Regulation Of Reactive Oxygen Species Production Research Articles

Renalase attenuates mitochondrial fission in cisplatin-induced acute kidney injury via modulating sirtuin-3

AimsAcute kidney injury (AKI) can limit the clinical use of cisplatin in cancer treatment. The drivers of cisplatin-induced AKI include oxidative stress, mitochondrial dysfunction and apoptosis. Previous studies showed renalase protected cultured human renal proximal tubular cell (HK-2) against cisplatin induced necrosis, and renalase-knockout mice subjected to cisplatin showed exacerbated kidney injury. Therefore, it is necessary to determine the exact mechanisms of renalase in cisplatin-induced nephrotoxicity. Main methodsTo study the protective effect of renalase on cell viability, renal function, apoptosis, reactive oxygen species (ROS) production and mitochondrial dynamics, cultured HK-2 cells and male mice were subjected to cisplatin. Signaling proteins related to apoptosis, survival, and mitochondrial fission were analyzed by Western blot. Key findingsIn this study, we showed that the protective effect of recombinant renalase in cisplatin-induced AKI was associated with the regulation of ROS production, mitochondrial dynamics and sirtuin-3 (Sirt3) levels in vivo and in vitro. After cisplatin treatment, recombinant renalase restored Sirt3 expression, reduced mitochondrial fission and ROS generation. In HK-2 cells, downregulation of endogenous Sirt3 expression by siRNA transfection abrogated the renalase cytoprotection. SignificanceOur study suggests that renalase protects against cisplatin-induced AKI by improving mitochondrial function and inhibiting oxidative stress, and in vitro, it functions in a Sirt3-dependent manner.

Genetic polymorphisms associated with reactive oxygen species and blood pressure regulation.

Hypertension is the most prevalent cause of cardiovascular disease and kidney failure but only about 50% of patients achieve adequate blood pressure control, in part, due to inter-individual genetic variations in the response to antihypertensive medication. Significant strides have been made toward the understanding of the role of reactive oxygen species (ROS) in the regulation of the cardiovascular system. However, the role of ROS in human hypertension is still unclear. Polymorphisms of some genes involved in the regulation of ROS production are associated with hypertension, suggesting their potential influence on blood pressure control and response to antihypertensive medication. This review provides an update on the genes associated with the regulation of ROS production in hypertension and discusses the controversies on the use of antioxidants in the treatment of hypertension, including the antioxidant effects of antihypertensive drugs.

Fucoidan Exerts Anticancer Effects Against Head and Neck Squamous Cell Carcinoma In Vitro.

Fucoidans have been reported to exert anticancer effects with simultaneous low toxicity against healthy tissue. That correlation was observed in several cancer models, however, it has never been investigated in head and neck cancer before. To magnify the efficacy of conventional therapy, the administration of agents like fucoidan could be beneficial. The aim of this study was to evaluate the anticancer effect of Fucus vesiculosus (FV) extract alone and with co-administration of cisplatin in head and neck squamous cell carcinoma (HNSCC) in vitro. MTT assay results revealed an FV-induced inhibition of proliferation in all tested cell lines (H103, FaDu, KB). Flow cytometric cell cycle analysis showed an FV-induced, dose-dependent arrest in either S/G2 phase (H103, FaDu) or G1 arrest (KB). Furthermore, a dose-dependent gain in apoptotic fraction was observed. Western blot analysis confirmed the induction of apoptosis. A significant dose-dependent increase in reactive oxygen species (ROS) production was revealed in the H103 cell line, while FaDu cells remained unresponsive. On the contrary, an HPV-positive cell line, KB, demonstrated a dose-dependent decrease in ROS synthesis. Moreover, fucoidan enhanced the response to cisplatin (synergistic effect) in all cell lines with the HPV-positive one (KB) being the most sensitive. These results have been confirmed by flow-cytometric apoptosis analysis. In conclusion, we confirmed that fucoidan exhibits anticancer properties against HNSCC, which are manifested by the induction of apoptosis, regulation of ROS production, cell cycle arrest, and inhibition of proliferation.

PRL2 Controls Phagocyte Bactericidal Activity by Sensing and Regulating ROS.

