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

The Emerging Role of TXNIP in Ischemic and Cardiovascular Diseases; A Novel Marker and Therapeutic Target

Thioredoxin interacting protein (TXNIP) is a metabolism- oxidative- and inflammation-related marker induced in cardiovascular diseases and is believed to represent a possible link between metabolism and cellular redox status. TXNIP is a potential biomarker in cardiovascular and ischemic diseases but also a novel identified target for preventive and curative medicine. The goal of this review is to focus on the novelties concerning TXNIP. After an overview in TXNIP involvement in oxidative stress, inflammation and metabolism, the remainder of this review presents the clues used to define TXNIP as a new marker at the genetic, blood, or ischemic site level in the context of cardiovascular and ischemic diseases.

The α-arrestin family of ubiquitin ligase adaptors links metabolism with selective endocytosis

The regulation of nutrient uptake into cells is important, as it allows to either increase biomass for cell growth or to preserve homoeostasis. A key strategy to adjust cellular nutrient uptake is the reconfiguration of the nutrient transporter repertoire at the plasma membrane by the addition of nutrient transporters through the secretory pathway and by their endocytic removal. In this review, we focus on the mechanisms that regulate selective nutrient transporter endocytosis, which is mediated by the α-arrestin protein family. In the budding yeast Saccharomyces cerevisiae, 14 different α-arrestins (also named arrestin-related trafficking adaptors, ARTs) function as adaptors for the ubiquitin ligase Rsp5. They instruct Rsp5 to ubiquitinate subsets of nutrient transporters to orchestrate their endocytosis. The ART proteins are under multilevel control of the major nutrient sensing systems, including amino acid sensing by the general amino acid control and target of rapamycin pathways, and energy sensing by 5'-adenosine-monophosphate-dependent kinase. The function of the six human α-arrestins is comparably under-characterised. Here, we summarise the current knowledge about the function, regulation and substrates of yeast ARTs and human α-arrestins, and highlight emerging communalities and general principles.

TXNIP Regulates Natural Killer Cell-Mediated Innate Immunity by Inhibiting IFN-γ Production during Bacterial Infection

The function of natural killer (NK) cell-derived interferon-γ (IFN-γ) expands to remove pathogens by increasing the ability of innate immune cells. Here, we identified the critical role of thioredoxin-interacting protein (TXNIP) in the production of IFN-γ in NK cells during bacterial infection. TXNIP inhibited the production of IFN-γ and the activation of transforming growth factor β-activated kinase 1 (TAK1) activity in primary mouse and human NK cells. TXNIP directly interacted with TAK1 and inhibited TAK1 activity by interfering with the complex formation between TAK1 and TAK1 binding protein 1 (TAB1). Txnip^−/− (KO) NK cells enhanced the activation of macrophages by inducing IFN-γ production during Pam3CSK4 stimulation or Staphylococcus aureus (S. aureus) infection and contributed to expedite the bacterial clearance. Our findings suggest that NK cell-derived IFN-γ is critical for host defense and that TXNIP plays an important role as an inhibitor of NK cell-mediated macrophage activation by inhibiting the production of IFN-γ during bacterial infection.

Thioredoxin-Interacting Protein (TXNIP) with Focus on Brain and Neurodegenerative Diseases

The development of new therapeutic approaches to diseases relies on the identification of key molecular targets involved in amplifying disease processes. One such molecule is thioredoxin-interacting protein (TXNIP), also designated thioredoxin-binding protein-2 (TBP-2), a member of the α-arrestin family of proteins and a central regulator of glucose and lipid metabolism, involved in diabetes-associated vascular endothelial dysfunction and inflammation. TXNIP sequesters reduced thioredoxin (TRX), inhibiting its function, resulting in increased oxidative stress. Many different cellular stress factors regulate TXNIP expression, including high glucose, endoplasmic reticulum stress, free radicals, hypoxia, nitric oxide, insulin, and adenosine-containing molecules. TXNIP is also directly involved in inflammatory activation through its interaction with the nucleotide-binding domain, leucine-rich-containing family, and pyrin domain-containing-3 (NLRP3) inflammasome complex. Neurodegenerative diseases such as Alzheimer’s disease have significant pathologies associated with increased oxidative stress, inflammation, and vascular dysfunctions. In addition, as dysfunctions in glucose and cellular metabolism have been associated with such brain diseases, a role for TXNIP in neurodegeneration has actively been investigated. In this review, we will focus on the current state of the understanding of possible normal and pathological functions of TXNIP in the central nervous system from studies of in vitro neural cells and the brains of humans and experimental animals with reference to other studies. As TXNIP can be expressed by neurons, microglia, astrocytes, and endothelial cells, a complex pattern of regulation and function in the brain is suggested. We will examine data suggesting TXNIP as a therapeutic target for neurodegenerative diseases where further research is needed.

TXNIP/VDUP1 attenuates steatohepatitis via autophagy and fatty acid oxidation

Impaired macroautophagy/autophagy has been implicated in experimental and human nonalcoholic steatohepatitis (NASH). However, the mechanism underlying autophagy dysregulation in NASH is largely unknown. Here, we investigated the role and mechanism of TXNIP/VDUP1 (thioredoxin interacting protein), a key mediator of cellular stress responses, in the pathogenesis of NASH. Hepatic TXNIP expression was upregulated in nonalcoholic fatty liver disease (NAFLD) patients and in methionine choline-deficient (MCD) diet-fed mice, as well as in palmitic acid (PA)-treated hepatocytes. Upregulation of hepatic TXNIP was positively correlated with impaired autophagy, as evidenced by a decreased number of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 beta) puncta and increased SQSTM1/p62 (sequestosome 1) expression. Deletion of the Txnip gene enhanced hepatic steatosis, inflammation, and fibrosis, accompanied by impaired autophagy and fatty acid oxidation (FAO) in MCD diet-fed mice. Mechanistically, TXNIP directly interacted with and positively regulated p-PRKAA, leading to inactivation of MTOR (mechanistic target of rapamycin kinase) complex 1 (MTORC1) and nuclear translocation of TFEB (transcription factor EB), which in turn promoted autophagy. Inhibition of MTORC1 by rapamycin induced autophagy and increased the expression levels of FAO-related genes and concomitantly attenuated lipid accumulation in PA-treated txnip-knockout (KO) hepatocytes, which was further abolished by silencing of Atg7. Rapamycin treatment also attenuated MCD diet-induced steatosis, inflammation, and fibrosis with increased TFEB nuclear translocation and restored FAO in txnip-KO mice. Our findings suggest that elevated TXNIP ameliorates steatohepatitis by interacting with PRKAA and thereby inducing autophagy and FAO. Targeting TXNIP may be a potential therapeutic approach for NASH.Abbreviations: ACOX1: acyl-Coenzyme A oxidase 1, palmitoyl; ACSL1: acyl-CoA synthetase long-chain family member 1; ACTA2/α-SMA: actin, alpha 2, smooth muscle, aorta; ACTB: actin beta; ADGRE1/F4/80: adhesion G protein-coupled receptor E1; AMPK: AMP-activated protein kinase; ATG: autophagy-related; BafA1: bafilomycin A1; COL1A1/Col1α1: collagen, type I, alpha 1; CPT1A: carnitine palmitoyltransferase 1a, liver; CQ: chloroquine; DGAT1: diacylglycerol O-acyltransferase 1; DGAT2: diacylglycerol O-acyltransferase 2; ECI2/Peci: enoyl-Coenzyme A isomerase 2; EHHADH: enoyl-Coenzyme A, hydratase/3-hydroxyacyl Coenzyme A dehydrogenase; FAO: fatty acid oxidation; FASN: fatty acid synthase; FFA: free fatty acids; GFP: green fluorescent protein; GK/GYK: glycerol kinase; GOT1/AST: glutamic-oxaloacetic transaminase 1, soluble; GPAM: glycerol-3-phosphate acyltransferase, mitochondrial; GPT/ALT: glutamic pyruvic transaminase, soluble; H&E: hematoxylin and eosin; IL1B/IL-1β: interleukin 1 beta; IL6: interleukin 6; IOD: integral optical density; KO: knockout; Leu: leupeptin; LPIN1: lipin 1; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MCD: methionine choline-deficient; MMP9: matrix metallopeptidase 9; mRNA: messenger RNA; MTORC1: mechanistic target of rapamycin kinase complex 1; NAFLD: nonalcoholic fatty liver diseases; NASH: nonalcoholic steatohepatitis; PA: palmitic acid; PPARA/PPARα: peroxisome proliferator activated receptor alpha; PPARG/PPARγ: peroxisome proliferator activated receptor gamma; qRT-PCR: quantitative real-time PCR; RPS6KB1/p70S6K1: ribosomal protein S6 kinase, polypeptide 1; RPTOR: regulatory associated protein of MTOR complex 1; SCD1: stearoyl-Coenzyme A desaturase 1; SEM: standard error of the mean; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TG: triglyceride; TGFB/TGF-β: transforming growth factor, beta; TIMP1: tissue inhibitor of metalloproteinase 1; TNF/TNF-α: tumor necrosis factor; TXNIP/VDUP1: thioredoxin interacting protein; WT: wild-type.

