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FEBS Letters Mar 2012Superoxide dismutases (SODs) catalyze the de toxification of superoxide. SODs therefore acquired great importance as O(2) became prevalent following the evolution of... (Review)
Review
Superoxide dismutases (SODs) catalyze the de toxification of superoxide. SODs therefore acquired great importance as O(2) became prevalent following the evolution of oxygenic photosynthesis. Thus the three forms of SOD provide intriguing insights into the evolution of the organisms and organelles that carry them today. Although ancient organisms employed Fe-dependent SODs, oxidation of the environment made Fe less bio-available, and more dangerous. Indeed, modern lineages make greater use of homologous Mn-dependent SODs. Our studies on the Fe-substituted MnSOD of Escherichia coli, as well as redox tuning in the FeSOD of E. coli shed light on how evolution accommodated differences between Fe and Mn that would affect SOD performance, in SOD proteins whose activity is specific to one or other metal ion.
Topics: Animals; Biological Evolution; Eukaryotic Cells; Humans; Models, Chemical; Molecular Conformation; Oxidation-Reduction; Prokaryotic Cells; Superoxide Dismutase; Superoxides
PubMed: 22079668
DOI: 10.1016/j.febslet.2011.10.048 -
Redox Biology Sep 2021The chief ROS formed by mitochondria are superoxide (O) and hydrogen peroxide (HO). Superoxide is converted rapidly to HO and therefore the latter is the chief ROS... (Review)
Review
The chief ROS formed by mitochondria are superoxide (O) and hydrogen peroxide (HO). Superoxide is converted rapidly to HO and therefore the latter is the chief ROS emitted by mitochondria into the cell. Once considered an unavoidable by-product of aerobic respiration, HO is now regarded as a central mitokine used in mitochondrial redox signaling. However, it has been postulated that O can also serve as a signal in mammalian cells. Progress in understanding the role of mitochondrial HO in signaling is due to significant advances in the development of methods and technologies for its detection. Unfortunately, the development of techniques to selectively measure basal O changes has been met with more significant hurdles due to its short half-life and the lack of specific probes. The development of sensitive techniques for the selective and real time measure of O and HO has come on two fronts: development of genetically encoded fluorescent proteins and small molecule reporters. In 2015, I published a detailed comprehensive review on the state of knowledge for mitochondrial ROS production and how it is controlled, which included an in-depth discussion of the up-to-date methods utilized for the detection of both superoxide (O) and HO. In the article, I presented the challenges associated with utilizing these probes and their significance in advancing our collective understanding of ROS signaling. Since then, many other authors in the field of Redox Biology have published articles on the challenges and developments detecting O and HO in various organisms [1-3]. There has been significant advances in this state of knowledge, including the development of novel genetically encoded fluorescent HO probes, several O sensors, and the establishment of a toolkit of inhibitors and substrates for the interrogation of mitochondrial HO production and the antioxidant defenses utilized to maintain the cellular HO steady-state. Here, I provide an update on these methods and their implementation in furthering our understanding of how mitochondria serve as cell ROS stabilizing devices for HO signaling.
Topics: Animals; Hydrogen Peroxide; Mitochondria; Oxidation-Reduction; Reactive Oxygen Species; Superoxides
PubMed: 34157640
DOI: 10.1016/j.redox.2021.102044 -
American Journal of Physiology.... Sep 2006We review gases that can affect oxidative stress and that themselves may be radicals. We discuss O(2) toxicity, invoking superoxide, hydrogen peroxide, and the hydroxyl... (Review)
Review
We review gases that can affect oxidative stress and that themselves may be radicals. We discuss O(2) toxicity, invoking superoxide, hydrogen peroxide, and the hydroxyl radical. We also discuss superoxide dismutase (SOD) and both ground-state, triplet oxygen ((3)O(2)), and the more energetic, reactive singlet oxygen ((1)O(2)). Nitric oxide ((*)NO) is a free radical with cell signaling functions. Besides its role as a vasorelaxant, (*)NO and related species have other functions. Other endogenously produced gases include carbon monoxide (CO), carbon dioxide (CO(2)), and hydrogen sulfide (H(2)S). Like (*)NO, these species impact free radical biochemistry. The coordinated regulation of these species suggests that they all are used in cell signaling. Nitric oxide, nitrogen dioxide, and the carbonate radical (CO(3)(*-)) react selectively at moderate rates with nonradicals, but react fast with a second radical. These reactions establish "cross talk" between reactive oxygen (ROS) and reactive nitrogen species (RNS). Some of these species can react to produce nitrated proteins and nitrolipids. It has been suggested that ozone is formed in vivo. However, the biomarkers that were used to probe for ozone reactions may be formed by non-ozone-dependent reactions. We discuss this fascinating problem in the section on ozone. Very low levels of ROS or RNS may be mitogenic, but very high levels cause an oxidative stress that can result in growth arrest (transient or permanent), apoptosis, or necrosis. Between these extremes, many of the gasses discussed in this review will induce transient adaptive responses in gene expression that enable cells and tissues to survive. Such adaptive mechanisms are thought to be of evolutionary importance.
