101
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Fuller BF, Cortes DF, Landis MK, Yohannes H, Griffin HE, Stafflinger JE, Bowers MS, Lewis MH, Fox MA, Ottens AK. Exposure of rats to environmental tobacco smoke during cerebellar development alters behavior and perturbs mitochondrial energetics. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:1684-1691. [PMID: 23014793 PMCID: PMC3548280 DOI: 10.1289/ehp.1104857] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 09/26/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Environmental tobacco smoke (ETS) exposure is linked to developmental deficits and disorders with known cerebellar involvement. However, direct biological effects and underlying neurochemical mechanisms remain unclear. OBJECTIVES We sought to identify and evaluate underlying neurochemical change in the rat cerebellum with ETS exposure during critical period development. METHODS We exposed rats to daily ETS (300, 100, and 0 µg/m3 total suspended particulate) from postnatal day 8 (PD8) to PD23 and then assayed the response at the behavioral, neuroproteomic, and cellular levels. RESULTS Postnatal ETS exposure induced heightened locomotor response in a novel environment on par initially with amphetamine stimulation. The cerebellar mitochondrial subproteome was significantly perturbed in the ETS-exposed rats. Findings revealed a dose-dependent up-regulation of aerobic processes through the modification and increased translocation of Hk1 to the mitochondrion with corresponding heightened ATP synthase expression. ETS exposure also induced a dose-dependent increase in total Dnm1l mitochondrial fission factor; although more active membrane-bound Dnm1l was found at the lower dose. Dnm1l activation was associated with greater mitochondrial staining, particularly in the molecular layer, which was independent of stress-induced Bcl-2 family dynamics. Further, electron microscopy associated Dnm1l-mediated mitochondrial fission with increased biogenesis, rather than fragmentation. CONCLUSIONS The critical postnatal period of cerebellar development is vulnerable to the effects of ETS exposure, resulting in altered behavior. The biological effect of ETS is underlain in part by a Dnm1l-mediated mitochondrial energetic response at a time of normally tight control. These findings represent a novel mechanism by which environmental exposure can impact neurodevelopment and function.
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Affiliation(s)
- Brian F Fuller
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia 23298-0709, USA
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102
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Anitha A, Nakamura K, Thanseem I, Yamada K, Iwayama Y, Toyota T, Matsuzaki H, Miyachi T, Yamada S, Tsujii M, Tsuchiya KJ, Matsumoto K, Iwata Y, Suzuki K, Ichikawa H, Sugiyama T, Yoshikawa T, Mori N. Brain region-specific altered expression and association of mitochondria-related genes in autism. Mol Autism 2012; 3:12. [PMID: 23116158 PMCID: PMC3528421 DOI: 10.1186/2040-2392-3-12] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 10/04/2012] [Indexed: 02/02/2023] Open
Abstract
UNLABELLED BACKGROUND Mitochondrial dysfunction (MtD) has been observed in approximately five percent of children with autism spectrum disorders (ASD). MtD could impair highly energy-dependent processes such as neurodevelopment, thereby contributing to autism. Most of the previous studies of MtD in autism have been restricted to the biomarkers of energy metabolism, while most of the genetic studies have been based on mutations in the mitochondrial DNA (mtDNA). Despite the mtDNA, most of the proteins essential for mitochondrial replication and function are encoded by the genomic DNA; so far, there have been very few studies of those genes. Therefore, we carried out a detailed study involving gene expression and genetic association studies of genes related to diverse mitochondrial functions. METHODS For gene expression analysis, postmortem brain tissues (anterior cingulate gyrus (ACG), motor cortex (MC) and thalamus (THL)) from autism patients (n=8) and controls (n=10) were obtained from the Autism Tissue Program (Princeton, NJ, USA). Quantitative real-time PCR arrays were used to quantify the expression of 84 genes related to diverse functions of mitochondria, including biogenesis, transport, translocation and apoptosis. We used the delta delta Ct (∆∆Ct) method for quantification of gene expression. DNA samples from 841 Caucasian and 188 Japanese families were used in the association study of genes selected from the gene expression analysis. FBAT was used to examine genetic association with autism. RESULTS Several genes showed brain region-specific expression alterations in autism patients compared to controls. Metaxin 2 (MTX2), neurofilament, light polypeptide (NEFL) and solute carrier family 25, member 27 (SLC25A27) showed consistently reduced expression in the ACG, MC and THL of autism patients. NEFL (P = 0.038; Z-score 2.066) and SLC25A27 (P = 0.046; Z-score 1.990) showed genetic association with autism in Caucasian and Japanese samples, respectively. The expression of DNAJC19, DNM1L, LRPPRC, SLC25A12, SLC25A14, SLC25A24 and TOMM20 were reduced in at least two of the brain regions of autism patients. CONCLUSIONS Our study, though preliminary, brings to light some new genes associated with MtD in autism. If MtD is detected in early stages, treatment strategies aimed at reducing its impact may be adopted.
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Affiliation(s)
- Ayyappan Anitha
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Kazuhiko Nakamura
- Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Ismail Thanseem
- Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Kazuo Yamada
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, 351 0198, Japan
| | - Yoshimi Iwayama
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, 351 0198, Japan
| | - Tomoko Toyota
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, 351 0198, Japan
| | - Hideo Matsuzaki
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Taishi Miyachi
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Satoru Yamada
- Tokyo Metropolitan Children's Medical Center, 2-8-29 Musashidai, Fuchu, 183 8561, Japan
| | - Masatsugu Tsujii
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan.,Faculty of Sociology, Chukyo University, 101 Tokodachi, Toyota, 470 0393, Japan
| | - Kenji J Tsuchiya
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Kaori Matsumoto
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Yasuhide Iwata
- Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Katsuaki Suzuki
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Hironobu Ichikawa
- Tokyo Metropolitan Children's Medical Center, 2-8-29 Musashidai, Fuchu, 183 8561, Japan
| | - Toshiro Sugiyama
- Department of Child and Adolescent Psychiatry, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
| | - Takeo Yoshikawa
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, 351 0198, Japan
| | - Norio Mori
- Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan.,Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431 3192, Japan
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103
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Lee JS, Yoon YG, Yoo SH, Jeong NY, Jeong SH, Lee SY, Jung DI, Jeong SY, Yoo YH. Histone deacetylase inhibitors induce mitochondrial elongation. J Cell Physiol 2012; 227:2856-69. [PMID: 21928346 DOI: 10.1002/jcp.23027] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Although various stimuli-inducing cell demise are known to alter mitochondrial morphology, it is currently debated whether alteration of mitochondrial morphology is per se responsible for apoptosis execution or prevention. This study was undertaken to examine the effect of histone deacetylase (HDAC) inhibitors on mitochondrial fusion-fission equilibrium. The mechanism underlying HDAC inhibitor-induced alteration of mitochondrial morphology was examined in various cells including primary cultured cells and untransformed and cancer cell lines treated with seven different HDAC inhibitors. Suberoylanilide hydroxamic acid (SAHA)-induced mitochondrial elongation in both Hep3B and Bcl-2-overexpressing Hep3B cells, apart from its apoptosis induction function. SAHA significantly decreased the expression of mitochondrial fission protein Fis1 and reduced the translocation of Drp1 to the mitochondria. Fis1 overexpression attenuated SAHA-induced mitochondrial elongation. In addition, depletion of mitochondrial fusion proteins, Mfn1 or Opa1, by RNA interference also attenuated SAHA-induced mitochondrial elongation. All of the HDAC inhibitors we examined induced mitochondrial elongation in all the cell types tested at both subtoxic and toxic concentrations. These results indicate that HDAC inhibitors induce mitochondrial elongation, irrespective of the induction of apoptosis, which may be linked to alterations of mitochondrial dynamics regulated by mitochondrial morphology-regulating proteins. Since mitochondria have recently emerged as attractive targets for cancer therapy, our findings that HDAC inhibitors altered mitochondrial morphology may support the rationale for these agents as novel therapeutic approaches against cancer. Further, the present study may provide insight into a valuable experimental strategy for simple manipulation of mitochondrial morphology.
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Affiliation(s)
- Jee Suk Lee
- Department of Anatomy and Cell Biology and Mitochondria Hub Regulation Center, College of Medicine, Dong-A University, Busan, Republic of Korea
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104
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Mitochondrial dynamics in cancer and neurodegenerative and neuroinflammatory diseases. Int J Cell Biol 2012; 2012:729290. [PMID: 22792111 PMCID: PMC3391904 DOI: 10.1155/2012/729290] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 04/12/2012] [Indexed: 11/18/2022] Open
Abstract
Mitochondria are key organelles in the cell, hosting essential functions, from biosynthetic and metabolic pathways, to oxidative phosphorylation and ATP production, from calcium buffering to red-ox homeostasis and apoptotic signalling pathways. Mitochondria are also dynamic organelles, continuously fusing and dividing, and their localization, size and trafficking are finely regulated. Moreover, in recent decades, alterations in mitochondrial function and dynamics have been implicated in an increasing number of diseases. In this review, we focus on the relationship clarified hitherto between mitochondrial dynamics and cancer, neurodegenerative and neuroinflammatory diseases.