Laron Syndrome Research Paves the Way for New Insights in Oncological Investigation

Laron syndrome (LS) is a rare genetic endocrinopathy that results from mutation of the growth hormone receptor (GH-R) gene and is typically associated with dwarfism and obesity. LS is the best characterized entity under the spectrum of the congenital insulin-like growth factor-1 (IGF1) deficiencies. Epidemiological analyses have shown that LS patients do not develop cancer, whereas heterozygous family members have a cancer prevalence similar to the general population. To identify genes and signaling pathways differentially represented in LS that may help delineate a biochemical and molecular basis for cancer protection, we have recently conducted a genome-wide profiling of LS patients. Studies were based on our collection of Epstein–Barr virus (EBV)-immortalized lymphoblastoid cell lines derived from LS patients, relatives and healthy controls. Bioinformatic analyses identified differences in gene expression in several pathways, including apoptosis, metabolic control, cytokine biology, Jak-STAT and PI3K-AKT signaling, etc. Genes involved in the control of cell cycle, motility, growth and oncogenic transformation are, in general, down-regulated in LS. These genetic events seem to have a major impact on the biological properties of LS cells, including proliferation, apoptosis, response to oxidative stress, etc. Furthermore, genomic analyses allowed us to identify novel IGF1 downstream target genes that have not been previously linked to the IGF1 signaling pathway. In summary, by ‘mining’ genomic data from LS patients, we were able to generate clinically-relevant information in oncology and, potentially, related disciplines.

Redox homeostasis and cell cycle activation mediate beta-cell mass expansion in aged, diabetes-prone mice under metabolic stress conditions: Role of thioredoxin-interacting protein (TXNIP)

Overnutrition contributes to insulin resistance, obesity and metabolic stress, initiating a loss of functional beta-cells and diabetes development. Whether these damaging effects are amplified in advanced age is barely investigated. Therefore, New Zealand Obese (NZO) mice, a well-established model for the investigation of human obesity-associated type 2 diabetes, were fed a metabolically challenging diet with a high-fat, carbohydrate restricted period followed by a carbohydrate intervention in young as well as advanced age. Interestingly, while young NZO mice developed massive hyperglycemia in response to carbohydrate feeding, leading to beta-cell dysfunction and cell death, aged counterparts compensated the increased insulin demand by persistent beta-cell function and beta-cell mass expansion. Beta-cell loss in young NZO islets was linked to increased expression of thioredoxin-interacting protein (TXNIP), presumably initiating an apoptosis-signaling cascade via caspase-3 activation. In contrast, islets of aged NZOs exhibited a sustained redox balance without changes in TXNIP expression, associated with higher proliferative potential by cell cycle activation. These findings support the relevance of a maintained proliferative potential and redox homeostasis for preserving islet functionality under metabolic stress, with the peculiarity that this adaptive response emerged with advanced age in diabetes-prone NZO mice.

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Differential expression of redox and cell cycle genes in young and aged islets.

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Increased TXNIP expression is associated with the induction of beta-cell apoptosis.

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Islets of aged mice maintained redox homeostasis and proliferative potential.

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Aging under diet-induced metabolic stress does not amplify beta-cell failure.

Thioredoxin Interacting Protein (TXNIP) Is Differentially Expressed in Human Tumor Samples but Is Absent in Human Tumor Cell Line Xenografts: Implications for Its Use as an Immunosurveillance Marker

Simple Summary

The metabolic protein TXNIP plays a crucial role in various cellular processes. Abnormal TXNIP levels are notable, e.g., in type II diabetes, cardiovascular diseases, and tumors. Using immunohistochemical staining for TXNIP in different tumor entities, we give new insights of TXNIP expression on the protein level. In human tumors, staining intensity inversely correlated with aggressiveness of the tumor entity. In contrast, human tumor cell lines grown in mice (xenografts), consistently revealed no staining. Hence, loss of TXNIP suggests a critical role for the development of tumors in xenografts. Furthermore, we investigated TXNIP staining of immunocompetent cells in the proximity of the xenograft tumor tissue. Our findings demonstrate that TXNIP downregulation is a common feature in human tumor xenograft models. Subsequently, TXNIP expression might be used to monitor the functional state of tumor-infiltrating leukocytes in tissue sections and may help to predict response to modern immune therapy.

Abstract

Thioredoxin interacting protein (TXNIP) is a metabolic protein critically involved in redox homeostasis and has been proposed as a tumor suppressor gene in a variety of malignancies. Accordingly, TXNIP is downregulated in breast, bladder, and gastric cancer and in tumor transplant models TXNIP overexpression inhibits growth and metastasis. As TXNIP protein expression has only been investigated in few malignancies, we employed immunohistochemical detection in a large multi-tumor tissue microarray consisting of 2,824 samples from 94 different tumor entities. In general, TXNIP protein was present only in a small proportion of primary tumor samples and in these cases was differently expressed depending on tumor stage and subtype (e.g., renal cell carcinoma, thyroid cancer, breast cancer, and ductal pancreatic cancer). Further, TXNIP protein expression was determined in primary mouse xenograft tumors derived from human cancer cell lines and was immunohistochemically absent in all xenograft tumors investigated. Intriguingly, TXNIP expression became gradually lower in the proximity of the primary tumor tissue and was absent in leukocytes directly adjacent to tumor tissue. In conclusion, these findings suggest that TXNIP downregulation is as a common feature in human tumor xenograft models and that intra-tumoral leukocytes down-regulate TXNIP. Hence TXNIP expression might be used to monitor the functional state of tumor-infiltrating leukocytes in tissue sections.

Melatonin induced suppression of ER stress and mitochondrial dysfunction inhibited NLRP3 inflammasome activation in COPD mice

In recent decades, the occurrence of chronic obstructive pulmonary disease (COPD) has been increased remarkably in the population. Cigarette smoke (Cs) plays one of the key roles for COPD development. In our study, we explored the ameliorative role of melatonin on COPD progression by using a Cs inhaled in vivo COPD and cigarette smoke extract (CSE)-treated in vitro L-132 (alveolar epithelial cell) models. Mice exposed to Cs (4hr/day for 4 weeks) exhibited abrupt increase of lactate dehydrogenase (LDH) level in broncho alveolar lavage fluid (BALF) and disrupted alveolar structure in lung tissue. Additionally, increased reactive oxygen species (ROS), decreased cellular antioxidant status with reduced GSH/GSSG ratio were also found in Cs exposed lung. Besides, Cs induced endoplasmic reticulum (ER) stress and mitochondrial dysfunctions causing the activation of NLRP3 inflammasome. Activated NLRP3 inflammasome caused Caspase-1 mediated release of IL-1β and IL-18 resulting in inflammatory outburst. Melatonin showed protection against COPD both in vitro and in vivo. Exhibiting its anti-inflammatory potential, melatonin also attenuated the lung inflammation. It activated the intracellular antioxidant Thioredoxin-1 (thereby suppressing the TXNIP/NLRP3 pathway) and inhibited the impaired mitophagy mediated inflammasome activation (upregulating PINK-1, Parkin, LC3B-II expression). Melatonin also improved the overall antioxidant status of the COPD lung via NRF-2-HO-1 axis restoration.

ITCH regulates oxidative stress induced by high glucose through thioredoxin interacting protein in cultured human lens epithelial cells

Thioredoxin (Trx) is an important protein that controls oxidative damage in almost all eukaryotic cells. Trx interaction protein (Txnip) has been reported to negatively regulate the bioavailability of Trx and inhibit its biological function. The E3 ubiquitin ligase ITCH can specifically degrade Txnip via ubiquitination. The apoptosis of human lens epithelial cells (HLECs), which are highly sensitive to redox caused by oxidative stress, is a significant factor for the development of sugar cataract in a high-glucose environment. However, whether Trx, Txnip and ITCH contribute to the progression of sugar cataracts and the underlying mechanisms remain unknown, and thus, identifying these were the aims of the present study. The present results suggested that the expression levels of Trx, Txnip and ITCH in HLECs cultured with different glucose concentrations were detected by reverse transcription-quantitative PCR and western blotting, and the apoptotic rate of the cells was detected by flow cytometry and superoxide detection assay. The interaction between ITCH and Txnip was determined by co-localization immunofluorescence and co-immunoprecipitation. In addition, a vector and small interfering RNA of ITCH were transfected to overexpress and knockdown ITCH, respectively, to alter the expression of downstream proteins and cell apoptosis. It was found that Txnip was highly expressed in cultured HLECs in high-glucose environment, and the antioxidative function of Trx was restricted and suppressed, thus promoting apoptosis. The overexpression of ITCH increased the expression of Trx and decreased oxidative stress and apoptosis by decreasing Txnip in cultured HLECs, while downregulation of ITCH significantly decreased the expression of Trx and enhanced oxidative stress and apoptosis. Therefore, the present results indicated that ITCH could regulate the apoptosis of HLECs that were cultured in high-glucose concentration and that it may be a treatment target for sugar cataract.

E3 Ubiquitin ligase NEDD4 family‑regulatory network in cardiovascular disease

Protein ubiquitination represents a critical modification occurring after translation. E3 ligase catalyzes the covalent binding of ubiquitin to the protein substrate, which could be degraded. Ubiquitination as an important protein post-translational modification is closely related to cardiovascular disease. The NEDD4 family, belonging to HECT class of E3 ubiquitin ligases can recognize different substrate proteins, including PTEN, ENaC, Nav1.5, SMAD2, PARP1, Septin4, ALK1, SERCA2a, TGFβR3 and so on, via the WW domain to catalyze ubiquitination, thus participating in multiple cardiovascular-related disease such as hypertension, arrhythmia, myocardial infarction, heart failure, cardiotoxicity, cardiac hypertrophy, myocardial fibrosis, cardiac remodeling, atherosclerosis, pulmonary hypertension and heart valve disease. However, there is currently no review comprehensively clarifying the important role of NEDD4 family proteins in the cardiovascular system. Therefore, the present review summarized recent studies about NEDD4 family members in cardiovascular disease, providing novel insights into the prevention and treatment of cardiovascular disease. In addition, assessing transgenic animals and performing gene silencing would further identify the ubiquitination targets of NEDD4. NEDD4 quantification in clinical samples would also constitute an important method for determining NEDD4 significance in cardiovascular disease.

