Evidence for voltage-dependent Cl− permeability in mouse pancreatic β-cells

In the present study, we examined the ability of adenosine 3′,5′-cyclic monophosphate (cAMP) to reduce elevated levels of cytosolic Ca2+ concentration ([Ca2+]i) in pancreatic β-cells. [Ca2+]iand reduced pyridine nucleotide, NAD(P)H, were measured in rat single β-cells by fura 2 and autofluorescence microfluorometry. Sustained [Ca2+]ielevation, induced by high KCl (25 mM) at a basal glucose concentration (2.8 mM), was substantially reduced by cAMP-increasing agents, dibutyryl cAMP (DBcAMP, 5 mM), an adenylyl cyclase activator forskolin (10 μM), and an incretin glucagon-like peptide-1-(7–36) amide (10−9 M), as well as by glucose (16.7 mM). The [Ca2+]i-reducing effects of cAMP were greater at elevated glucose (8.3–16.7 mM) than at basal glucose (2.8 mM). An inhibitor of protein kinase A (PKA), H-89, counteracted [Ca2+]i-reducing effects of cAMP but not those of glucose. Okadaic acid, a phosphatase inhibitor, at 10–100 nM also reduced sustained [Ca2+]ielevation in a concentration-dependent manner. Glucose, but not DBcAMP, increased NAD(P)H in β-cells. [Ca2+]i-reducing effects of cAMP were inhibited by 0.3 μM thapsigargin, an inhibitor of the endoplasmic reticulum (ER) Ca2+ pump. In contrast, [Ca2+]i-reducing effects of cAMP were not altered by ryanodine, an ER Ca2+-release inhibitor, Na+-free conditions, or diazoxide, an ATP-sensitive K+ channel opener. In conclusion, the cAMP-PKA pathway reduces [Ca2+]ielevation by sequestering Ca2+ in thapsigargin-sensitive stores. This process does not involve, but is potentiated by, activation of β-cell metabolism. Together with the known [Ca2+]i-increasing action of cAMP, our results reveal dual regulation of β-cell [Ca2+]iby the cAMP-signaling pathway and by a physiological incretin.

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Cyanidin-3-rutinoside protects INS-1 pancreatic β cells against high glucose-induced glucotoxicity by apoptosis

Zeitschrift für Naturforschung C ◽

10.1515/znc-2017-0172 ◽

2018 ◽

Vol 73 (7-8) ◽

pp. 281-289 ◽

Cited By ~ 1

Author(s):

Kung-Ha Choi ◽

Mi Hwa Park ◽

Hyun Ah Lee ◽

Ji-Sook Han

Keyword(s):

Cell Death ◽

High Glucose ◽

Cell Damage ◽

Therapeutic Effects ◽

Dependent Manner ◽

Pancreatic Β Cell ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells ◽

Induced Apoptosis

Abstract Exposure to high levels of glucose may cause glucotoxicity, leading to pancreatic β cell dysfunction, including cell apoptosis and impaired glucose-stimulated insulin secretion. The aim of this study was to explore the effect of cyanidin-3-rutinoside (C3R), a derivative of anthocyanin, on glucotoxicity-induced apoptosis in INS-1 pancreatic β cells. Glucose (30 mM) treatment induced INS-1 pancreatic β cell death, but glucotoxicity and apoptosis significantly decreased in cells treated with 50 μM C3R compared to that observed in 30 mM glucose-treated cells. Furthermore, hyperglycemia increased intracellular reactive oxygen species (ROS), lipid peroxidation, and nitric oxide (NO) levels, while C3R treatment reduced these in a dose-dependent manner. C3R also increased the activity of antioxidant enzymes, markedly reduced the expression of pro-apoptotic proteins (such as Bax, cytochrome c, caspase 9 and caspase 3), and increased the expression of the anti-apoptotic protein, Bcl-2, in hyperglycemia-exposed cells. Finally, cell death was examined using annexin V/propidium iodide staining, which revealed that C3R significantly reduced high glucose-induced apoptosis. In conclusion, C3R may have therapeutic effects against hyperglycemia-induced β cell damage in diabetes.

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Cavβ3 regulates Ca2+-signalling and insulin expression in pancreatic β-cells in a cell-autonomous manner

10.2337/figshare.15173556 ◽

2021 ◽

Author(s):

Alexander Becker ◽

Barbara Wardas ◽

Houssein Salah ◽

Maryam Amini ◽

Claudia Fecher‐Trost ◽

...

