scholarly journals Longitudinal Intravital Imaging of Biosensor-labeled In Situ Islet Beta Cells

2019 ◽  
Author(s):  
Christopher A. Reissaus ◽  
Ashley N. Twigg ◽  
Kara S. Orr ◽  
Abass M. Conteh ◽  
Michelle M. Martinez ◽  
...  
Keyword(s):  
Β Cells ◽  
Dynamic Nature ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Longitudinal Measurements ◽  
Ros Accumulation

AbstractImpaired function and apoptosis of insulin-secreting islet β-cells is central to disease progression in both type 1 and type 2 diabetes. Oxidative damage resulting from excess reactive oxygen species (ROS) is a central factor in β-cell dysfunction and death, but the dynamic nature of ROS accumulation and its depletion pose a problem for mechanistic studies in vivo. Biosensors, including the redox-sensitive GFP (roGFPs), coupled with intravital microscopy provide a sensitive and dynamic solution to this problem. Here, we utilize a virally-delivered roGFP2-containing human glutaredoxin-1 (Grx1-roGFP2) to selectively monitor β-cell ROS dynamics in vivo in response to toxic glucose analogs. We paired viral biosensor delivery with implanted abdominal imaging windows over the pancreas, thus allowing longitudinal measurements of β-cell ROS and islet area during and after streptozotocin (STZ) exposure. The studies presented here represent a robust experimental platform that could be readily adapted to various transgenic or physiological mouse models in conjunction with any number of available biosensors, and thus opens a vast realm of potential for discovery in islet biology in vivo.

scholarly journals G6PD Up-Regulation Promotes Pancreatic β-Cell Dysfunction

Endocrinology ◽  
2011 ◽  
Vol 152 (3) ◽  
pp. 793-803 ◽  
Author(s):  
Joo-Won Lee ◽  
A Hyun Choi ◽  
Mira Ham ◽  
Ji-Won Kim ◽  
Sung Sik Choe ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Cell Apoptosis ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Ros Accumulation ◽  
Glucose Stimulated Insulin Secretion ◽  
Reduced Nicotinamide Adenine Dinucleotide

Increased reactive oxygen species (ROS) induce pancreatic β-cell dysfunction during progressive type 2 diabetes. Glucose-6-phosphate dehydrogenase (G6PD) is a reduced nicotinamide adenine dinucleotide phosphate-producing enzyme that plays a key role in cellular reduction/oxidation regulation. We have investigated whether variations in G6PD contribute to β-cell dysfunction through regulation of ROS accumulation and β-cell gene expression. When the level of G6PD expression in pancreatic islets was examined in several diabetic animal models, such as db/db mice and OLEFT rats, G6PD expression was evidently up-regulated in pancreatic islets in diabetic animals. To investigate the effect of G6PD on β-cell dysfunction, we assessed the levels of cellular ROS, glucose-stimulated insulin secretion and β-cell apoptosis in G6PD-overexpressing pancreatic β-cells. In INS-1 cells, G6PD overexpression augmented ROS accumulation associated with increased expression of prooxidative enzymes, such as inducible nitric oxide synthase and reduced nicotinamide adenine dinucleotide phosphate oxidase. G6PD up-regulation also caused decrease in glucose-stimulated insulin secretion in INS-1 cells and primary pancreatic islets. Moreover, elevated G6PD expression led to β-cell apoptosis, concomitant with the increase in proapoptotic gene expression. On the contrary, suppression of G6PD with small interference RNA attenuated palmitate-induced β-cell apoptosis. Together, these data suggest that up-regulation of G6PD in pancreatic β-cells would induce β-cell dysregulation through ROS accumulation in the development of type 2 diabetes.

scholarly journals Neratinib protects pancreatic beta cells in diabetes

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Amin Ardestani ◽  
Sijia Li ◽  
Karthika Annamalai ◽  
Blaz Lupse ◽  
Shirin Geravandi ◽  
...  
Keyword(s):  
Pancreatic Beta Cells ◽  
Cell Function ◽  
Cell Mass ◽  
Human Islets ◽  
Β Cells ◽  
Β Cell

