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Berger ND, Brownlee PM, Chen MJ, Morrison H, Osz K, Ploquin NP, Chan JA, Goodarzi AA. High replication stress and limited Rad51-mediated DNA repair capacity, but not oxidative stress, underlie oligodendrocyte precursor cell radiosensitivity. NAR Cancer 2022; 4:zcac012. [PMID: 35425901 PMCID: PMC9004414 DOI: 10.1093/narcan/zcac012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 02/15/2022] [Accepted: 03/21/2022] [Indexed: 12/29/2022] Open
Abstract
Abstract
Cranial irradiation is part of the standard of care for treating pediatric brain tumors. However, ionizing radiation can trigger serious long-term neurologic sequelae, including oligodendrocyte and brain white matter loss enabling neurocognitive decline in children surviving brain cancer. Oxidative stress-mediated oligodendrocyte precursor cell (OPC) radiosensitivity has been proposed as a possible explanation for this. Here, however, we demonstrate that antioxidants fail to improve OPC viability after irradiation, despite suppressing oxidative stress, suggesting an alternative etiology for OPC radiosensitivity. Using systematic approaches, we find that OPCs have higher irradiation-induced and endogenous γH2AX foci compared to neural stem cells, neurons, astrocytes and mature oligodendrocytes, and these correlate with replication-associated DNA double strand breakage. Furthermore, OPCs are reliant upon ATR kinase and Mre11 nuclease-dependent processes for viability, are more sensitive to drugs increasing replication fork collapse, and display synthetic lethality with PARP inhibitors after irradiation. This suggests an insufficiency for homology-mediated DNA repair in OPCs—a model that is supported by evidence of normal RPA but reduced RAD51 filament formation at resected lesions in irradiated OPCs. We therefore propose a DNA repair-centric mechanism of OPC radiosensitivity, involving chronically-elevated replication stress combined with ‘bottlenecks’ in RAD51-dependent DNA repair that together reduce radiation resilience.
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Affiliation(s)
- N Daniel Berger
- Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Peter M Brownlee
- Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada
| | - Myra J Chen
- Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Hali Morrison
- Department of Oncology and Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - Katalin Osz
- Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
| | - Nicolas P Ploquin
- Department of Oncology and Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - Jennifer A Chan
- Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Aaron A Goodarzi
- Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Department of Oncology and Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
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2
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Bamm VV, Henein MEL, Sproul SLJ, Lanthier DK, Harauz G. Potential role of ferric hemoglobin in MS pathogenesis: Effects of oxidative stress and extracellular methemoglobin or its degradation products on myelin components. Free Radic Biol Med 2017; 112:494-503. [PMID: 28863941 DOI: 10.1016/j.freeradbiomed.2017.08.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 08/22/2017] [Accepted: 08/28/2017] [Indexed: 10/19/2022]
Abstract
There is a well-documented relationship between cerebral vasculature and multiple sclerosis (MS) lesions: abnormal accumulations of iron have been found in the walls of the dilated veins in cerebral MS plaques. The source of this iron is unknown, but could be related to the recognized phenomenon of capillary and venous hemorrhages leading to blood extravasation. In turn, hemorrhaging leading to hemolysis results in extracellular release of hemoglobin, a reactive molecule that could induce local oxidative stress, inflammation, and tissue damage. Our previous studies with a reduced form of hemoglobin (oxyHb) have demonstrated its ability to cause extensive lipid and protein oxidation in vitro, which would result in membrane destabilization. Here, we investigated in further detail the mechanism by which the more abundant oxidized form of extracellular hemoglobin (metHb), and dissociated hemin, cause direct oxidative damage to myelin components, specifically membrane-mimetic lipid vesicles and myelin basic protein (MBP), a highly-abundant protein in the CNS. Oxidation of lipids was assessed by the formation of conjugated diene/triene and malondialdehyde, and oxidation of MBP was demonstrated by the bityrosine formation and by the change in protein mass. Our results show that metHb causes oxidative damage to MBP and myelin lipids, partly by transferring its hemin moiety to protein and lipid, but mostly as an intact protein possibly via formation of a ferryl radical. These results elucidating the mechanism of extracellular hemoglobin-induced oxidative damage to myelin components support the need for further research into vascular pathology in MS pathogenesis, to gain insight into the role of iron deposits and/or in stimulation of different comorbidities associated with the disease.
