Isoquercitrin attenuates the osteoclast-mediated bone loss in rheumatoid arthritis via the Nrf2/ROS/NF-κB pathway.

An excess of osteoclastogenesis significantly contributes to the development of rheumatoid arthritis (RA). Activation of the nuclear factor erythroid-2 related factor 2 (Nrf2) and nuclear factor kappa B (NF-κB) ligand (RANKL)-induced reactive oxygen species (ROS)-to-NF-κB signaling cascade are important mechanisms regulating osteoclastogenesis; however, whether Nrf2 is involved in RANKL-induced NF-κB activation is controversial. Isoquercitrin, a natural flavonoid compound, has been shown to have Nrf2-dependent antioxidant effects inprevious studies. We sought to verify whether isoquercitrin could modulate RANKL-induced NF-κB activation by activating Nrf2, thereby affecting osteoclastogenesis. Tartrate-resistant acid phosphatase staining, F-actin ring staining and resorption pit assay suggested that isoquercitrin significantly inhibited osteoclastogenesis and osteolytic function. Mitosox staining showed that RANKL-induced ROS generation was significantly inhibited by isoquercitrin from day 3 of the osteoclast differentiation cycle. Quantitative real-time PCR, Western blot, and immunofluorescence indicated that isoquercitrin activated the Nrf2 signaling pathway and inhibited NF-κB expression. And when we used the Nrf2-specific inhibitor ML385, the inhibition of NF-κB by isoquercitrin disappeared. Moreover, we found that Nrf2 is not uninvolved in RANKL-induced NF-κB activation and may be related to the timing of ROS regulation. When we limited isoquercitrin administration to 2 days, Nrf2 remained activated and the inhibition of NF-κB disappeared. In vivo experiments suggested that isoquercitrin attenuated RA modeling-induced bone loss. Overall, isoquercitrin-activated Nrf2 blocked the RANKL-induced ROS-to-NF-κB signaling cascade response, thereby inhibiting osteoclastogenesis and bone loss. These findings provide new ideas for the treatment of RA.

[Construction and evaluation of a gradient stress model of PC12 cells induced by corticosterone].

Objective: A gradient stress model of PC12 cells induced by corticosterone was established to provide a basis for the evaluation and regulation of cell stress. Methods: The effect of corticosterone on cell viability was observed by measuring PC12 cell viability at different concentrations of corticosterone (0~1 000 µmol/L) after different intervention times (8~48 h) to screen the cell models for optimal intervention conditions. Key stress indicators (MDA, SOD, NADH, LDH) were measured spectrophotometrically and microscopically to evaluate the models. Results: When the concentration of corticosterone was below 200 µmol/L and the intervention time was 12 h, the cell viability was below half inactivation rate, which could reduce the confounding factors due to the decrease of cell viability in each group. Compared with the blank control group, corticosterone increased the levels of MDA, NADH and LDH,and decreased the levels of SOD in the model group in a concentration-dependent manner (P＜0.01), which was consistent with the construction of the gradient stress model. Conclusion: A gradient stress injury model of PC12 cells was successfully established, with intervention concentrations of 0 µmol/L, 25 µmol/L, 50 µmol/L, 100 µmol/L, 150 µmol/L and 200 µmol/L corticosterone at an intervention time of 12 h. The degree of stress injury of the cell model was increased gradually, which could be used as a basis and object for conducting cell stress injury assessment and regulation experiments.

[Resveratrol attenuates cardiac function impairment in plateau hypobaric hypoxia rats].

