Peroxiredoxin I deficiency increases pancreatic β‑cell apoptosis after streptozotocin stimulation via the AKT/GSK3β signaling pathway

Redox Status as a Key Driver of Healthy Pancreatic Beta-Cells

Redox status plays a multifaceted role in the intricate physiology and pathology of pancreatic beta-cells, the pivotal regulators of glucose homeostasis through insulin secretion. They are highly responsive to changes in metabolic cues where reactive oxygen species are part of it, all arising from nutritional intake. These molecules not only serve as crucial signaling intermediates for insulin secretion but also participate in the nuanced heterogeneity observed within the beta-cell population. A central aspect of beta-cell redox biology revolves around the localized production of hydrogen peroxide and the activity of NADPH oxidases which are tightly regulated and serve diverse physiological functions. Pancreatic beta-cells possess a remarkable array of antioxidant defense mechanisms although considered relatively modest compared to other cell types, are efficient in preserving redox balance within the cellular milieu. This intrinsic antioxidant machinery operates in concert with redox-sensitive signaling pathways, forming an elaborate redox relay system essential for beta-cell function and adaptation to changing metabolic demands. Perturbations in redox homeostasis can lead to oxidative stress exacerbating insulin secretion defect being a hallmark of type 2 diabetes. Understanding the interplay between redox signaling, oxidative stress, and beta-cell dysfunction is paramount for developing effective therapeutic strategies aimed at preserving beta-cell health and function in individuals with type 2 diabetes. Thus, unraveling the intricate complexities of beta-cell redox biology presents exciting avenues for advancing our understanding and treatment of metabolic disorders.

A new labdane diterpenoid from Scoparia dulcis improving pancreatic function against islets cell apoptotic by Bax/Bcl-2/Caspase-3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Scoparia dulcis has been identified as a significant ethnopharmacological substance in the Li, Zhuang, and Dai ethnic groups of China. Traditional medicine use S. dulcis to treat numerous illnesses, most notably diabetes. The considerable antidiabetic properties of this herbal remedy have been established by several clinical investigations and animal experiments. The islet is the intended target of S. dulcis, although the cause of its activity and mechanism for diabetes treatment is unclear. The diterpenoids from S. dulcis have been shown in the literature to have significant hypoglycemic efficacy and to protect islet cells in vitro. Diterpenoids may be the components of this herbal remedy that preserve islets, but further research is needed.

AIM OF THE STUDY

This study was projected to investigate the new diterpenoid scoparicol E from S. dulcis and examined its islet-protective effect and the potential mechanism both in vitro and in vivo.

METHODS

The structure of the novel diterpenoid scoparicol E was clarified by employing a wide range of spectroscopic methods. Using CCK-8 tests, cytotoxicity and antiapoptotic activity of scoparicol E were detected. Serum biochemical analysis and pathologic examination were performed to study the protective effect of scoparicol E against islet damage. The specific mechanism of action of scoparicol E was investigated through the mitochondrial membrane potential, Annexin V-FITC flow cytometry, and western blotting.

RESULTS

Scoparicol E reduced MLD-STZ-induced hyperglycemia in mice and increased insulin and islet apoptosis. Scoparicol E effectively suppressed the Bax/Bcl-2/Caspase-3 pathway, according to the in vivo western blot investigation. Scoparicol E showed significant antiapoptotic action in vitro. We also showed that scoparicol E might prevent islet cells from dying by inhibiting the Bax/Bcl-2/Caspase-3 pathway. The Annexin V-FITC flow cytometry results revealed that MIN6 cell apoptosis was considerably decreased following scoparicol E intervention, showing anti-islet cell apoptosis action. Furthermore, the Caspase-3-mediated apoptosis pathway depends on cytochrome c and the potential of the mitochondrial membrane. Scoparicol E prevented the release of cytochrome c, restored the mitochondrial membrane potential, and prevented MIN6 cell apoptosis.

