Nε-(carboxymethyl) lysine-induced mitochondrial fission and mitophagy cause decreased insulin secretion from β-cells

2015 ◽  
Vol 309 (10) ◽  
pp. E829-E839 ◽  
Author(s):  
Mei-Chen Lo ◽  
Ming-Hong Chen ◽  
Wen-Sen Lee ◽  
Chin-I Lu ◽  
Chuang-Rung Chang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Fission ◽  
Lipid Peroxide ◽  
Mitochondrial Morphology ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Atp Production ◽  
Mitochondrial Functions ◽  
Carboxymethyl Lysine

Nε-(carboxymethyl) lysine-conjugated bovine serum albumin (CML-BSA) is a major component of advanced glycation end products (AGEs). We hypothesised that AGEs reduce insulin secretion from pancreatic β-cells by damaging mitochondrial functions and inducing mitophagy. Mitochondrial morphology and the occurrence of autophagy were examined in pancreatic islets of diabetic db/db mice and in the cultured CML-BSA-treated insulinoma cell line RIN-m5F. In addition, the effects of α-lipoic acid (ALA) on mitochondria in AGE-damaged tissues were evaluated. The diabetic db/db mouse exhibited an increase in the number of autophagosomes in damaged mitochondria and receptor for AGEs (RAGE). Treatment of db/db mice with ALA for 12 wk increased the number of mitochondria with well-organized cristae and fewer autophagosomes. Treatment of RIN-m5F cells with CML-BSA increased the level of RAGE protein and autophagosome formation, caused mitochondrial dysfunction, and decreased insulin secretion. CML-BSA also reduced mitochondrial membrane potential and ATP production, increased ROS and lipid peroxide production, and caused mitochondrial DNA deletions. Elevated fission protein dynamin-related protein 1 (Drp1) level and mitochondrial fragmentation demonstrated the unbalance of mitochondrial fusion and fission in CML-BSA-treated cells. Additionally, increased levels of Parkin and PTEN-induced putative kinase 1 protein suggest that fragmented mitochondria were associated with increased mitophagic activity, and ALA attenuated the CML-BSA-induced mitophage formation. Our study demonstrated that CML-BSA induced mitochondrial dysfunction and mitophagy in pancreatic β-cells. The findings from this study suggest that increased concentration of AGEs may damage β-cells and reduce insulin secretion.

scholarly journals Cytoprotective Effects of N-Acetylcysteine on Streptozotocin- Induced Oxidative Stress and Apoptosis in RIN-5F Pancreatic β-Cells

2018 ◽  
Vol 51 (1) ◽  
pp. 201-216 ◽  
Author(s):  
Arwa M.T. Al-Nahdi ◽  
Annie John ◽  
Haider  Raza
Keyword(s):  
Oxidative Stress ◽  
Insulin Secretion ◽  
Molecular Mechanisms ◽  
Protective Action ◽  
Mitochondrial Enzymes ◽  
Partial Recovery ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Mitochondrial Energy Metabolism ◽  
Mitochondrial Functions

Background/Aims: Numerous studies have reported overproduction of reactive oxygen species (ROS) and alterations in mitochondrial energy metabolism in the development of diabetes and its complications. The potential protective effects of N-acetylcysteine (NAC) in diabetes have been reported in many therapeutic studies. NAC has been shown to reduce oxidative stress and enhance redox potential in tissues protecting them against oxidative stress associated complications in diabetes. In the current study, we aimed to investigate the molecular mechanisms of the protective action of NAC on STZ-induced toxicity in insulin secreting Rin-5F pancreatic β-cells. Methods: Rin-5F cells were grown to 80% confluence and then treated with 10mM STZ for 24h in the presence or absence of 10mM NAC. After sub-cellular fractionation, oxidative stress, GSH-dependent metabolism and mitochondrial respiratory functions were studied using spectrophotometric, flow cytometric and Western blotting techniques. Results: Our results showed that STZ-induced oxidative stress and apoptosis caused inhibition in insulin secretion while NAC treatment restored the redox homeostasis, enhanced insulin secretion in control cells and prevented apoptosis in STZ-treated cells. Moreover, NAC attenuated the inhibition of mitochondrial functions induced by STZ through partial recovery of the mitochondrial enzymes and restoration of membrane potential. STZ-induced DNA damage and expression of apoptotic proteins were significantly inhibited in NAC-treated cells. Conclusion: Our results suggest that the cytoprotective action of NAC is mediated via suppression of oxidative stress and apoptosis and restoration of GSH homeostasis and mitochondrial bioenergetics. This study may, thus, help in better understanding the cellular defense mechanisms of pancreatic β-cells against STZ-induced cytotoxicity.

