Vitamin D3 Up-regulated Protein 1 Research Articles

Vitamin D3 Upregulated Protein 1 Deficiency Promotes Azoxymethane/Dextran Sulfate Sodium-Induced Colorectal Carcinogenesis in Mice.

VDUP1 acts as a tumor suppressor gene in various cancers. VDUP1 is expressed at low levels in sporadic and ulcerative-colitis-associated colorectal cancer. However, the effects of VDUP1 deficiency on CAC remain unclear. In this study, we found that VDUP1 deficiency promoted CAC development in mice. Wild-type (WT) and VDUP1 KO mice were used to investigate the role of VDUP1 in the development of azoxymethane (AOM)- and dextran sulfate sodium (DSS)-induced CAC. VDUP1 levels significantly decreased in the colonic tumor and adjacent nontumoral tissues of WT mice after AOM/DSS treatment. Moreover, AOM/DSS-treated VDUP1 KO mice exhibited a worse survival rate, disease activity index, and tumor burden than WT mice. VDUP1 deficiency significantly induced cell proliferation and anti-apoptosis in tumor tissues of VDUP1 KO mice compared to WT littermates. Additionally, mRNA levels of interleukin-6 and tumor necrosis factor-alpha and active forms of signal transducer and activator of transcription 3 and nuclear factor-kappa B p65 were significantly increased in the tumor tissues of VDUP1 KO mice. Overall, this study demonstrated that the loss of VDUP1 promoted AOM/DSS-induced colon tumorigenesis in mice, highlighting the potential of VDUP1-targeting strategies for colon cancer prevention and treatment.

VDUP1 Deficiency Promotes the Severity of DSS-Induced Colitis in Mice by Inducing Macrophage Infiltration.

The loss of vitamin D3 upregulated protein 1 (VDUP1) has been implicated in the pathogenesis of various inflammation-related diseases. Notably, reduced expression of VDUP1 has been observed in clinical specimens of ulcerative colitis (UC). However, the role of VDUP1 deficiency in colitis remains unclear. In this study, we investigated the role of VDUP1 in dextran sulfate sodium (DSS)-induced experimental colitis in mice. VDUP1-deficient mice were more susceptible to DSS-induced colitis than their wild-type (WT) littermates after 2% DSS administration. VDUP1-deficient mice exhibited an increased disease activity index (DAI) and histological scores, as well as significant colonic goblet cell loss and an increase in apoptotic cells. These changes were accompanied by a significant decrease in MUC2 mRNA expression and a marked increase in proinflammatory cytokines and chemokines within damaged tissues. Furthermore, phosphorylated NF-κB p65 expression was significantly upregulated in damaged tissues in the context of VDUP1 deficiency. VDUP1 deficiency also led to significant infiltration of macrophages into the site of ulceration. An in vitro chemotaxis assay confirmed that VDUP1 deficiency enhanced bone marrow-derived macrophage (BMDM) chemotaxis induced by CCL2. Overall, this study highlights VDUP1 as a regulator of UC pathogenesis and a potential target for the future development of therapeutic strategies.

Targeted Induction of Endogenous VDUP1 by Small Activating RNA Inhibits the Growth of Lung Cancer Cells.

