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Islam MZ, Shackelford RE. Pioglitazone treatment increases the cellular acid-labile and protein-bound sulfane sulfur fractions. Biochem Biophys Res Commun 2023; 670:79-86. [PMID: 37285721 DOI: 10.1016/j.bbrc.2023.05.118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 05/29/2023] [Indexed: 06/09/2023]
Abstract
BACKGROUND Iron-sulfur clusters play a central role in cellular function and are regulated by the ATM protein. Iron-sulfur clusters are part of the cellular sulfide pool, which functions to maintain cardiovascular health, and consists of free hydrogen sulfide, iron-sulfur clusters, protein bound sulfides, which constitute the total cellular sulfide fraction. ATM protein signaling and the drug pioglitazone share some cellular effects, which led us to examine the effects of this drug on cellular iron-sulfur cluster formation. Additionally, as ATM functions in the cardiovasculature and its signaling may be diminished in cardiovascular disease, we examined pioglitazone in the same cell type, with and without ATM protein expression. METHODS We examined the effects of pioglitazone treatment on the total cellular sulfide profile, the glutathione redox state, cystathionine gamma-lyase enzymatic activity, and on double-stranded DNA break formation in cells with and without ATM protein expression. RESULTS Pioglitazone increased the acid-labile (iron-sulfur cluster) and bound sulfur cellular fractions and reduced cystathionine gamma-lyase enzymatic activity in cells with and without ATM protein expression. Interestingly, pioglitazone also increased reduced glutathione and lowered DNA damage in cells without ATM protein expression, but not in ATM wild-type cells. These results are interesting as the acid-labile (iron-sulfur cluster), bound sulfur cellular fractions, and reduced glutathione are low in cardiovascular disease. CONCLUSION Here we found that pioglitazone increased the acid-labile (iron-sulfur cluster) and bound sulfur cellular fractions, impinges on hydrogen sulfide synthesis, and exerts beneficial effect on cells with deficient ATM protein signaling. Thus, we show a novel pharmacologic action for pioglitazone.
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Affiliation(s)
- Mohammad Z Islam
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, LA, 71130, United States
| | - Rodney E Shackelford
- Department of Pathology, University of South Alabama, 2451 University Hospital Dr, Mobile, AL, 37717, United States.
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Islam MZ, Shen X, Pardue S, Kevil CG, Shackelford RE. The ataxia-telangiectasia mutated gene product regulates the cellular acid-labile sulfide fraction. DNA Repair (Amst) 2022; 116:103344. [PMID: 35696854 PMCID: PMC11118069 DOI: 10.1016/j.dnarep.2022.103344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/30/2022] [Accepted: 05/11/2022] [Indexed: 11/03/2022]
Abstract
The ataxia-telangiectasia mutated (ATM) protein regulates cell cycle checkpoints, the cellular redox state, and double-stranded DNA break repair. ATM loss causes the disorder ataxia-telangiectasia (A-T), distinguished by ataxia, telangiectasias, dysregulated cellular redox and iron responses, and an increased cancer risk. We examined the sulfur pool in A-T cells, with and without an ATM expression vector. While free and bound sulfide levels were not changed with ATM expression, the acid-labile sulfide faction was significantly increased. ATM expression also increased cysteine desulfurase (NFS1), NFU1 iron-sulfur cluster scaffold homolog protein, and several mitochondrial complex I proteins' expression. Additionally, ATM expression suppressed cystathionine β-synthase and cystathionine γ-synthase protein expression, cystathionine γ-synthase enzymatic activity, and increased the reduced to oxidized glutathione ratio. This last observation is interesting, as dysregulated glutathione is implicated in A-T pathology. As ATM expression increases the expression of proteins central in initiating 2Fe-2S and 4Fe-4S cluster formation (NFS1 and NFU1, respectively), and the acid-labile sulfide faction is composed of sulfur incorporated into Fe-S clusters, our data indicates that ATM regulates aspects of Fe-S cluster biosynthesis, the transsulfuration pathway, and glutathione redox cycling. Thus, our data may explain some of the redox- and iron-related pathologies seen in A-T.
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Affiliation(s)
- Mohammad Z Islam
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, LA 71130, United States
| | - Xinggui Shen
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, LA 71130, United States
| | - Sibile Pardue
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, LA 71130, United States
| | - Christopher G Kevil
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, LA 71130, United States
| | - Rodney E Shackelford
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, LA 71130, United States.