Acute bout of exercise downregulates thioredoxin-interacting protein expression in rat contracting skeletal muscles

We previously reported that in rat skeletal muscle, disuse (i.e., decreased muscle contractile activity) rapidly increases thioredoxin-interacting protein (TXNIP), which is implicated in the reduced glucose uptake. Accordingly, we sought herein to (a) determine the effect of exercise (i.e., increased muscle contractile activity) on muscle TXNIP protein expression, and (b) elucidate the mechanisms underlying the changes of TXNIP protein expression in response to exercise. Rat epitrochlearis and soleus muscles were dissected out after an acute bout of 3-hr swimming (without weight loading) or 3-hr treadmill running (15% grade at 9m/min). In a separate protocol, the isolated epitrochlearis and soleus muscles were incubated for 3 hr with AMP-dependent protein kinase activator AICAR. Immediately after the cessation of the 3-hr swimming, the TXNIP protein was decreased in epitrochlearis but not in soleus muscle. Conversely, 3-hr treadmill running decreased the TXNIP protein in soleus but not in epitrochlearis muscle. TXNIP protein was decreased concomitantly with reduced postexercise muscle glycogen, showing that a decrease in TXNIP protein expression occurs in muscles that are recruited during exercise. In addition, 3-hr incubation with AICAR decreased TXNIP protein in both isolated epitrochlearis and soleus muscles. Our results suggest that (a) an acute bout of exercise downregulates TXNIP protein expression in rat contracting skeletal muscles, and (b) the reduction in TXNIP protein expression in contracting muscles is probably mediated by AMPK activation, at least in part.

Enhanced Keap1-Nrf2/Trx-1 axis by daphnetin protects against oxidative stress-driven hepatotoxicity via inhibiting ASK1/JNK and Txnip/NLRP3 inflammasome activation

BACKGROUND

Oxidative stress-triggered fatal hepatotoxicity is an essential pathogenic factor in acute liver failure (ALF).

AIMS

To investigate the protective effect of daphnetin (Daph) on tert-butyl hydroperoxide (t-BHP) and acetaminophen (APAP)-induced hepatotoxicity through altering Nrf2/Trx-1 pathway activation.

MATERIALS AND METHODS

In vivo, male C57BL/6 mice with Wild-type (WT) and Nrf2^-/- were divided into five groups and acute liver injury model were established by APAP or LPS/GalN after injection with Daph (20, 40, or 80 mg/kg), seperately. Then, liver tissue and serum were collected for biochemical determination, TUNEL and H & E staining, and western blot analysis. In vitro, HepG2 cells were used to investigate the protective effect and mechanism of daphnetin against ROS and apoptosis induced by t-BHP via apoptosis detection, western blot, immunofluorescence analysis, and sgRNA transfection.

RESULTS

Our results indicated that Daph efficiently inhibited t-BHP-stimulated hepatotoxicity, and modulated Trx-1 expression and Nrf2 activation which decreased Keap1-overexpression in HepG2 cells. Moreover, Daph inhibited t-BHP-excited hepatotoxicity and enhanced Trx-1 expression, which was reversed in Nrf2^-/- HepG2 cells. In vivo, a survival rate analysis first suggested that Daph significantly reduced the lethality induced by APAP or GalN/LPS in a Nrf2-dependent or -independent manner by using Nrf2^-/- mice, respectively. Next, further results implicated that Daph not only effectively alleviated APAP-induced an increase of ALT and AST levels, histopathological changes, ROS overproduction, malondialdehyde (MDA) formation and GSH/GSSG reduction, but it also relieved hepatic apoptosis by strengthening the suppression of cleaved-caspase-3 and expression of P53 protein. Additionally, Daph attenuated mitochondrial dysfunction by suppressing ASK1/JNK activation and decreasing apoptosis-inducing factor (AIF) and Cytochrome c release and Bax mitochondrial translocation. Daph inhibited inflammatory responses by inactivating the thioredoxin-interacting protein (Txnip)/NLRP3 inflammasome. Furthermore, Daph efficiently enhanced Nrf2 nuclear translocation and Trx-1 expression. However, these effects in WT mice were eliminated in Nrf2^-/- mice.

CONCLUSIONS

These investigations demonstrated that Daph treatment has protective potential against oxidative stress-driven hepatotoxicity by inhibition of ASK1/JNK and Txnip/NLRP3 activation, which may be strongly related to the Nrf2/Trx-1 upregulation.

miR-93, miR-373, and miR-17-5p Negatively Regulate the Expression of TBP2 in Lung Cancer

Recently, several miRNAs have been revealed to play critical roles in oncogenesis and tumor progression of many cancers. Thioredoxin-1 (Trx-1) binding protein-2 (TBP-2) is an internal inhibitor of Trx-1, which plays the role in regulating oxidative stress, inhibiting cell growth, and promoting apoptosis. The expression of TBP-2 is usually decreased in cancer tissues. However, whether the miRNAs regulate the TBP-2 expression in lung cancer is still unclear. In this study, we examined the levels of TBP-2, miR-93, miR-373, and miR-17-5p in lung cancer tissues and their adjacent normal lung tissues of 36 patients. We found that the expressions of miR-93, miR-373, and miR-17-5p were higher, whereas the expression of TBP-2 mRNA and protein was significantly lower in lung cancer tissues compared with adjacent normal lung tissues. After the three miRNA mimics were transfected in the lung cancer cells, NCI-H460, the level of TBP-2 mRNA and TBP-2 protein was decreased. Then, the anti-cancer drug 5-fluorouracil was used to stimulate the NCI-H460 cells; the mRNA levels of miR-93, miR-373, and miR-17-5p were decreased, and the level of TBP-2 mRNA and protein was increased. Collectively, the above results suggest that miR-93, miR-373, and miR-17-5p negatively regulate the TBP-2 expression in lung cancer. This study may provide therapeutic targets with lung cancer.

Thioredoxin-interacting protein promotes activation and inflammation of monocytes with DNA demethylation in coronary artery disease

Numerous studies have demonstrated that thioredoxin‐interacting protein (TXNIP) expression of peripheral blood leucocytes is increased in coronary artery disease (CAD). However, the molecular mechanism of this phenomenon remained unclear. DNA methylation plays important roles in the regulation of gene expression. Therefore, we speculated there might be a close association between the expression of TXNIP and methylation. In this study, we found that compared with controls, DNA methylation at cg19693031 was decreased in CAD, while mRNA expressions of TXNIP and inflammatory factors, NLRP3, IL‐1β, IL‐18, were increased. Methylation at cg19693031 was negatively associated with TXNIP expression in the cohort, THP‐1 and macrophages/foam cells. Furthermore, Transwell assay and co‐cultured adhesion assay were performed to investigate functions of TXNIP on the migration of THP‐1 or the adhesion of THP‐1 on the surface of endothelial cells, respectively. Notably, overexpressed TXNIP promoted the migration and adhesion of THP‐1 cells and expressions of NLRP3, IL‐18 and IL‐1β. Oppositely, knock‐down TXNIP inhibited the migration and adhesion of THP‐1 and expressions of NLRP3, IL‐18. In conclusion, increased TXNIP expression, related to cg19693031 demethylation orientates monocytes towards an inflammatory status through the NLRP3 inflammasome pathway involved in the development of CAD.

Molecular analysis of lymphoid tissue from rhesus macaque rhadinovirus-infected monkeys identifies alterations in host genes associated with oncogenesis

Rhesus macaque (RM) rhadinovirus (RRV) is a simian gamma-2 herpesvirus closely related to human Kaposi’s sarcoma-associated herpesvirus (KSHV). RRV is associated with the development of diseases in simian immunodeficiency virus (SIV) co-infected RM that resemble KSHV-associated pathologies observed in HIV-infected humans, including B cell lymphoproliferative disorders (LPD) and lymphoma. Importantly, how de novo KSHV infection affects the expression of host genes in humans, and how these alterations in gene expression affect viral replication, latency, and disease is unknown. The utility of the RRV/RM infection model provides a novel approach to address these questions in vivo, and utilizing the RRV bacterial artificial chromosome (BAC) system, the effects of specific viral genes on host gene expression patterns can also be explored. To gain insight into the effects of RRV infection on global host gene expression patterns in vivo, and to simultaneously assess the contributions of the immune inhibitory viral CD200 (vCD200) molecule to host gene regulation, RNA-seq was performed on pre- and post-infection lymph node (LN) biopsy samples from RM infected with either BAC-derived WT (n = 4) or vCD200 mutant RRV (n = 4). A variety of genes were identified as being altered in LN tissue samples due to RRV infection, including cancer-associated genes activation-induced cytidine deaminase (AICDA), glypican-1 (GPC1), CX3C chemokine receptor 1 (CX3CR1), and Ras dexamethasone-induced 1 (RasD1). Further analyses also indicate that GPC1 may be associated with lymphomagenesis. Finally, comparison of infection groups identified the differential expression of host gene thioredoxin interacting protein (TXNIP), suggesting a possible mechanism by which vCD200 negatively affects RRV viral loads in vivo.

Targeting endothelial thioredoxin-interacting protein (TXNIP) protects from metabolic disorder-related impairment of vascular function and post-ischemic revascularisation

INTRODUCTION

Although thioredoxin-interacting protein (TXNIP) is involved in a variety of biological functions, the contribution of endothelial TXNIP has not been well-defined in regards to endothelial and vascular function or in post-ischemic revascularisation. We postulated that inhibition of endothelial TXNIP with siRNA or in a Cre-LoxP system could be involved in protection from high fat, high protein, low carbohydrate (HFHPLC) diet-induced oxidative stress and endothelial dysfunction, leading to vascular damage and impaired revascularisation in vivo.

