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

2021 ◽  
Vol 12 ◽  
Author(s):  
Jennifer S. Stancill ◽  
John A. Corbett
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Cell Function ◽  
Cell Damage ◽  
Thioredoxin Reductase ◽  
Β Cells ◽  
Β Cell ◽  
Cell Defense ◽  
Β Cell Function

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.

scholarly journals Lipotoxicity and β-Cell Failure in Type 2 Diabetes: Oxidative Stress Linked to NADPH Oxidase and ER Stress

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3328
Author(s):  
Eloisa Aparecida Vilas-Boas ◽  
Davidson Correa Almeida ◽  
Leticia Prates Roma ◽  
Fernanda Ortis ◽  
Angelo Rafael Carpinelli
Keyword(s):  
Oxidative Stress ◽  
Type 2 Diabetes ◽  
Nadph Oxidase ◽  
Er Stress ◽  
Cell Function ◽  
Caloric Intake ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function

A high caloric intake, rich in saturated fats, greatly contributes to the development of obesity, which is the leading risk factor for type 2 diabetes (T2D). A persistent caloric surplus increases plasma levels of fatty acids (FAs), especially saturated ones, which were shown to negatively impact pancreatic β-cell function and survival in a process called lipotoxicity. Lipotoxicity in β-cells activates different stress pathways, culminating in β-cells dysfunction and death. Among all stresses, endoplasmic reticulum (ER) stress and oxidative stress have been shown to be strongly correlated. One main source of oxidative stress in pancreatic β-cells appears to be the reactive oxygen species producer NADPH oxidase (NOX) enzyme, which has a role in the glucose-stimulated insulin secretion and in the β-cell demise during both T1 and T2D. In this review, we focus on the acute and chronic effects of FAs and the lipotoxicity-induced β-cell failure during T2D development, with special emphasis on the oxidative stress induced by NOX, the ER stress, and the crosstalk between NOX and ER stress.

scholarly journals Emerging role of testosterone in pancreatic β cell function and insulin secretion

2019 ◽  
Vol 240 (3) ◽  
pp. R97-R105 ◽  
Author(s):  
Weiwei Xu ◽  
Jamie Morford ◽  
Franck Mauvais-Jarvis
Keyword(s):  
Insulin Secretion ◽  
Metabolic Regulation ◽  
Cell Function ◽  
Visceral Obesity ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucagon Like Peptide 1 ◽  
Glucose Stimulated Insulin Secretion

One of the most sexually dimorphic aspects of metabolic regulation is the bidirectional modulation of glucose homeostasis by testosterone in male and females. Severe testosterone deficiency predisposes men to type 2 diabetes (T2D), while in contrast, androgen excess predisposes women to hyperglycemia. The role of androgen deficiency and excess in promoting visceral obesity and insulin resistance in men and women respectively is well established. However, although it is established that hyperglycemia requires β cell dysfunction to develop, the role of testosterone in β cell function is less understood. This review discusses recent evidence that the androgen receptor (AR) is present in male and female β cells. In males, testosterone action on AR in β cells enhances glucose-stimulated insulin secretion by potentiating the insulinotropic action of glucagon-like peptide-1. In females, excess testosterone action via AR in β cells promotes insulin hypersecretion leading to oxidative injury, which in turn predisposes to T2D.

scholarly journals A Putative Prohibitin-Calcium Nexus in β-Cell Mitochondria and Diabetes

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Gaurav Verma ◽  
Aparna Dixit ◽  
Craig S. Nunemaker
Keyword(s):  
Cell Function ◽  
Mitochondrial Protein ◽  
Active Role ◽  
Targeted Drugs ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Β Cell Function ◽  
Significant Attention

The role of mitochondria in apoptosis is well known; however, the mechanisms linking mitochondria to the proapoptotic effects of proinflammatory cytokines, hyperglycemia, and glucolipotoxicity are not completely understood. Complex Ca2+ signaling has emerged as a critical contributor to these proapoptotic effects and has gained significant attention in regulating the signaling processes of mitochondria. In pancreatic β-cells, Ca2+ plays an active role in β-cell function and survival. Prohibitin (PHB), a mitochondrial chaperone, is actively involved in maintaining the architecture of mitochondria. However, its possible interaction with Ca2+-activated signaling pathways has not been explored. The present review aims to examine potential crosstalk between Ca2+ signaling and PHB function in pancreatic β-cells. Moreover, this review will focus on the effects of cytokines and glucolipotoxicity on Ca2+ signaling and its possible interaction with PHB. Improved understanding of this important mitochondrial protein may aid in the design of more targeted drugs to identify specific pathways involved with stress-induced dysfunction in the β-cell.

scholarly journals The Role of Oxidative Stress in Pancreatic β Cell Dysfunction in Diabetes