Abstract The loss of functional insulin-producing β-cells is a hallmark of diabetes. Mammalian sterile 20-like kinase 1 (MST1) is a key regulator of pancreatic β-cell death and dysfunction; its deficiency restores functional β-cells and normoglycemia. The identification of MST1 inhibitors represents a promising approach for a β-cell-protective diabetes therapy. Here, we identify neratinib, an FDA-approved drug targeting HER2/EGFR dual kinases, as a potent MST1 inhibitor, which improves β-cell survival under multiple diabetogenic conditions in human islets and INS-1E cells. In a pre-clinical study, neratinib attenuates hyperglycemia and improves β-cell function, survival and β-cell mass in type 1 (streptozotocin) and type 2 (obese Leprdb/db) diabetic mouse models. In summary, neratinib is a previously unrecognized inhibitor of MST1 and represents a potential β-cell-protective drug with proof-of-concept in vitro in human islets and in vivo in rodent models of both type 1 and type 2 diabetes.

Oxidative stress: the vulnerable β-cell

2008 ◽  
Vol 36 (3) ◽  
pp. 343-347 ◽  
Author(s):  
Sigurd Lenzen
Keyword(s):  
Type 2 Diabetes ◽  
Reactive Oxygen ◽  
Reactive Species ◽  
Β Cells ◽  
Β Cell ◽  
Subsequent Formation ◽  
Redox Imbalance ◽  
Cell Dysfunction

Antioxidative defence mechanisms of pancreatic β-cells are particularly weak and can be overwhelmed by redox imbalance arising from overproduction of reactive oxygen and reactive nitrogen species. The consequences of this redox imbalance are lipid peroxidation, oxidation of proteins, DNA damage and interference of reactive species with signal transduction pathways, which contribute significantly to β-cell dysfunction and death in Type 1 and Type 2 diabetes mellitus. Reactive oxygen species, superoxide radicals (O2•−), hydrogen peroxide (H2O2) and, in a final iron-catalysed reaction step, the most reactive and toxic hydroxyl radicals (OH•) are produced during both pro-inflammatory cytokine-mediated β-cell attack in Type 1 diabetes and glucolipotoxicity-mediated β-cell dysfunction in Type 2 diabetes. In combination with NO•, which is toxic in itself, as well as through its reaction with the O2•− and subsequent formation of peroxynitrite, reactive species play a central role in β-cell death during the deterioration of glucose tolerance in the development of diabetes.

scholarly journals 5-Bromoprotocatechualdehyde Combats against Palmitate Toxicity by Inhibiting Parkin Degradation and Reducing ROS-Induced Mitochondrial Damage in Pancreatic β-Cells

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 264
Author(s):  
Seon-Heui Cha ◽  
Chunying Zhang ◽  
Soo-Jin Heo ◽  
Hee-Sook Jun
Keyword(s):  
Cell Loss ◽  
Cellular Damage ◽  
Mitochondrial Morphology ◽  
Protective Effects ◽  
Β Cells ◽  
Β Cell ◽  
Zebrafish Model ◽  
Cell Dysfunction ◽  
Glucose Stimulated Insulin Secretion

Pancreatic β-cell loss is critical in diabetes pathogenesis. Up to now, no effective treatment has become available for β-cell loss. A polyphenol recently isolated from Polysiphonia japonica, 5-Bromoprotocatechualdehyde (BPCA), is considered as a potential compound for the protection of β-cells. In this study, we examined palmitate (PA)-induced lipotoxicity in Ins-1 cells to test the protective effects of BPCA on insulin-secreting β-cells. Our results demonstrated that BPCA can protect β-cells from PA-induced lipotoxicity by reducing cellular damage, preventing reactive oxygen species (ROS) overproduction, and enhancing glucose-stimulated insulin secretion (GSIS). BPCA also improved mitochondrial morphology by preserving parkin protein expression. Moreover, BPCA exhibited a protective effect against PA-induced β-cell dysfunction in vivo in a zebrafish model. Our results provide strong evidence that BPCA could be a potential therapeutic agent for the management of diabetes.

