251
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Abstract
Hereditary spastic paraplegia (HSP) is a neurodegenerative disorder preferentially affecting the longest corticospinal axons. More than 40 HSP genetic loci have been identified, among them SPG10, an autosomal dominant HSP caused by point mutations in the neuronal kinesin heavy chain protein KIF5A. Constitutive KIF5A knockout (KIF5A–/–) mice die early after birth. In these mice, lungs were unexpanded, and cell bodies of lower motor neurons in the spinal cord swollen, but the pathomechanism remained unclear. To gain insights into the pathophysiology, we characterized survival, outgrowth, and function in primary motor and sensory neuron cultures from KIF5A–/– mice. Absence of KIF5A reduced survival in motor neurons, but not in sensory neurons. Outgrowth of axons and dendrites was remarkably diminished in KIF5A–/– motor neurons. The number of axonal branches was reduced, whereas the number of dendrites was not altered. In KIF5A–/– sensory neurons, neurite outgrowth was decreased but the number of neurites remained unchanged. In motor neurons maximum and average velocity of mitochondrial transport was reduced both in anterograde and retrograde direction. Our results point out a role of KIF5A in process outgrowth and axonal transport of mitochondria, affecting motor neurons more severely than sensory neurons. This gives pathophysiological insights into KIF5A associated HSP, and matches the clinical findings of predominant degeneration of the longest axons of the corticospinal tract.
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252
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Misko AL, Sasaki Y, Tuck E, Milbrandt J, Baloh RH. Mitofusin2 mutations disrupt axonal mitochondrial positioning and promote axon degeneration. J Neurosci 2012; 32:4145-55. [PMID: 22442078 PMCID: PMC3319368 DOI: 10.1523/jneurosci.6338-11.2012] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 01/27/2012] [Accepted: 02/03/2012] [Indexed: 11/21/2022] Open
Abstract
Alterations in mitochondrial dynamics (fission, fusion, and movement) are implicated in many neurodegenerative diseases, from rare genetic disorders such as Charcot-Marie-Tooth disease, to common conditions including Alzheimer's disease. However, the relationship between altered mitochondrial dynamics and neurodegeneration is incompletely understood. Here we show that disease associated MFN2 proteins suppressed both mitochondrial fusion and transport, and produced classic features of segmental axonal degeneration without cell body death, including neurofilament filled swellings, loss of calcium homeostasis, and accumulation of reactive oxygen species. By contrast, depletion of Opa1 suppressed mitochondrial fusion while sparing transport, and did not induce axonal degeneration. Axon degeneration induced by mutant MFN2 proteins correlated with the disruption of the proper mitochondrial positioning within axons, rather than loss of overall mitochondrial movement, or global mitochondrial dysfunction. We also found that augmenting expression of MFN1 rescued the axonal degeneration caused by MFN2 mutants, suggesting a possible therapeutic strategy for Charcot-Marie-Tooth disease. These experiments provide evidence that the ability of mitochondria to sense energy requirements and localize properly within axons is key to maintaining axonal integrity, and may be a common pathway by which disruptions in axonal transport contribute to neurodegeneration.
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Affiliation(s)
| | | | | | - Jeffrey Milbrandt
- Genetics, and
- Hope Center for Neurological Diseases, Washington University School of Medicine, St Louis, Missouri 63110, and
| | - Robert H. Baloh
- Departments of Neurology and
- Hope Center for Neurological Diseases, Washington University School of Medicine, St Louis, Missouri 63110, and
- Department of Neurology, Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048
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253
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NP1 regulates neuronal activity-dependent accumulation of BAX in mitochondria and mitochondrial dynamics. J Neurosci 2012; 32:1453-66. [PMID: 22279230 DOI: 10.1523/jneurosci.4604-11.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In cultured cerebellar granule neurons, low neuronal activity triggers the intrinsic program of apoptosis, which requires protein synthesis-dependent BAX translocation to mitochondria, a process that may underlie neuronal damage in neurodegeneration. However, the mechanisms that link neuronal activity with the induction of the mitochondrial program of apoptosis remain unclear. Neuronal pentraxin 1 (NP1) is a pro-apoptotic protein induced by low neuronal activity that is increased in damaged neurites in Alzheimer's disease-affected brains. Here we report that NP1 facilitates the accumulation of BAX in mitochondria and regulates mitochondrial dynamics during apoptosis in rat and mouse cerebellar granule neurons in culture. Reduction of neuronal activity increases NP1 protein levels in mitochondria and contributes to mitochondrial fragmentation in a Bax-dependent manner. In addition, NP1 is involved in mitochondrial transport in healthy neurons. These results show that NP1 is targeted to mitochondria acting upstream of BAX and uncover a novel function for NP1 in the regulation of mitochondrial dynamics and trafficking during apoptotic neurodegeneration.
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254
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Quintanilla RA, Dolan PJ, Jin YN, Johnson GVW. Truncated tau and Aβ cooperatively impair mitochondria in primary neurons. Neurobiol Aging 2012; 33:619.e25-35. [PMID: 21450370 PMCID: PMC3140623 DOI: 10.1016/j.neurobiolaging.2011.02.007] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 02/04/2011] [Accepted: 02/13/2011] [Indexed: 01/11/2023]
Abstract
Mitochondrial dysfunction is likely a significant contributing factor to Alzheimer disease pathogenesis, and both amyloid peptide (Aβ) and pathological forms of tau may contribute to this impairment. Cleavage of tau at Asp421 occurs early in Alzheimer disease, and Asp421-cleaved tau likely negatively impacts neuronal function. Previously we showed that expression of Asp421-cleaved tau in a neuronal cell model resulted in mitochondrial impairment. To extend these findings we expressed either full length tau or Asp421-cleaved tau (truncated tau) in primary cortical neurons and measured different aspects of mitochondrial function with or without the addition of sublethal concentrations of Aβ. The expression of truncated tau alone induced significant mitochondrial fragmentation in neurons. When truncated tau expression was combined with Aβ at sublethal concentrations, increases in the stationary mitochondrial population and the levels of oxidative stress in cortical neurons were observed. Truncated tau expression also enhanced Aβ-induced mitochondrial potential loss in primary neurons. These new findings show that Asp421-cleaved tau and Aβ cooperate to impair mitochondria, which likely contributes to the neuronal dysfunction in Alzheimer disease.
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255
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Campbell GR, Mahad DJ. Mitochondrial changes associated with demyelination: Consequences for axonal integrity. Mitochondrion 2012; 12:173-9. [DOI: 10.1016/j.mito.2011.03.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 02/04/2011] [Accepted: 03/04/2011] [Indexed: 12/30/2022]
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256
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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: 114] [Impact Index Per Article: 8.8] [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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257
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Ferraiuolo L, Kirby J, Grierson AJ, Sendtner M, Shaw PJ. Molecular pathways of motor neuron injury in amyotrophic lateral sclerosis. Nat Rev Neurol 2012; 7:616-30. [PMID: 22051914 DOI: 10.1038/nrneurol.2011.152] [Citation(s) in RCA: 459] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a genetically diverse disease. At least 15 ALS-associated gene loci have so far been identified, and the causative gene is known in approximately 30% of familial ALS cases. Less is known about the factors underlying the sporadic form of the disease. The molecular mechanisms of motor neuron degeneration are best understood in the subtype of disease caused by mutations in superoxide dismutase 1, with a current consensus that motor neuron injury is caused by a complex interplay between multiple pathogenic processes. A key recent finding is that mutated TAR DNA-binding protein 43 is a major constituent of the ubiquitinated protein inclusions in ALS, providing a possible link between the genetic mutation and the cellular pathology. New insights have also indicated the importance of dysregulated glial cell-motor neuron crosstalk, and have highlighted the vulnerability of the distal axonal compartment early in the disease course. In addition, recent studies have suggested that disordered RNA processing is likely to represent a major contributing factor to motor neuron disease. Ongoing research on the cellular pathways highlighted in this Review is predicted to open the door to new therapeutic interventions to slow disease progression in ALS.
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Affiliation(s)
- Laura Ferraiuolo
- Academic Neurology Unit, Sheffield Institute for Translational Neuroscience, Department of Neuroscience, School of Medicine and Biomedical Sciences, University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
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258
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Spatial parkin translocation and degradation of damaged mitochondria via mitophagy in live cortical neurons. Curr Biol 2012; 22:545-52. [PMID: 22342752 DOI: 10.1016/j.cub.2012.02.005] [Citation(s) in RCA: 267] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 01/16/2012] [Accepted: 02/03/2012] [Indexed: 11/23/2022]
Abstract
Mitochondria are essential for neuronal survival and function. Proper degradation of aged and damaged mitochondria through mitophagy is a key cellular pathway for mitochondrial quality control. Recent studies have indicated that PINK1/Parkin-mediated pathways ensure mitochondrial integrity and function. Translocation of Parkin to damaged mitochondria induces mitophagy in many nonneuronal cell types. However, evidence showing Parkin translocation in primary neurons is controversial, leaving unanswered questions as to how and where Parkin-mediated mitophagy occurs in neurons. Here, we report the unique process of dissipating mitochondrial Δψ(m)-induced and Parkin-mediated mitophagy in mature cortical neurons. Compared with nonneuronal cells, neuronal mitophagy is a much slower and compartmentally restricted process, coupled with reduced anterograde mitochondrial transport. Parkin-targeted mitochondria are accumulated in the somatodendritic regions where mature lysosomes are predominantly located. Time-lapse imaging shows dynamic formation and elimination of Parkin- and LC3-ring-like structures surrounding depolarized mitochondria through the autophagy-lysosomal pathway in the soma. Knocking down Parkin in neurons impairs the elimination of dysfunctional mitochondria. Thus, our study provides neuronal evidence for dynamic and spatial Parkin-mediated mitophagy, which will help us understand whether altered mitophagy contributes to pathogenesis of several major neurodegenerative diseases characterized by mitochondrial dysfunction and impaired transport.
