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Sample records for rat pancreatic beta-cells

  1. Dopamine Modulates Insulin Release and Is Involved in the Survival of Rat Pancreatic Beta Cells

    PubMed Central

    Iglesias Osma, Maria Carmen; Blanco, Enrique J.; Carretero Hernández, Marta; Sánchez Robledo, Virginia; Catalano Iniesta, Leonardo; Carrero, Sixto

    2015-01-01

    The local synthesis of dopamine and its effects on insulin release have been described in isolated islets. Thus, it may be accepted that dopamine exerts an auto-paracrine regulation of insulin secretion from pancreatic beta cells. The aim of the present study is to analyze whether dopamine is a regulator of the proliferation and apoptosis of rat pancreatic beta cells after glucose-stimulated insulin secretion. Glucose stimulated pancreatic islets obtained from male Wistar rats were cultured with 1 or 10 μM dopamine from 1 to 12 h. Insulin secretion was analyzed by RIA. The cellular proliferation rate of pancreatic islets and beta cells was studied with immunocytochemical double labelling for both insulin and PCNA (proliferating cell nuclear antigen), and active caspase-3 was detected to evaluate apoptosis. The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment. The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h. The proliferation rate of insulin-positive cells in the islets decreased significantly (p<0.01) following treatment with dopamine. Apoptosis in pancreatic islets and beta cells was increased by treatment with 1 and 10 μM dopamine along 12 h. In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets. PMID:25886074

  2. Species-Related Differences in the Proteome of Rat and Human Pancreatic Beta Cells

    PubMed Central

    Martens, G. A.

    2015-01-01

    The core proteomes of human and rat pancreatic beta cells were compared by label-free LC-MS/MS: this resulted in quantification of relative molar abundances of 707 proteins belonging to functional pathways of intermediary metabolism, protein synthesis, and cytoskeleton. Relative molar abundances were conserved both within and between pathways enabling the selection of a housekeeping network for geometric normalization and the analysis of potentially relevant differential expressions. Human beta cells differed from rat beta cells in their lower level of enzymes involved in glucose sensing (MDH1, PC, and ACLY) and upregulation of lysosomal enzymes. Human cells also expressed more heat shock proteins and radical scavenging systems: apart from SOD2, they expressed high levels of H2O2-scavenger peroxiredoxin 3 (PRDX3), confirmed by microarray, Western blotting, and microscopy. Besides conferring lower susceptibility to oxidative stress to human cells PRDX3 might also play a role in physiological redox regulation as, in rat, its expression was restricted to a beta cell subset with higher metabolic glucose responsiveness. In conclusion, although their core proteomic architecture is conserved, human and rat beta cells differ in their molar expression of key enzymes involved in glucose sensing and redox control. PMID:26064985

  3. Increased androgen levels in rats impair glucose-stimulated insulin secretion through disruption of pancreatic beta cell mitochondrial function.

    PubMed

    Wang, Hongdong; Wang, Xiaping; Zhu, Yunxia; Chen, Fang; Sun, Yujie; Han, Xiao

    2015-11-01

    Although insulin resistance is recognized to contribute to the reproductive and metabolic phenotypes of polycystic ovary syndrome (PCOS), pancreatic beta cell dysfunction plays an essential role in the progression from PCOS to the development of type 2 diabetes. However, the role of insulin secretory abnormalities in PCOS has received little attention. In addition, the precise changes in beta cells and the underlying mechanisms remain unclear. In this study, we therefore attempted to elucidate potential mechanisms involved in beta cell alterations in a rat model of PCOS. Glucose-induced insulin secretion was measured in islets isolated from DHT-treated and control rats. Oxygen consumption rate (OCR), ATP production, and mitochondrial copy number were assayed to evaluate mitochondrial function. Glucose-stimulated insulin secretion is significantly decreased in islets from DHT-treated rats. On the other hand, significant reductions are observed in the expression levels of several key genes involved in mitochondrial biogenesis and in mitochondrial OCR and ATP production in DHT-treated rat islets. Meanwhile, we found that androgens can directly impair beta cell function by inducing mitochondrial dysfunction in vitro in an androgen receptor dependent manner. For the first time, our study demonstrates that increased androgens in female rats can impair glucose-stimulated insulin secretion partly through disruption of pancreatic beta cell mitochondrial function. This work has significance for hyperandrogenic women with PCOS: excess activation of the androgen receptor by androgens may provoke beta cell dysfunction via mitochondrial dysfunction. PMID:26348137

  4. Reduced Expression of the Liver/Beta-Cell Glucose Transporter Isoform in Glucose-Insensitive Pancreatic Beta Cells of Diabetic Rats

    NASA Astrophysics Data System (ADS)

    Thorens, Bernard; Weir, Gordon C.; Leahy, John L.; Lodish, Harvey F.; Bonner-Weir, Susan

    1990-09-01

    Rats injected with a single dose of streptozocin at 2 days of age develop non-insulin-dependent diabetes 6 weeks later. The pancreatic beta islet cells of these diabetic rats display a loss of glucose-induced insulin secretion while maintaining sensitivity to other secretagogues such as arginine. We analyzed the level of expression of the liver/beta-cell glucose transporter isoform in diabetic islets by immunofluorescence staining of pancreas sections and by Western blotting of islet lysates. Islets from diabetic animals have a reduced expression of this beta-cell-specific glucose transporter isoform and the extent of reduction is correlated with the severity of hyperglycemia. In contrast, expression of this transporter isoform in liver is minimally modified by the diabetes. Thus a decreased expression of the liver/beta-cell glucose transporter isoform in beta cells is associated with the impaired glucose sensing characteristic of diabetic islets; our data suggest that this glucose transporter may be part of the beta-cell glucose sensor.

  5. A quantitative study of sodium tungstate protective effect on pancreatic beta cells in streptozotocin-induced diabetic rats.

    PubMed

    Heidari, Zahra; Mahmoudzadeh-Sagheb, Hamidreza; Moudi, Bita

    2008-12-01

    Diabetes is a major public health problem. Development of new therapies that are able to improve glycemia management, cure diabetes, and can even protect from it, are of great interest. This study investigated the protective effect of sodium tungstate against STZ-induced beta-cell damages by means of stereological methods. Sixty rats were divided into six groups: control (C), tungstate-treated control (TC), STZ-induced diabetic (D), STZ-induced diabetic rats were treated by sodium tungstate from 1 week before STZ injection (TDB), food-restricted diabetic (FRD), and diabetic rats treated with sodium tungstate 1 week after STZ administration (TDA). Stereological estimation of pancreas volume, islets volume density, volume-weighted mean islets volume and mass of beta cells, islets, and pancreas and total number of islets were done. Islets volume density, volume-weighted mean islets volume, and mass of beta cells, islets, and pancreas of TDB group was significantly higher than D, FRD and TDA groups (P<0.001) and was comparable to controls (C and TC groups). Total number of islets, pancreas wet weight and volume did not show any significant changes between these groups (P>0.05). Results suggested that sodium tungstate preserves pancreatic beta cells from STZ-induced damages and diabetes induction in rats. PMID:18400503

  6. Properties of single potassium channels modulated by glucose in rat pancreatic beta-cells.

    PubMed Central

    Ashcroft, F M; Ashcroft, S J; Harrison, D E

    1988-01-01

    1. The patch clamp method has been used to examine the effect of glucose on single K+ channel currents recorded from cell-attached patches on dissociated rat pancreatic beta-cells. Patch pipettes contained a 140 mM-K+ solution. 2. In glucose-free solution three types of K+ channels were observed. Two of these, having conductances of around 50 pS (G-channel) and 20 pS when the external K+ concentration, [K+]0, was 140 mM, were active at the resting potential of the cell. The G-channel was observed in more patches and showed higher activity; it therefore appears to contribute the major fraction of the resting K+ permeability of the beta-cell. At membrane potentials positive to about +20 mV a third type of K+ channel, having a mean conductance of 120 pS, was activated. The open probability of this channel was strongly voltage dependent and increased with depolarization. 3. The reversal potential of the G-channel current was shifted 59 mV by a 10-fold change in external K+ (Na+ substitution) indicating the channel is highly K+ selective. The single-channel conductance varied with [K+]o as predicted from the Goldman-Hodgkin-Katz equation; at physiological [K+]o (5 mM-K+) an inward conductance of around 10 pS is predicted. The amplitude of the single-channel current showed a tendency to saturate with increasing [K+]o. 4. Single G-channel currents show burst kinetics indicating at least two closed states. The open and closed (gap) times within the bursts were distributed exponentially with time constants of 2.5 ms (tau o) and 0.5 ms (tau c1) respectively at the resting potential of the cell. There was little change in tau c1 over the voltage range -40 to 60 mV (pipette potential) but tau o increased slightly with membrane depolarization. 5. The addition of glucose to the bath solution produced a reversible, dose-dependent decrease in G-channel activity. This decrease results principally from a reduction in the frequency and duration of the bursts of openings with

  7. BACE2 is stored in secretory granules of mouse and rat pancreatic beta cells.

    PubMed

    Finzi, Giovanna; Franzi, Francesca; Placidi, Claudia; Acquati, Francesco; Palumbo, Elisa; Russo, Antonella; Taramelli, Roberto; Sessa, Fausto; La Rosa, Stefano

    2008-01-01

    BACE2 is a protease homologous to BACE1 protein, an enzyme involved in the amyloid formation of Alzheimer disease (AD). However, despite the high homology between these two proteins, the biological role of BACE2 is still controversial, even though a few studies have suggested a pathogenetic role in sporadic inclusion-body myositis and hereditary inclusion-body myopathy, which are characterized by vacuolization of muscular fibers with intracellular deposits of proteins similar to those found in the brain of AD patients. Although BACE2 has also been identified in the pancreas, its function remains unknown and its specific localization in different pancreatic cell types has not been definitively ascertained. For these reasons, the authors have investigated the cellular and subcellular localization of BACE2 in normal rodent pancreases. BACE2 immunoreactivity was found in secretory granules of beta cells, co-stored with insulin and IAPP, while it was lacking in the other endocrine and exocrine cell types. The presence of BACE2 in secretory granules of beta cells suggests that it may play a role in diabetes-associated amyloidogenesis. PMID:19117266

  8. Protective effect of Withania somnifera against oxidative stress and pancreatic beta-cell damage in type 2 diabetic rats.

    PubMed

    Anwer, Tarique; Sharma, Manju; Pillai, Krishna Kolappa; Khan, Gyas

    2012-01-01

    The aim of the present study was to investigate the effects of Withania somnifera (WS) on lipid peroxidation (LPO), activities of both non-enzymatic and enzymatic antioxidants and histopathological examination of pancreas in type 2 diabetic rats. Type 2 diabetes was induced by single intraperitoneal injection of STZ (100 mg/kg) to 2 days old rat pups. Oxidative stress was measured by tissue LPO levels, reduced glutathione (GSH) contents and by enzymatic activities of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT). Administration of WS to type 2 diabetic rats caused a significant decrease in blood glucose and tissue LPO levels with significant increase in GSH contents when compared with the type 2 diabetic control rats. In addition, WS treated rats also showed a significant increase in the activities of antioxidant enzymes namely GPx, GR, GST, SOD and CAT when compared with type 2 diabetic control rats. Significant reduction in the number and size of pancreatic beta-cells were preserved to near normal morphology by the administration of WS in type 2 diabetic rats as evident from histopathological examination. The results obtained clearly indicate that WS has shown strong free radical scavenging activity and helped in improving the non-enzymatic and enzymatic antioxidants in type 2 diabetic rats. PMID:23285670

  9. Glucolipotoxicity of the Pancreatic Beta Cell

    PubMed Central

    Poitout, Vincent; Amyot, Julie; Semache, Meriem; Zarrouki, Bader; Hagman, Derek; Fontés, Ghislaine

    2009-01-01

    Summary The concept of glucolipotoxicity refers to the combined, deleterious effects of elevated glucose and fatty acid levels on pancreatic beta-cell function and survival. Significant progress has been made in recent years towards a better understanding of the cellular and molecular basis of glucolipotoxicity in the beta cell. The permissive effect of elevated glucose on the detrimental actions of fatty acids stems from the influence of glucose on intracellular fatty-acid metabolism, promoting the synthesis of cellular lipids. The combination of excessive levels of fatty acids and glucose therefore leads to decreased insulin secretion, impaired insulin gene expression, and beta-cell death by apoptosis, all of which probably have distinct underlying mechanisms. Recent studies from our laboratory have identified several pathways implicated in fatty-acid inhibition of insulin gene expression, including the extracellular-regulated kinase (ERK1/2) pathway; the metabolic sensor Per-Arnt-Sim kinase (PASK); and the ATF6 branch of the unfolded protein response. We have also confirmed in vivo in rats that the decrease in insulin gene expression is an early defect which precedes any detectable abnormality in insulin secretion. While the role of glucolipotoxicity in humans is still debated, the inhibitory effects of chronically elevated fatty acid levels has been clearly demonstrated in several studies, at least in individuals genetically predisposed to developing type 2 diabetes. It is therefore likely that glucolipotoxicity contributes to beta-cell failure in type 2 diabetes as well as to the decline in beta-cell function observed after the onset of the disease. PMID:19715772

  10. Regulation of pancreatic beta-cell mass.

    PubMed

    Bouwens, Luc; Rooman, Ilse

    2005-10-01

    Beta-cell mass regulation represents a critical issue for understanding diabetes, a disease characterized by a near-absolute (type 1) or relative (type 2) deficiency in the number of pancreatic beta cells. The number of islet beta cells present at birth is mainly generated by the proliferation and differentiation of pancreatic progenitor cells, a process called neogenesis. Shortly after birth, beta-cell neogenesis stops and a small proportion of cycling beta cells can still expand the cell number to compensate for increased insulin demands, albeit at a slow rate. The low capacity for self-replication in the adult is too limited to result in a significant regeneration following extensive tissue injury. Likewise, chronically increased metabolic demands can lead to beta-cell failure to compensate. Neogenesis from progenitor cells inside or outside islets represents a more potent mechanism leading to robust expansion of the beta-cell mass, but it may require external stimuli. For therapeutic purposes, advantage could be taken from the surprising differentiation plasticity of adult pancreatic cells and possibly also from stem cells. Recent studies have demonstrated that it is feasible to regenerate and expand the beta-cell mass by the application of hormones and growth factors like glucagon-like peptide-1, gastrin, epidermal growth factor, and others. Treatment with these external stimuli can restore a functional beta-cell mass in diabetic animals, but further studies are required before it can be applied to humans. PMID:16183912

  11. Beneficial effects of Murraya koenigii leaves on antioxidant defense system and ultra structural changes of pancreatic beta-cells in experimental diabetes in rats.

    PubMed

    Arulselvan, Palanisamy; Subramanian, Sorimuthu Pillai

    2007-01-30

    Oxidative stress and oxidative damage to tissues are common end points of chronic diseases such as atherosclerosis, diabetes, and rheumatoid arthritis. Oxidative stress in diabetes coexists with a reduction in the antioxidant status, which can further increase the deleterious effects of free radicals. The aim of the present study was to evaluate the possible protective effects of Murraya koenigii leaves extract against beta-cell damage and antioxidant defense systems of plasma and pancreas in streptozotocin induced diabetes in rats. The levels of glucose and glycosylated hemoglobin in blood and insulin, Vitamin C, Vitamin E, ceruloplasmin, reduced glutathione and TBARS were estimated in plasma of control and experimental groups of rats. To assess the changes in the cellular antioxidant defense system such as the level of reduced glutathione and activities of superoxide dismutase, catalase and glutathione peroxidase were assayed in pancreatic tissue homogenate. The levels of glucose, glycosylated hemoglobin, insulin, TBARS, enzymatic and non-enzymatic antioxidants were altered in diabetic rats. These alterations were reverted back to near control levels after the treatment of M. koenigii leaves extract. Transmission electron microscopic studies also revealed the protective nature of M. koenigii leaves on pancreatic beta-cells. These findings suggest that M. koenigii treatment exerts a therapeutic protective nature in diabetes by decreasing oxidative stress and pancreatic beta-cell damage. The antioxidant effect of the M. koenigii extract was compared with glibenclamide, a well-known hypoglycemic drug. PMID:17188670

  12. Extracellular ATP stimulates exocytosis via localized Ca(2+) release from acidic stores in rat pancreatic beta cells.

    PubMed

    Xie, Li; Zhang, Ming; Zhou, Wei; Wu, Zhengxing; Ding, Jiuping; Chen, Liangyi; Xu, Tao

    2006-04-01

    Three different methods, membrane capacitance (C(m)) measurement, amperometry and FM dye labeling were used to investigate the role of extracellular ATP in insulin secretion from rat pancreatic beta cells. We found that extracellular application of ATP mobilized intracellular Ca(2+) stores and synchronously triggered vigorous exocytosis. No influence of ATP on the readily releasable pool of vesicles was observed, which argues against a direct modulation of the secretory machinery at a level downstream of Ca(2+) elevation. The stimulatory effects of ATP were greatly reduced by intracellular perfusion of BAPTA but not EGTA, suggesting a close spatial association of fusion sites with intracellular Ca(2+) releasing sites. ATP-induced Ca(2+) transients and exocytosis were not blocked by thapsigargin (TG), by a ryanodine receptor antagonist or by dissipation of pH in acidic stores by monensin alone, but they were greatly attenuated by IP(3) receptor inhibition as well as ionomycin plus monensin, suggesting involvement of IP(3)-sensitive acidic Ca(2+) stores. Taken together, our data suggest that extracellular ATP triggers exocytosis by mobilizing spatially limited acidic Ca(2+) stores through IP(3) receptors. This mechanism may explain how insulin secretion from the pancreas is coordinated through diffusible ATP that is co-released with insulin. PMID:16536741

  13. Detailed transcriptome atlas of the pancreatic beta cell

    PubMed Central

    Kutlu, Burak; Burdick, David; Baxter, David; Rasschaert, Joanne; Flamez, Daisy; Eizirik, Decio L; Welsh, Nils; Goodman, Nathan; Hood, Leroy

    2009-01-01

    Background Gene expression patterns provide a detailed view of cellular functions. Comparison of profiles in disease vs normal conditions provides insights into the processes underlying disease progression. However, availability and integration of public gene expression datasets remains a major challenge. The aim of the present study was to explore the transcriptome of pancreatic islets and, based on this information, to prepare a comprehensive and open access inventory of insulin-producing beta cell gene expression, the Beta Cell Gene Atlas (BCGA). Methods We performed Massively Parallel Signature Sequencing (MPSS) analysis of human pancreatic islet samples and microarray analyses of purified rat beta cells, alpha cells and INS-1 cells, and compared the information with available array data in the literature. Results MPSS analysis detected around 7600 mRNA transcripts, of which around a third were of low abundance. We identified 2000 and 1400 transcripts that are enriched/depleted in beta cells compared to alpha cells and INS-1 cells, respectively. Microarray analysis identified around 200 transcription factors that are differentially expressed in either beta or alpha cells. We reanalyzed publicly available gene expression data and integrated these results with the new data from this study to build the BCGA. The BCGA contains basal (untreated conditions) gene expression level estimates in beta cells as well as in different cell types in human, rat and mouse pancreas. Hierarchical clustering of expression profile estimates classify cell types based on species while beta cells were clustered together. Conclusion Our gene atlas is a valuable source for detailed information on the gene expression distribution in beta cells and pancreatic islets along with insulin producing cell lines. The BCGA tool, as well as the data and code used to generate the Atlas are available at the T1Dbase website (T1DBase.org). PMID:19146692

  14. Rat neonatal beta cells lack the specialised metabolic phenotype of mature beta cells

    PubMed Central

    Jermendy, A.; Toschi, E.; Aye, T.; Koh, A.; Aguayo-Mazzucato, C.; Sharma, A.; Weir, G. C.; Sgroi, D.

