Types Of Oxidative Stress Research Articles

Specific cancer types and prognosis in patients with variations in the KEAP1-NRF2 system: A retrospective cohort study.

The KEAP1-NRF2 system induces the expression of antioxidant genes in response to various types of oxidative stress. Some cancer cells activate this system, which increases their malignancy through genetic mutations. We performed a retrospective cohort study using the C-CAT database, which contains the gene-panel sequence data from 60,056 cases of diagnosed solid tumors. We analyzed somatic mutations in NRF2 and KEAP1 genes and their associations with clinical outcomes. Variants in the NRF2 gene were clustered in exon 2, which encodes the DLG and ETGE motifs essential for KEAP1 interaction. The NRF2 variants were frequently observed in esophageal and lung squamous cell carcinoma with frequencies of 35.9% and 19.6%, respectively. Among these mutations, the NRF2 variants in the ETGE motif were indicators of a worse prognosis. KEAP1 variants were found in 2.5% of all cases. The variants were frequent in lung cancer and showed a worse prognosis in lung and other types of adenocarcinomas. We then conducted gene expression analysis using TCGA data. While cancers with DLG and ETGE variants were similar in terms of gene expression profiles, there were significant differences between cancers with KEAP1 and NRF2 variants. Our results indicate that genetic alteration of the KEAP1-NRF2 pathway is a major factor in patient prognosis for each cancer type and its genetic variant. Variants in NRF2 and KEAP1 genes can characterize the biological basis of each cancer type and are involved in carcinogenesis, resistance to therapy, and other biological differences.

Sphingosine-1-Phosphate–Cathelicidin Axis Plays a Pivotal Role in the Development of Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer, caused by mutagenesis resulting from excess ultraviolet radiation or other types of oxidative stress. These stressors also upregulate production of a cutaneous innate immune element, cathelicidin antimicrobial peptide (CAMP), via endoplasmic reticulum (ER) stress-initiated, sphingosine-1-phosphate (S1P) signaling pathway. While CAMP has beneficial antimicrobial activities, it also can be pro-inflammatory and pro-carcinogenic. We addressed whether and how S1P-induced CAMP production leads to cSCC development. Our study demonstrated that: 1) CAMP expression is increased in cSCC cells and skin from cSCC patients; 2) S1P levels are elevated in cSCC cells, while inhibition of S1P production attenuates CAMP-stimulated cSCC growth; 3) exogenous CAMP stimulates cSCC, but not normal human keratinocyte growth; 4) blockade of formyl peptide receptor-like (FPRL) 1 protein, a CAMP receptor, attenuates cSCC growth as well as the growth and invasion of cSCC cells mediated by CAMP into an extracellular matrix-containing fibroblast substrate; 5) Foxp3+ regulatory T cell (which decreases anti-tumor immunity) levels increase in cSCC skin; and 6) CAMP induces ER stress in cSCC cells. Together, the ER stress-S1P-CAMP axis forms a vicious circle, creating a favorable environment for cSCC development, i.e., cSCC growth and invasion impedes anti-cancer immunity.

Evidence of a Viable but Nonculturable (VBNC) Phase in B. abortus S19 under Oxidative Stress (H2O2, -Fe2+, Bleach) and under Non-Oxidative Inhibitory Conditions (Isopropanol, Erythritol, Selenite).

The effect of oxidative stress on the survival of various Brucella species has not been fully investigated yet. We here conducted a study in which we investigated the effect of different types of oxidative stress (Fe2+, H2O2, bleach) versus non-oxidative inhibitory effects (selenite, erythritol, and isopropanol) on the survival of B. abortus S19, B. abortus S19 ∆mglA 3.14, and B. neotomae 5K33. The work focuses on the appearance of ATP-CFU quotient imbalances indicating the existence of a viable but nonculturable (VBNC) form of B. abortus S19, as has previously been shown.

Protective Effects of Lanostane Triterpenoids from Chaga Mushroom in Human Keratinocytes, HaCaT Cells, against Inflammatory and Oxidative Stresses.