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Proshkina E, Shaposhnikov M, Moskalev A. Genome-Protecting Compounds as Potential Geroprotectors. Int J Mol Sci 2020; 21:E4484. [PMID: 32599754 PMCID: PMC7350017 DOI: 10.3390/ijms21124484] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 02/06/2023] Open
Abstract
Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.
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Affiliation(s)
- Ekaterina Proshkina
- Laboratory of Geroprotective and Radioprotective Technologies, Institute of Biology, Komi Science Centre, Ural Branch, Russian Academy of Sciences, 28 Kommunisticheskaya st., 167982 Syktyvkar, Russia; (E.P.); (M.S.)
| | - Mikhail Shaposhnikov
- Laboratory of Geroprotective and Radioprotective Technologies, Institute of Biology, Komi Science Centre, Ural Branch, Russian Academy of Sciences, 28 Kommunisticheskaya st., 167982 Syktyvkar, Russia; (E.P.); (M.S.)
| | - Alexey Moskalev
- Laboratory of Geroprotective and Radioprotective Technologies, Institute of Biology, Komi Science Centre, Ural Branch, Russian Academy of Sciences, 28 Kommunisticheskaya st., 167982 Syktyvkar, Russia; (E.P.); (M.S.)
- Pitirim Sorokin Syktyvkar State University, 55 Oktyabrsky prosp., 167001 Syktyvkar, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
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Thadathil N, Hori R, Xiao J, Khan MM. DNA double-strand breaks: a potential therapeutic target for neurodegenerative diseases. Chromosome Res 2019; 27:345-364. [PMID: 31707536 PMCID: PMC7934912 DOI: 10.1007/s10577-019-09617-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/08/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022]
Abstract
The complexity of neurodegeneration restricts the ability to understand and treat the neurological disorders affecting millions of people worldwide. Therefore, there is an unmet need to develop new and more effective therapeutic strategies to combat these devastating conditions and that will only be achieved with a better understanding of the biological mechanism associated with disease conditions. Recent studies highlight the role of DNA damage, particularly, DNA double-strand breaks (DSBs), in the progression of neuronal loss in a broad spectrum of human neurodegenerative diseases. This is not unexpected because neurons are prone to DNA damage due to their non-proliferative nature and high metabolic activity. However, it is not clear if DSBs is a primary driver of neuronal loss in disease conditions or simply occurs concomitant with disease progression. Here, we provide evidence that supports a critical role of DSBs in the pathogenesis of the neurodegenerative diseases. Among different kinds of DNA damages, DSBs are the most harmful and perilous type of DNA damage and can lead to cell death if left unrepaired or repaired with error. In this review, we explore the current state of knowledge regarding the role of DSBs repair mechanisms in preserving neuronal function and survival and describe how DSBs could drive the molecular mechanisms resulting in neuronal death in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. We also discuss the potential implications of DSBs as a novel therapeutic target and prognostic marker in patients with neurodegenerative conditions.
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Affiliation(s)
- Nidheesh Thadathil
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Roderick Hori
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jianfeng Xiao
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Mohammad Moshahid Khan
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
- Division of Rehabilitation Sciences and Department of Physical Therapy, College of Health Professions, University of Tennessee Health Science Center, Memphis, TN, USA.
- Department of Neurology, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
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Chen J, Shen X, Pardue S, Meram AT, Rajendran S, Ghali GE, Kevil CG, Shackelford RE. The Ataxia telangiectasia-mutated and Rad3-related protein kinase regulates cellular hydrogen sulfide concentrations. DNA Repair (Amst) 2018; 73:55-63. [PMID: 30470507 DOI: 10.1016/j.dnarep.2018.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 12/16/2022]
Abstract
The ataxia telangiectasia-mutated and Rad3-related (ATR) serine/threonine kinase plays a central role in the repair of replication-associated DNA damage, the maintenance of S and G2/M-phase genomic stability, and the promotion of faithful mitotic chromosomal segregation. A number of stimuli activate ATR, including persistent single-stranded DNA at stalled replication folks, R loop formation, hypoxia, ultraviolet light, and oxidative stress, leading to ATR-mediated protein phosphorylation. Recently, hydrogen sulfide (H2S), an endogenous gasotransmitter, has been found to regulate multiple cellular processes through complex redox reactions under similar cell stress environments. Three enzymes synthesize H2S: cystathionine-β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase. Since H2S can under some conditions cause DNA damage, we hypothesized that ATR activity may regulate cellular H2S concentrations and H2S-syntheszing enzymes. Here we show that human colorectal cancer cells carrying biallelic knock-in hypomorphic ATR mutations have lower cellular H2S concentrations than do syngeneic ATR wild-type cells, and all three H2S-synthesizing enzymes show lower protein expression in the ATR hypomorphic mutant cells. Additionally, ATR serine 428 phosphorylation is altered by H2S donor and H2S synthesis enzyme inhibition, while the oxidative-stress induced phosphorylation of the ATR-regulated protein CHK1 on serine 345 is increased by H2S synthesis enzyme inhibition. Lastly, inhibition of H2S production potentiated oxidative stress-induced double-stranded DNA breaks in the ATR hypomorphic mutant compared to ATR wild-type cells. Our findings demonstrate that the ATR kinase regulates and is regulated by H2S.
