ATL-derived factor (ADF), an IL-2 receptor/Tac inducer homologous to thioredoxin; possible involvement of dithiol-reduction in the IL-2 receptor induction

Selective redox regulation of cytokine receptor signaling by extracellular thioredoxin-1

The thiol-disulfide oxidoreductase thioredoxin-1 (Trx1) is known to be secreted by leukocytes and to exhibit cytokine-like properties. Extracellular effects of Trx1 require a functional active site, suggesting a redox-based mechanism of action. However, specific cell surface proteins and pathways coupling extracellular Trx1 redox activity to cellular responses have not been identified so far. Using a mechanism-based kinetic trapping technique to identify disulfide exchange interactions on the intact surface of living lymphocytes, we found that Trx1 catalytically interacts with a single principal target protein. This target protein was identified as the tumor necrosis factor receptor superfamily member 8 (TNFRSF8/CD30). We demonstrate that the redox interaction is highly specific for both Trx1 and CD30 and that the redox state of CD30 determines its ability to engage the cognate ligand and transduce signals. Furthermore, we confirm that Trx1 affects CD30-dependent changes in lymphocyte effector function. Thus, we conclude that receptor–ligand signaling interactions can be selectively regulated by an extracellular redox catalyst.

From oxygen sensing to heart failure: role of thioredoxin

Oxidative stress has been widely recognized to be involved in the pathogenesis of cardiopulmonary disorders. In ischemic heart diseases, it is involved not only in the development of atherosclerosis but also in ongoing ischemic injury, especially in the reperfusion process. Cardiomyopathy is another cardiac disorder in which oxidative stress is involved. In diabetic cardiomyopathy, homocysteine, a well-known source of oxidative stress, is believed to play major roles in its development. Thioredoxin (TRX) is a redox-acting protein ubiquitously present in the human body. It also is inducible by a wide variety of oxidative stresses. TRX is a multifunctional protein and has anti-inflammatory and antiapoptotic effects, as well as antioxidative effects. It is therefore feasible to think that TRX is a potential therapy for cardiac disease. Moreover, serum TRX is a well-recognized biomarker of various diseases involving oxidative stress, and this is also the case for cardiac disorders. Here we discuss how TRX is useful as a biomarker of and therapeutic agent for cardiopulmonary disorders, especially focusing on ischemic heart disease, myocarditis and oxygen sensing, and acute respiratory distress syndrome.

Thioredoxins in chloroplasts

Thioredoxins (TRXs) are small disulfide oxidoreductases of ca. 12 kDa found in all free living organisms. In plants, two chloroplastic TRXs, named TRX f and TRX m, were originally identified as light dependent regulators of several carbon metabolism enzymes including Calvin cycle enzymes. The availability of genome sequences revealed an unsuspected multiplicity of TRXs in photosynthetic eukaryotes, including new chloroplastic TRX types. Moreover, proteomic approaches and focused studies allowed identification of 90 potential chloroplastic TRX targets. Lately, recent studies suggest the existence of a complex interplay between TRXs and other redox regulators such as glutaredoxins (GRXs) or glutathione. The latter is involved in a post-translational modification, named glutathionylation that could be controlled by GRXs. Glutathionylation appears to specifically affect the activity of TRX f and other chloroplastic enzymes and could thereby constitute a previously undescribed regulatory mechanism of photosynthetic metabolism under oxidative stress. After summarizing the initial studies on TRX f and TRX m, this review will focus on the most recent developments with special emphasis on the contributions of genomics and proteomics to the field of TRXs. Finally, new emerging interactions with other redox signaling pathways and perspectives for future studies will also be discussed.

Release of thioredoxin from Saccharomyces cerevisiae with environmental stimuli: solubilization of thioredoxin with ethanol

Thioredoxin is crucial for the maintenance of the redox status of cells of all types. Mammalian thioredoxin is secreted from various types of cells, although the mechanism underlying has not yet been clarified. Previously, we demonstrated that thioredoxin was released from Saccharomyces cerevisiae after treatment with ethanol. In this paper, we show that as well as ethanol, low-pH shock and hypoosmotic shock release thioredoxin. Low-molecular-weight proteins in yeast cells were preferentially released by treatment with ethanol and low-pH shock. A cell wall integrity pathway seems partially involved in the hypoosmotic shock-induced release of thioredoxin. Considerable amounts of thioredoxin were present in the insoluble fractions of the cells, a portion of which was associated with lipid microdomains that are resistant to nonionic detergent at 4 degrees C. The intracellular localization of thioredoxin may influence the efficiency of its release from yeast cells with ethanol.

Thioredoxin prevents the development and progression of elastase-induced emphysema

Thioredoxin 1 (TRX1) is a redox (reduction/oxidation)-active protein that scavenges reactive oxygen species. Here we examined whether endogenous or exogenous administration of TRX1 prevented the development and progression of elastase-induced pulmonary emphysema. Mice were treated with intratracheal elastase via microspray on day 0, and were given recombinant human TRX1 (rhTRX1) every other day from days -1 to 21. To determine the effects of TRX1 on the progression of established emphysema, mice were treated intratracheally with elastase on day 0, and rhTRX1 was administered from days 14 to 21. Histopathologic examination was performed on day 21. TRX1-transgenic but not transgene-negative mice demonstrated a decrease in the physiological indicators of elastase-induced emphysema. TRX1 administration from days -1 to 19 significantly decreased the signs of elastase-induced emphysema. Moreover, TRX1 administration beginning 14 days after elastase treatment significantly slowed the progression of emphysema. TRX1 may be of clinical benefit for the treatment of COPD.

Delay of photoreceptor degeneration intubbymouse by sulforaphane

In this study, the homozygous tubby (tub/tub) mutant mouse, with an early progressive hearing loss and photoreceptor degeneration, was used as a model system to examine the effects of systemic administration of a naturally occurring isothiocyanate, sulforaphane (SF), on photoreceptor degeneration. Several novel observations have been made: (i) the mRNA and protein expression of thioredoxin (Trx), thioredoxin reductase (TrxR) and NF-E2-related factor-2 (Nrf2) were significantly reduced even prior to photoreceptor cell degeneration in the retinas of tub/tub mice, suggesting that retinal expression of the Trx system is impaired and that Trx regulation is involved in the pathogenesis of retinal degeneration in this model, (ii) intraperitoneal injection with SF significantly up-regulated retinal levels of Trx, TrxR, and Nrf2, and effectively protected photoreceptor cells in tub/tub mice as evaluated functionally by electroretinography and morphologically by quantitative histology, and (iii) treatment with PD98059, an inhibitor of extracellular signal-regulated kinases (ERKs), blocked SF-mediated ERKs activation and up-regulation of Trx/TrxR/Nrf2 in the retinas of tub/tub mice. This suggests that ERKs and Nrf2 are involved in the mechanism of SF-mediated up-regulation of the Trx system to protect photoreceptor cells in this model. These novel findings are significant and could provide important information for the development of a unique strategy to prevent sensorineural deafness/retinal dystrophic syndromes and also other forms of inherited neurological disorders.

