scholarly journals Phagocyte-like NADPH oxidase promotes cytokine-induced mitochondrial dysfunction in pancreatic β-cells: evidence for regulation by Rac1

2011 ◽  
Vol 300 (1) ◽  
pp. R12-R20 ◽  
Author(s):  
Wasanthi Subasinghe ◽  
Ismail Syed ◽  
Anjaneyulu Kowluru
Keyword(s):  
Nadph Oxidase ◽  
Mitochondrial Dysfunction ◽  
Caspase 3 ◽  
Primary Source ◽  
Significant Loss ◽  
Ros Generation ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Subunit Expression ◽  
Cellular Signal

Reactive oxygen species (ROS) are important mediators of cellular signal transduction cascades such as proliferation, migration, and apoptosis. Chronic exposure of isolated β-cells to proinflammatory cytokines elevates intracellular oxidative stress leading to the demise of pancreatic β-cells culminating in the onset of diabetes. Although the mitochondrial electron transport chain is felt to be the primary source of ROS, several lines of recent evidence suggest that phagocyte-like NADPH oxidase plays a central role in cytokine-mediated ROS generation and apoptosis of β-cells. However, the precise mechanisms underlying the regulation of NADPH oxidase remain unknown. To address this, insulin-secreting INS 832/13 cells were treated with cytomix (IL-1β, IFN-γ, and TNF-α; 10 ng/ml each) for different time intervals (0–24 h). A significant, time-dependent increase in NADPH oxidase activation/intracellular ROS production, p47phox subunit, but not p67phox subunit, expression of the phagocyte-like NADPH oxidase were demonstrable under these conditions. Furthermore, siRNA-p47phox transfection or exposure of INS 832/13 cells to apocynin, a selective inhibitor of NADPH oxidase, markedly attenuated cytomix-induced ROS generation in these cells. Cytomix-mediated mitochondrial dysfunction in INS 832/13 cells was evident by a significant loss of mitochondrial membrane potential (MMP) and upregulated caspase 3 activity. Cytomix treatment also caused a transient (within 15 min) activation of Rac1, a component of the NADPH oxidase holoenzyme. Furthermore, GGTI-2147 and NSC23766, known Rac1 inhibitors, not only attenuated the cytomix-induced Rac1 activation but also significantly prevented loss of MMP (NSC23766 > GGTI-2147). However, NSC23766 had no effect on cytomix-induced NO generation or caspase 3 activation, suggesting additional regulatory mechanisms might underlie these signaling steps. Together, these findings suggested that Rac1-mediated regulation of phagocyte-like NADPH oxidase contributes to cytokine-mediated mitochondrial dysfunction in the β-cell.

scholarly journals Chebulic Acid Prevents Methylglyoxal-Induced Mitochondrial Dysfunction in INS-1 Pancreatic β-Cells

Antioxidants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 771
Author(s):  
Hyun-jung Yoo ◽  
Chung-Oui Hong ◽  
Sang Keun Ha ◽  
Kwang-Won Lee
Keyword(s):  
Enzyme Activity ◽  
Protein Expression ◽  
Western Blot ◽  
Mitochondrial Dysfunction ◽  
Atp Synthesis ◽  
Ros Production ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Chebulic Acid ◽  
Cyt C

To investigate the anti-diabetic properties of chebulic acid (CA) associated with the prevention of methyl glyoxal (MG)-induced mitochondrial dysfunction in INS-1 pancreatic β-cells, INS-1 cells were pre-treated with CA (0.5, 1.0, and 2.0 μM) for 48 h and then treated with 2 mM MG for 8 h. The effects of CA and MG on INS-1 cells were evaluated using the following: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; glyoxalase 1 (Glo-1) expression via Western blot and enzyme activity assays; Nrf-2, nuclear factor erythroid 2-related factor 2 protein expression via Western blot assay; reactive oxygen species (ROS) production assay; mRNA expression of mitochondrial dysfunction related components (UCP2, uncoupling protein 2; VDAC1, voltage-dependent anion-selective channel-1; cyt c, cytochrome c via quantitative reverse transcriptase-PCR; mitochondrial membrane potential (MMP); adenosine triphosphate (ATP) synthesis; glucose-stimulated insulin secretion (GSIS) assay. The viability of INS-1 cells was maintained upon pre-treating with CA before exposure to MG. CA upregulated Glo-1 protein expression and enzyme activity in INS-1 cells and prevented MG-induced ROS production. Mitochondrial dysfunction was alleviated by CA pretreatment; this occurred via the downregulation of UCP2, VDAC1, and cyt c mRNA expression and the increase of MMP and ATP synthesis. Further, CA pre-treatment promoted the recovery from MG-induced decrease in GSIS. These results indicated that CA could be employed as a therapeutic agent in diabetes due to its ability to prevent MG-induced development of insulin sensitivity and oxidative stress-induced dysfunction of β-cells.