Inotodiol, a lanostane-type triterpenoid, and many phytochemicals from Chaga mushrooms have been investigated for various allergic diseases. However, the anti-aging and anti-inflammatory activities of inotodiol under different types of oxidative stress and the impact of inotodiol on collagen and hyaluronan synthesis have not been sufficiently studied. Lanostane triterpenoids-rich concentrate, which contained 10% inotodiol as major (inotodiol concentrate), was prepared from Chaga and compared with pure inotodiol in terms of anti-inflammatory activities on a human keratinocyte cell line, HaCaT cells, under various stimulations such as stimulation with ultraviolet (UV) B or tumor necrosis factor (TNF)-α. In stimulation with TNF-α, interleukin (IL)-1β, IL-6, and IL-8 genes were significantly repressed by 0.44~4.0 μg/mL of pure inotodiol. UVB irradiation induced the overexpression of pro-inflammatory cytokines, but those genes were significantly suppressed by pure inotodiol or inotodiol concentrate. Moreover, pure inotodiol/inotodiol concentrate could also modulate the synthesis of collagen and hyaluronic acid by controlling COL1A2 and HAS2/3 expression, which implies a crucial role for pure inotodiol/inotodiol concentrate in the prevention of skin aging. These results illuminate the anti-inflammatory and anti-aging effects of pure inotodiol/inotodiol concentrate, and it is highly conceivable that pure inotodiol and inotodiol concentrate could be promising natural bioactive substances to be incorporated in therapeutic and beautifying applications.

NIR triggered photocatalytic and photothermal bifunctional MOF nanozyme using for improving osteoarthritis microenvironment by repairing injured chondrocytes of mitochondria

Osteoarthritis (OA) is one of the leading causes of chronic disability in the elderly. Effective clinical interventions for OA are still lacking, and new therapeutic measures are urgently needed. The emerging near-infrared light (NIR) sensitive nanozymes are attractive for their great potential and appeal in treating OA by repairing mitochondrial function and improving impaired autophagic flux. In this study, a NIR-sensitive tea polyphenol-modified zirconium-based porphyrin metal–organic framework (TP-Au@PCN) was introduced as a multifunctional nanoplatform for the treatment of OA. TEM and EDS mapping revealed that gold nanoclusters were uniformly distributed on the surface of the spherical particles. Electron spin resonance (ESR) analysis revealed that nanozymes could alleviate different types of oxidative stress. Molecular biology indicated that TP-Au@PCN reduced chondrocyte apoptosis and increased chondrocyte metabolism by 80.7%. An increase in chondrocyte-expressed type II collagen and proteoglycan content ensues. Injection of TP-Au@PCN effectively raised the joint temperature to 46.9 °C and controlled drug delivery under NIR excitation. Section staining revealed that eight weeks of intervention decreased the OARSI score in OA rats by approximately 67.0%. Transmission electron microscopy confirmed a significant improvement in intracellular mitochondrial morphology. The present study provides evidence that modifiable multifunctional nanozymes effectively repair cartilage-damaged mitochondria and promote cartilage regeneration, representing an appealing therapeutic strategy for OA.

The effect of antioxidants supplementation on oxidative stress and proinflammatory biomarkers in patients with chronic kidney disease: a systematic review and meta-analysis.

This systematic review and meta-analysis aimed to address the effect of antioxidant supplementation on oxidative stress and proinflammatory biomarkers in patients with Chronic Kidney Disease (CKD). Systematic literature searches from the date of inception up to September 16th, 2022, were performed on PubMed, SCOPUS, and the Cochrane Central Register of Controlled Trials using relevant keywords, i.e., "Chronic Kidney Disease" and "antioxidants", and "supplementation". All studies relevant to the selection criteria were included in the analysis, focusing on any type of oxidative stress and proinflammatory biomarkers. A meta-analysis of included literature was conducted if sufficient data was obtained. This systematic review involved 32 published studies, with most having a Jadad score of ≥ 3 (65.6%). Only studies on antioxidants, i.e., polyphenols (n=5) and vitamin E (n=6) in curcumin/turmeric, were sufficient to be included in a meta-analysis. Curcumin/turmeric supplementation was found to significantly reduce the serum c-reative protein (CRP) [standardized mean difference (SMD) -0.5238 (95% CI: -1.0495, 0.0019); p = 0.05; I2 = 78%; p = 0.001]. Similarly, vitamin E supplementation was found to significantly reduce the serum CRP [SMD -0.37 (95% CI: -0.711, -0.029); p = 0.03; I2= 53%; p = 0.06] , but not serum interleukin-6 (IL-6) [SMD -0.26 (95% CI: -0.68, 0.16); p = 0.22; I2 = 43%; p = 0.17] and malondialdehyde (MDA) content [SMD -0.94 (95% CI: -1.92, 0.04); p = 0.06; I2= 87%; p = 0.0005]. Our review suggests that curcumin/turmeric and vitamin E supplements effectively lower serum CRP levels in CKD patients, particularly those undergoing chronic dialysis (CKD-5D). Higher scales of randomized controlled trials (RCTs) are still needed for other antioxidants due to inconclusive and contradicting results.

