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

Identification and Experimental Validation of Prognostic miRNA Signature and Ferroptosis-Related Key Genes in Cervical Squamous Cell Carcinoma

OBJECTIVES

This study aimed to investigate the prognostic value of miRNAs and ferroptosis-related genes in cervical squamous cell carcinoma.

METHODS

We mined data from public databases for differentially expressed miRNAs, ferroptosis-related genes, and clinical parameters and constructed a prognostic risk model. The predictive performance of the model was evaluated using survival and receiver operating characteristic curve analyses. We combined the clinicopathological features to construct a nomogram and evaluated its efficacy using calibration and clinical decision curves. The correlation between miRNA characteristics, risk score, and the tumor microenvironment was also studied. Next, consensus and key genes were screened, and their biological functions were analyzed using KEGG, GO, GSEA, and drug sensitivity analysis. Finally, the expression of miRNAs and key genes was detected using qRT-PCR and western blotting to verify the prediction results.

RESULTS

Seven miRNA signatures (miR-100-3p, miR-301a-5p, miR-331-3p, miR-425-5p, miR-502-3p, miR-505-5p, and miR-629-3p) were generated, and prognostic risk and nomogram models were successfully constructed. These models exhibited good accuracy. miRNA signatures correlated with the tumor microenvironment. Twelve consensus genes and three key genes (SLC2A1, ANO6, and TXNIP) were screened and their biofunctional diversity was identified using various analytical methods. qRT-PCR and western blotting were used to verify the expression of miR-301a-5p, miR-505-5p, SLC2A1, and TXNIP in cervical squamous carcinoma. The results were consistent with those of bioinformatics analyses.

CONCLUSIONS

Seven miRNAs may serve as prognostic biomarkers of cervical squamous cell carcinoma. SLC2A1, ANO6, and TXNIP are associated with cervical squamous cell carcinoma and may serve as ferroptosis-related markers of the disease.

Copper Oxide Nanoparticles Induce Pulmonary Inflammation and Exacerbate Asthma via the TXNIP Signaling Pathway

Copper oxide nanoparticles (CuO NPs) have seen increasing use across various industries, raising significant concerns about their potential toxicity and the exacerbation of pre-existing conditions like asthma. Asthma, a chronic inflammatory condition of the airways, can be triggered or worsened by environmental factors such as allergens, air pollutants, and chemicals, including nanoparticles. This study aimed to investigate the pulmonary toxicity induced by CuO NPs and their impact on asthma, with a particular focus on the role of thioredoxin-interacting protein (TXNIP). Using an ovalbumin (OVA)-induced asthma model, we found that CuO NP exposure led to significant increases in inflammatory cell infiltration, cytokine production, airway hyperresponsiveness, OVA-specific immunoglobulin (Ig)E levels, and mucus production. These pathological changes were closely associated with the upregulation of TXNIP-related signaling pathways, including phosphorylated apoptosis signal-regulating kinase (p-ASK)1, the Bax/Bcl-2 ratio, and cleaved caspase-3 activation. Complementary in vitro experiments using NCI-H292 respiratory epithelial cells showed that CuO NP treatment enhanced TXNIP signaling and increased mRNA expression and the production of inflammatory cytokines. Notably, TXNIP knockdown significantly attenuated these CuO NP-induced effects. In conclusion, our findings suggest that CuO NP exposure not only induces pulmonary toxicity but also exacerbates asthma, primarily through the activation of the TXNIP signaling pathway.

Oxidative Stress in Cataract Formation: Is There a Treatment Approach on the Horizon?

Cataracts, a leading cause of blindness worldwide, are closely linked to oxidative stress-induced damage to lens epithelial cells (LECs). Key factors contributing to cataract formation include aging, arterial hypertension, and diabetes mellitus. Given the high global prevalence of cataracts, the burden of cataract-related visual impairment is substantial, highlighting the need for pharmacological strategies to supplement surgical interventions. Understanding the molecular pathways involved in oxidative stress during cataract development may offer valuable insights for designing novel therapeutic approaches. This review explores the role of oxidative stress in cataract formation, focusing on critical mechanisms, such as mitochondrial dysfunction, endoplasmic reticulum stress, loss of gap junctions, and various cell death pathways in LECs. Additionally, we discuss emerging therapeutic strategies and potential targeting options, including antioxidant-based treatments.

Thioredoxin-Interacting Protein's Role in NLRP3 Activation and Osteoarthritis Pathogenesis by Pyroptosis Pathway: In Vivo Study

Thioredoxin-interacting protein (TXNIP) has been involved in oxidative stress and activation of the NOD-like receptor protein-3 (NLRP3) inflammasome, directly linking it to the pyroptosis pathway. Furthermore, pyroptosis may contribute to the inflammatory process in osteoarthritis (OA). The purpose of this study was to investigate the role of TXNIP in activating the NLRP3 inflammasome through the pyroptosis pathway in an OA rat model. Destabilization of the medial meniscus (DMM) was induced in the OA model with intra-articular injections of adeno-associated virus (AAV) overexpressing (OE) or knocking down (KD) TXNIP. A total of 48 healthy rats were randomly divided into six groups (N = 8 each). During the experiment, the rats' weights, mechanical pain thresholds, and thermal pain thresholds were measured weekly. Morphology staining, micro-CT, 3D imaging, and immunofluorescence (IF) staining were used to measure the expression level of TXNIP, and ELISA techniques were employed. OE-TXNIP-AAV in DMM rats aggravated cartilage destruction and subchondral bone loss, whereas KD-TXNIP slowed the progression of OA. The histological results showed that DMM modeling and OE-TXNIP-AAV intra-articular injection caused joint structure destruction, decreased anabolic protein expression, and increased catabolic protein expression and pyroptosis markers. Conversely, KD-TXNIP-AAV slowed joint degeneration. OE-TXNIP-AVV worsened OA by accelerating joint degeneration and damage, while KD-TXNIP-AAV treatment had a protective effect.