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105
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Wakabayashi T, Kosaka J, Mori T, Yamada H. Prolonged expression of Puma in cholinergic amacrine cells during the development of rat retina. J Histochem Cytochem 2012; 60:777-88. [PMID: 22736709 DOI: 10.1369/0022155412452737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During development of the nervous system, large numbers of neurons are overproduced and then eliminated by programmed cell death. Puma is a BH3-only protein that is reported to be involved in the initiation of developmental programmed cell death in rodent retinal neurons. The expression and cellular localization of Puma in retinal tissues during development are not, however, well known. Here the authors report the expression pattern of Puma during retinal development in the rat. During the period of programmed cell death in the retina, Puma was expressed in some members of each retinal neuron, including retinal ganglion cells, amacrine cells, bipolar cells, horizontal cells, and photoreceptor cells. Although the developmental programmed cell death of cholinergic amacrine cells is known to be independent of Puma, this protein was expressed in almost all their dendrites and somata of cholinergic amacrine cells at postnatal age 2 to 3 weeks, and it continued to be detected in cholinergic dendrites in the inner plexiform layer for up to 8 weeks after birth. These results suggest that Puma has some significant roles in retinal neurons after eye opening, especially that of cholinergic amacrine cells, in addition to programmed cell death of retinal neurons before eye opening.
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Affiliation(s)
- Taketoshi Wakabayashi
- Department of Anatomy and Cell Science, Kansai Medical University, Moriguchi, Japan.
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106
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Van Laar VS, Berman SB. The interplay of neuronal mitochondrial dynamics and bioenergetics: implications for Parkinson's disease. Neurobiol Dis 2012; 51:43-55. [PMID: 22668779 DOI: 10.1016/j.nbd.2012.05.015] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 05/07/2012] [Accepted: 05/24/2012] [Indexed: 12/15/2022] Open
Abstract
The dynamic properties of mitochondria (mitochondrial fission, fusion, transport biogenesis and degradation) are critical for neuronal function and health, and dysregulation of mitochondrial dynamics has been increasingly linked to the pathogenesis of Parkinson's disease (PD). Mitochondrial dynamics and bioenergetics are interconnected, and this is of particular importance in neurons, which have a unique bioenergetic profile due to their energetic dependence on mitochondria and specialized, compartmentalized energetic needs. In this review, we summarize the interplay of mitochondrial dynamics and bioenergetics, and its particular relevance for neurodegeneration. Evidence linking dysregulation of mitochondrial dynamics to PD is presented from both toxin and genetic models, including newly emerging details of how PD-relevant genes PTEN-induced kinase 1 (PINK1) and Parkin regulate fission, fusion, mitophagy and transport. Finally, we discuss how neuronal bioenergetics may impact PD-relevant regulation of mitochondrial dynamics, and possible implications for understanding the role of mitochondrial dynamics in PD.
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Affiliation(s)
- Victor S Van Laar
- University of Pittsburgh Department of Neurology, Pittsburgh Institute for Neurodegenerative Diseases, Pittsburgh, PA 15213, USA
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107
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Elgass K, Pakay J, Ryan MT, Palmer CS. Recent advances into the understanding of mitochondrial fission. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:150-61. [PMID: 22580041 DOI: 10.1016/j.bbamcr.2012.05.002] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/24/2012] [Accepted: 05/02/2012] [Indexed: 12/20/2022]
Abstract
Mitochondria exist as a highly dynamic tubular network, and their morphology is governed by the delicate balance between frequent fusion and fission events, as well as by interactions with the cytoskeleton. Alterations in mitochondrial morphology are associated with changes in metabolism, cell development and cell death, whilst several human pathologies have been associated with perturbations in the cellular machinery that coordinate these processes. Mitochondrial fission also contributes to ensuring the proper distribution of mitochondria in response to the energetic requirements of the cell. The master mediator of fission is Dynamin related protein 1 (Drp1), which polymerises and constricts mitochondria to facilitate organelle division. The activity of Drp1 at the mitochondrial outer membrane is regulated through post-translational modifications and interactions with mitochondrial receptor and accessory proteins. This review will concentrate on recent advances made in delineating the mechanism of mitochondrial fission, and will highlight the importance of mitochondrial fission in health and disease. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology.
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Affiliation(s)
- Kirstin Elgass
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
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108
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Hardwick JM, Chen YB, Jonas EA. Multipolar functions of BCL-2 proteins link energetics to apoptosis. Trends Cell Biol 2012; 22:318-28. [PMID: 22560661 DOI: 10.1016/j.tcb.2012.03.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 03/26/2012] [Accepted: 03/26/2012] [Indexed: 10/28/2022]
Abstract
Classical apoptotic cell death is now sufficiently well understood to be interrogated with mathematical modeling and manipulated with targeted drugs for clinical benefit. However, a biological black hole has emerged with the realization that apoptosis regulators are functionally multipolar. BCL-2 family proteins appear to have much greater effects on cells than can be explained by their known roles in apoptosis. Although these effects may be observable simply because the cell is not dead, the general assumption is that BCL-2 proteins have undiscovered biochemical activities. Conversely, these as yet uncharacterized day-jobs also may underlie their profound effects on cell survival, challenging current assumptions about classical apoptosis. Even their sub-mitochondrial localizations remain controversial. Here we attempt to integrate seemingly conflicting information with the prospect that BCL-2 proteins themselves may be the critical crosstalk between life and death.
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Affiliation(s)
- J Marie Hardwick
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
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109
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von Bernhardi R, Eugenín J. Alzheimer's disease: redox dysregulation as a common denominator for diverse pathogenic mechanisms. Antioxid Redox Signal 2012; 16:974-1031. [PMID: 22122400 DOI: 10.1089/ars.2011.4082] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia and a progressive neurodegeneration that appears to result from multiple pathogenic mechanisms (including protein misfolding/aggregation, involved in both amyloid β-dependent senile plaques and tau-dependent neurofibrillary tangles), metabolic and mitochondrial dysfunction, excitoxicity, calcium handling impairment, glial cell dysfunction, neuroinflammation, and oxidative stress. Oxidative stress, which could be secondary to several of the other pathophysiological mechanisms, appears to be a major determinant of the pathogenesis and progression of AD. The identification of oxidized proteins common for mild cognitive impairment and AD suggests that key oxidation pathways are triggered early and are involved in the initial progression of the neurodegenerative process. Abundant data support that oxidative stress, also considered as a main factor for aging, the major risk factor for AD, can be a common key element capable of articulating the divergent nature of the proposed pathogenic factors. Pathogenic mechanisms influence each other at different levels. Evidence suggests that it will be difficult to define a single-target therapy resulting in the arrest of progression or the improvement of AD deterioration. Since oxidative stress is present from early stages of disease, it appears as one of the main targets to be included in a clinical trial. Exploring the articulation of AD pathogenic mechanisms by oxidative stress will provide clues for better understanding the pathogenesis and progression of this dementing disorder and for the development of effective therapies to treat this disease.
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Affiliation(s)
- Rommy von Bernhardi
- Department of Neurology, Pontificia Universidad Católica de Chile, Santiago, Chile
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110
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Wang X, Petrie TG, Liu Y, Liu J, Fujioka H, Zhu X. Parkinson's disease-associated DJ-1 mutations impair mitochondrial dynamics and cause mitochondrial dysfunction. J Neurochem 2012; 121:830-9. [PMID: 22428580 DOI: 10.1111/j.1471-4159.2012.07734.x] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mitochondrial dysfunction represents a critical event during the pathogenesis of Parkinson's disease (PD) and expanding evidences demonstrate that an altered balance in mitochondrial fission/fusion is likely an important mechanism leading to mitochondrial and neuronal dysfunction/degeneration. In this study, we investigated whether DJ-1 is involved in the regulation of mitochondrial dynamics and function in neuronal cells. Confocal and electron microscopic analysis demonstrated that M17 human neuroblastoma cells over-expressing wild-type DJ-1 (WT DJ-1 cells) displayed elongated mitochondria while M17 cells over-expressing PD-associated DJ-1 mutants (R98Q, D149A and L166P) (mutant DJ-1 cells) showed significant increase of fragmented mitochondria. Similar mitochondrial fragmentation was also noted in primary hippocampal neurons over-expressing PD-associated mutant forms of DJ-1. Functional analysis revealed that over-expression of PD-associated DJ-1 mutants resulted in mitochondria dysfunction and increased neuronal vulnerability to oxidative stress (H(2) O(2)) or neurotoxin. Further immunoblot studies demonstrated that levels of dynamin-like protein (DLP1), also known as Drp1, a regulator of mitochondrial fission, was significantly decreased in WT DJ-1 cells but increased in mutant DJ-1 cells. Importantly, DLP1 knockdown in these mutant DJ-1 cells rescued the abnormal mitochondria morphology and all associated mitochondria/neuronal dysfunction. Taken together, these studies suggest that DJ-1 is involved in the regulation of mitochondrial dynamics through modulation of DLP1 expression and PD-associated DJ-1 mutations may cause PD by impairing mitochondrial dynamics and function.
