Thioredoxin-interacting protein is essential for memory T cell formation via the regulation of the redox metabolism.

CD4+ memory T cells are central to long-lasting protective immunity and are involved in shaping the pathophysiology of chronic inflammation. While metabolic reprogramming is critical for the generation of memory T cells, the mechanisms controlling the redox metabolism in memory T cell formation remain unclear. We found that reactive oxygen species (ROS) metabolism changed dramatically in T helper-2 (Th2) cells during the contraction phase in the process of memory T cell formation. Thioredoxin-interacting protein (Txnip), a regulator of oxidoreductase, regulated apoptosis by scavenging ROS via the nuclear factor erythroid 2-related factor 2 (Nrf2)-biliverdin reductase B (Blvrb) pathway. Txnip regulated the pathology of chronic airway inflammation in the lung by controlling the generation of allergen-specific pathogenic memory Th2 cells in vivo. Thus, the Txnip-Nrf2-Blvrb axis directs ROS metabolic reprogramming in Th2 cells and is a potential therapeutic target for intractable chronic inflammatory diseases.

Txnip regulates the Oct4-mediated pluripotency circuitry via metabolic changes upon differentiation.

Thioredoxin interacting protein (Txnip) is a stress-responsive factor regulating Trx1 for redox balance and involved in diverse cellular processes including proliferation, differentiation, apoptosis, inflammation, and metabolism. However, the biological role of Txnip function in stem cell pluripotency has yet to be investigated. Here, we reveal the novel functions of mouse Txnip in cellular reprogramming and differentiation onset by involving in glucose-mediated histone acetylation and the regulation of Oct4, which is a fundamental component of the molecular circuitry underlying pluripotency. During reprogramming or PSC differentiation process, cellular metabolic and chromatin remodeling occur in order to change its cellular fate. Txnip knockout promotes induced pluripotency but hinders initial differentiation by activating pluripotency factors and promoting glycolysis. This alteration affects the intracellular levels of acetyl-coA, a final product of enhanced glycolysis, resulting in sustained histone acetylation on active PSC gene regions. Moreover, Txnip directly interacts with Oct4, thereby repressing its activity and consequently deregulating Oct4 target gene transcriptions. Our work suggests that control of Txnip expression is crucial for cell fate transitions by modulating the entry and exit of pluripotency.

Association between DNA methylation levels of thioredoxin-interacting protein (TXNIP) and changes in glycemic traits: a longitudinal population-based study.

Thioredoxin-interacting protein (TXNIP) plays an important role in glucose metabolism, and its expression is regulated by DNA methylation (DNAm). Although the association between TXNIP DNAm and type 2 diabetes mellitus has been demonstrated in studies with a cross-sectional design, prospective studies are needed. We therefore examined the association between TXNIP DNAm levels and longitudinal changes in glycemic traits by conducting a longitudinal study involving 169 subjects who underwent two health checkups in 2015 and 2019. We used a pyrosequencing assay to determine TXNIP DNAm levels in leukocytes (cg19693031). Logistic regression analyses were performed to assess the associations between dichotomized TXNIP DNAm levels and marked increases in glycemic traits. At four years, the TXNIP DNA hypomethylation group had a higher percentage of changes in fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) compared to those in the hypermethylation group. The adjusted odds ratios for FPG and HbA1c levels were significantly higher in the TXNIP DNA hypomethylation group than in the hypermethylation group. We found that TXNIP DNA hypomethylation at baseline was associated with a marked increase in glycemic traits. Leukocyte TXNIP DNAm status could potentially be used as an early biomarker for impaired glucose homeostasis.

ATGL activity regulates GLUT1-mediated glucose uptake and lactate production via TXNIP stability in adipocytes.

