Regulation Of Reactive Oxygen Species Production Research Articles

ERRα regulates synaptic transmission through reactive oxygen species in hippocampal neurons

Reactive oxygen species (ROS) play multiple roles in synaptic transmission, and estrogen-related receptor α (ERRα) is involved in regulating ROS production. The purpose of our study was to explore the underlying effect of ERRα on ROS production, neurite formation and synaptic transmission. Our results revealed that knocking down ERRα expression affected the formation of neuronal neurites and dendritic spines, which are the basic structures of synaptic transmission and play important roles in learning, memory and neuronal plasticity; moreover, the amplitude and frequency of miniature excitatory postsynaptic currents (mEPSCs) and miniature inhibitory postsynaptic currents (mIPSCs) were decreased. These abnormalities were reversed by overexpression of human ERRα. Additionally, we also found that knocking down ERRα expression increased intracellular ROS levels in neurons. ROS inhibitor PBN rescued the changes in neurite formation and synaptic transmission induced by ERRα knockdown. These results indicate a new possible cellular mechanism by which ERRα affects intracellular ROS levels, which in turn regulate neurite and dendritic spine formation and synaptic transmission.

Enhancement of Human Neutrophil Bactericidal Activity through ROS Regulation

Antimicrobial agents are vital for treating infectious diseases, but their widespread use has led to a concerning rise in drug-resistant bacteria. The development and overuse of new antimicrobial agents have paradoxically given rise to even more drug-resistant strains. If current trends persist, drug-resistant infections may become the leading global cause of mortality by 2050. However, current measures such as restricting antimicrobial use and promoting appropriate usage have not provided a definitive solution. Therefore, exploring alternative treatment approaches is essential. In this study, our research was based on a novel strategy that shifts the focus from targeting specific bacterial species to leveraging the defense mechanisms of human neutrophils. Neutrophils play a critical role in innate immunity by engulfing bacteria and generating reactive oxygen species (ROS) in phagosomes. The primary ROS producer in neutrophils is the NADPH oxidase (NOX) complex centered on gp91 phox (NOX2), a membrane protein of the NOX family. However, excessive ROS are harmful, necessitating negative regulation. Neutrophils contain a negative regulator of reactive oxygen species (NRROS), which regulates ROS production by competing with p22 phox for binding to NOX2 when inflammation go into ending. NRROS knockout mice have shown increased ROS production and bactericidal activity during bacterial infection, resulting in significantly prolonged survival compared to wild-type mice. If this mechanism could be applied to human cells to enhance bactericidal activity, it would eliminate the need to target specific bacterial species and could revolutionize the treatment of infectious diseases. We used human induced pluripotent stem cells (iPSC) as a model to validate the NRROS knockout effect in human cells, overcoming challenges in isolating peripheral blood neutrophils due to their limited lifespan, poor in vitro culture tolerance, and genetic editing complexities. We successfully generated NRROS-heterozygous knockout (hetero-KO) and NRROS-homozygous knockout (homo-KO) iPSC clones using genome editing techniques. Additionally, using the PiggyBac system, we established doxycycline-inducible NRROS expression clones (homo-KO+Dox) based on homo-KO clones. These iPSC were differentiated into neutrophils and evaluated for function. The isolated neutrophil fraction exhibited characteristic segmented nuclei in all clones. We measured ROS production and examined changes induced by NRROS knockout after stimulation. Immediate superoxide production showed no difference between wild-type and NRROS-KO clones. However, after 2 hours of stimulation, the NRROS-KO clones exhibited significantly elevated hydrogen peroxide production, indicating increased total ROS production, possibly due to delayed NOX complex degradation. Furthermore, we assessed the bactericidal capacity of iPSC-derived neutrophils against multidrug-resistant bacteria, revealing significantly enhanced bactericidal activity in NRROS-KO clones compared to wild-type clones. In conclusion, NRROS knockout in human neutrophils enhances bactericidal capacity through heightened ROS production, offering promising prospects for innovative infectious disease treatments. If successfully harnessed, this innovative treatment modality could revolutionize infectious disease management, combating drug-resistant infections, and improving global health outcomes.