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259
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Galea E, Launay N, Portero-Otin M, Ruiz M, Pamplona R, Aubourg P, Ferrer I, Pujol A. Oxidative stress underlying axonal degeneration in adrenoleukodystrophy: a paradigm for multifactorial neurodegenerative diseases? Biochim Biophys Acta Mol Basis Dis 2012; 1822:1475-88. [PMID: 22353463 DOI: 10.1016/j.bbadis.2012.02.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/31/2011] [Accepted: 02/03/2012] [Indexed: 12/13/2022]
Abstract
X-linked adrenoleukodystrophy (X-ALD) is an inherited neurodegenerative disorder expressed as four disease variants characterized by adrenal insufficiency and graded damage in the nervous system. X-ALD is caused by a loss of function of the peroxisomal ABCD1 fatty-acid transporter, resulting in the accumulation of very long chain fatty acids (VLCFA) in the organs and plasma, which have potentially toxic effects in CNS and adrenal glands. We have recently shown that treatment with a combination of antioxidants containing α-tocopherol, N-acetyl-cysteine and α-lipoic acid reversed oxidative damage and energetic failure, together with the axonal degeneration and locomotor impairment displayed by Abcd1 null mice, the animal model of X-ALD. This is the first direct demonstration that oxidative stress, which is a hallmark not only of X-ALD, but also of other neurodegenerative processes, such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD), contributes to axonal damage. The purpose of this review is, first, to discuss the molecular and cellular underpinnings of VLCFA-induced oxidative stress, and how it interacts with energy metabolism and/or inflammation to generate a complex syndrome wherein multiple factors are contributing. Particular attention will be paid to the dysregulation of redox homeostasis by the interplay between peroxisomes and mitochondria. Second, we will extend this analysis to the aforementioned neurodegenerative diseases with the aim of defining differences as well as the existence of a core pathogenic mechanism that would justify the exchange of therapeutic opportunities among these pathologies.
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Affiliation(s)
- Elena Galea
- Universitat Autònoma de Barcelona, Barcelona, Spain
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260
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Karbowski M, Neutzner A. Neurodegeneration as a consequence of failed mitochondrial maintenance. Acta Neuropathol 2012; 123:157-71. [PMID: 22143516 DOI: 10.1007/s00401-011-0921-0] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 11/18/2011] [Accepted: 11/22/2011] [Indexed: 02/06/2023]
Abstract
Maintaining the functional integrity of mitochondria is pivotal for cellular survival. It appears that neuronal homeostasis depends on high-fidelity mitochondria, in particular. Consequently, mitochondrial dysfunction is a fundamental problem associated with a significant number of neurological diseases, including Parkinson's disease (PD), Huntington's disease (HD), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and various peripheral neuropathies, as well as the normal aging process. To ensure optimal mitochondrial function, diverse, evolutionarily conserved mitochondrial quality control mechanisms are in place, including the scavenging of toxic reactive oxygen species (ROS) and degradation of damaged mitochondrial proteins, but also turnover of whole organelles. In this review we will discuss various mitochondria-associated conditions, focusing on the role of protein turnover in mitochondrial maintenance with special emphasis on neurodegenerative disorders.
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Affiliation(s)
- Mariusz Karbowski
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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261
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Parkin, PINK1 and mitochondrial integrity: emerging concepts of mitochondrial dysfunction in Parkinson's disease. Acta Neuropathol 2012; 123:173-88. [PMID: 22057787 DOI: 10.1007/s00401-011-0902-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/20/2011] [Accepted: 10/21/2011] [Indexed: 10/15/2022]
Abstract
Mitochondria are dynamic organelles which are essential for many cellular processes, such as ATP production by oxidative phosphorylation, lipid metabolism, assembly of iron sulfur clusters, regulation of calcium homeostasis, and cell death pathways. The dynamic changes in mitochondrial morphology, connectivity, and subcellular distribution are critically dependent on a highly regulated fusion and fission machinery. Mitochondrial function, dynamics, and quality control are vital for the maintenance of neuronal integrity. Indeed, there is mounting evidence that mitochondrial dysfunction plays a central role in several neurodegenerative diseases. In particular, the identification of genes linked to rare familial variants of Parkinson's disease has fueled research on mitochondrial aspects of the disease etiopathogenesis. Studies on the function of parkin and PINK1, which are associated with autosomal recessive parkinsonism, provided compelling evidence that these proteins can functionally interact to maintain mitochondrial integrity and to promote clearance of damaged and dysfunctional mitochondria. In this review we will summarize current knowledge about the impact of parkin and PINK1 on mitochondria.
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262
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Ciron C, Lengacher S, Dusonchet J, Aebischer P, Schneider BL. Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function. Hum Mol Genet 2012; 21:1861-76. [PMID: 22246294 PMCID: PMC3313800 DOI: 10.1093/hmg/ddr618] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mitochondrial dysfunction and oxidative stress have been implicated in the etiology of Parkinson's disease. Therefore, pathways controlling mitochondrial activity rapidly emerge as potential therapeutic targets. Here, we explore the neuronal response to prolonged overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), a transcriptional regulator of mitochondrial function, both in vitro and in vivo. In neuronal primary cultures from the ventral midbrain, PGC-1α induces mitochondrial biogenesis and increases basal respiration. Over time, we observe an increasing proportion of the oxygen consumed by neurons which are dedicated to adenosine triphosphate production. In parallel to enhanced oxidative phosphorylation, PGC-1α progressively leads to a decrease in mitochondrial polarization. In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content. In addition, PGC-1α prevents the labeling of nigral neurons following striatal injection of the fluorogold retrograde tracer. When PGC-1α is expressed at higher levels following intranigral AAV injection, it leads to overt degeneration of dopaminergic neurons. Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression. Overall, we find that lasting overexpression of PGC-1α leads to major alterations in the metabolic activity of neuronal cells which dramatically impair dopaminergic function in vivo. These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activity.
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Affiliation(s)
- C Ciron
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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263
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Matenia D, Hempp C, Timm T, Eikhof A, Mandelkow EM. Microtubule affinity-regulating kinase 2 (MARK2) turns on phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1) at Thr-313, a mutation site in Parkinson disease: effects on mitochondrial transport. J Biol Chem 2012; 287:8174-86. [PMID: 22238344 DOI: 10.1074/jbc.m111.262287] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The kinase MARK2/Par-1 plays key roles in several cell processes, including neurodegeneration such as Alzheimer disease by phosphorylating tau and detaching it from microtubules. In search of interaction partners of MARK2, we identified phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1), which is important for the survival of neurons and whose mutations are linked to familial Parkinson disease (PD). MARK2 phosphorylated and activated the cleaved form of PINK1 (ΔN-PINK1; amino acids 156-581). Thr-313 was the primary phosphorylation site, a residue mutated to a non-phosphorylatable form (T313M) in a frequent variant of PD. Mutation of Thr-313 to Met or Glu in PINK1 showed toxic effects with abnormal mitochondrial distribution in neurons. MARK2 and PINK1 were found to colocalize with mitochondria and regulate their transport. ΔN-PINK1 promoted anterograde transport and increased the fraction of stationary mitochondria, whereas full-length PINK1 promoted retrograde transport. In both cases, MARK2 enhanced the effects. The results identify MARK2 as an upstream regulator of PINK1 and ΔN-PINK1 and provide insights into the regulation of mitochondrial trafficking in neurons and neurodegeneration in PD.
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Affiliation(s)
- Dorthe Matenia
- Max Planck Unit for Structural Molecular Biology, c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany.
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264
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Mitochondrial transport in neurons: impact on synaptic homeostasis and neurodegeneration. Nat Rev Neurosci 2012; 13:77-93. [PMID: 22218207 DOI: 10.1038/nrn3156] [Citation(s) in RCA: 642] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondria have a number of essential roles in neuronal function. Their complex mobility patterns within neurons are characterized by frequent changes in direction. Mobile mitochondria can become stationary or pause in regions that have a high metabolic demand and can move again rapidly in response to physiological changes. Defects in mitochondrial transport are implicated in the pathogenesis of several major neurological disorders. Research into the mechanisms that regulate mitochondrial transport is thus an important emerging frontier.
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265
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Abstract
Gene products such as organelles, proteins and RNAs are actively transported to synaptic terminals for the remodeling of pre-existing neuronal connections and formation of new ones. Proteins described as molecular motors mediate this transport and utilize specialized cytoskeletal proteins that function as molecular tracks for the motor based transport of cargos. Molecular motors such as kinesins and dynein's move along microtubule tracks formed by tubulins whereas myosin motors utilize tracks formed by actin. Deficits in active transport of gene products have been implicated in a number of neurological disorders. We describe such disorders collectively as "transportopathies". Here we review current knowledge of critical components of active transport and their relevance to neurodegenerative diseases.
