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de Mello Souza T, Choueri RB, Nobre CR, de Souza Abessa DM, Moreno BB, Carnaúba JH, Mendes GI, de Albergaria-Barbosa ACR, Simões FR, Gusso-Choueri PK. Interactive effects of microplastics and benzo[a]pyrene on two species of marine invertebrates. MARINE POLLUTION BULLETIN 2023; 193:115170. [PMID: 37329735 DOI: 10.1016/j.marpolbul.2023.115170] [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: 02/14/2023] [Revised: 06/07/2023] [Accepted: 06/09/2023] [Indexed: 06/19/2023]
Abstract
This study aimed to evaluate B[a]P and low-density polyethylene microplastics (MPs) toxicty, alone and in mixture (0.03 to 30 μg L-1 of B[a]P; and 5, 50 and 500 mg L-1 for MPs). Five mg L-1 of MPs is considerably higher than commonly reported environmental concentrations, although it has been reported for marine environments. Individual (sea urchin embryo-larval development and mortality of mysids) and sub-individual responses (LPO and DNA damage in mysids) were assessed. The toxicity increased as the B[a]P concentration increased, and microplastics alone did not cause toxicity. B[a]P toxicity was not modified by the lowest concentration of MPs (5 mg L-1), but at higher MPs concentrations (50 and 500 mg L-1), the effects of B[a]P on sea urchin development and in biomarkers in mysids were diminished. Microplastics interacted with B[a]P in seawater, reducing its toxicity, probably due to adsorption of B[a]P to the surface of microplastics.
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Affiliation(s)
- Tawany de Mello Souza
- Universidade Santa Cecília (Unisanta), R. Oswaldo Cruz, 277, Boqueirão, 11045-907 Santos, São Paulo, Brazil; Laboratório de Ecotoxicologia - ALS Life Sciences Brasil - Food & Agro, R. Fábia, 59, Vila Romana, 05051-030 São Paulo, SP, Brazil
| | - Rodrigo Brasil Choueri
- Departamento de Ciências do Mar, Instituto do Mar, Universidade Federal de São Paulo (Unifesp), Campus Baixada Santista. Rua Maria Máximo, 168, Ponta da Praia, 11030-100 Santos, São Paulo, Brazil.
| | - Caio Rodrigues Nobre
- Laboratório de Ecotoxicologia - ALS Life Sciences Brasil - Food & Agro, R. Fábia, 59, Vila Romana, 05051-030 São Paulo, SP, Brazil
| | - Denis Moledo de Souza Abessa
- NEPEA, Campus do Litoral Paulista, Universidade Estadual Paulista Júlio de Mesquita Filho (Unesp), Praça Infante Dom Henrique, s/n, 11330-900 São Vicente, São Paulo, Brazil
| | - Beatriz Barbosa Moreno
- Departamento de Ciências do Mar, Instituto do Mar, Universidade Federal de São Paulo (Unifesp), Campus Baixada Santista. Rua Maria Máximo, 168, Ponta da Praia, 11030-100 Santos, São Paulo, Brazil
| | - José Hérelis Carnaúba
- Programa de Pós-Graduação em Química: Ciência e Tecnologia da Sustentabilidade, Universidade Federal de São Paulo (Unifesp), Diadema, São Paulo, Brazil
| | - Gabriel Izar Mendes
- Laboratório de Geoquímica Marinha, Instituto de Geociências, Universidade Federal da Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115 Salvador, Bahia, Brazil; Laboratório de Estudos do Petróleo, Instituto de Geociências, Universidade Federal da Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115 Salvador, Bahia, Brazil
| | - Ana Cecilia Rizzatti de Albergaria-Barbosa
- Laboratório de Geoquímica Marinha, Instituto de Geociências, Universidade Federal da Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115 Salvador, Bahia, Brazil; Laboratório de Estudos do Petróleo, Instituto de Geociências, Universidade Federal da Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115 Salvador, Bahia, Brazil
| | - Fábio Ruiz Simões
- Departamento de Ciências do Mar, Instituto do Mar, Universidade Federal de São Paulo (Unifesp), Campus Baixada Santista. Rua Maria Máximo, 168, Ponta da Praia, 11030-100 Santos, São Paulo, Brazil
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Abstract
Alzheimer's disease (AD) is characterized by neuronal death with an accumulaton of intra-cellular neurofibrillary tangles (NFT) and extracellular amyloid plaques. Reduced DNA repair ability has been reported in AD brains. In neurons, the predominant mechanism to repair double-strand DNA breaks (DSB) is non-homologous end joining (NHEJ) that requires DNA-dependent protein kinase (DNA-PK) activity. DNA-PK is a holoenzyme comprising the p460 kD DNA-PK catalytic subunit (DNA-PKcs) and its activator Ku, a heterodimer of p86 (Ku80) and p70 (Ku70) subunits. Upon binding to double-stranded DNA ends, Ku recruits DNA-PKcs to process NHEJ. In AD brains, reduced NHEJ activity as well as DNA-PKcs and Ku protein levels have been shown. Normal aging brains also show a reduction in both DNA-PKcs and Ku levels questioning a direct link between NHEJ ability and AD, and suggesting additional players/events in AD pathogenesis. Deficiency of Ku80, a somatostatin receptor, can disrupt somatostatin signaling thus inducing amyloid beta (Aβ) generation, which in turn can potentiate DNA-PKcs degradation and consequently loss of NHEJ activity, an additional step negatively affecting DSB repair. Trigger of these two different pathways culminating in genome instability may differentiate the outcomes between AD and normal aging.
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Affiliation(s)
- Jyotshna Kanungo
- Division of Neurotoxicology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
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3
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Iuchi K, Yagura T. DNA binding activity of Ku during chemotherapeutic agent-induced early apoptosis. Exp Cell Res 2016; 342:135-44. [PMID: 26976509 DOI: 10.1016/j.yexcr.2016.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 01/09/2023]
Abstract
Ku protein is a heterodimer composed of two subunits, and is capable of both sequence-independent and sequence-specific DNA binding. The former mode of DNA binding plays a crucial role in DNA repair. The biological role of Ku protein during apoptosis remains unclear. Here, we show characterization of Ku protein during apoptosis. In order to study the DNA binding properties of Ku, we used two methods for the electrophoresis mobility shift assay (EMSA). One method, RI-EMSA, which is commonly used, employed radiolabeled DNA probes. The other method, WB-EMSA, employed unlabeled DNA followed by western blot and detection with anti-Ku antiserum. In this study, Ku-DNA probe binding activity was found to dramatically decrease upon etoposide treatment, when examined by the RI-EMSA method. In addition, pre-treatment with apoptotic cell extracts inhibited Ku-DNA probe binding activity in the non-treated cell extract. The inhibitory effect of the apoptotic cell extract was reduced by DNase I treatment. WB-EMSA showed that the Ku in the apoptotic cell extract bound to fragmented endogenous DNA. Interestingly, Ku in the apoptotic cell extract purified by the Resource Q column bound 15-bp DNA in both RI-EMSA and WB-EMSA, whereas Ku in unpurified apoptotic cell extracts did not bind additional DNA. These results suggest that Ku binds cleaved chromosomal DNA and/or nucleosomes in apoptotic cells. In conclusion, Ku is intact and retains DNA binding activity in early apoptotic cells.
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Affiliation(s)
- Katsuya Iuchi
- Department of Bioscience, Faculty of Science and Technology, Kwansei Gakuin University, 2-1 Gakuin, Sanda-shi, Hyogo-ken 669-1337, Japan.
| | - Tatsuo Yagura
- Department of Bioscience, Faculty of Science and Technology, Kwansei Gakuin University, 2-1 Gakuin, Sanda-shi, Hyogo-ken 669-1337, Japan
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Simpson JE, Ince PG, Matthews FE, Shaw PJ, Heath PR, Brayne C, Garwood C, Higginbottom A, Wharton SB. A neuronal DNA damage response is detected at the earliest stages of Alzheimer's neuropathology and correlates with cognitive impairment in the Medical Research Council's Cognitive Function and Ageing Study ageing brain cohort. Neuropathol Appl Neurobiol 2015; 41:483-96. [PMID: 25443110 PMCID: PMC4861215 DOI: 10.1111/nan.12202] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/27/2014] [Indexed: 01/03/2023]
Abstract
AIMS Population-based studies have shown that approximately 20% of the ageing population (aged 65 years and over) with dementia have little or no classical Alzheimer-type neuropathology. Cumulative DNA damage and a reduced capacity of DNA repair may result in neuronal dysfunction and contribute to cognitive impairment independent of Alzheimer-type pathology in the ageing brain. METHODS We investigated expression of the DNA damage response (DDR)-associated molecules γH2AX and DNA-PKcs using immunohistochemistry and western blotting, and senescence-associated β-galactosidase in the frontal association neocortex of cases with low levels of Alzheimer-type pathology (Braak & Braak stage 0-II), and explored their relationship to cognitive impairment in a population-representative sample from the Medical Research Council's Cognitive Function and Ageing Study cohort. RESULTS Increases in both γH2AX(+) (r(s) = -0.36, P = 0.025) and DNA-PKcs(+) (r(s) = -0.39, P = 0.01) neuronal counts were associated with a lower Mini-Mental State Examination score. Increasing levels of senescence associated-β-gal(+) pyramidal neurones were weakly associated with the total number of DNA-PKcs(+) neurones (P = 0.08), but not with traditional senescence-associated signalling molecules, including p53 and p16. CONCLUSION The association between the neuronal DDR and cognitive impairment, independent of AD pathology in the ageing brain, may be suggestive of a causal link via neuronal dysfunction.