ROS scavenging enzyme-encoding genes play important roles in the desert moss Syntrichia caninervis response to extreme cold and desiccation stresses

Abiotic stress is one of the major environmental constraints limiting plant growth. Syntrichia caninervis is one of the unique plant models that can cope with harsh environments. Reactive oxygen species (ROS) are a vital signaling molecule for protecting plants from oxidative stress, but research on ROS in S. caninervis is limited. Here, we identified 112 ROS genes in S. caninervis, including 40 GSTs, 51 PODs, 9 SODs, 6 CATs, 3 GPXs and 3 APXs families. GO and KEGG analyses showed that ROS genes are involved in responses to various stimuli and phenylpropanoid biosynthesis. ROS genes contain many stress-responsive and hormonal cis-elements in their promoter regions. More ROS genes were induced by cold stress than desiccation stress, and both conditions changed the transcript abundances of several ROS genes. CAT and POD, H2O2, MDA, and GSH were also induced under biotic stress, specifically CAT activity. The results indicated that the ScCAT genes and their activities could be strongly associated with the regulation of ROS production. This is the first systematic identification of ROS genes in S. caninervis and our findings contribute to further research into the roles of ScROS adjustment under abiotic stress while also providing excellent genetic resources for plant breeding.

XYLEM CYSTEINE PEPTIDASE 1 and its inhibitor CYSTATIN 6 regulate pattern-triggered immunity by modulating the stability of the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D.

Plants produce a burst of reactive oxygen species (ROS) after pathogen infection to successfully activate immune responses. During pattern-triggered immunity (PTI), ROS are primarily generated by the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD). RBOHD is degraded in the resting state to avoid inappropriate ROS production; however, the enzyme mediating RBOHD degradation and how to prevent RBOHD degradation after pathogen infection is unclear. In this study, we identified an Arabidopsis (Arabidopsis thaliana) vacuole-localized papain-like cysteine protease, XYLEM CYSTEINE PEPTIDASE 1 (XCP1), and its inhibitor CYSTATIN 6 (CYS6). Pathogen-associated molecular pattern-induced ROS burst and resistance were enhanced in the xcp1 mutant but were compromised in the cys6 mutant, indicating that XCP1 and CYS6 oppositely regulate PTI responses. Genetic and biochemical analyses revealed that CYS6 interacts with XCP1 and depends on XCP1 to enhance PTI. Further experiments showed that XCP1 interacts with RBOHD and accelerates RBOHD degradation in a vacuole-mediated manner. CYS6 inhibited the protease activity of XCP1 toward RBOHD, which is critical for RBOHD accumulation upon pathogen infection. As CYS6, XCP1, and RBOHD are conserved in all plant species tested, our findings suggest the existence of a conserved strategy to precisely regulate ROS production under different conditions by modulating the stability of RBOHD.

The metabolic function of pyruvate kinase M2 regulates reactive oxygen species production and microbial killing by neutrophils

Neutrophils rely predominantly on glycolytic metabolism for their biological functions, including reactive oxygen species (ROS) production. Although pyruvate kinase M2 (PKM2) is a glycolytic enzyme known to be involved in metabolic reprogramming and gene transcription in many immune cell types, its role in neutrophils remains poorly understood. Here, we report that PKM2 regulates ROS production and microbial killing by neutrophils. Zymosan-activated neutrophils showed increased cytoplasmic expression of PKM2. Pharmacological inhibition or genetic deficiency of PKM2 in neutrophils reduced ROS production and Staphylococcus aureus killing in vitro. In addition, this also resulted in phosphoenolpyruvate (PEP) accumulation and decreased dihydroxyacetone phosphate (DHAP) production, which is required for de novo synthesis of diacylglycerol (DAG) from glycolysis. In vivo, PKM2 deficiency in myeloid cells impaired the control of infection with Staphylococcus aureus. Our results fill the gap in the current knowledge of the importance of lower glycolysis for ROS production in neutrophils, highlighting the role of PKM2 in regulating the DHAP and DAG synthesis to promote ROS production in neutrophils.

