transient mPTP opening during Ca(2+) influx. Such mPTP openings, a sign of mitochondrial stress, would disrupt motor terminal handling of Ca(2+) loads and might thereby contribute to motor terminal degeneration in fALS mice. Ψ(m) depolarizations resembling those in symptomatic fALS mice could be elicited in wild-type mice following a 0.5-1h exposure to diamide (200 μM), which produces an oxidative stress, but these depolarizations were not reduced by CsA.
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Lenzken SC, Romeo V, Zolezzi F, Cordero F, Lamorte G, Bonanno D, Biancolini D, Cozzolino M, Pesaresi MG, Maracchioni A, Sanges R, Achsel T, Carrì MT, Calogero RA, Barabino SM. Mutant SOD1 and mitochondrial damage alter expression and splicing of genes controlling neuritogenesis in models of neurodegeneration. Hum Mutat 2011; 32:168-82. [DOI: 10.1002/humu.21394] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 09/24/2010] [Indexed: 12/13/2022]
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Zhang Z, Nguyen KT, Barrett EF, David G. Vesicular ATPase inserted into the plasma membrane of motor terminals by exocytosis alkalinizes cytosolic pH and facilitates endocytosis. Neuron 2011; 68:1097-108. [PMID: 21172612 DOI: 10.1016/j.neuron.2010.11.035] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2010] [Indexed: 01/29/2023]
Abstract
Key components of vesicular neurotransmitter release, such as Ca(2+) influx and membrane recycling, are affected by cytosolic pH. We measured the pH-sensitive fluorescence of Yellow Fluorescent Protein transgenically expressed in mouse motor nerve terminals, and report that Ca(2+) influx elicited by action potential trains (12.5-100 Hz) evokes a biphasic pH change: a brief acidification (∼ 13 nM average peak increase in [H(+)]), followed by a prolonged alkalinization (∼ 30 nM peak decrease in [H(+)]) that outlasts the stimulation train. The alkalinization is selectively eliminated by blocking vesicular exocytosis with botulinum neurotoxins, and is prolonged by the endocytosis-inhibitor dynasore. Blocking H(+) pumping by vesicular H(+)-ATPase (with folimycin or bafilomycin) suppresses stimulation-induced alkalinization and reduces endocytotic uptake of FM1-43. These results suggest that H(+)-ATPase, known to transfer cytosolic H(+) into prefused vesicles, continues to extrude cytosolic H(+) after being exocytotically incorporated into the plasma membrane. The resulting cytosolic alkalinization may facilitate vesicular endocytosis.
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Affiliation(s)
- Zhongsheng Zhang
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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36
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Martin LJ. An approach to experimental synaptic pathology using green fluorescent protein-transgenic mice and gene knockout mice to show mitochondrial permeability transition pore-driven excitotoxicity in interneurons and motoneurons. Toxicol Pathol 2011; 39:220-33. [PMID: 21378209 PMCID: PMC3517994 DOI: 10.1177/0192623310389475] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Researchers used transgenic mice expressing enhanced-green fluorescent protein (eGFP) driven by either the glycine transporter-2 gene promoter to specifically visualize glycinergic interneurons or the homeobox-9 (Hb9) gene promoter to visualize motoneurons for assessing their vulnerabilities to excitotoxins in vivo. Stereotaxic excitotoxic lesions were made in adult male and female mouse lumbar spinal cord with the specific N-methyl-D-aspartate (NMDA) receptor agonist quinolinic acid (QA) and the non-NMDA ion channel glutamate receptor agonist kainic acid (KA). QA and KA induced large-scale degeneration of glycinergic interneurons in spinal cord. Glycinergic interneurons were more sensitive than motoneurons to NMDA receptor-mediated and non-NMDA glutamate receptor-mediated excitotoxicity. Outcome after spinal cord excitotoxicity was gender-dependent, with males showing greater sensitivity than females. Excitotoxic degeneration of spinal interneurons resembled apoptosis, while motoneuron degeneration appeared non-apoptotic. Perikaryal mitochondrial accumulation was antecedent to both NMDA and non-NMDA receptor-mediated excitotoxic stimulation of interneurons and motoneurons. Genetic ablation of cyclophilin D, a regulator of the mitochondrial permeability transition pore (mPTP), protected both interneurons and motoneurons from excitotoxicity. The results demonstrate in adult mouse spinal cord that glycinergic interneurons are more sensitive than motoneurons to excitotoxicity that stimulates mitochondrial accumulation, and that the mPTP has pro-death functions mediating apoptotic and non-apoptotic neuronal degeneration in vivo.
