Cardiovascular protective effect of pioglitazone on oxidative stress in rats with metabolic syndrome

BACKGROUND

Although cardiovascular oxidative stress is examined in type 2 diabetes, there is relatively limited number of reports about the effect of pioglitazone, an insulin sensitizer, on cardiovascular oxidative stress in sucrose diet-induced metabolic syndrome (MetS). As a regulator of cardiovascular homeostasis, thioredoxin (TRX) has an important role in defense against oxidative stress in cardiovascular diseases. The purpose of this study is to investigate the role of pioglitazone on oxidative stress markers and TRX1 level in tissues of both heart and aorta from MetS rats.

METHODS

Male Wistar rats (200 to 250 g in weight) were divided into three groups: control group, MetS group receiving drinking water including 935 mM sucrose, and pioglitazone-treated MetS (MetS-P) group. Aspartate aminotransferase (AST), lactate dehydrogenase (LDH), total oxidant status (TOS), and total antioxidant status (TAS) levels were measured in serum and tissues using commercial kits. Malondialdehyde (MDA) and superoxide dismutase (SOD) were measured in serum and tissues for experimental groups. TRX1 protein level was measured by western blot.

RESULTS

The sucrose-fed rats exhibited several characteristics of MetS. In MetS group, AST, LDH, TOS, and MDA levels of heart and aorta tissues increased, whereas TAS and SOD levels of these tissues decreased. TRX1 protein level of heart and aorta tissues decreased in MetS group. Also, in the serum of experimental groups, AST, LDH, and TOS levels increased.

CONCLUSION

Pioglitazone treatment significantly increased TRX1 protein level in heart and aorta tissues in MetS group. Pioglitazone affected the TRX1 protein level via regulation of reactive oxygen intermediates. Pioglitazone reduced the elevated oxidative stress in heart and aorta of MetS rats.

Alterations in NO/ROS ratio and expression of Trx1 and Prdx2 in isoproterenol-induced cardiac hypertrophy

The development of cardiac hypertrophy is a complicated process, which undergoes a transition from compensatory hypertrophy to heart failure, and the identification of new biomarkers and targets for this disease is greatly needed. Here we investigated the development of isoproterenol (ISO)-induced cardiac hypertrophy in an in vitro experimental model. After the induction of hypertrophy with ISO treatment in H9c2 cells, cell surface area, cell viability, cellular reactive oxygen species (ROS), and nitric oxide (NO) levels were tested. Our data showed that the cell viability, mitochondrial membrane potential, and NO/ROS balance varied during the development of cardiac hypertrophy in H9c2 cells. It was also found that the expression of thioredoxin1 (Trx1) and peroxiredoxin2 (Prdx2) was decreased during the cardiac hypertrophy of H9c2 cells. These results suggest a critical role for Trx1 and Prdx2 in the cardiac hypertrophy of H9c2 cells and in the transition from compensated hypertrophy to de-compensated hypertrophy in H9c2 cells, and our findings may have important implications for the management of this disease.

Reactive oxygen species, glutathione, and thioredoxin influence suberoyl bishydroxamic acid-induced apoptosis in A549 lung cancer cells

Suberoyl bishydroxamic acid (SBHA) as a histone deacetylase (HDAC) inhibitor can induce apoptosis through the formation of reactive oxygen species (ROS). However, there is no report about the regulation of ROS and antioxidant enzymes in SBHA-treated lung cancer cells. Here, we investigated the toxicological effects of SBHA on the regulations of ROS, glutathione (GSH), and antioxidant enzymes, especially thioredoxin (Trx) in A549 lung cancer cells. SBHA inhibited the growth of A549 cells in time- and dose-dependent manners, and it induced apoptosis which accompanied by the loss of mitochondrial membrane potential (MMP; ΔΨm). SBHA significantly increased ROS levels including O2 (•-) level at 72 h whereas it decreased ROS levels at the early time points (30 min to 3 h). SBHA also induced GSH depletion at 24 and 72 h. N-acetyl cysteine (NAC; a well-known antioxidant) prevented apoptotic cell death and GSH depletion via decreasing ROS in SBHA-treated A549 cells. In addition, SBHA changed the levels of antioxidant-related proteins, especially Trx1. The expression and activity of Trx1 in A549 cells were reduced by SBHA. While the downregulation of Trx1 enhanced cell death, ROS level, and GSH depletion in SBHA-treated A549 cells, the overexpression of Trx1 decreased ROS level in these cells without the prevention of cell death and GSH depletion. In conclusion, SBHA-induced A549 cell death was influenced by changes in ROS and GSH levels. The basal status of Trx1 among other antioxidant proteins was closely correlated with the survival of A549 cells.

Methodological aspects of ELISA analysis of thioredoxin 1 in human plasma and cerebrospinal fluid

Thioredoxin-1 (Trx1) is a protein antioxidant involved in major cellular processes. Increased plasma levels of Trx1 have been associated with human diseases suggesting that Trx1 is a marker for oxidative stress with putative clinical use. However, the reported mean levels of Trx1 in the control cohorts vary a hundred-fold between studies (0.8-87 ng/ml), possibly due to methodological differences between the capture ELISA used in the different studies. The aim of this study was to investigate methodological aspects related to the ELISA measurement of Trx1. ELISAs utilizing different capture and detection combinations of antibodies to Trx1 and as well as recombinant human (rh) Trx1 standards from two sources were characterized. The different ELISAs were subsequently used to measure Trx1 in human plasma and cerebrospinal fluid samples (CSF) from healthy donors and from patients with various neurological diagnoses. The Trx1 standards differed in their content of monomeric and oligomeric Trx1, which affected the ELISAs composed of different antibody combinations. Thus, the levels of Trx1 determined in human plasma and CSF samples varied depending on the antibody used in the ELISAs and on the rhTrx1 standard. Furthermore, the relevance of preventing interference by heterophilic antibodies (HA) in human plasma and CSF was investigated. The addition of a HA blocking buffer to human samples drastically reduced the ELISA signals in many samples showing that HA are likely to cause false positive results unless they are blocked. In conclusion, the study shows that the design of a Trx1 ELISA in regards to antibodies and standards used has an impact on the measured Trx1 levels. Importantly, analyses of human plasma and CSF without preventing HA interference may obscure the obtained data. Overall, the results of this study are crucial for the improvement of future studies on the association of Trx1 levels with various diseases.

Cycling hypoxia up-regulates thioredoxin levels in human MDA-MB-231 breast cancer cells

The thioredoxin system is a key cellular antioxidant system and is highly expressed in cancer cells, especially in more aggressive and therapeutic resistant tumors. We analysed the expression of the thioredoxin system in the MDA-MB-231 breast cancer cell line under conditions mimicking the tumor oxygen microenvironment. We grew breast cancer cells in either prolonged hypoxia or hypoxia followed by various lengths of reoxygenation and in each case cells were cultured with or without a hypoxic cycling preconditioning (PC) phase preceding the hypoxic growth. Flow cytometry-based assays were used to measure reactive oxygen species (ROS) levels. Cells grown in hypoxia showed a significant decrease in ROS levels compared to normoxic cells, while a significant increase in ROS levels over normoxic cells was observed after 4 h of reoxygenation. The PC pre-treatment did not have a significant effect on ROS levels. Thioredoxin levels were also highest after 4 h of reoxygenation, however cells subjected to PC pre-treatment displayed even higher thioredoxin levels. The high level of intracellular thioredoxin was also reflected on the cell surface. Reporter assays showed that activity of the thioredoxin and thioredoxin reductase gene promoters was also highest in the reoxygenation phase, although PC pre-treatment did not result in a significant increase over non-PC treated cells. The use of a dominant negative Nrf-2 negated the increased thioredoxin promoter activity during reoxygenation. This data suggests that the high levels of thioredoxin observed in tumors may arise due to cycling between hypoxia and reoxygenation.

[Identification of proteins overexpressed in malignant gastric tumors: comparison of the results of 2-De and bioinformatics search]

Comparison of protein expression in intestinal and diffuse stomach tumors by 2D gel electrophoresis led to identification of three proteins (SOD2, S100A6, and TXN), which are overexpressed in tumors as compared to normal controls. It was shown, that overexpression of proteins SOD2 and TXN occurs much more frequently in diffuse tumors than in intestinal ones. A control panel of eleven proteins overexpressed in stomach tumors has been selected based on the data of comparative 2D analysis described in the literature. Bioinformatics search for mRNAs encoding proteins from the control panel in Oncomine database (which contains the results of determination of mRNA transcription level in tumor vs. normal samples) demonstrated the coincidence of proteomic and transcriptomic data for seven out of 11 proteins.