METHODS AND RESULTS

To investigate the role of endothelial TXNIP, the TXNIP gene was deleted in endothelial cells using anti-TXNIP siRNA treatment or the Cre-LoxP system. Murine models were fed a HFHPLC diet, known to induce metabolic disorders. Endothelial TXNIP targeting resulted in protection against metabolic disorder-related endothelial oxidative stress and endothelial dysfunction. This protective effect mitigates media cell loss induced by metabolic disorders and hampered metabolic disorder-related vascular dysfunction assessed by aortic reactivity and distensibility. In aortic ring cultures, metabolic disorders impaired vessel sprouting and this alteration was alleviated by deletion of endothelial TXNIP. When subjected to ischemia, mice fed a HFHPLC diet exhibited defective post-ischemic angiogenesis and impaired blood flow recovery in hind limb ischemia. However, reducing endothelial TXNIP rescued metabolic disorder-related impairment of ischemia-induced revascularisation.

CONCLUSION

Collectively, these results show that targeting endothelial TXNIP in metabolic disorders is essential to maintaining endothelial function, vascular function and improving ischemia-induced revascularisation, making TXNIP a potential therapeutic target for therapy of vascular complications related to metabolic disorders.

Umbilical Cord-Derived Mesenchymal Stem Cells Ameliorate Nephrocyte Injury and Proteinuria in a Diabetic Nephropathy Rat Model

Mesenchymal stem cells (MSCs) are shown to alleviate renal injury of diabetic nephropathy (DN) in rats. However, the underlying mechanism of this beneficial effect is not fully understood. The aims of this study are to evaluate effects of umbilical cord-derived mesenchymal stem cells (UC-MSCs) on renal cell apoptosis in streptozotocin- (STZ-) induced diabetic rats and explore the underlying mechanisms. Characteristics of UC-MSCs were identified by flow cytometry and differentiation capability. Six weeks after DN induction by STZ injection in Sprague-Dawley rats, the DN rats received UC-MSCs once a week for consecutive two weeks. DN-related physical and biochemical parameters were measured at 2 weeks after UC-MSC infusion. Renal histological changes were also assessed. Moreover, the apoptosis of renal cells and expression of apoptosis-related proteins were evaluated. Compared with DN rats, rats treated with UC-MSCs showed suppressed increase in 24-hour urinary total protein, urinary albumin to creatinine ratio, serum creatinine, and blood urea nitrogen. UC-MSC treatment ameliorated pathological abnormalities in the kidney of DN rats as evidenced by H&E, PAS, and Masson Trichrome staining. Furthermore, UC-MSC treatment reduced apoptosis of renal cells in DN rats. UC-MSCs promoted expression of antiapoptosis protein Bcl-xl and suppressed expression of high mobility group protein B1 (HMGB1) in the kidney of DN rats. Most importantly, UC-MSCs suppressed upregulation of thioredoxin-interacting protein (TXNIP), downregulation of thioredoxin 1 (TRX1), and activation of apoptosis signal-regulating kinase 1 (ASK1) and P38 MAPK in the kidney of DN rats. Our results suggest that UC-MSCs could alleviate nephrocyte injury and albuminuria of DN rats through their antiapoptotic property. The protective effects of UC-MSCs may be mediated by inhibiting TXNIP upregulation in part.

Surface coatings alter transcriptional responses to silver nanoparticles following oral exposure

Silver nanoparticles (AgNPs) are used in food packaging materials, dental care products and other consumer goods and can result in oral exposure. To determine whether AgNP coatings modulate transcriptional responses to AgNP exposure, we exposed mice orally to 20 nm citrate (cit)-coated AgNPs (cit-AgNPs) or polyvinylpyrrolidone (PVP)-coated AgNPs (PVP-AgNPs) at a 4 mg/kg dose for 7 consecutive days and analyzed changes in the expression of protein-coding genes and long noncoding RNAs (lncRNAs), a new class of regulatory RNAs, in the liver. We identified unique and common expression signatures of protein-coding and lncRNA genes, altered biological processes and signaling pathways, and coding-non-coding gene interactions for cit-AgNPs and PVP-AgNPs. Commonly regulated genes comprised only about 10 and 20 percent of all differentially expressed genes in PVP-AgNP and cit-AgNP exposed mice, respectively. Commonly regulated biological processes included glutathione metabolic process and cellular oxidant detoxification. Commonly regulated pathways included Keap-Nrf2, PPAR, MAPK and IL-6 signaling pathways. The coding-non-coding gene co-expression analysis revealed that protein-coding genes were co-expressed with a variable number of lncRNAs ranging from one to twenty three and may share functional roles with the protein-coding genes. PVP-AgNP exposure induced a more robust transcriptional response than cit-AgNP exposure characterized by more than two-fold higher number of differentially expressed both protein- coding and lncRNA genes. Our data demonstrate that the surface coating strongly modulates the spectrum and the number of differentially expressed genes after oral AgNP exposure. On the other hand, our data suggest that AgNP exposure can alter drug and chemical sensitivity, metabolic homeostasis and cancer risk irrespective of the coating type, warranting further investigations.

Small Molecules as Drugs to Upregulate Metastasis Suppressors in Cancer Cells

It is well-recognized that the majority of cancer-related deaths is attributed to metastasis, which can arise from virtually any type of tumor. Metastasis is a complex multistep process wherein cancer cells must break away from the primary tumor, intravasate into the circulatory or lymphatic systems, extravasate, proliferate and eventually colonize secondary sites. Since these molecular processes involve the coordinated actions of numerous proteins, targeted disruptions of key players along these pathways represent possible therapeutic interventions to impede metastasis formation and reduce cancer mortality. A diverse group of proteins with demonstrated ability to inhibit metastatic colonization have been identified and they are collectively known as metastasis suppressors. Given that the metastasis suppressors are often downregulated in tumors, drug-induced re-expression or upregulation of these proteins represents a promising approach to limit metastasis. Indeed, over 40 compounds are known to exhibit efficacy in upregulating the expression of metastasis suppressors via transcriptional or post-transcriptional mechanisms, and the most promising ones are being evaluated for their translational potentials. These small molecules range from natural products to drugs in clinical use and they apparently target different molecular pathways, reflecting the diverse nature of the metastasis suppressors. In this review, we provide an overview of the different classes of compounds known to possess the ability to upregulate one or more metastasis suppressors, with an emphasis on their mechanisms of action and therapeutic potentials.

Thioredoxin-Interacting Protein Promotes Phagosomal Acidification Upon Exposure to Escherichia coli Through Inflammasome-Mediated Caspase-1 Activation in Macrophages

In host defense, it is crucial to maintain the acidity of the macrophage phagosome for effective bacterial clearance. However, the mechanisms governing phagosomal acidification upon exposure to gram-negative bacteria have not been fully elucidated. In this study, we demonstrate that in macrophages exposed to Escherichia coli, the thioredoxin-interacting protein (TXNIP)-associated inflammasome plays a role in pH modulation through the activated caspase-1-mediated inhibition of NADPH oxidase. While there was no difference in early-phase bacterial engulfment between Txnip knockout (KO) macrophages and wild-type (WT) macrophages, Txnip KO macrophages were less efficient at destroying intracellular bacteria in the late phase, and their phagosomes failed to undergo appropriate acidification. These phenomena were associated with reactive oxygen species production and were reversed by treatment with an NADPH oxidase inhibitor or a caspase inhibitor. In line with these results, Txnip KO mice were more susceptible to both intraperitoneally administered E. coli and sepsis induced by cecum ligation and puncture than WT mice. Taken together, this study suggests that the TXNIP-associated inflammasome-caspase-1 axis regulates NADPH oxidase to modulate the pH of the phagosome, controlling bacterial clearance by macrophages.

Oxidative stress-mediated TXNIP loss causes RPE dysfunction

The disruption of the retinal pigment epithelium (RPE), for example, through oxidative damage, is a common factor underlying age-related macular degeneration (AMD). Aberrant autophagy also contributes to AMD pathology, as autophagy maintains RPE homeostasis to ensure blood–retinal barrier (BRB) integrity and protect photoreceptors. Thioredoxin-interacting protein (TXNIP) promotes cellular oxidative stress by inhibiting thioredoxin reducing capacity and is in turn inversely regulated by reactive oxygen species levels; however, its role in oxidative stress-induced RPE cell dysfunction and the mechanistic link between TXNIP and autophagy are largely unknown. Here, we observed that TXNIP expression was rapidly downregulated in RPE cells under oxidative stress and that RPE cell proliferation was decreased. TXNIP knockdown demonstrated that the suppression of proliferation resulted from TXNIP depletion-induced autophagic flux, causing increased p53 activation via nuclear localization, which in turn enhanced AMPK phosphorylation and activation. Moreover, TXNIP downregulation further negatively impacted BRB integrity by disrupting RPE cell tight junctions and enhancing cell motility by phosphorylating, and thereby activating, Src kinase. Finally, we also revealed that TXNIP knockdown upregulated HIF-1α, leading to the enhanced secretion of VEGF from RPE cells and the stimulation of angiogenesis in cocultured human retinal microvascular endothelial cells. This suggests that the exposure of RPE cells to sustained oxidative stress may promote choroidal neovascularization, another AMD pathology. Together, these findings reveal three distinct mechanisms by which TXNIP downregulation disrupts RPE cell function and thereby exacerbates AMD pathogenesis. Accordingly, reinforcing or restoring BRB integrity by targeting TXNIP may serve as an effective therapeutic strategy for preventing or attenuating photoreceptor damage in AMD.

A protein found in retinal cells promotes the development of age-related macular degeneration and may provide a therapeutic target. Sight loss through macular degeneration is triggered by disruption to the retinal pigment epithelium (RPE), a layer of cells that carries nutrients to the eye. RPE cells can be disrupted under oxidative stress conditions, but how this influences macular degeneration is unclear. Jeong-Ki Min and Sang-Hyun Lee at the Korea Research Institute of Bioscience and Biotechnology in Daejeon, South Korea, and co-workers found that oxidative stress reduces levels of the thioredoxin-interacting protein (TXNIP) in human RPE cell cultures. This interrupts cellular communication and disturbs the balance between cell proliferation and cell recycling. It also increases the levels of proteins that promote excess blood vessel formation, a key process contributing to macular degeneration.