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Affiliation(s)
- Xinglong Wang
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA.
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111
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Markham A, Cameron I, Bains R, Franklin P, Kiss JP, Schwendimann L, Gressens P, Spedding M. Brain-derived neurotrophic factor-mediated effects on mitochondrial respiratory coupling and neuroprotection share the same molecular signalling pathways. Eur J Neurosci 2012; 35:366-74. [DOI: 10.1111/j.1460-9568.2011.07965.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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112
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Alavian KN, Dworetzky SI, Bonanni L, Zhang P, Sacchetti S, Mariggio MA, Onofrj M, Thomas A, Li H, Mangold JE, Signore AP, Demarco U, Demady DR, Nabili P, Lazrove E, Smith PJS, Gribkoff VK, Jonas EA. Effects of dexpramipexole on brain mitochondrial conductances and cellular bioenergetic efficiency. Brain Res 2012; 1446:1-11. [PMID: 22364637 DOI: 10.1016/j.brainres.2012.01.046] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 01/18/2012] [Indexed: 02/01/2023]
Abstract
Cellular stress or injury can result in mitochondrial dysfunction, which has been linked to many chronic neurological disorders including amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). Stressed and dysfunctional mitochondria exhibit an increase in large conductance mitochondrial membrane currents and a decrease in bioenergetic efficiency. Inefficient energy production puts cells, and particularly neurons, at risk of death when energy demands exceed cellular energy production. Here we show that the candidate ALS drug dexpramipexole (DEX; KNS-760704; ((6R)-4,5,6,7-tetrahydro-N6-propyl-2,6-benzothiazole-diamine) and cyclosporine A (CSA) inhibited increases in ion conductance in whole rat brain-derived mitochondria induced by calcium or treatment with a proteasome inhibitor, although only CSA inhibited calcium-induced permeability transition in liver-derived mitochondria. In several cell lines, including cortical neurons in culture, DEX significantly decreased oxygen consumption while maintaining or increasing production of adenosine triphosphate (ATP). DEX also normalized the metabolic profile of injured cells and was protective against the cytotoxic effects of proteasome inhibition. These data indicate that DEX increases the efficiency of oxidative phosphorylation, possibly by inhibition of a CSA-sensitive mitochondrial conductance.
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Affiliation(s)
- Kambiz N Alavian
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
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113
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Increased Expression of the Anti-Apoptotic Protein Bcl-xL in the Brain is Associated with Resilience to Stress-Induced Depression-Like Behavior. Cell Mol Neurobiol 2012; 32:767-76. [DOI: 10.1007/s10571-011-9794-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 12/26/2011] [Indexed: 10/25/2022]
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114
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Cell signaling and mitochondrial dynamics: Implications for neuronal function and neurodegenerative disease. Neurobiol Dis 2012; 51:13-26. [PMID: 22297163 DOI: 10.1016/j.nbd.2012.01.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/09/2012] [Accepted: 01/12/2012] [Indexed: 11/22/2022] Open
Abstract
Nascent evidence indicates that mitochondrial fission, fusion, and transport are subject to intricate regulatory mechanisms that intersect with both well-characterized and emerging signaling pathways. While it is well established that mutations in components of the mitochondrial fission/fusion machinery can cause neurological disorders, relatively little is known about upstream regulators of mitochondrial dynamics and their role in neurodegeneration. Here, we review posttranslational regulation of mitochondrial fission/fusion enzymes, with particular emphasis on dynamin-related protein 1 (Drp1), as well as outer mitochondrial signaling complexes involving protein kinases and phosphatases. We also review recent evidence that mitochondrial dynamics has profound consequences for neuronal development and synaptic transmission and discuss implications for clinical translation.
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115
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PKA/AKAP1 and PP2A/Bβ2 regulate neuronal morphogenesis via Drp1 phosphorylation and mitochondrial bioenergetics. J Neurosci 2011; 31:15716-26. [PMID: 22049414 DOI: 10.1523/jneurosci.3159-11.2011] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial shape is determined by fission and fusion reactions, perturbation of which can contribute to neuronal injury and disease. Mitochondrial fission is catalyzed by dynamin-related protein 1 (Drp1), a large GTPase of the dynamin family that is highly expressed in neurons and regulated by various posttranslational modifications, including phosphorylation. We report here that reversible phosphorylation of Drp1 at a conserved Ser residue by an outer mitochondrial kinase (PKA/AKAP1) and phosphatase (PP2A/Bβ2) impacts dendrite and synapse development in cultured rat hippocampal neurons. PKA/AKAP1-mediated phosphorylation of Drp1 at Ser656 increased mitochondrial length and dendrite occupancy, enhancing dendritic outgrowth but paradoxically decreasing synapse number and density. Opposing PKA/AKAP1, PP2A/Bβ2-mediated dephosphorylation of Drp1 at Ser656 fragmented and depolarized mitochondria and depleted them from dendrites, stunting dendritic outgrowth but augmenting synapse formation. Raising and lowering intracellular calcium reproduced the effects of dephospho-Drp1 and phospho-Drp1on dendrite and synapse development, respectively, while boosting mitochondrial membrane potential with l-carnitine-fostered dendrite at the expense of synapse formation without altering mitochondrial size or distribution. Thus, outer mitochondrial PKA and PP2A regulate neuronal development by inhibiting and promoting mitochondrial division, respectively. We propose that the bioenergetic state of mitochondria, rather than their localization or shape per se, is the key effector of Drp1, altering calcium homeostasis to modulate neuronal morphology and connectivity.
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116
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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: 467] [Impact Index Per Article: 35.9] [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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117
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Chen YB, Aon MA, Hsu YT, Soane L, Teng X, McCaffery JM, Cheng WC, Qi B, Li H, Alavian KN, Dayhoff-Brannigan M, Zou S, Pineda FJ, O'Rourke B, Ko YH, Pedersen PL, Kaczmarek LK, Jonas EA, Hardwick JM. Bcl-xL regulates mitochondrial energetics by stabilizing the inner membrane potential. ACTA ACUST UNITED AC 2011; 195:263-76. [PMID: 21987637 PMCID: PMC3198165 DOI: 10.1083/jcb.201108059] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To promote cell survival, the antiapoptotic factor Bcl-xL both
inhibits Bax-induced mitochondrial outer membrane permeabilization and
stabilizes mitochondrial inner membrane ion flux and thus overall mitochondrial
energetic capacity. Mammalian Bcl-xL protein localizes to the outer mitochondrial
membrane, where it inhibits apoptosis by binding Bax and inhibiting Bax-induced
outer membrane permeabilization. Contrary to expectation, we found by electron
microscopy and biochemical approaches that endogenous Bcl-xL also
localized to inner mitochondrial cristae. Two-photon microscopy of cultured
neurons revealed large fluctuations in inner mitochondrial membrane potential
when Bcl-xL was genetically deleted or pharmacologically inhibited,
indicating increased total ion flux into and out of mitochondria. Computational,
biochemical, and genetic evidence indicated that Bcl-xL reduces
futile ion flux across the inner mitochondrial membrane to prevent a wasteful
drain on cellular resources, thereby preventing an energetic crisis during
stress. Given that F1FO–ATP synthase directly
affects mitochondrial membrane potential and having identified the mitochondrial
ATP synthase β subunit in a screen for Bcl-xL–binding
partners, we tested and found that Bcl-xL failed to protect β
subunit–deficient yeast. Thus, by bolstering mitochondrial energetic
capacity, Bcl-xL may contribute importantly to cell survival
independently of other Bcl-2 family proteins.
