ROS Damage Research Articles

Integrated Proteome and Cytokine Profiles Reveal Ceruloplasmin Eliciting Liver Allograft Tolerance via Antioxidant Cascades.

Acute rejection (AR) and spontaneous tolerance may occur after allograft orthotopic liver transplants (OLT) performed in certain combinations of donor and recipient rat strains, yet the underlying molecular cascades involved in these conditions remain poorly understood. Comprehensive analysis with proteomic tools revealed that ceruloplasmin was highly expressed during the tolerant period on day 63 post-OLT (POD 63) compared to the rejected samples on POD 14. Meanwhile, cytokine expression profiles implied that the inflammation was significantly stimulated in the AR subjects. Again, protein carbonylation was dramatically upregulated in the rejected subject within the tolerant group. Knockdown of ceruloplasmin would elicit more severe ROS damage, leading to cell death in the presence of H2O2, which induced Nrf2 cascade and the recovery of ceruloplasmin to mediate spontaneous tolerance. In summary, ceruloplasmin may contribute to amending the oxidative stress that eventually causes cell apoptosis and to maintaining the survival of hepatocytes in a drug-free tolerance OLT model.

Protective Role of Selenium Against Hemolytic Anemia Is Mediated Through Redox Modulation

Selenium (Se), an essential trace element and potent nutritional antioxidant, exerts its biological effects through incorporation into selenoproteins like glutathione peroxidase (GPx). Modest decrement in the levels of GPx could be partly responsible for peroxidation of RBCs, which results into hemolytic anemia. Therefore, it is hypothesized that dietary Se, as selenoproteins (GPx), can maintain the homeostasis in RBCs and regulate the erythropoiesis by preventing oxidative stress-mediated hemolysis. Se-deficient (0.01ppm), Se-adequate (0.1ppm sodium selenite), and Se-supplemented (0.5ppm sodium selenite) status were created in Balb/c mice by feeding yeast-based diets for 8weeks and established by measuring Se levels in plasma and activities, expressions of Se-dependent selenoproteins. Fifty percent of mice from each differential Se group were treated with phenylhydrazine (PHZ, 20mg/kg, i.p.) to induce hemolytic anemia. Results indicated that PHZ-treated Se-deficient animals demonstrated increased hemolysis, abnormal RBC morphology, increase in Heinz bodies and reticulocytes, and denaturation of hemoglobin to globin precipitates and methemoglobin. Se supplementation protected against these hemolytic changes and makes RBCs less fragile. These findings were consistent with dietary Se concentration-dependent changes in activity and expression of GPx indicating that ROS-mediated oxidative stress is integral to hemolysis. Protective effects of Se supplementation against increased levels of ROS, protein carbonyls, and peroxide damage to membrane lipids and enzymatic antioxidants validated these observations. In conclusion, dietary Se supplementation protected the RBCs against hemolysis by mitigating ROS-mediated oxidative stress.

GRSF1 suppresses cell senescence.

A prominent phenotype triggered by the loss of mitochondrial homeostasis is cellular senescence, characterized by cessation of growth and a senescence-associated secretory phenotype (SASP). We identified the G-rich RNA sequence-binding factor 1 (GRSF1) as a major mitochondrial protein implicated in this response. GRSF1 levels declined in senescent cells through reduced protein stability, and lowering GRSF1 abundance caused mitochondrial stress leading to elevated production of superoxide, increased DNA damage foci, and diminished cell proliferation. In addition, reducing GRSF1 increased the activity of a senescence-associated β-galactosidase (SA-β-gal) and the production and secretion of the SASP factor interleukin 6 (IL6). Together, our findings indicate that the decline in GRSF1 levels during cellular senescence contributes to impairing mitochondrial function, elevating ROS and DNA damage, suppressing growth, and implementing a pro-inflammatory program.