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Affiliation(s)
- Julie E Simpson
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Paul G Ince
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | | | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Paul R Heath
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Carol Brayne
- Institute of Public Health, University of Cambridge, Cambridge, UK
| | - Claire Garwood
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Adrian Higginbottom
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Stephen B Wharton
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
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Apoptosis in human compressive myelopathy due to metastatic neoplasia. Spine (Phila Pa 1976) 2015; 40:E450-7. [PMID: 25868101 DOI: 10.1097/brs.0000000000000821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Immunohistochemical assessment of apoptotic markers in human cases of compressive myelopathy due to neoplastic compression. OBJECTIVE To characterize the role of apoptosis in neoplastic compressive myelopathy in human postmortem tissue with extramedullary tumor involvement. SUMMARY OF BACKGROUND DATA Neoplasms, whether primary or metastatic, may lead to compression of the spinal cord and development of a compressive myelopathy syndrome. Apoptotic processes of cell death are thought to contribute to cell death in chronic compressive myelopathy because of degenerative spondylosis, but this has not previously been described in neoplastic compression. METHODS Six postmortem cases of human neoplastic compressive myelopathy were assessed for apoptosis using a panel of immunohistochemical markers including Fas, B-cell lymphoma 2 (Bcl-2), caspase-3 and 9, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), poly (ADP-ribose) polymerase (PARP), apoptosis-inducing factor (AIF), and terminal deoxynucleotide transferase dUTP Nick End Labeling (TUNEL). RESULTS Apoptosis was maximal at the site of tumor compression. Glial cells, predominantly oligodendrocytes, were immunopositive for DNA-PKcs, PARP, AIF, and TUNEL. Axons were immunopositive for caspase 3, DNA-PKcs, and AIF. Neurons were immunopositive for DNA-PKcs, PARP, AIF, and TUNEL. CONCLUSION The current study demonstrates that apoptosis plays a role in human neoplastic compressive myelopathy. Necrosis dominates the severe end of the spectrum of compression. The prominent oligodendroglial involvement is suggestive that apoptosis may be important in the ongoing remodeling of white matter due to sustained compression. LEVEL OF EVIDENCE 4.
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MicroRNA-124 (miR-124) regulates Ku70 expression and is correlated with neuronal death induced by ischemia/reperfusion. J Mol Neurosci 2013; 52:148-55. [PMID: 24166354 DOI: 10.1007/s12031-013-0155-9] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/15/2013] [Indexed: 12/13/2022]
Abstract
MicroRNAs are small, non-coding RNA molecules that regulate gene expression, and miR-124 is the most abundant miRNA in the brain. Studies have shown that miR-124 is clearly reduced in the ischemic brain after stroke; however, the role of miR-124 after stroke is less well studied. Using TargetScan, MicroCosm Targets version 5, and microRNA.org databases, we identified miR-124 as a possible regulator of the DNA repair protein Ku70. We validated that Ku70 is a target for miR-124 with a luciferase reporter activity assay. Moreover, adult rats subjected to focal cerebral ischemia exhibited a substantial reduction of miR-124 expression, which was inversely upregulated by Ku70 expression. In vivo treatment with miR-124 antagomir effectively enhanced Ku70 mRNA and protein levels in the ischemic region. Furthermore, knockdown of cerebral miR-124 reduced cell death and infarct size and improved neurological outcomes. Our data demonstrate that miR-124 is an endogenous regulator of Ku70 that improves ischemia/reperfusion (I/R)-induced brain injury and dysfunction.
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Antila JM, Jeserevics J, Rakauskas M, Anttila M, Cizinauskas S. Spinal dural ossification causing neurological signs in a cat. Acta Vet Scand 2013; 55:47. [PMID: 23777582 PMCID: PMC3694019 DOI: 10.1186/1751-0147-55-47] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 06/09/2013] [Indexed: 11/10/2022] Open
Abstract
A six-year-old Ragdoll cat underwent examination due to a six-month history of slowly progressive gait abnormalities. The cat presented with an ambulatory tetraparesis with a neurological examination indicating a C1-T2 myelopathy. Radiographs of the spine showed a radiopaque irregular line ventrally in the vertebral canal dorsal to vertebral bodies C3-C5. In this area, magnetic resonance imaging revealed an intradural extramedullary/extradural lesion compressing the spinal cord. The spinal cord was surgically decompressed. The cause of the spinal cord compression was dural ossification, a diagnosis confirmed by histopathological examination of the surgically dissected sample of dura mater. The cat gradually improved after the procedure and was ambulating better than prior to the surgery. The cat’s locomotion later worsened again due to ossified plaques in the dura causing spinal cord compression on the same cervical area as before. Oral prednisolone treatment provided temporary remission. Ten months after surgery, the cat was euthanized due to severe worsening of gait abnormalities, non-ambulatory tetraparesis. Necropsy confirmed spinal cord compression and secondary degenerative changes in the spinal cord on cervical and lumbar areas caused by dural ossification. To our knowledge, this is the first report of spinal dural ossification in a cat. The reported cat showed neurological signs associated with these dural changes. Dural ossification should be considered in the differential diagnosis of compressive spinal cord disorders in cats.
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Smith JA, Park S, Krause JS, Banik NL. Oxidative stress, DNA damage, and the telomeric complex as therapeutic targets in acute neurodegeneration. Neurochem Int 2013; 62:764-75. [PMID: 23422879 DOI: 10.1016/j.neuint.2013.02.013] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 02/04/2013] [Accepted: 02/08/2013] [Indexed: 01/19/2023]
Abstract
Oxidative stress has been identified as an important contributor to neurodegeneration associated with acute CNS injuries and diseases such as spinal cord injury (SCI), traumatic brain injury (TBI), and ischemic stroke. In this review, we briefly detail the damaging effects of oxidative stress (lipid peroxidation, protein oxidation, etc.) with a particular emphasis on DNA damage. Evidence for DNA damage in acute CNS injuries is presented along with its downstream effects on neuronal viability. In particular, unchecked oxidative DNA damage initiates a series of signaling events (e.g. activation of p53 and PARP-1, cell cycle re-activation) which have been shown to promote neuronal loss following CNS injury. These findings suggest that preventing DNA damage might be an effective way to promote neuronal survival and enhance neurological recovery in these conditions. Finally, we identify the telomere and telomere-associated proteins (e.g. telomerase) as novel therapeutic targets in the treatment of neurodegeneration due to their ability to modulate the neuronal response to both oxidative stress and DNA damage.
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Affiliation(s)
- Joshua A Smith
- Division of Neurology, Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas St., Clinical Sciences Building Room 309, Charleston, SC 29425, USA.
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Cardinale A, Racaniello M, Saladini S, De Chiara G, Mollinari C, de Stefano MC, Pocchiari M, Garaci E, Merlo D. Sublethal doses of β-amyloid peptide abrogate DNA-dependent protein kinase activity. J Biol Chem 2011; 287:2618-31. [PMID: 22139836 DOI: 10.1074/jbc.m111.276550] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Accumulation of DNA damage and deficiency in DNA repair potentially contribute to the progressive neuronal loss in neurodegenerative disorders, including Alzheimer disease (AD). In multicellular eukaryotes, double strand breaks (DSBs), the most lethal form of DNA damage, are mainly repaired by the nonhomologous end joining pathway, which relies on DNA-PK complex activity. Both the presence of DSBs and a decreased end joining activity have been reported in AD brains, but the molecular player causing DNA repair dysfunction is still undetermined. β-Amyloid (Aβ), a potential proximate effector of neurotoxicity in AD, might exert cytotoxic effects by reactive oxygen species generation and oxidative stress induction, which may then cause DNA damage. Here, we show that in PC12 cells sublethal concentrations of aggregated Aβ(25-35) inhibit DNA-PK kinase activity, compromising DSB repair and sensitizing cells to nonlethal oxidative injury. The inhibition of DNA-PK activity is associated with down-regulation of the catalytic subunit DNA-PK (DNA-PKcs) protein levels, caused by oxidative stress and reversed by antioxidant treatment. Moreover, we show that sublethal doses of Aβ(1-42) oligomers enter the nucleus of PC12 cells, accumulate as insoluble oligomeric species, and reduce DNA-PK kinase activity, although in the absence of oxidative stress. Overall, these findings suggest that Aβ mediates inhibition of the DNA-PK-dependent nonhomologous end joining pathway contributing to the accumulation of DSBs that, if not efficiently repaired, may lead to the neuronal loss observed in AD.
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Affiliation(s)
- Alessio Cardinale
- Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome 00166, Italy
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Mandraju R, Chekuri A, Bhaskar C, Duning K, Kremerskothen J, Kondapi AK. Topoisomerase IIβ associates with Ku70 and PARP-1 during double strand break repair of DNA in neurons. Arch Biochem Biophys 2011; 516:128-37. [PMID: 22019940 DOI: 10.1016/j.abb.2011.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 09/30/2011] [Accepted: 10/01/2011] [Indexed: 12/20/2022]
Abstract
In the present study, the activity of Topoisomerase IIβ (TopoIIβ) is evaluated during peroxide induced double stranded DNA breaks (DSBs) repair in primary neurons. The results showed that the TopoIIβ levels were enhanced during recovery from peroxide mediated damage (PED) along with Ku70, PARP-1, pol beta, and WRN helicase. Furthermore, siRNA mediated knock-down of TopoIIβ in primary neurons conferred enhanced susceptibility to PED in neurons. DSBs in neurons are repaired through two pathways, one promoted by Ku70, while the other is by PARP-1 dependent manner. Participation of TopoIIβ in both pathways was assessed by analysis of the interaction of TopoIIβ with Ku70 and PARP-1 using co-immunoprecipitation experiments in extracts of neurons under peroxide treatment and recovery. The results of these studies showed a strong interaction of TopoIIβ with Ku70 as well as PARP-1 suggesting that TopoIIβ is associated both in Ku70 and PARP-dependent pathways in DSBs repair in primary neurons. The study has thus established that TopoIIβ is an essential component in DSBs repair in primary neurons in both Ku70 and PARP-1 dependent pathways. We suppose that the interaction of TopoIIβ may provide stabilization of the repair complex, which may assist in maintenance of tensional integrity in genomic DNA.
