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Konopka A, Atkin JD. The Role of DNA Damage in Neural Plasticity in Physiology and Neurodegeneration. Front Cell Neurosci 2022; 16:836885. [PMID: 35813507 PMCID: PMC9259845 DOI: 10.3389/fncel.2022.836885] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 05/09/2022] [Indexed: 12/15/2022] Open
Abstract
Damage to DNA is generally considered to be a harmful process associated with aging and aging-related disorders such as neurodegenerative diseases that involve the selective death of specific groups of neurons. However, recent studies have provided evidence that DNA damage and its subsequent repair are important processes in the physiology and normal function of neurons. Neurons are unique cells that form new neural connections throughout life by growth and re-organisation in response to various stimuli. This “plasticity” is essential for cognitive processes such as learning and memory as well as brain development, sensorial training, and recovery from brain lesions. Interestingly, recent evidence has suggested that the formation of double strand breaks (DSBs) in DNA, the most toxic form of damage, is a physiological process that modifies gene expression during normal brain activity. Together with subsequent DNA repair, this is thought to underlie neural plasticity and thus control neuronal function. Interestingly, neurodegenerative diseases such as Alzheimer’s disease, amyotrophic lateral sclerosis, frontotemporal dementia, and Huntington’s disease, manifest by a decline in cognitive functions, which are governed by plasticity. This suggests that DNA damage and DNA repair processes that normally function in neural plasticity may contribute to neurodegeneration. In this review, we summarize current understanding about the relationship between DNA damage and neural plasticity in physiological conditions, as well as in the pathophysiology of neurodegenerative diseases.
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Affiliation(s)
- Anna Konopka
- Centre for Motor Neuron Disease Research, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
- *Correspondence: Anna Konopka
| | - Julie D. Atkin
- Centre for Motor Neuron Disease Research, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
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Bird CW, Barber MJ, Post HR, Jacquez B, Chavez GJ, Faturos NG, Valenzuela CF. Neonatal ethanol exposure triggers apoptosis in the murine retrosplenial cortex: Role of inhibition of NMDA receptor-driven action potential firing. Neuropharmacology 2019; 162:107837. [PMID: 31689422 DOI: 10.1016/j.neuropharm.2019.107837] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/07/2019] [Accepted: 10/30/2019] [Indexed: 02/07/2023]
Abstract
Exposure to ethanol during the last trimester equivalent of human pregnancy causes apoptotic neurodegeneration in the developing brain, an effect that is thought to be mediated, in part, by inhibition of NMDA receptors. However, NMDA receptors can rapidly adapt to the acute effects of ethanol and are ethanol resistant in some populations of developing neurons. Here, we characterized the effect of ethanol on NMDA and non-NMDA receptor-mediated synaptic transmission in the retrosplenial cortex (RSC), a brain region involved in the integration of different modalities of spatial information that is among the most sensitive regions to ethanol-induced neurodegeneration. A single 4-h exposure to ethanol vapor of 7-day-old transgenic mice that express the Venus fluorescent protein in interneurons triggered extensive apoptosis in the RSC. Slice electrophysiological recordings showed that bath-applied ethanol inhibits NMDA and non-NMDA receptor excitatory postsynaptic currents (EPSCs) in pyramidal neurons and interneurons; however, we found no evidence of acute tolerance development to this effect after the 4-h in-vivo ethanol vapor exposure. Acute bath application of ethanol reduced action potential firing evoked by synaptic stimulation to a greater extent in pyramidal neurons than interneurons. Submaximal inhibition of NMDA EPSCs, but not non-NMDA EPSCs, mimicked the acute effect of ethanol on synaptically-evoked action potential firing. These findings indicate that partial inhibition of NMDA receptors by ethanol has sizable effects on the excitability of glutamatergic and GABAergic neurons in the developing RSC, and suggest that positive allosteric modulators of these receptors could ameliorate ethanol intoxication-induced neurodegeneration during late stages of fetal development.