Oxygen sensing and redox signaling: the role of thioredoxin in embryonic development and cardiac diseases

It is important to regulate the oxygen concentration and scavenge oxygen radicals throughout the life of animals. In mammalian embryos, proper oxygen concentration gradually increases in utero and excessive oxygen is rather toxic during early embryonic development. Reactive oxygen species (ROS) are generated as by-products in the respiratory system and increased under inflammatory conditions. In the pathogenesis of a variety of adult human diseases such as cancer and cardiovascular disorders, ROS cause an enhancement of tissue injuries. ROS promote not only the development of atherosclerosis but also tissue injury during the reperfusion process. The thioredoxin (TRX) system is one of the most important mechanisms for regulating the redox balance. TRX is a small redox active protein distributed ubiquitously in various mammalian tissues and cells. TRX acts as not only an antioxidant but also an anti-inflammatory and an antiapoptotic protein. TRX is induced by oxidative stress and released from cells in response to oxidative stress. In various human diseases, the serum/plasma level of TRX is a well-recognized biomarker of oxidative stress. Here we discuss the roles of TRX on oxygen stress and redox regulation from different perspectives, in embryogenesis and in adult diseases focusing on cardiac disorders.

Dual localization: proteins in extracellular and intracellular compartments

The goal of this article is to provide a comprehensive catalog of those proteins documented to exhibit dual localization, being found in both the extracellular compartment (cell surface and extracellular medium) as well as the intracellular compartment (cytosol and nucleus). A large subset of these proteins that show dual localization is found both in the nucleus and outside of cells. Proteins destined to be secreted out of the cell or to be expressed at the cell surface usually enter the endomembrane pathway on the basis of a signal sequence that targets them into the endoplasmic reticulum. Proteins destined for import into the nucleus, on the other hand, usually carry a nuclear localization signal. We have organized our catalog in terms of the presence and absence of these trafficking signals: (a) proteins that contain a signal sequence but no nuclear localization signal; (b) proteins that contain both a signal sequence as well as a nuclear localization signal; (c) proteins that contain a nuclear localization signal but lack a signal sequence; and (d) proteins containing neither a signal sequence nor a nuclear localization signal. Novel insights regarding the activities of several classes of proteins exhibiting dual localization can be derived when one targeting signal is experimentally abrogated. For example, the mitogenic activity of both fibroblasts growth factor-1 and schwannoma-derived growth factor clearly requires nuclear localization, independent of the activation of the receptor tyrosine kinase signaling pathway. In addition, there is a growing list of integral membrane receptors that undergo translocation to the nucleus, with bona fide nuclear localization signals and transcription activation activity. The information provided in this descriptive catalog will, hopefully, stimulate investigations into the pathways and mechanisms of transport between these compartments and the physiological significance of dual localization.

Structural and Functional Analysis of Hypothetical Proteins in Mouse Hippocampus from Two-Dimensional Gel Electrophoresis

Protein profiling in five individual mouse strains showed strain-specific expression of three hypothetical proteins (HPs). As functional and structural assignment of HPs were based on predictions and low identity to known structures, HPs were identified by MALDI-TOF/TOF, and their proposed tentative function was determined by enzyme assays. Three identified HPs were extracted from gels and renatured, and pyridoxal phosphate phosphatase, inorganic pyrophosphate phosphatase, and antioxidant activities were revealed, findings in agreement with functional predictions.

Thioredoxin and related molecules--from biology to health and disease

Thioredoxin and glutaredoxin systems in mammalian cells utilize thiol and selenol groups to maintain a reducing intracellular redox state acting as antioxidants and reducing agents in redox signaling with oxidizing reactive oxygen species. During the last decade, the functional roles of thioredoxin in particular have continued to expand, also including novel functions such as a secreted growth factor or a chemokine for immune cells. The role of thioredoxin and glutaredoxin in antioxidant defense and the role of thioredoxin in controlling recruitment of inflammatory cells offer potential use in clinical therapy. The fundamental differences between bacterial and mammalian thioredoxin reductases offer new principles for treatment of infections. Clinical drugs already in use target the active site selenol in thioredoxin reductases, inducing cell death in tumor cells. Thioredoxin and binding proteins (ASK1 and TBP2) appear to control apoptosis or metabolic states such as carbohydrate and lipid metabolism related to diseases such as diabetes and atherosclerosis.

Increased oxidative stress with elevated serum thioredoxin level in patients with coronary spastic angina

BACKGROUND

Increased oxidative stress has been implicated in the pathogenesis of coronary vasospasm. Thioredoxin (TRX) is a redox-active protein that is known to be induced by oxidative stress.

HYPOTHESIS

The serum TRX level may be high in patients with coronary vasospasm.

METHODS

The serum TRX level was determined using an enzyme-linked immunosorbent assay in 21 patients with the active stage of coronary spastic angina (CSA), in 18 patients with the inactive stage of CSA (iCSA), in 24 control subjects without coronary artery disease (Control), and in 20 patients with stable effort angina (SEA).

RESULTS

Serum TRX levels (mean +/- standard deviation ng/ml) were significantly higher in CSA (64 +/- 44) than in iCSA (28 +/- 26), in Control (34 +/- 15), and in SEA (36 +/- 16). In contrast, serum alpha-tocopherol levels (mg/g lipids) were significantly lower in CSA (2.8 +/- 0.7) than in Control (4.0 +/- 1.2) and in SEA (3.2 +/- 0.4). Current smoking was significantly more prevalent in CSA (76%) than in any of the other groups. No significant correlation was found between the serum level of TRX and alpha-tocopherol in the study subjects. In nine patients with CSA, the serum TRX level decreased (93 +/- 41 --> 41 +/- 35 ng/ml) and the alpha-tocopherol level increased (2.7 +/- 0.6 --> 3.2 +/- 0.7 mg/g lipids) significantly under medication with calcium entry blockers after an at least 3-month angina-free period.

CONCLUSIONS

Patients with coronary spastic angina had a higher serum TRX level associated with a lower serum level of antioxidant vitamin E, with redox equilibrium appearing to be related to the disease activity of coronary vasospasm in these patients. Oxidative stress may be related to the genesis of coronary vasospasm.

Role of thioredoxin in cell growth through interactions with signaling molecules

The thioredoxin system helps maintain a reducing environment in cells, but thioredoxin functions as more than simply an antioxidant. Thioredoxin functions depend on the protein's redox state, as determined by two conserved cysteines. Key biologic activities of thioredoxin include antioxidant, growth control, and antiapoptotic properties, resulting from interaction with target molecules including transcription factors. Mechanisms by which thioredoxin regulates cell growth include binding to signaling molecules such as apoptosis signal-regulating kinase-1 (ASK-1) and thioredoxin-interacting protein (Txnip). The molecular interplay between thioredoxin, ASK-1, and Txnip potentially influences cell growth and survival in diverse human diseases such as cancer, diabetes, and heart disease. In this review, we focus on the structure of thioredoxin and its functional regulation of cell growth through the interactions with signaling molecules.

Human thioredoxin-1 ameliorates experimental murine colitis in association with suppressed macrophage inhibitory factor production

BACKGROUND & AIMS

Thioredoxin-1 (TRX) is a small multifunctional protein with antioxidative and redox-regulating functions. In this study, we investigated the significance of TRX in patients with inflammatory bowel disease (IBD) and the ability and mechanism to ameliorate experimental colitis.

METHODS

Serum TRX and macrophage migration inhibitory factor (MIF) levels were measured in patients with IBD. The effects of TRX were evaluated in a dextran sulfate sodium (DSS)-induced colitis model by comparing TRX-overexpressing transgenic (TRX-TG) and control mice. We further evaluated the effect of recombinant human TRX (rhTRX) administration on DSS-induced colitis and colonic inflammation of interleukin (IL)-10 knockout (IL-10 KO) mice. Colonic inflammation was examined clinically and histologically. Proinflammatory cytokine levels were examined in colonic tissues, and MIF levels were measured in colonic tissues and sera in mice. The effect of TRX on MIF production was also analyzed in vitro.