Correlation between circulating advanced glycation end products and thioredoxin-interacting protein levels and renal fat content in type 2 diabetes mellitus patients

BACKGROUND

This study sought to explore the clinical relevance of the associations of serum levels of advanced glycation end products (AGEs), soluble receptor for AGEs (sRAGE), and thioredoxin-interacting protein (TXNIP) with the renal fat fraction (RFF) in individuals with type 2 diabetes mellitus (T2DM).

METHODS

A total of 133 patients with T2DM were enrolled in the study. RFF, which represents the renal fat level, was determined utilizing Dixon magnetic resonance imaging (MRI). Serum levels of AGEs, sRAGE, TXNIP, and other biochemical parameters were measured in patients who fasted.

RESULTS

RFF in T2DM patients was positively correlated with the fasting levels of C-peptide (CP), triglycerides (TG), AGEs, TXNIP, and sRAGE (P < 0.05) and negatively correlated with the high-density lipoprotein cholesterol (HDL-c) level (P < 0.05). Pearson's correlation analysis indicated that the serum levels of AGEs, sRAGE, and TXNIP were interrelated and positively correlated (P < 0.05). Then, all patients were assigned to four groups according to the RFF quartile. The HC, CP, TG, AGEs, sRAGE, TXNIP, and DKD percentages tended to increase as the RFF quartiles increased, while the HDL-c level tended to decrease (p for trend < 0.05). Next, multiple linear regression analysis was performed using RFF as the dependent variable. After controlling for covariates related to RFF, the results showed that the serum levels of AGEs and TXNIP were still significantly correlated with RFF.

CONCLUSION

These results suggest that circulating AGEs and TXNIP levels may be associated with ectopic fat accumulation in the kidneys of T2DM patients and may serve as indicators of the severity of renal fat deposition.

MicroRNA-204-5p Attenuates Oxidative Stress, Apoptosis and Inflammation by Targeting TXNIP in Diabetic Cataract

Diabetic cataract (DC) is a major cause of blindness in diabetic patients and it is characterized by early onset and rapid progression. MiR-204-5p was previously identified as one of the top five down-regulated miRNAs in human DC lens tissues. We aimed to determine the expression of miR-204-5p in human lens epithelial cells (HLECs) and explore its effects and mechanisms in regulating the progression of DC. The expression of miR-204-5p in the anterior capsules of DC patients and HLECs was examined by RT-qPCR. Bioinformatics tools were then used to identify the potential target of miR-204-5p. The relationship between miR-204-5p and the target gene was confirmed through a dual luciferase reporter assay. Additionally, the regulatory mechanism of oxidative stress, apoptosis, and inflammation in DC was investigated by overexpressing miR-204-5p using miR-204-5p agomir. The expression of miR-204-5p was downregulated in the anterior capsules of DC patients and HLECs. Overexpression of miR-204-5p reduced ROS levels, pro-apoptosis genes (Bid, Bax, caspase-3), and IL-1β production in HG-treated HLECs. TXNIP was the direct target of miR-204-5p by dual luciferase reporter assay. Therefore, this study demonstrated that miR-204-5p effectively reduced oxidative damage, apoptosis, and inflammation in HLECs under HG conditions by targeting TXNIP. Targeting miR-204-5p could be a promising therapeutic strategy for the potential treatment of DC.

Amino acid deprivation induces TXNIP expression by NRF2 downregulation

Thioredoxin-interacting protein (TXNIP) is sensitive to oxidative stress and is involved in the pathogenesis of various metabolic, cardiovascular, and neurodegenerative disorders. Therefore, several studies have suggested that TXNIP is a promising therapeutic target for several diseases, particularly cancer and diabetes. However, the regulation of TXNIP expression under amino acid (AA)-restricted conditions is not well understood. In the present study, we demonstrated that TXNIP expression was promoted by the deprivation of AAs, especially arginine, glutamine, lysine, and methionine, in non-small cell lung cancer (NSCLC) cells. Interestingly, we determined that increased TXNIP expression induced by AA deprivation was associated with nuclear factor erythroid 2-related factor 2 (NRF2) downregulation, but not with activating transcription factor 4 (ATF4) activation. Furthermore, N-acetyl-l-cysteine (NAC), a scavenger of reactive oxygen species (ROS), suppressed TXNIP expression in NSCLC cells deprived of AA. Collectively, the induction of TXNIP expression by AA deprivation was mediated by ROS production, potentially through NRF2 downregulation. Our findings suggest that TXNIP expression may be associated with the redox homeostasis of AA metabolism and provide a possible rationale for a therapeutic strategy to treat cancer with AA restriction.