Although it is well-recognized that inflammation enhances leukocyte bactericidal activity, the underlying mechanisms are not clear. Here we report that PRL2 is sensitive to oxidative stress at inflamed sites. Reduced PRL2 in phagocytes causes increased respiratory burst activity and enhances phagocyte bactericidal activity. PRL2 (Phosphatase Regenerating Liver 2) is highly expressed in resting immune cells, but is markedly downregulated by inflammation. in vitro experiments showed that PRL2 was sensitive to hydrogen peroxide (H2O2), a common damage signal at inflamed sites. In response to infection, PRL2 knockout (KO) phagocytes were hyper activated, produced more reactive oxygen species (ROS) and exhibited enhanced bactericidal activity. Mice with PRL2 deficiency in the myeloid cell compartment were resistant to lethal listeria infection and cleared the bacteria more rapidly and effectively. Moreover, in vitro experiments demonstrated that PRL2 binds to GTPase Rac and regulates ROS production. Rac GTPases were more active in PRL2 (KO) phagocytes than in wild type cells after bacterium infection. Our findings indicate that PRL2 senses ROS at inflamed sites and regulates ROS production in phagocytes. This positive feedback mechanism promotes bactericidal activity of phagocytes and may play an important role in innate anti-bacterial immunity.

Aspergillus fumigatus phospholipase D may enhance reactive oxygen species production by accumulation of histone deacetylase 6

Aspergillus fumigatus, an airborne pathogen, causes many diseases, including aspergilloma, invasive aspergillosis, and allergic bronchopulmonary aspergillosis. Phospholipase D (PLD) is an important virulence factor for A. fumigatus infection, but the manner by which PLD contributes to the virulence of this pathogen is not clear. Our results show that expression of A. fumigatus PLD in human cells was able to increase the production of reactive oxygen species (ROS), which play an important role in several signaling pathways as well as in lung infection. Meanwhile, A. fumigatus PLD was found to interact with human endogenous histone deacetylase 6 (HDAC6), a known regulator of ROS production and inflammatory responses; PLD significantly increased the expression level of HDAC6 protein without altering its mRNA level. These results suggest that A. fumigatus PLD may enhance the production of ROS via the accumulation of HDAC6, which may be involved in host immunomodulation during A. fumigatus infection.

A Cross Talk Between BRG1 and Males Absent on the First Contributes to Reactive Oxygen Species Production in a Mouse Model of Nonalcoholic Steatohepatitis.

Aims: Accumulation of reactive oxygen species (ROS) in hepatocytes in response to excessive nutrients and the ensuing liver damages caused by ROS constitute a key pathophysiological event in nonalcoholic steatohepatitis (NASH). In the present study, we investigated the epigenetic mechanism underlying ROS production in NASH pathogenesis. Results: NASH was induced by feeding the mice with a methionine-and-choline-deficient (MCD) diet for 4 weeks. Compared with the control mice (wild type [WT]), mice with hepatocyte-specific deletion of Brg1 (HepcKO), a core component of the mammalian chromatin remodeling complex, developed a less severe form of NASH when fed on the MCD diet. Importantly, ROS levels were attenuated in HepcKO mice as opposed to WT mice. Brahma-related gene 1 (Brg1) deficiency downregulated the transcription of NADPH oxidases (NOX1, NOX2, and NOX4) both in vivo and in vitro. Mechanistically, Brg1 deletion rendered a more repressive chromatin structure surrounding the NOX promoters as characterized by reduced levels of acetylated histones. In addition, Brg1 interacted with the histone H4K16 acetyltransferase males absent on the first (MOF) to activate NOX transcription. MOF knockdown by small interfering RNA or pharmaceutical inhibition by MG149 suppressed NOX transcription and ameliorated ROS levels. Innovation: Our data highlight a novel epigenetic mechanism through which Brg1 and MOF cooperate to regulate ROS production in hepatocytes in response to pro-NASH stimuli. Conclusion: A cross talk between Brg1 and MOF epigenetically activates NOX transcription and elevates ROS synthesis contributing to NASH pathogenesis.

Omega-3 polyunsaturated fatty acids alleviate adenine-induced chronic renal failure via regulating ROS production and TGF-β/SMAD pathway.