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Affiliation(s)
- Rajakumar Mandraju
- Departments of Biotechnology, School of Life Sciences, University of Hyderabad, India
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Breu A, Sprinzing B, Merkl K, Bechmann V, Kujat R, Jenei-Lanzl Z, Prantl L, Angele P. Estrogen reduces cellular aging in human mesenchymal stem cells and chondrocytes. J Orthop Res 2011; 29:1563-71. [PMID: 21469181 DOI: 10.1002/jor.21424] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2011] [Accepted: 03/10/2011] [Indexed: 02/04/2023]
Abstract
Chondrocyte aging is associated with cartilage degeneration and senescence impairs the regenerative potential of mesenchymal stem cells (MSCs). Estrogen exerts profound effects on human physiology including articular cartilage and MSCs. The present study should analyze the effects of pre- and postmenopausal estrogen concentrations on chondrogenic cells. Physiologic premenopausal concentrations of 17β-estradiol (E(2)) significantly decelerated telomere attrition in MSCs and chondrocytes while postmenopausal E(2) concentration had no significant effects. The estrogen agonist-antagonist tamoxifen did not affect telomere biology, but inhibited the E(2) -stimulated reduction in telomere shortening. E(2) and tamoxifen did not influence cell proliferation, cell morphology, and β-galactosidase staining in chondrogenic cells. E(2) treatment did not affect the telomere-associated proteins TRF1 and TRF2. E(2) had no regulatory effects on the expression rates of the cell cycle regulator p21 and the DNA repair proteins SIRT1 and XRCC5. In spite of reducing telomere shortening in aging MSCs and chondrocytes, estrogen is not able to prevent somatic cells from replicative exhaustion and from finally entering senescence. The fade of telomere shortening under pre- to postmenopausal estrogen concentrations suggests, at least in part, a senescence-dependent cause for the onset of osteoarthritis in women after menopause.
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Affiliation(s)
- Anita Breu
- Department of Anesthesiology, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany
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Brandl A, Hartmann A, Bechmann V, Graf B, Nerlich M, Angele P. Oxidative stress induces senescence in chondrocytes. J Orthop Res 2011; 29:1114-20. [PMID: 21284033 DOI: 10.1002/jor.21348] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Accepted: 12/09/2010] [Indexed: 02/04/2023]
Abstract
Cellular senescence is a program activated during diverse situations of cell stress. Chondrocytes differ from other somatic cells as articular cartilage is an avascular tissue. The effects of oxidative stress on chondrocytes are still unknown. Our studies were to investigate into the proliferation potential, cytological features and the telomere linked stress response system of human osteoarthritic chondrocytes, subjected to acute or prolonged oxidant challenge with hydrogen peroxide. Telomere length was measured using the telomere restriction fragment assay, gene expression was determined by RT-PCR. Sub-lethal doses of oxidative stress induced cell-cycle arrest, senescent-morphological features and senescence-associated β-galactosidase positivity. Prolonged oxidative treatment had no effects on cell proliferation or morphology. Sub-lethal and prolonged low doses of oxidative stress considerably accelerated telomere attrition. The effects of sub-lethal oxidative stress regarding proliferation and telomere biology were more distinct in senescent cells. Acute oxidant insult caused up-regulation of p21 expression to levels comparable to senescent cells. TRF2 protects telomere ends and showed elevated expression levels. SIRT1 and XRCC5 enable cells to cope with unfavorable growing conditions. Both were up-regulated after oxidant insult, but expression levels decreased in aging cells. Taken together, oxidative stress considerably accelerated telomere shortening and cellular aging in chondrocytes. Senescent cells showed a reduced tolerance to oxidative stress.
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Affiliation(s)
- Anita Brandl
- Department of Anesthesiology, University Hospital Regensburg, 93042 Regensburg, Germany.
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Oxidative stress induces senescence in human mesenchymal stem cells. Exp Cell Res 2011; 317:1541-7. [DOI: 10.1016/j.yexcr.2011.02.015] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 02/15/2011] [Accepted: 02/25/2011] [Indexed: 12/27/2022]
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Li P, Hu X, Gan Y, Gao Y, Liang W, Chen J. Mechanistic insight into DNA damage and repair in ischemic stroke: exploiting the base excision repair pathway as a model of neuroprotection. Antioxid Redox Signal 2011; 14:1905-18. [PMID: 20677909 PMCID: PMC3078503 DOI: 10.1089/ars.2010.3451] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Stroke is a common cause of death and serious long-term adult disability. Oxidative DNA damage is a severe consequence of oxidative stress associated with ischemic stroke. The accumulation of DNA lesions, including oxidative base modifications and strand breaks, triggers cell death in neurons and other vulnerable cell populations in the ischemic brain. DNA repair systems, particularly base excision repair, are endogenous defense mechanisms that combat oxidative DNA damage. The capacity for DNA repair may affect the susceptibility of neurons to ischemic stress and influence the pathological outcome of stroke. This article reviews the accumulated understanding of molecular pathways by which oxidative DNA damage is triggered and repaired in ischemic cells, and the potential impact of these pathways on ischemic neuronal cell death/survival. Genetic or pharmacological strategies that target the signaling molecules in DNA repair responses are promising for potential clinically effective treatment. Further understanding of mechanisms for oxidative DNA damage and its repair processes may lead to new avenues for stroke management.
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Affiliation(s)
- Peiying Li
- Anesthesiology Department of Huashan Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
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Tsuchimoto T, Sakata KI, Someya M, Yamamoto H, Hirayama R, Matsumoto Y, Furusawa Y, Hareyama M. Gene expression associated with DNA-dependent protein kinase activity under normoxia, hypoxia, and reoxygenation. JOURNAL OF RADIATION RESEARCH 2011; 52:464-471. [PMID: 21905307 DOI: 10.1269/jrr.10137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- Tadashi Tsuchimoto
- Department of Radiology, Sapporo Medical University, School of Medicine, Hokkaido, Japan
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Cultured cerebellar granule neurons as an in vitro aging model: topoisomerase IIβ as an additional biomarker in DNA repair and aging. Toxicol In Vitro 2010; 24:1935-45. [PMID: 20708677 DOI: 10.1016/j.tiv.2010.08.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 07/27/2010] [Accepted: 08/09/2010] [Indexed: 01/11/2023]
Abstract
Aging in the brain is a multicellular process manifesting as neurodegeneration and associated functional impairment. In the present study, we report that cerebellar granule neurons (CGNs) in culture show senescence-mediated molecular changes indicating establishment of aging processes in vitro. CGNs were viable for 5 weeks followed by cellular degeneration. Molecular changes correlated with cellular senescence and aging include the elevation of senescence-mediated beta galactosidase (SA-β-gal) activity and intracellular Ca(2+) levels. Decreased base excision repair (BER) as well as non-homologous end joining (NHEJ) activities in CGNs were also observed upon aging in vitro. The decrease in NHEJ activity was shown correlated with corresponding decrease in the levels of topoisomerase IIβ (topo IIβ), Ku 70 and Ku 80 suggesting a crucial role for topo IIβ in repair capacity of CGNs. These studies, besides establishing that CGNs would serve as a good in vitro model for analysis of aging phenomena, also brought out that topo IIβ, by virtue of its significant role in controlling NHEJ activity, would serve as an additional biomarker for studying aging process.
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The effects of propofol on hippocampal caspase-3 and Bcl-2 expression following forebrain ischemia-reperfusion in rats. Brain Res 2010; 1356:11-23. [PMID: 20707988 DOI: 10.1016/j.brainres.2010.08.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/18/2010] [Accepted: 08/05/2010] [Indexed: 12/15/2022]
Abstract
Transient cerebral ischemia may result in neuronal apoptosis. During this process, several apoptosis-regulatory genes are induced in apoptotic cells. Among these genes, cysteinyl aspartate-specific protease-3 (caspase-3) and B-cell leukemia-2 (Bcl-2) are the most effective apoptotic regulators because they play a decisive role in the occurrence of apoptosis. Research has shown that propofol, which is an intravenous anesthetic agent, exhibits neuroprotective effects against cerebral ischemia-reperfusion injury, although the neuroprotective mechanism is still unclear. In this study, we examined the effects of propofol in rats after forebrain ischemia-reperfusion. We assessed the expression of hippocampal caspase-3, which acts as an apoptotic activator, and Bcl-2, which acts as an apoptotic suppressor. Forebrain ischemia was induced in hypotensive rats by clamping the bilateral common carotid arteries for 10 min. Propofol was administered via a lateral cerebral ventricle injection using a microsyringe after the induction of ischemia. Neuronal damage was determined by histological examination of brain sections at the level of the dorsal hippocampus. Caspase-3 and Bcl-2 expression in the hippocampus were detected using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. We also used an immunohistochemical method after ischemia-reperfusion. In the hippocampus, caspase-3 and Bcl-2 mRNA were dramatically increased at 24h after forebrain ischemia. Following 6-24h of reperfusion, forebrain ischemia for 10 min induced a gradual increase in the expression of caspase-3 and Bcl-2 protein in the rat hippocampus, which peaked at 24h. In the propofol (1.0mg/kg) intervention group, the hippocampal expression of caspase-3 mRNA decreased significantly in rats 24h after ischemia; Bcl-2 mRNA was increased at the same time point. During the 24-h reperfusion period and after treatment with propofol, the level of caspase-3 protein expression was low, while the level of Bcl-2 was high. Thus, our results suggest that the neuroprotective effects of propofol against neuronal apoptosis may be mediated by the inhibition of caspase-3 expression and an increase in Bcl-2 expression.