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Affiliation(s)
- Clark W Bird
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Megan J Barber
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Hilary R Post
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Belkis Jacquez
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Glenna J Chavez
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Nicholas G Faturos
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - C Fernando Valenzuela
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA.
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Alhowail AH, Bloemer J, Majrashi M, Pinky PD, Bhattacharya S, Yongli Z, Bhattacharya D, Eggert M, Woodie L, Buabeid MA, Johnson N, Broadwater A, Smith B, Dhanasekaran M, Arnold RD, Suppiramaniam V. Doxorubicin-induced neurotoxicity is associated with acute alterations in synaptic plasticity, apoptosis, and lipid peroxidation. Toxicol Mech Methods 2019; 29:457-466. [PMID: 31010378 DOI: 10.1080/15376516.2019.1600086] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cognitive deficits are commonly reported by patients following treatment with chemotherapeutic agents. Anthracycline-containing chemotherapy regimens are associated with cognitive impairment and reductions in neuronal connectivity in cancer survivors, and doxorubicin (Dox) is a commonly used anthracycline. Although it has been reported that Dox distribution to the central nervous system (CNS) is limited, considerable Dox concentrations are observed in the brain with co-administration of certain medications. Additionally, pro-inflammatory cytokines, which are overproduced in cancer or in response to chemotherapy, can reduce the integrity of the blood-brain barrier (BBB). Therefore, the aim of this study was to evaluate the acute neurotoxic effects of Dox on hippocampal neurons. In this study, we utilized a hippocampal cell line (H19-7/IGF-IR) along with rodent hippocampal slices to evaluate the acute neurotoxic effects of Dox. Hippocampal slices were used to measure long-term potentiation (LTP), and expression of proteins was determined by immunoblotting. Cellular assays for mitochondrial complex activity and lipid peroxidation were also utilized. We observed reduction in LTP in hippocampal slices with Dox. In addition, lipid peroxidation was increased as measured by thiobarbituric acid reactive substances content indicating oxidative stress. Caspase-3 expression was increased indicating an increased propensity for cell death. Finally, the phosphorylation of signaling molecules which modulate LTP including extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase, and Akt were increased. This data indicates that acute Dox exposure dose-dependently impairs synaptic processes associated with hippocampal neurotransmission, induces apoptosis, and increases lipid peroxidation leading to neurotoxicity.
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Affiliation(s)
- Ahmad H Alhowail
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Jenna Bloemer
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Mohammed Majrashi
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Priyanka D Pinky
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | | | - Zhang Yongli
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA.,b Tianjin Huanhu Hospital , Tianjin , PR China
| | - Dwipayan Bhattacharya
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Matthew Eggert
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Lauren Woodie
- c Department of Nutrition, Dietetics and Hospitality Management , College of Human Sciences, Auburn University , Auburn , AL , USA
| | - Manal A Buabeid
- d College of Pharmacy and Health Sciences , Ajman University , Ajman , UAE
| | - Nathaniel Johnson
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Alyssa Broadwater
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Bruce Smith
- e Department of Anatomy, Physiology and Pharmacology , College of Veterinary Medicine, Auburn University , Auburn , AL , USA
| | | | - Robert D Arnold
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
| | - Vishnu Suppiramaniam
- a Department of Drug Discovery and Development , Auburn University , Auburn , AL , USA
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Wang JG, Wang YL, Xu F, Zhao JX, Zhou SY, Yu Y, Chazot PL, Wang XF, Lu CB. Activity- and development-dependent down-regulation of TARPγ8 and GluA1 in cultured rat hippocampal neurons. Acta Pharmacol Sin 2016; 37:303-11. [PMID: 26725511 DOI: 10.1038/aps.2015.112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 10/26/2015] [Indexed: 01/16/2023] Open
Abstract