Traditionally, lipolysis has been regarded as an enzymatic activity that liberates fatty acids as metabolic fuel. However, recent work has shown that novel substrates, including a variety of lipid compounds such as fatty acids and their derivatives, release lipolysis products that act as signaling molecules and transcriptional modulators. While these studies have expanded the role of lipolysis, the mechanisms underpinning lipolysis signaling are not fully defined. Here, we uncover a new mechanism regulating glucose uptake, whereby activation of lipolysis, in response to elevated cAMP, leads to the stimulation of thioredoxin-interacting protein (TXNIP) degradation. This, in turn, selectively induces glucose transporter 1 surface localization and glucose uptake in 3T3-L1 adipocytes and increases lactate production. Interestingly, cAMP-induced glucose uptake via degradation of TXNIP is largely dependent upon adipose triglyceride lipase (ATGL) and not hormone-sensitive lipase or monoacylglycerol lipase. Pharmacological inhibition or knockdown of ATGL alone prevents cAMP-dependent TXNIP degradation and thus significantly decreases glucose uptake and lactate secretion. Conversely, overexpression of ATGL amplifies the cAMP response, yielding increased glucose uptake and lactate production. Similarly, knockdown of TXNIP elicits enhanced basal glucose uptake and lactate secretion, and increased cAMP further amplifies this phenotype. Overexpression of TXNIP reduces basal and cAMP-stimulated glucose uptake and lactate secretion. As a proof of concept, we replicated these findings in human primary adipocytes and observed TXNIP degradation and increased glucose uptake and lactate secretion upon elevated cAMP signaling. Taken together, our results suggest a crosstalk between ATGL-mediated lipolysis and glucose uptake.

The thioredoxin-1 inhibitor Txnip restrains effector T-cell and germinal center B-cell expansion.

Thioredoxin-1 (Trx1) is a vital component for cellular redox homeostasis. In T cells, Trx1 donates electrons for the de novo synthesis of deoxyribonucleotides to allow rapid cell proliferation. The Trx-interacting protein (Txnip) binds to the reduced Trx1 and inhibits its activity. However, the role of Txnip in adaptive immunity in vivo is unknown. Here, we show that absence of Txnip increased proliferation of effector T cells and GC B-cell responses in response to lymphocytic choriomeningitis virus and Qß virus-like particles, respectively, but did not affect development and homeostasis of T and B cells. While downregulation of Txnip and concomitant upregulation of Trx1 is critical for rapid T-cell expansion upon viral infection, re-expression of Txnip and consequently inhibition of Trx1 is important to restrain late T-cell expansion. Importantly, we demonstrated that T-cell receptor (TCR) engagement but not CD28 costimulation is critically required for Txnip downregulation. Thus, this study further uncovers positive and negative control of lymphocyte proliferation by the Trx1 system.

DNA methylation level of the gene encoding thioredoxin-interacting protein in peripheral blood cells is associated with metabolic syndrome in the Japanese general population.

Metabolic syndrome (MetS) is cluster of metabolic diseases, including abdominal obesity, hyperglycemia, high blood pressure, and dyslipidemia, that directly escalate the risk of type 2 diabetes, heart disease, and stroke. Thioredoxin-interacting protein (TXNIP) is a binding protein for thioredoxin, a molecule that is a key inhibitor of cellular oxidation, and thus regulates the cellular redox state. Epigenetic alteration of the TXNIP-encoding locus has been associated with components of MetS. In the present study, we sought to determine whether the level of TXNIP methylation in blood is associated with MetS in the general Japanese population. DNA was extracted from the peripheral blood cells of 37 subjects with and 392 subjects without MetS. The level of TXNIP methylation at cg19693031 was assessed by the bisulfite-pyrosequencing method. We observed that TXNIP methylation levels were lower in MetS subjects (median 74.9%, range 71.7-78.4%) than in non-MetS subjects (median 77.7%, range 74.4-80.5%; p = 0.0024). Calculation of the confounding factor-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for hypomethylation revealed that subjects with MetS exhibited significantly higher ORs for hypomethylation than did those without MetS (OR, 2.92; 95% CI, 1.33-6.62; p = 0.009). Our findings indicated that lower levels of TXNIP methylation are associated with MetS in the general Japanese population. Altered levels of DNA methylation in TXNIP at cg19693031 might play an important role in the pathogenesis of MetS.

The physiological and pathophysiological roles of carbohydrate response element binding protein in the kidney.

Glucose is not only the energy fuel for most cells, but also the signaling molecule which affects gene expression via carbohydrate response element binding protein (ChREBP), a Mondo family transcription factor. In response to high glucose conditions, ChREBP regulates glycolytic and lipogenic genes by binding to carbohydrate response elements (ChoRE) in the regulatory region of its target genes, thus elucidating the role of ChREBP for converting excessively ingested carbohydrates to fatty acids as an energy storage in lipogenic tissues such as the liver and adipose tissue. While the pathophysiological roles of ChREBP for fatty liver and obesity in these tissues are well known, much of the physiological and pathophysiological roles of ChREBP in other tissues such as the kidney remains unclear despite its high levels of expression in them. This review will thus highlight the roles of ChREBP in the kidney and briefly introduce the latest research results that have been reported so far.

