Chronically elevated glucose compromises myocardial mitochondrial DNA integrity by alteration of mitochondrial topoisomerase function

Mitochondrial dysfunction has a significant role in the development and complications of diabetic cardiomyopathy. Mitochondrial dysfunction and mitochondrial DNA (mtDNA) mutations are also associated with different types of cancer and neurodegenerative diseases. The goal of this study was to determine if chronically elevated glucose increase in mtDNA damage contributed to mitochondrial dysfunction and identify the underlying basis for mtDNA damage. H9c2 myotubes (a cardiac-derived cell line) were studied in the presence of 5.5, 16.5, or 33.0 mM glucose for up to 13 days. Tests of mitochondria function (Complex I and IV activity and ATP generation) were all significantly depressed by elevated media glucose. Intramitochondrial superoxide and intracellular superoxide levels were transiently increased during the experimental period. AnnexinV binding (a marker of apoptosis) was significantly increased after 7 and 13 days of high glucose. Thirteen days of elevated glucose significantly increased mtDNA damage globally and across the region encoding for the three subunits of cytochrome oxidase. Using mitochondria isolated from cells chronically exposed to elevated glucose, we observed significant increases in topoisomerase-linked DNA cleavage. Mitochondria-dependent DNA cleavage was significantly exacerbated by H2O2 and that immunoprecipitation of mitochondrial extracts with a mtTOP1 antibody significantly decreased DNA cleavage, indicating that at least part of this activity could be attributed to mtTOP1. We conclude that even mild increases in glucose presentation compromised mitochondrial function as a result of a decline in mtDNA integrity. Separate from a direct impact of oxidative stress on mtDNA, ROS-induced alteration of mitochondrial topoisomerase activity exacerbated and propagated increases in mtDNA damage. These findings are significant in that the activation/inhibition state of the mitochondrial topoisomerases will have important consequences for mitochondrial DNA integrity and the well being of the myocardium.

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Type II diabetes increases mitochondrial DNA mutations in the left ventricle of the Goto-Kakizaki diabetic rat

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00567.2012 ◽

2013 ◽

Vol 304 (7) ◽

pp. H903-H915 ◽

Cited By ~ 9

Author(s):

S. Hicks ◽

N. Labinskyy ◽

B. Piteo ◽

D. Laurent ◽

J. E. Mathew ◽

...

Keyword(s):

Mitochondrial Dna ◽

Left Ventricle ◽

Mitochondrial Dysfunction ◽

Dna Cleavage ◽

Type Ii Diabetes ◽

Oxidant Stress ◽

Type Ii ◽

Mtdna Damage ◽

Cleavage Activity ◽

Dna Cleavage Activity

Mitochondrial dysfunction has a significant role in the development of diabetic cardiomyopathy. Mitochondrial oxidant stress has been accepted as the singular cause of mitochondrial DNA (mtDNA) damage as an underlying cause of mitochondrial dysfunction. However, separate from a direct effect on mtDNA integrity, diabetic-induced increases in oxidant stress alter mitochondrial topoisomerase function to propagate mtDNA mutations as a contributor to mitochondrial dysfunction. Both glucose-challenged neonatal cardiomyocytes and the diabetic Goto-Kakizaki (GK) rat were studied. In both the GK left ventricle (LV) and in cardiomyocytes, chronically elevated glucose presentation induced a significant increase in mtDNA damage that was accompanied by decreased mitochondrial function. TTGE analysis revealed a number of base pair substitutions in the 3' end of COX3 from GK LV mtDNA that significantly altered the protein sequence. Mitochondrial topoisomerase DNA cleavage activity in isolated mitochondria was significantly increased in the GK LV compared with Wistar controls. Both hydroxycamptothecin, a topoisomerase type 1 inhibitor, and doxorubicin, a topoisomerase type 2 inhibitor, significantly exacerbated the DNA cleavage activity of isolated mitochondrial extracts indicating the presence of multiple functional topoisomerases in the mitochondria. Mitochondrial topoisomerase function was significantly altered in the presence of H2O2suggesting that separate from a direct effect on mtDNA, oxidant stress mediated type II diabetes-induced alterations of mitochondrial topoisomerase function. These findings are significant in that the activation/inhibition state of the mitochondrial topoisomerases will have important consequences for mtDNA integrity and the well being of the diabetic myocardium.

