Role of metallothionein and other antioxidants in scavenging superoxide radicals and their possible role in neuroprotection

Natural variation in WHITE-CORE RATE 1 regulates redox homeostasis in rice endosperm to affect grain quality

Grain chalkiness reduces the quality of rice (Oryza sativa) and is a highly undesirable trait for breeding and marketing. However, the underlying molecular cause of chalkiness remains largely unknown. Here, we cloned the F-box gene WHITE-CORE RATE 1 (WCR1), which negatively regulates grain chalkiness and improves grain quality in rice. A functional A/G variation in the promoter region of WCR1 generates the alleles WCR1A and WCR1G, which originated from tropical japonica and wild rice Oryza rufipogon, respectively. OsDOF17 is a transcriptional activator that binds to the AAAAG cis-element in the WCR1A promoter. WCR1 positively affects the transcription of the metallothionein gene MT2b and interacts with MT2b to inhibit its 26S proteasome-mediated degradation, leading to decreased reactive oxygen species production and delayed programmed cell death in rice endosperm. This, in turn, leads to reduced chalkiness. Our findings uncover a molecular mechanism underlying rice chalkiness and identify the promising natural variant WCR1A, with application potential for rice breeding.

Bioreduction and bioremoval of hexavalent chromium by genetically engineered strains (Escherichia coli MT2A and Escherichia coli MT3)

The number of studies on the removal of hazardous metals from water using genetic engineering technologies is growing. A high rate of metal ion removal from the environment is ensured, particularly through the expression of cysteine and thiol-rich proteins such as metallothioneins in bacterial cells. In this study, we used recombinant strains created by cloning the human metallothioneins MT2A and MT3 into Escherichia coli Jm109 to assess the removal and reduction of hexavalent chromium (Cr(VI)) from aqueous solutions. MT2A was the most effective strain in both Cr(VI) removal (89% in 25 mg/L Cr(VI)) and Cr(VI) reduction (76% in 25 mg/L Cr(VI)). The amount of Cr adsorbed per dry cell by the MT2A strain was 22 mg/g. The biosorption of total Cr was consistent with the Langmuir isotherm model. Scanning electron microscope (SEM) images revealed that the morphological structures of Cr(VI)-treated cells were significantly damaged when compared to control cells. Scanning transmission electron microscope (STEM) images showed black spots in the cytoplasm of cells treated with Cr(VI). Shifts in the Fourier transform infrared spectroscopy analysis (FTIR) spectra of the cells treated with Cr(VI) showed that the groups interacting with Cr were hydroxyl, amine, amide I, amide II, phosphoryl and carbonyl. When all of the experimental data was combined, it was determined that both MT2A and MT3 were effective in removing Cr(VI) from aqueous solutions, but MT2A was more effective, indicating that MT2A may be employed as a biotechnological tool.

Biochemical and Metabolic Plant Responses toward Polycyclic Aromatic Hydrocarbons and Heavy Metals Present in Atmospheric Pollution

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) are toxic components of atmospheric particles. These pollutants induce a wide variety of responses in plants, leading to tolerance or toxicity. Their effects on plants depend on many different environmental conditions, not only the type and concentration of contaminant, temperature or soil pH, but also on the physiological or genetic status of the plant. The main detoxification process in plants is the accumulation of the contaminant in vacuoles or cell walls. PAHs are normally transformed by enzymatic plant machinery prior to conjugation and immobilization; heavy metals are frequently chelated by some molecules, with glutathione, phytochelatins and metallothioneins being the main players in heavy metal detoxification. Besides these detoxification mechanisms, the presence of contaminants leads to the production of the reactive oxygen species (ROS) and the dynamic of ROS production and detoxification renders different outcomes in different scenarios, from cellular death to the induction of stress resistances. ROS responses have been extensively studied; the complexity of the ROS response and the subsequent cascade of effects on phytohormones and metabolic changes, which depend on local concentrations in different organelles and on the lifetime of each ROS species, allow the plant to modulate its responses to different environmental clues. Basic knowledge of plant responses toward pollutants is key to improving phytoremediation technologies.

The Roles of Dietary, Nutritional and Lifestyle Interventions in Adipose Tissue Adaptation and Obesity

The obesity and the associated non-communicable diseases (NCDs) are globally increasing in their prevalence. While the modern-day lifestyle required less ventilation of metabolic energy through muscular activities, this lifestyle transition also provided the unlimited accession to foods around the clock, which prolong the daily eating period of foods that contained high calorie and high glycemic load. These situations promote the high continuous flux of carbon substrate availability in mitochondria and induce the indecisive bioenergetic switches. The disrupted bioenergetic milieu increases the uncoupling respiration due to the excess flow of the substrate-derived reducing equivalents and reduces ubiquinones into the respiratory chain. The diversion of the uncoupling proton gradient through adipocyte thermogenesis will then alleviate the damaging effects of free radicals to mitochondria and other organelles. The adaptive induction of white adipose tissues (WAT) to beige adipose tissues (beAT) has shown beneficial effects on glucose oxidation, ROS protection and mitochondrial function preservation through the uncoupling protein 1 (UCP1)-independent thermogenesis of beAT. However, the maladaptive stage can eventually initiate with the persistent unhealthy lifestyles. Under this metabolic gridlock, the low oxygen and pro-inflammatory environments promote the adipose breakdown with sequential metabolic dysregulation, including insulin resistance, systemic inflammation and clinical NCDs progression. It is unlikely that a single intervention can reverse all these complex interactions. A comprehensive protocol that includes dietary, nutritional and all modifiable lifestyle interventions, can be the preferable choice to decelerate, stop, or reverse the NCDs pathophysiologic processes.

