Multiple paths of plant host toxicity are associated with the fungal toxin cercosporin.

The Cercospora species of fungi are responsible for leaf spot disease affecting many key economic crops. Most of these fungi secrete a toxic photodynamic molecule, cercosporin, that reacts with light and oxygen to produce reactive singlet oxygen (1 O2 ) contributing to fungal virulence. We show similar cellular localization and aetiology of cercosporin in the non-host Arabidopsis and the host Nicotiana benthamiana. Cercosporin accumulates in cell membranes in an oxidized state and in plastids in a mixture of redox states in a manner that is dependent on ongoing photosynthetic processes. We observed that cercosporin rapidly compromised photosynthesis as measured by Fv /Fm , NPQ, and photosystem I (PSI) parameters. Stomatal guard cells in particular demonstrated rapid light-dependent membrane permeabilization that led to changes in leaf conductance. We showed that cercosporin-mediated 1 O2 generation oxidized RNA to form 8-oxoguanosine (8-oxoG), leading to translational attenuation and induction of 1 O2 signature gene transcripts. We also identified a subset of cercosporin-induced transcripts that were independent of the photodynamic effect. Our results point to the multimodal action of cercosporin that includes the inhibition of photosynthesis, the direct oxidation of nucleic acid residues and the elicitation of complex transcriptome responses.

Attenuation of cytosolic translation by RNA oxidation is involved in singlet oxygen-mediated transcriptomic responses.

Singlet oxygen (1 O2 ) production is associated with stress signalling. Here, using Arabidopsis as a model system, we study the effects of the accumulation of 8-hydroxyguanosine (8-oxoG), a major product of 1 O2 -mediated RNA oxidation. We show that 8-oxoG can accumulate in vivo when 1 O2 is produced in the cytoplasm. Conditions for such production include the application of RB in the light, dark-to-light transitions in the flu mutant, or subjecting plants to combined dehydration/light exposure. Transcriptomes of these treatments displayed a significant overlap with transcripts stimulated by the cytosolic 80S ribosomal translation inhibitors, cycloheximide and homoharringtonine. We demonstrate that 8-oxoG accumulation correlates with a decrease in RNA translatability, resulting in the rapid decrease of the levels of labile gene repressor elements such as IAA1 and JAZ1 in a proteasome-dependent manner. Indeed, genes regulated by the labile repressors of the jasmonic acid signalling pathway were induced by cycloheximide, RB or dehydration/light treatment independently of the hormone. The results suggest that 1 O2 , by oxidizing RNA, attenuated cellular translatability and caused specific genes to be released from the repression of their cognate short half-life repressors. The findings here describe a novel means of gene regulation via the direct interaction of 1 O2 with RNA.

Salivary 8-hydroxyguanosine levels in smokers and non-smokers with chronic periodontitis.

This case-controlled clinical trial was performed on the salivary 8-hydroxyguanosine (8-OHdG) levels in smokers and non-smokers with chronic periodontitis after non-surgical periodontal therapy. Subjects (N = 40) with periodontitis (smokers and non-smokers) and with clinically healthy conditions (smokers and non-smokers) were assigned to this study. At baseline, clinical periodontal parameters (plaque index, gingival index, pocket probing depth and clinical attachment levels) were evaluated. Saliva samples were obtained pre- and post-treatment to quantify the 8-OHdG levels using Elisa technique. Subjects diagnosed with chronic periodontitis with smoking habit (CPs) and non-smokers (CPns) received scaling and root planing. In clinically healthy subjects with smoking habit (CHs) and non-smokers (CHns), only oral hygiene tutoring was performed. All clinical measurements and salivary collection were repeated in a 3-month recall interval. Data were analyzed using Anova, Tukey post hoc test and Mann-Whitney 'U' tests (P < 0.05). At baseline, CPs and CPns groups showed significantly higher PI, GI, PD and CAL values than those of CHns and CHs (P < 0.001). Baseline salivary levels of 8-OHdG were significantly higher in CPs group (14.775 pg/mL) (P < 0.001) compared to the other groups. All clinical parameters in chronic periodontitis group improved at the 3rd month recall interval, however, with regards to 8-OHdG values, the CP smoker category still had a higher level compared to CP non-smoker. This study reflects an on-going periodontal destructive status in smokers and salivary 8-OHdG levels could be recognized as an oxidative biomarker for determining periodontal tissue destruction.