REDD1 Activates a ROS-Generating Feedback Loop in the Retina of Diabetic Mice

Purpose

The present study was designed to evaluate the role of the stress response protein REDD1 in diabetes-induced oxidative stress and retinal pathology.

Methods

Wild-type and REDD1-deficient mice were administered streptozotocin to induce diabetes. Some mice received the antioxidant N-acetyl-l-cysteine (NAC). Visual function was assessed by virtual optometry. Retinas were analyzed by Western blotting. Reactive oxygen species (ROS) were assessed by 2,7-dichlorofluoroscein. Similar analyses were performed on R28 retinal cells in culture exposed to hyperglycemic conditions, NAC, and/or the exogenous ROS source hydrogen peroxide.

Results

In the retina of diabetic mice, REDD1 expression and ROS were increased. In cells in culture, hyperglycemic conditions enhanced REDD1 expression, ROS levels, and the mitochondrial membrane potential. However, similar effects were not observed in the retina of diabetic mice or cells lacking REDD1. In the retina of diabetic mice and cells exposed to hyperglycemic conditions, NAC normalized ROS and prevented an increase in REDD1 expression. Diabetic mice receiving NAC also exhibited improved contrast sensitivity as compared to diabetic controls. Hydrogen peroxide addition to culture medium increased REDD1 expression and attenuated Akt/GSK3 phosphorylation in a REDD1-dependent manner. In REDD1-deficient cells exposed to hyperglycemic conditions, expression of a dominant negative Akt or constitutively active GSK3 increased the mitochondrial membrane potential and promoted ROS.

Conclusions

The findings provide new insight into the mechanism whereby diabetes-induced hyperglycemia causes oxidative stress and visual dysfunction. Specifically, hyperglycemia-induced REDD1 activates a ROS-generating feedback loop that includes Akt/GSK3. Thus, therapeutic approaches targeting REDD1 expression and ROS may be beneficial for preventing diabetes-induced visual dysfunction.

Modulating Expression of Thioredoxin Interacting Protein (TXNIP) Prevents Secondary Damage and Preserves Visual Function in a Mouse Model of Ischemia/Reperfusion

Retinal neurodegeneration, an early characteristic of several blinding diseases, triggers glial activation, resulting in inflammation, secondary damage and visual impairment. Treatments that aim only at neuroprotection have failed clinically. Here, we examine the impact of modulating thioredoxin interacting protein (TXNIP) to the inflammatory secondary damage and visual impairment in a model of ischemia/reperfusion (IR). Wild type (WT) and TXNIP knockout (TKO) mice underwent IR injury by increasing intraocular pressure for 40 min, followed by reperfusion. An additional group of WT mice received intravitreal TXNIP-antisense oligomers (ASO, 100 µg/2 µL) 2 days post IR injury. Activation of Müller glial cells, apoptosis and expression of inflammasome markers and visual function were assessed. IR injury triggered early TXNIP mRNA expression that persisted for 14 days and was localized within activated Müller cells in WT-IR, compared to sham controls. Exposure of Müller cells to hypoxia-reoxygenation injury triggered endoplasmic reticulum (ER) stress markers and inflammasome activation in WT cells, but not from TKO cells. Secondary damage was evident by the significant increase in the number of occluded acellular capillaries and visual impairment in IR-WT mice but not in IR-TKO. Intervention with TXNIP-ASO prevented ischemia-induced glial activation and neuro-vascular degeneration, and improved visual function compared to untreated WT. Targeting TXNIP expression may offer an effective approach in the prevention of secondary damage associated with retinal neurodegenerative diseases.

Differentiation agents increase the potential AraC therapy of AML by reactivating cell death pathways without enhancing ROS generation

Acute myeloid leukemia (AML) has a poor prognosis and requires new approaches for treatment. We have reported that a combination of vitamin D-based cell differentiation agents (doxercalciferol/carnosic acid [D2/CA]) added following the cytotoxic drug arabinocytosine (AraC) increases AML cell death (CD), a model for improved therapy of this disease. Because AraC-induced CD is known to involve reactive oxygen species (ROS) generation, here we investigated if the modulation of cellular REDOX status plays a role in the enhancement of cell death (ECD) by D2/CA. Using thiol antioxidants, such as N-acetyl cysteine (NAC), we found a significant inhibition of ECD, yet this occurred in the absence of any detectable change in cellular ROS levels. In contrast, NAC reduced the vitamin D receptor (VDR) abundance and its signaling of ECD. Importantly, VDR knockdown and NAC similarly inhibited ECD without producing an additive effect. Thus, the proposed post-AraC therapy may be compromised by agents that reduce VDR levels in AML blasts.

Traditional and Novel Mechanisms of Heat Shock Protein 90 (HSP90) Inhibition in Cancer Chemotherapy Including HSP90 Cleavage

HSP90 is a molecular chaperone that increases the stability of client proteins. Cancer cells show higher HSP90 expression than normal cells because many client proteins play an important role in the growth and survival of cancer cells. HSP90 inhibitors mainly bind to the ATP binding site of HSP90 and inhibit HSP90 activity, and these inhibitors can be distinguished as ansamycin and non-ansamycin depending on the structure. In addition, the histone deacetylase inhibitors inhibit the activity of HSP90 through acetylation of HSP90. These HSP90 inhibitors have undergone or are undergoing clinical trials for the treatment of cancer. On the other hand, recent studies have reported that various reagents induce cleavage of HSP90, resulting in reduced HSP90 client proteins and growth suppression in cancer cells. Cleavage of HSP90 can be divided into enzymatic cleavage and non-enzymatic cleavage. Therefore, reagents inducing cleavage of HSP90 can be classified as another class of HSP90 inhibitors. We discuss that the cleavage of HSP90 can be another mechanism in the cancer treatment by HSP90 inhibition.

Dl-3-n-Butylphthalide Inhibits NLRP3 Inflammasome and Mitigates Alzheimer's-Like Pathology via Nrf2-TXNIP-TrX Axis

AIMS

Oxidative stress and neuroinflammation play important roles in the pathology of Alzheimer's disease (AD). Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of antioxidant thioredoxin, is suspected to be an important modulator of oxidative stress and inflammation. However, the underlying mechanism involved in the abnormal homeostasis of TXNIP-thioredoxin (TrX) in AD pathogenesis remains unclear.

RESULTS

Using the Swedish mutant form of APP (APPswe)/PSEN1dE9 transgenic mouse (APP/PS1) and human-derived neuronal cells as model systems, we disclosed the impairment of the nuclear factor erythroid 2-related factor 2 (Nrf2)-TXNIP-TrX signaling in Alzheimer's-like pathology. We observed that the immune staining of TXNIP was increased in postmortem AD brain. The chronic accumulation of inflammatory mediator in neuronal cells facilitates interactions of TXNIP-nucleotide binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3) and NLRP3-ASC, which increases β-amyloid (Aβ) secretion. The antioxidant Dl-3-n-butylphthalide (Dl-NBP) is commonly used for cerebral ischemia treatment. In our study, we elucidated for new mechanisms by which Dl-NBP enhanced TrX activity, suppressed TXNIP, and ameliorated neuronal apoptosis in the APP/PS1 mouse brains. In human glioblastoma A172 cells and neuroblastoma SH-SY5Y cells, we delineated the Dl-NBP-mediated signaling pathways by which Dl-NBP-dependent upregulation of Nrf2 mediated the reciprocal regulation of reducing proinflammatory cytokine and inhibiting Aβ production in the glial and neuronal cells overexpressing APPswe.

INNOVATION

Our data provide a novel insight into the molecular mechanism that impairments of Nrf2-TXNIP-TrX system may be involved in the imbalance of cellular redox homeostasis and inflammatory damage in the AD brain.

CONCLUSION

Dl-NBP treatment could suppress TXNIP-NLRP3 interaction and inhibit NLRP3 inflammasome activation via upregulating Nrf2. These findings may provide an instrumental therapeutic approach for AD. Antioxid. Redox Signal. 00, 000-000.

Cellular acidosis triggers human MondoA transcriptional activity by driving mitochondrial ATP production

Human MondoA requires glucose as well as other modulatory signals to function in transcription. One such signal is acidosis, which increases MondoA activity and also drives a protective gene signature in breast cancer. How low pH controls MondoA transcriptional activity is unknown. We found that low pH medium increases mitochondrial ATP (mtATP), which is subsequently exported from the mitochondrial matrix. Mitochondria-bound hexokinase transfers a phosphate from mtATP to cytoplasmic glucose to generate glucose-6-phosphate (G6P), which is an established MondoA activator. The outer mitochondrial membrane localization of MondoA suggests that it is positioned to coordinate the adaptive transcriptional response to a cell’s most abundant energy sources, cytoplasmic glucose and mtATP. In response to acidosis, MondoA shows preferential binding to just two targets, TXNIP and its paralog ARRDC4. Because these transcriptional targets are suppressors of glucose uptake, we propose that MondoA is critical for restoring metabolic homeostasis in response to high energy charge.

Molecular analysis of NPAS3 functional domains and variants

Background

NPAS3 encodes a transcription factor which has been associated with multiple human psychiatric and neurodevelopmental disorders. In mice, deletion of Npas3 was found to cause alterations in neurodevelopment, as well as a marked reduction in neurogenesis in the adult mouse hippocampus. This neurogenic deficit, alongside the reduction in cortical interneuron number, likely contributes to the behavioral and cognitive alterations observed in Npas3 knockout mice. Although loss of Npas3 has been found to affect proliferation and apoptosis, the molecular function of NPAS3 is largely uncharacterized outside of predictions based on its high homology to bHLH–PAS transcription factors. Here we set out to characterize NPAS3 as a transcription factor, and to confirm whether NPAS3 acts as predicted for a Class 1 bHLH–PAS family member.

