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1
Schneider, Christin, Lisa Gebhardt, Stephanie Arndt, Sigrid Karrer, Julia L. Zimmermann, Michael J. M. Fischer, and Anja-Katrin Bosserhoff. "Acidification is an Essential Process of Cold Atmospheric Plasma and Promotes the Anti-Cancer Effect on Malignant Melanoma Cells." Cancers 11, no. 5 (May 14, 2019): 671. http://dx.doi.org/10.3390/cancers11050671.
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(1) Background: Cold atmospheric plasma (CAP) is ionized gas near room temperature. The anti-cancer effects of CAP were confirmed for several cancer types and were attributed to CAP-induced reactive species. However, the mode of action of CAP is still not well understood. (2) Methods: Changes in cytoplasmic Ca2+ level after CAP treatment of malignant melanoma cells were analyzed via the intracellular Ca2+ indicator fura-2 AM. CAP-produced reactive species were determined by fluorescence spectroscopic and protein nitration by Western Blot analysis. (3) Results: CAP caused a strong acidification of water and solutions that were buffered with the so-called Good buffers, while phosphate-buffered solutions with higher buffer capacity showed minor pH reductions. The CAP-induced Ca2+ influx in melanoma cells was stronger in acidic pH than in physiological conditions. NO formation that is induced by CAP was dose- and pH-dependent and CAP-treated solutions only caused protein nitration in cells under acidic conditions. (4) Conclusions: We describe the impact of CAP-induced acidification on the anti-cancer effects of CAP. A synergistic effect of CAP-induced ROS, RNS, and acidic conditions affected the intracellular Ca2+ level of melanoma cells. As the microenvironment of tumors is often acidic, further acidification might be one reason for the specific anti-cancer effects of CAP.
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Feigl, Gábor, Ádám Bordé, Árpád Molnár, and Zsuzsanna Kolbert. "Exogenous ascorbic acid is a pro-nitrant in Arabidopsis thaliana." Acta Biologica Szegediensis 62, no. 2 (January 30, 2019): 115–22. http://dx.doi.org/10.14232/abs.2018.2.115-122.
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Due to the intensified production of reactive nitrogen species (RNS) proteins can be modified by tyrosine nitration (PTN). Examination of PTN is a hot topic of plant biology, especially because the exact outcome of this modification is still pending. Both RNS and ascorbic acid (AsA) are redox-active molecules, which directly affect the redox state of cells. The possible link between RNS-dependent PTN and AsA metabolism was studied in RNS (gsnor1-3, nia1nia2) and AsA (vtc2-3) homeostasis Arabidopsis mutants. During physiological conditions, intensified PTN was detected in all mutant lines compared to the wild-type (WT); without altering nitration pattern. Moreover, the increased PTN seemed to be associated with endogenous peroxynitrite (ONOO-) levels, but it showed no tight correlation with endogenous levels of nitric-oxide (NO) or AsA. Exogenous AsA caused intensified PTN in WT, vtc2-3 and nia1nia2. In the background of increased PTN, significant NO and ONOO- accumulation was detected, indicating exogenous AsA-induced RNS burst. Interestingly, in AsA-triggered stress-situation, changes of NO levels seem to be primarily connected to the development of PTN. Our results point out for the first time that similarly to human and animal systems exogenous AsA exerts pro-nitrant effect on plant proteome.
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Carballeda Sangiao, Noelia, Susana Chamorro, Sonia de Pascual-Teresa, and Luis Goya. "Aqueous Extract of Cocoa Phenolic Compounds Protects Differentiated Neuroblastoma SH-SY5Y Cells from Oxidative Stress." Biomolecules 11, no. 9 (August 25, 2021): 1266. http://dx.doi.org/10.3390/biom11091266.
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Cocoa is a rich source of polyphenols, especially flavanols and procyanidin oligomers, with antioxidant properties, providing protection against oxidation and nitration. Cocoa phenolic compounds are usually extracted with methanol/ethanol solvents in order to obtain most of their bioactive compounds; however, aqueous extraction seems more representative of the physiological conditions. In this study, an aqueous extract of cocoa powder has been prepared and chemically characterized, and its potential protective effect against chemically-induced oxidative stress has been tested in differentiated human neuroblastoma SH-SY5Y cells. Neuronal-like cultured cells were pretreated with realistic concentrations of cocoa extract and its major monomeric flavanol component, epicatechin, and then submitted to oxidative stress induced by a potent pro-oxidant. After one hour, production of reactive oxygen species was evaluated by two different methods, flow cytometry and in situ fluorescence by a microplate reader. Simultaneously, reduced glutathione and antioxidant defense enzymes glutathione peroxidase and glutathione reductase were determined and the results used for a comparative analysis of both ROS (reactive oxygen species) methods and to test the chemo-protective effect of the bioactive products on neuronal-like cells. The results of this approach, never tested before, validate both analysis of ROS and indicate that concentrations of an aqueous extract of cocoa phenolics and epicatechin within a physiological range confer a significant protection against oxidative insult to neuronal-like cells in culture.