RESULTS

Serum TRX and MIF levels were significantly higher in patients with IBD than normal controls, and TRX levels correlated with disease activity. TRX significantly ameliorated DSS-induced colitis and colonic inflammation of IL-10 KO mice. Increase of tumor necrosis factor-alpha and interferon-gamma in colonic tissues was significantly suppressed in TRX-TG mice compared with wild-type mice. MIF levels in colonic tissues and sera were significantly lower in TRX-TG mice than in wild-type mice, irrespective of DSS administration. Anti-TRX treatment exacerbated DSS-induced colitis. In vitro studies demonstrated that rhTRX suppressed MIF production in human monocyte cells.

CONCLUSIONS

TRX might have a potential as a novel therapeutic agent for the treatment of IBD.

Extracellular thioredoxin and thioredoxin-binding protein 2 in control of cancer

Thioredoxin-1 (TRX) is a redox-active protein with multiple intracellular and extracellular functions. Intracellular redox balance is maintained by the TRX family and its related molecules. Extracellular TRX shows cytoprotective effects, while truncated Trx80 has more mitogenic activity. Exogenously administered TRX does not promote the growth of cancer in vivo and shows anti-chemotactic effect for neutrophils and anti-inflammatory functions. Thioredoxin is released from cells in response to oxidative stress and TRX levels in plasma or serum are good markers for oxidative stress associated with cancer. Thioredoxin-binding protein 2 (TBP-2) is an endogenous negative regulator of TRX and a tumor suppressor.

Redox regulation of human thioredoxin network

Oxidative stresses are largely mediated by intracellular protein oxidations by reactive oxygen species (ROS). Host cells are equipped with antioxidants that scavenge ROS. The cellular reduction/oxidation (redox) balance is maintained by ROS and antioxidants. Accumulating evidence suggests that the redox balance plays an important role in cellular signaling through the redox modification of cysteine residues in various important components of the signal transduction pathway. Thioredoxin (TRX) is a small protein playing important roles in cellular responses, including cell growth, cell cycle, gene expression, and apoptosis, to maintain the redox circumstance. Moreover, many recent papers have shown that the redox regulation by TRX is deeply involved in the pathogenesis of various oxidative stress-associated disorders. This review focuses on TRX and its related molecules, and discusses the role of TRX-dependent redox regulation in oxidative stress-induced signal transduction.

Thioredoxin-1 suppresses systemic inflammatory responses against cigarette smoking

Thioredoxin-1 (TRX) is a small redox-active protein with antioxidative effects and redox-regulating functions. Cigarette smoking is a major etiological factor in the pathogenesis of a variety of diseases and recruits systemic immune and inflammatory responses. This report demonstrates that TRX attenuates the systemic inflammatory responses induced by cigarette smoking. The mRNA expressions of tumor necrosis factor alpha (TNF-alpha) and macrophage migration inhibitory factor (MIF) were suppressed in the spleen of TRX overexpressing transgenic mice (TRX-tg) exposed to cigarette smoking, compared with control C57BL/6 mice. In addition, protein carbonylation, a marker of cellular protein oxidation, was enhanced by cigarette smoking in the tissues of heart and liver in control mice more than in TRX-tg mice. These findings suggest that TRX may suppress the systemic inflammatory responses against cigarette smoking.

Thioredoxin inhibits NMDA-induced neurotoxicity in the rat retina

Thioredoxin (TRX) plays a variety of redox-related roles in organisms. To investigate its function as an endogenous redox regulator in NMDA-induced retinal neurotoxicity, we injected NMDA with TRX, mutant TRX or saline into the vitreous cavity of rat eyes. Retinal ganglion cells were rescued by TRX, compared with saline, when evaluated by retrograde labeling analysis at 7 days after NMDA injection. TRX, but not its mutant form, prevented NMDA-induced apoptosis in the retina, as measured by terminal deoxynucleotidyl transferase-mediated UTP nick-end labeling. The induction of caspase 3 and 9, but not caspase 8, by NMDA was significantly lower in TRX-treated eyes than in saline-treated eyes. NMDA-induced activation of the MAPKs, p38 kinase and c-Jun N-terminal kinase after 6 h and of the MAPK kinases (MKKs) MKK3/6 and MKK4 after 3 h was markedly suppressed in retinal ganglion cells by TRX but not by the mutant form. NMDA-induced increases in protein carbonylation, nitrosylation and lipid peroxidation were also suppressed in TRX-treated eyes. We concluded that the intravitreous injection of TRX effectively attenuated NMDA-induced retinal cell damage and that suppression of oxidative stress and inhibition of apoptotic signaling pathways were involved in this neuroprotection.

Recombinant human thioredoxin suppresses lipopolysaccharide-induced bronchoalveolar neutrophil infiltration in rat

Human thioredoxin (TRX) is a multifunctional redox-active protein. We previously reported that the intraperitoneal administration of recombinant human thioredoxin (rhTRX) attenuates inflammatory cytokine- or bleomycin-induced lung injury in mice. In this study, the effect of rhTRX injected intravenously after lipopolysaccharide (LPS) injection was analyzed in rats. Rats were injected with LPS followed by treatment with rhTRX. Although the bolus injection exerted no protective effect, continuous intravenous administration of rhTRX significantly suppressed percentage number of neutrophils in bronchoalveolar lavage fluid. Histological examination also showed that rhTRX decreased neutrophil infiltration in the lung tissues. Administered rhTRX was mainly excreted into the urine and the tissue accumulation of rhTRX in the lung was marginal. LPS-induced oxidative stress in the lung was slight in this model. These results demonstrated that continuous intravenous administration of rhTRX suppresses LPS-induced bronchoalveolar neutrophil infiltration by an anti-chemotactic effect. Administration of rhTRX did not promote the tumor growth nor affect chemosensitivity in the xenotransplantation model, suggesting the safety of rhTRX therapy for cancer patients.

Anti-proliferative and anti-tumor effects of antisense oligonucleotide GTI-2601 targeted against human thioredoxin

Human thioredoxin has been implicated in cancer as a growth stimulator through regulation of DNA replication and growth factor activity, as a modulator of transcription factor activity, and as an inhibitor of apoptosis. In the present study, the steady-state level of thioredoxin protein was examined in a number of cancer cell lines. Interestingly, thioredoxin expression is elevated in a variety of human tumor cell lines compared with normal cell lines. The altered expression of thioredoxin in tumor cells suggests it may be a target in the development of novel therapeutic agents for the treatment and prevention of cancer. Further to this possibility, 26 phosphorothioate antisense oligodeoxynucleotides (PS-AS-ODNs) were evaluated for the ability to inhibit thioredoxin expression in cell culture. One PS-AS-ODN, GTI-2601, specifically reduced the levels of thioredoxin mRNA and protein, exhibited potent anti-proliferative effects on colony formation in vitro, and had anti-tumor effects in human tumor xenograft mouse models in vivo. Sequence-specific decreases in thioredoxin expression levels were accompanied by significant suppression of tumor growth in mice. Taken together, these data suggest that thioredoxin may be a useful target for developing PS-AS-ODNs as drug candidates against human cancer.