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Liu J, Naegele JR, Lin SL. The DNA-PK catalytic subunit regulates Bax-mediated excitotoxic cell death by Ku70 phosphorylation. Brain Res 2009; 1296:164-75. [PMID: 19664609 DOI: 10.1016/j.brainres.2009.07.101] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 07/27/2009] [Accepted: 07/30/2009] [Indexed: 10/20/2022]
Abstract
DNA repair deficiency results in neurodegenerative disease and increased susceptibility to excitotoxic cell death, suggesting a critical but undefined role for DNA damage in neurodegeneration. We compared DNA damage, Ku70-Bax interaction, and Bax-dependent excitotoxic cell death in kainic acid-treated primary cortical neurons derived from both wild-type mice and mice deficient in the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) encoded by the Prkdc gene. In both wild-type and Prkdc(-/-) neurons, kainic acid treatment resulted in rapid induction of DNA damage (53BP1 foci formation) followed by nuclear pyknosis. Bax deficiency, by either Bax shRNA-mediated knockdown or gene deletion, protected wild-type and heterozygous but not Prkdc(-/-) neurons from kainate-induced excitotoxicity. Cotransfection of DNA-PKcs with Bax shRNA restored Bax shRNA-mediated neuroprotection in Prkdc(-/-) neurons, suggesting that DNA-PKcs is required for kainate-induced activation of the pro-apoptotic Bax pathway. Immunoprecipitation studies revealed that the DNA-PKcs-nonphosphorylatable Ku70 (S6A/S51A) bound 3- to 4-fold greater Bax than wild-type Ku70, suggesting that DNA-PKcs-mediated Ku70 phosphorylation causes release of Bax from Ku70. In support of this, kainic acid induced translocation of a Bax-EGFP fusion protein to the mitochondria in the presence of a cotransfected wild-type, but not mutant Ku70 (S6A/S51A) gene when examined at 4 and 8 h following kainate addition. We conclude that DNA-PKcs links DNA damage to Bax-dependent excitotoxic cell death, by phosphorylating Ku70 on serines 6 and/or 51, to initiate Bax translocation to the mitochondria and directly activate a pro-apoptotic Bax-dependent death cascade.
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Affiliation(s)
- Jia Liu
- Program in Neuroscience and Behavior, Department of Biology, Wesleyan University, Middletown, CT 06459-0170, USA
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20
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Kang MJ, Jung SM, Kim MJ, Bae JH, Kim HB, Kim JY, Park SJ, Song HS, Kim DW, Kang CD, Kim SH. DNA-dependent protein kinase is involved in heat shock protein-mediated accumulation of hypoxia-inducible factor-1alpha in hypoxic preconditioned HepG2 cells. FEBS J 2009; 275:5969-81. [PMID: 19021771 DOI: 10.1111/j.1742-4658.2008.06725.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Hypoxic preconditioning may afford protection against subsequent lethal hypoxia. As hypoxic tolerance induces changes in the expression of genes involved in DNA damage and repair response pathways, we investigated whether DNA-dependent protein kinase (DNA-PK), one of the DNA double-strand break repair proteins, could be involved in hypoxic preconditioning-induced protective signaling cascades. We showed that induction of hypoxia-inducible factor-1alpha expression during hypoxic preconditioning by repeated hypoxic exposure was associated with increased mRNA and protein levels of DNA-PK catalytic subunit (DNA-PKcs) and Ku70/Ku80, the DNA-PK components, in human hepatoma HepG2 cells, followed by upregulation of Hsp70/Hsp90 and Bcl-2 and concurrent downregulation of Bax. Additionally, loss of DNA-PKcs led to attenuated expression of Hsp70/Hsp90, accelerated hypoxia-inducible factor-1alpha degradation, and increased susceptibility to hypoxia-induced cell death. We also found that the mRNA and protein levels of heat shock factor-1 (HSF1) were progressively increased with DNA-PK activation during hypoxic preconditioning, and inhibition of HSF1 function by KNK437 resulted in a significant decrease in the level of protein kinase Akt as well as of DNA-PKcs, with downregulation of Hsp70/Hsp90 and HIF-1alpha. Our results suggest the possibility that DNA-PK-mediated signaling pathway is required for the increase in HIF-1alpha expression through activation of HSF1 and subsequent upregulation of heat shock proteins after hypoxic reconditioning.
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Affiliation(s)
- Moon Jung Kang
- Department of Biochemistry, Pusan National University School of Medicine, Busan, South Korea
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Meng S, Lin L, Lama S, Qiao M, Tuor UI. Cerebral expression of DNA repair protein, Ku70, and its association with cell proliferation following cerebral hypoxia-ischemia in neonatal rats. Int J Dev Neurosci 2008; 27:129-34. [PMID: 19121380 DOI: 10.1016/j.ijdevneu.2008.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 10/29/2008] [Accepted: 12/04/2008] [Indexed: 01/17/2023] Open
Abstract
We hypothesized that increased Ku70 expression could be involved in recovery following cerebral hypoxia-ischemia. We investigated the progression of cerebral alterations in Ku70 expression at different time points (24 h, 72 h, 1 week, 4 weeks and 8 weeks) after hypoxia-ischemia (right carotid artery occlusion plus 1.5h of hypoxia) in neonatal rats. To determine whether in addition to its known role of DNA repair, Ku70 was associated with cell death or cell proliferation we performed double staining for Ku70 and DNA fragmentation or bromodeoxyuridine, respectively. The results show that Ku70 expression was increased in the infarct core and peri-infarct regions at 24h following hypoxia-ischemia. The increased Ku70 expression was transient in the infarct core with a loss of Ku70 positive cells over days. In contrast, in the peri-infarct region the expression of Ku70 remained increased at chronic times 8 weeks following the insult. Cells positive for DNA fragmentation were not co-localized with cells positive for Ku70 after an insult. However, most of the cells positive for bromodeoxyuridine indicative of cell proliferation were positive for Ku70 in the peri-infarct region at 8 weeks after the insult. Considering the roles of Ku70 in DNA repair or inhibiting apoptosis and its co-localization within cells that had undergone proliferation, Ku70 may be considered a potential novel target to enhance recovery following hypoxia-ischemia.
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Affiliation(s)
- Shuzhen Meng
- MR Technology, Institute for Biodiagnostics (West), Calgary, Alberta, Canada
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Bañuelos CA, Banáth JP, MacPhail SH, Zhao J, Eaves CA, O'Connor MD, Lansdorp PM, Olive PL. Mouse but not human embryonic stem cells are deficient in rejoining of ionizing radiation-induced DNA double-strand breaks. DNA Repair (Amst) 2008; 7:1471-83. [PMID: 18602349 DOI: 10.1016/j.dnarep.2008.05.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 05/08/2008] [Indexed: 01/05/2023]
Abstract
Mouse embryonic stem (mES) cells will give rise to all of the cells of the adult mouse, but they failed to rejoin half of the DNA double-strand breaks (dsb) produced by high doses of ionizing radiation. A deficiency in DNA-PK(cs) appears to be responsible since mES cells expressed <10% of the level of mouse embryo fibroblasts (MEFs) although Ku70/80 protein levels were higher than MEFs. However, the low level of DNA-PK(cs) found in wild-type cells appeared sufficient to allow rejoining of dsb after doses <20Gy even in G1 phase cells. Inhibition of DNA-PK(cs) with wortmannin and NU7026 still sensitized mES cells to radiation confirming the importance of the residual DNA-PK(cs) at low doses. In contrast to wild-type cells, mES cells lacking H2AX, a histone protein involved in the DNA damage response, were radiosensitive but they rejoined double-strand breaks more rapidly. Consistent with more rapid dsb rejoining, H2AX(-/-) mES cells also expressed 6 times more DNA-PK(cs) than wild-type mES cells. Similar results were obtained for ATM(-/-) mES cells. Differentiation of mES cells led to an increase in DNA-PK(cs), an increase in dsb rejoining rate, and a decrease in Ku70/80. Unlike mouse ES, human ES cells were proficient in rejoining of dsb and expressed high levels of DNA-PK(cs). These results confirm the importance of homologous recombination in the accurate repair of double-strand breaks in mES cells, they help explain the chromosome abnormalities associated with deficiencies in H2AX and ATM, and they add to the growing list of differences in the way rodent and human cells deal with DNA damage.
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Affiliation(s)
- C A Bañuelos
- Medical Biophysics Department, British Columbia Cancer Research Centre, 675 W. 10th Avenue, Vancouver, BC, Canada
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Barzilai A, Biton S, Shiloh Y. The role of the DNA damage response in neuronal development, organization and maintenance. DNA Repair (Amst) 2008; 7:1010-27. [DOI: 10.1016/j.dnarep.2008.03.005] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Morio T, Kim H. Ku, Artemis, and ataxia-telangiectasia-mutated: Signalling networks in DNA damage. Int J Biochem Cell Biol 2008; 40:598-603. [DOI: 10.1016/j.biocel.2007.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2007] [Revised: 12/06/2007] [Accepted: 12/17/2007] [Indexed: 01/27/2023]
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Liu QZ, Jiang GF, He Y, Wang XR, Zhou JW, Zhuang ZX. Arsenite-induced alterations in Ku70-deficient cells: a model to study genotoxic effects. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2007; 70:938-46. [PMID: 17479409 DOI: 10.1080/15287390701290253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
As one of three subunits of DNA-dependent protein kinase (DNA-PK), Ku70 protein plays an important role in repair of DNA double-strand breaks (DNA DSB). To further understand the functions of Ku70 protein and the mechanisms underlying arsenite-induced genotoxic effects, the effects of Ku70 deficiency were examined. The Ku70-deficient cell line HLFK and null vector cell line HLFC were established after recombinant plasmid of Ku70 gene antisense RNA and null pEGFP-C1 vector were transferred into human embryo lung fibroblasts (HLF) cells. Experiments were undertaken to detect DNA DSB damage by neutral single-cell gel electrophoresis assay (SCGE), chromosomal alterations by micronucleus test, and cell cycle progression by flow cytometry in HLFC and HLFK cells treated with control, 1, 2.5, 5, or 10 microM sodium arsenite for 2, 4, or 24 h, respectively. Western blot analysis results showed that Ku70 protein content in HLFK cells decreased to 38% of those in HLFC cells. The median lethal concentrations (LC50) of sodium arsenite to HLFC and HLFK cells for 24 h were 27.38 microM and 21.80 microM, respectively. Results of neutral SCGE assay showed that there were concentration-dependent increases in tail length of DNA DSB, in percent of cells with DNA DSB tails, and in severity of DNA DSB damage in HLFK and HLFC cells. The increases in these indices in HLFK cells were significantly higher than those found in HLFC cells exposed to similar amounts of metal. The ability of DNA DSB to repair in HLFK cells was less than that seen in HLFC cells. Sodium arsenite produced concentration-dependent elevation in micronuclei and abnormal nuclei formation. The Ku70-deficiency enhanced the susceptibility to chromosomal alterations induced by sodium arsenite. Low concentrations of sodium arsenite induced cell arrest at G1; however, at high concentrations of metal this G1 arrest effect disappeared. These results suggested that Ku70 protein plays an important role in repair of DNA DSB damage and for maintainance of genome stability.