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Merry, T. L., R. M. Dywer, E. A. Bradley, S. Rattigan, and G. K. McConell. "Local hindlimb antioxidant infusion does not affect muscle glucose uptake during in situ contractions in rat." Journal of Applied Physiology 108, no. 5 (May 2010): 1275–83. http://dx.doi.org/10.1152/japplphysiol.01335.2009.
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There is evidence that reactive oxygen species (ROS) contribute to the regulation of skeletal muscle glucose uptake during highly fatiguing ex vivo contraction conditions via AMP-activated protein kinase (AMPK). In this study we investigated the role of ROS in the regulation of glucose uptake and AMPK signaling during low-moderate intensity in situ hindlimb muscle contractions in rats, which is a more physiological protocol and preparation. Male hooded Wistar rats were anesthetized, and then N-acetylcysteine (NAC) was infused into the epigastric artery (125 mg·kg−1·h−1) of one hindlimb (contracted leg) for 15 min before this leg was electrically stimulated (0.1-ms impulse at 2 Hz and 35 V) to contract at a low-moderate intensity for 15 min. The contralateral leg did not receive stimulation or local NAC infusion (rest leg). NAC infusion increased ( P < 0.05) plasma cysteine and cystine (by ∼360- and 1.4-fold, respectively) and muscle cysteine (by 1.5-fold, P = 0.001). Although contraction did not significantly alter muscle tyrosine nitration, reduced (GSH) or oxidized glutathione (GSSG) content, S-glutathionylation of protein bands at ∼250 and 150 kDa was increased ( P < 0.05) ∼1.7-fold by contraction, and this increase was prevented by NAC. Contraction increased ( P < 0.05) skeletal muscle glucose uptake 20-fold, AMPK phosphorylation 6-fold, ACCβ phosphorylation 10-fold, and p38 MAPK phosphorylation 60-fold, and the muscle fatigued by ∼30% during contraction and NAC infusion had no significant effect on any of these responses. This was despite NAC preventing increases in S-glutathionylation with contraction. In conclusion, unlike during highly fatiguing ex vivo contractions, local NAC infusion during in situ low-moderate intensity hindlimb contractions in rats, a more physiological preparation, does not attenuate increases in skeletal muscle glucose uptake or AMPK signaling.
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Filipovic, Milos R., Jan Miljkovic, Andrea Allgäuer, Ricardo Chaurio, Tatyana Shubina, Martin Herrmann, and Ivana Ivanovic-Burmazovic. "Biochemical insight into physiological effects of H2S: reaction with peroxynitrite and formation of a new nitric oxide donor, sulfinyl nitrite." Biochemical Journal 441, no. 2 (December 21, 2011): 609–21. http://dx.doi.org/10.1042/bj20111389.
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The reaction of hydrogen sulfide (H2S) with peroxynitrite (a key mediator in numerous pathological states) was studied in vitro and in different cellular models. The results show that H2S can scavenge peroxynitrite with a corresponding second order rate constant of 3.3±0.4×103 M−1·s−1 at 23°C (8±2×103 M−1·s−1 at 37°C). Activation parameters for the reaction (ΔH‡, ΔS‡ and ΔV‡) revealed that the mechanism is rather associative than multi-step free-radical as expected for other thiols. This is in agreement with a primary formation of a new reaction product characterized by spectral and computational studies as HSNO2 (thionitrate), predominantly present as sulfinyl nitrite, HS(O)NO. This is the first time a thionitrate has been shown to be generated under biologically relevant conditions. The potential of HS(O)NO to serve as a NO donor in a pH-dependent manner and its ability to release NO inside the cells has been demonstrated. Thus sulfide modulates the chemistry and biological effects of peroxynitrite by its scavenging and formation of a new chemical entity (HSNO2) with the potential to release NO, suppressing the pro-apoptotic, oxidative and nitrative properties of peroxynitrite. Physiological concentrations of H2S abrogated peroxynitrite-induced cell damage as demonstrated by the: (i) inhibition of apoptosis and necrosis caused by peroxynitrite; (ii) prevention of protein nitration; and (iii) inhibition of PARP-1 [poly(ADP-ribose) polymerase 1] activation in cellular models, implying that a major part of the cytoprotective effects of hydrogen sulfide may be mediated by modulation of peroxynitrite chemistry, in particular under inflammatory conditions.