Results

Through these studies we have experimentally demonstrated that NPAS3 behaves as a true transcription factor, capable of gene regulation through direct association with DNA. NPAS3 and ARNT are confirmed to directly interact in human cells through both bHLH and PAS dimerization domains. The C-terminus of NPAS3 was found to contain a functional transactivation domain. Further, the NPAS3::ARNT heterodimer was shown to directly regulate the expression of VGF and TXNIP through binding of their proximal promoters. Finally, we assessed the effects of three human variants of NPAS3 on gene regulatory function and do not observe significant deficits.

Conclusions

NPAS3 is a true transcription factor capable of regulating expression of target genes through their promoters by directly cooperating with ARNT. The tested human variants of NPAS3 require further characterization to identify their effects on NPAS3 expression and function in the individuals that carry them. These data enhance our understanding of the molecular function of NPAS3 and the mechanism by which it contributes to normal and abnormal neurodevelopment and neural function.

Electronic supplementary material

The online version of this article (10.1186/s12867-018-0117-4) contains supplementary material, which is available to authorized users.

Potential role of α-lipoic acid and Ginkgo biloba against silver nanoparticles-induced neuronal apoptosis and blood-brain barrier impairments in rats

AIMS

This study explored whether silver nanoparticles (AgNPs) can disrupt tight-junctions integrity resulted in blood-brain barrier dysfunction along with oxidative stress, pro-inflammation, and apoptosis induction. Additionally, neuroprotective activities of α-lipoic acid (LA) and Ginkgo biloba (GB) were investigated.

MAIN METHODS

Forty adults rats were enrolled into; Control, AgNPs (50 mg/kg), LA (100 mg/kg) + AgNPs, and GB (120 mg/kg) + AgNPs. After 30 days, neuronal changes were assessed biochemically and histopathologically. Brain tissues oxidative indices, mRNA expression of proinflammatory cytokines and tight-junction proteins and pro-apoptotic biomarker, caspase-3 were investigated.

KEY FINDINGS

AgNPs exposure enhanced lipid peroxidation (+195%) along with declines in glutathione (-43%), glutathione peroxidase (-34%), glutathione S-transferase (-31%), catalase (-43%), and superoxide dismutase (-38%) activities in brain tissues. The apparent brain oxidative damage was associated with obvious neuronal dysfunction that was ascertained by neuropathological lesions. AgNPs lowered serum acetylcholine esterase, iron and copper levels, and increased creatine phosphokinase and creatine phosphokinase-brain type activities. Following AgNPs exposure, brain silver and iron contents were increased, but the copper level was decreased. AgNPs up-regulated TNF-α (6.5-fold) and IL-1β (8.9-fold) transcript levels, and simultaneously over-expressed the caspase-3 protein in cerebrum and cerebellum inducing cell apoptosis. Moreover, AgNPs down-regulated the transcript levels of tight-junction proteins; JP-1 (0.65-fold) and JAM-3(0.81-fold).

SIGNIFICANCE

LA and relatively GB improved the serious effects of AgNPs on the blood-brain barrier function and tight-junction proteins through their antioxidants, anti-inflammatory, and anti-apoptotic efficacies. Co-treatment with LA or GB may be favorable in ameliorating the neurotoxic side effects of AgNPs.

Both Ser361 phosphorylation and the C-arrestin domain of thioredoxin interacting protein are important for cell cycle blockade at the G1/S checkpoint

Thioredoxin interacting protein (TXNIP) is a novel tumor suppressor that is down‐regulated in several cancer tissues and tumor cell lines. Overexpression of TXNIP causes cell cycle arrest at the G1/S checkpoint in the hepatocellular carcinoma cell line HuH‐7. TXNIP contains putative phosphorylation sites, but the effects of its phosphorylation have not been fully characterized. TXNIP also contains two α‐arrestin domains (N‐arrestin and C‐arrestin) whose functions are not fully understood. Here, we reveal an association between TXNIP and cell cycle regulatory proteins (p27^kip1, Jun activation domain‐binding protein 1 (JAB1), Cdk2, and cyclin E), suggesting its participation in cell cycle regulation. We observed phosphorylation of TXNIP and used both in vivo and in vitro kinase assays to demonstrate that TXNIP can be phosphorylated by p38 mitogen‐activated protein kinase. Furthermore, we also identified Ser361 in TXNIP as one of the major phosphorylation sites. Cell cycle analysis showed that Ser361 phosphorylation participates in TXNIP‐mediated cell cycle arrest. In addition, the C‐arrestin domain may also play an important role in cell cycle arrest. We also showed that phosphorylation at Ser361 may be important for the association of TXNIP with JAB1 and that the C‐arrestin domain is necessary for the nuclear localization of this molecule. Collectively, these studies reveal that TXNIP participates in cell cycle regulation through association with regulatory proteins, especially JAB1, and that C‐arrestin‐dependent nuclear localization is important for this function. This work may facilitate the development of a new cancer therapy strategy that targets TXNIP as a key molecule inhibiting cancer cell growth via cell cycle blockade at the G1/S checkpoint.

Targeting antioxidant enzymes as a radiosensitizing strategy

Radiotherapy represents a major anti-cancer modality and effectively kills cancer cells through generation of reactive oxygen species (ROS). However, cancer cells are commonly characterized by increased activity of ROS-scavenging enzymes in adaptation to intrinsic oxidative stress, leading to radioresistance. Abrogation of this defense network by pharmacological ROS insults therefore is shown to improve radioresponse in preclinical models; some of them are then tested in clinical trials. In this review, we address (1) the importance of ROS in radioresponse, (2) the main systems regulating redox homeostasis with a special focus on their prognostic effect and predictive role in radiotherapy, and (3) the potential radiosensitizers acting through inhibition of antioxidant enzymes.

Expression pattern of new genes regulating female sex differentiation and in vitro maturational status of oocytes in pigs

The processes underlying maturation of mammalian oocytes are considered crucial for the oocytes ability to undergo monospermic fertilization. The same factors of influence are suggested to impact the development of sex associated characteristics, allowing sex differentiation to progress during embryonic growth. The primary aim of the study was to analyze the gene ontology groups involved in regulation of porcine oocytes' response to endogenous stimuli. The results obtained would indicate potential genes influencing sex differentiation. Additionally, they could help to determine new genetic markers, expression profile of which is substantially regulated during porcine oocytes' in vitro maturation. To achieve that, porcine oocytes were collected for analysis before and after in vitro maturation. Pigs were used as they are a readily available model that presents significant similarity to humans in terms of physiology and anatomy. Microarray analysis of oocytes, before and after in vitro maturation was performed and later validated by RT-qPCR. We have particularly detected and analyzed genes belonging to gene ontology groups associated with hormonal stimulation during maturation of the oocytes, that exhibited significant change in expression (fold change ≥ |2|; p < 0.05) namely "Female sex differentiation" (CCND2, MMP14, VEGFA, FST, INHBA, NR5A1), "Response to endogenous stimulus" (INSR, ESR1, CCND2, TXNIP, TACR3, MMP14, FOS, AR, EGR2, IGFBP7, TGFBR3, BTG2, PLD1, PHIP, UBE2B) and "Response to estrogen stimulus" (INSR, ESR1, CCND2, IHH, TXNIP, TACR3, MMP14). Some of them were characteristic for just one of the described ontologies, while some belonged into multiple ontological terms. The genes were analyzed, with their relation to the processes of interest explained. Overall, the study provides us with a range of genes that might serve as molecular markers of in vitro maturation associated processes of the oocytes. This knowledge might serve as a reference for further studies and, after further validation, as a potentially useful knowledge in assessment of the oocytes during assisted reproduction processes.

Adenine derivatives invert high glucose-induced thioredoxin-interacting protein overexpression

Overexpression of thioredoxin-interacting protein (TXNIP) is associated with reduced insulin sensitivity and β-cell apoptosis. We have previously shown that W2476 inhibited high glucose-induced TXNIP expression at both mRNA and protein levels in INS-1E cells. In this study, we describe structural modification and optimization of W2476 leading to three more active derivatives, 8d, 8g, and 9h, capable of suppressing TXNIP expression in BG73 and INS-1E cells, increasing insulin production, and reducing high glucose-induced apoptosis in INS-1E cells.

BRCA1 deficiency sensitizes breast cancer cells to bromodomain and extra-terminal domain (BET) inhibition

BRCA1 is a tumor suppressor frequently mutated in breast and ovarian cancer, serving it as a target for therapeutic exploitation. Here, we show that BRCA1 has a synthetic lethality interaction with an epigenetics regulator, bromodomain and extra-terminal domain (BET). BET inhibition led to gene expression changes reversing MYC-dependent transcription repression of a redox regulator, thioredoxin-interacting protein (TXNIP), via switching the promoter occupant from MYC to MondoA:MLX complex. Reversing the MYC-TXNIP axis inhibited thioredoxin activity and elevated cellular oxidative stress, causing DNA damages that are detrimental to BRCA1-deficient breast cancer cells. Tumor xenograft models and breast cancer clinical data analyses further demonstrated an in vivo synthetic lethality interaction and clinical association between BET/TXNIP and BRCA1 deficiency in the survival of breast cancer patients.

BET Bromodomain inhibition promotes De-repression of TXNIP and activation of ASK1-MAPK pathway in acute myeloid leukemia

Background

Targeted therapy has always been the focus in developing therapeutic approaches in cancer, especially in the treatment of acute myeloid leukemia (AML). A new small molecular inhibitor, JQ1, targeting BRD4, which recognizes the acetylated lysine residues, has been shown to induce cell cycle arrest in different cancers by inhibiting MYC oncogene. However, the downstream signaling of MYC inhibition induced by BET inhibitor is not well understood.