The thioredoxin system in retroviral infection and apoptosis

Human thioredoxin (TRX) was first identified in human T-cell leukemia virus type I (HTLV-I)-positive T-cell lines and is associated with the pathophysiology of retroviral infections. TRX is a vital component of the thiol-reducing system and regulates various cellular function (redox regulation). Members of the TRX system regulate apoptosis through a wide variety of mechanisms. A family of thioredoxin-dependent peroxidases (peroxiredoxins) protects against apoptosis by scavenging hydrogen peroxide. Thioredoxin 2 is a critical regulator of cytochrome c release and mitochondrial apoptosis; transmembrane thioredoxin-related molecule (TMX) has a protective role in endoplasmic reticulum (ER) stress-induced apoptosis. TRX interacts with apoptosis signal-regulating kinase 1 (ASK1) and is a sensor of oxidative stress. Thioredoxin binding protein-2/vitamin D(3) upregulated protein 1 is a growth suppressor and its expression is suppressed in HTLV-I-transformed cells. Studies of these molecules of the TRX system provide novel insights into the apoptosis associated with retroviral diseases.

Evidence for a Domain-Swapped CD4 Dimer as the Coreceptor for Binding to Class II MHC

CD4 is a coreceptor for binding of T cells to APC and the primary receptor for HIV. The disulfide bond in the second extracellular domain (D2) of CD4 is reduced on the cell surface, which leads to formation of disulfide-linked homodimers. A large conformational change must take place in D2 to allow for formation of the disulfide-linked dimer. Domain swapping of D2 is the most likely candidate for the conformational change leading to formation of two disulfide-bonds between Cys130 in one monomer and Cys159 in the other one. Mild reduction of the extracellular part of CD4 resulted in formation of disulfide-linked dimers, which supports the domain-swapped model. The functional significance of dimer formation for coreceptor function was tested using cells expressing wild-type or disulfide-bond mutant CD4. Eliminating the D2 disulfide bond markedly impaired CD4's coreceptor function. Modeling of the complex of the TCR and domain-swapped CD4 dimer bound to class II MHC and Ag supports the domain-swapped dimer as the immune coreceptor. The known involvement of D4 residues Lys318 and Gln344 in dimer formation is also accommodated by this model. These findings imply that disulfide-linked dimeric CD4 is the preferred coreceptor for binding to APC.

Protective roles of redox-active protein thioredoxin-1 for severe acute pancreatitis

Severe acute pancreatitis is a disease with high mortality, and infiltration of inflammatory cells and reactive oxygen species have a crucial role in the pathophysiology of this disease. Thioredoxin-1 (TRX-1) is an endogenous redox-active multifunctional protein with antioxidant and anti-inflammatory effects. TRX-1 is induced in various inflammatory conditions and shows cytoprotective effects. The aim of the present study was to clarify the protective roles of TRX-1 in the host defense mechanism against severe acute pancreatitis. Experimental acute pancreatitis was induced by intraperitoneal administration of cerulein, a CCK analog, and aggravated by lipopolysaccharide injection in transgenic mice overexpressing human TRX-1 (hTRX-1) and control C57BL/6 mice. Transgenic overexpression of hTRX-1 strikingly attenuated the severity of experimental acute pancreatitis. TRX-1 overexpression suppressed neutrophil infiltration as determined by myeloperoxidase activity, oxidative stress as determined by malondialdehyde concentration, and cytoplasmic degradation of inhibitor of kappaB-alpha, thereby suppressing proinflammatory cytokines, tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6; a neutrophil chemoattractant, keratinocyte-derived chemokine; and inducible nitric oxide synthase in the pancreas. Administration of recombinant hTRX-1 also suppressed neutrophil infiltration, reduced the inflammation of the pancreas and the lung, and improved the mortality rate. The present study suggests that TRX-1 has potent antioxidant and anti-inflammatory actions in experimental acute pancreatitis and might be a new therapeutic strategy to improve the prognosis of severe acute pancreatitis.

Expression of a thioredoxin-related protein-1 is induced by prostaglandin E(2)

Prostaglandin E(2) (PGE(2)) plays an important role in protection of the gastric mucosa against various damaging agents and growth-inhibitory activity on tumor cells. However, the precise regulation mechanism of PGE(2) in gastric cancer cells is still unclear. In this study, we isolated a gene, which is regulated by PGE(2) in SNU-1, human gastric adenocarcinoma cells, using differential display RT-PCR (DD RT-PCR) and characterized the function of the gene induced by PGE(2). The full-length cDNA of the gene was cloned by the rapid amplification of cDNA ends method. The 1659 base pair cDNA consists of a 30-nt 5'-noncoding region, an 891-nt open reading frame and a 738-nt 3'noncoding region that includes a poly (A) signal. As a result of protein motif search, we found that it has a conserved thioredoxin-active site, Cys-Gly-Pro-Cys and a Myb-DNA binding domain repeat signature. Thus, we designated this gene product as thioredoxin-related protein-1, TRP-1. TRP-1 was expressed in a lower extent in renal, gastric and colon cancer tissues and is translated into 33 kDa protein in nuclear and cytoplasmic fractions. TRP-1 has a thioredoxin activity, which was detected using the insulin disulfide reduction assay. Another potential role of TRP-1 is repression of B-Myb activity through direct binding to B-Myb, a transcriptional factor induced at G1-S transition. Finally, TRP-1 overexpression inhibits mammalian cell proliferation and specifically predispose to G0/G1 phase arrest. In conclusion, these results imply that TRP-1 is a mammalian thioredoxin and plays as a transcriptional repressor through direct binding to the transcription factor B-Myb.

The role of low molecular weight thiols in T lymphocyte proliferation and IL-2 secretion

Glutathione (GSH) is an abundant intracellular tripeptide that has been implicated as an important regulator of T cell proliferation. The effect of pharmacological regulators of GSH and other thiols on murine T cell signaling, proliferation, and intracellular thiol levels was examined. l-Buthionine-S,R-sulfoximine (BSO), an inhibitor of GSH synthesis, markedly reduced GSH levels and blocked T cell proliferation without significant effect on cell viability. N-acetylcysteine markedly enhanced T cell proliferation without affecting GSH levels. Cotreatment of T cells with N-acetylcysteine and BSO failed to restore GSH levels, but completely restored the proliferative response. Both 2-ME and l-cysteine also reversed the BSO inhibition of T cell proliferation. Intracellular l-cysteine levels were reduced with BSO treatment and restored with cotreatment with NAC or l-cysteine. However, 2-ME completely reversed the BSO inhibition of proliferation without increasing intracellular cysteine levels. Therefore, neither GSH nor cysteine is singularly critical in limiting T cell proliferation. Reducing equivalents from free thiols were required because oxidation of the thiol moiety completely abolished the effect. Furthermore, BSO did not change the expression of surface activation markers, but effectively blocked IL-2 and IL-6 secretion. Importantly, exogenous IL-2 completely overcame BSO-induced block of T cell proliferation. These results demonstrate that T cell proliferation is regulated by thiol-sensitive pathway involving IL-2.

Redox regulation of mast cell histamine release in thioredoxin-1 (TRX) transgenic mice

Thioredoxin-1 (TRX) is a stress-inducible redox-regulatory protein with antioxidative and anti-inflammatory effects. Here we show that the release of histamine from mast cells elicited by cross-linking of high-affinity receptor for IgE (FcepsilonRI) was significantly suppressed in TRX transgenic (TRX-tg) mice compared to wild type (WT) mice. Intracellular reactive oxygen species (ROS) of mast cells stimulated by IgE and antigen was also reduced in TRX-tg mice compared to WT mice. Whereas there was no difference in the production of cytokines (IL-6 and TNF-alpha) from mast cells in response to 2,4-dinitrophenylated bovine serum albumin (DNP-BSA) stimulation in TRX-tg and WT mice. Immunological status of TRX-tg mice inclined to T helper (Th) 2 dominant in primary immune response, although there was no difference in the population of dendritic cells (DCs) and regulatory T cells. We conclude that the histamine release from mast cells in TRX-tg mice is suppressed by inhibition of ROS generation. As ROS are involved in mast cell activation and facilitate mediator release, TRX may be a key signaling molecule regulating the early events in the IgE signaling in mast cells and the allergic inflammation.