miRNA-146a-5p Inhibits Hypoxia-Induced Myocardial Fibrosis Through EndMT

Cardiac Vascular disease particularly myocardial infarction (MI) is a threat to health worldwide. microRNAs (miRNAs) have been shown to regulate myocardial fibrosis. Therefore, it is potential to investigate the mechanism of miRNA and fibrosis following myocardial infarction. Hypoxia human cardiac microvascular endothelial cells (HCMECs) were selected for the vitro experimental model. The miR-146a-5p expression was tested via RT-qPCR. The level of endothelial-to-mesenchymal transition (EndMT) and fibrosis markers were detected by Western blotting and immunofluorescence. Then, the inflammation, cell viability and apoptosis were investigated. The target was predicted by an online database and verified by a dual-luciferase activity assay. An MI mouse model was created to validate that miR-146a-5p regulates cardiac fibrosis in vivo. MI mouse was transfected with miR-146a-5p lentivirus. Subsequently, its effect on cardiac fibrosis of infarcted hearts was assessed by In situ hybridization (ISH), Immunohistochemistry (IHC), Triphenylterazolium chloride (TTC) staining and Masson staining. Herein, we confirmed that miR-146a-5p was down-regulated in hypoxia HCMECs. Overexpression of miR-146a-5p inhibited hypoxia-induced cardiac fibrosis following myocardial infarction by inhibiting EndMT in HCMECs. Thioredoxin-interacting protein (TXNIP) was a target that was negatively regulated by miR-146a-5p. Up-regulation of miR-146a-5p inhibited cardiac fibrosis via regulating EndMT by targeting TXNIP, and it also regulated EndMT to inhibit cardiac fibrosis in vivo.

Integrative bioinformatics analysis and experimental validation of key biomarkers for risk stratification in primary biliary cholangitis

BACKGROUND

Primary biliary cholangitis (PBC) is an autoimmune liver disease, whose etiology is yet to be fully elucidated. Currently, ursodeoxycholic acid (UDCA) is the only first-line drug. However, 40% of PBC patients respond poorly to it and carry a potential risk of disease progression. So, in this study, we aimed to explore new biomarkers for risk stratification in PBC patients to enhance treatment.

METHODS

We first downloaded the clinical characteristics and microarray datasets of PBC patients from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified and subjected to enrichment analysis. Hub genes were further validated in multiple public datasets and PBC mouse model. Furthermore, we also verified the expression of the hub genes and developed a predictive model in our clinical specimens.

RESULTS

A total of 166 DEGs were identified in the GSE79850 dataset, including 95 upregulated and 71 downregulated genes. Enrichment analysis indicated that DEGs were significantly enriched in inflammatory or immune-related process. Among these DEGs, 15 risk-related genes were recognized and further validated in the GSE119600 cohort. Then, TXNIP, CD44, ENTPD1, and PDGFRB were identified as candidate hub genes. Finally, we proceeded to the next screening with these four genes in our serum samples and developed a three-gene panel. The gene panel could effectively identify those patients at risk of disease progression, yielding an AUC of 0.777 (95% CI, 0.657-0.870).

CONCLUSIONS

In summary, combining bioinformatics analysis and experiment validation, we identified TXNIP, CD44, and ENTPD1 as promising biomarkers for risk stratification in PBC patients.

USP5 promotes lipopolysaccharide-induced apoptosis and inflammatory response by stabilizing the TXNIP protein

BACKGROUND

The role of thioredoxin-interacting protein (TXNIP) in lipopolysaccharide-induced liver injury in mice has been reported, but the underlying mechanisms are poorly understood.

METHODS

We overexpressed deubiquitinase in cells overexpressing TXNIP and then detected the level of TXNIP to screen out the deubiquitinase regulating TXNIP; the interaction between TXNIP and deubiquitinase was verified by coimmunoprecipitation. After knockdown of a deubiquitinase and overexpression of TXNIP in Huh7 and HepG2 cells, lipopolysaccharide was used to establish a cellular inflammatory model to explore the role of deubiquitinase and TXNIP in hepatocyte inflammation.

RESULTS

In this study, we discovered that ubiquitin-specific protease 5 (USP5) interacts with TXNIP and stabilizes it through deubiquitylation in Huh-7 and HepG2 cells after treatment with lipopolysaccharide. In lipopolysaccharide-treated Huh-7 and HepG2 cells, USP5 knockdown increased cell viability, reduced apoptosis, and decreased the expression of inflammatory factors, including NLRP3, IL-1β, IL-18, ASC, and procaspase-1. Overexpression of TXNIP reversed the phenotype induced by knockdown USP5.

CONCLUSIONS

In summary, USP5 promotes lipopolysaccharide-induced apoptosis and inflammatory response by stabilizing the TXNIP protein.

Myocardial Glutathione Synthase and TRXIP Expression Are Significantly Elevated in Hypertension and Diabetes: Influence of Stress on Antioxidant Pathways

Antioxidant protection is one of the key reactions of cardiomyocytes (CMCs) in response to myocardial damage of various origins. The thioredoxin interacting protein (TXNIP) is an inhibitor of thioredoxin (TXN). Over the recent few years, TXNIP has received significant attention due to its wide range of functions in energy metabolism. In the present work, we studied the features of the redox-thiol systems, in particular, the amount of TXNIP and glutathione synthetase (GS) as markers of oxidative damage to CMCs and antioxidant protection, respectively. This study was carried out on 38-week-old Wistar-Kyoto rats with insulin-dependent diabetes mellitus (DM) induced by streptozotocin, on 38- and 57-week-old hypertensive SHR rats and on a model of combined hypertension and DM (38-week-old SHR rats with DM). It was found that the amount of TXNIP increased in 57-week-old SHR rats, in diabetic rats and in SHR rats with DM. In 38-week-old SHR rats, the expression of TXNIP significantly decreased. The expression of GS was significantly higher compared with the controls in 57-week-old SHR rats, in DM rats and in the case of the combination of hypertension and DM. The obtained data show that myocardial damage caused by DM and hypertension are accompanied by the activation of oxidative stress and antioxidant protection.