Abstract 467: p53 Stabilized iPS Derived Cardiomyocytes Promote Myocardial Repair

Rapid and continuous culturing of cells leads to accumulation of oxidative stress and DNA damage. These heterogeneous mixtures of healthy and damaged functionally incompetent cells (FIC) are not suitable for transplantation. We hypothesized that selecting only the healthy cells and use for cell would improve engraftment rate and cardiac function. Utilizing the discriminating nature of p53, inducing apoptosis in damaged cells while retaining cell cycle in healthy cells, we tested whether stabilizing p53 can retain only the healthy cells in the culture. p53 in iPS cultures were stabilized using small-molecule nutlin-3a. Cells that didn’t die due to p53 stabilization were collected and differentiated into cardiomyocytes. The markers for cell stress such as the ROS, superoxide and DNA damage were significantly reduced in p53S cells. Following differentiation p53S-CMs were characterized by high expression of CM markers Nkx2.5, Gata4, TnI, MYL2, MLYK, KCNH2 and CAMK2B. Efficiency of p53S-CM to engraft and remuscularize the injured myocardium were tested in small animal MI model. After one week of cell transplantion cardiac function, infarct size and engraftment rate of cells were comparable between p53S-CM and control-CM recieved groups. At week four significant improvement in cardiac function and reduction in infarct size were observed in both groups. However, improvement in these parameters were more prominent in p53S-CM groups. Macrophage analysis revealed enhanced recruitment of anti-infalmatory M2 macrophages in p53S-CM groups and inflammatory M1 macropaheges in control-CM groups at the injection site. Moreover, p53S-CM exosomes induced predominant M2 polarization while control-CM exosomes favored M1 polarization of RAW264.7 macrophages. Our data clearly shows functionally competent cells can be isolated from a population of heterogeneous cells by stabilizing p53. The p53S-CMs showed superior performance in in vitro and in vivo. Therefore, selecting healthy cells by stabilizing p53 would better repopulate the deteriorating myocardium and improve cardiac performance.

Perfluorooctanesulfonate (PFOS) Induces Apoptosis Signaling and Proteolysis in Human Lymphocytes through ROS Mediated Mitochondrial Dysfunction and Lysosomal Membrane Labialization.

Perfluorinated compounds (PFCs) such as perfluorooctanesulfonate (PFOS) are stable chemicals that accumulate in biological matrix. Toxicity of these compounds including immunotoxicity has been demonstrated in experimental models and wildlife. Although limited number of studies examined the effects of PFOS on human lymphocytes but so far no research has investigated the complete mechanisms of PFOS cytotoxicity toward human lymphocytes. The main goal of this investigation was to find out the mechanisms underlying the cytotoxic effect of PFOS toward human lymphocytes using accelerated cytotoxicity mechanisms screening (ACMS) technique. Human lymphocytes were isolated from blood of healthy donors using Ficoll-paquePLUS standard method. Cell viability was determined following 12 h of incubation of human lymphocytes with 100-500 µM PFOS. Our results showed that IC50 concentration (163.5 µM) of PFOS reduced viability of human lymphocytes approximately 50% via increased ROS formation, lipid peroxidation, glutathione depletion and damage to cell sub organelles such as mitochondria and lysosomes. Besides, in this study we demonstrated involvement of cellular proteolysis and activation of caspase-3 in PFOS induced lymphocyte cytotoxicity. We finally concluded that at environmentally related concentration, PFOS can induce toxic effect toward human lymphocytes through induction of oxidative stress and damage to cell sub organelles.

(S)-crizotinib reduces gastric cancer growth through oxidative DNA damage and triggers pro-survival akt signal

Gastric cancer (GC), a common gastrointestinal malignancy worldwide, has poor prognosis and frequent recurrence. There is a great need to identify effective therapy for GC. Crizotinib is a multi-targeted, clinically available oral tyrosine kinase inhibitor approved for lung cancer, but its use for the highly heterogeneous disease of GC is unknown. The goal of this study was to investigate the anti-cancer mechanisms of the (S)-crizotinib in inhibiting GC growth. Human GC cell lines (SGC-7901 and BGC-823) and the (S)-crizotinib-resistant BGC-823/R were cultured for determining the effects of (S)-crizotinib on cell viability, apoptosis, oxidant generation, and cell cycle progression. Involvement of ROS, Akt signaling, MTH1, and DNA damage was tested with respective pharmacological blockade. The in vivo anti-tumor effects of (S)-crizotinib were determined using xenograft tumor mice. Results indicated that (S)-crizotinib decreased GC cell viability, induced growth arrest and apoptosis, and increased levels of γH2AX and Ser1981-phosphorylated ATM, which were inhibited by NAC. The anti-cancer mechanism of (S)-crizotinib was independent of MTH1. Moreover, ATM-activated Akt, a pro-survival signal, whose inhibition further enhanced (S)-crizotinib-induced inhibition of GC cell growth and tumor growth in xenograft mice, and re-sensitized resistant GC cells to (S)-crizotinib. (S)-crizotinib reduced GC cell and tumor growth through oxidative DNA damage mechanism and triggered pro-survival Akt signaling. We conclude that inclusion of Akt inhibition (to block the survival signaling) with (S)-crizotinib may provide an effective and novel combination therapy for GC in the clinical setting.