Glutathione in the Brain

Glutathione (GSH) is the most abundant non-protein thiol, and plays crucial roles in the antioxidant defense system and the maintenance of redox homeostasis in neurons. GSH depletion in the brain is a common finding in patients with neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease, and can cause neurodegeneration prior to disease onset. Excitatory amino acid carrier 1 (EAAC1), a sodium-dependent glutamate/cysteine transporter that is selectively present in neurons, plays a central role in the regulation of neuronal GSH production. The expression of EAAC1 is posttranslationally controlled by the glutamate transporter-associated protein 3–18 (GTRAP3-18) or miR-96-5p in neurons. The regulatory mechanism of neuronal GSH production mediated by EAAC1 may be a new target in therapeutic strategies for these neurodegenerative diseases. This review describes the regulatory mechanism of neuronal GSH production and its potential therapeutic application in the treatment of neurodegenerative diseases.

A metallothionein type 2 from Avicennia marina binds to iron and mediates hydrogen peroxide balance by activation of enzyme catalase

Metallothioneins (MTs) are low molecular weight, cysteine-rich, metal-binding proteins that are important for essential metal homeostasis, protection against oxidative stress, and buffering against toxic heavy metals. In this work the gene encoding an MT type 2 from Avicennia marina (Forssk.) Vierh. (AmMT2) was cloned into pET41a and transformed into the Escherichia coli strain Rosetta (DE3). Following the induction with isopropyl β-_D-1-thiogalactopyranoside, AmMT2 was expressed as glutathione-S-transferase (GST)-tagged fusion protein. The accumulation of Zn²⁺, Cu²⁺, Fe²⁺, Ni²⁺ and Cd²⁺ for strain R-AmMT2 was 4, 8, 5.4, 2 and 1.6 fold of control strain suggesting the role of AmMT2 in accumulation of metals. Particularly the strain R-AmMT2 was able to accumulate 30.7 mg per g dry weight. The cells expressing AmMT2 was more tolerant to hydrogen peroxide and had higher catalase (CAT) activity. To understand the mechanistic action of AmMT2 hydrogen peroxide tolerance, the activity of CAT in the E. coli protein extract was assayed after addition of pure Fe²⁺/GST-AmMT complex and Apo/GST-AmMT2 in vitro. Whereas, the activity of CAT did not change by the addition of Apo/GST-AmMT2, the activity of CAT significantly increased after addition of Fe²⁺/GST-AmMT2. These results show that AmMT2 activates CAT through Fe²⁺ transfer which subsequently causes the oxidative stress tolerance.

Photochemically stabilized formulation of dacarbazine with reduced production of algogenic photodegradants

The present study aimed to develop a photochemically stabilized formulation of dacarbazine [5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide; DTIC] for reducing the production of algogenic photodegradant (5-diazoimidazole-4-carboxamide; Diazo-IC). Photochemical properties of DTIC were characterized by UV-visible light spectral analysis, reactive oxygen species (ROS) assay, and photostability testing. A pharmacokinetic study was conducted after intravenous administration of DTIC formulations (1 mg-DTIC/kg) to rats. DTIC exhibited strong absorption in the UVA range, and photoirradiated DTIC exhibited marked ROS generation. Thus, DTIC had high photoreactive potential. After exposure of DTIC (1 mM) to simulated sunlight (250 W/m²) for 3 min, remaining DTIC and yielded Diazo-IC were estimated to be ca. 230 μM and 600 μM, respectively. The addition of radical scavenger (1 mM), including l-ascorbic acid, l-cysteine (Cys), l-histidine, D-mannitol, l-tryptophan, or l-tyrosine, to DTIC (1 mM) could attenuate DTIC photoreactions, and in particular, the addition of Cys to DTIC brought ca. 34% and 86% inhibition of DTIC photodegradation and Diazo-IC photogeneration, respectively. There were no significant differences in the calculated pharmacokinetic parameters of DTIC between DTIC and DTIC with Cys (0.67 mg/kg). From these findings, the supplementary use of Cys would be an effective approach to improve the photostability of DTIC with less production of Diazo-IC.

Probiotic potential of Bacillus velezensis JW: Antimicrobial activity against fish pathogenic bacteria and immune enhancement effects on Carassius auratus

This study evaluated the probiotic potential of B. velezensis JW through experimental and genomic analysis approaches. Strain JW showed antimicrobial activity against a broad range of fish pathogenic bacteria including Aeromonas hydrophila, Aeromonas salmonicida, Lactococcus garvieae, Streptococcus agalactiae, and Vibrio Parahemolyticus. Fish (Carassius auratus) were fed with the diets containing 0 (control), 10⁷, and 10⁹ cfu/g of B. velezensis JW for 4 weeks. Various immune parameters were examined at 1, 2, 3, and 4 weeks of post-feeding. Results showed that JW supplemented diets significantly increased acid phosphatase (ACP), alkaline phosphatase (AKP), and glutathione peroxidase (GSH-PX) activity. The mRNA expression of immune-related genes in the head kidney of C. auratus was measured. Among them, the interferon gamma gene (IFN- γ) and tumor necrosis factor-α (TNF-α) showed higher expression after 3 and 4 weeks of feeding (P < 0.05). The expression of interleukin-1 (IL-1) only being significantly upregulated by 10⁹ cfu/g of JW after 1 week of feeding (P < 0.05). The upregulation of interleukin-4 (IL-4) increased over time from 1st to 4th week. The expression of interleukin-10 (IL-10) and interleukin-12 (IL-12) showed an opposite expression pattern with IL-10 significantly upregulated and IL-12 significantly downregulated by JW containing diets at 2, 3, and 4 weeks of post-feeding (P < 0.05). Moreover, fish fed with JW supplemented diets showed significantly improved survival rate after A. hydrophila infection. The analysis of the genome of JW revealed several features aiding host health and being relevant to the GIT adaptation. Four bacteriocins, three Polyketide Synthetase (PKS), and five Nonribosomal Peptide-Synthetase (NRPS) gene clusters were identified in the genome. In summary, the above results clearly proved that B. velezensis JW has the potential to be developed as a probiotic agent in aquaculture.