scholarly journals NF-κB activity during pancreas development regulates adult β-cell mass by modulating neonatal β-cell proliferation and apoptosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dror Sever ◽  
Anat Hershko-Moshe ◽  
Rohit Srivastava ◽  
Roy Eldor ◽  
Daniel Hibsher ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Developmental Stages ◽  
Cell Mass ◽  
Diabetes Incidence ◽  
Β Cells ◽  
Β Cell ◽  
Cell Dysfunction ◽  
Regulatory Circuit ◽  
Proliferation And Apoptosis

AbstractNF-κB is a well-characterized transcription factor, widely known for its roles in inflammation and immune responses, as well as in control of cell division and apoptosis. However, its function in β-cells is still being debated, as it appears to depend on the timing and kinetics of its activation. To elucidate the temporal role of NF-κB in vivo, we have generated two transgenic mouse models, the ToIβ and NOD/ToIβ mice, in which NF-κB activation is specifically and conditionally inhibited in β-cells. In this study, we present a novel function of the canonical NF-κB pathway during murine islet β-cell development. Interestingly, inhibiting the NF-κB pathway in β-cells during embryogenesis, but not after birth, in both ToIβ and NOD/ToIβ mice, increased β-cell turnover, ultimately resulting in a reduced β-cell mass. On the NOD background, this was associated with a marked increase in insulitis and diabetes incidence. While a robust nuclear immunoreactivity of the NF-κB p65-subunit was found in neonatal β-cells, significant activation was not detected in β-cells of either adult NOD/ToIβ mice or in the pancreata of recently diagnosed adult T1D patients. Moreover, in NOD/ToIβ mice, inhibiting NF-κB post-weaning had no effect on the development of diabetes or β-cell dysfunction. In conclusion, our data point to NF-κB as an important component of the physiological regulatory circuit that controls the balance of β-cell proliferation and apoptosis in the early developmental stages of insulin-producing cells, thus modulating β-cell mass and the development of diabetes in the mouse model of T1D.

scholarly journals Increased vimentin in human α- and β-cells in type 2 diabetes

2017 ◽  
Vol 233 (3) ◽  
pp. 217-227 ◽  
Author(s):  
Maaike M Roefs ◽  
Françoise Carlotti ◽  
Katherine Jones ◽  
Hannah Wills ◽  
Alexander Hamilton ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Epithelial To Mesenchymal Transition ◽  
Islet Cells ◽  
Cell Types ◽  
Β Cells ◽  
Β Cell ◽  
Mesenchymal Transition ◽  
Cell Expression

Type 2 diabetes (T2DM) is associated with pancreatic islet dysfunction. Loss of β-cell identity has been implicated via dedifferentiation or conversion to other pancreatic endocrine cell types. How these transitions contribute to the onset and progression of T2DM in vivo is unknown. The aims of this study were to determine the degree of epithelial-to-mesenchymal transition occurring in α and β cells in vivo and to relate this to diabetes-associated (patho)physiological conditions. The proportion of islet cells expressing the mesenchymal marker vimentin was determined by immunohistochemistry and quantitative morphometry in specimens of pancreas from human donors with T2DM (n = 28) and without diabetes (ND, n = 38) and in non-human primates at different stages of the diabetic syndrome: normoglycaemic (ND, n = 4), obese, hyperinsulinaemic (HI, n = 4) and hyperglycaemic (DM, n = 8). Vimentin co-localised more frequently with glucagon (α-cells) than with insulin (β-cells) in the human ND group (1.43% total α-cells, 0.98% total β-cells, median; P < 0.05); these proportions were higher in T2DM than ND (median 4.53% α-, 2.53% β-cells; P < 0.05). Vimentin-positive β-cells were not apoptotic, had reduced expression of Nkx6.1 and Pdx1, and were not associated with islet amyloidosis or with bihormonal expression (insulin + glucagon). In non-human primates, vimentin-positive β-cell proportion was larger in the diabetic than the ND group (6.85 vs 0.50%, medians respectively, P < 0.05), but was similar in ND and HI groups. In conclusion, islet cell expression of vimentin indicates a degree of plasticity and dedifferentiation with potential loss of cellular identity in diabetes. This could contribute to α- and β-cell dysfunction in T2DM.

