Synchronization and entrainment of cytoplasmic Ca2+ oscillations in cell clusters prepared from single or multiple mouse pancreatic islets

2004 ◽  
Vol 287 (2) ◽  
pp. E340-E347 ◽  
Author(s):  
Milos Zarkovic ◽  
Jean-Claude Henquin
Keyword(s):  
Pancreatic Islets ◽  
Islet Cells ◽  
Single Pulse ◽  
External Signal ◽  
Β Cells ◽  
Mouse Islet ◽  
Mouse Pancreatic Islets ◽  
The Difference ◽  
External Signals ◽  
Sufficient Strength

In contrast to pancreatic islets, isolated β-cells stimulated by glucose display irregular and asynchronous increases in cytoplasmic Ca2+ concentration ([Ca2+]i). Here, clusters of 5–30 cells were prepared from a single mouse islet or from pools of islets, loaded with fura-2, and studied with a camera-based system. [Ca2+]i oscillations were compared in pairs of clusters by computing the difference in period and a synchronization index λ. During perifusion with 12 mM glucose, the clusters exhibited regular [Ca2+]i oscillations that were quasi-perfectly synchronized (Δ period of 1.4% and index λ close to 1.0) between cells of each cluster. In contrast, separate clusters were not synchronized, even when prepared from one single islet. Pairs of clusters neighboring on the same coverslip were not better synchronized than pairs of clusters examined separately (distinct coverslips). We next attempted to synchronize clusters perifused with 12 mM glucose by applying external signals. A single pulse of 20 mM glucose, 10 mM amino acids, or 10 μM tolbutamide transiently altered [Ca2+]i oscillations but did not reset the clusters to oscillate synchronously. On a background of 12 mM glucose, repetitive applications (1 min/5 min) of 10 μM tolbutamide, but not of 20 mM glucose, synchronized separate clusters. Our results identify a level of β-cell heterogeneity intermediate between single β-cells and the whole islet. They do not support the idea that substances released by islet cells serve as paracrine synchronizers. However, synchronization can be achieved by an external signal, if this signal has a sufficient strength to overwhelm the intrinsic rhythm of glucose-induced oscillations and is repetitively applied.

scholarly journals Expression of somatostatin receptor subtypes 1–5 in pancreatic islets of normoglycaemic and diabetic NOD mice

2005 ◽  
Vol 153 (3) ◽  
pp. 445-454 ◽  
Author(s):  
E Ludvigsen ◽  
M Stridsberg ◽  
E T Janson ◽  
S Sandler
Keyword(s):  
Pancreatic Islets ◽  
Islet Cells ◽  
Somatostatin Receptor ◽  
Nod Mice ◽  
Receptor Subtypes ◽  
Β Cells ◽  
Somatostatin Receptor Subtypes ◽  
Icr Mouse ◽  
The Difference ◽  
Cell Expression

Objective: Somatostatin acts on five specific receptors (sst1–5) to elicit different biological functions. The non-obese diabetic (NOD) mouse is an experimental model of type 1 diabetes. The aim of this study was to investigate whether the islet expression of sst1–5 is affected during the development of diabetes in NOD mice, with insulitis accompanied by spontaneous hyperglycaemia. Methods: By immunostaining for sst1–5 the expression and co-expression together with the four major islet hormones in pancreatic islets were investigated in female and male NOD mice at different stages of disease. The NOD related non-diabetic ICR mouse was also examined. Results: The islet cells of diabetic NOD mice showed an increased islet cell expression of sst2–5 compared with normoglycaemic female NOD mice. This correlated to increasing age and extent of insulitis. Major findings from the co-expression investigations were that sst2 was expressed in a majority of β-cells in the normoglycaemic NOD mice, but absent in the β-cells in the diabetic NOD mice. A majority of the α-cells expressed sst2 and 5 in normoglycaemic and diabetic NOD mice. About 60% of δ-cells showed co-expression of sst4 and 5 in both normoglycaemic and diabetic NOD mice. 60% of pancreatic polypeptide (PP)-cells expressed sst4 in both groups. Insulitis was found to be accompanied by a down-regulation of sst in normoglycaemic animals. Conclusions: The difference in sst expression in the islets cells of diabetic mice may suggest either a contributing factor in the process leading to diabetes, or a defence response against ongoing β-cell destruction.