RUNX1/ETO regulates reactive oxygen species (ROS) levels in t(8,21) acute myeloid leukaemia via FLT3 and RAC1.

Reactive oxygen species (ROS) homeostasis is crucial for leukaemogenesisand deregulation would hamper leukaemic progression. Although the regulatory effects of RUNX1/ETO has been extensively studied, its underlying molecular mechanims in ROS production in t(8,21) AML is yet to be fully elucidated. Here, we report that RUNX1/ETO could directly control FLT3 by occupying several DNA elements on FLT3 locus. The possible hijacking mechanism by RUNX1/ETO over FLT3 mediated ROS modulation in AML t(8;21) was made apparent when suppression of RUNX1/ETO led to decrement in ROS levels and the direct oxidative marker FOXO3 but not in FLT3 and RAC1 suppressed t(8,21) AML cell line Furthermore, nuclear import of RUNX1/ETO was aberrated following RUNX1/ETO and RAC1 suppression suggesting association in ROS control. A different picture was depicted in non t(8;21) cells where suppression of RAC1 and FLT3 led to decreased levels of FOXO3a and ROS. Results alltogether indicate a possible dysregulation of ROS levels by RUNX1/ETO in t(8,21) AML.

Exogenous glucose reduces the incidence of black rot disease in apricot (Prunus armeniaca L.) by regulating energy metabolism and ROS

Apricot is one of the most highly consumed fruit in Xingjiang, China, but it is extremely perishable. In this study, the effects of exogenous glucose (Glu) on postharvest energy metabolism and reactive oxygen species (ROS) metabolism in the apricot fruit and its relationship to black rot disease were investigated. The results demonstrated that the disease incidence of apricot fruit inoculation and the expansion of the diameter of the disease spots were inhibited after exogenous Glu-treatment. Contrarily to the control group, exogenous Glu-treated fruits exhibited higher activities of enzymes involved in energy metabolism and ROS-scavenge system and effectively maintain the adenosine triphosphate (ATP), adenosine diphosphate (ADP), and energy charge in the apricot fruit. Simultaneously, the accumulation of adenosine monophosphate (AMP), superoxide radical (O2−) production, hydrogen peroxide (H2O2), malondialdehyde (MDA) and the electrolyte leakage was inhibited after treatment. Overall, the results suggested that exogenous Glu-treatment can effectively enhance the resistance of apricot fruit to black rot disease by regulating ROS production and energy metabolism.

Oxidative Stress and Inflammation in Osteoporosis: Molecular Mechanisms Involved and the Relationship with microRNAs.

Osteoporosis is characterized by the alteration of bone homeostasis due to an imbalance between osteoclastic bone resorption and osteoblastic bone formation. Estrogen deficiency causes bone loss and postmenopausal osteoporosis, the pathogenesis of which also involves oxidative stress, inflammatory processes, and the dysregulation of the expression of microRNAs (miRNAs) that control gene expression at post-transcriptional levels. Oxidative stress, due to an increase in reactive oxygen species (ROS), proinflammatory mediators and altered levels of miRNAs enhance osteoclastogenesis and reduce osteoblastogenesis through mechanisms involving the activation of MAPK and transcription factors. The present review summarizes the principal molecular mechanisms involved in the role of ROS and proinflammatory cytokines on osteoporosis. Moreover, it highlights the interplay among altered miRNA levels, oxidative stress, and an inflammatory state. In fact, ROS, by activating the transcriptional factors, can affect miRNA expression, and miRNAs can regulate ROS production and inflammatory processes. Therefore, the present review should help in identifying targets for the development of new therapeutic approaches to osteoporotic treatment and improve the quality of life of patients.

