Copper-caused oxidative stress triggers the activation of antioxidant enzymes via ZmMPK3 in maize leaves.

Copper (Cu) is a necessary trace element participated in many physiological processes in plants. But excessive Cu2+ is toxic, which can activate intracellular signals that lead to cellular damage. The mitogen-activated protein kinase (MAPK) cascade is at the center of cell signal transduction and has been reported to be involved in stress-related signaling pathways. ZmMPK3, a kind of MAPKs in maize cells, can be activated by diverse abiotic stresses. In the present study, we investigated the effects of Cu2+ on hydrogen peroxide (H2O2) level, ZmMPK3 activity as well as the activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and ascorbic acid peroxidase (APX) using maize leaf as an experimental model. The results demonstrated that acute Cu2+ exposure for 24 hours led to rapid increases of H2O2 level and the increase in ZmMPK3 activity as well as the total activities of antioxidant enzymes SOD, CAT and APX. H2O2 scavenger, dimethylthiourea (DMTU), effectively inhibited the Cu2+-increased H2O2 level and the activity of ZmMPK3 as well as the activities of the antioxidant enzymes SOD, CAT and APX. Pre-treatment with the MAPK inhibitor, PD98059, significantly blocked the Cu2+-increased activities of ZmMPK3, CAT, APX and SOD, but didn't affect the accumulation of H2O2. Our results suggest that Cu2+ causes oxidative stress to the maize leaves which then activates defense antioxidant enzymes via MAPK pathway. Thus, the signaling pathway is Cu2+-H2O2-ZmMPK3-antioxidant enzymes.

Type 2 Diabetes Promotes Cell Centrosome Amplification via AKT-ROS-Dependent Signalling of ROCK1 and 14-3-3σ.

BACKGROUND/AIMS: Type 2 diabetes is associated with oxidative stress and DNA damage which can cause centrosome amplification. Thus, the study investigated centrosome amplification in type 2 diabetes and the underlying mechanisms. METHODS: Centrosome numbers in human peripheral blood mononuclear blood cells (PBMC) from healthy subjects and patients with type 2 diabetes were compared to access the association between type 2 diabetes and centrosome amplification. Colon cancer cells were used to investigate the molecular mechanisms underlying the centrosome amplification triggered by high glucose, insulin and palmitic acid. Western blot analysis was used to quantify the level of protein and protein phosphorylation. Immunofluorescent staining was performed to detect centrosomes. ROS was quantified using flow cytometry technique. Transcriptpmic profiling was performed using Illumina HiSeqTM500 platform. RESULTS: We found that centrosome amplification was increased PBMC from the type 2 diabetic patients, which correlated with the levels of fasting blood glucose and HbA1c. High glucose, insulin and palmitic acid, alone or in combinations, induced ROS production and centrosome amplification. Together, they increased AKT activation as well as the expression, binding and centrosome translation of ROCK1 and 14-3-3σ. Results from further analyses showed that AKT-ROS-dependent upregulations of expression, binding and centrosome translocation of ROCK1 and 14-3-3σ was the molecular pathway underlying the centrosome amplification in vitro triggered by high glucose, insulin and palmitic acid. Moreover, the key in vitro molecular signalling events activated by high glucose, insulin and palmitic acid were verified in PBMC from the patients with type 2 diabetes. CONCLUSION: Our results show that type 2 diabetes promotes cell centrosome amplification, and suggest that the diabetic pathophysiological factors-activated AKT-ROS-dependent signalling of ROCK1 and 14-3-3σ is the underlying molecular mechanism.

Effects of cadmium on oxidative stress activities in plasma of freshwater turtle Chinemys reevesii.

Cadmium (Cd) has been recently found in high concentrations in the aquatic environment. This study was designed to examine the effects of Cd on the oxidative stress activities in plasma of freshwater turtle Chinemys reevesii. Experimental turtles were exposed to Cd at the concentration of 15 mg/kg by intraperitoneal injection, and redox status was investigated. Compared to the controls, superoxide dismutase (SOD) and catalase activities in plasma of the treated animals significantly decreased in week 1, week 2, and week 4. However, SOD activities gradually increased from week 4 to week 8. The treated animals had higher content of MDA and lower content of GSH in plasma over the observation period. In conclusion, our results showed that Cd decreased the antioxidant capacity and increased the level of oxidative damage product in plasma, which suggest that Cd causes oxidative stress and damage in the animal under the experimental conditions.

Biogenic selenium and its hepatoprotective activity.