The response of Naegleria gruberi to oxidative stress.

Aerobic organisms require oxygen for respiration but must simultaneously cope with oxidative damages inherently linked with this molecule. Unicellular amoeboflagellates of the genus Naegleria, containing both free-living species and opportunistic parasites, thrive in aerobic environments. However, they are also known to maintain typical features of anaerobic organisms. Here, we describe the mechanisms of oxidative damage mitigation in Naegleria gruberi and focus on the molecular characteristics of three noncanonical proteins interacting with oxygen and its derived reactive forms. We show that this protist expresses hemerythrin, protoglobin, and an aerobic-type rubrerythrin, with spectral properties characteristic of the cofactors they bind. We provide evidence that protoglobin and hemerythrin interact with oxygen in vitro and confirm the mitochondrial localization of rubrerythrin by immunolabeling. Our proteomic analysis and immunoblotting following heavy metal treatment revealed upregulation of hemerythrin, while rotenone treatment resulted in an increase in rubrerythrin protein levels together with a vast upregulation of alternative oxidase. Our study provided new insights into the mechanisms employed by N. gruberi to cope with different types of oxidative stress and allowed us to propose specific roles for three unique and understudied proteins: hemerythrin, protoglobin, and rubrerythrin.

Characterization of a sigma class GST (GSTS6) required for cellular detoxification and embryogenesis in Tribolium castaneum

The sigma glutathione S-transferases (GSTSs) are a class of cytosolic glutathione S transferases (GSTs) that play important roles in antioxidant defense in insects, but the mechanisms by which GSTSs contribute to antioxidant activity remain unclear. Here, we isolated a GSTS (GSTS6) from Tribolium castaneum and explored its function. Homology and phylogenetic analysis revealed that TcGSTS6 shared high identity with other evolutionarily conserved GSTSs. The recombinant TcGSTS6 protein had strong activity toward cumene hydroperoxide and 4-hydroxynonenal but low activity toward the universal substrate 1-chloro-2,4-dinitrobenzene. Exposure to various types of oxidative stress, including heat, cold, UV and pathogenic microbes, significantly induced TcGSTs6 expression, which indicates that it is involved in antioxidant defense. Knockdown TcGSTs6 by using RNA interference (RNAi) caused reduced antioxidant capacity, which was accomplished by cooperating with other antioxidant genes. Moreover, treatment with various insecticides such as phoxim, lambda-cyhalothrin, dichlorvos and carbofuran revealed that TcGSTS6 plays an important role in insecticide detoxification. The RNAi results showed that TcGSTS6 is essential for embryogenesis in T. castaneum. Our study elucidates the mechanism by which a GSTS contributes to antioxidant activity and enhances our understanding of the functional diversity of GSTSs in insects.

The impact of combinatorial stress on the growth dynamics and metabolome of Burkholderia mesoacidophila demonstrates the complexity of tolerance mechanisms.