Reactive Oxygen Species Are Key Mediators of Demyelination in Canine Distemper Leukoencephalitis but not in Theiler's Murine Encephalomyelitis.

(1) Background: Canine distemper virus (CDV)-induced demyelinating leukoencephalitis (CDV-DL) in dogs and Theiler's murine encephalomyelitis (TME) virus (TMEV)-induced demyelinating leukomyelitis (TMEV-DL) are virus-induced demyelinating conditions mimicking Multiple Sclerosis (MS). Reactive oxygen species (ROS) can induce the degradation of lipids and nucleic acids to characteristic metabolites such as oxidized lipids, malondialdehyde, and 8-hydroxyguanosine. The hypothesis of this study is that ROS are key effector molecules in the pathogenesis of myelin membrane breakdown in CDV-DL and TMEV-DL. (2) Methods: ROS metabolites and antioxidative enzymes were assessed using immunofluorescence in cerebellar lesions of naturally CDV-infected dogs and spinal cord tissue of TMEV-infected mice. The transcription of selected genes involved in ROS generation and detoxification was analyzed using gene-expression microarrays in CDV-DL and TMEV-DL. (3) Results: Immunofluorescence revealed increased amounts of oxidized lipids, malondialdehyde, and 8-hydroxyguanosine in CDV-DL while TMEV-infected mice did not reveal marked changes. In contrast, microarray-analysis showed an upregulated gene expression associated with ROS generation in both diseases. (4) Conclusion: In summary, the present study demonstrates a similar upregulation of gene-expression of ROS generation in CDV-DL and TMEV-DL. However, immunofluorescence revealed increased accumulation of ROS metabolites exclusively in CDV-DL. These results suggest differences in the pathogenesis of demyelination in these two animal models.

The role of mitochondrial DNA damage at skeletal muscle oxidative stress on the development of type 2 diabetes.

Reduced cellular response to insulin in skeletal muscle is one of the major components of the development of type 2 diabetes (T2D). Mitochondrial dysfunction involves in the accumulation of toxic reactive oxygen species (ROS) that leads to insulin resistance. The aim of this study was to verify the involvement of mitochondrial DNA damage at ROS generation in skeletal muscle during development of T2D. Wistar rats were fed a diet containing 60% fat over 8 weeks and at day 14 a single injection of STZ (25 mg/kg) was administered (T2D-induced). Control rats received standard food and an injection of citrate buffer. Blood and soleus muscle were collected. Abdominal fat was quantified as well as glucose, triglyceride, LDL, HDL, and total cholesterol in plasma and mtDNA copy number, cytochrome b (cytb) mRNA, 8-hydroxyguanosine, and 8-isoprostane (a marker of ROS) in soleus muscle. T2D-induced animal presented similar characteristics to humans that develop T2D such as changes in blood glucose, abdominal fat, LDL, HDL and cholesterol total. In soleus muscle 8-isoprostane, mtDNA copy number and 8-hydroxyguanosine were increased, while cytb mRNA was decreased in T2D. Our results suggest that in the development of T2D, when risks factors of T2D are present, intracellular oxidative stress increases in skeletal muscle and is associated with a decrease in cytb transcription. To overcome this process mtDNA increased but due to the proximity of ROS generation, mtDNA remains damaged by oxidation leading to an increase in ROS in a vicious cycle accounting to the development of insulin resistance and further T2D.

Consequences of RNA oxidation on protein synthesis rate and fidelity: implications for the pathophysiology of neuropsychiatric disorders.