Immunomodulatory Role of Thioredoxin Interacting Protein in Cancer's Impediments: Current Understanding and Therapeutic Implications

Cancer, which killed ten million people in 2020, is expected to become the world's leading health problem and financial burden. Despite the development of effective therapeutic approaches, cancer-related deaths have increased by 25.4% in the last ten years. Current therapies promote apoptosis and oxidative stress DNA damage and inhibit inflammatory mediators and angiogenesis from providing temporary relief. Thioredoxin-binding protein (TXNIP) causes oxidative stress by inhibiting the function of the thioredoxin system. It is an important regulator of many redox-related signal transduction pathways in cells. In cancer cells, it functions as a tumor suppressor protein that inhibits cell proliferation. In addition, TXNIP levels in hemocytes increased after immune stimulation, suggesting that TXNIP plays an important role in immunity. Several studies have provided experimental evidence for the immune modulatory role of TXNIP in cancer impediments. TXNIP also has the potential to act against immune cells in cancer by mediating the JAK-STAT, MAPK, and PI3K/Akt pathways. To date, therapies targeting TXNIP in cancer are still under investigation. This review highlights the role of TXNIP in preventing cancer, as well as recent reports describing its functions in various immune cells, signaling pathways, and promoting action against cancer.

[The TXNIP/Trx-1/GPX4 pathway promotes ferroptosis in hippocampal neurons after hypoxia-ischemia in neonatal rats]

OBJECTIVES

To observe the change in ferroptosis in hippocampal neurons after hypoxia-ischemia (HI) in neonatal rats and investigate the related mechanism based on the TXNIP/Trx-1/GPX4 signaling pathway.

METHODS

Healthy neonatal Sprague-Dawley rats, aged 7 days, were randomly divided into three groups: sham-operation (n=30), hypoxic-ischemic brain damage (HIBD) (n=30) and siRNA (TXNIP siRNA) (n=12). The classic Rice-Vannucci method was used to establish a neonatal rat model of HIBD. At 6 hours, 24 hours, 72 hours, and 7 days after modeling, Western blot was used to measure the protein expression of GPX4 in the hippocampal tissue at the injured side; at 24 hours after modeling, laser speckle imaging combined with hematoxylin-eosin staining was used to determine whether the model was established successfully; NeuN/GPX4 and GFAP/GPX4 immunofluorescence staining combined with Western blot and other methods was used to measure the protein expression of GPX4 and the signal molecules TXNIP and Trx-1 in the hippocampal tissue at the injured side; the kits for determining the content of serum iron and tissue iron were used to measure the change in iron content; quantitative real-time PCR was used to measure the mRNA expression of TXNIP, Trx-1, and GPX4.

RESULTS

At 6 hours, 24 hours, 72 hours, and 7 days after modeling, the HIBD group had a significantly lower protein expression level of GPX4 than the sham-operation group (P<0.05). At 24 hours after modeling, the HIBD group had a significantly lower cerebral blood flow of the injured side than the sham-operation group (P<0.05), with loose and disordered arrangement and irregular morphology of hippocampal CA1 neurons at the injured side. Compared with the sham-operation group, the HIBD group had a significantly higher number of TXNIP+ cells and significantly lower numbers of Trx-1+ cells and NeuN+GPX4+/NeuN+ cells in the hippocampal CA1 region at the injured side (P<0.05), with almost no GFAP+GPX4+ cells in the hippocampal CA1 region. Compared with the sham-operation group, the HIBD group and the siRNA group had significantly higher levels of serum iron and tissue iron in the hippocampus at the injured side (P<0.05). Compared with the HIBD group, the siRNA group had significantly lower levels of serum iron and tissue iron in the hippocampus at the injured side (P<0.05). The HIBD group and the siRNA group had significantly higher mRNA and protein expression levels of TXNIP than the sham-operation group (P<0.05), and the siRNA group had significantly lower expression levels than the HIBD group (P<0.05). The HIBD group and the siRNA group had significantly lower mRNA and protein expression levels of Trx-1 and GPX4 in the hippocampus at the injured side than the sham-operation group (P<0.05), and the siRNA group had significantly higher expression levels than the HIBD group (P<0.05).

CONCLUSIONS

HI induces ferroptosis of hippocampal neurons in neonatal rats by activating the TXNIP/Trx-1/GPX4 pathway, thereby resulting in HIBD.

Comprehensive pan-cancer analysis reveals the prognostic value and immunological role of SPIB

It is well-established that SPIB is essential for the survival of mature B cells, playing a key role in diffuse large B-cell lymphoma, colorectal cancer, and lung cancer. However, no study has hitherto conducted a systematic pan-cancer analysis on SPIB. Herein, we analyzed the differential expression of SPIB in pan-cancer using The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases and found that SPIB was significantly upregulated in most cancers. In addition, SPIB was positively or negatively associated with prognosis in different cancers. We found that SPIB was significantly associated with tumor immune infiltration and immune checkpoint genes in more than 35 tumors by TIMER database analysis. In addition, SPIB was negatively correlated with Tumor mutational burden (TMB) and Microsatellite instability (MSI) in most tumors. Finally, GO/KEGG enrichment analysis revealed the possible involvement of SPIB in NF-kappa B and B-cell receptor signaling pathways. In conclusion, our comprehensive pan-cancer analysis of SPIB reveals its important role in tumor immunity, suggesting it has huge prospects for clinical application in cancer therapy.