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Affiliation(s)
- Qi-Zhan Liu
- Department of Molecular Cell Biology and Toxicology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China
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26
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Kim H. DNA repair Ku proteins in gastric cancer cells and pancreatic acinar cells. Amino Acids 2006; 34:195-202. [PMID: 17031478 DOI: 10.1007/s00726-006-0411-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Accepted: 08/29/2006] [Indexed: 12/18/2022]
Abstract
The DNA repair protein Ku acts as a heterodimer of Ku70 and Ku80 that binds to the DNA ends, nicks, or single-to-double-strand transition. It has a crucial role for DNA double-strand-break repair. Either Ku70 or Ku80 itself may have a unique function that is independent of the other Ku subunit. In this review, the role of Ku on cell proliferation and apoptosis will be discussed. Ku acts as a regulator of transcription by interacting with the recombination signal binding protein Jkappa and the NF-kappaB p50 homodimer to up-regulate p50 expression, which may regulate the proliferation of gastric cancer cells. Both Ku70 and Ku80 expressions are mediated by constitutively activated NF-kappaB and constitutively expressed cyclooxygenase-2 in gastric cancer cells, which may be related to gastric cell proliferation and carcinogenesis. In addition, nuclear loss of Ku may underlie the mechanism of apoptosis in pancreatic acinar cells after oxidative stress.
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Affiliation(s)
- H Kim
- Department of Food and Nutrition, Brain Korea 21 Project, College of Human Ecology and Biomolecule Secretion Research Center, Institute of Gastroenterology, College of Medicine, Yonsei University, Seoul, Korea.
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Sklavounou E, Hay A, Ashraf N, Lamb K, Brown E, Mac Intyre A, George WD, Hartley RC, Shiels PG. The use of telomere biology to identify and develop superior nitrone based anti-oxidants. Biochem Biophys Res Commun 2006; 347:420-7. [PMID: 16828709 DOI: 10.1016/j.bbrc.2006.06.087] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 06/15/2006] [Indexed: 11/28/2022]
Abstract
We have employed a biological chemistry approach to dissect the mechanisms underpinning cellular responses to oxidant stress and to develop biologically relevant anti-oxidants. We have used telomere biology to define cellular stress responses and have observed telomere independent, p21- and p16-dependent stasis following oxidative insult in human fibroblasts. This was accompanied by a [corrected] reduction in XRCC5 expression and a reduction in [corrected] SIRT 1 expression. Using these markers in conjunction with senescence-associated beta-galactosidase expression, we have developed and screened novel nitrone based anti-oxidant compounds. We have identified functional compounds that are unsuitable for use in primary human cells. This has allowed subsequent identification of suitably structured compounds that act as superior biological anti-oxidants, which have potential for use in clinical interventions.
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Affiliation(s)
- E Sklavounou
- Division of Cancer Sciences and Molecular Pathology University of Glasgow, Glasgow G12 8QQ, UK
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Shackelford DA. DNA end joining activity is reduced in Alzheimer's disease. Neurobiol Aging 2006; 27:596-605. [PMID: 15908050 DOI: 10.1016/j.neurobiolaging.2005.03.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Revised: 02/22/2005] [Accepted: 03/09/2005] [Indexed: 11/28/2022]
Abstract
Evidence indicates that oxidative stress-induced damage to DNA, protein, and other cellular components contributes to the progression of Alzheimer's disease (AD). Several studies indicate that postmitotic neurons have a reduced capacity for some types of DNA repair, which is further compromised by aging. Thus in AD, the cellular response to increased oxidative DNA damage may be inadequate to protect the genome. Mammalian cells use several mechanisms to repair DNA damage generated during normal oxidative metabolism or by genotoxic insults. The predominant mechanism to repair double strand breaks is non-homologous end joining (NHEJ) which utilizes the DNA-dependent protein kinase (DNA-PK) complex. A cell-free DNA end joining assay was employed to determine if NHEJ was reduced in nuclear cortical extracts from brains of AD versus normal subjects. This report demonstrates that end joining activity and protein levels of DNA-PK catalytic subunit are significantly lower in AD brains compared to normal controls. The amount of end joining activity correlates with the expression of DNA-PK and is dependent on DNA-PK catalytic activity. This indicates that repair of DNA double-strand breaks by the DNA-PK-dependent NHEJ pathway may be deficient in AD.
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Affiliation(s)
- Deborah A Shackelford
- Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093-0624, USA.
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29
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Merlo D, Di Stasi AMM, Bonini P, Mollinari C, Cardinale A, Cozzolino F, Wisden W, Garaci E. DNA repair in post-mitotic neurons: a gene-trapping strategy. Cell Death Differ 2005; 12:307-9. [PMID: 15665815 DOI: 10.1038/sj.cdd.4401572] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Abstract
Mammalian cells utilize multiple mechanisms to repair DNA damage that occurs during normal cellular respiration and in response to genotoxic stress. This study sought to determine if chronic oxidative stress proposed to occur during Alzheimer's disease alters the expression or activity of DNA double-strand break repair or base excision repair proteins. Double-strand break repair requires DNA-dependent protein kinase, composed of a catalytic subunit, DNA-PKcs, and a regulatory component, Ku. Ku DNA binding activity was reduced in extracts of postmortem AD midfrontal cortex, but was not significantly different from the age-matched controls. Decreased Ku DNA binding correlated with reduced protein levels of Ku subunits, DNA-PKcs, and poly(ADP-ribose) polymerase-1. Expression of the base excision repair enzyme Ref-1, however, was significantly increased in AD extracts compared to controls. Ku DNA binding and DNA-PK protein levels in the AD cases correlated significantly with synaptophysin immunoreactivity, which is a measure of synaptic loss, a major correlate of cognitive deficits in AD. Immunohistochemical analysis suggested that DNA-PK protein levels reflected both number of neurons and regulation of cellular expression.
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Affiliation(s)
- Vladislav Davydov
- Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093-0624, USA
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Song JY, Lim JW, Kim H, Morio T, Kim KH. Oxidative stress induces nuclear loss of DNA repair proteins Ku70 and Ku80 and apoptosis in pancreatic acinar AR42J cells. J Biol Chem 2003; 278:36676-87. [PMID: 12867423 DOI: 10.1074/jbc.m303692200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell death linked to oxidative DNA damage has been implicated in acute pancreatitis. The severe DNA damage, which is beyond the capacity of the DNA repair proteins, triggers apoptosis. It has been hypothesized that oxidative stress may induce a decrease in the Ku70 and Ku80 levels and apoptosis in pancreatic acinar cells. In this study, it was found that oxidative stress caused by glucose oxidase (GO) acting on beta-d-glucose, glucose/glucose oxidase (G/GO), induced slight changes in cytoplasmic Ku70 and Ku80 but drastically induced a decrease in nuclear Ku70 and Ku80 both time- and concentration-dependently in AR42J cells. G/GO induced apoptosis determined by poly(ADP-ribose) polymerase cleavage, an increase in expression of p53 and Bax, and a decrease in Bcl-2 expression. G/GO-induced apoptosis was in parallel with the loss of nuclear Ku proteins in AR42J cells. Caspase-3 inhibitor prevented G/GO-induced nuclear Ku loss and cell death. G/GO did not induce apoptosis in the cells transfected with either the Ku70 or Ku80 expression gene but increased apoptosis in those transfected with the Ku dominant negative mutant. Pulse and pulse-chase results show that G/GO induced Ku70 and Ku80 syntheses, even though Ku70 and Ku80 were degraded both in cytoplasm and nucleus. G/GO-induced decrease in Ku binding to importin alpha and importin beta reflects possible modification of nuclear import of Ku proteins. The importin beta level was not changed by G/GO. These results demonstrate that nuclear decrease in Ku70 and Ku80 may result from the decrease in Ku binding to nuclear transporter importins and the degradation of Ku proteins. The nuclear loss of Ku proteins may underlie the mechanism of apoptosis in pancreatic acinar cells after oxidative stress.
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Affiliation(s)
- Ji Yeon Song
- Department of Pharmacology and Institute of Gastroenterology, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Korea
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Shackelford DA, Yeh RY. Activation of extracellular signal-regulated kinases (ERK) during reperfusion of ischemic spinal cord. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2003; 115:173-86. [PMID: 12877988 DOI: 10.1016/s0169-328x(03)00206-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The extracellular signal-regulated kinases (ERK) participate in numerous signaling pathways and are abundantly expressed in the CNS. It has been proposed that ERK activation promotes survival in models of neuronal injury. Inhibition of MEK, the upstream kinase that activates ERK, however, leads to neuroprotection in models of cerebral ischemia and trauma, suggesting that in this context ERK activation contributes to cellular damage. The effect of ischemia and reperfusion on activity and expression of ERK was investigated using a reversible model of rabbit spinal cord ischemia. Active ERK was observed in nai;ve animals, which decreased during 15 to 60 min of ischemia. Upon reperfusion, a robust activation of ERK was observed in animals occluded for 60 min that remained permanently paraplegic. Immunohistochemical analyses revealed increased staining of phosphorylated ERK (pERK) in glial cells and faint nuclear staining in motor neurons of animals occluded for 60 min and reperfused for 18 h. In contrast ERK activity did not increase in animals occluded for 15 min that regained motor function. No evidence of increased pERK immunoreactivity in motor neurons or nuclear translocation was noted in these animals. ERK1 was demonstrated to be identical to a p46 c-Jun/ATF-2 kinase previously shown to be activated by reperfusion after a 60-min occlusion. The results suggest that activation of ERK during reperfusion of ischemic spinal cord participates in the cellular pathways leading to neuronal damage.
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Affiliation(s)
- Deborah A Shackelford
- Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093-0624, USA.
