Reactive oxygen and nitrogen species: Friends or foes?

CCCP inhibits DPV infection in DEF cells by attenuating DPV manipulated ROS, apoptosis, and mitochondrial stability

Duck plague virus (DPV) is extremely infectious and lethal, so antiviral drugs are urgently needed. Our previous study shows that DPV infection with duck embryo fibroblast (DEF) induces reactive oxygen species (ROS) changes and promotes apoptosis. In this study, we tested the antiviral effect of the carbonyl cyanide m-chlorophenyl hydrazone (CCCP), a common mitochondrial autophagy inducer. Our results demonstrated a dose-dependent anti-DPV effect of CCCP, CCCP-treatment blocked the intercellular transmission of DPV after infection, and we also proved that CCCP could have an antiviral effect up to 48 hpi. The addition of CCCP reversed the DPV-induced ROS changes, CCCP can inhibit virus-induced apoptosis; meanwhile, CCCP can affect mitochondrial fusion and activate mitophagy to inhibit DPV. In conclusion, CCCP can be an effective antiviral candidate against DPV.

Mitocentricity

Worldwide, interest in mitochondria is constantly growing, as evidenced by scientific statistics, and studies of the functioning of these organelles are becoming more prevalent than studies of other cellular structures. In this analytical review, mitochondria are conditionally placed in a certain cellular center, which is responsible for both energy production and other non-energetic functions, without which the existence of not only the eukaryotic cell itself, but also the entire organism is impossible. Taking into account the high multifunctionality of mitochondria, such a fundamentally new scheme of cell functioning organization, including mitochondrial management of processes that determine cell survival and death, may be justified. Considering that this issue is dedicated to the memory of V. P. Skulachev, who can be called mitocentric, due to the history of his scientific activity almost entirely aimed at studying mitochondria, this work examines those aspects of mitochondrial functioning that were directly or indirectly the focus of attention of this outstanding scientist. We list all possible known mitochondrial functions, including membrane potential generation, synthesis of Fe-S clusters, steroid hormones, heme, fatty acids, and CO2. Special attention is paid to the participation of mitochondria in the formation and transport of water, as a powerful biochemical cellular and mitochondrial regulator. The history of research on reactive oxygen species that generate mitochondria is subject to significant analysis. In the section "Mitochondria in the center of death", special emphasis is placed on the analysis of what role and how mitochondria can play and determine the program of death of an organism (phenoptosis) and the contribution made to these studies by V. P. Skulachev.

The role of mitochondrial dynamics in cerebral ischemia-reperfusion injury

Stroke is one of the leading causes of death and long-term disability worldwide. More than 80 % of strokes are ischemic, caused by an occlusion of cerebral arteries. Without question, restoration of blood supply as soon as possible is the first therapeutic strategy. Nonetheless paradoxically, reperfusion can further aggravate the injury through a series of reactions known as cerebral ischemia-reperfusion injury (CIRI). Mitochondria play a vital role in promoting nerve survival and neurological function recovery and mitochondrial dysfunction is considered one of the characteristics of CIRI. Neurons often die due to oxidative stress and an imbalance in energy metabolism following CIRI, and there is a strong association with mitochondrial dysfunction. Altered mitochondrial dynamics is the first reaction of mitochondrial stress. Mitochondrial dynamics refers to the maintenance of the integrity, distribution, and size of mitochondria as well as their ability to resist external stimuli through a continuous cycle of mitochondrial fission and fusion. Therefore, improving mitochondrial dynamics is a vital means of treating CIRI. This review discusses the relationship between mitochondria and CIRI and emphasizes improving mitochondrial dynamics as a potential therapeutic approach to improve the prognosis of CIRI.

Star Polymers as Non-Viral Carriers for Apoptosis Induction

Apoptosis is a widely controlled, programmed cell death, defects in which are the source of various diseases such as neurodegenerative diseases as well as cancer. The use of apoptosis in the therapy of various human diseases is of increasing interest, and the analysis of the factors involved in its regulation is valuable in designing specific carriers capable of targeting cell death. Highly efficient and precisely controlled delivery of genetic material by low-toxic carriers is one of the most important challenges of apoptosis-based gene therapy. In this work, we investigate the effect of the star polymer with 28 poly(N,N′-dimethylaminoethyl methacrylate) arms (STAR) on human cells, according to its concentration and structure. We show that star polymer cytotoxicity increases within its concentration and time of cells treatment. Except for cytotoxic effect, we observe morphological changes such as a shrinkage, loss of shape and begin to detach. We also prove DNA condensation after star polymer treatment, one of the most characteristic feature of apoptosis. The results indicate that the use of STAR triggers apoptosis in cancer cells compared to various normal cells, what makes these nanoparticles a promising drug in therapeutic strategy, which targets apoptosis. We demonstrate highlighting potential of star polymers as an innovative tool for anti-cancer therapy.

Redox Homeostasis Involvement in the Pharmacological Effects of Metformin in Systemic Lupus Erythematosus

Significance: Metformin has been proposed as a treatment for systemic lupus erythematosus (SLE). The primary target of metformin, the electron transport chain complex I in the mitochondria, is associated with redox homeostasis in immune cells, which plays a critical role in the pathogenesis of autoimmune diseases. This review addresses the evidence and knowledge gaps on whether a beneficial effect of metformin in lupus may be due to a restoration of a balanced redox state. Recent Advances: Clinical trials in SLE patients with mild-to-moderate disease activity and preclinical studies in mice have provided encouraging results for metformin. The mechanism by which this therapeutic effect was achieved is largely unknown. Metformin regulates redox homeostasis in a context-specific manner. Multiple cell types contribute to SLE, with evidence of increased mitochondrial oxidative stress in T cells and neutrophils. Critical Issues: The major knowledge gaps are whether the efficacy of metformin is linked to a restored redox homeostasis in the immune system, and if it does, in which cell types it occurs? We also need to know which patients may have a better response to metformin, and whether it corresponds to a specific mechanism? Finally, the identification of biomarkers to predict treatment outcomes would be of great value. Future Directions: Mechanistic studies must address the context-dependent pharmacological effects of metformin. Multiple cell types as well as a complex disease etiology should be considered. These studies must integrate the rapid advances made in understanding how metabolic programs direct the effector functions of immune cells. Antioxid. Redox Signal. 36, 462-479.