Ca2+-dependent oxidation of exogenous NADH and NADPH by the mitochondria of spring wheat and its relation with AOX capacity and ROS content at high temperatures

Mitochondria are sources of reactive oxygen species (ROS) in a plant cell under high temperature. Mitochondrial alternative NAD(P)H dehydrogenases (type II NAD(P)H DHs) and cyanide-resistant oxidase (AOX) can regulate ROS production, but their role at high temperatures is unknown. This study investigates the influence heat acclimation (37 °C) and heat shock (50 °C) temperatures on ROS content, activity and protein abundance of external Ca2+-dependent NAD(P)H DHs (NDB) and AOX in mitochondria of 4- and 8-day-old seedlings of spring wheat (Triticum aestivum L., var. Novosibirskya 29). The shoots of 4-day-old seedlings contained more carbohydrates, had a higher rate of total respiration and a high rate of oxidation of exogenous NADH, a greater AOX capacity and a lower of ROS content, as compared to leaves of 8-day-old seedlings, and were more resistant to heat shock. The activity of external NADH DH was higher than the one of NADPH DH in mitochondria of both shoots and leaves. At 37 °C, high NADH oxidation was associated with increased AOX capacity in mitochondria of both shoots and leaves, whereas NADPH oxidation with COX capacity. At 50 °C, the NADPH oxidation by shoots’ mitochondria increased and the NADH oxidation stayed high. The content of NDB and AOX proteins depends on heat treatments and differs between mitochondria of shoots and leaves. Our data indicate that Ca2+-dependent type II NAD(P)H DHs can regulate the ROS content and together with AOX are involved in heat tolerance, depending on the development phase of spring wheat and is, probably, tissue-specific.

TrPLD1 and TrPLD2 modulate reactive oxygen species production and pathogenicity in Trichothecium roseum infected apple fruit

Phospholipase D (PLD) plays an important role during pathogen-host interaction, which not only hydrolyzes the phosphodiester bond in the phospholipid structure of the host cell membrane, resulting in the cell membrane structure destruction of the host, but also produces phosphatidic acid that can interact with NADPH oxidase (NOX) on the cell plasma membrane, resulting in reactive oxygen species (ROS) accumulation and improving the pathogenicity of the pathogen. However, the ROS production of filamentous fungi by PLD modulation and its pathogenicity on postharvest fruit and vegetables have not been documented. In this study, we constructed ΔTrPLD1 and ΔTrPLD2 mutants and complement strains of Trichothecium roseum by homologous recombination, and analyzed ROS production and its pathogenicity on apple fruit. The results showed that the deletion of TrPLD1 and TrPLD2 increased the sensitivity to oxidative stress and reduced ROS production of T. roseum mycelia. During ΔTrPLD1 mutant of T. roseum infecting apple fruit, the gene expression and activity of NOX decreased, which lead to the reduction of superoxide anion production rate. The gene expressions and activities of superoxide dismutase and peroxidase were up-regulated, the expression and activity of catalase were down-regulated, and the activation of ascorbic acid-glutathione cycle, ultimately enhanced the production of H2O2 in apple tissue, H2O2 acted as signal molecule to trigger disease resistance of fruit, thereby reducing the pathogenicity on apple fruit. The ΔTrPLD2 mutant had no significant effect on ROS production during pathogen infecting apple fruit. In summary, ΔTrPLD1 and ΔTrPLD2 mutants were highly sensitive to oxidative stress, and TrPLD1 played more important role in T. roseum infected apple fruit by regulating ROS production.

Cardioprotective role of inner membrane chloride channel, CLIC5 from ischemia-reperfusion injury.