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Affiliation(s)
- Ying-Bei Chen
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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118
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Lu X, Zhang N, Dong S, Hu Y. Involvement of GPR12 in the induction of neurite outgrowth in PC12 cells. Brain Res Bull 2011; 87:30-6. [PMID: 21985983 DOI: 10.1016/j.brainresbull.2011.09.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 09/19/2011] [Accepted: 09/25/2011] [Indexed: 10/17/2022]
Abstract
GPR12, an orphan G protein-coupled receptor, constitutively activates the Gs signaling pathway and further increases intracellular cyclic AMP. GPR12 overexpression has been reported to promote neurite extension in neurons or transform neuro2a neuroblastoma cells into neuron-like cells. However, the possible effects and mechanisms of GPR12 in the differentiation of PC12 cells are still unknown. The present study shows that GPR12 overexpression induced PC12 cells differentiation into neuron-like cells with enlarged cell sizes and neuritogenesis possibly via activation of Erk1/2 signaling and significantly increased the expression of several neurite outgrowth-related genes, including Bcl-xL, Bcl-2 and synaptophysin. These findings indicate that GPR12 may play a role in neurite outgrowth during PC12 cell differentiation.
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Affiliation(s)
- Xiaoming Lu
- Advanced Institutes for Interdisciplinary Research, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
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119
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A molecular switch that governs mitochondrial fusion and fission mediated by the BCL2-like protein CED-9 of Caenorhabditis elegans. Proc Natl Acad Sci U S A 2011; 108:E813-22. [PMID: 21949250 DOI: 10.1073/pnas.1103218108] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Depending on the cellular context, BCL2-like proteins promote mitochondrial fusion or fission. What determines which of these two opposing processes they promote has so far been unknown. Furthermore, the mechanisms through which BCL2-like proteins affect mitochondrial dynamics remain to be fully understood. The BCL2-like protein CED-9 of Caenorhabditis elegans has previously been shown to promote mitochondrial fusion by physically interacting with the mitochondrial fusion protein FZO-1. Here, we report that CED-9 also physically interacts with the mitochondrial fission protein DRP-1 and that this interaction can be enhanced when CED-9 is associated with the BH3-only protein EGL-1. In addition, we show that the EGL-1-CED-9 complex promotes mitochondrial fission by recruiting DRP-1 to mitochondria and that the egl-1 gene is required for CED-9-dependent mitochondrial fission in vivo. Based on these results, we propose that EGL-1 converts CED-9 into a mitochondrial receptor for DRP-1, thereby shifting its activity from profusion to profission. We hypothesize that BCL2-like proteins act as mitochondrial receptors for DRP-1-like proteins in higher organisms as well and that BH3-only proteins play a general role as modifiers of the function in mitochondrial dynamics of BCL2-like proteins. We speculate that this function of BCL2-like proteins may be as couplers of mitochondrial fusion and fission.
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120
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Bcl-xL regulates metabolic efficiency of neurons through interaction with the mitochondrial F1FO ATP synthase. Nat Cell Biol 2011; 13:1224-33. [PMID: 21926988 PMCID: PMC3186867 DOI: 10.1038/ncb2330] [Citation(s) in RCA: 219] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 08/02/2011] [Indexed: 12/17/2022]
Abstract
Anti-apoptotic Bcl2 family proteins such as Bcl-xL protect cells from death by sequestering apoptotic molecules, but also contribute to normal neuronal function. We find in hippocampal neurons that Bcl-xL enhances the efficiency of energy metabolism. Our evidence suggests that Bcl-xL interacts directly with the beta subunit of the F1FO ATP synthase, decreasing an ion leak within the F1FO ATPase complex and thereby increasing net transport of H+ by F1FO during F1FO ATPase activity. By patch clamping submitochondrial vesicles enriched in F1FO ATP synthase complexes, we find that, in the presence of ATP, pharmacological or genetic inhibition of Bcl-xL increases the membrane leak conductance. In addition, recombinant Bcl-xL protein directly increases ATPase activity of purified synthase complexes, while inhibition of endogenous Bcl-xL decreases F1FO enzymatic activity. Our findings suggest that increased mitochondrial efficiency contributes to the enhanced synaptic efficacy found in Bcl-xL expressing neurons.
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121
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Hartman AL. Neuroprotection in metabolism-based therapy. Epilepsy Res 2011; 100:286-94. [PMID: 21872441 DOI: 10.1016/j.eplepsyres.2011.04.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Revised: 04/20/2011] [Accepted: 04/25/2011] [Indexed: 12/21/2022]
Abstract
Metabolism-based therapy has been used successfully in the treatment of seizures but study of its use in other neurodegenerative disorders is growing. Data demonstrating the use of different forms of metabolism-based therapy in human trials of Alzheimer disease and Parkinson disease are discussed. Animal and in vitro studies have shed light on metabolism-based therapy's mechanisms in these diseases, as well as ALS, aging, ischemia, trauma and mitochondrial cytopathies. Additional insights may be obtained by considering the role of metabolism-based therapy in cell disability and death (specifically apoptosis, excitotoxicity, and autophagy).
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Affiliation(s)
- Adam L Hartman
- Johns Hopkins University, Neurology, 600 N. Wolfe St., Meyer 2-147, Baltimore, MD 21287, USA.
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122
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Shishkina GT, Kalinina TS, Berezova IV, Dygalo NN. Stress-induced activation of the brainstem Bcl-xL gene expression in rats treated with fluoxetine: correlations with serotonin metabolism and depressive-like behavior. Neuropharmacology 2011; 62:177-83. [PMID: 21740920 DOI: 10.1016/j.neuropharm.2011.06.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/16/2011] [Accepted: 06/17/2011] [Indexed: 11/27/2022]
Abstract
Mechanisms underlying stress-induced depression and antidepressant drug action were shown to involve alterations in serotonergic (5-HT) neurotransmission and expression of genes coding for proteins associated with neurotrophic signaling pathways and cell-survival in the hippocampus and cortex. Expression of these genes in the brainstem containing 5-HT neurons may also be related to vulnerability or resilience to stress-related psychopathology. Here we investigated 5-HT markers and expression of genes for Brain-Derived Neurotrophic Factor (BDNF) and apoptotic proteins in the brainstem in relation to swim stress-induced behavioral despair. We found that anti-apoptotic Bcl-xL gene is sensitive to stress during the course of fluoxetine administration. Responsiveness of this gene to stress appeared concomitantly with an antidepressant-like effect of fluoxetine in the forced swim test. Bcl-xL transcript levels showed negative correlations with duration of immobility in the test and 5-HT turnover in the brainstem. In contrast, BDNF and pro-apoptotic protein Bax mRNA levels were unchanged by either fluoxetine or stress, suggesting specificity of Bcl-xL gene responses to these treatments. We also found that the levels of mRNAs for tryptophan hydroxylase-2 (TPH2) and 5-HT transporter (5-HTT) were significantly down-regulated following prolonged treatment with fluoxetine, but were not affected by stress. Unlike TPH2 and 5-HTT, 5-HT1A receptor mRNA levels were not altered by fluoxetine but significantly increased in response to swim stress. These data show that long-term fluoxetine treatment leads to changes in 5-HT and Bcl-xL responses to stress associated with antidepressant-like effects of the drug. This article is part of a Special Issue entitled 'Anxiety and Depression'.
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Affiliation(s)
- Galina T Shishkina
- Functional Neurogenomics Laboratory, Institute of Cytology and Genetics, Novosibirsk 630090, Russia
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123
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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: 214] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [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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124
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Redox modulation by S-nitrosylation contributes to protein misfolding, mitochondrial dynamics, and neuronal synaptic damage in neurodegenerative diseases. Cell Death Differ 2011; 18:1478-86. [PMID: 21597461 DOI: 10.1038/cdd.2011.65] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The pathological processes of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases engender synaptic and neuronal cell damage. While mild oxidative and nitrosative (nitric oxide (NO)-related) stress mediates normal neuronal signaling, excessive accumulation of these free radicals is linked to neuronal cell injury or death. In neurons, N-methyl-D-aspartate (NMDA) receptor (NMDAR) activation and subsequent Ca(2+) influx can induce the generation of NO via neuronal NO synthase. Emerging evidence has demonstrated that S-nitrosylation, representing covalent reaction of an NO group with a critical protein thiol, mediates the vast majority of NO signaling. Analogous to phosphorylation and other posttranslational modifications, S-nitrosylation can regulate the biological activity of many proteins. Here, we discuss recent studies that implicate neuropathogenic roles of S-nitrosylation in protein misfolding, mitochondrial dysfunction, synaptic injury, and eventual neuronal loss. Among a growing number of S-nitrosylated proteins that contribute to disease pathogenesis, in this review we focus on S-nitrosylated protein-disulfide isomerase (forming SNO-PDI) and dynamin-related protein 1 (forming SNO-Drp1). Furthermore, we describe drugs, such as memantine and newer derivatives of this compound that can prevent both hyperactivation of extrasynaptic NMDARs as well as downstream pathways that lead to nitrosative stress, synaptic damage, and neuronal loss.