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Backes, Anna T., Kathrin Reinmuth-Selzle, Anna Lena Leifke, Kira Ziegler, Carola S. Krevert, Georg Tscheuschner, Kurt Lucas, et al. "Oligomerization and Nitration of the Grass Pollen Allergen Phl p 5 by Ozone, Nitrogen Dioxide, and Peroxynitrite: Reaction Products, Kinetics, and Health Effects." International Journal of Molecular Sciences 22, no. 14 (July 16, 2021): 7616. http://dx.doi.org/10.3390/ijms22147616.
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The allergenic and inflammatory potential of proteins can be enhanced by chemical modification upon exposure to atmospheric or physiological oxidants. The molecular mechanisms and kinetics of such modifications, however, have not yet been fully resolved. We investigated the oligomerization and nitration of the grass pollen allergen Phl p 5 by ozone (O3), nitrogen dioxide (NO2), and peroxynitrite (ONOO–). Within several hours of exposure to atmospherically relevant concentration levels of O3 and NO2, up to 50% of Phl p 5 were converted into protein oligomers, likely by formation of dityrosine cross-links. Assuming that tyrosine residues are the preferential site of nitration, up to 10% of the 12 tyrosine residues per protein monomer were nitrated. For the reaction with peroxynitrite, the largest oligomer mass fractions (up to 50%) were found for equimolar concentrations of peroxynitrite over tyrosine residues. With excess peroxynitrite, the nitration degrees increased up to 40% whereas the oligomer mass fractions decreased to 20%. Our results suggest that protein oligomerization and nitration are competing processes, which is consistent with a two-step mechanism involving a reactive oxygen intermediate (ROI), as observed for other proteins. The modified proteins can promote pro-inflammatory cellular signaling that may contribute to chronic inflammation and allergies in response to air pollution.
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Kang, Minho, Atsushi Hashimoto, Aravind Gade, and Hamid I. Akbarali. "Interaction between hydrogen sulfide-induced sulfhydration and tyrosine nitration in the KATP channel complex." American Journal of Physiology-Gastrointestinal and Liver Physiology 308, no. 6 (March 15, 2015): G532—G539. http://dx.doi.org/10.1152/ajpgi.00281.2014.
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Hydrogen sulfide (H2S) is an endogenous gaseous mediator affecting many physiological and pathophysiological conditions. Enhanced expression of H2S and reactive nitrogen/oxygen species (RNS/ROS) during inflammation alters cellular excitability via modulation of ion channel function. Sulfhydration of cysteine residues and tyrosine nitration are the posttranslational modifications induced by H2S and RNS, respectively. The objective of this study was to define the interaction between tyrosine nitration and cysteine sulfhydration within the ATP-sensitive K+ (KATP) channel complex, a significant target in experimental colitis. A modified biotin switch assay was performed to determine sulfhydration of the KATP channel subunits, Kir6.1, sulphonylurea 2B (SUR2B), and nitrotyrosine measured by immunoblot. NaHS (a donor of H2S) significantly enhanced sulfhydration of SUR2B but not Kir6.1 subunit. 3-Morpholinosydnonimine (SIN-1) (a donor of peroxynitrite) induced nitration of Kir6.1 subunit but not SUR2B. Pretreatment with NaHS reduced the nitration of Kir6.1 by SIN-1 in Chinese hamster ovary cells cotransfected with the two subunits, as well as in enteric glia. Two specific mutations within SUR2B, C24S, and C1455S prevented sulfhydration by NaHS, and these mutations prevented NaHS-induced reduction in tyrosine nitration of Kir6.1. NaHS also reversed peroxynitrite-induced inhibition of smooth muscle contraction. These studies suggest that posttranslational modifications of the two subunits of the KATP channel interact to alter channel function. The studies described herein demonstrate a unique mechanism by which sulfhydration of one subunit modifies tyrosine nitration of another subunit within the same channel complex. This interaction provides a mechanistic insight on the protective effects of H2S in inflammation.
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Campolo, Nicolás, Federico M. Issoglio, Darío A. Estrin, Silvina Bartesaghi, and Rafael Radi. "3-Nitrotyrosine and related derivatives in proteins: precursors, radical intermediates and impact in function." Essays in Biochemistry 64, no. 1 (February 2020): 111–33. http://dx.doi.org/10.1042/ebc20190052.
