Synchronized Microfluidic System to Dynamically Assess Pancreatic Islet Function beyond Glucose-Stimulated Insulin Secretion

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 2162-P
Author(s):  
STEPHAN NIEUWOUDT ◽  
RUTH MCDOWELL ◽  
HUI ZHANG ◽  
JOHN P. KIRWAN
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islet ◽  
Microfluidic System ◽  
Islet Function ◽  
Glucose Stimulated Insulin Secretion

scholarly journals Chromomycin A2 potently inhibits glucose-stimulated insulin secretion from pancreatic β cells

2018 ◽  
Author(s):  
Michael A Kalwat ◽  
In Hyun Hwang ◽  
Jocelyn Macho ◽  
Magdalena G Grzemska ◽  
Jonathan Z Yang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Natural Product ◽  
Pancreatic Islet ◽  
Islet Function ◽  
Gene Promoters ◽  
Β Cells ◽  
Β Cell ◽  
Regulatory Pathways ◽  
Glucose Stimulated Insulin Secretion ◽  
Cell Gene

ABSTRACTEnhancers or inhibitors of insulin secretion could become therapeutics as well as lead to the identification of requisite β-cell regulatory pathways and increase our understanding of pancreatic islet function. Toward this goal, we previously used an insulin-linked luciferase that is co-secreted with insulin in MIN6 β-cells to perform a high-throughput natural product screen for chronic effects on glucose-stimulated insulin secretion. Using multiple phenotypic analyses, we identified that one of the top natural product hits, chromomycin A2 (CMA2), potently inhibited insulin secretion through at least three mechanisms: disruption of Wnt signaling, interfering with β-cell gene expression, and suppression of triggering calcium (Ca2+) influx. Chronic treatment with CMA2 largely ablated glucose-stimulated insulin secretion even post-washout, but did not inhibit glucose-stimulated generation of ATP or Ca2+ influx. However, by using the KATP channel-opener diazoxide, we uncovered defects in depolarization-induced Ca2+ influx which may contribute to the suppressed secretory response. Glucose-responsive ERK1/2 and S6 phosphorylation were also disrupted by chronic CMA2 treatment. The FUSION bioinformatic database indicated that the phenotypic effects of CMA2 clustered with a number of Wnt/GSK3 pathway-related genes. Consistently, CMA2 decreased GSK3 phosphorylation and suppressed activation of a β-catenin activity reporter. CMA2 and a related compound mithramycin are described to have DNA-interaction properties, possibly abrogating transcription factor binding to critical β-cell gene promoters. We observed that CMA2, but not mithramycin, suppressed expression of PDX1 and UCN3. However, neither expression of INSI/II nor insulin content was affected by chronic CMA2. The mechanisms of CMA2-induced insulin secretion defects may involve components both proximal and distal to Ca2+ influx. Therefore, CMA2 is an example of a chemical that can simultaneously disrupt β-cell function through both non-cytotoxic and cytotoxic mechanisms. Future applications of CMA2 and similar aureolic acid analogs for disease therapies should consider the potential impacts on pancreatic islet function.

scholarly journals Chromomycin A2 potently inhibits glucose-stimulated insulin secretion from pancreatic β cells

2018 ◽  
Vol 150 (12) ◽  
pp. 1747-1757 ◽  
Author(s):  
Michael A. Kalwat ◽  
In Hyun Hwang ◽  
Jocelyn Macho ◽  
Magdalena G. Grzemska ◽  
Jonathan Z. Yang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islet ◽  
Cell Function ◽  
Islet Function ◽  
Gene Promoters ◽  
Β Cells ◽  
Β Cell ◽  
Regulatory Pathways ◽  
Glucose Stimulated Insulin Secretion ◽  
Cell Gene

