Vitamin D3 up-regulated protein 1 mediates oxidative stress via suppressing the thioredoxin function

Thioredoxin-interacting protein controls cardiac hypertrophy through regulation of thioredoxin activity

BACKGROUND

Although cellular redox balance plays an important role in mechanically induced cardiac hypertrophy, the mechanisms of regulation are incompletely defined. Because thioredoxin is a major intracellular antioxidant and can also regulate redox-dependent transcription, we explored the role of thioredoxin activity in mechanically overloaded cardiomyocytes in vitro and in vivo.

METHODS AND RESULTS

Overexpression of thioredoxin induced protein synthesis in cardiomyocytes (127+/-5% of controls, P<0.01). Overexpression of thioredoxin-interacting protein (Txnip), an endogenous thioredoxin inhibitor, reduced protein synthesis in response to mechanical strain (89+/-5% reduction, P<0.01), phenylephrine (80+/-3% reduction, P<0.01), or angiotensin II (80+/-4% reduction, P<0.01). In vivo, myocardial thioredoxin activity increased 3.5-fold compared with sham controls after transverse aortic constriction (P<0.01). Aortic constriction did not change thioredoxin expression but reduced Txnip expression by 40% (P<0.05). Gene transfer studies showed that cells that overexpress Txnip develop less hypertrophy after aortic constriction than control cells in the same animals (28.1+/-5.2% reduction versus noninfected cells, P<0.01).

CONCLUSIONS

Thus, even though thioredoxin is an antioxidant, activation of thioredoxin participates in the development of pressure-overload cardiac hypertrophy, demonstrating the dual function of thioredoxin as both an antioxidant and a signaling protein. These results also support the emerging concept that the thioredoxin inhibitor Txnip is a critical regulator of biomechanical signaling.

Microarray analysis of mouse brain gene expression following acute ethanol treatment

Alterations in gene expression are thought to help mediate certain effects of alcohol in the brain. We have analyzed the expression of approximately 24,000 genes using oligonucleotide microarrays to examine the brain expression profiles in two strains of inbred mice, C57BL/6J and DBA/2J, following exposure to an acute dose of ethanol. Our screen identified 61 genes responding to the ethanol treatment beyond a 1.5-fold threshold, with 46 genes altered in both mouse strains and 15 altered in only one strain. Approximately 25% of the genes were selected for confirmation by reverse transcriptase polymerase chain reaction with an 87% success rate. The genes identified have roles in cell signaling, gene regulation, and homeostasis/stress response. Although some of the genes were previously known to be ethanol responsive, we have for the most part identified novel genes involved in the acute murine brain response to ethanol. Such genes have the potential to represent candidate genes in the search to elucidate the molecular pathways mediating ethanol's effects in the brain.

Rat endometrial Vdup1 expression: changes related to sensitization for the decidual cell reaction and hormonal control

During implantation in rodents, attachment and invasion of embryonic trophoblast is accompanied by decidualization of the adjacent endometrial stroma. Decidualization can be initiated only when the endometrium is receptive, and this occurs for a short period in pregnancy. The molecular mechanisms underlying this phenomenon remain unclear. In the current study, using differential display and northern blot analysis, we found that steady-state levels of mRNA for vitamin D3upregulated protein 1 (Vdup1) were significantly higher in ‘refractory’ and ‘delayed’ endometrium compared with ‘receptive’ endometrium or endometrium undergoing artificially induced decidualization. Conversely, thioredoxin (Txn), a ubiquitously expressed cellular redox regulator known to promote growth and proliferation, was found to have elevated transcript levels within the decidualizing endometrium. VDUP1 has previously been shown to bind TXN and inhibit its action. In an inverse, but cooperative, relationship, these molecules have been implicated in regulating cell growth and proliferation in a number of tissues and during transformation to cancer. TheVdup1mRNA is localized to the uterine stroma in the nonreceptive endometrium, the site of increasedTxnmRNA levels during decidualization. In addition,Vdup1mRNA levels are inversely regulated by progesterone and estrogen; prolonged progesterone exposure stimulates an increase inVdup1mRNA levels whereas estrogen decreasesVdup1transcript levels. Together, these results suggest a novel mechanism by which suppression of the decidual response in the nonreceptive endometrium may occur.

Heat shock factor regulates VDUP1 gene expression

The vitamin D3 up-regulated protein 1 (VDUP1) is identified as interacting protein with thioredoxin (TRX) and functions as a natural antagonist of TRX. Its expression is regulated by various stresses including ROS, UV, and heat shock. In the present study, we observed an inducible expression of VDUP1 in Bosc cells by high density and serum deprivation cultures. To determine transcription factors associated with the induction of VDUP1 by stresses, the promoter region of VDUP1 was cloned. Through reporter assays with plasmids having various deletion of its promoter region and analysis of putative cis-elements, heat shock factor element (HSE) was identified. The deletion of HSE abolished transcriptional activity of VDUP1 promoter by stresses and the binding of heat shock factor (HSF) to HSE was confirmed by gel-shift and supershift assays using nuclear extracts prepared from stressed Bosc cells. Also, the enforced expression of HSF or heat shock increased the transcription of endogenous VDUP1. These imply that HSF is an important transcription factor involved in up-regulation of VDUP1 expression by stresses such as high density and serum deprivation cultures.