Mitochondrial chloride channels by regulating mitochondrial volume, pH and membrane potential are important in determining the cell fate. However, very few of them are identified in mitochondria. Previously, we demonstrated the localization of a member of chloride intracellular channel (CLIC) family, CLIC5 in the inner mitochondrial membrane and its importance in regulating reactive oxygen species (ROS) generation. Herein, we show the novel role of an alternative N-terminal splice variant clic5b in cardiac mitochondrial physiology. Mass spectrometry and qPCR analysis indicated the presence of the splice variant, clic5b in cardiac tissue in addition to the prominent transcript variant, clic5a. Interestingly, the presence of splice variant clic5b was correlated with its mitochondrial localization in myoblast cells, H9C2 (55.12 ± 7.1%) but not in mouse lung epithelial cells (11 ± 2.1%). Further, using transfection studies we showed that the N terminal region of clic5b is integral for its mitochondrial targeting in neonatal cardiomyocytes and in HEK cells as transfection of clic5a does not exhibit mitochondrial localization. We also demonstrate increased mitochondrial ROS generation in clic5-/- mouse heart (N=4, p≤0.05) in comparison to wild type (wt) mice. On the other hand, lungs, that only contain splice variant clic5a, neither demonstrate mitochondrial localization of CLIC5 nor any change in ROS production. The absence of CLIC5 exacerbated myocardial infarction (52 ± 9.5% versus 38.6 ± 4.5%, n≥3, p≤ 0.05) and reduced left ventricular function upon ischemia-reperfusion (IR) injury in clic5-/- mice in comparison to wt mice suggesting a cardioprotective role of CLIC5. Furthermore, in human heart failure samples, we observed a differential expression of the splice variants clic5a and clic5b in comparison to healthy hearts. Thus, our study highlights the role of splice variant clic5b in regulating cardiac mitochondrial physiology and cardioprotection from IR injury.

Phytochrome B regulates reactive oxygen signaling during abiotic and biotic stress in plants.

Reactive oxygen species (ROS) and the photoreceptor protein phytochrome B (phyB) play a key role in plant acclimation to stress. However, how phyB that primarily functions in the nuclei impacts ROS signaling mediated by respiratory burst oxidase homolog (RBOH) proteins that reside on the plasma membrane, during stress, is unknown. Arabidopsis thaliana and Oryza sativa mutants, RNA-Seq, bioinformatics, biochemistry, molecular biology, and whole-plant ROS imaging were used to address this question. Here, we reveal that phyB and RBOHs function as part of a key regulatory module that controls apoplastic ROS production, stress-response transcript expression, and plant acclimation in response to excess light stress. We further show that phyB can regulate ROS production during stress even if it is restricted to the cytosol and that phyB, respiratory burst oxidase protein D (RBOHD), and respiratory burst oxidase protein F (RBOHF) coregulate thousands of transcripts in response to light stress. Surprisingly, we found that phyB is also required for ROS accumulation in response to heat, wounding, cold, and bacterial infection. Our findings reveal that phyB plays a canonical role in plant responses to biotic and abiotic stresses, regulating apoplastic ROS production, possibly while at the cytosol, and that phyB and RBOHD/RBOHF function in the same regulatory pathway.

Mitochondrial protein, TBRG4, modulates KSHV and EBV reactivation from latency.

Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr (EBV) are gammaherpesviruses associated with multiple human malignancies. KSHV is the etiological agent of Kaposi's Sarcoma, primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). EBV is associated with Burkitt's lymphoma (BL), Hodgkin's lymphoma (HL), nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC). KSHV and EBV establish life-long latency in the human host with intermittent periods of lytic reactivation. Here, we identified a cellular factor named transforming growth factor-beta regulator 4 (TBRG4) that plays a role in the gammaherpesvirus lifecycle. We find that TBRG4, a protein that is localized to the mitochondria, can regulate lytic reactivation from latency of both KSHV and EBV. Knockdown of TBRG4 in cells latently infected with KSHV or EBV induced viral lytic gene transcription and replication. TBRG4 deficiency causes mitochondrial stress and increases reactive oxygen species (ROS) production. Treatment with a ROS scavenger decreased viral reactivation from latency in TBRG4-depleted cells. These data suggest that TBRG4 serves as a cellular repressor of KSHV and EBV reactivation through the regulation of ROS production.