Fisetin Exerts Antioxidant and Neuroprotective Effects in Multiple Mutant hSOD1 Models of Amyotrophic Lateral Sclerosis by Activating ERK

Oxidative stress exhibits a central role in the course of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease commonly found to include a copper/zinc superoxide dismutase (SOD1) gene mutation. Fisetin, a natural antioxidant, has shown benefits in varied neurodegenerative diseases. The possible effect of fisetin in ALS has not been clarified as of yet. We investigated whether fisetin affected mutant hSOD1 ALS models. Three different hSOD1-related mutant models were used: Drosophila expressing mutant hSOD1G85R, hSOD1G93A NSC34 cells, and transgenic mice. Fisetin treatment provided neuroprotection as demonstrated by an improved survival rate, attenuated motor impairment, reduced ROS damage and regulated redox homeostasis compared with those in controls. Furthermore, fisetin increased the expression of phosphorylated ERK and upregulated antioxidant factors, which were reversed by MEK/ERK inhibition. Finally, fisetin reduced the levels of both mutant and wild-type hSOD1 in vivo and in vitro, as well as the levels of detergent-insoluble hSOD1 proteins. The results indicate that fisetin protects cells from ROS damage and improves the pathological behaviors caused by oxidative stress in disease models related to SOD1 gene mutations probably by activating ERK, thereby providing a potential treatment for ALS.

Porous Se@SiO2 nanocomposites protect the femoral head from methylprednisolone-induced osteonecrosis.

BackgroundMethylprednisolone (MPS) is an important drug used in therapy of many diseases. However, osteonecrosis of the femoral head is a serious damage in the MPS treatment. Thus, it is imperative to develop new drugs to prevent the serious side effect of MPS.MethodsThe potential interferences Se@SiO2 nanocomposites may have to the therapeutic effect of methylprednisolone (MPS) were evaluated by classical therapeutic effect index of acute respiratory distress syndrome (ARDS), such as wet-to-dry weight ratio, inflammatory factors IL-1β and TNF-α. And oxidative stress species (ROS) index like superoxide dismutase (SOD) and glutathione (GSH) were tested. Then, the protection effects of Se@SiO2 have in osteonecrosis of the femoral head (ONFH) were evaluated by micro CT, histologic analysis and Western-blot analysis.ResultsIn the present study, we found that in the rat model of ARDS, Se@SiO2 nanocomposites induced SOD and GSH indirectly to reduce ROS damage. The wet-to-dry weight ratio of lung was significantly decreased after MPS treatment compared with the control group, whereas the Se@SiO2 did not affect the reduced wet-to-dry weight ratio of MPS. Se@SiO2 also did not impair the effect of MPS on the reduction of inflammatory factors IL-1β and TNF-α, and on the alleviation of structural destruction. Furthermore, micro CT and histologic analysis confirmed that Se@SiO2 significantly alleviate MPS-induced destruction of femoral head. Moreover, compared with MPS group, Se@SiO2 could increase collagen II and aggrecan, and reduce the IL-1β level in the cartilage of femoral head. In addition, the biosafety of Se@SiO2 in vitro and in vivo were supported by cell proliferation assay and histologic analysis of main organs from rat models.ConclusionSe@SiO2 nanocomposites have a protective effect in MPS-induced ONFH without influence on the therapeutic activity of MPS, suggesting the potential as effective drugs to avoid ONFH in MPS therapy.