To explore the role of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in adenine-induced rat chronic renal failure and its underlying mechanism. 30 Sprague Dawley (SD) rats were randomly assigned into three groups, namely sham group, adenine induction group (adenine group) and adenine induction + ω-3 PUFAs treatment group (ω-3 PUFAs group), with 10 rats in each group. Serum and kidney samples were collected after rats were sacrificed. Serum levels of Cr (creatinine) and BUN (urea nitrogen) were detected using commercial kits. HE (hematoxylin and eosin) staining was performed to evaluate the pathological changes of kidneys. Levels of oxidative stress indicators in rat kidney homogenate were detected by relative commercial kits, including SOD (superoxide dismutase), GSH (reduced glutathione), CAT (catalase), and T-AOC (total antioxidant capacity). Reactive oxygen species (ROS) production was also detected by immunofluorescence. Protein expressions of nuclear factor E2 related factor 2 (Nrf2) and transforming growth factor-beta (TGF-β)/SMAD pathway-related genes were detected by Western blot. Serum levels of Cr and BUN in ω-3 PUFAs group were remarkably decreased compared with those of adenine group. Higher contents of SOD, GSH, CAT and T-AOC were observed in ω-3 PUFAs group compared with those of adenine group. Besides, MAD content and ROS production were lower in ω-3 PUFAs group than those of adenine group. Pathological changes of kidneys were alleviated after ω-3 PUFAs treatment. Western blot results demonstrated that ω-3 PUFAs treatment remarkably upregulates Nrf2, HO-1, NQO1, but downregulates relative genes in TGF-β/SMAD pathway. ω-3 PUFAs alleviated adenine-induced chronic renal failure through enhancing antioxidant stress and inhibiting inflammatory response via regulating Nrf2 and TGF-β/SMAD pathway.

Hydrogen Sulfide Protects Human Cardiac Fibroblasts Against H2O2-induced Injury Through Regulating Autophagy-Related Proteins

Autophagy, an intracellular bulk degradation process of proteins and organelles, can be induced by myocardial ischemia in the heart. However, the causative role of autophagy in the survival of human cardiac fibroblasts and the underlying mechanisms are incompletely understood. Oxidative stress can induce autophagy in cultured cells upon hydrogen peroxide (H2O2) exposure. Because hydrogen sulfide (H2S) regulates reactive oxygen species (ROS) and apoptosis, we hypothesize that H2S may have a cardioprotective function. To examine our hypothesis, we investigated the regulation of autophagy by the H2S donor sodium hydrosulfide (NaHS), using a cell model of human cardiac fibroblasts from adult ventricles (HCF-av) that suffered from endoplasmic reticulum (ER) stress by H2O2. In the present study, we found that the apoptosis and autophagy were induced along with ER stress by H2O2 in the primary cultured HCF-av cells. In contrast, H2S suppressed HCF-av cell apoptosis and autophagic flux, in part directly by inhibiting ROS production and preserving mitochondrial functions.

Calmodulin 1 Regulates Senescence and ABA Response in Arabidopsis.

Cellular calcium acts as a second messenger and regulates diverse developmental events and stress responses. Cytosolic calcium has long been considered as an important regulator of senescence, however, the role of Ca2+ in plant senescence has remained elusive. Here we show that the Calmodulin 1 (CaM1) gene, which encodes Ca2+-binding protein calmodulin 1, positively regulates leaf senescence in Arabidopsis. Yellowing of leaves, accumulation of reactive oxygen species (ROS), and expression of the senescence-associated gene 12 (SAG12) were significantly enhanced in CaM1 overexpression plants. In contrast, abscisic acid (ABA)-triggered ROS production and stomatal closure were reduced in amiRNA-CaM1 plants. We found a positive-feedback regulation loop among three signaling components, CaM1, RPK1, and RbohF, which physically associate with each other. RPK1 positively regulates the expression of the CaM1 gene, and the CaM1 protein, in turn, up-regulates RbohF gene expression. Interestingly, the expression of CaM1 was down-regulated in rbohD, rbohF, and rbohD/F mutants. We show that CaM1 positively regulates ROS production, leaf senescence, and ABA response in Arabidopsis.