scholarly journals Porphyromonas gingivalis infection promotes mitochondrial dysfunction through Drp1-dependent mitochondrial fission in endothelial cells

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Tong Xu ◽  
Qin Dong ◽  
Yuxiao Luo ◽  
Yanqing Liu ◽  
Liang Gao ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Mitochondrial Dysfunction ◽  
Porphyromonas Gingivalis ◽  
Vascular Endothelial Cells ◽  
Mitochondrial Fission ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Atp Production ◽  
Luminescence Assay ◽  
The Impact

AbstractPorphyromonas gingivalis (P. gingivalis), a key pathogen in periodontitis, has been shown to accelerate the progression of atherosclerosis (AS). However, the definite mechanisms remain elusive. Emerging evidence supports an association between mitochondrial dysfunction and AS. In our study, the impact of P. gingivalis on mitochondrial dysfunction and the potential mechanism were investigated. The mitochondrial morphology of EA.hy926 cells infected with P. gingivalis was assessed by transmission electron microscopy, mitochondrial staining, and quantitative analysis of the mitochondrial network. Fluorescence staining and flow cytometry analysis were performed to determine mitochondrial reactive oxygen species (mtROS) and mitochondrial membrane potential (MMP) levels. Cellular ATP production was examined by a luminescence assay kit. The expression of key fusion and fission proteins was evaluated by western blot and immunofluorescence. Mdivi-1, a specific Drp1 inhibitor, was used to elucidate the role of Drp1 in mitochondrial dysfunction. Our findings showed that P. gingivalis infection induced mitochondrial fragmentation, increased the mtROS levels, and decreased the MMP and ATP concentration in vascular endothelial cells. We observed upregulation of Drp1 (Ser616) phosphorylation and translocation of Drp1 to mitochondria. Mdivi-1 blocked the mitochondrial fragmentation and dysfunction induced by P. gingivalis. Collectively, these results revealed that P. gingivalis infection promoted mitochondrial fragmentation and dysfunction, which was dependent on Drp1. Mitochondrial dysfunction may represent the mechanism by which P. gingivalis exacerbates atherosclerotic lesions.

scholarly journals Involvement of a Mitochondrial Phosphatase in the Regulation of ATP Production and Insulin Secretion in Pancreatic β Cells

2005 ◽  
Vol 19 (2) ◽  
pp. 197-207 ◽  
Author(s):  
David J. Pagliarini ◽  
Sandra E. Wiley ◽  
Michelle E. Kimple ◽  
Jesse R. Dixon ◽  
Patrick Kelly ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Atp Production

CFTR silencing in pancreatic β-cells reveals a functional impact on glucose-stimulated insulin secretion and oxidative stress response

2016 ◽  
Vol 310 (3) ◽  
pp. E200-E212 ◽  
Author(s):  
Thierry Ntimbane ◽  
Geneviève Mailhot ◽  
Schohraya Spahis ◽  
Remi Rabasa-Lhoret ◽  
Marie-Laure Kleme ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cystic Fibrosis ◽  
Insulin Secretion ◽  
Inflammatory Responses ◽  
Lipid Peroxides ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Min6 Cells ◽  
Atp Production

Cystic fibrosis (CF)-related diabetes (CFRD) has become a critical complication that seriously affects the clinical outcomes of CF patients. Although CFRD has emerged as the most common nonpulmonary complication of CF, little is known about its etiopathogenesis. Additionally, whether oxidative stress (OxS), a common feature of CF and diabetes, influences CFRD pathophysiology requires clarification. The main objective of this study was to shed light on the role of the cystic fibrosis transmembrane conductance regulator (CFTR) in combination with OxS in insulin secretion from pancreatic β-cells. CFTR silencing was accomplished in MIN6 cells by stable expression of small hairpin RNAs (shRNA), and glucose-induced insulin secretion was evaluated in the presence and absence of the valuable prooxidant system iron/ascorbate (Fe/Asc; 0.075/0.75 mM) along with or without the antioxidant Trolox (1 mM). Insulin output from CFTR-silenced MIN6 cells was significantly reduced (∼70%) at basal and at different glucose concentrations compared with control Mock cells. Furthermore, CFTR silencing rendered MIN6 cells more sensitive to OxS as evidenced by both increased lipid peroxides and weakened antioxidant defense, especially following incubation with Fe/Asc. The decreased insulin secretion in CFTR-silenced MIN6 cells was associated with high levels of NF-κB (the major participant in inflammatory responses), raised apoptosis, and diminished ATP production in response to the Fe/Asc challenge. However, these defects were alleviated by the addition of Trolox, thereby pointing out the role of OxS in aggravating the effects of CFTR deficiency. Our findings indicate that CFTR deficiency in combination with OxS may contribute to endocrine cell dysfunction and insulin secretion, which at least in part may explain the development of CFRD.