AIM Transmembrane AMPA receptor regulatory proteins (TARPs) regulate the trafficking and expression of AMPA receptors that are essential for the fast excitatory synaptic transmission and plasticity in the brain. This study aimed to investigate the activity-dependent regulation of TARPγ8 in cultured rat hippocampal neurons. METHODS Rat hippocampal neurons cultured for 7-8 DIV or 17-18 DIV were exposed to the AMPA receptor agonist AMPA at a non-toxic concentration (100 μmol/L) for 4 h. The protein levels of TARPγ8 and AMPA receptor subunits (GluA1 and GluA2) were measured using Western blotting analysis. AMPA-induced currents were recorded in the neurons using a whole-cell recording method. RESULTS Four-hour exposure to AMPA significantly decreased the protein levels of TARPγ8 and GluA1 in the neurons at 17-18 DIV, but did not change the protein level of TARPγ8 in the neurons cultured at 7-8 DIV. AMPA-induced down-regulation of TARPγ8 and GluA1 was largely blocked by the calpain inhibitor calpeptin (50 μmol/L), but not affected by the caspase inhibitor zVAD (50 μmol/L). Four-hour exposure to AMPA significantly decreased AMPA-induced currents in the neurons at 17-18 DIV, which was blocked by co-exposure to calpeptin (50 μmol/L). CONCLUSION The down-regulation of TARPγ8 and GluA1 protein levels and AMPA-induced currents in cultured rat hippocampal neurons is activity- and development-dependent, and mediated by endogenous calpain.
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Fan H, Kou J, Han D, Li P, Zhang D, Wu Q, He Q. Sensitive proteolysis assay based on the detection of a highly characteristic solid-state process. RSC Adv 2015. [DOI: 10.1039/c5ra05749c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This paper reported a sensitive proteolysis assay based on the detection of a highly characteristic solid-state process.
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Affiliation(s)
- Hua Fan
- Department of Hepatobiliary Surgery
- Beijing Chaoyang Hospital
- Capital Medical University
- Beijing
- P. R. China
| | - Jiantao Kou
- Department of Hepatobiliary Surgery
- Beijing Chaoyang Hospital
- Capital Medical University
- Beijing
- P. R. China
| | - Dongdong Han
- Department of Hepatobiliary Surgery
- Beijing Chaoyang Hospital
- Capital Medical University
- Beijing
- P. R. China
| | - Ping Li
- Department of Hepatobiliary Surgery
- Beijing Chaoyang Hospital
- Capital Medical University
- Beijing
- P. R. China
| | - Dong Zhang
- Department of Hepatobiliary Surgery
- Beijing Chaoyang Hospital
- Capital Medical University
- Beijing
- P. R. China
| | - Qiao Wu
- Department of Hepatobiliary Surgery
- Beijing Chaoyang Hospital
- Capital Medical University
- Beijing
- P. R. China
| | - Qiang He
- Department of Hepatobiliary Surgery
- Beijing Chaoyang Hospital
- Capital Medical University
- Beijing
- P. R. China
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Wu RSC, Liu KC, Tang NY, Chung HK, Ip SW, Yang JS, Chung JG. cDNA microarray analysis of the gene expression of murine leukemia RAW 264.7 cells after exposure to propofol. ENVIRONMENTAL TOXICOLOGY 2013; 28:471-478. [PMID: 21786383 DOI: 10.1002/tox.20742] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 05/10/2011] [Accepted: 05/12/2011] [Indexed: 05/31/2023]
Abstract
Propofol (2,6-diisopropylphenol) is the most extensively used general anesthetic-sedative agent and it is employed in clinical patients. It has been shown that propofol exhibits anticancer activities. However, there is no available information to address propofol-induced cytotoxic effects and affected gene expressions on murine leukemia cells. Therefore, we investigated the effects of propofol on the levels of protein and gene expression, which are associated with apoptotic death in mouse leukemia RAW 264.7 cells in vitro. Results indicated that propofol induced cell morphological changes, cytotoxicity, and induction of apoptosis in RAW 264.7 cells in vitro. Western blot analysis demonstrated that propofol promoted Fas, cytochrome c, caspase-9 and -3 active form and Bax levels, but inhibited Bcl-xl protein level which led to cell apoptosis. Furthermore, cDNA microarray assay indicated that propofol significantly enhanced 5 gene expressions (Gm4884; Gm10883; Lce1c; Lrg1; and LOC100045878) and significantly suppressed 26 gene expressions (Gm10679; Zfp617; LOC621831; LOC621831; Gm5929; Snord116; Gm3994; LOC380994; Gm5592; LOC380994; Gm4638; LOC280487; Gm4638; Tex24; A530064D06Rik; BC094916; EG668725; Gm189; Hist2h3c2; Gm8020; Snord115; Gm3079; Olfr198; Tdh; Snord115; and Olfr1249). Based on these observations, propofol-altered apoptosis-related proteins might result from induction of apoptotic gene expression and inhibition of cell growth gene expression, which finally led to apoptosis in a mouse leukemia cell line (RAW 264.7) in vitro.
