W2476 ameliorates β-cell dysfunction and exerts therapeutic effects in mouse models of diabetes via modulation of the thioredoxin-interacting protein signaling pathway

Fluorinated curcumin derivative (Shiga-Y6) modulates the level of thioredoxin-interacting protein (TXNIP) in a mouse model of diabetes

Thioredoxin interacting protein (TXNIP) has emerged as a significant regulator of β-cell mass and loss, rendering it an attractive target for treating diabetes. We previously showed that Shiga-Y6, a fluorinated curcumin derivative, inhibited TXNIP mRNA and protein expression in vitro, raising the question of whether the same effect could be translated in vivo. Herein, we examined the effect of Shiga-Y6 on TNXIP levels and explored its therapeutic potential in a mouse model of diabetes, Akita mice. We intraperitoneally injected Shiga-Y6 (SY6; 30 mg/kg of body weight) or vehicle into 8-week-old Akita mice for 28 consecutive days. On day 29, the mice were euthanized, following which the serum levels of glucose, insulin, and glucagon were measured using ELISA, the expression of TXNIP in pancreatic tissue lysates was determined using western blotting, and the level of β-cell apoptosis was assessed using the TUNEL assay. TXNIP levels in the pancreatic tissue of Akita mice were significantly elevated compared with wild-type (WT) mice. Shiga-Y6 administration for 28 days significantly lowered those levels compared with Akita mice that received vehicle to a level comparable to WT mice. In immunohistochemical analysis, both α- to β-cell ratio and the number of apoptotic β-cells were significantly reduced in SY6-treated Akita mice, compared with vehicle-treated Akita mice. Findings from the present study suggest a potential of Shiga-Y6 as an antidiabetic agent through lowering TXNIP protein levels and ameliorating pancreatic β-cells apoptosis.

A high throughput screen for pharmacological inhibitors of the carbohydrate response element

A central regulator of metabolism, transcription factor carbohydrate response element binding protein (ChREBP) senses and responds to dietary glucose levels by stimulating the transcription of glycolytic and lipogenic enzymes. Genetic depletion of ChREBP rescues β-cell dysfunction arising from high glucose levels, suggesting that inhibiting ChREBP might represent an attractive therapeutic approach to manage diabetes and other metabolic diseases. However, the molecular mechanisms governing ChREBP activation are poorly understood and chemical tools to probe the cellular activity of ChREBP are lacking. Here, we report a high-throughput pharmacological screen in INS-1E β-cells that identified novel inhibitors of ChREBP-driven transcription at carbohydrate response element sites, including three putative covalent inhibitors and two likely non-covalent chemical scaffolds. This work affords a pharmacological toolkit to help uncover the signaling logic controlling ChREBP activation and may ultimately reveal potential therapeutic approaches for treating metabolic disease.

TXNIP: A key protein in the cellular stress response pathway and a potential therapeutic target

Thioredoxin-interacting protein (TXNIP), which is also known as thioredoxin-binding protein 2 (TBP2), directly interacts with the major antioxidant protein thioredoxin (TRX) and inhibits its antioxidant function and expression. However, recent studies have demonstrated that TXNIP is a multifunctional protein with functions beyond increasing intracellular oxidative stress. TXNIP activates endoplasmic reticulum (ER) stress-mediated nucleotide-binding oligomerization domain (NOD)-like receptor protein-3 (NLRP3) inflammasome complex formation, triggers mitochondrial stress-induced apoptosis, and stimulates inflammatory cell death (pyroptosis). These newly discovered functions of TXNIP highlight its role in disease development, especially in response to several cellular stress factors. In this review, we provide an overview of the multiple functions of TXNIP in pathological conditions and summarize its involvement in various diseases, such as diabetes, chronic kidney disease, and neurodegenerative diseases. We also discuss the potential of TXNIP as a therapeutic target and TXNIP inhibitors as novel therapeutic drugs for treating these diseases.

Physiological and Pathophysiological Roles of Thioredoxin Interacting Protein: A Perspective on Redox Inflammation and Metabolism

Significance: Thioredoxin interacting protein (TXNIP) is a member of the arrestin fold superfamily with important cellular functions, including cellular transport, mitochondrial energy generation, and protein cycling. It is the only arrestin-domain protein known to covalently bind to thioredoxin and plays roles in glucose metabolism, inflammation, apoptosis, and cancer. Recent Advances: The crystal structure of the TXNIP-thioredoxin complex provided details about this fascinating interaction. Recent studies showed that TXNIP is induced by endoplasmic reticulum (ER) stress, activates NLR family pyrin domain containing 3 (NLRP3) inflammasomes, and can regulate glucose transport into cells. The tumor suppressor role of TXNIP in various cancer types and the role of TXNIP in fructose absorption are now described. Critical Issues: The influence of TXNIP on redox state is more complex than its interaction with thioredoxin. Future Directions: It is incompletely understood which functions of TXNIP are thioredoxin-dependent. It is also unclear whether TXNIP binding can inhibit glucose transporters without endocytosis. TXNIP-regulated control of ER stress should also be investigated further. Antioxid. Redox Signal. 38, 442-460.