Maresin 1 attenuates mitochondrial dysfunction through the ALX/cAMP/ROS pathway in the cecal ligation and puncture mouse model and sepsis patients

Inflammation always accompanies infection during sepsis. Mitochondrial dysfunction and the role of reactive oxygen species (ROS) produced by mitochondria have been proposed in the pathogenesis of sepsis. Maresins have protective and resolving effects in experimental models of infection. In the present study, we investigated the effects of maresin 1 (MaR1) on mitochondrial function in cecal ligation and puncture (CLP)-induced sepsis and sepsis patients to identify mechanisms underlying maresin 1-mediated stimulation of ROS in mitochondria. We found that treatment with MaR1 significantly inhibited production of cytokines, decreased bacterial load in the peritoneal lavage fluid, reduced the number of neutrophils, decreased lactic acid level and upregulated cyclic AMP (cAMP) concentration, with the outcome of decreased lung injury in CLP-induced sepsis in mice. The effects of MaR1 on downregulation nitric oxide (NOX) activity, improvement CAT and SOD activity to inhibit ROS production in mitochondria was dependent on lipoxin receptor (ALX) and cAMP. Survival rates were significantly increased after the treatment of mice with MaR1. In BMDM stimulated with LPS, MaR1 inhibited the ROS production, downregulated enzyme activity, reduced mtO2 production, increased mitochondrial membrane potential, improved adenosine triphosphate (ATP) content and mitochondrial DNA (mtDNA) copy number. Finally, the effects of MaR1 on ROS production in the blood of healthy volunteers stimulated with LPS or sepsis patients were associated with ALX and cAMP. Taken together, these data suggest that treatment with MaR1 could attenuate mitochondrial dysfunction during sepsis through regulating ROS production.

Mitochondrial Dysfunction as a Predictor and Driver of Alzheimer's Disease-Like Pathology in OXYS Rats.

Growing evidence suggests that mitochondrial dysfunction is an early event in sporadic Alzheimer's disease (AD), but the impact of mitochondrial dysfunction on the transition from healthy aging to AD remains elusive. Here we estimated the influence of mitochondrial dysfunction on the initiation of AD signs in OXYS rats, which simulate key characteristics of sporadic AD. We assessed the mitochondrial ultrastructure of pyramidal neurons of the hippocampus at the age preceding the development (age 20 days), during manifestation (4-5 months), and at the well-pronounced stages (18-24 months) of the AD-like pathology in OXYS rats. Ultrastructural alterations were collated with the amounts of proteins mediating mitochondrial dynamics [mitofusins (MFN1 and MFN2) and dynamin-1-like protein (DRP1)]; with activity of respiratory chain complexes I, IV, and V in the hippocampal mitochondria; with reactive oxygen species (ROS) production; and with expression of uncoupling protein 2 (UCP2) regulating ROS production. Already at the preclinical stage, OXYS rats showed some characteristic changes in hippocampal mitochondria, which increased in size with the manifestation and progression of AD-like pathology, including decreased activity of respiratory complexes against the background of greater fusion and formation of larger mitochondria. Signs of AD developed simultaneously with increasing dysfunction of mitochondria, with a dramatic decrease in their number, and with increased fission but without upregulation of ROS production (observed only in 20-day-old OXYS rats). Summarizing the data from our present and previous studies, we conclude that mitochondrial dysfunction appears to mediate or possibly even initiate pathological molecular cascades of AD-like pathology in OXYS rats and can be considered a predictor of the early development of the late-onset form of AD in humans.

P-107 - Inhibitory effect of carnosic acid by the down-regulation of ROS generation and the up-regulation of ROS scavenging on adipocyte differentiation

Reactive oxygen species (ROS) are known to be involved in the maintenance of redox homeostasis and various cellular signaling pathways. Non-toxic level of ROS has been reported to be involved in the adipocyte differentiation from 3T3-L1 cells. Previous study showed that ROS is intermediately generated in pre-adipocytes and be involved in modulating pre-adipocyte differentiation. The potent inhibitory effect of carnosic acid (CA) on adipocyte differentiation was observed using Oil Red O staining assay. The ROS level reached to a maximum level at two days in adipocyte differentiation. CA attenuated the expression of NADPH oxidase 4 (Nox4) and p47phox. In addition, CA suppressed the expression of transcription factor such as C/EBPα, C/EBPβ, PPARγ, and NF-κB involved in adipocyte differentiation. Furthermore, CA enhanced the expression of phase II antioxidant enzymes through the up-regulation of Nrf2 activation. These results indicate that the inhibitory effect of CA on the differentiation of 3T3-L1 cells into adipocyte can be accomplished by regulating ROS production via Nox 4 and ROS scavenging via Nrf2 activation. Consequently, the regulation of ROS may be the crucial factor in inhibitory effect of CA on adipogenesis, further implying ROS as a prime target of obesity control.