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266
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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: 126] [Impact Index Per Article: 9.7] [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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267
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Calkins MJ, Manczak M, Mao P, Shirendeb U, Reddy PH. Impaired mitochondrial biogenesis, defective axonal transport of mitochondria, abnormal mitochondrial dynamics and synaptic degeneration in a mouse model of Alzheimer's disease. Hum Mol Genet 2011; 20:4515-29. [PMID: 21873260 PMCID: PMC3209824 DOI: 10.1093/hmg/ddr381] [Citation(s) in RCA: 508] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 08/23/2011] [Indexed: 11/13/2022] Open
Abstract
Increasing evidence suggests that the accumulation of amyloid beta (Aβ) in synapses and synaptic mitochondria causes synaptic mitochondrial failure and synaptic degeneration in Alzheimer's disease (AD). The purpose of this study was to better understand the effects of Aβ in mitochondrial activity and synaptic alterations in neurons from a mouse model of AD. Using primary neurons from a well-characterized Aβ precursor protein transgenic (AβPP) mouse model (Tg2576 mouse line), for the first time, we studied mitochondrial activity, including axonal transport of mitochondria, mitochondrial dynamics, morphology and function. Further, we also studied the nature of Aβ-induced synaptic alterations, and cell death in primary neurons from Tg2576 mice, and we sought to determine whether the mitochondria-targeted antioxidant SS31 could mitigate the effects of oligomeric Aβ. We found significantly decreased anterograde mitochondrial movement, increased mitochondrial fission and decreased fusion, abnormal mitochondrial and synaptic proteins and defective mitochondrial function in primary neurons from AβPP mice compared with wild-type (WT) neurons. Transmission electron microscopy revealed a large number of small mitochondria and structurally damaged mitochondria, with broken cristae in AβPP primary neurons. We also found an increased accumulation of oligomeric Aβ and increased apoptotic neuronal death in the primary neurons from the AβPP mice relative to the WT neurons. Our results revealed an accumulation of intraneuronal oligomeric Aβ, leading to mitochondrial and synaptic deficiencies, and ultimately causing neurodegeneration in AβPP cultures. However, we found that the mitochondria-targeted antioxidant SS31 restored mitochondrial transport and synaptic viability, and decreased the percentage of defective mitochondria, indicating that SS31 protects mitochondria and synapses from Aβ toxicity.
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Affiliation(s)
- Marcus J. Calkins
- Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA and
| | - Maria Manczak
- Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA and
| | - Peizhong Mao
- Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA and
| | - Ulziibat Shirendeb
- Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA and
| | - P. Hemachandra Reddy
- Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA and
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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268
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Somerville SM, Conley RR, Roberts RC. Striatal mitochondria in subjects with chronic undifferentiated vs. chronic paranoid schizophrenia. Synapse 2011; 66:29-41. [PMID: 21905126 DOI: 10.1002/syn.20981] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 08/29/2011] [Accepted: 09/03/2011] [Indexed: 01/24/2023]
Abstract
Schizophrenia (SZ) is a heterogeneous disease with a spectrum of symptoms, risk factors, and etiology. Abnormalities in mitochondria, the energy-producing organelles of the cell, have been observed in mixed cohorts of subjects with SZ. The purpose of the present study was to determine if striatal mitochondria were differentially affected in two different DSM-IV subgroups of SZ. Postmortem striatal tissue was examined from normal controls (NC), chronic paranoid SZs (SZP), and chronic undifferentiated SZs (SZU). Tissue was processed for calbindin immunohistochemistry to identify striosomal compartments, prepared for electron microscopy and analyzed using stereological methods. In both caudate and putamen, the density of mitochondria in the neuropil was decreased in SZP compared to both NCs and SZU. In the putamen, both the SZP and the SZU subgroups had fewer mitochondria per synapse than did NCs. When examining patch matrix compartments, striatal compartments associated with different circuitry and function, only the matrix exhibited changes. In the caudate matrix, the SZP subgroup had fewer mitochondria in the neuropil than did the SZU and NCs. In the putamen matrix, the SZP had fewer mitochondria in the neuropil as compared to NCs, but not the SZU. The numbers of mitochondria per synapse in both the SZP and the SZU groups were similar to each other and fewer than that of NCs. A decrease in mitochondrial density in the neuropil distinguishes the SZP from the SZU subgroup, which could be associated with the symptoms of paranoia and/or could represent a protective mechanism against some of the symptoms that are less pronounced in this subtype than in the SZU subgroup such as cognitive and emotional deficits.
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Affiliation(s)
- Shahza M Somerville
- Maryland Psychiatric Research Center, Maple and Locust Street, Baltimore, Maryland 21228, USA
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269
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Palmer CS, Osellame LD, Stojanovski D, Ryan MT. The regulation of mitochondrial morphology: intricate mechanisms and dynamic machinery. Cell Signal 2011; 23:1534-45. [PMID: 21683788 DOI: 10.1016/j.cellsig.2011.05.021] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 05/31/2011] [Indexed: 01/04/2023]
Abstract
Mitochondria typically form a reticular network radiating from the nucleus, creating an interconnected system that supplies the cell with essential energy and metabolites. These mitochondrial networks are regulated through the complex coordination of fission, fusion and distribution events. While a number of key mitochondrial morphology proteins have been identified, the precise mechanisms which govern their activity remain elusive. Moreover, post translational modifications including ubiquitination, phosphorylation and sumoylation of the core machinery are thought to regulate both fusion and division of the network. These proteins can undergo several different modifications depending on cellular signals, environment and energetic demands of the cell. Proteins involved in mitochondrial morphology may also have dual roles in both dynamics and apoptosis, with regulation of these proteins under tight control of the cell to ensure correct function. The absolute reliance of the cell on a functional mitochondrial network is highlighted in neurons, which are particularly vulnerable to any changes in organelle dynamics due to their unique biochemical requirements. Recent evidence suggests that defects in the shape or distribution of mitochondria correlate with the progression of neurodegenerative diseases such as Alzheimer's, Huntington's and Parkinson's disease. This review focuses on our current understanding of the mitochondrial morphology machinery in cell homeostasis, apoptosis and neurodegeneration, and the post translational modifications that regulate these processes.
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Affiliation(s)
- Catherine S Palmer
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
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270
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Amadoro G, Corsetti V, Atlante A, Florenzano F, Capsoni S, Bussani R, Mercanti D, Calissano P. Interaction between NH(2)-tau fragment and Aβ in Alzheimer's disease mitochondria contributes to the synaptic deterioration. Neurobiol Aging 2011; 33:833.e1-25. [PMID: 21958963 DOI: 10.1016/j.neurobiolaging.2011.08.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 07/26/2011] [Accepted: 08/05/2011] [Indexed: 12/15/2022]
Abstract
Although amyloid beta (Aβ) peptide can promote tau pathology and its toxicity is concurrently tau-dependent, the underlying mechanisms of the in vivo interplay of these proteins remain unsolved. Structural and functional mitochondrial alterations play an early, precipitating role in synaptic failure of Alzheimer's disease (AD) pathogenesis and an aggravated mitochondrial impairment has been described in triple APP/PS/tau transgenic mice carrying both plaques and tangles, if compared with mice overexpressing tau or amyloid precursor protein (APP) alone. Here, we show that a neurotoxic aminoterminal (NH(2))-derived tau fragment mapping between 26 and 230 amino acids of the human tau40 isoform (441 amino acids)-but not the physiological full-length protein-preferentially interacts with Aβ peptide(s) in human AD synapses in association with mitochondrial adenine nucleotide translocator-1 (ANT-1) and cyclophilin D. The two peptides-Aβ 1-42 and the smaller and more potent NH(2)-26-44 peptide of the longest 20-22 kDa NH(2)-tau fragment-inhibit the ANT-1-dependent adenosine diphosphate-adenosine triphosphate (ADP/ATP) exchange in a noncompetitive and competitive manner, respectively, and together further aggravate the mitochondrial dysfunction by exacerbating the ANT-1 impairment. Taken together, these data establish a common, direct and synergistic toxicity of pathological APP and tau products on synaptic mitochondria and suggest potential, new pathway(s) and target(s) for a combined, more efficient therapeutic intervention of early synaptic dysfunction in AD.
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271
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Mitochondrial matrix Ca2+ as an intrinsic signal regulating mitochondrial motility in axons. Proc Natl Acad Sci U S A 2011; 108:15456-61. [PMID: 21876166 DOI: 10.1073/pnas.1106862108] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The proper distribution of mitochondria is particularly vital for neurons because of their polarized structure and high energy demand. Mitochondria in axons constantly move in response to physiological needs, but signals that regulate mitochondrial movement are not well understood. Aside from producing ATP, Ca(2+) buffering is another main function of mitochondria. Activities of many enzymes in mitochondria are also Ca(2+)-dependent, suggesting that intramitochondrial Ca(2+) concentration is important for mitochondrial functions. Here, we report that mitochondrial motility in axons is actively regulated by mitochondrial matrix Ca(2+). Ca(2+) entry through the mitochondrial Ca(2+) uniporter modulates mitochondrial transport, and mitochondrial Ca(2+) content correlates inversely with the speed of mitochondrial movement. Furthermore, the miro1 protein plays a role in Ca(2+) uptake into the mitochondria, which subsequently affects mitochondrial movement.