Unlike DNA, oxidative damage to RNA has received little attention presumably due to the assumed transient nature of RNA. However, RNAs including mRNA can persist for several hours to days in certain tissues and are demonstrated to sustain greater oxidative damage than DNA. Because neuronal cells in the brain are continuously exposed to reactive oxygen species due to a high oxygen consumption rate, it is not surprising that neuronal RNA oxidation is observed as a common feature at an early stage in a series of neurodegenerative disorders. A recent study on a well-defined bacterial translation system has revealed that mRNA containing 8-oxo-guanosine (8-oxoGuo) has little effect on fidelity despite the anticipated miscoding. Indeed, 8-oxoGuo-containing mRNA leads to ribosomal stalling with a reduced rate of peptide-bond formation by 3-4 orders of magnitude and is subject to no-go decay, a ribosome-based mRNA surveillance mechanism. Another study demonstrates that transfer RNA oxidation catalyzed by cytochrome c (cyt c) leads to its depurination and cross-linking, which may facilitate cyt c release from mitochondria and subsequently induce apoptosis. Even more importantly, a discovery of oxidized microRNA has been recently reported. The oxidized microRNA causes misrecognizing the target mRNAs and subsequent down-regulation in the protein synthesis. It is noteworthy that oxidative modification to RNA not only interferes with the translational machinery but also with regulatory mechanisms of noncoding RNAs that contribute toward the biological complexity of the mammalian brain. Oxidative RNA damage might be a promising therapeutic target potentially useful for an early intervention of diverse neuropsychiatric disorders.

A fully validated bioanalytical method using an UHPLC-MS/MS system for quantification of DNA and RNA oxidative stress biomarkers.

A new, rapid and effective ultra-high-performance liquid chromatography method with mass spectrometry detection is described for the separation and quantification of 8-hydroxy-2-deoxyguanosine, 8-hydroxyguanosine and creatinine in human urine. The present study uses an isotope-labelled internal standard ([15N]5-8-hydroxy-2-deoxyguanosine), a BIO core-shell stationary phase and an isocratic elution of methanol and water. Sample preparation of human urine was performed by solid-phase extraction (SPE) on Oasis HLB cartridges with methanol/water 50:50 (v/v) elution. Extraction recoveries ranged from 98.1% to 109.2%. Biological extracts showed high short-term stability. Several aspects of this procedure make it suitable for both clinical and research purposes: a short elution time of less than 3.2 min, an intra-day precision of 2.5-8.9%, an inter-day precision of 3.4-8.7% and low limits of quantification (27.7 nM for 8-hydroxyguanosine, 6.0 nM for 8-hydroxy-2-deoxyguanosine). Finally, simultaneous analysis of DNA and RNA oxidative stress biomarkers is a useful tool for monitoring disease progression in neurodegenerative disorders and cancer. Graphical abstract UHPLC-MS/MS analysis of DNA and RNA oxidative stress biomarkers.

DNA damage in inhabitants exposed to heavy metals near Hudiara drain, Lahore, Pakistan.

The current study was conducted on the inhabitants living in the area adjacent to the Hudiara drain using bore water and vegetables adjacent to the Hudiara drain. Toxic heavy metals badly affect human health because of industrial environmental contamination. Particularly hundreds of millions of individuals globally have faced the consequences of consuming water and food tainted with pollutants. Concentrations of heavy metals in human blood were elevated in Hudiara drainings in Lahore city, Pakistan, due to highly polluted industrial effluents. The study determined the health effects of high levels of heavy metals (Cd, Cu, Zn, Fe, Pb, Ni, Hg, Cr) on residents of the Hudiara draining area, including serum MDA, 8-Isoprostane, 8-hydroxyguanosine, and creatinine levels. An absorption spectrophotometer was used to determine heavy metals in wate water, drinking water, soil, plants and human beings blood sampleas and ELISA kits were used to assess the level of 8-hydroxyguanosine, MDA, 8-Isoprostane in plasma serum creatinine level. Waste water samples, irrigation water samples, drinking water samples, Soil samples, Plants samples and blood specimens of adult of different weights and ages were collected from the polluted area of the Hudiara drain (Laloo and Mohanwal), and control samples were obtained from the unpolluted site Sheiikhpura, 60 km away from the site. Toxic heavy metals in blood damage the cell membrane and DNA structures, increasing the 8-hydroxyguanosine, MDA, creatinine, and 8-Isoprostane. Toxic metals contaminated bore water and vegetables, resulting in increased levels of creatinine, MDA, Isoprostane, and 8-hydroxy-2-guanosine in the blood of inhabitants from the adjacent area Hudiara drain compared to the control group. In addition,. This study also investigated heavy metal concentrations in meat and milk samples from buffaloes, cows, and goats. In meat, cow samples showed the highest Cd, Cu, Fe and Mn concentrations. In milk also, cows exhibited elevated Cu and Fe levels compared to goats. The results highlight species-specific variations in heavy metal accumulation, emphasizing the need for targeted monitoring to address potential health risks. The significant difference between the two groups i.e., the control group and the affected group, in all traits of the respondents (weight, age, heavy metal values MDA, 8-Isoprostane, 8-hydroxyguaniosine, and serum creatinine level). Pearson's correlation coefficient was calculated. The study has shown that the level of serum MDA, 8-Isoprostane, 8-hydroxyguaniosine, or creatinine has not significantly correlated with age, so it is independent of age. This study has proved that in Pakistan, the selected area of Lahore in the villages of Laloo and Mohanwal, excess of heavy metals in the human body damages the DNA and increases the level of 8-Isoprostane, MDA, creatinine, and 8-hydroxyguaniosine. As a result, National and international cooperation must take major steps to control exposure to heavy metals.