Effects of glutathione on the survival, growth performance and non-specific immunity of white shrimps (Litopenaeus vannamei)

Reduced glutathione (GSH) is the most abundant non-enzymatic antioxidant present in mammalian cells and the main intracellular defence mechanism against oxidative stress. This study investigated the effects of GSH on survival rate, mean body gain weight, feed efficiency (FE), phenoloxidase (PO) activity, superoxide dismutase (SOD) activity, acid phosphatase (ACP), alkaline phosphatase (AKP) activity, GSH peroxidase (GPx) and susceptibility to Vibrio alginolyticus when Pacific white shrimps (Litopenaeus vannamei) were fed with GSH-containing diets. GSH was added to diets at 0.10, 0.20 and 0.30 g/kg during the eight-week breeding experiment. Oral administration of GSH had significantly increased mean body weight gain, FE, PO activity, SOD activity, ACP activity, AKP activity, GPx activity and susceptibility to V. alginolyticus compared with those of the control group (p < .05). Results indicate that GSH exerts both growth-promoting and immunostimulatory effects on Pacific white shrimps (L. vannamei).

The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline

Neurodegeneration, the progressive death of neurons, loss of brain function, and cognitive decline is an increasing problem for senior populations. Its causes are poorly understood and therapies are largely ineffective. Neurons, with high energy and oxygen requirements, are especially vulnerable to detrimental factors, including age-related dysregulation of biochemical pathways caused by altered expression of multiple genes. GHK (glycyl-l-histidyl-l-lysine) is a human copper-binding peptide with biological actions that appear to counter aging-associated diseases and conditions. GHK, which declines with age, has health promoting effects on many tissues such as chondrocytes, liver cells and human fibroblasts, improves wound healing and tissue regeneration (skin, hair follicles, stomach and intestinal linings, boney tissue), increases collagen, decorin, angiogenesis, and nerve outgrowth, possesses anti-oxidant, anti-inflammatory, anti-pain and anti-anxiety effects, increases cellular stemness and the secretion of trophic factors by mesenchymal stem cells. Studies using the Broad Institute Connectivity Map show that GHK peptide modulates expression of multiple genes, resetting pathological gene expression patterns back to health. GHK has been recommended as a treatment for metastatic cancer, Chronic Obstructive Lung Disease, inflammation, acute lung injury, activating stem cells, pain, and anxiety. Here, we present GHK's effects on gene expression relevant to the nervous system health and function.

Immunomodulation of cell-penetrating tat-metallothionein for successful outcome of xenotransplanted pancreatic islet

Pancreatic islet transplantation is a promising treatment for treatment of type 1 diabetes; however, transplantation outcomes have been disappointing due to early graft loss that is mediated by many immune responses. Immune cells not only directly damaged islet but also produced reactive oxygen species (ROS), which is highly toxic to islet cells. Metallothionein (MT) can provide protection against oxidative stress by scavenging various ranges of ROS including superoxide, hydroxyl radical, hydrogen peroxide and nitric oxide. For scavenging immune response-induced ROS, cell-penetrating Tat peptide-metallothionein (Tat-MT) was delivered into islets. The viability of Tat-MT-treated islets was not damaged during co-culture with macrophages or ROS-generating paraquat. When Tat-MT-treated islets were xenotransplanted, ROS production was significantly attenuated at the islets. Eventually, the survival time of Tat-MT-treated islets was significantly enhanced without any immunosuppressant medicine. Additionally, we confirmed that the survival time of Tat-MT-treated islets in all animals was dramatically improved when accompanied with low dose immunosuppressive agents (tacrolimus and anti-CD154 monoclonal antibody), indicating that Tat-MT delivery could have synergistic effect with immunosuppressants. Collectively, this new combination therapy of Tat-MT delivery with low dose immunosuppressant would be a powerful remedy for successful outcome of islet xenotransplantation.

Serotonin 1A Receptors on Astrocytes as a Potential Target for the Treatment of Parkinson's Disease

Astrocytes are the most abundant neuron-supporting glial cells in the central nervous system. The neuroprotective role of astrocytes has been demonstrated in various neurological disorders such as amyotrophic lateral sclerosis, spinal cord injury, stroke and Parkinson’s disease (PD). Astrocyte dysfunction or loss-of-astrocytes increases the susceptibility of neurons to cell death, while astrocyte transplantation in animal studies has therapeutic advantage. We reported recently that stimulation of serotonin 1A (5-HT_1A) receptors on astrocytes promoted astrocyte proliferation and upregulated antioxidative molecules to act as a neuroprotectant in parkinsonian mice. PD is a progressive neurodegenerative disease with motor symptoms such as tremor, bradykinesia, rigidity and postural instability, that are based on selective loss of nigrostriatal dopaminergic neurons, and with non-motor symptoms such as orthostatic hypotension and constipation based on peripheral neurodegeneration. Although dopaminergic therapy for managing the motor disability associated with PD is being assessed at present, the main challenge remains the development of neuroprotective or disease-modifying treatments. Therefore, it is desirable to find treatments that can reduce the progression of dopaminergic cell death. In this article, we summarize first the neuroprotective properties of astrocytes targeting certain molecules related to PD. Next, we review neuroprotective effects induced by stimulation of 5-HT_1A receptors on astrocytes. The review discusses new promising therapeutic strategies based on neuroprotection against oxidative stress and prevention of dopaminergic neurodegeneration.

Metallothionein regulates intracellular zinc signaling during CD4(+) T cell activation

BACKGROUND

The ultra-low redox potential and zinc binding properties of the intracellular pool of mammalian metallothioneins (MT) suggest a role for MT in the transduction of redox signals into intracellular zinc signals. Increased expression of MT after exposure to heavy metals, oxidative stress, or inflammatory cytokines leads to an increased intracellular redox-mobilizable zinc pool that can affect downstream zinc-sensitive signaling pathways. CD4(+) T helper cells are poised to be influenced by MT transduced zinc signaling because they produce intracellular reactive oxygen species following activation through the T cell receptor and are sensitive to small changes in intracellular [Zn(2+)].