2021 ◽  
Vol 22 (4) ◽  
pp. 1509
Author(s):  
Natsuki Eguchi ◽  
Nosratola D. Vaziri ◽  
Donald C. Dafoe ◽  
Hirohito Ichii
Keyword(s):  
Oxidative Stress ◽  
Cell Function ◽  
Pancreatic Β Cell ◽  
Antioxidative Capacity ◽  
Β Cells ◽  
Β Cell ◽  
Glucose Levels ◽  
Cell Dysfunction ◽  
Elevated Glucose ◽  
Β Cell Function

Diabetes is a chronic metabolic disorder characterized by inappropriately elevated glucose levels as a result of impaired pancreatic β cell function and insulin resistance. Extensive studies have been conducted to elucidate the mechanism involved in the development of β cell failure and death under diabetic conditions such as hyperglycemia, hyperlipidemia, and inflammation. Of the plethora of proposed mechanisms, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, and oxidative stress have been shown to play a central role in promoting β cell dysfunction. It has become more evident in recent years that these 3 factors are closely interrelated and importantly aggravate each other. Oxidative stress in particular is of great interest to β cell health and survival as it has been shown that β cells exhibit lower antioxidative capacity. Therefore, this review will focus on discussing factors that contribute to the development of oxidative stress in pancreatic β cells and explore the downstream effects of oxidative stress on β cell function and health. Furthermore, antioxidative capacity of β cells to counteract these effects will be discussed along with new approaches focused on preserving β cells under oxidative conditions.

Regulation of the susceptibility to oxidative stress by cysteine availability in pancreatic β-cells

2008 ◽  
Vol 295 (2) ◽  
pp. C468-C474 ◽  
Author(s):  
Satoshi Numazawa ◽  
Harumi Sakaguchi ◽  
Risa Aoki ◽  
Toshio Taira ◽  
Takemi Yoshida
Keyword(s):  
Oxidative Stress ◽  
Cell Lines ◽  
Cell Function ◽  
Rinm5f Cells ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Pancreatic Cell ◽  
Intracellular Glutathione ◽  
Β Cell Function

Pancreatic β-cells are susceptible to oxidative stress, which is related closely to the islet dysfunction. In the present study, using the pancreatic cell lines HIT-T15 and RINm5F as known in vitro models of impaired β-cell function as well as primary rat islet β-cells, we observed a relationship between intracellular glutathione levels and oxidative stress-mediated cell dysfunction. Hydrogen peroxide and 4-hydroxy-2-nonenal caused cell death in HIT-T15 and RINm5F cells at lower concentrations compared with non-β-cells, such as HepG2 and NRK-49F cells. The extent of the cytotoxicity caused by the model oxidants was inversely correlated well with intracellular glutathione levels in the cell lines used. Treatment of HIT-T15 and RINm5F cells with l-cysteine or l-cystine significantly augmented the glutathione contents, surpassing the effect of N-acetylcysteine, and abrogated 4-hydroxy-2-nonenal-mediated cytotoxicity almost completely. l-Cysteine increased intracellular glutathione levels in primary β-cells as well. Supplementation of l-cysteine to the RINm5F cell culture inhibited 4-hydroxy-2-nonenal-mediated cytosolic translocation of PDX-1, a key transcription factor for β-cell function. Intrinsic transport activities ( Vmax/ Km) of the l-cystine/l-glutamate exchanger in HIT-T15 and RINm5F cells were considerably lower than that in NRK-49F cells, although gene expressions of the exchanger were similar in these cells. Results obtained from the present study suggest that the restricted activity of the l-cystine/l-glutamate exchanger controls the levels of intracellular glutathione, thereby making β-cells become susceptible to oxidative stress.

scholarly journals The pathogenetic role of β-cell mitochondria in type 2 diabetes

2018 ◽  
Vol 236 (3) ◽  
pp. R145-R159 ◽  
Author(s):  
Malin Fex ◽  
Lisa M Nicholas ◽  
Neelanjan Vishnu ◽  
Anya Medina ◽  
Vladimir V Sharoyko ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Mitochondrial Dysfunction ◽  
Translational Regulation ◽  
Cell Function ◽  
Rare Condition ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function

Mitochondrial metabolism is a major determinant of insulin secretion from pancreatic β-cells. Type 2 diabetes evolves when β-cells fail to release appropriate amounts of insulin in response to glucose. This results in hyperglycemia and metabolic dysregulation. Evidence has recently been mounting that mitochondrial dysfunction plays an important role in these processes. Monogenic dysfunction of mitochondria is a rare condition but causes a type 2 diabetes-like syndrome owing to β-cell failure. Here, we describe novel advances in research on mitochondrial dysfunction in the β-cell in type 2 diabetes, with a focus on human studies. Relevant studies in animal and cell models of the disease are described. Transcriptional and translational regulation in mitochondria are particularly emphasized. The role of metabolic enzymes and pathways and their impact on β-cell function in type 2 diabetes pathophysiology are discussed. The role of genetic variation in mitochondrial function leading to type 2 diabetes is highlighted. We argue that alterations in mitochondria may be a culprit in the pathogenetic processes culminating in type 2 diabetes.

scholarly journals Reactive oxygen and nitrogen species generation, antioxidant defenses, and β-cell function: a critical role for amino acids