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Affiliation(s)
- Jie Chen
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, Louisiana, 71130, United States
| | - Xinggui Shen
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, Louisiana, 71130, United States
| | - Sibile Pardue
- Department of Cell Biology & Anatomy, LSU Health Sciences Center Shreveport, Shreveport, Louisiana, 71130, United States
| | - Andrew T Meram
- Head & Neck Oncologic/Microvascular Reconstructive Surgery Department of Oral & Maxillofacial/Head & Neck Surgery, Louisiana State University Health Sciences Center, Shreveport, LA, United States
| | - Saranya Rajendran
- Department of Cell Biology & Anatomy, LSU Health Sciences Center Shreveport, Shreveport, Louisiana, 71130, United States
| | - Ghali E Ghali
- Head & Neck Oncologic/Microvascular Reconstructive Surgery Department of Oral & Maxillofacial/Head & Neck Surgery, Louisiana State University Health Sciences Center, Shreveport, LA, United States
| | - Christopher G Kevil
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, Louisiana, 71130, United States; Department of Cell Biology & Anatomy, LSU Health Sciences Center Shreveport, Shreveport, Louisiana, 71130, United States.
| | - Rodney E Shackelford
- Department of Pathology & Translational Pathobiology, LSU Health Sciences Center Shreveport, Shreveport, Louisiana, 71130, United States.
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Apostolakis S, Kypraiou AM. Iron in neurodegenerative disorders: being in the wrong place at the wrong time? Rev Neurosci 2018; 28:893-911. [PMID: 28792913 DOI: 10.1515/revneuro-2017-0020] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/02/2017] [Indexed: 12/22/2022]
Abstract
Brain iron deposits have been reported consistently in imaging and histologic examinations of patients with neurodegenerative disorders. While the origins of this finding have not been clarified yet, it is speculated that impaired iron homeostasis or deficient transport mechanisms result in the accumulation of this highly toxic metal ultimately leading to formation of reactive oxygen species and cell death. On the other hand, there are also those who support that iron is just an incidental finding, a by product of neuronal loss. A literature review has been performed in order to present the key findings in support of the iron hypothesis of neurodegeneration, as well as to identify conditions causing or resulting from iron overload and compare and contrast their features with the most prominent neurodegenerative disorders. There is an abundance of experimental and observational findings in support of the hypothesis in question; however, as neurodegeneration is a rare incident of commonly encountered iron-associated disorders of the nervous system, and this metal is found in non-neurodegenerative disorders as well, it is possible that iron is the result or even an incidental finding in neurodegeneration. Understanding the underlying processes of iron metabolism in the brain and particularly its release during cell damage is expected to provide a deeper understanding of the origins of neurodegeneration in the years to come.
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The interaction of iron and the genome: For better and for worse. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2017; 774:25-32. [DOI: 10.1016/j.mrrev.2017.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 07/28/2017] [Accepted: 09/12/2017] [Indexed: 12/11/2022]
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Eid R, Arab NTT, Greenwood MT. Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:399-430. [PMID: 27939167 DOI: 10.1016/j.bbamcr.2016.12.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/08/2016] [Accepted: 12/04/2016] [Indexed: 12/11/2022]
Abstract
Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe2+) and ferric (Fe3+) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.
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Affiliation(s)
- Rawan Eid
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Nagla T T Arab
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Michael T Greenwood
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada.