The Thioredoxin System of Mammalian Cells and Its Modulators

Oxidative stress involves the increased production and accumulation of free radicals, peroxides, and other metabolites that are collectively termed reactive oxygen species (ROS), which are produced as by-products of aerobic respiration. ROS play a significant role in cell homeostasis through redox signaling and are capable of eliciting damage to macromolecules. Multiple antioxidant defense systems have evolved to prevent dangerous ROS accumulation in the body, with the glutathione and thioredoxin/thioredoxin reductase (Trx/TrxR) systems being the most important. The Trx/TrxR system has been used as a target to treat cancer through the thiol–disulfide exchange reaction mechanism that results in the reduction of a wide range of target proteins and the generation of oxidized Trx. The TrxR maintains reduced Trx levels using NADPH as a co-substrate; therefore, the system efficiently maintains cell homeostasis. Being a master regulator of oxidation–reduction processes, the Trx-dependent system is associated with cell proliferation and survival. Herein, we review the structure and catalytic properties of the Trx/TrxR system, its role in cellular signaling in connection with other redox systems, and the factors that modulate the Trx system.

TXNIP knockout improves cardiac function after myocardial infarction by promoting angiogenesis and reducing cardiomyocyte apoptosis

BACKGROUND

Myocardial infarction (MI) is a common cause of death. Thioredoxin-interacting protein (TXNIP) expression increases after MI, and it exerts a negative regulatory effect on cardiac function after MI. Our study aimed to investigate the specific regulatory mechanism of TXNIP on angiogenesis and cardiomyocyte apoptosis after MI.

METHODS

The TXNIP gene knock-in (TXNIP-KI) and knock-out (TXNIP-KO) mice were generated, respectively. Eight-week-old male TXNIP-KO, TXNIP-KI, and wild type (WT) mice were subjected to MI by permanent ligation of the left anterior descending artery. Cardiomyocyte apoptosis was detected by TUNEL assay on the 4th post-surgery day. The expressions of TXNIP, hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), phosphorylated protein kinase B (p-AKT), p-AMP-activated protein kinase (p-AMPK), cleaved caspase-3, and caspase-3 were detected by Western blot. Quantitative real-time PCR was performed to detect the expression of TXNIP, HIF-1α, VEGF, prolyl hydroxylase (PHD) 1, and factor inhibiting HIF (FIH). In addition, the superoxide dismutase (SOD) activity and malondialdehyde (MDA) level in each group were also measured. On day 7 after MI, the hearts of sacrificed animals were analyzed by immunohistochemistry to assess CD31 expression and determine the density of angiogenesis. One month after treatment, the cardiac functional and structural changes were determined by echocardiography and the level of myocardial fibrosis was observed by Masson staining.

RESULTS

Compared with WT mice, TXNIP-KO mice had a significantly improved cardiac functional recovery after MI, and the proportion of myocardial fibrosis area was dramatically reduced, cardiomyocyte apoptosis was decreased, and angiogenesis was significantly increased; TXNIP-KI mice reversed in these changes. The expression of HIF-1α, p-AKT, and p-AMPK increased after MI in TXNIP-KO mice, and the mRNA expression of PHD 1 and FIH decreased. TXNIP-KI mice reversed in these changes.

CONCLUSIONS

After MI, TXNIP down-regulated the level of HIF-1α and VEGF, reduced the number of angiogenesis, increased cardiomyocyte apoptosis, and ultimately led to a poor prognosis of ischemic myocardium. TXNIP was a protein with negative effects after MI and was expected to be a target for the prevention and treatment of MI.

Thioredoxin-interacting protein regulates keratinocyte differentiation: Implication of its role in psoriasis

Thioredoxin-interacting protein (TXNIP), also known as Vitamin-D upregulated protein-1 (VDUP-1), interacts with thioredoxin to regulate redox responses and participates in diverse disorders including metabolic, cardiovascular, inflammatory and malignant diseases. Psoriasis is characterized by chronic skin inflammation and an aberrant pattern of keratinocyte differentiation. Clinically, psoriasis is associated with various cardiometabolic comorbidities but studies on TXNIP's biological role in skin disorders are limited. In this study, we investigated TXNIP expression in psoriasis and its regulation in normal human epidermal keratinocytes (NHEKs), and then explored how TXNIP regulated skin keratinocyte differentiation to determine its role in psoriasis pathogenesis. Our immunohistochemical study demonstrated extensive TXNIP expression in the upper and lower epidermis of psoriasis compared to predominant TXNIP expression in the basal layer of normal skin. 1, 25-dihydroxyvitamin D₃  suppressed but TGF-α and EGF enhanced TXNIP expression in NHEKs. An inducer of keratinocyte differentiation, phorbol 12-myristate 13-acetate (PMA), also diminished TXNIP expression, which was reversed by PKC-δ knockdown. TXNIP knockdown reduced PMA-induced involucrin and transglutaminse-1 expression, and increased p63 expression in NHEKs but did not significantly affect cell proliferation. H₂ O₂ -induced ROS production and EGFR phosphorylation decreased in NHEKs with TXNIP knockdown. Furthermore, PMA-induced PKC-δ phosphorylation, TGF-α, and EGF-triggered EGFR phosphorylation were attenuated by TXNIP knockdown. Our results unraveled the regulation and function of TXNIP expression in skin keratinocytes and the cross-regulation between TXNIP and EGFR signaling. These findings imply a role of TXNIP in psoriasis and provide insight into the possible impact of TXNIP regulators on the skin or psoriasis.

Association of Circulating TXNIP Levels with Fatty Liver in Newly Diagnosed Type 2 Diabetes Mellitus

BACKGROUND AND AIMS

Thioredoxin-interacting protein (TXNIP), a crucial modulator of the redox system, plays a crucial role in modulating lipid/glucose metabolism. Hence, this study aimed to explore whether circulating TXNIP is associated with non-alcoholic fatty liver disease (NAFLD) among patients with type 2 diabetes mellitus (T2DM).