[Clinical application of urinary redox regulating protein, thioredoxin]

Thioredoxin (TRX) is a redox-regulating protein, induced in response to oxidative stress. The function of TRX in the urine is unknown. We show here that urinary TRX begin to increase within one hour and peaks within two hours after ischemia reperfusion of mice. Serum levels of TRX are not changed by the ischemia/reperfusion. In a time-dependent study of immunohistochemistry, TRX appears diffusely in the tubular cytosol in sham-operated mice. On the other hand, immediately after renal ischemia/reperfusion, TRX become to eccentrically-locate in the apical side of the tubular cytosol, and then TRX is detected only in the urinary lumen. In contrast, when we examine the immunolocalization of glutaredoxin, which is a member of the TRX superfamily, we find that the immunoreactivity is unchanged after renal ischemia/reperfusion. Northern blotting and in situ hybridization show that epithelial cells constitutively express TRX mRNA but neither expression levels nor distribution are altered by ischemia-reperfusion. An overexpression of hTRX in transgenic mice attenuates the reperfusion injury. These data suggests that TRX is produced in tubular cells in a steady state. The increase in the urine after ischemia-reperfusion is not mediated by a de novo induction of TRX mRNA but by a discharge of TRX protein from tubular epithelial cells. TRX is useful for the diagnosis of AKI in association with oxidative stress.

Transgenic mice overexpressing methionine sulfoxide reductase A: characterization of embryonic fibroblasts

Methionine residues in protein can be oxidized by reactive oxygen species to generate methionine sulfoxide. Aerobic organisms have methionine sulfoxide reductases capable of reducing methionine sulfoxide back to methionine. Methionine sulfoxide reductase A acts on the S-epimer of methionine sulfoxide, and it is known that altering its cellular level by genetic ablation or overexpression has notable effects on resistance to oxidative stress and on life span in species from microorganisms to animals. In mammals, the enzyme is present in both the cytosol and the mitochondria, and this study was undertaken to assess the contribution of each subcellular compartment's reductase activity to resistance against oxidative stresses. Nontransgenic mouse embryonic fibroblasts lack methionine sulfoxide reductase A activity, providing a convenient cell type to determine the effects of expression of the enzyme in each compartment. We created transgenic mice with methionine sulfoxide reductase A targeted to the cytosol, mitochondria, or both and studied embryonic fibroblasts derived from each line. Unexpectedly, none of the transgenic cells gained resistance to a variety of oxidative stresses even though the expressed enzymes were catalytically active when assayed in vitro. Noting that activity in vivo requires thioredoxin and thioredoxin reductase, we determined the levels of these proteins in the fibroblasts and found that they were very low in both the nontransgenic and the transgenic cells. We conclude that overexpression of methionine sulfoxide reductase A did not confer resistance to oxidative stress because the cells lacked other proteins required to constitute a functional methionine sulfoxide reduction system.

Elevated levels of thioredoxin 1 in the lungs and sera of idiopathic pulmonary fibrosis, non-specific interstitial pneumonia and cryptogenic organizing pneumonia

OBJECTIVE

Oxidant stress is thought to be involved in the establishment of idiopathic interstitial pneumonia (IIP). Thioredoxin 1 (TRX1) plays a role as a strong antioxidant in vivo, suggesting that TRX1 may be involved in the pathogenesis of IIPs. However, there is no report on TRX1 levels in the sera of IIPs. In addition, TRX1 expression in the lungs of non-specific interstitial pneumonia (NSIP) and cryptogenic organizing pneumonia (COP) patients also has not been reported. Here, we investigated whether or not TRX1 levels are altered in the lungs and sera of patients with idiopathic pulmonary fibrosis (IPF), NSIP, and COP.

METHODS

Immunohistochemical analysis was performed to examine the expression of TRX1. TRX1 levels in sera were measured using an ELISA kit.

RESULTS

TRX1 was expressed in the bronchiole-alveolar epithelium, especially with regenerative or metaplastic feature, and in alveolar macrophages in usual interstitial pneumonia (UIP) and fibrotic NSIP. TRX1 was weakly expressed in the lungs of cellular NSIP and COP. TRX1 producing cells in UIP (n=16), fibrotic NSIP (n=15), cellular NSIP (n=4), and COP (n=5) were significantly increased when compared to nonsmokers (n=7). TRX1 producing cells in UIP and fibrotic NSIP were significantly increased when compared to cellular NSIP and COP. TRX1 levels in the sera of the patients with IPF (n=32; 74.2 ± 7.5 ng/mL), fibrotic NSIP (n=7; 82.5 ± 18.4 ng/mL), cellular NSIP (n=3; 62.2 ± 3.2 ng/mL) and COP (n=17; 88.8 ± 19.7 ng/mL) were significantly higher than those of control subjects (n=74; 35.3 ± 2.7 ng/mL). Furthermore, TRX1 levels in the sera of IPF patients who later showed acute exacerbation (n=7; 106.6 ± 16.3 ng/mL) were significantly higher than those of IPF patients without acute exacerbation (n=25; 65.1 ± 7.6 ng/mL).

CONCLUSION

Overproduction of TRX1 in the lungs and sera may play an important role in the pathogenesis of IIPs.

From proteomics to structural studies of cytosolic/mitochondrial-type thioredoxin systems in barley seeds

Thioredoxins (Trx) are ubiquitous proteins that participate in thiol disulfide reactions via two active site cysteine residues, allowing Trx to reduce disulfide bonds in target proteins. Recent progress in proteome analysis has resulted in identification of a wide range of potential target proteins for Trx, indicating that Trx plays a key role in several aspects of cell metabolism. In contrast to other organisms, plants contain multiple forms of Trx that are classified based on their primary structures and sub-cellular localization. The reduction of cytosolic and mitochondrial types of Trx is dependent on NADPH and catalyzed by NADPH-dependent thioredoxin reductase (NTR). In barley, two isoforms each of Trx and NTR have been identified and investigated using proteomics, gene expression, and structural studies. This review outlines the diverse roles suggested for cytosolic/mitochondrial-type Trx systems in cereal seeds and summarizes the current knowledge of the barley system including recent data on function, regulation, interactions, and structure. Directions for future research are discussed.

Novel prediction method of beer foam stability using protein Z, barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and yeast thioredoxin

Foam stability is an important quality trait of beer. Our previous results of two-dimensional gel electrophoresis (2DE) analyses of beer proteins implied a relationship between barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and beer foam stability as judged by the NIBEM-T analyzer. To develop a novel prediction method of beer foam stability under different conditions of barley cultivar and malt modification, multiple linear regression analysis was applied. The spot intensities of major beer proteins on 2DE gel were quantified and used as explanatory variables. The foam stabilities of 25 beer samples each brewed from malt with different malt modification in one of the three cultivars (cultivars A, B, and C) were explained by the spot intensities of BDAI-1 at the 5% significance level ( r = 0.421). Furthermore, two other major protein spots (b0 and b5) were observed on the 2DE gels of Japanese commercial beer samples with different foam stability. Then, multiple regression for foam stability was calculated using these three spot intensities as explanatory variables. As a result, 72.1% of the beer foam stability in 25 beer samples was explained by a novel multiple regression equation calculated using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. To verify the validity of the multiple regression equation and the explanatory variables, the beer foam stability in practical beer samples was analyzed. As a result, 81.5% of the beer foam stability in 10 Japanese commercial beer samples was also explained by using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. Mass spectrometry analyses followed by database searches revealed that protein spots b0 and b5 were identified as protein Z originated from barley and thioredoxin originated from yeast, respectively. These results confirm that BDAI-1 and protein Z are foam-positive factors and identify yeast thioredoxin as a possible novel foam-negative factor.