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Affiliation(s)
- Vladimir V Bamm
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1
| | - Mary E L Henein
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1; Department of Human Genetics, McGill University, Montréal, Québec, Canada
| | - Shannon L J Sproul
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1; Department of Cell and Developmental Biology, University of British Columbia, Vancouver, BC, Canada
| | - Danielle K Lanthier
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1
| | - George Harauz
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1.
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Murphy NP, Lampe KJ. Fabricating PLGA microparticles with high loads of the small molecule antioxidant N-acetylcysteine that rescue oligodendrocyte progenitor cells from oxidative stress. Biotechnol Bioeng 2017; 115:246-256. [PMID: 28872660 DOI: 10.1002/bit.26443] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/12/2017] [Accepted: 08/28/2017] [Indexed: 01/02/2023]
Abstract
Reactive oxygen species (ROS), encompassing all oxygen radical or non-radical oxidizing agents, play key roles in disease progression. Controlled delivery of antioxidants is therapeutically relevant in such oxidant-stressed environments. Encapsulating small hydrophilic molecules into hydrophobic polymer microparticles via traditional emulsion methods has long been a challenge due to rapid mass transport of small molecules out of particle pores. We have developed a simple alteration to the existing water-in-oil-in-water (W/O/W) drug encapsulation method that dramatically improves loading efficiency: doping external water phases with drug to mitigate drug diffusion out of the particle during fabrication. PLGA microparticles with diameters ranging from 0.6 to 0.9 micrometers were fabricated, encapsulating high loads of 0.6-0.9 µm diameter PLGA microparticles were fabricated, encapsulating high loads of the antioxidant N-acetylcysteine (NAC), and released active, ROS-scavenging NAC for up to 5 weeks. Encapsulation efficiencies, normalized to the theoretical load of traditional encapsulation without doping, ranged from 96% to 400%, indicating that NAC-loaded external water phases not only prevented drug loss due to diffusion, but also doped the particles with additional drug. Antioxidant-doped particles positively affected the metabolism of oligodendrocyte progenitor cells (OPCs) under H2 O2 -mediated oxidative stress when administered both before (protection) or after (rescue) injury. Antioxidant doped particles improved outcomes of OPCs experiencing multiple doses of H2 O2 by increasing the intracellular glutathione content and preserving cellular viability relative to the injury control. Furthermore, antioxidant-doped particles preserve cell number, number of process extensions, cytoskeletal morphology, and nuclear size of H2 O2 -stressed OPCs relative to the injury control. These NAC-doped particles have the potential to provide temporally-controlled antioxidant therapy in neurodegenerative disorders such as multiple sclerosis (MS) that are characterized by continuous oxidative stress.