scholarly journals Glycated Albumin Causes Pancreatic β-Cells Dysfunction Through Autophagy Dysfunction

Endocrinology ◽  
2013 ◽  
Vol 154 (8) ◽  
pp. 2626-2639 ◽  
Author(s):  
Young Mi Song ◽  
Sun Ok Song ◽  
Young-Hye You ◽  
Kun-Ho Yoon ◽  
Eun Seok Kang ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Glycated Albumin ◽  
Nuclear Factor Κb ◽  
Nuclear Factor ◽  
Bafilomycin A1 ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Autophagy Induction ◽  
Interfering Rna

Abstract Growing evidence suggests that advanced glycation end-products (AGEs) are cytotoxic to pancreatic β-cells. The aims of this study were to investigate whether glycated albumin (GA), an early precursor of AGEs, would induce dysfunction in pancreatic β-cells and to determine which kinds of cellular mechanisms are activated in GA-induced β-cell apoptosis. Decreased viability and increased apoptosis were induced in INS-1 cells treated with 2.5 mg/mL GA under 16.7mM high-glucose conditions. Insulin content and glucose-stimulated secretion from isolated rat islets were reduced in 2.5 mg/mL GA-treated cells. In response to 2.5 mg/mL GA in INS-1 cells, autophagy induction and flux decreased as assessed by green fluorescent protein–microtubule-associated protein 1 light chain 3 dots, microtubule-associated protein 1 light chain 3-II conversion, and SQSTM1/p62 in the presence and absence of bafilomycin A1. Accumulated SQSTM1/p62 through deficient autophagy activated the nuclear factor-κB (p65)-inducible nitric oxide synthase-caspase-3 cascade, which was restored by treatment with small interfering RNA against p62. Small interfering RNA treatment against autophagy-related protein 5 significantly inhibited the autophagy machinery resulting in a significant increase in iNOS-cleaved caspase-3 expression. Treatment with 500μM 4-phenyl butyric acid significantly alleviated the expression of endoplasmic reticulum stress markers and iNOS in parallel with upregulated autophagy induction. However, in the presence of bafilomycin A1, the decreased viability of INS-1 cells was not recovered. Glycated albumin, an early precursor of AGE, caused pancreatic β-cell death by inhibiting autophagy induction and flux, resulting in nuclear factor-κB (p65)-iNOS-caspase-3 cascade activation as well as by increasing susceptibility to endoplasmic reticulum stress and oxidative stress.

scholarly journals Identification of a novel lncRNA (G3R1) regulated by GLIS3 in pancreatic β-cells

2020 ◽  
Vol 65 (3) ◽  
pp. 59-67
Author(s):  
David W Scoville ◽  
Artiom Gruzdev ◽  
Anton M Jetten
Keyword(s):  
Pancreatic Islets ◽  
Knockout Mouse ◽  
Cell Function ◽  
Significant Loss ◽  
Messenger Rnas ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Phenotypic Analysis ◽  
Cell Functions

Recent advances in high throughput RNA sequencing have revealed that, in addition to messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs) play an important role in the regulation of many cell functions and of organ development. While a number of lncRNAs have been identified in pancreatic islets, their function remains largely undetermined. Here, we identify a novel long ncRNA regulated by the transcription factor GLIS3, which we refer to as GLIS3 regulated 1 (G3R1). This lncRNA was identified for its significant loss of expression in GLIS3 knockout mouse pancreatic islets. G3R1 appears to be specifically expressed in mouse pancreatic β-cells and in a β-cell line (βTC-6). ChIP-seq analysis indicated that GLIS3 and other islet-enriched transcription factors bind near the G3R1 gene, suggesting they directly regulate G3R1 transcription. Similarly, an apparent human homolog of G3R1 displays a similar expression pattern, with additional expression seen in human brain. In order to determine the function of G3R1 in mouse pancreatic β-cells, we utilized CRISPR to develop a knockout mouse where ~80% of G3R1 sequence is deleted. Phenotypic analysis of these mice did not reveal any impairment in β-cell function or glucose regulation, indicating the complexity underlying the study of lncRNA function.

scholarly journals Antioxidant activity of a new multiflorane-type triterpene from seeds of Cucurbita Argyrosperma and their protective role on hydrogen peroxide induced oxidative stress

