Mitochondrial antioxidants abate SARS-COV-2 pathology in mice.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection inhibits mitochondrial oxidative phosphorylation (OXPHOS) and elevates mitochondrial reactive oxygen species (ROS, mROS) which activates hypoxia-inducible factor-1alpha (HIF-1α), shifting metabolism toward glycolysis to drive viral biogenesis but also causing the release of mitochondrial DNA (mtDNA) and activation of innate immunity. To determine whether mitochondrially targeted antioxidants could mitigate these viral effects, we challenged mice expressing human angiotensin-converting enzyme 2 (ACE2) with SARS-CoV-2 and intervened using transgenic and pharmacological mitochondrially targeted catalytic antioxidants. Transgenic expression of mitochondrially targeted catalase (mCAT) or systemic treatment with EUK8 decreased weight loss, clinical severity, and circulating levels of mtDNA; as well as reduced lung levels of HIF-1α, viral proteins, and inflammatory cytokines. RNA-sequencing of infected lungs revealed that mCAT and Eukarion 8 (EUK8) up-regulated OXPHOS gene expression and down-regulated HIF-1α and its target genes as well as innate immune gene expression. These data demonstrate that SARS-CoV-2 pathology can be mitigated by catalytically reducing mROS, potentially providing a unique host-directed pharmacological therapy for COVID-19 which is not subject to viral mutational resistance.

The protein phosphatase PC1 dephosphorylates and deactivates CatC to negatively regulate H2O2 homeostasis and salt tolerance in rice.

Catalase (CAT) is often phosphorylated and activated by protein kinases to maintain hydrogen peroxide (H2O2) homeostasis and protect cells against stresses, but whether and how CAT is switched off by protein phosphatases remains inconclusive. Here, we identified a manganese (Mn2+)-dependent protein phosphatase, which we named PHOSPHATASE OF CATALASE 1 (PC1), from rice (Oryza sativa L.) that negatively regulates salt and oxidative stress tolerance. PC1 specifically dephosphorylates CatC at Ser-9 to inhibit its tetramerization and thus activity in the peroxisome. PC1 overexpressing lines exhibited hypersensitivity to salt and oxidative stresses with a lower phospho-serine level of CATs. Phosphatase activity and seminal root growth assays indicated that PC1 promotes growth and plays a vital role during the transition from salt stress to normal growth conditions. Our findings demonstrate that PC1 acts as a molecular switch to dephosphorylate and deactivate CatC and negatively regulate H2O2 homeostasis and salt tolerance in rice. Moreover, knockout of PC1 not only improved H2O2-scavenging capacity and salt tolerance but also limited rice grain yield loss under salt stress conditions. Together, these results shed light on the mechanisms that switch off CAT and provide a strategy for breeding highly salt-tolerant rice.

Sensing of H2O2-induced oxidative stress by the UPF factor complex is crucial for activation of catalase-3 expression in Neurospora.

UPF-1-UPF-2-UPF-3 complex-orchestrated nonsense-mediated mRNA decay (NMD) is a well-characterized eukaryotic cellular surveillance mechanism that not only degrades aberrant transcripts to protect the integrity of the transcriptome but also eliminates normal transcripts to facilitate appropriate cellular responses to physiological and environmental changes. Here, we describe the multifaceted regulatory roles of the Neurospora crassa UPF complex in catalase-3 (cat-3) gene expression, which is essential for scavenging H2O2-induced oxidative stress. First, losing UPF proteins markedly slowed down the decay rate of cat-3 mRNA. Second, UPF proteins indirectly attenuated the transcriptional activity of cat-3 gene by boosting the decay of cpc-1 and ngf-1 mRNAs, which encode a well-studied transcription factor and a histone acetyltransferase, respectively. Further study showed that under oxidative stress condition, UPF proteins were degraded, followed by increased CPC-1 and NGF-1 activity, finally activating cat-3 expression to resist oxidative stress. Together, our data illustrate a sophisticated regulatory network of the cat-3 gene mediated by the UPF complex under physiological and H2O2-induced oxidative stress conditions.