METHODS

We enrolled 110 new patients with T2DM. In this study, we determined hepatic fat fraction (HFF), which represents a hepatic fat level, by Dixon magnetic resonance imaging. TXNIP and the other biochemical profiles of the patients were measured using fasting plasma.

RESULTS

Among the 110 patients with T2DM, 41 were classified as without fatty liver, whereas 34 and 35 were with mild and moderate-to-severe fatty liver, respectively. The patients with diabetes and advanced fatty liver had significantly higher TXNIP levels (P <0.001) than other patients. The prevalence of severe NAFLD showed an increasing trend with the increase in TXNIP quartiles (for all trends, P <0.05). HFF showed a positive correlation with TXNIP (r = 0.516, P <0.001). Even main risk factors were adjusted, TXNIP level was associated with NAFLD as analyzed by logistic regression.

CONCLUSION

TXNIP level remarkably increases among diabetics, which shows its positive relationship with the severity of NAFLD. TXNIP is a promising NAFLD biomarker that offers an efficient way to evaluate and monitor fatty liver progression among patients with T2DM.

A Fluorine-19 Magnetic Resonance Probe, Shiga-Y5, Downregulates Thioredoxin-Interacting Protein Expression in the Brain of a Mouse Model of Alzheimer's Disease

Thioredoxin-interacting protein (TXNIP) is involved in multiple disease-associated functions related to oxidative stress, especially by inhibiting the anti-oxidant- and thiol-reducing activity of thioredoxin (TXN). Shiga-Y5 (SY5), a fluorine-19 magnetic resonance probe for detecting amyloid-β deposition in the brain, previously showed therapeutic effects in a mouse model of Alzheimer's disease; however, the mechanism of action of SY5 remains unclear. SY5 passes the blood-brain barrier and then undergoes hydrolysis to produce a derivative, Shiga-Y6 (SY6), which is a TXNIP-negative regulator. Therefore, this study investigates the therapeutic role of SY5 as the prodrug of SY6 in the thioredoxin system in the brain of a mouse model of Alzheimer's disease. The intraperitoneal injection of SY5 significantly inhibited TXNIP mRNA (p = 0.0072) and protein expression (p = 0.0143) induced in the brain of APP/PS1 mice. In contrast, the levels of TXN mRNA (p = 0.0285) and protein (p = 0.0039) in the brain of APP/PS1 mice were increased after the injection of SY5. The ratio of TXN to TXNIP, which was decreased (p = 0.0131) in the brain of APP/PS1 mice, was significantly increased (p = 0.0072) after the injection of SY5. These results suggest that SY5 acts as a prodrug of SY6 in targeting the thioredoxin system and could be a potential therapeutic compound in oxidative stress-related diseases in the brain.

Whole-transcriptome Analysis of Fully Viable Energy Efficient Glycolytic-null Cancer Cells Established by Double Genetic Knockout of Lactate Dehydrogenase A/B or Glucose-6-Phosphate Isomerase

BACKGROUND/AIM

Nearly all mammalian tumors of diverse tissues are believed to be dependent on fermentative glycolysis, marked by elevated production of lactic acid and expression of glycolytic enzymes, most notably lactic acid dehydrogenase (LDH). Therefore, there has been significant interest in developing chemotherapy drugs that selectively target various isoforms of the LDH enzyme. However, considerable questions remain as to the consequences of biological ablation of LDH or upstream targeting of the glycolytic pathway.

MATERIALS AND METHODS

In this study, we explore the biochemical and whole transcriptomic effects of CRISPR-Cas9 gene knockout (KO) of lactate dehydrogenases A and B [LDHA/B double KO (DKO)] and glucose-6-phosphate isomerase (GPI KO) in the human colon cancer cell line LS174T, using Affymetrix 2.1 ST arrays.

RESULTS

The metabolic biochemical profiles corroborate that relative to wild type (WT), LDHA/B DKO produced no lactic acid, (GPI KO) produced minimal lactic acid and both KOs displayed higher mitochondrial respiration, and minimal use of glucose with no loss of cell viability. These findings show a high biochemical energy efficiency as measured by ATP in glycolysis-null cells. Next, transcriptomic analysis conducted on 48,226 mRNA transcripts reflect 273 differentially expressed genes (DEGS) in the GPI KO clone set, 193 DEGS in the LDHA/B DKO clone set with 47 DEGs common to both KO clones. Glycolytic-null cells reflect up-regulation in gene transcripts typically associated with nutrient deprivation / fasting and possible use of fats for energy: thioredoxin interacting protein (TXNIP), mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), PPARγ coactivator 1α (PGC-1α), and acetyl-CoA acyltransferase 2 (ACAA2). Other changes in non-ergometric transcripts in both KOs show losses in "stemness", WNT signaling pathway, chemo/radiation resistance, retinoic acid synthesis, drug detoxification, androgen/estrogen activation, and extracellular matrix reprogramming genes.

CONCLUSION

These findings demonstrate that: 1) The "Warburg effect" is dispensable, 2) loss of the LDHAB gene is not only inconsequential to viability but fosters greater mitochondrial energy, and 3) drugs that target LDHA/B are likely to be ineffective without a plausible combination second drug target.