Elemental selenium nanoparticles (SeNPs) have multiple biological activities. In this study, we investigated the protective effects of biogenic SeNPs (BioSeNPs) on CCl4-induced liver damage in mice. The results showed that: (i) when compared to sodium selenite (SS), BioSeNPs has a similar tissue distribution after intragastrical administration to mice; (ii) BioSeNPs and SS showed comparable efficacy in increasing the activities of glutathione peroxidase and thioredoxin reductase in liver cell lines, mice blood and liver; (iii) pretreatment with BioSeNPs inhibiting the elevation of activities of various enzymes significantly which included aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase and liver lipid peroxide (p < 0.05 or p < 0.01) in CCl4-treated mice; (iv) activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) were significantly increased (p < 0.05 or p < 0.01) after a pretreatment with BioSeNPs in CCl4-treated mice; (v) histopathological damages in the liver from CCl4-treated mice were ameliorated by a pretreatment with BioSeNPs. In conclusion, these results have shown that BioSeNPs is able to protect the liver from CCl4-induced hepatic damage via increasing the antioxidant capacity and inhibiting oxidative damage. BioSeNPs may have the potential to be used as a trace element food supplement inducing antioxidant bioactivities.

Identification of a novel toll gene (Shtoll3) from the freshwater crab Sinopotamon henanense and its expression pattern changes in response to cadmium followed by Aeromonas hydrophila infection.

Toll signaling is essential for expression of immune genes which are important for defense against bacterial, fungal and viral infections in invertebrates. Although several toll genes have been identified in the crustaceans, none of them has been investigated in freshwater crab Sinopotamon henanense. Moreover, the effect of cadmium (Cd) on toll gene expression has never been examined on the freshwater crabs which live in the sediments and are prone to heavy metal bioaccumulation. Our transcriptomic analysis of hepatopancreas tissue reveals that toll3 gene expression has been decreased when treated with Cd. In this study, we cloned one toll gene (hereby designated Shtoll3) from the crab. The full-length cDNA of Shtoll3 was 4488 bp, with an ORF of 3693 bp encoding a putative protein of 1230 amino acids, a 5'-untranslated region of 414 bp and a 3'-untranslated region of 781 bp. Phylogenetic analysis showed that ShToll3 was clustered into the group of DmToll8. The tissue distribution results showed that Shtoll3 was expressed widely in different tissues, with the highest in gills, and the lowest in hemocytes. Shtoll3 expression was down-regulated only in midguts after Aeromonas hydrophila infection. With Cd presence, Shtoll3 expression in response to A. hydrophila were up-regulated in midguts and gills, which was further confirmed by western blotting analysis. Moreover, the mRNA level of two antimicrobial peptides (AMPs) crustin and c-lys, which possibly responded to Cd and A. hydrophila stimulation through Shtoll3, were analysised. Thus, we conclude that Cd changes the susceptibility of Shtoll3 to A. hydrophila infection in gills and midguts. This suggest that Shtoll3 may contribute to the innate immune defense of S. henanense to A. hydrophila and Cd can modify the immune function in epithelium.

Cadmium induces histopathological injuries and ultrastructural changes in the liver of freshwater turtle (Chinemys reevesii).

The study investigated the histopathological and ultrastructural lesions of liver of freshwater turtle Chinemys reevesii exposed to Cadmium (Cd). The animals were exposed to 0 mg kg-1 (0.85% normal saline (NS)), 7.5 mg kg-1, 15 mg kg-1, 30 mg kg-1 Cd chloride separately by intraperitoneal injection. Liver samples were collected for examination of lesions under light and electronic microscopes. Results showed that liver tissues from Cd -treated animals presented various degrees of histopathological lesions. Liver cells showed swollen, degeneration and necrosis with dose-dependent manner. Under electronic microscope, nucleus, mitochondria and rough endoplasmic reticulum presented various degrees of lesions with dose-dependent manner. In conclusion, Cd has significant toxicity on liver tissue of the freshwater turtle, which occurs in a dose-dependent manner.

Levistolide A Induces Apoptosis via ROS-Mediated ER Stress Pathway in Colon Cancer Cells.

BACKGROUND/AIMS: Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. Levistolide A (LA), a natural compound isolated from the traditional Chinese herb Ligusticum chuanxiong Hort, is used for treating cancer. In this study, we investigated the anticancer effect of LA in HCT116 and its isogenic p53-/- colon cancer cells, as well as the underlying mechanisms. METHODS: MTT assay was used to evaluate the effect of LA on the viability of cancer cells. Apoptosis and reactive oxygen species (ROS) production by the cells were determined by flow cytometry. Protein expression was detected by western blotting. RESULTS: The results showed that LA inhibited viability and caused apoptosis of both wild-type and p53-/- HCT116 cells. LA was able to trigger production of ROS and endoplasmic reticulum (ER) stress. Inhibition of ROS using N-acetylcysteine abrogated LA-induced ER stress and apoptosis, as well as the reduction in cancer cell viability. CONCLUSION: Our results indicate that LA causes apoptosis of colon cancer cells via ROS-mediated ER stress pathway. It will be interesting to develop the natural compound for chemotherapy of cancers such as CRC.