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Affiliation(s)
- Rick Sai-Chuen Wu
- Department of Anesthesiology, China Medical University Hospital, Taichung 404, Taiwan
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Wu RSC, Yu CS, Liu KC, Huang HY, Ip SW, Lin JP, Chueh FS, Yang JS, Chung JG. Citosol (thiamylal sodium) triggers apoptosis and affects gene expressions of murine leukemia RAW 264.7 cells. Hum Exp Toxicol 2012; 31:771-9. [DOI: 10.1177/0960327111429137] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Citosol (thiamylal sodium) is one of generally used anesthetic–sedative agents for clinical patients, and it has not been reported to show induction of cytotoxic effects in cancer cells, especially in mice leukemia RAW 264.7 cells in vitro. In the present study, we investigated the cytotoxic effects of citosol on mice leukemic RAW 264.7 cells, including the effects on protein and gene expression levels which are determined by Western blotting and DNA microarray methods, respectively. Results indicated that citosol induced cell morphological changes, cytotoxic effect, and induction of apoptosis in RAW 264.7 cells. Western blotting analysis demonstrated that citosol promoted the levels of Fas, cytochrome c, caspase 9 and 3 active form and Bax levels, but it suppressed Bcl-xl protein level that may lead to apoptotic death in RAW 264.7 cells. Furthermore, DNA microarray assay indicated that citosol significantly promoted the expression of 5 genes (Gm4884, Gm10883, Lce1c, Lrg1, and LOC100045878) and significantly inhibited the expression of 24 genes (Gm10679, Zfp617, LOC621831, Gm5929, Snord116, Gm3994, LOC380994, Gm5592, LOC380994, LOC280487, Gm4638, Tex24, A530064D06Rik, BC094916, EG668725, Gm189, Hist2h3c2, Gm8020, Snord115, Gm3079, Olfr198, Tdh, Snord115, and Olfr1249). Based on these observations, citosol induced cell apoptosis and influenced gene expression in mice leukemia RAW 264.7 cells in vitro.
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Affiliation(s)
- RS-C Wu
- Department of Anesthesiology, China Medical University Hospital, Taichung, Taiwan
| | - C-S Yu
- School of Pharmacy, China Medical University, Taichung, Taiwan
| | - K-C Liu
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, Taiwan
| | - H-Y Huang
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - S-W Ip
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - J-P Lin
- School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - F-S Chueh
- Department of Health and Nutrition Biotechnology, Asia University, Taichung, Taiwan
| | - J-S Yang
- Department of Pharmacology, China Medical University, Taichung, Taiwan
| | - J-G Chung
- Department of Biological Science and Technology, China Medical University, Taichung, Taiwan
- Department of Biotechnology, Asia University, Taichung, Taiwan
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Beretta F, Bassani S, Binda E, Verpelli C, Bello L, Galli R, Passafaro M. The GluR2 subunit inhibits proliferation by inactivating Src-MAPK signalling and induces apoptosis by means of caspase 3/6-dependent activation in glioma cells. Eur J Neurosci 2009; 30:25-34. [PMID: 19558602 DOI: 10.1111/j.1460-9568.2009.06804.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glioblastoma multiforme (GBM) is the most invasive and undifferentiated type of brain tumour, and so surgical interventions are ineffective. We found that GluR2 is absent in fast-growing GBM-derived tumour stem cells and high-grade glioma specimens, but is expressed in slow-growing stem cells and low-grade glioma specimens. More remarkably, GluR2 overexpression in U-87MG cells inhibits proliferation by inactivating extracellular signal-regulated kinase (ERK)1/2-Src phosphorylation and induces apoptosis. Mechanistically, we observed that the scaffold protein GRIP is essential for the effect of GluR2 on ERK-Src inactivation. These findings indicate that the absence of the GluR2 subunit favours malignancy.