Role of Thioredoxin-Interacting Protein in Diseases and Its Therapeutic Outlook

Thioredoxin-interacting protein (TXNIP), widely known as thioredoxin-binding protein 2 (TBP2), is a major binding mediator in the thioredoxin (TXN) antioxidant system, which involves a reduction-oxidation (redox) signaling complex and is pivotal for the pathophysiology of some diseases. TXNIP increases reactive oxygen species production and oxidative stress and thereby contributes to apoptosis. Recent studies indicate an evolving role of TXNIP in the pathogenesis of complex diseases such as metabolic disorders, neurological disorders, and inflammatory illnesses. In addition, TXNIP has gained significant attention due to its wide range of functions in energy metabolism, insulin sensitivity, improved insulin secretion, and also in the regulation of glucose and tumor suppressor activities in various cancers. This review aims to highlight the roles of TXNIP in the field of diabetology, neurodegenerative diseases, and inflammation. TXNIP is found to be a promising novel therapeutic target in the current review, not only in the aforementioned diseases but also in prolonged microvascular and macrovascular diseases. Therefore, TXNIP inhibitors hold promise for preventing the growing incidence of complications in relevant diseases.

Increased Expression of TXNIP Facilitates Oxidative Stress in Nasal Epithelial Cells of Patients With Chronic Rhinosinusitis With Nasal Polyps

BACKGROUND

Oxidative stress plays crucial roles in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). Thioredoxin-interacting protein (TXNIP) is essential in the process of triggering oxidative stress. However, its role and mechanism in CRSwNP remain unclear. The present study sought to explore the role and mechanism of TXNIP in the pathogenesis of CRSwNP.

METHODS

Western blotting, real-time PCR and immunohistochemistry (IHC) were employed to assess TXNIP, thioredoxin (TRX) expression in nasal tissue samples from patients with CRSwNP and control subjects. MDA level and SOD activity in nasal tissue homogenates were measured using MDA and SOD Assay Kit. To evaluate the role and mechanism of TXNIP in CRSwNP, human nasal epithelial cells (HNECs) were cultured and stimulated using TXNIP siRNA, with or without N-acetylcysteine (NAC, an ROS scavenger). Western blotting, real-time PCR, ROS detecting dye DCFH-DA, MDA and SOD Assay Kit were performed to assess the effects and mechanisms of stimulators on the cells.

RESULTS

We found significantly increased levels of TXNIP and decreased levels of TRX protein, mRNA, positive cells, increased MDA level and decreased SOD activity in CRSwNP patients compared with control subjects. In vitro study, significantly altered levels of TXNIP, TRX, MDA, SOD and ROS in HNECs were found following treatment of TXNIP siRNA with or without NAC on HNECs.

CONCLUSION

TXNIP expression was increased and TRX expression was decreased in CRSwNP at both protein and mRNA levels. MDA levels were increased and SOD activities were decreased in CRSwNP. TXNIP may have negative association with TRX, and then decrease SOD activities and increase MDA levels, resulting in the upregulation of ROS and oxidative stress in HNECs, which may play a pivotal role in the pathogenesis of CRSwNP. Future studies are expected to further explore the role and mechanism of TXNIP in CRSwNP.

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.

Understanding the Biological Activities of Vitamin D in Type 1 Neurofibromatosis: New Insights into Disease Pathogenesis and Therapeutic Design

Vitamin D is a fat-soluble steroid hormone playing a pivotal role in calcium and phosphate homeostasis as well as in bone health. Vitamin D levels are not exclusively dependent on food intake. Indeed, the endogenous production-occurring in the skin and dependent on sun exposure-contributes to the majority amount of vitamin D present in the body. Since vitamin D receptors (VDRs) are ubiquitous and drive the expression of hundreds of genes, the interest in vitamin D has tremendously grown and its role in different diseases has been extensively studied. Several investigations indicated that vitamin D action extends far beyond bone health and calcium metabolism, showing broad effects on a variety of critical illnesses, including cancer, infections, cardiovascular and autoimmune diseases. Epidemiological studies indicated that low circulating vitamin D levels inversely correlate with cutaneous manifestations and bone abnormalities, clinical hallmarks of neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant tumour predisposition syndrome causing significant pain and morbidity, for which limited treatment options are available. In this context, vitamin D or its analogues have been used to treat both skin and bone lesions in NF1 patients, alone or combined with other therapeutic agents. Here we provide an overview of vitamin D, its characteristic nutritional properties relevant for health benefits and its role in NF1 disorder. We focus on preclinical and clinical studies that demonstrated the clinical correlation between vitamin D status and NF1 disease, thus providing important insights into disease pathogenesis and new opportunities for targeted therapy.

Correlation Between Thioredoxin-Interacting Protein and Nerve Conduction Velocity in Patients With Type 2 Diabetes Mellitus

Aims: To investigate the correlation between thioredoxin-interacting protein (TXNIP) and peripheral nerve conduction velocity (NCV) in patients with type 2 diabetes mellitus.

Methods: In total, 338 patients with type 2 diabetes mellitus (T2DM) were included in this study. We collected the clinical data and measured the motor conduction velocities of the bilateral ulnar nerve, median nerve, tibial nerve, and common peroneal nerve, and the sensory conduction velocities of the ulnar nerve, median nerve, sural nerve, and superficial peroneal nerve. According to the results, the patients were divided into two groups: normal peripheral nerve conduction group (NCVN group) and abnormal peripheral nerve conduction group (NCVA group). The two groups were then compared in terms of the conventional biochemical index and the sugar metabolic index as well as the serum levels of TXNIP, reduced glutathione (GSH), total superoxide dismutase (SOD), malondialdehyde (MDA), and tumor necrosis factor alpha (TNF-α). The correlation between TXNIP and NCV was also analyzed.