Triphenyltin impairs insulin secretion by decreasing glucose-induced NADP(H) and ATP production in hamster pancreatic β-cells

Toxicology ◽  
2012 ◽  
Vol 299 (2-3) ◽  
pp. 165-171 ◽  
Author(s):  
Yoshikazu Miura ◽  
Yuichi Hori ◽  
Shinzo Kimura ◽  
Hiroyuki Hachiya ◽  
Yuichirou Sakurai ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Atp Production

scholarly journals Bezafibrate Improves Mitochondrial Fission and Function in DNM1L-Deficient Patient Cells

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 301 ◽  
Author(s):  
Liza Douiev ◽  
Ruth Sheffer ◽  
Gabriella Horvath ◽  
Ann Saada
Keyword(s):  
De Novo ◽  
Neurodevelopmental Disorder ◽  
Mitochondrial Fission ◽  
Fibroblast Cell ◽  
Multiple Organ ◽  
Mitochondrial Morphology ◽  
Main Role ◽  
Atp Production ◽  
Organ Systems ◽  
Mitochondrial Functions

Mitochondria are involved in many cellular processes and their main role is cellular energy production. They constantly undergo fission and fusion, and these counteracting processes are under strict balance. The cytosolic dynamin-related protein 1, Drp1, or dynamin-1-like protein (DNM1L) mediates mitochondrial and peroxisomal division. Defects in the DNM1L gene result in a complex neurodevelopmental disorder with heterogeneous symptoms affecting multiple organ systems. Currently there is no curative treatment available for this condition. We have previously described a patient with a de novo heterozygous c.1084G>A (p.G362S) DNM1L mutation and studied the effects of a small molecule, bezafibrate, on mitochondrial functions in this patient’s fibroblasts compared to controls. Bezafibrate normalized growth on glucose-free medium, as well as ATP production and oxygen consumption. It improved mitochondrial morphology in the patient’s fibroblasts, although causing a mild increase in ROS production at the same time. A human foreskin fibroblast cell line overexpressing the p.G362S mutation showed aberrant mitochondrial morphology, which normalized in the presence of bezafibrate. Further studies would be needed to show the consistency of the response to bezafibrate, possibly using fibroblasts from patients with different mutations in DNM1L, and this treatment should be confirmed in clinical trials. However, taking into account the favorable effects in our study, we suggest that bezafibrate could be offered as a treatment option for patients with certain DNM1L mutations.

Glucolipotoxicity-induced oxidative stress is related to mitochondrial dysfunction and apoptosis of pancreatic β-cell

2020 ◽  
Vol 16 ◽  
Author(s):  
Jorge E. Vela-Guajardo ◽  
Salvador Garza-González ◽  
Noemí García
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Insulin Secretion ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Dynamics ◽  
Atp Synthesis ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Diabetes Development

: Glucolipotoxicity-induced oxidative stress and mitochondrial dysfunction of pancreatic β-cells are one of the mechanisms that have been related to the low insulin secretion and cell death during diabetes development. In early or non-chronic stages, the pancreatic β-cells respond to hyperglycemia or hyperlipidemia, stimulating insulin secretion. However, the chronic effect of both leads to the establishment of glucolipotoxicity which induces constant overstimulation of pancreatic β-cells, a condition that leads to cell death by apoptosis. The mechanism described, at this moment, is the accelerated mitochondrial dysfunction triggered by the high production of reactive oxygen species (ROS) due to excess nutrients. At first, mitochondria respond to over-nutrition accelerating oxygen consumption and consequently increasing the ATP synthesis. A permanent increase of ATP/ADP ratio leads to a constant inhibition of K+ ATP-channel and therefore a continuous insulin secretion accompanied by an increase in ROS. Finally, ROS accumulation compromises mitochondrial function due to the uncontrolled oxidation of proteins, lipids, and DNA generating functional alterations such as a drop of membrane potential, deregulation of mitochondrial dynamics, low rate of ATP synthesis and consequently the cell death. This review aims to describe the effect of glucolipotoxicity-induced oxidative stress and its relationship with mitochondrial dysfunction in β-cell during type 2 diabetes development.