Topics: Free Radicals; Humans; Oxygen; Superoxides
PubMed: 16627692
DOI: 10.1152/ajpregu.00614.2005 -
Redox Biology Aug 2023Using S-phase synchronized RPE1-hTERT cells exposed to the DNA damaging agent, methyl methanesulfonate, we show the existence of a redox state associated with...
Using S-phase synchronized RPE1-hTERT cells exposed to the DNA damaging agent, methyl methanesulfonate, we show the existence of a redox state associated with replication stress-induced senescence termed senescence-associated redox state (SA-redox state). SA-redox state is characterized by its reactivity with superoxide-sensing fluorescent probes such as dihydroethidine, lucigenin and mitosox and peroxynitrite or hydroxyl radical sensing probe hydroxyphenyl fluorescein (HPF) but not the hydrogen peroxide (HO) reactive fluorescent probe CM-HDCFDA. Measurement of GSH and GSSH also reveals that SA-redox state mitigates the level of total GSH rather than oxidizes GSH to GSSG. Moreover, supporting the role of superoxide (O) in the SA-redox state, we show that incubation of senescent RPE1-hTERT cells with the O scavenger, Tiron, decreases the reactivity of SA-redox state with the oxidants' reactive probes lucigenin and HPF while the HO antioxidant N-acetyl cysteine has no effect. SA-redox state does not participate in the loss of proliferative capacity, G2/M cell cycle arrest or the increase in SA-β-Gal activity. However, SA-redox state is associated with the activation of NF-κB, dictates the profile of the Senescence Associated Secretory Phenotype, increases TFEB protein level, promotes geroconversion evidenced by increased phosphorylation of S6K and S6 proteins, and influences senescent cells response to senolysis. Furthermore, we provide evidence for crosstalk between SA redox state, p53 and p21. While p53 mitigates the establishment of SA-redox state, p21 is critical for the sustained reinforcement of the SA-redox state involved in geroconversion and resistance to senolysis.
Topics: Superoxides; Hydrogen Peroxide; Cellular Senescence; Tumor Suppressor Protein p53; Oxidation-Reduction
PubMed: 37285741
DOI: 10.1016/j.redox.2023.102757 -
Archives of Biochemistry and Biophysics Mar 2017In this review, some of the recent developments in probes and assay techniques specific for superoxide (O) and hydrogen peroxide (HO) are discussed. Over the last... (Review)
Review
In this review, some of the recent developments in probes and assay techniques specific for superoxide (O) and hydrogen peroxide (HO) are discussed. Over the last decade, significant progress has been made in O and HO detection due to syntheses of new redox probes, better understanding of their chemistry, and development of specific and sensitive assays. For superoxide detection, hydroethidine (HE) is the most suitable probe, as the product, 2-hydroxyethidium, is specific for O. In addition, HE-derived dimeric products are specific for one-electron oxidants. As red-fluorescent ethidium is always formed from HE intracellularly, chromatographic techniques are required for detecting 2-hydroxyethidium. HE analogs, Mito-SOX and hydropropidine, exhibit the same reaction chemistry with O and one-electron oxidants. Thus, mitochondrial superoxide can be unequivocally detected using HPLC-based methods and not by fluorescence microscopy. Aromatic boronate-based probes react quantitatively with HO, forming a phenolic product. However, peroxynitrite and hypochlorite react more rapidly with boronates, forming the same product. Using ROS-specific probes and HPLC assays, it is possible to screen chemical libraries to discover specific inhibitors of NADPH oxidases. We hope that rigorous detection of O and HO in different cellular compartments will improve our understanding of their role in redox signaling.