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272
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Tanaka K, Sugiura Y, Ichishita R, Mihara K, Oka T. KLP6: a newly identified kinesin that regulates the morphology and transport of mitochondria in neuronal cells. J Cell Sci 2011; 124:2457-65. [DOI: 10.1242/jcs.086470] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mitochondria utilize diverse cytoskeleton-based mechanisms to control their functions and morphology. Here, we report a role for kinesin-like protein KLP6, a newly identified member of the kinesin family, in mitochondrial morphology and dynamics. An RNA interference screen using Caenorhabditis elegans led us to identify a C. elegans KLP-6 involved in maintaining mitochondrial morphology. We cloned a cDNA coding for a rat homolog of C. elegans KLP-6, which is an uncharacterized kinesin in vertebrates. A rat KLP6 mutant protein lacking the motor domain induced changes in mitochondrial morphology and significantly decreased mitochondrial motility in HeLa cells, but did not affect the morphology of other organelles. In addition, the KLP6 mutant inhibited transport of mitochondria during anterograde movement in differentiated neuro 2a cells. To date, two kinesins, KIF1Bα and kinesin heavy chain (KHC; also known as KIF5) have been shown to be involved in the distribution of mitochondria in neurons. Expression of the kinesin heavy chain/KIF5 mutant prevented mitochondria from entering into neurites, whereas both the KLP6 and KIF1Bα mutants decreased mitochondrial transport in axonal neurites. Furthermore, both KLP6 and KIF1Bα bind to KBP, a KIF1-binding protein required for axonal outgrowth and mitochondrial distribution. Thus, KLP6 is a newly identified kinesin family member that regulates mitochondrial morphology and transport.
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Affiliation(s)
- Kousuke Tanaka
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Yoshimi Sugiura
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Ryohei Ichishita
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Katsuyoshi Mihara
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8582, Japan
| | - Toshihiko Oka
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8582, Japan
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273
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Zambonin JL, Zhao C, Ohno N, Campbell GR, Engeham S, Ziabreva I, Schwarz N, Lee SE, Frischer JM, Turnbull DM, Trapp BD, Lassmann H, Franklin RJM, Mahad DJ. Increased mitochondrial content in remyelinated axons: implications for multiple sclerosis. Brain 2011; 134:1901-13. [PMID: 21705418 PMCID: PMC3122369 DOI: 10.1093/brain/awr110] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 03/26/2011] [Accepted: 03/29/2011] [Indexed: 01/15/2023] Open
Abstract
Mitochondrial content within axons increases following demyelination in the central nervous system, presumably as a response to the changes in energy needs of axons imposed by redistribution of sodium channels. Myelin sheaths can be restored in demyelinated axons and remyelination in some multiple sclerosis lesions is extensive, while in others it is incomplete or absent. The effects of remyelination on axonal mitochondrial content in multiple sclerosis, particularly whether remyelination completely reverses the mitochondrial changes that follow demyelination, are currently unknown. In this study, we analysed axonal mitochondria within demyelinated, remyelinated and myelinated axons in post-mortem tissue from patients with multiple sclerosis and controls, as well as in experimental models of demyelination and remyelination, in vivo and in vitro. Immunofluorescent labelling of mitochondria (porin, a voltage-dependent anion channel expressed on all mitochondria) and axons (neurofilament), and ultrastructural imaging showed that in both multiple sclerosis and experimental demyelination, mitochondrial content within remyelinated axons was significantly less than in acutely and chronically demyelinated axons but more numerous than in myelinated axons. The greater mitochondrial content within remyelinated, compared with myelinated, axons was due to an increase in density of porin elements whereas increase in size accounted for the change observed in demyelinated axons. The increase in mitochondrial content in remyelinated axons was associated with an increase in mitochondrial respiratory chain complex IV activity. In vitro studies showed a significant increase in the number of stationary mitochondria in remyelinated compared with myelinated and demyelinated axons. The number of mobile mitochondria in remyelinated axons did not significantly differ from myelinated axons, although significantly greater than in demyelinated axons. Our neuropathological data and findings in experimental demyelination and remyelination in vivo and in vitro are consistent with a partial amelioration of the supposed increase in energy demand of demyelinated axons by remyelination.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Animals
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/metabolism
- Axons/metabolism
- Axons/pathology
- Axons/ultrastructure
- Brain/metabolism
- Brain/pathology
- Brain/ultrastructure
- Cells, Cultured
- Coculture Techniques
- Demyelinating Diseases/chemically induced
- Disease Models, Animal
- Ethidium/toxicity
- Female
- Ganglia, Spinal/drug effects
- HLA Antigens/metabolism
- Humans
- Leukocyte Common Antigens/metabolism
- Lysophosphatidylcholines/toxicity
- Male
- Microscopy, Electron, Transmission
- Middle Aged
- Mitochondria/drug effects
- Mitochondria/metabolism
- Multiple Sclerosis/pathology
- Myelin Basic Protein/metabolism
- Neurofilament Proteins/metabolism
- Rats
- Rats, Sprague-Dawley
- Schwann Cells/drug effects
- Voltage-Dependent Anion Channels/metabolism
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Affiliation(s)
- Jessica L. Zambonin
- 1 The Mitochondrial Research Group, Institute of Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Chao Zhao
- 2 MRC Centre for Stem Cell Biology and Regenerative Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
- 3 Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Nobuhiko Ohno
- 4 Department of Neurosciences, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Graham R. Campbell
- 1 The Mitochondrial Research Group, Institute of Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Sarah Engeham
- 1 The Mitochondrial Research Group, Institute of Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Iryna Ziabreva
- 1 The Mitochondrial Research Group, Institute of Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Nadine Schwarz
- 1 The Mitochondrial Research Group, Institute of Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Sok Ee Lee
- 2 MRC Centre for Stem Cell Biology and Regenerative Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Josa M. Frischer
- 5 Department of Neuroimmunology, Centre for Brain Research, Medical University Vienna, Spitalgasse 4, 1090, Vienna, Austria
| | - Doug M. Turnbull
- 1 The Mitochondrial Research Group, Institute of Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Bruce D. Trapp
- 4 Department of Neurosciences, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Hans Lassmann
- 5 Department of Neuroimmunology, Centre for Brain Research, Medical University Vienna, Spitalgasse 4, 1090, Vienna, Austria
| | - Robin J. M. Franklin
- 2 MRC Centre for Stem Cell Biology and Regenerative Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Don J. Mahad
- 1 The Mitochondrial Research Group, Institute of Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
- 4 Department of Neurosciences, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
- 6 The Mellen Centre for Multiple Sclerosis Treatment and Research, Department of Neurology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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274
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Zhang K, Osakada Y, Xie W, Cui B. Automated image analysis for tracking cargo transport in axons. Microsc Res Tech 2011; 74:605-13. [PMID: 20945466 PMCID: PMC3022967 DOI: 10.1002/jemt.20934] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 07/28/2010] [Accepted: 08/05/2010] [Indexed: 02/03/2023]
Abstract
The dynamics of cargo movement in axons encodes crucial information about the underlying regulatory mechanisms of the axonal transport process in neurons, a central problem in understanding many neurodegenerative diseases. Quantitative analysis of cargo dynamics in axons usually includes three steps: (1) acquiring time-lapse image series, (2) localizing individual cargos at each time step, and (3) constructing dynamic trajectories for kinetic analysis. Currently, the later two steps are usually carried out with substantial human intervention. This article presents a method of automatic image analysis aiming for constructing cargo trajectories with higher data processing throughput, better spatial resolution, and minimal human intervention. The method is based on novel applications of several algorithms including 2D kymograph construction, seed points detection, trajectory curve tracing, back-projection to extract spatial information, and position refining using a 2D Gaussian fitting. This method is sufficiently robust for usage on images with low signal-to-noise ratio, such as those from single molecule experiments. The method was experimentally validated by tracking the axonal transport of quantum dot and DiI fluorophore-labeled vesicles in dorsal root ganglia neurons.
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Affiliation(s)
- Kai Zhang
- Department of Chemistry, Stanford University, Stanford, California, 94305
| | - Yasuko Osakada
- Department of Chemistry, Stanford University, Stanford, California, 94305
| | - Wenjun Xie
- Department of Chemistry, Stanford University, Stanford, California, 94305
| | - Bianxiao Cui
- Department of Chemistry, Stanford University, Stanford, California, 94305
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275
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A fast and robust method for automated analysis of axonal transport. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 40:1061-9. [PMID: 21695534 DOI: 10.1007/s00249-011-0722-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 04/08/2011] [Accepted: 06/02/2011] [Indexed: 01/05/2023]
Abstract
Cargo movement along axons and dendrites is indispensable for the survival and maintenance of neuronal networks. Key parameters of this transport such as particle velocities and pausing times are often studied using kymograph construction, which converts the transport along a line of interest from a time-lapse movie into a position versus time image. Here we present a method for the automatic analysis of such kymographs based on the Hough transform, which is a robust and fast technique to extract lines from images. The applicability of the method was tested on simulated kymograph images and real data from axonal transport of synaptophysin and tetanus toxin as well as the velocity analysis of synaptic vesicle sharing between adjacent synapses in hippocampal neurons. Efficiency analysis revealed that the algorithm is able to detect a wide range of velocities and can be used at low signal-to-noise ratios. The present work enables the quantification of axonal transport parameters with high throughput with no a priori assumptions and minimal human intervention.