The Double-Edged Sword Profile of Redox Signaling: Oxidative Events As Molecular Switches in the Balance between Cell Physiology and Cancer.

The intracellular redox state in the cell depends on the balance between the level of reactive oxygen species (ROS) and the activity of defensive systems including antioxidant enzymes. This balance is a dynamic process that can change in relation to many factors and/or stimuli induced within the cell. ROS production is derived from physiological metabolic events. For instance, mitochondria represent the major ROS sources during oxidative phosphorylation, but other systems, such as NADPH oxidase or specific enzymes in certain metabolisms, may account for ROS production as well. Whereas high levels of ROS perturb the cell environment, causing oxidative damage to biological macromolecules, low levels of ROS can exert a functional role in the cell, influencing the activity of specific enzymes or modulating some intracellular signaling cascades. Of particular interest appears to be the role of ROS in tumor systems not only because ROS are known to be tumorigenic but also because tumor cells are able to modify their redox state, regulating ROS production to sustain tumor growth and proliferation. Overall, the scope of this review was to critically discuss the most recent findings pertaining to ROS physiological roles as well as to highlight the controversial involvement of ROS in tumor systems.

3,3′-Diindolylmethane enhances apoptosis in docetaxel-treated breast cancer cells by generation of reactive oxygen species

Context: A major problem in the treatment of cancer is the development of toxic side effects and resistance to chemotherapy. The use of plant compounds to overcome resistance and prevent toxicity is a potential strategy for treatment.Objective: We evaluated whether 3,3′-diindolylmethane (DIM) enhanced the sensitivity of breast cancer cells to docetaxel (DOC).Materials and methods: MDA-MB231 and Sk-BR-3 cells were treated with and without 25 or 50 µM of DIM and 1 nM of DOC for 48 and 72 h, respectively. MTT assay was used to measure cell survival. Apoptosis and intracellular reactive oxygen species (ROS) were determined by flow cytometry. The expression of proteins regulating ROS production and apoptosis was evaluated by immunoblotting technique.Results: Combining 25 µM of DIM with 1 nM DOC decreased cell survival by 42% in MDA-MB231 cells and 59% in Sk-BR-3 cells compared to control, DIM, or DOC (p ≤ 0.05). The combination treatment increased apoptosis over 20% (p ≤ 0.01) in both cell lines, which was associated with decreased Bcl-2, increased Bax, cleaved PARP and activated JNK (p ≤ 0.01). ROS production increased by 46.5% in the MDA-MB231 and 29.3% in Sk-BR-3 cells with the combination compared to DIM or DOC alone. Pretreating cells with N-acetyl-cysteine or Tiron abrogated the anti-survival effect of the combination. The increase in ROS was associated with a 54% decrease in MnSOD and 47% increase in NOX2 protein compared to the other groups.Conclusions: Our findings indicated that DIM enhances the sensitivity of breast cancer cells to DOC treatment by increasing ROS, which led to decreased cell survival and apoptosis.

Protective effects of the mechanistic target of rapamycin against excess iron and ferroptosis in cardiomyocytes.