    2011-01-01

    Aims/hypothesis Fetal and neonatal beta cells have poor glucose-induced insulin secretion and only gain robust glucose responsiveness several weeks after birth. We hypothesise that this unresponsiveness is due to a generalised immaturity of the metabolic pathways normally found in beta cells rather than to a specific defect. Methods Using laser-capture microdissection we excised beta cell-enriched cores of pancreatic islets from day 1 (P1) neonatal and young adult Sprague–Dawley rats in order to compare their gene-expression profiles using Affymetrix U34A microarrays (neonatal, n=4; adult, n=3). Results Using dChip software for analysis, 217 probe sets for genes/38 expressed sequence tags (ESTs) were significantly higher and 345 probe sets for genes/33 ESTs significantly lower in beta cell-enriched cores of neonatal islets compared with those of adult islets. Among the genes lower in the neonatal beta cells were key metabolic genes including mitochondrial shuttles (malate dehydrogenase, glycerol-3-phosphate dehydrogenase and glutamate oxalacetate transaminase), pyruvate carboxylase and carnitine palmitoyl transferase 2. Differential expression of these enzyme genes was confirmed by quantitative PCR on RNA from isolated neonatal (P2 until P28) and adult islets and with immunostaining of pancreas. Even by 28 days of age some of these genes were still expressed at lower levels than in adults. Conclusions/interpretation The lack of glucose responsiveness in neonatal islets is likely to be due to a generalised immaturity of the metabolic specialisation of pancreatic beta cells. PMID:21240476

  15. Positron emission tomography study on pancreatic somatostatin receptors in normal and diabetic rats with {sup 68}Ga-DOTA-octreotide: A potential PET tracer for beta cell mass measurement

    SciTech Connect

    Sako, Takeo; Hasegawa, Koki; Nishimura, Mie; Kanayama, Yousuke; Wada, Yasuhiro; Hayashinaka, Emi; Cui, Yilong; Kataoka, Yosky; Senda, Michio; Watanabe, Yasuyoshi

    2013-12-06

    Highlights: •PET images showed high uptake of {sup 68}Ga-DOTA-octreotide in the normal pancreas. •{sup 68}Ga-DOTA-octreotide specifically binds to somatostatin receptors in the pancreas. •The pancreatic uptake of {sup 68}Ga-DOTA-octreotide was decreased in the diabetic rats. •{sup 68}Ga-DOTA-octreotide could be a candidate PET probe to measure the beta cell mass. -- Abstract: Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycemia, and the loss or dysfunction of pancreatic beta cells has been reported before the appearance of clinical symptoms and hyperglycemia. To evaluate beta cell mass (BCM) for improving the detection and treatment of DM at earlier stages, we focused on somatostatin receptors that are highly expressed in the pancreatic beta cells, and developed a positron emission tomography (PET) probe derived from octreotide, a metabolically stable somatostatin analog. Octreotide was conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), a chelating agent, and labeled with {sup 68}Gallium ({sup 68}Ga). After intravenous injection of {sup 68}Ga-DOTA-octreotide, a 90-min emission scan of the abdomen was performed in normal and DM model rats. The PET studies showed that {sup 68}Ga-DOTA-octreotide radioactivity was highly accumulated in the pancreas of normal rats and that the pancreatic accumulation was significantly reduced in the rats administered with an excess amount of unlabeled octreotide or after treatment with streptozotocin, which was used for the chemical induction of DM in rats. These results were in good agreement with the ex vivo biodistribution data. These results indicated that the pancreatic accumulation of {sup 68}Ga-DOTA-octreotide represented specific binding to the somatostatin receptors and reflected BCM. Therefore, PET imaging with {sup 68}Ga-DOTA-octreotide could be a potential tool for evaluating BCM.

  16. ADVANCES IN MOLECULAR IMAGING OF PANCREATIC BETA CELLS

    PubMed Central

    Lin, Mai; Lubag, Angelo; McGuire, Michael J.; Seliounine, Serguei Y.; Tsyganov, Edward N.; Antich, Peter P.; Sherry, A. Dean; Brown, Kathlynn C.; Sun, Xiankai

    2009-01-01

    The development of non-invasive imaging methods for early diagnosis of the beta cell associated metabolic diseases, including type 1 and type 2 diabetes (T1D and T2D), has recently drawn considerable interest from the molecular imaging community as well as clinical investigators. Due to the challenges imposed by the location of the pancreas, the sparsely dispersed beta cell population within the pancreas, and the poor understanding of the pathogenesis of the diseases, clinical diagnosis of beta cell abnormalities is still limited. Current diagnostic methods are invasive, often inaccurate, and usually performed post-onset of the disease. Advances in imaging techniques for probing beta cell mass and function are needed to address this critical health care problem. A variety of currently available imaging techniques have been tested for the assessment of the pancreatic beta cell islets. Here we discuss the current advances in magnetic resonance imaging (MRI), bioluminescence imaging (BLI), and nuclear imaging for the study of beta cell diseases. Spurred by early successes in nuclear imaging techniques for beta cells, especially positron emission tomography (PET), the need for beta cell specific ligands has expanded. Progress in the field for obtaining such ligands is presented. Additionally, we report our preliminary efforts of developing such a peptidic ligand for PET imaging of the pancreatic beta cells. PMID:18508529

  17. Pancreatic beta-cell hyperactivity in morbidly obese adolescents.

    PubMed

    Mercado, Arlene B; Castells, Salvador

    2006-12-01

    beta-cell hyperactivity, with increased beta-cell mass in the pancreas, contributes to insulin oversecretion in response to insulin resistance. beta-cell mass expansion, also known as "endocrine pancreas plasticity", is an adaptation to variations in insulin demand, is generally observed in obese persons and in women during late pregnancy. In obese persons, increased free fatty acids contribute to beta-cell growth. It is believed that type 2 diabetes develops in those persons unable to respond to an increased insulin demand with a high rate of beta-cell proliferation. Impairment of insulin secretion may originate from a genetic predisposition as well as aggravated by high lipid and glucose levels. Better understanding of endocrine pancreas plasticity and its regeneration mechanisms could lead to new treatment modalities for type 2 diabetes. Review of literature of pancreatic beta-cell hyperactivity in obesity and its existence in morbidly obese adolescents is hereby presented. PMID:17237743

  18. Arsenite reduces insulin secretion in rat pancreatic {beta}-cells by decreasing the calcium-dependent calpain-10 proteolysis of SNAP-25

    SciTech Connect

    Diaz-Villasenor, Andrea; Burns, Anna L.; Salazar, Ana Maria; Sordo, Monserrat; Hiriart, Marcia; Cebrian, Mariano E.; Ostrosky-Wegman, Patricia

    2008-09-15

    An increase in the prevalence of type 2 diabetes has been consistently observed among residents of high arsenic exposure areas. We have previously shown that in rat pancreatic {beta}-cells, low arsenite doses impair the secretion of insulin without altering its synthesis. To further study the mechanism by which arsenite reduces insulin secretion, we evaluated the effects of arsenite on the calcium-calpain pathway that triggers insulin exocytosis in RINm5F cells. Cell cycle and proliferation analysis were also performed to complement the characterization. Free [Ca{sup 2+}]i oscillations needed for glucose-stimulated insulin secretion were abated in the presence of subchronic low arsenite doses (0.5-2 {mu}M). The global activity of calpains increased with 2 {mu}M arsenite. However, during the secretion of insulin stimulated with glucose (15.6 mM), 1 {mu}M arsenite decreased the activity of calpain-10, measured as SNAP-25 proteolysis. Both proteins are needed to fuse insulin granules with the membrane to produce insulin exocytosis. Arsenite also induced a slowdown in the {beta} cell line proliferation in a dose-dependent manner, reflected by a reduction of dividing cells and in their arrest in G2/M. Data obtained showed that one of the mechanisms by which arsenite impairs insulin secretion is by decreasing the oscillations of free [Ca{sup 2+}]i, thus reducing calcium-dependent calpain-10 partial proteolysis of SNAP-25. The effects in cell division and proliferation observed with arsenite exposure can be an indirect consequence of the decrease in insulin secretion.

  19. Human Fucci Pancreatic Beta Cell Lines: New Tools to Study Beta Cell Cycle and Terminal Differentiation

    PubMed Central

    Carlier, Géraldine; Maugein, Alicia; Cordier, Corinne; Pechberty, Séverine; Garfa-Traoré, Meriem; Martin, Patrick; Scharfmann, Raphaël; Albagli, Olivier

    2014-01-01

    Regulation of cell cycle in beta cells is poorly understood, especially in humans. We exploited here the recently described human pancreatic beta cell line EndoC-βH2 to set up experimental systems for cell cycle studies. We derived 2 populations from EndoC-βH2 cells that stably harbor the 2 genes encoding the Fucci fluorescent indicators of cell cycle, either from two vectors, or from a unique bicistronic vector. In proliferating non-synchronized cells, the 2 Fucci indicators revealed cells in the expected phases of cell cycle, with orange and green cells being in G1 and S/G2/M cells, respectively, and allowed the sorting of cells in different substeps of G1. The Fucci indicators also faithfully red out alterations in human beta cell proliferative activity since a mitogen-rich medium decreased the proportion of orange cells and inflated the green population, while reciprocal changes were observed when cells were induced to cease proliferation and increased expression of some beta cell genes. In the last situation, acquisition of a more differentiated beta cell phenotype correlates with an increased intensity in orange fluorescence. Hence Fucci beta cell lines provide new tools to address important questions regarding human beta cell cycle and differentiation. PMID:25259951

  20. Proliferating pancreatic beta-cells upregulate ALDH.

    PubMed

    Liu, Yinglan; Jiang, Xiaoxin; Zeng, Yong; Zhou, Hui; Yang, Jing; Cao, Renxian

    2014-12-01

    High levels of aldehyde dehydrogenase (ALDH) activity have been regarded as a specific feature of progenitor cells and stem cells. Hence, as an indicator of ALDH activity, aldefluor fluorescence has been widely used for the identification and isolation of stem and progenitor cells. ALDH activity was recently detected in embryonic mouse pancreas, and specifically and exclusively in adult centroacinar and terminal duct cells, suggesting that these duct cells may harbor cells of endocrine and exocrine differentiation potential in the adult pancreas. Here, we report the presence of aldefluor+ beta-cells in a beta-cell proliferation model, partial pancreatectomy. The aldefluor+ beta-cells are essentially all positive for Ki-67 and expressed high levels of cell-cycle activators such as CyclinD1, CyclinD2, and CDK4, suggesting that they are mitotic cells. Our data thus reveal a potential change in ALDH activity of proliferating beta-cells, which provides a novel method for the isolation and analysis of proliferating beta-cells. Moreover, our data also suggest that aldefluor lineage-tracing is not a proper method for analyzing progenitor or stem activity in the adult pancreas. PMID:25028343

  1. Uncovering Factors Related to Pancreatic Beta-Cell Function

    PubMed Central

    Curran, Aoife M.; Ryan, Miriam F.; Drummond, Elaine; Gibney, Eileen R.; Gibney, Michael J.; Roche, Helen M.; Brennan, Lorraine

    2016-01-01

    Aim The incidence of type 2 diabetes has increased rapidly on a global scale. Beta-cell dysfunction contributes to the overall pathogenesis of type 2 diabetes. However, factors contributing to beta-cell function are not clear. The aims of this study were (i) to identify factors related to pancreatic beta-cell function and (ii) to perform mechanistic studies in vitro. Methods Three specific measures of beta-cell function were assessed for 110 participants who completed an oral glucose tolerance test as part of the Metabolic Challenge Study. Anthropometric and biochemical parameters were assessed as potential modulators of beta-cell function. Subsequent in vitro experiments were performed using the BRIN-BD11 pancreatic beta-cell line. Validation of findings were performed in a second human cohort. Results Waist-to-hip ratio was the strongest anthropometric modulator of beta-cell function, with beta-coefficients of -0.33 (p = 0.001) and -0.30 (p = 0.002) for beta-cell function/homeostatic model assessment of insulin resistance (HOMA-IR), and disposition index respectively. Additionally, the resistin-to-adiponectin ratio (RA index) emerged as being strongly associated with beta-cell function, with beta-coefficients of -0.24 (p = 0.038) and -0.25 (p = 0.028) for beta-cell function/HOMA-IR, and disposition index respectively. Similar results were obtained using a third measure for beta-cell function. In vitro experiments revealed that the RA index was a potent regulator of acute insulin secretion where a high RA index (20ng ml-1 resistin, 5nmol l-1 g-adiponectin) significantly decreased insulin secretion whereas a low RA index (10ng ml-1 resistin, 10nmol l-1 g-adiponectin) significantly increased insulin secretion. The RA index was successfully validated in a second human cohort with beta-coefficients of -0.40 (p = 0.006) and -0.38 (p = 0.008) for beta-cell function/ HOMA-IR, and disposition index respectively. Conclusions Waist-to-hip ratio and RA index were identified

  2. Conversion of adult pancreatic alpha-cells to beta-cells after extreme beta-cell loss.

    PubMed

    Thorel, Fabrizio; Népote, Virginie; Avril, Isabelle; Kohno, Kenji; Desgraz, Renaud; Chera, Simona; Herrera, Pedro L

    2010-04-22

    Pancreatic insulin-producing beta-cells have a long lifespan, such that in healthy conditions they replicate little during a lifetime. Nevertheless, they show increased self-duplication after increased metabolic demand or after injury (that is, beta-cell loss). It is not known whether adult mammals can differentiate (regenerate) new beta-cells after extreme, total beta-cell loss, as in diabetes. This would indicate differentiation from precursors or another heterologous (non-beta-cell) source. Here we show beta-cell regeneration in a transgenic model of diphtheria-toxin-induced acute selective near-total beta-cell ablation. If given insulin, the mice survived and showed beta-cell mass augmentation with time. Lineage-tracing to label the glucagon-producing alpha-cells before beta-cell ablation tracked large fractions of regenerated beta-cells as deriving from alpha-cells, revealing a previously disregarded degree of pancreatic cell plasticity. Such inter-endocrine spontaneous adult cell conversion could be harnessed towards methods of producing beta-cells for diabetes therapies, either in differentiation settings in vitro or in induced regeneration. PMID:20364121

  3. Adhesion of pancreatic beta cells to biopolymer films.

    PubMed

    Williams, S Janette; Wang, Qun; Macgregor, Ronal R; Siahaan, Teruna J; Stehno-Bittel, Lisa; Berkland, Cory

    2009-08-01

    Dramatic reversal of Type 1 diabetes in patients receiving pancreatic islet transplants continues to prompt vigorous research concerning the basic mechanisms underlying patient turnaround. At the most fundamental level, transplanted islets must maintain viability and function in vitro and in vivo and should be protected from host immune rejection. Our previous reports showed enhancement of islet viability and insulin secretion per tissue mass for small islets (<125 mum) as compared with large islets (>125 mum), thus, demonstrating the effect of enhancing the mass transport of islets (i.e. increasing tissue surface area to volume ratio). Here, we report the facile dispersion of rat islets into individual cells that are layered onto the surface of a biopolymer film towards the ultimate goal of improving mass transport in islet tissue. The tightly packed structure of intact islets was disrupted by incubating in calcium-free media resulting in fragmented islets, which were further dispersed into individual or small groups of cells by using a low concentration of papain. The dispersed cells were screened for adhesion to a range of biopolymers and the nature of cell adhesion was characterized for selected groups by quantifying adherent cells, measuring the surface area coverage of the cells, and immunolabeling cells for adhesion proteins interacting with selected biopolymers. Finally, beta cells in suspension were centrifuged to form controlled numbers of cell layers on films for future work determining the mass transport limitations in the adhered tissue constructs. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 676-685, 2009.This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com. PMID:19353639

  4. The effect of smoking cessation pharmacotherapies on pancreatic beta cell function

    SciTech Connect

    Woynillowicz, Amanda K.; Raha, Sandeep; Nicholson, Catherine J.; Holloway, Alison C.