The recently sequenced Burkholderia mesoacidophila (previously Pseudomonas mesoacidophila) is a soil organism and as such will be exposed to multiple concurrent stresses in the natural environment. The combinatorial stress potentially experienced by microbes in soil has not been investigated in detail. The impact of combinatorial stress on growth was investigated using tripartite variables-temperature, nutritional environment and either osmotic or oxidative stress. In nutritionally stringent conditions, increasing diamide concentration had no effect on growth while increasing H2 O2 concentration reduced both growth rate and maximum density. Metabolomic studies with oxidative stress revealed specific (unidentified) metabolites associated with diamide tolerance, and an overwhelming dominance of sugars and sugar alcohols in nutritionally stringent conditions with and without the additional stressor. Combinatorial stress tolerance is complex. Temperature had the greatest independent impact on growth, while the impact of the nutritional environment played a key role in oxidative stress tolerance. In nutritionally stringent conditions, the metabolome suggested different tolerance mechanisms for different types of oxidative stress. This work demonstrates the specificity of the stress response, and the need to consider multiple environmental factors to meaningfully investigate tolerance. Both environmental and clinical settings subject bacteria to combinatorial stress and this should be considered in the design of further studies.

Abstract 884: Interplay between NRF2 and GPX4 is critical for cancer cell survival in 3D spheroids

Abstract Antioxidants have historically been thought of as cancer preventative agents; however, increasing evidence in recent years indicate that antioxidants promote cancer cell survival. Using 3D spheroid models, our lab previously demonstrated that normal cells die in the inner layers of spheroids, whereas cancer cells survive. Multiple lines of evidence indicate that survival of inner cells within tumor spheroids is dependent on escape from apoptosis and reactive oxygen species (ROS)-induced cell death through upregulation of anti-apoptotic and antioxidant programs. While the mechanisms associated with apoptosis are well-established, there is relatively little understood about the cellular processes involved in ROS-induced cell death (origins of ROS, types of oxidative stress experienced, mechanisms of cell death, antioxidants involved etc.). Tumor cells with mutations in the nuclear factor erythroid 2-related factor 2 (NRF2) pathway that lead to hyperactivation of this transcription factor serve as an excellent model to study the role of antioxidant programs in the regulation of survival processes. NRF2 is the master regulator of the antioxidant response directly regulating expression of antioxidant enzymes as well as proteins required for the production of non-enzymatic antioxidants. Furthermore, mutations in the NRF2 pathway are frequent in tumor types that are associated with oxidative stress such as lung cancer. We found that knock-down of NRF2 affected cell survival and growth in 3D by regulating (i) cell proliferation and (ii) inner cell survival. To better understand the specific processes responsible for ROS-induced cell death and the antioxidant program(s) utilized by cancer cells to bypass these death programs, we performed CRISPR screens in 3D using lung cancer cell lines with NRF2 hyperactivation to identify downstream targets of NRF2 and/or antioxidants that collaborate with NRF2 to regulate cell survival and growth in 3D. As predicted, we observed drop-out of sgRNAs targeting NRF2. Notably, a top drop-out hit was glutathione peroxidase 4 (GPX4), an essential antioxidant enzyme that reduces membrane phospholipid hydroperoxides to prevent a form of non-apoptotic cell death known as ferroptosis. We found that inhibition of GPX4 resulted in elevated levels of lipid peroxidation and death in the inner cells of 3D spheroids which were rescuable by the ferroptosis inhibitor Ferrostatin-1, implicating ferroptotic cell death in 3D biology. Surprisingly, knock-down of NRF2 resulted in stabilization of GPX4 at the post-transcriptional level. Finally, knock-down of NRF2 combined with GPX4 inhibition induced cell death in both inner and outer cells of 3D spheroids. These data suggest that cancer cells exploit the functional interplay between NRF2 and GPX4 to survive in high oxidative stress environments. This work was supported by funding from the ROADS Program funded by F. Hoffmann-La Roche Ltd.. Note: This abstract was not presented at the meeting. Citation Format: Patricia Cho, Nobuaki Takahashi, Laura M. Selfors, Hendrik J. Kuiken, Joan S. Brugge. Interplay between NRF2 and GPX4 is critical for cancer cell survival in 3D spheroids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 884.

The Biochemical Relevance of Different Types of Oxidative Stress at the Ocular Level

The connection between oxidative stress and ocular injuries was highly debated, given the fact that, as a result of its particular structure, the eye may have different reactions when exposed to oxidative stress and visual activity and functionality are considerable compromised. Our experimental research focused on two types of induced oxidative stress on rats (disruption of circadian rhythm and diabetes mellitus) with impact on biochemical markers of oxidative stress. We have analysed the amplitude of significant antioxidant markers correlated with each individual type of antioxidant disorder. We observed alterations of stress biomarkers for all induced types of stress, but the most relevant are associated with diabetes mellitus and light exposure.

