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Ni W, Ye Y, Wang S, Li X, Li H, Cheng D, Jia Q, Liu Z, Shan S, Qiang Y, Chao S, Zhao X, Song F. Pyrrole adducts mediated mitochondrial dysfunction activates SARM1-dependent axon degeneration in 2,5-hexanedione-induced neuropathy. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 360:124651. [PMID: 39094998 DOI: 10.1016/j.envpol.2024.124651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 07/21/2024] [Accepted: 07/30/2024] [Indexed: 08/04/2024]
Abstract
2,5-hexanedione (HD) is the γ-diketone metabolite of industrial organic solvent n-hexane, primarily responsible for n-hexane neurotoxicity. Previous studies have shown that the formation of pyrrole adducts (PAs) is crucial for the toxic axonopathy induced by HD. However, the exact mechanism underlying PAs-induced axonal degeneration remains unclear. Recently, Sterile α and toll/interleukin 1 receptor motif-containing protein 1 (SARM1) has been identified as the central executor of axon degeneration. This study was designed to investigate the role of SARM1-mediated axon degeneration in rats exposed to HD. Furthermore, the causal relationship between PAs and SARM1-mediated axon degeneration was further explored using Sarm1 KO mice. Our findings suggest that HD causes axon degeneration and neuronal loss in animals. Mechanistic studies revealed that HD activates SARM1-dependent axonal degeneration machinery. In contrast, Sarm1 KO attenuates motor dysfunction and rescues neuron loss following HD exposure. Interestingly, the PAs formed by the binding of HD to proteins primarily accumulate on mitochondria, leading to mitochondrial dysfunction. This dysfunction serves as an upstream event in HD-induced nerve injuries. Our findings highlight the crucial role of PAs formation in the major pathological changes during n-hexane poisoning, providing a potential therapeutic target for n-hexane neuropathy.
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Affiliation(s)
- Wenting Ni
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China; Gansu Provincial Hospital, Lanzhou, Gansu, 730000, China
| | - Yihan Ye
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Shuai Wang
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Xianjie Li
- Institute of Biological and Medical Engineering, Guangdong Academy of Sciences, Guangzhou, Guangdong, 510075, China
| | - Hui Li
- Department of Health Test and Detection, Shandong Center for Disease Control and Prevention, Jinan, Shandong, 250014, China
| | - Dong Cheng
- Department of Health Test and Detection, Shandong Center for Disease Control and Prevention, Jinan, Shandong, 250014, China
| | - Qiang Jia
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Science, Jinan, Shandong, 250062, China
| | - Zhidan Liu
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Shulin Shan
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Yalong Qiang
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Shihua Chao
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Xiulan Zhao
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Fuyong Song
- Department of Toxicology, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.
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Misawa H, Kamishima K, Koyama T, Ohgaki L, Morisaki Y, Yamanaka T, Itohara S, Sawano S, Mizunoya W, Ogihara N. Type selective ablation of postnatal slow and fast fatigue-resistant motor neurons in mice induces late onset kinetic and postural tremor following fiber-type transition and myopathy. Exp Neurol 2024; 376:114772. [PMID: 38599366 DOI: 10.1016/j.expneurol.2024.114772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 03/28/2024] [Accepted: 04/06/2024] [Indexed: 04/12/2024]
Abstract
Animals on Earth need to hold postures and execute a series of movements under gravity and atmospheric pressure. VAChT-Cre is a transgenic Cre driver mouse line that expresses Cre recombinase selectively in motor neurons of S-type (slow-twitch fatigue-resistant) and FR-type (fast-twitch fatigue-resistant). Sequential motor unit recruitment is a fundamental principle for fine and smooth locomotion; smaller-diameter motor neurons (S-type, FR-type) first contract low-intensity oxidative type I and type IIa muscle fibers, and thereafter larger-diameter motor neurons (FInt-type, FF-type) are recruited to contract high-intensity glycolytic type IIx and type IIb muscle fibers. To selectively eliminate S- and FR-type motor neurons, VAChT-Cre mice were crossbred with NSE-DTA mice in which the cytotoxic diphtheria toxin A fragment (DTA) was expressed in Cre-expressing neurons. The VAChT-Cre;NSE-DTA mice were born normally but progressively manifested various characteristics, including body weight loss, kyphosis, kinetic and postural tremor, and muscular atrophy. The progressive kinetic and postural tremor was remarkable from around 20 weeks of age and aggravated. Muscular atrophy was apparent in slow muscles, but not in fast muscles. The increase in motor unit number estimation was detected by electromyography, reflecting compensatory re-innervation by remaining FInt- and FF-type motor neurons to the orphaned slow muscle fibers. The muscle fibers gradually manifested fast/slow hybrid phenotypes, and the remaining FInt-and FF-type motor neurons gradually disappeared. These results suggest selective ablation of S- and FR-type motor neurons induces progressive muscle fiber-type transition, exhaustion of remaining FInt- and FF-type motor neurons, and late-onset kinetic and postural tremor in mice.
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Affiliation(s)
- Hidemi Misawa
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan.
| | - Kai Kamishima
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Tenkei Koyama
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Lisa Ohgaki
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Yuta Morisaki
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Tomoyuki Yamanaka
- Department of Neuroscience of Disease, Brain Research Institute, Niigata University, Chuo-ku, Niigata, Japan
| | - Shigeyoshi Itohara
- Laboratory for Behavioral Genetics, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Shoko Sawano
- Department of Food and Life Science, School of Life and Environmental Science, Azabu University, Sagamihara, Kanagawa, Japan
| | - Wataru Mizunoya
- Department of Animal Science and Biotechnology, School of Veterinary Medicine, Azabu University, Sagamihara, Kanagawa, Japan
| | - Naomichi Ogihara
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Márquez BT, Leung TCS, Hui J, Charron F, McKinney RA, Watt AJ. A mitochondrial-targeted antioxidant (MitoQ) improves motor coordination and reduces Purkinje cell death in a mouse model of ARSACS. Neurobiol Dis 2023; 183:106157. [PMID: 37209925 DOI: 10.1016/j.nbd.2023.106157] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 05/10/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023] Open
Abstract
Mitochondrial deficits have been observed in animal models of Autosomal-recessive spastic ataxia of the Charlevoix-Saguenay (ARSACS) and in patient-derived fibroblasts. We investigated whether mitochondrial function could be restored in Sacs-/- mice, a mouse model of ARSACS, using the mitochondrial-targeted antioxidant ubiquinone MitoQ. After 10 weeks of chronic MitoQ administration in drinking water, we partially reversed motor coordination deficits in Sacs-/- mice but did not affect litter-matched wild-type control mice. MitoQ administration led to a restoration of superoxide dismutase 2 (SOD2) in cerebellar Purkinje cell somata without altering Purkinje cell firing deficits. Purkinje cells in anterior vermis of Sacs-/- mice normally undergo cell death in ARSACS; however, Purkinje cells numbers were elevated after chronic MitoQ treatment. Furthermore, Purkinje cell innervation of target neurons in the cerebellar nuclei of Sacs-/- mice were also partially restored with MitoQ treatment. Our data suggest that MitoQ is a potential therapeutic treatment for ARSACS and that it improves motor coordination via increasing cerebellar Purkinje cell mitochondria function and reducing Purkinje cell death.
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Affiliation(s)
| | | | - Jeanette Hui
- Department of Biology, McGill University, Montreal, QC, Canada
| | - François Charron
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada.
| | - Alanna J Watt
- Department of Biology, McGill University, Montreal, QC, Canada.
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4
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Gotoh H, Chimhanda TA, Nomura T, Ono K. STAT3 transcriptionally regulates the expression of genes related to glycogen metabolism in developing motor neurons. FEBS Lett 2022; 596:2940-2951. [PMID: 36050761 DOI: 10.1002/1873-3468.14489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/29/2022] [Accepted: 08/22/2022] [Indexed: 11/06/2022]
Abstract
Motor neurons in the spinal cord are essential for movement. During the embryonic period, developing motor neurons store glycogen to protect against hypoglycemic and hypoxic stress. However, the mechanisms by which glycogen metabolism is regulated in motor neurons remain unclear. We herein investigated the transcriptional regulation of genes related to glycogen metabolism in the developing spinal cord. We focused on the regulatory mechanism of glycogen synthase (Gys1) and glycogen phosphorylase brain isoform (PygB), which play central roles in glycogen metabolism, and found that the transcription factor STAT3 regulated the expression of Gys1 and PygB via cis-regulatory promoter sequences in the developing spinal cord. These results suggest that STAT3 is important for the regulation of glycogen metabolism during motor neuron development.