Immunocytochemical localization of Pisum sativum TRXs f and m in non-photosynthetic tissues

Plants are the organisms containing the most complex multigenic family for thioredoxins (TRX). Several types of TRXs are targeted to chloroplasts, which have been classified into four subgroups: m, f, x, and y. Among them, TRXs f and m were the first plastidial TRXs characterized, and their function as redox modulators of enzymes involved in carbon assimilation in the chloroplast has been well-established. Both TRXs, f and m, were named according to their ability to reduce plastidial fructose-1,6-bisphosphatase (FBPase) and malate dehydrogenase (MDH), respectively. Evidence is presented here based on the immunocytochemistry of the localization of f and m-type TRXs from Pisum sativum in non-photosynthetic tissues. Both TRXs showed a different spatial pattern. Whilst PsTRXm was localized to vascular tissues of all the organs analysed (leaves, stems, and roots), PsTRXf was localized to more specific cells next to xylem vessels and vascular cambium. Heterologous complementation analysis of the yeast mutant EMY63, deficient in both yeast TRXs, by the pea plastidial TRXs suggests that PsTRXm, but not PsTRXf, is involved in the mechanism of reactive oxygen species (ROS) detoxification. In agreement with this function, the PsTRXm gene was induced in roots of pea plants in response to hydrogen peroxide.

Fragmentation of multiply-charged intact protein ions using MALDI TOF-TOF mass spectrometry

Top down proteomics in a TOF-TOF instrument was further explored by examining the fragmentation of multiply charged precursors ions generated by matrix-assisted laser desorption ionization. Evaluation of sample preparation conditions allowed selection of solvent/matrix conditions and sample deposition methods to produce sufficiently abundant doubly and triply charged precursor ions for subsequent CID experiments. As previously reported, preferential cleavage was observed at sites C-terminal to acidic residues and N-terminal to proline residues for all ions examined. An increase in nonpreferential fragmentation as well as additional low mass product ions was observed in the spectra from multiply charged precursor ions providing increased sequence coverage. This enhanced fragmentation from multiply charged precursor ions became increasingly important with increasing protein molecular weight and facilitates protein identification using database searching algorithms. The useable mass range for MALDI TOF-TOF analysis of intact proteins has been expanded to 18.2 kDa using this approach.

Human TRP14 gene homologue from amphioxus Branchiostoma belcheri: identification, evolution, expression and functional characterization

Thioredoxin-related protein of 14 kDa, TRP14, has previously been identified only in humans. Here we report the identification and expression of an amphioxus TRP14 gene, named AmphiTRP14, the first such data in a non-mammalian organism. AmphiTRP14 consists of a 372-bp open reading frame coding for a 123-amino-acid protein with a calculated molecular weight of 14 kDa. It shares 56% identity with human TRP14 and possesses a highly conserved motif CPDC. Sequence comparison suggests the evolutionary appearance of the four-exon-three-intron organization of TRP14 genes after the split of protostome/deuterostome, which is highly conserved since then. AmphiTRP14 has been successfully expressed in Escherichia coli and purified. The recombinant protein exhibited features characteristic of human TRP14, including a reductase activity towards insulin. Both in situ hybridization histochemistry and immunohistochemistry revealed that AmphiTRP14 was expressed in a tissue-specific manner, with the most abundant expression in the hepatic caecum, ovary and hind-gut. This suggests that AmphiTRP14 plays a fundamental but tissue-specific role, or alternatively reflects differences in the tissue susceptibility to oxidative damage.

Cell-free synthesis of proteins that require disulfide bonds using glucose as an energy source

The primary objective of this work was to create a cell-free protein synthesis extract that produces proteins requiring disulfide bonds while using glucose as an energy source. We attempted to avoid using iodoacetamide (IAM) to stabilize the required oxidizing thiol redox potential, since previous IAM pretreatments prevented glucose utilization apparently by inactivating glyceraldehyde 3-phosphate dehydrogenase (G-3PDH). Instead, the glutathione reductase (Gor)-mediated disulfide reductase system was disabled by deleting the gor gene from the KC6 cell-extract source strain. The thioredoxin reductase (TrxB)-mediated system was disabled by first adding a purification tag to the trxB gene in the chromosome to create strain KGK10 and then by affinity removal of the tagged TrxB. This was expected to result in a cell extract devoid of all disulfide reductase activity, but this was not the case. Although the concentration of IAM required to stabilize oxidized glutathione in the KGK10 extract could be reduced 20-fold, IAM pretreatment was still required to avoid disulfide reduction. Nonetheless, active urokinase and murine granulocyte macrophage-colony stimulating factor (mGM-CSF) were produced in reactions with KGK10 extract either with affinity removal of TrxB or with 50 microM IAM pretreatment. With the less intensive IAM pretreatment, glucose could be used as an energy source in a production system that promotes oxidative protein folding. This new protocol offers an economically feasible cell-free system for the production of secreted mammalian proteins as human therapeutics or vaccines.

Dual action of sulforaphane in the regulation of thioredoxin reductase and thioredoxin in human HepG2 and Caco-2 cells

We have previously demonstrated that sulforaphane is a potent inducer for thioredoxin reductase in HepG2 and MCF-7 cells (Zhang et al. Carcinogenesis 2003, 24, 497-503; Wang et al. J. Agric. Food Chem. 2005, 53, 1417-1421). In this study, we have shown that sulforaphane is not only an inducer for thioredoxin reductase but also an inducer for its substrate, thioredoxin in HepG2, and undifferentiated Caco-2 cells. Sulforaphane acts at two levels in the regulation of thioredoxin reductase/thioredoxin system by the upregulation of the expression of both the enzyme and the substrate. In human hepatoma HepG2 cells, sulforaphane induced thioredoxin reductase mRNA and protein by 4- and 2-fold, respectively, whereas thioredoxin mRNA was induced 2.9-fold and thioredoxin protein was unchanged in whole cell extracts, but an increase in nuclear accumulation (1.8-fold) was observed. Moreover, the induction of thioredoxin reductase was found faster than that of thioredoxin. The effects of PI3K and MAPK kinase inhibitors, LY294002, PD98059, SP600125, and SB202190, have been investigated on the sulforaphane-induced expression of thioredoxin reductase and thioredoxin. PD98059 abrogates the sulforaphane-induced thioredoxin reductase at both mRNA and protein levels in HepG2 cells, although other inhibitors were found less effective. However, both PD98059 and LY294002 significantly decrease thioredoxin mRNA expression in HepG2 cells. None of the inhibitors tested were able to modulate the level of expression of either thioredoxin reductase mRNA or protein in Caco-2 cells suggesting that there are cell-specific responses to sulforaphane. In summary, the dietary isothiocyanate, sulforaphane, is important in the regulation of thioredoxin reductase/thioredoxin redox system in cells.

Efficient extraction of thioreodoxin from Saccharomyces cerevisiae by ethanol

Thioredoxin, an antioxidant protein, is a promising molecule for development of functional foods because it protects the gastric mucosa and reduces the allergenicity of allergens. To establish a method for obtaining an ample amount of yeast thioredoxin, we found here that thioredoxin is released from Saccharomyces cerevisiae by treatment with 20% ethanol. We also found that Japanese sake contains a considerable amount of thioredoxin.

A possible role of thioredoxin interacting protein in the pathogenesis of streptozotocin-induced diabetic nephropathy

Oxidative stress has been suggested to play an important role in the pathogenesis of diabetic nephropathy because it increases under diabetic conditions and is known to induce cellular dysfunction in a wide variety of cells. To protect cells against oxidative stress, cells possess defensive mechanisms such as intracellular antioxidants. Although it has been reported that central enzymes in the antioxidative defense mechanisms of the cell are induced under hyperglycemic conditions, the oxidative stress level remains high. On the other hand, there are endogenous inhibitors of antioxidants, such as thioredoxin interacting protein (Txnip). In the present study, the relationship between diabetic nephropathy and Txnip was investigated using streptozotocin (STZ)-induced diabetic mice. Eight-week-old male C57BL/6 mice were treated with either STZ or citrate vehicle. After 24 weeks of treatment, diabetic nephropathy and oxidative stress were assessed by biochemical analyses of urine and histological analyses of the kidneys. In addition, the expression of Type IV collagen alpha1 chain (Col4A1), Transforming growth factor-beta (TGF-beta), and Txnip were evaluated by real-time polymerase chain reaction. Albuminuria, renal hypertrophy, and expansion of the mesangial area, which are the hallmarks of diabetic nephropathy, were confirmed in the diabetic mice. The mRNA expression of COL4A1 and TGF-beta was dramatically increased in diabetic mice in comparison with the control mice. Moreover, associated with the increased renal expression of Txnip, diabetic conditions increased oxidative stress as determined by urinary excretion of 8-hydroxy-2'-deoxyguanosine and acrolein adduct, which are oxidative stress markers. Moreover, Txnip may be a therapeutic target in diabetic nephropathy.

