Phase-Transition Nanoparticles Enable Fluorescence Self-Reporting for Close-Loop Photodynamic Therapy.

Catalase overexpression attenuates angiotensinogen expression and apoptosis in diabetic mice

UVB Radiation Induces Apoptosis in Keratinocytes by Activating a Pathway Linked to “BLT2-Reactive Oxygen Species”

We examined whether cGMP-dependent protein kinase (PKG) and mitochondrial ATP-sensitive potassium (K(ATP)) channels are involved in S-nitroso-N-acetyl penicillamine (SNAP)-induced reactive oxygen species (ROS) generation. SNAP significantly increased ROS generation in cardiomyocytes. This increase was suppressed by both 5-hydroxydecanoate (5-HD) and glibenclamide. Direct opening of mitochondrial K(ATP) channels with diazoxide led to ROS generation. The increased ROS generation was reversed by N-(2-mercaptopropionyl)glycine (MPG), a scavenger of ROS. Myxothiazol partially suppressed the ROS generation. KT-5823, an inhibitor of PKG, prevented ROS generation, indicating that PKG is required for ROS generation. In addition, 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP), an activator of PKG, induced ROS generation. The effect of 8-BrcGMP was reversed by either 5-HD or MPG. YC-1, an activator of guanylyl cyclase, also increased ROS production, which was reversed by 5-HD. Neither LY-294002 nor wortmannin, the inhibitors of phosphatidylinositol 3-kinase (PI3-kinase), affected SNAP's action. In a whole heart study, SNAP significantly reduced infarct size. The anti-infarct effect of SNAP was abrogated by either MPG or 5-HD. This effect was also blocked by PD-98059, an ERK inhibitor, but not by LY-294002. A Western blotting study showed that SNAP significantly enhanced phosphorylation of ERK, which was reversed by MPG. These results suggest that SNAP-induced ROS generation is mediated by activation of PKG and mitochondrial K(ATP) channels and that opening of mitochondrial K(ATP) channels is the downstream event of PKG activation. ROS and mitochondrial K(ATP) channels participate in the anti-infarct effect of SNAP. Moreover, phosphorylation of ERK is the downstream signaling event of ROS and plays a role in the cardioprotection of SNAP.

Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca2+ release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.

BackgroundSystemic lupus erythematosus (SLE) is characterised by chronic stimulation of the innate and adaptive immune response. Oxidative stress resulting from Reactive Oxygen Species (ROS) generation is another hallmark of the...

Background: Our previous study identified a novel microRNA, miR-4673, which is upregulated in A549 cells exposed to paclitaxel (PTX). In this study, we investigated the role of miR-4673 in PTX-induced cytotoxicity. Methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, apoptosis assay, 5,5’,6,6’-Tetrachloro-1,1’,3,3’-tetraethyl-imidacarbocyanine iodide (JC-1) staining and 2’,7’-Dichlorofluorescein (DCFH) staining were used to evaluate cell viability, apoptosis, mitochondrial membrane potential (MMP) loss and reactive oxygen species (ROS) generation in A549 and H1299 cells. Bioinformatics analysis and Luciferase reporter assay were used to explore whether 8-oxoguanine-DNA glycosylase-1 (OGG1) is a target gene of miR-4673. Results: Enforced expression of miR-4673 decreased cell viability and increased PTX-induced apoptosis, MMP loss and reactive oxygen species (ROS) generation in A549 and H1299 cells. Bioinformatics analysis, which was used to identify potential target of miR-4673, revealed a binding site of miR-4673 in 3’UTR of OGG1. Luciferase reporters assays showed that miR-4673 specifically binds to ‘CUGUUGA’ in 3’UTR of OGG1. Enforced expression of miR-4673 decreased accumulation of OGG1. In addition, silencing OGG1 enhanced inhibitory effects of PTX on apoptosis, MMP loss and ROS generation, which is similar to effects of miR-4673. Moreover, enforced expression of OGG1 compromised promoting effects of miR-4673 on PTX-induced apoptosis, MMP loss and ROS generation. Conclusion: miR-4673 modulates PTX-induced apoptosis, MMP loss and ROS generation by targeting OGG1.