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Lavin MF, Yeo AJ, Kijas AW, Wolvetang E, Sly PD, Wainwright C, Sinclair K. Therapeutic targets and investigated treatments for Ataxia-Telangiectasia. Expert Opin Orphan Drugs 2016. [DOI: 10.1080/21678707.2016.1254618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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10
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Brochier C, Langley B. Chromatin modifications associated with DNA double-strand breaks repair as potential targets for neurological diseases. Neurotherapeutics 2013; 10:817-30. [PMID: 24072514 PMCID: PMC3805873 DOI: 10.1007/s13311-013-0210-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The integrity of the genome is continuously challenged by both endogenous and exogenous DNA damaging agents. Neurons, due to their post-mitotic state, high metabolism, and longevity are particularly prone to the accumulation of DNA lesions. Indeed, DNA damage has been suggested as a major contributor to both age-associated neurodegenerative diseases and acute neurological injury. The DNA damage response is a key factor in maintaining genome integrity. It relies on highly dynamic posttranslational modifications of the chromatin and DNA repair proteins to allow signaling, access, and repair of the lesion. Drugs that modulate the activity of the enzymes responsible for these modifications have emerged as attractive therapeutic compounds to treat neurodegeneration. In this review, we discuss the role of DNA double-strand breaks and abnormal chromatin modification patterns in a range of neurodegenerative conditions, and the chromatin modifiers that might ameliorate them. Finally, we suggest that understanding the epigenetic modifications specific to neuronal DNA repair is crucial for the development of efficient neurotherapeutic strategies.
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Affiliation(s)
- Camille Brochier
- The Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY, 10605, USA,
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Abstract
Understanding the role of oxidative injury will allow for therapy with agents that scavenge ROS (reactive oxygen species) and antioxidants in the management of several diseases related to free radical damage. The majority of free radicals are generated by mitochondria as a consequence of the mitochondrial cycle, whereas free radical accumulation is limited by the action of a variety of antioxidant processes that reside in every cell. In the present review, we provide an overview of the mitochondrial generation of ROS and discuss the role of ROS in the regulation of endothelial and adipocyte function. Moreover, we also discuss recent findings on the role of ROS in sepsis, cerebral ataxia and stroke. These results provide avenues for the therapeutic potential of antioxidants in a variety of diseases.
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Semlitsch M, Shackelford RE, Zirkl S, Sattler W, Malle E. ATM protects against oxidative stress induced by oxidized low-density lipoprotein. DNA Repair (Amst) 2011; 10:848-60. [PMID: 21669554 PMCID: PMC3154283 DOI: 10.1016/j.dnarep.2011.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 04/15/2011] [Accepted: 05/10/2011] [Indexed: 11/29/2022]
Abstract
Chronic oxidative stress is involved in the pathogenesis of multiple inflammatory diseases, including cardiovascular disease and atherosclerosis. The rare autosomal recessive disorder Ataxia-telangiectasia (A-T) is characterized by progressive cerebellar ataxia secondary to Purkinje cell death, immunodeficiency, and increased cancer incidence. ATM, the protein mutated in A-T, plays a key role in cellular DNA-damage responses. A-T cells show poor cellular anti-oxidant defences and increased oxidant sensitivity compared to normal cells, and ATM functions, in part, as an oxidative stress sensor. The oxidation of low-density lipoprotein (oxLDL) and its uptake by macrophages is an initiating step in the development of atherosclerosis. We demonstrate that oxLDL activates ATM and downstream p21 expression in normal fibroblasts and endothelial cells. In ATM-deficient fibroblasts oxLDL induces DNA double-strand breaks, micronuclei formation and causes chromosome breaks. Furthermore, oxLDL decreases cell viability and inhibits colony formation in A-T fibroblasts more effectively as compared to normal controls. Formation of oxLDL-induced reactive oxygen species is significantly higher in A-T, than normal fibroblasts. Last, pre-treatment of cells with ammonium pyrrolidine dithiocarbamate, a potent antioxidant and inhibitor of transcription factor nuclear factor κB, reduces oxLDL-induced reactive oxygen species formation. Our data indicates that ATM functions in the defence against oxLDL-mediated cytotoxicity.