Wheat and maize thioredoxins: a novel cross-reactive cereal allergen family related to baker's asthma

BACKGROUND

Baker's asthma is a serious problem for a significant proportion of workers in bakeries, confectionaries, and the food industry. Although several wheat allergens related to baker's asthma have been described, standardized reagents for a reliable diagnosis are not yet available.

OBJECTIVE

To clone novel wheat allergens related to baker's asthma and investigate the cross-reactive potential of their maize and human homologues.

METHODS

A wheat cDNA phage display library was screened with sera from bakers with occupational asthma for IgE-binding structures. Homologous sequences from maize and human thioredoxins were amplified from corresponding cDNA libraries.

RESULTS

Within the enriched wheat cDNA repertoire we identified, among others, the sequence encoding wheat thioredoxin-hB (Triticum aestivum allergen 25 [Tri a 25]). The recombinant protein displayed enzymatic activity, and we observed a sensitization rate of 47% among bakers with occupational asthma and of 35% among patients with grass pollen allergy, but without a clinical history of cereal allergy. Furthermore, the previously characterized maize thioredoxin-h1 (Zea mays allergen 25 [Zea m 25]), sharing 74% identity with Tri a 25, exhibited distinct IgE cross-reactivity with its wheat homologue. Two bakers also showed sensitization to human thioredoxin, which shares 29% identity with Tri a 25. In a comparative study, we included recombinant alpha-amylase inhibitor 0.19, showing a sensitization rate of 65% in individuals with baker's asthma.

CONCLUSION

Thioredoxins represent a novel family of cross-reactive allergens that might contribute to the symptoms of baker's asthma and might in addition be related to grass pollen allergy, as indicated by the reactivity of grass pollen allergic patients to cereal thioredoxins.

CLINICAL IMPLICATIONS

The recombinant cereal thioredoxins will, together with the already reported wheat allergens, contribute to a more reliable diagnosis of baker's asthma and, perhaps, become a tool for the development of component-resolved immunotherapy.

High thioredoxin expression is associated with resistance to docetaxel in primary breast cancer

PURPOSE

Thioredoxin overexpression is suggested to be associated with resistance to several chemotherapeutic agents in vitro. In the present study, it has been studied whether or not high thioredoxin expression is associated with resistance to docetaxel therapy in breast cancer patients.

PATIENTS AND METHODS

Sixty-three primary breast cancer patients were treated with docetaxel (60 mg/m(2), q3w) for four cycles in the neoadjuvant setting. Expression of thioredoxin, estrogen receptor (ER), p53, BRCA-1, and Bcl-2 in tumor tissues obtained before docetaxel therapy was studied by immunohistochemistry (thioredoxin, p53, BRCA-1, and Bcl-2) and enzyme immunoassay (ER), and relationship of expression of these biomarkers with a pathologic response was investigated.

RESULTS

There was no significant correlation between the expression of p53, BRCA-1, or Bcl-2 and a response to docetaxel. However, tumors with high thioredoxin expression showed a significantly lower response rate (0%) than those with low thioredoxin expression (30.6%; P = 0.018) and ER-negative tumors showed a significantly higher response rate (32.4%) than ER-positive tumors (10.7%; P = 0.043). Thioredoxin expression significantly increased after docetaxel therapy (mean, 56.1%) as compared with that before docetaxel therapy (mean, 28.6%; P < 0.0001) but there was no significant association between the extent of increase in thioredoxin expression and response.

CONCLUSION

High thioredoxin expression in prechemotherapy tumor samples, but not the increase in thioredoxin expression induced by docetaxel, is associated with resistance to docetaxel in breast cancer. Thioredoxin and ER might be clinically useful in the prediction of a response to docetaxel.

Thioredoxin-binding protein-2 (TBP-2): its potential roles in the aging process

Thioredoxin (TRX) binding protein-2 (TBP-2), a negative regulator of TRX, is involved in intracellular redox regulation and cellular growth. The expression of TBP-2 is frequently lost in tumor cell lines and tissues, whereas the ectopic expression of TBP-2 suppresses cellular proliferation along with cell cycle arrest at the G1 phase. TBP-2 was also reported to be a cellular senescence-associated gene. Besides the retardation of cellular growth, the reduction of white adipose, and alteration of the energy pathway are involved in several features of the aging process. We have generated TBP-2 genetically modified mice and found that TBP-2 is closely linked to lipid metabolism. Indeed, TBP-2 has been suggesting to be related to familial combined hyperlipidemia analyzed by a spontaneous mutant mouse strain. As lipid metabolism is one of the most primitive sources of energy production, we discussed the possible roles of TBP-2 in the regulation of energy utilization connected to the aging process.

Thioredoxin-1 suppresses lung injury and apoptosis induced by diesel exhaust particles (DEP) by scavenging reactive oxygen species and by inhibiting DEP-induced downregulation of Akt

Diesel exhaust particles (DEP) are reactive oxygen species (ROS)-inducing toxic agents that damage lungs. Thioredoxin-1 (Trx-1) is a thiol protein with antioxidant and redox-regulating effects. In this study, we demonstrate that Trx-1 scavenges ROS generated by DEP and attenuates the lung injury. Intratracheal instillation of DEP resulted in the generation of more hydroxyl radicals in control mice than in human Trx-1 (hTrx-1)-transgenic mice as measured by noninvasive L-band in vivo electron spin resonance. DEP caused acute lung damage with massive infiltration of inflammatory cells in control mice, but much less damage in hTrx-1-transgenic mice. The hTrx-1 transgene protected the mice against DEP toxicity. To investigate further the molecular mechanism of the protective role of Trx-1 against DEP-induced lung injury, we used hTrx-1-transfected L-929 cells and recombinant hTrx-1 (rhTrx-1)-pretreated A-549 cells. DEP-induced ROS generation was suppressed by hTrx-1 transfection or pretreatment with rhTrx-1. Endogenous Trx-1 expression was induced by DEP in control cells. The downregulation of Akt phosphorylation by DEP resulted in apoptosis, which was prevented by Trx-1. Moreover, an Akt inhibitor canceled this protective effect of Trx-1. Collectively, the results suggest that Trx-1 exerts antioxidant effects in vivo and in vitro and that this plays a role in protection against DEP-induced lung damage by regulating Akt-mediated antiapoptotic signaling.