Keyword(s):

Protein Profiling ◽

Dependent Manner ◽

Ip3 Receptor ◽

Β Cells ◽

Pancreatic Β Cells ◽

Concentration Dependent Manner ◽

Insulin Expression ◽

Low Concentrations ◽

A Cell ◽

Nitric Oxide Synthase 1

Voltage-gated Ca2+ (Cav) channels consist of a pore-forming Cavα1 subunit and auxiliary Cavα2-δ and Cavβ subunits. In fibroblasts, Cavβ3, independent of its role as a Cav subunit, reduces the sensitivity to low concentrations of inositol-1,4,5-trisphosphate (IP3). Similarly, Cavβ3 could affect cytosolic [Ca2+] in pancreatic β-cells. Here, we deleted the Cavβ3-encoding gene Cacnb3 in insulin-secreting rat β-(Ins-1) cells using CRISPR/Cas9. These cells were used as controls to investigate the role of Cavβ3 on Ca2+-signalling, glucose-induced insulin secretion (GIIS), Cav-channel activity and gene expression in wild-type cells in which Cavβ3 and the IP3-receptor were co-immunoprecipitated. Transcript and protein profiling revealed significantly increased levels of insulin transcription factor Mafa, CaMKIV, neuroendocrine convertase1 (Pcsk1) and nitric oxide synthase-1 (NOS-1) in Cavβ3-KO cells. In the absence of Cavβ3, Cav-currents were not altered. In contrast, CREB activity, the amount of MAFA protein and GIIS, the extent of IP3-dependent Ca2+ release and the frequency of Ca2+-oscillations were increased. These processes were decreased by the Cavβ3 protein in a concentration-dependent manner. Our study shows that Cavβ3 interacts with the IP3-receptor in isolated β-cells, controls IP3-dependent Ca2+-signalling independently of Cav channel functions, and thereby regulates insulin expression and its glucose-dependent release in a cell-autonomous manner.

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Overexpression of the Coactivator Bridge-1 Results in Insulin Deficiency and Diabetes

Molecular Endocrinology ◽

10.1210/me.2005-0127 ◽

2006 ◽

Vol 20 (1) ◽

pp. 167-182 ◽

Cited By ~ 12

Author(s):

Jamie L. Volinic ◽

Jee H. Lee ◽

Kazuhiro Eto ◽

Varinderpal Kaur ◽

Melissa K. Thomas

Keyword(s):

Transcription Factors ◽

Pancreatic Islet ◽

Pdz Domain ◽

Insulin Gene ◽

Dependent Manner ◽

Pancreatic Β Cell ◽

Insulin Deficiency ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells

Abstract Multiple forms of heritable diabetes are associated with mutations in transcription factors that regulate insulin gene transcription and the development and maintenance of pancreatic β-cell mass. The coactivator Bridge-1 (PSMD9) regulates the transcriptional activation of glucose-responsive enhancers in the insulin gene in a dose-dependent manner via PDZ domain-mediated interactions with E2A transcription factors. Here we report that the pancreatic overexpression of Bridge-1 in transgenic mice reduces insulin gene expression and results in insulin deficiency and severe diabetes. Dysregulation of Bridge-1 signaling increases pancreatic apoptosis with a reduction in the number of insulin-expressing pancreatic β-cells and an expansion of the complement of glucagon-expressing pancreatic α-cells in pancreatic islets. Increased expression of Bridge-1 alters pancreatic islet, acinar, and ductal architecture and disrupts the boundaries between endocrine and exocrine cellular compartments in young adult but not neonatal mice, suggesting that signals transduced through this coactivator may influence postnatal pancreatic islet morphogenesis. Signals mediated through the coactivator Bridge-1 may regulate both glucose homeostasis and pancreatic β-cell survival. We propose that coactivator dysfunction in pancreatic β-cells can limit insulin production and contribute to the pathogenesis of diabetes.

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Peroxiredoxin III protects pancreatic β cells from apoptosis

Journal of Endocrinology ◽

10.1677/joe-09-0455 ◽

2010 ◽

Vol 207 (2) ◽

pp. 163-175 ◽

Cited By ~ 39

Author(s):

Gabriele Wolf ◽

Nicole Aumann ◽

Marta Michalska ◽

Antje Bast ◽

Jürgen Sonnemann ◽

...