Large-scale identification of disease genes involved in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous group of diseases in which chromosomal aberrations, small insertions or deletions, or point mutations in certain genes have profound consequences for prognosis. However, the majority of AML patients present without currently known genetic defects. Retroviral insertion mutagenesis in mice has become a powerful tool for identifying new disease genes involved in the pathogenesis of leukemia and lymphoma. Here we have used the Graffi-1.4 strain of murine leukemia virus, which causes predominantly AML, in a screen to identify novel genes involved in the pathogenesis of this disease. We report 79 candidate disease genes in common integration sites (CISs) and 15 genes whose family members previously were found to be affected in other studies. The majority of the identified sequences (60%) were not found in lymphomas and monocytic leukemias in previous screens, suggesting a specific involvement in AML. Although most of the virus integrations occurred in or near the 5' or 3' ends of the genes, suggesting deregulation of gene expression as a consequence of virus integration, 18 CISs were located exclusively within the genes, conceivably causing gene disruption.

Regulation of the mammalian selenoprotein thioredoxin reductase 1 in relation to cellular phenotype, growth, and signaling events

Reactive oxygen species (ROS) are generated as toxic by-products of aerobic metabolism, but are also essential biomolecules in cell signaling. The thioredoxin (Trx) system is a major enzymatic system modulating ROS levels and is important for redox regulation of cellular function. It consists of Trx and thioredoxin reductase (TrxR), which reduces Trx using NADPH. Most, if not all, of the functions of Trx depend on the activity of TrxR. Mammalian TrxR enzymes are selenoproteins with broad substrate specificities, and alteration of cytosolic TrxR1 expression and activity is likely to be an important determinant for the control of cellular redox regulation. TrxR1 activity in cells seems to be modulated by an intricate interplay, involving a housekeeping type promoter in combination with alternative splice variants and transcriptional start sites, posttranscriptional regulation through AU-rich elements, inactivation by electrophilic agents and by itself modulating the effects of several key signaling molecules. TrxR1 activity is also intimately linked with several aspects of selenium metabolism, and hence selenoprotein function in general. Here, we summarize the current knowledge of these different levels of TrxR1 regulation in diverse cell types and in response to growth and signaling events.

The genome of canarypox virus

Here we present the genomic sequence, with analysis, of a canarypox virus (CNPV). The 365-kbp CNPV genome contains 328 potential genes in a central region and in 6.5-kbp inverted terminal repeats. Comparison with the previously characterized fowlpox virus (FWPV) genome revealed avipoxvirus-specific genomic features, including large genomic rearrangements relative to other chordopoxviruses and novel cellular homologues and gene families. CNPV also contains many genomic differences with FWPV, including over 75 kbp of additional sequence, 39 genes lacking FWPV homologues, and an average of 47% amino acid divergence between homologues. Differences occur primarily in terminal and, notably, localized internal genomic regions and suggest significant genomic diversity among avipoxviruses. Divergent regions contain gene families, which overall comprise over 49% of the CNPV genome and include genes encoding 51 proteins containing ankyrin repeats, 26 N1R/p28-like proteins, and potential immunomodulatory proteins, including those similar to transforming growth factor beta and beta-nerve growth factor. CNPV genes lacking homologues in FWPV encode proteins similar to ubiquitin, interleukin-10-like proteins, tumor necrosis factor receptor, PIR1 RNA phosphatase, thioredoxin binding protein, MyD116 domain proteins, circovirus Rep proteins, and the nucleotide metabolism proteins thymidylate kinase and ribonucleotide reductase small subunit. These data reveal genomic differences likely affecting differences in avipoxvirus virulence and host range, and they will likely be useful for the design of improved vaccine vectors.

Thioredoxin: a key regulator of cardiovascular homeostasis

The thioredoxin (TRX) system (TRX, TRX reductase, and NADPH) is a ubiquitous thiol oxidoreductase system that regulates cellular reduction/oxidation (redox) status. The oxidation mechanism for disease pathogenesis states that an imbalance in cell redox state alters function of multiple cell pathways. In this study, we review the essential role for TRX to limit oxidative stress directly via antioxidant effects and indirectly by protein-protein interaction with key signaling molecules, such as apoptosis signal-regulating kinase 1. We propose that TRX and its endogenous regulators are important future targets to develop clinical therapies for cardiovascular disorders associated with oxidative stress.