In-Cell NMR spectroscopy: inhibition of autologous protein expression reduces Escherichia coli lysis

Structural studies by in-cell nuclear magnetic resonance are a developing new field of research, and their objective is to obtain structural information of proteins and other biological macromolecules in the cytoplasm of Escherichia coli cells. The major limitation of in-cell experiments is cell lysis that occurs during the experiments. In this article, we describe how inhibition of autologous expression by rifampicin at a high concentration decreases cell lysis in E. coli. We suggest that rifampicin is acting in the programmed cell death gene system MazEF, which is triggered by stress conditions and ultimately leads to cell lysis.

Insulin-like growth factor-I (IGF-I) and thioredoxin are differentially expressed along the reproductive tract of the ewe during the oestrous cycle and after ovariectomy

Insulin-like growth factor-I (IGF-I) and thioredoxin are regulated by gonadal steroids in the female reproductive tract of many species. Oestradiol regulates IGF-I and thioredoxin mRNA levels in the reproductive tract of prepubertal lambs. The physiological status (different endocrine environment) may affect the sensitivity of the reproductive tract to oestradiol and progesterone. We studied the effects of different endocrine milieus (late-follicular and luteal phases of the oestrous cycle, and ovariectomy before or after puberty) on the expression of IGF-I, thioredoxin, oestrogen receptor α (ERα) and progesterone receptor (PR) in sheep. The mRNA levels were determined by a solution hybridisation technique. In the uterus the levels of ERα, PR and thioredoxin mRNA were higher in the late-follicular phase group than in the other three groups, and IGF-I mRNA was high during both the late-follicular and the luteal phases. In the cervix only PR mRNA was significantly higher in the ewes in the late-follicular phase than in the other groups. In the oviducts the levels of thioredoxin and ERα mRNA were highest in the ovariectomised adult ewes, and thioredoxin mRNA was higher than the levels found in the ewes in the late-follicular phase. The IGF-I mRNA levels in the oviduct did not differ between any of the groups. The transcripts of IGF-I, thioredoxin, ERα and PR, varied according to the physiological status and also along the female reproductive tract, suggesting that the regulation of the mRNA levels of these factors by the steroid environment is tissue specific.

Koncentrationen av insulin-like growth factor-I (IGF-I) och thioredoxin regleras hos många arter i honors reproduktionsorgan av könssteroider. Sålunda reglerar östradiol IGF-I och thioredoxin mRNA i reproduktionsorganen hos prepubertala lamm. Djurets fysiologiska status (dvs den endokrina miljön) kan påverka känsligheten hos reproduktionsorganen för östradiol och progesteron. Vi studerade effekterna av olika endokrina miljöer (sen follikelfas och lutealfas i östruscykeln, samt ovariektomi före och efter puberteten) på uttrycket av IGF-I, thioredoxin, östrogenreceptor α (ERα) och progesteronreceptorn (PR) hos får. Lösningshybridisering användes för att bestämma mRNA nivåerna. I livmodern var mRNA koncentrationen för ERα, PR och thioredoxin högre i sen follikelfas än i de andra tre grupperna och IGF-I mRNA nivån var hög både under sen follikelfas och i lutealfas. PR mRNA i cervix var signifikant högre hos tackorna under sen follikelfas än i de andra grupperna. I äggledarna var mRNA nivåerna av thioredoxin och ERα högst i de djur som ovariektomerats som vuxna, och thioredoxin mRNA var högre än hos tackorna under sen follikelfas. Det förelåg ingen skillnad vad gäller IGF-I mRNA nivåerna i äggledaren mellan någon av grupperna. IGF-I, thioredoxin, ERα och PR mRNA nivåerna varierade beroende på fysiologisk status och morfologisk lokalisation i reproduktionsorganen. Detta tyder på att steroidhormonernas reglering av dessa faktorers mRNA uttryck också är vävnadsspecifik.

Expression of thioredoxin and thioredoxin-binding protein-2 in the liver of patients with chronic hepatitis C as a predictor of response to interferon therapy

Oxidative stress contributes to the pathogenesis of various hepatic injuries. Thioredoxin (TRX) is an indicator of oxidative stress, reported to be increased in the serum of patients with chronic hepatitis C with the progression of fibrosis. The aim of this study was to evaluate the clinical significance of the expression of TRX and thioredoxin-binding protein-2 (TBP-2), which is a negative regulator of TRX function, in the liver of patients with chronic hepatitis C and the relationship of this to the efficacy of interferon (IFN) treatment. A retrospective study was performed using the liver biopsy specimens obtained before IFN treatment from 69 patients with chronic serotype 1 hepatitis C virus (HCV) infection. TRX and TBP-2 mRNA levels in the liver biopsy specimens were amplified by real-time RT-PCR. The serum TRX protein level was estimated with a sandwich enzyme-linked immunosorbent assay kit, and the expression of TRX protein in the liver was examined immunohistochemically in 19 patients. There was no association between the serum TRX level and the TRX level in the liver. There was a significant correlation between the expression level of TRX protein in the liver and the TRX mRNA level in the liver. TRX and TBP-2 levels in the liver tended to decrease slightly with increased fibrosis stage, although not significantly. The TRX level in the liver tended to increase with hepatitis activity index, although not significantly. TBP-2 mRNA levels in the liver were significantly higher in responders than non-responders to the IFN therapy (p<0.05). Among patients who had a high viral load of >850 KIU/ml, the TRX level in the livers of non-responders was significantly lower than that in the livers of responders (p<0.05). TRX and TBP-2 mRNA levels in the liver before IFN therapy may predict the outcome of IFN therapy in patients with chronic serotype 1 HCV infection.

Evidence for an age-related attenuation of cerebral microvascular antioxidant response to oxidative stress

Effects of aging and oxidative stress were studied in cerebral microvessels and microvessel-depleted brain from 6-, 18-, and 24-month-old C57Bl/6J mice exposed to normoxia, 24 or 48 h hyperoxia, or 24 h hyperoxia followed by 24 h normoxia. Microvessels lacked smooth muscle and consisted predominantly of endothelium. Following exposure and isolation of microvessel and parenchymal proteins, Western blot analysis was performed for detection of cytosolic thioredoxin 1 (TRx 1) and mitochondrial thioredoxin 2 (TRx 2), protein carbonyl, and mitochondrial superoxide dismutase (MnSOD). Both microvessel and parenchymal TRx 1 levels were increased by hyperoxia; however, the microvascular response was limited and delayed in comparison to that of the parenchymal fraction. Whereas TRx 2 levels in microvessels were increased in older mice, irrespective of exposure condition, hyperoxia per se had little or no apparent effect. Parenchymal cells showed no age-related increase in TRx 2 level under normoxic conditions, but showed increased levels following hyperoxia. Microvessel MnSOD was lower than that in parenchymal cells, but increased with age under normoxia, and also was correlated with the duration of hyperoxia. Although hyperoxia augmented MnSOD levels in young (6 months) and middle-aged (18 months) animals, the response was less pronounced in microvessels from senescent, 24-month-old mice. Unlike microvessels, which showed a sustained age-related increase in MnSOD level under each exposure condition, parenchymal cells from normoxic mice showed no increase, and hyperoxia-induced elevations declined with prolonged 48 h exposure. These results indicate that the microvessel endothelium is (1) subjected to a more intense oxidative environment than neurons and glia and (2) is limited by aging in its ability to respond to oxidative insult.

Antioxidant enzymes in renal cell carcinoma

The aim of the study was to estimate the significance of oxidative/nitrosative damage and expression of antioxidant enzymes in renal cell carcinomas (RCC). For this we investigated immunohistochemically six antioxidant enzymes (AOEs) including MnSOD, ECSOD, thioredoxin, thioredoxin reductase, and gammaglutamyl cysteine synthetase heavy and light chain in 138 RCCs. As an indicator of oxidative/nitrosative damage, sections were stained with an antibody to nitrotyrosine. The extent of apoptosis was evaluated by TUNEL method and proliferation by immunohistochemistry to Ki67. Variable expression of all AOEs could be seen in RCC with expression of MnSOD being strongest. Nitrotyrosine was significantly associated with high grade tumors. MnSOD was associated with tumors of a lower stage. Cases showing ECSOD reactivity had higher and cases expressing thioredoxin lower apoptotic index than other tumors. No association with patient prognosis was observed. According to the results renal cell carcinomas show oxidative/nitrosative damage which, according to nitrotyrosine staining, was higher in high grade tumors. Of AOEs, MnSOD was more abundantly expressed in low stage tumors suggesting that its antioxidant function could play a main role to prevent development of oxidative damage leading to more aggressive tumors.