Geniposide improves insulin resistance through AMPK-mediated Txnip protein degradation in 3T3-L1 adipocytes.

Thioredoxin-interacting protein (Txnip) has emerged as a key regulator of insulin resistance. In this study, we investigated the roles of geniposide and Txnip in insulin resistance in differentiated 3T3-L1 adipocytes. Our results revealed that geniposide markedly enhanced glucose uptake, increased the protein levels of insulin receptor substrate (IRS)-1 and GLUT-1, and prevented the phosphorylation of IRS-1 and Akt Thr308 induced by insulin resistance in 3T3-L1 adipocytes. We also observed that geniposide accelerated protein degradation of Txnip through proteasome pathway, and knockdown of Txnip with small interfering RNA attenuated the effect of geniposide on insulin signaling molecules, implying that Txnip played a pivotal role in the regulation of insulin signaling molecules by geniposide in 3T3-L1 adipocytes. Furthermore, geniposide induced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) in the presence of high glucose in differentiated 3T3-L1 adipocytes, while compound C, an inhibitor of AMPK, prevented the effect of geniposide on Txnip degradation and the regulation of glucose uptake and insulin signaling molecules including p-IRS-1, IRS-1, and GLUT-1 in differentiated 3T3-L1 adipocytes. Taken together, all these findings suggest that geniposide improves the insulin signaling defect possibly by AMPK-mediated Txnip degradation in 3T3-L1 adipocytes.

A prodrug of epigallocatechin-3-gallate alleviates high glucose-induced pro-angiogenic factor production by inhibiting the ROS/TXNIP/NLRP3 inflammasome axis in retinal Müller cells.

Diabetic retinopathy (DR) is a neurovascular complication of diabetes mellitus that leads to blindness in the working-age population. Retinal Müller cells proliferate and produce pro-angiogenic factors, including vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF), via the reactive oxygen species (ROS)/thioredoxin interacting protein (TXNIP)/NACHT, LRR and PYD domain-containing protein 3 (NLRP3) inflammasome axis to promote proliferative DR. Epigallocatechin-3-gallate (EGCG) plays anti-oxidant, anti-inflammatory, anti-proliferative and anti-angiogenic roles in Müller cells. A prodrug of EGCG (pro-EGCG) enhances the bioavailability of EGCG. In an in vitro model of high glucose-stimulated Müller cells, pro-EGCG inhibited proliferation and pro-angiogenic factor production by down-regulating the activity of the ROS/TXNIP/NLRP3 inflammasome axis. In a mouse DR model, pro-EGCG reduced ROS accumulation, NLRP3 inflammasome activation, Müller cell proliferation, and production of the pro-angiogenic factors VEGF and HGF. In summary, pro-EGCG mitigated hyperglycaemia-challenged Müller cell proliferation and pro-angiogenic factor production by inhibiting ROS/TXNIP/NLRP3 inflammasome signalling, implying a potential therapeutic strategy for DR.

Geniposide inhibits glucolipotoxicity and cooperates with Txnip knockdown to potentiate cell adaption to endoplasmic reticulum stress in pancreatic beta cells.

Thioredoxin-interacting protein (Txnip), a negative regulator of thioredoxin, has become an attractive therapeutic target to alleviate metabolic diseases. Our previous data demonstrated that geniposide improved glucose-stimulated insulin secretion by accelerating Txnip degradation and prevented the early-stage apoptosis of pancreatic ß cells induced by palmitate, but the underlying mechanisms are still unclear. The objective of this study is to identify the role of Txnip in geniposide preventing the apoptosis of pancreatic ß cells induced by high glucose and palmitate (HG/PA). The results revealed that geniposide attenuated HG/PA-induced cell apoptosis and the expression of Bax and caspase-3, while increasing mitochondrial membrane potential and the anti-apoptotic protein levels of heme-oxygenase-1 (HO-1) and Bcl-2 in INS-1 rat pancreatic ß cells. Knockdown of the Txnip gene raised the levels of anti-apoptotic proteins HO-1 and Bcl-2 and geniposide potentiated the effect of Txnip when the INS-1 cells were challenged by HG/PA. Furthermore, geniposide enhanced the adoptive unfolded protein response by increasing the phosphorylation of PERK/eIF2α and IRE1α in HG/PA-treated INS-1 cells. The results together suggest that geniposide might be useful to antagonize glucolipotoxicity and Txnip might be a pleiotropic cellular factor in pancreatic ß cells.