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Affiliation(s)
- Francesca Beretta
- DTI Dulbecco Telethon Institute, Via Vanvitelli 32, Milan 20129, Italy
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Copanaki E, Schürmann T, Eckert A, Leuner K, Müller WE, Prehn JHM, Kögel D. The amyloid precursor protein potentiates CHOP induction and cell death in response to ER Ca2+ depletion. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:157-65. [PMID: 17113167 DOI: 10.1016/j.bbamcr.2006.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 09/20/2006] [Accepted: 10/10/2006] [Indexed: 11/17/2022]
Abstract
Here we investigated the role of the amyloid precursor protein (APP) in regulation of Ca(2+) store depletion-induced neural cell death. Ca(2+) store depletion from the endoplasmic reticulum (ER) was induced by the SERCA (Sarco/Endoplasmic Reticulum Calcium ATPase) inhibitor thapsigargin which led to a rapid induction of the unfolded protein response (UPR) and a delayed activation of executioner caspases in the cultures. Overexpression of APP potently enhanced cytosolic Ca(2+) levels and cell death after ER Ca(2+) store depletion in comparison to vector-transfected controls. GeneChip and RT-PCR analysis revealed that the expression of classical UPR chaperone genes was not altered by overexpression of APP. Interestingly, the induction of the ER stress-responsive pro-apoptotic transcription factor CHOP was significantly upregulated in APP-overexpressing cells in comparison to vector-transfected controls. Chelation of intracellular Ca(2+) with BAPTA-AM revealed that enhanced CHOP expression after store depletion occurred in a Ca(2+)-dependent manner in APP-overexpressing cells. Prevention of CHOP induction by BAPTA-AM and by RNA interference was also able to abrogate the potentiating effect of APP on thapsigargin-induced apoptosis. Application of the store-operated channel (SOC)-inhibitors SK & F96365 and 2-APB downmodulated APP-triggered potentiation of cytosolic Ca(2+) levels and apoptosis after treatment with thapsigargin. Our data demonstrate that APP significantly modulates Ca(2+) store depletion-induced cell death in a SOC- and CHOP-dependent manner, but independent of the UPR.
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Affiliation(s)
- Ekaterini Copanaki
- Department of Neurosurgery, Johann Wolfgang Goethe University Clinics, D-60590 Frankfurt, Germany
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Abstract
Glutamic acid (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system (CNS) where it is involved in the physiological regulation of different processes. It has been well established that excessive endogenous Glu is associated with many acute and chronic neurodegenerative disorders such as cerebral ischaemia, epilepsy, amiotrophic lateral sclerosis, Parkinson's, and Alzheimer's disease. These data have consequently added great impetus to the research in this field. In fact, many Glu receptor antagonists acting at the N-methyl-D-aspartic acid (NMDA), 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA), and/or kainic acid (KA) receptors have been developed as research tools and potential therapeutic agents. Ligands showing competitive antagonistic action at the AMPA type of Glu receptors were first reported in 1988, and the systemically active 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo[f]quinoxaline (NBQX) was first shown to have useful therapeutic effects in animal models of neurological disease in 1990. Since then, the quinoxaline template has represented the backbone of various competitive AMPA receptor antagonists belonging to different classes which had been developed in order to increase potency, selectivity and water solubility, but also to prolong the "in vivo" action. Compounds that present better pharmacokinetic properties and less serious adverse effects with respect to the others previously developed are undergoing clinical evaluation. In the near future, the most important clinical application for the AMPA receptor antagonists will probably be as neuroprotectant in neurodegenerative diseases, such as epilepsy, for the treatment of patients not responding to current therapies. The present review reports the history of competitive AMPA receptor antagonists from 1988 up to today, providing a systematic coverage of both the open and patent literature.