Holistic and network analysis of meningioma pathogenesis and malignancy

Meningiomas, which originate from arachnoid cells and constitute the largest subgroup of all intracranial tumors, are generally benign, yet have the capacity to progress into a higher histological grade of malignancy associated with an increase in biological aggressivity and/or capacity to recur. To elucidate meningioma pathogenesis and malignancy, we applied a holistic and network approach analyzing cDNA and tissue microarray results. A potential pathway leading to meningioma angiogenesis, apoptosis and proliferation was evidenced as well as a regulatory network of the biomarkers including Ki-67, AR, CD34, P53, c-MYC, etc. which might support clinical research. In this potential pathway, ITGB1 could be the most important "superoncogene" playing a vital role in apoptosis and proliferation, while FOXO3A, MDM4 and MT3 are important to the malignancy process. Some genes are first reported that could explain why radiation induces meningioma and why more female than male patients are affected. Further, we present the hypothesis that HIV-Tat protein might have a close relationship with meningioma pathogenesis and malignancy.

Activity assay of mammalian 2-cys peroxiredoxins using yeast thioredoxin reductase system

2-Cys peroxiredoxin (Prx) is a novel cellular peroxidase that reduces peroxides in the presence of thioredoxin, thioredoxin reductase, and nicotinamide adenine dinucleotide phosphate (NADPH) and that functions in H(2)O(2)-mediated signal transduction. Recent studies have shown that 2-cys Prx can be inactivated by cysteine overoxidation in conditions of oxidative stress. Therefore, peroxidase activity, rather than the protein level, of 2-cys Prx is the more important measure to predict its cellular function. Here, we introduce a modified activity assay method for mammalian 2-cys Prx based on yeast nonselenium thioredoxin reductase. Yeast thioredoxin reductase is expressed in Escherichia coli cells and purified at high yield (40 mg/L of culture broth) as an active flavoprotein by combined diethyl aminoethyl (DEAE) and phenyl hydrophobic chromatography. The optimal concentrations of yeast thioredoxin and thioredoxin reductase required to achieve maximum mammalian 2-cys Prx activity are 3.0 and 1.5 microM, respectively. This modified assay method is useful for measuring 2-cys Prx activity in cell lysates and can also be adapted for a 96-well plate reader for high-throughput screening of chemical compounds that target 2-cys Prx.

Thioredoxin affinity chromatography: a useful method for further understanding the thioredoxin network

Thioredoxin affinity chromatography can be used to recognize the target proteins of thioredoxin or thioredoxin-related proteins in whole cells or certain cellular compartments. In the last couple of years, many potential target proteins have been identified from various organelles and organisms by this method. Based on the information on the target proteins provided by these studies, the complete thioredoxin-related redox networks can now be efficiently described.

The effects of some Mannich bases on heat shock proteins HSC70 and GRP75, and thioredoxin and glutaredoxin levels in Jurkat cells

Mannich bases interact with cellular thiols and inactivate thioredoxin reductase. In this study, the effects of cytotoxic mono-Mannich bases 2, 3 and cyclic Mannich base C1 on the expression of cytoprotective heat shock proteins (HSC70 and GRP75) and on levels of thioredoxin (TRX) and glutaredoxin (GRX) were investigated in Jurkat cells. Cells were exposed to the compounds for 24 h in cell culture medium with 1% FBS. C1 and 2 increased the levels of HSC70 (200% of control) in all the concentrations tested, but 3 did not affect HSC70 levels. Whereas 3 increased GRP75 expression (123-154%), 2 and C1 either did not affect (95-87% for 2, and 88% for C1) or slightly decreased GRP75 expression (82% for 2 and 67% for C1). Mannich bases generally decreased GRX levels (68%, 63-77% and 33-71% for 2, 3 and C1, respectively), but 3 increased GRX levels at 1 microg/ml (142%). Whereas 2 and 3 decreased TRX levels (30-79% and 37-44% of control, respectively), C1 increased the expression of TRX (156-201%). Our results suggest that decreases in GRX and TRX due to the alkylating effects of Mannich bases might have prevented cell division and decreased survival in Jurkat cells, which could not be prevented by increased heat shock protein expression.

Comparative proteome analysis of Mycobacterium tuberculosis grown under aerobic and anaerobic conditions

Data are presented from two-dimensional (2-D) PAGE analysis of Mycobacterium tuberculosis strain Harlingen grown during aerobic and anaerobic culture, according to a modified Wayne dormancy model. M. tuberculosis cultures were grown to the transition point between exponential growth and stationary phase in the presence of oxygen (7 days) and then part of the cultures was shifted to anaerobic conditions for 16 days. Growth declined similarly during aerobic and anaerobic conditions, whereas the ATP consumption rapidly decreased in the anaerobic cultures. 2-D PAGE revealed 50 protein spots that were either unique to, or more abundant during, anaerobic conditions and 16 of these were identified by MALDI-TOF. These proteins were the alpha-crystalline homologue (HspX), elongation factor Tu (Tuf), GroEL2, succinyl-CoA : 3-oxoacid-CoA transferase (ScoB), mycolic acid synthase (CmaA2), thioredoxin (TrxB2), beta-ketoacyl-ACP synthase (KasB), l-alanine dehydrogenase (Ald), Rv2005c, Rv2629, Rv0560c, Rv2185c and Rv3866. Some protein spots were found to be proteolytic fragments, e.g. HspX and GroEL2. These data suggest that M. tuberculosis induces expression of about 1 % of its genes in response to dormancy.

Enrichment of yeast thioredoxin by green tea extract through activation of Yap1 transcription factor in Saccharomyces cerevisiae

Thioredoxin (TRX) is an important antioxidant present in all types of organisms. Besides its role as an antioxidant, TRX protects the gastric mucosa due to its antiinflammatory effect. In addition, TRX decreases allergenicity; therefore, the oral administration of TRX is of considerable interest with respect to its clinical use as well as the development of functional foods containing TRX. We have attempted to enrich the cellular TRX content in Saccharomyces cerevisiae, and found that green tea extract (Sunphenon), which is rich in catechins (polyphenols), activates the Yap1 transcription factor, leading to the induction of TRX2, a target of Yap1. Production of yeast TRX was monitored by both a TRX2-lacZ reporter expression assay and Western blotting using an anti-yeast TRX antibody. Maximal production of TRX was achieved in a medium containing 0.1% green tea extract at pH 7.6. We discuss the underlying mechanism by which green tea extract activates Yap1.

Analysis of the proteins targeted by CDSP32, a plastidic thioredoxin participating in oxidative stress responses

The chloroplastic drought-induced stress protein of 32 kDa (CDSP32) is a thioredoxin induced by environmental stress conditions. To gain insight into the function of CDSP32, we applied two strategies to analyze its targets. First, using affinity chromatography with an immobilized CDSP32 active site mutant, we identified six plastidic targets of CDSP32. Three of them are involved in photosynthetic processes: ATP-ase gamma-subunit, Rubisco and aldolase. The three others participate in the protection against oxidative damage: two peroxiredoxins, PrxQ and the BAS1 2-Cys peroxiredoxin, and a B-type methionine sulfoxide reductase. Then, we developed a novel strategy to trap targets directly in leaf extracts. The method, based on co-immunoprecipitation using extracts from plants overexpressing Wt CDSP32 or CDSP32 active site mutant, confirmed the interaction in vivo between CDSP32 and the PrxQ and BAS1 peroxiredoxins. We showed that CDSP32 is able to form heterodimeric complexes with PrxQ and that the peroxiredoxin displays CDSP32-dependent peroxidase activity. Under photooxidative stress induced by methyl viologen, plants overexpressing CDSP32 active site mutant exhibit decreased maximal PSII photochemical efficiency and retain much less chlorophyll compared with Wt plants and with plants overexpressing Wt CDSP32. We propose that the increased sensitivity results from trapping in planta of the targets involved in the protection against oxidative damage. We conclude that CDSP32, compared with other plant thioredoxins, is a thioredoxin more specifically involved in plastidic responses against oxidative stress.