Modulators of insulin secretion could be used to treat diabetes and as tools to investigate β cell regulatory pathways in order to increase our understanding of pancreatic islet function. Toward this goal, we previously used an insulin-linked luciferase that is cosecreted with insulin in MIN6 β cells to perform a high-throughput screen of natural products for chronic effects on glucose-stimulated insulin secretion. In this study, using multiple phenotypic analyses, we found that one of the top natural product hits, chromomycin A2 (CMA2), potently inhibited insulin secretion by at least three potential mechanisms: disruption of Wnt signaling, interference of β cell gene expression, and partial suppression of Ca2+ influx. Chronic treatment with CMA2 largely ablated glucose-stimulated insulin secretion even after washout, but it did not inhibit glucose-stimulated generation of ATP or Ca2+ influx. However, by using the KATP channel opener diazoxide, we uncovered defects in depolarization-induced Ca2+ influx that may contribute to the suppressed secretory response. Glucose-responsive ERK1/2 and S6 phosphorylation were also disrupted by chronic CMA2 treatment. By querying the FUSION bioinformatic database, we revealed that the phenotypic effects of CMA2 cluster with a number of Wnt–GSK3 pathway-related genes. Furthermore, CMA2 consistently decreased GSK3β phosphorylation and suppressed activation of a β-catenin activity reporter. CMA2 and a related compound, mithramycin, are known to have DNA interaction properties, possibly abrogating transcription factor binding to critical β cell gene promoters. We observed that CMA2 but not mithramycin suppressed expression of PDX1 and UCN3. However, neither expression of INSI/II nor insulin content was affected by chronic CMA2. The mechanisms of CMA2-induced insulin secretion defects may involve components both proximal and distal to Ca2+ influx. Therefore, CMA2 is an example of a chemical that can simultaneously disrupt β cell function through both noncytotoxic and cytotoxic mechanisms. Future therapeutic applications of CMA2 and similar aureolic acid analogues should consider their potential effects on pancreatic islet function.

Vitamin D and pancreatic islet function I. Time course for changes in insulin secretion and content during vitamin D deprivation and repletion

1988 ◽  
Vol 11 (8) ◽  
pp. 577-584 ◽  
Author(s):  
H. Labriji-Mestaghanmi ◽  
B. Billaudel ◽  
P. E. Garnier ◽  
W. J. Malaisse ◽  
B. C. J. Sutter
Keyword(s):  
Vitamin D ◽  
Insulin Secretion ◽  
Pancreatic Islet ◽  
Time Course ◽  
Islet Function

Developmental programming of aging of isolated pancreatic islet glucose-stimulated insulin secretion in female offspring of mothers fed low-protein diets in pregnancy and/or lactation

2012 ◽  
Vol 3 (6) ◽  
pp. 483-488 ◽  
Author(s):  
S. Morimoto ◽  
T. C. Sosa ◽  
L. Calzada ◽  
L. A. Reyes-Castro ◽  
E. Díaz-Díaz ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islet ◽  
High Glucose ◽  
Female Offspring ◽  
Developmental Programming ◽  
Serum Glucose ◽  
Female Rat ◽  
Low Protein ◽  
Glucose Stimulated Insulin Secretion ◽  
In Pregnancy

Diabetes predisposition is determined by pancreatic islet insulin secretion and insulin resistance. We studied female rat offspring exposed to low-protein maternal diet (50% control protein diet) in pregnancy and/or lactation at postnatal days 36, 110 and 450. Rats were fed either control 20% casein diet (C) or restricted diet (R – 10% casein) during pregnancy. After delivery, mothers received either C or R diet until weaning to provide four offspring groups: CC, RR, CR and RC (first letter denoting maternal pregnancy diet and the second lactation diet). Serum glucose, insulin and homeostatic model assessment (HOMA) were measured. Pancreatic islets were isolated and in vitro insulin secretion quantified in low glucose (5 mM) and high glucose (11 mM). Serum glucose, insulin and HOMA were similar in all groups at 36 and 110 postnatal days. HOMA was only higher in RR at 450 postnatal days. Only CC demonstrated differences in glucose sensitivity of β-cells to high and low doses at the three ages studied. At 36 days, RR, CR and RC and at 450 days RR and RC groups did not show glucose-stimulated insulin secretion differences between low and high glucose. Aging-associated glucose-stimulated insulin secretion loss was affected by maternal dietary history, indicating that developmental programming must be considered a major factor in aging-related development of predisposition to later-life dysfunctional insulin metabolism. Female offspring islets’ insulin secretion was higher than previously reported in males.