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Affiliation(s)
- Daniela Catarzi
- Dipartimento di Scienze Farmaceutiche, Universita' degli Studi di Firenze, Polo Scientifico, Via U. Schiff, 6-50019 Sesto Fiorentino (Firenze), Italy.
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Colitz CMH, Barden CA, Lu P, Chandler HL. Ultraviolet irradiation up-regulates telomerase transcription and activity in lens epithelial cells. Vet Ophthalmol 2006; 9:379-85. [PMID: 16939468 DOI: 10.1111/j.1463-5224.2006.00499.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Ultraviolet irradiation (UVR) increases telomerase activity in various cell types including skin, a sun-exposed organ. The lens is also continually exposed to UVR and we hypothesized that lenses exposed to UVR would have increased telomerase activity, with up-regulated TERT and TR, the two main components of the telomerase holoenzyme. To evaluate whether the cornea would protect lenses from such changes, whole globes, as well as isolated lenses, were exposed to UVR, and lenses were evaluated for changes in telomerase activity. METHODS There were three parts to this project. The first part of this experiment evaluated freshly harvested normal adult canine lenses exposed to 0, 300, 600, or 1200 J/m(2) UVR, and then allowed to recover for 1, 2, 3 and 4 h. Since only 600 J/m(2) UVR increased telomerase activity, four more postexposure recovery time-points for this UVR dose were evaluated: 10 min, 30 min, 8 h and 24 h. The second part of this experiment used freshly enucleated whole canine globes exposed to 0, 50, 100, 150, 300, 600 or 1200 J/m(2) and incubated overnight; lens epithelial cells (LEC) were evaluated for telomerase activity. The third part evaluated lenses that were exposed to 0 or 600 J/m(2) UVR, and then allowed to recover for 8 and 24 h, before TERT and TR mRNA levels were measured. RESULTS Isolated lenses exposed to 600 J/m(2) UVR had significantly higher telomerase activity than unexposed controls and other UVR doses, at all time-points except 24 h postexposure. Lenses from whole globes exposed to UVR showed a dose-dependent increase in telomerase activity except at 50 J/m(2) and 1200 J/m(2). Isolated lenses exposed to 600 J/m(2) UVR and then allowed to recover for 8 and 24 h significantly up-regulated TERT and TR mRNAs compared to unexposed control lenses. CONCLUSIONS Telomerase activity is regulated at both the transcriptional and post-translational levels in canine LEC. Previous work in our laboratory showed dose, time, and age-dependent changes in telomerase activity in the lens. The present study showed that TERT and TR mRNA transcription was increased for up to 24 h following an acute dose of UVR. Both telomerase activity and TERT and TR mRNA levels were elevated until 24 h post-UVR exposure, TERT in combination with TR functions in proliferation-related telomerase activity, but TERT alone has an anti-apoptotic function and its up-regulation may protect LEC from the acute effects of UVR. We are continuing to evaluate the mechanisms by which telomerase is regulated in normal and cataractous LEC.
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Affiliation(s)
- Carmen M H Colitz
- Departments of Veterinary Clinical Science, The Ohio State University, Columbus, OH, USA.