Selenium, the thyroid, and the endocrine system

Recent identification of new selenocysteine-containing proteins has revealed relationships between the two trace elements selenium (Se) and iodine and the hormone network. Several selenoproteins participate in the protection of thyrocytes from damage by H(2)O(2) produced for thyroid hormone biosynthesis. Iodothyronine deiodinases are selenoproteins contributing to systemic or local thyroid hormone homeostasis. The Se content in endocrine tissues (thyroid, adrenals, pituitary, testes, ovary) is higher than in many other organs. Nutritional Se depletion results in retention, whereas Se repletion is followed by a rapid accumulation of Se in endocrine tissues, reproductive organs, and the brain. Selenoproteins such as thioredoxin reductases constitute the link between the Se metabolism and the regulation of transcription by redox sensitive ligand-modulated nuclear hormone receptors. Hormones and growth factors regulate the expression of selenoproteins and, conversely, Se supply modulates hormone actions. Selenoproteins are involved in bone metabolism as well as functions of the endocrine pancreas and adrenal glands. Furthermore, spermatogenesis depends on adequate Se supply, whereas Se excess may impair ovarian function. Comparative analysis of the genomes of several life forms reveals that higher mammals contain a limited number of identical genes encoding newly detected selenocysteine-containing proteins.

Soybean oil in total parenteral nutrition maintains albumin and antioxidant enzyme mRNA levels

Changes in albumin and antioxidant enzyme mRNA expression in infant rat liver following administration of total parenteral nutrition (TPN) with/without soybean oil emulsion were studied. Infant rats were divided into three groups: group 1=oral diet, group 2=TPN without fat, and group 3=TPN with 20% of calories from soybean oil emulsion. The period of TPN administration was 4 d. Serum aspartate aminotransferase and alanine aminotransferase levels were higher in group 2 than in the other groups, with similar levels seen in the other groups. Albumin, Cu, Zn-superoxide dismutase, and glutaredoxin 1 mRNA expression levels were lower in group 2 than in the other groups, with similar levels seen in the other groups. Catalase mRNA expression was higher in group 1 than in the other groups, with the lowest level seen in group 2. Soybean oil emulsion should be included in TPN regimens to prevent down-regulation of albumin and antioxidant enzyme mRNA expression.

Extracellular human thioredoxin-1 inhibits lipopolysaccharide-induced interleukin-1beta expression in human monocyte-derived macrophages

Oxidative stress plays an important role in atherosclerotic vascular disease, and several recent studies were focused on thioredoxin-1 (Trx-1) and its potential protective role against oxidative stress. Since human monocyte-derived macrophages (HMDM) are important cells in several inflammatory diseases including atherosclerosis, we conducted this study to evaluate the impact of extracellular recombinant human Trx-1 (rhTrx-1) on gene expression in lipopolysaccharide-activated HMDM. Our results showed that rhTrx-1 was capable of reducing interleukin (IL)-1beta mRNA and protein synthesis in a dose-dependent manner. This effect was partly mediated through a reduction of NF-kappaB activation as analyzed by transient transfection and gel shift assays. In addition, we showed that the attenuation of NF-kappaB activity was the result of the reduction of both p50 and p65 subunit mRNA and protein synthesis on one hand and of the induction of I-kappaBalpha mRNA and protein expression on the other hand. Moreover, inhibition of endogenous Trx-1 mRNA was also observed, suggesting a contribution to the diminution of NF-kappaB activity since endogenous Trx-1, in contrast to the exogenous Trx-1, activates the NF-kappaB system. Finally, H2O2-oxidized rhTrx-1 reduced IL-1beta mRNA synthesis in lipopolysaccharide-activated HMDM. This result highly suggested that the rhTrx-1 used in this study could be oxidized in the culture medium and, in turn, reduced IL-1beta mRNA and protein synthesis. Taken together, these data indicated a potential new mechanism through which extracellular rhTrx-1 exerts an anti-inflammatory function in HMDM.

Thioredoxin suppresses airway hyperresponsiveness and airway inflammation in asthma

Thioredoxin (TRX) is a 12-kDa redox (reduction/oxidation)-active protein that has a highly conserved site (-Cys-Gly-Pro-Cys-) and scavenges reactive oxygen species. Here we examined whether exogenously administered TRX modulated airway hyperresponsiveness (AHR) and airway inflammation in a mouse asthma model. Increased AHR to inhaled acetylcholine and airway inflammation accompanied by eosinophilia were observed in OVA-sensitized mice. Administration of wild-type but not 32S/35S mutant TRX strongly suppressed AHR and airway inflammation, and upregulated expression of mRNA of several cytokines (e.g., IL-1alpha, IL-1beta, IL-1 receptor antagonist, and IL-18) in the lungs of OVA-sensitized mice. In contrast, TRX treatment at the time of OVA sensitization did not improve AHR or airway inflammation in OVA-sensitized mice. Thus, TRX inhibited the asthmatic response after sensitization, but did not prevent sensitization itself. TRX and redox-active protein may have clinical benefits in patients with asthma.

Link between macrophage migration inhibitory factor and cellular redox regulation

Macrophage migration inhibitory factor (MIF) is an evolutionary conserved 12.5-kDa protein mediator with multiple functions in innate and acquired immunity. Upon leaderless secretion, MIF acts as a typical inflammatory cytokine, but there is no structural homology between MIF and any of the known cytokine protein families. Also, MIF is unique among cytokines in that it exhibits certain endocrine properties and has enzymatic activity. The catalytic thiol-protein oxidoreductase (TPOR) activity of MIF is mediated by a Cys-Ala-Leu-Cys active site between residues 57 and 60 that can undergo reversible intramolecular disulfide formation. Such a redox motif is typically found in TPORs of the thioredoxin (Trx) family of proteins. MIF seems to act as a disulfide reductase, and structure-function analyses of the redox site indicate that this activity is not only observed in vitro, but plays a role in cellular redox homeostasis, apoptosis inhibition, MIF-mediated monocyte/macrophage activation, and possibly the modulation of the activity of MIF-binding proteins. In this Forum review, the biochemical and biological evidence for a role of the TPOR activity for various MIF functions is summarized and discussed. In particular, the marked functional homologies with Trx proteins, the MIF redox/MHC II link, and recent attempts to discern the intra- versus extracellular roles of the MIF TPOR activity are dealt with.

Similarities and differences in the thioredoxin superfamily

There is growing interest in the proteins involved in protein folding. This is mainly due to the large number of human diseases related to defects in folding, which include cystic fibrosis, Alzheimer's and cancer. However, equally important as the oxidation and concomitant formation of disulfide bridges of the extracellular or secretory proteins is the reduction and maintenance in the reduced state of the proteins within the cell. Interestingly, the proteins that are responsible for maintenance of the reduced state belong to the same superfamily as those responsible for the formation of disulfide bridges: all are members of the thioredoxin superfamily. In this article, we highlight the main features of those thioredoxin-like proteins directly involved in the redox reactions. We describe their biological functions, cytoplasmic location, mechanisms of action, structures and active site features, and discuss the principal hypotheses concerning origins of the different reduction potentials and unusual pK(a)'s of the catalytic residues.

Biochemical and biological aspects of protein thiolation in cells and plasma

Protein thiolation is elicited by oxidation by different mechanisms and is involved in a variety of biological processes. Thiols, protein SH (PSH) and non-protein SH groups (NPSH, namely GSH), are in competition in all biological environments in the regulation of oxidant homeostasis because oxidants thiolate proteins, whereas GSH dethiolates them (e.g., GSSG + PSH --> GSSP + GSH). Although poorly investigated, the elimination of disulfides from thiolated proteins to regenerate critical PSH is important. These aspects are poorly known in cells, where glutaredoxin and peroxiredoxin operate as enzymes or potential chaperones to accelerate dethiolation. On the contrary, studies with plasma or albumin have highlighted the importance of protein conformation in dethiolation processes and have clarified the reason why homocysteine (thiol with potential toxicity) is preferentially bound to albumin as protein-thiol mixed disulfide with respect to other NPSH. Here we provide an overview of protein thiolation/dethiolation processes, with an emphasis on recent developments and future perspectives in this field.