Neuroprotective Potential of Mild Uncoupling in Mitochondria. Pros and Cons

There has been an explosion of interest in the use of uncouplers of oxidative phosphorylation in mitochondria in the treatment of several pathologies, including neurological ones. In this review, we analyzed all the mechanisms associated with mitochondrial uncoupling and the metabolic and signaling cascades triggered by uncouplers. We provide a full set of positive and negative effects that should be taken into account when using uncouplers in experiments and clinical practice.

Nonphosphorylating Oxidation in Mitochondria and Related Processes

The mechanism of oxidative phosphorylation and its regulation remain one of the main problems of bioenergetics. Efficiency of the mitochondrial energization is determined by the relationship between the rate of generation of electrochemical potential of hydrogen ions and the rate of its expenditure on the synthesis of ATP and the use of ATP in endergonic reactions. Uncoupling (partial or complete), which occurs in the process of uncontrolled and controlled leakage of ions through the inner mitochondrial membrane, on the one hand leads to the decrease in the relative synthesis of ATP, and on the other, being consistent with the law of conservation of energy, leads to the formation of heat, generation of which is an essential function of the organism. In addition to increased thermogenesis, the increase of non-phosphorylating oxidation of various substrates is accompanied by the decrease in transmembrane potential, production of reactive oxygen species, and activation of oxygen consumption, water and carbon dioxide production, increase in the level of intracellular ADP and acidification of the cytosol. In this analysis, each of these factors will be considered separately for its role in regulating metabolism.

Mitochondrial complex II and reactive oxygen species in disease and therapy

Increasing evidence points to the respiratory Complex II (CII) as a source and modulator of reactive oxygen species (ROS). Both functional loss of CII as well as its pharmacological inhibition can lead to ROS generation in cells, with a relevant impact on the development of pathophysiological conditions, i.e. cancer and neurodegenerative diseases. While the basic framework of CII involvement in ROS production has been defined, the fine details still await clarification. It is important to resolve these aspects to fully understand the role of CII in pathology and to explore its therapeutic potential in cancer and other diseases.

Oxidative and Nitrosative Stress in Age-Related Macular Degeneration: A Review of Their Role in Different Stages of Disease

Although the exact pathogenetic mechanisms leading to age-related macular degeneration (AMD) have not been clearly identified, oxidative damage in the retina and choroid due to an imbalance between local oxidants/anti-oxidant systems leading to chronic inflammation could represent the trigger event. Different in vitro and in vivo models have demonstrated the involvement of reactive oxygen species generated in a highly oxidative environment in the development of drusen and retinal pigment epithelium (RPE) changes in the initial pathologic processes of AMD; moreover, recent evidence has highlighted the possible association of oxidative stress and neovascular AMD. Nitric oxide (NO), which is known to play a key role in retinal physiological processes and in the regulation of choroidal blood flow, under pathologic conditions could lead to RPE/photoreceptor degeneration due to the generation of peroxynitrite, a potentially cytotoxic tyrosine-nitrating molecule. Furthermore, the altered expression of the different isoforms of NO synthases could be involved in choroidal microvascular changes leading to neovascularization. The purpose of this review was to investigate the different pathways activated by oxidative/nitrosative stress in the pathogenesis of AMD, focusing on the mechanisms leading to neovascularization and on the possible protective role of anti-vascular endothelial growth factor agents in this context.

Protective Effect of Mitochondria-Targeted Antioxidants against Inflammatory Response to Lipopolysaccharide Challenge: A Review

Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, is the most abundant proinflammatory agent. Considerable evidence indicates that LPS challenge inescapably causes oxidative stress and mitochondrial dysfunction, leading to cell and tissue damage. Increased mitochondrial reactive oxygen species (mtROS) generation triggered by LPS is known to play a key role in the progression of the inflammatory response. mtROS at excessive levels impair electron transport chain functioning, reduce the mitochondrial membrane potential, and initiate lipid peroxidation and oxidative damage of mitochondrial proteins and mtDNA. Over the past 20 years, a large number of mitochondria-targeted antioxidants (mito-AOX) of different structures that can accumulate inside mitochondria and scavenge free radicals have been synthesized. Their protective role based on the prevention of oxidative stress and the restoration of mitochondrial function has been demonstrated in a variety of common diseases and pathological states. This paper reviews the current data on the beneficial application of different mito-AOX in animal endotoxemia models, in either in vivo or in vitro experiments. The results presented in our review demonstrate the promising potential of approaches based on mito-AOX in the development of new treatment strategies against Gram-negative infections and LPS per se.

Oxidative stress as a therapeutic target for the prevention and treatment of early age-related macular degeneration

Age-related macular degeneration, the leading cause of irreversible visual loss among older adults in developed countries, is a chronic, multifactorial, and progressive disease with the development of painless, central vision loss. Retinal pigment epithelial cell dysfunction is a core change in age-related macular degeneration that results from aging and the accumulated effects of genetic and environmental factors that, in part, is both caused by and leads to oxidative stress. In this review, we describe the role of oxidative stress, the cytoprotective oxidative stress pathways, and the impact of oxidative stress on critical cellular processes involved in age-related macular degeneration pathobiology. We also offer targeted therapy that may define how antioxidant therapy can either prevent or improve specific stages of age-related macular degeneration.