Somatic Mitochondrial DNA Mutations in Diffuse Large B-Cell Lymphoma

Diffuse Large B-Cell Lymphoma (DLBCL) is an aggressive hematological cancer for which mitochondrial metabolism may play an important role. Mitochondrial DNA (mtDNA) encodes crucial mitochondrial proteins, yet the relationship between mtDNA and DLBCL remains unclear. We analyzed the functional consequences and mutational spectra of mtDNA somatic mutations and private constitutional variants in 40 DLBCL tumour-normal pairs. While private constitutional variants occurred frequently in the D-Loop, somatic mutations were randomly distributed across the mitochondrial genome. Heteroplasmic constitutional variants showed a trend towards loss of heteroplasmy in the corresponding tumour regardless of whether the reference or variant allele was being lost, suggesting that these variants are selectively neutral. The mtDNA mutational spectrum showed minimal support for ROS damage and revealed strand asymmetry with increased C > T and A > G transitions on the heavy strand, consistent with a replication-associated mode of mutagenesis. These heavy strand transitions carried higher proportions of amino acid changes – which were also more pathogenic – than equivalent substitutions on the light strand. Taken together, endogenous replication-associated events underlie mtDNA mutagenesis in DLBCL and preferentially generate functionally consequential mutations. Yet mtDNA somatic mutations remain selectively neutral, suggesting that mtDNA-encoded mitochondrial functions may not play an important role in DLBCL.

Protective Effects of Lycium barbarum Extracts on UVB-Induced Damage in Human Retinal Pigment Epithelial Cells Accompanied by Attenuating ROS and DNA Damage.

The medicinal herb Lycium barbarum fruit has been widely used for improving and maintaining the health of the eyes in the Far East for many centuries. This study is aimed at investigating whether protective effects generated from the aqueous (LBA) and ethanol (LBE) extracts of the L. barbarum fruit existed against oxidative stress-induced apoptosis in human retinal pigment epithelial cells. L. barbarum extracts LBA and LBE exerted the activity of ROS scavenging and rescued UVB irradiation-induced growth inhibition in retinal pigment epithelial ARPE-19 cells. Compared to LBA, the ethanol extract LBE exerted a superior protective activity on UVB-induced growth arrest in ARPE-19 cells. Both L. barbarum extracts significantly reduced cell cycle G2-arrest population in ARPE-19 cells. Furthermore, the cytometer-based Annexin V/propidium iodide staining assay further showed that both L. barbarum extracts protected ARPE-19 cells from UVB-induced apoptosis. L. barbarum extracts also reduced the activation of γH2AX, a sensor of DNA damage in ARPE-19 cells in a dose-responsive manner. By using Ingenuity Pathway Analysis (IPA), the bioinformatics revealed that the protective effects of both LBA and LBE extracts might be involved in three signaling pathways, especially the Toll-like receptor (TLR) pathway associated with cellular proliferation. Our study suggests that both ethanol and aqueous extracts of L. barbarum exhibit antioxidant activity and rescue UVB-induced apoptosis of ARPE-19 cells. Collectively, the ethanol extract exerts a superior effect on rescuing UVB-induced growth arrest of ARPE-19 compared to the aqueous extract, which might be associated with the activation of TLR signaling. Our present work will benefit the preventive strategy of herbal medicine-based vision protection for treating eye diseases such as age-related macular degeneration in the future.

Reprogramming of Aged Cells into Pluripotent Stem Cells by Nuclear Transfer.

Stem cells have the potential to differentiate into specialized cell types under specific conditions in vivo or in vitro, which are used to cure many diseases related to aging. Somatic cell nuclear transfer (SCNT) can reprogram differential somatic cells into cloned embryos and embryonic stem cells can be derived from these cloned embryos. Recipient oocytes have healthier mitochondria and can improve the metabolism competence, lessen the ROS damage, and rejuvenate mitochondrial function of aged cells during reprogramming. Here, we describe a protocol to isolate aged somatic cells and reprogram them into embryonic stem cells by SCNT. These stem cells can be used to differentiate into regenerative somatic cells and replace the aged cells.

NRPS-Derived Isoquinolines and Lipopetides Mediate Antagonism between Plant Pathogenic Fungi and Bacteria.