Recent studies have reported that small double-strand RNAs (dsRNAs) can activate endogenous genes via an RNA-based promoter targeting mechanism termed RNA activation (RNAa). In the present study, we showed that dsVDUP1-834, a novel small activating RNA (saRNA) targeting promoter of vitamin D3 up-regulated protein 1 (VDUP1) gene, up-regulated expression of VDUP1 at both mRNA and protein levels in A549 lung cancer cells. We also demonstrated that dsVDUP1-834 inhibited cell proliferation in A549 lung cancer cells. Further studies showed that dsVDUP1-834 induced cell-cycle arrest by increasing p27 and p53 and decreasing cyclin A and cyclin B1. In addition, knockdown of VDUP1 abrogated dsVDUP1-834-induced up-regulation of VDUP1 gene expression and related effects. The activation of VDUP1 by dsVDUP1-834 was accompanied by an increase in dimethylation of histone 3 at lysine 4 (H3K4me2) and acetylation of histone 3 (H3ac) and a decrease in dimethylation of histone 3 at lysine 9 (H3K9me2) at the target site of VDUP1 promoter. Moreover, the enrichment of Ago2 was detected at the dsVDUP1-834 target site, and Ago2 knockdown significantly suppressed dsVDUP1-834-mediated inhibition of cell proliferation and modulation of cell-cycle regulators. Taken together, the results presented in this report demonstrate that dsVDUP1-834 induces VDUP1 gene expression by epigenetic changes, resulting in cell growth inhibition and cell-cycle arrest. Our results suggest that targeted induction of VDUP1 by dsVDUP1-834 might be a promising therapeutic strategy for the treatment of lung cancer.

TXNIP inhibition in the treatment of diabetes. Verapamil as a novel therapeutic modality in diabetic patients.

Loss of pancreatic β–cell is a critical factor in the pathogenesis of type 1 diabetes and it also occurs in type 2. TXNIP (thioredoxin – interacting protein), also known as vitamin D3-upregulated protein 1, or thioredoxin-binding-protein-2, regulates this process and modulates cellular redox balance. TXNIP is localized primarily in the nucleus, but under oxidative stress it moves to mitochondria, where it interacts with mitochondrial thioredoxin 2. Overexpression of TXNIP induced by hyperglycaemia is typical for diabetes and insulin resistance and leads to apoptosis of pancreatic β–cell, cardiomyopathy, metabolic disorders and multiple harmful effects. It activates NLRP3 inflamasomme and IL–1β, a cytokine involved in type 2 diabetes and insulin resistance. TXNIP influences peroxisome proliferator-activated receptor alpha transcriptional activity, expression of glucose transporter–1, nitric oxide production in endothelium and insulin production in β–cells. TXNIP overexpression leads to diabetic retinopathy, nephropathy, atherosclerosis, it occurs in cancers and autoimmune diseases, while its deficiency protects β cells. Reduction of TXNIP is an important target in diabetes treatment. In this mechanism insulin, metformin and inhibitors of dipeptydylopeptydase IV are involved. It has been observed that calcium channel blockers (CCB) used in hypertension also inhibit TXNIP expression in cardiomyocytes. L–type channels identification in pancreatic β-cells revealed that CCB inhibit TXNIP expression also in β–cells. For the first time, verapamil was distinguished as an agent that not only inhibits TXNIP expression in pancreatic β-cells, but also enhances β cell survival and function, and possibly prevents diabetes.

TXNIP: A Double-Edged Sword in Disease and Therapeutic Outlook.

Thioredoxin-interacting protein (TXNIP) was originally named vitamin D3 upregulated protein-1 (VDUP1) because of its ability to bind to thioredoxin (TRX) and inhibit TRX function and expression. TXNIP is an alpha-arrestin protein that is essential for redox homeostasis in the human body. TXNIP may act as a double-edged sword in the cell. The balance of TXNIP is crucial. A study has shown that TXNIP can travel between diverse intracellular locations and bind to different proteins to play different roles under oxidative stress. The primary function of TXNIP is to induce apoptosis or pyroptosis under oxidative stress. TXNIP also inhibits proliferation and migration in cancer cells, although TXNIP levels decrease, and function diminishes in various cancers. In this review, we summarized the main structure, binding proteins, pathways, and the role of TXNIP in diseases, aiming to explore the double-edged sword role of TXNIP, and expect it to be helpful for future treatment using TXNIP as a therapeutic target.