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Affiliation(s)
- Lee J Martin
- Department of Pathology, 558 Ross Building, 720 Rutland Avenue, Baltimore, MD 21205-2196, USA.
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Liang HL, Sedlic F, Bosnjak Z, Nilakantan V. SOD1 and MitoTEMPO partially prevent mitochondrial permeability transition pore opening, necrosis, and mitochondrial apoptosis after ATP depletion recovery. Free Radic Biol Med 2010; 49:1550-60. [PMID: 20736062 PMCID: PMC3863116 DOI: 10.1016/j.freeradbiomed.2010.08.018] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 07/27/2010] [Accepted: 08/16/2010] [Indexed: 12/29/2022]
Abstract
Generation of excessive reactive oxygen species (ROS) leads to mitochondrial dysfunction, apoptosis, and necrosis in renal ischemia-reperfusion (IR) injury. Previously we showed that lentiviral vector-mediated overexpression of superoxide dismutase-1 (SOD1) in proximal tubular epithelial cells (LLC-PK(1)) reduced cytotoxicity in an in vitro model of IR injury. Here, we examined the effects of SOD1 overexpression on mitochondrial signaling after ATP depletion-recovery (ATP-DR). To examine the role of mitochondrial ROS, a subset of cells was treated with the mitochondrial antioxidant MitoTEMPO. ATP-DR-mediated increase in mitochondrial calcium, loss of mitochondrial membrane potential, and increase in mitochondrial permeability transition pore (MPTP) were attenuated by SOD1 and MitoTEMPO (P<0.01). SOD1 prevented ATP-DR-induced mitochondrial Bax translocation, although the release of proapoptotic proteins from mitochondria was not prevented by SOD1 alone and required the presence of both SOD1 and MitoTEMPO. SOD1 suppressed the increase in c-jun phosphorylation, suggesting that JNK signaling regulates Bax translocation to mitochondria via ROS. ATP-DR-mediated changes in MPTP and mitochondrial signaling increased necrosis and apoptosis, both of which were partially attenuated by SOD1 and MitoTEMPO. These studies show that SOD1 and MitoTEMPO preserve mitochondrial integrity and attenuate ATP-DR-mediated necrosis and apoptosis.
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Affiliation(s)
- Huan Ling Liang
- Division of Transplant Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Kidney Disease Center, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Filip Sedlic
- Departments of Anesthesiology and Physiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Zeljko Bosnjak
- Departments of Anesthesiology and Physiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Vani Nilakantan
- Division of Transplant Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Kidney Disease Center, Medical College of Wisconsin, Milwaukee, WI 53226
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Misfolded mutant SOD1 directly inhibits VDAC1 conductance in a mouse model of inherited ALS. Neuron 2010; 67:575-87. [PMID: 20797535 DOI: 10.1016/j.neuron.2010.07.019] [Citation(s) in RCA: 235] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2010] [Indexed: 02/07/2023]
Abstract
Mutations in superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS), a neurodegenerative disease characterized by loss of motor neurons. With conformation-specific antibodies, we now demonstrate that misfolded mutant SOD1 binds directly to the voltage-dependent anion channel (VDAC1), an integral membrane protein imbedded in the outer mitochondrial membrane. This interaction is found on isolated spinal cord mitochondria and can be reconstituted with purified components in vitro. ADP passage through the outer membrane is diminished in spinal mitochondria from mutant SOD1-expressing ALS rats. Direct binding of mutant SOD1 to VDAC1 inhibits conductance of individual channels when reconstituted in a lipid bilayer. Reduction of VDAC1 activity with targeted gene disruption is shown to diminish survival by accelerating onset of fatal paralysis in mice expressing the ALS-causing mutation SOD1(G37R). Taken together, our results establish a direct link between misfolded mutant SOD1 and mitochondrial dysfunction in this form of inherited ALS.
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Kawamata H, Manfredi G. Mitochondrial dysfunction and intracellular calcium dysregulation in ALS. Mech Ageing Dev 2010; 131:517-26. [PMID: 20493207 PMCID: PMC2933290 DOI: 10.1016/j.mad.2010.05.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 05/05/2010] [Accepted: 05/12/2010] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder that affects the aging population. A progressive loss of motor neurons in the spinal cord and brain leads to muscle paralysis and death. As in other common neurodegenerative diseases, aging-related mitochondrial dysfunction is increasingly being considered among the pathogenic factors. Mitochondria are critical for cell survival: they provide energy to the cell, buffer intracellular calcium, and regulate apoptotic cell death. Whether mitochondrial abnormalities are a trigger or a consequence of the neurodegenerative process and the mechanisms whereby mitochondrial dysfunction contributes to disease are not clear yet. Calcium homeostasis is a major function of mitochondria in neurons, and there is ample evidence that intracellular calcium is dysregulated in ALS. The impact of mitochondrial dysfunction on intracellular calcium homeostasis and its role in motor neuron demise are intriguing issues that warrants in depth discussion. Clearly, unraveling the causal relationship between mitochondrial dysfunction, calcium dysregulation, and neuronal death is critical for the understanding of ALS pathogenesis. In this review, we will outline the current knowledge of various aspects of mitochondrial dysfunction in ALS, with a special emphasis on the role of these abnormalities on intracellular calcium handling.