Heat-shock treatment of mouse pancreatic islets results in a partial loss of islet cells but no remaining functional impairment among the surviving β cells

1988 ◽  
Vol 1 (1) ◽  
pp. 27-31 ◽  
Author(s):  
M. Welsh ◽  
D. L. Eizirik ◽  
E. Strandell
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Pancreatic Islets ◽  
Cell Function ◽  
Islet Cells ◽  
Β Cells ◽  
Insulin Synthesis ◽  
Mouse Pancreatic Islets ◽  
Β Cell Function ◽  
Shock Proteins

ABSTRACT To elucidate the role of thermal stress on the function of pancreatic β cells, isolated mouse pancreatic islets were incubated for 30 min at 42°C. This resulted in decreased glucose-stimulated insulin secretion, inhibited total protein and pro-insulin synthesis and the induction of heat-shock proteins with molecular weights of 64 and 88 kDa. Six days later, the islets exposed to heat shock showed a lower DNA content, indicating islet cell death. However, the insulin secretory response and rates of oxygen consumption in the presence of glucose were normal. It is suggested that the induction of heat-shock proteins does not permanently impair β-cell function, but rather protects these cells from lasting damage.

scholarly journals Taurine supplementation: involvement of cholinergic/phospholipase C and protein kinase A pathways in potentiation of insulin secretion and Ca2+handling in mouse pancreatic islets

2010 ◽  
Vol 104 (8) ◽  
pp. 1148-1155 ◽  
Author(s):  
Rosane A. Ribeiro ◽  
Emerielle C. Vanzela ◽  
Camila A. M. Oliveira ◽  
Maria L. Bonfleur ◽  
Antonio C. Boschero ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Protein Kinase ◽  
Pancreatic Islets ◽  
Phospholipase C ◽  
Islet Cells ◽  
Taurine Supplementation ◽  
Adult Mice ◽  
Intracellular Ca ◽  
Mouse Pancreatic Islets ◽  
Methyl Xanthine

Taurine (TAU) supplementation increases insulin secretion in response to high glucose concentrations in rodent islets. This effect is probably due to an increase in Ca2+handling by the islet cells. Here, we investigated the possible involvement of the cholinergic/phospholipase C (PLC) and protein kinase (PK) A pathways in this process. Adult mice were fed with 2 % TAU in drinking water for 30 d. The mice were killed and pancreatic islets isolated by the collagenase method. Islets from TAU-supplemented mice showed higher insulin secretion in the presence of 8·3 mm-glucose, 100 μm-carbachol (Cch) and 1 mm-3-isobutyl-1-methyl-xanthine (IBMX), respectively. The increase in insulin secretion in response to Cch in TAU islets was accompanied by a higher intracellular Ca2+mobilisation and PLCβ2protein expression. The Ca2+uptake was higher in TAU islets in the presence of 8·3 mm-glucose, but similar when the islets were challenged by glucose plus IBMX. TAU islets also showed an increase in the expression of PKAα protein. This protein may play a role in cation accumulation, since the amount of Ca2+in these islets was significantly reduced by the PKA inhibitors:N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline sulfonamide (H89) and PK inhibitor-(6–22)-amide (PKI). In conclusion, TAU supplementation increases insulin secretion in response to glucose, favouring both influx and internal mobilisation of Ca2+, and these effects seem to involve the activation of both PLC–inositol-1,4,5-trisphosphate and cAMP–PKA pathways.

scholarly journals Piezo1 channel activation mimics high glucose as a stimulator of insulin release

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vijayalakshmi Deivasikamani ◽  
Savitha Dhayalan ◽  
Yilizila Abudushalamu ◽  
Romana Mughal ◽  
Asjad Visnagri ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Insulin Release ◽  
Cell Lines ◽  
High Glucose ◽  
Mammalian Cells ◽  
Cell Swelling ◽  
Β Cells ◽  
Β Cell ◽  
Intracellular Ca ◽  
Mouse Pancreatic Islets