    2012-11-15

    The goal of our study was to evaluate whether drugs currently used for smoking cessation (i.e., nicotine replacement therapy, varenicline [a partial agonist at nicotinic acetylcholine receptors (nAChR)] and bupropion [which acts in part as a nAChR antagonist]) can affect beta cell function and determine the mechanism(s) of this effect. INS-1E cells, a rat beta cell line, were treated with nicotine, varenicline and bupropion to determine their effects on beta cell function, mitochondrial electron transport chain enzyme activity and cellular/oxidative stress. Treatment of INS-1E cells with equimolar concentrations (1 μM) of three test compounds resulted in an ablation of normal glucose-stimulated insulin secretion by the cells. This disruption of normal beta cell function was associated with mitochondrial dysfunction since all three compounds tested significantly decreased the activity of mitochondrial electron transport chain enzyme activity. These results raise the possibility that the currently available smoking cessation pharmacotherapies may also have adverse effects on beta cell function and thus glycemic control in vivo. Therefore whether or not the use of nicotine replacement therapy, varenicline and bupropion can cause endocrine changes which are consistent with impaired pancreatic function warrants further investigation. -- Highlights: ► Smoking cessation drugs have the potential to disrupt beta cell function in vitro. ► The effects of nicotine, varenicline and bupropion are similar. ► The impaired beta cell function is mediated by mitochondrial dysfunction. ► If similar effects are seen in vivo, these drugs may increase the risk of diabetes.

  5. D-saccharic acid-1,4-lactone ameliorates alloxan-induced diabetes mellitus and oxidative stress in rats through inhibiting pancreatic beta-cells from apoptosis via mitochondrial dependent pathway

    SciTech Connect

    Bhattacharya, Semantee; Manna, Prasenjit; Sil, Parames C.

    2011-12-15

    Oxidative stress plays a vital role in diabetic complications. To suppress the oxidative stress mediated damage in diabetic pathophysiology, a special focus has been given on naturally occurring antioxidants present in normal diet. D-saccharic acid 1,4-lactone (DSL), a derivative of D-glucaric acid, is present in many dietary plants and is known for its detoxifying and antioxidant properties. The aim of the present study was to evaluate the beneficial role of DSL against alloxan (ALX) induced diabetes in the pancreas tissue of Swiss albino rats. A dose-dependent study for DSL (20-120 mg/kg body weight) was carried out to find the effective dose of the compound in ALX-induced diabetic rats. ALX exposure elevated the blood glucose, glycosylated Hb, decreased the plasma insulin and disturbed the intra-cellular antioxidant machineries whereas oral administration of DSL at a dose of 80 mg/kg body weight restored these alterations close to normal. Investigating the mechanism of the protective activity of DSL we observed that it prevented the pancreatic {beta}-cell apoptosis via mitochondria-dependent pathway. Results showed decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol and reciprocal regulation of Bcl-2 family proteins in the diabetic rats. These events were also found to be associated with increased level of Apaf-1, caspase 9, and caspase 3 that ultimately led to pancreatic {beta}-cell apoptosis. DSL treatment, however, counteracted these changes. In conclusion, DSL possesses the capability of ameliorating the oxidative stress in ALX-induced diabetes and thus could be a promising approach in lessening diabetic complications. Highlights: Black-Right-Pointing-Pointer Oxidative stress is suggested as a key event in the pathogenesis of diabetes. Black-Right-Pointing-Pointer D-saccharic acid 1,4-lactone (DSL) reduces the alloxan-induced diabetes mellitus. Black-Right-Pointing-Pointer DSL normalizes cellular antioxidant machineries

  6. Sodium arsenite impairs insulin secretion and transcription in pancreatic {beta}-cells

    SciTech Connect

    Diaz-Villasenor, Andrea; Sanchez-Soto, M. Carmen; Cebrian, Mariano E.; Ostrosky-Wegman, Patricia; Hiriart, Marcia . E-mail: mhiriart@ifc.unam.mx

    2006-07-01

    Human studies have shown that chronic inorganic arsenic (iAs) exposure is associated with a high prevalence and incidence of type 2 diabetes. However, the mechanism(s) underlying this effect are not well understood, and practically, there is no information available on the effects of arsenic on pancreatic {beta}-cells functions. Thus, since insulin secreted by the pancreas plays a crucial role in maintaining glucose homeostasis, our aim was to determine if sodium arsenite impairs insulin secretion and mRNA expression in single adult rat pancreatic {beta}-cells. Cells were treated with 0.5, 1, 2, 5 and 10 {mu}M sodium arsenite and incubated for 72 and 144 h. The highest dose tested (10 {mu}M) decreased {beta}-cell viability, by 33% and 83%, respectively. Insulin secretion and mRNA expression were evaluated in the presence of 1 and 5 {mu}M sodium arsenite. Basal insulin secretion, in 5.6 mM glucose, was not significantly affected by 1 or 5 {mu}M treatment for 72 h, but basal secretion was reduced when cells were exposed to 5 {mu}M sodium arsenite for 144 h. On the other hand, insulin secretion in response to 15.6 mM glucose decreased with sodium arsenite in a dose-dependent manner in such a way that cells were no longer able to distinguish between different glucose concentrations. We also showed a significant decrease in insulin mRNA expression of cells exposed to 5 {mu}M sodium arsenite during 72 h. Our data suggest that arsenic may contribute to the development of diabetes mellitus by impairing pancreatic {beta}-cell functions, particularly insulin synthesis and secretion.

  7. The role of autophagy in pancreatic beta-cell and diabetes.

    PubMed

    Fujitani, Yoshio; Kawamori, Ryuzo; Watada, Hirotaka

    2009-02-01

    Pancreatic beta-cells play a key role in glucose homeostasis in mammals. Although large-scale protein synthesis and degradation occur in pancreatic beta-cells, the mechanism underlying dynamic protein turnover in beta-cells remains largely unknown. We found low-level constitutive autophagy in beta-cells of C57BL/6 mice fed a standard diet; however, autophagy was markedly upregulated in mice fed a high-fat diet. beta-cells of diabetic db/db mice contained large numbers of autophagosomes, compared with nondiabetic db/misty controls. The functional importance of autophagy was analyzed using beta-cell-specific Atg7 knockout mice. Autophagy-deficient mice showed degeneration of beta-cells and impaired glucose tolerance with reduced insulin secretion. While a high-fat diet stimulated beta-cell autophagy in control mice, it induced a profound deterioration of glucose intolerance in beta-cell autophagy-deficient mutants, partly because of the lack of a compensatory increase in beta-cell mass. These results suggest that the degradation of unnecessary cellular components by autophagy is essential for maintenance of the architecture and function of beta-cells. Autophagy also serves as a crucial element of stress responses to protect beta-cells under insulin-resistant states. Impairment of autophagic machinery could thus predispose individuals to type 2 diabetes. PMID:19158492

  8. The reprogrammed pancreatic progenitor-like intermediate state of hepatic cells is more susceptible to pancreatic beta cell differentiation.

    PubMed

    Wang, Qiwei; Wang, Hai; Sun, Yu; Li, Shi-Wu; Donelan, William; Chang, Lung-Ji; Jin, Shouguang; Terada, Naohiro; Cheng, Henrique; Reeves, Westley H; Yang, Li-Jun

    2013-08-15

    Induced pluripotent stem cells (iPSCs) hold great promise for cell therapy. However, their low efficiency of lineage-specific differentiation and tumorigenesis severely hinder clinical translation. We hypothesized that reprogramming of somatic cells into lineage-specific progenitor cells might allow for large-scale expansion, avoiding the tumorigenesis inherent with iPSCs and simultaneously facilitating lineage-specific differentiation. Here we aimed at reprogramming rat hepatic WB cells, using four Yamanaka factors, into pancreatic progenitor cells (PPCs) or intermediate (IM) cells that have characteristics of PPCs. IM clones were selected based on their specific morphology and alkaline phosphatase activity and stably passaged under defined culture conditions. IM cells did not have iPSC properties, could be stably expanded in large quantity, and expressed all 14 genes that are used to define the PPC developmental stage. Directed differentiation of IM and WB cells by Pdx1-Ngn3-MafA (PNM) into pancreatic beta-like cells revealed that the IM cells are more susceptible to directed beta cell differentiation because of their open chromatin configuration, as demonstrated by expression of key pancreatic beta cell genes, secretion of insulin in response to glucose stimulation, and easy access to exogenous PNM proteins at the rat insulin 1 and Pdx1 promoters. This notion that IM cells are superior to their parental cells is further supported by the epigenetic demonstration of accessibility of Pdx1 and insulin 1 promoters. In conclusion, we have developed a strategy to derive and expand PPC cells from hepatic WB cells using conventional cell reprogramming. This proof-of-principal study may offer a novel, safe and effective way to generate autologous pancreatic beta cells for cell therapy of diabetes. PMID:23750005

  9. Cell therapies for pancreatic beta-cell replenishment.

    PubMed

    Okere, Bernard; Lucaccioni, Laura; Dominici, Massimo; Iughetti, Lorenzo

    2016-01-01

    The current treatment approach for type 1 diabetes is based on daily insulin injections, combined with blood glucose monitoring. However, administration of exogenous insulin fails to mimic the physiological activity of the islet, therefore diabetes often progresses with the development of serious complications such as kidney failure, retinopathy and vascular disease. Whole pancreas transplantation is associated with risks of major invasive surgery along with side effects of immunosuppressive therapy to avoid organ rejection. Replacement of pancreatic beta-cells would represent an ideal treatment that could overcome the above mentioned therapeutic hurdles. In this context, transplantation of islets of Langerhans is considered a less invasive procedure although long-term outcomes showed that only 10 % of the patients remained insulin independent five years after the transplant. Moreover, due to shortage of organs and the inability of islet to be expanded ex vivo, this therapy can be offered to a very limited number of patients. Over the past decade, cellular therapies have emerged as the new frontier of treatment of several diseases. Furthermore the advent of stem cells as renewable source of cell-substitutes to replenish the beta cell population, has blurred the hype on islet transplantation. Breakthrough cellular approaches aim to generate stem-cell-derived insulin producing cells, which could make diabetes cellular therapy available to millions. However, to date, stem cell therapy for diabetes is still in its early experimental stages. This review describes the most reliable sources of stem cells that have been developed to produce insulin and their most relevant experimental applications for the cure of diabetes. PMID:27400873

  10. Evidence for glucagon-like peptide-1 receptor signaling to activate ATP-sensitive potassium channels in pancreatic beta cells.

    PubMed

    Kwon, Hye-Jung; Park, Hyun-Sun; Park, Sung-Hee; Park, Jae-Hyung; Shin, Su-Kyung; Song, Seung Eun; Hwang, Meeyul; Cho, Ho-Chan; Song, Dae-Kyu

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) is a gut peptide that promotes insulin release from pancreatic beta cells. GLP-1 has been shown to confer glucose-insensitive beta cells with glucose sensitivity by modulation of the activity of the ATP-sensitive potassium (KATP) channel. The channel closing effect of GLP-1, interacting with corresponding G-protein-coupled receptors, has been well established; however, to our knowledge, no study has shown whether GLP-1 directly induces activation of beta-cell KATP channels. Here, we aimed to evaluate whether the activation of beta-cell KATP channels by GLP-1 exists and affects intracellular Ca(2+) levels ([Ca(2+)]i). KATP channel activity was measured in isolated rat pancreatic beta cells by whole-cell perforated patch-clamp recordings with a diazoxide-containing pipette solution. Changes in [Ca(2+)]i and the subcellular localization of KATP channels were observed using the calcium-sensitive dye fura-4/AM and anti-Kir6.2 antibodies in INS-1 beta cells, respectively. To eliminate the well-known inhibitory effects of GLP-1 on KATP channel activity, channels were fully inhibited by pretreatment with methyl pyruvate and epigallocatechin-3-gallate. In the pretreated beta cells, GLP-1 and exendin-4 promptly activated the channels, reducing [Ca(2+)]i. The phosphoinositide 3-kinase (PI3K) inhibitor LY294002 blocked the effects of GLP-1 on channel activity. Moreover, phosphatidylinositol-3,4,5-trisphosphate mimicked the effects of GLP-1. These results suggested that beta-cell GLP-1 receptor signaling involved activation of KATP channels via a PI3K-dependent pathway. This alternative mechanism of GLP-1 function may act as a negative feedback pathway, modulating the glucose-dependent GLP-1 inhibition on KATP channel activity. PMID:26655814

  11. Induction of human pancreatic beta cell replication by inhibitors of dual specificity tyrosine regulated kinase

    PubMed Central

    Wang, Peng; Alvarez-Perez, Juan-Carlos; Felsenfeld, Dan P.; Liu, Hongtao; Sivendran, Sharmila; Bender, Aaron; Kumar, Anil; Sanchez, Roberto; Scott, Donald K.; Garcia-Ocaña, Adolfo; Stewart, Andrew F.

    2015-01-01

    Types 1 and 2 diabetes affect some 380 million people worldwide. Both result ultimately from a deficiency of functional pancreatic insulin-producing beta cells. Beta cells proliferate in humans during a brief temporal window beginning around the time of birth, with peak beta cell labeling indices achieving approximately 2% in first year of life1-4. In embryonic life and after early childhood, beta cell replication rates are very low. While beta cell expansion seems an obvious therapeutic approach to beta cell deficiency, adult human beta cells have proven recalcitrant to such efforts1-8. Hence, there remains an urgent need for diabetes therapeutic agents that can induce regeneration and expansion of adult human beta cells in vivo or ex vivo. Here, we report the results of a high-throughput small molecule screen (HTS) revealing a novel class of human beta cell mitogenic compounds, analogues of the small molecule, harmine. We also define dual specificity tyrosine-regulated kinase-1a (DYRK1A) as the likely target of harmine, and the Nuclear Factors of activated T-cells (NFAT) family of transcription factors as likely mediators of human beta cell proliferation as well as beta cell differentiation. These observations suggest that harmine analogues (“harmalogs”) may have unique therapeutic promise for human diabetes therapy. Enhancing potency and beta cell specificity are important future challenges. PMID:25751815

  12. Radioiodinated Naphthylalanine Derivatives Targeting Pancreatic Beta Cells in Normal and Nonobese Diabetic Mice

    PubMed Central

    Amartey, John K.; Shi, Yufei; Al-Jammaz, Ibrahim; Esguerra, Celestina; Al-Otaibi, Basem; Al-Mohanna, Futwan

    2008-01-01

    An imaging method capable of using a signal from pancreatic beta cells to determine their mass would be of immense value in monitoring the progression of diabetes as well as response to treatment. Somatostatin receptors (SSTRs) are expressed on beta cells and are a potential target for imaging. The main objective of this study was to investigate whether pancreatic beta cells are a target for radiolabeled naphthylalanine derivatives. The molecules were subjected to in vitro and ex vivo evaluations. Pancreatic uptake of radioactivity was lower in nonobese diabetic (NOD) mice than normal mice at all time points investigated (P < .05) and correlated with the number of islets in tissue sections of both control and NOD mice. Immunohistochemical and confocal fluorescent microscopic studies showed colocalization of insulin and the conjugate radioligand in the pancreas. The results demonstrated that pancreatic uptake is receptor-mediated, and that beta cells are the primary target. PMID:18483609

  13. Pancreatic beta cell function in the fetal pig and sow.

    PubMed

    Fowden, A L; Comline, R S; Silver, M

    1982-04-01

    Insulin secretion was investigated in acutely anaesthetized and chronically catheterized sows and their fetuses during late gestation. In the conscious animals, the mean fetal concentration of plasma insulin was 8.4 +/- 1.5 microunits/ml which was significantly less than the corresponding maternal value of 33.9 +/- 6.5 microunits/ml (n = 12, P less than 0.01). The plasma concentrations of insulin and glucose in the new-born piglets from these litters were not significantly different from the values observed in utero. The plasma concentration of insulin in the anaesthetized fetuses was significantly less than that in the chronically catheterized piglets over the same range of glucose levels. In the chronically catheterized animals, both fetal and maternal levels of insulin rose with increasing concentrations of plasma glucose while under acute conditions there was no correlation between the endogenous concentrations of insulin and glucose in either the fetuses or their mothers. Infusion of exogenous glucose (0.5 g as a 50% solution in 0.9% NaCl) stimulated the release of insulin in all the chronically catheterized fetuses studied but rarely increased the concentration of insulin in the anaesthetized fetusus. The present findings show that anaesthesia and surgery depress pancreatic beta cell function in the pig, particularly in the fetus. PMID:7043523

  14. Cocoa Phenolic Extract Protects Pancreatic Beta Cells against Oxidative Stress

    PubMed Central

    Martín, María Ángeles; Ramos, Sonia; Cordero-Herrero, Isabel; Bravo, Laura; Goya, Luis

    2013-01-01

    Diabetes mellitus is associated with reductions in glutathione, supporting the critical role of oxidative stress in its pathogenesis. Antioxidant food components such as flavonoids have a protective role against oxidative stress-induced degenerative and age-related diseases. Flavonoids constitute an important part of the human diet; they can be found in most plant foods, including green tea, grapes or cocoa and possess multiple biological activities. This study investigates the chemo-protective effect of a cocoa phenolic extract (CPE) containing mainly flavonoids against oxidative stress induced by tert-butylhydroperoxide (t-BOOH) on Ins-1E pancreatic beta cells. Cell viability and oxidative status were evaluated. Ins-1E cells treatment with 5–20 μg/mL CPE for 20 h evoked no cell damage and did not alter ROS production. Addition of 50 μM t-BOOH for 2 h increased ROS and carbonyl groups content and decreased reduced glutathione level. Pre-treatment of cells with CPE significantly prevented the t-BOOH-induced ROS and carbonyl groups and returned antioxidant defences to adequate levels. Thus, Ins-1E cells treated with CPE showed a remarkable recovery of cell viability damaged by t-BOOH, indicating that integrity of surviving machineries in the CPE-treated cells was notably protected against the oxidative insult. PMID:23912326

  15. Cell-type, allelic, and genetic signatures in the human pancreatic beta cell transcriptome.

    PubMed

    Nica, Alexandra C; Ongen, Halit; Irminger, Jean-Claude; Bosco, Domenico; Berney, Thierry; Antonarakis, Stylianos E; Halban, Philippe A; Dermitzakis, Emmanouil T