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Affiliation(s)
- Hitoshi Gotoh
- Department of Biology, Kyoto Prefectural University of Medicine. Inamori Memorial Building, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto city, Kyoto, 603-0823, Japan
| | - Tatenda Alois Chimhanda
- Department of Biology, Kyoto Prefectural University of Medicine. Inamori Memorial Building, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto city, Kyoto, 603-0823, Japan.,Faculty of Health, Medicine and Life Sciences, Maastricht University Medical Center, Universiteitssingel 40, 6229, ER, Maastricht, the Netherlands
| | - Tadashi Nomura
- Department of Biology, Kyoto Prefectural University of Medicine. Inamori Memorial Building, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto city, Kyoto, 603-0823, Japan
| | - Katsuhiko Ono
- Department of Biology, Kyoto Prefectural University of Medicine. Inamori Memorial Building, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto city, Kyoto, 603-0823, Japan
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5
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Fulton RE, Pearson-Smith JN, Huynh CQ, Fabisiak T, Liang LP, Aivazidis S, High BA, Buscaglia G, Corrigan T, Valdez R, Shimizu T, Patel MN. Neuron-specific mitochondrial oxidative stress results in epilepsy, glucose dysregulation and a striking astrocyte response. Neurobiol Dis 2021; 158:105470. [PMID: 34371143 PMCID: PMC8939287 DOI: 10.1016/j.nbd.2021.105470] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 08/02/2021] [Indexed: 10/20/2022] Open
Abstract
Mitochondrial superoxide (O2-) production is implicated in aging, neurodegenerative disease, and most recently epilepsy. Yet the specific contribution of neuronal O2- to these phenomena is unclear. Here, we selectively deleted superoxide dismutase-2 (SOD2) in neuronal basic helix-loop-helix transcription factor (NEX)-expressing cells restricting deletion to a subset of excitatory principle neurons primarily in the forebrain (cortex and hippocampus). This resulted in nSOD2 KO mice that lived into adulthood (2-3 months) with epilepsy, selective loss of neurons, metabolic rewiring and a marked mitohormetic gene response. Surprisingly, expression of an astrocytic gene, glial fibrillary acidic protein (GFAP) was significantly increased relative to WT. Further studies in rat primary neuron-glial cultures showed that increased mitochondrial O2-, specifically in neurons, was sufficient to upregulate GFAP. These results suggest that neuron-specific mitochondrial O2- is sufficient to drive a complex and catastrophic epileptic phenotype and highlights the ability of SOD2 to act in a cell-nonautonomous manner to influence an astrocytic response.
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Affiliation(s)
- Ruth E Fulton
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Jennifer N Pearson-Smith
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Division of Geriatric Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Christopher Q Huynh
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Timothy Fabisiak
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Li-Ping Liang
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Stefanos Aivazidis
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Brigit A High
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Georgia Buscaglia
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Timothy Corrigan
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Robert Valdez
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Takahiko Shimizu
- Aging Stress Response Research Project Team, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8511, Japan
| | - Manisha N Patel
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
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6
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Rosa AC, Corsi D, Cavi N, Bruni N, Dosio F. Superoxide Dismutase Administration: A Review of Proposed Human Uses. Molecules 2021; 26:1844. [PMID: 33805942 PMCID: PMC8037464 DOI: 10.3390/molecules26071844] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 12/12/2022] Open
Abstract
Superoxide dismutases (SODs) are metalloenzymes that play a major role in antioxidant defense against oxidative stress in the body. SOD supplementation may therefore trigger the endogenous antioxidant machinery for the neutralization of free-radical excess and be used in a variety of pathological settings. This paper aimed to provide an extensive review of the possible uses of SODs in a range of pathological settings, as well as describe the current pitfalls and the delivery strategies that are in development to solve bioavailability issues. We carried out a PubMed query, using the keywords "SOD", "SOD mimetics", "SOD supplementation", which included papers published in the English language, between 2012 and 2020, on the potential therapeutic applications of SODs, including detoxification strategies. As highlighted in this paper, it can be argued that the generic antioxidant effects of SODs are beneficial under all tested conditions, from ocular and cardiovascular diseases to neurodegenerative disorders and metabolic diseases, including diabetes and its complications and obesity. However, it must be underlined that clinical evidence for its efficacy is limited and consequently, this efficacy is currently far from being demonstrated.
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Affiliation(s)
- Arianna Carolina Rosa
- Department of Scienza e Tecnologia del Farmaco, University of Turin, Via P. Giuria 9, 10125 Turin, Italy; (D.C.); (N.C.); (F.D.)
| | - Daniele Corsi
- Department of Scienza e Tecnologia del Farmaco, University of Turin, Via P. Giuria 9, 10125 Turin, Italy; (D.C.); (N.C.); (F.D.)
| | - Niccolò Cavi
- Department of Scienza e Tecnologia del Farmaco, University of Turin, Via P. Giuria 9, 10125 Turin, Italy; (D.C.); (N.C.); (F.D.)
| | - Natascia Bruni
- Istituto Farmaceutico Candioli, Strada Comunale di None, 1, 10092 Beinasco, Italy;
| | - Franco Dosio
- Department of Scienza e Tecnologia del Farmaco, University of Turin, Via P. Giuria 9, 10125 Turin, Italy; (D.C.); (N.C.); (F.D.)
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Dynamic Phosphorylation of the C Terminus of Hsp70 Regulates the Mitochondrial Import of SOD2 and Redox Balance. Cell Rep 2019; 25:2605-2616.e7. [PMID: 30485823 DOI: 10.1016/j.celrep.2018.11.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 09/14/2018] [Accepted: 10/31/2018] [Indexed: 12/11/2022] Open
Abstract
The import of superoxide dismutase-2 (SOD2) into mitochondria is vital for the survival of eukaryotic cells. SOD2 is encoded within the nuclear genome and translocated into mitochondria for activation after translation in the cytosol. The molecular chaperone Hsp70 modulates SOD2 activity by promoting import of SOD2 into mitochondria. In turn, the activity of Hsp70 is controlled by co-chaperones, particularly CHIP, which directs Hsp70-bound proteins for degradation in the proteasomes. We investigated the mechanisms controlling the activity of SOD2 to signal activation and maintain mitochondrial redox balance. We demonstrate that Akt1 binds to and phosphorylates the C terminus of Hsp70 on Serine631, which inhibits CHIP-mediated SOD2 degradation thereby stabilizing and promoting SOD2 import. Conversely, increased mitochondrial-H2O2 formation disrupts Akt1-mediated phosphorylation of Hsp70, and non-phosphorylatable Hsp70 mutants decrease SOD2 import, resulting in mitochondrial oxidative stress. Our findings identify Hsp70 phosphorylation as a physiological mechanism essential for regulation of mitochondrial redox balance.
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8
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Susceptibility to Oxidative Stress Is Determined by Genetic Background in Neuronal Cell Cultures. eNeuro 2018; 5:eN-NWR-0335-17. [PMID: 29568799 PMCID: PMC5861596 DOI: 10.1523/eneuro.0335-17.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 01/28/2018] [Accepted: 02/18/2018] [Indexed: 01/24/2023] Open
Abstract
Traumatic brain injury (TBI) leads to a deleterious and multifactorial secondary inflammatory response in the brain. Oxidative stress from the inflammation likely contributes to the brain damage although it is unclear to which extent. A largely unexplored approach is to consider phenotypic regulation of oxidative stress levels. Genetic polymorphism influences inflammation in the central nervous system and it is possible that the antioxidative response differs between phenotypes and affects the severity of the secondary injury. We therefore compared the antioxidative response in inbred rat strains dark agouti (DA) to piebald viral glaxo (PVG). DA has high susceptibility to inflammatory challenges and PVG is protected. Primary neuronal cell cultures were exposed to peroxynitrite (ONOO-), nitric oxide (NO), superoxide (O2-), and 4-hydroxynonenal (4-HNE). Our findings demonstrated a phenotypic control of the neuronal antioxidative response, specific to manganese O2- dismutase (MnSOD). DA neurons had increased levels of MnSOD, equal levels of peroxiredoxin 5 (PRDX5), decreased oxidative stress markers 3-nitrotyrosine (3-NT) and 4-HNE and decreased neuronal death detected by lactate dehydrogenase (LDH) release after 24 h, and higher oxidative stress levels by CellROX than PVG after 2 h. It is possible that DA neurons had a phenotypic adaptation to a fiercer inflammatory environment. ONOO- was confirmed as the most powerful oxidative damage mediator, while 4-HNE caused few oxidative effects. Inducible NO synthase (iNOS) was not induced, suggesting that inflammatory, while not oxidative stimulation was required. These findings indicate that phenotypic antioxidative regulation affects the secondary inflammation, which should be considered in future individualized treatments and when evaluating antioxidative pharmacological interventions.
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On the Origin of Superoxide Dismutase: An Evolutionary Perspective of Superoxide-Mediated Redox Signaling. Antioxidants (Basel) 2017; 6:antiox6040082. [PMID: 29084153 PMCID: PMC5745492 DOI: 10.3390/antiox6040082] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 10/23/2017] [Accepted: 10/27/2017] [Indexed: 12/15/2022] Open
Abstract
The field of free radical biology originated with the discovery of superoxide dismutase (SOD) in 1969. Over the last 5 decades, a plethora of research has been performed in species ranging from bacteria to mammals that has elucidated the molecular reaction, subcellular location, and specific isoforms of SOD. However, while humans have only begun to study this class of enzymes over the past 50 years, it has been estimated that these enzymes have existed for billions of years, and may be some of the original enzymes found in primitive life. As life evolved over this expanse of time, these enzymes have taken on new and different functional roles potentially in contrast to how they were originally derived. Herein, examination of the evolutionary history of these enzymes provides both an explanation and further inquiries into the modern-day role of SOD in physiology and disease.