scholarly journals Suppression of Peroxisome Proliferator-Activated Receptor γ-Coactivator-1α Normalizes the Glucolipotoxicity-Induced Decreased BETA2/NeuroD Gene Transcription and Improved Glucose Tolerance in Diabetic Rats

Endocrinology ◽  
2009 ◽  
Vol 150 (9) ◽  
pp. 4074-4083 ◽  
Author(s):  
Ji-Won Kim ◽  
Young-Hye You ◽  
Dong-Sik Ham ◽  
Jae-Hyoung Cho ◽  
Seung-Hyun Ko ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Receptor Site ◽  
Diabetic Rats ◽  
Peroxisome Proliferator ◽  
Β Cells ◽  
Β Cell ◽  
Peroxisome Proliferator Activated Receptor ◽  
Cell Dysfunction

Abstract Peroxisome proliferator-activated receptor γ-coactivator-1α (PGC-1α) is significantly elevated in the islets of animal models of diabetes. However, the molecular mechanism has not been clarified. We investigated whether the suppression of PGC-1α expression protects against β-cell dysfunction in vivo and determined the mechanism of action of PGC-1α in β-cells. The studies were performed in glucolipotixicity-induced primary rat islets and INS-1 cells. In vitro and in vivo approaches using adenoviruses were used to evaluate the role of PGC-1α in glucolipotoxicity-associated β-cell dysfunction. The expression of PGC-1α in cultured β-cells increased gradually with glucolipotoxicity. The overexpression of PGC-1α also suppressed the expression of the insulin and β-cell E-box transcription factor (BETA2/NeuroD) genes, which was reversed by PGC-1α small interfering RNA (siRNA). BETA2/NeuroD, p300-enhanced BETA2/NeuroD, and insulin transcriptional activities were significantly suppressed by Ad-PGC-1α but were rescued by Ad-siPGC-1α. PGC-1α binding at the glucocorticoid receptor site on the BETA2/NeuroD promoter increased in the presence of PGC-1α. Ad-siPGC-1α injection through the celiac arteries of 90% pancreatectomized diabetic rats improved their glucose tolerance and maintained their fasting insulin levels. The suppression of PGC-1α expression protects the glucolipotoxicity-induced β-cell dysfunction in vivo and in vitro. A better understanding of the functions of molecules such as PGC-1α, which play key roles in intracellular fuel regulation, could herald a new era of the treatment of patients with type 2 diabetes mellitus by providing protection from glucolipotoxicity, which is an important cause of the development and progression of the disease.

scholarly journals METABOLIC PHENOTYPING GUIDELINES: Assessing glucose homeostasis in rodent models

2014 ◽  
Vol 222 (3) ◽  
pp. G13-G25 ◽  
Author(s):  
James E Bowe ◽  
Zara J Franklin ◽  
Astrid C Hauge-Evans ◽  
Aileen J King ◽  
Shanta J Persaud ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Glucose Tolerance ◽  
Glucose Homeostasis ◽  
Β Cells ◽  
Advantages And Disadvantages ◽  
Autoimmune Destruction ◽  
Normal Glucose

The pathophysiology of diabetes as a disease is characterised by an inability to maintain normal glucose homeostasis. In type 1 diabetes, this is due to autoimmune destruction of the pancreatic β-cells and subsequent lack of insulin production, and in type 2 diabetes it is due to a combination of both insulin resistance and an inability of the β-cells to compensate adequately with increased insulin release. Animal models, in particular genetically modified mice, are increasingly being used to elucidate the mechanisms underlying both type 1 and type 2 diabetes, and as such the ability to study glucose homeostasisin vivohas become an essential tool. Several techniques exist for measuring different aspects of glucose tolerance and each of these methods has distinct advantages and disadvantages. Thus the appropriate methodology may vary from study to study depending on the desired end-points, the animal model, and other practical considerations. This review outlines the most commonly used techniques for assessing glucose tolerance in rodents and details the factors that should be taken into account in their use. Representative scenarios illustrating some of the practical considerations of designingin vivoexperiments for the measurement of glucose homeostasis are also discussed.