Atrophic astrocytes in aged marmosets present tau hyperphosphorylation, RNA oxidation, and DNA fragmentation.

Astrocytes perform multiple essential functions in the brain showing morphological changes. Hypertrophic astrocytes are commonly observed in cognitively healthy aged animals, implying a functional defense mechanism without losing neuronal support. In neurodegenerative diseases, astrocytes show morphological alterations, such as decreased process length and reduced number of branch points, known as astroglial atrophy, with detrimental effects on neuronal cells. The common marmoset (Callithrix jacchus) is a non-human primate that, with age, develops several features that resemble neurodegeneration. In this study, we characterize the morphological alterations in astrocytes of adolescent (mean 1.75 y), adult (mean 5.33 y), old (mean 11.25 y), and aged (mean 16.83 y) male marmosets. We observed a significantly reduced arborization in astrocytes of aged marmosets compared to younger animals in the hippocampus and entorhinal cortex. These astrocytes also show oxidative damage to RNA and increased nuclear plaques in the cortex and tau hyperphosphorylation (AT100). Astrocytes lacking S100A10 protein show a more severe atrophy and DNA fragmentation. Our results demonstrate the presence of atrophic astrocytes in the brains of aged marmosets.

The Possibility of IPC to Prevent Ischemic-Reperfusion Injury in Skeletal Muscle in a Rat.

Blood removal with air tourniquets for a long time induces muscle damage after reperfusion. Ischemic preconditioning (IPC) has a protective effect against ischemia-reperfusion injury in striated muscle and myocardium. However, the mechanism of action of IPC on skeletal muscle injury is unclear. Thus, this study aimed to investigate the effect of IPC in reducing skeletal muscle damage caused by ischemia-reperfusion injury. The hindlimbs of 6-month-old rats were wounded with air tourniquets at a carminative blood pressure of 300 mmHg on the thighs. Rats were divided into the IPC (-) group and the IPC (+) group. The vascular endothelial growth factor (VEGF), 8-hydroxyguanosine (8-OHdG), and cyclooxygenase 2 (COX-2) were investigated by protein levels. Quantitative analysis of apoptosis was performed using the TUNEL method. Compared with the IPC (-) group, the IPC (+) group retained the VEGF expression, and the COX-2 and 8-OHdG expressions were suppressed. The proportion of apoptosis cells decreased in the IPC (+) group compared with the IPC (-) group. IPC in skeletal muscles proliferated VEGF and suppressed inflammatory response and oxidative DNA damage. IPC has the potential to reduce muscle damage after ischemia-reperfusion.

The role of epigenetic and epitranscriptomic modifications in plants exposed to non-essential metals.

Contamination of the soil with non-essential metals and metalloids is a serious problem in many regions of the world. These non-essential metals and metalloids are toxic to all organisms impacting crop yields and human health. Crop plants exposed to high concentrations of these metals leads to perturbed mineral homeostasis, decreased photosynthesis efficiency, inhibited cell division, oxidative stress, genotoxic effects and subsequently hampered growth. Plants can activate epigenetic and epitranscriptomic mechanisms to maintain cellular and organism homeostasis. Epigenetic modifications include changes in the patterns of cytosine and adenine DNA base modifications, changes in cellular non-coding RNAs, and remodeling histone variants and covalent histone tail modifications. Some of these epigenetic changes have been shown to be long-lasting and may therefore contribute to stress memory and modulated stress tolerance in the progeny. In the emerging field of epitranscriptomics, defined as chemical, covalent modifications of ribonucleotides in cellular transcripts, epitranscriptomic modifications are postulated as more rapid modulators of gene expression. Although significant progress has been made in understanding the plant's epigenetic changes in response to biotic and abiotic stresses, a comprehensive review of the plant's epigenetic responses to metals is lacking. While the role of epitranscriptomics during plant developmental processes and stress responses are emerging, epitranscriptomic modifications in response to metals has not been reviewed. This article describes the impact of non-essential metals and metalloids (Cd, Pb, Hg, Al and As) on global and site-specific DNA methylation, histone tail modifications and epitranscriptomic modifications in plants.