Thioredoxin system activation is associated with the progression of experimental pulmonary arterial hypertension

In addition to being an antioxidant, thioredoxin (Trx) is known to stimulate signaling pathways involved in cell proliferation and to inhibit apoptosis. The aim of this study was to explore the role of Trx in some of these pathways along the progression of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH). Male rats were first divided into two groups: monocrotaline (MCT - 60 mg/kg i.p.) and control (received saline), that were further divided into three groups: 1, 2, and 3 weeks. Animals were submitted to echocardiographic analysis. Right and left ventricles were used for the measurement of hypertrophy, through morphometric and histological analysis. The lung was prepared for biochemical and molecular analysis. One week after MCT injection, there was an increase in thioredoxin reductase (TrxR) activity, a reduction in glutathione reductase (GR) activity, and an increase in Trx-1 and vitamin D3 up-regulated protein-1 (VDUP-1) expression. Two weeks after MCT injection, there was an increase in VDUP-1, Akt and cleaved caspase-3 activation, and a decrease in Trx-1 and Nrf2 expression. PAH-induced by MCT promoted a reduction in Nrf2 and Trx-1 expression as well as an increase in Akt and VDUP-1 expression after three weeks. The increase in pulmonary vascular resistance was accompanied by increased TrxR activity, suggesting an association between the Trx system and functional changes in the progression of PAH. It seems that Trx-1 activation was an adaptive response to MCT administration to cope with pulmonary remodeling and disease progression, suggesting a potential new target for PAH therapeutics.

Expression of TXNIP in Cancer Cells and Regulation by 1,25(OH)₂D₃: Is It Really the Vitamin D₃ Upregulated Protein?

Thioredoxin-interacting protein (TXNIP) was originally identified in HL-60 cells as the vitamin D3 upregulated protein 1, and is now known to be involved in diverse cellular processes, such as maintenance of glucose homeostasis, redox balance, and apoptosis. Besides the initial characterization, little is known about if and how 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] induces TXNIP expression. We therefore screened multiple cancerous cell lines of different tissue origins, and observed induction, repression, or no change in TXNIP expression in response to 1,25(OH)2D3. In-depth analyses on HL-60 cells revealed a rapid and transient increase in TXNIP mRNA levels by 1,25(OH)2D3 (3–24 h), followed by a clear reduction at later time points. Furthermore, a strong induction in protein levels was observed only after 96 h of 1,25(OH)2D3 treatment. Induction of TXNIP expression by 1,25(OH)2D3 was found to be dependent on the availability of glucose in the culture medium, as well as the presence of a functional glucose transport system, indicating an inter-dependence of 1,25(OH)2D3 actions and glucose-sensing mechanisms. Moreover, the inhibition of de novo protein synthesis by cycloheximide reduced TXNIP half-life in 24 h, but not in 96 h-1,25(OH)2D3-treated HL-60 cells, demonstrating a possible influence of 1,25(OH)2D3 on TXNIP stability in long-term treatment.

Astragaloside IV ameliorates necrotizing enterocolitis by attenuating oxidative stress and suppressing inflammation via the vitamin D3-upregulated protein 1/NF-κB signaling pathway.

Astragaloside IV (AS-IV) is a flavonoid from the plant Astragalus membranaceus (Fisch) Bge that has a wide range of therapeutic effects. The aim of the present study was to examine the effect of AS-IV on rats with necrotizing enterocolitis (NEC) under oxidative stress and inflammation. Newborn Sprague-Dawley rats were induced with NEC by asphyxia and hypothermia applied on 3 consecutive days. The rats were orally administered AS-IV at 25, 50 and 75 mg/kg for 4 days. The results revealed that AS-IV administration prevented NEC-induced decrease in the concentration of malondialdehyde and myeloperoxidase, and increase in the activity of glutathione (GSH) and superoxide dismutase in murine models. AS-IV also inhibited NEC-induced elevation in the levels of interleukin (IL)-6, IL-1β, tumor necrosis factor-α and nuclear factor (NF)-κB. The effects of AS-IV were achieved under inflammation and oxidative stress. Western blotting demonstrated that AS-IV substantially inhibited the phosphorylated (p)-IκBα, NF-κBp65, p-NF-κBp65 protein levels and increased vitamin D3 upregulated protein 1 (VDUP1) and IκBα protein levels. These data indicate that AS-IV may be effective in the protection of NEC-induced ileum degeneration by inhibiting the levels of inflammatory markers and oxidative stress via the regulation of the VDUP1/NF-κB signaling pathway.