    2013-09-01

    Elucidating the pathophysiology and molecular attributes of common disorders as well as developing targeted and effective treatments hinges on the study of the relevant cell type and tissues. Pancreatic beta cells within the islets of Langerhans are centrally involved in the pathogenesis of both type 1 and type 2 diabetes. Describing the differentiated state of the human beta cell has been hampered so far by technical (low resolution microarrays) and biological limitations (whole islet preparations rather than isolated beta cells). We circumvent these by deep RNA sequencing of purified beta cells from 11 individuals, presenting here the first characterization of the human beta cell transcriptome. We perform the first comparison of gene expression profiles between beta cells, whole islets, and beta cell depleted islet preparations, revealing thus beta-cell-specific expression and splicing signatures. Further, we demonstrate that genes with consistent increased expression in beta cells have neuronal-like properties, a signal previously hypothesized. Finally, we find evidence for extensive allelic imbalance in expression and uncover genetic regulatory variants (eQTLs) active in beta cells. This first molecular blueprint of the human beta cell offers biological insight into its differentiated function, including expression of key genes associated with both major types of diabetes. PMID:23716500

  16. Unraveling the contribution of pancreatic beta-cell suicide in autoimmune type 1 diabetes✩

    PubMed Central

    Jaberi-Douraki, Majid; Schnell, Santiago; Pietropaolo, Massimo; Khadra, Anmar

    2014-01-01

    In type 1 diabetes, an autoimmune disease mediated by autoreactive T-cells that attack insulin-secreting pancreatic beta-cells, it has been suggested that disease progression may additionally require protective mechanisms in the target tissue to impede such auto-destructive mechanisms. We hypothesize that the autoimmune attack against beta-cells causes endoplasmic reticulum stress by forcing the remaining beta-cells to synthesize and secrete defective insulin. To rescue beta-cell from the endoplasmic reticulum stress, beta-cells activate the unfolded protein response to restore protein homeostasis and normal insulin synthesis. Here we investigate the compensatory role of unfolded protein response by developing a multi-state model of type 1 diabetes that takes into account beta-cell destruction caused by pathogenic autoreactive T-cells and apoptosis triggered by endoplasmic reticulum stress. We discuss the mechanism of unfolded protein response activation and how it counters beta-cell extinction caused by an autoimmune attack and/or irreversible damage by endoplasmic reticulum stress. Our results reveal important insights about the balance between beta-cell destruction by autoimmune attack (beta-cell homicide) and beta-cell apoptosis by endoplasmic reticulum stress (beta-cell suicide). It also provides an explanation as to why the unfolded protein response may not be a successful therapeutic target to treat type 1 diabetes. PMID:24831415

  17. Influence and timing of arrival of murine neural crest on pancreatic beta cell development and maturation.

    PubMed

    Plank, Jennifer L; Mundell, Nathan A; Frist, Audrey Y; LeGrone, Alison W; Kim, Thomas; Musser, Melissa A; Walter, Teagan J; Labosky, Patricia A

    2011-01-15

    Interactions between cells from the ectoderm and mesoderm influence development of the endodermally-derived pancreas. While much is known about how mesoderm regulates pancreatic development, relatively little is understood about how and when the ectodermally-derived neural crest regulates pancreatic development and specifically, beta cell maturation. A previous study demonstrated that signals from the neural crest regulate beta cell proliferation and ultimately, beta cell mass. Here, we expand on that work to describe timing of neural crest arrival at the developing pancreatic bud and extend our knowledge of the non-cell autonomous role for neural crest derivatives in the process of beta cell maturation. We demonstrated that murine neural crest entered the pancreatic mesenchyme between the 26 and 27 somite stages (approximately 10.0 dpc) and became intermingled with pancreatic progenitors as the epithelium branched into the surrounding mesenchyme. Using a neural crest-specific deletion of the Forkhead transcription factor Foxd3, we ablated neural crest cells that migrate to the pancreatic primordium. Consistent with previous data, in the absence of Foxd3, and therefore the absence of neural crest cells, proliferation of insulin-expressing cells and insulin-positive area are increased. Analysis of endocrine cell gene expression in the absence of neural crest demonstrated that, although the number of insulin-expressing cells was increased, beta cell maturation was significantly impaired. Decreased MafA and Pdx1 expression illustrated the defect in beta cell maturation; we discovered that without neural crest, there was a reduction in the percentage of insulin-positive cells that co-expressed Glut2 and Pdx1 compared to controls. In addition, transmission electron microscopy analyses revealed decreased numbers of characteristic insulin granules and the presence of abnormal granules in insulin-expressing cells from mutant embryos. Together, these data demonstrate that

  18. Influence and timing of arrival of murine neural crest on pancreatic beta cell development and maturation

    PubMed Central

    Plank, Jennifer L.; Mundell, Nathan A.; Frist, Audrey Y.; LeGrone, Alison W.; Kim, Thomas; Musser, Melissa A.; Walter, Teagan J.; Labosky, Patricia A.

    2010-01-01

    Interactions between cells from the ectoderm and mesoderm influence development of the endodermally-derived pancreas. While much is known about how mesoderm regulates pancreatic development, relatively little is understood about how and when the ectodermally-derived neural crest regulates pancreatic development and specifically, beta cell maturation. A previous study demonstrated that signals from the neural crest regulate beta cell proliferation and ultimately, beta cell mass. Here, we expand on that work to describe timing of neural crest arrival at the developing pancreatic bud and extend our knowledge of the non-cell autonomous role for neural crest derivatives in the process of beta cell maturation. We demonstrated that murine neural crest entered the pancreatic mesenchyme between the 26 and 27 somite stages (approximately 10.0 dpc) and became intermingled with pancreatic progenitors as the epithelium branched into the surrounding mesenchyme. Using a neural crest-specific deletion of the Forkhead transcription factor Foxd3, we ablated neural crest cells that migrate to the pancreatic primordium. Consistent with previous data, in the absence of Foxd3, and therefore the absence of neural crest cells, proliferation of Insulin-expressing cells and Insulin-positive area are increased. Analysis of endocrine cell gene expression in the absence of neural crest demonstrated that, although the number of Insulin-expressing cells was increased, beta cell maturation was significantly impaired. Decreased MafA and Pdx1 expression illustrated the defect in beta cell maturation; we discovered that without neural crest, there was a reduction in the percentage of Insulin-positive cells that co-expressed Glut2 and Pdx1 compared to controls. In addition, transmission electron microscopy analyses revealed decreased numbers of characteristic Insulin granules and the presence of abnormal granules in Insulin-expressing cells from mutant embryos. Together, these data demonstrate that

  19. Glucose activates prenyltransferases in pancreatic islet {beta}-cells

    SciTech Connect

    Goalstone, Marc; Kamath, Vasudeva; Kowluru, Anjaneyulu

    2010-01-01

    A growing body of evidence implicates small G-proteins [e.g., Cdc42 and Rac1] in glucose-stimulated insulin secretion [GSIS] in the islet {beta}-cell. These signaling proteins undergo post-translational modifications [e.g., prenylation] at their C-terminal cysteine residue and appear to be essential for the transport and fusion of insulin-containing secretory granules with the plasma membrane and the exocytotic secretion of insulin. However, potential regulation of the prenylating enzymes by physiological insulin secretogues [e.g., glucose] has not been investigated thus far. Herein, we report immunological localization, sub-cellular distribution and regulation of farnesyltransferases [FTases] and geranylgeranyltransferase [GGTase] by glucose in insulin-secreting INS 832/13 {beta}-cells and normal rat islets. Our findings suggest that an insulinotropic concentration of glucose [20 mM] markedly stimulated the expression of the {alpha}-subunits of FTase/GGTase-1, but not the {beta}-subunits of FTase or GGTase-1 without significantly affecting the predominantly cytosolic distribution of these holoenzymes in INS 832/13 cells and rodent islets. Under these conditions, glucose significantly stimulated [2.5- to 4.0-fold over basal] the activities of both FTase and GGTase-1 in both cell types. Together, these findings provide the first evidence to suggest that GSIS involves activation of the endogenous islet prenyltransferases by glucose, culminating in the activation of their respective G-protein substrates, which is necessary for cytoskeletal rearrangement, vesicular transport, fusion and secretion of insulin.

  20. Phenylpropenoic Acid Glucoside from Rooibos Protects Pancreatic Beta Cells against Cell Death Induced by Acute Injury

    PubMed Central

    Himpe, Eddy; Cunha, Daniel A.; Song, Imane; Bugliani, Marco; Marchetti, Piero; Cnop, Miriam; Bouwens, Luc

    2016-01-01

    Objective Previous studies demonstrated that a phenylpropenoic acid glucoside (PPAG) from rooibos (Aspalathus linearis) extract had anti-hyperglycemic activity and significant protective effects on the pancreatic beta cell mass in a chronic diet-induced diabetes model. The present study evaluated the cytoprotective effect of the phytochemical on beta cells exposed to acute cell stress. Methods Synthetically prepared PPAG was administered orally in mice treated with a single dose of streptozotocin to acutely induce beta cell death and hyperglycemia. Its effect was assessed on beta cell mass, proliferation and apoptotic cell death. Its cytoprotective effect was also studied in vitro on INS-1E beta cells and on human pancreatic islet cells. Results Treatment with the phytochemical PPAG protected beta cells during the first days after the insult against apoptotic cell death, as evidenced by TUNEL staining, and prevented loss of expression of anti-apoptotic protein BCL2 in vivo. In vitro, PPAG protected INS-1E beta cells from streptozotocin-induced apoptosis and necrosis in a BCL2-dependent and independent way, respectively, depending on glucose concentration. PPAG also protected human pancreatic islet cells against the cytotoxic action of the fatty acid palmitate. Conclusions These findings show the potential use of PPAG as phytomedicine which protects the beta cell mass exposed to acute diabetogenic stress. PMID:27299564

  1. Update on the protective molecular pathways improving pancreatic beta-cell dysfunction.

    PubMed

    Puddu, Alessandra; Sanguineti, Roberta; Mach, François; Dallegri, Franco; Viviani, Giorgio Luciano; Montecucco, Fabrizio

    2013-01-01

    The primary function of pancreatic beta-cells is to produce and release insulin in response to increment in extracellular glucose concentrations, thus maintaining glucose homeostasis. Deficient beta-cell function can have profound metabolic consequences, leading to the development of hyperglycemia and, ultimately, diabetes mellitus. Therefore, strategies targeting the maintenance of the normal function and protecting pancreatic beta-cells from injury or death might be crucial in the treatment of diabetes. This narrative review will update evidence from the recently identified molecular regulators preserving beta-cell mass and function recovery in order to suggest potential therapeutic targets against diabetes. This review will also highlight the relevance for novel molecular pathways potentially improving beta-cell dysfunction. PMID:23737653

  2. Transcriptome landmarks of the functional maturity of rat beta-cells, from lactation to adulthood.

    PubMed

    Larqué, Carlos; Velasco, Myrian; Barajas-Olmos, Francisco; García-Delgado, Neyvis; Chávez-Maldonado, Juan Pablo; García-Morales, Jazmín; Orozco, Lorena; Hiriart, Marcia

    2016-07-01

    Research on the postnatal development of pancreatic beta-cells has become an important subject in recent years. Understanding the mechanisms that govern beta-cell postnatal maturation could bring new opportunities to therapeutic approaches for diabetes. The weaning period consists of a critical postnatal window for structural and physiologic maturation of rat beta-cells. To investigate transcriptome changes involved in the maturation of beta-cells neighboring this period, we performed microarray analysis in fluorescence-activated cell-sorted (FACS) beta-cell-enriched populations. Our results showed a variety of gene sets including those involved in the integration of metabolism, modulation of electrical activity, and regulation of the cell cycle that play important roles in the maturation process. These observations were validated using reverse hemolytic plaque assay, electrophysiological recordings, and flow cytometry analysis. Moreover, we suggest some unexplored pathways such as sphingolipid metabolism, insulin-vesicle trafficking, regulation of transcription/transduction by miRNA-30, trafficking proteins, and cell cycle proteins that could play important roles in the process mentioned above for further investigation. PMID:27220619

  3. Pancreatic beta cells express a diverse set of homeobox genes.

    PubMed Central

    Rudnick, A; Ling, T Y; Odagiri, H; Rutter, W J; German, M S

    1994-01-01

    Homeobox genes, which are found in all eukaryotic organisms, encode transcriptional regulators involved in cell-type differentiation and development. Several homeobox genes encoding homeodomain proteins that bind and activate the insulin gene promoter have been described. In an attempt to identify additional beta-cell homeodomain proteins, we designed primers based on the sequences of beta-cell homeobox genes cdx3 and lmx1 and the Drosophila homeodomain protein Antennapedia and used these primers to amplify inserts by PCR from an insulinoma cDNA library. The resulting amplification products include sequences encoding 10 distinct homeodomain proteins; 3 of these proteins have not been described previously. In addition, an insert was obtained encoding a splice variant of engrailed-2, a homeodomain protein previously identified in the central nervous system. Northern analysis revealed a distinct pattern of expression for each homeobox gene. Interestingly, the PCR-derived clones do not represent a complete sampling of the beta-cell library because no inserts encoding cdx3 or lmx1 protein were obtained. Beta cells probably express additional homeobox genes. The abundance and diversity of homeodomain proteins found in beta cells illustrate the remarkable complexity and redundancy of the machinery controlling beta-cell development and differentiation. Images PMID:7991607

  4. A role for G(z) in pancreatic islet beta-cell biology.

    PubMed

    Kimple, Michelle E; Nixon, Andrew B; Kelly, Patrick; Bailey, Candice L; Young, Kenneth H; Fields, Timothy A; Casey, Patrick J

    2005-09-01

    Glucose-stimulated insulin secretion and beta-cell growth are important facets of pancreatic islet beta-cell biology. As a result, factors that modulate these processes are of great interest for the potential treatment of Type 2 diabetes. Here, we present evidence that the heterotrimeric G protein G(z) and its effectors, including some previously thought to be confined in expression to neuronal cells, are present in pancreatic beta-cells, the largest cellular constituent of the islets of Langerhans. Furthermore, signaling pathways upon which G alpha(z) impacts are intact in beta-cells, and G alpha(z) activation inhibits both cAMP production and glucose-stimulated insulin secretion in the Ins-1(832/13) beta-cell-derived line. Inhibition of glucose-stimulated insulin secretion by prostaglandin E (PGE1) is pertussis-toxin insensitive, indicating that other G alpha(i) family members are not involved in this process in this beta-cell line. Indeed, overexpression of a selective deactivator of G alpha(z), the RGS domain of RGSZ1, blocks the inhibitory effect of PGE1 on glucose-stimulated insulin secretion. Finally, the inhibition of glucose-stimulated insulin secretion by PGE1 is substantially blunted by small interfering RNA-mediated knockdown of G alpha(z) expression. Taken together, these data strongly imply that the endogenous E prostanoid receptor in the Ins-1(832/13) beta-cell line couples to G(z) predominantly and perhaps even exclusively. These data provide the first evidence for G(z) signaling in pancreatic beta-cells, and identify an endogenous receptor-mediated signaling process in beta-cells that is dependent on G alpha(z) function. PMID:16157560

  5. Plant-Derived Compounds Targeting Pancreatic Beta Cells for the Treatment of Diabetes

    PubMed Central

    Oh, Yoon Sin

    2015-01-01

    Diabetes is a global health problem and a national economic burden. Although several antidiabetic drugs are available, the need for novel therapeutic agents with improved efficacy and few side effects remains. Drugs derived from natural compounds are more attractive than synthetic drugs because of their diversity and minimal side effects. This review summarizes the most relevant effects of various plant-derived natural compounds on the functionality of pancreatic beta cells. Published data suggest that natural compounds directly enhance insulin secretion, prevent pancreatic beta cell apoptosis, and modulate pancreatic beta cell differentiation and proliferation. It is essential to continuously investigate natural compounds as sources of novel pharmaceuticals. Therefore, more studies into these compounds' mechanisms of action are warranted for their development as potential anti-diabetics. PMID:26587047

  6. Ryanodine receptors are involved in nuclear calcium oscillation in primary pancreatic {beta}-cells

    SciTech Connect

    Zheng, Ji; Chen, Zheng; Yin, Wenxuan; Miao, Lin; Zhou, Zhansong; Ji, Guangju

    2012-06-29

    Highlights: Black-Right-Pointing-Pointer We found that RyRs are expressed on the nuclear envelope in single primary pancreatic {beta}-cells and isolated nuclei. Black-Right-Pointing-Pointer We showed that the pattern of glucose-induced Ca{sup 2+} oscillation in the nucleus and cytosol was similar. Black-Right-Pointing-Pointer Our results demonstrate that ryanodine-sensitive Ca{sup 2+} stores exist and have function in the pancreatic {beta}-cell nucleus. -- Abstract: Ryanodine receptors (RyRs) are mainly located on the endoplasmic reticulum (ER) and play an important role in regulating glucose-induced cytosolic Ca{sup 2+} oscillation in pancreatic {beta}-cells. However, subcellular locations and functions of RyRs on other cell organelles such as nuclear envelope are not well understood. In order to investigate the role of RyRs in nuclear Ca{sup 2+} oscillation we designed and conducted experiments in intact primary pancreatic {beta}-cells. Immunocytochemistry was used to examine the expression of RYRs on the nuclear envelope. Confocal microscopy was used to evaluate the function of RYRs on the nuclear envelope. We found that RyRs are expressed on the nuclear envelope in single primary pancreatic {beta}-cells and isolated nuclei. Laser scanning confocal microscopy studies indicated that application of glucose to the cells co-incubated with Ca{sup 2+} indicator Fluo-4 AM and cell-permeable nuclear indicator Hoechst 33342 resulted in nuclear Ca{sup 2+} oscillation. The pattern of glucose-induced Ca{sup 2+} oscillation in the nucleus and cytosol was similar. The reduction of Ca{sup 2+} oscillation amplitude by ryanodine was much greater in the nucleus though both the cytosol and the nucleus Ca{sup 2+} amplitude decreased by ryanodine. Our results suggest that functional ryanodine receptors not only exist in endoplasmic reticulum but are also expressed in nuclear envelope of pancreatic {beta}-cells.