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Affiliation(s)
- Hibiki Kawamata
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10065, USA
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Pedrini S, Sau D, Guareschi S, Bogush M, Brown RH, Naniche N, Kia A, Trotti D, Pasinelli P. ALS-linked mutant SOD1 damages mitochondria by promoting conformational changes in Bcl-2. Hum Mol Genet 2010; 19:2974-86. [PMID: 20460269 PMCID: PMC2901139 DOI: 10.1093/hmg/ddq202] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In mutant superoxide dismutase (SOD1)-linked amyotrophic lateral sclerosis (ALS), accumulation of misfolded mutant SOD1 in spinal cord mitochondria is thought to cause mitochondrial dysfunction. Whether mutant SOD1 is toxic per se or whether it damages the mitochondria through interactions with other mitochondrial proteins is not known. We previously identified Bcl-2 as an interacting partner of mutant SOD1 specifically in spinal cord, but not in liver, mitochondria of SOD1 mice and patients. We now show that mutant SOD1 toxicity relies on this interaction. Mutant SOD1 induces mitochondrial morphological changes and compromises mitochondrial membrane integrity leading to release of Cytochrome C only in the presence of Bcl-2. In cells, mouse and human spinal cord with SOD1 mutations, the binding to mutant SOD1 triggers a conformational change in Bcl-2 that results in the uncovering of its toxic BH3 domain and conversion of Bcl-2 into a toxic protein. Bcl-2 carrying a mutagenized, non-toxic BH3 domain fails to support mutant SOD1 mitochondrial toxicity. The identification of Bcl-2 as a specific target and active partner in mutant SOD1 mitochondrial toxicity suggests new therapeutic strategies to inhibit the formation of the toxic mutant SOD1/Bcl-2 complex and to prevent mitochondrial damage in ALS.
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Affiliation(s)
- Steve Pedrini
- Frances and Joseph Weinberg Unit for ALS Research, Farber Institute for Neurosciences, Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Abstract
Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal cell death are unresolved. Morphological, biochemical, genetic, as well as cell and animal model studies reveal that mitochondria could have roles in this neurodegeneration. The functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and overlying genetic variations, triggering neurodegeneration according to a cell death matrix theory. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in putative mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This review summarizes how mitochondrial pathobiology might contribute to neuronal death in AD, PD, and ALS and could serve as a target for drug therapy.
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Gellerich FN, Gizatullina Z, Trumbeckaite S, Nguyen HP, Pallas T, Arandarcikaite O, Vielhaber S, Seppet E, Striggow F. The regulation of OXPHOS by extramitochondrial calcium. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1018-27. [PMID: 20144582 DOI: 10.1016/j.bbabio.2010.02.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 02/01/2010] [Accepted: 02/02/2010] [Indexed: 11/29/2022]
Abstract
Despite extensive research, the regulation of mitochondrial function is still not understood completely. Ample evidence shows that cytosolic Ca2+ has a strategic task in co-ordinating the cellular work load and the regeneration of ATP by mitochondria. Currently, the paradigmatic view is that Cacyt2+ taken up by the Ca2+ uniporter activates the matrix enzymes pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and isocitrate dehydrogenase. However, we have recently found that Ca2+ regulates the glutamate-dependent state 3 respiration by the supply of glutamate to mitochondria via aralar, a mitochondrial glutamate/aspartate carrier. Since this activation is not affected by ruthenium red, glutamate transport into mitochondria is controlled exclusively by extramitochondrial Ca2+. Therefore, this discovery shows that besides intramitochondrial also extramitochondrial Ca2+ regulates oxidative phosphorylation. This new mechanism acts as a mitochondrial "gas pedal", supplying the OXPHOS with substrate on demand. These results are in line with recent findings of Satrustegui and Palmieri showing that aralar as part of the malate-aspartate shuttle is involved in the Ca2+-dependent transport of reducing hydrogen equivalents (from NADH) into mitochondria. This review summarises results and evidence as well as hypothetical interpretations of data supporting the view that at the surface of mitochondria different regulatory Ca2+-binding sites exist and can contribute to cellular energy homeostasis. Moreover, on the basis of our own data, we propose that these surface Ca2+-binding sites may act as targets for neurotoxic proteins such as mutated huntingtin and others. The binding of these proteins to Ca2+-binding sites can impair the regulation by Ca2+, causing energetic depression and neurodegeneration.