Unfolded protein response is involved in geniposide-regulating glucose-stimulated insulin secretion in INS-1 cells.

The growing evidence shows that in the early stage of type 2 diabetes mellitus (T2DM) development, when challenged by hyperglycemia and/or insulin resistance, pancreatic islets would produce more insulin to maintain the balance of blood sugar, but at the same time, endoplasmic reticulum (ER) stress will be initiated for the reason of over-compensation, which might be a crucial caused factor of dysfunction and death of pancreatic beta cell. In this study, we showed that high glucose induced a remarkably unfolded protein response (UPR) with the phosphorylation of PERK/eIF2α and IRE1α in INS-1 cells, but geniposide prevented the role of high glucose on the phosphorylation of PERK/eIF2α and IRE1α, respectively. Although inhibition of Txnip expression by siRNA had no significant effect on geniposide-regulating UPR, PERK and IRE1α were associated with geniposide-regulating Txnip degradation and glucose-stimulated insulin secretion (GSIS) in high glucose-cultured INS-1 cells. All these data suggest that geniposide might be an important regulator of ER stress and GSIS, and a promising compound for the treatment of T2DM. SIGNIFICANCE OF THE STUDY: Mounting evidence indicates that endoplasmic reticulum (ER) stress plays an essential role to maintain the normal cellular functions and dysfunction. In this study, we revealed that geniposide might be an important regulator of ER stress and glucose-stimulated insulin secretion in pancreatic beta cells.

All-trans retinoic acid ameliorates hepatic stellate cell activation via suppression of thioredoxin interacting protein expression.

Activation of hepatic stellate cells (HSCs) is the effector factor of hepatic fibrosis and hepatocellular carcinoma (HCC) development. Accumulating evidence suggests that retinoic acids (RAs), derivatives of vitamin A, contribute to prevention of liver fibrosis and carcinogenesis, however, regulatory mechanisms of RAs still remain exclusive. To elucidate RA signaling pathway, we previously performed a genome-wide screening of RA-responsive genes by in silico analysis of RA-response elements, and identified 26 RA-responsive genes. We found that thioredoxin interacting protein (TXNIP), which inhibits antioxidant activity of thioredoxin (TRX), was downregulated by all-trans retinoic acid (ATRA). In the present study, we demonstrate that ATRA ameliorates activation of HSCs through TXNIP suppression. HSC activation was attenuated by TXNIP downregulation, whereas potentiated by TXNIP upregulation, indicating that TXNIP plays a crucial role in activation of HSCs. Notably, we showed that TXNIP-mediated HSC activation was suppressed by antioxidant N-acetylcysteine. In addition, ATRA treatment or downregulation of TXNIP clearly declined oxidative stress levels in activated HSCs. These data suggest that ATRA plays a key role in inhibition of HSC activation via suppressing TXNIP expression, which reduces oxidative stress levels.

IRE1α inhibition decreased TXNIP/NLRP3 inflammasome activation through miR-17-5p after neonatal hypoxic-ischemic brain injury in rats.