Methods

In this study, we explored the more mechanisms of JQ1-induced cell death in acute myeloid lukemia and downstream signaling of JQ1.

Results

We found that JQ1 is able to reactivate the tumor suppressor gene, TXNIP, and induces apoptosis through the ASK1-MAPK pathway. Further studies confirmed that MYC could repress the expression of TXNIP through the miR-17-92 cluster.

Conclusions

These findings provide novel insight on how BET inhibitor can induce apoptosis in AML, and further support the development of BET inhibitors as a promising therapeutic strategy against AML.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4661-6) contains supplementary material, which is available to authorized users.

Differential Expression of TXNIP Isoforms in the Peripheral Leukocytes of Patients with Acute Myocardial Infarction

Background

Acute myocardial infarction (AMI) is the most serious type of coronary atherosclerotic heart disease (CAD). The pathological changes are characterized by atherosclerosis. Oxidative stress plays an important role in atherosclerosis. Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor and regulator of thioredoxin, could bind thioredoxin to regulate its expression and antioxidant activity negatively. The NCBI data show that there are two isoforms in TXNIP gene, namely, TXNIP1 and TXNIP2. Our previous studies have shown that TXNIP expression levels in patients with unstable angina pectoris (UAP) were increased compared with controls (CTR). However, no upregulation of TXNIP was detected in AMI patients.

Methods

The leucocytes were isolated from peripheral venous blood, and total RNA of the leucocytes was extracted. Then, real-time quantitative PCR was performed.

Results

mRNA levels of TXNIP2 in AMI were significantly increased compared with CTR (P < 0.05). However, the expression of TXNIP1 was downregulated in AMI, but the difference was not statistically significant (P > 0.05). Logistic regression analysis showed that TXNIP2 mRNA levels were significantly associated with AMI (OR = 2.207, P < 0.05).

Conclusions

The expression of TXNIP2, not TXNIP1, is upregulated in leukocytes of AMI patients, indicating that only TXNIP2 in circulating leucocytes may be involved in the pathogenesis of AMI.

The Function of Thioredoxin-Binding Protein-2 (TBP-2) in Different Diseases

Thioredoxin-binding protein-2 (TBP-2) has an important role in the redox system, but it plays a different role in many different diseases (e.g., various cancers, diabetes mellitus (DM), cardiovascular disease, and cataracts) by influencing cell proliferation, differentiation, apoptosis, autophagy, and metabolism. Distinct transcription factors (TFs) stimulated by different factors combine with binding sites or proteins to upregulate or downregulate TBP-2 expression, in order to respond to the change in the internal environment. Most research disclosed that the main function of TBP-2 is associating with thioredoxin (Trx) to inhibit the antioxidant capacity of Trx. Furthermore, the TBP-2 located in tissues, whether normal or abnormal, has the ability to cause the dysfunctioning of cells and even death through different pathways, such as shortening the cell cycle and inducing apoptosis or autophagy. Through these studies, we found that TBP-2 promoted the development of diseases which are involved in inflammatory and oxidative damage. To a certain extent, we believe that there is some hidden connection between the biological functions which TBP-2 participates in and some distinct diseases. This review presents only a summary of the roles that TBP-2 plays in cancer, DM, cataracts, and so on, as well as its universal mechanisms. Further investigations are needed for the cell signaling pathways of the effects caused by TBP-2. A greater understanding of the mechanisms of TBP-2 could produce potential new targets for the treatment of diseases, including cancer and diabetes, cardiovascular disease, and cataracts.

More than a syllable in fib-ROS-is: The role of ROS on the fibrotic extracellular matrix and on cellular contacts

Fibrosis is characterized by excess deposition of extracellular matrix (ECM). However, the ECM changes during fibrosis not only quantitatively but also qualitatively. Thus, the composition is altered as the expression of various ECM proteins changes. Moreover, also posttranslational modifications, secretion, deposition and crosslinkage as well as the proteolytic degradation of ECM components run differently during fibrosis. As several of these processes involve redox reactions and some of them are even redox-regulated, reactive oxygen species (ROS) influence fibrotic diseases. Redox regulation of the ECM has not been studied intensively, although evidences exist that the alteration of the ECM, including the redox-relevant processes of its formation and degradation, may be of key importance not only as a cause but also as a consequence of fibrotic diseases. Myofibroblasts, which have differentiated from fibroblasts during fibrosis, produce most of the ECM components and in return obtain important environmental cues of the ECM, including their redox-dependent fibrotic alterations. Thus, myofibroblast differentiation and fibrotic changes of the ECM are interdependent processes and linked with each other via cell-matrix contacts, which are mediated by integrins and other cell adhesion molecules. These cell-matrix contacts are also regulated by redox processes and by ROS. However, most of the redox-catalyzing enzymes are localized within cells. Little is known about redox-regulating enzymes, especially the ones that control the formation and cleavage of redox-sensitive disulfide bridges within the extracellular space. They are also important players in the redox-regulative crosstalk between ECM and cells during fibrosis.

Diabetes pathogenic mechanisms and potential new therapies based upon a novel target called TXNIP

PURPOSE OF REVIEW

Thioredoxin-interacting protein has emerged as a major factor regulating pancreatic β-cell dysfunction and death, key processes in the pathogenesis of type 1 and type 2 diabetes. Accumulating evidence based on basic, preclinical, and retrospective epidemiological research suggests that TXNIP represents a promising therapeutic target for diabetes. The present review is aimed at providing an update regarding these developments.

RECENT FINDINGS

TXNIP has been shown to be induced by glucose and increased in diabetes and to promote β-cell apoptosis, whereas TXNIP deletion protected against diabetes. More recently, TXNIP inhibition has also been found to promote insulin production and glucagon-like peptide 1 signaling via regulation of a microRNA. β-Cell TXNIP expression itself was found to be regulated by hypoglycemic agents, carbohydrate-response-element-binding protein, and cytosolic calcium or the calcium channel blocker, verapamil. Retrospective studies now further suggest that verapamil use might be associated with a lower incidence of type 2 diabetes in humans.

SUMMARY

TXNIP has emerged as a key factor in the regulation of functional β-cell mass and TXNIP inhibition has shown beneficial effects in a variety of studies. Thus, the inhibition of TXNIP may provide a novel approach to the treatment of diabetes.

Genomic and transcriptomic comparison of allergen and silver nanoparticle-induced mast cell degranulation reveals novel non-immunoglobulin E mediated mechanisms

Mast cells represent a crucial cell type in host defense; however, maladaptive responses are contributing factors in the pathogenesis of allergic diseases. Previous work in our laboratory has shown that exposure to silver nanoparticles (AgNPs) results in mast cell degranulation via a non-immunoglobulin E (IgE) mechanism. In this study, we utilized a systems biology approach to identify novel genetic factors playing a role in AgNP-induced mast cell degranulation compared to the classical activation by antigen-mediated FcεRI crosslinking. Mast cell degranulation was assessed in bone marrow-derived mast cells isolated from 23 strains of mice following exposure to AgNPs or FcεRI crosslinking with dinitrophenyl (DNP). Utilizing strain-dependent mast cell degranulation, an association mapping study identified 3 chromosomal regions that were significantly associated with mast cell degranulation by AgNP and one non-overlapping region associated with DNP-mediated degranulation. Two of the AgNP-associated regions correspond to genes previously reported to be associated with allergic disorders (Trac2 on chromosome 1 and Traf6 on chromosome 2) and an uncharacterized gene identified on chromosome 1 (Fam126b). In conjunction, RNA-sequencing performed on mast cells from the high and low responder strains revealed 3754 and 34 differentially expressed genes that were unique to DNP and AgNP exposures, respectively. Select candidate genes include Ptger4, a gene encoding a G-protein coupled receptor in addition to a multifunctional adaptor protein, Txnip, that may be driving mast cell degranulation by AgNP. Taken together, we identified novel genes that have not been previously shown to play a role in nanoparticle-mediated mast cell activation. With further functional evaluation in the future, these genes may be potential therapeutic targets in the treatment of non-IgE mediated mast cell-linked disorders.

Quercetin and Ascorbic Acid Suppress Fructose-Induced NLRP3 Inflammasome Activation by Blocking Intracellular Shuttling of TXNIP in Human Macrophage Cell Lines

The aim of this study was to identify the role of thioredoxin-interacting protein (TXNIP) and its interaction with antioxidants in the activation of the fructose-induced NOD-like receptor protein 3 (NLRP3) inflammasome in human macrophages. The study was performed with U937 and THP-1 macrophage cell lines. Total reactive oxygen species (ROS) were measured by flow cytometry. Interleukin-1β (IL-1β), IL-18, NLRP3, TXNIP, and caspase-1 protein expression was detected using western blotting. Quantitative real-time polymerase chain reaction was used to detect IL-1β, IL-18, and caspase-1 gene expression. Intracellular shuttling of TXNIP was assessed by immunofluorescent staining with MitoTracker Red. Increased production of ROS and expression of IL-1β, IL-18, and caspase-1 genes and proteins were observed in U937 and THP-1 cells incubated with fructose and were effectively inhibited by quercetin and ascorbic acid. Intracellular shuttling of TXNIP from the nucleus into the mitochondria was detected under stimulation with fructose, which was also attenuated by antioxidants quercetin and ascorbic acid but not butylated hydroxyanisole. Treatment of macrophages with fructose promoted the association between TXNIP and NLRP3 in the cytosol, sequentially resulting in the activation of the NLRP3 inflammasome. This study revealed that intracellular TXNIP protein is a critical regulator of activation of the fructose-induced NLRP3 inflammasome, which can be effectively blocked by the antioxidants quercetin and ascorbic acid.