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Mitochondrial Dysfunction in Parkinson’s Disease: Focus on Mitochondrial DNA

Biomedicines ◽

10.3390/biomedicines8120591 ◽

2020 ◽

Vol 8 (12) ◽

pp. 591

Author(s):

Olga Buneeva ◽

Valerii Fedchenko ◽

Arthur Kopylov ◽

Alexei Medvedev

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Mitochondrial Dna ◽

Mitochondrial Dysfunction ◽

Nuclear Dna ◽

Good Evidence ◽

Inner Mitochondrial Membrane ◽

Mtdna Mutations ◽

Increased Risk ◽

Mtdna Replication

Mitochondria, the energy stations of the cell, are the only extranuclear organelles, containing their own (mitochondrial) DNA (mtDNA) and the protein synthesizing machinery. The location of mtDNA in close proximity to the oxidative phosphorylation system of the inner mitochondrial membrane, the main source of reactive oxygen species (ROS), is an important factor responsible for its much higher mutation rate than nuclear DNA. Being more vulnerable to damage than nuclear DNA, mtDNA accumulates mutations, crucial for the development of mitochondrial dysfunction playing a key role in the pathogenesis of various diseases. Good evidence exists that some mtDNA mutations are associated with increased risk of Parkinson’s disease (PD), the movement disorder resulted from the degenerative loss of dopaminergic neurons of substantia nigra. Although their direct impact on mitochondrial function/dysfunction needs further investigation, results of various studies performed using cells isolated from PD patients or their mitochondria (cybrids) suggest their functional importance. Studies involving mtDNA mutator mice also demonstrated the importance of mtDNA deletions, which could also originate from abnormalities induced by mutations in nuclear encoded proteins needed for mtDNA replication (e.g., polymerase γ). However, proteomic studies revealed only a few mitochondrial proteins encoded by mtDNA which were downregulated in various PD models. This suggests nuclear suppression of the mitochondrial defects, which obviously involve cross-talk between nuclear and mitochondrial genomes for maintenance of mitochondrial functioning.

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Do Somatic Mitochondrial DNA Mutations Contribute to Parkinson's Disease?

Parkinson s Disease ◽

10.4061/2011/659694 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Joanne Clark ◽

Ying Dai ◽

David K. Simon

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Mitochondrial Dna ◽

Mitochondrial Dysfunction ◽

Point Mutations ◽

Premature Aging ◽

Mtdna Mutations ◽

Dna Mutations ◽

Mitochondrial Dna Polymerase ◽

Mitochondrial Defect

A great deal of evidence supports a role for mitochondrial dysfunction in the pathogenesis of Parkinson's disease (PD), although the origin of the mitochondrial dysfunction in PD remains unclear. Expression of mitochondrial DNA (mtDNA) from PD patients in “cybrid” cell lines recapitulates the mitochondrial defect, implicating a role for mtDNA mutations, but the specific mutations responsible for the mitochondrial dysfunction in PD have been difficult to identify. Somatic mtDNA point mutations and deletions accumulate with age and reach high levels in substantia nigra (SN) neurons. Mutations in mitochondrial DNA polymeraseγ(POLG) that lead to the accumulation of mtDNA mutations are associated with a premature aging phenotype in “mutator” mice, although overt parkinsonism has not been reported in these mice, and with parkinsonism in humans. Together these data support, but do not yet prove, the hypothesis that the accumulation of somatic mtDNA mutations in SN neurons contribute to the pathogenesis of PD.

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Mitochondrial DNA targeting and impairment by a dinuclear Ir–Pt complex that overcomes cisplatin resistance

Inorganic Chemistry Frontiers ◽

10.1039/d0qi00224k ◽

2020 ◽

Vol 7 (9) ◽

pp. 1864-1871 ◽

Cited By ~ 1

Author(s):

Cheng Zhang ◽

Ruilin Guan ◽

Xinxing Liao ◽

Cheng Ouyang ◽

Jiangping Liu ◽

...

Keyword(s):

Mitochondrial Dna ◽

Antitumor Activity ◽

Mitochondrial Dysfunction ◽

Cancer Cells ◽

Cisplatin Resistance ◽

Cell Necrosis ◽

Mtdna Damage ◽

Dna Targeting ◽

Pt Complex ◽

Strong Antitumor Activity

A dinuclear complex [(ppy)Ir(tpy)PtCl]2+ (Ir–Pt) can exhibit strong antitumor activity towards cisplatin-resistant cancer cells and induce cell necrosis via mtDNA damage and mitochondrial dysfunction.