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276
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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. [PMID: 21299590 DOI: 10.1111/j.1365-2990.2011.01166.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by loss of upper and lower motor neurones leading to muscle weakness and paralysis. Despite recent advances in the genetics of ALS, the mechanisms underlying motor neurone degeneration are not fully understood. Mitochondria are known to be involved in the pathogenesis of ALS, principally through mitochondrial dysfunction, the generation of free radicals, and impaired calcium handling in ALS patients and models of disease. However, recent studies have highlighted the potential importance of altered mitochondrial morphology and defective axonal transport of mitochondria in ALS. Here, we review the evidence for mitochondrial involvement in ALS and discuss potential therapeutic strategies targeting mitochondria.
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Affiliation(s)
- L M Duffy
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
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277
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Chetta J, Shah SB. A novel algorithm to generate kymographs from dynamic axons for the quantitative analysis of axonal transport. J Neurosci Methods 2011; 199:230-40. [PMID: 21620890 DOI: 10.1016/j.jneumeth.2011.05.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 04/11/2011] [Accepted: 05/09/2011] [Indexed: 12/22/2022]
Abstract
The biological and clinical relevance of axonal transport has driven the development of a variety of new approaches to its study, including the generation of fluorescence or brightfield movies of moving cargoes within axons. Kymograph analysis is a simple and effective tool used to analyze axonal transport in neurons. Typically, kymographs are built by having a user trace the path of the axon in one frame of a time-lapse movie and extracting intensity profiles from subsequent frames along that path. This method cannot accommodate movies in which translation of the axon, or changes in axonal orientation or geometry, occur. Both are frequently observed in long-term movies of neurons, both in vitro and in vivo. To solve this problem and automate the creation of kymographs from these movies, we developed a two step algorithm. The first step implemented a simple image registration algorithm that aligned axons based on identification of a reference point on the axon in each image. The second step used a Hough transformation (HT) to automatically detect the axonal contour in each frame. Intensity profiles along this contour were then used to construct a kymograph. This algorithm was able to build an accurate kymograph of mitochondrial and actin transport in dynamic cultured sensory neurons, which were not amenable to previously used analytical methods. Although developed as a tool for analyzing transport, this algorithm is easily modified to analyze movies for the directionality and speed of axonal outgrowth, another metric of interest to neuroscientists.
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Affiliation(s)
- Joshua Chetta
- Fischell Department of Bioengineering, University of Maryland, 3236 Kim Engineering Building, College Park, MD 20742, United States
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278
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Ohno N, Kidd GJ, Mahad D, Kiryu-Seo S, Avishai A, Komuro H, Trapp BD. Myelination and axonal electrical activity modulate the distribution and motility of mitochondria at CNS nodes of Ranvier. J Neurosci 2011; 31:7249-58. [PMID: 21593309 PMCID: PMC3139464 DOI: 10.1523/jneurosci.0095-11.2011] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/28/2011] [Accepted: 03/30/2011] [Indexed: 12/15/2022] Open
Abstract
Energy production presents a formidable challenge to axons as their mitochondria are synthesized and degraded in neuronal cell bodies. To meet the energy demands of nerve conduction, small mitochondria are transported to and enriched at mitochondrial stationary sites located throughout the axon. In this study, we investigated whether size and motility of mitochondria in small myelinated CNS axons are differentially regulated at nodes, and whether mitochondrial distribution and motility are modulated by axonal electrical activity. The size/volume of mitochondrial stationary sites was significantly larger in juxtaparanodal/internodal axoplasm than in nodal/paranodal axoplasm. With three-dimensional electron microscopy, we observed that axonal mitochondrial stationary sites were composed of multiple mitochondria of varying length, except at nodes where mitochondria were uniformly short and frequently absent altogether. Mitochondrial transport speed was significantly reduced in nodal axoplasm compared with internodal axoplasm. Increased axonal electrical activity decreased mitochondrial transport and increased the size of mitochondrial stationary sites in nodal/paranodal axoplasm. Decreased axonal electrical activity had the opposite effect. In cerebellar axons of the myelin-deficient rat, which contain voltage-gated Na(+) channel clusters but lack paranodal specializations, axonal mitochondrial motility and stationary site size were similar at Na(+) channel clusters and other axonal regions. These results demonstrate juxtaparanodal/internodal enrichment of stationary mitochondria and neuronal activity-dependent dynamic modulation of mitochondrial distribution and transport in nodal axoplasm. In addition, the modulation of mitochondrial distribution and motility requires oligodendrocyte-axon interactions at paranodal specializations.
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Affiliation(s)
- Nobuhiko Ohno
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Grahame J. Kidd
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Don Mahad
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Sumiko Kiryu-Seo
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Amir Avishai
- Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio, 44106
| | - Hitoshi Komuro
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Bruce D. Trapp
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
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279
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Gusdon AM, Chu CT. To eat or not to eat: neuronal metabolism, mitophagy, and Parkinson's disease. Antioxid Redox Signal 2011; 14:1979-87. [PMID: 21126205 PMCID: PMC3078495 DOI: 10.1089/ars.2010.3763] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Neurons are exquisitely dependent upon mitochondrial respiration to support energy-demanding functions. Mechanisms that regulate mitochondrial quality control have recently taken center stage in Parkinson's disease research, particularly the selective degradation of mitochondria by autophagy (mitophagy). Unlike other cells, neurons show limited glycolytic potential, and both insufficient and excessive mitophagy have been linked to neurodegeneration. Kinases implicated in regulating mammalian mitophagy include extracellular signal-regulated protein kinases (ERK1/2) and PTEN-induced kinase 1 (PINK1). Increased expression of full-length PINK1 enhances recruitment of parkin to chemically depolarized mitochondria, resulting in rapid mitochondrial clearance in transformed cell lines. As parkin and PINK1 mutations cause autosomal recessive parkinsonism, potential defects in clearing dysfunctional mitochondria may contribute to mitochondrial abnormalities in disease. Given the unique features of metabolic regulation in neurons, however, mechanisms regulating mitochondrial network stability and the threshold for mitophagy are likely to vary from cells that preferentially utilize aerobic glycolysis. Moreover, removal of the entire mitochondrial complement may represent part of a neuronal cell death pathway. Future work utilizing physiological injuries that affect only a subset of mitochondria would help to elucidate whether defective recognition of damaged mitochondria, or alternatively, inability to maintain or generate healthy mitochondria, play the major roles in parkinsonian neurodegeneration.
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Affiliation(s)
- Aaron M Gusdon
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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280
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Somerville SM, Lahti AC, Conley RR, Roberts RC. Mitochondria in the striatum of subjects with schizophrenia: relationship to treatment response. Synapse 2011; 65:215-24. [PMID: 20665724 DOI: 10.1002/syn.20838] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Schizophrenia (SZ) is a severe mental illness with neuropathology in many regions, including the striatum. The typical symptoms of this disease are psychosis (such as hallucinations and delusions), cognitive impairments, and the deficit syndrome. Not all patients respond to treatment and, in those who do, only psychotic symptoms are improved. Imaging studies support a biological distinction between treatment response and resistance, but postmortem examinations of this issue are rare. This study tests the hypotheses that abnormalities in mitochondria, the energy producing organelles in the cell, may correlate with treatment response. Postmortem striatal tissue was obtained from the Maryland Brain Collection. The density of mitochondria (in various neuropil compartments) and the number of mitochondria per synapse (all types of synapses combined) were tallied using electron microscopy and stereology in striatum from SZ subjects (rated treatment responsive or not) and normal controls. The number of mitochondria per synapse was significantly different among groups for both the caudate nucleus (P < 0.025) and putamen (P < 0.002). Compared to controls, treatment-responsive SZ subjects had a 37-43% decrease in the number of mitochondria per synapse in the caudate nucleus and putamen. In the putamen, treatment-responsive subjects also had decreases in this measure compared to treatment-resistant subjects (34%). Our results provide further support for a biological distinction between treatment response and treatment resistance in SZ. Because treatment responders have fewer mitochondria per synapse than controls, although the treatment-resistant subjects have similar results to that of controls, fewer mitochondria per synapse may be related to treatment response.
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Affiliation(s)
- Shahza M Somerville
- Neuroscience and Cognitive Sciences, University of Maryland, Baltimore County, Catonsville 21228, USA
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281
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De Vos A, Anandhakumar J, Van den Brande J, Verduyckt M, Franssens V, Winderickx J, Swinnen E. Yeast as a model system to study tau biology. Int J Alzheimers Dis 2011; 2011:428970. [PMID: 21559193 PMCID: PMC3090044 DOI: 10.4061/2011/428970] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 01/21/2011] [Indexed: 11/20/2022] Open
Abstract
Hyperphosphorylated and aggregated human protein tau constitutes a hallmark of a multitude of neurodegenerative diseases called tauopathies, exemplified by Alzheimer's disease. In spite of an enormous amount of research performed on tau biology, several crucial questions concerning the mechanisms of tau toxicity remain unanswered. In this paper we will highlight some of the processes involved in tau biology and pathology, focusing on tau phosphorylation and the interplay with oxidative stress. In addition, we will introduce the development of a human tau-expressing yeast model, and discuss some crucial results obtained in this model, highlighting its potential in the elucidation of cellular processes leading to tau toxicity.