Improved capacity for the repair of photosystem II via reinforcement of the translational and antioxidation systems in Synechocystis sp. PCC 6803.

In the cyanobacterium Synechocystis sp. PCC 6803, translation factor EF-Tu is inactivated by reactive oxygen species (ROS) via oxidation of Cys82 and the oxidation of EF-Tu enhances the inhibition of the repair of photosystem II (PSII) by suppressing protein synthesis. In our present study, we generated transformants of Synechocystis that overexpressed a mutated form of EF-Tu, designated EF-Tu (C82S), in which Cys82 had been replaced by a Ser residue, and ROS-scavenging enzymes individually or together. Expression of EF-Tu (C82S) alone in Synechocystis enhanced the repair of PSII under strong light, with the resultant mitigation of PSII photoinhibition, but it stimulated the production of ROS. However, overexpression of superoxide dismutase and catalase, together with the expression of EF-Tu (C82S), lowered intracellular levels of ROS and enhanced the repair of PSII more significantly under strong light, via facilitation of the synthesis de novo of the D1 protein. By contrast, the activity of photosystem I was hardly affected in wild-type cells and in all the lines of transformed cells under the same strong-light conditions. Furthermore, transformed cells that overexpressed EF-Tu (C82S), superoxide dismutase, and catalase were able to survive longer under stronger light than wild-type cells. Thus, the reinforced capacity for both protein synthesis and ROS scavenging allowed both photosynthesis and cell proliferation to tolerate strong light.

Methylation of a MITE insertion in the MdRFNR1-1 promoter is positively associated with its allelic expression in apple in response to drought stress.

Miniature inverted-repeat transposable elements (MITEs) are widely distributed in the plant genome and can be methylated. However, whether DNA methylation of MITEs is associated with induced allelic expression and drought tolerance is unclear. Here, we identified the drought-inducible MdRFNR1 (root-type ferredoxin-NADP+ oxidoreductase) gene in apple (Malus domestica). MdRFNR1 plays a positive role in drought tolerance by regulating the redox system, including increasing NADP+ accumulation and catalase and peroxidase activities and decreasing NADPH levels. Sequence analysis identified a MITE insertion (MITE-MdRF1) in the promoter of MdRFNR1-1 but not the MdRFNR1-2 allele. MdRFNR1-1 but not MdRFNR1-2 expression was significantly induced by drought stress, which was positively associated with the MITE-MdRF1 insertion and its DNA methylation. The methylated MITE-MdRF1 is recognized by the transcriptional anti-silencing factors MdSUVH1 and MdSUVH3, which recruit the DNAJ domain-containing proteins MdDNAJ1, MdDNAJ2, and MdDNAJ5, thereby activating MdRFNR1-1 expression under drought stress. Finally, we showed that MdSUVH1 and MdDNAJ1 are positive regulators of drought tolerance. These findings illustrate the molecular roles of methylated MITE-MdRF1 (which is recognized by the MdSUVH-MdDNAJ complex) in induced MdRFNR1-1 expression as well as the drought response of apple and shed light on the molecular mechanisms of natural variation in perennial trees.

High-Dose Isoniazid Lacks EARLY Bactericidal Activity against Isoniazid-resistant Tuberculosis Mediated by katG Mutations: A Randomized Phase II Clinical Trial.