Thioredoxin-Interacting Protein in Cancer and Diabetes

Significance: Thioredoxin-interacting protein (Txnip) is an α-arrestin protein that acts as a cancer suppressor. Txnip is simultaneously a critical regulator of energy metabolism. Other alpha-arrestin proteins also play key roles in cell biology and cancer. Recent Advances: Txnip expression is regulated by multilayered mechanisms, including transcriptional regulation, microRNA, messenger RNA (mRNA) stabilization, and protein degradation. The Txnip-based connection between cancer and metabolism has been widely recognized. Meanwhile, new aspects are proposed for the mechanism of action of Txnip, including the regulation of RNA expression and autophagy. Arrestin domain containing 3 (ARRDC3), another α-arrestin protein, regulates endocytosis and signaling, whereas ARRDC1 and ARRDC4 regulate extracellular vesicle formation. Critical Issues: The mechanism of action of Txnip is yet to be elucidated. The regulation of intracellular protein trafficking by arrestin family proteins has opened an emerging field of biology and medical research, which needs to be examined further. Future Directions: A fundamental understanding of the mechanism of action of Txnip and other arrestin family members needs to be explored in the future to combat diseases such as cancer and diabetes. Antioxid. Redox Signal. 36, 1001-1022.

Thioredoxin interacting protein, a key molecular switch between oxidative stress and sterile inflammation in cellular response

Tissue and systemic inflammation have been the main culprit behind the cellular response to multiple insults and maintaining homeostasis. Obesity is an independent disease state that has been reported as a common risk factor for multiple metabolic and microvascular diseases including nonalcoholic fatty liver disease (NAFLD), retinopathy, critical limb ischemia, and impaired angiogenesis. Sterile inflammation driven by high-fat diet, increased formation of reactive oxygen species, alteration of intracellular calcium level and associated release of inflammatory mediators, are the main common underlying forces in the pathophysiology of NAFLD, ischemic retinopathy, stroke, and aging brain. This work aims to examine the contribution of the pro-oxidative and pro-inflammatory thioredoxin interacting protein (TXNIP) to the expression and activation of NLRP3-inflammasome resulting in initiation or exacerbation of sterile inflammation in these disease states. Finally, the potential for TXNIP as a therapeutic target and whether TXNIP expression can be modulated using natural antioxidants or repurposing other drugs will be discussed.

Molecular study of the proliferation process of beta cells derived from pluripotent stem cells

BACKGROUND

Diabetes mellitus (DM) is a chronic metabolic disorder, increasing in the number of patients and poses a severe threat to human health. Significant advances have been made in DM treatment; the most important of which is differentiation and proliferation of beta cells from IPSCs.

METHODS

Data were collected from PUBMED at various time points up to the academic year of 2020. The related keywords are listed as follows: "Induced pluripotent stem cell", "Proliferation", "Growth factor", "Small molecule", "cardiotoxicity" and "Scaffold."

RESULT

The use of growth factors along with small molecules can be a good strategy for beta-cell proliferation. Also, proliferation of beta cells on nanofibers scaffolds can create a similar in vivo environment, that leads to increased function of beta-cell. Some transcription factors that cause beta cells proliferation play an important role in inflammation; so, it is essential to monitor them to prevent inflammation.

CONCLUSION

Finally, the simultaneous use of growth factors, micronutrients and scaffolds can be an excellent strategy to increase the proliferation and function of beta cells derived from IPSCs.

W2476 represses TXNIP transcription via dephosphorylation of FOXO1 at Ser319

Thioredoxin-interacting protein (TXNIP) overexpression is implicated in the pathogenesis of type 2 diabetes. Previous studies have shown that a small molecule compound (W2476) was able to improve β-cell dysfunction and exert therapeutic effects in diabetic mice via repression of TXNIP signaling pathway. The impact of W2476 on TXNIP transcription was thus investigated using the chromatin immunoprecipitation method. It was found that W2476 promotes competitive binding of forkhead box O1 transcription factor (FOXO1) to the carbohydrate response element (ChoRE) sequence associated with ChoRE-binding protein (ChREBP)/Mlx interacting protein-like(Mlx) complexes. This interaction hinders the attachment of histone acetyltransferase p300 and reduces histone H4 acetylation on the TXNIP promoter, leading to decreasing TXNIP transcription.

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.

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.