Mitochondria Specific Antioxidant, MitoTEMPO, Modulates Cd Uptake and Oxidative Response of Soybean Seedlings.

Numerous reports find that Cd induces formation of reactive oxygen species (ROS) in plants. However, a general ROS pool is usually studied, without distinction of their production site. In the present study, we applied a mitochondria-specific antioxidant, MitoTEMPO, to elucidate the role of mitochondria-derived ROS in the response of soybean seedlings to short-term (48 h) Cd stress. The obtained results showed that Cd caused a reduction in root length and fresh weight and increase in the level of superoxide anion, hydrogen peroxide, markers of lipid peroxidation (thiobarbituric reactive substances, TBARS) and markers of RNA oxidation (8-hydroxyguanosine, 8-OHG) in seedling roots. Application of MitoTEMPO affected Cd uptake in a dose-dependent manner and diminished the Cd-dependent induction of superoxide anion and lipid peroxidation.

A multi-omics study to boost continuous bolaform sophorolipid production.

Biodegradable and biobased surface active agents are renewable and environmentally friendly alternatives to petroleum derived or oleochemical surfactants. However, they are accompanied by relatively high production costs. In this study, the aim was to reduce the production costs for an innovative type of microbial biosurfactant: bolaform sophorolipids, produced by the yeast Starmerella bombicola ΔsbleΔat. A novel continuous retentostat set-up was performed whereby continuous broth microfiltration retained the biomass in the bioreactor while performing an in situ product separation of bolaform sophorolipids. Although a mean volumetric productivity of 0.56 g L-1 h-1 was achieved, it was not possible to maintain this productivity, which collapsed to almost 0 g L-1 h-1. Therefore, two process adaptations were evaluated, a sequential batch strategy and a phosphate limitation alleviation strategy. The sequential batch set-up restored the mean volumetric productivity to 0.66 g L-1 h-1 for an additional 132 h but was again followed by a productivity decline. A similar result was obtained with the phosphate limitation alleviation strategy where a mean volumetric productivity of 0.54 g L-1 h-1 was reached, but a productivity decline was also observed. Whole genome variant analysis uncovered no evidence for genomic variations for up to 1306 h of retentostat cultivation. Untargeted metabolomics analysis identified 8-hydroxyguanosine, a biomarker for oxidative RNA damage, as a key metabolite correlating with high bolaform sophorolipid productivity. This study showcases the application of a retentostat to increase bolaform sophorolipid productivity and lays the basis of a multi-omics platform for in depth investigation of microbial biosurfactant production with S. bombicola.

Oxidative RNA Modifications as an Early Response of Soybean (Glycine max L.) Exposed to Copper and Lead.

Plant exposure to metals is associated with the accumulation of reactive oxygen species, which mediate the oxidation of various molecules including lipids, proteins, and nucleic acids. The aim of the present study is the evaluation of the impact of short-term Cu and Pb treatment on oxidative events in the roots of soybean seedlings, with special emphasis on RNA oxidation. The results show that an increase in total RNA oxidative modification, 8-hydroxyguanosine (8-OHG), constitutes a very early response to both applied metals, observed already within the first hour of treatment. Exposure to Cu and Pb resulted also in the increase in superoxide anion and hydrogen peroxide levels and intensified lipid peroxidation. However, these responses were most prominent after longer treatment times. On the other hand, no changes were observed in the level of protein carbonylation. It can be concluded that 8-OHG enrichment in total RNA constitutes one of the earliest reactions to metals, which precedes the symptoms of oxidative stress.