RESULTS

MT expression and intracellular [Zn(2+)] are both increased during primary activation and expansion of naïve CD4(+) T cells into the Tr1 phenotype in vitro. When Tr1 cells from wildtype mice are compared with congenic mice lacking functional Mt1 and Mt2 genes, the expression of intracellular MT is associated with a greater increase in intracellular [Zn(2+)] immediately following exposure to reactive oxygen species or upon restimulation through the T cell receptor. The release of Zn(2+) from MT is associated with a greater increase in p38 MAPK activation following restimulation and decreased p38 MAPK activation in MT knockout Tr1 cells can be rescued by increasing intracellular [Zn(2+)]. Additionally, IL-10 secretion is increased in MT knockout Tr1 cells compared with wildtype controls and this increase is prevented when the intracellular [Zn(2+)] is increased experimentally.

CONCLUSIONS

Differences in zinc signaling associated with MT expression appear to be a result of preferential oxidation of MT and concomitant release of Zn(2+). Although zinc is released from many proteins following oxidation, release is greater when the cell contains an intracellular pool of MT. By expressing MT in response to certain environmental conditions, CD4(+) T cells are able to more efficiently release intracellular zinc and regulate signaling pathways following stimulation. The link between MT expression and increased zinc signaling following activation represents an important immunomodulatory mechanism of MT and illuminates the complex role MT plays in shaping immune responses.

Withanolide A prevents neurodegeneration by modulating hippocampal glutathione biosynthesis during hypoxia

Withania somnifera root extract has been used traditionally in ayurvedic system of medicine as a memory enhancer. Present study explores the ameliorative effect of withanolide A, a major component of withania root extract and its molecular mechanism against hypoxia induced memory impairment. Withanolide A was administered to male Sprague Dawley rats before a period of 21 days pre-exposure and during 07 days of exposure to a simulated altitude of 25,000 ft. Glutathione level and glutathione dependent free radicals scavenging enzyme system, ATP, NADPH level, γ-glutamylcysteinyl ligase (GCLC) activity and oxidative stress markers were assessed in the hippocampus. Expression of apoptotic marker caspase 3 in hippocampus was investigated by immunohistochemistry. Transcriptional alteration and expression of GCLC and Nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2) were investigated by real time PCR and immunoblotting respectively. Exposure to hypobaric hypoxia decreased reduced glutathione (GSH) level and impaired reduced gluatathione dependent free radical scavenging system in hippocampus resulting in elevated oxidative stress. Supplementation of withanolide A during hypoxic exposure increased GSH level, augmented GSH dependent free radicals scavenging system and decreased the number of caspase and hoescht positive cells in hippocampus. While withanolide A reversed hypoxia mediated neurodegeneration, administration of buthionine sulfoximine along with withanolide A blunted its neuroprotective effects. Exogenous administration of corticosterone suppressed Nrf2 and GCLC expression whereas inhibition of corticosterone synthesis upregulated Nrf2 as well as GCLC. Thus present study infers that withanolide A reduces neurodegeneration by restoring hypoxia induced glutathione depletion in hippocampus. Further, Withanolide A increases glutathione biosynthesis in neuronal cells by upregulating GCLC level through Nrf2 pathway in a corticosterone dependenet manner.

GHK and DNA: resetting the human genome to health

During human aging there is an increase in the activity of inflammatory, cancer promoting, and tissue destructive genes plus a decrease in the activity of regenerative and reparative genes. The human blood tripeptide GHK possesses many positive effects but declines with age. It improves wound healing and tissue regeneration (skin, hair follicles, stomach and intestinal linings, and boney tissue), increases collagen and glycosaminoglycans, stimulates synthesis of decorin, increases angiogenesis, and nerve outgrowth, possesses antioxidant and anti-inflammatory effects, and increases cellular stemness and the secretion of trophic factors by mesenchymal stem cells. Recently, GHK has been found to reset genes of diseased cells from patients with cancer or COPD to a more healthy state. Cancer cells reset their programmed cell death system while COPD patients' cells shut down tissue destructive genes and stimulate repair and remodeling activities. In this paper, we discuss GHK's effect on genes that suppress fibrinogen synthesis, the insulin/insulin-like system, and cancer growth plus activation of genes that increase the ubiquitin-proteasome system, DNA repair, antioxidant systems, and healing by the TGF beta superfamily. A variety of methods and dosages to effectively use GHK to reset genes to a healthier state are also discussed.

Characterization of the myometrial transcriptome in women with an arrest of dilatation during labor

OBJECTIVE

The molecular basis of failure to progress in labor is poorly understood. This study was undertaken to characterize the myometrial transcriptome of patients with an arrest of dilatation (AODIL).

STUDY DESIGN

Human myometrium was prospectively collected from women in the following groups: (1) spontaneous term labor (TL; n=29) and (2) arrest of dilatation (AODIL; n=14). Gene expression was characterized using Illumina® HumanHT-12 microarrays. A moderated Student's t-test and false discovery rate adjustment were used for analysis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) of selected genes was performed in an independent sample set. Pathway analysis was performed on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database using Pathway Analysis with Down-weighting of Overlapping Genes (PADOG). The MetaCore knowledge base was also searched for pathway analysis.