Roles of thioredoxin reductase 1 and APE/Ref-1 in the control of basal p53 stability and activity

The p53 protein is redox-sensitive in vitro but in vivo effectors of this sensitivity are not known. In yeasts deficient for thioredoxin (Trx) reductase (TRR), p53 accumulates in an inactive, oxidized form, suggesting a role for TRR-Trx in controlling p53. In mammalian cells, p53 binds to redox factor-1 (APE/Ref-1), an enzyme containing an abasic endonuclease domain involved in base excision repair, and a thiol reductase domain recycled by Trx and involved in regulating the transcription factor AP-1. To evaluate the role of TRR and APE/Ref-1 in p53 regulation, we have abrogated their expression using RNA interference in cell lines expressing wild-type p53. Inhibition of TRR resulted in accumulation of oxidized Trx and increased levels and DNA-binding activity of p53, with no phosphorylation of Ser15 or Ser20. In contrast, inhibition of APE/Ref-1 accelerated p53 protein turnover, resulting in a decrease in p53 levels and activity. However, inhibition of either TRR or APE/Ref-1 did not prevent activation and accumulation of p53 in response to DNA-damage by doxorubicin. When both factors were inhibited, basal levels of p53 were restored. These results suggest that TRR-Trx and APE/Ref-1 cooperate in the control of basal p53 activity, but not in its induction by DNA-damage.

Potential role of thioredoxin in immune responses in intestinal lamina propria T lymphocytes

Thioredoxin (TRX) is a ubiquitous oxidoreductase with strong co-cytokine, chemoattractant and anti-apoptotic activities. TRX expression was found to be particularly elevated in the intestinal mucosa, where its physiologic function is entirely unknown. Here, we demonstrate a high level of TRX expression in lamina propria T cells (LP-T) as opposed to autologous peripheral blood T lymphocytes (PB-T). Addition of recombinant human TRX (rhTRX) to PB-T enhances TRX gene expression. This autoregulation involves the calcineurin signaling pathway, as rhTRX antagonizes the cyclosporine A (CsA)- and tacrolimus-mediated suppression of TRX gene expression. Similarly, rhTRX reverses the suppression of IL-2 mRNA production by CsA and enhances cytokine production preferentially in prestimulated cells. The differential TRX expression in LP-T versus PB-T may thus contribute to the high-level, CsA-resistant IL-2 production characteristic for CD2-stimulated LP-T. Inversely, inactivation of TRX in LP-T through inhibition of TRX reductase abolishes cytokine gene expression. TRX may play a key role in the specialized intestinal microenvironment in amplifying immediate immune responses of LP-T whenever appropriate costimulation of LP-T is provided.

Insulinlike growth factor I gene expression is increased in the fetal lung after tracheal ligation

BACKGROUND/PURPOSE

The mortality and morbidity in congenital diaphragmatic hernia are mainly caused by pulmonary hypoplasia. To improve clinical results, further methods inducing lung growth may have to be used. The aim of this report was to evaluate the expression of insulinlike growth factor I (IGF-I), estrogen receptor alpha, estrogen receptor beta, growth hormone receptor, and thioredoxin in a rat model of hypoplastic, hyperplastic, and normal fetal lungs to improve understanding of lung growth.

METHODS

Hypoplastic diaphragmatic hernia lungs were created by giving nitrofen by gavage to pregnant rats on day 9.5. Hyperplastic lungs were achieved by intrauterine tracheal ligation of rat fetuses on day 19. All lungs were harvested on gestational day 21. Total nucleic acids were extracted by proteinase K digestion and extraction in phenol/chloroform. The total nucleic acids mixture was hybridized with radioactively labeled RNA probes, and the radioactivity of the hybrids was compared with the respective standard curve of known amounts of in vitro synthesized mRNA. Immunohistochemistry staining was performed for IGF-I.

RESULTS

The IGF-I mRNA was significantly (P < .01) higher in hyperplastic lungs compared with control and hypoplastic lungs. The latter 2 did not differ. No difference was found between the other mRNA levels in the study groups.

CONCLUSIONS

IGF-I is involved in the accelerated lung growth seen after intrauterine tracheal ligation.

Current views in HTLV-I-associated adult T-cell leukemia/lymphoma

Epidemiological studies have demonstrated that the relative percentage of malignant lymphoid proliferations varies widely according to geographical location and ethnic populations. HTLV-I is the etiological agent of adult T-cell leukemia/lymphoma (ATLL) and is also associated with cutaneous T-cell lymphoma (CTCL). However, a definite role of HTLV-I in mycosis fungoides (MF) and/or Sezary syndrome (SS) remains controversial. While most HTLV-I-infected individuals remain asymptomatic carriers, 1-5% will develop ATLL, an invariably fatal expansion of virus-infected CD4+ T cells. This low incidence and the long latency period preceding occurrence of the disease suggest that additional factors are involved in development of ATLL. In this review, diagnosis, clinical features, and molecular pathogenesis of HTLV-I are discussed.

Binding of JAB1/CSN5 to MIF is mediated by the MPN domain but is independent of the JAMM motif

Macrophage migration inhibitory factor (MIF) binds to c-Jun activation domain binding protein-1 (JAB1)/subunit 5 of COP9 signalosome (CSN5) and modulates cell signaling and the cell cycle through JAB1. The binding domain of JAB1 responsible for binding to MIF is unknown. We hypothesized that the conserved Mpr1p Pad1p N-terminal (MPN) domain of JAB1 may mediate binding to MIF. In fact, yeast two hybrid (YTH) and in vitro translation/coimmunoprecipitation (CoIP) analysis showed that a core MPN domain, which did not cover the functional JAB1/MPN/Mov34 metalloenzyme (JAMM) deneddylase sequence, binds to MIF comparable to full-length JAB1. YTH and pull-down analysis in conjunction with nanobead affinity matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry demonstrated that MIF(50-65) and MPN are sufficient to mediate MIF-JAB1 interaction, respectively. Finally, endogenous CoIP of MIF-CSN6 complexes from mammalian cells demonstrated that MPN is responsible for MIF-JAB1 binding in vivo, and, as CSN6 does not contain a functional JAMM motif, confirmed that the interaction does not require JAMM.

PSK and Trx80 inhibit B-cell growth in EBV-infected cord blood mononuclear cells through T cells activated by the monocyte products IL-15 and IL-12

Epstein-Barr virus (EBV)–specific immunologic memory is not transferred from mother to child. In vitro infection of cord blood cells can therefore readily lead to the outgrowth of transformed B lymphocytes. We found that the immunomodulator polysaccharide K (PSK) or the mitogenic cytokine truncated thioredoxin (Trx80) inhibited the EBV-induced B-cell proliferation. Using signaling lymphocytic activation molecule (SLAM)–associated protein (SAP) induction as a sign for T- and natural killer (NK) cell activation, we could follow it without any need for cell separation because neither macrophages nor B lymphocytes express SAP. The results suggest the following scenario: EBV infected and activated B lymphocytes. Upon interacting with these cells, T cells became posed for responding to cytokines produced by monocytes. Both PSK and Trx80, which is a secreted C-terminally truncated thioredoxin, activated the monocytes, which then produced cytokines in the presence of the primed T cells. PSK induced interleukin-15 (IL-15), while Trx80 induced IL-12 production. Both cytokines activated the T cells for function. Phosphatidylinositol 3–(PI 3)–kinase and reactive oxygen species (ROSs) were involved in the PSK-induced activation of monocytes. Restimulation of the cultures with EBV-transformed B cells generated specific cytotoxic activity.