Pros and Cons of Use of Mitochondria-Targeted Antioxidants

Mitochondrial targeting is a novel strategy, which addresses pathologies originating from mitochondrial dysfunction. Here, one of the most potent therapeutics arises from the group of mitochondria-targeted antioxidants, which specifically quench mitochondrial reactive oxygen species (ROS). They show very high efficacy in the treatment of a diverse array of pathologies encountered in this Special Issue of Antioxidants. However, despite very encouraging results in the use of mitochondria-targeted antioxidants, the mechanistic principle of delivering these agents is, to some extent, counterproductive to the goal of selectively treating a population of damaged mitochondria. The main problem that arises is that injured mitochondria may carry a lower membrane potential when compared with normal ones and as a result, injured mitochondria are capable of taking up less therapeutic antioxidants than healthy mitochondria. Another problem is that the intracellular activity of mitochondrial ROS differs from cytosolic ROS in that they carry specific intracellular functions which are maintained at a delicate equilibrium and which may be disturbed under careless use of antioxidant doses. Consequently, understanding the overall benefit of targeting dysfunctional mitochondria in pathological tissue requires furthering the development of alternative techniques to target mitochondria.

Mitochondria as a Source and a Target for Uremic Toxins

Elucidation of molecular and cellular mechanisms of the uremic syndrome is a very challenging task. More than 130 substances are now considered to be "uremic toxins" and represent a very diverse group of molecules. The toxicity of these molecules affects many cellular processes, and expectably, some of them are able to disrupt mitochondrial functioning. However, mitochondria can be the source of uremic toxins as well, as the mitochondrion can be the site of complete synthesis of the toxin, whereas in some scenarios only some enzymes of the pathway of toxin synthesis are localized here. In this review, we discuss the role of mitochondria as both the target and source of pathological processes and toxic compounds during uremia. Our analysis revealed about 30 toxins closely related to mitochondria. Moreover, since mitochondria are key regulators of cellular redox homeostasis, their functioning might directly affect the production of uremic toxins, especially those that are products of oxidation or peroxidation of cellular components, such as aldehydes, advanced glycation end-products, advanced lipoxidation end-products, and reactive carbonyl species. Additionally, as a number of metabolic products can be degraded in the mitochondria, mitochondrial dysfunction would therefore be expected to cause accumulation of such toxins in the organism. Alternatively, many uremic toxins (both made with the participation of mitochondria, and originated from other sources including exogenous) are damaging to mitochondrial components, especially respiratory complexes. As a result, a positive feedback loop emerges, leading to the amplification of the accumulation of uremic solutes. Therefore, uremia leads to the appearance of mitochondria-damaging compounds, and consecutive mitochondrial damage causes a further rise of uremic toxins, whose synthesis is associated with mitochondria. All this makes mitochondrion an important player in the pathogenesis of uremia and draws attention to the possibility of reducing the pathological consequences of uremia by protecting mitochondria and reducing their role in the production of uremic toxins.

PARP inhibition in platinum-based chemotherapy: Chemopotentiation and neuroprotection

Cisplatin, carboplatin and oxaliplatin represent the backbone of platinum therapy for several malignancies including head and neck, lung, colorectal, ovarian, breast, and genitourinary cancer. However, the efficacy of platinum-based drugs is often compromised by a plethora of severe toxicities including sensory and enteric neuropathy. Acute and chronic neurotoxicity following platinum chemotherapy is a major constraint, contributing to dose-reductions, treatment delays, and cessation of treatment. Identifying drugs that effectively prevent these toxic complications is imperative to improve the efficacy of anti-cancer treatment and patient quality of life. Oxidative stress and mitochondrial dysfunction have been highlighted as key players in the pathophysiology of platinum chemotherapy-induced neuropathy. Inhibition of poly(ADP-ribose) polymerase (PARP), a nuclear enzyme activated upon DNA damage, has demonstrated substantial sensory and enteric neuroprotective capacity when administered in combination with platinum chemotherapeutics. Furthermore, administration of PARP inhibitors alongside platinum chemotherapy has been found to significantly improve progression-free survival in patients with breast and ovarian cancer when compared to those receiving chemotherapy alone. This review summarises the current knowledge surrounding mitochondrial damage and oxidative stress in platinum chemotherapy-induced neuropathy and highlights a potential role for PARP in chemopotentiation and neuroprotection.

Daphnegiravone D from Daphne giraldii Nitsche induces p38-dependent apoptosis via oxidative and nitrosative stress in hepatocellular carcinoma cells

Daphnegiravone D (DGD), a prenylated flavonoid from Daphne giraldii Nitsche, significantly inhibited cell growth of several cancer cell lines without cytotoxicity on human normal cells. Our previous study showed that DGD could induce apoptosis in hepatocellular carcinoma Hep3B and HepG2 cells, but the detailed mechanism was still unclear. The present study provides that DGD-induced oxidative and nitrosative stress contribute to apoptotic cell death in Hep3B and HepG2 cells. Furthermore, there is a positive loop between oxidative stress and p38 activation, similar result is observed between nitrosative stress and p38. N-Acetylcysteine (NAC), a reactive oxygen species scavenger, could relieve DGD-induced oxidative stress, but exerts little effect on nitrosative stress. In addition, carboxy-PTIO (PTIO, a well-known scavenger of reactive nitrogen species) down-regulates the induction of nitrosative stress without obvious effect on oxidative stress in DGD-treated cells. In conclusion, the induction of oxidative and nitrosative stress could enhance p38-mediated apoptosis in DGD-treated Hep3B and HepG2 cells. Moreover, we speculated that OS and NS could not ultimately affect each other in DGD-treated HCC cells. This study gives a new insight on the mechanism of DGD-induced apoptotic cell death via oxidative and nitrosative stress in HCC cells.

Mitochondrial membrane potential

The mitochondrial membrane potential (ΔΨm) generated by proton pumps (Complexes I, III and IV) is an essential component in the process of energy storage during oxidative phosphorylation. Together with the proton gradient (ΔpH), ΔΨm forms the transmembrane potential of hydrogen ions which is harnessed to make ATP. The levels of ΔΨm and ATP in the cell are kept relatively stable although there are limited fluctuations of both these factors that can occur reflecting normal physiological activity. However, sustained changes in both factors may be deleterious. A long-lasting drop or rise of ΔΨm vs normal levels may induce unwanted loss of cell viability and be a cause of various pathologies. Among other factors, ΔΨm plays a key role in mitochondrial homeostasis through selective elimination of dysfunctional mitochondria. It is also a driving force for transport of ions (other than H+) and proteins which are necessary for healthy mitochondrial functioning. We propose additional potential mechanisms for which ΔΨm is essential for maintenance of cellular health and viability and provide recommendations how to accurately measure ΔΨm in a cell and discuss potential sources of artifacts.