Rationale: Observational studies suggest that high-dose isoniazid may be efficacious in treating multidrug-resistant tuberculosis. However, its activity against Mycobacterium tuberculosis (M.tb) with katG mutations (which typically confer high-level resistance) is not established. Objectives: To characterize the early bactericidal activity (EBA) of high-dose isoniazid in patients with tuberculosis caused by katG-mutated M.tb. Methods: A5312 was a phase IIA randomized, open-label trial. Participants with tuberculosis caused by katG-mutated M.tb were randomized to receive 15 or 20 mg/kg isoniazid daily for 7 days. Daily sputum samples were collected for quantitative culture. Intensive pharmacokinetic sampling was performed on Day 6. Data were pooled across all A5312 participants for analysis (drug-sensitive, inhA-mutated, and katG-mutated M.tb). EBA was determined using nonlinear mixed-effects modeling. Measurements and Main Results: Of 80 treated participants, 21 had katG-mutated M.tb. Isoniazid pharmacokinetics were best described by a two-compartment model with an effect of NAT2 acetylator phenotype on clearance. Model-derived maximum concentration and area under the concentration-time curve in the 15 and 20 mg/kg groups were 15.0 and 22.1 mg/L and 57.6 and 76.8 mg ⋅ h/L, respectively. Isoniazid bacterial kill was described using an effect compartment and a sigmoidal maximum efficacy relationship. Isoniazid potency against katG-mutated M.tb was approximately 10-fold lower than in inhA-mutated M.tb. The highest dose of 20 mg/kg did not demonstrate measurable EBA, except against a subset of slow NAT2 acetylators (who experienced the highest concentrations). There were no grade 3 or higher drug-related adverse events. Conclusions: This study found negligible bactericidal activity of high-dose isoniazid (15-20 mg/kg) in the majority of participants with tuberculosis caused by katG-mutated M.tb. Clinical trial registered with www.clinicaltrials.gov (NCT01936831).

Pepper catalase: a broad analysis of its modulation during fruit ripening and by nitric oxide.

Catalase is a major antioxidant enzyme located in plant peroxisomes that catalyzes the decomposition of H2O2. Based on our previous transcriptomic (RNA-Seq) and proteomic (iTRAQ) data at different stages of pepper (Capsicum annuum L.) fruit ripening and after exposure to nitric oxide (NO) enriched atmosphere, a broad analysis has allowed us to characterize the functioning of this enzyme. Three genes were identified, and their expression was differentially modulated during ripening and by NO gas treatment. A dissimilar behavior was observed in the protein expression of the encoded protein catalases (CaCat1-CaCat3). Total catalase activity was down-regulated by 50% in ripe (red) fruits concerning immature green fruits. This was corroborated by non-denaturing polyacrylamide gel electrophoresis, where only a single catalase isozyme was identified. In vitro analyses of the recombinant CaCat3 protein exposed to peroxynitrite (ONOO-) confirmed, by immunoblot assay, that catalase underwent a nitration process. Mass spectrometric analysis identified that Tyr348 and Tyr360 were nitrated by ONOO-, occurring near the active center of catalase. The data indicate the complex regulation at gene and protein levels of catalase during the ripening of pepper fruits, with activity significantly down-regulated in ripe fruits. Nitration seems to play a key role in this down-regulation, favoring an increase in H2O2 content during ripening. This pattern can be reversed by the exogenous NO application. While plant catalases are generally reported to be tetrameric, the analysis of the protein structure supports that pepper catalase has a favored quaternary homodimer nature. Taken together, data show that pepper catalase is down-regulated during fruit ripening, becoming a target of tyrosine nitration, which provokes its inhibition.

The Structural Biology of Catalase Evolution.

Catalases are essential enzymes for removal of hydrogen peroxide, enabling aerobic and anaerobic metabolism in an oxygenated atmosphere. Monofunctional heme catalases, catalase-peroxidases, and manganese catalases, evolved independently more than two billion years ago, constituting a classic example of convergent evolution. Herein, the diversity of catalase sequences is analyzed through sequence similarity networks, providing the context for sequence distribution of major catalase families, and showing that many divergent catalase families remain to be experimentally studied.

A role for the mitotic proteins Bub3 and BuGZ in transcriptional regulation of catalase-3 expression.