  7. On the coherent behavior of pancreatic beta cell clusters

    NASA Astrophysics Data System (ADS)

    Loppini, Alessandro; Capolupo, Antonio; Cherubini, Christian; Gizzi, Alessio; Bertolaso, Marta; Filippi, Simonetta; Vitiello, Giuseppe

    2014-09-01

    Beta cells in pancreas represent an example of coupled biological oscillators which via communication pathways, are able to synchronize their electrical activity, giving rise to pulsatile insulin release. In this work we numerically analyze scale free self-similarity features of membrane voltage signal power density spectrum, through a stochastic dynamical model for beta cells in the islets of Langerhans fine tuned on mouse experimental data. Adopting the algebraic approach of coherent state formalism, we show how coherent molecular domains can arise from proper functional conditions leading to a parallelism with “phase transition” phenomena of field theory.

  8. The expression and function of histamine H3 receptors in pancreatic beta cells

    PubMed Central

    Nakamura, T; Yoshikawa, T; Noguchi, N; Sugawara, A; Kasajima, A; Sasano, H; Yanai, K

    2014-01-01

    BACKGROUND AND PURPOSE Histamine and its receptors in the CNS play important roles in energy homeostasis. Here, we have investigated the expression and role of histamine receptors in pancreatic beta cells, which secrete insulin. EXPERIMENTAL APPROACH The expression of histamine receptors in pancreatic beta cells was examined by RT-PCR, Western blotting and immunostaining. Insulin secretion assay, ATP measurement and calcium imaging studies were performed to determine the function and signalling pathway of histamine H3 receptors in glucose-induced insulin secretion (GIIS) from MIN6 cells, a mouse pancreatic beta cell line. The function and signalling pathway of H3 receptors in MIN6 cell proliferation were examined using pharmacological assay and Western blotting. KEY RESULTS Histamine H3 receptors were expressed in pancreatic beta cells. A selective H3 receptor agonist, imetit, and a selective inverse H3 receptor agonist, JNJ-5207852, had inhibitory and facilitatory effects, respectively, on GIIS in MIN6 cells. Neither imetit nor JNJ-5207852 altered intracellular ATP concentration, or intracellular calcium concentration stimulated by glucose and KCl, indicating that GIIS signalling was affected by H3 receptor signalling downstream of the increase in intracellular calcium concentration. Moreover, imetit attenuated bromodeoxyuridine incorporation in MIN6 cells. The phosphorylation of cAMP response element-binding protein (CREB), which facilitated beta cell proliferation, was inhibited, though not significantly, by imetit, indicating that activated H3 receptors inhibited MIN6 cell proliferation, possibly by decreasing CREB phosphorylation. CONCLUSIONS AND IMPLICATIONS Histamine H3 receptors were expressed in mouse beta cells and could play a role in insulin secretion and, possibly, beta cell proliferation. PMID:24117016

  9. ROS signaling, oxidative stress and Nrf2 in pancreatic beta-cell function

    SciTech Connect

    Pi Jingbo; Zhang Qiang; Fu Jingqi; Woods, Courtney G.; Hou Yongyong; Corkey, Barbara E.; Collins, Sheila; Andersen, Melvin E.

    2010-04-01

    This review focuses on the emerging evidence that reactive oxygen species (ROS) derived from glucose metabolism, such as H{sub 2}O{sub 2}, act as metabolic signaling molecules for glucose-stimulated insulin secretion (GSIS) in pancreatic beta-cells. Particular emphasis is placed on the potential inhibitory role of endogenous antioxidants, which rise in response to oxidative stress, in glucose-triggered ROS and GSIS. We propose that cellular adaptive response to oxidative stress challenge, such as nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant induction, plays paradoxical roles in pancreatic beta-cell function. On the one hand, induction of antioxidant enzymes protects beta-cells from oxidative damage and possible cell death, thus minimizing oxidative damage-related impairment of insulin secretion. On the other hand, the induction of antioxidant enzymes by Nrf2 activation blunts glucose-triggered ROS signaling, thus resulting in reduced GSIS. These two premises are potentially relevant to impairment of beta-cells occurring in the late and early stage of Type 2 diabetes, respectively. In addition, we summarized our recent findings that persistent oxidative stress due to absence of uncoupling protein 2 activates cellular adaptive response which is associated with impaired pancreatic beta-cell function.

  10. Pituitary tumor transforming gene-null male mice exhibit impaired pancreatic beta cell proliferation and diabetes

    PubMed Central

    Wang, Zhiyong; Moro, Enrico; Kovacs, Kalman; Yu, Run; Melmed, Shlomo

    2003-01-01

    The mammalian securin, pituitary tumor transforming gene (PTTG), regulates sister chromatid separation during mitosis. Mice or cell lines deficient in PTTG expression, however, are surprisingly viable. Here we show that PTTG disruption in mice (PTTG−/−) severely impairs glucose homeostasis leading to diabetes during late adulthood, especially in males associated with nonautoimmune insulinopenia and reversed alpha/beta cell ratio. Islet beta cell mass in PTTG−/− mice was already diminished before development of frank diabetes and only increased minimally during growth. BrdUrd incorporation of islet cells in PTTG-null mice was ≈65% lower (P < 0.005) than in the WT pancreas, whereas apoptosis rates were similar. PTTG−/− beta cells had pleiotropic nuclei, suggesting defects in cell division. The results indicated that securin is indispensable for normal pancreatic beta cell proliferation. PMID:12626748

  11. Generating pancreatic beta-cells from embryonic stem cells by manipulating signaling pathways.

    PubMed

    Champeris Tsaniras, Spyridon; Jones, Peter M

    2010-07-01

    Type 1 diabetes results from an insufficiency of insulin production as a result of autoimmune destruction of the insulin-secreting pancreatic beta-cells. It can be treated by transplantation of islets of Langerhans from human donors, but widespread application of this therapy is restricted by the scarcity of donor tissue. Generation of functional beta-cells from embryonic stem (ES) cells in vitro could provide a source of an alternative graft material. Several ES cell differentiation protocols have reported the production of insulin-producing cells by mimicking the in vivo developmental stages of pancreatic organogenesis in which cells are transitioned through mesendoderm, definitive endoderm, foregut endoderm, pancreatic endoderm, and the endocrine precursor stage, until mature beta-cells are obtained. These studies provide proof of concept that recapitulating pancreatic development in vitro offers a useful strategy for generating beta-cells, but current differentiation protocols employ a bewildering variety of growth factors, mitogens, and pharmacological agents. In this review, we will attempt to clarify the functions of these agents in in vitro differentiation strategies by focusing on the intracellular signaling pathways through which they operate - phosphatidylinositol 3-kinase, transforming growth factor beta, Wnt/beta-catenin, Hedgehog, and Notch. PMID:20385725

  12. Pigment epithelium-derived factor (PEDF) regulates metabolism and insulin secretion from a clonal rat pancreatic beta cell line BRIN-BD11 and mouse islets.

    PubMed

    Chen, Younan; Carlessi, Rodrigo; Walz, Nikita; Cruzat, Vinicius Fernandes; Keane, Kevin; John, Abraham N; Jiang, Fang-Xu; Carnagarin, Revathy; Dass, Crispin R; Newsholme, Philip

    2016-05-01

    Pigment epithelium-derived factor (PEDF) is a multifunctional glycoprotein, associated with lipid catabolism and insulin resistance. In the present study, PEDF increased chronic and acute insulin secretion in a clonal rat β-cell line BRIN-BD11, without alteration of glucose consumption. PEDF also stimulated insulin secretion from primary mouse islets. Seahorse flux analysis demonstrated that PEDF did not change mitochondrial respiration and glycolytic function. The cytosolic presence of the putative PEDF receptor - adipose triglyceride lipase (ATGL) - was identified, and ATGL associated stimulation of glycerol release was robustly enhanced by PEDF, while intracellular ATP levels increased. Addition of palmitate or ex vivo stimulation with inflammatory mediators induced β-cell dysfunction, effects not altered by the addition of PEDF. In conclusion, PEDF increased insulin secretion in BRIN-BD11 and islet cells, but had no impact on glucose metabolism. Thus elevated lipolysis and enhanced fatty acid availability may impact insulin secretion following PEDF receptor (ATGL) stimulation. PMID:26868448

  13. Insulin-producing cells could not mimic the physiological regulation of insulin secretion performed by pancreatic beta cells

    PubMed Central

    2013-01-01

    Objective The aim of this study was to compare the difference between insulin-producing cells (IPCs) and normal human pancreatic beta cells both in physiological function and morphological features in cellular level. Methods The levels of insulin secretion were measured by enzyme-linked immunosorbent assay. The insulin gene expression was determined by real-time quantitative polymerase chain reaction. The morphological features were detected by atomic force microscopy (AFM) and laser confocal scanning microscopy. Results IPCs and normal human pancreatic beta cells were similar to each other under the observation in AFM with the porous structure features in the cytoplasm. Both number of membrane particle size and average roughness of normal human beta cells were higher than those of IPCs. Conclusions Our results firstly revealed that the cellular ultrastructure of IPCs was closer to that of normal human pancreatic beta cells, but they still could not mimic the physiological regulation of insulin secretion performed by pancreatic beta cells. PMID:23421382

  14. [A preliminary study on the mechanism of impaired beta cell function in monosodium glutamate obese rat with insulin resistance].

    PubMed

    Liu, Shuai-Nan; Liu, Quan; Shen, Zhu-Fang

    2008-11-01

    This study is to evaluate beta cell function and investigate the mechanism of impaired pancreatic islet beta cell function in monosodium glutamate (MSG) obese rat with insulin resistance, an animal model of metabolic syndrome. Insulin tolerance test was used to screen MSG obese rats with insulin resistance. Blood concentrations of glucose, triglyceride, total cholesterol and insulin were determined. Beta cell function was assessed with hyperglycemic clamp technique. The morphological alterations in pancreas and changes of islet beta cell mass were evaluated by hematoxylin-eosin (HE) and Gomori aldehyde fuchsin staining. Lipid, oxidative stress relevant factors, nitric oxide (NO) level and activity of ATPase in pancreas and pancreatic mitochondrial were tested. The MSG obese rats with insulin resistance could be validated as a typical metabolic syndrome animal model possessing increased fasting plasma triglycerides and insulin (P < 0. 001), markedly decreased weight indices of pancreas and impaired glucose-stimulated insulin secretion. Hematoxylin-eosin (HE) and Gomori aldehyde fuchsin staining showed increased adipocytes and fibroplasia deposition in pancreas and reduced beta cell mass. The increased contents of triglyceride and NO level, the decreased SOD levels and activities of total ATPase (P < 0.001), Na+-K+-ATPase (P < 0.001) and Ca2+-Mg2+-ATPase (P < 0.01) were observed in pancreas and its mitochondria versus normal rat. The study demonstrates that accumulation of lipids in pancreas could lead to increased systemic indicators of inflammation, such as NO, which may influence the activities of several kinds of ATPase in cell membranes and interfere the ion transport, substance metabolism and energy production in pancreas. Finally the MSG obese rats characterized with metabolic syndrome displayed an impairment of beta cell function. PMID:19239028

  15. Islet-selectivity of G-protein coupled receptor ligands evaluated for PET imaging of pancreatic {beta}-cell mass

    SciTech Connect

    Cline, Gary W.; Zhao, Xiaojian; Jakowski, Amy B.; Soeller, Walter C.; Treadway, Judith L.

    2011-09-02

    Highlights: {yields} We screened G-protein coupled receptors for imaging pancreatic. {yields} Database mining and immunohistochemistry identified GPCRs enriched in {beta}-cells. {yields} In vitro and in vivo assays were used to determine exocrine vs endocrine specificity. {yields} GPCR candidates for imaging of {beta}-cell mass are Prokineticin-1R, mGluR5, and GLP-1R. -- Abstract: A critical unmet need exists for methods to quantitatively measure endogenous pancreatic {beta}-cell mass (BCM) for the clinical evaluation of therapies to prevent or reverse loss of BCM and diabetes progression. Our objective was to identify G-protein coupled receptors (GPCRs) that are expressed with a high degree of specificity to islet {beta}-cells for receptor-targeted imaging of BCM. GPCRs enriched in pancreatic islets relative to pancreas acinar and hepatic tissue were identified using a database screen. Islet-specific expression was confirmed by human pancreas immunohistochemistry (IHC). In vitro selectivity assessment was determined from the binding and uptake of radiolabeled ligands to the rat insulinoma INS-1 832/13 cell line and isolated rat islets relative to the exocrine pancreas cell-type, PANC-1. Tail-vein injections of radioligands into rats were used to determine favorable image criteria of in vivo biodistribution to the pancreas relative to other internal organs (i.e., liver, spleen, stomach, and lungs). Database and IHC screening identified four candidate receptors for further in vitro and in vivo evaluation for PET imaging of BCM: prokineticin-1 receptor (PK-1R), metabotropic glutamate receptor type-5 (mGluR5), neuropeptide Y-2 receptor (NPY-2R), and glucagon-like peptide 1 receptor (GLP-1R). In vitro specificity ratios gave the following receptor rank order: PK-1R > GLP-1R > NPY-2R > mGluR5. The biodistribution rank order of selectivity to the pancreas was found to be PK-1R > VMAT2 {approx} GLP-1R > mGluR5. Favorable islet selectivity and biodistribution

  16. Osteocalcin protects pancreatic beta cell function and survival under high glucose conditions

    SciTech Connect

    Kover, Karen; Yan, Yun; Tong, Pei Ying; Watkins, Dara; Li, Xiaoyu; Tasch, James; Hager, Melissa; Clements, Mark; Moore, Wayne V.

    2015-06-19

    Diabetes is characterized by progressive beta cell dysfunction and loss due in part to oxidative stress that occurs from gluco/lipotoxicity. Treatments that directly protect beta cell function and survival in the diabetic milieu are of particular interest. A growing body of evidence suggests that osteocalcin, an abundant non-collagenous protein of bone, supports beta cell function and proliferation. Based on previous gene expression data by microarray, we hypothesized that osteocalcin protects beta cells from glucose-induced oxidative stress. To test our hypothesis we cultured isolated rat islets and INS-1E cells in the presence of normal, high, or high glucose ± osteocalcin for up to 72 h. Oxidative stress and viability/mitochondrial function were measured by H{sub 2}O{sub 2} assay and Alamar Blue assay, respectively. Caspase 3/7 activity was also measured as a marker of apoptosis. A functional test, glucose stimulated insulin release, was conducted and expression of genes/protein was measured by qRT-PCR/western blot/ELISA. Osteocalcin treatment significantly reduced high glucose-induced H{sub 2}O{sub 2} levels while maintaining viability/mitochondrial function. Osteocalcin also significantly improved glucose stimulated insulin secretion and insulin content in rat islets after 48 h of high glucose exposure compared to untreated islets. As expected sustained high glucose down-regulated gene/protein expression of INS1 and BCL2 while increasing TXNIP expression. Interestingly, osteocalcin treatment reversed the effects of high glucose on gene/protein expression. We conclude that osteocalcin can protect beta cells from the negative effects of glucose-induced oxidative stress, in part, by reducing TXNIP expression, thereby preserving beta cell function and survival. - Highlights: • Osteocalcin reduces glucose-induced oxidative stress in beta cells. • Osteocalcin preserves beta cell function and survival under stress conditions. • Osteocalcin reduces glucose

  17. Transcription factors involved in glucose-stimulated insulin secretion of pancreatic beta cells

    SciTech Connect

    Shao, Shiying; Fang, Zhong; Yu, Xuefeng; Zhang, Muxun

    2009-07-10

    GSIS, the most important function of pancreatic beta cell, is essential for maintaining the glucose homeostasis. Transcription factors are known to control different biological processes such as differentiation, proliferation and apoptosis. In pancreas, some transcription factors are involved in regulating the function of beta cells. In this review, the role of these transcription factors including Pdx-1, FoxO1, SREBP-1c, and MafA in GSIS is highlighted. The related molecular mechanisms are analyzed as well. Furthermore, the association between the role of transcription factors in GSIS and the development of T2DM is discussed.