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125
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Abstract
Mitochondrial dynamics and mitophagy are recognized as two critical processes underlying mitochondrial homeostasis. Morphological and bioenergetic characterization of the life cycle of an individual mitochondrion reveals several points where fusion, fission, and mitophagy interact. Mitochondrial fission can produce an impaired daughter unit that will be targeted by the autophagic machinery. Mitochondrial fusion, on the other hand, may serve to dilute impaired respiratory components and thereby prevent their removal. The inverse dependency of fusion and mitophagy on membrane potential allows them to act as complementary rather than competitive fates of the daughter mitochondrion after a fission event. We discuss the interplay between mitochondrial dynamics and mitophagy in different tissues and in different disease models under both stress-induced and steady-state conditions.
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Affiliation(s)
- Gilad Twig
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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126
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Nakamura T, Lipton SA. S-nitrosylation of critical protein thiols mediates protein misfolding and mitochondrial dysfunction in neurodegenerative diseases. Antioxid Redox Signal 2011; 14:1479-92. [PMID: 20812868 PMCID: PMC3061195 DOI: 10.1089/ars.2010.3570] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Excessive nitrosative and oxidative stress is thought to trigger cellular signaling pathways leading to neurodegenerative conditions. Such redox dysregulation can result from many cellular events, including hyperactivation of the N-methyl-D-aspartate-type glutamate receptor, mitochondrial dysfunction, and cellular aging. Recently, we and our colleagues have shown that excessive generation of free radicals and related molecules, in particular nitric oxide species (NO), can trigger pathological production of misfolded proteins, abnormal mitochondrial dynamics (comprised of mitochondrial fission and fusion events), and apoptotic pathways in neuronal cells. Emerging evidence suggests that excessive NO production can contribute to these pathological processes, specifically by S-nitrosylation of specific target proteins. Here, we highlight examples of S-nitrosylated proteins that regulate misfolded protein accumulation and mitochondrial dynamics. For instance, in models of Parkinson's disease, these S-nitrosylation targets include parkin, a ubiquitin E3 ligase and neuroprotective molecule, and protein-disulfide isomerase, a chaperone enzyme for nascent protein folding. S-Nitrosylation of protein-disulfide isomerase may also be associated with mutant Cu/Zn superoxide dismutase toxicity in amyotrophic lateral sclerosis. Additionally, in models of Alzheimer's disease, excessive NO generation leads to the formation of S-nitrosylated dynamin-related protein 1 (forming SNO-Drp1), which contributes to abnormal mitochondrial fragmentation and resultant synaptic damage.
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Affiliation(s)
- Tomohiro Nakamura
- Del E. Webb Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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127
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Redox regulation of mitochondrial fission, protein misfolding, synaptic damage, and neuronal cell death: potential implications for Alzheimer's and Parkinson's diseases. Apoptosis 2011; 15:1354-63. [PMID: 20177970 PMCID: PMC2978885 DOI: 10.1007/s10495-010-0476-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Normal mitochondrial dynamics consist of fission and fusion events giving rise to new mitochondria, a process termed mitochondrial biogenesis. However, several neurodegenerative disorders manifest aberrant mitochondrial dynamics, resulting in morphological abnormalities often associated with deficits in mitochondrial mobility and cell bioenergetics. Rarely, dysfunctional mitochondrial occur in a familial pattern due to genetic mutations, but much more commonly patients manifest sporadic forms of mitochondrial disability presumably related to a complex set of interactions of multiple genes (or their products) with environmental factors (G × E). Recent studies have shown that generation of excessive nitric oxide (NO), in part due to generation of oligomers of amyloid-β (Aβ) protein or overactivity of the NMDA-subtype of glutamate receptor, can augment mitochondrial fission, leading to frank fragmentation of the mitochondria. S-Nitrosylation, a covalent redox reaction of NO with specific protein thiol groups, represents one mechanism contributing to NO-induced mitochondrial fragmentation, bioenergetic failure, synaptic damage, and eventually neuronal apoptosis. Here, we summarize our evidence in Alzheimer’s disease (AD) patients and animal models showing that NO contributes to mitochondrial fragmentation via S-nitrosylation of dynamin-related protein 1 (Drp1), a protein involved in mitochondrial fission. These findings may provide a new target for drug development in AD. Additionally, we review emerging evidence that redox reactions triggered by excessive levels of NO can contribute to protein misfolding, the hallmark of a number of neurodegenerative disorders, including AD and Parkinson’s disease. For example, S-nitrosylation of parkin disrupts its E3 ubiquitin ligase activity, and thereby affects Lewy body formation and neuronal cell death.
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128
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Calfa G, Percy AK, Pozzo-Miller L. Experimental models of Rett syndrome based on Mecp2 dysfunction. Exp Biol Med (Maywood) 2011; 236:3-19. [PMID: 21239731 DOI: 10.1258/ebm.2010.010261] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder predominantly occurring in females with an incidence of 1:10,000 births and caused by sporadic mutations in the MECP2 gene, which encodes methyl-CpG-binding protein-2, an epigenetic transcription factor that binds methylated DNA. The clinical hallmarks include a period of apparently normal early development followed by a plateau and then subsequent frank regression. Impaired visual and aural contact often lead to an initial diagnosis of autism. The characterization of experimental models based on the loss-of-function of the mouse Mecp2 gene revealed that subtle changes in the morphology and function of brain cells and synapses have profound consequences on network activities that underlie critical brain functions. Furthermore, these experimental models have been used for successful reversals of RTT-like symptoms by genetic, pharmacological and environmental manipulations, raising hope for novel therapeutic strategies to improve the quality of life of RTT individuals.
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Affiliation(s)
- Gaston Calfa
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
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129
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Abstract
Mitochondria are at the center of cellular energy metabolism and regulate cell life and death. The cell biological aspect of mitochondria, especially mitochondrial dynamics, has drawn much attention through implications in human pathology, including neurological disorders and metabolic diseases. Mitochondrial fission and fusion are the main processes governing the morphological plasticity and are controlled by multiple factors, including mechanochemical enzymes and accessory proteins. Emerging evidence suggests that mitochondrial dynamics plays an important role in metabolism-secretion coupling in pancreatic β-cells as well as complications of diabetes. This review describes an overview of mechanistic and functional aspects of mitochondrial fission and fusion, and comments on the recent advances connecting mitochondrial dynamics with diabetes and diabetic complications.
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Affiliation(s)
- Yisang Yoon
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
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130
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Xie R, Nguyen S, McKeehan K, Wang F, McKeehan WL, Liu L. Microtubule-associated protein 1S (MAP1S) bridges autophagic components with microtubules and mitochondria to affect autophagosomal biogenesis and degradation. J Biol Chem 2011; 286:10367-77. [PMID: 21262964 DOI: 10.1074/jbc.m110.206532] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ubiquitously distributed MAP1S is a homologue of the exclusively neuronal distributed microtubule-associated protein 1A and 1B (MAP1A/B). They give rise to multiple isoforms through similar post-translational modification. Isoforms of MAP1S have been implicated in microtubule dynamics and mitotic abnormalities and mitotic cell death. Here we show that ablation of the Map1s gene in mice caused reduction in the B-cell CLL/lymphoma 2 or xL (Bcl-2/xL) and cyclin-dependent kinase inhibitor 1B (P27) protein levels, accumulation of defective mitochondria, and severe defects in response to nutritive stress, suggesting defects in autophagosomal biogenesis and clearance. Furthermore, MAP1S isoforms interacted with the autophagosome-associated light chain 3 of MAP1A/B (LC3), a homologue of yeast autophagy-related gene 8 (ATG8), and recruited it to stable microtubules in a MAP1S and LC3 isoform-dependent mode. In addition, MAP1S interacted with mitochondrion-associated leucine-rich PPR-motif containing protein (LRPPRC) that interacts with the mitophagy initiator and Parkinson disease-related protein Parkin. The three-way interactions of MAP1S isoforms with LC3 and microtubules as well as the interaction of MAP1S with LRPPRC suggest that MAP1S isoforms may play positive roles in integration of autophagic components with microtubules and mitochondria in both autophagosomal biogenesis and degradation. For the first time, our results clarify roles of MAP1S in bridging microtubules and mitochondria with autophagic and mitophagic initiation, maturation, trafficking, and lysosomal clearance. Defects in the MAP1S-regulated autophagy may impact heart disease, cancers, neurodegenerative diseases, and a wide range of other diseases.