Overexpression of thioredoxin prevents thioacetamide-induced hepatic fibrosis in mice

BACKGROUND/AIMS

Thioredoxin is a small redox-active protein with anti-oxidant and anti-apoptotic effects. We have previously reported that thioacetamide-induced acute hepatitis was attenuated in thioredoxin transgenic mice. The aim of the present study was to investigate the protective effect of thioredoxin for hepatic fibrosis.

METHODS

We subjected thioredoxin transgenic mice to thioacetamide-induced hepatic fibrosis. We also studied the effect of thioredoxin on the activation process of primary-cultured hepatic stellate cell.

RESULTS

The expression of endogenous thioredoxin was induced in hepatocytes of thioacetamide-induced murine and rat fibrotic livers. Overexpression of thioredoxin inhibited tumor necrosis factor-alpha-induced apoptosis of HepG2 cells. Thioacetamide-induced fibrosis and accumulation of malondialdehyde were suppressed in transgenic mice as compared with wild type mice. Hepatic stellate cells isolated from transgenic mice were less proliferative than those isolated from wild type mice. Recombinant thioredoxin significantly inhibited DNA synthesis of primary-cultured stellate cells under serum or platelet-derived growth factor stimulation.

CONCLUSIONS

Thioredoxin has a potential to attenuate hepatic fibrosis via suppressing oxidative stress and inhibiting proliferation of stellate cells.

Redox regulation of lung inflammation by thioredoxin

The lungs are the richest in oxygen among the various organs of the body and are always subject to harmful reactive oxygen species. Regulation of the reduction/oxidation (redox) state is critical for cell viability, activation, proliferation, and organ functions. Although the protective importance of various antioxidants has been reported, few antioxidants have established their clinical usefulness. Thioredoxin (TRX), a key redox molecule, plays crucial roles as an antioxidant and a catalyst in protein disulfide/dithiol exchange. TRX also modulates intracellular signal transduction and exerts antiinflammatory effects in tissues. In addition to its beneficial effects in other organs, the protective effect of TRX in the lungs has been shown against ischemia/ reperfusion injury, influenza infection, bleomycin-induced injury, or lethal inflammation caused by interleukin- 2 and interleukin-18. Monitoring of TRX in the plasma, airway, or lung tissue may be useful for the diagnosis and follow-up of pulmonary inflammation. Promotion/modulation of the TRX system by the administration of recombinant TRX protein, induction of endogenous TRX, or gene therapies can be a therapeutic modality for oxidative stress-associated lung disorders.

New therapeutic approaches for adult T-cell leukaemia

Adult T-cell leukaemia or lymphoma is an aggressive malignant disease of mature activated T cells caused by human T-cell lymphotropic virus type I. Patients with this disease have a very poor outlook because of intrinsic chemoresistance and severe immunosuppression. In acute adult T-cell leukaemia, clinical trials in Japan show that although non-targeted combinations of chemotherapy improve response, they do not have a significant effect on complete remission and survival. Antiretroviral therapy with combination zidovudine and interferon alfa, which induces a high rate of complete remission and lengthens survival, should be the first treatment option in acute adult T-cell leukaemia. Patients with adult T-cell lymphoma might benefit from initial aggressive chemotherapy followed by antiretroviral therapy. To prevent relapse in all patients allogeneic bone-marrow transplantation when feasible, or additional targeted therapy, should be mandatory. Based on current pathophysiology, we discuss promising new drugs such as arsenic trioxide, proteasome inhibitors, retinoids, and angiogenesis inhibitors, as well as cellular immunotherapy.

Cellular and plasma levels of human glutaredoxin 1 and 2 detected by sensitive ELISA systems

Glutaredoxins (Grx) catalyze glutathione-dependent thiol-disulfide oxidoreduction reactions. Mammalian cells contain at least two dithiol glutaredoxins, the well-characterized cytoplasmic (12kDa) Grx1 and the recently identified (18kDa) Grx2 with mitochondrial and nuclear isoforms. We have developed two sensitive and specific sandwich ELISAs to study the levels of human Grx1 and Grx2. Both Grx1 and Grx2 were present in placenta extracts and in cell lysates prepared from various tumor cell lines. However, the levels of Grx1 were at least 20 times higher than those of Grx2. Plasma from healthy blood donors contained 13.4+/-7.9ng/ml of Grx1, while Grx2 was not detected. Unstimulated peripheral blood mononuclear cells were shown to secrete Grx1, but upon 12-O-tetradecanoylphorbol-13-acetate activation, the secretion of Grx1 was strongly suppressed. This effect was shown to occur at the transcriptional level. The secretion of Grx1 and its presence in plasma suggests extracellular functions as found for mammalian thioredoxin 1.

Thioredoxin, a redox-regulating protein, is expressed in spontaneous myocarditis in inbred strains of mice

Redox-regulating mechanisms may be involved in the pathogenesis of aging. Thioredoxin (TRX) is a small multifunctional protein which contains a redox active sequence. Spontaneous myocarditis is often observed in aged mice. In this study, we examined the histopathology and characteristics of TRX expression in spontaneous myocarditis in inbred strains of mice. No spontaneous myocarditis was found in adult 4-week-old inbred strains of mice. High incidence of spontaneous myocarditis was found in aged 8-week-old DBA/2 mice, and low incidence was in 8-week-old BALB/c or C57BL/6 mice. The lesions, limited to the right ventricle, were most severe in DBA/2 mice. TRX was upregulated, and the expression was correlated with the severity of the disease in these strains. Also, 8-hydroxy-2'-deoxyguanosine (8-OHdG), which was an established marker for oxidative stress, was concomitantly positive in necrotic lesions among them. In addition, the long-term anti-oxidant treatment with N-acetylcysteine (NAC) suppressed the development of spontaneous myocarditis. Thus, TRX may be induced by the spontaneously developed myocarditis, and the redox-regulating system may play an important role in the development of aging-related myocarditis.

Loss of thioredoxin-binding protein-2/vitamin D3 up-regulated protein 1 in human T-cell leukemia virus type I-dependent T-cell transformation: implications for adult T-cell leukemia leukemogenesis

Human T-cell leukemia virus type I (HTLV-I) is the causative agent of adult T-cell leukemia (ATL). However, the low incidence of ATL among HTLV-I-infected carriers, together with a long latent period, suggests that multiple host-viral events are involved in the progression of HTLV-I-dependent transformation and subsequent development of ATL. Human thioredoxin (TRX) is a redox active protein highly expressed in HTLV-I-transformed cell lines, whereas the TRX-binding protein-2/vitamin D3 up-regulated protein 1 (TBP-2/VDUP1) was recently identified as a negative regulator of TRX. We report here that expression of TBP-2 is lost in HTLV-I-positive, interleukin-2-independent T-cell lines but maintained in HTLV-I-positive, interleukin-2-dependent T-cell lines, as well as HTLV-I-negative T-cell lines. Ectopic overexpression of TBP-2 in HTLV-I-positive T cells resulted in growth suppression. In the TBP-2-overexpressing cells, a G1 arrest was observed in association with an increase of p16 expression and reduction of retinoblastoma phosphorylation. The results suggest that TBP-2 plays a crucial role in the growth regulation of T cells and that the loss of TBP-2 expression in HTLV-I-infected T cells is one of the key events involved in the multistep progression of ATL leukemogenesis.