AbstractGlucose and hypotonicity induced cell swelling stimulate insulin release from pancreatic β-cells but the mechanisms are poorly understood. Recently, Piezo1 was identified as a mechanically-activated nonselective Ca2+ permeable cationic channel in a range of mammalian cells. As cell swelling induced insulin release could be through stimulation of Ca2+ permeable stretch activated channels, we hypothesised a role for Piezo1 in cell swelling induced insulin release. Two rat β-cell lines (INS-1 and BRIN-BD11) and freshly-isolated mouse pancreatic islets were studied. Intracellular Ca2+ measurements were performed using the fura-2 Ca2+ indicator dye and ionic current was recorded by whole cell patch-clamp. Piezo1 agonist Yoda1, a competitive antagonist of Yoda1 (Dooku1) and an inactive analogue of Yoda1 (2e) were used as chemical probes. Piezo1 mRNA and insulin secretion were measured by RT-PCR and ELISA respectively. Piezo1 mRNA was detected in both β-cell lines and mouse islets. Yoda1 evoked Ca2+ entry was inhibited by Yoda1 antagonist Dooku1 as well as other Piezo1 inhibitors gadolinium and ruthenium red, and not mimicked by 2e. Yoda1, but not 2e, stimulated Dooku1-sensitive insulin release from β-cells and pancreatic islets. Hypotonicity and high glucose increased intracellular Ca2+ and enhanced Yoda1 Ca2+ influx responses. Yoda1 and hypotonicity induced insulin release were significantly inhibited by Piezo1 specific siRNA. Pancreatic islets from mice with haploinsufficiency of Piezo1 released less insulin upon exposure to Yoda1. The data show that Piezo1 channel agonist induces insulin release from β-cell lines and mouse pancreatic islets suggesting a role for Piezo1 in cell swelling induced insulin release. Hence Piezo1 agonists have the potential to be used as enhancers of insulin release.

Identification of iduronate-2-sulfatase in mouse pancreatic islets

2004 ◽  
Vol 287 (5) ◽  
pp. E983-E990 ◽  
Author(s):  
I. Coronado-Pons ◽  
A. Novials ◽  
S. Casas ◽  
A. Clark ◽  
R. Gomis
Keyword(s):  
Pancreatic Islets ◽  
Cell Function ◽  
Dermatan Sulfate ◽  
Islet Cells ◽  
Secretory Response ◽  
High Rate ◽  
Insulin Content ◽  
Dependent Manner ◽  
Mouse Pancreatic Islets ◽  
Mouse Islets

The lysosomal enzyme iduronate-2-sulfatase (IDS) is expressed in pancreatic islets and is responsible for degradation of proteoglycans, such as perlecan and dermatan sulfate. To determine the role of IDS in islets, expression and regulation of the gene and localization of the enzyme were investigated in mouse pancreatic islets and clonal cells. The Ids gene was expressed in mouse islets and β- and α-clonal cells, in which it was localized intracellularly in lysosomes. The transcriptional expression of Ids in mouse islets increased with glucose in a dose-dependent manner (11.5, 40.2, 88, and 179% at 5.5, 11.1, 16.7, and 24.4 mM, respectively, P < 0.01 for 16.7 and 24.4 mM glucose vs. 3 mM glucose). This increase was not produced by glyceraldehyde (1 mM) or 6-deoxyglucose (21.4 mM) and was blocked by the addition of mannoheptulose (21.4 mM). Neither insulin content nor secretory response to glucose (16.7 mM) was altered in mouse islets infected with lentiviral constructs carrying the IDS gene in sense orientation. Furthermore, no decrease in islet cell viability was observed in mouse islets carrying lentiviral contracts compared with controls. However, insulin content was reduced (35% vs. controls, P < 0.001) in islets infected with IDS antisense construct, while the secretory response of those islets to glucose was maintained. Inhibition of IDS by antisense infection led to an increase in lysosomal size and a high rate of insulin granule degradation via the crinophagic route in pancreatic β-cells. We conclude that IDS is localized in lysosomes in pancreatic islet cells and expression is regulated by glucose. IDS has a potential role in the normal pathway of lysosomal degradation of secretory peptides and is likely to be essential to maintain pancreatic β-cell function.

scholarly journals Unraveling the role of the ghrelin gene peptides in the endocrine pancreas

2010 ◽  
Vol 45 (3) ◽  
pp. 107-118 ◽  
Author(s):  
Riccarda Granata ◽  
Alessandra Baragli ◽  
Fabio Settanni ◽  
Francesca Scarlatti ◽  
Ezio Ghigo
Keyword(s):  
Pancreatic Islets ◽  
Cell Biology ◽  
Islet Cell ◽  
Endocrine Pancreas ◽  
Islet Cells ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Islet Cell ◽  
Ghrelin Gene