RESULTS

(1) Forty-two differentially expressed genes were identified in women with an AODIL; (2) gene ontology analysis indicated enrichment of biological processes, which included regulation of angiogenesis, response to hypoxia, inflammatory response, and chemokine-mediated signaling pathway. Enriched molecular functions included transcription repressor activity, heat shock protein (Hsp) 90 binding, and nitric oxide synthase (NOS) activity; (3) MetaCore analysis identified immune response chemokine (C-C motif) ligand 2 (CCL2) signaling, muscle contraction regulation of endothelial nitric oxide synthase (eNOS) activity in endothelial cells, and triiodothyronine and thyroxine signaling as significantly overrepresented (false discovery rate <0.05); (4) qRT-PCR confirmed the overexpression of Nitric oxide synthase 3 (NOS3); hypoxic ischemic factor 1A (HIF1A); Chemokine (C-C motif) ligand 2 (CCL2); angiopoietin-like 4 (ANGPTL4); ADAM metallopeptidase with thrombospondin type 1, motif 9 (ADAMTS9); G protein-coupled receptor 4 (GPR4); metallothionein 1A (MT1A); MT2A; and selectin E (SELE) in an AODIL.

CONCLUSION

The myometrium of women with AODIL has a stereotypic transcriptome profile. This disorder has been associated with a pattern of gene expression involved in muscle contraction, an inflammatory response, and hypoxia. This is the first comprehensive and unbiased examination of the molecular basis of an AODIL.

Toxicological profile of small airway epithelial cells exposed to gold nanoparticles

Gold nanoparticles (AuNPs) have diverse applications in the biomedical industry such as in diagnosis, labeling, delivering and sensing. Despite their prevalent medical use, nanotoxicity induced by AuNPs is still largely unknown. We have previously shown that AuNPs could exert cytotoxic effects on lung fibroblasts. In this study, we investigated the in vitro toxicological effects of AuNPs in small airway epithelial cells (SAECs) which are the first cells of contact for inhaled NPs and compared expression of metallothionein (MT), a reactive oxygen species scavenger, in SAECs and lung fibroblasts in vitro. Transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy study revealed cellular uptake of aggregates of AuNPs into the cytoplasm at the ultrastructural level. A significant increase in lipid peroxide as well as substantial DNA damage and cytotoxicity was observed in AuNP-treated cells. For MT expression, AuNPs induced down-regulation of the MT-1X isoform in SAECs, but up-regulation of the MT-1X and MT-2 A isoforms in MRC5 lung fibroblasts. The present study suggests that AuNPs could induce oxidative stress-related cytotoxicity and genotoxicity in SAECs.

Genome-wide identification of rice class I metallothionein gene: tissue expression patterns and induction in response to heavy metal stress

Metallothioneins (MTs) are members of a family of cysteine-rich low molecular weight polypeptides which play an important role in heavy metal detoxification and homeostasis of intracellular metal ions in plant. Though MT genes from some selected plants have been characterized with respect to their protein sequences, kinetic properties and tissue-specific localization, no detailed study has been carried out in rice. Here, we present genome-wide identification, structural and expression analyses of rice MT gene family. Our analysis suggests presence of 11 class I MT genes in rice genome (Release 7 of the MSU Rice Genome Annotation Project) which are differentially expressed during growth and development, in various tissues and during biotic and abiotic stresses. Our analyses suggest that class I MT proteins in rice differ in tissue localization as well as in heavy metal coordination chemistry. We also suggest that some MTs have a predominant role in detoxification of As (V) in arsenic-tolerant rice cultivars. Our analysis suggests that apart from transcriptional regulation, post-transcriptional alternative splicing in some members of this family takes place during growth and development, in various tissues and during biotic and abiotic stresses.

Investigations into Potential Extrasynaptic Communication between the Dopaminergic and Nitrergic Systems

Nitric oxide is unconstrained by cell membranes and can therefore act along a broad distance as a volume transmitter. Spillover of nitric oxide between neurons may have a major impact on central nervous system diseases and particularly on neurodegeneration. There is evidence whereby communication between nitrergic and dopaminergic systems plays an essential role in the control of the nigrostriatal pathway. However, there is sparse information for either the coexistence or overlap of nitric oxide and dopaminergic structures. The dual localization of immunoreactivity for nitric oxide synthase (NOS) and tyrosine hydroxylase, enzymes responsible for the synthesis of nitric oxide and dopamine, respectively, was examined in neurons of the nigrostriatal pathway in the rat brain by means of a double-immunohistochemical method and confocal laser scanning microscopy, acquired at the resolution limit. After perfusional fixation, the brains were cut and double-immunostained. A proximity analysis of tyrosine hydroxylase and NOS structures was done using binary masks generated from the respective maximum projections, using confocal laser microscopy. Unrevealed regions were determined somatodendritic positive for both NOS and tyrosine hydroxylase, within an image limit resolution at 2 μm-wide margin. The described interconnected localization of nNOS(+) and TH(+) containing neuronal fibers and cells bodies in the nigrostriatal pathway propose a close anatomical link between the two neurotransmitters.

Inhibition of GTRAP3-18 may increase neuroprotective glutathione (GSH) synthesis

Glutathione (GSH) is a tripeptide consisting of glutamate, cysteine, and glycine; it has a variety of functions in the central nervous system. Brain GSH depletion is considered a preclinical sign in age-related neurodegenerative diseases, and it promotes the subsequent processes toward neurotoxicity. A neuroprotective mechanism accomplished by increasing GSH synthesis could be a promising approach in the treatment of neurodegenerative diseases. In neurons, cysteine is the rate-limiting substrate for GSH synthesis. Excitatory amino acid carrier 1 (EAAC1) is a neuronal cysteine/glutamate transporter in the brain. EAAC1 translocation to the plasma membrane promotes cysteine uptake, leading to GSH synthesis, while being negatively regulated by glutamate transport associated protein 3-18 (GTRAP3-18). Our recent studies have suggested GTRAP3-18 as an inhibitory factor for neuronal GSH synthesis. Inhibiting GTRAP3-18 function is an endogenous mechanism to increase neuron-specific GSH synthesis in the brain. This review gives an overview of EAAC1-mediated GSH synthesis, and its regulatory mechanisms by GTRAP3-18 in the brain, and a potential approach against neurodegeneration.