Urinary concentrations of acetaminophen in young children in central and south China: Repeated measurements and associations with 8-hydroxy-guanosine and 8-hydroxy-2'-deoxyguanosine.

Acetaminophen (AAP) is the most widely used over-the-counter analgesic in the world; it is also a metabolite of industrial chemical aniline. It may predispose individuals to oxidative stress. However, the exposure profile of AAP in the general population in China and the associations between AAP and oxidative stress biomarkers have scarcely been investigated. In this study, we determined the urinary concentrations of AAP and evaluated its associations with 8-hydroxy-guanosine (8-OHG) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), the most widely used biomarkers of nucleoside oxidation affecting RNA and DNA, in 393 urine samples collected from 131 healthy children (0-6.6 y) on three consecutive days from Wuhan, central China, and Shenzhen, south China. AAP was found in all urine samples, suggesting that exposure to AAP was ubiquitous in young children in central and south China. The median concentration of specific gravity (SG)-adjusted AAP was 9.21 ng/mL (range: 1.11-1 453 ng/mL). Good inter-day reproducibility was observed for SG-adjusted AAP concentrations (intraclass correlation coefficient, 0.75). The SG-adjusted urinary 8-OHdG and 8-OHG concentrations were positively correlated with AAP (ß = 0.08; 95% confidence interval [95% CI]: 0.02-0.13, and ß = 0.10; 95% CI: 0.04-0.15, respectively). The data indicated that AAP exposure might be associated with oxidative DNA and RNA damage in the general population with unintentional exposure. To our knowledge, this is the first report of AAP exposure in young healthy children in central and south China. This is also the first study to evaluate the inter-day variations in urinary AAP concentrations and to explore the associations between AAP exposure and oxidative stress biomarkers in the general population.

8-Hydroxyguanosine as a possible RNA oxidative modification marker in urine from colorectal cancer patients: Evaluation by ultra performance liquid chromatography-tandem mass spectrometry.

Oxidative RNA damage has been found to be associated with a variety of diseases, and 8-hydroxyguanosine (8-OHG) is a typical marker of oxidative modification of RNA. This guanosine modification is an emerging biomarker for disease detection and determination of 8-OHG in human urine is favored because it is noninvasive to patients. However, due to its poor ionization efficiency in mass spectrometry and trace amount in urine, accurate quantification of this modified nucleoside is still challenging. Herein, a rapid, accurate, sensitive and robust method using solid-phase extraction (SPE) combined with isotope dilution ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed for detection of this oxidative RNA modification in human urine. The limit of detection can reach 1.5 fmol and the method exhibits good precision on intra-day (1.8-3.3%) and inter-day (0.6-1.2%) analyses. Satisfactory recovery (87.5-107.2%) at three spiked levels was achieved by using HLB cartridge for urine pretreatment. Using this method, we quantified 8-OHG in urine from 65 colorectal cancer (CRC) patients and 76 healthy volunteers. The measured level of urinary 8-OHG for CRC patients and healthy controls is 1.91 ± 0.63 nmol/mmol creatinine and 1.33 ± 0.35 nmol/mmol creatinine, respectively. We found the content of 8-OHG in urine was raised in CRC patients patients, implying this oxidative RNA modification marker could act as a potential noninvasive indicator for early screening of CRC. In addition, this study will make contributions to the investigations of the influences of oxidative stress on the formation and development of CRC.

Recent Advances: Molecular Mechanism of RNA Oxidation and Its Role in Various Diseases.

Compared with the research on DNA damage, there are fewer studies on RNA damage, and the damage mechanism remains mostly unknown. Recent studies have shown that RNA is more vulnerable to damage than DNA when the cells are exposed to endogenous and exogenous insults. RNA injury may participate in a variety of disease occurrence and development. RNA not only has important catalytic functions and other housekeeping functions, it also plays a decisive role in the translation of genetic information and protein biosynthesis. Various kinds of stressors, such as ultraviolet, reactive oxygen species and nitrogen, can cause damage to RNA. It may involve in the development and progression of diseases. In this review, we focused on the relationship between the RNA damage and disease as well as the research progress on the mechanism of RNA damage, which is of great significance for the pathogenesis, diagnosis, and treatment of related diseases.

The Exacerbation of Aging and Oxidative Stress in the Epididymis of Sod1 Null Mice.