Antiasthmatic Effects of Eugenol in a Mouse Model of Allergic Asthma by Regulation of Vitamin D3 Upregulated Protein 1/NF-κB Pathway

The aim of the study was to investigate the antiasthmatic effects of eugenol (EUG) and the possible mechanisms. Asthma model was established by ovalbumin induction. A total of 50 mice were randomly assigned to five experimental groups: control, OVA, OVA + dexamethasone (2 mg/kg), OVA + EUG (10 mg/kg), and OVA + EUG (20 mg/kg). Airway resistance (Raw) were measured, histological studies were evaluated by the hematoxylin and eosin (HE) staining, interleukin-4 (IL-4) and interleukin-5 (IL-5) were evaluated by enzyme-linked immunosorbent assay (ELISA), Vitamin D3 upregulated protein 1 (VDUP1), IκBα, P-IκBα, NF-κBP65, and p-NF-κBP65 were measured by Western blotting. Our study demonstrated that EUG inhibited OVA-induced increases in Raw and eosinophil count; IL-4 and IL-5 were recovered. Histological studies demonstrated that EUG substantially inhibited OVA-induced eosinophilia in the lung tissue. Western blotting studies demonstrated that EUG substantially inhibited P-IκBα, NF-κBP65, and p-NF-κBP65 protein levels and increased VDUP1 and IκBα protein levels. These findings suggest that EUG may effectively ameliorate the progression of asthma and could be used as a therapy for patients with allergic asthma.

GW24-e1396 The relationship between thioredoxin-interacting protein expression in peripheral blood mononuclear cells and hypertension

ObjectivesThioredoxin-interacting protein (TXNIP) is a regulator of metabolism and inhibitor of the antioxidant thioredoxins. TXNIP binds thioredxins and is therefore also known as Thioredoxin-binding protein 2(TBP-2) or Vitamin D3 upregulated...

Vitamin D3 up-regulated protein 1 controls the priming phase of liver regeneration

Vitamin D3 up-regulated protein 1 (VDUP1) is a potent growth suppressor that inhibits tumor cell proliferation and cell cycle progression when overexpressed. In a previous study, we showed that VDUP1 knockout (KO) mice exhibited accelerated liver regeneration because such animals could effectively control the expression of cell cycle regulators that drive the G1-to-S phase progression. In the present study, we further investigated the role played by VDUP1 in initial priming of liver regeneration. To accomplish this, VDUP1 KO and wild-type (WT) mice were subjected to 70% partial hepatectomy (PH) and sacrificed at different times after surgery. The hepatic levels of TNF-α and IL-6 increased after PH, but there were no significant differences between VDUP1 KO and WT mice. Nuclear factor-κB (NF-κB), c-Jun-N-terminal kinase (JNK), and signal transducer and activator of transcription 3 (STAT-3) were activated much earlier and to a greater extent in VDUP1 KO mice after PH. A single injection of TNF-α or IL-6 caused rapid activation of JNK and STAT-3 expression in both mice, but the responses were stronger and more sustained in VDUP1 KO mice. In conclusion, our findings provide evidence that VDUP1 plays a role in initiation of liver regeneration.