Objective: To study the protective effects of resveratrol (RSV) on cardiac function in rats with high altitude hypobaric hypoxia and its mechanisms. Methods: Thirty-six rats were randomly divided into control group, hypobaric hypoxia group (HH) and hypobaric hypoxia + RSV group (HH+RSV) according to the random number, 12 rats in each group. Rats in the HH and HH+RSV groups were subjected to chronic long-term high altitude hypobaric hypoxia intervention for 8 weeks in a hypobaric chamber at a simulated altitude of 6 000 m for 20 h / d. The rats of HH + RSV were fed with RSV at a dose of 400 mg/(kg·d). The rats were tested once a week for body weight and twice a week for food intake. Before execution, the rats were tested by blood cell analyzer for routine blood parameters and echocardiogram for cardiac function parameters in each group. The routine blood indexes of each group were measured by blood cell analyzer, the cardiac function indexes of each group were measured by echocardiography, myocardial hypertrophy was evaluated by HE staining, myocardial tissue reactive oxygen levels were evaluated by dihydroethidium (DHE) staining. Oxidative stress was evaluated by serum and myocardial tissue total antioxidant capacity (T-AOC), superoxide dismutase activity (SOD) and malondialdehyde (MDA) content. Results: Compared with the C group, the body mass and food intake of rats were decreased significantly (P＜0.05) in HH group, while compared with the C group, RSV had no significant effects on the body mass and food intake of rats in the HH+RSV group (P＞0.05). Compared with the C group, the levels of erythrocytes and hemoglobin of rats in the HH group were increased significantly (P＜0.05), while the platelet concentration was decreased significantly(P＜0.05); compared with the HH group, the erythrocyte and hemoglobin levels were decreased significantly (P＜0.05) and platelet concentration was increased significantly(P＜0.05) in rats of the HH+RSV group. Compared with the C group, the cardiac coefficient, myocardial fiber diameter and thickness were significantly increased in the HH group (P＜0.05); compared with the HH group, the cardiac coefficient and myocardial fiber thickness were significantly decreased in the HH+RSV group (P＜0.05). Echocardiographic analysis showed a significant increase in ventricular wall thickness (P＜0.05) and a significant decrease in ejection fraction and cardiac output (P＜0.05) in the HH group compared with the C group, and a significant decrease in ventricular wall thickness and a significant improvement in cardiac function (P＜0.05) in the HH+RSV group compared with the HH group. The results of DHE staining showed that myocardial tissue reactive oxygen levels were increased significantly in the HH group compared with the C group (P＜0.05); myocardial tissue reactive oxygen levels were significantly restored in the HH+RSV group compared with the HH group (P＜0.05). The oxidative/antioxidant results showed that the serum and myocardial T-AOC and SOD activities were decreased significantly (P＜0.05) and the MDA level was increased significantly (P＜0.05) in the HH group compared with the C group; the serum and myocardial T-AOC and SOD activities were increased significantly (P＜0.05) and the MDA level was decreased significantly(P＜0.05) in the HH+RSV group compared with the HH group. Conclusion: Long-term plateau hypobaric hypoxia exposure leads to myocardial hypertrophy and reduced cardiac function in rats. Resveratrol intervention significantly improves myocardial hypertrophy and cardiac function in rats caused by altitude hypobaric hypoxia exposure, which is closely related to reducing of reactive oxygen species and improving myocardial oxidative stress levels.

[Effects of MAPKs inhibitors on GSH metabolic enzymes in rat hepatocytes].

OBJECTIVE: To investigate the effects of mitogen-activated protein kinases (MAPKs) inhibitors on glutathione (GSH) metabolism, and to explore the pathway related to GSH metabolism. METHODS: BRL rat hepatocytes were treated by c-Jun NH2-terminal kinase (JNK),p38, and extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitors:SP600125, SB203580 and PD98659, respectively, for 24 h. MTT method was used to measure hepatocytes viability. The content of GSH was determined by high performance liquid chromatography. The protein expressions of JNK and phosphorylated JNK (p-JNK) was tested by Luminex method. Activities of GSH metabolic enzymes were detected by commercial kits. RESULTS: Hepatocytes vitality was inhibited when the concentrations of SP600125, SB203580 and PD98659 were higher than 10 µmol/L, 20 µmol/L, and 40 µmol/L, respectively; SP600125 decreased the content of GSH in hepatocytes, while SB203580 and PD98659 had no effect. SP600125 reduced p-JNK protein expression, and enhanced GSH-Px activity significantly. CONCLUSIONS: JNK MAPK pathway takes part in the GSH metabolism in hepatocytes.