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Abstract Oxidative post-translational modification of proteins by molecular oxygen (O2)- and nitric oxide (•NO)-derived reactive species is a usual process that occurs in mammalian tissues under both physiological and pathological conditions and can exert either regulatory or cytotoxic effects. Although the side chain of several amino acids is prone to experience oxidative modifications, tyrosine residues are one of the preferred targets of one-electron oxidants, given the ability of their phenolic side chain to undergo reversible one-electron oxidation to the relatively stable tyrosyl radical. Naturally occurring as reversible catalytic intermediates at the active site of a variety of enzymes, tyrosyl radicals can also lead to the formation of several stable oxidative products through radical–radical reactions, as is the case of 3-nitrotyrosine (NO2Tyr). The formation of NO2Tyr mainly occurs through the fast reaction between the tyrosyl radical and nitrogen dioxide (•NO2). One of the key endogenous nitrating agents is peroxynitrite (ONOO−), the product of the reaction of superoxide radical (O2•−) with •NO, but ONOO−-independent mechanisms of nitration have been also disclosed. This chemical modification notably affects the physicochemical properties of tyrosine residues and because of this, it can have a remarkable impact on protein structure and function, both in vitro and in vivo. Although low amounts of NO2Tyr are detected under basal conditions, significantly increased levels are found at pathological states related with an overproduction of reactive species, such as cardiovascular and neurodegenerative diseases, inflammation and aging. While NO2Tyr is a well-established stable oxidative stress biomarker and a good predictor of disease progression, its role as a pathogenic mediator has been laboriously defined for just a small number of nitrated proteins and awaits further studies.
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Moulian, Nathalie, Frédérique Truffault, Yvette Morot Gaudry-Talarmain, Alain Serraf, and Sonia Berrih-Aknin. "In vivo and in vitro apoptosis of human thymocytes are associated with nitrotyrosine formation." Blood 97, no. 11 (June 1, 2001): 3521–30. http://dx.doi.org/10.1182/blood.v97.11.3521.
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Most thymocytes are deleted by thymic selection. The mechanisms of cell death are far from being clear. Peroxynitrite is a powerful oxidant produced in vivo by the reaction of superoxide (O2•−) with nitric oxide (NO•) and is able to mediate apoptosis. The aim of this study was to analyze whether NO and peroxynitrite could play a role in human thymocyte apoptosis. The results indicate that 3-(4-morpholinyl)-sydnonimine (SIN-1, an O2•− and NO• donor) and chemically synthesized peroxynitrite, but not S-nitroso-N-acetyl-D,L-penicillamine (SNAP, an NO• donor), have a strong apoptotic effect on human thymocytes (annexin V staining and TUNEL reaction). This effect was inhibited by exogenous superoxide dismutase (SOD), which interacts with O2•− and inhibits the formation of peroxynitrite. Because peroxynitrite formation requires NO•, thymic stromal cells were investigated to determine if they produced NO•. Inducible NOS was synthesized in cultured thymic epithelial cells in certain conditions of cytokine stimulation, as shown by messenger RNA levels, protein analysis, and nitrite production in the supernatants. SIN-1–treated thymocytes had high levels of tyrosine nitration, abolished by the addition of exogenous SOD. Tyrosine nitration was also detected in thymus extracts and sections, suggesting the presence of peroxynitrite in situ. In thymus sections, clusters of nitrotyrosine-positive cells were found in the cortex and corticomedullary areas colocalized with cells positive in the TUNEL reaction. These data indicate an association between human thymocyte apoptosis and nitrotyrosine formation. Thus, the results support the notion of a physiologic role for peroxynitrite in human thymocyte apoptosis.
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Jankov, Robert P., Kathrine L. Daniel, Shira Iny, Crystal Kantores, Julijana Ivanovska, Nadya Ben Fadel, and Amish Jain. "Sodium nitrite augments lung S-nitrosylation and reverses chronic hypoxic pulmonary hypertension in juvenile rats." American Journal of Physiology-Lung Cellular and Molecular Physiology 315, no. 5 (November 1, 2018): L742—L751. http://dx.doi.org/10.1152/ajplung.00184.2018.