Photodynamic therapy as an emerging phototheranostic approach holds great potential for antibacterial treatment, but is limited by compromised reactive oxygen species (ROS) generation in an aggregate and hypoxic microenvironment. Herein, we report a molecular cationization approach to boost the ROS, especially type I ROS generation of aggregation-induced emission (AIE) photosensitizers for photodynamic treatment of drug-resistant bacteria. Such cationization reinforces the electron-accepting ability of the cationic moiety, promotes intersystem crossing (ISC), and increases electron separation and transfer processes. The resultant CTBZPyI exhibits largely enhanced ROS generation ability with predominant hydroxyl radical generation over its neutral counterpart in aggregate. Moreover, cationization also confers CTBZPyI with the bacterial binding ability and a moderate bacterial inactivation ability in the dark. Further light irradiation leads to superb antibacterial performance, which largely promotes the healing process of a MRSA-infected wound. Such a cationization strategy is expected to be a general strategy for the design of highly effective type I photosensitizers for bacterial infection treatment.

Nanotechnology offers unique advantages over small-molecule drugs by delivering a high payload of photosensitizers to the target tissue, providing flexibility in the excitation wavelengths, enabling longer retention in the target tissue, possessing regenerative reactive oxygen speciesproducing capability and stimulating the immune system.

Event Abstract Back to Event The Effect of Ca2+ on Reactive Oxygen Species Generation and Elimination in Brain Mitochondria Zsofia Komary1*, Laszlo Tretter1 and Vera Adam-Vizi1 1 Department of Medical Biochemistry, Semmelweis University, Hungary Mitochondria have an essential role in the intracellular ROS (reactive oxygen species) generation. Mitochondrial ROS production is a significant pathogenic factor both in acute ischemic and in chronic neurodegenerative diseases. Mitochondria however might play a role in the elimination of ROS as well. The purpose of our experiments was to describe the effects of Ca2+ on ROS production/ROS elimination in isolated brain mitochondria. H2O2 was measured by the Amplex red method. Ca2+ in the micromolar range caused permeability transition (PT) of mitochondria respiring on glutamate + malate. Parallel with the PT, ROS generation was reduced and loss of NAD(H) was observed. Inhibition of PT with ADP resulted in an increase of ROS production after addition of Ca2+. Mitochondrial ROS elimination was measured detecting the accumulation of H2O2. Micromolar [Ca2+] did not cause H2O2 accumulation neither in the presence nor in the absence of PT inhibitor ADP. Inhibition of the complexes of the respiratory chain (complex I inhibitor - rotenon, complex III inhibitor – antimycin) resulted in an extensive elevation of ROS generation, however it did not influence the efficacy of ROS elimination. Ca2+ acting in the presence of respiratory inhibitors increased ROS formation and reduced ROS elimination with antimycin, but combination of Ca2+ with rotenone did not influence ROS elimination. It is concluded that a Ca2+-mediated single hit on the mitochondrial metabolism does not prevent ROS elimination. Combination of Ca2+-load with inhibition of the respiratory chain can impair endogenous ROS scavenging. These results contribute to the understanding of the role of mitochondrial components in excitotoxic ROS production. Conference: 12th Meeting of the Hungarian Neuroscience Society, Budapest, Hungary, 22 Jan - 24 Jan, 2009. Presentation Type: Poster Presentation Topic: Pathophysiology and neurology - degenerative disorders Citation: Komary Z, Tretter L and Adam-Vizi V (2009). The Effect of Ca2+ on Reactive Oxygen Species Generation and Elimination in Brain Mitochondria. Front. Syst. Neurosci. Conference Abstract: 12th Meeting of the Hungarian Neuroscience Society. doi: 10.3389/conf.neuro.01.2009.04.160 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 05 Mar 2009; Published Online: 05 Mar 2009. * Correspondence: Zsofia Komary, Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary, komaryzsofia@yahoo.co.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Zsofia Komary Laszlo Tretter Vera Adam-Vizi Google Zsofia Komary Laszlo Tretter Vera Adam-Vizi Google Scholar Zsofia Komary Laszlo Tretter Vera Adam-Vizi PubMed Zsofia Komary Laszlo Tretter Vera Adam-Vizi Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Stimulated macrophages generate potent anti-microbial reactive oxygen and nitrogen species within their phagosomes. There is mounting evidence that ubiquitination plays a role in modulating macrophage bactericidal functions. Recently, we demonstrated that the ubiquitin ligase NKLAM was a component of the macrophage phagosome. In this present study we investigated the effects of NKLAM on macrophage generation of nitric oxide (NO) and reactive oxygen species. Stimulation with LPS induced wild type (WT) macrophages to produce NO in a time and concentration-dependent manner. NO production was attenuated in NKLAM-knock out (KO) macrophages. We also found that inducible nitric oxide synthase (iNOS) protein expression was lower and that iNOS translocation to the maturing phagosome was defective in KO macrophages. In vivo, intraperitoneal injection of LPS induced a time-dependent increase in serum nitrite (NO metabolite) in both WT and KO mice. However, nitrite levels in KO mice were lower than in WT mice. The generation of reactive oxygen species (ROS) is a potent killing mechanism; however the role of ubiquitination in regulating ROS generation is unclear. To this end, we investigated ROS production in WT and KO macrophages and found that ROS production was defective in KO macrophages stimulated with either PMA or Escherichia coli. Collectively, our data implicate NKLAM as a potent modulator of macrophage oxidative killing functions.