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10
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Misawa H, Inomata D, Kikuchi M, Maruyama S, Moriwaki Y, Okuda T, Nukina N, Yamanaka T. Reappraisal of VAChT-Cre: Preference in slow motor neurons innervating type I or IIa muscle fibers. Genesis 2016; 54:568-572. [PMID: 27596971 DOI: 10.1002/dvg.22979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 08/31/2016] [Accepted: 09/01/2016] [Indexed: 12/26/2022]
Abstract
VAChT-Cre.Fast and VAChT-Cre.Slow mice selectively express Cre recombinase in approximately one half of postnatal somatic motor neurons. The mouse lines have been used in various studies with selective genetic modifications in adult motor neurons. In the present study, we crossed VAChT-Cre lines with a reporter line, CAG-Syp/tdTomato, in which synaptophysin-tdTomato fusion proteins are efficiently sorted to axon terminals, making it possible to label both cell bodies and axon terminals of motor neurons. In the mice, Syp/tdTomato fluorescence preferentially co-localized with osteopontin, a recently discovered motor neuron marker for slow-twitch fatigue-resistant (S) and fast-twitch fatigue-resistant (FR) types. The fluorescence did not preferentially co-localize with matrix metalloproteinase-9, a marker for fast-twitch fatigable (FF) motor neurons. In the neuromuscular junctions, Syp/tdTomato fluorescence was detected mainly in motor nerve terminals that innervate type I or IIa muscle fibers. These results suggest that the VAChT-Cre lines are Cre-drivers that have selectivity in S and FR motor neurons. In order to avoid confusion, we have changed the mouse line names from VAChT-Cre.Fast and VAChT-Cre.Slow to VAChT-Cre.Early and VAChT-Cre.Late, respectively. The mouse lines will be useful tools to study slow-type motor neurons, in relation to physiology and pathology.
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Affiliation(s)
- Hidemi Misawa
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Daijiro Inomata
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Miseri Kikuchi
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Sae Maruyama
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Yasuhiro Moriwaki
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Takashi Okuda
- Division of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Nobuyuki Nukina
- Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, Kyoto, Japan
| | - Tomoyuki Yamanaka
- Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, Kyoto, Japan
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11
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Lei XG, Zhu JH, Cheng WH, Bao Y, Ho YS, Reddi AR, Holmgren A, Arnér ESJ. Paradoxical Roles of Antioxidant Enzymes: Basic Mechanisms and Health Implications. Physiol Rev 2016; 96:307-64. [PMID: 26681794 DOI: 10.1152/physrev.00010.2014] [Citation(s) in RCA: 262] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from aerobic metabolism, as a result of accidental electron leakage as well as regulated enzymatic processes. Because ROS/RNS can induce oxidative injury and act in redox signaling, enzymes metabolizing them will inherently promote either health or disease, depending on the physiological context. It is thus misleading to consider conventionally called antioxidant enzymes to be largely, if not exclusively, health protective. Because such a notion is nonetheless common, we herein attempt to rationalize why this simplistic view should be avoided. First we give an updated summary of physiological phenotypes triggered in mouse models of overexpression or knockout of major antioxidant enzymes. Subsequently, we focus on a series of striking cases that demonstrate "paradoxical" outcomes, i.e., increased fitness upon deletion of antioxidant enzymes or disease triggered by their overexpression. We elaborate mechanisms by which these phenotypes are mediated via chemical, biological, and metabolic interactions of the antioxidant enzymes with their substrates, downstream events, and cellular context. Furthermore, we propose that novel treatments of antioxidant enzyme-related human diseases may be enabled by deliberate targeting of dual roles of the pertaining enzymes. We also discuss the potential of "antioxidant" nutrients and phytochemicals, via regulating the expression or function of antioxidant enzymes, in preventing, treating, or aggravating chronic diseases. We conclude that "paradoxical" roles of antioxidant enzymes in physiology, health, and disease derive from sophisticated molecular mechanisms of redox biology and metabolic homeostasis. Simply viewing antioxidant enzymes as always being beneficial is not only conceptually misleading but also clinically hazardous if such notions underpin medical treatment protocols based on modulation of redox pathways.
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Affiliation(s)
- Xin Gen Lei
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Jian-Hong Zhu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Wen-Hsing Cheng
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Yongping Bao
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ye-Shih Ho
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Amit R Reddi
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Arne Holmgren
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Elias S J Arnér
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing,China; Department of Animal Science, Cornell University, Ithaca, New York; Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, Mississippi; Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom; Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan; Georgia Institute of Technology, School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Atlanta, Georgia; and Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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12
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Brain-Specific Superoxide Dismutase 2 Deficiency Causes Perinatal Death with Spongiform Encephalopathy in Mice. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:238914. [PMID: 26301039 PMCID: PMC4537744 DOI: 10.1155/2015/238914] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/26/2014] [Indexed: 01/23/2023]
Abstract
Oxidative stress is believed to greatly contribute to the pathogenesis of various diseases, including neurodegeneration. Impairment of mitochondrial energy production and increased mitochondrial oxidative damage are considered early pathological events that lead to neurodegeneration. Manganese superoxide dismutase (Mn-SOD, SOD2) is a mitochondrial antioxidant enzyme that converts toxic superoxide to hydrogen peroxide. To investigate the pathological role of mitochondrial oxidative stress in the central nervous system, we generated brain-specific SOD2-deficient mice (B-Sod2−/−) using nestin-Cre-loxp system. B-Sod2−/− showed perinatal death, along with severe growth retardation. Interestingly, these mice exhibited spongiform neurodegeneration in motor cortex, hippocampus, and brainstem, accompanied by gliosis. In addition, the mutant mice had markedly decreased mitochondrial complex II activity, but not complex I or IV, in the brain based on enzyme histochemistry. Furthermore, brain lipid peroxidation was significantly increased in the B-Sod2−/−, without any compensatory alterations of the activities of other antioxidative enzymes, such as catalase or glutathione peroxidase. These results suggest that SOD2 protects the neural system from oxidative stress in the perinatal stage and is essential for infant survival and central neural function in mice.
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13
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Liu G, Elrashidy RA, Xiao N, Kavran M, Huang Y, Tao M, Powell CT, Kim E, Sadeghi G, Mohamed HE, Daneshgari F. Bladder function in mice with inducible smooth muscle-specific deletion of the manganese superoxide dismutase gene. Am J Physiol Cell Physiol 2015; 309:C169-78. [PMID: 25948732 DOI: 10.1152/ajpcell.00046.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/02/2015] [Indexed: 11/22/2022]
Abstract
Manganese superoxide dismutase (MnSOD) is considered a critical component of the antioxidant systems that protect against oxidative damage. We are interested in the role of oxidative stress in bladder detrusor smooth muscle (SM) in different disease states. In this study, we generated an inducible, SM-specific Sod2(-/-) mouse model to investigate the effects of MnSOD depletion on the function of the bladder. We crossbred floxed Sod2 (Sod2(lox/lox)) mice with mice containing heterozygous knock-in of a gene encoding a tamoxifen-activated Cre recombinase in the SM22α promoter locus [SM-CreER(T2)(ki)(Cre/+)]. We obtained Sod2(lox/lox),SM-CreER(T2)(ki)(Cre/+) mice and injected 8-wk-old males with 4-hydroxytamoxifen to induce Cre-mediated excision of the floxed Sod2 allele. Twelve weeks later, SM-specific deletion of Sod2 and depletion of MnSOD were confirmed by polymerase chain reaction, immunoblotting, and immunohistochemistry. SM-specific Sod2(-/-) mice exhibited normal growth with no gross abnormalities. A significant increase in nitrotyrosine concentration was found in bladder SM tissue of SM-specific Sod2(-/-) mice compared with both wild-type mice and Sod2(+/+), SM-CreER(T2)(ki)(Cre/+) mice treated with 4-hydroxytamoxifen. Assessment of 24-h micturition in SM-specific Sod2(-/-) mice revealed significantly higher voiding frequency compared with both wild-type and SM-specific Cre controls. Conscious cystometry revealed significantly shorter intercontraction intervals and lower functional bladder capacity in SM-specific Sod2(-/-) mice compared with wild-type mice. This novel model can be used for exploring the mechanistic role of oxidative stress in organs rich in SM in different pathological conditions.