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Affiliation(s)
- Ann De Vos
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Jayamani Anandhakumar
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Jeff Van den Brande
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Mathias Verduyckt
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Vanessa Franssens
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Erwin Swinnen
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
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282
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Abstract
The structure and function of the mitochondrial network is regulated by mitochondrial biogenesis, fission, fusion, transport and degradation. A well-maintained balance of these processes (mitochondrial dynamics) is essential for neuronal signaling, plasticity and transmitter release. Core proteins of the mitochondrial dynamics machinery play important roles in the regulation of apoptosis, and mutations or abnormal expression of these factors are associated with inherited and age-dependent neurodegenerative disorders. In Parkinson's disease (PD), oxidative stress and mitochondrial dysfunction underlie the development of neuropathology. The recessive Parkinsonism-linked genes PTEN-induced kinase 1 (PINK1) and Parkin maintain mitochondrial integrity by regulating diverse aspects of mitochondrial function, including membrane potential, calcium homeostasis, cristae structure, respiratory activity, and mtDNA integrity. In addition, Parkin is crucial for autophagy-dependent clearance of dysfunctional mitochondria. In the absence of PINK1 or Parkin, cells often develop fragmented mitochondria. Whereas excessive fission may cause apoptosis, coordinated induction of fission and autophagy is believed to facilitate the removal of damaged mitochondria through mitophagy, and has been observed in some types of cells. Compensatory mechanisms may also occur in mice lacking PINK1 that, in contrast to cells and Drosophila, have only mild mitochondrial dysfunction and lack dopaminergic neuron loss. A better understanding of the relationship between the specific changes in mitochondrial dynamics/turnover and cell death will be instrumental to identify potentially neuroprotective pathways steering PINK1-deficient cells towards survival. Such pathways may be manipulated in the future by specific drugs to treat PD and perhaps other neurodegenerative disorders characterized by abnormal mitochondrial function and dynamics.
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Affiliation(s)
- Hansruedi Büeler
- Department of Anatomy and Neurobiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA.
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283
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Eschbach J, Dupuis L. Cytoplasmic dynein in neurodegeneration. Pharmacol Ther 2011; 130:348-63. [PMID: 21420428 DOI: 10.1016/j.pharmthera.2011.03.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 03/01/2011] [Indexed: 12/11/2022]
Abstract
Cytoplasmic dynein 1 (later referred to as dynein) is the major molecular motor moving cargoes such as mitochondria, organelles and proteins towards the minus end of microtubules. Dynein is involved in multiple basic cellular functions, such as mitosis, autophagy and structure of endoplasmic reticulum and Golgi, but also in neuron specific functions in particular retrograde axonal transport. Dynein is regulated by a number of protein complexes, notably by dynactin. Several studies have supported indirectly the involvement of dynein in neurodegeneration associated with Alzheimer's disease, Parkinson's disease, Huntington's disease and motor neuron diseases. First, axonal transport disruption represents a common feature occurring in neurodegenerative diseases. Second, a number of dynein-dependent processes, including autophagy or clearance of aggregation-prone proteins, are found defective in most of these diseases. Third, a number of mutant genes in various neurodegenerative diseases are involved in the regulation of dynein transport. This includes notably mutations in the P150Glued subunit of dynactin that are found in Perry syndrome and motor neuron diseases. Interestingly, gene products that are mutant in Huntington's disease, Parkinson's disease, motor neuron disease or spino-cerebellar ataxia are also involved in the regulation of dynein motor activity or of cargo binding. Despite a constellation of indirect evidence, direct links between the motor itself and neurodegeneration are few, and this might be due to the requirement of fully active dynein for development. Here, we critically review the evidence of dynein involvement in different neurodegenerative diseases and discuss potential underlying mechanisms.
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Affiliation(s)
- Judith Eschbach
- Inserm U692, Laboratoire de Signalisations Moléculaires et Neurodégénérescence, Strasbourg, F-67085, France
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284
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Chu CT. Diversity in the regulation of autophagy and mitophagy: lessons from Parkinson's disease. PARKINSONS DISEASE 2011; 2011:789431. [PMID: 21603187 PMCID: PMC3096099 DOI: 10.4061/2011/789431] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 01/22/2011] [Indexed: 11/20/2022]
Abstract
Selective mitochondrial degradation through autophagy (mitophagy) has emerged as an important homeostatic mechanism in a variety of organisms and contexts. Complete clearance of mitochondria can be observed during normal maturation of certain mammalian cell types, and during certain forms of neuronal cell death. In recent years, autophagy dysregulation has been implicated in toxin-injured dopaminergic neurons as well as in major genetic models of Parkinson's disease (PD), including α-synuclein, leucine-rich repeat kinase 2 (LRRK2), parkin, PTEN-induced kinase 1 (PINK1), and DJ-1. Indeed, PINK1-parkin interactions may form the basis of a mechanism by which dissipation of the inner mitochondrial membrane potential can trigger selective mitochondrial targeting for autophagy. Multiple signals are likely to exist, however, depending upon the trigger for mitophagy. Similarly, the regulation of basal or injury-induced autophagy does not always follow canonical pathways described for nutrient deprivation. Implications of this regulatory diversity are discussed in the context of neuronal function and survival. Further studies are needed to address whether alterations in autophagy regulation play a directly injurious role in PD pathogenesis, or if the observed changes reflect impaired, appropriate, or excessive autophagic responses to other forms of cellular injury.
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Affiliation(s)
- Charleen T Chu
- Division of Neuropathology, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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285
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Campbell GR, Mahad DJ. Mitochondria as crucial players in demyelinated axons: lessons from neuropathology and experimental demyelination. Autoimmune Dis 2011; 2011:262847. [PMID: 21331147 PMCID: PMC3038418 DOI: 10.4061/2011/262847] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 11/29/2010] [Indexed: 01/18/2023] Open
Abstract
Mitochondria are the most efficient producers of energy in the form of ATP. Energy demands of axons, placed at relatively great distances from the neuronal cell body, are met by mitochondria, which when functionally compromised, produce reactive oxygen species (ROS) in excess. Axons are made metabolically efficient by myelination, which enables saltatory conduction. The importance of mitochondria for maintaining the structural integrity of myelinated axons is illustrated by neuroaxonal degeneration in primary mitochondrial disorders. When demyelinated, the compartmentalisation of ion channels along axons is disrupted. The redistribution of electrogenic machinery is thought to increase the energy demand of demyelinated axons. We review related studies that focus on mitochondria within unmyelinated, demyelinated and dysmyelinated axons in the central nervous system. Based on neuropathological observations we propose the increase in mitochondrial presence within demyelinated axons as an adaptive process to the increased energy need. An increased presence of mitochondria would also increase the capacity to produce deleterious agents such as ROS when functionally compromised. Given the lack of direct evidence of a beneficial or harmful effect of mitochondrial changes, the precise role of increased mitochondrial presence within axons due to demyelination needs to be further explored in experimental demyelination in-vivo and in-vitro.
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Affiliation(s)
- Graham R Campbell
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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286
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Stroebel A, Welzel O, Kornhuber J, Groemer TW. Background determination-based detection of scattered peaks. Microsc Res Tech 2011; 73:1115-22. [PMID: 20981757 DOI: 10.1002/jemt.20858] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In many instances of signal and image processing, it is indispensable to precisely distinguish scattered peaks from a background, e.g., camera signals in microscopy. Here we addressed the detection of Gaussian signals in simulated line profiles (LP) comparable with e.g., fluorescence microscopy data. In a first step, we measured the applicability of histogram-based global background estimation. We find that the method is valid for typical scattered Gaussian signals if they are averagely separated by interpeak distances of 5.5 standard deviations. This enabled us to design global background determination-based peak detection (GBPD). GBPD was compared with two local background determination-based signal detection methods that had been designed for analysis of electrophysiological data and microscopy images, respectively. We were able to prove via receiver-operator characteristic (ROC) comparisons of signal-to-noise ratio (SNR), interpeak distance, and filtering behavior that, when applicable, GBPD brings advantages in knowledge needed a priori, performance at any SNR, controllability and spatial resolution.
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Affiliation(s)
- Armin Stroebel
- Department of Psychiatry and Psychotherapy, University of Erlangen-Nuremberg, Germany
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287
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Sau D, Rusmini P, Crippa V, Onesto E, Bolzoni E, Ratti A, Poletti A. Dysregulation of axonal transport and motorneuron diseases. Biol Cell 2011; 103:87-107. [PMID: 21250942 DOI: 10.1042/bc20100093] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
MNDs (motorneuron diseases) are neurodegenerative disorders in which motorneurons located in the motor cortex, in the brainstem and in the spinal cord are affected. These diseases in their inherited or sporadic forms are mainly characterized by motor dysfunctions, occasionally associated with cognitive and behavioural alterations. Although these diseases show high variability in onset, progression and clinical symptoms, they share common pathological features, and motorneuronal loss invariably leads to muscle weakness and atrophy. One of the most relevant aspect of these disorders is the occurrence of defects in axonal transport, which have been postulated to be either a direct cause, or a consequence, of motorneuron degeneration. In fact, due to their peculiar morphology and high energetic metabolism, motorneurons deeply rely on efficient axonal transport processes. Dysfunction of axonal transport is known to adversely affect motorneuronal metabolism, inducing progressive degeneration and cell death. In this regard, the understanding of the fine mechanisms at the basis of the axonal transport process and of their possible alterations may help shed light on MND pathological processes. In the present review, we will summarize what is currently known about the alterations of axonal transport found to be either causative or a consequence of MNDs.