Keyword(s):

Diabetes Mellitus ◽

Nitrosative Stress ◽

Focal Point ◽

Dependent Diabetes Mellitus ◽

Dependent Manner ◽

Cell Protection ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells ◽

Insulinoma Cells

Type 1 diabetes mellitus is characterized by a progressive autoimmune destruction of insulin-producing β cells. Macrophages and T lymphocytes release cytokines, which induce the synthesis of oxygen and nitrogen radicals in the pancreatic islets. The resulting cellular and mitochondrial damage promotes β cell death. β cells are very sensitive to the autoimmune free radical-dependent attack due to their low content of antioxidant enzymes such as glutathione peroxidase and catalase. A focal point of β cell protection should be the control of the mitochondrial redox status, which will result in the preservation of metabolic stimulus-secretion coupling. For this reason, there is a considerable interest in the mitochondrial peroxiredoxin III (PRX III), a thioredoxin-dependent peroxide reductase, which was shown to be able to protect against both oxidative and nitrosative stress. Using the Tet-On-system, we generated stably transfected rat insulinoma cells over- or under-expressing PRX III in a doxycyclin-dependent manner to analyze the effect of increased or decreased amounts of cellular PRX III, following treatment with several stressors. We provide evidence that PRX III protects pancreatic β cells from cell stress induced by accumulation of hydrogen peroxide, or the induction of inducible nitric oxide synthase or caspase-9 and -3 by pro-inflammatory cytokines or streptozotocin. Basal insulin secretion was markedly decreased in cells expressing lower levels of PRX III. We suggest PRX III may be a suitable target for promoting deceleration or even prevention of stress-associated apoptosis in pancreatic β cells and the manifestation of insulin-dependent diabetes mellitus.

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Sphingosine 1-phosphate Stimulates Insulin Secretion and Improves Cell Survival by Blocking Voltage-dependent K+ Channels in β Cells

Frontiers in Pharmacology ◽

10.3389/fphar.2021.683674 ◽

2021 ◽

Vol 12 ◽

Author(s):

Zhihong Liu ◽

Huanhuan Yang ◽

Linping Zhi ◽

Huan Xue ◽

Zhihong Lu ◽

...

Keyword(s):

Insulin Secretion ◽

Cell Survival ◽

Dependent Manner ◽

Β Cells ◽

Β Cell ◽

Kv Channels ◽

Channel Inhibition ◽

Voltage Dependent ◽

Sphingosine 1 Phosphate ◽

Intracellular Ca

Recent studies suggest that Sphingosine 1-phosphate (S1P) plays an important role in regulating glucose metabolism in type 2 diabetes. However, its effects and mechanisms of promoting insulin secretion remain largely unknown. Here, we found that S1P treatment decreased blood glucose level and increased insulin secretion in C57BL/6 mice. Our results further showed that S1P promoted insulin secretion in a glucose-dependent manner. This stimulatory effect of S1P appeared to be irrelevant to cyclic adenosine monophosphate signaling. Voltage-clamp recordings showed that S1P did not influence voltage-dependent Ca2+ channels, but significantly blocked voltage-dependent potassium (Kv) channels, which could be reversed by inhibition of phospholipase C (PLC) and protein kinase C (PKC). Calcium imaging revealed that S1P increased intracellular Ca2+ levels, mainly by promoting Ca2+ influx, rather than mobilizing intracellular Ca2+ stores. In addition, inhibition of PLC and PKC suppressed S1P-induced insulin secretion. Collectively, these results suggest that the effects of S1P on glucose-stimulated insulin secretion (GSIS) depend on the inhibition of Kv channels via the PLC/PKC signaling pathway in pancreatic β cells. Further, S1P improved β cell survival; this effect was also associated with Kv channel inhibition. This work thus provides new insights into the mechanisms whereby S1P regulates β cell function in diabetes.

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SAT-715 Bisphenol-A Alters Pancreatic B-Cell Proliferation and Mass in an Estrogen Receptor Beta-Dependent Manner

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.791 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Angel Nadal ◽

Talia Boronat-Belda ◽

Ivan Quesada ◽

Esther Fuentes ◽

Jan-Ake Gustafsson ◽

...