VDUP1 exacerbates bacteremic shock in mice infected with Pseudomonas aeruginosa

Vitamin-D3 upregulated protein-1 (VDUP1) is a stress response protein. Pseudomonas aeruginosa (P. aeruginosa) infection is a leading cause of death. Mice infected with live P. aeruginosa exhibit significantly decreased VDUP1 expression. However, the function of VDUP1 during P. aeruginosa-induced mouse bacteremic shock is unknown. To address the function of VDUP1 in P. aeruginosa-infected mice, we constructed a bacteremic shock model wherein both wild-type and VDUP1-deficient mice were infected intra-peritoneally with live P. aeruginosa. We found that VDUP1-deficient mice were more resistant to P. aeruginosa-induced bacteremic shock than wild-type mice, as shown by the increased survival, accelerated bacterial clearance and suppression of cytokine overproduction of the VDUP1-deficient mice. VDUP1 promoted the recruitment of neutrophils into the peritoneal cavities of infected mice. VDUP1 impeded the phagocytosis of non-opsonized P. aeruginosa via phosphatidylinositide 3-kinase (PI3K) pathway in macrophages. P. aeruginosa infection induced the generation of reactive oxygen species (ROS), and the increased production of ROS by the peritoneal cells of VDUP1-deficient mice was advantageous in clearing the bacteria. Overall, VDUP1 aggravates bacteremic shock; thus, VDUP1 can be considered a target molecule for the inhibition of P. aeruginosa-induced bacteremic shock.

Vitamin D3 up-regulated protein 1 deficiency accelerates liver regeneration after partial hepatectomy in mice

Liver regeneration is a complicated process involving a variety of interacting factors. Vitamin D3 up-regulated protein 1 (VDUP1) is a potent growth suppressor that, upon over-expression, inhibits tumor cell proliferation and cell-cycle progression. Here, we investigated the function of VDUP1 in liver regeneration following hepatectomy in mice. Liver regeneration after 70% partial hepatectomy (PH) was compared in VDUP1 knockout (KO) and wild-type (WT) mice, and the activities of proliferative- and cell-cycle-related signaling pathways were measured. Compared with WT mice, liver recovery was significantly accelerated in VDUP1 KO mice during the first day after PH, in association with increased DNA synthesis. Consistent with this observation, the expression levels of key cell-cycle regulatory proteins, including cyclin D, cyclin E, cyclin-dependent kinase 4 (CDK4), p21, and p27, were markedly altered in the livers of VDUP1 KO mice. Induction of growth factors and activation of proliferative signaling pathway components including extracellular signal-regulated kinase 1/2 (ERK1/2), Akt, glycogen synthase kinase 3β (GSK3β), mammalian target of rapamycin (mTOR), and p70S6 kinase (p70(S6K)), occurred much earlier and to a greater extent in VDUP1 KO mouse livers. In addition, primary hepatocytes isolated from VDUP1 KO mice displayed increased activation of ERK1/2 and Akt in response to HGF and TGF-α. Our results reveal an important role for VDUP1 in the regulation of proliferative signaling during liver regeneration. Altered activation of genes involved in ERK1/2 and Akt signaling pathways may explain the accelerated growth responses seen in VDUP1 KO mice.

Vitamin D3 Up-regulated Protein 1(VDUP1) Is Regulated by FOXO3A and miR-17-5p at the Transcriptional and Post-transcriptional Levels, Respectively, in Senescent Fibroblasts

Vitamin D(3) up-regulated protein 1 (VDUP1) plays multifunctional roles in diverse cellular responses, particularly in its relation to proliferation, apoptosis, differentiation, and diseases such as cancer and stress-related diseases. In this study, we demonstrated that VDUP1 was up-regulated during the senescence process. Our results showed that overexpression of VDUP1 in young cells caused typical signs of senescence. We also found that VDUP1 knockdown delayed the onset of Ras-induced cellular senescence. Subsequently, we found that FOXO3A, whose activity increased in senescent cells, transcriptionally up-regulates VDUP1 expression and miR-17-5p, whose expression decreased in senescent cells, directly interacted with the 3'-untranslated region of VDUP1 transcripts, and destabilized VDUP1 mRNA in young cells. These results indicated that VDUP1 expression was regulated by FOXO3A at the transcriptional level and by miR-17-5p at the post-transcriptional levels during the senescence process.