CONCLUSION

We demonstrated the new diterpenoid scoparicol E could protect islet cells apoptosis by modulating the Bax/Bcl-2/Caspase-3 pathway.

Effect of peroxiredoxin 1 on the regulation of trophoblast function by affecting autophagy and oxidative stress in preeclampsia

PURPOSE

PE is a pregnancy-specific syndrome and one of the main causes of maternal, fetal, and neonatal mortality. PRDX1 is an antioxidant that regulates cell proliferation, differentiation, and apoptosis. The aim of this study is to investigate the effect of PRDX1 on the regulation of trophoblast function by affecting autophagy and oxidative stress in preeclampsia.

METHODS

Western blotting, RT-qPCR, and immunofluorescence were used to examine the expression of PRDX1 in placentas. PRDX1-siRNA was transfected to knockdown PRDX1 in HTR-8/SVneo cells. The biological function of HTR-8/SVneo cells was detected by wound healing, invasion, tube formation, CCK-8, EdU, flow cytometry, and TUNEL assays. Western blotting was used to detect the protein expression of cleaved-Caspase3, Bax, LC3II, Beclin1, PTEN, and p-AKT. DCFH-DA staining was used to detect ROS levels by flow cytometry.

RESULTS

PRDX1 was significantly decreased in placental trophoblasts in PE patients. Following the exposure of HTR-8/SVneo cells to H₂O₂, PRDX1 expression was significantly decreased, LC3II and Beclin1 expression was notably increased, and ROS level was also markedly increased. PRDX1 knockdown impaired migration, invasion, and tube-formation abilities and promoted apoptosis, which was accompanied by an increased expression of cleaved-Caspase3 and Bax. PRDX1 knockdown induced a significant decrease in LC3II and Beclin1 expression, along with an elevated p-AKT expression and a decreased PTEN expression. PRDX1 knockdown increased intracellular ROS levels, and NAC attenuated PRDX1 knockdown-induced apoptosis.

CONCLUSION

PRDX1 regulated trophoblast function through the PTEN/AKT signaling pathway to affect cell autophagy and ROS level, which provided a potential target for the treatment of PE.

Hydrogen peroxide detoxification through the peroxiredoxin/thioredoxin antioxidant system: A look at the pancreatic β-cell oxidant defense

Reactive oxygen species (ROS), such as hydrogen peroxide, are formed when molecular oxygen obtains additional electrons, increasing its reactivity. While low concentrations of hydrogen peroxide are necessary for regulation of normal cellular signaling events, high concentrations can be toxic. To maintain this balance between beneficial and deleterious concentrations of hydrogen peroxide, cells utilize antioxidants. Our recent work supports a primary role for peroxiredoxin, thioredoxin, and thioredoxin reductase as the oxidant defense pathway used by insulin-producing pancreatic β-cells. These three players work in an antioxidant cycle based on disulfide exchange, with oxidized targets ultimately being reduced using electrons provided by NADPH. Peroxiredoxins also participate in hydrogen peroxide-based signaling through disulfide exchange with redox-regulated target proteins. This chapter will describe the catalytic mechanisms of thioredoxin, thioredoxin reductase, and peroxiredoxin and provide an in-depth look at the roles these enzymes play in antioxidant defense pathways of insulin-secreting β-cells. Finally, we will evaluate the physiological relevance of peroxiredoxin-mediated hydrogen peroxide signaling as a regulator of β-cell function.

Natural COA water inhibits mitochondrial ROS-mediated apoptosis through Plk3 downregulation under STZ diabetic stress in pancreatic β-cell lines