The ghrelin gene peptides include acylated ghrelin (AG), unacylated ghrelin (UAG), and obestatin (Ob). AG, mainly produced by the stomach, exerts its central and peripheral effects through the GH secretagogue receptor type 1a (GHS-R1a). UAG, although devoid of GHS-R1a-binding affinity, is an active peptide, sharing with AG many effects through an unknown receptor. Ob was discovered as the G-protein-coupled receptor 39 (GPR39) ligand; however, its physiological actions remain unclear. The endocrine pancreas is necessary for glucose homeostasis maintenance. AG, UAG, and Ob are expressed in both human and rodent pancreatic islets from fetal to adult life, and the pancreas is the major source of ghrelin in the perinatal period. GHS-R1a and GPR39 expression has been shown in β-cells and islets, as well as specific binding sites for AG, UAG, and Ob. Ghrelin colocalizes with glucagon in α-islet cells, but is also uniquely expressed in ε-islet cells, suggesting a role in islet function and development. Indeed, AG, UAG, and Ob regulate insulin secretion in β-cells and isolated islets, promote β-cell proliferation and survival, inhibit β-cell and human islet cell apoptosis, and modulate the expression of genes that are essential in pancreatic islet cell biology. They even induce β-cell regeneration and prevent diabetes in streptozotocin-treated neonatal rats. The receptor(s) mediating their effects are not fully characterized, and a signaling crosstalk has been suggested. The present review summarizes the newest findings on AG, UAG, and Ob expression in pancreatic islets and the role of these peptides on β-cell development, survival, and function.

Sustained exposure of toxically damaged mouse pancreatic islets to high glucose does not increase β-cell dysfunction

1989 ◽  
Vol 123 (1) ◽  
pp. 47-51 ◽  
Author(s):  
D. L. Eizirik ◽  
S. Sandler
Keyword(s):  
Pancreatic Islets ◽  
Insulin Release ◽  
High Glucose ◽  
Β Cells ◽  
Β Cell ◽  
Glucose Stimulation ◽  
Cell Dysfunction ◽  
Mouse Pancreatic Islets ◽  
Insulin Secretory Response

ABSTRACT The aim of this study was to clarify whether prolonged in-vitro exposure of either normal or damaged β cells to a high glucose environment can be toxic to these cells. For this purpose NMRI mice were injected intravenously with a diabetogenic dose of streptozotocin (SZ; 160 mg/kg) or vehicle alone (controls). Their islets were isolated 15 min after the injection and subsequently maintained in culture for 21 days in the presence of 11·1 or 28 mmol glucose/l. After this period, during acute glucose stimulation, the control islets showed a marked increase in their insulin release in response to a high glucose stimulus. In the SZ-exposed islets there was a decrease in DNA and insulin contents, and a deficient insulin secretory response to glucose. However, in the SZ-damaged islets as well as in the control islets, culture with 28 mmol glucose/l compared with 11·1 mmol glucose/l did not impair islet retrieval after culture, islet DNA content or glucose-induced insulin release. Thus, the degree of damage was similar in the SZ-treated islets cultured at the two concentrations of glucose. These results suggest that glucose is not toxic to normal or damaged mouse pancreatic islets over a prolonged period in tissue culture. Journal of Endocrinology (1989) 123, 47–51

scholarly journals GPRC6A Mediates the Effects of l-Arginine on Insulin Secretion in Mouse Pancreatic Islets

Endocrinology ◽  
2012 ◽  
Vol 153 (10) ◽  
pp. 4608-4615 ◽  
Author(s):  
Min Pi ◽  
Yunpeng Wu ◽  
Nataliya I Lenchik ◽  
Ivan Gerling ◽  
L. Darryl Quarles
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islets ◽  
Ex Vivo ◽  
Β Cells ◽  
Direct Role ◽  
Mouse Pancreatic Islets ◽  
Islet Size ◽  
G Protein Coupled ◽  
Stimulation Of

Abstract l-Arginine (l-Arg) is an insulin secretagogue, but the molecular mechanism whereby it stimulates insulin secretion from β-cells is not known. The possibility that l-Arg regulates insulin secretion through a G protein-coupled receptor (GPCR)-mediated mechanism is suggested by the high expression of the nutrient receptor GPCR family C group 6 member A (GPRC6A) in the pancreas and TC-6 β-cells and the finding that Gprc6a−/]minus] mice have abnormalities in glucose homeostasis. To test the direct role of GPRC6A in regulating insulin secretion, we evaluated the response of pancreatic islets derived from Gprc6a−/]minus] mice to l-Arg. We found that the islet size and insulin content were decreased in pancreatic islets from Gprac6a−/]minus] mice. These alterations were selective for β-cells, because there were no abnormalities in serum glucagon levels or glucagon content of islets derived from Gprac6a−/]minus] mice. Significant reduction was observed in both the pancreatic ERK response to l-Arg administration to Gprc6a−/]minus] mice in vivo and l-Arg-induced insulin secretion and production ex vivo in islets isolated from Gprc6a−/]minus] mice. l-Arg stimulation of cAMP accumulation in isolated islets isolated from Gprc6a−/]minus] mice was also diminished. These findings suggest that l-Arg stimulation of insulin secretion in β-cells is mediated, at least in part, through GPRC6A activation of cAMP pathways.