Redox regulation by thioredoxin in cardiovascular diseases

Increasing evidence has indicated that the modulation of intracellular redox states has important aspects to cellular events, such as cellular proliferation, activation, growth inhibition, or death via the regulation of intracellular signal transduction and gene expression. Thioredoxin (TRX) is a multifunctional stress-inducible protein, which protects cells from various types of stresses. TRX has not only a scavenging activity of reactive oxygen species, but also a regulating activity of various intracellular molecules including transcription factors. We demonstrated that the serum TRX levels are correlated with the severity of heart failure, and are negatively correlated with left ventricular ejection fractions of patients with heart failure. The expression of TRX is enhanced in endothelial cells and macrophages in human atherosclerotic plaques, in balloon-injured rat arteries, and in damaged cardiomyocytes of rats with acute myocarditis. Overexpression of TRX in transgenic mice attenuates adriamycin-induced cardiotoxicity by reducing oxidative stresses. These findings suggest that TRX and the redox system modulated by TRX have an important role in cellular defense against oxidative stress in cardiovascular diseases.

Effector ExoU from the type III secretion system is an important modulator of gene expression in lung epithelial cells in response to Pseudomonas aeruginosa infection

Pseudomonas aeruginosa is an important pathogen in immunocompromised patients and secretes a diverse set of virulence factors that aid colonization and influence host cell defenses. An important early step in the establishment of infection is the production of type III-secreted effectors translocated into host cells by the bacteria. We used cDNA microarrays to compare the transcriptomic response of lung epithelial cells to P. aeruginosa mutants defective in type IV pili, the type III secretion apparatus, or in the production of specific type III-secreted effectors. Of the 18,000 cDNA clones analyzed, 55 were induced or repressed after 4 h of infection and could be classified into four different expression patterns. These include (i) host genes that are induced or repressed in a type III secretion-independent manner (32 clones), (ii) host genes induced specifically by ExoU (20 clones), and (iii) host genes induced in an ExoU-independent but type III secretion dependent manner (3 clones). In particular, ExoU was essential for the expression of immediate-early response genes, including the transcription factor c-Fos. ExoU-dependent gene expression was mediated in part by early and transient activation of the AP1 transcription factor complex. In conclusion, the present study provides a detailed insight into the response of epithelial cells to infection and indicates the significant role played by the type III virulence mechanism in the initial host response.

Vitamin D3 up-regulated protein-1 regulates collagen expression in mesangial cells

BACKGROUND

Hyperglycemia is a known risk factor in the pathogenesis of nephropathy, and collagen accumulation due to an increase reactive oxygen species (ROS) has been suspected to be one of the reasons for high glucose-mediated diseases. However, molecular mechanisms that connect glucose stimulation, oxidative stress, and collagen induction are unknown.

METHODS

We examined global changes in gene expression patterns following high glucose stimulation by using DNA microarray technology in cultured human mesangial cells. The expression of vitamin D3 up-regulated protein-1 (VDUP-1), our candidate for the molecular mediator, was evaluated in the human mesangial cells, mouse mesangial cell line, and kidneys of diabetic mice by quantitative reverse transcription-polymerase chain reaction (RT-PCR). Truncated VDUP-1 proteins were used to test the effects of VDUP-1 on the biosynthesis of collagen in mesangial cells.

RESULTS

Expression of VDUP-1, which was reported as an inhibitor of thioredoxin, was induced rapidly and constantly after exposure to high concentrations of glucose upon analysis with DNA microarray. Overexpression of VDUP-1 gene in cultured mesangial cells resulted in type IV collagen alpha1 chain (COL4A1) mRNA induction and accumulation of type IV collagen protein. However, induction of COL4A1 expression was abolished with a deletion mutant of VDUP-1, which lost thioredoxin-interacting domain. Also, streptozotocin-induced diabetic mice were shown to overexpress VDUP-1 as well as COL4A1.

CONCLUSION

VDUP-1 mediates collagen accumulation in mesangial cells and could be the molecular mediator/marker for fibrosis in diabetic nephropathy caused by chronic hyperglycemia such as diabetes.

The Expression of Vitamin D-Upregulated Protein 1 in Skin and its Interaction with Sciellin in Cultured Keratinocytes

Sciellin, a precursor of the cornified envelope, contains a LIM domain that is known to function as a protein interaction module. In this study we used the yeast two-hybrid system to find proteins interacting with sciellin and identified vitamin D-upregulated protein 1 (VDUP1). This protein had not been reported in skin, but was shown in a number of cells to interact with reduced thioredoxin and regulate its function. Using an affinity VDUP1 column and an extract of cultured keratinocytes it was shown that VDUP1 and sciellin interacted. By immunohistochemistry VDUP1 was localized to the basal layer of normal human epidermis and the inner and outer root sheaths but not the matrix of the hair follicle. In the proliferative epidermis of psoriasis, VDUP1 was most highly expressed in the upper epidermal layers. In cultured keratinocytes, VDUP1 and sciellin were more highly expressed in cells undergoing differentiation. Colocalization of the proteins could be demonstrated by immunohistochemistry in parts of the follicle, psoriatic epidermis, and cultured keratinocytes. Our results suggested that VDUP1 could have a unique role in epidermis regulating the conversion of postmitotic cells to differentiating ones.