scholarly journals DIMT1, a regulator of ribosomal biogenesis, controls β-cell protein synthesis, mitochondrial function and insulin secretion

2020 ◽  
Author(s):  
Gaurav Verma ◽  
Alexander Bowen ◽  
Alexander Hamilton ◽  
Jonathan Esguerra ◽  
Alexandros Karagiannopoulos ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Insulin Secretion ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Cell Protein ◽  
Ribosomal Biogenesis ◽  
Β Cells ◽  
Β Cell ◽  
Ribosomal Subunits ◽  
Atp Production

AbstractWe previously reported that transcription factor B1 mitochondrial (TFB1M) is involved in the pathogenesis of type 2 diabetes (T2D) owing to mitochondrial dysfunction. Here, we describe that dimethyladenosine transferase 1 homolog (DIMT1), a homologue of TFB1M, is expressed and active in pancreatic β-cells. Like TFB1M, it has been implicated in control of ribosomal RNA (rRNA) but its role in β-cells or T2D remains to be identified. Silencing of DIMT1 impacted mitochondrial function, leading to reduced expression of mitochondrial OXPHOS proteins, reduced oxygen consumption rate (OCR), dissipated mitochondrial membrane potential (ΔΨm) and caused a lower rate of ATP production (mATP). In addition, DIMT1 knockdown slowed the rate of protein synthesis. In accordance with these findings, DIMT1-deficiency perturbed insulin secretion in rodent and human β-cell lines. These effects are likely a result of destabilization of ribosomal assembly, involving NIN1 (RPN12) binding protein 1 homolog (NOB-1) and Pescadillo ribosomal biogenesis factor 1 (PES-1). These are two critical ribosomal subunits proteins, whose interactions were perturbed upon DIMT1-deficiency, thereby disturbing protein synthesis in β-cells. Thus, we have here highlighted a role of DIMT1 in ribosomal biogenesis that perturbs protein synthesis, resulting in mitochondrial dysfunction and disrupted insulin secretion, both being potential pathogenetic factors in T2D.

scholarly journals Role of mitochondrial phosphate carrier in metabolism–secretion coupling in rat insulinoma cell line INS-1

2011 ◽  
Vol 435 (2) ◽  
pp. 421-430 ◽  
Author(s):  
Yuichi Nishi ◽  
Shimpei Fujimoto ◽  
Mayumi Sasaki ◽  
Eri Mukai ◽  
Hiroki Sato ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Critical Role ◽  
Mitochondrial Fraction ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Atp Production ◽  
Insulinoma Cell ◽  
Consequent Reduction ◽  
Phosphate Carrier

In pancreatic β-cells, glucose-induced mitochondrial ATP production plays an important role in insulin secretion. The mitochondrial phosphate carrier PiC is a member of the SLC25 (solute carrier family 25) family and transports Pi from the cytosol into the mitochondrial matrix. Since intramitochondrial Pi is an essential substrate for mitochondrial ATP production by complex V (ATP synthase) and affects the activity of the respiratory chain, Pi transport via PiC may be a rate-limiting step for ATP production. We evaluated the role of PiC in metabolism–secretion coupling in pancreatic β-cells using INS-1 cells manipulated to reduce PiC expression by siRNA (small interfering RNA). Consequent reduction of the PiC protein level decreased glucose (10 mM)-stimulated insulin secretion, the ATP:ADP ratio in the presence of 10 mM glucose and elevation of intracellular calcium concentration in response to 10 mM glucose without affecting the mitochondrial membrane potential (Δψm) in INS-1 cells. In experiments using the mitochondrial fraction of INS-1 cells in the presence of 1 mM succinate, PiC down-regulation decreased ATP production at various Pi concentrations ranging from 0.001 to 10 mM, but did not affect Δψm at 3 mM Pi. In conclusion, the Pi supply to mitochondria via PiC plays a critical role in ATP production and metabolism–secretion coupling in INS-1 cells.

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