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Deficient nitric oxide (NO) signaling plays a critical role in the pathogenesis of chronic neonatal pulmonary hypertension (PHT). Physiological NO signaling is regulated by S-nitrosothiols (SNOs), which act both as a reservoir for NO and as a reversible modulator of protein function. We have previously reported that therapy with inhaled NO (iNO) increased peroxynitrite-mediated nitration in the juvenile rat lung, although having minimal reversing effects on vascular remodeling. We hypothesized that sodium nitrite (NaNO2) would be superior to iNO in enhancing lung SNOs, thereby contributing to reversal of chronic hypoxic PHT. Rat pups were exposed to air or hypoxia (13% O2) from postnatal days 1 to 21. Dose-response prevention studies were conducted from days 1–21 to determine the optimal dose of NaNO2. Animals then received rescue therapy with daily subcutaneous NaNO2 (20 mg/kg), vehicle, or were continuously exposed to iNO (20 ppm) from days 14–21. Chronic PHT secondary to hypoxia was both prevented and reversed by treatment with NaNO2. Rescue NaNO2 increased lung NO and SNO contents to a greater extent than iNO, without causing nitration. Seven lung SNO proteins upregulated by treatment with NaNO2 were identified by multiplex tandem mass tag spectrometry, one of which was leukotriene A4 hydrolase (LTA4H). Rescue therapy with a LTA4H inhibitor, SC57461A (10 mg·kg−1·day−1 sc), partially reversed chronic hypoxic PHT. We conclude that NaNO2 was superior to iNO in increasing tissue NO and SNO generation and reversing chronic PHT, in part via upregulated SNO-LTA4H.
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Reifenberger, Matthew S., Krista L. Arnett, Craig Gatto, and Mark A. Milanick. "The reactive nitrogen species peroxynitrite is a potent inhibitor of renal Na-K-ATPase activity." American Journal of Physiology-Renal Physiology 295, no. 4 (October 2008): F1191—F1198. http://dx.doi.org/10.1152/ajprenal.90296.2008.
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Peroxynitrite is a reactive nitrogen species produced when nitric oxide and superoxide react. In vivo studies suggest that reactive oxygen species and, perhaps, peroxynitrite can influence Na-K-ATPase function. However, the direct effects of peroxynitrite on Na-K-ATPase function remain unknown. We show that a single bolus addition of peroxynitrite inhibited purified renal Na-K-ATPase activity, with IC50 of 107 ± 9 μM. To mimic cellular/physiological production of peroxynitrite, a syringe pump was used to slowly release (∼0.85 μM/s) peroxynitrite. The inhibition of Na-K-ATPase activity induced by this treatment was similar to that induced by a single bolus addition of equal cumulative concentration. Peroxynitrite produced 3-nitrotyrosine residues on the α, β, and FXYD subunits of the Na pump. Interestingly, the flavonoid epicatechin, which prevented tyrosine nitration, was unable to blunt peroxynitrite-induced ATPase inhibition, suggesting that tyrosine nitration is not required for inhibition. Peroxynitrite led to a decrease in iodoacetamidofluorescein labeling, implying that cysteine modifications were induced. Glutathione was unable to reverse ATPase inhibition. The presence of Na+ and low MgATP during peroxynitrite treatment increased the IC50 to 145 ± 10 μM, while the presence of K+ and low MgATP increased the IC50 to 255 ± 13 μM. This result suggests that the EPNa conformation of the pump is slightly more sensitive to peroxynitrite than the E(K) conformation. Taken together, these results show that peroxynitrite is a potent inhibitor of Na-K-ATPase activity and that peroxynitrite can induce amino acid modifications to the pump.
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Ji, Lele, Feng Fu, Lihua Zhang, Wenchong Liu, Xiaoqing Cai, Lei Zhang, Qiangsun Zheng, Haifeng Zhang, and Feng Gao. "Insulin attenuates myocardial ischemia/reperfusion injury via reducing oxidative/nitrative stress." American Journal of Physiology-Endocrinology and Metabolism 298, no. 4 (April 2010): E871—E880. http://dx.doi.org/10.1152/ajpendo.00623.2009.
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It is well known that insulin possesses a cardioprotective effect and that insulin resistance is closely related to cardiovascular diseases. Peroxynitrite (ONOO−) formation may trigger oxidative/nitrative stress and represent a major cytotoxic effect in heart diseases. This study was designed to investigate whether insulin attenuates ONOO− generation and oxidative/nitrative stress in acute myocardial ischemia/reperfusion (MI/R). Adult male rats were subjected to 30 min of myocardial ischemia and 3 h of reperfusion. Rats randomly received vehicle, insulin, or insulin plus wortmannin. Arterial blood pressure and left ventricular pressure were monitored throughout the experiment. Insulin significantly improved cardiac functions and reduced myocardial infarction, apoptotic cell death, and blood creatine kinase/lactate dehydrogenase levels following MI/R. Myocardial ONOO− formation was significantly attenuated after insulin treatment. Moreover, insulin resulted in a significant increase in Akt and endothelial nitric oxide (NO) synthase (eNOS) phosphorylation, NO production, and antioxidant capacity in ischemic/reperfused myocardial tissue. On the other hand, insulin markedly reduced MI/R-induced inducible NOS (iNOS) and gp91phox expression in cardiac tissue. Inhibition of insulin signaling with wortmannin not only blocked the cardioprotection of insulin but also markedly attenuated insulin-induced antioxidative/antinitrative effect. Furthermore, the suppression on ONOO− formation by either insulin or an ONOO− scavenger uric acid reduced myocardial infarct size in rats subjected to MI/R. We concluded that insulin exerts a cardioprotective effect against MI/R injury by blocking ONOO− formation. Increased physiological NO production (via eNOS phosphorylation) and superoxide anion reduction contribute to the antioxidative/antinitrative effect of insulin, which can be reversed by inhibiting phosphatidylinositol 3′-kinase. These results provide important novel information on the mechanisms of cardiovascular actions of insulin.