  18. The Microtubule-Associated Protein Tau and Its Relevance for Pancreatic Beta Cells

    PubMed Central

    Maj, Magdalena; Hoermann, Gregor; Rasul, Sazan; Base, Wolfgang; Wagner, Ludwig; Attems, Johannes

    2016-01-01

    Structural and biochemical alterations of the microtubule-associated protein tau (MAPT) are associated with degenerative disorders referred to as tauopathies. We have previously shown that MAPT is present in human islets of Langerhans, human insulinomas, and pancreatic beta-cell line models, with biophysical similarities to the pathological MAPT in the brain. Here, we further studied MAPT in pancreatic endocrine tissue to better understand the mechanisms that lead to functional dysregulation of pancreatic beta cells. We found upregulation of MAPT protein expression in human insulinomas when compared to human pancreatic islets of Langerhans and an imbalance between MAPT isoforms in insulinomas tissue. We cloned one 3-repeat domain MAPT and transduced this into a beta-cell derived rodent cell line Rin-5F. Proliferation experiments showed higher growth rates and metabolic activities of cells overexpressing MAPT protein. We observed that a MAPT overexpressing cell line demonstrates altered insulin transcription, translation, and insulin secretion rates. We found the relative insulin secretion rates were significantly decreased in a MAPT overexpressing cell line and these findings could be confirmed using partial MAPT knock-down cell lines. Our findings support that MAPT may play an important role in insulin granule trafficking and indicate the importance of balanced MAPT phosphorylation and dephosphorylation for adequate insulin release. PMID:26824039

  19. Thyrotropin releasing hormone (TRH) affects gene expression in pancreatic beta-cells.

    PubMed

    Luo, LuGuang; Yano, Naohiro

    2005-01-01

    Thyrotropin-releasing hormone (TRH), originally identified as a hypothalamic hormone, is expressed in the pancreas. The peptide has been shown to control glycemia, although the role of TRH in the pancreas has not yet been clarified. In quiescent INS-1 cells (rat immortalized beta-cell line), 200 nM of TRH for 24 hours significantly increased insulin levels in the culture medium and in cell extracts. In studies with gene array technology where about 60% to 75% of the 1081 genes were detected, TRH significantly stimulated multiple groups of gene expressions, including G-protein-coupled receptor and related signaling, such as insulin secretion, endoplasmic reticulum traffic mechanisms, cell-cycle regulators, protein turnover factors, DNA recombination, and growth factors. Noticeably, TRH suppressed the genes of proapoptotic Bcl-2-associated protein X, Bcl-xL/ Bcl-2-associated death promoter, and Fas. The multiple gene expressions in response to TRH in pancreatic cells suggest that the changed microenvironment brought about by TRH may influence beta-cellfunction. PMID:16392621

  20. Effect of Exendin-4 on Autophagy Clearance in Beta Cell of Rats with Tacrolimus-induced Diabetes Mellitus

    PubMed Central

    Lim, Sun Woo; Jin, Long; Jin, Jian; Yang, Chul Woo

    2016-01-01

    Growing evidence suggests that GLP-1 protects beta cells against various cellular injuries by modulating autophagy. In this study, we examined whether exendin-4 (Ex-4), a GLP-1 analog, had preventive effects on tacrolimus (Tac)-induced beta cell injury by improving autophagy clearance. Rats with Tac-induced diabetes mellitus exhibited increased autophagy-associated protein expression, light chain 3B levels, and autophagic vacuole numbers in pancreatic beta cells. Additionally, Tac increased autophagy in a dose- and time-dependent manner in vitro, and inhibition of autophagosome using 3-methyladenine reduced Tac-induced islet cell injury by decreasing reactive oxygen species production and apoptosis. Ex-4 treatment decreased Tac-induced hyperglycaemia, oxidative stress, and apoptosis, accompanied by decreased autophagy-associated protein expression and autophagosome numbers. In vivo and in vitro studies showed that Tac treatment impaired lysosomal function and autophagosome-lysosome fusion; these processes were improve by Ex-4 treatment. Moreover, addition of bafilomycin A1, an inhibitor of lysosomal function, abolished the protective effects of Ex-4. Our findings reveal that Tac-induced diabetes mellitus was a state of excessive burden of autophagosomes and impairment of autophagy clearance and that Ex-4 protected against Tac-induced pancreatic islet injury by reducing the burden of autophagosomes via activation of autophagosome clearance. Thus, Ex-4 had therapeutic effects on Tac-induced pancreatic beta cell injury. PMID:27436514

  1. Ataxin-10 interacts with O-GlcNAc transferase OGT in pancreatic {beta} cells

    SciTech Connect

    Andrali, Sreenath S.; Maerz, Pia; Oezcan, Sabire . E-mail: sozcan@uky.edu

    2005-11-11

    Several nuclear and cytoplasmic proteins in metazoans are modified by O-linked N-acetylglucosamine (O-GlcNAc). This modification is dynamic and reversible similar to phosphorylation and is catalyzed by the O-linked GlcNAc transferase (OGT). Hyperglycemia has been shown to increase O-GlcNAc levels in pancreatic {beta} cells, which appears to interfere with {beta}-cell function. To obtain a better understanding of the role of O-linked GlcNAc modification in {beta} cells, we have isolated OGT interacting proteins from a cDNA library made from the mouse insulinoma MIN6 cell line. We describe here the identification of Ataxin-10, encoded by the SCA10 (spinocerebellar ataxia type 10) gene as an OGT interacting protein. Mutations in the SCA10 gene cause progressive cerebellar ataxias and seizures. We demonstrate that SCA10 interacts with OGT in vivo and is modified by O-linked glycosylation in MIN6 cells, suggesting a novel role for the Ataxin-10 protein in pancreatic {beta} cells.

  2. Present and future cell therapies for pancreatic beta cell replenishment

    PubMed Central

    Domínguez-Bendala, Juan; Ricordi, Camillo

    2012-01-01

    If only at a small scale, islet transplantation has successfully addressed what ought to be the primary endpoint of any cell therapy: the functional replenishment of damaged tissue in patients. After years of less-than-optimal approaches to immunosuppression, recent advances consistently yield long-term graft survival rates comparable to those of whole pancreas transplantation. Limited organ availability is the main hurdle that stands in the way of the widespread clinical utilization of this pioneering intervention. Progress in stem cell research over the past decade, coupled with our decades-long experience with islet transplantation, is shaping the future of cell therapies for the treatment of diabetes. Here we review the most promising avenues of research aimed at generating an inexhaustible supply of insulin-producing cells for islet regeneration, including the differentiation of pluripotent and multipotent stem cells of embryonic and adult origin along the beta cell lineage and the direct reprogramming of non-endocrine tissues into insulin-producing cells. PMID:23322984

  3. The Glucotoxicity Protecting Effect of Ezetimibe in Pancreatic Beta Cells via Inhibition of CD36

    PubMed Central

    2016-01-01

    Inhibition of CD36, a fatty acid transporter, has been reported to prevent glucotoxicity and ameliorate high glucose induced beta cell dysfunction. Ezetimibe is a selective cholesterol absorption inhibitor that blocks Niemann Pick C1-like 1 protein, but may exert its effect through suppression of CD36. We attempted to clarify the beneficial effect of ezetimibe on insulin secreting cells and to determine whether this effect is related to change of CD36 expression. mRNA expression of insulin and CD36, intracellular peroxide level and glucose stimulated insulin secretion (GSIS) under normal (5.6 mM) or high glucose (30 mM) condition in INS-1 cells and primary rat islet cells were compared. Changes of the aforementioned factors with treatment with ezetimibe (20 μM) under normal or high glucose condition were also assessed. mRNA expression of insulin was decreased with high glucose, which was reversed by ezetimibe in both INS-1 cells and primary rat islets. CD36 mRNA expression was increased with high glucose, but decreased by ezetimibe in INS-1 cells and primary rat islets. Three-day treatment with high glucose resulted in an increase in intracellular peroxide level; however, it was decreased by treatment with ezetimibe. Decrease in GSIS by three-day treatment with high glucose was reversed by ezetimibe. Palmitate uptake following exposure to high glucose conditions for three days was significantly elevated, which was reversed by ezetimibe in INS-1 cells. Ezetimibe may prevent glucotoxicity in pancreatic β-cells through a decrease in fatty acid influx via inhibition of CD36. PMID:27051238

  4. The Glucotoxicity Protecting Effect of Ezetimibe in Pancreatic Beta Cells via Inhibition of CD36.

    PubMed

    Yoon, Ji Sung; Moon, Jun Sung; Kim, Yong-Woon; Won, Kyu Chang; Lee, Hyoung Woo

    2016-04-01

    Inhibition of CD36, a fatty acid transporter, has been reported to prevent glucotoxicity and ameliorate high glucose induced beta cell dysfunction. Ezetimibe is a selective cholesterol absorption inhibitor that blocks Niemann Pick C1-like 1 protein, but may exert its effect through suppression of CD36. We attempted to clarify the beneficial effect of ezetimibe on insulin secreting cells and to determine whether this effect is related to change of CD36 expression. mRNA expression of insulin and CD36, intracellular peroxide level and glucose stimulated insulin secretion (GSIS) under normal (5.6 mM) or high glucose (30 mM) condition in INS-1 cells and primary rat islet cells were compared. Changes of the aforementioned factors with treatment with ezetimibe (20 μM) under normal or high glucose condition were also assessed. mRNA expression of insulin was decreased with high glucose, which was reversed by ezetimibe in both INS-1 cells and primary rat islets. CD36 mRNA expression was increased with high glucose, but decreased by ezetimibe in INS-1 cells and primary rat islets. Three-day treatment with high glucose resulted in an increase in intracellular peroxide level; however, it was decreased by treatment with ezetimibe. Decrease in GSIS by three-day treatment with high glucose was reversed by ezetimibe. Palmitate uptake following exposure to high glucose conditions for three days was significantly elevated, which was reversed by ezetimibe in INS-1 cells. Ezetimibe may prevent glucotoxicity in pancreatic β-cells through a decrease in fatty acid influx via inhibition of CD36. PMID:27051238

  5. GLP-1 receptor antagonist as a potential probe for pancreatic {beta}-cell imaging

    SciTech Connect

    Mukai, Eri; Toyoda, Kentaro; Kimura, Hiroyuki; Kawashima, Hidekazu; Fujimoto, Hiroyuki; Ueda, Masashi; Temma, Takashi; Hirao, Konomu; Nagakawa, Kenji; Saji, Hideo; Inagaki, Nobuya

    2009-11-20

    We examined exendin(9-39), an antagonist of glucagon-like peptide-1 (GLP-1) receptor (GLP-1R), as a potential probe for imaging of pancreatic {beta}-cells. To evaluate in vitro receptor specificity, binding assay was performed using dispersed mouse islet cells. Binding assay showed competitive inhibition of [{sup 125}I]BH-exendin(9-39) binding by non-radioactive exendin(9-39). To assess in vivo selectivity, the biodistribution was evaluated by intravenous administration of [{sup 125}I]BH-exendin(9-39) to mice. Radioactivity of harvested pancreas reached highest levels at 60 and 120 min among organs examined except lung. Pre-administration of excess non-radioactive exendin(9-39) remarkably and specifically blocked the radioactivity of pancreas. After [{sup 125}I]BH-exendin(9-39) injection into transgenic mice with pancreatic {beta}-cells expressing GFP, fluorescent and radioactive signals of sections of pancreas were evaluated with an image analyzer. Imaging analysis showed that the fluorescent GFP signals and the radioactive signals were correspondingly located. Thus, the GLP-1R antagonist exendin(9-39) may serve as a useful probe for pancreatic {beta}-cell imaging.

  6. Modulation of Ionic Channels and Insulin Secretion by Drugs and Hormones in Pancreatic Beta Cells.

    PubMed

    Velasco, Myrian; Díaz-García, Carlos Manlio; Larqué, Carlos; Hiriart, Marcia

    2016-09-01

    Pancreatic beta cells, unique cells that secrete insulin in response to an increase in glucose levels, play a significant role in glucose homeostasis. Glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells has been extensively explored. In this mechanism, glucose enters the cells and subsequently the metabolic cycle. During this process, the ATP/ADP ratio increases, leading to ATP-sensitive potassium (KATP) channel closure, which initiates depolarization that is also dependent on the activity of TRP nonselective ion channels. Depolarization leads to the opening of voltage-gated Na(+) channels (Nav) and subsequently voltage-dependent Ca(2+) channels (Cav). The increase in intracellular Ca(2+) triggers the exocytosis of insulin-containing vesicles. Thus, electrical activity of pancreatic beta cells plays a central role in GSIS. Moreover, many growth factors, incretins, neurotransmitters, and hormones can modulate GSIS, and the channels that participate in GSIS are highly regulated. In this review, we focus on the principal ionic channels (KATP, Nav, and Cav channels) involved in GSIS and how classic and new proteins, hormones, and drugs regulate it. Moreover, we also discuss advances on how metabolic disorders such as metabolic syndrome and diabetes mellitus change channel activity leading to changes in insulin secretion. PMID:27436126

  7. Ubiquitin D Regulates IRE1α/c-Jun N-terminal Kinase (JNK) Protein-dependent Apoptosis in Pancreatic Beta Cells.

    PubMed

    Brozzi, Flora; Gerlo, Sarah; Grieco, Fabio Arturo; Juusola, Matilda; Balhuizen, Alexander; Lievens, Sam; Gysemans, Conny; Bugliani, Marco; Mathieu, Chantal; Marchetti, Piero; Tavernier, Jan; Eizirik, Décio L

    2016-06-01

    Pro-inflammatory cytokines contribute to pancreatic beta cell apoptosis in type 1 diabetes at least in part by inducing endoplasmic reticulum (ER) stress and the consequent unfolded protein response (UPR). It remains to be determined what causes the transition from "physiological" to "apoptotic" UPR, but accumulating evidence indicates that signaling by the ER transmembrane protein IRE1α is critical for this transition. IRE1α activation is regulated by both intra-ER and cytosolic cues. We evaluated the role for the presently discovered cytokine-induced and IRE1α-interacting protein ubiquitin D (UBD) on the regulation of IRE1α and its downstream targets. UBD was identified by use of a MAPPIT (mammalian protein-protein interaction trap)-based IRE1α interactome screen followed by comparison against functional genomic analysis of human and rodent beta cells exposed to pro-inflammatory cytokines. Knockdown of UBD in human and rodent beta cells and detailed signal transduction studies indicated that UBD modulates cytokine-induced UPR/IRE1α activation and apoptosis. UBD expression is induced by the pro-inflammatory cytokines interleukin (IL)-1β and interferon (IFN)-γ in rat and human pancreatic beta cells, and it is also up-regulated in beta cells of inflamed islets from non-obese diabetic mice. UBD interacts with IRE1α in human and rodent beta cells, modulating IRE1α-dependent activation of JNK and cytokine-induced apoptosis. Our data suggest that UBD provides a negative feedback on cytokine-induced activation of the IRE1α/JNK pro-apoptotic pathway in cytokine-exposed beta cells. PMID:27044747

  8. Zip4 Mediated Zinc Influx Stimulates Insulin Secretion in Pancreatic Beta Cells

    PubMed Central

    Hardy, Alexandre B.; Prentice, Kacey J.; Froese, Sean; Liu, Ying; Andrews, Glen K.; Wheeler, Michael B.

    2015-01-01

    Zinc has an important role in normal pancreatic beta cell physiology as it regulates gene transcription, insulin crystallization and secretion, and cell survival. Nevertheless, little is known about how zinc is transported through the plasma membrane of beta cells and which of the class of zinc influx transporters (Zip) is involved. Zip4 was previously shown to be expressed in human and mouse beta cells; however, its function there is still unknown. Therefore, the aim of this study was to define the zinc transport role of Zip4 in beta cells. To investigate this, Zip4 was over-expressed in MIN6 beta cells using a pCMV6-Zip4GFP plasmid. Organelle staining combined with confocal microscopy showed that Zip4 exhibits a widespread localization in MIN6 cells. Time-lapse zinc imaging experiments showed that Zip4 increases cytoplasmic zinc levels. This resulted in increased granular zinc content and glucose-stimulated insulin secretion. Interestingly, it is unlikely that the increased glucose stimulated insulin secretion was triggered by a modulation of mitochondrial function, as mitochondrial membrane potential remained unchanged. To define the role of Zip4 in-vivo, we generated a beta cell-specific knockout mouse model (Zip4BKO). Deletion of the Zip4 gene was confirmed in Zip4BKO islets by PCR, RT-PCR, and immuno-histochemistry. Zip4BKO mice showed slightly improved glucose homeostasis but no change in insulin secretion during an oral glucose tolerance test. While Zip4 was not found to be essential for proper glucose homeostasis and insulin secretion in vivo in mice, this study also found that Zip4 mediates increases in cytoplasmic and granular zinc pools and stimulates glucose dependant insulin secretion in-vitro. PMID:25806541

  9. Age-related differences in the pancreatic beta-cell response to hyperglycemia after eccentric exercise.

    PubMed

    Krishnan, R K; Hernandez, J M; Williamson, D L; O'Gorman, D J; Evans, W J; Kirwan, J P

    1998-09-01

    Eccentric exercise (ECC) causes muscle damage, insulin resistance, and increased pancreatic beta-cell secretion in young individuals. However, the effects of age on the pancreatic beta-cell response to glucose after ECC are unknown. Hyperglycemic clamps (180 min, 10.0 mM) were performed on eight young (age 22 +/- 1 yr) and eight older (age 66 +/- 2 yr) healthy sedentary males without exercise (CONT) and 48 h after ECC. ECC increased (P < 0.02) muscle soreness ratings and plasma creatine kinase concentrations in both groups. Insulin and C-peptide secretions were similar between young and older subjects during CONT clamps. ECC increased (P < 0.05) first-phase (0-10 min) C-peptide area under the curve in young (4.2 +/- 0.4 vs. 3.7 +/- 0.6 nM . min; ECC vs. CONT, respectively) but not in older subjects (3.2 +/- 0.7 vs. 3.5 +/- 0.7 nM . min; ECC vs. CONT), with significant group differences (P < 0.02). Indeed, ECC repressed (P < 0.05) first-phase peak C-peptide concentrations in older subjects (0. 93 +/- 0.16 vs. 1.12 +/- 0.11 nM; ECC vs. CONT). Moreover, first-phase C-peptide-to-insulin molar ratios suggest age-related differences (P < 0.05) in insulin/C-peptide clearance after ECC. Furthermore, the observed C-peptide response after ECC was related to abdominal adiposity [r = -0.62, P < 0.02, and r = -0.66, P < 0. 006, for first and second (10-180 min) phases, respectively]. In conclusion, older individuals did not exhibit the compensatory increase in beta-cell secretion observed among young individuals after ECC. Thus, with increasing age, the pancreatic beta-cell may be less responsive to the physiological stress associated with ECC. PMID:9725813

  10. Joe Doupe lecture: emerging strategies for the preservation of pancreatic beta-cell function in early type 2 diabetes.