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Affiliation(s)
- Guiming Liu
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Rania A Elrashidy
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio; Faculty of Pharmacy, Biochemistry Department, Zagazig University, Zagazig, Egypt
| | - Nan Xiao
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio; Department of Urology, The Second Hospital of Lanzhou University, Lanzhou, China; and
| | - Michael Kavran
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Yexiang Huang
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio; Department of Urology, The First Affiliated Hospital, China Medical University, Shenyang, China
| | - Mingfang Tao
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - C Thomas Powell
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Edward Kim
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Ghazal Sadeghi
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Hoda E Mohamed
- Faculty of Pharmacy, Biochemistry Department, Zagazig University, Zagazig, Egypt
| | - Firouz Daneshgari
- Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio;
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14
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Maity‐Kumar G, Thal DR, Baumann B, Scharffetter‐Kochanek K, Wirth T. Neuronal redox imbalance results in altered energy homeostasis and early postnatal lethality. FASEB J 2015; 29:2843-58. [DOI: 10.1096/fj.14-265157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 03/09/2015] [Indexed: 12/15/2022]
Affiliation(s)
| | - Dietmar R. Thal
- Laboratory of Neuropathology, Institute for Pathology, University of UlmUlmGermany
| | - Bernd Baumann
- Institute of Physiological Chemistry, University of UlmUlmGermany
| | | | - Thomas Wirth
- Institute of Physiological Chemistry, University of UlmUlmGermany
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15
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Resveratrol ameliorates motor neuron degeneration and improves survival in SOD1(G93A) mouse model of amyotrophic lateral sclerosis. BIOMED RESEARCH INTERNATIONAL 2014; 2014:483501. [PMID: 25057490 PMCID: PMC4095711 DOI: 10.1155/2014/483501] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 04/16/2014] [Indexed: 01/27/2023]
Abstract
Resveratrol has recently been used as a supplemental treatment for several neurological and nonneurological diseases. It is not known whether resveratrol has neuroprotective effect on amyotrophic lateral sclerosis (ALS). To assess the effect of resveratrol on the disease, we tested this agent on an ALS model of SOD1G93A transgenic mouse. Rotarod measurement was performed to measure the motor function of the ALS mice. Nissl staining and SMI-32 immunofluorescent staining were used to determine motor neurons survival in the spinal cord of the ALS mice. Hematoxylin-eosin (H&E), succinic dehydrogenase (SDH), and cytochrome oxidase (COX) staining were applied to pathologically analyze the skeletal muscles of the ALS mice. We found that resveratrol treatment significantly delayed the disease onset and prolonged the lifespan of the ALS mice. Furthermore, resveratrol treatment attenuated motor neuron loss, relieved muscle atrophy, and improved mitochondrial function of muscle fibers in the ALS mice. In addition, we demonstrated that resveratrol exerted these neuroprotective effects mainly through increasing the expression of Sirt1, consequently suppressing oxidative stress and downregulating p53 and its related apoptotic pathway. Collectively, our findings suggest that resveratrol might provide a promising therapeutic intervention for ALS.
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16
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Edrey YH, Salmon AB. Revisiting an age-old question regarding oxidative stress. Free Radic Biol Med 2014; 71:368-378. [PMID: 24704971 PMCID: PMC4049226 DOI: 10.1016/j.freeradbiomed.2014.03.038] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 03/27/2014] [Accepted: 03/27/2014] [Indexed: 02/06/2023]
Abstract
Significant advances in maintaining health throughout life can be made through a clear understanding of the fundamental mechanisms that regulate aging. The Oxidative Stress Theory of Aging (OSTA) is probably the most well studied mechanistic theory of aging and suggests that the rate of aging is controlled by accumulation of oxidative damage. To directly test the OSTA, aging has been measured in several lines of mice with genetic alterations in the expression of enzymatic antioxidants. Under its strictest interpretation, these studies do not support the OSTA, as modulation of antioxidant expression does not generally affect mouse life span. However, the incidence of many age-related diseases and pathologies is altered in these models, suggesting that oxidative stress does significantly influence some aspects of the aging process. Further, oxidative stress may affect aging in disparate patterns among tissues or under various environmental conditions. In this review, we summarize the current literature regarding aging in antioxidant mutant mice and offer several interpretations of their support of the OSTA.
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Affiliation(s)
- Yael H Edrey
- The Sam and Ann Barshop Institute for Longevity and Aging Studies and San Antonio, TX 78229, USA
| | - Adam B Salmon
- The Sam and Ann Barshop Institute for Longevity and Aging Studies and San Antonio, TX 78229, USA; The Geriatric Research Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX 78229, USA; Department of Molecular Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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17
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Marecki JC, Parajuli N, Crow JP, MacMillan-Crow LA. The use of the Cre/loxP system to study oxidative stress in tissue-specific manganese superoxide dismutase knockout models. Antioxid Redox Signal 2014; 20:1655-70. [PMID: 23641945 PMCID: PMC3942694 DOI: 10.1089/ars.2013.5293] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
SIGNIFICANCE Respiring mitochondria are a significant site for reactions involving reactive oxygen and nitrogen species that contribute to irreversible cellular, structural, and functional damage leading to multiple pathological conditions. Manganese superoxide dismutase (MnSOD) is a critical component of the antioxidant system tasked with protecting the oxidant-sensitive mitochondrial compartment from oxidative stress. Since global knockout of MnSOD results in significant cardiac and neuronal damage leading to early postnatal lethality, this approach has limited use for studying the mechanisms of oxidant stress and the development of disease in specific tissues lacking MnSOD. To circumvent this problem, a number of investigators have employed the Cre/loxP system to precisely knockout MnSOD in individual tissues. RECENT ADVANCES Multiple tissue and organ-specific Cre-expressing mice have been generated, which greatly enhance the specificity of MnSOD knockout in tissues and organ systems that were once difficult, if not impossible to study. CRITICAL ISSUES Evaluating the contribution of MnSOD deficiency to oxidant-mediated mitochondrial damage requires careful consideration of the promoter system used for creating the tissue-specific knockout animal, in addition to the collection and interpretation of multiple indices of oxidative stress and damage. FUTURE DIRECTIONS Expanded use of well-characterized tissue-specific promoter elements and inducible systems to drive the Cre/loxP recombinational events will lead to a spectrum of MnSOD tissue knockout models, and a clearer understanding of the role of MnSOD in preventing mitochondrial dysfunction in human disease.
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Affiliation(s)
- John C Marecki
- 1 Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences , Little Rock, Arkansas
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18
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Zhang X, Chen S, Song L, Tang Y, Shen Y, Jia L, Le W. MTOR-independent, autophagic enhancer trehalose prolongs motor neuron survival and ameliorates the autophagic flux defect in a mouse model of amyotrophic lateral sclerosis. Autophagy 2014; 10:588-602. [PMID: 24441414 DOI: 10.4161/auto.27710] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder caused by selective motor neuron degeneration. Abnormal protein aggregation and impaired protein degradation pathways may contribute to the disease pathogenesis. Although it has been reported that autophagy is altered in patients and animal model of ALS, little is known about the role of autophagy in motor neuron degeneration in this disease. Our previous study shows that rapamycin, an MTOR-dependent autophagic activator, accelerates disease progression in the SOD1(G93A) mouse model of ALS. In the present report, we have assessed the role of the MTOR-independent autophagic pathway in ALS by determining the effect of the MTOR-independent autophagic inducer trehalose on disease onset and progression, and on motor neuron degeneration in SOD1(G93A) mice. We have found that trehalose significantly delays disease onset prolongs life span, and reduces motor neuron loss in the spinal cord of SOD1(G93A) mice. Most importantly, we have documented that trehalose decreases SOD1 and SQSTM1/p62 aggregation, reduces ubiquitinated protein accumulation, and improves autophagic flux in the motor neurons of SOD1(G93A) mice. Moreover, we have demonstrated that trehalose can reduce skeletal muscle denervation, protect mitochondria, and inhibit the proapoptotic pathway in SOD1(G93A) mice. Collectively, our study indicated that the MTOR-independent autophagic inducer trehalose is neuroprotective in the ALS model and autophagosome-lysosome fusion is a possible therapeutic target for the treatment of ALS.