Cadmium toxicokinetics in the freshwater turtle, Chinemys reevesii.

This study was designed to investigate the toxicokinetics of Cadmium (Cd) in Chinemys reevesii. The animals were exposed to 15 mg/kg Cd chloride by intraperitoneal injection, and the Cd absorption, distribution, and excretion in different organs were determined. The results showed that Cd absorption reached its peak in the blood at 3 h after treatment. The accumulation of Cd was the highest in the liver and the second highest in the pancreas. All other tissues also accumulated Cd, such as spleen, kidney, intestine, lung, stomach, heart, brain, muscle. A small amount of Cd was found in the faeces. The urine and bile had low concentrations of Cd. In conclusion, absorbance of Cd reaches its peak at 3 h in blood. The liver and pancreas are the major organs of Cd accumulation, and the major excretion route of Cd is through feaces.

Phenotypic heterogeneity and associations of two aldose reductase gene polymorphisms with nephropathy and retinopathy in type 2 diabetes.

OBJECTIVE: We investigated the phenotypic features of diabetic microvascular complications and their association with a (CA)(n) microsatellite and a C/T polymorphism at the 5' region of the aldose reductase gene (ALR2) in a consecutive cohort of 738 Chinese type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Of the entire patient cohort, 392 were free of diabetes complications, or uncomplicated, 159 had diabetic nephropathy, 66 had diabetic retinopathy, and 121 had both diabetic nephropathy and retinopathy. Nephropathy was defined as urinary albumin excretion rate (AER) >or=20 micro g/min and albumin-to-creatinine ratio >or=3.5 mg/mmol in two urine collections. Retinopathy was defined by the presence of hemorrhages, exudates, laser marks, and fibrous proliferation or by a history of vitrectomy. (CA)(n) and C/T polymorphisms were examined by PCR followed by capillary electrophoresis and digestion with BfaI, respectively. RESULTS: In the whole cohort, patients with diabetic retinopathy (n = 187) had higher blood pressure and lower BMI, while those with diabetic nephropathy (n = 280) had higher blood pressure, waist-to-hip ratio, and lipid profile than those without the respective complications. The z+6 carriers of the (CA)(n) polymorphism were less common in patients with diabetic retinopathy than those without diabetic retinopathy (n = 551) (4.3 vs. 9.3%, P = 0.04). The CT/TT carriers had a higher AER than the CC carriers (30.2 x/divided by 7.2 vs. 21.9 x/divided by 6.9 micro g/min, P = 0.03). Further subgroup analysis was performed after excluding uncomplicated patients with <5 years disease duration. The group with both diabetic nephropathy and retinopathy had higher frequencies of the z-2 allele (25.7 vs. 16.9%, P = 0.03) and T allele (26.4 vs. 18.5%, P = 0.04) and a lower frequency of the z+6 allele (1.7 vs. 5.5%, P = 0.054) than the uncomplicated group. Multiple logistic regression analysis confirmed that z-2 carrying (odds ratio 2.6, 95% CI 1.20-5.83, P = 0.02) and CT/TT genotypes (OR 2.5, 95% CI 1.19-5.19, P = 0.02) were independent predictors for both diabetic nephropathy and retinopathy. CONCLUSIONS: Chinese type 2 diabetic patients exhibited phenotypic differences in terms of risk factors for both diabetic nephropathy and diabetic retinopathy. Both the z-2 allele of (CA)(n) polymorphism and T allele of ALR2 were independently associated with severe diabetic microvascular complications.

Amylin evokes protein p20 phosphorylation and insulin resistance in rat skeletal muscle extensor digitorum longus.

In the present study, we investigate effect of amylin on the insulin sensitivity of rat skeletal muscle extensor digitorum longus (EDL) using in vitro intact muscle incubation in combination with metabolic radioactive labeling. The molecular basis of the amylin action was further examined using proteomic analysis. In particular, proteins of interest were characterized using an integrated microcharacterization procedure that involved in-gel trypsin digestion, organic solvent extraction, high performance liquid chromatography separation, microsequencing and microsequence analysis. We found that amylin significantly decreased the insulin-stimulated glucose incorporation into glycogen (p < 0.01) and produced a protein spot of approximately 20 ku in size. This amylin responsive protein (hereby designated as amylin responsive protein 1, APR1) was identified to be protein p20. Moreover, ARP1 spots on gels were found to consistently produce a corresponding radioactive spot on X-ray films in (32)Pi but not in (35)S-methionine labeling experiments. In conclusion, our results showed that in vitro amylin concomitantly evoked the production of ARP1 and caused insulin resistance in EDL muscle. It is suggested that protein p20 may be involved in amylin signal transduction and the appearance of ARP1 may be a step in a molecular pathway leading to the development of insulin resistance. ARP1 might therefore be a useful molecular marker for amylin action, insulin resistance and Type 2 diabetes.