Kojic acid-mediated damage responses induce mycelial regeneration in the basidiomycete Hypsizygus marmoreus

Mechanical damage can induce fruiting body production in fungi. In this study, the antioxidant kojic acid (KA) was found to enhance injured mycelial regeneration and increase fruiting body production in Hypsizygus marmoreus. KA reduced the level of reactive oxygen species (ROS), which are harmful to mycelia when excessively generated by mechanical damage. Moreover, KA increased catalase and superoxide dismutase activities and glutathione and ascorbic acid contents by up-regulating antioxidant gene expression. These results suggest that KA promotes mycelial regeneration in response to damage by activating a “stress signal” and enhances the ability of H. marmoreus to resist oxidative damage by invoking the antioxidant system. In addition, KA increased the content of extracellular ATP, which serves as a “stress signal” in response to injury, and modulated ROS signaling, decreasing NADPH oxidase gene expression and ROS levels in the mycelial-regeneration stage. KA treatment also up-regulated the MAPK, Ca²⁺ and oxylipin pathways, suggesting their involvement in the damage response. Furthermore, laccase and cellulase activities were stimulated by KA at different developmental stages. These results demonstrate that KA regulates gene expression and activates pathways for mycelial wound healing, regeneration of damaged mycelia and reproductive structure formation in the basidiomycete H. marmoreus.

Mitochondrial Aging: Is There a Mitochondrial Clock?

Fragmentation (fission) of mitochondria, occurring in response to oxidative challenge, leads to heterogeneity in the mitochondrial population. It is assumed that fission provides a way to segregate mitochondrial content between the "young" and "old" phenotype, with the formation of mitochondrial "garbage," which later will be disposed. Fidelity of this process is the basis of mitochondrial homeostasis, which is disrupted in pathological conditions and aging. The asymmetry of the mitochondrial fission is similar to that of their evolutionary ancestors, bacteria, which also undergo an aging process. It is assumed that mitochondrial markers of aging are recognized by the mitochondrial quality control system, preventing the accumulation of dysfunctional mitochondria, which normally are subjected to disposal. Possibly, oncocytoma, with its abnormal proliferation of mitochondria occupying the entire cytoplasm, represents the case when segregation of damaged mitochondria is impaired during mitochondrial division. It is plausible that mitochondria contain a "clock" which counts the degree of mitochondrial senescence as the extent of flagging (by ubiquitination) of damaged mitochondria. Mitochondrial aging captures the essence of the systemic aging which must be analyzed. We assume that the mitochondrial aging mechanism is similar to the mechanism of aging of the immune system which we discuss in detail.

The impact of oxidative stress and inflammation on RPE degeneration in non-neovascular AMD

The retinal pigment epithelium (RPE) is a highly specialized, unique epithelial cell that interacts with photoreceptors on its apical side and with Bruch's membrane and the choriocapillaris on its basal side. Due to vital functions that keep photoreceptors healthy, the RPE is essential for maintaining vision. With aging and the accumulated effects of environmental stresses, the RPE can become dysfunctional and die. This degeneration plays a central role in age-related macular degeneration (AMD) pathobiology, the leading cause of blindness among the elderly in western societies. Oxidative stress and inflammation have both physiological and potentially pathological roles in RPE degeneration. Given the central role of the RPE, this review will focus on the impact of oxidative stress and inflammation on the RPE with AMD pathobiology. Physiological sources of oxidative stress as well as unique sources from photo-oxidative stress, the phagocytosis of photoreceptor outer segments, and modifiable factors such as cigarette smoking and high fat diet ingestion that can convert oxidative stress into a pathological role, and the negative impact of impairing the cytoprotective roles of mitochondrial dynamics and the Nrf2 signaling system on RPE health in AMD will be discussed. Likewise, the response by the innate immune system to an inciting trigger, and the potential role of local RPE production of inflammation, as well as a potential role for damage by inflammation with chronicity if the inciting trigger is not neutralized, will be debated.

Neuroprotective Effects of Mitochondria-Targeted Plastoquinone and Thymoquinone in a Rat Model of Brain Ischemia/Reperfusion Injury

We explored the neuroprotective properties of natural plant-derived antioxidants plastoquinone and thymoquinone (2-demethylplastoquinone derivative) modified to be specifically accumulated in mitochondria. The modification was performed through chemical conjugation of the quinones with penetrating cations: Rhodamine 19 or tetraphenylphosphonium. Neuroprotective properties were evaluated in a model of middle cerebral artery occlusion. We demonstrate that the mitochondria-targeted compounds, introduced immediately after reperfusion, possess various neuroprotective potencies as judged by the lower brain damage and higher neurological status. Plastoquinone derivatives conjugated with rhodamine were the most efficient, and the least efficiency was shown by antioxidants conjugated with tetraphenylphosphonium. Antioxidants were administered intraperitoneally or intranasally with the latter demonstrating a high level of penetration into the brain tissue. The therapeutic effects of both ways of administration were similar. Long-term administration of antioxidants in low doses reduced the neurological deficit, but had no effect on the volume of brain damage. At present, cationic decylrhodamine derivatives of plastoquinone appear to be the most promising anti-ischemic mitochondria-targeted drugs of the quinone family. We suggest these antioxidants could be potentially used for a stroke treatment.