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Affiliation(s)
- Xiaojie Zhang
- Institute of Neurology; Ruijin Hospital; Jiao Tong University School of Medicine; Shanghai, China; The Key Laboratory of Stem Cell Biology; Institute of Health Sciences; Shanghai Institutes for Biological Sciences; Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine; Shanghai, China
| | - Sheng Chen
- Institute of Neurology; Ruijin Hospital; Jiao Tong University School of Medicine; Shanghai, China; Department of Neurology; Baylor College of Medicine; Houston, TX USA
| | - Lin Song
- Institute of Neurology; Ruijin Hospital; Jiao Tong University School of Medicine; Shanghai, China
| | - Yu Tang
- The Key Laboratory of Stem Cell Biology; Institute of Health Sciences; Shanghai Institutes for Biological Sciences; Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine; Shanghai, China
| | - Yufei Shen
- Institute of Neurology; Ruijin Hospital; Jiao Tong University School of Medicine; Shanghai, China
| | - Li Jia
- The Key Laboratory of Stem Cell Biology; Institute of Health Sciences; Shanghai Institutes for Biological Sciences; Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine; Shanghai, China
| | - Weidong Le
- Institute of Neurology; Ruijin Hospital; Jiao Tong University School of Medicine; Shanghai, China; The Key Laboratory of Stem Cell Biology; Institute of Health Sciences; Shanghai Institutes for Biological Sciences; Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine; Shanghai, China; The First Affiliated Hospital; Dalian Medical University; Dalian, China
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19
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Bird MJ, Thorburn DR, Frazier AE. Modelling biochemical features of mitochondrial neuropathology. Biochim Biophys Acta Gen Subj 2013; 1840:1380-92. [PMID: 24161927 DOI: 10.1016/j.bbagen.2013.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/29/2013] [Accepted: 10/11/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND The neuropathology of mitochondrial disease is well characterised. However, pathophysiological mechanisms at the level of biochemistry and cell biology are less clear. Progress in this area has been hampered by the limited accessibility of neurologically relevant material for analysis. SCOPE OF REVIEW Here we discuss the recent development of a variety of model systems that have greatly extended our capacity to understand the biochemical features associated with mitochondrial neuropathology. These include animal and cell based models, with mutations in both nuclear and mitochondrial DNA encoded genes, which aim to recapitulate the neuropathology and cellular biochemistry of mitochondrial diseases. MAJOR CONCLUSIONS Analysis of neurological tissue and cells from these models suggests that although there is no unifying mode of pathogenesis, dysfunction of the oxidative phosphorylation (OXPHOS) system is often central. This can be associated with altered reactive oxygen species (ROS) generation, disruption of the mitochondrial membrane potential (ΔΨm) and inadequate ATP synthesis. Thus, other cellular processes such as calcium (Ca(2+)) homeostasis, cellular signaling and mitochondrial morphology could be altered, ultimately compromising viability of neuronal cells. GENERAL SIGNIFICANCE Mechanisms of neuronal dysfunction in mitochondrial disease are only just beginning to be characterised, are system dependent and complex, and not merely driven by energy deficiency. The diversity of pathogenic mechanisms emphasises the need for characterisation in a wide range of models, as different therapeutic strategies are likely to be needed for different diseases. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
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Affiliation(s)
- Matthew J Bird
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - David R Thorburn
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia; Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Australia
| | - Ann E Frazier
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia.
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20
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Flynn JM, Melov S. SOD2 in mitochondrial dysfunction and neurodegeneration. Free Radic Biol Med 2013; 62:4-12. [PMID: 23727323 PMCID: PMC3811078 DOI: 10.1016/j.freeradbiomed.2013.05.027] [Citation(s) in RCA: 235] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 05/15/2013] [Accepted: 05/17/2013] [Indexed: 12/15/2022]
Abstract
The brain is a highly metabolically active tissue that critically relies on oxidative phosphorylation as a means for maintaining energy. One result of this process is the production of potentially damaging radicals such as the superoxide anion (O2(-)). Superoxide has the capacity to damage components of the electron transport chain and other cellular constituents. Eukaryotic systems have evolved defenses against such damaging moieties, the chief member of which is superoxide dismutase (SOD2), an enzyme that efficiently converts superoxide to the less reactive hydrogen peroxide (H2O2), which can freely diffuse across the mitochondrial membrane. Loss of SOD2 activity can result in numerous pathological phenotypes in metabolically active tissues, particularly within the central nervous system. We review SOD2's potential involvement in the progression of neurodegenerative diseases such as stroke and Alzheimer and Parkinson diseases, as well as its potential role in "normal" age-related cognitive decline. We also examine in vivo models of endogenous oxidative damage based upon the loss of SOD2 and associated neurological phenotypes in relation to human neurodegenerative disorders.
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Affiliation(s)
- James M Flynn
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Simon Melov
- Buck Institute for Research on Aging, Novato, CA 94945, USA.
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21
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Galactooligosaccharide improves the animal survival and alleviates motor neuron death in SOD1G93A mouse model of amyotrophic lateral sclerosis. Neuroscience 2013; 246:281-90. [DOI: 10.1016/j.neuroscience.2013.05.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 03/27/2013] [Accepted: 05/03/2013] [Indexed: 12/13/2022]
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22
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Cyr AR, Hitchler MJ, Domann FE. Regulation of SOD2 in cancer by histone modifications and CpG methylation: closing the loop between redox biology and epigenetics. Antioxid Redox Signal 2013; 18:1946-55. [PMID: 22946823 PMCID: PMC3624766 DOI: 10.1089/ars.2012.4850] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
SIGNIFICANCE Manganese superoxide dismutase (SOD2), encoded by the nuclear gene SOD2, is a critical mitochondrial antioxidant enzyme whose activity has broad implications in health and disease. Thirty years ago, Oberley and Buettner elegantly folded SOD2 into cancer biology with the free radical theory of cancer, which was built on the observation that many human cancers had reduced SOD2 activity. In the original formulation, the loss of SOD2 in tumor cells produced a state of perpetual oxidative stress, which, in turn, drove genetic instability, leading to cancer development. RECENT ADVANCES In the past two decades, research has established that SOD2 transcriptional activity is controlled, at least in part, via epigenetic mechanisms at different stages in the development of human cancer. These mechanisms, which include histone methylation, histone acetylation, and DNA methylation, are increasingly recognized as being aberrantly regulated in human cancer. Indeed, the epigenetic progenitor model proposed by Henikoff posits that epigenetic events are central governing agents of carcinogenesis. Important recent advances in epigenetics research have indicated that the loss of SOD activity itself may contribute to changes in epigenetic regulation, establishing a vicious cycle that drives further epigenetic instability. CRITICAL ISSUES With these observations in mind, we propose an epigenetic revision to the free radical theory of cancer: that loss of SOD activity promotes epigenetic aberrancies, driving the epigenetic instability in tumor cells which produces broad phenotypic effects. FUTURE DIRECTIONS The development of next-generation sequencing technologies and novel approaches in systems biology and bioinformatics promise to make testing this exciting model a reality in the near future.
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Affiliation(s)
- Anthony R Cyr
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, and Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242-1181, USA
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23
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Holley AK, Dhar SK, St Clair DK. Curbing cancer's sweet tooth: is there a role for MnSOD in regulation of the Warburg effect? Mitochondrion 2013; 13:170-88. [PMID: 22820117 PMCID: PMC4604438 DOI: 10.1016/j.mito.2012.07.104] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 07/04/2012] [Accepted: 07/10/2012] [Indexed: 01/27/2023]
Abstract
Reactive oxygen species (ROS), while vital for normal cellular function, can have harmful effects on cells, leading to the development of diseases such as cancer. The Warburg effect, the shift from oxidative phosphorylation to glycolysis, even in the presence of adequate oxygen, is an important metabolic change that confers many growth and survival advantages to cancer cells. Reactive oxygen species are important regulators of the Warburg effect. The mitochondria-localized antioxidant enzyme manganese superoxide dismutase (MnSOD) is vital to survival in our oxygen-rich atmosphere because it scavenges mitochondrial ROS. MnSOD is important in cancer development and progression. However, the significance of MnSOD in the regulation of the Warburg effect is just now being revealed, and it may significantly impact the treatment of cancer in the future.
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Affiliation(s)
- Aaron K. Holley
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536
| | - Sanjit Kumar Dhar
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536
| | - Daret K. St Clair
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536
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24
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Glutathione and thioredoxin dependent systems in neurodegenerative disease: What can be learned from reverse genetics in mice. Neurochem Int 2013; 62:738-49. [DOI: 10.1016/j.neuint.2013.01.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 12/20/2012] [Accepted: 01/08/2013] [Indexed: 12/21/2022]
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25
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Zhou LY, Liu JP, Wang K, Gao J, Ding SL, Jiao JQ, Li PF. Mitochondrial function in cardiac hypertrophy. Int J Cardiol 2012; 167:1118-25. [PMID: 23044430 DOI: 10.1016/j.ijcard.2012.09.082] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 08/24/2012] [Accepted: 09/15/2012] [Indexed: 10/27/2022]
Abstract
Cardiac hypertrophic program is a chronic, complex process, and occurs in response to long-term increases of hemodynamic load related to a variety of pathophysiological conditions. Mitochondria, known as "the cellular power plants", occupy about one-third of cardiomyocyte volume and supply roughly 90% of the adenosine triphosphate (ATP). Impairment of energy metabolism has been regarded as one of the main pathogenesis of cardiac hypertrophy. Thus, we summarize here the molecular events of mitochondrial adaptations, including the mitochondrial genesis, ATP generation, ROS signaling and Ca(2+) homeostasis in cardiac hypertrophy, expecting that this effort will shed new light on understanding the maladaptive cardiac remodeling.