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Porter, Joseph J., Hyo Sang Jang, Mohammad Mahfuzul Haque, Dennis J. Stuehr, and Ryan A. Mehl. "Tyrosine nitration on calmodulin enhances calcium-dependent association and activation of nitric-oxide synthase." Journal of Biological Chemistry 295, no. 8 (December 30, 2019): 2203–11. http://dx.doi.org/10.1074/jbc.ra119.010999.
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Production of reactive oxygen species caused by dysregulated endothelial nitric-oxide synthase (eNOS) activity is linked to vascular dysfunction. eNOS is a major target protein of the primary calcium-sensing protein calmodulin. Calmodulin is often modified by the main biomarker of nitroxidative stress, 3-nitrotyrosine (nitroTyr). Despite nitroTyr being an abundant post-translational modification on calmodulin, the mechanistic role of this modification in altering calmodulin function and eNOS activation has not been investigated. Here, using genetic code expansion to site-specifically nitrate calmodulin at its two tyrosine residues, we assessed the effects of these alterations on calcium binding by calmodulin and on binding and activation of eNOS. We found that nitroTyr–calmodulin retains affinity for eNOS under resting physiological calcium concentrations. Results from in vitro eNOS assays with calmodulin nitrated at Tyr-99 revealed that this nitration reduces nitric-oxide production and increases eNOS decoupling compared with WT calmodulin. In contrast, calmodulin nitrated at Tyr-138 produced more nitric oxide and did so more efficiently than WT calmodulin. These results indicate that the nitroTyr post-translational modification, like tyrosine phosphorylation, can impact calmodulin sensitivity for calcium and reveal Tyr site-specific gain or loss of functions for calmodulin-induced eNOS activation.
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Napieraj, Natalia, Małgorzata Reda, and Małgorzata Janicka. "The role of NO in plant response to salt stress: interactions with polyamines." Functional Plant Biology 47, no. 10 (2020): 865. http://dx.doi.org/10.1071/fp19047.
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Soil salinity is a major abiotic stress that limits plant growth and productivity. High concentrations of sodium chloride can cause osmotic and ionic effects. This stress minimises a plant’s ability to uptake water and minerals, and increases Na+ accumulation in the cytosol, thereby disturbing metabolic processes. Prolonged plant exposure to salt stress can lead to oxidative stress and increased production of reactive oxygen species (ROS). Higher plants developed some strategies to cope with salt stress. Among these, mechanisms involving nitric oxide (NO) and polyamines (PAs) are particularly important. NO is a key signalling molecule that mediates a variety of physiological functions and defence responses against abiotic stresses in plants. Under salinity conditions, NO donors increase growth parameters, reduce Na+ toxicity, maintain ionic homeostasis, stimulate osmolyte accumulation and prevent damages caused by ROS. NO enhances salt tolerance of plants via post-translational protein modifications through S-nitrosylation of thiol groups, nitration of tyrosine residues and modulation of multiple gene expression. Several reviews have reported on the role of polyamines in modulating salt stress plant response and the capacity to enhance PA synthesis upon salt stress exposure, and it is known that NO and PAs interact under salinity. In this review, we focus on the role of NO in plant response to salt stress, paying particular attention to the interaction between NO and PAs.
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Li, Jiayu, Jingjing Wei, Zhonghong Gao, Guochuan Yin, and Hailing Li. "The oxidative reactivity of three manganese(III) porphyrin complexes with hydrogen peroxide and nitrite toward catalytic nitration of protein tyrosine." Metallomics 13, no. 3 (February 12, 2021). http://dx.doi.org/10.1093/mtomcs/mfab005.