Stability of Tocopherol Homologs in Bulk Oils at 60°C Oxidation and Chlorophyll Photosensitization by the Action of Moisture

AbstractThe effects of deuterium oxide (D2O) on the stability of tocopherol homologs were evaluated in corn oil stored at 60°C or in the process of chlorophyll photosensitization. The degree of oxidation, changes in moisture, and the levels of tocopherol homologs were analyzed. The moisture content in corn oil incubated with deuterium‐free water (H2O) was significantly (P < 0.05) higher than that in corn oil incubated with D2O. The presence of D2O accelerated the rate of lipid oxidation in corn oil, irrespective of whether it has been oxidized at 60°C or has been photosensitized by chlorophyll. After exposure to either of the oxidative stresses, the stability of β + γ‐tocopherols present in corn oil was enhanced in the presence of D2O compared to corn oil incubated in the presence of H2O, or control corn oil without the addition of moisture. However, the stability of α‐tocopherol in corn oil incubated with D2O was significantly lower after oxidation at 60°C compared to the other conditions (P < 0.05), whereas it was significantly higher than under the other conditions after chlorophyll photosensitization (P < 0.05). The moisture and type of oxidative stress, therefore, play important roles in the stability of tocopherol homologs in bulk oils.

Comparative analysis of seven types of superoxide dismutases for their ability to respond to oxidative stress in Bombyx mori

Insects are well adapted to changing environmental conditions. They have unique systems for eliminating reactive oxygen species (ROS). Superoxide dismutase (SOD) is a key enzyme that plays a primary role in removing ROS. Bombyx mori is a lepidopteran insect, whose body size is larger than the model insect Drosophila melanogaster, which enabled us to more easily examine gene expression at the tissue level. We searched B. mori SOD (BmSOD) genes using genome database, and we analyzed their function under different type of oxidative stress. Consequently, we identified four new types of BmSODs in addition to the three types already known. Two of the seven types had a unique domain architecture that has not been discovered previously in the SOD family, and they were expressed in different tissues and developmental stages. Furthermore, these BmSODs responded differently to several kinds of stressors. Our results showed that the seven types of BmSODs are likely to play different roles in B. mori; therefore, B. mori could be used to distinguish the functions of each SOD for resistance to oxidative stress that changes with the environmental conditions.

The Steady State Concentration of Different Biomarkers of Oxidative Stress Reflect Different Types of Oxidative Stress

Oxidative stress (OS) is an intuitively defined term that depends on the criterion used to evaluate it. The MARK-AGE consortium recently published a thorough investigation of the age dependence of the OS as determined by the steady state concentrations of different biomarkers of OS. Most biomarkers correlate significantly with almost all the other biomarkers but the correlations were weak. The possibility that all these effects are manifestations of one type of OS has yet to be evaluated. We think that the different biomarkers reflect different types of OS. This conclusion accords with two lines of comparison. (i) the overlapping between the lists of OS, as studied by different biomarkers is very low and (2) MDA appears to be sensitive to both gender and age. Specifically, in women MDA concentration increases in a stepwise fashion at the age of about 50 and, GSH decreased with age apparently simultaneously with the increase of MDA level. By contrast the concentration of both protein carbonyls and nitrotyrosine were the same in men and women and appeared to be independent of age. In conclusion, it appears that different biomarkers reflect different types of OS and that MDA and GSH reflect the same type of OS.

Mfd protects against oxidative stress in Bacillus subtilis independently of its canonical function in DNA repair