The role of vitamin D3 upregulated protein 1 in thioacetamide-induced mouse hepatotoxicity

Thioacetamide (TA) is a commonly used drug that can trigger acute hepatic failure (AHF) through generation of oxidative stress. Vitamin D3 upregulated protein 1 (VDUP1) is an endogenous inhibitor of thioredoxin, a ubiquitous thiol oxidoreductase, that regulates cellular redox status. In this study, we investigated the role of VDUP1 in AHF using a TA-induced liver injury model. VDUP1 knockout (KO) and wild-type (WT) mice were subjected to a single intraperitoneal TA injection, and various parameters of hepatic injury were assessed. VDUP1 KO mice displayed a significantly higher survival rate, lower serum alanine aminotransferase and aspartate aminotransferase levels, and less hepatic damage, compared to WT mice. In addition, induction of apoptosis was decreased in VDUP1 KO mice, with the alteration of caspase-3 and -9 activities, Bax-to-Bcl-2 expression ratios, and mitogen activated protein kinase (MAPK) signaling pathway. Importantly, analysis of TA bioactivation revealed lower plasma clearance of TA and covalent binding of [ 14C]TA to liver macromolecules in VDUP1 KO mice. Furthermore, the level of oxidative stress was significantly less in VDUP1 KO mice than in their WT counterparts, as evident from lipid peroxidation assay. These results collectively indicate that VDUP1 deficiency protects against TA-induced acute liver injury via lower bioactivation of TA and antioxidant effects.

Anti-oxidative, anti-cancer and anti-inflammatory actions by thioredoxin 1 and thioredoxin-binding protein-2

Thioredoxin 1 (Trx 1) is a 12-kDa protein with redox-active dithiol in the active site –Cys–Gly–Pro–Cys– that is ubiquitously present in the human body. Trx 1 is a defensive protein induced by various stresses and has anti-oxidative, anti-apoptotic and anti-inflammatory effects. The anti-oxidative effect of Trx 1 is mediated by the dithiol–disulfide exchange in the active site. Trx 1 is able to interact with certain molecules, one of which is thioredoxin-binding protein-2 (TBP-2)/Vitamin D3 upregulated protein 1 (VDUP1)/thioredoxin interacting protein (TXNIP). TBP-2 was originally identified as a negative regulator of Trx 1 and acts as a cell growth suppressor and a regulator in lipid/glucose metabolism. Trx 1 and TBP-2 play crucial roles in pathophysiological mechanisms in metabolic disorders, cancer and inflammation. Here we discuss pharmacological aspects of Trx 1 and TBP-2 in these diseases and propose potential therapeutic approaches for intractable oxidative stress-related disorders.

Regulation of hematopoietic stem cell quiescence by TXNIP (36.1)

Abstract Hematopoietic stem cells (HSCs) are distinct cells that are predominantly located in the bone marrow microenvironment, which is referred to as the niche. HSC quiescence, activation, and mobilization are coordinately regulated in their niche by intrinsic and extrinsic mechanisms. Several genes, including those that encode transcriptional regulators, cell cycle regulatory proteins, tumor suppressors, and proto-oncogenes, intrinsically regulate the balance between HSC quiescence and activation. The vitamin D3 up-regulated protein 1 (VDUP1) is a 397 amino acid residue, 50-kDa protein that belongs to the arrestin family. We hypothesized that VDUP1 plays a pivotal role in controlling HSC cell cycle, migration, and BM niche interactions. The expression of VDUP1 is decreased during HSC activation. In VDUP1-/- mice, the LT-HSC population is decreased and exhausted, and its capacity to repopulate is rapidly lost. The VDUP1 deficiency reduced the osteopontin/integrin β1-mediated interaction between HSCs and the bone marrow niche and impaired homing and retention in the osteoblastic niche, resulting in mobilized HSCs. Thus, we propose that VDUP1 is essential for maintaining HSC quiescence and interactions with the BM niche.