The spindle assembly checkpoint factors Bub3 and BuGZ play critical roles in mitotic process, but little is known about their roles in other cellular processes in eukaryotes. In aerobic organisms, transcriptional regulation of catalase genes in response to developmental or environmental stimuli is necessary for redox homeostasis. Here, we demonstrate that Bub3 and BuGZ negatively regulate cat-3 transcription in the model filamentous fungus Neurospora crassa. The absence of Bub3 caused a significant decrease in BuGZ protein levels. Our data indicate that BuGZ and Bub3 interact directly via the GLEBS domain of BuGZ. Despite loss of the interaction, the amount of BuGZ mutant protein negatively correlated with the cat-3 expression level, indicating that BuGZ amount rather than Bub3-BuGZ interaction determines cat-3 transcription level. Further experiments demonstrated that BuGZ binds directly to the cat-3 gene and responses to cat-3 overexpression induced by oxidative stresses. However, the zinc finger domains of BuGZ have no effects on DNA binding, although mutations of these highly conserved domains lead to loss of cat-3 repression. The deposition of BuGZ along cat-3 chromatin hindered the recruitment of transcription activators GCN4/CPC1 and NC2 complex, thereby preventing the assembly of the transcriptional machinery. Taken together, our results establish a mechanism for how mitotic proteins Bub3 and BuGZ functions in transcriptional regulation in a eukaryotic organism.

Redox status regulates autophagy in thymic stromal cells and promotes T cell tolerance.

Thymic stromal cells (TSCs) are critical regulators of T cell tolerance, but their basic biology has remained under-characterized because they are relatively rare and difficult to isolate. Recent work has revealed that constitutive autophagy in TSCs is required for self-antigen presentation and central T cell tolerance induction; however, the mechanisms regulating constitutive autophagy in TSCs are not well understood. Hydrogen peroxide has been shown to increase autophagy flux in other tissues, and we previously identified conspicuously low expression of the hydrogen peroxide-quenching enzyme catalase in TSCs. We investigated whether the redox status of TSCs established by low catalase expression regulates their basal autophagy levels and their capacity to impose central T cell tolerance. Transgenic overexpression of catalase diminished autophagy in TSCs and impaired thymocyte clonal deletion, concomitant with increased frequencies of spontaneous lymphocytic infiltrates in lung and liver and of serum antinuclear antigen reactivity. Effects on clonal deletion and autoimmune indicators were diminished in catalase transgenic mice when autophagy was rescued by expression of the Becn1F121A/F121A knock-in allele. These results suggest a metabolic mechanism by which the redox status of TSCs may regulate central T cell tolerance.

Natural variation in yeast reveals multiple paths for acquiring higher stress resistance.

BACKGROUND: Organisms frequently experience environmental stresses that occur in predictable patterns and combinations. For wild Saccharomyces cerevisiae yeast growing in natural environments, cells may experience high osmotic stress when they first enter broken fruit, followed by high ethanol levels during fermentation, and then finally high levels of oxidative stress resulting from respiration of ethanol. Yeast have adapted to these patterns by evolving sophisticated "cross protection" mechanisms, where mild 'primary' doses of one stress can enhance tolerance to severe doses of a different 'secondary' stress. For example, in many yeast strains, mild osmotic or mild ethanol stresses cross protect against severe oxidative stress, which likely reflects an anticipatory response important for high fitness in nature. RESULTS: During the course of genetic mapping studies aimed at understanding the mechanisms underlying natural variation in ethanol-induced cross protection against H2O2, we found that a key H2O2 scavenging enzyme, cytosolic catalase T (Ctt1p), was absolutely essential for cross protection in a wild oak strain. This suggested the absence of other compensatory mechanisms for acquiring H2O2 resistance in that strain background under those conditions. In this study, we found surprising heterogeneity across diverse yeast strains in whether CTT1 function was fully necessary for acquired H2O2 resistance. Some strains exhibited partial dispensability of CTT1 when ethanol and/or salt were used as mild stressors, suggesting that compensatory peroxidases may play a role in acquired stress resistance in certain genetic backgrounds. We leveraged global transcriptional responses to ethanol and salt stresses in strains with different levels of CTT1 dispensability, allowing us to identify possible regulators of these alternative peroxidases and acquired stress resistance in general. CONCLUSIONS: Ultimately, this study highlights how superficially similar traits can have different underlying molecular foundations and provides a framework for understanding the diversity and regulation of stress defense mechanisms.