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Mitochondrial DNA integrity may be a determinant of endothelial barrier properties in oxidant-challenged rat lungs

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00210.2011 ◽

2011 ◽

Vol 301 (6) ◽

pp. L892-L898 ◽

Cited By ~ 36

Author(s):

Joshua M. Chouteau ◽

Boniface Obiako ◽

Olena M. Gorodnya ◽

Viktor M. Pastukh ◽

Mykhaylo V. Ruchko ◽

...

Keyword(s):

Mitochondrial Dna ◽

Fusion Proteins ◽

Nuclear Dna ◽

Oxidant Stress ◽

Barrier Properties ◽

Pharmacological Intervention ◽

Dna Integrity ◽

Barrier Dysfunction ◽

Mtdna Damage ◽

Rat Lungs

In cultured pulmonary artery endothelial cells and other cell types, overexpression of mt-targeted DNA repair enzymes protects against oxidant-induced mitochondrial DNA (mtDNA) damage and cell death. Whether mtDNA integrity governs functional properties of the endothelium in the intact pulmonary circulation is unknown. Accordingly, the present study used isolated, buffer-perfused rat lungs to determine whether fusion proteins targeting 8-oxoguanine DNA glycosylase 1 (Ogg1) or endonuclease III (Endo III) to mitochondria attenuated mtDNA damage and vascular barrier dysfunction evoked by glucose oxidase (GOX)-generated hydrogen peroxide. We found that both Endo III and Ogg1 fusion proteins accumulated in lung cell mitochondria within 30 min of addition to the perfusion medium. Both constructs prevented GOX-induced increases in the vascular filtration coefficient. Although GOX-induced nuclear DNA damage could not be detected, quantitative Southern blot analysis revealed substantial GOX-induced oxidative mtDNA damage that was prevented by pretreatment with both fusion proteins. The Ogg1 construct also reversed preexisting GOX-induced vascular barrier dysfunction and oxidative mtDNA damage. Collectively, these findings support the ideas that mtDNA is a sentinel molecule governing lung vascular barrier responses to oxidant stress in the intact lung and that the mtDNA repair pathway could be a target for pharmacological intervention in oxidant lung injury.

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The Role of Mitochondrial Dysfunction in Vascular Disease, Tumorigenesis, and Diabetes

Frontiers in Molecular Biosciences ◽

10.3389/fmolb.2021.671908 ◽

2021 ◽

Vol 8 ◽

Author(s):

Olga A. Zhunina ◽

Nikita G. Yabbarov ◽

Andrey V. Grechko ◽

Antonina V. Starodubova ◽

Ekaterina Ivanova ◽

...

Keyword(s):

Cardiovascular Diseases ◽

Mitochondrial Dysfunction ◽

Mitochondrial Protein ◽

Cellular Damage ◽

Future Perspective ◽

Antioxidant Systems ◽

Mtdna Damage ◽

Mtdna Mutations ◽

Wide Range

Mitochondrial dysfunction is known to be associated with a wide range of human pathologies, such as cancer, metabolic, and cardiovascular diseases. One of the possible ways of mitochondrial involvement in the cellular damage is excessive production of reactive oxygen and nitrogen species (ROS and RNS) that cannot be effectively neutralized by existing antioxidant systems. In mitochondria, ROS and RNS can contribute to protein and mitochondrial DNA (mtDNA) damage causing failure of enzymatic chains and mutations that can impair mitochondrial function. These processes further lead to abnormal cell signaling, premature cell senescence, initiation of inflammation, and apoptosis. Recent studies have identified numerous mtDNA mutations associated with different human pathologies. Some of them result in imbalanced oxidative phosphorylation, while others affect mitochondrial protein synthesis. In this review, we discuss the role of mtDNA mutations in cancer, diabetes, cardiovascular diseases, and atherosclerosis. We provide a list of currently described mtDNA mutations associated with each pathology and discuss the possible future perspective of the research.

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Protection from Palmitate-Induced Mitochondrial DNA Damage Prevents from Mitochondrial Oxidative Stress, Mitochondrial Dysfunction, Apoptosis, and Impaired Insulin Signaling in Rat L6 Skeletal Muscle Cells

Endocrinology ◽

10.1210/en.2011-1442 ◽

2012 ◽

Vol 153 (1) ◽

pp. 92-100 ◽

Cited By ~ 49

Author(s):

Larysa V. Yuzefovych ◽

Viktoriya A. Solodushko ◽

Glenn L. Wilson ◽

Lyudmila I. Rachek

Keyword(s):