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Affiliation(s)
- Daniela Sau
- Dipartimento di Endocrinologia, Fisiopatologia e Biologia Applicata, and Centre of Excellence on Neurodegenerative Diseases, Università degli Studi di Milano, Milan, Italy
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288
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Somerville SM, Conley RR, Roberts RC. Mitochondria in the striatum of subjects with schizophrenia. World J Biol Psychiatry 2011; 12:48-56. [PMID: 20698738 DOI: 10.3109/15622975.2010.505662] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVES Schizophrenia is a severe mental illness that manifests pathology in many brain regions, including the striatum. Among the abnormalities in schizophrenia are those related to mitochondria. The present study sought to determine whether the number of mitochondria was affected at the level of the synapse. METHODS Human postmortem striatum from schizophrenia subjects and controls was examined at the ultrastructural level. The density of mitochondria and synapses were tabulated using stereology. RESULTS There were similar overall numbers of mitochondria in the caudate nucleus and putamen of schizophrenia subjects vs. controls, but a differential distribution of existing mitochondria. Schizophrenia subjects had 26?30% fewer mitochondria per synapse compared to controls. This may contribute to the pathophysiology of the illness, may be a medication effect, or an adaptive response to normalize the high number of striatal synapses we have previously found. The higher density of mitochondria in dendrites in the caudate nucleus in certain subgroups of schizophrenia vs. controls (>34%) may be related to more synaptic inputs. CONCLUSIONS The role of mitochondria in the various symptoms of schizophrenia is still unclear. A comparison of schizophrenia subjects with differing symptoms or treatment response might shed light on whether differences in mitochondrial density are abnormal or adaptive.
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Affiliation(s)
- Shahza M Somerville
- Neuroscience and Cognitive Sciences, University of Maryland, Baltimore County, Catonsville, MD, USA
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289
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Esteves AR, Arduíno DM, Silva DFF, Oliveira CR, Cardoso SM. Mitochondrial Dysfunction: The Road to Alpha-Synuclein Oligomerization in PD. PARKINSON'S DISEASE 2011; 2011:693761. [PMID: 21318163 PMCID: PMC3026982 DOI: 10.4061/2011/693761] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 12/21/2010] [Accepted: 12/27/2010] [Indexed: 12/21/2022]
Abstract
While the etiology of Parkinson's disease remains largely elusive, there is accumulating evidence suggesting that mitochondrial dysfunction occurs prior to the onset of symptoms in Parkinson's disease. Mitochondria are remarkably primed to play a vital role in neuronal cell survival since they are key regulators of energy metabolism (as ATP producers), of intracellular calcium homeostasis, of NAD(+)/NADH ratio, and of endogenous reactive oxygen species production and programmed cell death. In this paper, we focus on mitochondrial dysfunction-mediated alpha-synuclein aggregation. We highlight some of the findings that provide proof of evidence for a mitochondrial metabolism control in Parkinson's disease, namely, mitochondrial regulation of microtubule-dependent cellular traffic and autophagic lysosomal pathway. The knowledge that microtubule alterations may lead to autophagic deficiency and may compromise the cellular degradation mechanisms that culminate in the progressive accumulation of aberrant protein aggregates shields new insights to the way we address Parkinson's disease. In line with this knowledge, an innovative window for new therapeutic strategies aimed to restore microtubule network may be unlocked.
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Affiliation(s)
- A. R. Esteves
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004 Coimbra, Portugal
| | - D. M. Arduíno
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004 Coimbra, Portugal
| | - D. F. F. Silva
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004 Coimbra, Portugal
| | - C. R. Oliveira
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004 Coimbra, Portugal
- Faculdade de Medicina, Universidade de Coimbra, 3000 Coimbra, Portugal
| | - S. M. Cardoso
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004 Coimbra, Portugal
- Faculdade de Medicina, Universidade de Coimbra, 3000 Coimbra, Portugal
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290
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Fujimoto M, Hayashi T. New Insights into the Role of Mitochondria-Associated Endoplasmic Reticulum Membrane. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 292:73-117. [DOI: 10.1016/b978-0-12-386033-0.00002-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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291
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O'Malley KL. The role of axonopathy in Parkinson's disease. Exp Neurobiol 2010; 19:115-9. [PMID: 22110350 PMCID: PMC3214783 DOI: 10.5607/en.2010.19.3.115] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 12/31/2010] [Indexed: 01/07/2023] Open
Abstract
New genetic and environmental studies of Parkinson's disease have revealed early problems in synaptic function and connectivity indicating that axonal impairment may be an important hallmark in this disorder. Since many studies suggest that axonal dysfunction precedes cell body loss, it is critical to target axons with treatments aimed at preserving "connectivity" as well as to develop and verify "biomarkers" with which to assess disease progression and drug efficacy.
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Affiliation(s)
- Karen L O'Malley
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, Missouri, 63110, USA
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292
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Harvey A, Gibson T, Lonergan T, Brenner C. Dynamic regulation of mitochondrial function in preimplantation embryos and embryonic stem cells. Mitochondrion 2010; 11:829-38. [PMID: 21168533 DOI: 10.1016/j.mito.2010.12.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 12/06/2010] [Accepted: 12/09/2010] [Indexed: 01/14/2023]
Abstract
Mitochondrial function is dependent upon regulation of biogenesis and dynamics. A number of studies have documented the importance of these organelles in both preimplantation embryos and embryonic stem cells (ESCs), however it remains unclear how mitochondria respond to their immediate microenvironment through modulation of morphology and movement, or whether perturbations in these processes will have a significant impact following differentiation/implantation. Here we review existing literature on two key aspects of nuclear-mitochondrial cross-talk and the dynamic processes involved in mediating mitochondrial function through regulation of mitochondrial biogenesis, morphology and movement, with particular emphasis on embryos and ESCs.
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Affiliation(s)
- Alexandra Harvey
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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293
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Vives-Bauza C, Przedborski S. Mitophagy: the latest problem for Parkinson's disease. Trends Mol Med 2010; 17:158-65. [PMID: 21146459 DOI: 10.1016/j.molmed.2010.11.002] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 11/09/2010] [Accepted: 11/11/2010] [Indexed: 12/13/2022]
Abstract
Parkinson's disease (PD) is a common neurodegenerative disorder of unknown cause. Some familial forms of PD are provoked by mutations in the genes encoding for the PTEN (phosphatase and tensin homolog)-induced putative kinase-1 (PINK1) and Parkin. Mounting evidence indicates that PINK1 and Parkin might function in concert to modulate mitochondrial degradation, termed mitophagy. However, the molecular mechanisms by which PINK1/Parkin affect mitophagy are just beginning to be elucidated. Herein, we review the main advances in our understanding of the PINK1/Parkin pathway. Because of the phenotypic similarities among the different forms of PD, a better understanding of PINK1/Parkin biology might have far-reaching pathogenic and therapeutic implications for both the inherited and the sporadic forms of PD.
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294
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Cheng A, Hou Y, Mattson MP. Mitochondria and neuroplasticity. ASN Neuro 2010; 2:e00045. [PMID: 20957078 PMCID: PMC2949087 DOI: 10.1042/an20100019] [Citation(s) in RCA: 312] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 08/06/2010] [Accepted: 08/13/2010] [Indexed: 12/22/2022] Open
Abstract
The production of neurons from neural progenitor cells, the growth of axons and dendrites and the formation and reorganization of synapses are examples of neuroplasticity. These processes are regulated by cell-autonomous and intercellular (paracrine and endocrine) programs that mediate responses of neural cells to environmental input. Mitochondria are highly mobile and move within and between subcellular compartments involved in neuroplasticity (synaptic terminals, dendrites, cell body and the axon). By generating energy (ATP and NAD(+)), and regulating subcellular Ca(2+) and redox homoeostasis, mitochondria may play important roles in controlling fundamental processes in neuroplasticity, including neural differentiation, neurite outgrowth, neurotransmitter release and dendritic remodelling. Particularly intriguing is emerging data suggesting that mitochondria emit molecular signals (e.g. reactive oxygen species, proteins and lipid mediators) that can act locally or travel to distant targets including the nucleus. Disturbances in mitochondrial functions and signalling may play roles in impaired neuroplasticity and neuronal degeneration in Alzheimer's disease, Parkinson's disease, psychiatric disorders and stroke.