Characterization of plastidial thioredoxins from Arabidopsis belonging to the new y-type

The plant plastidial thioredoxins (Trx) are involved in the light-dependent regulation of many enzymatic activities, owing to their thiol-disulfide interchange activity. Three different types of plastidial Trx have been identified and characterized so far: the m-, f-, and x-types. Recently, a new putative plastidial type, the y-type, was found. In this work the two isoforms of Trx y encoded by the nuclear genome of Arabidopsis (Arabidopsis thaliana) were characterized. The plastidial targeting of Trx y has been established by the expression of a TrxGFP fusion protein. Then both isoforms were produced as recombinant proteins in their putative mature forms and purified to characterize them by a biochemical approach. Their ability to activate two plastidial light-regulated enzymes, NADP-malate dehydrogenase (NADP-MDH) and fructose-1,6-bisphosphatase, was tested. Both Trx y were poor activators of fructose-1,6-bisphosphatase and NADP-MDH; however, a detailed study of the activation of NADP-MDH using site-directed mutants of its regulatory cysteines suggested that Trx y was able to reduce the less negative regulatory disulfide but not the more negative regulatory disulfide. This property probably results from the fact that Trx y has a less negative redox midpoint potential (-337 mV at pH 7.9) than thioredoxins f and m. The y-type Trxs were also the best substrate for the plastidial peroxiredoxin Q. Gene expression analysis showed that Trx y2 was mainly expressed in leaves and induced by light, whereas Trx y1 was mainly expressed in nonphotosynthetic organs, especially in seeds at a stage of major accumulation of storage lipids.

Suboptimal action of NF-kappaB in Fanconi anemia cells results from low levels of thioredoxin

Electrophoretic mobility shift assays (EMSA) revealed that under standard cell culture conditions NF-kappaB was induced in Fanconi anemia fibroblasts in contrast to control cells. Dithiothreitol, a potent synthetic redox potential-delivering compound, when added to growing cells, prevented this induction of NF-kappaB and, simultaneously, chromosomal instability was reduced. Fanconi anemia cells possess low endogenous levels of the naturally occurring antioxidant thioredoxin. Transfection of Fanconi anemia cells with thioredoxin cDNA containing a nuclear localization signal prevented both spontaneous as well as mitomycin C-induced chromosomal instability. A promotor construct with two NF-kappaB binding sites in front of the CAT gene induced little CAT expression in cells with low thioredoxin content in spite of induced NF-kappaB. In cells with higher thioredoxin content CAT expression was increased. Cotransfection of the NF-kappaB-dependent CAT plasmid with the Trx/nuc-plasmid into FA fibroblasts increased the CAT expression to almost that of control cells, indicating that in this model system with diminished thioredoxin content NF-kappaB requires thioredoxin for binding to its specific promotor. Since Fanconi anemia cells have low thioredoxin contents, NF-kappaB-dependent genes are expressed insufficiently. This explains part of the pathophysiological processes observed in Fanconi anemia.

Active recombinant thioredoxin h protein with antioxidant activities from sweet potato (Ipomoea batatas [L.] Lam Tainong 57) storage roots

Recombinant thioredoxin h (Trx2) overproduced in Escherichia coli (M15) was purified by Ni2+-chelated affinity chromatography. The molecular mass of Trx2 is approximately 1.4 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Total antioxidant status, 1,1-diphenyl-2-picrylhydrazyl (DPPH) staining, reducing power method, Fe2+-chelating ability, ferric thiocyanate (FTC) method, and protection of calf thymus DNA against hydroxyl radical-induced damage were studied. The thioredoxin h protein with a concentration of 12.5 mg/mL exhibited the highest activity (expressed as 0.37 +/- 0.012 mM ABTS* radical cation being cleared) in a total antioxidant status test. In the DPPH staining thioredoxin h appeared as white spots when it was diluted to 50 mg/mL (a final amount of 15 microg). Like the total antioxidant status, the reducing power, Fe2+-chelating ability, FTC activity, and protection against hydroxyl radical-induced calf thymus DNA damage were found with the thioredoxin h protein. It was suggested that thioredoxin h might contribute to its antioxidant activities against hydroxyl and peroxyl radicals.

Functional proteomics of neurokinin B in the placenta indicates a novel role in regulating cytotrophoblast antioxidant defences

Neurokinin B (NKB) has recently been demonstrated to be secreted from the placenta in abnormally high amounts in preeclampsia (PE) and to cause hypertension in rats, suggesting it may be a mediator of some pathophysiological features of PE. It is also known that NKB receptors exist in the placenta. To determine the effect of high levels of NKB on the placenta, we have performed proteomics on five separate preparations of cultured purified human term cytotrophoblast cells. The results showed a statistically significant decrease in 20 proteins, of which five were unknown proteins. Proteins important in antioxidant defenses that decreased were thioredoxin, cyclophilin A, cytokeratin 1, and peroxiredoxin 5. Two proteins that inhibit intravascular anticoagulation, cytokeratin 1 and annexin 11 were also decreased. Pathways involving pro-inflammatory cytokine activation of NF-kappa B are opposed by Raf kinase inhibitor protein, which was also decreased. Cofilin 1, a protein involved in defense against bacteria, was also decreased. Among other proteins that were suppressed by NKB were proteasome proteins, desmoplakin, and calgizzarin. Western blots confirmed the decrease in cytokeratin 1 and cyclophilin A protein after NKB exposure. In PE, there is reduced antioxidant activity and increased intravascular coagulation. The findings that high levels of NKB, similar to those observed in PE, can impair these two classes of activity support the hypothesis that high NKB levels may contribute to the pathogenesis of PE.

Differentiation-associated redox-regulation in human B cell lines from stem cell/pro-B to plasma cell

Redox-regulation of receptors and transcription factors are important for lymphocyte activation, differentiation and apoptosis. Thioredoxin (Trx) is a key redox-regulating protein and oxidative stress sensor operating in synergy with Trx-reductase and protein disulfide isomerase (PDI). The expression of Trx, PDI, and the Trx-regulated transcription-factor Pax5 were analyzed in a panel of human B cell lines and were compared with that of the Bcl-2 family proteins, also redox-controlled. The panel included representative cells from various stages: FLEB14-4 (pro-B); REH and NALM-6 (pre-B); Rael and Daudi (small mature B); U-698 and NC0467.3 (B-blasts); LP-1, U-1996, and U-266 (plasma cells). We found a significant congruence and co-variation of Trx and Bcl-2 levels in the B-lineage, with high expression levels in early stages (pro-B and pre-B) and in the late stage representing terminally-differentiated plasma cells, whereas mid-stage small resting B cells showed a very low expression. PDI increased significantly in plasma-blasts and plasma cells, indicating its importance in the highly specialized immunoglobulin assembly-machinery, including disulfide-bond isomerization. Pax5 was expressed in early and mid-stages, but was silenced in terminal stages. We conclude that the high Trx and Bcl-2-expression early and late in the B cell maturation pathway reflects a redox-strategy favoring an increased survival potential of the B cells at those stages.

Determination of the electron relaxation rates in paramagnetic metal complexes: applicability of available NMR methods

Four different approaches for determining the electron relaxation rates in paramagnetic metallo-proteins are investigated, using a paramagnetic Ni2+ complex of a protein as an example. All four approaches rely on the determination of the longitudinal paramagnetic relaxation enhancements, R1p, of the 1H nuclei and the backbone 15N nuclei. Three of the methods utilize the field dependence of the R1p rates. It is found that the applicability of each of these methods depends on whether the fast-motion condition, omegaS2tau2<<1, applies to the electron relaxation, omegaS being the Larmor frequency of the electron spin S and tau the correlation time of the electron relaxation. If the fast-motion condition is fulfilled, the electron relaxation rate can be obtained from the ratio of the R1p rates of one or more protons at two magnetic field strengths (method A). On the other hand, if the fast-motion condition does not apply, more elaborate methods must be used that, in general, require a determination of the R1p rates over a larger range of magnetic field strengths (method C). However, in the case of paramagnetic metal ions with relatively slow electron relaxation rates only two magnetic field strengths suffice, if the R1p rates of a hetero nucleus are included in the analysis (method B). In the fourth method (method D), the electron relaxation is estimated as a parameter in a structure calculation, using distance constraints derived from proton R1p rates at only one magnetic field strength. In general, only methods B and C give unambiguous electron relaxation rates.