Topics: Cell Proliferation; Chromatography, High Pressure Liquid; HEK293 Cells; Humans; Mitochondria; Oxidation-Reduction; Oxygen; Phenanthridines; Reactive Oxygen Species; Signal Transduction; Superoxides
PubMed: 27590268
DOI: 10.1016/j.abb.2016.08.021 -
Biochimica Et Biophysica Acta 2013Apart from complex I (NADH:ubiquinone oxidoreductase) the mitochondrial cytochrome bc1 complex (complex III; ubiquinol:cytochrome c oxidoreductase) has been identified... (Review)
Review
Apart from complex I (NADH:ubiquinone oxidoreductase) the mitochondrial cytochrome bc1 complex (complex III; ubiquinol:cytochrome c oxidoreductase) has been identified as the main producer of superoxide and derived reactive oxygen species (ROS) within the mitochondrial respiratory chain. Mitochondrial ROS are generally linked to oxidative stress, aging and other pathophysiological settings like in neurodegenerative diseases. However, ROS produced at the ubiquinol oxidation center (center P, Qo site) of complex III seem to have additional physiological functions as signaling molecules during cellular processes like the adaptation to hypoxia. The molecular mechanism of superoxide production that is mechanistically linked to the electron bifurcation during ubiquinol oxidation is still a matter of debate. Some insight comes from extensive kinetic studies with mutated complexes from yeast and bacterial cytochrome bc1 complexes. This review is intended to bridge the gap between those mechanistic studies and investigations on complex III ROS in cellular signal transduction and highlights factors that impact superoxide generation. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.
Topics: Electron Transport; Electron Transport Complex III; Heme; Humans; Mitochondrial Membranes; Models, Chemical; Models, Molecular; Protein Conformation; Protein Subunits; Superoxides
PubMed: 23269318
DOI: 10.1016/j.bbabio.2012.12.002 -
Free Radical Research Mar 2018Superoxide radical represents one of the most biologically relevant reactive oxygen species involved in numerous physiological and pathophysiological processes....
Superoxide radical represents one of the most biologically relevant reactive oxygen species involved in numerous physiological and pathophysiological processes. Superoxide measurement through the decay of an electron paramagnetic resonance (EPR) signal of a triarylmethyl (TAM) radical possesses the advantage of a high selectivity and relatively high rate constant of TAM reaction with the superoxide. Hereby we report a straightforward synthesis and characterization of a TAM-TAM biradical showing a high reactivity with superoxide (second-order rate constant, (6.7 ± 0.2) × 10 M s) enabling the measurement of superoxide radical by following the increase of a sharp EPR signal associated with the formation of a TAM-quinone-methide monoradical product.
Topics: Electron Spin Resonance Spectroscopy; Superoxides; Trityl Compounds
PubMed: 28817975
DOI: 10.1080/10715762.2017.1369058 -
British Journal of Pharmacology Jun 2017Insulin sensitivity and metabolic homeostasis depend on the capacity of adipose tissue to take up and utilize excess glucose and fatty acids. The key aspects that... (Review)
Review
UNLABELLED
Insulin sensitivity and metabolic homeostasis depend on the capacity of adipose tissue to take up and utilize excess glucose and fatty acids. The key aspects that determine the fuel-buffering capacity of adipose tissue depend on the physiological levels of the small redox molecule, nitric oxide (NO). In addition to impairment of NO synthesis, excessive formation of the superoxide anion (О ) in adipose tissue may be an important interfering factor diverting the signalling of NO and other reactive oxygen and nitrogen species in obesity, resulting in metabolic dysfunction of adipose tissue over time. Besides its role in relief from superoxide burst, enhanced NO signalling may be responsible for the therapeutic benefits of different superoxide dismutase mimetics, in obesity and experimental diabetes models. This review summarizes the role of NO in adipose tissue and highlights the effects of NO/О ratio 'teetering' as a promising pharmacological target in the metabolic syndrome.
LINKED ARTICLES
This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.