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Hou ST, MacManus JP. Molecular mechanisms of cerebral ischemia-induced neuronal death. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 221:93-148. [PMID: 12455747 DOI: 10.1016/s0074-7696(02)21011-6] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The mode of neuronal death caused by cerebral ischemia and reperfusion appears on the continuum between the poles of catastrophic necrosis and apoptosis: ischemic neurons exhibit many biochemical hallmarks of apoptosis but remain cytologically necrotic. The position on this continuum may be modulated by the severity of the ischemic insult. The ischemia-induced neuronal death is an active process (energy dependent) and is the result of activation of cascades of detrimental biochemical events that include perturbion of calcium homeostasis leading to increased excitotoxicity, malfunction of endoplasmic reticulum and mitochondria, elevation of oxidative stress causing DNA damage, alteration in proapoptotic gene expression, and activation of the effector cysteine proteases (caspases) and endonucleases leading to the final degradation of the genome. In spite of strong evidence showing that brain infarction can be reduced by inhibiting any one of the above biochemical events, such as targeting excitotoxicity, up-regulation of an antiapoptotic gene, or inhibition of a down-stream effector caspase, it is becoming clear that targeting a single gene or factor is not sufficient for stroke therapeutics. An effective neuroprotective therapy is likely to be a cocktail aimed at all of the above detrimental events evoked by cerebral ischemia and the success of such therapeutic intervention relies upon the complete elucidation of pathways and mechanisms of the cerebral ischemia-induced active neuronal death.
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Affiliation(s)
- Sheng T Hou
- Experimental Stroke Group, Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, KIA 0R6, Canada
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Liou AKF, Clark RS, Henshall DC, Yin XM, Chen J. To die or not to die for neurons in ischemia, traumatic brain injury and epilepsy: a review on the stress-activated signaling pathways and apoptotic pathways. Prog Neurobiol 2003; 69:103-42. [PMID: 12684068 DOI: 10.1016/s0301-0082(03)00005-4] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
After a severe episode of ischemia, traumatic brain injury (TBI) or epilepsy, it is typical to find necrotic cell death within the injury core. In addition, a substantial number of neurons in regions surrounding the injury core have been observed to die via the programmed cell death (PCD) pathways due to secondary effects derived from the various types of insults. Apart from the cell loss in the injury core, cell death in regions surrounding the injury core may also contribute to significant losses in neurological functions. In fact, it is the injured neurons in these regions around the injury core that treatments are targeting to preserve. In this review, we present our cumulated understanding of stress-activated signaling pathways and apoptotic pathways in the research areas of ischemic injury, TBI and epilepsy and that gathered from concerted research efforts in oncology and other diseases. However, it is obvious that our understanding of these pathways in the context of acute brain injury is at its infancy stage and merits further investigation. Hopefully, this added research effort will provide a more detailed knowledge from which better therapeutic strategies can be developed to treat these acute brain injuries.
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Affiliation(s)
- Anthony K F Liou
- Department of Neurology, University of Pittsburgh School of Medicine, S526 Biomedical Science Tower, 3500 Terrace Street, Pittsburgh, PA 15261, USA
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35
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Vanden Hoek TL, Qin Y, Wojcik K, Li CQ, Shao ZH, Anderson T, Becker LB, Hamann KJ. Reperfusion, not simulated ischemia, initiates intrinsic apoptosis injury in chick cardiomyocytes. Am J Physiol Heart Circ Physiol 2003; 284:H141-50. [PMID: 12388298 PMCID: PMC7359634 DOI: 10.1152/ajpheart.00132.2002] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although ischemia-reperfusion (I/R) can initiate apoptosis, the timing and contribution of the mitochondrial/cytochrome c apoptosis death pathway to I/R injury is unclear. We studied the timing of cytochrome c release during I/R and whether subsequent caspase activation contributes to reperfusion injury in confluent chick cardiomyocytes. One-hour simulated ischemia followed by 3-h reperfusion resulted in significant cell death, with most cell death evident during the reperfusion phase and demonstrating mitochondrial cytochrome c release within 5 min after reperfusion. By contrast, cells exposed to prolonged ischemia for 4 h had only marginally increased cell death and no detectable cytochrome c release into the cytosol. Caspase activation could not be detected after ischemia only, but it significantly increased after reperfusion. Caspase inhibitors benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, Ac-Asp-Gln-Thr-Asp-H, or benzyloxycarbonyl-Leu-Glu (Ome)-His-Asp-(Ome)-fluoromethyl ketone given only at reperfusion significantly attenuated cell death and resulted in return of contraction. Antixoxidants decreased cytochrome c release, nuclear condensation, and cell death. These results suggest that reperfusion oxidants initiate cytochrome c release within minutes, and apoptosis within hours, significant enough to increase cell death and contractile dysfunction.
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Affiliation(s)
- Terry L Vanden Hoek
- Sections of Emergency Medicine and Pulmonary/Critical Care, Department of Medicine and Emergency Resuscitation Center, University of Chicago, Illinois 60637, USA
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36
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Abstract
Recent studies using ischemia/reperfusion models of brain injury suggest that there is a period of time during which the formation of oxidative DNA lesions (ODLs) exceeds removal. This interval is a window of opportunity in which to study the effect of gene damage on gene expression in the brain, because the presence of excessive ODLs mimics a deficiency in gene repair, which has been shown to be associated with neurological disorders. Evidence from studies using similar models indicates that expression of faulty transcripts from ODL-infested genes and non-sense mutation in repaired genes occur before the process of cell death. Preventing the formation of ODLs and enhancing ODL repair are shown to increase the expression of intact transcripts and attenuate cell death. Understanding this mechanism could lead to the development of therapeutic techniques (physiologic, pharmacological, and/or genomic) that can enhance recovery.
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Affiliation(s)
- Philip K Liu
- Department of Neurosurgery, Baylor College of Medicine, Houston, Texas 77030, USA.
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Cao G, Luo Y, Nagayama T, Pei W, Stetler RA, Graham SH, Chen J. Cloning and characterization of rat caspase-9: implications for a role in mediating caspase-3 activation and hippocampal cell death after transient cerebral ischemia. J Cereb Blood Flow Metab 2002; 22:534-46. [PMID: 11973426 DOI: 10.1097/00004647-200205000-00005] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Delayed hippocampal neurodegeneration after transient global ischemia is mediated, at least in part, through the activation of terminal caspases, particularly caspase-3, and the subsequent proteolytic degradation of critical cellular proteins. Caspase-3 may be activated by the membrane receptor-initiated caspase-8-dependent extrinsic pathway and the mitochondria-initiated caspase-9-dependent intrinsic pathway; however, the precise role of these deduced apoptosis-signaling pathways in activating caspase-3 in ischemic neurons remains elusive. The authors cloned the caspase-9 gene from the rat brain and investigated its potential role in mediating ischemic neuronal death in a rat model of transient global ischemia. Caspase-9 gene expression and protease activity were extremely low in the adult brain, whereas they were developmentally upregulated in newborn rats, especially at postnatal 12 weeks, a finding consistent with the theory of an essential role for caspase-9 in neuronal apoptosis during brain development. After 15-minute transient global ischemia, caspase-9 was overexpressed and proteolytically activated in the hippocampal CA1 neurons at 8 to 72 hours of reperfusion. The temporal profile of caspase-9 activation coincided with that of cytochrome c release and caspase-3 activation, but preceded CA1 neuronal death. Immunoprecipitation experiments revealed that there was enhanced formation of Apaf-1/caspase-9 complex in the hippocampus 8 and 24 hours after ischemia. Furthermore, intracerebral ventricular infusion of the relatively specific caspase-9 inhibitor N-benzyloxycarbonyl-Leu-Glu-His-Asp-fluoro-methylketone before ischemia attenuated caspase-3-like activity and significantly enhanced neuronal survival in the CA1 sector. In contrast, inhibition of caspase-8 activity had no significant effect on caspase-3 activation or neuronal survival. These results suggest that the caspase-9-dependent intrinsic pathway may be the primary mechanism responsible for the activation of caspase-3 in ischemic hippocampal neurons.
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Affiliation(s)
- Guodong Cao
- Department of Neurology and Pittsburgh Institute of Neurological Disorders, University of Pittsburgh School of Medicine, Biomedical Science Tower, Pittsburgh, PA 15213, U.S.A
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38
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Shackelford DA, Yeh RY. Differential effects of ischemia and reperfusion on c-Jun N-terminal kinase isoform protein and activity. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 94:178-92. [PMID: 11597778 DOI: 10.1016/s0169-328x(01)00245-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Activation of the c-Jun N-terminal (JNK) or stress-activated protein kinases (SAPK) is associated with a wide range of disparate cellular responses to extracellular stimuli, including either induction of or protection from apoptosis. This study investigates the effect of ischemia and reperfusion on JNK isoform activities using a reversible rabbit spinal cord ischemia model. High basal JNK activity, attributed to the p46 JNK1 isoform, was expressed in the CNS of untreated rabbits. JNK activity decreased in the lumbar spinal cord of rabbits occluded for 15-60 min. During reperfusion animals occluded for 15 min recovered neurological function and JNK activity returned to normal levels. In contrast animals occluded for 60 min remained permanently paraplegic and JNK activity was half the control activity after 18 h of reperfusion. In these animals proteolytic fragments of JNK1 and JNK3 were observed and protein levels, but not activity, of JNK isoforms increased in a detergent-insoluble fraction. Two novel c-Jun (and ATF-2) kinase activities increased during reperfusion of animals occluded for 60 min. An activity designated p46(slow) was similar in M(r) to a JNK2 isoform induced in these animals. A second 30-kDa activity associated with the detergent-insoluble fraction co-migrated with a JNK3 N-terminal fragment. The results show that JNK1 is active in the normal CNS and increased activity is not associated with durations of ischemia and reperfusion that induce cell death. However, specific JNK isoform activation may participate in the cell death pathways as increased activity of novel c-Jun (ATF-2) kinase activities was observed in paraplegic animals.
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Affiliation(s)
- D A Shackelford
- Department of Neurosciences, University of California at San Diego, 92093-0624, USA.