There is growing evidence that the quality of spermatozoa decreases with age and that children of older fathers have a higher incidence of birth defects and genetic mutations. The free radical theory of aging proposes that changes with aging are due to the accumulation of damage induced by exposure to excess reactive oxygen species. We showed previously that absence of the superoxide dismutase 1 (Sod1) antioxidant gene results in impaired mechanisms of repairing DNA damage in the testis in young Sod1-/- mice. In this study, we examined the effects of aging and the Sod-/- mutation on mice epididymal histology and the expression of markers of oxidative damage. We found that both oxidative nucleic acid damage (via 8-hydroxyguanosine) and lipid peroxidation (via 4-hydroxynonenal) increased with age and in Sod1-/- mice. These findings indicate that lack of SOD1 results in an exacerbation of the oxidative damage accumulation-related aging phenotype.

The mechanism of RNA oxidation involved in the development of heart failure.

Heart failure (HF) has become a global public health problem due to its unclear pathogenesis. Our previous studies have found that RNA oxidation is associated with the occurrence and development of a variety of chronic diseases in the elderly, but whether RNA oxidation is related to the pathogenesis of HF remains unclear. Male Dahl salt-sensitive rats (DSSR) were divided into 8% NaCl groups and 0.3% NaCl groups. The blood pressure of DSSR, HE staining of cardiac tissue, cardiac function index of colour Doppler echocardiography and plasma N-terminal probrain Natriuretic Peptide (NT-ProBNP) were used to evaluate the model making. The levels of 8-hydroxyguanosine (8-oxoGsn) and 8-hydroxydeoxyguanosine (8-oxodGsn) in myocardium and urine of DSSR were determined by high-performance liquid chromatography-mass spectrometry (LC-MS/MS). The expression of ERK-MAPK pathway and MTH1 was detected by Western blot (WB). Rats in the 8% NaCl group developed heart failure symptoms such as increased blood pressure, myocardial hypertrophy, decreased diastolic function, and increased plasma NT-ProBNP. The content of 8-oxoGsn in urine and heart tissue also increased, which was positively correlated with the related indicators of heart failure. This process is also accompanied by the sequential activation of ERK-MAPK pathway molecules and the increase of MTH1. The mechanism of RNA oxidation and inhibition is related to the occurrence and development of HF, which may be involved through ERK-MAPK pathway.

Paricalcitol accelerates BACE1 lysosomal degradation and inhibits calpain-1 dependent neuronal loss in APP/PS1 transgenic mice.

BACKGROUND: Recent studies have revealed that vitamin D deficiency may increase the risk of Alzheimer's disease, and vitamin D supplementation may be effective strategy to ameliorate the neurodegenerative process in Alzheimer's disease patients. Paricalcitol (PAL), a low-calcemic vitamin D receptor agonist, is clinically used to treat secondary hyperparathyroidism. However, the potential application of PAL for treating neurodegenerative disorders remains unexplored. METHODS: The APP/PS1 mice were intraperitoneally injected with PAL or vehicle every other day for 15 weeks. The ß-amyloid (Aß) production was confirmed using immunostaining and enzyme linked immunosorbent assay. The underlying mechanism was verified by western blot and immunostaining in vivo and in vitro. FINDINGS: Long-term PAL treatment clearly reduced ß-amyloid (Aß) generation and neuronal loss in APP/PS1 transgenic mouse brains. PAL stimulated the expression of low-density lipoprotein receptor-related protein 1 (LRP1) possibly through inhibiting sterol regulatory element binding protein-2 (SREBP2); PAL also promoted LRP1-mediated ß-site APP cleavage enzyme 1 (BACE1) transport to late endosomes, thus increasing the lysosomal degradation of BACE1. Furthermore, PAL diminished 8-hydroxyguanosine (8-OHdG) generation in neuronal mitochondria via enhancing base excision repair (BER), resulting in the attenuation of calpain-1-mediated neuronal loss. INTERPRETATION: The present data demonstrate that PAL can reduce Aß generation through accelerating BACE1 lysosomal degradation and can inhibit neuronal loss through suppressing mitochondrial 8-OHdG generation. Hence, PAL might be a promising agent for treating Alzheimer's disease. FUND: This study was financially supported by the Natural Science Foundation of China (U1608282).