Global analysis of gene expression patterns during disuse atrophy in rat skeletal muscle

Muscular inactivity leads to atrophy, weakness, and decreased fatigue resistance. In order to provide a window into the dynamic processes that underlie muscle atrophy, we performed global gene expression analysis of rat soleus muscles using Affymetrix GeneChips at 1, 4, 7 and 14 days of hindlimb unloading. Expression of 309 known genes was significantly changed by at least 2-fold (212 upregulated, 97 downregulated). K-means clustering was used to divide these genes into co-regulated clusters based on the similarity of temporal expression patterns. This allowed the development of a timeline of the atrophy process with respect to the behaviour of genes in a broad array of functional categories. Regulatory genes were often upregulated early, in either a transient or sustained manner, but they also populated clusters with later patterns of activation, suggesting different phases of molecular adaptations. Other early events were the activation of ubiquitination genes and downregulation of protein chaperones. In comparison, clusters representing slightly delayed activation patterns included genes involved in fast contraction, glycolysis, translational inhibition, oxidative stress, protein degradation, and amino acid catabolism. Downregulated genes exhibited fewer unique expression patterns and included structural and regulatory genes of the extracellular matrix and cytoskeleton, and genes that define a slow-oxidative phenotype. Other novel findings include the tight co-activation of proteasome subunit and ubiquitination genes, differential regulation of serine proteases and serine protease inhibitors, and the identification of transcriptional, signalling, growth and cell cycle genes that probably play a role in the atrophy process. The present work has uncovered temporal patterns of gene expression that highlight the molecular processes that underlie muscle atrophy and provide new avenues for study.

Metastasis suppressor pathways--an evolving paradigm

A greater understanding of the processes of tumor invasion and metastasis, the principal cause of death in cancer patients, is essential to determine newer therapeutic targets. Metastasis suppressor genes, by definition, suppress metastasis without affecting tumorigenicity and, hence, present attractive targets as prognostic or therapeutic markers. This short review focuses on those twelve metastasis suppressor genes for which functional data exist. We also outline newly identified genes that bear promising traits of having metastasis suppressor activity, but for which functional data have not been completed. We also summarize the biochemical mechanism(s) of action (where known), and present a working model assembling potential metastasis suppression pathways.

Localization of thioredoxin-interacting protein (TXNIP) mRNA in epithelium of human gastrointestinal tract

Thioredoxin-interacting protein (TXNIP) is a negative regulator of thioredoxin. However, its role in the gastrointestinal (GI) epithelium is as yet unknown. Using in situ hybridization, we demonstrated that mRNA of TXNIP was differentially expressed in the epithelium of the human GI tract. TXNIP transcript was especially prominent in terminal differentiated cells. TXNIP was also highly expressed in lymphocytes in the lymphoid follicles. Our results suggest a new potential role of TXNIP in the differentiation of epithelial cells and in mucosal immunity of the GI tract.

VDUP1 upregulated by TGF-beta1 and 1,25-dihydorxyvitamin D3 inhibits tumor cell growth by blocking cell-cycle progression

Vitamin D(3) upregulated protein 1 (VDUP1) is a 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) upregulated protein, and it is induced by various stresses. In human tumor tissues, VDUP1 expression was downregulated. Upon stimulation by growth-inhibitory signals such as TGF-beta1 and 1,25(OH)(2)D(3), its expression was rapidly upregulated as the cell growth was retarded. The transfection of VDUP1 in tumor cells reduced cell growth. The VDUP1 expression was also increased when the cell-cycle progression was arrested. Transfection of VDUP1 induced cell-cycle arrest at the G0/G1 phase, indicating that VDUP1 possesses a tumor-suppressive activity. In addition, it was found that VDUP1 interacted with promyelocytic leukemia zinc-finger, Fanconi anemia zinc-finger, and histone deacetylase 1, which are known to be transcriptional corepressors. VDUP1 itself suppressed IL-3 receptor and cyclin A2 promoter activity. Taken together, these results suggest that VDUP1 is a novel antitumor gene which forms a transcriptional repressor complex.

Induction of pathogenic sets of genes in macrophages and neurons in NeuroAIDS

The etiology of the central nervous system (CNS) alterations after human immunodeficiency virus (HIV) infection, such as dementia and encephalitis, remains unknown. We have used microarray analysis in a monkey model of neuroAIDS to identify 98 genes, many previously unrecognized in lentiviral CNS pathogenesis, whose expression is significantly up-regulated in the frontal lobe of simian immunodeficiency virus-infected brains. Further, through immunohistochemical illumination, distinct classes of genes were found whose protein products localized to infiltrating macrophages, endothelial cells and resident glia, such as CD163, Glut5, and ISG15. In addition we found proteins induced in cortical neurons (ie, cyclin D3, tissue transglutaminase, alpha1-antichymotrypsin, and STAT1), which have not previously been described as participating in simian immunodeficiency virus or HIV-related CNS pathology. This molecular phenotyping in the infected brains revealed pathways promoting entry of macrophages into the brain and their subsequent detrimental effects on neurons. These data support the hypothesis that in HIV-induced CNS disease products of activated macrophages and astrocytes lead to CNS dysfunction by directly damaging neurons, as well as by induction of altered gene and protein expression profiles in neurons themselves which are deleterious to their function.