Immunohistochemical evaluation of oxidative stress markers in chronic hepatitis C

Oxidative stress (OS) plays a major role in chronic hepatitis C. Various OS markers have been found to be elevated in hepatitis C virus (HCV)-related liver disease. This study detected the presence of OS in serum and liver biopsy specimens of HCV patients. Reactive oxygen molecules (ROM) in sera of 54 HCV patients were compared with 23 controls. OS markers 8-hydroxydeoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal, malondialdehyde, and thioredoxin were measured in liver biopsy specimens of 18 HCV patients with fibrosis staging F1 (six); F2 (two), F3 (four), and F4 (six). The interferon (IFN) response and hepatocellular carcinoma (HCC) occurrence in the presence of OS markers were also evaluated. The level of ROM in HCV patients was 318 +/- 56.7 Carr compared with 248 +/- 40.8 Carr in controls (p=0.032). Multivariate analysis found age (p=0.0236) to be the only independent variable associated with increase in ROM in sera. In liver biopsy specimens, OS markers were found mainly around the area of piecemeal necrosis or the periportal area. The presence of OS markers seemed to increase with fibrosis staging, although not significantly. The OS DNA damage marker 8-OHdG was detected in the nucleus of hepatocytes. Thirteen patients received IFN therapy. During the 4-year follow-up period, HCC developed in four nonresponders to IFN and in one untreated patient. OS markers were stained in both HCC cells and non-HCC cells in HCC patients. OS markers were found in serum and liver specimens of HCV-associated liver disease and in HCC tissue. Detection of OS markers may be important for monitoring disease progression in HCV patients. Antioxidant therapy in combination with antiviral therapy may minimize liver damage and aid in the prevention and subsequent development of HCC.

Enhanced oxidative stress and impaired thioredoxin expression in spontaneously hypertensive rats

As oxidative stress plays a crucial role in the development and pathogenesis of hypertension, we analyzed the redox (reduction/oxidation) status in tissues from Wistar-Kyoto rats (WKY), spontaneously hypertensive rats (SHR), and stroke-prone SHR (SHRSP). Expressions of 8-hydroxy-2'-deoxyguanosine, a marker for oxidative stress-induced DNA damage, and protein carbonylation, a marker for oxidation status of proteins, were enhanced in aorta, heart, and kidney from SHR and SHRSP compared with WKY. The expression of redox regulating protein, thioredoxin (TRX), estimated by immunohistochemistry and western blot, and expression of TRX gene estimated by real-time RT-PCR were markedly suppressed in those tissues from SHR and SHRSP compared with WKY. Induction of TRX was impaired after angiotension II treatment in peripheral blood mononuclear cells isolated from SHR and SHRSP compared with those isolated from WKY. Although previous reports have shown that TRX is induced by a variety of oxidative stress in tissues, the present study shows the impaired induction of TRX in tissues from genetically hypertensive rats despite the relative increment of oxidative stress. Redox imbalance in essential organs may play a crucial role in the development and pathogenesis of hypertension.

Expression of the thioredoxin system in interstitial lung disease

The thioredoxin system containing thioredoxin (Trx) and thioredoxin reductase (TrxR) has profound effects on cell proliferation and protection against exogenous oxidants. The significance of the Trx system in human lung and lung diseases is, however, largely unresolved. Altogether, 66 specimens of human lung were investigated by immunohistochemistry for their expression of Trx and TrxR. The diseases included interstitial pneumonias such as usual interstitial pneumonia (UIP), desquamative interstitial pneumonia (DIP), and UIP associated with collagen vascular diseases (CVD-ILD), and granulomatous diseases such as sarcoidosis and allergic alveolitis. The ultrastructural localization of Trx and TrxR was analysed by immunoelectron microscopy. In healthy lung, Trx and TrxR were expressed in bronchial epithelium and alveolar macrophages. Trx and TrxR were highly concentrated in areas of metaplastic epithelium in UIP and in alveolar macrophages in DIP, though fibrotic areas in UIP were mainly negative. The expression of both enzymes was clearly weaker in CVD-ILD than in UIP. Granulomas of sarcoidosis showed moderate to intense Trx immunoreactivity. Ultrastructurally, Trx and TrxR were expressed diffusely in the cytosolic compartment and plasma membrane of metaplastic type II pneumocytes, macrophages, and bronchial epithelial cells. This study highlights the importance of Trx and TrxR in primary defence in bronchial epithelium, alveolar epithelium, and macrophages in human lung, but also indicates that elevated expression of these proteins may serve as markers of ongoing cell regeneration and inflammation.

Quantification of thioredoxin mRNA expression in the rat hippocampus by real-time PCR following oxidative stress

Thioredoxin (Trx) is a multifunctional protein with a redox-active disulfide/dithiol in the active site. Thioredoxin, with its redox-regulating and reactive oxygen species (ROS) scavenging activities, plays several important biologic roles both in intracellular and extracellular compartments. The purpose of this report was to quantify the relative expression of Trx in rat hippocampus following an oxidative stress-involving treatment such as kainic acid (KA) using real-time PCR and the 2(-DeltaDeltaC(T)) method. The relative changes in expression of Trx mRNA in KA-treated and control animals were significantly different as 2.02 +/- 0.77 and 1.0 +/- 0.26, respectively (P<0.05). Minimum and maximum n-fold changes in Trx expression in KA-treated and control animals were determined as (1.4-5.2) and (0.8-1.3), respectively. Thus, real-time PCR and the 2(-DeltaDeltaC(T)) method for data analysis from real-time PCR were found to be an accurate and sensitive method for quantifying Trx mRNA levels.

Cloning and developmental analysis of murid spermatid-specific thioredoxin-2 (SPTRX-2), a novel sperm fibrous sheath protein and autoantigen

Thioredoxins compose a growing family of proteins that participate in different cellular processes via redox-mediated reactions. We report here the cloning, developmental expression, and location of murid Sptrx-2. Mouse and rat SPTRX-2 proteins display a high homology to their human ortholog in the thioredoxin and NDP kinase domains, and the coding genes are located at syntenic positions. Northern blotting and in situ hybridization confirmed the testis-specific expression of murine Sptrx-2 mRNA, mostly in round spermatids. Immunohistochemical analysis of the 19 steps of rat spermiogenesis showed that SPTRX-2 expression becomes prominent in the cytoplasmic lobe of step 15-18 spermatids and diminishes in step 19 just before spermiation. However, in the spermatid tail, SPTRX-2 immunoreactivity increased from step 15 to 19 and was confined to the principal piece. By immunogold electron microscopy, SPTRX-2 was first detected scattered throughout the cytoplasm of the axoneme in step 14-15 spermatids, but began to be incorporated by step 16 into the fibrous sheath (FS). During steps 17-18, the labeling increased over the ribs and columns of the assembled FS. It peaked in step 19 and remained in the FS of epididymal spermatozoa. Immunoblots of isolated FS obtained from spermatozoa confirmed that SPTRX-2 is an integral component of the FS and a post-obstruction autoantigen in vasectomized rats. Our data indicate that SPTRX-2 incorporation into the FS lags well behind FS assembly, suggesting it is required during the final stages of sperm tail maturation in the testis and/or epididymis, where extensive disulfide bonding of FS proteins occurs.

Levels of oxidative stress and redox-related molecules in the placenta in preeclampsia and fetal growth restriction

Recent evidence suggests that oxidative stress is involved in the pathophysiology of preeclampsia. Using immunohistochemistry and Western blotting, we investigated the oxidative stress- and redox-related molecules, such as 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE), thioredoxin (TRX) and redox factor-1 (ref-1) in the placenta in preeclampsia, intrauterine growth restriction (IUGR), preeclampsia + IUGR and in normal pregnancy. Using immunohistochemistry, the level of 8-OHdG was significantly higher in IUGR ( P=0.012) or preeclampsia + IUGR (P=0.0021) than in normal pregnancy, while TRX expression was significantly higher in preeclampsia (P=0.045), and ref-1 expression was significantly higher in preeclampsia (P=0.017), IUGR (P=0.016) and preeclampsia + IUGR (P=0.0038) than in normal pregnancy. The levels of 4-HNE did not differ significantly between either preeclampsia or IUGR and normal pregnancy. A significant positive correlation was observed between TRX and ref-1 expressions in both normal (rho=0.52) and complicated (rho=0.43) pregnancies. Using Western blotting, ref-1 expression tended to be higher in complicated pregnancies than in normal pregnancy (P=0.09). These results suggest that oxidative DNA damage is increased in IUGR and that redox function is enhanced in both preeclampsia and IUGR compared with normal pregnancy.