BACKGROUND: The endoplasmic reticulum (ER) is responsible for the control of correct protein folding and protein function which is crucial for cell survival. However, under pathological conditions, such as hypoxia-ischemia (HI), there is an accumulation of unfolded proteins thereby triggering the unfolded protein response (UPR) and causing ER stress which is associated with activation of several stress sensor signaling pathways, one of them being the inositol requiring enzyme-1 alpha (IRE1α) signaling pathway. The UPR is regarded as a potential contributor to neuronal cell death and inflammation after HI. In the present study, we sought to investigate whether microRNA-17 (miR-17), a potential IRE1α ribonuclease (RNase) substrate, arbitrates downregulation of thioredoxin-interacting protein (TXNIP) and consequent NLRP3 inflammasome activation in the immature brain after HI injury and whether inhibition of IRE1α may attenuate inflammation via miR-17/TXNIP regulation. METHODS: Postnatal day 10 rat pups (n = 287) were subjected to unilateral carotid artery ligation followed by 2.5 h of hypoxia (8% O2). STF-083010, an IRE1α RNase inhibitor, was intranasally delivered at 1 h post-HI or followed by an additional one administration per day for 2 days. MiR-17-5p mimic or anti-miR-17-5p inhibitor was injected intracerebroventricularly at 48 h before HI. Infarct volume and body weight were used to evaluate the short-term effects while brain weight, gross and microscopic brain tissue morphologies, and neurobehavioral tests were conducted for the long-term evaluation. Western blots, immunofluorescence staining, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), and co-immunoprecipitation (Co-IP) were used for mechanism studies. RESULTS: Endogenous phosphorylated IRE1α expression was significantly increased after HI. Intranasal administration of STF-083010 alleviated brain injury and improved neurological behavior. MiR-17-5p expression was reduced after HI, and this decrease was attenuated by STF-083010 treatment. MiR-17-5p mimic administration ameliorated TXNIP expression, NLRP3 inflammasome activation, caspase-1 cleavage, and IL-1ß production, as well as brain infarct volume. Conversely, anti-miR-17-5p inhibitor reversed IRE1α inhibition-induced decrease in TXNIP expression and inflammasome activation, as well as exacerbated brain injury after HI. CONCLUSIONS: IRE1a-induced UPR pathway may contribute to inflammatory activation and brain injury following neonatal HI. IRE1a activation, through decay of miR-17-5p, elevated TXNIP expression to activate NLRP3 inflammasome and aggravated brain damage.

Geniposide accelerates proteasome degradation of Txnip to inhibit insulin secretion in pancreatic ß-cells.

PURPOSE: To analyze the role of geniposide in the protein degradation of Txnip and to determine the impact of Txnip on geniposide-regulated GSIS in pancreatic INS-1 cells. METHODS: The content of Txnip protein was measured by western blot; insulin content and glucose uptake were determined by ELISA; and knockdown of Txnip was the method of RNA interference. RESULTS: Glucose induces a rapid increase in Txnip protein, and geniposide accelerates the degradation of Txnip via proteasome pathway in the presence of high glucose (25 mM) in INS-1 pancreatic ß-cells. And MG132, a proteasomal inhibitor, potentiates glucose uptake, metabolism (ATP production) and glucose-stimulated insulin secretion (GSIS) in high-glucose (25 mM)-treated INS-1 cells, but geniposide significantly prevents these effects. Furthermore, the combination of geniposide and Txnip knockdown shows substantial synergistic effects to reduce glucose uptake, metabolism and GSIS in high-glucose (25 mM)-treated INS-1 cells. CONCLUSIONS: Txnip protein played an essential role in glucose uptake, metabolism and GSIS, and geniposide could accelerate the degradation via proteasome pathway in high-glucose-treated pancreatic INS-1 cells.

Differential expression of thioredoxin binding protein-2/Txnip in human placenta: Possible involvement of hypoxia in its suppression during early pregnancy.

AIM: Thioredoxin binding protein-2 (TBP-2), which is identical to thioredoxin interacting protein (Txnip), controls cellular proliferation and differentiation. The aim of the present study was to compare TBP-2 protein and mRNA expression in human placenta during the three trimesters of pregnancy and to investigate the role of hypoxia in the change of these expressions in placental tissue. A secondary objective was to determine the gene expression of peroxisome proliferator-activated receptors (PPARs) in TBP-2 deficient placenta using TBP-2 gene disrupted mice (TBP-2-/- ). METHODS: Protein and mRNA expression of TBP-2 in human placenta from each trimester were analyzed by immunohistochemistry, Western blots, and by quantitative reverse-transcriptase-polymerase chain reaction. The effect of hypoxia on TBP-2 expression was tested using an explant culture of human placenta. In TBP-2-/- mouse placenta, we detected PPAR mRNA expression. RESULTS: TBP-2 was located in syncytiotrophoblasts and cytotrophoblasts, and also in the endothelium in human placenta. Its expression in the placenta was low in the first trimester, and increased in the second and third trimesters. Hypoxia decreased TBP-2 mRNA and protein expression in human placental explant culture. In TBP-2-/- mice, placental mRNA levels of PPARα and γ were significantly suppressed compared with those in wild-type mice. CONCLUSION: Hypoxia suppresses TBP-2 gene expression, which may ultimately alter placental development.