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Affiliation(s)
- Lu-Yu Zhou
- Division of Cardiovascular Research, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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26
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Case AJ, Domann FE. Manganese superoxide dismutase is dispensable for post-natal development and lactation in the murine mammary gland. Free Radic Res 2012; 46:1361-8. [PMID: 22834911 DOI: 10.3109/10715762.2012.715370] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mammary gland development is a multistage process requiring tightly regulated spatial and temporal signalling pathways. Many of these pathways have been shown to be sensitive to oxidative stress. Understanding that the loss of manganese superoxide dismutase (Sod2) leads to increased cellular oxidative stress, and that the loss or silencing of this enzyme has been implicated in numerous pathologies including those of the mammary gland, we sought to examine the role of Sod2 in mammary gland development and function in situ in the mouse mammary gland. Using Cre-recombination driven by the mouse mammary tumor virus (MMTV) promoter, we created a mammary-specific post-natal conditional Sod2 knock-out mouse model. Surprisingly, while substantial decreases in Sod2 were noted throughout both virgin and lactating adult mammary glands, no significant changes in developmental structures either pre- or post-pregnancy were observed histologically. Moreover, mothers lacking mammary gland expression of Sod2 were able to sustain equal numbers of litters, equal pups per litter, and equal pup weights as were control animals. Overall, our results demonstrate that loss of Sod2 expression is not universally toxic to all cell types and that excess mitochondrial superoxide can apparently be tolerated during the development and function of post-natal mammary glands.
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Affiliation(s)
- Adam J Case
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA 52240, USA
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Court FA, Coleman MP. Mitochondria as a central sensor for axonal degenerative stimuli. Trends Neurosci 2012; 35:364-72. [PMID: 22578891 DOI: 10.1016/j.tins.2012.04.001] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 03/19/2012] [Accepted: 04/02/2012] [Indexed: 12/12/2022]
Abstract
Axonal degeneration is a major contributor to neuronal dysfunction in many neurological conditions and has additional roles in development. It can be triggered by divergent stimuli including mechanical, metabolic, infectious, toxic, hereditary and inflammatory stresses. Axonal mitochondria are an important convergence point as regulators of bioenergetic metabolism, reactive oxygen species (ROS), Ca²⁺ homeostasis and protease activation. The challenges likely to render axonal mitochondria more vulnerable than their cellular counterparts are reviewed, including axonal transport, replenishing nuclear-encoded proteins and maintenance of quality control, fusion and fission in locations remote from the cell body. The potential for mitochondria to act as a decision node in axon loss is considered, highlighting the need to understand the biology of axonal mitochondria and their contributions to degenerative mechanisms for novel therapeutic strategies.
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Affiliation(s)
- Felipe A Court
- Millennium Nucleus for Regenerative Biology, Faculty of Biology, Catholic University of Chile, Santiago 8331150, Chile.
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Oh SS, Sullivan KA, Wilkinson JE, Backus C, Hayes JM, Sakowski SA, Feldman EL. Neurodegeneration and early lethality in superoxide dismutase 2-deficient mice: a comprehensive analysis of the central and peripheral nervous systems. Neuroscience 2012; 212:201-13. [PMID: 22516022 DOI: 10.1016/j.neuroscience.2012.03.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 03/02/2012] [Accepted: 03/20/2012] [Indexed: 01/17/2023]
Abstract
The contribution of oxidative stress to diabetic complications including neuropathy is widely known. Mitochondrial and cellular damage are associated with the overproduction of reactive oxygen species and decreased levels or function of the cellular antioxidant mitochondrial manganese superoxide dismutase (SOD2). We hypothesized that targeted SOD2 deletion in the peripheral nervous system using cre-lox technology under control of the nestin promoter would accelerate neuropathy in a type 2 model of diabetes, the BKS.db/db mouse. SOD2-deficient mice, however, demonstrated severe gait deformities and seizures and died by 20 days of age. Examination of SOD2 expression levels revealed that SOD2 was lost in brain and reduced in the spinal cord, but appeared normal in dorsal root ganglia and peripheral nerves in SOD2-deficient mice. These findings indicate incomplete targeted knockout of SOD2. Morphological examination revealed cortical lesions similar to spongiform encephalopathy in the brain of SOD2-deficient mice. No lesions were evident in the spinal cord, but changes in myelin within the sciatic and sural nerves including a lack of cohesion between layers of compact myelin were observed. Together, these results indicate that targeted neuronal SOD2 knockout using the nestin promoter results in severe central nervous system degeneration and perinatal lethality in mice. A specific peripheral nervous system-targeting construct is required to examine the consequences of SOD2 knockout in diabetic neuropathy.
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Affiliation(s)
- S S Oh
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
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Morimoto N, Miyazaki K, Kurata T, Ikeda Y, Matsuura T, Kang D, Ide T, Abe K. Effect of mitochondrial transcription factor a overexpression on motor neurons in amyotrophic lateral sclerosis model mice. J Neurosci Res 2012; 90:1200-8. [PMID: 22354563 DOI: 10.1002/jnr.23000] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 10/22/2011] [Accepted: 10/23/2011] [Indexed: 11/09/2022]
Abstract
Increasing evidence indicates that oxidative stress is an important mechanism underlying motor neuron (MN) degeneration in amyotrophic lateral sclerosis (ALS). Mitochondrial DNA (mtDNA) is highly susceptible to oxidative damage and has little potential for repair, although mitochondrial transcription factor A (TFAM) plays essential roles in maintaining mitochondrial DNA by reducing oxidative stress, promoting mtDNA transcription, and regulating mtDNA copy number. To analyze a possible therapeutic effect of TFAM on ALS pathology, double transgenic mice overexpressing G93A mutant SOD1 (G93ASOD1) and human TFAM (hTFAM) were newly generated in the present study. Rotarod scores were better in G93ASOD1/hTFAM double-Tg mice than G93ASOD1 single-Tg mice at an early symptomatic stage, 15 and 16 weeks of age, with a 10% extension of the onset age in double-Tg mice. The number of surviving MNs was 30% greater in double-Tg mice with end-stage disease, at 19 weeks, with remarkable reductions in the amount of the oxidative stress marker 8-OHdG and the apoptotic marker cleaved caspase 3 and with preserved COX1 expression. Double-immunofluorescence study showed that hTFAM was expressed specifically in MNs and microglia in the spinal cords of double-Tg mice. The present study suggests that overexpression of TFAM has a potential to reduce oxidative stress in MN and delay onset of the disease in ALS model mice. © 2012 Wiley Priodicals, Inc.
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Affiliation(s)
- Nobutoshi Morimoto
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama University, Okayama, Japan
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Hamilton RT, Walsh ME, Van Remmen H. Mouse Models of Oxidative Stress Indicate a Role for Modulating Healthy Aging. ACTA ACUST UNITED AC 2012; Suppl 4. [PMID: 25300955 DOI: 10.4172/2161-0681.s4-005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Aging is a complex process that affects every major system at the molecular, cellular and organ levels. Although the exact cause of aging is unknown, there is significant evidence that oxidative stress plays a major role in the aging process. The basis of the oxidative stress hypothesis is that aging occurs as a result of an imbalance between oxidants and antioxidants, which leads to the accrual of damaged proteins, lipids and DNA macromolecules with age. Age-dependent increases in protein oxidation and aggregates, lipofuscin, and DNA mutations contribute to age-related pathologies. Many transgenic/knockout mouse models over expressing or deficient in key antioxidant enzymes have been generated to examine the effect of oxidative stress on aging and age-related diseases. Based on currently reported lifespan studies using mice with altered antioxidant defense, there is little evidence that oxidative stress plays a role in determining lifespan. However, mice deficient in antioxidant enzymes are often more susceptible to age-related disease while mice overexpressing antioxidant enzymes often have an increase in the amount of time spent without disease, i.e., healthspan. Thus, by understanding the mechanisms that affect healthy aging, we may discover potential therapeutic targets to extend human healthspan.
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Affiliation(s)
- Ryan T Hamilton
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA ; Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA
| | - Michael E Walsh
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA
| | - Holly Van Remmen
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA ; Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA ; GRECC, South Texas Veterans Health Care System, San Antonio, TX, USA
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Holley AK, Bakthavatchalu V, Velez-Roman JM, St. Clair DK. Manganese superoxide dismutase: guardian of the powerhouse. Int J Mol Sci 2011; 12:7114-62. [PMID: 22072939 PMCID: PMC3211030 DOI: 10.3390/ijms12107114] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 09/28/2011] [Accepted: 10/08/2011] [Indexed: 12/18/2022] Open
Abstract
The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as β-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component.
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Affiliation(s)
- Aaron K. Holley
- Graduate Center for Toxicology, University of Kentucky, 454 HSRB, 1095 VA Drive, Lexington, KY 40536, USA; E-Mails: (A.K.H.); (V.B.); (J.M.V.-R.)
| | - Vasudevan Bakthavatchalu
- Graduate Center for Toxicology, University of Kentucky, 454 HSRB, 1095 VA Drive, Lexington, KY 40536, USA; E-Mails: (A.K.H.); (V.B.); (J.M.V.-R.)
| | - Joyce M. Velez-Roman
- Graduate Center for Toxicology, University of Kentucky, 454 HSRB, 1095 VA Drive, Lexington, KY 40536, USA; E-Mails: (A.K.H.); (V.B.); (J.M.V.-R.)
| | - Daret K. St. Clair
- Graduate Center for Toxicology, University of Kentucky, 454 HSRB, 1095 VA Drive, Lexington, KY 40536, USA; E-Mails: (A.K.H.); (V.B.); (J.M.V.-R.)