TMET-15. CYTOCHROME C OXIDASE MEDIATES CELLULAR IRON HOMEOSTASIS AND RADIORESISTANCE IN GLIOBLASTOMA

Abstract Defining the molecular mechanism(s) responsible for the adaptive radioresistance in glioblastoma (GBM) is necessary for the development of effective treatment options. The cellular labile iron pool (LIP) is very important for determining the cellular response to radiation, as it contributes to radiation-induced production of reactive oxygen species (ROS). Recently, cytochrome c oxidase (CcO), a mitochondrial heme-containing enzyme also involved in regulating ROS production, was found to be involved in GBM chemoresistance. However, the role of LIP and CcO in GBM radioresistance is not known. Herein, we tested the hypothesis that CcO-mediated alterations in the level of labile iron contribute to adaptive radioresistance. Using an in vitro model of GBM adaptive radioresistance, we found an increase in CcO activity in radioresistant cells that associated with a decrease in the cellular LIP (4.1-fold), decrease in lipid peroxidation (2-fold), and a switch in the CcO subunit 4 (COX4) isoform expression, from COX4-2 to COX4-1. Furthermore, knockdown of COX4-1 in radioresistant GBM cells decreased CcO activity and restored radiosensitivity, whereas overexpression of COX4-1 in radiosensitive cells increased CcO activity and rendered the cells radioresistant. We further observed that radioresistant cells has increased expression of mitoferrin-1, a protein that facilitates the incorporation of iron into mitochondria. Overexpression of mitoferrin-1 in glioma cells increases the activity of mitochondrial protein complexes, decreases the cellular labile iron pool (p< 0.05), and decreases the production of 4-hydroxy nonenal (4-HNE), a lipid peroxidation product. Furthermore, overexpression of mitoferrin-1 significantly increases the anchorage independent colony formation in soft agar assay (p< 0.01). Moreover, mitoferrin-1 overexpressing cells implanted orthotopically in the brain of nude mice significantly decreased survival compared to wild type (p < 0.01). These results indicate that manipulation of cellular and mitochondrial iron homeostasis may provide a strategy to improve therapeutic outcome in patients with GBM.

Ginsenoside induces apoptosis, autophagy and cell cycle arrest in gastric cancer cells by regulation of reactive oxygen species and activation of MAPK pathway

Purpose: To study the influence of ginsenoside on apoptosis, cell cycle and autophagy in gastric carcinoma (GC), and its effect on reactive oxygen species (ROS) levels and the mitogen-activated protein kinase (MAPK) pathway. 
 Methods: Human gastric cancer cell line BGC-823 was randomly divided into the following groups: control, 100 μM ginsenoside (Rg5), 150 μM Rg5, and 200 μM Rg5 groups. Western blot assay was used to determine the expressions of autophagy-associated protein 12 (Atg12), Beclin-1, lc3b II, cycle-related protein, phosphated mitotic cyclin 25 homologous protein C (p-cdc25c), cyclin B1, and MAPK signaling pathway-related proteins. 
 Results: There was significantly higher apoptosis in Rg5-treated BGC-823 cells than in untreated cells. Relative protein levels of Beclin-1, Atg5, Atg12, and lc3b II in BGC-823 cells in Rg5 groups were significantly and concentration-dependently up-regulated, relative to the corresponding expression levels in untreated cells. There were markedly up-regulated proteins of p-cdc25c, cyclin B1 and p-cdc2 in Rg5-exposed BGC-823 cells than in untreated cells, while CDC2 protein expression was significantly and concentration-dependently lower than that of control group (p < 0.05). Rg5 treatment resulted in marked and concentration-dependent increases in ROS levels in BGC-823 cells, relative to control cells (p < 0.05), whereas the expression levels of p-p38, p-JNK and p-ERK were significantly higher in Rg5-exposed cells than in unexposed cells (p < 0.05). 
 Conclusion: Ginsenoside induces apoptosis, autophagy and cycle interruption in GC cells by regulating ROS production and activating MAPK pathway. Therefore, ginsenoside may be a promising agent for the management of gastric cancer. However, there is a need to conduct in vivo studies on the compound.

A vicious circle in breast cancer: The interplay between inflammation, reactive oxygen species, and microRNAs.