BackgroundPrevious reports showed that mutagenesis in nutrient-limiting conditions is dependent on Mfd in Bacillus subtilis. Mfd initiates one type of transcription-coupled repair (TCR); this type of repair is known to target bulky lesions, like those associated with UV exposure. Interestingly, the roles of Mfd in repair of oxidative-promoted DNA damage and regulation of transcription differ. Here, we used a genetic approach to test whether Mfd protected B. subtilis from exposure to two different oxidants.ResultsWild-type cells survived tert-butyl hydroperoxide (t-BHP) exposure significantly better than Mfd-deficient cells. This protective effect was independent of UvrA, a component of the canonical TCR/nucleotide excision repair (NER) pathway. Further, our results suggest that Mfd and MutY, a DNA glycosylase that processes 8-oxoG DNA mismatches, work together to protect cells from lesions generated by oxidative damage. We also tested the role of Mfd in mutagenesis in starved cells exposed to t-BHP. In conditions of oxidative stress, Mfd and MutY may work together in the formation of mutations. Unexpectedly, Mfd increased survival when cells were exposed to the protein oxidant diamide. Under this type of oxidative stress, cells survival was not affected by MutY or UvrA.ConclusionsThese results are significant because they show that Mfd mediates error-prone repair of DNA and protects cells against oxidation of proteins by affecting gene expression; Mfd deficiency resulted in increased gene expression of the OhrR repressor which controls the cellular response to organic peroxide exposure. These observations point to Mfd functioning beyond a DNA repair factor in cells experiencing oxidative stress.

Indirect oxidative stress from pulmonary inflammation exceeds direct oxidative stress from chemical damage to mitochondria

The term oxidative stress was introduced by the National Toxicology Program (NTP) in 1985. It is now invoked as a contributing mechanism to the induction of tumors in chronic rodent cancer bioassays following administration of a chemical agent, especially via inhalation. The term oxidative stress is confusing as there are two different types of oxidative stress. Direct oxidative stress derives from chemical damage to mitochondrial energy-producing structures with concomitantly altered mitochondrial function. Indirect oxidative stress is frequently quantitatively greater than direct oxidative stress in terms of release of activated oxygen or nitrogen species secreted by one or more of 12 potential in situ or recruited inflammatory cell types. Evidence supporting a role for direct oxidative stress in chemical carcinogenesis comes from cell culture studies wherein the cells have been removed from their natural environment and denuded of defense systems, for example, removal of particles by cilia, macrophage engulfment of particles, and suspension and dilution of chemicals or particles in pulmonary surfactant. In contrast, extensive direct evidence from bronchoalveolar lung washes conducted on humans shows elevations in pulmonary macrophage and neutrophil counts, release of intravascular proteins into the extracellular space, and activation of pro-inflammatory cytokines that correlate with observed pulmonary pathology. Higher rates of lung cancer in smokers with chronic obstructive pulmonary disease (COPD) than in smokers at the same cigarette consumption level but without COPD demonstrate a positive contribution by pulmonary inflammation to pulmonary carcinogenesis. Indirect oxidative stress from pulmonary inflammation should be considered before allocating a primary carcinogenic role for direct oxidative stress.

Influence of Oxidants on the Stability of Tocopherol in Model Nanoemulsions: Role of Interfacial Membrane Organized by Nonionic Emulsifiers

Nanoemulsions were prepared by using emulsifiers with various sizes of hydrophilic and hydrophobic groups to determine the impact of interfacial characteristics on the stability of α-tocopherol incorporated into the nanoemulsions. The α-tocopherol concentration remaining after 3 weeks of storage at 25°C depended greatly on the type of oxidative stress, which indicated that the environment surrounding the oil droplets could determine the stability of α-tocopherol in nanoemulsions. α-Tocopherol was gradually degraded by radical-mediated oxidation over storage, and approximately 60% of its initial concentration remained after 3 weeks of storage. However, under acid- and iron-mediated oxidation, α-tocopherol concentration steeply decreases for the initial 3-day storage, but the degradation rate of α-tocopherol decreased after 3 days of storage and over 90% of the initial α-tocopherol remained after 3 weeks of storage. Interestingly, and contrary to our expectations, the thickness and/or density of the droplet interfacial membrane rarely affected the stability of α-tocopherol incorporated into nanoemulsions. Although it is difficult to generalize beyond α-tocopherol, we conclude that the properties of oil droplet surfaces had no influence on the storage stability of α-tocopherol encapsulated in the droplets.