Epigenetic regulation of the thioredoxin-interacting protein (TXNIP) gene by hyperglycemia in kidney.

Diabetic kidney disease is the leading cause of end-stage renal disease. Genetic factors have been suggested to contribute to its susceptibility. However, results from genetic studies are disappointing possibly because the role of glucose in diabetic kidney disease predisposed by epigenetic mechanisms has not been taken into account. Since thioredoxin-interacting protein (TXNIP) has been shown to play an important role in the pathogenesis of diabetic kidney disease, we tested whether glucose could induce expression of TXNIP in the kidney by epigenetic mechanisms. In kidneys from diabetic Sur1-E1506K(+/+) mice, hyperglycemia-induced Txnip expression was associated with stimulation of activating histone marks H3K9ac, H3K4me3, and H3K4me1, as well as decrease in the repressive histone mark H3K27me3 at the promoter region of the gene. Glucose also coordinated changes in histone marks and TXNIP gene expression in mouse SV40 MES13 mesangial cells and the normal human mesangial cell line NHMC. The involvement of histone acetylation in glucose-stimulated TXNIP expression was confirmed by reversing or enhancing acetylation using the histone acetyltransferase p300 inhibitor C646 or the histone deacetylase inhibitor trichostatin A. Thus, glucose is a potent inducer of histone modifications, which could drive expression of proinflammatory genes and thereby predispose to diabetic kidney disease.

D-mannose alleviates intervertebral disc degeneration through glutamine metabolism.

BACKGROUND: Intervertebral disc degeneration (IVDD) is a multifaceted condition characterized by heterogeneity, wherein the balance between catabolism and anabolism in the extracellular matrix of nucleus pulposus (NP) cells plays a central role. Presently, the available treatments primarily focus on relieving symptoms associated with IVDD without offering an effective cure targeting its underlying pathophysiological processes. D-mannose (referred to as mannose) has demonstrated anti-catabolic properties in various diseases. Nevertheless, its therapeutic potential in IVDD has yet to be explored. METHODS: The study began with optimizing the mannose concentration for restoring NP cells. Transcriptomic analyses were employed to identify the mediators influenced by mannose, with the thioredoxin-interacting protein (Txnip) gene showing the most significant differences. Subsequently, small interfering RNA (siRNA) technology was used to demonstrate that Txnip is the key gene through which mannose exerts its effects. Techniques such as colocalization analysis, molecular docking, and overexpression assays further confirmed the direct regulatory relationship between mannose and TXNIP. To elucidate the mechanism of action of mannose, metabolomics techniques were employed to pinpoint glutamine as a core metabolite affected by mannose. Next, various methods, including integrated omics data and the Gene Expression Omnibus (GEO) database, were used to validate the one-way pathway through which TXNIP regulates glutamine. Finally, the therapeutic effect of mannose on IVDD was validated, elucidating the mechanistic role of TXNIP in glutamine metabolism in both intradiscal and orally treated rats. RESULTS: In both in vivo and in vitro experiments, it was discovered that mannose has potent efficacy in alleviating IVDD by inhibiting catabolism. From a mechanistic standpoint, it was shown that mannose exerts its anti-catabolic effects by directly targeting the transcription factor max-like protein X-interacting protein (MondoA), resulting in the upregulation of TXNIP. This upregulation, in turn, inhibits glutamine metabolism, ultimately accomplishing its anti-catabolic effects by suppressing the mitogen-activated protein kinase (MAPK) pathway. More importantly, in vivo experiments have further demonstrated that compared with intradiscal injections, oral administration of mannose at safe concentrations can achieve effective therapeutic outcomes. CONCLUSIONS: In summary, through integrated multiomics analysis, including both in vivo and in vitro experiments, this study demonstrated that mannose primarily exerts its anti-catabolic effects on IVDD through the TXNIP-glutamine axis. These findings provide strong evidence supporting the potential of the use of mannose in clinical applications for alleviating IVDD. Compared to existing clinically invasive or pain-relieving therapies for IVDD, the oral administration of mannose has characteristics that are more advantageous for clinical IVDD treatment.