Breast cancer (BC) is the most common cancer in women worldwide. This highly heterogeneous disease is molecularly stratified into luminal A, luminal B, HER2, triple-negative/basal-like, and normal-like subtypes. An important aspect in BC progression is the activation of inflammatory processes. The activation of CD8+/Th1, NK, and M1 tumor associated macrophages (TAMs), leads to tumor destruction. In contrast, an anti-inflammatory response mediated by CD4+/Th2 and M2 TAMs will favor tumor progression. Inflammation also stimulates the production of inflammatory mediators like reactive oxygen species (ROS). In chronic inflammation, ROS activates oxidative stress and endothelial dysfunction. In cancer, ROS plays a dual role with anti-tumorigenic and pro-tumorigenic effects in cell signaling pathways that control proliferation, survival, apoptosis, and inflammation. MicroRNAs (miRNAs), which are known to be involved in BC progression and inflammation, can be regulated by ROS. At the same time, miRNAs regulate the expression of genes modulating oxidative stress. In this review, we will discuss the interplay between inflammation, ROS, and miRNAs as anticancer and tumor promoter molecules in BC. A clear understanding of the role of miRNAs in the regulation of ROS production and inflammation, may lead to new opportunities for therapy in BC.

Role of Carbon Monoxide in Oxidative Stress-Induced Senescence in Human Bronchial Epithelium.

Prolonged or excessive stimulation from inhaled toxins may cause oxidative stress and DNA damage that can lead to stress-induced senescence in epithelial cells, which can contribute to several airway diseases. Mounting evidence has shown carbon monoxide (CO) confers cytoprotective effects. We investigated the effects of CO on oxidative stress-induced senescence in human airway epithelium and elucidated the underlying molecular mechanisms. Here, CO pretreatment reduced H2O2-mediated increases in total reactive oxygen species (ROS) production and mitochondrial superoxide in a human bronchial epithelial cell line (BEAS-2B). H2O2 treatment triggered a premature senescence-like phenotype with enlarged and flattened cell morphology accompanied by increased SA-β-gal activity, cell cycle arrest in G0/G1, reduced cell viability, and increased transcription of senescence-associated secretory phenotype (SASP) genes. Additionally, exposure to H2O2 increased protein levels of cellular senescence markers (p53 and p21), reduced Sirtuin 3 (SIRT3) and manganese superoxide dismutase (MnSOD) levels, and increased p53 K382 acetylation. These H2O2-mediated effects were attenuated by pretreatment with a CO-containing solution. SIRT3 silencing induced mitochondrial superoxide production and triggered a senescence-like phenotype, whereas overexpression decreased mitochondrial superoxide production and alleviated the senescence-like phenotype. Air-liquid interface (ALI) culture of primary human bronchial cells, which becomes a fully differentiated pseudostratified mucociliary epithelium, was used as a model. We found that apical and basolateral exposure to H2O2 induced a vacuolated structure that impaired the integrity of ALI cultures, increased goblet cell numbers, decreased SCGB1A1+ club cell numbers, increased p21 protein levels, and increased SASP gene transcription, consistent with our observations in BEAS-2B cells. These effects were attenuated in the apical presence of a CO-containing solution. In summary, we revealed that CO has a pivotal role in epithelial senescence by regulating ROS production via the SIRT3/MnSOD/p53/p21 pathway. This may have important implications in the prevention and treatment of age-associated respiratory pathologies.

Heme oxygenase-1 modulates ferroptosis by fine-tuning levels of intracellular iron and reactive oxygen species of macrophages in response to Bacillus Calmette-Guerin infection.

Macrophages are the host cells and the frontline defense against Mycobacterium tuberculosis (Mtb) infection, and the form of death of infected macrophages plays a pivotal role in the outcome of Mtb infections. Ferroptosis, a programmed necrotic cell death induced by overwhelming lipid peroxidation, was confirmed as one of the mechanisms of Mtb spread following infection and the pathogenesis of tuberculosis (TB). However, the mechanism underlying the macrophage ferroptosis induced by Mtb infection has not yet been fully understood. In the present study, transcriptome analysis revealed the upregulation of heme oxygenase-1 (HMOX1) and pro-ferroptosis cytokines, but downregulation of glutathione peroxidase 4 (GPX4) and other key anti-lipid peroxidation factors in the peripheral blood of both patients with extra-pulmonary tuberculosis (EPTB) and pulmonary tuberculosis (PTB). This finding was further corroborated in mice and RAW264.7 murine macrophage-like cells infected with Bacillus Calmette-Guerin (BCG). A mechanistic study further demonstrated that heme oxygenase-1 protein (HO-1) regulated the production of reactive oxygen species (ROS) and iron metabolism, and ferroptosis in BCG-infected murine macrophages. The knockdown of Hmox1 by siRNA resulted in a significant increase of intracellular ROS, Fe2+, and iron autophagy-mediated factor Ncoa4, along with the reduction of antioxidant factors Gpx4 and Fsp1 in macrophages infected with BCG. The siRNA-mediated knockdown of Hmox1 also reduced cell survival rate and increased the release of intracellular bacteria in BCG-infected macrophages. By contrast, scavenging ROS by N-acetyl cysteine led to the reduction of intracellular ROS, Fe2+, and Hmox1 concentrations, and subsequently inhibited ferroptosis and the release of intracellular BCG in RAW264.7 cells infected with BCG. These findings suggest that HO-1 is an essential regulator of Mtb-induced ferroptosis, which regulates ROS production and iron accretion to alter macrophage death against Mtb infections.