Curcumin prevents perfluorooctane sulfonate-induced genotoxicity and oxidative DNA damage in rat peripheral blood

Perfluorooctane sulfonate (PFOS) is a man-made fluorosurfactant and global pollutant. PFOS a persistent and bioaccumulative compound, and it is widely distributed in humans and wildlife. Therefore, it was added to Annex B of the Stockholm Convention on Persistent Organic Pollutants in May 2009. Curcumin is a natural polyphenolic compound abundant in the rhizome of the perennial herb turmeric. It is commonly used as a dietary spice and coloring agent in cooking and anecdotally as an herb in traditional Asian medicine. In this study, male rats were treated with three different PFOS doses (0.6, 1.25, and 2.5 mg/kg) and one dose of curcumin, from Curcuma longa (80 mg/kg), and combined three doses of PFOS with 80 mg/kg dose of curcumin by gavage for 30 d at 48 h intervals. Here, we investigated the DNA damage via single-cell gel electrophoresis/comet assay and micronucleus test in rat peripheral blood in vivo. It is found that all doses of PFOS increased micronucleus frequency (p < 0.05) and strongly induced DNA damage in peripheral blood in two different parameters; the damaged cell percent and genetically damage index, and curcumin prevented the formation of DNA damage induced by PFOS. Results showed that curcumin inhibited DNA damage including GDI at certain levels at statistical manner, 30.07%, 54.41%, and 36.99% for 0.6 mg/kg, 1.25 mg/kg, and 2.5 mg/kg.

Bladder function in mice with inducible smooth muscle-specific deletion of the manganese superoxide dismutase gene

Manganese superoxide dismutase (MnSOD) is considered a critical component of the antioxidant systems that protect against oxidative damage. We are interested in the role of oxidative stress in bladder detrusor smooth muscle (SM) in different disease states. In this study, we generated an inducible, SM-specific Sod2(-/-) mouse model to investigate the effects of MnSOD depletion on the function of the bladder. We crossbred floxed Sod2 (Sod2(lox/lox)) mice with mice containing heterozygous knock-in of a gene encoding a tamoxifen-activated Cre recombinase in the SM22α promoter locus [SM-CreER(T2)(ki)(Cre/+)]. We obtained Sod2(lox/lox),SM-CreER(T2)(ki)(Cre/+) mice and injected 8-wk-old males with 4-hydroxytamoxifen to induce Cre-mediated excision of the floxed Sod2 allele. Twelve weeks later, SM-specific deletion of Sod2 and depletion of MnSOD were confirmed by polymerase chain reaction, immunoblotting, and immunohistochemistry. SM-specific Sod2(-/-) mice exhibited normal growth with no gross abnormalities. A significant increase in nitrotyrosine concentration was found in bladder SM tissue of SM-specific Sod2(-/-) mice compared with both wild-type mice and Sod2(+/+), SM-CreER(T2)(ki)(Cre/+) mice treated with 4-hydroxytamoxifen. Assessment of 24-h micturition in SM-specific Sod2(-/-) mice revealed significantly higher voiding frequency compared with both wild-type and SM-specific Cre controls. Conscious cystometry revealed significantly shorter intercontraction intervals and lower functional bladder capacity in SM-specific Sod2(-/-) mice compared with wild-type mice. This novel model can be used for exploring the mechanistic role of oxidative stress in organs rich in SM in different pathological conditions.

Damage response involves mechanisms conserved across plants, animals and fungi

All organisms are constantly exposed to adverse environmental conditions including mechanical damage, which may alter various physiological aspects of growth, development and reproduction. In plant and animal systems, the damage response mechanism has been widely studied. Both systems posses a conserved and sophisticated mechanism that in general is aimed at repairing and preventing future damage, and causes dramatic changes in their transcriptomes, proteomes, and metabolomes. These damage-induced changes are mediated by elaborate signaling networks, which include receptors/sensors, calcium (Ca(2+)) influx, ATP release, kinase cascades, reactive oxygen species (ROS), and oxylipin signaling pathways. In contrast, our current knowledge of how fungi respond to injury is limited, even though various reports indicate that mechanical damage triggers reproductive processes. In fungi, the damage response mechanism has been studied more in depth in Trichoderma atroviride. Interestingly, these studies indicate that the mechanical damage response involves ROS, Ca(2+), kinase cascades, and lipid signaling pathways. Here we compare the response to mechanical damage in plants, animals and fungi and provide evidence that they appear to share signaling molecules and pathways, suggesting evolutionary conservation across the three kingdoms.

Mitochondria are targets for the antituberculosis drug rifampicin in cultured epithelial cells

Rifampicin is a widely used drug for antituberculosis therapy. Its target is the bacterial RNA polymerase. After entry into the human or mammalian organism, rifampicin is accumulated in cells of epithelial origin (kidneys, liver, lungs) where it induces apoptosis, necrosis, and fibrosis. The purpose of this study was to determine the intracellular mechanisms leading to rifampicin-induced pathological changes and cell death. We analyzed the survival and state of the chondriome of cultured epithelial cells of the SPEV line under the influence of rifampicin. Our data show that the drug induces pronounced pathological changes in the network and ultrastructure of mitochondria, and their dysfunction results in excessive production of reactive oxygen species and release of cytochrome c. These data suggest the initiation of the mitochondrial pathway of apoptosis. Simultaneously, we observed inhibition of cell proliferation and changes in morphology of the epithelial cells toward fibroblast-like appearance, which could indicate induction of epithelial-mesenchymal transition. Thus, mitochondria are the main potential target for rifampicin in cells of epithelial origin. We suggest that similar mechanisms of pathological changes can be induced in vivo in organs and tissues accumulating rifampicin during chemotherapy of bacterial infectious diseases.

Role of oxidative stress and mitochondria in onset of urinary bladder dysfunction under acute urine retention

Acute urine retention is a frequent complication in patients with benign hyperplasia of the prostate gland. According to studies made on experimental animals and people, it is accompanied by the deterioration of the bladder blood supply. This study attempts to explore the relationship of intramural blood flow, production of reactive oxygen species, and functional state of the bladder detrusor in modeling of acute urine retention in rats, as well as the impact of mitochondria-targeted antioxidants (which are supposed to alleviate the effects of oxidative stress induced by experimental ischemia) on these parameters. The study showed beneficial effects of mitochondria-targeted antioxidant SkQR1 in preventing damage of the bladder caused by acute urinary retention, which suggests the therapeutic use of this type of compounds for the treatment of ischemic abnormalities of the urinary bladder.