    PubMed

    Retnakaran, Ravi

    2014-01-01

    A fundamental problem in the clinical management of type 2 diabetes is the inability to prevent the ongoing deterioration of pancreatic beta-cell function over time that underlies the chronic progressive nature of this condition. Importantly, beta-cell dysfunction has both reversible and irreversible components. Furthermore, the amelioration of reversible beta-cell dysfunction through the early institution of short-term insulin-based therapy has emerged as a strategy that can yield temporary remission of type 2 diabetes. In this context, we have forwarded a novel therapeutic paradigm consisting of initial induction therapy to improve beta-cell function early in the course of diabetes followed by maintenance therapy aimed at preserving this beneficial beta-cell effect. Ultimately, this approach may yield an optimized therapeutic strategy for the durable preservation of beta-cell function and consequent modification of the natural history of type 2 diabetes. PMID:25618275

  11. Nuclear SREBP-1a causes loss of pancreatic {beta}-cells and impaired insulin secretion

    SciTech Connect

    Iwasaki, Yuko; Iwasaki, Hitoshi; Yatoh, Shigeru; Ishikawa, Mayumi; Kato, Toyonori; Matsuzaka, Takashi; Nakagawa, Yoshimi; Yahagi, Naoya; Kobayashi, Kazuto; Takahashi, Akimitsu; Suzuki, Hiroaki; Yamada, Nobuhiro; Shimano, Hitoshi

    2009-01-16

    Transgenic mice expressing nuclear sterol regulatory element-binding protein-1a under the control of the insulin promoter were generated to determine the role of SREBP-1a in pancreatic {beta}-cells. Only low expressors could be established, which exhibited mild hyperglycemia, impaired glucose tolerance, and reduced plasma insulin levels compared to C57BL/6 controls. The islets isolated from the transgenic mice were fewer and smaller, and had decreased insulin content and unaltered glucagon staining. Both glucose- and potassium-stimulated insulin secretions were decreased. The transgenic islets consistently expressed genes for fatty acids and cholesterol synthesis, resulting in accumulation of triglycerides but not cholesterol. PDX-1, {beta}{epsilon}{tau}{alpha}2, MafA, and IRS-2 were suppressed, partially explaining the loss and dysfunction of {beta}-cell mass. The transgenic mice on a high fat/high sucrose diet still exhibited impaired insulin secretion and continuous {beta}-cell growth defect. Therefore, nuclear SREBP-1a, even at a low level, strongly disrupts {beta}-cell mass and function.

  12. Nitric oxide stimulates insulin gene transcription in pancreatic {beta}-cells

    SciTech Connect

    Campbell, S.C. . E-mail: s.c.campbell@ncl.ac.uk; Richardson, H.; Ferris, W.F.; Butler, C.S.; Macfarlane, W.M.

    2007-02-23

    Recent studies have identified a positive role for nitric oxide (NO) in the regulation of pancreatic {beta}-cell function. The aim of this study was to determine the effects of short-term exposure to NO on {beta}-cell gene expression and the activity of the transcription factor PDX-1. NO stimulated the activity of the insulin gene promoter in Min6 {beta}-cells and endogenous insulin mRNA levels in both Min6 and isolated islets of Langerhans. Addition of wortmannin prior to NO stimulation blocked the observed increases in insulin gene promoter activity. Although NO addition stimulated the phosphorylation of p38, inhibition by SB203580 did not block the effect of NO on the insulin gene promoter. NO addition also stimulated both the nuclear accumulation and the DNA binding activity of PDX-1. This study has shown that over 24 h, NO stimulates insulin gene expression, PI-3-kinase activity and the activity of the critical {beta}-cell transcription factor PDX-1.

  13. Junctophilin 3 expresses in pancreatic beta cells and is required for glucose-stimulated insulin secretion.

    PubMed

    Li, L; Pan, Z-F; Huang, X; Wu, B-W; Li, T; Kang, M-X; Ge, R-S; Hu, X-Y; Zhang, Y-H; Ge, L-J; Zhu, D-Y; Wu, Y-L; Lou, Y-J

    2016-01-01

    It is well accepted that junctophilin (JPHs) isoforms act as a physical bridge linking plasma membrane and endoplasmic reticulum (ER) for channel crosstalk in excitable cells. Our purpose is to investigate whether JPHs are involved in the proper communication between Ca(2+) influx and subsequent Ca(2+) amplification in pancreatic beta cells, thereby participating in regulating insulin secretion. The expression of JPH isoforms was examined in human and mouse pancreatic tissues, and JPH3 expression was found in both the beta cells. In mice, knockdown of Jph3 (si-Jph3) in islets decreased glucose-stimulated insulin secretion (GSIS) accompanied by mitochondrial function impairment. Si-Jph3 lowered the insulin secretory response to Ca(2+) signaling in the presence of glucose, and reduced [Ca(2+)]c transient amplitude triggered by caffeine. Si-Jph3 also attenuated mitofusin 2 expression, thereby disturbing the spatial organization of ER-mitochondria contact in islets. These results suggest that the regulation of GSIS by the KATP channel-independent pathways is partly impaired due to decrease of JPH3 expression in mouse islets. JPH3 also binds to type 2 ryanodine receptors (RyR2) in mouse and human pancreatic tissues, which might contribute to Ca(2+) release amplification in GSIS. This study demonstrates some previously unrecognized findings in pancreatic tissues: (1) JPH3 expresses in mouse and human beta cells; (2) si-Jph3 in mouse primary islets impairs GSIS in vitro; (3) impairment in GSIS in si-Jph3 islets is due to changes in RyR2-[Ca(2+)]c transient amplitude and ER-mitochondria contact. PMID:27336719

  14. ER stress in pancreatic beta cells: the thin red line between adaptation and failure.

    PubMed

    Eizirik, Decio L; Cnop, Miriam

    2010-01-01

    Secretory cells, such as pancreatic beta cells, face the challenge of increasing protein synthesis severalfold during acute or chronic stimulation. This poses a burden on the endoplasmic reticulum (ER), the organelle where proinsulin synthesis and folding takes place. Thus, beta cells use various adaptive mechanisms to adjust the functional capacity of the ER to the prevailing demand. These check-and-balance mechanisms are collectively known as the unfolded protein response (UPR). It remains unclear how UPR signaling is ultimately regulated and what delineates the boundaries between a physiological and a pathological response. New discoveries point to the divergent effects of acute and chronic metabolic fluxes and chemical ER stressors on the formation of complexes among UPR transducers, scaffold proteins, and phosphatases. These and other findings provide a first glimpse on how different signals trigger diverging UPR outcomes. PMID:20179270

  15. Properties of the Ca-activated K+ channel in pancreatic beta-cells.

    PubMed

    Atwater, I; Rosario, L; Rojas, E

    1983-12-01

    The existence of [Ca2+]i-activated K+-channels in the pancreatic beta-cell membrane is based in two observations: quinine inhibits K+-permeability and, increasing intracellular Ca2+ stimulates it. The changes in K+-permeability of the beta-cell have been monitored electrically by combining measurements of the dependence of the membrane potential on external K+ concentration and input resistance. The changes in the passive 42K and 86Rb efflux from the whole islet have been measured directly. Intracellular Ca2+ has been increased by various means, including increasing extracellular Ca2+, addition of the Ca2+-ionophore A23187 or noradrenaline and application of mitochondrial uncouplers and blockers. In addition to quinine, many other substances have been found to inhibit or modulate the [Ca2+]i-activated K+-channel. The most important of these is the natural stimulus for insulin secretion, glucose. Glucose may inhibit K+-permeability by lowering intracellular Ca2+. Glibenclamide, a hypoglycaemic sulphonylurea, is about 25 times more active than quinine in blocking the K+-channel in beta-cells. The methylxanthines, c-AMP, various calmodulin inhibitors and Ba2+ also inhibit K+-permeability. Genetically diabetic mice have been studied and show an alteration in the [Ca2+]i-activated K+-channel. It is concluded that the [Ca2+]i-activated K+-channel plays a major role in the normal function of the pancreatic beta-cell. The study of its properties should prove valuable for the understanding and treatment of diabetes. PMID:6323007

  16. Biophysical properties of gap junctions between freshly dispersed pairs of mouse pancreatic beta cells.

    PubMed Central

    Pérez-Armendariz, M; Roy, C; Spray, D C; Bennett, M V

    1991-01-01

    Coupling between beta cells through gap junctions has been postulated as a principal mechanism of electrical synchronization of glucose-induced activity throughout the islet of Langerhans. We characterized junctional conductance between isolated pairs of mouse pancreatic beta cells by whole-cell recording with two independent patch-clamp circuits. Most pairs were coupled (67%, n = 155), although the mean junctional conductance (gj) (215 +/- 110 pS) was lower than reported in other tissues. Coupling could be recorded for long periods, up to 40 min. Voltage imposed across the junctional or nonjunctional membranes had no effect on gj. Up to several hours of treatment to increase intracellular cAMP levels did not affect gj. Electrically coupled pairs did not show transfer of the dye Lucifer yellow. Octanol (2 mM) reversibly decreased gj. Lower concentrations of octanol (0.5 mM) and heptanol (0.5 mM) than required to uncouple beta cells decreased voltage-dependent K+ and Ca2+ currents in nonjunctional membranes. Although gj recorded in these experiments would be expected to be provided by current flowing through only a few channels of the unitary conductance previously reported for other gap junctions, no unitary junctional currents were observed even during reversible suppression of gj by octanol. This result suggests either that the single channel conductance of gap junction channels between beta cells is smaller than in other tissues (less than 20 pS) or that the small mean conductance is due to transitions between open and closed states that are too rapid or too slow to be resolved. Images FIGURE 1 FIGURE 5 PMID:2015391

  17. Glucocorticoids Inhibit Basal and Hormone-Induced Serotonin Synthesis in Pancreatic Beta Cells

    PubMed Central

    Hasni Ebou, Moina; Singh-Estivalet, Amrit; Launay, Jean-Marie; Callebert, Jacques; Tronche, François; Ferré, Pascal; Gautier, Jean-François; Guillemain, Ghislaine; Bréant, Bernadette

    2016-01-01

    Diabetes is a major complication of chronic Glucocorticoids (GCs) treatment. GCs induce insulin resistance and also inhibit insulin secretion from pancreatic beta cells. Yet, a full understanding of this negative regulation remains to be deciphered. In the present study, we investigated whether GCs could inhibit serotonin synthesis in beta cell since this neurotransmitter has been shown to be involved in the regulation of insulin secretion. To this aim, serotonin synthesis was evaluated in vitro after treatment with GCs of either islets from CD1 mice or MIN6 cells, a beta-cell line. We also explored the effect of GCs on the stimulation of serotonin synthesis by several hormones such as prolactin and GLP 1. We finally studied this regulation in islet in two in vivo models: mice treated with GCs and with liraglutide, a GLP1 analog, and mice deleted for the glucocorticoid receptor in the pancreas. We showed in isolated islets and MIN6 cells that GCs decreased expression and activity of the two key enzymes of serotonin synthesis, Tryptophan Hydroxylase 1 (Tph1) and 2 (Tph2), leading to reduced serotonin contents. GCs also blocked the induction of serotonin synthesis by prolactin or by a previously unknown serotonin activator, the GLP-1 analog exendin-4. In vivo, activation of the Glucagon-like-Peptide-1 receptor with liraglutide during 4 weeks increased islet serotonin contents and GCs treatment prevented this increase. Finally, islets from mice deleted for the GR in the pancreas displayed an increased expression of Tph1 and Tph2 and a strong increased serotonin content per islet. In conclusion, our results demonstrate an original inhibition of serotonin synthesis by GCs, both in basal condition and after stimulation by prolactin or activators of the GLP-1 receptor. This regulation may contribute to the deleterious effects of GCs on beta cells. PMID:26901633

  18. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic {beta} cells

    SciTech Connect

    Kumar, Divya P.; Rajagopal, Senthilkumar; Mahavadi, Sunila; Mirshahi, Faridoddin; Grider, John R.; Murthy, Karnam S.; Sanyal, Arun J.

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer G protein coupled receptor TGR5 is expressed in mouse and human islets. Black-Right-Pointing-Pointer TGR5 is coupled to activation of Gs and Ca{sup 2+} release via cAMP/Epac/PLC-{epsilon} pathway. Black-Right-Pointing-Pointer Activation of TGR5 by bile salts and selective ligands causes insulin secretion. Black-Right-Pointing-Pointer TGR5 could be a potential therapeutic target to treat diabetes. -- Abstract: Bile acids act as signaling molecules and stimulate the G protein coupled receptor, TGR5, in addition to nuclear farnesoid X receptor to regulate lipid, glucose and energy metabolism. Bile acid induced activation of TGR5 in the enteroendocrine cells promotes glucagon like peptide-1 (GLP-1) release, which has insulinotropic effect in the pancreatic {beta} cells. In the present study, we have identified the expression of TGR5 in pancreatic {beta} cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated G{alpha}{sub s} and caused an increase in intracellular cAMP and Ca{sup 2+}. OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective G{alpha}{sub s} inhibitor) or (U73122) (PI hydrolysis inhibitor). OA, INT-777 and lithocholic acid increased insulin release in MIN6 and human islets and the increase was inhibited by treatment with NF449, (U73122) or BAPTA-AM (chelator of calcium), but not with myristoylated PKI (PKA inhibitor), suggesting that the release is dependent on G{sub s}/cAMP/Ca{sup 2+} pathway. 8-pCPT-2 Prime -O-Me-cAMP, a cAMP analog, which activates Epac, but not PKA also stimulated PI hydrolysis. In conclusion, our study demonstrates that the TGR5 expressed in the pancreatic {beta} cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

  19. Effects of antidiabetic agents on pancreatic beta-cell function in gestational diabetes: is there enough evidence?

    PubMed

    Tura, Andrea; Göbl, Christian; Pacini, Giovanni

    2016-01-01

    Gestational diabetes mellitus (GDM) is typically characterized by the presence of insulin resistance. However, recent studies showed that both insulin resistance and pancreatic beta-cell function impairment may contribute to the development of type 2 diabetes in women with history of GDM. In fact, beta-cell function decline was found as significant predictor of later disease in former GDM women progressing towards type 2 diabetes. Despite the evidence of the relevance of beta-cell function quantification in GDM, a low number of studies focused on the effects of GDM treatments on beta-cell function. We briefly present the evidence of the effects on beta-cell function of pharmacological agents, as well as nutrition supplements or medical nutrition therapy, used in the management of GDM. We found that few studies reported information on beta-cell function effects in GDM, despite some agents, such as glyburide, are well known insulin secretagogues. Therefore, further studies should be carried out to clearly assess the effects on beta-cell function of the treatments in GDM women. PMID:26609764

  20. Down-regulation of zinc transporter 8 (SLC30A8) in pancreatic beta-cells promotes cell survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pancreatic islet contains high levels of zinc in granular vesicles of beta-cells where insulin is matured, crystallized, and stored before secretion. Zinc is an essential co-factor for insulin crystallization forming dense core in secretory granules. In insulin-containing secretory granules, zin...

  1. Evidence for a slowly exchangeable pool of calcium in the pancreatic beta cell plasma membrane.

    PubMed Central

    Gylfe, E; Hellman, B

    1982-01-01

    1. Exposure to media deprived of Ca2+ resulted in prompt and transient stimulation of 45Ca efflux from beta cell-rich pancreatic islets microdissected from ob/ob-mice and to some extent also from the isolated neurohypophysis. 2. Particular high efflux rates were reached when the Ca2+-deficient medium contained EGTA, but there was no effect of the chelator on the total amount of radioactivity mobilized from the islets. 3. The removal of extracellular Ca2+ was less effective in promoting the 45Ca efflux in the absence of Na+ and no stimulatory response was seen in the presence of 1 mM-La3+. 4. The 45Ca washout was stimulated whether or not the media used for the loading or subsequent perifusion of the islets were supplemented with 20 mM-D-glucose. However, there was no response to a second exposure to a Ca2+-deficient medium even subsequent to redistribution of intracellular calcium induced by temporary lowering of the temperature. 5. It is suggested that the islet 45Ca released by the removal of extracellular Ca2+ originates from a distinct plasma membrane pool which is exchanged slowly compared to most of the calcium at the beta cell periphery. PMID:6752376

  2. Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress.

    PubMed

    Backe, Marie Balslev; Moen, Ingrid Wahl; Ellervik, Christina; Hansen, Jakob Bondo; Mandrup-Poulsen, Thomas

    2016-07-17

    Dietary advice is the cornerstone in first-line treatment of metabolic diseases. Nutritional interventions directed at these clinical conditions mainly aim to (a) improve insulin resistance by reducing energy-dense macronutrient intake to obtain weight loss and (b) reduce fluctuations in insulin secretion through avoidance of rapidly absorbable carbohydrates. However, even in the majority of motivated patients selected for clinical trials, massive efforts using this approach have failed to achieve lasting efficacy. Less attention has been given to the role of micronutrients in metabolic diseases. Here, we review the evidence that highlights (a) the importance of iron in pancreatic beta-cell function and dysfunction in diabetes and (b) the integrative pathophysiological effects of tissue iron levels in the interactions among the beta cell, gut microbiome, hypothalamus, innate and adaptive immune systems, and insulin-sensitive tissues. We propose that clinical trials are warranted to clarify the impact of dietary or pharmacological iron reduction on the development of metabolic disorders. PMID:27146016

  3. Transient receptor potential M3 channels are ionotropic steroid receptors in pancreatic beta cells.

    PubMed

    Wagner, Thomas F J; Loch, Sabine; Lambert, Sachar; Straub, Isabelle; Mannebach, Stefanie; Mathar, Ilka; Düfer, Martina; Lis, Annette; Flockerzi, Veit; Philipp, Stephan E; Oberwinkler, Johannes

    2008-12-01

    Transient receptor potential (TRP) cation channels are renowned for their ability to sense diverse chemical stimuli. Still, for many members of this large and heterogeneous protein family it is unclear how their activity is regulated and whether they are influenced by endogenous substances. On the other hand, steroidal compounds are increasingly recognized to have rapid effects on membrane surface receptors that often have not been identified at the molecular level. We show here that TRPM3, a divalent-permeable cation channel, is rapidly and reversibly activated by extracellular pregnenolone sulphate, a neuroactive steroid. We show that pregnenolone sulphate activates endogenous TRPM3 channels in insulin-producing beta cells. Application of pregnenolone sulphate led to a rapid calcium influx and enhanced insulin secretion from pancreatic islets. Our results establish that TRPM3 is an essential component of an ionotropic steroid receptor enabling unanticipated crosstalk between steroidal and insulin-signalling endocrine systems. PMID:18978782

  4. Impairment of Rat Fetal Beta-Cell Development by Maternal Exposure to Dexamethasone during Different Time-Windows

    PubMed Central

    Dumortier, Olivier; Theys, Nicolas; Ahn, Marie-Thérèse; Remacle, Claude; Reusens, Brigitte