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Affiliation(s)
- Michaela Semlitsch
- Institute of Molecular Biology and Biochemistry, Center for Molecular Medicine, Medical University of Graz, Harrachgasse 21, A-8010 Graz, Austria
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McDonald CJ, Ostini L, Wallace DF, John AN, Watters DJ, Subramaniam VN. Iron loading and oxidative stress in the Atm-/- mouse liver. Am J Physiol Gastrointest Liver Physiol 2011; 300:G554-60. [PMID: 21292994 DOI: 10.1152/ajpgi.00486.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ataxia-Telangiectasia (A-T) is an autosomal recessive disorder resulting in a myriad of abnormalities, including progressive neurodegeneration and cancer predisposition. At the cellular level, A-T is a disease of chronic oxidative stress (OS) causing damage to proteins, lipids, and DNA. OS is contributed to by pro-oxidative transition metals such as iron that catalyze the conversion of weakly reactive oxygen species to highly reactive hydroxyl radicals. Iron-associated OS has been linked to neurodegeneration in Alzheimer's and Parkinson's diseases and development of lymphoid tumors (which afflict ∼30% of A-T patients). To investigate iron regulation in A-T, iron indexes, regulatory genes, and OS markers were studied in livers of wild-type and Ataxia telangiectasia mutated (Atm) null mice on control or high-iron diets. Atm(-/-) mice had increased serum iron, hepatic iron, and ferritin and significantly higher Hepcidin compared with wild-type mice. When challenged with the high-iron diet, Bmp6 and Hfe expression was significantly increased. Atm(-/-) mice had increased protein tyrosine nitration and significantly higher Heme Oxygenase (decycling) 1 levels that were substantially increased by a high-iron diet. Ferroportin gene expression was significantly increased; however, protein levels were unchanged. We demonstrate that Atm(-/-) mice have a propensity to accumulate iron that is associated with a significant increase in hepatic OS. The iron-induced increase in hepcidin peptide in turn suppresses ferroportin protein levels, thus nullifying the upregulation of mRNA expression in response to increased OS. Our results suggest that increased iron status may contribute to the chronic OS seen in A-T patients and development of disease pathology.
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Affiliation(s)
- Cameron J McDonald
- Membrane Transport Laboratory, Division of Cancer and Cell Biology, Queensland Institute of Medical Research, Brisbane, QLD, Australia
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Cheng WH. Impact of inorganic nutrients on maintenance of genomic stability. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2009; 50:349-360. [PMID: 19326466 DOI: 10.1002/em.20489] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Maintenance of genome stability is of fundamental importance for counteracting carcinogenesis. Many human genome instability syndromes exhibit a predisposition to cancer. An increasing body of epidemiological evidence has suggested a link between nutrient status and risk of cancer. Like other chemicals, nutrients can be toxic when consumed in excess. It has become clear that both nutritional deficiency and toxicity can compromise the integrity of the genome. This article focuses on roles of inorganic trace nutrients, including selenium, copper, zinc, and iron, in the redox regulation of genome stability and how they relate to the pathologies of genomic instability syndromes and cancer.
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Affiliation(s)
- Wen-Hsing Cheng
- Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20742, USA.
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Berni A, Meschini R, Filippi S, Palitti F, De Amicis A, Chessa L. l-Carnitine enhances resistance to oxidative stress by reducing DNA damage in Ataxia telangiectasia cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2008; 650:165-74. [DOI: 10.1016/j.mrgentox.2007.11.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 10/22/2007] [Accepted: 11/21/2007] [Indexed: 10/22/2022]
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Ambrose M, Goldstine JV, Gatti RA. Intrinsic mitochondrial dysfunction in ATM-deficient lymphoblastoid cells. Hum Mol Genet 2007; 16:2154-64. [PMID: 17606465 DOI: 10.1093/hmg/ddm166] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
One of the characteristic features of cells from patients with ataxia telangiectasia (A-T) is that they are in a state of continuous oxidative stress and exhibit constitutive activation of pathways that normally respond to oxidative damage. In this report, we investigated whether the oxidative stress phenotype of A-T cells might be a reflection of an intrinsic mitochondrial dysfunction. Mitotracker Red staining showed that the structural organization of mitochondria in A-T cells was abnormal compared to wild-type. Moreover, A-T cells harbored a much larger population of mitochondria with decreased membrane potential (DeltaPsi) than control cells. In addition, the basal expression levels of several nuclear DNA-encoded oxidative damage responsive genes whose proteins are targeted to the mitochondria--polymerase gamma, mitochondrial topoisomerase I, peroxiredoxin 3 and manganese superoxide dismutase--are elevated in A-T cells. Consistent with these results, we found that overall mitochondrial respiratory activity was diminished in A-T compared to wild-type cells. Treating A-T cells with the antioxidant, alpha lipoic acid (ALA), restored mitochondrial respiration rates to levels approaching those of wild-type. When wild-type cells were transfected with ATM-targeted siRNA, we observed a small but significant reduction in the respiration rates of mitochondria. Moreover, mitochondria in A-T cells induced to stably express full-length ATM, exhibited respiration rates approaching those of wild-type cells. Taken together, our results provide evidence for an intrinsic mitochondrial dysfunction in A-T cells, and implicate a requirement for ATM in the regulation of mitochondrial function.
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Affiliation(s)
- Mark Ambrose
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA 90095-1732, USA
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