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Ido A, Fukuyama H, Urushitani M. Protein misdirection inside and outside motor neurons in Amyotrophic Lateral Sclerosis (ALS): a possible clue for therapeutic strategies. Int J Mol Sci 2011; 12:6980-7003. [PMID: 22072931 PMCID: PMC3211022 DOI: 10.3390/ijms12106980] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 10/09/2011] [Accepted: 10/11/2011] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by progressive muscle wasting and weakness with no effective cure. Emerging evidence supports the notion that the abnormal conformations of ALS-linked proteins play a central role in triggering the motor neuron degeneration. In particular, mutant types of superoxide dismutase 1 (SOD1) and TAR DNA binding protein 43kDa (TDP-43) are key molecules involved in the pathogenesis of familial and sporadic ALS, respectively. The commonalities of the two proteins include a propensity to aggregate and acquire detrimental conformations through oligomerization, fragmentation, or post-translational modification that may drive abnormal subcellular localizations. Although SOD1 is a major cytosolic protein, mutated SOD1 has been localized to mitochondria, endoplasmic reticulum, and even the extracellular space. The nuclear exclusion of TDP-43 is a pathological hallmark for ALS, although the pathogenic priority remains elusive. Nevertheless, these abnormal behaviors based on the protein misfolding are believed to induce diverse intracellular and extracellular events that may be tightly linked to non-cell-autonomous motor neuron death. The generation of mutant- or misfolded protein-specific antibodies would help to uncover the distribution and propagation of the ALS-linked proteins, and to design a therapeutic strategy to clear such species. Herein we review the literature regarding the mislocalization of ALS-linked proteins, especially mutant SOD1 and TDP-43 species, and discuss the rationale of molecular targeting strategies including immunotherapy.
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Affiliation(s)
- Akemi Ido
- Unit for Neurobiology and Therapeutics, Molecular Neuroscience Research Center, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan; E-Mail:
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan; E-Mail:
| | - Hidenao Fukuyama
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan; E-Mail:
| | - Makoto Urushitani
- Unit for Neurobiology and Therapeutics, Molecular Neuroscience Research Center, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +81-77-548-2328
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Parajuli N, Marine A, Simmons S, Saba H, Mitchell T, Shimizu T, Shirasawa T, MacMillan-Crow LA. Generation and characterization of a novel kidney-specific manganese superoxide dismutase knockout mouse. Free Radic Biol Med 2011; 51:406-16. [PMID: 21571061 PMCID: PMC3118857 DOI: 10.1016/j.freeradbiomed.2011.04.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 02/23/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
Abstract
Inactivation of manganese superoxide dismutase (MnSOD), a mitochondrial antioxidant, has been associated with renal disorders and often results in detrimental downstream events that are mechanistically not clear. Development of an animal model that exhibits kidney-specific deficiency of MnSOD would be extremely beneficial in exploring the downstream events that occur following MnSOD inactivation. Using Cre-Lox recombination technology, kidney-specific MnSOD deficient mice (both 100% and 50%) were generated that exhibited low expression of MnSOD in discrete renal cell types and reduced enzymatic activity within the kidney. These kidney-specific 100% KO mice possessed a normal life-span, although it was interesting that the mice were smaller. Consistent with the important role in scavenging superoxide radicals, the kidney-specific KO mice showed a significant increase in oxidative stress (tyrosine nitration) in a gene-dose dependent manner. In addition, loss of MnSOD resulted in mild renal damage (tubular dilation and cell swelling). Hence, this novel mouse model will aid in determining the specific role (local and/or systemic) governed by MnSOD within certain kidney cells. Moreover, these mice will serve as a powerful tool to explore molecular mechanisms that occur downstream of MnSOD inactivation in renal disorders or possibly in other pathologies that rely on normal renal function.
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Affiliation(s)
- Nirmala Parajuli
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Akira Marine
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Sloane Simmons
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Hamida Saba
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Tanecia Mitchell
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Takahiko Shimizu
- Molecular Gerontology, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Takuji Shirasawa
- Molecular Gerontology, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
- Aging Control Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Lee Ann MacMillan-Crow
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Corresponding Author: Lee Ann MacMillan-Crow, Ph.D., University of Arkansas for Medical Sciences, 325 Jack Stephens Drive, Biomedical Bldg. I 323D, Little Rock, AR 72205, Tel.: 501-686-5289; Fax: 501-686-8970,
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Case AJ, McGill JL, Tygrett LT, Shirasawa T, Spitz DR, Waldschmidt TJ, Legge KL, Domann FE. Elevated mitochondrial superoxide disrupts normal T cell development, impairing adaptive immune responses to an influenza challenge. Free Radic Biol Med 2011; 50:448-58. [PMID: 21130157 PMCID: PMC3026081 DOI: 10.1016/j.freeradbiomed.2010.11.025] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 11/12/2010] [Accepted: 11/22/2010] [Indexed: 01/23/2023]
Abstract
Reactive oxygen species (ROS) are critical in a broad spectrum of cellular processes including signaling, tumor progression, and innate immunity. The essential nature of ROS signaling in the immune systems of Drosophila and zebrafish has been demonstrated; however, the role of ROS, if any, in mammalian adaptive immune system development and function remains unknown. This work provides the first clear demonstration that thymus-specific elevation of mitochondrial superoxide (O(2)(•-)) disrupts normal T cell development and impairs the function of the mammalian adaptive immune system. To assess the effect of elevated mitochondrial superoxide in the developing thymus, we used a T-cell-specific knockout of manganese superoxide dismutase (i.e., SOD2) and have thus established a murine model to examine the role of mitochondrial superoxide in T cell development. Conditional loss of SOD2 led to increased superoxide, apoptosis, and developmental defects in the T cell population, resulting in immunodeficiency and susceptibility to the influenza A virus H1N1. This phenotype was rescued with mitochondrially targeted superoxide-scavenging drugs. These findings demonstrate that loss of regulated levels of mitochondrial superoxide lead to aberrant T cell development and function, and further suggest that manipulations of mitochondrial superoxide levels may significantly alter clinical outcomes resulting from viral infection.
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Affiliation(s)
- Adam J. Case
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Jodi L. McGill
- Department of Pathology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Lorraine T. Tygrett
- Department of Pathology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Takuji Shirasawa
- Juntendo University, Department of Aging Control Medicine, Hongo 3-3-10-201, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Douglas R. Spitz
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Thomas J. Waldschmidt
- Department of Pathology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Kevin L. Legge
- Department of Pathology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Frederick E. Domann
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa 52242, USA
- Corresponding Author: Frederick E. Domann, PhD, B180 Medical Laboratories, Free Radical and Radiation Biology Program, Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa 52240, Phone: 319-335-8019, Fax: 319-335-8039,
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Abstract
Axons depend critically on axonal transport both for supplying materials and for communicating with cell bodies. This chapter looks at each activity, asking what aspects are essential for axon survival. Axonal transport declines in neurodegenerative disorders, such as Alzheimer's disease, amyotrophic lateral sclerosis, and multiple sclerosis, and in normal ageing, but whether all cargoes are equally affected and what limits axon survival remains unclear. Cargoes can be differentially blocked in some disorders, either individually or in groups. Each missing protein cargo results in localized loss-of-function that can be partially modeled by disrupting the corresponding gene, sometimes with surprising results. The axonal response to losing specific proteins also depends on the rates of protein turnover and on whether the protein can be locally synthesized. Among cargoes with important axonal roles are components of the PI3 kinase, Mek/Erk, and Jnk signaling pathways, which help to communicate with cell bodies and to regulate axonal transport itself. Bidirectional trafficking of Bdnf, NT-3, and other neurotrophic factors contribute to intra- and intercellular signaling, affecting the axon's cellular environment and survival. Finally, several adhesion molecules and gangliosides are key determinants of axon survival, probably by mediating axon-glia interactions. Thus, failure of long-distance intracellular transport can deprive axons of one, few, or many cargoes. This can lead to axon degeneration either directly, through the absence of essential axonal proteins, or indirectly, through failures in communication with cell bodies and nonneuronal cells.