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Abstract Understanding the toxicological properties of MnIII-porphyrins (MnTPPS, MnTMPyP, or MnTBAP) can provide important biochemical rationales in developing them as the therapeutic drugs against protein tyrosine nitration-induced inflammation diseases. Here, we present a comprehensive understanding of the pH-dependent redox behaviors of these MnIII-porphyrins and their structural effects on catalyzing bovine serum albumin (BSA) nitration in the presence of H2O2 and NO2−. It was found that both MnTPPS and MnTBAP stand out in catalyzing BSA nitration at physiologically close condition (pH 8), yet they are less effective at pH 6 and 10. MnTMPyP was shown to have no ability to catalyze BSA nitration under all tested pHs (pH 6, 8, and 10). The kinetics and active intermediate determination through electrochemistry method revealed that both the pH-dependent redox behavior of the central metal cation and the antioxidant capability of porphin derivative contribute to the catalytic activities of three MnIII-porphyrins in BSA nitration in the presence of H2O2/NO2−. These comprehensive studies on the oxidative reactivity of MnIII-porphyrins toward BSA nitration may provide new clues for searching the manganese-based therapeutic drugs against the inflammation-related diseases.
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KOHUTIAR, M., A. ECKHARDT, I. MIKŠÍK, P. ŠANTOROVÁ, and J. WILHELM. "Proteomic Analysis of Peroxynitrite-Induced Protein Nitration in Isolated Beef Heart Mitochondria." Physiological Research, April 8, 2018, 239–50. http://dx.doi.org/10.33549/10.33549/physiolres.933608.
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Mitochondria are exposed to reactive nitrogen species under physiological conditions and even more under several pathologic states. In order to reveal the mechanism of these processes we studied the effects of peroxynitrite on isolated beef heart mitochondria in vitro. Peroxynitrite has the potential to nitrate protein tyrosine moieties, break the peptide bond, and eventually release the membrane proteins into the solution. All these effects were found in our experiments. Mitochondrial proteins were resolved by 2D electrophoresis and the protein nitration was detected by immunochemical methods and by nano LC-MS/MS. Mass spectrometry confirmed nitration of ATP synthase subunit beta, pyruvate dehydrogenase E1 component subunit beta, citrate synthase and acetyl-CoA acetyltransferase. Immunoblot detection using chemiluminiscence showed possible nitration of other proteins such as cytochrome b-c1 complex subunit 1, NADH dehydrogenase [ubiquinone] iron-sulfur protein 2, elongation factor Tu, NADH dehydrogenase [ubiquinone] flavoprotein 2, heat shock protein beta-1 and NADH dehydrogenase [ubiquinone] iron-sulfur protein 8. ATP synthase beta subunit was nitrated both in membrane and in fraction prepared by osmotic lysis. The high sensitivity of proteins to nitration by peroxynitrite is of potential biological importance, as these enzymes are involved in various pathways associated with energy production in the heart.
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KOHUTIAR, M., A. ECKHARDT, I. MIKŠÍK, P. ŠANTOROVÁ, and J. WILHELM. "Proteomic Analysis of Peroxynitrite-Induced Protein Nitration in Isolated Beef Heart Mitochondria." Physiological Research, April 8, 2018, 239–50. http://dx.doi.org/10.33549/physiolres.933608.
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Mitochondria are exposed to reactive nitrogen species under physiological conditions and even more under several pathologic states. In order to reveal the mechanism of these processes we studied the effects of peroxynitrite on isolated beef heart mitochondria in vitro. Peroxynitrite has the potential to nitrate protein tyrosine moieties, break the peptide bond, and eventually release the membrane proteins into the solution. All these effects were found in our experiments. Mitochondrial proteins were resolved by 2D electrophoresis and the protein nitration was detected by immunochemical methods and by nano LC-MS/MS. Mass spectrometry confirmed nitration of ATP synthase subunit beta, pyruvate dehydrogenase E1 component subunit beta, citrate synthase and acetyl-CoA acetyltransferase. Immunoblot detection using chemiluminiscence showed possible nitration of other proteins such as cytochrome b-c1 complex subunit 1, NADH dehydrogenase [ubiquinone] iron-sulfur protein 2, elongation factor Tu, NADH dehydrogenase [ubiquinone] flavoprotein 2, heat shock protein beta-1 and NADH dehydrogenase [ubiquinone] iron-sulfur protein 8. ATP synthase beta subunit was nitrated both in membrane and in fraction prepared by osmotic lysis. The high sensitivity of proteins to nitration by peroxynitrite is of potential biological importance, as these enzymes are involved in various pathways associated with energy production in the heart.
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Pu, Jun, Ben He, Erhe Gao, Xinliang Ma, and Yajing Wang. "Abstract 343: Activation of ROR-α, but not ROR-β or ROR-γ, Protects against Myocardial Ischemia/Reperfusion Injury." Circulation Research 115, suppl_1 (July 18, 2014). http://dx.doi.org/10.1161/res.115.suppl_1.343.