Hedgehog-dependent down-regulation of the tumor suppressor, vitamin D 3 up-regulated protein 1 (VDUP1), precedes lamina development in Drosophila

The tumor suppressor vitamin D 3 up-regulated protein 1 (VDUP1) is expressed throughout the developing and mature Drosophila nervous system, but its regulatory pathways are not well understood. Within the developing Drosophila visual system, down-regulation of VDUP1 in lamina precursor cells (LPCs) coincided with the arrival of retinal axons into the lamina target field, suggesting VDUP1 regulation by an axonally transmitted signal. Hedgehog (Hh) is a signal well known to coordinate LPC proliferation and differentiation in response to retinal axon innervation, and analysis of orthologous dvdup1 promoters identified an evolutionarily conserved binding site for the Hh-dependent transcription factor cubitus interruptus (Ci). Hh-dependent regulation of VDUP1 in the developing lamina was confirmed in Hh loss-of-function backgrounds where VDUP1 expression was maintained in LPCs, inhibiting both cell proliferation and lamina neurogenesis. This putative coupling of VDUP1 to the Hh signaling pathway may provide novel insights into the mechanisms controlling brain growth and development.

Expression and regulation of vitamin D3 upregulated protein 1 (VDUP1) is conserved in mammalian and insect brain

Originally characterized as a cell-cycle inhibitor induced by vitamin D(3), the tumor suppressor vitamin-D(3) upregulated protein 1 (VDUP1) has increasingly been shown to play major physiological roles in cell differentiation and glucose metabolism. Here we show evolutionarily conserved expression patterns of VDUP1 in Drosophila and rat nervous systems, including subcellular localization--cytoplasmic enrichment in neurons and nuclear expression in glia. These anatomical correlates suggested conservation of VDUP1 regulation, which was investigated both functionally and through promoter studies. Characterization of orthologous vdup1 cis-regulatory regions identified evolutionarily conserved sequence blocks (CSBs) with similarities to neural enhancers, including basic helix-loop-helix (bHLH) transcription factor Neurogenin/Math/atonal and Mash/achaete-scute family members. E-boxes (CANNTG), the binding sites for bHLH proteins, were associated with these CSBs as well, including E-boxes known to mediate glucose-dependent upregulation of VDUP1 in nonneuronal cells. Hyperglycemia-induced upregulation of VDUP1 was observed in brain tumor cells and in the Drosophila nervous system, which resulted in developmental arrest. Taken together, these data demonstrate evolutionary conservation of VDUP1 regulation and function, and suggest an expanding role for VDUP1 in nervous system development.

Differential expression of H19 and vitamin D3 upregulated protein 1 as a mechanism of the modulatory effects of high virgin olive oil and high corn oil diets on experimental mammary tumours

Dietary lipids have a role in the aetiology of breast cancer. We have reported earlier that a high corn oil diet downregulates H19 and vitamin D3 upregulated protein 1 (VDUP1) messenger RNA (mRNA) expression in rat dimethylbenz (alpha) anthracene-induced mammary adenocarcinomas in comparison with the control low-fat diet, this effect being associated with a higher degree of tumour malignancy. This result was compatible with the stimulating effect of this diet. In this study we have investigated the influence of a high extra virgin olive diet on H19 and VDUP1 mRNA and/or protein expression. We have shown earlier that this high-fat diet confers to the tumours a more benign phenotype in accordance with its potential protective effect on mammary cancer. We have also analysed the effects on the mRNA and protein expression of insulin-like growth factor-2 , in close relation with H19, and the expression and activity of the thioredoxin protein, negatively regulated by VDUP1. mRNA and protein expression were analysed by chemiluminescent northern blot and western blot, respectively. Thioredoxin activity was determined by the insulin-reducing assay. The results showed that the high olive oil diet does not change the tumour expression of H19 and VDUP1. Moreover, tumours from the animals fed this diet displayed higher levels of the insulin-like growth factor-2 mRNAs, which are related to a higher rate of degradation or a lower traducibility. Finally, tumour expression and activity levels of thioredoxin-1 protein did not change irrespective of the diet. These results suggest that the differential effects of high olive oil and high corn oil diets on mammary cancer are exerted by means of a different, specific influence on gene expression.