Depletion of Reduced Glutathione Enhances Motor Neuron Degeneration in vitro and in vivo; PY2007; USA (美國);_WJD_2021-0320_V001R01_IR94_IR95_RvD20210320_

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2021-03-20
Depletion of Reduced Glutathione Enhances Motor Neuron Degeneration in vitro and in vivo; PY2007; USA (美國);_WJD_2021-0320_V001R01_IR94_IR95_RvD20210320_

Source (資訊來源):
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1944995/
Info cited on 2021-03-20-WD6 (資訊引用於 中華民國110年西元2021年3月20日) by 湯偉晉 (WeiJin Tang)
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Source (資訊來源):
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1944995/pdf/nihms17516.pdf
Info cited on 2021-03-20-WD6 (資訊引用於 中華民國110年西元2021年3月20日) by 湯偉晉 (WeiJin Tang)
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Neuroscience. Author manuscript; available in PMC 2007 Aug 10.

Neuroscience. 2007 Feb 9; 144(3): 991–1003.
Published online 2006 Dec 5. doi: 10.1016/j.neuroscience.2006.09.064
PMCID: PMC1944995
NIHMSID: NIHMS17516
PMID: 17150307

Depletion of Reduced Glutathione Enhances Motor Neuron Degeneration in vitro and in vivo

Liying Chi,1 Yan Ke,2 Chun Luo,1 David Gozal,2 and Rugao Liu1,*
Author information Copyright and License information Disclaimer
1 Department of Anatomy and Cell Biology, University of North Dakota School of Medicine, 501 N. Columbia Road, Grand Forks, ND 58202
2 Kosair Children Hospital Research Institute, Department of Pediatrics, University of Louisville, 570 S. Preston St., Suite 204, Louisville, KY 40202
*Corresponding author: Rugao Liu, Ph.D., Associate Professor, Department of Anatomy and Cell Biology, University of North Dakota School of Medicine, 501 N. Columbia Road, Grand Forks, ND 58202, Telephone: (701)-777-2559, Fax: (701)-777-2477, E-mail: ude.kadon.enicidem@uilr
Section Editor: Dr. Werner Sieghart
The publisher's final edited version of this article is available at Neuroscience

Abstract (摘要)
The mechanism of selective and age-dependent motor neuron degeneration in human amyotrophic lateral sclerosis (ALS) has not been defined and the role of glutathione (GSH) in association with motor neuron death remains largely unknown. A motor neuron-like cell culture system and a transgenic mouse model were used to study the effect of cellular GSH alteration on motor neuron cell death. Exposure of NSC34 motor neuron-like cells to Ethacrynic Acid (EA) or L-Buthionine Sulfoximine (BSO) dramatically reduced the cellular GSH levels, and was accompanied by increased production of reactive oxygen species (ROS) measured by the DCF fluorescent oxidation assay. In addition, GSH depletion enhanced oxidative stress markers, AP-1 transcriptional activation, c-Jun, c-Fos and HO-1 expression in NSC34 cells analyzed by a luciferase reporter, western blotting and quantitative PCR assays respectively. Furthermore, depletion of GSH decreased mitochondrial function, facilitated apoptosis inducing factor (AIF) translocation, cytochrome c release, and caspase 3 activation, and consequently led to motor neuron-like cell apoptosis. In an ALS-like transgenic mouse model overexpressing mutant G93A-SOD1 gene, we showed that the reduction of GSH in the spinal cord and motor neuron cells is correlated with AIF translocation, caspase 3 activation, and motor neuron degeneration during ALS-like disease onset and progression. Taken together, the in vitro and in vivo data presented in the current report demonstrated that decreased GSH promotes multiple apoptotic pathways contributing, at least partially, to motor neuron degeneration in ALS.

Introduction (簡介)
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that primarily affects motor neurons in brain cortex, brainstem and spinal cord (Williams and Windebank, 1991). The mechanisms underlying the selective and age-dependent motor neuron degeneration remain largely unidentified, and effective therapy for ALS is not yet available. Mutations of Cu,Zn-superoxide dismutase (SOD1) gene cause motor neuron degeneration and have linked to 2–5% of ALS cases (Rosen et al., 1994; Rosen et al., 1993). Several potential mechanisms of motor neuron degeneration in ALS have been proposed based on clinical studies, animal model and cell culture system analyses. Increased oxidative stress, glutamate toxicity, protein aggregation and Cu/Zn cytotoxicity have all been suggested to contribute to motor neuron degeneration (Cleveland and Rothstein, 2001; Li et al., 2003; Liu et al., 2002; Shaw et al., 2001; Shaw and Eggett, 2000; Shibata et al., 2000). Of these, increased oxidative stress appears to be an early and sustained event in association with motor neuron death in ALS (Bogdanov et al., 1998; Liu et al., 1998), although the specific mechanism leading to oxidative damage on motor neurons remains to be defined. Oxidative stress can be potentially increased by enhanced production of reactive oxygen species (ROS), decreased antioxidants/antioxidant enzyme systems or a combination of both. Glutathione (GSH), a tripeptide of γ-glutamylcysteinylglycine, is one of the most abundant antioxidants in cells and tissues. Reduction of GSH enhances ROS production and promotes oxidative damage. A previous study demonstrated increased GSH binding in the spinal cords of patients with sporadic ALS (Lanius et al., 1993), suggesting that GSH may play a role in the pathogenesis of ALS. In a cell culture model, it has been shown that expression of mutant SOD1 gene decreased cellular levels of GSH, suggesting the reduction in GSH bioavailability may participate in the mutant SOD1-mediated motor neuron degeneration (Lee et al., 2001).

GSH is the most abundant and effective scavenger against ROS directly in mammalian cells. In addition, GSH is also a key substrate for antioxidant enzymes that detoxify hydrogen peroxide and lipid peroxide catalyzed by glutathione peroxidase. More recently, it has been demonstrated that GSH participates in cellular signal transduction pathways, and modulates ionotropic receptor function (Bains and Shaw, 1997; Grima et al., 2003; Janaky et al., 1993). GSH is synthesized in two sequential enzymatic reactions catalyzed by γ-glutamylcysteine synthetase (γ-GCS) and GSH synthetase. L-Buthionine Sulfoximine (BSO) is a selective inhibitor (選擇性的抑制劑) of γ-GCS. Exposure of cells to BSO inhibits GSH synthesis and decreases intracellular levels of GSH. Thus, BSO has been frequently used to study the role of GSH in association with oxidative stress-induced neuronal cell and other cell death. On the other hand, because BSO does not completely deplete mitochondrial and nuclear GSH, other agents, including ethacrynic acid (EA) have been used to effectively deplete cellular, mitochondrial and nuclear GSH (Keelan et al., 2001; Rizzardini et al., 2003). Alterations in GSH synthesis, or in GSH pools, have been associated with neuronal cell death and mimic a variety of human neurodegenerative diseases, such as Parkinson’s disease (Bharath et al., 2002; Jha et al., 2000; Mytilineou et al., 2002; Paik et al., 2003), Alzheimer’s disease (Adams, Jr. et al., 1991; Cecchi et al., 1999; Janaky et al., 1999; Karelson et al., 2002) and Schizophrenia (Do et al., 2000). Nevertheless, the role of GSH in the pathogenesis of motor neuron degeneration in ALS remained largely undefined. To this end, we have focused on a cell culture system and an ALS-like transgenic mouse model to study the effect of GSH on motor neuron cell death. We showed that reduction of intracellular GSH increases oxidative stress, decreases mitochondrial function, activates multiple apoptotic pathways, and consequently contributes to motor neuron degeneration in vitro and in vivo.

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