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39
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Sugawara T, Noshita N, Lewén A, Kim GW, Chan PH. Neuronal expression of the DNA repair protein Ku 70 after ischemic preconditioning corresponds to tolerance to global cerebral ischemia. Stroke 2001; 32:2388-93. [PMID: 11588331 DOI: 10.1161/hs1001.097109] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND AND PURPOSE Oxidative stress after ischemia/reperfusion has been shown to induce DNA damage and subsequent DNA repair activity. Ku 70/86, multifunctional DNA repair proteins, bind to broken DNA ends and trigger a DNA repair pathway. We investigated the involvement of these proteins in the development of neuronal tolerance to global cerebral ischemia after ischemic preconditioning. METHODS Adult male Sprague-Dawley rats were subjected to either 5 minutes of lethal global ischemia with or without 3 minutes of sublethal ischemic preconditioning or 3 minutes of ischemia only. Neuronal injury was histologically assessed, and DNA damage was visualized by in situ labeling of DNA fragmentation and DNA gel electrophoresis. Ku expression was also examined by immunohistochemistry and Western blot analysis. RESULTS Hippocampal CA1 neurons underwent DNA-fragmented cell death 3 days after 5 minutes of ischemia. However, these neurons showed a strong tolerance to 5 minutes of ischemia 1 to 3 days after ischemic preconditioning. Immunohistochemistry showed virtually no constitutive expression of Ku proteins in CA1 neurons; however, ischemic preconditioning induced neuronal Ku 70 expression 1 to 3 days later. Western blot confirmed an increase in Ku 70 in this region at the same time. CONCLUSIONS The temporal and spatial expression of Ku 70 corresponded to tolerance of the hippocampal CA1 neurons to subsequent ischemia, suggesting the involvement of Ku proteins in the development of neuronal tolerance after ischemic preconditioning.
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Affiliation(s)
- T Sugawara
- Department of Neurosurgery, Program in Neurosciences, Stanford University School of Medicine, CA 94305-5487, USA
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40
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Abstract
The brain has the highest metabolic rate of all organs and depends predominantly on oxidative metabolism as a source of energy. Oxidative metabolism generates reactive oxygen species, which can damage all cellular components, including protein, lipids and nucleic acids. The processes of DNA repair normally remove spontaneous gene damage with few errors. However, cerebral ischemia followed by reperfusion leads to elevated oxidative stress and damage to genes in brain tissue despite a functional mechanism of DNA repair. These critical events occur at the same time as the expression of immediate early genes, the products of which trans-activate late effector genes that are important for sustaining neuronal viability. These findings open the possibility of applying genetic tools to identify molecular mechanisms of gene repair and to derive new therapies for stroke and brain injury.
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Affiliation(s)
- P K Liu
- Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA.
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41
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Um JH, Kang CD, Lee BG, Kim DW, Chung BS, Kim SH. Increased and correlated nuclear factor-kappa B and Ku autoantigen activities are associated with development of multidrug resistance. Oncogene 2001; 20:6048-56. [PMID: 11593412 DOI: 10.1038/sj.onc.1204732] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2001] [Revised: 06/05/2001] [Accepted: 06/14/2001] [Indexed: 11/09/2022]
Abstract
In this study, we investigated possible engagement of NF-kappaB and Ku autoantigen (Ku) activation in development of multidrug resistance (MDR) and circumvention of MDR by modulation of NF-kappaB and Ku. The NF-kappaB activity and NF-kappaB p65 subunit level were constitutively higher in MDR cells than in drug-sensitive parental cells. Interestingly, a faster running NF-kappaB DNA binding complex was identified as Ku, a DNA damage sensor and a key double strand break repair protein, and was positively correlated with the NF-kappaB activity in MDR cells and Ku- or both subunits of NF-kappaB-transfected cells. Also both NF-kappaB and Ku activities were activated or inhibited by treatment with etoposide (VP-16) or MG-132 (a proteasome inhibitor), respectively. Furthermore, PKA inhibitor suppressed markedly the constitutive and drug-induced activities of NF-kappaB and Ku in MDR cells and subsequently potentiated the cytotoxic activity of anticancer drugs. Our results proposed that the NF-kappaB and Ku activation could be one of multi-factorial MDR mechanism, and PKA inhibitor, likely via inhibition of NF-kappaB and Ku activities, could enhance the effectiveness of anticancer drugs against MDR cells with high activities of NF-kappaB and Ku.
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Affiliation(s)
- J H Um
- Department of Biochemistry, College of Medicine, Pusan National University, Pusan 602-739, South Korea
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42
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Cassada DC, Tribble CG, Laubach VE, Nguyen BN, Rieger JM, Linden J, Kaza AK, Long SM, Kron IL, Kern JA. An adenosine A2A agonist, ATL-146e, reduces paralysis and apoptosis during rabbit spinal cord reperfusion. J Vasc Surg 2001; 34:482-8. [PMID: 11533601 DOI: 10.1067/mva.2001.117996] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND We hypothesized that systemic ATL-146e, an adenosine A(2A) agonist, would decrease spinal cord reperfusion inflammatory stress and inhibit apoptosis and that these effects would correlate with improved neurologic functional outcome. METHODS Thirty rabbits underwent cross-clamping of the infrarenal aorta for 45 minutes. One group of animals (n = 14) received 0.06 microg/kg per minute of ATL-146e infused intravenously for 3 hours, beginning 15 minutes before reperfusion. A second group of animals (n = 16) underwent spinal cord ischemia with saline vehicle alone and served as ischemic controls. Animals (n = 9, 11) from each group survived for 48 hours and assessed for neurologic impairment with the Tarlov (0-5) scoring system. Four animals from each group were humanely killed at the end of the 3-hour treatment period, and the remainder killed after 48 hours' survival. In all animals, lumbar spinal cord tissue specimens were frozen for subsequent Western blot analysis of heat shock protein 70 (HSP 70), and for the p85 fragment of poly (ADP-ribose) polymerase (PARP). Neuronal viability indices were determined at 48 hours with hematoxylin and eosin staining. RESULTS There was improvement in neurologic function in rabbits receiving ATL-146e (P <.001) compared with ischemic controls. At the end of the 3-hour treatment period there was a 46% (P <.05) decrease in HSP 70 expression in the ATL-146e group compared with the control group, but no difference in PARP expression. At 48 hours, there was no difference between control and ATL-146e groups in HSP 70 expression, but there was a 65% (P <.05) reduction in PARP in the spinal cords of animals that had received ATL-146e. There was a significant improvement in neuronal viability indices in animals receiving ATL-146e compared with ischemic controls (P <.05). CONCLUSIONS Systemic ATL-146e infusion during reperfusion after spinal cord ischemia results in preservation of hindlimb motor function. There is evidence of decreased spinal cord inflammatory stress immediately after treatment with ATL-146e as indicated by reduced HSP 70 induction. Treatment with ATL-146e is associated with a reduction in neuronal apoptosis as suggested by a substantial decrease in the fragmentation of PARP at 48 hours. These results suggest that inflammation during reperfusion and subsequent apoptosis contribute to paralysis after restoration of blood flow to the ischemic spinal cord.
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Affiliation(s)
- D C Cassada
- Department of Surgery, Division of Thoracic and Cardiovascular Surgery, The University of Virginia Health System, Charlottesville 22908, USA
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Cao G, Pei W, Lan J, Stetler RA, Luo Y, Nagayama T, Graham SH, Yin XM, Simon RP, Chen J. Caspase-activated DNase/DNA fragmentation factor 40 mediates apoptotic DNA fragmentation in transient cerebral ischemia and in neuronal cultures. J Neurosci 2001; 21:4678-90. [PMID: 11425895 PMCID: PMC6762351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2001] [Revised: 04/17/2001] [Accepted: 04/18/2001] [Indexed: 02/20/2023] Open
Abstract
Nuclear changes, including internucleosomal DNA fragmentation, are characteristic features of neuronal apoptosis resulting from transient cerebral ischemia and related brain insults for which the molecular mechanism has not been elucidated. Recent studies suggest that a caspase-3-mediated mechanism may be involved in the process of nuclear degradation in ischemic neurons. In this study, we cloned from rat brain a homolog cDNA encoding caspase-activated deoxyribonuclease (CAD)/DNA fragmentation factor 40 (DFF40), a 40 kDa nuclear enzyme that is activated by caspase-3 and promotes apoptotic DNA degradation. Subsequently, we investigated the role of CAD/DFF40 in the induction of internucleosomal DNA fragmentation in the hippocampus in a rat model of transient global ischemia and in primary neuronal cultures under ischemia-like conditions. At 8-72 hr after ischemia, CAD/DFF40 mRNA and protein were induced in the degenerating hippocampal CA1 neurons. CAD/DFF40 formed a heterodimeric complex in the nucleus with its natural inhibitor CAD (ICAD) and was activated after ischemia in a delayed manner (>24 hr) by caspase-3, which translocated into the nucleus and cleaved ICAD. Furthermore, an induced CAD/DFF40 activity was detected in nuclear extracts in both in vivo and in vitro models, and the DNA degradation activity of CAD/DFF40 was inhibited by purified ICAD protein. These results strongly suggest that CAD/DFF40 is the endogenous endonuclease that mediates caspase-3-dependent internucleosomal DNA degradation and related nuclear alterations in ischemic neurons.