Proopiomelanocortin gene delivery induces apoptosis in melanoma through NADPH oxidase 4-mediated ROS generation

Since glucose intake acutely increases reactive oxygen species (ROS) generation by polymorphonuclear leucocytes (PMN) and mononuclear cells (MNC), we have now investigated whether a fast over a period of 48h reduces ROS generation by these cells. Eight normal subjects were fasted for 48h. Blood samples were obtained at 0, 24h and 48h. ROS generation by PMN fell significantly at 24h (66.1 +/- 19.5% of basal) and further at 48h (45.9 +/- 23.0 % of basal; p < 0.001). ROS generation by MNC fell to 62.4 +/- 16.5% at 24h and by 48.4 +/- 16.5% (p < 0.001) by 48h. The level of p47(phox) subunit, an index of NADPH oxidase, the enzyme converting molecular oxygen to superoxide (O(.)(2)(-)) radical, also fell in parallel. Plasma o-tyrosine/phenylalanine ratio fell significantly from 0.326 +/- 0.053 mmol/mol to 0.303 +/- 0.055 mmol/mol at 48h and m-tyrosine/phenylalanine ratio fell from 0.363 +/- 0.063 mmol/mol to 0.340 +/- 0.064 mmol/mol (p < 0.05). Thus, a 48h fast may reduce ROS generation, total oxidative load and oxidative damage to amino acids.

Diabetic nephropathy (DN) is characterized by perturbations in metabolic/cellular signaling pathways with generation of reactive oxygen species (ROS). The ROS are regarded as a common denominator of various pathways, and they inflict injury on renal glomerular cells. Recent studies indicate that tubular pathobiology also plays a role in the progression of DN. However, the mechanism(s) for how high (25 mm) glucose (HG) ambience induces tubular damage remains enigmatic. myo-Inositol oxygenase (MIOX) is a tubular enzyme that catabolizes myo-inositol to d-glucuronate via the glucuronate-xylulose (G-X) pathway. In this study, we demonstrated that G-X pathway enzymes are expressed in the kidney, and MIOX expression/bioactivity was up-regulated under HG ambience in LLC-PK1 cells, a tubular cell line. We further investigated whether MIOX overexpression leads to accentuation of tubulo-interstitial injury, as gauged by some of the parameters relevant to the progression of DN. Under HG ambience, MIOX overexpression accentuated redox imbalance, perturbed NAD(+)/NADH ratios, increased ROS generation, depleted reduced glutathione, reduced GSH/GSSG ratio, and enhanced adaptive changes in the profile of the antioxidant defense system. These changes were also accompanied by mitochondrial dysfunctions, DNA damage and induction of apoptosis, accentuated activity of profibrogenic cytokine, and expression of fibronectin, the latter two being the major hallmarks of DN. These perturbations were largely blocked by various ROS inhibitors (Mito Q, diphenyleneiodonium chloride, and N-acetylcysteine) and MIOX/NOX4 siRNA. In conclusion, this study highlights a novel mechanism where MIOX under HG ambience exacerbates renal injury during the progression of diabetic nephropathy following the generation of excessive ROS via an unexplored G-X pathway.