Metallothionein-like gene from Cicer microphyllum is regulated by multiple abiotic stresses

Cicer microphyllum, a wild relative of cultivated chickpea, is a high altitude cold desert-adapted species distributed in western and trans-Himalayas. A complementary DNA (cDNA) encoding metallothionein-like protein has been identified from a cold-induced subtraction cDNA library from C. microphyllum. The sequence of the cloned metallothionein gene from C. microphyllum (GQ900702) contains 240-bp-long open reading frame and encodes predicted 79-amino acid protein of 7.9 kDa. Sequence analysis identified the motifs characteristic of type II metallothionein and designated as CmMet-2. Southern hybridization confirms a single copy of the CmMet-2 gene in C. microphyllum genome. In situ hybridization indicated spatial transcript regulation of CmMet-2 in root and aerial parts and also confirmed through real-time PCR-based quantitative transcript analysis. The data revealed a significantly low level of transcript in the aerial parts than the roots. Quantitative analysis using real-time PCR assay revealed induction of transcript in all parts of plants in response to cold stress at 4°C. The transcript abundance was found to increase exponentially with time course from 6 to 24 h after exposure. Further, regulation of transcript accumulation in response to abscisic acid application, polyethylene glycol (100 μM)-induced osmotic stress, or ZnSO(4) (1 μM) foliar spray indicated by Northern hybridization suggests the involvement of CmMet-2 in multiple stress response.

EAAC1 gene deletion alters zinc homeostasis and exacerbates neuronal injury after transient cerebral ischemia

EAAC1 is a neuronal glutamate and cysteine transporter. EAAC1 uptake of cysteine provides substrate for neuronal glutathione synthesis, which plays a key role in both antioxidant defenses and intracellular zinc binding. Here we evaluated the role of EAAC1 in neuronal resistance to ischemia. EAAC1(-/-) mice subjected to transient cerebral ischemia exhibited twice as much hippocampal neuronal death as wild-type mice and a corresponding increase in microglial activation. EAAC1(-/-) mice also had elevated vesicular and cytosolic zinc concentrations in hippocampal CA1 neurons and an increased zinc translocation to postsynaptic neurons after ischemia. Treatment of the EAAC1(-/-) mice with N-acetyl cysteine restored neuronal glutathione concentrations and normalized basal zinc levels in the EAAC1(-/-) mice. Treatment of the EAAC1(-/-) mice with either N-acetyl cysteine or with zinc chelators reduced ischemia-induced zinc translocation, superoxide production, and neuron death. These findings suggest that cysteine uptake by EAAC1 is important for zinc homeostasis and neuronal antioxidant function under ischemic conditions.

Application of phi29 motor pRNA for targeted therapeutic delivery of siRNA silencing metallothionein-IIA and survivin in ovarian cancers

Ovarian cancer is a highly metastatic and lethal disease, making it imperative to find treatments that target late-stage malignant tumors. The packaging RNA (pRNA) of bacteriophage phi29 DNA-packaging motor has been reported to function as a highly versatile vehicle to carry small interference RNA (siRNA) for silencing of survivin. In this article, we explore the potential of pRNA as a vehicle to carry siRNA specifically targeted to metallothionein-IIa (MT-IIA) messenger RNA (mRNA), and compare it to survivin targeting pRNA. These two anti-apoptotic cell survival factors promote tumor cell viability, and are overexpressed in recurrent tumors. We find that pRNA chimeras targeting MT-IIA are processed into double-stranded siRNA by dicer, are localized within the GW/P-bodies, and are more potent than siRNA alone in silencing MT-IIA expression. Moreover, knockdown of both survivin and MT-IIA expression simultaneously results in more potent effects on cell proliferation in the aggressive ovarian tumor cell lines than either alone, suggesting that therapeutic approaches that target multiple genes are essential for molecular therapy. The folate receptor-targeted delivery of siRNA by the folate-pRNA dimer emphasizes the cancer cell-specific aspect of this system. The pRNA system, which has the capability to assemble into multivalent nanoparticles, has immense promise as a highly potent therapeutic agent.

Endogenous antioxidants and radical scavengers

All living organisms are constantly exposed to oxidant agents deriving from both endogenous and exogenous sources capable to modify biomolecules and induce damages. Free radicals generated by oxidative stress exert an important role in the development of tissue damage and aging. Reactive species (RS) derived from oxygen (ROS) and nitrogen (RNS) pertain to free radicals family and are constituted by various forms of activated oxygen or nitrogen. RS are continuosly produced during normal physiological events but can be removed by antioxidant defence mechanism: the imbalance between RS and antioxidant defence mechanism leads to modifications in cellular membrane or intracellular molecules. In this chapter only endogenous antioxidant molecules will be critically discussed, such as Glutathione, Alpha-lipoic acid, Coenzyme Q, Ferritin, Uric acid, Bilirubin, Metallothioneine, L-carnitine and Melatonin.

Regulation of neuronal glutathione synthesis

The brain is among the major organs generating large amounts of reactive oxygen species and is especially susceptible to oxidative stress. Glutathione (GSH) plays critical roles as an antioxidant, enzyme cofactor, cysteine storage form, the major redox buffer, and a neuromodulator in the central nervous system. GSH deficiency has been implicated in neurodegenerative diseases. GSH is a tripeptide comprised of glutamate, cysteine, and glycine. Cysteine is the rate-limiting substrate for GSH synthesis within neurons. Most neuronal cysteine uptake is mediated by sodium-dependent excitatory amino acid transporter (EAAT) systems, known as excitatory amino acid carrier 1 (EAAC1). Previous studies demonstrated EAAT is vulnerable to oxidative stress, leading to impaired function. A recent study found EAAC1-deficient mice to have decreased brain GSH levels and increased susceptibility to oxidative stress. The function of EAAC1 is also regulated by glutamate transporter associated protein 3-18. This review focuses on the mechanisms underlying GSH synthesis, especially those related to neuronal cysteine transport via EAAC1, as well as on the importance of GSH functions against oxidative stress.