scholarly journals Chronic Fetal Leucine Infusion Does Not Potentiate Glucose-Stimulated Insulin Secretion or Affect Pancreatic Islet Development in Late-Gestation Growth-Restricted Fetal Sheep

2020 ◽  
Author(s):  
Brit H Boehmer ◽  
Stephanie R Wesolowski ◽  
Laura D Brown ◽  
Paul J Rozance
Keyword(s):  
Endothelial Cells ◽  
Insulin Secretion ◽  
Mrna Expression ◽  
Pancreatic Islet ◽  
Late Gestation ◽  
Β Cells ◽  
Fetal Sheep ◽  
Islet Size ◽  
Intrauterine Fetal Growth Restriction ◽  
Glucose Stimulated Insulin Secretion

ABSTRACT Background Growth-restricted fetuses have attenuated glucose-stimulated insulin secretion (GSIS), smaller pancreatic islets, less pancreatic β-cells, and less pancreatic vascularization compared with normally growing fetuses. Infusion of leucine into normal late-gestation fetal sheep potentiates GSIS, as well as increases pancreatic islet size, the proportion of the pancreas and islet comprising β-cells, and pancreatic and islet vascularity. In addition, leucine stimulates hepatocyte growth factor (HGF ) mRNA expression in islet endothelial cells isolated from normal fetal sheep. Objective We hypothesized that a 9-d leucine infusion would potentiate GSIS and increase pancreatic islet size, β-cells, and vascularity in intrauterine fetal growth restriction (IUGR) fetal sheep. We also hypothesized that leucine would stimulate HGF mRNA in islet endothelial cells isolated from IUGR fetal sheep. Methods Late-gestation Columbia-Rambouillet IUGR fetal sheep (singleton or twin) underwent surgeries to place vascular sampling and infusion catheters. Fetuses were randomly allocated to receive a 9-d leucine infusion to achieve a 50–100% increase in leucine concentrations or a control saline infusion. GSIS was measured and pancreas tissue was processed for histologic analysis. Pancreatic islet endothelial cells were isolated from IUGR fetal sheep and incubated with supplemental leucine. Data were analyzed by mixed-models ANOVA; Student, Mann-Whitney, or a paired t test; or a test of equality of proportions. Results Chronic leucine infusion in IUGR fetuses did not affect GSIS, islet size, the proportion of the pancreas comprising β-cells, or pancreatic or pancreatic islet vascularity. In isolated islet endothelial cells from IUGR fetuses, HGF mRNA expression was not affected by supplemental leucine. Conclusions IUGR fetal sheep islets are not responsive to a 9-d leucine infusion with respect to insulin secretion or any histologic features measured. This is in contrast to the response in normally growing fetuses. These results are important when considering nutritional strategies to prevent the adverse islet and β-cell consequences in IUGR fetuses.

scholarly journals Mitochondrial Efflux of Citrate and Isocitrate is Fully Dispensable for Glucose-Stimulated Insulin Secretion and Pancreatic Islet β-Cell Function

2021 ◽  
Author(s):  
Casey J. Bauchle ◽  
Kristen E. Rohli ◽  
Cierra K. Boyer ◽  
Vidhant Pal ◽  
Jonathan V. Rocheleau ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islet ◽  
Glucose Homeostasis ◽  
Cell Function ◽  
Normal Glucose Tolerance ◽  
Coupling Factor ◽  
Β Cell ◽  
Metabolic Coupling ◽  
Β Cell Function ◽  
Glucose Stimulated Insulin Secretion