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Affiliation(s)
- Rui Xie
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, USA
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131
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Ofengeim D, Miyawaki T, Suzanne zukin R. Molecular and Cellular Mechanisms of Ischemia-Induced Neuronal Death. Stroke 2011. [DOI: 10.1016/b978-1-4160-5478-8.10006-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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132
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Modulation of the generation of dopaminergic neurons from human neural stem cells by Bcl-X(L): mechanisms of action. VITAMINS AND HORMONES 2011; 87:175-205. [PMID: 22127243 DOI: 10.1016/b978-0-12-386015-6.00029-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Understanding the developmental mechanisms governing dopaminergic neuron generation and maintenance is crucial for the development of neuronal replacement therapeutic procedures, like in Parkinson's disease (PD), but also for research aimed at drug screening and pharmacology. In the present chapter, we review the present situation using stem cells of different origins (pluripotent and multipotent) and summarize current manipulations of stem cells for the enhancement of dopaminergic neuron generation, focusing on the actions of Bcl-X(L). Bcl-X(L) not only enhances dopaminergic neuron survival but also augments the expression of key developmental and maintenance genes, and, through the lengthening of the cell cycle early during differentiation, regulates cell fate decisions, producing a net enhancement of neurogenesis. The relevance of these findings is discussed in the context of basic neurogenesis and also for the development of efficient cell therapy in PD.
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133
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Vento MT, Zazzu V, Loffreda A, Cross JR, Downward J, Stoppelli MP, Iaccarino I. Praf2 is a novel Bcl-xL/Bcl-2 interacting protein with the ability to modulate survival of cancer cells. PLoS One 2010; 5:e15636. [PMID: 21203533 PMCID: PMC3006391 DOI: 10.1371/journal.pone.0015636] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 11/18/2010] [Indexed: 11/18/2022] Open
Abstract
Increased expression of Bcl-xL in cancer has been shown to confer resistance to a broad range of apoptotic stimuli and to modulate a number of other aspects of cellular physiology, including energy metabolism, cell cycle, autophagy, mitochondrial fission/fusion and cellular adhesion. However, only few of these activities have a mechanistic explanation. Here we used Tandem Affinity purification to identify novel Bcl-xL interacting proteins that could explain the pleiotropic effects of Bcl-xL overexpression. Among the several proteins co-purifying with Bcl-xL, we focused on Praf2, a protein with a predicted role in trafficking. The interaction of Praf2 with Bcl-xL was found to be dependent on the transmembrane domain of Bcl-xL. We found that Bcl-2 also interacts with Praf2 and that Bcl-xL and Bcl-2 can interact also with Arl6IP5, an homologue of Praf2. Interestingly, overexpression of Praf2 results in the translocation of Bax to mitochondria and the induction of apoptotic cell death. Praf2 dependent cell death is prevented by the co-transfection of Bcl-xL but not by its transmembrane domain deleted mutant. Accordingly, knock-down of Praf2 increases clonogenicity of U2OS cells following etoposide treatment by reducing cell death. In conclusion a screen for Bcl-xL-interacting membrane proteins let us identify a novel proapoptotic protein whose activity is strongly counteracted exclusively by membrane targeted Bcl-xL.
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Affiliation(s)
- Maria Teresa Vento
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso,” Consiglio Nazionale delle Ricerche (CNR), Naples, Italy
| | - Valeria Zazzu
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso,” Consiglio Nazionale delle Ricerche (CNR), Naples, Italy
| | - Alessia Loffreda
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso,” Consiglio Nazionale delle Ricerche (CNR), Naples, Italy
| | - Justin R. Cross
- Signal Transduction Laboratory, Cancer Research UK, London Research Institute, London, United Kingdom
| | - Julian Downward
- Signal Transduction Laboratory, Cancer Research UK, London Research Institute, London, United Kingdom
| | - Maria Patrizia Stoppelli
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso,” Consiglio Nazionale delle Ricerche (CNR), Naples, Italy
| | - Ingram Iaccarino
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso,” Consiglio Nazionale delle Ricerche (CNR), Naples, Italy
- * E-mail:
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134
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Mitochondrial fission/fusion dynamics and apoptosis. Mitochondrion 2010; 10:640-8. [DOI: 10.1016/j.mito.2010.08.005] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 08/04/2010] [Accepted: 08/04/2010] [Indexed: 11/18/2022]
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135
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Abdelwahid E, Rolland S, Teng X, Conradt B, Hardwick JM, White K. Mitochondrial involvement in cell death of non-mammalian eukaryotes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:597-607. [PMID: 20950655 DOI: 10.1016/j.bbamcr.2010.10.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 09/29/2010] [Accepted: 10/04/2010] [Indexed: 12/28/2022]
Abstract
Although mitochondria are essential organelles for long-term survival of eukaryotic cells, recent discoveries in biochemistry and genetics have advanced our understanding of the requirements for mitochondria in cell death. Much of what we understand about cell death is based on the identification of conserved cell death genes in Drosophila melanogaster and Caenorhabditis elegans. However, the role of mitochondria in cell death in these models has been much less clear. Considering the active role that mitochondria play in apoptosis in mammalian cells, the mitochondrial contribution to cell death in non-mammalian systems has been an area of active investigation. In this article, we review the current research on this topic in three non-mammalian models, C. elegans, Drosophila, and Saccharomyces cerevisiae. In addition, we discuss how non-mammalian models have provided important insight into the mechanisms of human disease as they relate to the mitochondrial pathway of cell death. The unique perspective derived from each of these model systems provides a more complete understanding of mitochondria in programmed cell death. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
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Affiliation(s)
- Eltyeb Abdelwahid
- Cutaneous Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
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136
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Lackner LL, Nunnari J. Small molecule inhibitors of mitochondrial division: tools that translate basic biological research into medicine. ACTA ACUST UNITED AC 2010; 17:578-83. [PMID: 20609407 DOI: 10.1016/j.chembiol.2010.05.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 05/07/2010] [Accepted: 05/28/2010] [Indexed: 12/01/2022]
Abstract
Mitochondria do not exist as discrete static entities; rather, mitochondria form a network that continuously moves, divides, and fuses. The structure of this dynamic network is in part maintained by a balance of division and fusion events (Hoppins et al., 2007). The ratio of division to fusion events that defines a proper balance is not universal but varies with developmental stage, cell type, and biological circumstances. This is evident throughout the cell cycle in higher eukaryotes, where mitochondria elongate during the G1/S transition and fragment at the onset of mitosis, and when mitochondria fragment in response to certain cellular stimuli, such as increases in cytosolic calcium levels (Breckenridge et al., 2003; Cereghetti et al., 2008; Han et al., 2008; Mitra et al., 2009; Taguchi et al., 2007). The functional state and distribution of mitochondria are clearly influenced by its steady-state structure. When the normal balance of division and fusion is disrupted as a consequence of the inappropriate stimulation or inhibition of either process, problems arise at the cellular level that compromises the well-being of the organism as a whole. This is evident by the ever-increasing number of diseases in which abnormal mitochondrial dynamics have been etiologically implicated. In this context, the mitochondrial division and fusion machines are valuable and interesting targets of small molecule effectors, as inhibition or activation of these processes may be able to restore the proper dynamic balance and function. A small molecule inhibitor of mitochondrial division, mdivi-1, has already been identified and characterized (Cassidy-Stone et al., 2008). This inhibitor has provided valuable insight into the mechanism of mitochondrial division and has shown great therapeutic promise in a wide array of disease models. This review will focus on small molecule effectors of mitochondrial division, discussing their value in basic biological research as well as their therapeutic potential.
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Affiliation(s)
- Laura L Lackner
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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137
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Baratchi S, Kanwar RK, Kanwar JR. Survivin: A target from brain cancer to neurodegenerative disease. Crit Rev Biochem Mol Biol 2010; 45:535-54. [DOI: 10.3109/10409238.2010.516740] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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138
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Cho DH, Nakamura T, Lipton SA. Mitochondrial dynamics in cell death and neurodegeneration. Cell Mol Life Sci 2010; 67:3435-47. [PMID: 20577776 PMCID: PMC11115814 DOI: 10.1007/s00018-010-0435-2] [Citation(s) in RCA: 222] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 06/06/2010] [Accepted: 06/08/2010] [Indexed: 12/22/2022]
Abstract
Mitochondria are highly dynamic organelles that continuously undergo two opposite processes, fission and fusion. Mitochondrial dynamics influence not only mitochondrial morphology, but also mitochondrial biogenesis, mitochondrial distribution within the cell, cell bioenergetics, and cell injury or death. Drp1 mediates mitochondrial fission, whereas Mfn1/2 and Opa1 control mitochondrial fusion. Neurons require large amounts of energy to carry out their highly specialized functions. Thus, mitochondrial dysfunction is a prominent feature in a variety of neurodegenerative diseases. Mutations of Mfn2 and Opa1 lead to neuropathies such as Charcot-Marie-Tooth disease type 2A and autosomal dominant optic atrophy. Moreover, both Aβ peptide and mutant huntingtin protein induce mitochondrial fragmentation and neuronal cell death. In addition, mutants of Parkinson's disease-related genes also show abnormal mitochondrial morphology. This review highlights our current understanding of abnormal mitochondrial dynamics relevant to neuronal synaptic loss and cell death in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and Huntington's disease.