2012 ◽  
Vol 214 (1) ◽  
pp. 11-20 ◽  
Author(s):  
P Newsholme ◽  
E Rebelato ◽  
F Abdulkader ◽  
M Krause ◽  
A Carpinelli ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Cell Function ◽  
Reactive Oxygen ◽  
Antioxidant Defenses ◽  
Nitrogen Species ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Β Cell Function ◽  
The Impact

Growing evidence indicates that the regulation of intracellular reactive oxygen species (ROS) and reactive nitrogen species (RNS) levels is essential for maintaining normal β-cell glucose responsiveness. While long-term exposure to high glucose induces oxidative stress in β cells, conflicting results have been published regarding the impact of ROS on acute glucose exposure and their role in glucose stimulated insulin secretion (GSIS). Although β cells are considered to be particularly vulnerable to oxidative damage, as they express relatively low levels of some peroxide-metabolizing enzymes such as catalase and glutathione (GSH) peroxidase, other less known GSH-based antioxidant systems are expressed in β cells at higher levels. Herein, we discuss the key mechanisms of ROS/RNS production and their physiological function in pancreatic β cells. We also hypothesize that specific interactions between RNS and ROS may be the cause of the vulnerability of pancreatic β cells to oxidative damage. In addition, using a hypothetical metabolic model based on the data available in the literature, we emphasize the importance of amino acid availability for GSH synthesis and for the maintenance of β-cell function and viability during periods of metabolic disturbance before the clinical onset of diabetes.

scholarly journals Acute Deletion of METTL14 in β-Cells of Adult Mice Results in Glucose Intolerance

Endocrinology ◽  
2019 ◽  
Vol 160 (10) ◽  
pp. 2388-2394 ◽  
Author(s):  
Lili Men ◽  
Juan Sun ◽  
Guanzheng Luo ◽  
Decheng Ren
Keyword(s):  
Glucose Intolerance ◽  
Cell Function ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Protein Levels ◽  
Adult Mice ◽  
Β Cell Function ◽  
Upregulated Genes

Abstract N6-Methyladenosine (m6A) is the most common and abundant mRNA modification that involves regulating the RNA metabolism. However, the role of m6A in regulating the β-cell function is unclear. Methyltransferase-like 14 (METTL14) is a key component of the m6A methyltransferase complex. To define the role of m6A in regulating the β-cell function, we generated β-cell METTL14-specific knockout (βKO) mice by tamoxifen administration. Acute deletion of Mettl14 in β-cells results in glucose intolerance as a result of a reduction in insulin secretion in β-cells even though β-cell mass is increased, which is related to increased β-cell proliferation. To define the molecular mechanism, we performed RNA sequencing to detect the gene expression in βKO islets. The genes responsible for endoplasmic reticulum stress, such as Ire1α, were among the top upregulated genes. Both mRNA and protein levels of IRE1α and spliced X-box protein binding 1 (sXBP-1) were increased in βKO islets. The protein levels of proinsulin and insulin were decreased in βKO islets. These results suggest that acute METTL14 deficiency in β-cells induces glucose intolerance by increasing the IRE1α/sXBP-1 pathway.

scholarly journals Involvement of the Ca2+-responsive transactivator in high glucose-induced β-cell apoptosis

2012 ◽  
Vol 216 (2) ◽  
pp. 231-243 ◽  
Author(s):  
Xiuli Men ◽  
Liang Peng ◽  
Haiyan Wang ◽  
Wenjian Zhang ◽  
Shiqing Xu ◽  
...  
Keyword(s):  
High Glucose ◽  
Cell Apoptosis ◽  
Cell Function ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Induced Apoptosis ◽  
Sirna Knockdown

The calcium-regulated transcription coactivator, Ca2+-responsive transactivator (CREST) was expressed in pancreatic β-cells. Moreover, CREST expression became significantly increased in pancreatic islets isolated from hyperglycemic Goto–Kakizaki rats compared with normoglycemic Wistar controls. In addition, culture of β-cells in the presence of high glucose concentrations also increased CREST expression in vitro. To further investigate the role of this transactivator in the regulation of β-cell function, we established a stable β-cell line with inducible CREST expression. Hence, CREST overexpression mimicked the glucotoxic effects on insulin secretion and cell growth in β-cells. Moreover, high glucose-induced apoptosis was aggravated by upregulation of the transactivator but inhibited when CREST expression was partially silenced by siRNA technology. Further investigation found that upregulation of Bax and downregulation of Bcl2 was indeed induced by its expression, especially under high glucose conditions. In addition, as two causing factors leading to β-cell apoptosis under diabetic conditions, endoplasmic reticulum stress and high free fatty acid, mimicked the high glucose effects on CREST upregulation and generation of apoptosis in β-cells, and these effects were specifically offset by the siRNA knockdown of CREST. These results indicated that CREST is implicated in β-cell apoptosis induced by culture in high glucose and hence that CREST may become a potential pharmacological target for the prevention and treatment of type 2 diabetes mellitus.

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