scholarly journals Expression Pattern of 12-Lipoxygenase in Human Islets With Type 1 Diabetes and Type 2 Diabetes

2015 ◽  
Vol 100 (3) ◽  
pp. E387-E395 ◽  
Author(s):  
Wojciech J. Grzesik ◽  
Joseph L. Nadler ◽  
Yui Machida ◽  
Jerry L. Nadler ◽  
Yumi Imai ◽  
...  
Keyword(s):  
Outcome Measure ◽  
Islet Cells ◽  
Human Islets ◽  
Β Cells ◽  
Β Cell ◽  
Diabetes Development ◽  
12 Lipoxygenase ◽  
Type 2 Diabetic

Context: Inflammation in the pancreas can cause β-cell stress, leading to diabetes development. Access to human pancreas tissues via the Network for Pancreatic Organ Donors with Diabetes (nPOD) has allowed characterization of pathways leading to this inflammation. Objective: 12-Lipoxygenase (12-LO) induces inflammation and has been implicated in diabetes development. Our goal was to determine expression of 12-LO in human islets from control, autoantibody-positive, type 1 diabetic, and type 2 diabetic nPOD pancreas donors. Design: Pancreas tissues from nPOD donors were examined by immunohistochemistry and immunofluorescence for islet expression of 12-LO in different subsets of islet cells. Participants: Donor pancreas samples were obtained from nPOD based on disease status (control, n = 7; autoantibody-positive, n = 8; type 1 diabetic, n = 17; or type 2 diabetic donors, n = 15). Main Outcome Measure: Determination of 12-LO expression within human islets served as the main outcome measure, including distinguishing which types of islet cells expressed 12-LO. Results: Islets from control participants (nondiabetic) lacked islet expression of 12-LO. Of donors in the other groups, 25% to 37% expressed islet 12-LO with a clear inverse relation between the numbers of β-cells and 12-LO+ cells within islets of 12-LO+ cases. 12-LO expression was not seen within macrophages, endothelial cells, α-cells, or β-cells, but only within cells expressing low levels of pancreatic polypeptide (PP) and increased levels of vimentin. Conclusions: 12-LO expression colocalizes within a specific type of islet PP+ cell under prediabetic and diabetic conditions. The costaining of PP and vimentin suggests that 12-LO participates in the process leading to β-cell dedifferentiation in the islet.

scholarly journals Regenerative Medicine for Diabetes Mellitus

2009 ◽  
Vol 18 (5-6) ◽  
pp. 491-496 ◽  
Author(s):  
Naoya Kobayashi ◽  
Takeshi Yuasa ◽  
Teru Okitsu
Keyword(s):  
Regenerative Medicine ◽  
The Body ◽  
Definitive Treatment ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Living Body

In diabetes, a loss of pancreatic β-cells causes insulin dependency. When insulin dependency is caused by type 1 diabetes or pancreatic diabetes, for example, pancreatic β-cells need to be regenerated for definitive treatment. The methods for generating pancreatic β-cells include a method of creating pancreatic β-cells in vitro and implanting them into the body and a method of regenerating pancreatic β-cells in the body via gene introduction or the administration of differential proliferation factors to the body. Moreover, the number of pancreatic β-cells is also low in type 2 diabetes, caused by the compounding factors of insulin secretory failure and insulin resistance; therefore, if pancreatic β-cells can be regenerated in a living body, then a further amelioration of the pathology can be expected. The development of pancreatic β-cell-targeting regenerative medicine can lead to the next generation of diabetes treatment.

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