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Affiliation(s)
- Frank N Gellerich
- KeyNeurotek Pharmaceuticals AG, ZENIT Technology Park, Leipziger Str. 44, D-39120 Magdeburg, Germany.
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43
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Cardoso S, Santos R, Correia S, Carvalho C, Zhu X, Lee HG, Casadesus G, Smith MA, Perry G, Moreira PI. Insulin and Insulin-Sensitizing Drugs in Neurodegeneration: Mitochondria as Therapeutic Targets. Pharmaceuticals (Basel) 2009; 2:250-286. [PMID: 27713238 PMCID: PMC3978547 DOI: 10.3390/ph2030250] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 12/21/2009] [Accepted: 12/22/2009] [Indexed: 12/13/2022] Open
Abstract
Insulin, besides its glucose lowering effects, is involved in the modulation of lifespan, aging and memory and learning processes. As the population ages, neurodegenerative disorders become epidemic and a connection between insulin signaling dysregulation, cognitive decline and dementia has been established. Mitochondria are intracellular organelles that despite playing a critical role in cellular metabolism are also one of the major sources of reactive oxygen species. Mitochondrial dysfunction, oxidative stress and neuroinflammation, hallmarks of neurodegeneration, can result from impaired insulin signaling. Insulin-sensitizing drugs such as the thiazolidinediones are a new class of synthetic compounds that potentiate insulin action in the target tissues and act as specific agonists of the peroxisome proliferator-activated receptor gamma (PPAR-γ). Recently, several PPAR agonists have been proposed as novel and possible therapeutic agents for neurodegenerative disorders. Indeed, the literature shows that these agents are able to protect against mitochondrial dysfunction, oxidative damage, inflammation and apoptosis. This review discusses the role of mitochondria and insulin signaling in normal brain function and in neurodegeneration. Furthermore, the potential protective role of insulin and insulin sensitizers in Alzheimer´s, Parkinson´s and Huntington´s diseases and amyotrophic lateral sclerosis will be also discussed.
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Affiliation(s)
- Susana Cardoso
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Renato Santos
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Sonia Correia
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Cristina Carvalho
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3000- 354 Coimbra, Portugal
| | - Xiongwei Zhu
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Hyoung-Gon Lee
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Gemma Casadesus
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mark A Smith
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - George Perry
- College of Sciences, The University of Texas at San Antonio, TX 78249, USA
| | - Paula I Moreira
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal.
- Institute of Physiology, Faculty of Medicine, University of Coimbra, 3000-354 Coimbra, Portugal.
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Zhou J, Yi J, Fu R, Liu E, Siddique T, Ríos E, Deng HX. Hyperactive intracellular calcium signaling associated with localized mitochondrial defects in skeletal muscle of an animal model of amyotrophic lateral sclerosis. J Biol Chem 2009; 285:705-12. [PMID: 19889637 DOI: 10.1074/jbc.m109.041319] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disorder characterized by degeneration of motor neurons and atrophy of skeletal muscle. Mutations in the superoxide dismutase (SOD1) gene are linked to 20% cases of inherited ALS. Mitochondrial dysfunction has been implicated in the pathogenic process, but how it contributes to muscle degeneration of ALS is not known. Here we identify a specific deficit in the cellular physiology of skeletal muscle derived from an ALS mouse model (G93A) with transgenic overexpression of the human SOD1(G93A) mutant. The G93A skeletal muscle fibers display localized loss of mitochondrial inner membrane potential in fiber segments near the neuromuscular junction. These defects occur in young G93A mice prior to disease onset. Fiber segments with depolarized mitochondria show greater osmotic stress-induced Ca(2+) release activity, which can include propagating Ca(2+) waves. These Ca(2+) waves are confined to regions of depolarized mitochondria and stop propagating shortly upon entering the regions of normal, polarized mitochondria. Uncoupling of mitochondrial membrane potential with FCCP or inhibition of mitochondrial Ca(2+) uptake by Ru360 lead to cell-wide propagation of such Ca(2+) release events. Our data reveal that mitochondria regulate Ca(2+) signaling in skeletal muscle, and loss of this capacity may contribute to the progression of muscle atrophy in ALS.