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Key Words
- AD, Alzheimer's disease
- AP, adaptor protein
- APP, amyloid precursor protein
- Aβ, amyloid β-peptide
- BDNF, brain-derived neurotrophic factor
- CR, caloric restriction
- CREB, cAMP-response-element-binding protein
- CaMK, Ca2+/calmodulin-dependent protein kinase
- ES, embryonic stem
- ETC, electron transport chain
- HD, Huntington's disease
- LRRK2, leucine-rich repeat kinase 2
- LTP, long-term potentiation
- MAPK, mitogen-activated protein kinase
- Mn-SOD, manganese superoxide dismutase
- NGF, nerve growth factor
- NMDA, N-methyl-d-aspartate
- Nrf1, nuclear respiratory factor 1
- OPA1, Optic Atrophy-1
- PD, Parkinson's disease
- PGC1α, peroxisome-proliferator-activated receptor γ co-activator 1α
- PINK1, PTEN (phosphatase and tensin homologue deleted on chromosome 10)-induced kinase 1
- PPAR, peroxisome-proliferator-activated receptor
- UCP, uncoupling protein
- mitochondria biogenesis
- mitochondria fission and fusion
- neural progenitor cell
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Affiliation(s)
- Aiwu Cheng
- *Laboratory of Neurosciences, National Institute of Aging Intramural Research Program, Baltimore, MD 21224, U.S.A
| | - Yan Hou
- *Laboratory of Neurosciences, National Institute of Aging Intramural Research Program, Baltimore, MD 21224, U.S.A
| | - Mark P Mattson
- *Laboratory of Neurosciences, National Institute of Aging Intramural Research Program, Baltimore, MD 21224, U.S.A
- †Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
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295
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Vos M, Lauwers E, Verstreken P. Synaptic mitochondria in synaptic transmission and organization of vesicle pools in health and disease. Front Synaptic Neurosci 2010; 2:139. [PMID: 21423525 PMCID: PMC3059669 DOI: 10.3389/fnsyn.2010.00139] [Citation(s) in RCA: 196] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Accepted: 08/09/2010] [Indexed: 12/21/2022] Open
Abstract
Cell types rich in mitochondria, including neurons, display a high energy demand and a need for calcium buffering. The importance of mitochondria for proper neuronal function is stressed by the occurrence of neurological defects in patients suffering from a great variety of diseases caused by mutations in mitochondrial genes. Genetic and pharmacological evidence also reveal a role of these organelles in various aspects of neuronal physiology and in the pathogenesis of neurodegenerative disorders. Yet the mechanisms by which mitochondria can affect neurotransmission largely remain to be elucidated. In this review we focus on experimental data that suggest a critical function of synaptic mitochondria in the function and organization of synaptic vesicle pools, and in neurotransmitter release during intense neuronal activity. We discuss how calcium handling, ATP production and other mitochondrial mechanisms may influence synaptic vesicle pool organization and synaptic function. Given the link between synaptic mitochondrial function and neuronal communication, efforts toward better understanding mitochondrial biology may lead to novel therapeutic approaches of neurological disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and psychiatric disorders that are at least in part caused by mitochondrial deficits.
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Affiliation(s)
- Melissa Vos
- Department of Molecular and Developmental Genetics VIB, Leuven, Belgium
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296
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Kim JY, Casaccia P. HDAC1 in axonal degeneration: A matter of subcellular localization. Cell Cycle 2010; 9:3680-4. [PMID: 20930523 PMCID: PMC2995919 DOI: 10.4161/cc.9.18.12716] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Accepted: 08/30/2010] [Indexed: 12/21/2022] Open
Abstract
Multiple sclerosis (MS) is a disease characterized by inflammatory demyelination and a strong neurodegenerative component. Axonal damage is characteristically detected in MS brains, although the pathogenic mechanisms are not clearly understood. Here, we discuss the importance of HDAC1 localization as one of the potential mechanisms initiating damage in demyelinating conditions. We suggest the occurrence of a two-stage mechanism of damage. The first event is a calcium-dependent HDAC1 nuclear export in a CRM1-dependent manner and the second event is the interruption of mitochondrial transport resulting from the cytoplasmic localization of HDAC1. In the cytosol of neurons challenged by cytokines and excitatory aminoacids, HDAC1 formed complexes with motor-protein and microtubules and this resulted in blockade of axonal transport and release of cargo from motor proteins. We suggest that these findings might be the framework for future studies and for the development of novel therapeutic targets for axonal damage in demyelinating conditions.
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Affiliation(s)
- Jin Young Kim
- Department of Neuroscience and Genetics & Genomics, Mount Sinai School of Medicine, New York, NY, USA
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297
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Chetta J, Kye C, Shah SB. Cytoskeletal dynamics in response to tensile loading of mammalian axons. Cytoskeleton (Hoboken) 2010; 67:650-65. [DOI: 10.1002/cm.20478] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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298
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Pathak D, Sepp KJ, Hollenbeck PJ. Evidence that myosin activity opposes microtubule-based axonal transport of mitochondria. J Neurosci 2010; 30:8984-92. [PMID: 20592219 PMCID: PMC2904968 DOI: 10.1523/jneurosci.1621-10.2010] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 04/22/2010] [Accepted: 05/10/2010] [Indexed: 11/21/2022] Open
Abstract
Neurons transport and position mitochondria using a combination of saltatory, bidirectional movements and stationary docking. Axonal mitochondria move along microtubules (MTs) using kinesin and dynein motors, but actin and myosin also play a poorly defined role in their traffic. To ascertain this role, we have used RNA interference (RNAi) to deplete specific myosin motors in cultured Drosophila neurons and quantified the effects on mitochondrial motility. We produced a fly strain expressing the Caenorhabditis elegans RNA transporter SID-1 in neurons to increase the efficacy of RNAi in primary cultures. These neurons exhibited significantly increased RNAi-mediated knockdown of gene expression compared with neurons not expressing this transporter. Using this system, we observed a significant increase in mitochondrial transport during myosin V depletion. Mitochondrial mean velocity and duty cycle were augmented in both anterograde and retrograde directions, and the fraction of mitochondrial flux contained in long runs almost doubled for anterograde movement. Myosin VI depletion increased the same movement parameters but was selective for retrograde movement, whereas myosin II depletion produced no phenotype. An additional effect of myosin V depletion was an increase in mitochondrial length. These data indicate that myosin V and VI play related but distinct roles in regulating MT-based mitochondrial movement: they oppose, rather than complement, protracted MT-based movements and perhaps facilitate organelle docking.
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Affiliation(s)
- Divya Pathak
- Department of Biological Sciences and Purdue University Integrative Neuroscience Program, West Lafayette, IN 47907, and
| | - Katharine J. Sepp
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Peter J. Hollenbeck
- Department of Biological Sciences and Purdue University Integrative Neuroscience Program, West Lafayette, IN 47907, and
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299
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Kiryu-Seo S, Ohno N, Kidd GJ, Komuro H, Trapp BD. Demyelination increases axonal stationary mitochondrial size and the speed of axonal mitochondrial transport. J Neurosci 2010; 30:6658-66. [PMID: 20463228 PMCID: PMC2885867 DOI: 10.1523/jneurosci.5265-09.2010] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 03/26/2010] [Accepted: 03/30/2010] [Indexed: 01/23/2023] Open
Abstract
Axonal degeneration contributes to permanent neurological disability in inherited and acquired diseases of myelin. Mitochondrial dysfunction has been proposed as a major contributor to this axonal degeneration. It remains to be determined, however, if myelination, demyelination, or remyelination alter the size and distribution of axonal mitochondrial stationary sites or the rates of axonal mitochondrial transport. Using live myelinated rat dorsal root ganglion (DRG) cultures, we investigated whether myelination and lysolecithin-induced demyelination affect axonal mitochondria. Myelination increased the size of axonal stationary mitochondrial sites by 2.3-fold. After demyelination, the size of axonal stationary mitochondrial sites was increased by an additional 2.2-fold and the transport velocity of motile mitochondria was increased by 47%. These measures returned to the levels of myelinated axons after remyelination. Demyelination induced activating transcription factor 3 (ATF3) in DRG neurons. Knockdown of neuronal ATF3 by short hairpin RNA abolished the demyelination-induced increase in axonal mitochondrial transport and increased nitrotyrosine immunoreactivity in axonal mitochondria, suggesting that neuronal ATF3 expression and increased mitochondrial transport protect demyelinated axons from oxidative damage. In response to insufficient ATP production, demyelinated axons increase the size of stationary mitochondrial sites and thereby balance ATP production with the increased energy needs of nerve conduction.
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Affiliation(s)
- Sumiko Kiryu-Seo
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Nobuhiko Ohno
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Grahame J. Kidd
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Hitoshi Komuro
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Bruce D. Trapp
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
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300
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Ward MW, Concannon CG, Whyte J, Walsh CM, Corley B, Prehn JHM. The amyloid precursor protein intracellular domain(AICD) disrupts actin dynamics and mitochondrial bioenergetics. J Neurochem 2010; 113:275-84. [PMID: 20405578 DOI: 10.1111/j.1471-4159.2010.06615.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The amyloid precursor protein (APP) is critically involved in the pathogenesis of Alzheimer's disease, and is strongly up-regulated in response to traumatic, metabolic, or toxic insults to the nervous system. The processing of APP by gamma/epsilon-secretase activity results in the generation of the APP intracellular domain (AICD). Previously, we have shown that AICD induces the expression of genes (transgelin, alpha2-actin) with functional roles in actin organization and dynamics and demonstrated that the induction of AICD and its co-activator Fe65 (AICD/Fe65) resulted in a loss of organized filamentous actin structures within the cell. As mitochondrial function is thought to be reliant on ordered actin dynamics, we examined mitochondrial function in human SHEP neuroblastoma cells inducibly expressing AICD/Fe65. Confocal analysis of the mitochondrial membrane potential (DeltaPsim) identified a significant decrease in the DeltaPsim in the AICD50/Fe65 over-expressing cells. This was paralleled by significantly reduced ATP levels and decreased basal superoxide production. Overexpression of the proposed AICD target gene transgelin in SHEP-SF parental cells and primary neurons was sufficient to destabilize actin filaments, depolarize DeltaPsim, and significantly alter mitochondrial distribution and morphology. Our data demonstrate that the induction of AICD/Fe65 or transgelin significantly alters actin dynamics and mitochondrial function in neuronal cells.
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Affiliation(s)
- Manus W Ward
- Department of Physiology and Medical Physics and RCSI Neuroscience Research Centre, Royal College of Surgeons in Ireland, Dublin 2, Ireland
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