Oxidative Stress ◽

Insulin Resistance ◽

Skeletal Muscle ◽

Dna Repair ◽

Mitochondrial Dna ◽

Mitochondrial Dysfunction ◽

Insulin Signaling ◽

Mtdna Damage ◽

L6 Myotubes ◽

Impaired Insulin

Saturated free fatty acids have been implicated in the increase of oxidative stress, mitochondrial dysfunction, apoptosis, and insulin resistance seen in type 2 diabetes. The purpose of this study was to determine whether palmitate-induced mitochondrial DNA (mtDNA) damage contributed to increased oxidative stress, mitochondrial dysfunction, apoptosis, impaired insulin signaling, and reduced glucose uptake in skeletal muscle cells. Adenoviral vectors were used to deliver the DNA repair enzyme human 8-oxoguanine DNA glycosylase/(apurinic/apyrimidinic) lyase (hOGG1) to mitochondria in L6 myotubes. After palmitate exposure, we evaluated mtDNA damage, mitochondrial function, production of mitochondrial reactive oxygen species, apoptosis, insulin signaling pathways, and glucose uptake. Protection of mtDNA from palmitate-induced damage by overexpression of hOGG1 targeted to mitochondria significantly diminished palmitate-induced mitochondrial superoxide production, restored the decline in ATP levels, reduced activation of c-Jun N-terminal kinase (JNK) kinase, prevented cells from entering apoptosis, increased insulin-stimulated phosphorylation of serine-threonine kinase (Akt) (Ser473) and tyrosine phosphorylation of insulin receptor substrate-1, and thereby enhanced glucose transporter 4 translocation to plasma membrane, and restored insulin signaling. Addition of a specific inhibitor of JNK mimicked the effect of mitochondrial overexpression of hOGG1 and partially restored insulin sensitivity, thus confirming the involvement of mtDNA damage and subsequent increase of oxidative stress and JNK activation in insulin signaling in L6 myotubes. Our results are the first to report that mtDNA damage is the proximal cause in palmitate-induced mitochondrial dysfunction and impaired insulin signaling and provide strong evidence that targeting DNA repair enzymes into mitochondria in skeletal muscles could be a potential therapeutic treatment for insulin resistance.

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Mitochondrial Dysfunction Due to Oxidative Mitochondrial DNA Damage Is Reduced through Cooperative Actions of Diverse Proteins

Molecular and Cellular Biology ◽

10.1128/mcb.22.12.4086-4093.2002 ◽

2002 ◽

Vol 22 (12) ◽

pp. 4086-4093 ◽

Cited By ~ 91

Author(s):

Thomas W. O'Rourke ◽

Nicole A. Doudican ◽

Melinda D. Mackereth ◽

Paul W. Doetsch ◽

Gerald S. Shadel

Keyword(s):

Mitochondrial Dna ◽

Mitochondrial Dysfunction ◽

Base Excision Repair ◽

Excision Repair ◽

Mtdna Damage ◽

Mtdna Recombination ◽

Mitochondrial Dna Damage ◽

Base Excision ◽

Enzyme Functions ◽

Point Mutagenesis

ABSTRACT The mitochondrial genome is a significant target of exogenous and endogenous genotoxic agents; however, the determinants that govern this susceptibility and the pathways available to resist mitochondrial DNA (mtDNA) damage are not well characterized. Here we report that oxidative mtDNA damage is elevated in strains lacking Ntg1p, providing the first direct functional evidence that this mitochondrion-localized, base excision repair enzyme functions to protect mtDNA. However, ntg1 null strains did not exhibit a mitochondrial respiration-deficient (petite) phenotype, suggesting that mtDNA damage is negotiated by the cooperative actions of multiple damage resistance pathways. Null mutations in ABF2 or PIF1, two genes implicated in mtDNA maintenance and recombination, exhibit a synthetic-petite phenotype in combination with ntg1 null mutations that is accompanied by enhanced mtDNA point mutagenesis in the corresponding double-mutant strains. This phenotype was partially rescued by malonic acid, indicating that reactive oxygen species generated by the electron transport chain contribute to mitochondrial dysfunction in abf2Δ strains. In contrast, when two other genes involved in mtDNA recombination, CCE1 and NUC1, were inactivated a strong synthetic-petite phenotype was not observed, suggesting that the effects mediated by Abf2p and Pif1p are due to novel activities of these proteins other than recombination. These results document the existence of recombination-independent mechanisms in addition to base excision repair to cope with oxidative mtDNA damage in Saccharomyces cerevisiae. Such systems are likely relevant to those operating in human cells where mtDNA recombination is less prevalent, validating yeast as a model system in which to study these important issues.