Vitamin D(3) up-regulating protein 1 (VDUP1) antisense DNA regulates tumorigenicity and melanogenesis of murine melanoma cells via regulating the expression of fas ligand and reactive oxygen species

The expression of vitamin D(3) up-regulating protein-1 (VDUP1) was up-regulated by 1alpha,25-dihydroxyvitamin D(3) (VD3) treatment in B16 mouse melanoma cells. The functional effect of VDUP1 on B16F10 melanoma cells was demonstrated by reduction of Fas ligand and CD44 expression in cells transfected with VDUP1 antisense cDNA. Furthermore, intracellular reactive oxygen species level and cell proliferation were decreased in antisense transfectants compared with those in vector controls. However, melanin synthesis was up-regulated in antisense transfectants. In addition, VDUP1 antisense transfectants showed an increased susceptibility to natural killer (NK) cells in vitro. When VDUP1 antisense transfectants were implanted into syngeneic mice, significant reduction of tumor cell growth was observed with the infiltrate of T cells and NK cells in tumor area. Taken together, these results demonstrate that VDUP1 has critical physiological roles and can be a novel therapeutic target for melanoma.

Metastasis suppressor genes: basic biology and potential clinical use

Metastatic disease remains a significant contributor to morbidity and mortality in patients with breast cancer. An improved molecular and biochemical understanding of the metastatic process is expected to fuel the development of new therapeutic approaches. The suppression of tumor metastasis, despite tumor cell expression of oncogenes and metastasis-promoting events, has become a diverse and fruitful field of investigation. Although many genetic events promote metastasis, several genes show relatively reduced expression levels in metastatic tumor cells in mouse model systems and in aggressive human tumors. Re-expression of a metastasis-suppressor gene in a metastatic tumor cell line results in a significant reduction in metastatic behavior in vivo with no effect on tumorigenicity. The known metastasis-suppressor gene products nm23, KAI1, mitogen-activated protein kinase kinase 4, breast cancer metastasis suppressor-1, KiSS1, RHOGDI2, CRSP3, and vitamin D3-upregulated protein/thioredoxin interacting protein exhibit unexpected biochemical functions that have shed new light on signaling events that are important in metastasis. Most metastasis suppressors function at the translationally important stage of outgrowth of micrometastatic tumor cells at a distant site. We hypothesize that elevation of metastasis suppressor gene expression in micrometastatic tumor cells in the adjuvant high-risk population of patients with breast cancer will halt metastatic colonization and have a clinical benefit. DNA methylation inhibitors have shown limited promise in increasing metastasis-suppressor gene expression, and ligands of the nuclear hormone receptor family are currently under investigation in vitro and in vivo. Clinical testing of agents that increase metastasis-suppressor gene expression is expected to require tailored trial designs.

Characterization of the MM.1 human multiple myeloma (MM) cell lines: a model system to elucidate the characteristics, behavior, and signaling of steroid-sensitive and -resistant MM cells

Multiple myeloma (MM) is a clonal B-lymphocyte malignancy, which is characterized by the accumulation of terminally differentiated antibody-producing cells in the bone marrow. Because current treatments offer only a median survival of 3 years, investigators continue to search for novel therapeutic strategies to combat the disease. Rational drug design is enhanced by understanding MM cell proliferation and key signaling pathways employed. In addition, a model system for preclinical evaluation of novel therapeutics is critical. Our laboratory has developed MM cell lines to study drug action and resistance, cell proliferation, and apoptosis. These cell lines are widely used in MM research. From a single MM patient, three separate cell lines were established that parallel the progression of the disease. These three cell lines, designated MM1.S, MM1.R(E), and MM1.R(L), can be distinguished on the basis of their sensitivity to steroid hormones such as glucocorticoids (GCs). Utilization of these cell lines to study the etiology of MM, effects of chemotherapeutic agents, and development of clinical resistance, will provide us with vital information for the evolution of new and more efficacious therapeutics. The aim of this review is to summarize the morphological, biochemical, and growth characteristics of these cells, and to review the results from investigations of the MM.1 signaling pathways. This information will enhance the study, treatment, and eventual eradication of MM.