Clinical studies have suggested that myocardial iron is a risk factor for left ventricular remodeling in patients after myocardial infarction. Ferroptosis has recently been reported as a mechanism of iron-dependent nonapoptotic cell death. However, ferroptosis in the heart is not well understood. Mechanistic target of rapamycin (mTOR) protects the heart against pathological stimuli such as ischemia. To define the role of cardiac mTOR on cell survival in iron-mediated cell death, we examined cardiomyocyte (CM) cell viability under excess iron and ferroptosis conditions. Adult mouse CMs were isolated from cardiac-specific mTOR transgenic mice, cardiac-specific mTOR knockout mice, or control mice. CMs were treated with ferric iron [Fe(III)]-citrate, erastin, a class 1 ferroptosis inducer, or Ras-selective lethal 3 (RSL3), a class 2 ferroptosis inducer. Live/dead cell viability assays revealed that Fe(III)-citrate, erastin, and RSL3 induced cell death. Cotreatment with ferrostatin-1, a ferroptosis inhibitor, inhibited cell death in all conditions. mTOR overexpression suppressed Fe(III)-citrate, erastin, and RSL3-induced cell death, whereas mTOR deletion exaggerated cell death in these conditions. 2',7'-Dichlorodihydrofluorescein diacetate measurement of reactive oxygen species (ROS) production showed that erastin-induced ROS production was significantly lower in mTOR transgenic versus control CMs. These findings suggest that ferroptosis is a significant type of cell death in CMs and that mTOR plays an important role in protecting CMs against excess iron and ferroptosis, at least in part, by regulating ROS production. Understanding the effects of mTOR in preventing iron-mediated cell death will provide a new therapy for patients with myocardial infarction. NEW & NOTEWORTHY Ferroptosis has recently been reported as a new form of iron-dependent nonapoptotic cell death. However, ferroptosis in the heart is not well characterized. Using cultured adult mouse cardiomyocytes, we demonstrated that the mechanistic target of rapamycin plays an important role in protecting cardiomyocytes against excess iron and ferroptosis.

Leptin-induced migration and angiogenesis in rheumatoid arthritis is mediated by reactive oxygen species.

Rheumatoid arthritis (RA) is a progressive autoimmune disease affecting the joints. In this study, we investigated the role of the pro‐angiogenic factor leptin in regulating reactive oxygen species (ROS) to promote cell migration and angiogenesis in RA. We showed that leptin triggered RA fibroblast‐like synoviocyte (FLS) migration by increased ROS expression. Additionally, leptin enhanced human umbilical vein endothelial cell (HUVEC) tube formation in a ROS/hypoxia‐inducible factor‐1α‐dependent manner, accompanied by increased production of vascular endothelial growth factor and interleukin (IL)‐6. We also revealed that antagonists of tumor necrosis factor, IL‐6 and IL‐1β down‐regulated ROS production of RA FLS induced by leptin, which subsequently attenuated RA FLS migration and HUVEC tube formation. These findings demonstrated that leptin might play an important role in RA FLS migration and HUVEC angiogenesis.

Estrogen Signaling Modulates Mitochondrial ROS Production and Mitochondrial Function in Mouse Bone Marrow Macrophages

Estrogen (E2), the female sex hormone has anti-inflammatory and anti-oxidant properties which have been proposed to play a role its cardioprotective effects. Women have an increase incidence of cardiovascular disease (CVD) in the postmenopausal period when E2 levels are at their lowest. E2 receptors are found on the cell surface, cytoplasm, nucleus, and mitochondria where they can modulate both nuclear and mitochondrial genes. Previous work has shown that E2 receptor levels decrease with age in rodents and humans. We were specifically interested in the role of E2 signaling in macrophages, an inflammatory cell dysregulated in CVD. We hypothesize that E2 preserves mitochondrial function by decreasing reactive oxygen species (ROS) and preserving mitochondrial membrane potential. In order to better study the effects of E2 signaling on mitochondrial function and anti-inflammatory capacity we isolated bone marrow macrophages (BMMs) from 8-13 month old wild type (wt), E2 receptor α knockout (ERα KO) and E2 receptor β knock out (ERβ KO) mice and measured mitochondrial function with the Seahorse Extracellular Flux Analyzer, mitochondrial membrane potential with TMRM and ROS production with DCF-DA. There was no difference in mitochondrial membrane potential in BMMs isolated from wt and ERβ KO mice. To induce inflammation, we treated the BMMS with LPS for 4 hours. There was a significant increase in LPS induced ROS in BMMS isolated from wt and ERβ KO which was further exacerbated in BMMs isolated from ERα KO mice. The maximal and reserve OCR and ECAR was significantly less in BMMs isolated from both ERα KO and ERβ KO compared to wt. These data suggest E2 partially regulates mitochondrial function in macrophages through both ERα and ERβ while ROS production is less dependent on ERα in BMMs. Taken together, these data provide evidence of E2 signaling modulating mitochondrial function and regulating ROS production through specific E2 receptors in BMMs. These results may help us to understand the anti-inflammatory role of E2 in pre-menopausal women and the increased incidence of CVD in post-menopausal women.

Basidiomycete-specific PsCaMKL1 encoding a CaMK-like protein kinase is required for full virulence of Puccinia striiformis f. sp. tritici.