Results: Compared with the NCVN group, the TXNIP and MDA values were significantly increased in the NCVA group (P < 0.05). Among the patients with T2DM, age, fasting glucose, SDBG, and TXNIP were risk factors for NCV abnormality, while vitamin D3 was a protective factor. After adjusting for related confounding factors, TXNIP was significantly correlated with NCV (P < 0.05). Among the patients with T2DM, TXNIP was an independent risk factor for left ulnar motor conduction velocity (MCV), right ulnar MCV, left median MCV, and right median MCV. TNF-α was identified as a positive influencing factor for serum TXNIP, while serum TXNIP was a positive factor for TNF-α and MDA (both P < 0.05).

Conclusion: Serum TXNIP is related to NCV in T2DM patients. In combination with oxidative stress and inflammation, TXNIP may affect diabetic peripheral neuropathy (DPN).

Thioredoxin-interacting protein regulates glucose metabolism and improves the intracellular redox state in bovine oocytes during in vitro maturation

The extent of glucose metabolism during oocyte maturation is closely related to oocyte developmental potential. Thioredoxin-interacting protein (TXNIP) is an α-arrestin family protein that negatively regulates glucose uptake into cells. However, little information is available regarding the function of TXNIP in bovine oocytes. Accordingly, the present study was performed to investigate the influence of TXNIP on glucose metabolism in bovine oocytes during in vitro maturation. Pharmacological inhibition of TXNIP by azaserine enhanced glucose uptake and imparted a specific metabolic effect on glycolysis and pentose phosphate pathway (PPP). RNA interference (RNAi) was adopted to further determine the biological significance of TXNIP in regulating glucose metabolism. The maturation rate and the developmental competence of TXNIP siRNA-treated oocytes were significantly improved. Knockdown of TXNIP in bovine oocytes significantly increased glycolysis by increasing the activities of phosphofructokinase (PFK), pyruvate kinase, and lactate dehydrogenase; pyruvate and lactate production; and intracellular ATP level, as well as mitochondrial activity. Furthermore, glucose metabolism through PPP was also enhanced by TXNIP depletion, as TXNIP siRNA treatment promoted glucose-6-phosphate dehydrogenase (G6PDH) activity and NADPH content, and helped maintain a high level of glutathione and a low level of reactive oxygen species within the oocytes. Further studies revealed that inhibition of TXNIP resulted increases in glucose transporter 1 (GLUT1) expression, as well as PFK1 platelet isoform (PFKP) and G6PDH mRNA levels. These results reveal that TXNIP depletion promotes oocyte maturation by enhancing both glycolysis and the PPP. During in vitro maturation of bovine oocytes, TXNIP serves as a key regulator of glucose uptake by controlling GLUT1 expression.

Thioredoxin-Interacting Protein as a Novel Potential Therapeutic Target in Diabetes Mellitus and Its Underlying Complications

Diabetes mellitus (DM) is a common metabolic disorder which is characterized by a persistent increment of blood glucose. Globally, DM affects millions of people and the prevalence is increasing alarmingly. The critical step in the pathophysiology of DM is the loss of β-cells of the pancreas, which are responsible for the secretion of insulin. Thioredoxin-interacting protein (TXNIP) is among the factors that control the production and loss of the pancreatic β-cells. TXNIP is an α-arrestin that can bind and inhibit thioredoxin (the antioxidant protein) which is produced in the pancreatic islet after glucose intake. Numerous studies illustrated that elevated TXNIP levels were found to induce β-cell apoptosis; whereas TXNIP deficiency protects against type I and type II diabetes by promoting β-cell survival. Nowadays, TXNIP depletion is becoming a key factor in pancreatic β-cell survival enhancement. In the present review, targeting TXNIP is found to be relevant as a unique therapeutic opportunity, not only to improve insulin secretion and sensitivity, but also ameliorating the long term microvascular and macrovascular complications of the disease. Thus, TXNIP inhibitors that could reduce the expression and/or activity of TXNIP to non-diabetic levels are promising agents to halt the alarming rate of diabetes and its related complications.

Autophagy and Age-Related Eye Diseases

Background

Autophagy is a catabolic process that depends on the lysosome. It is usually used to maintain cellular homeostasis, survival and development by degrading abnormal substances and dysfunctional organelles, especially when the cell is exposed to starvation or other stresses. Increasing studies have reported that autophagy is associated with various eye diseases, of which aging is one of the important factors.

Objective

To summarize the functional and regulatory role of autophagy in ocular diseases with aging, and discuss the possibility of autophagy-targeted therapy in age-related diseases.

Methods

PubMed searches were performed to identify relevant articles published mostly in the last 5 years. The key words were used to retrieve including “autophagy”, “aging”, “oxidative stress AND autophagy”, “dry eye AND autophagy”, “corneal disease AND autophagy”, “glaucoma AND autophagy”, “cataract AND autophagy”, “AMD AND autophagy”, “cardiovascular diseases AND autophagy”, “diabetes AND autophagy”. After being classified and assessed, the most relevant full texts in English were chosen.

Results

Apart from review articles, more than two research articles for each age-related eye diseases related to autophagy were retrieved. We only included the most relevant and recent studies for summary and discussion.

Conclusion

Autophagy has both protective and detrimental effects on the progress of age-related eye diseases. Different types of studies based on certain situations in vitro showed distinct results, which do not necessarily coincide with the actual situation in human bodies completely. It means the exact role and regulatory function of autophagy in ocular diseases remains largely unknown. Although autophagy as a potential therapeutic target has been proposed, many problems still need to be solved before it applies to clinical practice.