Thioredoxin-Interacting Protein (TXNIP) in Cerebrovascular and Neurodegenerative Diseases: Regulation and Implication

Neurological diseases, including acute attacks (e.g., ischemic stroke) and chronic neurodegenerative diseases (e.g., Alzheimer's disease), have always been one of the leading cause of morbidity and mortality worldwide. These debilitating diseases represent an enormous disease burden, not only in terms of health suffering but also in economic costs. Although the clinical presentations differ for these diseases, a growing body of evidence suggests that oxidative stress and inflammatory responses in brain tissue significantly contribute to their pathology. However, therapies attempting to prevent oxidative damage or inhibiting inflammation have shown little success. Identification and targeting endogenous "upstream" mediators that normalize such processes will lead to improve therapeutic strategy of these diseases. Thioredoxin-interacting protein (TXNIP) is an endogenous inhibitor of the thioredoxin (TRX) system, a major cellular thiol-reducing and antioxidant system. TXNIP regulating redox/glucose-induced stress and inflammation, now is known to get upregulated in stroke and other brain diseases, and represents a promising therapeutic target. In particular, there is growing evidence that glucose strongly induces TXNIP in multiple cell types, suggesting possible physiological roles of TXNIP in glucose metabolism. Recently, a significant body of literature has supported an essential role of TXNIP in the activation of the NOD-like receptor protein (NLRP3)-inflammasome, a well-established multi-molecular protein complex and a pivotal mediator of sterile inflammation. Accordingly, TXNIP has been postulated to reside centrally in detecting cellular damage and mediating inflammatory responses to tissue injury. The majority of recent studies have shown that pharmacological inhibition or genetic deletion of TXNIP is neuroprotective and able to reduce detrimental aspects of pathology following cerebrovascular and neurodegenerative diseases. Conspicuously, the mainstream of the emerging evidences is highlighting TXNIP link to damaging signals in endothelial cells. Thereby, here, we keep the trend to present the accumulative data on CNS diseases dealing with vascular integrity. This review aims to summarize evidence supporting the significant contribution of regulatory mechanisms of TXNIP with the development of brain diseases, explore pharmacological strategies of targeting TXNIP, and outline obstacles to be considered for efficient clinical translation.

High dose of histone deacetylase inhibitors affects insulin secretory mechanism of pancreatic beta cell line

Objective. Histone deacytylase inhibitors (HDACis) inhibit the deacetylation of the lysine residue of proteins, including histones, and regulate the transcription of a variety of genes. Recently, HDACis have been used clinically as anti-cancer drugs and possible anti-diabetic drugs. Even though HDACis have been proven to protect the cytokine-induced damage of pancreatic beta cells, evidence also shows that high doses of HDACis are cytotoxic. In the present study, we, therefore, investigated the eff ect of HDACis on insulin secretion in a pancreatic beta cell line. Methods. Pancreatic beta cells MIN6 were treated with selected HDACis (trichostatin A, TSA; valproic acid, VPA; and sodium butyrate, NaB) in medium supplemented with 25 mM glucose and 13% heat-inactivated fetal bovine serum (FBS) for indicated time intervals. Protein expression of Pdx1 and Mafa in MIN6 cells was demonstrated by immunohistochemistry and immunocytochemistry, expression of Pdx1 and Mafa genes was measured by quantitative RT-PCR method. Insulin release from MIN6 cells and insulin cell content were estimated by ELISA kit. Superoxide production in MIN6 cells was measured using a Total ROS/Superoxide Detection System. Results. TSA, VPA, and NaB inhibited the expression of Pdx1 and Mafa genes and their products. TSA treatment led to beta cell malfunction, characterized by enhanced insulin secretion at 3 and 9 mM glucose, but impaired insulin secretion at 15 and 25 mM glucose. Th us, TSA induced dysregulation of the insulin secretion mechanism. TSA also enhanced reactive oxygen species production in pancreatic beta cells. Conclusions. Our results showed that HDACis caused failure to suppress insulin secretion at low glucose concentrations and enhance insulin secretion at high glucose concentrations. In other words, when these HDACis are used clinically, high doses of HDACis may cause hypoglycemia in the fasting state and hyperglycemia in the fed state. When using HDACis, physicians should, therefore, be aware of the capacity of these drugs to modulate the insulin secretory capacity of pancreatic beta cells.

miRNA-23a/CXCR4 regulates neuropathic pain via directly targeting TXNIP/NLRP3 inflammasome axis

BACKGROUND

Chemokine CXC receptor 4 (CXCR4) in spinal glial cells has been implicated in neuropathic pain. However, the regulatory cascades of CXCR4 in neuropathic pain remain elusive. Here, we investigated the functional regulatory role of miRNAs in the pain process and its interplay with CXCR4 and its downstream signaling.

METHODS

miRNAs and CXCR4 and its downstream signaling molecules were measured in the spinal cords of mice with sciatic nerve injury via partial sciatic nerve ligation (pSNL). Immunoblotting, immunofluorescence, immunoprecipitation, and mammal two-hybrid and behavioral tests were used to explore the downstream CXCR4-dependent signaling pathway.

RESULTS

CXCR4 expression increased in spinal glial cells of mice with pSNL-induced neuropathic pain. Blocking CXCR4 alleviated the pain behavior; contrarily, overexpressing CXCR4 induced pain hypersensitivity. MicroRNA-23a-3p (miR-23a) directly bounds to 3' UTR of CXCR4 mRNA. pSNL-induced neuropathic pain significantly reduced mRNA expression of miR-23a. Overexpression of miR-23a by intrathecal injection of miR-23a mimics or lentivirus reduced spinal CXCR4 and prevented pSNL-induced neuropathic pain. In contrast, knockdown of miR-23a by intrathecal injection of miR-23a inhibitor or lentivirus induced pain-like behavior, which was reduced by CXCR4 inhibition. Additionally, miR-23a knockdown or CXCR4 overexpression in naïve mice could increase the thioredoxin-interacting protein (TXNIP), which was associated with induction of NOD-like receptor protein 3 (NLRP3) inflammasome. Indeed, CXCR4 and TXNIP were co-expressed. The mammal two-hybrid assay revealed the direct interaction between CXCR4 and TXNIP, which was increased in the spinal cord of pSNL mice. In particular, inhibition of TXNIP reversed pain behavior elicited by pSNL, miR-23a knockdown, or CXCR4 overexpression. Moreover, miR-23a overexpression or CXCR4 knockdown inhibited the increase of TXNIP and NLRP3 inflammasome in pSNL mice.

CONCLUSIONS

miR-23a, by directly targeting CXCR4, regulates neuropathic pain via TXNIP/NLRP3 inflammasome axis in spinal glial cells. Epigenetic interventions against miR-23a, CXCR4, or TXNIP may potentially serve as novel therapeutic avenues in treating peripheral nerve injury-induced nociceptive hypersensitivity.

Identification of thioredoxin-interacting protein (TXNIP) as a downstream target for IGF1 action

Laron syndrome (LS), or primary growth hormone (GH) insensitivity, is the best-characterized entity among the congenital insulin-like growth factor 1 (IGF1) deficiencies. Life-long exposure to minute endogenous IGF1 levels is linked to low stature as well as a number of endocrine and metabolic abnormalities. While elevated IGF1 is correlated with increased cancer incidence, epidemiological studies revealed that patients with LS do not develop tumors. The mechanisms associated with cancer protection in LS are yet to be discovered. Recent genomic analyses identified a series of metabolic genes that are overrepresented in patients with LS. Given the augmented expression of these genes in a low IGF1 milieu, we hypothesized that they may constitute targets for IGF1 action. Thioredoxin-interacting protein (TXNIP) plays a critical role in cellular redox control by thioredoxin. TXNIP serves as a glucose and oxidative stress sensor, being commonly silenced by genetic or epigenetic events in cancer cells. Consistent with its enhanced expression in LS, we provide evidence that TXNIP gene expression is negatively regulated by IGF1. These results were corroborated in animal studies. In addition, we show that oxidative and glucose stresses led to marked increases in TXNIP expression. Supplementation of IGF1 attenuated TXNIP levels, suggesting that IGF1 exerts its antiapoptotic effect via inhibition of TXNIP Augmented TXNIP expression in LS may account for cancer protection in this condition. Finally, TXNIP levels could be potentially useful in the clinic as a predictive or diagnostic biomarker for IGF1R-targeted therapies.

Combined treatment with D-allose, docetaxel and radiation inhibits the tumor growth in an in vivo model of head and neck cancer

The present study was designed to evaluate the effect of one rare sugar, D-allose, on normal human cells and cutaneous tissue, and to investigate the radiosensitizing and chemosensitizing potential of D-allose in an in vivo model of head and neck cancer. Results indicated that D-allose did not inhibit the growth of normal human fibroblasts TIG-1 cells, and no apoptotic changes were observed after D-allose and D-glucose treatment. The mRNA expression levels of thioredoxin interacting protein (TXNIP) in TIG-1 cells after D-allose treatment increased by 2-fold (50.4 to 106.5). Conversely, the mRNA expression levels of TXNIP in HSC3 cancer cells increased by 74-fold (1.5 to 110.6), and the thioredoxin (TRX)/TXNIP ratio was markedly reduced from 61.7 to 1.4 following D-allose treatment. Combined multiple treatments with docetaxel, radiation and D-allose resulted in the greatest antitumor response in the in vivo model. Hyperkeratosis, epidermal thickening and tumor necrosis factor-α immunostaining were observed following irradiation treatment, but these pathophysiological reactions were reduced following D-allose administration. Thus, the present findings suggest that D-allose may enhance the antitumor effects of chemoradiotherapy whilst sparing normal tissues.