25 - Oxidative stress induced S-thiolation by glutathione and homocysteine

Although Vitamin C (AA, ascorbic acid; ascorbate ion at physiological pH) has multiple functions in humans its primary role is most likely as antioxidant thereby protecting the organism against continuously produced oxidative stress. When ascorbate is oxidized it loses one electron to give an ascorbyl free radical (AR), which subsequently easily undergoes oxidation to dehydroascorbate (DHA). Both AR and DHA are rapidly reduced back to ascorbate by several enzymes including NADH-cytochrome b5 reductase, thioredoxin reductase, protein disulfide isomerase, glutaredoxin-1 (thioltransferase), some glutathione-S-transferases and small thiol containing molecules like glutathione (GSH) and homocysteine (HCY). Homocysteine is a non-protein amino acid, differing from cysteine by an additional –CH2- in the amino acid side-chain. There is a strong correlation between an elevated blood concentration of HCY and the risk of developing oxidative stress related pathologies including cardiovascular and neurological diseases. However, the mechanism(s) by which hyperhomocysteinemia induces endothelial and neurological dysfunction as well as the role of oxidative stress is still unknown. In this study, we demonstrate that DHA catalyses S-glutathionylation and S-homocysteinylation. Oxidative stress catalyzed heterodimer formation was investigated using DHA or hydrogen peroxide in the presence of both HCY and GSH. Interestingly, while hydrogen peroxide favors peptide S-glutathionylation the presence of DHA induces increased thiolation by homocysteine compared to by glutathione. Furthermore, both S-homocysteinylated peptide and Grx-1 can be glutathionylated by disulfide exchange with glutathione dimer. In contrast, preliminary results indicate that GSH reduces the S-homocysteinylated peptide without immediate peptide S-glutathionylation. Moreover, the sites of S-thiolation in recombinant Grx-1 was determined by LCMS/MS analyses. The biological role and type of oxidative stress that direct post-translational protein modifications remain to be further elucidated.

Wolbachia affects survival to different oxidative stressors dependent upon the genetic background in Drosophila melanogaster

AbstractIt is well known that the rate of ageing varies among individuals dependent on the genetic background. In the present study, we explore how Wolbachia infection (a common insect endosymbiont bacterium) and oxidative stress interact in ageing with respect to two different genetic backgrounds of Drosophila melanogaster. Naturally infected and cured lines of Drosophila are challenged with either paraquat or l‐arginine to generate two different types of oxidative stress. We first observe that removing Wolbachia infection shortens the lifespan in one genetic background but not in the other. Wolbachia infection only makes one of the genetic lines more sensitive to paraquat. However, only the line unaffected by Wolbachia in the paraquat treatment is protected by Wolbachia from l‐arginine induced stress. Hence, Wolbachia is modifying free radical defence via two different mechanisms dependent on the genetic background. This supports the idea that factors that can govern ageing (infection and oxidative stress) are not universal, but are specific to the genetic make‐up of an individual.

Differential correlations between changes to glutathione redox state, protein ubiquitination, and stress-inducible HSPA chaperone expression after different types of oxidative stress.

In primary bovine fibroblasts with an hspa1b/luciferase transgene, we examined the intensity of heat-shock response (HSR) following four types of oxidative stress or heat stress (HS), and its putative relationship with changes to different cell parameters, including reactive oxygen species (ROS), the redox status of the key molecules glutathione (GSH), NADP(H) NAD(H), and the post-translational protein modifications carbonylation, S-glutathionylation, and ubiquitination. We determined the sub-lethal condition generating the maximal luciferase activity and inducible HSPA protein level for treatments with hydrogen peroxide (H2O2), UVA-induced oxygen photo-activation, the superoxide-generating agent menadione (MN), and diamide (DA), an electrophilic and sulfhydryl reagent. The level of HSR induced by oxidative stress was the highest after DA and MN, followed by UVA and H2O2 treatments, and was not correlated to the level of ROS production nor to the extent of protein S-glutathionylation or carbonylation observed immediately after stress. We found a correlation following oxidative treatments between HSR and the level of GSH/GSSG immediately after stress, and the increase in protein ubiquitination during the recovery period. Conversely, HS treatment, which led to the highest HSR level, did not generate ROS nor modified or depended on GSH redox state. Furthermore, the level of protein ubiquitination was maximum immediately after HS and lower than after MN and DA treatments thereafter. In these cells, heat-induced HSR was therefore clearly different from oxidative stress-induced HSR, in which conversely early redox changes of the major cellular thiol predicted the level of HSR and polyubiquinated proteins.