Oxidative stress parameters in serum and low density lipoproteins of Hashimoto's thyroiditis patients with subclinical and overt hypothyroidism

BACKGROUND

Although prooxidant and antioxidant status were reported to be changed in clinical and experimental hypothyroidism, obtained results are conflicting. In addition, in subclinical hypothyroidism, scarced and controversial data are available about oxidative stress. Therefore, we aimed to investigate prooxidant-antioxidant status only in Hashimoto's thyroiditis (HT) patients with subclinical (sHT) and overt hypothyroidism (oHT).

SUBJECTS AND METHODS

Thirty sHT and 18 oHT patients and 30 healthy control subjects were included in the study. Endogenous and prooxidant 2,2'-azobis-(2-amidinopropane) hydrochloride (AAPH)-induced malondialdehyde (MDA), diene conjugate (DC), protein carbonyl (PC) and nitrotyrosine (NT) levels as well as ferric reducing antioxidant power (FRAP) were determined in serum. In addition, endogenous DC and copper-induced MDA levels were measured in low density lipoprotein (LDL) fraction.

RESULTS

Although there were no significant difference in serum endogenous MDA and DC levels, AAPH-induced MDA levels were significantly increased in sHT patients. All these parameters increased in oHT patients. Serum PC levels were detected to be increased in both sHT and oHT patients. Serum FRAP values did not alter in sHT patients, but they lowered in oHT patients. Endogenous DC and copper-induced MDA levels in LDL fraction did not change in sHT patients. However, these parameters were detected to be increased significantly in oHT patients as compared to controls and sHT patients.

CONCLUSION

In conclusion, there were significant increases in oxidative stress parameters in serum and LDL-fraction in oHT patients. However, oxidative stress was detected to stimulate partly in serum, but not LDL fraction in sHT patients.

Endurance training stimulates growth and survival pathways and the redox balance in rat pancreatic islets

Endurance training has been shown to increase pancreatic β-cell function and mass. However, whether exercise modulates β-cell growth and survival pathways signaling is not completely understood. This study investigated the effects of exercise on growth and apoptotic markers levels in rat pancreatic islets. Male Wistar rats were randomly assigned to 8-wk endurance training or to a sedentary control group. After that, pancreatic islets were isolated; gene expression and the total content and phosphorylation of several proteins related to growth and apoptotic pathways as well as the main antioxidant enzymes were determined by real-time polymerase chain reaction and Western blot analysis, respectively. Reactive oxygen species (ROS) production was measured by fluorescence. Endurance training increased the time to reach fatigue by 50%. Endurance training resulted in increased protein phosphorylation content of AKT (75%), AKT substrate (AS160; 100%), mTOR (60%), p70s6k (90%), and ERK1/2 (50%), compared with islets from control group. Catalase protein content was 50% higher, whereas ROS production was 49 and 77% lower in islets from trained rats under basal and stimulating glucose conditions, respectively. Bcl-2 mRNA and protein levels increased by 46 and 100%, respectively. Bax and cleaved caspase-3 protein contents were reduced by 25 and 50% in islets from trained rats, respectively. In conclusion, these results demonstrate that endurance training favors the β-cell growth and survival by activating AKT and ERK1/2 pathways, enhancing antioxidant capacity, and reducing ROS production and apoptotic proteins content.

Mitochondria and reactive oxygen species. Which role in physiology and pathology?

Oxidative stress is among the major causes of toxicity due to interaction of Reactive Oxygen Species (ROS) with cellular macromolecules and structures and interference with signal transduction pathways. The mitochondrial respiratory chain, specially from Complexes I and III, is considered the main origin of ROS particularly under conditions of high membrane potential, but several other sources may be important for ROS generation, such as mitochondrial p66(Shc), monoamine oxidase, α-ketoglutarate dehydogenase, besides redox cycling of redox-active molecules. ROS are able to oxidatively modify lipids, proteins, carbohydrates and nucleic acids in mitochondria and to activate/inactivate signalling pathways by oxidative modification of redox-active factors. Cells are endowed with several defence mechanisms including repair or removal of damaged molecules, and antioxidant systems, either enzymatic or non-enzymatic. Oxidative stress is at the basis of ageing and many pathological disorders, such as ischemic diseases, neurodegenerative diseases, diabetes, and cancer, although the underlying mechanisms are not always completely understood.

Inhibition of GSK-3β decreases the ischemia-induced death of renal cells

Pharmacological preconditioning with insulin and lithium ions prevented the death of renal cells under conditions of ischemia/reperfusion. Preincubation of cells with insulin or lithium ions decreased production of reactive oxygen species after ischemia/reoxygenation. These agents also prevented the development of mitochondrial dysfunction in renal cells induced by ischemia/reoxygenation. It was hypothesized that the protective effects of these agents are related to inhibition of glycogen synthase kinase-3(. This enzyme is inactivated upon phosphorylation of serine residue in position 9. We found that in vivo administration of lithium ions to animals before renal ischemia prevents the development of kidney failure.

Biochemical biomarkers of oxidative collagen damage

Collagens are major constituents of connective tissues in the animal kingdom. During aging and inflammatory-related diseases, the collagen network undergoes oxidation that leads to structural and biochemical alterations within the collagen molecule. Collagen oxidation appears to be a key determinant of aging and a critical physiopathologic mechanism of numerous diseases. Further, the detection of oxidized-collagen peptides seems to be a promising approach for the diagnosis and the prognosis of inflammatory diseases. This chapter reviews the structural and biochemical changes to collagen induced by reactive oxygen and nitrogen species and discusses recent data on the use of collagen-derived biomarkers for measuring oxidative damage.