Keyword(s):

Cell Proliferation ◽

Cell Division ◽

Ex Vivo ◽

Cell Mass ◽

Dependent Manner ◽

Pancreatic Β Cell ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells ◽

Male And Female

Abstract Bisphenol-A (BPA) is one of the highest volume chemicals produced worldwide. It is used as the base compound in the manufacture of polycarbonate plastics, epoxies and resins. Humans are consistently exposed to BPA and consistently it has been detected in the majority of individuals examined. Experimental research in animals, as well as human epidemiological studies, converge to conclude that BPA is a risk factor for the development of type 2 diabetes. In previous studies we have demonstrated that the exposure to BPA during embryonic development promote an increment of pancreatic β-cell mass. This was correlated with increased β-cell division and altered global gene expression in pancreatic β-cells. The aim of this work was to determinate whether ERβ was involved in the in the β-cell mass and proliferation increment observed in male mice offspring. ERβ+/- pregnant mice were treated with vehicle or BPA (10 μg/kg/day) from day 9 to 16 of gestation. Offspring pancreatic β-cell mass was measured at postnatal day 0 (P0) and 30 (P30). For ex vivo experiments Wild-type (WT) and ERβ-/- neonates as well as adult male and female mice were used. For in vitro, single islets cells were cultured for 48 h in the presence of 10 μmol/L BrdU, and vehicle, BPA (1, 10, 100 nM) or the specific ERβ agonist WAY200070 (1, 10, 100 nM). β-cell proliferation rate was quantified as the percentage of BrdU-positive pancreatic β-cells. In vivo exposure to BPA during pregnancy promoted an increment of pancreatic β-cell mass and proliferation in WT mice at P30 which was absent in ERβ -/- mice. In order to explore if these changes were related to a direct action of BPA on pancreatic β-cell division we performed a series of ex vivo experiments. Augmented β-cell proliferation rate was observed in BPA-exposed β-cells isolated from both adult male and female WT animals in comparison to controls. The increment was significant at all BPA doses tested. The effect was imitated by the selective ERβ agonist, WAY200070, and was abolished in cells from ERβ-/- mice. We also explored the effects of BPA in pancreatic β-cells from neonates and found an increment in BPA-exposed cells compared to controls, although the difference was only significant at the dose of 1 nM. A similar effect was observed in neonate cells treated with WAY200070 (10 nM). The effects on β-cell replication were abolished in cells from ERβ-/- neonate mice treated either with BPA or WAY200070. Our findings suggest that BPA modulate pancreatic β-cell growth and mass in an ERβ-dependent manner. This could have important implications for metabolic programming of T2DM. Ministerio de Economía y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) grants BPU2017-86579-R (AN) and BFU2016-77125-R (IQ); Generalitat Valenciana PROMETEO II/2015/016 (AN). CIBERDEM is an initiative of the Instituto de Salud Carlos III.

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Cavβ3 regulates Ca2+-signalling and insulin expression in pancreatic β-cells in a cell-autonomous manner

10.2337/figshare.15173556.v1 ◽

2021 ◽

Author(s):

Alexander Becker ◽

Barbara Wardas ◽

Houssein Salah ◽

Maryam Amini ◽

Claudia Fecher‐Trost ◽

...

Keyword(s):

Protein Profiling ◽

Dependent Manner ◽

Ip3 Receptor ◽

Β Cells ◽

Pancreatic Β Cells ◽

Concentration Dependent Manner ◽

Insulin Expression ◽

Low Concentrations ◽

A Cell ◽

Nitric Oxide Synthase 1

Voltage-gated Ca2+ (Cav) channels consist of a pore-forming Cavα1 subunit and auxiliary Cavα2-δ and Cavβ subunits. In fibroblasts, Cavβ3, independent of its role as a Cav subunit, reduces the sensitivity to low concentrations of inositol-1,4,5-trisphosphate (IP3). Similarly, Cavβ3 could affect cytosolic [Ca2+] in pancreatic β-cells. Here, we deleted the Cavβ3-encoding gene Cacnb3 in insulin-secreting rat β-(Ins-1) cells using CRISPR/Cas9. These cells were used as controls to investigate the role of Cavβ3 on Ca2+-signalling, glucose-induced insulin secretion (GIIS), Cav-channel activity and gene expression in wild-type cells in which Cavβ3 and the IP3-receptor were co-immunoprecipitated. Transcript and protein profiling revealed significantly increased levels of insulin transcription factor Mafa, CaMKIV, neuroendocrine convertase1 (Pcsk1) and nitric oxide synthase-1 (NOS-1) in Cavβ3-KO cells. In the absence of Cavβ3, Cav-currents were not altered. In contrast, CREB activity, the amount of MAFA protein and GIIS, the extent of IP3-dependent Ca2+ release and the frequency of Ca2+-oscillations were increased. These processes were decreased by the Cavβ3 protein in a concentration-dependent manner. Our study shows that Cavβ3 interacts with the IP3-receptor in isolated β-cells, controls IP3-dependent Ca2+-signalling independently of Cav channel functions, and thereby regulates insulin expression and its glucose-dependent release in a cell-autonomous manner.