Empagliflozin reduces endoplasmic reticulum stress associated TXNIP/NLRP3 activation in tunicamycin-stimulated aortic endothelial cells.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have proven to be of therapeutic significance for cardiovascular diseases beyond the treatment of type 2 diabetes. Recent studies have demonstrated the beneficial effects of SGLT2i on endothelial cell (EC) dysfunction, but the underlying cellular mechanisms remain to be clarified. In this study, we sought to understand the effect of empagliflozin (EMPA; Jardiance®) on cell homeostasis and endoplasmic reticulum (ER) stress signaling. ER stress was induced by tunicamycin (Tm) in human abdominal aortic ECs treated with EMPA over 24 h. Tm-induced ER stress caused increases in the protein expression of thioredoxin interacting protein (TXNIP), NLR-family pyrin domain-containing protein 3 (NLRP3), C/EBP homologous protein (CHOP), and in the ratio of phospho-eIF2α/eIF2α. EMPA (50-100 µM) resulted in a dampened downstream activation of ER stress as seen by the reduced expression of CHOP and TXNIP/NLRP3 in a dose-dependent manner. Nuclear factor erythroid 2-related factor 2 (nrf2) translocation was also attenuated in EMPA-treated ECs. These results suggest that EMPA improves redox signaling under ER stress which in turn attenuates the activation of TXNIP/NLRP3.

Dynamic gene expression for metabolic engineering of mammalian cells in culture.

Recombinant mammalian cells are the major hosts for the production of protein therapeutics. In addition to high expression of the product gene, a hyper-producer must also harbor superior phenotypic traits related to metabolism, protein secretion, and growth control. Introduction of genes endowing the relevant hyper-productivity traits is a strategy frequently used to enhance the productivity. Most of such cell engineering efforts have been performed using constitutive expression systems. However, cells respond to various environmental cues and cellular events dynamically according to cellular needs. The use of inducible systems allows for time dependent expression, but requires external manipulation. Ideally, a transgene's expression should be synchronous to the host cell's own rhythm, and at levels appropriate for the objective. To that end, we identified genes with different expression dynamics and intensity ranges using pooled transcriptome data. Their promoters may be used to drive the expression of the transgenes following the desired dynamics. We isolated the promoter of the Thioredoxin-interacting protein (Txnip) gene and demonstrated its capability to drive transgene expression in concert with cell growth. We further employed this Chinese hamster promoter to engineer dynamic expression of the mouse GLUT5 fructose transporter in Chinese hamster ovary (CHO) cells, enabling them to utilize sugar according to cellular needs rather than in excess as typically seen in culture. Thus, less lactate was produced, resulting in a better growth rate, prolonged culture duration, and higher product titer. This approach illustrates a novel concept in metabolic engineering which can potentially be used to achieve dynamic control of cellular behaviors for enhanced process characteristics.

Atmospheric PM2.5 induce autophagy and autophagic flux blockage in HUVEC cells via ROS/TXNIP signaling: Important role of metal components.

Autophagy was involved in vascular endothelial injury caused by PM2.5, which aggravated the pathogenesis of cardiovascular diseases. However, major toxic components and underlying mechanism responsible for PM2.5-induced autophagy remain unclear. In this study, the effects of water-extracted PM2.5 (WE-PM2.5) on autophagy in human umbilical vein endothelial cells (HUVEC) were studied. Our results showed WE-PM2.5 promoted autophagosome initiation and formation, meanwhile, lysosomal function was impaired, which further caused autophagic flux blockage in HUVEC cells. Furthermore, removal of metals alleviated WE-PM2.5-induced autophagic flux blockage, while the artificial metal mixture reproduced the WE-PM2.5 response. Mechanistically, ROS regulated autophagy-related proteins evidenced by BECN1, LC3B and p62 expression reversed by NAC pretreatment in WE-PM2.5-exposed cells. WE-PM2.5 also increased TXNIP expression mediated by ROS; moreover, knockdown of TXNIP in WE-PM2.5-exposed cells decreased BECN1 and LC3B expression, but had little effects on the expression of p62, CTSB, and CTSD, indicating WE-PM2.5-induced TXNIP was involved in autophagosome initiation and formation rather than autophagic degradation. Collectively, WE-PM2.5-induced ROS not only promoted autophagosome initiation and formation, but also inhibited autophagic degradation. However, as the downstream molecule of ROS, TXNIP was only involved in autophagosome initiation and formation. Importantly, WE-PM2.5-bound metals were largely responsible for autophagic flux blockage in HUVEC cells.