Calcium/calmodulin-dependent kinases (CaMKs) are Ser/Thr protein kinases (PKs) that respond to changes in cytosolic free Ca2+ and play diverse roles in eukaryotes. In fungi, CAMKs are generally classified into four families CAMK1, CAMKL, RAD53 and CAMK-Unique. Among these, CAMKL constitutes the largest family. In some fungal plant pathogens, members of the CaMKL family have been shown to be responsible for pathogenesis. However, little is known about their role(s) in rust fungi. In this study, we functionally characterized a novel PK gene, PsCaMKL1, from Puccinia striiformis f. sp. tritici (Pst). PsCaMKL1 belongs to a group of PKs that is evolutionarily specific to basidiomyceteous fungi. PsCaMKL1 shows little intra-species polymorphism between Pst isolates. PsCaMKL1 transcripts are highly elevated at early infection stages, whereas gene expression is downregulated in barely germinated urediospores under KN93 treatment. Overexpression of PsCaMKL1 in fission yeast increased resistance to environmental stresses. Knock down of PsCaMKL1 using host-induced gene silencing (HIGS) reduced the virulence of Pst accompanied by reactive oxygen species (ROS) accumulation and a hypersensitive response. These results suggest that PsCaMKL1 is a novel pathogenicity factor that exerts it virulence function by regulating ROS production in wheat.

Functional characterization of a reactive oxygen species modulator 1 gene in Litopenaeus vannamei

Reactive oxygen species (ROS) imparts a dual effect on multicellular organisms, wherein high levels are usually harmful, and low levels could facilitate in combating pathogenic microorganisms; therefore, the regulation of ROS production is critical. Previous studies have suggested that ROS contributes to resistance to the white spot syndrome virus (WSSV) or Vibrio alginolyticus in Litopenaeus vannamei. However, the regulation of ROS metabolism in L. vannamei remains elusive. In the present study, we proved that the overexpression of L. vannamei reactive oxygen species modulator 1 (LvROMO1) increases ROS production in Drosophila Schneider 2 (S2) cells. Real-time RT-PCR analysis indicated that LvROMO1 is induced by WSSV or V. alginolyticus infection and β-glucan or microcystin (MC-LR) injection. Further investigation showed that LvROMO1 responding to MC-LR, thereby inducing hemocytes to undergo apoptosis, and ultimately resulting in hepatopancreatic damage. And LvROMO1 downregulation induced an increase in the cumulative mortality of WSSV-infected shrimp by reducing ROS production and suppressing the expression of antimicrobial peptides genes. The findings of present study suggest that LvROMO1 plays an important role in ROS production in L. vannamei and is involved in innate immunity.

Unconventional role of voltage-gated proton channels (VSOP/Hv1) in regulation of microglial ROS production.

It has been established that voltage-gated proton channels (VSOP/Hv1), encoded by Hvcn1, support reactive oxygen species (ROS) production in phagocytic activities of neutrophils (El Chemaly etal. ) and antibody production in B lymphocytes (Capasso etal. ). VSOP/Hv1 is a potential therapeutic target for brain ischemia, since Hvcn1 deficiency reduces microglial ROS production and protects brain from neuronal damage (Wu etal. ). In the present study, we report that VSOP/Hv1 has paradoxical suppressive role in ROS production in microglia. Extracellular ROS production was lower in neutrophils of Hvcn1-/- mice than WT mice as reported. In contrast, it was drastically enhanced in isolated Hvcn1-/- microglia as compared with cells from WT mice. Actin dynamics was altered in Hvcn1-/- microglia and intracellular distribution of cytosolic NADPH oxidase subunit, p67, was changed. When expression levels of oxidative stress responsive antioxidant genes were compared between WT and Hvcn1-/- in cerebral cortex at different ages of animals, they were slightly decreased in Hvcn1-/- mice at younger stage (1day, 5days, 3weeks old), but drastically increased at aged stage (6months old), suggesting that the regulation of microglial ROS production by VSOP/Hv1 is age-dependent. We also performed brain ischemic stroke experiments and found that the neuroprotective effect of VSOP/Hv1deficiency on infarct volume depended on the age of animals. Taken together, regulation of ROS production by VSOP/Hv1 is more complex than previously thought and significance of VSOP/Hv1 in microglial ROS production depends on age.