Bacterial-fungal interactions are presumed to be mediated chiefly by small-molecule signals; however, little is known about the signaling networks that regulate antagonistic relationships between pathogens. Here, we show that the ralstonins, lipopeptides produced by the plant pathogenic bacteria Ralstonia solanacearum, interfere with germination of the plant-pathogenic fungus Aspergillus flavus by down-regulating expression of a cryptic biosynthetic gene cluster (BGC), named imq. Comparative metabolomic analysis of overexpression strains of the transcription factor ImqK revealed imq-dependent production of a family of tripeptide-derived alkaloids, the imizoquins. These alkaloids are produced via a nonribosomal peptide synthetase- (NRPS-)derived tripeptide and contain an unprecedented tricyclic imidazo[2,1-a]isoquinoline ring system. We show that the imizoquins serve a protective role against oxidative stress that is essential for normal A. flavus germination. Supplementation of purified imizoquins restored wildtype germination to a ΔimqK A. flavus strain and protected the fungus from ROS damage. Whereas the bacterial ralstonins retarded A. flavus germination and suppressed expression of the imq cluster, the fungal imizoquins in turn suppressed growth of R. solanacearum. We suggest such reciprocal small-molecule-mediated antagonism is a common feature in microbial encounters affecting pathogenicity and survival of the involved species.

Camptosorus sibiricus rupr aqueous extract prevents lung tumorigenesis via dual effects against ROS and DNA damage

Ethnopharmacological relevanceCamptosorus sibiricus Rupr (CSR) is a widely used herbal medicine with antivasculitis, antitrauma, and antitumor effects. However, the effect of CSR aqueous extract on B[a]P-initiated tumorigenesis and the underlying mechanism remain unclear. Moreover, the compounds in CSR aqueous extract need to be identified and structurally characterized. Aim of the studyWe aim to investigate the chemopreventive effect of CSR and the underlying molecular mechanism. Materials and methodsA B[a]P-stimulated normal cell model (BEAS.2B) and lung adenocarcinoma animal model were established on A/J mice. In B[a]P-treated BEAS.2B cells, the protective effects of CSR aqueous extract on B[a]P-induced DNA damage and ROS production were evaluated through flow cytometry, Western blot, real-time quantitative PCR, single-cell gel electrophoresis, and immunofluorescence. Moreover, a model of B[a]P-initiated lung adenocarcinoma was established on A/J mice to determine the chemopreventive effect of CSR in vivo. The underlying mechanism was analyzed via immunohistochemistry and microscopy. Furthermore, the new compounds in CSR aqueous extract were isolated and structurally characterized using IR, HR-ESI-MS, and 1D and 2D NMR spectroscopy. ResultsCSR effectively suppressed ROS production by re-activating Nrf2-mediated reductases HO-1 and NQO-1. Simultaneously, CSR attenuated the DNA damage of BEAS.2B cells in the presence of B[a]P. Moreover, CSR at 1.5 and 3 g/kg significantly suppressed tumorigenesis with tumor inhibition ratios of 36.65% and 65.80%, respectively. The tumor volume, tumor size, and multiplicity of B[a]P-induced lung adenocarcinoma were effectively decreased by CSR in vivo. After extracting and identifying the compounds in CSR aqueous extract, three new triterpene saponins were isolated and characterized structurally. ConclusionsCSR aqueous extract prevents lung tumorigenesis by exerting dual effects against ROS and DNA damage, suggesting that CSR is a novel and effective agent for B[a]P-induced carcinogenesis. Moreover, by isolating and structurally characterizing three new triterpene saponins, our study further standardized the quality of CSR aqueous extract, which could widen CSR clinical applications.

Preclinical study of a Kv11.1 potassium channel activator as antineoplastic approach for breast cancer.

Potassium ion (K+) channels have been recently found to play a critical role in cancer biology. Despite that pharmacologic manipulation of ion channels is recognized as an important therapeutic approach, very little is known about the effects of targeting of K+ channels in cancer. In this study, we demonstrate that use of the Kv11.1 K+ channel activator NS1643 inhibits tumor growth in an in vivo model of breast cancer.Tumors exposed to NS1643 had reduced levels of proliferation markers, high expression levels of senescence markers, increased production of ROS and DNA damage compared to tumors of untreated mice. Importantly, mice treated with NS1643 did not exhibit significant cardiac dysfunction. In conclusion, pharmacological stimulation of Kv11.1 activity produced arrested TNBC-derived tumor growth by generating DNA damage and senescence without significant side effects. We propose that use of Kv11.1 channels activators could be considered as a possible pharmacological strategy against breast tumors.