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12
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Mattson MP. Excitotoxic and excitoprotective mechanisms: abundant targets for the prevention and treatment of neurodegenerative disorders. Neuromolecular Med 2003; 3:65-94. [PMID: 12728191 DOI: 10.1385/nmm:3:2:65] [Citation(s) in RCA: 343] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2003] [Accepted: 02/19/2003] [Indexed: 12/20/2022]
Abstract
Activation of glutamate receptors can trigger the death of neurons and some types of glial cells, particularly when the cells are coincidentally subjected to adverse conditions such as reduced levels of oxygen or glucose, increased levels of oxidative stress, exposure to toxins or other pathogenic agents, or a disease-causing genetic mutation. Such excitotoxic cell death involves excessive calcium influx and release from internal organelles, oxyradical production, and engagement of programmed cell death (apoptosis) cascades. Apoptotic proteins such as p53, Bax, and Par-4 induce mitochondrial membrane permeability changes resulting in the release of cytochrome c and the activation of proteases, such as caspase-3. Events occurring at several subcellular sites, including the plasma membrane, endoplasmic reticulum, mitochondria and nucleus play important roles in excitotoxicity. Excitotoxic cascades are initiated in postsynaptic dendrites and may either cause local degeneration or plasticity of those synapses, or may propagate the signals to the cell body resulting in cell death. Cells possess an array of antiexcitotoxic mechanisms including neurotrophic signaling pathways, intrinsic stress-response pathways, and survival proteins such as protein chaperones, calcium-binding proteins, and inhibitor of apoptosis proteins. Considerable evidence supports roles for excitotoxicity in acute disorders such as epileptic seizures, stroke and traumatic brain and spinal cord injury, as well as in chronic age-related disorders such as Alzheimer's, Parkinson's, and Huntington's disease and amyotrophic lateral sclerosis. A better understanding of the excitotoxic process is not only leading to the development of novel therapeutic approaches for neurodegenerative disorders, but also to unexpected insight into mechanisms of synaptic plasticity.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
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13
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Mattson MP, Kroemer G. Mitochondria in cell death: novel targets for neuroprotection and cardioprotection. Trends Mol Med 2003; 9:196-205. [PMID: 12763524 DOI: 10.1016/s1471-4914(03)00046-7] [Citation(s) in RCA: 207] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Post-mitotic neurons and heart muscle cells undergo apoptotic cell death in a variety of acute and chronic degenerative diseases. The intrinsic pathway of apoptosis involves the permeabilization of mitochondrial membranes, which leads to the release of protease and nuclease activators, and to bioenergetic failure. Mitochondrial permeabilization is induced by a variety of pathologically relevant second messengers, including reactive oxygen species, calcium, stress kinases and pro-apoptotic members of the Bcl-2 family. Several pharmacological agents act on mitochondria to prevent the permeabilization of their membranes, thereby inhibiting apoptosis. Such agents include inhibitors of the permeability transition pore complex (in particular ligands of cyclophilin D), openers of mitochondrial ATP-sensitive or Ca(2+)-activated K(+) channels, and proteins from the Bcl-2 family engineered to cross the plasma membrane. In addition, manipulations that modulate the expression or activity of mitochondrial uncoupling proteins can prevent the death of post-mitotic cells. Such agents hold promise for use in clinical neuroprotection and cardioprotection.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
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Lu C, Fu W, Zhao D, Mattson MP. The DNA damaging agent etoposide activates a cell survival pathway involving alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors and mitogen-activated protein kinases in hippocampal neurons. J Neurosci Res 2002; 70:671-9. [PMID: 12424735 DOI: 10.1002/jnr.10413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Etoposide, an inhibitor of topoisomerase II that induces DNA damage and can trigger cell death, is used as a chemotherapeutic agent. Because chemotherapies can result in neurological complications and because DNA damage in neurons is implicated in the pathogenesis of several neurodegenerative disorders, we studied the effects of etoposide on cultured hippocampal neurons. We found that etoposide induces neuronal apoptosis and that, prior to the cell death commitment point, there is an increase in whole-cell alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-induced current but no change in N-methyl-D-aspartate (NMDA)-induced current. Associated with the increase in AMPA-induced current was an increase in the amounts of AMPA receptor subunits GluR1 and GluR4, whereas levels of the NMDA receptor subunit NR1 were unaffected by etoposide. AMPA receptor activation can result in excitotoxic cell death but can also activate signaling pathways that promote synaptic plasticity and cell survival. We found that etoposide increases the activation of p42 and p44 mitogen-activated protein (MAP) kinases, and that activation of the MAP kinases by etoposide requires AMPA receptor activation. Pharmacological blockade of AMPA receptors and p42/p44 MAP kinases, but not of NMDA receptors, exacerbated etoposide-induced cell death. These findings suggest that, although etoposide is neurotoxic, it also activates a cell survival pathway involving AMPA receptor-mediated activation of p42/p44 MAP kinases. Agents that selectively inhibit the cell life or death pathways triggered by DNA damage may prove useful in the settings of cancer and neurodegenerative disorders, respectively.