Long-term dose-dependent response of Mequindox on aldosterone, corticosterone and five steroidogenic enzyme mRNAs in the adrenal of male rats

Mequindox (MEQ) is a synthetic quinoxaline 1,4-dioxides (QdNOs) derivative which can effectively improve growth and feed efficiency in animals. This study was to investigate the dose-dependent long-term toxicity in the adrenal of male rats exposed to 180 days of MEQ feed. Our data demonstrated that high doses of MEQ in the diet for 180 days led to adrenal damage and steroid hormone decrease, combined with sodium decrease and potassium increase in rat plasma. Significant changes of GSH and SOD in plasma were observed in the high doses (110, 275 mg/kg) groups. At the same doses, MEQ treatment down-regulated the mRNA levels of CYP11A1, CYP11B1 and CYP11B2 which located in mitochondria, but up-regulated mRNA levels of CYP21 and 3beta-HSD which located in endoplasmic reticulum. In conclusion, we reported the dose-dependent long-term toxicity of MEQ on adrenal gland in male rats, which raise awareness of its toxic effects to animals and consumers, and its mechanism may involve in oxidative stress and steroid hormone biosynthesis pathway.

The mitochondrial permeability transition, and oxidative and nitrosative stress in the mechanism of copper toxicity in cultured neurons and astrocytes

Copper is an essential element and an integral component of various enzymes. However, excess copper is neurotoxic and has been implicated in the pathogenesis of Wilson's disease, Alzheimer's disease, prion conditions, and other disorders. Although mechanisms of copper neurotoxicity are not fully understood, copper is known to cause oxidative stress and mitochondrial dysfunction. As oxidative stress is an important factor in the induction of the mitochondrial permeability transition (mPT), we determined whether mPT plays a role in copper-induced neural cell injury. Cultured astrocytes and neurons were treated with 20 microM copper and mPT was measured by changes in the cyclosporin A (CsA)-sensitive inner mitochondrial membrane potential (Delta Psi m), employing the potentiometric dye TMRE. In astrocytes, copper caused a 36% decrease in the Delta Psi m at 12 h, which decreased further to 48% by 24 h and remained at that level for at least 72 h. Cobalt quenching of calcein fluorescence as a measure of mPT similarly displayed a 45% decrease at 24 h. Pretreatment with antioxidants significantly blocked the copper-induced mPT by 48-75%. Copper (24 h) also caused a 30% reduction in ATP in astrocytes, which was completely blocked by CsA. Copper caused death (42%) in astrocytes by 48 h, which was reduced by antioxidants (35-60%) and CsA (41%). In contrast to astrocytes, copper did not induce mPT in neurons. Instead, it caused early and extensive death with a concomitant reduction (63%) in ATP by 14 h. Neuronal death was prevented by antioxidants and nitric oxide synthase inhibitors but not by CsA. Copper increased protein tyrosine nitration in both astrocytes and neurons. These studies indicate that mPT, and oxidative and nitrosative stress represent major factors in copper-induced toxicity in astrocytes, whereas oxidative and nitrosative stress appears to play a major role in neuronal injury.

Analysis of calcium ion homeostasis and mitochondrial function in cerebellar granule cells of adult CaV 2.1 calcium ion channel mutant mice

CaV 2.1 voltage-gated calcium channels (VGCC) are highly expressed by cerebellar neurons, and their dysfunction is linked to human disorders including familial hemiplegic migraine, episodic ataxia type 2 and spinocerebellar ataxia type 6. Altered calcium homeostasis, due to dysfunctional Ca(V 2.1 VGCC can severely affect mitochondrial function, eventually leading to neuronal cell death. We study leaner and tottering mice, which carry autosomal recessive mutations in the gene coding for the alpha 1A pore-forming subunit of CaV 2.1 VGCC. Both leaner and tottering mice exhibit cerebellar ataxia and epilepsy. Excessive leaner cerebellar granule cell (CGC) death starts soon after postnatal day 10, but it is not known whether the degree of CGC cell death observed in adult leaner mice is significantly different from wild type mice. We used Fluoro-Jade and TUNEL staining to quantify apoptotic cell death in leaner and wild type CGC. We investigated calcium homeostasis, mitochondrial function and generation of reactive oxygen species (ROS) in isolated CGC, using indicator dyes Fura-2AM, TMRM and CMH2DCFDA, respectively. We observed a small but significant increase in number of apoptotic adult leaner CGC. Calcium homeostasis and mitochondrial function also were altered in leaner CGC. However, no significant differences in ROS levels were observed. It is possible that CGC death in leaner mice may be related to mitochondrial dysfunction but may not be directly related to decreased basal intracellular calcium.

Oxidative stress modulates DNA methylation during melanocyte anchorage blockade associated with malignant transformation

Both oxidative/nitrosative stress and alterations in DNA methylation are observed during carcinogenesis of different tumor types, but no clear correlation between these events has been demonstrated until now. Melanoma cell lines were previously established after submitting the nontumorigenicmelanocyte lineage, melan-a, to cycles of anchorage blockade. In this work, increased intracellular oxidative species and nitric oxide levels, as well as alterations in the DNA methylation, were observed after melan-a detachment, which were also associated with a decrease in intracellular homocysteine (Hcy), an element in the methionine (universal methyl donor) cycle. This alteration was accompanied by increase in glutathione (GSH) levels and methylated DNA content. Furthermore, a significant increase in dnmt1 and 3b expression was identified along melan-a anchorage blockade. L(G)-Nitro-L-arginine methyl esther (L-NAME), known as a nitric oxide synthase (NOS) inhibitor, and N-acetyl-L-cysteine (NAC) prevented the increase in global DNA methylation, as well as the increase in dnmt1 and 3b expression, observed during melan-a detachment. Interestingly, both L-NAME and NAC did not inhibit nitric oxide (NO) production in these cells, but abrogated superoxide anion production during anchorage blockade. In conclusion, oxidative stress observed during melanocyte anchorage blockade seems to modulate DNA methylation levels and may directly contribute to the acquisition of an anoikis-resistant phenotype through an epigenetic mechanism.