scholarly journals GABAA receptor-mediated currents and hormone mRNAs in cells expressing more than one hormone transcript in intact human pancreatic islets

2019 ◽  
Author(s):  
Sergiy V. Korol ◽  
Zhe Jin ◽  
Bryndis Birnir
Keyword(s):  
Pancreatic Islets ◽  
Single Channel ◽  
Islet Cells ◽  
Cell Types ◽  
Cell Type ◽  
Expression Ratio ◽  
Human Pancreatic Islets ◽  
The Difference ◽  
Type 2 Diabetic

AbstractIn pancreatic islets the major cell-types are α, β and δ cells, secreting the hormones glucagon (GCG), insulin (INS) and somatostatin (SST), respectively. The GABA (γ-aminobutyric acid) signalling system is expressed in human pancreatic islets. We have previously used single-cell RT-PCR in combination with current recordings to correlate expression of single hormone transcript with functional GABAA receptor (iGABAAR) properties in islets. Here we extended these studies to islet cells from non-diabetic and type 2 diabetic donors that express mRNAs for more than one hormone. We detected cells expressing double (α/β, α/δ, β/δ cell-types) and triple (α/β/δ cell-type) hormone transcripts. The most common mixed-identity cell-type was the α/β group where the cells could be grouped into β- and α-like subgroups. The β-like cells had low GCG/INS expression ratio (< 0.6) and significantly higher frequency of single-channel iGABAAR openings than the α-like cells where the GCG/INS expression ratio was high (> 1.2). The difference in expression levels and single channel iGABAAR characteristics varied in the α/β/δ cell-type. No correlation was observed between the cell-types identity with time in culture or cell size. Clearly, multiple hormone transcripts can be expressed in islet cells whereas iGABAAR functional properties appear α or β cell specific.

scholarly journals Persistent Infection of Human Pancreatic Islets by Coxsackievirus B Is Associated with Alpha Interferon Synthesis in β Cells

2000 ◽  
Vol 74 (21) ◽  
pp. 10153-10164 ◽  
Author(s):  
Wassim Chehadeh ◽  
Julie Kerr-Conte ◽  
François Pattou ◽  
Gunar Alm ◽  
Jean Lefebvre ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Islet Cells ◽  
Human Islets ◽  
Adult Brain ◽  
Viral Rna ◽  
Alpha Interferon ◽  
Β Cells ◽  
Human Pancreatic Islets ◽  
Reverse Transcription Pcr ◽  
Vp1 Capsid Protein

ABSTRACT The interactions of coxsackievirus B3 (CVB3), CVB4E2 (diabetogenic), and CVB4JBV (nondiabetogenic) strains with human pancreatic islets from eight adult brain-dead donors were investigated. Persistent replication of viruses in human islets was proved by detection of viral RNA by in situ hybridization, VP1 capsid protein by immunofluorescence (IF) staining, negative-strand viral RNA by reverse transcription-PCR in extracted RNA from islets, and release of infectious particles up to 30 days after infection without obvious cytolysis. By double IF staining, glucagon-containing α cells and insulin-containing β cells were shown to be susceptible to CVB. The persistence of CVB3 and CVB4 in islet cells was associated with the chronic synthesis of alpha interferon (IFN-α), as evidenced by the detection of IFN-α mRNA and immunoreactive IFN-α with antiviral activity. By double IF staining, IFN-α was detected in insulin-producing β cells only. Experiments with neutralizing anti-coxsackievirus and adenovirus receptor (CAR) antibodies provided evidence that CAR was expressed by α and β cells and that it played a role in the infection of these cells with CVB and the consecutive IFN-α expression in β cells. The viral replication and the expression of IFN-α in islets were not restricted to the CVB4E2 diabetogenic strain and did not depend on the genetic background of the host. The neutralization of endogenous IFN-α significantly enhanced the CVB replication in islet cells and resulted in rapid destruction of islets. Thus, human β cells can harbor a persistent CVB infection, and CVB-induced IFN-α plays a role in the initiation and/or maintenance of chronic CVB infection in human islets.

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