Cloning and characterization of TsMT3, a type 3 metallothionein gene from salt cress (Thellungiella salsuginea)

A full-length type 3 plant metallothionein cDNA was isolated from 200 mM NaCl stressed shoots of the salt cress (Thellungiella salsuginea). The 447 bp TsMT3 cDNA sequence has a 207 bp open reading frame (ORF) and encodes a deduced 69 residue peptide of molecular weight 7.52 kDa. Southern blot analysis indicates that, there is only one copy of TsMT3 in the T. salsuginea genome. The accumulation of TsMT3 mRNA is enhanced by the stress imposed by PEG6000, 200 mM NaCl, 50 microM ABA, 4 degrees C, 40 microM CuSO(4) or 25 microM CdCl2. The expression vector pET28-TsMT3 was heterologously expressed in Escherichia coli to define the contribution of TsMT3 to heavy metal tolerance. In the presence of 2 mM CuSO4, 0.3 mM Pb(NO3)2 or 0.4 mM CdCl2, TsMT3 expressing cells exhibited enhanced metal tolerance and accumulated more metal than the controls. We believe that TsMT3 is probably involved in the processes of metal homeostasis, tolerance, and reactive oxygen species (ROS) scavenging.

Approaches to prevent dopamine quinone-induced neurotoxicity

Dopamine (DA) and its metabolites containing two hydroxyl residues exert cytotoxicity in dopaminergic neuronal cells, primarily due to the generation of highly reactive DA and DOPA quinones. Quinone formation is closely linked to other representative hypotheses such as mitochondrial dysfunction, inflammation, oxidative stress, and dysfunction of the ubiquitin-proteasome system, in the pathogenesis of neurodegenerative diseases such as Parkinson's disease and methamphetamine-induced neurotoxicity. Therefore, pathogenic effects of the DA quinone have focused on dopaminergic neuron-specific oxidative stress. Recently, various studies have demonstrated that some intrinsic molecules and several drugs exert protective effects against DA quinone-induced damage of dopaminergic neurons. In this article, we review recent studies on some neuroprotective approaches against DA quinone-induced dysfunction and/or degeneration of dopaminergic neurons.

Plant peptides and peptidomics

Extracellular plant peptides perform a large variety of functions, including signalling and defence. Intracellular peptides often have physiological functions or may merely be the products of general proteolysis. Plant peptides have been identified and, in part, functionally characterized through biochemical and genetic studies, which are lengthy and in some cases impractical. Peptidomics is a branch of proteomics that has been developed over the last 5 years, and has been used mainly to study neuropeptides in animals and the degradome of proteases. Peptidomics is a fast, efficient methodology that can detect minute and transient amounts of peptides and identify their post-translational modifications. This review describes known plant peptides and introduces the use of peptidomics for the detection of novel plant peptides.

Metallothionein I,II deficient mice do not exhibit significantly worse long-term behavioral outcomes following neonatal hypoxia-ischemia: MT-I,II deficient mice have inherent behavioral impairments

Metallothionein I and II are small metal binding proteins with a high affinity for zinc. They are found in the CNS and are thought to play a role in modulating the effects of free zinc. We hypothesized that MT-I,II deficient mice would have more neurological deficits both functionally and anatomically following a neonatal hypoxic-ischemic (HI) insult than wild-type mice subjected to the same insult. Forty wild-type and 40 MT-I,II deficient C57 X 129T2 F1 P10 mice were randomized to either 45 min of HI or sham HI. Beginning on P50, the mice were given a series of behavioral tests including locomotor activity, novel object recognition, Morris water maze (cued, hidden platform, reduced platform), a 2-week-delayed probe trial and an apomorphine-induced rotation test. At the conclusion of testing, the brains were removed for histological analysis including staining with NeuN and GFAP to assess neuronal loss and reactive gliosis. There were no significant differences in functional or anatomic measures between the wild-type HI mice and the MT-I,II deficient HI mice. The MT-I,II deficient mice exhibited an impaired rate of learning in the spatially oriented mazes but once learned retained the information as well as the wild-type mice. The absence of functional MT-I,II proteins does not result in significantly worse injury following 45 min of HI on P10. The MT-I,II deficient mice have baseline impairments in spatial learning but not retention.

Protective effects of metallothionein against dopamine quinone-induced dopaminergic neurotoxicity

Dopamine (DA) quinone as DA neuron-specific oxidative stress conjugates with cysteine residues in functional proteins to form quinoproteins. Here, we examined the effects of cysteine-rich metal-binding proteins, metallothionein (MT)-1 and -2, on DA quinone-induced neurotoxicity. MT quenched DA semiquinones in vitro. In dopaminergic cells, DA exposure increased quinoproteins and decreased cell viability; these were ameliorated by pretreatment with MT-inducer zinc. Repeated L-DOPA administration markedly elevated striatal quinoprotein levels and reduced the DA nerve terminals specifically on the lesioned side in MT-knockout parkinsonian mice, but not in wild-type mice. Our results suggested that intrinsic MT protects against L-DOPA-induced DA quinone neurotoxicity in parkinsonian mice by its quinone-quenching property.