KISS1 metastasis suppression and emergent pathways

Metastatic disease is the most critical impediment to cancer patient survival. However, comparatively little is known concerning the intricate pathways which govern the complex phenotypes associated with metastasis. The KISS1 metastasis suppressor gene inhibits metastasis in both in vivo melanoma and breast carcinoma models. Despite its clear physiological activity, the mechanism of KISS1 remains unclear. Recent identification of a 54 amino acid peptide of KISS1, termed metastin or kisspeptin-54, and its cognate G-protein coupled receptor (hOT7T175, AXOR12, GPR54) have provided additional clues and avenues of research. While studies have attributed KISS1 with modulation of NFkappaB regulation, experiments with metastin and its receptor implicate MAP kinase pathways and also suggest the potential of autocrine, paracrine and endocrine roles. Impacts on motility, chemotaxis, adhesion and invasion have each been documented in disparate cell lines and conflicting observations require resolution. Nevertheless, mounting clinical evidence, particularly the loss of KISS1 in metastases, correlates KISS1 and metastin receptor expression with human tumor progression. Together, the data substantiate roles for these molecules in metastasis regulation.

Gene expression profile of serial samples of transformed B-cell lymphomas

Follicular lymphoma (FL) is characterized by a continuous rate of relapse and transformation to a high-grade lymphoma, usually diffuse large B-cell lymphoma (DLBCL), associated with a dismal prognosis and a poor response to conventional chemotherapy. The progression of indolent to aggressive FL is accompanied by the successive accumulation of recurrent chromosomal defects, but the resultant alterations of gene expression are largely unknown. To expand the understanding of the pathogenesis of FL transformation, we initially performed oligonucleotide microarray analyses using Affymetrix HuFL chips on five cases with matched snap-frozen lymph nodes before and after transformation. Expression data were analyzed using the Affymetrix Microarray Suite 4.0 and Genespring 4.0. Thirty-six genes with increased expression and 66 genes with decreased expression associated with transformation were identified and functionally classified. The expression of differentially expressed genes was confirmed by real-time quantitative RT-PCR (QRT-PCR) using a total of seven matched pairs and an additional five FL and five unrelated DLBCL. In addition, selected genes were further analyzed by QRT-PCR or immunohistochemistry using a large, unrelated series of FL (grades 1 to 3) as well as transformed and de novo DLBCL (total of 51 samples). The microarray results correlated with the protein expression data obtained from samples at the time of initial diagnosis and transformation. Furthermore, the expression of 25 candidate genes was evaluated by QRT-PCR with a 78% confirmation rate. Some of the identified genes, such as nucleobindin, interferon regulatory factor 4, and tissue inhibitor of metalloproteinases 1, are already known to be associated with high-grade non-Hodgkin's lymphoma. Novel candidate genes with confirmed increased and decreased expression in transformed DLBCL include ABL2 and NEK2, and PDCD1 and VDUP1, respectively. In summary, this study shows that transformation of FL to DLBCL is associated with a distinct set of differentially expressed genes of potential functional importance.

Metastasis suppressors alter the signal transduction of cancer cells

Tumour metastasis is a significant contributor to death in cancer patients. Eight metastasis-suppressor genes that reduce the metastatic propensity of a cancer cell line in vivo without affecting its tumorigenicity have been identified. These affect important signal-transduction pathways, including mitogen-activated protein kinases, RHO, RAC and G-protein-coupled and tyrosine-kinase receptors. So how might we use this knowledge to improve the treatment of patients with cancer?

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.

Vitamin D3-upregulated protein-1 (VDUP-1) regulates redox-dependent vascular smooth muscle cell proliferation through interaction with thioredoxin

Reactive oxygen species are important cellular signaling molecules, and thioredoxin (TRX) is a key regulator of cellular redox balance. We investigated the interaction of TRX with its endogenous inhibitor, vitamin D3-upregulated protein (VDUP)-1, in human aortic smooth muscle cells (SMCs). Adenoviral gene transfer of TRX enhanced TRX enzyme activity 2.7+/-0.4-fold (P<0.05 versus cells infected with adenoviral vector expressing green fluorescent protein [AdGFP]) and resulted in a 3.8+/-0.5-fold increase of cellular DNA synthesis as detected by methyl-[3H]thymidine incorporation (P<0.001). Platelet-derived growth factor (PDGF) also increased TRX enzyme activity 2.5+/-3.3-fold (P<0.05 versus no stimulation) and DNA synthesis 6.5+/-0.3-fold (P<0.001 versus no stimulation) without significant changes in TRX expression. PDGF and H2O2 time-dependently suppressed VDUP-1 expression (13-fold and 30-fold reduction after 1 hour, respectively; P<0.001), and this was inhibited by the cell-permeable antioxidants N-acetylcysteine and 4,5-dihydroxy-1,3-benzene-disulfonic acid (Tiron). Overexpression of VDUP-1 (AdVDUP-1) reduced TRX activity at baseline (-61+/-23% versus control cells, P<0.05) and abolished PDGF-induced TRX activity (-9+/-27% in AdVDUP-1-infected cells; P=NS versus control cells). In addition, overexpression of VDUP-1 blocked PDGF-induced DNA synthesis (1.3+/-0.4-fold increase in AdVDUP-1-infected cells versus 6.5+/-0.4-fold increase in AdGFP-infected cells, P<0.001). In conclusion, VDUP-1 has marked antiproliferative effects in SMCs through the suppression of TRX activity, suggesting that the regulation of VDUP-1 is a critical molecular switch in the transduction of pro-oxidant mitogenic signals. These data also demonstrate that activation of the reductase TRX plays a pivotal role in the redox-dependent proliferation of SMCs.