126 - Loss of Epitranscriptomic Control of Seleno-cysteine Utilization Engages Senescence and Metabolic Reprogramming through mTOR Activation and Predicts Poor Survival in Clear Cell Renal Cell Cancer Patients

Over 14,000 Americans die each year from kidney cancer with clear-cell Renal Cell Carcinoma (ccRCC) being the most prevalent and malignant type of kidney cancer. Recent work has implicated disruptions in glutathione (GSH) metabolism as predictors of poor survival in ccRCC. Maintenance of the GSH redox cycle is reliant on the activities of selenocysteine-containing GSH metabolizing enzymes whose translation is controlled by the alkylation repair homolog 8 (Alkbh8) tRNA methyltransferase. In cells from Alkbh8-/- mice the absence of the tRNA methyltransferase Alkbh8 decreases the levels of many GSH metabolizing selenoproteins, promotes increased ROS and DNA damage levels, and confers enhanced sensitivity to oxidizing agents. Surprisingly the Alkbh8-/- mice reproduce, thrive normally but display phenotypic characteristics of premature ageing such as weight loss, reduced subcutaneous fat, alopecia (hair loss), kyphosis (curvature of the spine) when compared to their aged-matched WT control. Alkbh8-deficiency also triggers a senescence and metabolic gene signature that is predictive (Hazard Ratio 2.94, p

Nijmegen Breakage Syndrome fibroblasts and iPSCs: cellular models for uncovering disease-associated signaling pathways and establishing a screening platform for anti-oxidants

Nijmegen Breakage Syndrome (NBS) is associated with cancer predisposition, premature aging, immune deficiency, microcephaly and is caused by mutations in the gene coding for NIBRIN (NBN) which is involved in DNA damage repair. Dermal-derived fibroblasts from NBS patients were reprogrammed into induced pluripotent stem cells (iPSCs) in order to bypass premature senescence. The influence of antioxidants on intracellular levels of ROS and DNA damage were screened and it was found that EDHB-an activator of the hypoxia pathway, decreased DNA damage in the presence of high oxidative stress. Furthermore, NBS fibroblasts but not NBS-iPSCs were found to be more susceptible to the induction of DNA damage than their healthy counterparts. Global transcriptome analysis comparing NBS to healthy fibroblasts and NBS-iPSCs to embryonic stem cells revealed regulation of P53 in NBS fibroblasts and NBS-iPSCs. Cell cycle related genes were down-regulated in NBS fibroblasts. Furthermore, oxidative phosphorylation was down-regulated and glycolysis up-regulated specifically in NBS-iPSCs compared to embryonic stem cells. Our study demonstrates the utility of NBS-iPSCs as a screening platform for anti-oxidants capable of suppressing DNA damage and a cellular model for studying NBN de-regulation in cancer and microcephaly.

P 079 - Contribution of NADPH oxidase isoforms to angiotensin II-mediated oxidative stress and DNA damage in the mouse kidney

Hypertension caused by elevated levels of the blood pressure-regulating hormone angiotensin II (AngII) leads to oxidative stress and DNA damage in kidneys of mice. In vitro-studies showed a role of the free radical-generating NADPH oxidase (Nox) in this damage. Here, we studied the contribution of the isoforms Nox1, 2 and 4 to AngII-induced oxidative stress and DNA lesions in the kidney. Male wildtype (WT) C57BL/6, Nox1-, Nox2- and Nox4-knockout (KO) mice were infused with either vehicle or AngII during 28 days. Afterwards, urine and kidneys were analyzed for markers of oxidative stress and DNA damage. In WT mice, AngII induced hypertension, elevated urinary albumin levels and formation of ROS and DNA damage in the kidney. In Nox2- and Nox4-KO mice blood pressure was as high as in WT mice but lower in Nox1-KO mice. A rise in urinary albumin and systemic oxidative stress due to AngII was observed in all KO mice. In kidney tissue, only Nox1-KO mice showed no significant ROS formation. Basal values of genomic damage were higher in Nox2- and Nox4-KO mice. Only in Nox1-KO mice AngII did not cause significantly more DNA double strand breaks than in the controls. Nox1 seems to be mostly responsible for the AngII-induced generation of ROS in mouse kidney. Surprisingly, genomic damage in kidneys of Nox2- and Nox4-KO mice was already increased in the absence of AngII.