The defining feature of pancreatic islet β-cell function is the precise coordination of changes in blood glucose levels with insulin secretion to regulate systemic glucose homeostasis. While ATP has long been heralded as a critical metabolic coupling factor to trigger insulin release, glucose-derived metabolites have been suggested to further amplify fuel-stimulated insulin secretion. The mitochondrial export of citrate and isocitrate through the citrate-isocitrate carrier (CIC) has been suggested to initiate a key pathway that amplifies glucose-stimulated insulin secretion, though the physiological significance of β-cell CIC to glucose homeostasis has not been established. Here, we generated constitutive and adult CIC β-cell knockout mice and demonstrate these animals have normal glucose tolerance, similar responses to diet-induced obesity, and identical insulin secretion responses to various fuel secretagogues. Glucose-stimulated NADPH production was impaired in β-cell CIC KO islets, whereas glutathione reduction was retained. Furthermore, suppression of the downstream enzyme, cytosolic isocitrate dehydrogenase, Idh1, inhibited insulin secretion in wild type islets, but failed to impact β-cell function in β-cell CIC KO islets.<b> </b>Our data demonstrate that the mitochondrial citrate-isocitrate carrier is not required for glucose-stimulated insulin secretion, and that additional complexities exist for the role of Idh1 and NADPH in the regulation of β-cell function.

Mitochondrial efflux of citrate and isocitrate is fully dispensable for glucose-stimulated insulin secretion and pancreatic islet β-cell function

Diabetes ◽  
2021 ◽  
pp. db210037
Author(s):  
Casey J. Bauchle ◽  
Kristen E. Rohli ◽  
Cierra K. Boyer ◽  
Vidhant Pal ◽  
Jonathan V. Rocheleau ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islet ◽  
Cell Function ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucose Stimulated Insulin Secretion

scholarly journals Pancreatic Islet APJ Deletion Reduces Islet Density and Glucose Tolerance in Mice

Endocrinology ◽  
2015 ◽  
Vol 156 (7) ◽  
pp. 2451-2460 ◽  
Author(s):  
Song Han ◽  
Ella W. Englander ◽  
Guillermo A. Gomez ◽  
Cristiana Rastellini ◽  
Thomas Quertermous ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Pancreatic Islet ◽  
Glucose Tolerance Test ◽  
Islet Cells ◽  
Tolerance Test ◽  
Β Cell ◽  
Glucose Clearance ◽  
Islet Size ◽  
Glucose Stimulated Insulin Secretion

Protection and replenishment of a functional pancreatic β-cell mass (BCM) are key goals of all diabetes therapies. Apelin, a small regulatory peptide, is the endogenous ligand for the apelin receptor (APJ) receptor. The apelin-APJ signaling system is expressed in rodent and human islet cells. Apelin exposure has been shown to inhibit and to stimulate insulin secretion. Our aim was to assess the influence of a selective APJ deletion in pancreatic islet cells on islet homeostasis and glucose tolerance in mice. Cre-LoxP strategy was utilized to mediate islet APJ deletion. APJ deletion in islet cells (APJΔislet) resulted in a significantly reduced islet size, density and BCM. An ip glucose tolerance test showed significantly impaired glucose clearance in APJΔislet mice. APJΔislet mice were not insulin resistant and in vivo glucose-stimulated insulin secretion was reduced modestly. In vitro glucose-stimulated insulin secretion showed a significantly reduced insulin secretion by islets from APJΔislet mice. Glucose clearance in response to ip glucose tolerance test in obese APJΔislet mice fed a chronic high-fat (HF) diet, but not pregnant APJΔislet mice, was impaired significantly. In addition, the obesity-induced adaptive elevations in mean islet size and fractional islet area were reduced significantly in obese APJΔislet mice when compared with wild-type mice. Together, these findings demonstrate a stimulatory role for the islet cell apelin-APJ signaling axis in regulation of pancreatic islet homeostasis and in metabolic induced β-cell hyperplasia. The results indicate the apelin-APJ system can be exploited for replenishment of BCM.

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