SIRT7 Deficiency Protects against Aβ42-Induced Apoptosis through the Regulation of NOX4-Derived Reactive Oxygen Species Production in SH-SY5Y Cells.

Alzheimer’s disease (AD) is an age-related neurodegenerative disease that is characterized by irreversible memory loss and cognitive decline. The deposition of amyloid-β (Aβ), especially aggregation-prone Aβ42, is considered to be an early event preceding neurodegeneration in AD. Sirtuins (SIRT1–7 in mammals) are nicotinamide adenine dinucleotide-dependent lysine deacetylases/deacylases, and several sirtuins play important roles in AD. However, the involvement of SIRT7 in AD pathogenesis is not known. Here, we demonstrate that SIRT7 mRNA expression is increased in the cortex, entorhinal cortex, and prefrontal cortex of AD patients. We also found that Aβ42 treatment rapidly increased NADPH oxidase 4 (NOX4) expression at the post-transcriptional level, and induced reactive oxygen species (ROS) production and apoptosis in neuronal SH-SY5Y cells. In contrast, SIRT7 knockdown inhibited Aβ42-induced ROS production and apoptosis by suppressing the upregulation of NOX4. Collectively, these findings suggest that the inhibition of SIRT7 may play a beneficial role in AD pathogenesis through the regulation of ROS production.

Boron mediates nitrogen starvation-induced leaf senescence by regulating ROS production and C/N balance in Brassica napus

Rapeseed ( Brassica napus ) is highly sensitive to nitrogen (N) and boron (B) deficiencies. However, little is known about the effect of N and B interaction on rapeseed growth and the underlying mechanism of B regulating N starvation-induced leaf senescence in Brassica napus . In this study, B deficiency accelerated the senescence of old leaves induced by N starvation stress in B. napus , while young leaves were more susceptible to B deficiency under N-sufficient condition. B deficiency enhanced SGR1 -mediated chlorophyll degradation, exhibiting the chlorosis phenotype of old leaves. The excessive production of reactive oxygen species (ROS) in old leaves was regulated by the photooxidation damage and the up-regulation of RBOHDs under B deficiency. The senescence-associated genes SAG12s were strongly enhanced by B deficiency in response to the ROS over-accumulation. However, B-sufficient supply improved the antioxidant capacity to alleviate ROS toxicity under N starvation. Metabolic analysis showed that B deficiency improved N remobilization from source to sink and increased sugar accumulation in the old leaves, resulting in a significant increase in the C/N ratio. In addition, B deficiency further disrupted the balance of C and N pools through GABA (γ-aminobutyri acid) shunts, which negatively regulated the leaf senescence process. Our results provide a comprehensive model for balancing B and N application in rapeseed production to optimize plant growth. • B deficiency accelerates the N-starvation-induced senescence process in old leaves of Brassica napus . • B deficiency induces over-accumulation of ROS in rapeseed leaves through multiple pathways, stimulating leaf senescence. • B-sufficient supply improves plant resistance to oxidative stress under N starvation. • B deficiency enhances the remobilization of N from source to sink, resulting in an increase in the C/N ratio.