Diabetes from pancreatic β cell death and insulin resistance is a serious metabolic disease in the world. Although the overproduction of mitochondrial reactive oxygen species (ROS) plays an important role in the pathogenesis of diabetes, its specific molecular mechanism remains unclear. Here, we show that the natural Charisma of Aqua (COA) water plays a role in Streptozotocin (STZ) diabetic stress-induced cell death inhibition. STZ induces mitochondrial ROS by increasing Polo-like kinase 3 (Plk3), a major mitotic regulator, in both Beta TC-6 and Beta TC-tet mouse islet cells and leads to apoptosis. Overexpression of Plk3 regulates an increase in mitochondrial ROS as well as cell death, also these events were inhibited by Plk3 gene knockdown in STZ diabetic stimulated-Beta TC-6 cells. Interestingly, we found that natural COA water blocks mitochondrial ROS generation through the reduction of Plk3 and prevents apoptosis in STZ-treated beta cells. Furthermore, using the 3D organoid (ex vivo) system, we confirmed that the insulin secretion of the supernatant medium under STZ treated pancreatic β-cells is protected by the natural COA water. These findings demonstrate that the natural water COA has a beneficial role in maintaining β cell function through the inhibition of mitochondrial ROS-mediated cell death, and it might be introduced as a potential insulin stabilizer.

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Pancreatic β cell is stabilized through natural COA water in STZ-induced diabetes.

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Mitochondrial membrane potential (ΔΨm) is controlled by natural COA water.

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Plk3 expression under STZ treatment is negatively regulated by natural COA water.

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Insulin secretion is stabilized by natural COA water under STZ treatment in ex vivo (3D organoid) model.

Protective Effects of Almond Oil on Streptozotocin-Induced Diabetic Rats via Regulating Nrf2/HO-1 Pathway and Gut Microbiota

Almond oil has been used as a medicine substitution for its numerous health benefits. This study aimed to evaluate the effect of almond oil on streptozotocin- (STZ-) induced diabetic rats for 4 weeks. The results showed that the administration of almond oil could significantly increase body weight, attenuate abnormally elevated blood glucose, promote insulin secretion, and improve glucose tolerance. Almond oil treatment also suppressed oxidative stress, reduced inflammation reaction, improved liver and kidney function, upregulated the expressions of Nrf2, HO-1, and NQO1, while downregulating the expression of Keap1. Furthermore, almond oil reversed the gut microbiota change by STZ and regulated the gut microbiota associated with glucose metabolism. At the phylum level, the relative abundance of Firmicutes was decreased, while Bacteroidetes was increased by almond oil treatment. More importantly, the ratio of Firmicutes/Bacteroidetes was significantly increased. At the genus level, administration of almond oil increased the abundances of Lactobacillus, Bacteroides, and Lachnospiraceae_NK4A136_group, while decreased the abundances of Ruminococcaceae_UCG-014, Clostridium_sensu_stricto_1, and Fusicatenibacter. These results provided evidence for the regulating effect of almond oil on diabetic rats via the Nrf2/HO-1 pathway and gut microbiota.

The Role of Thioredoxin/Peroxiredoxin in the β-Cell Defense Against Oxidative Damage

Oxidative stress is hypothesized to play a role in pancreatic β-cell damage, potentially contributing to β-cell dysfunction and death in both type 1 and type 2 diabetes. Oxidative stress arises when naturally occurring reactive oxygen species (ROS) are produced at levels that overwhelm the antioxidant capacity of the cell. ROS, including superoxide and hydrogen peroxide, are primarily produced by electron leak during mitochondrial oxidative metabolism. Additionally, peroxynitrite, an oxidant generated by the reaction of superoxide and nitric oxide, may also cause β-cell damage during autoimmune destruction of these cells. β-cells are thought to be susceptible to oxidative damage based on reports that they express low levels of antioxidant enzymes compared to other tissues. Furthermore, markers of oxidative damage are observed in islets from diabetic rodent models and human patients. However, recent studies have demonstrated high expression of various isoforms of peroxiredoxins, thioredoxin, and thioredoxin reductase in β-cells and have provided experimental evidence supporting a role for these enzymes in promoting β-cell function and survival in response to a variety of oxidative stressors. This mini-review will focus on the mechanism by which thioredoxins and peroxiredoxins detoxify ROS and on the protective roles of these enzymes in β-cells. Additionally, we speculate about the role of this antioxidant system in promoting insulin secretion.