2020 ◽  
Vol 10 (2) ◽  
pp. 95
Author(s):  
Rosa Martha Perez Gutierrez ◽  
Alethia Muñiz Ramirez ◽  
Jose Maria Mota Flores ◽  
Abraham Heriberto Garcia Campoy
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Free Radical ◽  
Cell Viability ◽  
Caspase 3 ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells

Background: Cucurbita Argyrosperma seeds have acquired a reputation as an herbal remedy to treat various diseases because this plant is a predominant source of natural compounds with potent anti-inflammatory, antioxidant properties, and seed supplementation improves oxidative stress. Previous studies indicated that an imbalance between H2O2 production and elimination capacity is responsible for β-cell vulnerability, making β-cell a target susceptible to pathological disasters.This investigation aimed to evaluate the protective effects of one new multiflorane-type triterpene  3β-trans-caffeoyloxymultiflor-8-ene- 7α,12β, 18 β-triol (1)  from MeOH extract from C. Argyrosperma, on rat pancreatic β cells (INS-1 cells) exposed to hydrogen peroxide (H2O2) induced oxidative stress conditions.Methods: The chemical structure of the novel triterpene, which was identified as 3β-trans-caffeoyloxymultiflor-8-ene- 7α,12β, 18 β-triol (1), was established based on the interpretation of spectroscopic analyses. The antioxidant activities of 1 were leaded by detect radical scavenging potential of 2,2-dyphenyl-1-picrylhydrazyl (DPPH) and 3.1 2,2′-Azino-bis(3-Ethylbenzothiazoline-6-Sulfonic Acid) ABTS. The assays were conducted on INS-1 cells line exposed to increasing concentrations of 1 at 5,10 and 20 µg/mL and H2O2 at 250 µM. Then, the experiments, cell viability, cell integrity ((LDH; lactate dehydrogenase release), mitochondrial function (ATP analysis), ROS formation, lipid peroxidation (MDA) and caspase-3, 9 activities were measured in the cells. We also determined the effect of 1 on antioxidant enzyme levels and cytotoxicity in pancreatic β cells under oxidant conditions.Results: The results showed that triterpene displayed high free-radical-scavenging activity, which is similar to that of standard antioxidants used. At concentrations of 5, 10, and 20 𝜇g/mL protect INS-1 cells against H2O2 induced cytotoxicity decrease in cell death, with a marked increase in cell viability, sustained cellular functionality (ATP). Antioxidant enzymes such as glutathione peroxidase (GPx), glutathione reduced (GSH), catalase (CAT), superoxide dismutase (SOD), and the non-antioxidant enzyme (GSH) increased in INS-1 cells with 1 pretreatment. MDA in pancreatic cells was ameliorated by 1 pretreatment reducing intracellular reactive oxygen species level. Findings also demonstrated that H2O2-induced apoptosis in INS-1 cells and produced modulation of the caspase-3, 9 expressions in INS-1 cells exposed to 1. Exposure to 1significantly inhibited ROS and apoptosis production, reducing β cell dysfunction under oxidant conditions.Conclusions: Triterpene consequently could be a promising natural antioxidant for use in maintaining the integrity of pancreatic β-cells exposed to oxidative stress conditions being able to participate in the control type 2 diabetes.Keywords: Cucurbita Argyrosperma; antioxidants; multiflorane; free radical scavenging: oxidative stress

scholarly journals mTORC in β cells: more Than Only Recognizing Comestibles

2017 ◽  
Vol 216 (7) ◽  
pp. 1883-1885 ◽  
Author(s):  
Kathrin Maedler ◽  
Amin Ardestani
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dysfunction ◽  
Cell Survival ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Cell Biol

The pathways regulating pancreatic β cell survival in diabetes are poorly understood. Here, Chau et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201701085) demonstrate that mTOR regulates the apoptotic machinery through binding to the ChREBP–Mlx complex to suppress TXNIP, thereby protecting pancreatic β cells in the diabetic setting by inhibiting oxidative stress and mitochondrial dysfunction.

scholarly journals Phagocyte-like NADPH oxidase (Nox2) promotes activation of p38MAPK in pancreatic β-cells under glucotoxic conditions: Evidence for a requisite role of Ras-related C3 botulinum toxin substrate 1 (Rac1)

2015 ◽  
Vol 95 (4) ◽  
pp. 301-310 ◽  
Author(s):  
Vaibhav Sidarala ◽  
Rajakrishnan Veluthakal ◽  
Khadija Syeda ◽  
Cornelis Vlaar ◽  
Philip Newsholme ◽  
...  
Keyword(s):  
Botulinum Toxin ◽  
Nadph Oxidase ◽  
Β Cells ◽  
Pancreatic Β Cells
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