Expression and functional activity of pro-oxidants and antioxidants in murine heart exposed to acute hypobaric hypoxia

Under hypobaric hypoxia, antioxidant defenses of the heart are stressed by the enhanced production of ROS. Mammalian heart acclimatizes to hypoxia through altered gene expression, which we studied in murine heart exposed to 10h of acute hypobaric hypoxia (AHH), equivalent to 15000ft, using cDNA arrays. Functional classification of genes with a > or =2-fold change revealed a number of pro-oxidants like Cyba, Xdh, Txnip, Ppp1r15b and antioxidants like Cat, Gpx1, Mt1, Mgst1. Interestingly, the protein level of Cyba, a subunit of NADPH oxidase, was markedly decreased in AHH exposed heart, suggesting the involvement of some stress response pathways. The AHH exposure also caused a significant reduction (50%) in the level of GSH (P<0.05). The present study provides a retrospective insight on the cellular antioxidant defense mechanisms under AHH.

Sodium selenite induces superoxide-mediated mitochondrial damage and subsequent autophagic cell death in malignant glioma cells

Malignant gliomas are resistant to various proapoptotic therapies, such as radiotherapy and conventional chemotherapy. In this study, we show that selenite is preferentially cytotoxic to various human glioma cells over normal astrocytes via autophagic cell death. Overexpression of Akt, survivin, XIAP, Bcl-2, or Bcl-xL failed to block selenite-induced cell death, suggesting that selenite treatment may offer a potential therapeutic strategy against malignant gliomas with apoptotic defects. Before selenite-induced cell death in glioma cells, disruption of the mitochondrial cristae, loss of mitochondrial membrane potential, and subsequent entrapment of disorganized mitochondria within autophagosomes or autophagolysosomes along with degradation of mitochondrial proteins were noted, showing that selenite induces autophagy in which mitochondria serve as the main target. At the early phase of selenite treatment, high levels of superoxide anion were generated and overexpression of copper/zinc superoxide dismutase or manganese superoxide dismutase, but not catalase, significantly blocked selenite-induced mitochondrial damage and subsequent autophagic cell death. Furthermore, treatment with diquat, a superoxide generator, induced autophagic cell death in glioma cells. Taken together, our study clearly shows that superoxide anion generated by selenite triggers mitochondrial damage and subsequent mitophagy, leading to irreversible cell death in glioma cells.

Neurotoxicity mechanisms of thioether ecstasy metabolites

3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy"), is a widely abused, psychoactive recreational drug that is known to induce neurotoxic effects. Human and rat hepatic metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine (MDA), which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA) and alpha-methyldopamine (alpha-MeDA), respectively, which are both catechols that can undergo oxidation to the corresponding ortho-quinones. Ortho-quinones may be conjugated with glutathione (GSH) to form glutathionyl adducts, which can be transported into the brain and metabolized to the correspondent N-acetylcysteine (NAC) adducts. In this study we evaluated the neurotoxicity of nine MDMA metabolites, obtained by synthesis: N-Me-alpha-MeDA, alpha-MeDA and their correspondent GSH and NAC adducts. The studies were conducted in rat cortical neuronal cultures, for a 6 h of exposure period, under normal (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Our findings show that thioether MDMA metabolites are strong neurotoxins, significantly more than their correspondent parent catechols. On the other hand, N-Me-alpha-MeDA and alpha-MeDA are more neurotoxic than MDMA. GSH and NAC conjugates of N-Me-alpha-MeDA and alpha-MeDA induced a concentration dependent delayed neuronal death, accompanied by activation of caspase 3, which occurred earlier in hyperthermic conditions. Furthermore, thioether MDMA metabolites time-dependently increased the production of reactive species, concentration-dependently depleted intracellular GSH and increased protein bound quinones. Finally, thioether MDMA metabolites induced neuronal death and oxidative stress was prevented by NAC, an antioxidant and GSH precursor. This study provides new insights into the neurotoxicity mechanisms of thioether MDMA metabolites and highlights their importance in "ecstasy" neurotoxicity.

Metallothionein as a prognostic biomarker in breast cancer

Breast cancer is the most common cancer in women, with a general upward trend in incidence. Basic and clinical breast cancer research has continued at a rapid pace, in the endeavor to understand the biology of the disease so as to improve management of patients. Besides traditional pathological indicators, expression of molecular markers in breast cancer has also been comprehensively investigated. This paper will focus on the prognostic utility of metallothioneins (MTs), a family of low molecular weight metal binding proteins encoded by at least 10 functional MT genes that are associated with cell proliferation in breast cancer. Evidence that MT is a potential prognostic biomarker for breast cancer is supported by many reports in the literature. Expression of the MT protein has been detected by immunohistochemistry in a significant portion of invasive ductal breast cancers. MT expression has also been well studied in association with traditional clinico-pathological parameters of breast cancers. Generally, higher MT expression in breast cancers is predictive of worse patient outcomes. The relationship of MT isoforms to histological grade, estrogen receptor (ER) status, and prognosis will also be discussed.

Suppression of nitrative damage by metallothionein in diabetic heart contributes to the prevention of cardiomyopathy

Diabetic cardiomyopathy has become a major contributor to the increased mortality of diabetic patients. Although the development and progression of diabetic cardiomyopathy are considered to be associated with diabetes-derived oxidative stress, the precise mechanisms for and effectively preventive approaches to diabetic cardiomyopathy remain to be explored. Recent studies showed that reactive oxygen or nitrogen species (ROS/RNS) not only play a critical role in the initiation of diabetic cardiomyopathy, but also play an important role in physiological signaling. Therefore, this review will first discuss the dual roles of ROS/RNS in the physiological signaling and pathogenic remodeling leading to cardiomyopathy under diabetic conditions. The significant prevention of diabetic cardiomyopathy by metallothionein (MT) as a potent and nonspecific antioxidant will be also summarized. It is clearly revealed that although dual roles of peroxynitrite-nitrated proteins have been indicated under both physiological and pathogenic conditions, suppression of nitrative damage by MT in the diabetic heart is the major mechanism responsible for its prevention of diabetic cardiomyopathy. Finally the potential for clinical enhancement of the cardiac MT expression to prevent or delay the occurrence of cardiomyopathy in diabetic patients will also be addressed.