Scavenging H2O2 of plant host by saliva catalase of leafhopper vector benefits viral transmission.

Catalase (CAT) is the main reactive oxygen species (ROS)-scavenging enzyme in plants and insects. However, it remains elusive whether and how insect saliva CAT suppresses ROS-mediated plant defense, thereby promoting initial virus transmission by insect vectors. Here, we investigated how leafhopper Recilia dorsalis catalase (RdCAT) was secreted from insect salivary glands into rice phloem, and how it was perceived by rice chaperone NO CATALASE ACTIVITY1 (OsNCA1) to scavenge excessive H2O2 during insect-to-plant virus transmission. We found that the interaction of OsNCA1 with RdCAT activated its enzymatic activity to decompose H2O2 in rice plants during leafhopper feeding. However, initial insect feeding did not significantly change rice CATs transcripts. Knockout of OsNCA1 in transgenic lines decreased leafhopper feeding-activated CAT activity and caused higher H2O2 accumulation. A devastating rice reovirus activated RdCAT expression and promoted the cosecretion of virions and RdCAT into leafhopper salivary cavities and ultimately into the phloem. Virus-mediated increase of RdCAT secretion suppressed excessive H2O2, thereby promoting host attractiveness to insect vectors and initial virus transmission. Our findings provide insights into how insect saliva CAT is secreted and perceived by plant chaperones to suppress the early H2O2 burst during insect feeding, thereby facilitating viral transmission.

ENHANCED DISEASE SUSCEPTIBILITY 1 promotes hydrogen peroxide scavenging to enhance rice thermotolerance.

Heat stress is a major factor limiting the production and geographic distribution of rice (Oryza sativa), and breeding rice varieties with tolerance to heat stress is of immense importance. Although extensive studies have revealed that reactive oxygen species (ROS) play a critical role in rice acclimation to heat stress, the molecular basis of rice controlling ROS homeostasis remains largely unclear. In this study, we discovered a novel heat-stress-responsive strategy that orchestrates ROS homeostasis centering on an immune activator, rice ENHANCED DISEASE SUSCEPTIBILITY 1 (OsEDS1). OsEDS1, which confers heat stress tolerance, promotes hydrogen peroxide (H2O2) scavenging by stimulating catalase activity through the OsEDS1-catalase association. The loss-of-function mutation in OsEDS1 causes increased sensitivity to heat stress, whereas the overexpression of OsEDS1 enhances thermotolerance. Furthermore, overexpression lines greatly improved rice tolerance to heat stress during the reproductive stage, which was associated with substantially increased seed setting, grain weight, and plant yield. Rice CATALASE C (OsCATC), whose activity is promoted by OsEDS1, degrades H2O2 to activate rice heat stress tolerance. Our findings greatly expand our understanding of heat stress responses in rice. We reveal a molecular framework that promotes heat tolerance through ROS homeostasis regulation, suggesting a theoretical basis and providing genetic resources for breeding heat-tolerant rice varieties.

Mitochondria-targeted catalase induced cell malignant transformation by the downregulation of p53 protein stability via USP28/miR-200b/PP2A-Cα axis.