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Affiliation(s)
- Nicholas P Murphy
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia
| | - Kyle J Lampe
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia
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O'Sullivan SA, Velasco-Estevez M, Dev KK. Demyelination induced by oxidative stress is regulated by sphingosine 1-phosphate receptors. Glia 2017; 65:1119-1136. [PMID: 28375547 DOI: 10.1002/glia.23148] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 03/02/2017] [Accepted: 03/20/2017] [Indexed: 01/14/2023]
Abstract
Oxidative stress is a pathological condition defined as an imbalance between production and removal of reactive oxygen species. This process causes structural cell damage, disrupts DNA repair and induces mitochondrial dysfunction. Many in vitro studies have used direct bolus application of H2 O2 to investigate the role of oxidative stress in cell culture. In this study, using mouse organotypic cerebellar slice cultures, the effects of H2 O2 -induced oxidative stress on myelination state were examined, using bolus concentrations of H2 O2 (0.1-1 mM) and low-continuous H2 O2 (∼20 μM) generated from glucose oxidase and catalase (GOX-CAT). Using these models, the potential therapeutic effects of pFTY720, an oral therapy used in multiple sclerosis, was also examined. We found bolus treatment of H2 O2 (0.5 mM) and, for the first time, low-continuous H2 O2 (GOX-CAT) to induce demyelination in organotypic slices. Both bolus H2 O2 and GOX-CAT treatments significantly decreased vimentin expression in these slice cultures as well as increased cell death in isolated astrocyte cultures. Importantly, pre-treatment with pFTY720 significantly attenuated both bolus H2 O2 and GOX-CAT-induced demyelination and the GOX-CAT-induced decrease in vimentin in cerebellar slices, without altering levels of the proinflammatory cytokines such as IL-6 and CX3CL1. We also observed increased SMI-32 immunoreactivity in the white matter tract induced by GOX-CAT indicating axonal damage, which was remarkably attenuated by pFTY720. Taken together, this data establishes a novel GOX-CAT model of demyelination and demonstrates that pFTY720 can act independently of inflammatory cytokines to attenuate decreases in vimentin, as well as axonal damage and demyelination induced by oxidative stress.
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Affiliation(s)
- Sinead A O'Sullivan
- Drug Development, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | | | - Kumlesh K Dev
- Drug Development, School of Medicine, Trinity College Dublin, Dublin, Ireland
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Passiflora manicata (Juss.) aqueous leaf extract protects against reactive oxygen species and protein glycation in vitro and ex vivo models. Food Chem Toxicol 2013; 60:45-51. [DOI: 10.1016/j.fct.2013.07.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 11/17/2022]
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Kallenborn-Gerhardt W, Schröder K, Geisslinger G, Schmidtko A. NOXious signaling in pain processing. Pharmacol Ther 2012; 137:309-17. [PMID: 23146925 DOI: 10.1016/j.pharmthera.2012.11.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 10/26/2012] [Indexed: 12/14/2022]
Abstract
Chronic pain affects millions of people and often causes major health problems. Accumulating evidence indicates that the production of reactive oxygen species (ROS), such as superoxide anion or hydrogen peroxide, is increased in the nociceptive system during chronic inflammatory and neuropathic pain, and that ROS can act as specific signaling molecules in pain processing. Reduction of ROS levels by administration of scavengers or antioxidant compounds attenuated the nociceptive behavior in various animal models of chronic pain. However, the sources of increased ROS production during chronic pain and the role of ROS in pain processing are poorly understood. Current work revealed pain-relevant functions of the Nox family of NADPH oxidases, a group of electron-transporting transmembrane enzymes whose sole function seems to be the generation of ROS. In particular, significant expression of the Nox family members Nox1, Nox2, and Nox4 in various cells of the nociceptive system has been discovered. Studies using knockout mice suggest that these Nox enzymes specifically contribute to distinct signaling pathways in chronic inflammatory and/or neuropathic pain states. Accordingly, targeting Nox1, Nox2, and Nox4 could be a novel strategy for the treatment of chronic pain. Currently selective inhibitors of Nox enzymes are being developed. Here, we introduce the distinct roles of Nox enzymes in pain processing, we summarize recent findings in the understanding of ROS-dependent signaling pathways in the nociceptive system, and we discuss potential analgesic properties of currently available Nox inhibitors.