Vitamin D(3)-up-regulated protein-1 is a stress-responsive gene that regulates cardiomyocyte viability through interaction with thioredoxin

The protein-disulfide reductase thioredoxin is critical for redox signaling during apoptosis and growth. In this study, we demonstrate that vitamin D(3)-up-regulated protein-1 regulates thioredoxin in conditions of biomechanical or oxidative stress and critically regulates cardiomyocyte viability. Expression of vitamin D(3)-up-regulated protein-1 but not of thioredoxin in rat cardiomyocytes was rapidly suppressed by biomechanical strain or hydrogen peroxide at both mRNA and protein levels. Mechanical suppression of vitamin D(3)-up-regulated protein-1 gene expression was blocked by N-acetylcysteine. The half-life of vitamin D(3)-up-regulated protein-1 transcripts in cardiomyocytes was only 1.1 h and remained unchanged after mechanical stimulation, suggesting that rapid responses in vitamin D(3)-up-regulated protein-1 gene expression occur through transcriptional control. Vitamin D(3)-up-regulated protein-1 down-regulation by strain or hydrogen peroxide led to increased thioredoxin activity, whereas adenovirus-mediated overexpression of vitamin D(3)-up-regulated protein-1 suppressed thioredoxin activity. Overexpression of vitamin D(3)-up-regulated protein-1 but not of thioredoxin induced cardiomyocyte apoptosis. Furthermore, overexpression of vitamin D(3)-up-regulated protein-1 sensitized cells to hydrogen peroxide-induced apoptosis, whereas overexpression of thioredoxin protected against injury. These data identify vitamin D(3)-up-regulated protein-1 as a key stress-responsive inhibitory switch of thioredoxin activity in cardiomyocytes and demonstrate that the vitamin D(3)-up-regulated protein-1/thioredoxin axis has an important role in the preservation of cellular viability.

Regulatory roles of thioredoxin in oxidative stress-induced cellular responses

Thioredoxin (TRX) is a small ubiquitous and multifunctional protein having a redox-active dithiol/disulfide within the conserved active site sequence -Cys-Gly-Pro-Cys-. TRX is induced by a variety of oxidative stimuli, including UV irradiation, inflammatory cytokines and chemical carcinogens, and has been shown to play crucial roles in the regulation of cellular responses such as gene expression, cell proliferation and apoptosis. Overexpression of TRX protects cells from cytotoxicity elicited by oxidative stress in both in vitro and in vivo models. The regulatory mechanism of TRX expression and activity is also being elucidated. Recently, TRX binding protein-2 (TBP-2)/vitamin D3 up-regulated protein 1 (VDUP1) was identified as a negative regulator of TRX. The analysis of TRX promoter region has revealed putative regulatory elements responsible for oxidative stress. Thus, the modulation of TRX functions may be a new therapeutic strategy for the treatment of oxidative stress-mediated diseases.

Thioredoxin superfamily and thioredoxin-inducing agents

Mammalian thioredoxin (TRX) with redox-active dithiol in the active site plays multiple roles in intracellular signaling and resistance against oxidative stress. TRX is induced by a variety of stresses including infectious agents as well as hormones and chemicals. TRX is secreted from activated cells such as HTLV-I-transformed T-cells as a redox-sensitive molecule with cytokine-like and chemokine-like activities. The promoter of the TRX gene contains a series of stress-responsive elements. In turn, TRX promotes activation of transcription factors such as NF-kappa B, AP-1, and p53. We have reported that natural substances including estrogen, prostaglandins, and cAMP induce mRNA, protein, and secretion of TRX. These agents seemed to exert their physiological functions including cytoprotective actions partly through the induction of TRX without massive oxidative stress, which induces TRX strongly as well as other stress proteins. We report here a new TRX inducer substance, geranylgeranylacetone (GGA), which is originally derived from a natural plant constituent and has been used in the clinical field as an anti-ulcer drug. We have demonstrated that GGA induces the messenger RNA and protein of TRX and affects the activation of transcription factors, AP-1 and NF-kappa B, and that GGA blunted ethanol-induced cytotoxicity of cultured hepatocytes and gastrointestine mucosal cells. We will discuss a possible novel molecular mechanism of GGA, which is to protect cells via the induction of TRX and activation of transcription factors such as NF-kappa B and AP-1. Identification of the particular TRX-inducing components may contribute to the elucidation of the molecular basis of the "French Paradox," in which good red wines are beneficial for the cardiovascular system.