Antioxidants exert a paradoxical influence on cancer prevention. The latest explanation for this paradox is the different target sites of antioxidants. However, it remains unclear how mitochondria-targeted antioxidants trigger specific p53-dependent pathways in malignant transformation models. Our study revealed that overexpression of mitochondria-targeted catalase (mCAT) instigated such malignant transformation via mouse double minute 2 homolog (MDM2) -mediated p53 degradation. In mouse epithelial JB6 Cl41 cells, the stable expression of mCAT resulted in MDM2-mediated p53 degradation, unlike in catalase-overexpressed Cl41 cells. Further, we demonstrated that mCAT overexpression upregulated ubiquitin-specific protease 28 (USP28) expression, which in turn stabilized c-Jun protein levels. This alteration initiated the activation of the miR-200b promoter transcription activity and a subsequent increase in miR-200b expression. Furthermore, elevated miR-200b levels then promoted its binding to the 3'-untranslated region of protein phosphatase 2A catalytic subunit (PP2A-C) α-isoform mRNA, consequently resulting in PP2A-C protein downregulation. This cascade of events ultimately contributed to increased MDM2 phosphorylation and p53 protein degradation. Thus, the mCAT overexpression triggers MDM2/p53-dependent malignant transformation through USP28/miR-200b/PP2A-Cα pathway, which may provide a new information for understanding mitochondria-targeted antioxidants facilitate the progression to the tumorigenic state.

Mutations of ribosomal protein genes induce overexpression of catalase in Saccharomyces cerevisiae.

Ribosome assembly defects result in ribosomopathies, primarily caused by inadequate protein synthesis and induced oxidative stress. This study aimed to investigate the link between deleting one ribosomal protein gene (RPG) paralog and oxidative stress response. Our results indicated that RPG mutants exhibited higher oxidant sensitivity than the wild type (WT). The concentrations of H2O2 were increased in the RPG mutants. Catalase and superoxide dismutase (SOD) activities were generally higher at the stationary phase, with catalase showing particularly elevated activity in the RPG mutants. While both catalase genes, CTT1 and CTA1, consistently exhibited higher transcription in RPG mutants, Ctt1 primarily contributed to the increased catalase activity. Stress-response transcription factors Msn2, Msn4, and Hog1 played a role in regulating these processes. Previous studies have demonstrated that H2O2 can cleave 25S rRNA via the Fenton reaction, enhancing ribosomes' ability to translate mRNAs associated with oxidative stress-related genes. The cleavage of 25S rRNA was consistently more pronounced, and the translation efficiency of CTT1 and CTA1 mRNAs was altered in RPG mutants. Our results provide evidence that the mutations in RPGs increase H2O2 levels in vivo and elevate catalase expression through both transcriptional and translational controls.

Aquimarina aquimarini sp. nov. and Aquimarina spinulae sp. nov., novel bacterial species with versatile natural product biosynthesis potential isolated from marine sponges.

This study describes two Gram-negative, flexirubin-producing, biofilm-forming, motile-by-gliding and rod-shaped bacteria, isolated from the marine sponges Ircinia variabilis and Sarcotragus spinosulus collected off the coast of Algarve, Portugal. Both strains, designated Aq135T and Aq349T, were classified into the genus Aquimarina by means of 16S rRNA gene sequencing. We then performed phylogenetic, phylogenomic and biochemical analyses to determine whether these strains represent novel Aquimarina species. Whereas the closest 16S rRNA gene relatives to strain Aq135T were Aquimarina macrocephali JAMB N27T (97.8 %) and Aquimarina sediminis w01T (97.1 %), strain Aq349T was more closely related to Aquimarina megaterium XH134T (99.2 %) and Aquimarina atlantica 22II-S11-z7T (98.1 %). Both strains showed genome-wide average nucleotide identity scores below the species level cut-off (95 %) with all Aquimarina type strains with publicly available genomes, including their closest relatives. Digital DNA-DNA hybridization further suggested a novel species status for both strains since values lower than 70 % hybridization level with other Aquimarina type strains were obtained. Strains Aq135T and Aq349T grew from 4 to 30°C and with between 1-5 % (w/v) NaCl in marine broth. The most abundant fatty acids were iso-C17 : 03-OH and iso-C15 : 0 and the only respiratory quinone was MK-6. Strain Aq135T was catalase-positive and ß-galactosidase-negative, while Aq349T was catalase-negative and ß-galactosidase-positive. These strains hold unique sets of secondary metabolite biosynthetic gene clusters and are known to produce the peptide antibiotics aquimarins (Aq135T) and the trans-AT polyketide cuniculene (Aq349T), respectively. Based on the polyphasic approach employed in this study, we propose the novel species names Aquimarina aquimarini sp. nov. (type strain Aq135T=DSM 115833T=UCCCB 169T=ATCC TSD-360T) and Aquimarina spinulae sp. nov. (type strain Aq349T=DSM 115834T=UCCCB 170T=ATCC TSD-361T).