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Affiliation(s)
- Wiebke Kallenborn-Gerhardt
- Pharmazentrum Frankfurt/ZAFES, Institut für Klinische Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität, 60590 Frankfurt am Main, Germany
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Abstract
Reactive oxygen species (ROS) contribute to sensitization of pain pathways during neuropathic pain, but little is known about the primary sources of ROS production and how ROS mediate pain sensitization. Here, we show that the NADPH oxidase isoform Nox4, a major ROS source in somatic cells, is expressed in a subset of nonpeptidergic nociceptors and myelinated dorsal root ganglia neurons. Mice lacking Nox4 demonstrated a substantially reduced late-phase neuropathic pain behavior after peripheral nerve injury. The loss of Nox4 markedly attenuated injury-induced ROS production and dysmyelination processes of peripheral nerves. Moreover, persisting neuropathic pain behavior was inhibited after tamoxifen-induced deletion of Nox4 in adult transgenic mice. Our results suggest that Nox4 essentially contributes to nociceptive processing in neuropathic pain states. Accordingly, inhibition of Nox4 may provide a novel therapeutic modality for the treatment of neuropathic pain.
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Takamiya M, Miyamoto Y, Yamashita T, Deguchi K, Ohta Y, Abe K. Strong neuroprotection with a novel platinum nanoparticle against ischemic stroke- and tissue plasminogen activator-related brain damages in mice. Neuroscience 2012; 221:47-55. [DOI: 10.1016/j.neuroscience.2012.06.060] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/24/2012] [Accepted: 06/25/2012] [Indexed: 12/20/2022]
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Takamiya M, Miyamoto Y, Yamashita T, Deguchi K, Ohta Y, Ikeda Y, Matsuura T, Abe K. Neurological and pathological improvements of cerebral infarction in mice with platinum nanoparticles. J Neurosci Res 2011; 89:1125-33. [DOI: 10.1002/jnr.22622] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 01/07/2011] [Accepted: 01/15/2011] [Indexed: 11/06/2022]
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Shikonin protects mouse brain against cerebral ischemia/reperfusion injury through its antioxidant activity. Eur J Pharmacol 2010; 643:211-7. [DOI: 10.1016/j.ejphar.2010.06.027] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Revised: 05/20/2010] [Accepted: 06/16/2010] [Indexed: 01/31/2023]
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Brand A, Bauer NG, Hallott A, Goldbaum O, Ghebremeskel K, Reifen R, Richter-Landsberg C. Membrane lipid modification by polyunsaturated fatty acids sensitizes oligodendroglial OLN-93 cells against oxidative stress and promotes up-regulation of heme oxygenase-1 (HSP32). J Neurochem 2010; 113:465-76. [DOI: 10.1111/j.1471-4159.2010.06611.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Reduction of cerebral infarction in rats by biliverdin associated with amelioration of oxidative stress. Brain Res 2007; 1188:1-8. [PMID: 18035335 DOI: 10.1016/j.brainres.2007.07.104] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 07/18/2007] [Accepted: 07/20/2007] [Indexed: 11/23/2022]
Abstract
Biliverdin (BV), one of the byproducts of heme catalysis through heme oxygenase (HO) system, is a scavenger of reactive oxygen species (ROS). We hypothesized that BV treatment could protect rat brain cells from oxidative injuries via its anti-oxidant efficacies. Cerebral infarction was induced by transient middle cerebral artery occlusion (tMCAO) for 90 min, followed by reperfusion. BV or vehicle was administered intraperitoneally immediately after reperfusion. The size of the cerebral infarction 2 days after tMCAO was evaluated by 2,3,5-triphenyltetrazolium chloride (TTC) stain. Superoxide generation 4 h after tMCAO was determined by detection of oxidized hydroethidine. In addition, the oxidative impairment of neurons were immunohistochemically assessed by stain for lipid peroxidation with 4-hydroxy-2-nonenal (4-HNE) and damaged DNA with 8-hydroxy-2'-deoxyguanosine (8-OHdG). BV treatment significantly reduced infarct volume of the cerebral cortices associated with less superoxide production and decreased oxidative injuries of brain cells. The present study demonstrated that treatment with BV ameliorated the oxidative injuries on neurons and decreased brain infarct size in rat tMCAO model.
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