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Affiliation(s)
- Chengbiao Lu
- Laboratory of Neurosciences, National Institute on Aging/NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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McKinnon SJ, Lehman DM, Tahzib NG, Ransom NL, Reitsamer HA, Liston P, LaCasse E, Li Q, Korneluk RG, Hauswirth WW. Baculoviral IAP repeat-containing-4 protects optic nerve axons in a rat glaucoma model. Mol Ther 2002; 5:780-7. [PMID: 12027563 DOI: 10.1006/mthe.2002.0608] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gene therapy represents an attractive approach for the treatment of eye diseases such as glaucoma. Ocular administration of viral vectors produces localized retinal gene expression with reduced risks of side effects reported with systemic administration of viral vectors. Recombinant adeno-associated viral (AAV) vectors have proven effective in producing long-term retinal gene expression, due to stable integration of DNA into the genome and lack of host immune response to the virus. Recently developed AAV constructs using the chicken beta-actin (CBA) promoter drive highly efficient transgene expression in retinal ganglion cells (RGCs), photoreceptors, and pigment epithelium. Rats were given unilateral intravitreal injections of AAV-CBA vector coding for human baculoviral IAP repeat-containing protein-4 (BIRC4), a potent caspase inhibitor. Ocular hypertension was induced in the same eye by sclerosis of aqueous humor outflow channels. After chronic exposure to elevated intraocular pressure, we performed optic nerve axon counts to determine the neuroprotective effects of retinal BIRC4 expression, and compared axon survival with vector and balanced salt solution control groups. Gene therapy delivering BIRC4 significantly promoted optic nerve axon survival in a chronic ocular hypertensive model of rat glaucoma. Blocking RGC apoptosis with caspase inhibitors represents a promising approach for treatment of human glaucoma.
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Affiliation(s)
- Stuart J McKinnon
- Department of Ophthalmology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78229, USA.
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Lu C, Mattson MP. Dimethyl sulfoxide suppresses NMDA- and AMPA-induced ion currents and calcium influx and protects against excitotoxic death in hippocampal neurons. Exp Neurol 2001; 170:180-5. [PMID: 11421595 DOI: 10.1006/exnr.2001.7686] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dimethyl sulfoxide (DMSO) is widely used in neuroscience research as a solvent for various pharmacological agents in both cell culture and in vivo studies and is also used in humans to treat musculoskeletal problems and pain. We now report that concentrations of DMSO to which neurons are typically exposed in experimental studies and in human patients (0.5-1.5%) inhibit glutamate responses in hippocampal neurons. DMSO suppresses, in a rapidly reversible manner, electrophysiological responses and calcium influx induced by glutamate, N-methyl-d-aspartate, and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate. Moreover, DMSO can prevent excitotoxic death of the neurons. These findings have important implications for the use of DMSO as a solvent in studies that involve glutamatergic neurotransmission. Our data also identify a mechanism that might explain clinical effects of DMSO on both peripheral and CNS neurons and suggest a potential use for DMSO in the treatment of excitotoxic neurodegenerative conditions.
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Affiliation(s)
- C Lu
- Laboratory of Neurosciences, Gerontology Research Center 4F01, National Institute on Aging, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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