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Affiliation(s)
- Dong-Hyung Cho
- Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037 USA
- Institute for Innovative Cancer Research, Asan Medical Center, University of Ulsan College of Medicine, Pungpap-dong, Songpa-gu, Seoul, 138-736 Korea
- Graduate School of East-West Medical Science, Kyung Hee University, Yongin, Gyeonggi 446-701 Korea
| | - Tomohiro Nakamura
- Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037 USA
| | - Stuart A. Lipton
- Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037 USA
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139
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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: 177] [Impact Index Per Article: 12.6] [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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140
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Smith PJS, Collis LP, Messerli MA. Windows to cell function and dysfunction: signatures written in the boundary layers. Bioessays 2010; 32:514-23. [PMID: 20486138 DOI: 10.1002/bies.200900173] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand.
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Affiliation(s)
- Peter J S Smith
- BioCurrents Research Center, Cellular Dynamics Program, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
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141
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Rolland SG, Conradt B. New role of the BCL2 family of proteins in the regulation of mitochondrial dynamics. Curr Opin Cell Biol 2010; 22:852-8. [PMID: 20729050 DOI: 10.1016/j.ceb.2010.07.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 07/26/2010] [Indexed: 11/27/2022]
Abstract
Mitochondria are highly dynamic organelles that constantly fuse and divide. Dynamin-related GTPases are the core components of the machineries that mediate mitochondrial fusion and fission. The role and regulation of these machineries are currently under intense investigation. Recently, members of the BCL2 family of proteins, conserved regulators of apoptosis, have been implicated in the regulation of mitochondrial dynamics. Here, we review the functions of mitochondrial fusion and fission in apoptotic and nonapoptotic cells and how members of the BCL2 family of proteins regulate these functions.
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Affiliation(s)
- Stephane G Rolland
- Dartmouth Medical School, Department of Genetics, Norris Cotton Cancer Center, 7400 Remsen, Hanover, NH 03755, USA
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142
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Bcl-2 family interaction with the mitochondrial morphogenesis machinery. Cell Death Differ 2010; 18:235-47. [PMID: 20671748 DOI: 10.1038/cdd.2010.89] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The regulation of both mitochondrial dynamics and apoptosis is key for maintaining the health of a cell. Bcl-2 family proteins, central in apoptosis regulation, also have roles in the maintenance of the mitochondrial network. Here we report that Bax and Bak participate in the regulation of mitochondrial fusion in mouse embryonic fibroblasts, primary mouse neurons and human colon carcinoma cells. To assess how Bcl-2 family members may regulate mitochondrial morphogenesis, we determined the binding of a series of chimeras between Bcl-xL and Bax to the mitofusins, mitofusin 1 (Mfn1) and mitofusin 2 (Mfn2). One chimera (containing helix 5 (H5) of Bax replacing H5 of Bcl-xL (Bcl-xL/Bax H5)) co-immunoprecipitated with Mfn1 and Mfn2 significantly better than either wild-type Bax or Bcl-xL. Expression of Bcl-xL/Bax H5 in cells reduced the mobility of Mfn1 and Mfn2 and colocalized with ectopic Mfn1 and Mfn2, as well as endogenous Mfn2 to a greater extent than wild-type Bax. Ultimately, Bcl-xL/Bax H5 induced substantial mitochondrial fragmentation in healthy cells. Therefore, we propose that Bcl-xL/Bax H5 disturbs mitochondrial morphology by binding and inhibiting Mfn1 and Mfn2 activity, supporting the hypothesis that Bcl-2 family members have the capacity to regulate mitochondrial morphology through binding to the mitofusins in healthy cells.
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143
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MacAskill AF, Atkin TA, Kittler JT. Mitochondrial trafficking and the provision of energy and calcium buffering at excitatory synapses. Eur J Neurosci 2010; 32:231-40. [PMID: 20946113 DOI: 10.1111/j.1460-9568.2010.07345.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Neuronal postsynaptic currents consume most of the brain's energy supply. Delineating how neurons control the distribution, morphology and function of the energy-producing mitochondria that fuel synaptic communication is therefore important for our understanding of nervous system function and pathology. Here we review recent insights into the molecular mechanisms that control activity-dependent regulation of mitochondrial trafficking, morphology and activity at excitatory synapses. We also consider some implications of this regulation for synaptic function and plasticity and discuss how this may contribute to synaptic dysfunction and signalling in neurological disease, with a focus on Alzheimer's disease.
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Affiliation(s)
- Andrew F MacAskill
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
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144
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Li Z, Jo J, Jia JM, Lo SC, Whitcomb DJ, Jiao S, Cho K, Sheng M. Caspase-3 activation via mitochondria is required for long-term depression and AMPA receptor internalization. Cell 2010; 141:859-71. [PMID: 20510932 DOI: 10.1016/j.cell.2010.03.053] [Citation(s) in RCA: 415] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/28/2009] [Accepted: 03/22/2010] [Indexed: 01/05/2023]
Abstract
NMDA receptor-dependent synaptic modifications, such as long-term potentiation (LTP) and long-term depression (LTD), are essential for brain development and function. LTD occurs mainly by the removal of AMPA receptors from the postsynaptic membrane, but the underlying molecular mechanisms remain unclear. Here, we show that activation of caspase-3 via mitochondria is required for LTD and AMPA receptor internalization in hippocampal neurons. LTD and AMPA receptor internalization are blocked by peptide inhibitors of caspase-3 and -9. In hippocampal slices from caspase-3 knockout mice, LTD is abolished whereas LTP remains normal. LTD is also prevented by overexpression of the anti-apoptotic proteins XIAP or Bcl-xL, and by a mutant Akt1 protein that is resistant to caspase-3 proteolysis. NMDA receptor stimulation that induces LTD transiently activates caspase-3 in dendrites, without causing cell death. These data indicate an unexpected causal link between the molecular mechanisms of apoptosis and LTD.
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Affiliation(s)
- Zheng Li
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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145
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Nosyreva E, Kavalali ET. Activity-dependent augmentation of spontaneous neurotransmission during endoplasmic reticulum stress. J Neurosci 2010; 30:7358-68. [PMID: 20505103 PMCID: PMC2892630 DOI: 10.1523/jneurosci.5358-09.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 04/05/2010] [Accepted: 04/10/2010] [Indexed: 01/13/2023] Open
Abstract
The endoplasmic reticulum (ER) is an essential cellular compartment responsible for Ca(2+) sequestration, signaling, protein translation, folding as well as transport. Several acute and chronic disease conditions impair ER function leading to ER stress. To study the impact of ER stress on synaptic transmission we applied tunicamycin (TM) or thapsigargin (TG) to hippocampal neurons, which triggered sustained elevation of key ER stress markers. We monitored evoked and spontaneous neurotransmission during 4 d of TM or TG treatment and detected only a 20% increase in paired pulse depression suggesting an increase in neurotransmitter release probability. However, the treatments did not significantly affect the number of active synapses or the size of the total recycling vesicle pool as measured by uptake and release of styryl dye FM1-43. In contrast, under the same conditions, we observed a dramatic fourfold increase in spontaneous excitatory transmission, which could be reversed by chronic treatment with the NMDA receptor blocker AP-5 or by treatment with salubrinal, a selective inhibitor of eukaryotic translation initiation factor 2 (eIF2alpha) dephosphorylation. Furthermore, ER stress caused NMDA receptor-dependent suppression of eukaryotic elongation factor-2 (eEF2) phosphorylation thus reversing downstream signaling mediated by spontaneous release. Together, these findings suggest that chronic ER stress augments spontaneous excitatory neurotransmission and reverses its downstream signaling in a NMDA receptor-dependent manner, which may contribute to neuronal circuitry abnormalities that precede synapse degeneration in several neurological disorders.