Phenytoin is a human and animal teratogen. Accumulating evidence suggests that the teratogenicity is associated with a potential of phenytoin to cause embryonic cardiac arrhythmia and resultant generation of toxic reactive oxygen species via hypoxia-reoxygenation mechanisms. The A/J mouse is more susceptible to phenytoin teratogenicity than other mouse strains. The aim of this study was to investigate whether A/J mice have other antioxidant enzyme activities than C57BL/6J and CD-1 mice. Also, strain differences in phenytoin effects on embryonic heart rate and rhythm were determined. Another objective was to determine whether a spin trapping agent with capacity to capture reactive oxygen species alter the developmental toxicity of phenytoin. Treatment with this agent resulted in a marked decrease in phenytoin teratogenicity, which supports the idea that reactive oxygen species are important mediators for the teratogenic action of phenytoin. The A/J mice embryos were most susceptible to the adverse cardiac effects of phenytoin and had the highest activity of superoxide dismutase and glutathione peroxidase, while the activity of catalase was the same in embryos of the three different strains. The high activities of antioxidant enzymes in the A/J stain indicate that the sensitivity to develop malformations is caused by excessive arrhythmia-related generation of reactive oxygen species rather than impaired antioxidant defense.

Endothelin-1 (ET-1) is implicated in fibroblast proliferation, which results in cardiac fibrosis. Both reactive oxygen species (ROS) generation and epidermal growth factor receptor (EGFR) transactivation play critical roles in ET-1 signal transduction. In this study, we used rat cardiac fibroblasts treated with ET-1 to investigate the connection between ROS generation and EGFR transactivation. ET-1 treatment was found to stimulate the phosphorylation of EGFR and ROS generation, which were abolished by ETA receptor antagonist N-(N-(N-((hexahydro-1H-azepin-1-yl)carbonyl)-L-leucyl)-D-tryptophyl)-D-tryptophan (BQ485). NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI), ROS scavenger N-acetyl cysteine (NAC), and p47phox small interfering RNA knockdown all inhibited the EGFR transactivation induced by ET-1. In contrast, EGFR inhibitor 4-(3'-chloroanilino)-6,7-dimethoxyquinazoline (AG-1478) cannot inhibit intracellular ROS generation induced by ET-1. Src homology 2-containing tyrosine phosphatase (SHP-2) was shown to be associated with EGFR during ET-1 treatment by EGFR coimmunoprecipitation. ROS have been reported to transiently oxidize the catalytic cysteine of phosphotyrosine phosphatases to inhibit their activity. We examined the effect of ROS on SHP-2 in cardiac fibroblasts using a modified malachite green phosphatase assay. SHP-2 was transiently oxidized during ET-1 treatment, and this transient oxidization could be repressed by DPI or NAC treatment. In SHP-2 knockdown cells, ET-1-induced phosphorylation of EGFR was dramatically elevated and is not influenced by NAC and DPI. However, this elevation was suppressed by GM6001 [a matrix metalloproteinase (MMP) inhibitor] and heparin binding (HB)-epidermal growth factor (EGF) neutralizing antibody. Our data suggest that ET-1-ETA-mediated ROS generation can transiently inhibit SHP-2 activity to facilitate the MMP-dependent and HB-EGF-stimulated EGFR transactivation and mitogenic signal transduction in rat cardiac fibroblasts.