The mitochondrion as janus bifrons

The signaling function of mitochondria is considered with a special emphasis on their role in the regulation of redox status of the cell, possibly determining a number of pathologies including cancer and aging. The review summarizes the transport role of mitochondria in energy supply to all cellular compartments (mitochondria as an electric cable in the cell), the role of mitochondria in plastic metabolism of the cell including synthesis of heme, steroids, iron-sulfur clusters, and reactive oxygen and nitrogen species. Mitochondria also play an important role in the Ca(2+)-signaling and the regulation of apoptotic cell death. Knowledge of mechanisms responsible for apoptotic cell death is important for the strategy for prevention of unwanted degradation of postmitotic cells such as cardiomyocytes and neurons.

The role of mitochondria in oxidative and nitrosative stress during ischemia/reperfusion in the rat kidney

Reoxygenation following ischemia causes tissue oxidative stress. We studied the role of oxidative stress caused by kidney ischemia/reperfusion (I/R) on the mitochondria of renal tissue slices. I/R caused the mitochondria to be swollen, fragmented, and have lower membrane potential. The mitochondria generated more reactive oxygen species (ROS) and nitric oxide (NO) in situ as measured by fluorescence of ROS- and NO-sensitive probes. Infusion of lithium ion, an inhibitor of glycogen kinase synthase-3, caused phosphorylation of its Ser-9 and restored the membrane potential and decreased ROS production of the mitochondrial fraction. Ischemic kidney and hypoxic rat preconditioning improved mitochondrial membrane potential and lowered ROS production caused by subsequent I/R similar to lithium ion infusion. Preconditioning normalized NO production in mitochondria as well. The drop in the mitochondrial membrane potential was prevented by NO synthase inhibition, demonstrating a strong contribution of NO to changes in mitochondrial energy metabolism during the I/R transition. Mitochondria in the I/R-stressed kidney contained less cytochrome c and more pro-apoptotic Bax, consistent with apoptotic degradation.

Nitrotyrosine and protein carbonyls are equally distributed in HT22 cells after nitrosative stress

The generation of reactive oxygen and nitrogen species is an inevitable result of cellular metabolism and environmental influence. Such oxidation processes are always combined with the formation of various protein oxidation products. Environmental oxidants might either be activated inside the cell or act by themselves. Therefore, differences in the localization of oxidant formation might change the major compartment of oxidant action. Therefore, we employed NO donors (SNOC, DETA/NO, and Spe/NO) alone or in combination with the redox-cycling bipyridinium compound paraquat, the superoxide- and NO-releasing compound SIN-1, the relatively more lipophilic oxidants tert-butyl and cumene hydroperoxide, and peroxynitrite itself to test the ability of these compounds to generate oxidized and nitrated proteins in various cellular compartments. Combined treatment with oxidants and nitrating compounds led to the formation of protein carbonyls and nitrotyrosine with a severalfold higher concentration in the cytosol, compared to the nucleus. In fluorescence microscopy studies, the resulting protein modifications show a similar distribution of oxidized proteins and nitrotyrosine with highest concentrations in the perinuclear area. Studying the time- and concentration-dependent formation and degradation of protein carbonyls and nitrated proteins large similarities could be measured. Therefore, it can be concluded that formation, localization, and kinetics of protein carbonyl and nitrotyrosine formation parallel each other depending on the stress-inducing agent.

Mitochondrial ROS-induced ROS release: an update and review

Unstable mitochondrial membrane potential and redox transitions can occur following insults including ischemia/reperfusion injury and toxin exposure, with negative consequences for mitochondrial integrity and cellular survival. These transitions can involve mechanisms such as the recently described process, "Reactive Oxygen Species (ROS)-induced ROS-release" (RIRR), and be generated by circuits where the mitochondrial permeability transition (MPT) pore and the inner membrane anion channel (IMAC) are involved. The exposure to excessive oxidative stress results in an increase in ROS reaching a threshold level that triggers the opening of one of the requisite mitochondrial channels. In turn, this leads to the simultaneous collapse of the mitochondrial membrane potential and a transient increased ROS generation by the electron transfer chain. Generated ROS can be released into cytosol and trigger RIRR in neighboring mitochondria. This mitochondrion-to-mitochondrion ROS-signaling constitutes a positive feedback mechanism for enhanced ROS production leading to potentially significant mitochondrial and cellular injury. This review and update considers a variety of RIRR mechanisms (involving MPT, IMAC and episodes of mitochondrial transient hyperpolarization). RIRR could be a general cell biology phenomenon relevant to the processes of programmed mitochondrial destruction and cell death, and may contribute to other mechanisms of post-ischemic pathologies, including arrhythmias.

dl-α-lipoic acid ameliorates cyclophosphamide induced cardiac mitochondrial injury

Mitochondria play a central role in heart metabolism and function. Administration of antineoplastic drug cyclophosphamide (CP) adversely affects the heart mitochondria which may result in cardiotoxicity. The present study is aimed at evaluating the role of lipoic acid (LA) in CP induced myocardial injury. Male albino rats of Wistar strain were used for the study. CP was administered as a single intraperitoneal injection (200 mg/kg BW). A decrease in the activities of TCA cycle enzymes such as succinate dehydrogenase, malate dehydrogenase and isocitrate dehydrogenase was noted in CP treated rats. Simultaneously there was a decrease in the activities of mitochondrial complexes of electron transport chain. Decrease in the activities of these enzymes suggests a loss in mitochondrial function and integrity. Ultrastuctural observations were also in agreement with the above abnormal changes. Loss of myofilaments and damage of mitochondrial cristae revealed the cytotoxic effect of CP. The supplementation of LA (25 mg/kg BW) restored the above abnormalities to near normalcy. The study brings out the importance of LA in improving the mitochondrial function in cardiac cells after CP administration.