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Affiliation(s)
- Jingsong Zhou
- Department of Molecular Biophysics and Physiology, Rush University Medical School, Chicago, Illinois 60612, USA.
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Dupuis L. Oxidative stress sensitivity in ALS muscle cells. Exp Neurol 2009; 220:219-23. [PMID: 19733171 DOI: 10.1016/j.expneurol.2009.08.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 08/24/2009] [Accepted: 08/26/2009] [Indexed: 10/20/2022]
Affiliation(s)
- Luc Dupuis
- INSERM U692, Faculté de Médecine, 11 rue Humann, 67085 Strasbourg, France.
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Hayworth CR, Gonzalez-Lima F. Pre-symptomatic detection of chronic motor deficits and genotype prediction in congenic B6.SOD1(G93A) ALS mouse model. Neuroscience 2009; 164:975-85. [PMID: 19699279 DOI: 10.1016/j.neuroscience.2009.08.031] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/11/2009] [Accepted: 08/12/2009] [Indexed: 12/25/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is an incurable progressive paralytic motor neuron disease with limited therapeutic options. Since their creation by Gurney et al. (1994) [Science 264:1772-1775], transgenic superoxide dismutase-1 with glycine to alanine switch at codon 93 (SOD1(G93A)) mice have become the benchmark pre-clinical model for screening ALS therapies. Surprisingly, despite physiological, anatomical, ultrastructural and biochemical evidence of early motor system dysfunction, it has proven difficult to detect motor performance deficits in pre-symptomatic SOD1(G93A) mice. As an alternative to conventional forced motor tests, we investigated the progression of motor performance deficits in freely behaving pre-symptomatic congenic B6.SOD1(G93A) mice. We found that motor performance deficits began several weeks prior to the onset of overt clinical symptoms (postnatal day 45). More importantly, once motor performance deficits manifested, they persisted in parallel with disease progression. In addition, two physical measures of muscle girth revealed progressive hindlimb muscle atrophy that predicted genotype in individual pre-symptomatic mice with 80% accuracy. Together, these data suggest that muscle girth is a reliable and indirect measure of hindlimb muscle denervation and an early, objective marker for disease onset in congenic B6.SOD1(G93A) ALS mice. Moreover, we present regression equations based on hindlimb muscle girth for predicting genotype in future studies using B6.SOD1(G93A) mice. These findings support new objective criteria for clinical disease onset and provide objective measures that require little expertise. These studies demonstrate a cost-effective approach for more thorough evaluation of neuroprotective strategies that seek to disrupt disease mechanisms early in the disease process. To our knowledge, these findings are the first to report early chronic motor performance and physical deficits that are coincident with the earliest known motor dysfunction in any ALS mouse model.
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Affiliation(s)
- C R Hayworth
- Department of Psychology, Institute for Neuroscience, University of Texas at Austin, 2701 Speedway, Austin, TX 78712, USA.
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Martin LJ. The mitochondrial permeability transition pore: a molecular target for amyotrophic lateral sclerosis therapy. Biochim Biophys Acta Mol Basis Dis 2009; 1802:186-97. [PMID: 19651206 DOI: 10.1016/j.bbadis.2009.07.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 07/22/2009] [Accepted: 07/23/2009] [Indexed: 01/23/2023]
Abstract
Effective therapies are needed for the treatment of amyotrophic lateral sclerosis (ALS), a fatal type of motor neuron disease. Morphological, biochemical, molecular genetic, and cell/animal model studies suggest that mitochondria have potentially diverse roles in neurodegenerative disease mechanisms and neuronal cell death. In human ALS, abnormalities have been found in mitochondrial structure, mitochondrial respiratory chain enzymes, and mitochondrial cell death proteins indicative of some non-classical form of programmed cell death. Mouse models of ALS are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria. This minireview summarizes work on the how malfunctioning mitochondria might contribute to neuronal death in ALS through the biophysical entity called the mitochondrial permeability pore (mPTP). The major protein components of the mPTP are enriched in mouse motor neurons. Early in the course of disease in ALS mice expressing human mutant superoxide dismutase-1, mitochondria in motor neurons undergo trafficking abnormalities and dramatic remodeling resulting in the formation of mega-mitochondria and coinciding with increased protein carbonyl formation and nitration of mPTP components. The genetic deletion of a major mPTP component, cyclophilin D, has robust effects in ALS mice by delaying disease onset and extending survival. Thus, attention should be directed to the mPTP as a rational target for the development of drugs designed to treat ALS.
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Affiliation(s)
- Lee J Martin
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2196, USA.
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