4-Bromodiphenyl Ether Induces Germ Cell Apoptosis by Induction of ROS and DNA Damage in Caenorhabditis elegans.

4-Bromodiphenyl Ether Induces Germ Cell Apoptosis by Induction of ROS and DNA Damage in Caenorhabditis elegans.

An Antifungal Mechanism of Protolichesterinic Acid from the Lichen Usnea albopunctata Lies in the Accumulation of Intracellular ROS and Mitochondria-Mediated Cell Death Due to Apoptosis in Candida tropicalis

Candida species causes superficial and life-threatening systemic infections and are difficult to treat due to the resistance of these organism to various clinically used drugs. Protolichesterinic acid is a well-known lichen compound. Although the antibacterial activity of protolichesterinic acid has been reported earlier, the antifungal property and its mechanism of action are still largely unidentified. The goal of the present investigation is to explore the anticandidal activity and mechanism of action of protolichesterinic acid, especially against Candida tropicalis. The Minimum Inhibitory Concentration (MIC) value was established through microdilution techniques against four Candida species and out of four species tested, C. tropicalis showed a significant effect (MIC: 2 μg/ml). In the morphological interference assay, we observed the enhanced inhibition of hyphae when the cells were treated with protolichesterinic acid. Time-kill assay demonstrated that the maximum rate of killing was recorded between 2 and 6 h. C. tropicalis exposed to protolichesterinic acid exhibited an increased ROS production, which is one of the key factors of fungal death. The rise in ROS was due to the dysfunction of mitochondria caused by protolichesterinic acid. We confirmed that protolichesterinic acid-induced dysfunction of mitochondria in C. tropicalis. The damage of cell membrane due to protolichesterinic acid treatment was confirmed by the influx of propidium iodide and was further confirmed by the release of potassium ions. The treatment of protolichesterinic acid also triggered calcium ion signaling. Moreover, it commenced apoptosis which is clearly evidenced by Annexin V and propidium iodide staining. Interestingly protolichesterinic acid recorded excellent immunomodulatory property when tested against lymphocytes. Finally protolichesterinic acid showed low toxicity toward a normal human cell line Foreskin (FS) normal fibroblast. In in vivo test, protolichesterinic acid significantly enhanced the survival of C. tropicalis infected Caenorhabditis elegans. This investigation proposes that the protolichesterinic acid induces apoptosis in C. tropicalis via the enhanced accumulation of intracellular ROS and mitochondrial damage, which leads fungal cell death via apoptosis. Our work revealed a new key aspect of mechanisms of action of protolichesterinic acid in Candida species. This article is the first study on the antifungal and mechanism of action of protolichesterinic acid in Candida species.

Fusarium infection causes genotoxic disorders and antioxidant-based damages in Orobanche spp.

This study aims to evaluate the toxic effects of Fusarium oxysporum on root parasitic weed, Orobanche spp. Comparative genetic and gene expression studies were conducted on uninfected and fungus-infected orobanches. In genetic studies, isolated total DNA was amplified by RAPD PCR. Fragment properties were analysed by GTS test. According to the results, the fragment properties of control and Fusarium infected (experimental) groups varied widely; and it has been observed that Fusarium has genotoxic effects on the DNA of orobanches. In gene expression studies, the expression levels of genes encoding enzymes or proteins were associated with ROS damage and toxic effects, therefore, gene expressions of Mn-superoxide dismutase (SOD), Zn-superoxide dismutase (=SOD2, mitochondrial), glutamine synthetase (GS), heat shock protein gene (HSP70), BAX, Caspase-3 and BCL2 were significantly higher in the experimental group. In the light of obtained data, it was concluded that F. oxysporum (1) caused heavy ROS damage in Orobanche (2) induced significant irrevocable genotoxic effects on the DNA of Orobanche, (3) degraded protein metabolism and synthesis, and finally (4) triggered apoptosis. The results of this study can be a ground for further research on reducing the toxic effects of Fusarium on agricultural products, so that advancements in bio-herbicide technology may provide a sustainable agricultural production.