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Fischer LR, Igoudjil A, Magrané J, Li Y, Hansen JM, Manfredi G, Glass JD. SOD1 targeted to the mitochondrial intermembrane space prevents motor neuropathy in the Sod1 knockout mouse. ACTA ACUST UNITED AC 2010; 134:196-209. [PMID: 21078595 DOI: 10.1093/brain/awq314] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Motor axon degeneration is a critical but poorly understood event leading to weakness and muscle atrophy in motor neuron diseases. Here, we investigated oxidative stress-mediated axonal degeneration in mice lacking the antioxidant enzyme, Cu,Zn superoxide dismutase (SOD1). We demonstrate a progressive motor axonopathy in these mice and show that Sod1(-/-) primary motor neurons extend short axons in vitro with reduced mitochondrial density. Sod1(-/-) neurons also show oxidation of mitochondrial--but not cytosolic--thioredoxin, suggesting that loss of SOD1 causes preferential oxidative stress in mitochondria, a primary source of superoxide in cells. SOD1 is widely regarded as the cytosolic isoform of superoxide dismutase, but is also found in the mitochondrial intermembrane space. The functional significance of SOD1 in the intermembrane space is unknown. We used a transgenic approach to express SOD1 exclusively in the intermembrane space and found that mitochondrial SOD1 is sufficient to prevent biochemical and morphological defects in the Sod1(-/-) model, and to rescue the motor phenotype of these mice when followed to 12 months of age. These results suggest that SOD1 in the mitochondrial intermembrane space is fundamental for motor axon maintenance, and implicate oxidative damage initiated at mitochondrial sites in the pathogenesis of motor axon degeneration.
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Affiliation(s)
- Lindsey R Fischer
- Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
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Haramati S, Chapnik E, Sztainberg Y, Eilam R, Zwang R, Gershoni N, McGlinn E, Heiser PW, Wills AM, Wirguin I, Rubin LL, Misawa H, Tabin CJ, Brown R, Chen A, Hornstein E. miRNA malfunction causes spinal motor neuron disease. Proc Natl Acad Sci U S A 2010; 107:13111-6. [PMID: 20616011 PMCID: PMC2919953 DOI: 10.1073/pnas.1006151107] [Citation(s) in RCA: 242] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Defective RNA metabolism is an emerging mechanism involved in ALS pathogenesis and possibly in other neurodegenerative disorders. Here, we show that microRNA (miRNA) activity is essential for long-term survival of postmitotic spinal motor neurons (SMNs) in vivo. Thus, mice that do not process miRNA in SMNs exhibit hallmarks of spinal muscular atrophy (SMA), including sclerosis of the spinal cord ventral horns, aberrant end plate architecture, and myofiber atrophy with signs of denervation. Furthermore, a neurofilament heavy subunit previously implicated in motor neuron degeneration is specifically up-regulated in miRNA-deficient SMNs. We demonstrate that the heavy neurofilament subunit is a target of miR-9, a miRNA that is specifically down-regulated in a genetic model of SMA. These data provide evidence for miRNA function in SMN diseases and emphasize the potential role of miR-9-based regulatory mechanisms in adult neurons and neurodegenerative states.
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Affiliation(s)
| | | | - Yehezkel Sztainberg
- Departments of Neurobiology and
- The Leslie and Susan Gonda (Goldschmied) Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Raya Eilam
- Veterinary Resources, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | | | - Edwina McGlinn
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Patrick W. Heiser
- Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138
| | - Anne-Marie Wills
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114
| | - Itzhak Wirguin
- Department of Neurology, Soroka Medical Center, Ben-Gurion University of the Negev, Beer-Sheva 91352 , Israel
| | - Lee L. Rubin
- Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138
| | - Hidemi Misawa
- Department of Pharmacology, Keio University Faculty of Pharmacy, Tokyo 160-8582, Japan; and
| | | | - Robert Brown
- Department of Neurology, University of Massachusetts School of Medicine, Worcester, MA 01655
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Model mice for tissue-specific deletion of the manganese superoxide dismutase gene. Geriatr Gerontol Int 2010; 10 Suppl 1:S70-9. [DOI: 10.1111/j.1447-0594.2010.00604.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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SHIMIZU T, SHIRASAWA T. Anti-aging Research Using Mn-SOD Conditional Knockout Mice. YAKUGAKU ZASSHI 2010; 130:19-24. [DOI: 10.1248/yakushi.130.19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Takahiko SHIMIZU
- Molecular Gerontology, Tokyo Metropolitan Institute of Gerontology
| | - Takuji SHIRASAWA
- Department Ageing Control Medicine, Juntendo University Graduate School of Medicine
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Kawakami S, Matsuda A, Sunagawa T, Noda Y, Kaneko T, Tahara S, Hiraumi Y, Adachi S, Matsui H, Ando K, Fujita T, Maruyama N, Shirasawa T, Shimizu T. Antioxidant, EUK-8, prevents murine dilated cardiomyopathy. Circ J 2009; 73:2125-34. [PMID: 19749480 DOI: 10.1253/circj.cj-09-0204] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Mice lacking manganese-superoxide dismutase (Mn-SOD) activity exhibit the typical pathology of dilated cardiomyopathy (DCM). In the present study, presymptomatic and symptomatic mutant mice were treated with the SOD/catalase mimetic, EUK-8. METHODS AND RESULTS Presymptomatic heart/muscle-specific Mn-SOD-deficient mice (H/M-Sod2(-/-)) were treated with EUK-8 (30 mg x kg(-1) . day(-1)) for 4 weeks, and then cardiac function and the reactive oxygen species (ROS) production in their heart mitochondria were assessed. EUK-8 treatment suppressed the progression of cardiac dysfunction and diminished ROS production and oxidative damage. Furthermore, EUK-8 treatment effectively reversed the cardiac dilatation and dysfunction observed in symptomatic H/M-Sod2(-/-) mice. Interestingly, EUK-8 treatment repaired a molecular defect in connexin43. CONCLUSIONS EUK-8 treatment can prevent and cure murine DCM, so SOD/catalase mimetic treatment is proposed as a potential therapy for DCM.
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Affiliation(s)
- Satoru Kawakami
- Department of Research and Development, Anti-Aging Science, Co Ltd, United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
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41
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Heterogeneity of nervous system mitochondria: Location, location, location! Exp Neurol 2009; 218:293-307. [DOI: 10.1016/j.expneurol.2009.05.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 04/30/2009] [Accepted: 05/08/2009] [Indexed: 01/03/2023]
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42
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Vempati UD, Torraco A, Moraes CT. Mouse models of oxidative phosphorylation dysfunction and disease. Methods 2008; 46:241-7. [PMID: 18848991 PMCID: PMC2652743 DOI: 10.1016/j.ymeth.2008.09.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 08/28/2008] [Accepted: 09/12/2008] [Indexed: 11/23/2022] Open
Abstract
Oxidative phosphorylation (OXPHOS) deficiency results in a number of human diseases, affecting at least one in 5000 of the general population. Altering the function of genes by mutations are central to our understanding their function. Prior to the development of gene targeting, this approach was limited to rare spontaneous mutations that resulted in a phenotype. Since its discovery, targeted mutagenesis of the mouse germline has proved to be a powerful approach to understand the in vivo function of genes. Gene targeting has yielded remarkable understanding of the role of several gene products in the OXPHOS system. We provide a "tool box" of mouse models with OXPHOS defects that could be used to answer diverse scientific questions.
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Affiliation(s)
| | | | - Carlos T. Moraes
- Department of Neurology, University of Miami, USA
- Department of Cell Biology & Anatomy, University of Miami, USA
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43
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Sharma S, Sud N, Wiseman DA, Carter AL, Kumar S, Hou Y, Rau T, Wilham J, Harmon C, Oishi P, Fineman JR, Black SM. Altered carnitine homeostasis is associated with decreased mitochondrial function and altered nitric oxide signaling in lambs with pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 2007; 294:L46-56. [PMID: 18024721 DOI: 10.1152/ajplung.00247.2007] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Utilizing aortopulmonary vascular graft placement in the fetal lamb, we have developed a model (shunt) of pulmonary hypertension that mimics congenital heart disease with increased pulmonary blood flow. Our previous studies have identified a progressive development of endothelial dysfunction in shunt lambs that is dependent, at least in part, on decreased nitric oxide (NO) signaling. The purpose of this study was to evaluate the possible role of a disruption in carnitine metabolism in shunt lambs and to determine the effect on NO signaling. Our data indicate that at 2 wk of age, shunt lambs have significantly reduced expression (P < 0.05) of the key enzymes in carnitine metabolism: carnitine palmitoyltransferases 1 and 2 as well as carnitine acetyltransferase (CrAT). In addition, we found that CrAT activity was inhibited due to increased nitration. Furthermore, free carnitine levels were significantly decreased whereas acylcarnitine levels were significantly higher in shunt lambs (P < 0.05). We also found that alterations in carnitine metabolism resulted in mitochondrial dysfunction, since shunt lambs had significantly decreased pyruvate, increased lactate, and a reduced pyruvate/lactate ratio. In pulmonary arterial endothelial cells cultured from juvenile lambs, we found that mild uncoupling of the mitochondria led to a decrease in cellular ATP levels and a reduction in both endothelial NO synthase-heat shock protein 90 (eNOS-HSP90) interactions and NO signaling. Similarly, in shunt lambs we found a loss of eNOS-HSP90 interactions that correlated with a progressive decrease in NO signaling. Our data suggest that mitochondrial dysfunction may play a role in the development of endothelial dysfunction and pulmonary hypertension and increased pulmonary blood flow.
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Affiliation(s)
- Shruti Sharma
- Program in Pulmonary Disease, Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, USA
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