Amine oxidase copper-containing 3 aggravates cardiac remodelling by generating hydrogen peroxide after myocardial infarction.

Amine oxidase copper-containing 3 (AOC3) is a member of the semicarbazide-sensitive amine oxidase enzyme family. It acts as an ectoenzyme catalysing the oxidative deamination of primary amines and generating hydrogen peroxide (H2 O2 ). While AOC3 is implicated in cardiovascular diseases such as atherosclerosis, its role in cardiac remodelling after myocardial infarction (MI) is unclear. In this study, we first confirmed a long-term upregulation of AOC3 in both cardiac myofibroblasts after MI in vivo and angiotensin II (ANGII)-treated cardiac fibroblasts in vitro. AOC3 knockdown not only inhibited the activation of cardiac fibroblasts induced by ANGII but also alleviated cardiac fibrosis in mice after MI. Using sh-AOC3 lentiviruses, exogenous recombinant AOC3 (r-AOC3), semicarbazide (an AOC3 inhibitor), and catalase (a hydrogen peroxide scavenger) treatments, we also demonstrated that AOC3 promoted H2 O2 generation, increased oxidative stress, and enhanced ERK1/2 activation, which were responsible for the activation of cardiac fibroblasts. In particular, AOC3 knockdown also improved cardiac function and hypertrophy after MI. Through a coculture system, we confirmed that AOC3 expressed on cardiac myofibroblasts was able to enhance oxidative stress and induce hypertrophy of cardiomyocytes by promoting H2 O2 generation. Similarly, r-AOC3 promoted H2 O2 generation and resulted in oxidative stress and hypertrophy of cardiomyocytes, which were almost inhibited by both semicarbazide and catalase. In conclusion, AOC3 plays a critical role in cardiac fibrosis and hypertrophy after MI by promoting the generation of H2 O2 . AOC3 is a promising therapeutic target against cardiac remodelling. © 2023 The Pathological Society of Great Britain and Ireland.

Biochemical and molecular evaluation of oxidative stress and mitochondrial damage in fruit fly exposed to carmoisine.

BACKGROUND: In today's world, appearance is an important factor in almost all areas of our lives. Therefore, it has become common to use dyes to color foods to make them look appetizing and visually appealing. However, food additives have negative effects on biochemical processes in cells at both high and low doses. METHODS AND RESULTS: This study investigated the effect of carmoisine, a commonly used food coloring, on oxidative stress and damage parameters in Drosophila melanogaster in terms of both enzymatic and gene expression. The change in mitochondrial DNA copy number (mtDNA-CN), a marker of oxidative stress, was also examined. When the data obtained were analyzed, it was observed that carmoisine caused a significant decrease in GSH levels depending on the increase in dose. SOD, CAT, GPx, and AChE enzyme activities and gene expression levels were also found to be significantly decreased. All groups also showed a significant decrease in mtDNA-CN. The effect of carmoisine on Drosophila melanogaster morphology was also investigated in our study. However, no significant change was observed in terms of morphological development in any group. CONCLUSIONS: When all the findings were evaluated together, it was observed that carmoisin triggered oxidative stress and these effects became more risky at high doses. Therefore, we believe that the consumer should be made more aware of the side effects of azo dyes in food and that the type and concentration of each substance added to food should be specified.

Chlorella vulgaris algae ameliorates chlorpyrifos toxicity in Nile tilapia with special reference to antioxidant enzymes and Streptococcus agalactiae infection.