Full textAbstract:
Objectives: The RAR-related orphan receptors (RORs) are members of the nuclear receptor superfamily that play a pivotal role in many physiological processes, including regulation of the circadian rhythm, development, metabolism and immune function. Three different but highly homologous ROR isoforms, ROR-α, -β, and -γ, have been discovered separately. However, the functional roles of RORs in the heart have never been investigated. We investigate the role of RORs in the pathophysiology of acute myocardial ischemia/ reperfusion (MI/R) injury. Methods and Results: The endogenous RORα, but not RORβ or RORγ, was significantly upregulated after MI/R. Synthetic ROR agonists SR1078 and SR3335 reduced myocardial infarction and improved contractile function after MI/R. Mechanistically, ROR activation inhibited endoplasmic reticulum (ER) stress, attenuated mitochondrial impairment, reduced cardiomyocyte apoptosis, and inhibited MI/R-induced autophagy dysfunction. Moreover, ROR activation inhibited MI/R-induced oxidative stress and nitrative stress. The aforementioned cardioprotective effects of ROR agonists were impaired in the setting of cardiac-specific gene silencing of RORα, but not RORβ or RORγ subtype. In contrast, adenovirus-mediated cardiac RORα overexpression, but not RORβ or RORγ overexpression, decreased myocardial infarct size and improved cardiac function through attenuating oxidative/nitrative stress and inhibiting ER stress, mitochondrial impairment, and autophagy dysfunction. Finally, RORα sg/sg mice (loss-of-function mutation in RORα), but not RORβ-null or RORγ-null mice, increased MI/R injury (greater apoptosis, larger infarct size, and poor cardiac function), exacerbated MI/R-induced oxidative/nitrative stress, and aggravated endoplasmic-reticulum stress, mitochondrial dysfunction, and autophagy dysfunction. Conclusion: Our study provides the first direct evidence that RORα acts as a novel endogenous cardioprotective receptor against myocardial injury. RORα, but not RORβ or RORγ, is a novel cardiac protective receptor against MI/R injury, supporting for the drug development strategies specifically targeting RORα for the treatment of ischemic heart disease.
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Suvorava, Tatsiana, Stephanie Pick, and Georg Kojda. "Abstract 15259: Genetically Engineered eNOS Dimer Destabilization Impairs Blood Pressure Reducing Activity of eNOS in Mice." Circulation 132, suppl_3 (November 10, 2015). http://dx.doi.org/10.1161/circ.132.suppl_3.15259.
Full textAbstract:
Endothelial dysfunction and oxidative stress are associated with hypertension but whether endothelial superoxide plays a role in the early development of essential hypertension remains uncertain. In this study we investigated whether eNOS-derived endothelial oxidative stress is involved in the regulation of blood pressure (BP). Normal bovine eNOS (eNOS-Tg) or a novel dimer-destabilized eNOS-mutant harboring a partially disrupted zinc-finger (C101A-eNOS-Tg) was introduced in C57BL/6 mice using the endothelium-specific tie-2 promoter. Mice were monitored for aortic endothelium-dependent relaxation, systolic BP, levels of superoxide and several post-translational protein modifications indicating activity and/or increased vascular oxidative stress. Some groups of mice underwent voluntary exercise training or treatment with SOD mimetic Tempol (1mM). C101A-eNOS-Tg (aorta, skeletal muscle, left ventricular myocardium and lung) showed significantly increased superoxide generation, protein- and eNOS-tyrosine-nitration, eNOS-S-glutathionylation, eNOS1176/79 phosphorylation and Thr172-AMP kinase (AMPKα) phosphorylation as compared to eNOS-Tg and wildtype (WT)-controls. The localization of eNOS-Tg was restricted to endothelium as evidenced by immunohistochemical staining for eNOS and an endothelial-specific marker CD31. Exercise training increased phosphorylation of eNOS and AMPKα in WT while these physiologic adaptations were absent in C101A-eNOS-Tg. Aortic endothelium-dependent relaxation was similar in all strains. In striking contrast, C101A-eNOS-Tg displayed normal BP despite higher levels of eNOS, while eNOS-Tg showed significant hypotension. Tempol completely reversed the occurring protein modifications and significantly reduced BP in C101A-eNOS-Tg but not in WT. We observed that oxidative stress generated by endothelial-specific expression of genetically destabilized C101A- eNOS selectively prevents BP reducing activity of vascular eNOS, while having no effect on aortic endothelial dependent relaxation. Our data suggest that oxidative stress generated by eNOS dimer destabilization contributes to the regulation of blood pressure.