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Autocrine IGF2 programmes β-cell plasticity under conditions of increased metabolic demand

Scientific Reports ◽

10.1038/s41598-021-87292-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ionel Sandovici ◽

Constanze M. Hammerle ◽

Sam Virtue ◽

Yurena Vivas-Garcia ◽

Adriana Izquierdo-Lahuerta ◽

...

Keyword(s):

Insulin Resistance ◽

Glucose Homeostasis ◽

Association Studies ◽

Susceptibility Gene ◽

Chow Diet ◽

Genome Wide Association Studies ◽

Cell Plasticity ◽

Β Cells ◽

Β Cell ◽

Pancreatic Β Cells

AbstractWhen exposed to nutrient excess and insulin resistance, pancreatic β-cells undergo adaptive changes in order to maintain glucose homeostasis. The role that growth control genes, highly expressed in early pancreas development, might exert in programming β-cell plasticity in later life is a poorly studied area. The imprinted Igf2 (insulin-like growth factor 2) gene is highly transcribed during early life and has been identified in recent genome-wide association studies as a type 2 diabetes susceptibility gene in humans. Hence, here we investigate the long-term phenotypic metabolic consequences of conditional Igf2 deletion in pancreatic β-cells (Igf2βKO) in mice. We show that autocrine actions of IGF2 are not critical for β-cell development, or for the early post-natal wave of β-cell remodelling. Additionally, adult Igf2βKO mice maintain glucose homeostasis when fed a chow diet. However, pregnant Igf2βKO females become hyperglycemic and hyperinsulinemic, and their conceptuses exhibit hyperinsulinemia and placentomegalia. Insulin resistance induced by congenital leptin deficiency also renders Igf2βKO females more hyperglycaemic compared to leptin-deficient controls. Upon high-fat diet feeding, Igf2βKO females are less susceptible to develop insulin resistance. Based on these findings, we conclude that in female mice, autocrine actions of β-cell IGF2 during early development determine their adaptive capacity in adult life.

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The association of insulinemic potential of diet and lifestyle with the risk of insulin-related disorders: a prospective cohort study among participants of Tehran Lipid and Glucose Study

Diabetology & Metabolic Syndrome ◽

10.1186/s13098-021-00674-z ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Ebrahim Mokhtari ◽

Hossein Farhadnejad ◽

Farshad Teymoori ◽

Parvin Mirmiran ◽

Fereidoun Azizi

Keyword(s):

Insulin Resistance ◽

Dietary Intakes ◽

Β Cells ◽

Β Cell ◽

Food Frequency ◽

Cell Dysfunction ◽

The Mean ◽

Diet And Lifestyle ◽

Activity Information ◽

Insulin Insensitivity

Abstract Background We aim to assess the association of empirical dietary (EDIH) and lifestyle (ELIH) index for hyperinsulinemia with the risk of insulin resistance, hyperinsulinemia, insulin sensitivity, and β-cell dysfunction in Iranian adults. Methods In this prospective study, a total of 1244 men and women aged ≥ 20 years were selected among participants of the Tehran lipid and glucose study and followed for 3.2 years. Dietary intakes were assessed using a valid semi-quantitative food frequency questionnaire. Dietary and lifestyle insulinemic potential indices were calculated using dietary intake, body mass index, and physical activity information. Multivariable logistic regression was used to estimate the associated risk of a 3-year incidence of insulin-related disorders. Results The mean ± SD age and BMI of all eligible participants (42.7% males) were 43.0 ± 13.0 and 27.4 ± 4.9 in the study's baseline. After adjusting for all potential confounders, participants in the highest tertile of ELIH score had a greater risk of developing hyperinsulinemia (OR:2.42, 95%CI:1.52–3.86, P for trend = < 0.001), insulin resistance (OR:2.71, 95%CI:1.75–4.18, P for trend = < 0.001) and insulin insensitivity (OR:2.65, 95%CI: 1.72–4.10, P for trend = < 0.001) compared with those in the lowest tertile. However, the risk of incident β-cell dysfunction was lower in individuals with a higher score of ELIH in comparison to those with the lowest score (OR:0.30, 95%CI:0.19–0.45, P for trend = < 0.001). Conclusions Empirical lifestyle index for hyperinsulinemia was directly associated with insulin resistance, insulin insensitivity, and hyperinsulinemia and was inversely associated with β-cells dysfunction.

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