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Affiliation(s)
| | - Ege T. Kavalali
- Departments of Neuroscience and
- Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9111
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146
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Shishkina GT, Kalinina TS, Berezova IV, Bulygina VV, Dygalo NN. Resistance to the development of stress-induced behavioral despair in the forced swim test associated with elevated hippocampal Bcl-xl expression. Behav Brain Res 2010; 213:218-24. [PMID: 20457187 DOI: 10.1016/j.bbr.2010.05.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/30/2010] [Accepted: 05/01/2010] [Indexed: 01/27/2023]
Abstract
Stress may predispose individuals toward depression through down-regulation of neurogenesis and increase in apoptosis in the brain. However, many subjects show high resistance to stress in relation to psychopathology. In the present study, we assessed the possibility that individual-specific patterns of gene expression associated with cell survival and proliferation may be among the molecular factors underlying stress resilience. Brain-derived neurotrophic factor (BDNF), anti-apoptotic B cell lymphoma like X (Bcl-xl) and pro-apoptotic bcl2-associated X protein (Bax) expression were determined in the hippocampus and frontal cortex of rats naturally differed in despair-like behavior in the forced swim test. In the hippocampus, BDNF messenger RNA (mRNA) level was significantly down-regulated 2h after the forced swim test exposure, and at this time point, Bcl-xl mRNA and protein levels were significantly higher in stressed than in untested animals. The ratios of hippocampal Bcl-xl to Bax mRNA negatively correlated with the total time spent immobile in the test. When animals were divided in two groups according to immobility responses in two consecutive swim sessions and designated as stress resilient if their immobility time did not increase in the second session as it did in stress sensitive rats, it was found that resilient rats had significantly higher Bcl-xl/Bax ratios in the hippocampus than stress sensitive animals. The data suggest that naturally occurring variations in the Bcl-xl/Bax ratio in the hippocampus may contribute to individual differences in vulnerability to stress-induced depression-like behaviors.
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Affiliation(s)
- Galina T Shishkina
- Functional Neurogenomics Laboratory, Institute of Cytology and Genetics, Lavrentjev Av. 10, Novosibirsk, Russia
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147
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Nakamura T, Cieplak P, Cho DH, Godzik A, Lipton SA. S-nitrosylation of Drp1 links excessive mitochondrial fission to neuronal injury in neurodegeneration. Mitochondrion 2010; 10:573-8. [PMID: 20447471 DOI: 10.1016/j.mito.2010.04.007] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2010] [Indexed: 02/04/2023]
Abstract
Neurons are known to use large amounts of energy for their normal function and activity. In order to meet this demand, mitochondrial fission, fusion, and movement events (mitochondrial dynamics) control mitochondrial morphology, facilitating biogenesis and proper distribution of mitochondria within neurons. In contrast, dysfunction in mitochondrial dynamics results in reduced cell bioenergetics and thus contributes to neuronal injury and death in many neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease, and Huntington's disease. We recently reported that amyloid-beta peptide, thought to be a key mediator of AD pathogenesis, engenders S-nitrosylation and thus hyperactivation of the mitochondrial fission protein Drp1. This activation leads to excessive mitochondrial fragmentation, bioenergetic compromise, and synaptic damage in models of AD. Here, we provide an extended commentary on our findings of nitric oxide-mediated abnormal mitochondrial dynamics.
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Affiliation(s)
- Tomohiro Nakamura
- Del E. Webb Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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148
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Autret A, Martin SJ. Bcl-2 family proteins and mitochondrial fission/fusion dynamics. Cell Mol Life Sci 2010; 67:1599-606. [PMID: 20143248 PMCID: PMC11115729 DOI: 10.1007/s00018-010-0286-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 01/20/2010] [Indexed: 01/07/2023]
Abstract
Mitochondria are dynamic organelles and can undergo regulated fission/fragmentation to produce smaller organelles or, alternatively, can undergo fusion to produce tubular or net-like mitochondrial structures. Although some of the molecules that control mitochondrial fission and fusion are known, new molecules and pathways that control this process continue to be discovered, suggesting that this process is more complex than previously appreciated. In addition to their crucial role in the regulation of apoptosis, recent studies have implicated members of the Bcl-2 family in maintenance of the mitochondrial network. Here, we discuss the mechanisms governing mitochondrial fission/fusion and summarize current knowledge concerning the role of Bcl-2 family members in regulating mitochondrial fission/fusion dynamics.
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Affiliation(s)
- Arnaud Autret
- Molecular Cell Biology Laboratory, Department of Genetics, The Smurfit Institute, Trinity College, Dublin 2, Ireland
| | - Seamus J. Martin
- Molecular Cell Biology Laboratory, Department of Genetics, The Smurfit Institute, Trinity College, Dublin 2, Ireland
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149
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Gu Z, Nakamura T, Lipton SA. Redox reactions induced by nitrosative stress mediate protein misfolding and mitochondrial dysfunction in neurodegenerative diseases. Mol Neurobiol 2010; 41:55-72. [PMID: 20333559 DOI: 10.1007/s12035-010-8113-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 02/19/2010] [Indexed: 12/20/2022]
Abstract
Overstimulation of N-methyl-D-aspartate (NMDA)-type glutamate receptors accounts, at least in part, for excitotoxic neuronal damage, potentially contributing to a wide range of acute and chronic neurologic diseases. Neurodegenerative disorders including Alzheimer's disease (AD) and Parkinson's disease (PD), manifest deposits of misfolded or aggregated proteins, and result from synaptic injury and neuronal death. Recent studies have suggested that nitrosative stress due to generation of excessive nitric oxide (NO) can mediate excitotoxicity in part by triggering protein misfolding and aggregation, and mitochondrial fragmentation in the absence of genetic predisposition. S-Nitrosylation, or covalent reaction of NO with specific protein thiol groups, represents a convergent signal pathway contributing to NO-induced protein misfolding and aggregation, compromised dynamics of mitochondrial fission-fusion process, thus leading to neurotoxicity. Here, we review the effect of S-nitrosylation on protein function under excitotoxic conditions, and present evidence suggesting that NO contributes to protein misfolding and aggregation via S-nitrosylating protein-disulfide isomerase or the E3 ubiquitin ligase parkin, and mitochondrial fragmentation through beta-amyloid-related S-nitrosylation of dynamin-related protein-1. Moreover, we also discuss that inhibition of excessive NMDA receptor activity by memantine, an uncompetitive/fast off-rate (UFO) drug can ameliorate excessive production of NO, protein misfolding and aggregation, mitochondrial fragmentation, and neurodegeneration.
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Affiliation(s)
- Zezong Gu
- Department of Pathology and Anatomical Sciences, University of Missouri-Columbia School of Medicine, One Hospital Drive, Columbia, MO 65212, USA.
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150
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Young KW, Piñón LGP, Dhiraj D, Twiddy D, Macfarlane M, Hickman J, Nicotera P. Mitochondrial fragmentation and neuronal cell death in response to the Bcl-2/Bcl-x(L)/Bcl-w antagonist ABT-737. Neuropharmacology 2010; 58:1258-67. [PMID: 20307556 DOI: 10.1016/j.neuropharm.2010.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 02/26/2010] [Accepted: 03/15/2010] [Indexed: 01/05/2023]
Abstract
Inhibition of pro-survival Bcl-2 family proteins by BH3-only proteins is a key initial step leading to apoptotic cell death. In neurons, investigating cell death pathways is often hampered by the multi-factorial nature of the stress stimuli employed. Here we investigate the action of ABT-737, a small molecule inhibitor which specifically targets the BH3-protein binding domain of pro-survival Bcl-2, Bcl-X(L) and Bcl-w. ABT-737 produced a time- and concentration-dependent neuronal cell death which displayed the classical hallmarks of apoptosis. Cell death was maximal by around 4 h ABT-737 treatment, and the effect of ABT-737 could be delayed by the broad spectrum caspase inhibitor zVADfmk. Examining, using real-time confocal microscopy, the molecular basis for the onset of response demonstrated recruitment of pro-apoptotic Bax to specific mitochondrial foci, followed by mitochondrial fragmentation. Treatment of neurons with ABT-737 also produced cleavage of Bid, a BH3-only protein known to be a caspase substrate. Interestingly, cleaved Bid translocated to mitochondria but did not colocalise with Bax foci. zVADfmk inhibited Bid cleavage and slowed the rate of fragmentation, suggesting a role for cleaved Bid in the amplification of the apoptotic response. siRNA-mediated knockdown of Bax significantly inhibited ABT-737 induced cell death, whereas knockdown of the BH3-only proteins Bid or Bim had no effect. ABT-737 therefore appears to be a useful tool with which to examine neuronal apoptotic pathways. Our data suggests that caspase-dependent cleavage of Bid may be a downstream amplification event which enhances the rate of mitochondrial fragmentation.
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Affiliation(s)
- Kenneth W Young
- MRC Toxicology Unit, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
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