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Affiliation(s)
- G Cao
- Department of Neurology, Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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44
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Chen M, Kochanek PM, Watkins SC, Jin KL, Draviam R, Nathaniel PD, Pinto R, Marion DW, Graham SH. Detection of single- and double-strand DNA breaks after traumatic brain injury in rats: comparison of in situ labeling techniques using DNA polymerase I, the Klenow fragment of DNA polymerase I, and terminal deoxynucleotidyl transferase. J Neurotrauma 2001; 18:675-89. [PMID: 11497094 DOI: 10.1089/089771501750357627] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
DNA damage is a common sequela of traumatic brain injury (TBI). Available techniques for the in situ identification of DNA damage include DNA polymerase I-mediated biotin-dATP nick-translation (PANT), the Klenow fragment of DNA polymerase I-mediated biotin-dATP nick-end labeling (Klenow), and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). While TUNEL has been widely utilized to detect primarily double-strand DNA breaks, the use of PANT to detect primarily single-strand DNA breaks and Klenow to detect both single- and double-strand DNA breaks has not been reported after TBI. Accordingly, coronal brain sections from naive rats and rats at 0, 0.5, 1, 2, 6, 24, and 72 h (n = 3-5/group) after controlled cortical impact with imposed secondary insult were processed using the PANT, Klenow, and TUNEL methods. Cells with DNA breaks were detected by PANT in the ipsilateral hemisphere as early as 0.5 h after injury and were maximal at 6 h (cortex = 66.3+/-15.8, dentate gyrus 58.6+/-12.8, CA1 = 15.8+/-5.9, CA3 = 12.8+/-4.2 cells/x 400 field, mean +/- SEM, all p < 0.05 versus naive). Cells with DNA breaks were detected by Klenow as early as 30 min and were maximal at 24 h (cortex = 56.3+/-14.3, dentate gyrus 78.0+/-16.7, CA1 = 25.8+/-4.7, CA3 = 29.3+/-15.1 cells/x 400 field, all p < 0.05 versus naive). Cells with DNA breaks were not detected by TUNEL until 2 h and were maximal at 24 h (cortex = 47.7+/-21.4, dentate gyrus 63.0+/-11.9, CA1 = 5.6+/-5.4, CA3 = 6.9+/-3.7 cells/x 400 field, cortex and dentate gyrus p < 0.05 versus naive). Dual-label immunofluorescence revealed that PANT-positive cells were predominately neurons. These data demonstrate that TBI results in extensive DNA damage, which includes both single- and double-strand breaks in injured cortex and hippocampus. The presence of multiple types of DNA breaks implicate several pathways in the evolution of DNA damage after TBI.
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Kim GW, Noshita N, Sugawara T, Chan PH. Early decrease in dna repair proteins, Ku70 and Ku86, and subsequent DNA fragmentation after transient focal cerebral ischemia in mice. Stroke 2001; 32:1401-7. [PMID: 11387505 DOI: 10.1161/01.str.32.6.1401] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Ku70 and Ku86, multifunctional DNA repair proteins, bind to broken DNA ends, including double-strand breaks, and trigger a DNA repair pathway. To investigate the involvement of these proteins in DNA fragmentation after ischemia/reperfusion, Ku protein expression was examined before and after transient focal cerebral ischemia (FCI) in mice. METHODS Adult male CD-1 mice were subjected to 60 minutes of FCI by intraluminal suture blockade of the middle cerebral artery. Ku protein expression was studied by immunohistochemistry and Western blot analysis. DNA fragmentation was evaluated by gel electrophoresis and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). The spatial relationship between Ku expression and DNA fragmentation was examined by double labeling with Ku and TUNEL after reperfusion. RESULTS Immunohistochemistry showed constitutive expression of Ku proteins in control brains. The number of Ku-expressing cells was decreased in the entire middle cerebral artery territory as early as 4 hours after reperfusion and remained reduced until 24 hours. Western blot analyses confirmed the significant reduction of these proteins (59.4% and 57.7% reduction in optical density at 4 hours of reperfusion from the normal level of Ku70 and Ku86 bands, respectively; P<0.001). DNA gel electrophoresis demonstrated DNA laddering 24 hours after reperfusion, but not at 4 hours. Double staining with Ku and TUNEL showed a concomitant loss of Ku immunoreactivity and TUNEL-positive staining. CONCLUSIONS These results suggest that the early reduction of Ku proteins and the loss of defense against DNA damage may underlie the mechanism of DNA fragmentation after FCI.
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Affiliation(s)
- G W Kim
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
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46
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Cao G, Minami M, Pei W, Yan C, Chen D, O'Horo C, Graham SH, Chen J. Intracellular Bax translocation after transient cerebral ischemia: implications for a role of the mitochondrial apoptotic signaling pathway in ischemic neuronal death. J Cereb Blood Flow Metab 2001; 21:321-33. [PMID: 11323518 DOI: 10.1097/00004647-200104000-00001] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Activation of terminal caspases such as caspase-3 plays an important role in the execution of neuronal cell death after transient cerebral ischemia. Although the precise mechanism by which terminal caspases are activated in ischemic neurons remains elusive, recent studies have postulated that the mitochondrial cell death-signaling pathway may participate in this process. The bcl-2 family member protein Bax is a potent proapoptotic molecule that, on translocation from cytosol to mitochondria, triggers the activation of terminal caspases by increasing mitochondrial membrane permeability and resulting in the release of apoptosis-promoting factors, including cytochrome c. In the present study, the role of intracellular Bax translocation in ischemic brain injury was investigated in a rat model of transient focal ischemia (30 minutes) and reperfusion (1 to 72 hours). Immunochemical studies revealed that transient ischemia induced a rapid translocation of Bax from cytosol to mitochondria in caudate neurons, with a temporal profile and regional distribution coinciding with the mitochondrial release of cytochrome c and caspase-9. Further, in postischemic caudate putamen in vivo and in isolated brain mitochondria in vitro, the authors found enhanced heterodimerization between Bax and the mitochondrial membrane permeabilization-related proteins adenine nucleotide translocator (ANT) and voltage-dependent anion channel. The ANT inhibitor bongkrekic acid prevented Bax and ANT interactions and inhibited Bax-triggered caspase-9 release from isolated brain mitochondria in vitro. Bongkrekic acid also offered significant neuroprotection against ischemia-induced caspase-3 and caspase-9 activation and cell death in the brain. These results strongly suggest that the Bax-mediated mitochondrial apoptotic signaling pathway may play an important role in ischemic neuronal injury.
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Affiliation(s)
- G Cao
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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Lapchak PA, Araujo DM, Shackelford DA, Zivin JA. Prosaptide exacerbates ischemia-induced behavioral deficits in vivo; an effect that does not involve mitogen-activated protein kinase activation. Neuroscience 2001; 101:811-4. [PMID: 11113331 DOI: 10.1016/s0306-4522(00)00466-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Prosaposin is a 517 amino acid membrane component and secreted protein(5,7,9) that is proteolytically cleaved to generate the four small glycoproteins; saposins A, B, C and D.(9,13,19) Prosaposin's ability to promote neurite outgrowth(31) and to protect neurons from programmed cell death(28) in vitro, as well as to rescue neurons from ischemia and other damage in vivo(11,12,15,25) implied that prosaposin was neurotrophic/neuroprotectant.(1,7,24,31) The neurotrophic sequence of prosaposin was isolated to smaller peptide fragments termed prosaptides(15,31) within the amino terminal portion of saposin C.(1,6,8,10,17,20,21,28) The proposed use of synthetic prosaptides as peripherally administered neuroprotective and/or neurotrophic therapeutic agents has stemmed from their ability to cross the blood-brain barrier,(27) as well as their reported neurotrophic activity in vitro.(15,23,31) Few studies, however, have attempted to characterize these peptides, presumably due to their reported instability following peripheral administration.(27) With the recent design of a stable 11-mer retro-inverso prosaptide,(15,31) it has become feasible to investigate the pharmacological effects of a stable version of these peptides in the validated rabbit spinal cord ischemia model that has been used extensively in the development of therapeutics to treat ischemic stroke.(4,14,16,18) Our results show not only that prosaptide was not neurotrophic/neuroprotectant in vivo, but rather it worsened ischemia-induced behavioral deficits.
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Affiliation(s)
- P A Lapchak
- University of California San Diego, Department of Neuroscience, MTF 316, 9500 Gilman Drive, La Jolla CA 92093-0624, USA.
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Culmsee C, Bondada S, Mattson MP. Hippocampal neurons of mice deficient in DNA-dependent protein kinase exhibit increased vulnerability to DNA damage, oxidative stress and excitotoxicity. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 87:257-62. [PMID: 11245929 DOI: 10.1016/s0169-328x(01)00008-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
DNA damage has been documented in neurodegenerative conditions ranging from Alzheimer's disease to stroke. DNA-dependent protein kinase (DNA-PK) is involved in V(D)J recombination and DNA double strand break repair, and may play a role in cell death induced by DNA damage. We now report that cultured hippocampal neurons from severe combined immunodeficient (scid) mice which lack DNA-PK activity are hypersensitive to apoptosis induced by exposure to topoisomerase inhibitors, amyloid beta peptide (A beta) and glutamate. A similar increased vulnerability of hippocampal CA1 and CA3 neurons was observed in adult scid mice after kainate-induced seizures. Our results suggest that DNA-PK activity is important for neuron survival under conditions that may occur in neurological disorders.
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Affiliation(s)
- C Culmsee
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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49
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Lin LH, Cao S, Yu L, Cui J, Hamilton WJ, Liu PK. Up-regulation of base excision repair activity for 8-hydroxy-2'-deoxyguanosine in the mouse brain after forebrain ischemia-reperfusion. J Neurochem 2000; 74:1098-105. [PMID: 10693941 PMCID: PMC2726712 DOI: 10.1046/j.1471-4159.2000.741098.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The repair enzyme 8-oxoguanine glycosylase/ apyrimidinic/apurinic lyase (OGG) removes 8-hydroxy-2'deoxyguanosine (oh8dG) in human cells. Our goal was to examine oh8dG-removing activity in the cell nuclei of male C57BL/6 mouse brains treated with either forebrain ischemia-reperfusion (FblR) or sham operations. We found that the OGG activity in nuclear extracts, under the condition in which other nucleases did not destroy the oligodeoxynucleotide duplex, excised oh8dG with the greatest efficiency on the oligodeoxynucleotide duplex containing oh8dG/dC and with less efficiency on the heteroduplex containing oh8dG/dT, oh8dG/dG, or oh8dG/dA. This specificity was the same as for the recombinant type 1 OGG (OGG1) of humans. We observed that the OGG1 peptide and its activity in the mouse brain were significantly increased after 90 min of ischemia and 20-30 min of reperfusion. The increase in the protein level and in the activity of brain OGG1 correlated positively with the elevation of FblR-induced DNA lesions in an indicator gene (the c-fos gene) of the brain. The data suggest a possibility that the OGG1 protein may excise oh8dG in the mouse brain and that the activity of OGG1 may have a functional role in reducing oxidative gene damage in the brain after FblR.
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Affiliation(s)
- L H Lin
- Department of Neurosurgery, Baylor College of Medicine, Houston, Texas 77030, USA
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