Topics: Adipose Tissue; Animals; Anti-Obesity Agents; Diabetes Mellitus, Type 2; Humans; Hypoglycemic Agents; Nitric Oxide; Obesity; Signal Transduction; Superoxides
PubMed: 27079449
DOI: 10.1111/bph.13498 -
Journal of Inorganic Biochemistry Jan 2021Neuronal nitric oxide synthase (nNOS) generates superoxide, particularly at sub-optimal l-arginine (l-Arg) substrate concentrations. Heat shock protein 90 (Hsp90) was...
Neuronal nitric oxide synthase (nNOS) generates superoxide, particularly at sub-optimal l-arginine (l-Arg) substrate concentrations. Heat shock protein 90 (Hsp90) was reported to inhibit superoxide generation from nNOS protein. However, commercially available Hsp90 product from bovine brain tissues with unspecified Hsp90α and Hsp90β contents and an undefined Hsp90 protein oligomeric state was utilized. These two Hsp90s can have opposite effect on superoxide production by NOS. Importantly, emerging evidence indicates that nNOS splice variants are involved in different biological functions by functioning distinctly in redox signaling. In the present work, purified recombinant human Hsp90α, in its native dimeric state, was used in electron paramagnetic resonance (EPR) spin trapping experiments to study the effects of Hsp90α on superoxide generation from nNOS splice variants nNOSμ and nNOSα. Human Hsp90α was found to significantly increase superoxide generation from nNOSμ and nNOSα proteins under l-Arg-depleted conditions and Hsp90α influenced superoxide production by nNOSμ and nNOSα at varying degrees. Imidazole suppressed the spin adduct signal, indicating that superoxide was produced at the heme site of nNOS in the presence of Hsp90α, whereas l-Arg repletion diminished superoxide production by the nNOS-Hsp90α. Moreover, NADPH consumption rate values exhibited a similar trend/difference as a function of Hsp90α and l-Arg. Together, these EPR spin trapping and NADPH oxidation kinetics results demonstrated noticeable Hsp90α-induced increases in superoxide production by nNOS and a distinguishable effect of Hsp90α on nNOSμ and nNOSα proteins.
Topics: Animals; HSP90 Heat-Shock Proteins; Humans; Nitric Oxide Synthase Type I; Rats; Superoxides
PubMed: 33181440
DOI: 10.1016/j.jinorgbio.2020.111298 -
International Journal of Molecular... May 2023Our study proposes a pharmacological strategy to target cancerous mitochondria via redox-cycling "mitocans" such as quinone/ascorbate (Q/A) redox-pairs, which makes...
Our study proposes a pharmacological strategy to target cancerous mitochondria via redox-cycling "mitocans" such as quinone/ascorbate (Q/A) redox-pairs, which makes cancer cells fragile and sensitive without adverse effects on normal cells and tissues. Eleven Q/A redox-pairs were tested on cultured cells and cancer-bearing mice. The following parameters were analyzed: cell proliferation/viability, mitochondrial superoxide, steady-state ATP, tissue redox-state, tumor-associated NADH oxidase (tNOX) expression, tumor growth, and survival. Q/A redox-pairs containing unprenylated quinones exhibited strong dose-dependent antiproliferative and cytotoxic effects on cancer cells, accompanied by overproduction of mitochondrial superoxide and accelerated ATP depletion. In normal cells, the same redox-pairs did not significantly affect the viability and energy homeostasis, but induced mild mitochondrial oxidative stress, which is well tolerated. Benzoquinone/ascorbate redox-pairs were more effective than naphthoquinone/ascorbate, with coenzyme Q0/ascorbate exhibiting the most pronounced anticancer effects in vitro and in vivo. Targeted anticancer effects of Q/A redox-pairs and their tolerance to normal cells and tissues are attributed to: (i) downregulation of quinone prenylation in cancer, leading to increased mitochondrial production of semiquinone and, consequently, superoxide; (ii) specific and accelerated redox-cycling of unprenylated quinones and ascorbate mainly in the impaired cancerous mitochondria due to their redox imbalance; and (iii) downregulation of tNOX.
Topics: Mice; Animals; Superoxides; Oxidation-Reduction; Ascorbic Acid; Quinones; Neoplasms; Adenosine Triphosphate
PubMed: 37176145
DOI: 10.3390/ijms24098435