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Mitochondrial DNA damage triggers mitochondrial dysfunction and apoptosis in oxidant-challenged lung endothelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00255.2004 ◽

2005 ◽

Vol 288 (3) ◽

pp. L530-L535 ◽

Cited By ~ 66

Author(s):

Mykhaylo Ruchko ◽

Olena Gorodnya ◽

Susan P. LeDoux ◽

Mikhail F. Alexeyev ◽

Abu-Bakr Al-Mehdi ◽

...

Keyword(s):

Endothelial Cells ◽

Mitochondrial Dna ◽

Mitochondrial Dysfunction ◽

Mitochondrial Targeting ◽

Mtdna Damage ◽

Mitochondrial Dna Damage ◽

Human Dna ◽

Lung Endothelial Cells ◽

Induced Apoptosis ◽

Mtdna Repair

Oxidant-induced death and dysfunction of pulmonary vascular cells play important roles in the evolution of acute lung injury. In pulmonary artery endothelial cells (PAECs), oxidant-mediated damage to mitochondrial DNA (mtDNA) seems to be critical in initiating cytotoxicity inasmuch as overexpression of the mitochondrially targeted human DNA repair enzyme, human Ogg1 (hOgg1), prevents both mtDNA damage and cell death (Dobson AW, Grishko V, LeDoux SP, Kelley MR, Wilson GL, and Gillespie MN. Am J Physiol Lung Cell Mol Physiol 283: L205–L210, 2002). The mechanism by which mtDNA damage leads to PAEC death is unknown, and the present study tested the specific hypothesis that enhanced mtDNA repair suppresses PAEC mitochondrial dysfunction and apoptosis evoked by xanthine oxidase (XO). PAECs transfected either with an adenoviral vector encoding hOgg1 linked to a mitochondrial targeting sequence or with empty vector were challenged with ascending doses of XO plus hypoxanthine. Quantitative Southern blot analyses revealed that, as expected, hOgg1 overexpression suppressed XO-induced mtDNA damage. Mitochondrial overexpression of hOgg1 also suppressed the XO-mediated loss of mitochondrial membrane potential. Importantly, hOgg1 overexpression attenuated XO-induced apoptosis as detected by suppression of caspase-3 activation, by reduced DNA fragmentation, and by a blunted appearance of condensed, fragmented nuclei. These observations suggest that mtDNA damage serves as a trigger for mitochondrial dysfunction and apoptosis in XO-treated PAECs.

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Do mitochondrial DNA mutations play the key role in chronification of sterile inflammation? Special focus on atherosclerosis

Current Pharmaceutical Design ◽

10.2174/1381612826666201012164330 ◽

2020 ◽

Vol 26 ◽

Author(s):

Alexander N. Orekhov ◽

Elena V. Gerasimova ◽

Vasily N. Sukhorukov ◽

Anastasia V. Poznyak ◽

Nikita G. Nikiforov

Keyword(s):

Innate Immunity ◽

Mitochondrial Dna ◽

Low Density Lipoprotein ◽

Atherosclerotic Lesion ◽

Density Lipoprotein ◽

Sterile Inflammation ◽

Special Focus ◽

Mitochondrial Dysfunctions ◽

Mtdna Mutations ◽

Dna Mutations

Background: The elucidation of mechanisms implicated in the chronification of inflammation is able to shed the light on the pathogenesis of disorders that are responsible for the majority of the incidence of disease and deaths, and also causes of ageing. Atherosclerosis is an example of the most significant inflammatory pathology. The inflammatory response of innate immunity is implicated in the development of atherosclerosis arising locally or focally. Modified low-density lipoprotein (LDL) was regarded as the trigger for this response. No atherosclerotic changes in the arterial wall occur due to the quick decrease in inflammation rate. Nonetheless, the atherosclerotic lesion formation can be a result of the chronification of local inflammation, which, in turn, is caused by alteration of the response of innate immunity. Objective: In this review, we discussed potential mechanisms of the altered response of the immunity in atherosclerosis with a particular emphasis on mitochondrial dysfunctions. Conclusion: A few mitochondrial dysfunctions can be caused by the mitochondrial DNA (mtDNA) mutations. Moreover, mtDNA mutations were found to affect the development of defective mitophagy. Modern investigations have demonstrated the controlling mitophagy function in the response of the immune system. Therefore, we hypothesized that impaired mitophagy, as a consequence of mutations in mtDNA, can raise a disturbed innate immunity response resulting in the chronification of inflammation in atherosclerosis.

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