A massive expansion of effector genes underlies gall-formation in the wheat pest Mayetiola destructor.

Gall-forming arthropods are highly specialized herbivores that, in combination with their hosts, produce extended phenotypes with unique morphologies [1]. Many are economically important, and others have improved our understanding of ecology and adaptive radiation [2]. However, the mechanisms that these arthropods use to induce plant galls are poorly understood. We sequenced the genome of the Hessian fly (Mayetiola destructor; Diptera: Cecidomyiidae), a plant parasitic gall midge and a pest of wheat (Triticum spp.), with the aim of identifying genic modifications that contribute to its plant-parasitic lifestyle. Among several adaptive modifications, we discovered an expansive reservoir of potential effector proteins. Nearly 5% of the 20,163 predicted gene models matched putative effector gene transcripts present in the M. destructor larval salivary gland. Another 466 putative effectors were discovered among the genes that have no sequence similarities in other organisms. The largest known arthropod gene family (family SSGP-71) was also discovered within the effector reservoir. SSGP-71 proteins lack sequence homologies to other proteins, but their structures resemble both ubiquitin E3 ligases in plants and E3-ligase-mimicking effectors in plant pathogenic bacteria. SSGP-71 proteins and wheat Skp proteins interact in vivo. Mutations in different SSGP-71 genes avoid the effector-triggered immunity that is directed by the wheat resistance genes H6 and H9. Results point to effectors as the agents responsible for arthropod-induced plant gall formation.

Comparative validation of the D. melanogaster modENCODE transcriptome annotation.

Accurate gene model annotation of reference genomes is critical for making them useful. The modENCODE project has improved the D. melanogaster genome annotation by using deep and diverse high-throughput data. Since transcriptional activity that has been evolutionarily conserved is likely to have an advantageous function, we have performed large-scale interspecific comparisons to increase confidence in predicted annotations. To support comparative genomics, we filled in divergence gaps in the Drosophila phylogeny by generating draft genomes for eight new species. For comparative transcriptome analysis, we generated mRNA expression profiles on 81 samples from multiple tissues and developmental stages of 15 Drosophila species, and we performed cap analysis of gene expression in D. melanogaster and D. pseudoobscura. We also describe conservation of four distinct core promoter structures composed of combinations of elements at three positions. Overall, each type of genomic feature shows a characteristic divergence rate relative to neutral models, highlighting the value of multispecies alignment in annotating a target genome that should prove useful in the annotation of other high priority genomes, especially human and other mammalian genomes that are rich in noncoding sequences. We report that the vast majority of elements in the annotation are evolutionarily conserved, indicating that the annotation will be an important springboard for functional genetic testing by the Drosophila community.

The Drosophila melanogaster Genetic Reference Panel.

A major challenge of biology is understanding the relationship between molecular genetic variation and variation in quantitative traits, including fitness. This relationship determines our ability to predict phenotypes from genotypes and to understand how evolutionary forces shape variation within and between species. Previous efforts to dissect the genotype-phenotype map were based on incomplete genotypic information. Here, we describe the Drosophila melanogaster Genetic Reference Panel (DGRP), a community resource for analysis of population genomics and quantitative traits. The DGRP consists of fully sequenced inbred lines derived from a natural population. Population genomic analyses reveal reduced polymorphism in centromeric autosomal regions and the X chromosome, evidence for positive and negative selection, and rapid evolution of the X chromosome. Many variants in novel genes, most at low frequency, are associated with quantitative traits and explain a large fraction of the phenotypic variance. The DGRP facilitates genotype-phenotype mapping using the power of Drosophila genetics.