Identification of metabolic enzymes in renal cell carcinoma utilizing PROTEOMEX analyses

PROTEOMEX, an approach which combines conventional proteome analysis with serological screening, is a powerful tool to separate proteins and identify immunogenic components in malignant diseases. By applying this approach, we characterized nine metabolic enzymes which were differentially expressed in renal cell carcinoma (RCC) cell lines and compared their expression profiles to that of normal kidney epithelium cells. Four of these proteins, superoxide dismutase (SODC), triosephosphatase isomerase (TPIS), thioredoxin (THIO) and ubiquitin carboxyl-terminal hydrolase (UBL1) were further analysed for both their constitutive and interferon (IFN)-gamma inducible protein expression pattern in cell lines or tissue specimens derived from RCC or normal kidney epithelium using Western blot analysis and immunohistochemistry, respectively. With the exception of the RCC cell line MZ1940RC, which completely lacks the expression of UBL1, a heterogeneous and variable expression pattern of the different metabolic enzymes was detected in RCC and normal renal epithelium. The highest differences in the expression levels were found for THIO in the RCC cell lines, which was 2-fold upregulated when compared to autologous normal kidney epithelium. Moreover, IFN-gamma treatment did not influence the constitutive expression of these metabolic enzymes. Thus, PROTEOMEX represents a valuable approach for the identification of metabolic enzymes which might be used as markers for the diagnosis of RCC.

Cutaneous arteriolar thioredoxin expression in patients with heart failure

Cutaneous microangiopathic lesions exist in patients with heart failure, and heart failure is associated with increased oxidative stress. Thioredoxin (TRX) is stress-inducible and has a cytoprotective effect against oxidative stress. Accordingly, to investigate whether arteriolar TRX expression was increased in the skin of patients with congestive heart failure (CHF), skin biopsies were taken at the time of cardiac catheterization, and the results were compared with those of control subjects. The diagnosis of CHF was done by cardiac catheterization with reference to elevated plasma concentrations of TRX and brain natriuretic peptide (BNP). Increased TRX expression was found in the skin biopsies of 29 of the 35 patients with CHF, but in none of the 8 control subjects; the semiquantitative grade of arteriolar TRX immunoreactivity was 2.5+/-1.0 in patients with CHF and 1.0+/-0.0 in controls, respectively (p<0.01). The severity of arteriolar TRX expression did not correlate with the New York Heart Association functional class. These results indicate that cutaneous arteriolar TRX expression in patients with CHF may reflect the excessive oxidative stress of the peripheral circulation associated with the condition.

Intact protein analysis by matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry

Direct tandem mass spectrometric (MS/MS) analysis of small, singly charged protein ions by tandem time-of-flight mass spectrometry (TOFMS) is demonstrated for proteins up to a molecular mass of 12 kDa. The MALDI-generated singly charged precursor ions predominantly yield product ions resulting from metastable fragmentation at aspartyl and prolyl residues. Additional series of C-terminal sequence ions provide in some cases sufficient information for protein identification. The amount of sample required to obtain good quality spectra is in the high femtomolar to low picomolar range. Within this range, MALDI-MS/MS using TOF/TOF trade mark ion optics now provides the opportunity for direct protein identification and partial characterization without prior enzymatic hydrolysis.

Gene expression profiling of androgen deficiency predicts a pathway of prostate apoptosis that involves genes related to oxidative stress

Androgens are critical for prostate development, growth, and functions. In general, they support proliferation and prevent cell death of prostatic epithelial cells. Here, we studied changes of gene expression after castration and testosterone replacement therapy in the rat ventral prostate using cDNA microarrays analysis. We could identify 230 genes that were regulated in either experimental condition. Using hierarchical clustering analysis, different groups of genes could be detected according to their expression pattern. This enabled us to distinguish the putative androgen-responsive genes from the secondary-responsive ones. Among genes that altered during castration and testosterone replacement, a set of oxidative stress-related genes, including thioredoxin, peroxiredoxin 5, superoxide dismutase 2, glutathione peroxidase 1, selenoprotein 15 kDa, microsomal glutathione-S-transferase, glutathione reductase, and epoxide hydrolase, were changed by castration. We hypothesize that modulation of redox status can be a factor of relevance in androgen withdrawal-induced prostate apoptosis. In selective cases, quantitative RT-PCR was used to confirm changes in gene expression. Immunohistochemistry was performed to detect thioredoxin and ezrin. Both of these were detected in the prostate and seem to be regulated in a similar manner as shown by gene expression analysis. In conclusion, gene expression profiling provides a unique opportunity for understanding the molecular mechanisms of androgen actions in prostate gland.

Successful immunoglobulin treatment for fulminant myocarditis and serial analysis of serum thioredoxin: a case report

A 31-year-old woman suspected to have acute myocarditis was admitted to hospital and was managed with intra-aortic balloon pumping and a percutaneous cardiopulmonary support system because of sustained ventricular tachycardia. After immunoglobulin treatment, cardiac function and systematic inflammation were improved. The left ventricular endomyocardial biopsy revealed massive necrosis and degeneration of myocardial cells, and extensive infiltration of inflammatory cells. The clinicopathology of this patient was thought to be fulminant myocarditis. Serial serum thioredoxin (TRX) analysis showed that the serum level was high during the acute phase, and decreased during the chronic phase. Immunohistochemistry for TRX in the biopsy samples showed that inflammatory cells and cardiomyocytes were positively stained.

Molecular and enzymatic characterisation of Schistosoma mansoni thioredoxin

Defense against oxidative damage can be mediated through glutathione and/or thioredoxin utilising systems. Here, we report the identification and characterisation of a thioredoxin from Schistosoma mansoni. The predicted protein has similarity to previously characterised thioredoxins including conservation of the redox active site. Recombinant six-histidine tagged schistosome thioredoxin had insulin reduction activity and supported the enzymatic function of thioredoxin reductase and thioredoxin peroxidase. By Western blotting, all mammalian stages of the schistosome lifecycle expresses thioredoxin. Thioredoxin is present in egg secretory products and antibodies against the recombinant protein produce the circumoval precipitin reaction. This is the first identification of defined antigen producing this reaction. Furthermore, thioredoxin is a novel egg immunogen as it elicits an antibody response in schistosome-infected mice. The most significant IgG production against thioredoxin occurs after parasite oviposition commences. These observations suggest that thioredoxin participates in processes vital to the parasite and may facilitate the passage and survival of eggs across inflamed host tissues.

Enzyme-linked immunospot assay for detection of thioredoxin and thioredoxin reductase secretion from cells

Oxidative stress response was determined in this study by enzyme-linked immunospot (ELISpot) assays for thioredoxin (Trx) and Trx reductase (TrxR). On exposure to oxidative stress, cells can launch a variety of defense mechanisms, including release of antioxidant proteins. The Trx system, consisting of Trx, TrxR, and NADPH, constitutes one of these cellular defense systems for maintenance of a healthy reduction-oxidation (redox) balance. Trx and TrxR are rapidly upregulated and released from monocytes, lymphocytes, and other normal and neoplastic cells on exposure. Secreted Trx and TrxR have proved to be eminent indicators of oxidative stress. Trx is a small, 12-kDa protein released through a leaderless pathway, whereas TrxR, which is a 116-kDa selenoprotein and required for regeneration of Trx, is secreted through the Golgi pathway. In this chapter we present a detailed laboratory bench protocol for enumeration of single cells secreting redox-active Trx and TrxR after oxidative stress exposure. Physiological stimuli (such as interferon gamma, lipopolysaccharide, interleukin 1, and CD23 ligation; and phorbol 12-myristate 13-acetate and ionophore) as well as UV light and hydrogen peroxide were used to generate oxidative stress, and some are presented in detail. The protocol includes a description of cell isolation, preparation, handling, and development of ELISpot plates, troubleshooting notes, presentation of results, statistical evaluation, and comments on alternative sources of materials and manufacturer Web addresses. We concluded that the ELISpot assay is a useful method for detection of single cells secreting the redox-active proteins Trx and TrxR after oxidative stress exposure.