BACKGROUND: Chlorpyrifos (CPF) is a widely used pesticide in the production of plant crops. Despite rapid CPF biodegradation, fish were exposed to wastewater containing detectable residues. Recently, medicinal plants and algae were intensively used in aquaculture to replace antibiotics and ameliorate stress impacts. METHODS AND RESULTS: An indoor experiment was conducted to evaluate the deleterious impacts of CPF pollution on Nile tilapia health and the potential mitigation role of Chlorella vulgaris algae. Firstly, the median lethal concentration LC50 - 72 h of CPF was determined to be 85.8 µg /L in Nile tilapia (35.6 ± 0.5 g body weight) at a water temperature of 27.5 °C. Secondly, fish were exposed to 10% of LC50 - 72 h for six weeks, and tissue samples were collected and examined every two weeks. Also, Nile tilapia were experimentally infected with Streptococcus agalactiae. Exposed fish were immunosuppressed expressed with a decrease in gene expressions of interleukin (IL) 1ß, IL-10, and tumor necrosis factor (TNF)-α. Also, a decline was recorded in glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) gene expression in the head kidney tissue. A high mortality rate (MR) of 100% was recorded in fish exposed to CPF for six weeks and challenged with S. agalactiae. Fish that received dietary C. vulgaris could restore gene expression cytokines and antioxidants compared to the control. After six weeks of CPF exposure, fish suffered from anemia as red blood cell count (RBCs), hemoglobin (Hb), and packed cell volume (PCV) significantly declined along with downregulation of serum total protein (TP), globulin (GLO), and albumin (ALB). Liver enzymes were significantly upregulated in fish exposed to CPF pollution, alanine aminotransferase (ALT) (42.5, 53.3, and 61.7 IU/L) and aspartate aminotransferase (AST) (30.1, 31.2, and 22.8) after 2, 4, and 6 weeks, respectively. On S. agalactiae challenge, high MR was recorded in Nile tilapia exposed to CPF (G3) 60%, 60%, and 100% in week 2, week 4, and week 6, and C. vulgaris provided a relative protection level (RPL) of 0, 14.29, and 20%, respectively. CONCLUSIONS: It was concluded that CPF pollution induces immunosuppressed status, oxidative stress, and anemic signs in Nile tilapia. In contrast, C. vulgaris at a 50 g/kg fish feed dose could partially ameliorate such withdrawals, restoring normal physiological parameters.

Protective effects of silymarin in glioblastoma cancer cells through redox system regulation.

BACKGROUND: Glioblastoma multiforme, a deadly form of brain tumor, is characterized by aggressive growth and poor prognosis. Oxidative stress, a disruption in the balance between antioxidants and oxidants, is a crucial factor in its pathogenesis. Silymarin, a flavonoid extracted from milk thistle, has shown therapeutic potential in inhibiting cancer cell growth, promoting apoptosis, and reducing inflammation. It also regulates oxidative stress. This study aims to investigate the regulatory effects of silymarin on oxidative stress parameters, especially the transcription factor Nrf2 and its related enzymes in GBM cancer cells, to develop a new anti-cancer compound with low toxicity. METHODS AND RESULTS: First, the cytotoxicity of silymarin on U-87 MG cells was investigated by MTT and the results showed an IC50 of 264.6 µM. Then, some parameters of the redox system were measured with commercial kits, and the obtained results showed that silymarin increased the activity of catalase and superoxide dismutase enzymes, as well as the total antioxidant capacity levels; while the malondialdehyde level that is an indicator of lipid peroxidation was decreased by this compound. The expression level of Nrf2 and HO-1 and glutaredoxin and thioredoxin enzymes were checked by real-time PCR method, and the expression level increased significantly after treatment. CONCLUSIONS: Our findings suggest that silymarin may exert its cytotoxic and anticancer effects by enhancing the Nrf2/HO-1 pathway through antioxidant mechanisms in U-87 MG cells.