Overexpression of VDUP1 mRNA sensitizes HeLa cells to paraquat

5-Bromodeoxyuridine (BrdU) induces or suppresses senescence-associated genes in any types of mammalian cells. From a cDNA library upregulated by BrdU in HeLa cells, we identified the gene encoding VDUP1 as a senescence-associated gene in normal human fibroblasts. To address a role of VDUP1 in senescence, we established HeLa cell clones, V7 and V27, which express its mRNA in a doxycycline-dependent manner. Although their growth in liquid culture was moderately retarded, colony formation on semi-solid medium was strongly inhibited by overexpression of the mRNA. We also examined susceptibility of these clones to various reagents. Consequently, colony formation in liquid culture was strongly inhibited by paraquat in these clones. Their superoxide dismutase activity was normal.

Positional cloning of the combined hyperlipidemia gene Hyplip1

Familial combined hyperlipidemia (FCHL, MIM-144250) is a common, multifactorial and heterogeneous dyslipidemia predisposing to premature coronary artery disease and characterized by elevated plasma triglycerides, cholesterol, or both. We identified a mutant mouse strain, HcB-19/Dem (HcB-19), that shares features with FCHL, including hypertriglyceridemia, hypercholesterolemia, elevated plasma apolipoprotein B and increased secretion of triglyceride-rich lipoproteins. The hyperlipidemia results from spontaneous mutation at a locus, Hyplip1, on distal mouse chromosome 3 in a region syntenic with a 1q21-q23 FCHL locus identified in Finnish, German, Chinese and US families. We fine-mapped Hyplip1 to roughly 160 kb, constructed a BAC contig and sequenced overlapping BACs to identify 13 candidate genes. We found substantially decreased mRNA expression for thioredoxin interacting protein (Txnip). Sequencing of the critical region revealed a Txnip nonsense mutation in HcB-19 that is absent in its normolipidemic parental strains. Txnip encodes a cytoplasmic protein that binds and inhibits thioredoxin, a major regulator of cellular redox state. The mutant mice have decreased CO2 production but increased ketone body synthesis, suggesting that altered redox status down-regulates the citric-acid cycle, sparing fatty acids for triglyceride and ketone body production. These results reveal a new pathway of potential clinical significance that contributes to plasma lipid metabolism.

Rapid induction and Ca(2+) influx-mediated suppression of vitamin D3 up-regulated protein 1 (VDUP1) mRNA in cerebellar granule neurons undergoing apoptosis

Cerebellar granule neurons (CGNs) grown under depolarizing conditions with high K(+) (HK; 30 mM) undergo apoptosis following replacement of HK by physiological K(+) (5.4 mM). Differential display analysis identified eight genes up-regulated in this paradigm of apoptosis. Vitamin D3 up-regulated protein 1 (VDUP1) mRNA was markedly up-regulated as early as 2 h following HK withdrawal. VDUP1 mRNA was up-regulated in other paradigms of neuronal apoptosis as well both in vitro and in vivo. HK effectively suppressed the up-regulation of VDUP1 mRNA in CGNs undergoing apoptosis via Ca(2+) influx through voltage-dependent L-type Ca(2+) channels, which did not require de novo protein synthesis. The up-regulation occurred in parallel with that of the c-jun transcript and c-jun protein phosphorylation. Moreover, SB203580, p38 mitogen-activated protein kinase inhibitor, suppressed up-regulation of both c-jun and VDUP1 mRNAs, and c-jun phosphorylation in CGNs undergoing apoptosis. IGF-1, one of the neuroprotective agents for CGNs, also inhibited VDUP1 mRNA up-regulation through a phosphoinositide 3 kinase-dependent pathway. These results suggest that the VDUP1 gene is a novel member of early response genes in neuronal apoptosis whose expression is directly regulated by Ca(2+) influx and coordinately regulated with the transcription factor c-jun in CGNs.

Cloning, genetic characterization, and chromosomal mapping of the mouse VDUP1 gene

VDUP1 encodes a vitamin D3-inducible gene product that has been shown to be down-regulated in chemically-induced mammary tumors in rats. It has recently been reported to negatively regulate thioredoxin expression and function. We have cloned the mouse VDUP1 gene and characterized its genomic locus. The VDUP1 coding region spans eight exons within a total length of 2.3 kb located on mouse chromosome 3. Consensus sites for polyadenylation were identified 1.3 kb downstream of the gene, defining a long 3' untranslated region. The minimal functional VDUP1 promoter contains TATA and CCAAT boxes and transcription is initiated from two major start sites downstream. A direct repeat element located proximal to the TATA with homology to the USF binding site was identified as a potential regulator of VDUP1gene expression. Expression analysis determined that VDUP1 mRNA was markedly induced in myeloma cells in high density cell culture, but not in sub-confluent cells arrested by serum deprivation. All samples of a panel of mouse immortalized or transformed cell lines were shown to express abundant levels of VDUP1 mRNA.