    2011-01-01

    Aim Glucocorticoids (GCs) take part in the direct control of cell lineage during the late phase of pancreas development when endocrine and exocrine cell differentiation occurs. However, other tissues such as the vasculature exert a critical role before that phase. This study aims to investigate the consequences of overexposure to exogenous glucocorticoids during different time-windows of gestation for the development of the fetal endocrine pancreas. Methods Pregnant Wistar rats received dexamethasone acetate in their drinking water (1 µg/ml) during the last week or throughout gestation. Fetuses and their pancreases were analyzed at day 15 and 21 of gestation. Morphometrical analysis was performed on pancreatic sections after immunohistochemistry techniques and insulin secretion was evaluated on fetal islets collected in vitro. Results Dexamethasone given the last week or throughout gestation reduced the beta-cell mass in 21-day-old fetuses by respectively 18% or 62%. This was accompanied by a defect in insulin secretion. The alpha-cell mass was reduced similarly. Neither islet vascularization nor beta-cell proliferation was affected when dexamethasone was administered during the last week, which was however the case when given throughout gestation. When given from the beginning of gestation, dexamethasone reduced the number of cells expressing the early marker of endocrine lineage neurogenin-3 when analyzed at 15 days of fetal age. Conclusions GCs reduce the beta- and alpha-cell mass by different mechanisms according to the stage of development during which the treatment was applied. In fetuses exposed to glucocorticoids the last week of gestation only, beta-cell mass is reduced due to impairment of beta-cell commitment, whereas in fetuses exposed throughout gestation, islet vascularization and lower beta-cell proliferation are involved as well, amplifying the reduction of the endocrine mass. PMID:21991320

  5. Mitochondrial network regulation and its potential interference with inflammatory signals in pancreatic beta cells.

    PubMed

    Baltrusch, Simone

    2016-04-01

    Mitochondria fulfil multiple tasks in nutrient metabolism, energy production, redox homeostasis and stress response, and are essential for pancreatic beta cell function. The dynamism and health of the mitochondrial network is regulated by fission- and fusion-triggering factors and by a quality control system that removes dysfunctional organelles. Alongside the role of mitochondria in regulating apoptotic cell death mediated primarily via production of reactive oxygen species and release of cytochrome c, there is evidence of other links between mitochondria and inflammation that have implications for cell viability. This review briefly outlines two pathways that are potentially vital for pancreatic beta cell function. The first concerns the regulation of Parkin, a protein that acts, not only as a central player in regulating mitophagy, but also as an activator of the NF-ĸB pathway. The fact that expression of optic atrophy protein 1 (OPA1), a mitochondrial fusion inducer and master mitochondrial cristae biogenetic factor, is increased following NF-ĸB activation highlights a point of mitochondrial control that might be influenced by TNFα signalling. A second axis of interest is suggested by IL-6-mediated upregulation of the fission inducer FIS1 alongside downregulation of mitofusin 2 (MFN2), a guard of mitochondrial fusion and metabolism and an inhibitor of apoptosis. This review summarises a presentation given at the 'Islet inflammation in type 2 diabetes' symposium at the 2015 annual meeting of the EASD. It is accompanied two other reviews on topics from this symposium (by Marc Donath, DOI: 10.1007/s00125-016-3873-z , and Jerry Nadler and colleagues, DOI: 10.1007/s00125-016-3890-y ) and a commentary by the Session Chair, Piero Marchetti (DOI: 10.1007/s00125-016-3875-x ). PMID:26873508

  6. Serpine1 Mediates Porphyromonas gingivalis Induced Insulin Secretion in the Pancreatic Beta Cell Line MIN6

    PubMed Central

    Bhat, Uppoor G.; Watanabe, Keiko

    2015-01-01

    Periodontitis is an inflammatory disease resulting in destruction of gingiva and alveolar bone caused by an exuberant host immunological response to periodontal pathogens. Results from a number of epidemiological studies indicate a close association between diabetes and periodontitis. Results from cross-sectional studies indicate that subjects with periodontitis have a higher odds ratio of developing insulin resistance (IR). However, the mechanisms by which periodontitis influences the development of diabetes are not known. Results from our previous studies using an animal model of periodontitis suggest that periodontitis accelerates the onset of hyperinsulinemia and IR. In addition, LPS from a periodontal pathogen, Porphyromonas gingivalis (Pg), stimulates Serpine1 expression in the pancreatic beta cell line MIN6. Based on these observations, we hypothesized that a periodontal pathogen induces hyperinsulinemia and Serpine1 may be involved in this process. To test this hypothesis, we co-incubated Pg with the pancreatic beta cell line MIN6 and measured the effect on insulin secretion by MIN6 cells. We further determined the involvement of Serpine1 in insulin secretion by downregulating Serpine1 expression. Our results indicated that Pg stimulated insulin secretion by approximately 3.0 fold under normoglycemic conditions. In a hyperglycemic state, Pg increased insulin secretion by 1.5 fold. Pg significantly upregulated expression of the Serpine1 gene and this was associated with increased secretion of insulin by MIN6 cells. However, cells with downregulated Serpine1 expression were resistant to Pg stimulated insulin secretion under normoglycemic conditions. We conclude that the periodontal pathogen, Pg, induced insulin secretion by MIN6 cells and this induction was, in part, Serpine1 dependent. Thus, Serpine1 may play a pivotal role in insulin secretion during the accelerated development of hyperinsulinemia and the resulting IR in the setting of periodontitis. PMID

  7. Mafa expression enhances glucose-responsive insulin secretion in neonatal rat beta cells

    PubMed Central

    Aguayo-Mazzucato, C.; Koh, A.; El Khattabi, I.; Li, W.-C.; Toschi, E.; Jermendy, A.; Juhl, K.; Mao, K.; Weir, G. C.

    2011-01-01

    Aim/hypothesis Neonatal beta cells lack glucose-stimulated insulin secretion and are thus functionally immature. We hypothesised that this lack of glucose responsiveness results from a generalised low expression of genes characteristic of mature functional beta cells. Important glucose-responsive transcription factors, Mafa and Pdx1, regulate genes involved in insulin synthesis and secretion, and have been implicated in late beta cell development. The aim of this study was to assess whether Mafa and/or Pdx1 regulates the postnatal functional maturation of beta cells. Methods By quantitative PCR we evaluated expression of these and other beta cell genes over the first month compared with adult. After infection with adenovirus expressing MAFA, Pdx1 or green fluorescent protein (Gfp), P2 rat islets were evaluated by RT-PCR and insulin secretion with static incubation and reverse haemolytic plaque assay (RHPA). Results At P2 most beta cell genes were expressed at about 10% of adult, but by P7 Pdx1 and Neurod1 no longer differ from adult; by contrast, Mafa expression remained significantly lower than adult through P21. Overexpression of Pdx1 increased Mafa, Neurod1, glucokinase (Gck) mRNA and insulin content but failed to enhance glucose responsiveness. Similar overexpression of MAFA resulted in increased Neurod1, Nkx6-1, Gck and Glp1r mRNAs and no change in insulin content but, importantly, acquisition of glucose-responsive insulin secretion. Both the percentage of secreting beta cells and the amount of insulin secreted per beta cell increased, approaching that of adult beta cells. Conclusions/interpretation In the process of functional maturation acquiring glucose-responsive insulin secretion, neonatal beta cells undergo a coordinated gene expression programme in which Mafa plays a crucial role. PMID:21190012

  8. Hepatocyte nuclear factor 3beta is involved in pancreatic beta-cell-specific transcription of the pdx-1 gene.

    PubMed Central

    Wu, K L; Gannon, M; Peshavaria, M; Offield, M F; Henderson, E; Ray, M; Marks, A; Gamer, L W; Wright, C V; Stein, R

    1997-01-01

    The mammalian homeobox gene pdx-1 is expressed in pluripotent precursor cells in the dorsal and ventral pancreatic bud and duodenal endoderm, which will produce the pancreas and the rostral duodenum. In the adult, pdr-1 is expressed principally within insulin-secreting pancreatic islet beta cells and cells of the duodenal epithelium. Our objective in this study was to localize sequences within the mouse pdx-1 gene mediating selective expression within the islet. Studies of transgenic mice in which a genomic fragment of the mouse pdx-1 gene from kb -4.5 to +8.2 was used to drive a beta-galactosidase reporter showed that the control sequences sufficient for appropriate developmental and adult specific expression were contained within this region. Three nuclease-hypersensitive sites, located between bp -2560 and -1880 (site 1), bp -1330 and -800 (site 2), and bp -260 and +180 (site 3), were identified within the 5'-flanking region of the endogenous pdx-1 gene. Pancreatic beta-cell-specific expression was shown to be controlled by sequences within site 1 from an analysis of the expression pattern of various pdr-1-herpes simplex virus thymidine kinase promoter expression constructs in transfected beta-cell and non-beta-cell lines. Furthermore, we also established that this region was important in vivo by demonstrating that expression from a site 1-driven beta-galactosidase reporter construct was directed to islet beta-cells in transgenic mice. The activity of the site 1-driven constructs was reduced substantially in beta-cell lines by mutating a hepatocyte nuclear factor 3 (HNF3)-like site located between nucleotides -2007 and -1996. Gel shift analysis indicated that HNF3beta present in islet beta cells binds to this element. Immunohistochemical studies revealed that HNF3beta was present within the nuclei of almost all islet beta cells and subsets of pancreatic acinar cells. Together, these results suggest that HNF3beta, a key regulator of endodermal cell lineage

  9. Nkx6.1 controls a gene regulatory network required for establishing and maintaining pancreatic Beta cell identity.

    PubMed

    Schaffer, Ashleigh E; Taylor, Brandon L; Benthuysen, Jacqueline R; Liu, Jingxuan; Thorel, Fabrizio; Yuan, Weiping; Jiao, Yang; Kaestner, Klaus H; Herrera, Pedro L; Magnuson, Mark A; May, Catherine Lee; Sander, Maike

    2013-01-01

    All pancreatic endocrine cell types arise from a common endocrine precursor cell population, yet the molecular mechanisms that establish and maintain the unique gene expression programs of each endocrine cell lineage have remained largely elusive. Such knowledge would improve our ability to correctly program or reprogram cells to adopt specific endocrine fates. Here, we show that the transcription factor Nkx6.1 is both necessary and sufficient to specify insulin-producing beta cells. Heritable expression of Nkx6.1 in endocrine precursors of mice is sufficient to respecify non-beta endocrine precursors towards the beta cell lineage, while endocrine precursor- or beta cell-specific inactivation of Nkx6.1 converts beta cells to alternative endocrine lineages. Remaining insulin(+) cells in conditional Nkx6.1 mutants fail to express the beta cell transcription factors Pdx1 and MafA and ectopically express genes found in non-beta endocrine cells. By showing that Nkx6.1 binds to and represses the alpha cell determinant Arx, we identify Arx as a direct target of Nkx6.1. Moreover, we demonstrate that Nkx6.1 and the Arx activator Isl1 regulate Arx transcription antagonistically, thus establishing competition between Isl1 and Nkx6.1 as a critical mechanism for determining alpha versus beta cell identity. Our findings establish Nkx6.1 as a beta cell programming factor and demonstrate that repression of alternative lineage programs is a fundamental principle by which beta cells are specified and maintained. Given the lack of Nkx6.1 expression and aberrant activation of non-beta endocrine hormones in human embryonic stem cell (hESC)-derived insulin(+) cells, our study has significant implications for developing cell replacement therapies. PMID:23382704

  10. Beta-cell metabolic alterations under chronic nutrient overload in rat and human islets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this study was to assess multifactorial Beta-cell responses to metabolic perturbations in primary rat and human islets. Treatment of dispersed rat islet cells with elevated glucose and free fatty acids (FFAs, oleate:palmitate = 1:1 v/v) resulted in increases in the size and the number of ...

  11. Bulk-like endocytosis plays an important role in the recycling of insulin granules in pancreatic beta cells.

    PubMed

    Wen, Du; Xue, Yanhong; Liang, Kuo; Yuan, Tianyi; Lu, Jingze; Zhao, Wei; Xu, Tao; Chen, Liangyi

    2012-08-01

    Although bulk endocytosis has been found in a number of neuronal and endocrine cells, the molecular mechanism and physiological function of bulk endocytosis remain elusive. In pancreatic beta cells, we have observed bulk-like endocytosis evoked both by flash photolysis and trains of depolarization. Bulk-like endocytosis is a clathrin-independent process that is facilitated by enhanced extracellular Ca(2+) entry and suppressed by the inhibition of dynamin function. Moreover, defects in bulk-like endocytosis are accompanied by hyperinsulinemia in primary beta cells dissociated from diabetic KKAy mice, which suggests that bulk-like endocytosis plays an important role in maintaining the exo-endocytosis balance and beta cell secretory capability. PMID:22729398

  12. Induction of beta-cell resistance to hypoxia and technologies for oxygen delivery to transplanted pancreatic islets.

    PubMed

    Lazard, Daniel; Vardi, Pnina; Bloch, Konstantin

    2012-09-01

    Hypoxia is believed to be a crucial factor involved in cell adaptation to environmental stress. Islet transplantation, especially with immunoisolated islets, interrupts vascular connections, resulting in the substantially decreased delivery of oxygen and nutrients to islet cells. Insulin-producing pancreatic beta cells are known to be highly susceptible to oxygen deficiency. Such susceptibility to hypoxia is believed to be one of the main causes of beta-cell death in the post-transplantation period. Different strategies have been developed for the protection of beta cells against hypoxic injury and for oxygen delivery to transplanted islets. The enhancement of beta-cell defense properties against hypoxia has been achieved using various techniques such as gene transfection, drug supplementation, co-culturing with stem cells and cell selection. Technologies for oxygen delivery to transplanted islets include local neovascularization of subcutaneous sites, electrochemical and photosynthetic oxygen generation, oxygen refuelling of bio-artificial pancreas and whole body oxygenation by using hyperbaric therapy. Progress in the field of oxygen technologies for islet transplantation requires a multidisciplinary approach to explore and optimize the interaction between components of the biological system and different technological processes. This review article focuses mainly on the recently developed strategies for oxygenation and protection from hypoxic injury - to achieve stable and long-term normoglycaemia in diabetic patients with transplanted pancreatic islets. PMID:22389124

  13. Measuring phospholipase D activity in insulin-secreting pancreatic beta-cells and insulin-responsive muscle cells and adipocytes.

    PubMed

    Cazzolli, Rosanna; Huang, Ping; Teng, Shuzhi; Hughes, William E

    2009-01-01

    Phospholipase D (PLD) is an enzyme producing phosphatidic acid and choline through hydrolysis of phosphatidylcholine. The enzyme has been identified as a member of a variety of signal transduction cascades and as a key regulator of numerous intracellular vesicle trafficking processes. A role for PLD in regulating glucose homeostasis is emerging as the enzyme has recently been identified in events regulating exocytosis of insulin from pancreatic beta-cells and also in insulin-stimulated glucose uptake through controlling GLUT4 vesicle exocytosis in muscle and adipose tissue. We present methodologies for assessing cellular PLD activity in secretagogue-stimulated insulin-secreting pancreatic beta-cells and also insulin-stimulated adipocyte and muscle cells, two of the principal insulin-responsive cell types controlling blood glucose levels. PMID:19160674

  14. The Sherman-Rinzel-Keizer model for bursting electrical activity in the pancreatic. beta. -cell

    SciTech Connect

    Pernarowski, M.; Kevorkian, J. . Dept. of Applied Mathematics); Miura, R.M. )

    1990-03-01

    Pancreatic {beta}-cells exhibit periodic bursting electrical activity (BEA) consisting of active and silent phases. The Sherman-Rinzel-Keizer (SRK) model of this phenomenon consists of three coupled first-order nonlinear differential equations which describe the dynamics of the membrane potential, the activation parameter for the voltage-gated potassium channel, and the intracellular calcium concentration. These equations are nondimensionalized and transformed into a Lienard differential equation coupled to a single first-order differential equation for the slowly changing nondimensional calcium concentration. Leading-order perturbation problems are derived for the silent and active phases of the BEA on slow and fast time scales. Numerical solutions of these leading-order problems are compared with those for the exact equation in their respective regions. The leading-order solution in the active phase has a limit cycle behavior with a slowly varying frequency. It is observed that the damping term'' in the Lienard equation is small numerically. 26 refs., 6 figs., 2 tabs.

  15. Nkx6.1 is essential for maintaining the functional state of pancreatic beta cells.

    PubMed

    Taylor, Brandon L; Liu, Fen-Fen; Sander, Maike

    2013-09-26

    Recently, loss of beta-cell-specific traits has been proposed as an early cause of beta cell failure in diabetes. However, the molecular mechanisms that underlie the loss of beta cell features remain unclear. Here, we identify an Nkx6.1-controlled gene regulatory network as essential for maintaining the functional and molecular traits of mature beta cells. Conditional Nkx6.1 inactivation in adult mice caused rapid-onset diabetes and hypoinsulinemia. Genome-wide analysis of Nkx6.1-regulated genes and functional assays further revealed a critical role for Nkx6.1 in the control of insulin biosynthesis, insulin secretion, and beta cell proliferation. Over time, Nkx6.1-deficient beta cells acquired molecular characteristics of delta cells, revealing a molecular link between impaired beta cell functional properties and loss of cell identity. Given that Nkx6.1 levels are reduced in human type 2 diabetic beta cells, our study lends support to the concept that loss of beta cell features could contribute to the pathogenesis of diabetes. PMID:24035389

  16. Drp1 guarding of the mitochondrial network is important for glucose-stimulated insulin secretion in pancreatic beta cells.

    PubMed

    Reinhardt, Florian; Schultz, Julia; Waterstradt, Rica; Baltrusch, Simone

    2016-06-10

    Mitochondria form a tubular network in mammalian cells, and the mitochondrial life cycle is determined by fission, fusion and autophagy. Dynamin-related protein 1 (Drp1) has a pivotal role in these processes because it alone is able to constrict mitochondria. However, the regulation and function of Drp1 have been shown to vary between cell types. Mitochondrial morphology affects mitochondrial metabolism and function. In pancreatic beta cells mitochondrial metabolism is a key component of the glucose-induced cascade of insulin secretion. The goal of the present study was to investigate the action of Drp1 in pancreatic beta cells. For this purpose Drp1 was down-regulated by means of shDrp1 in insulin-secreting INS1 cells and mouse pancreatic islets. In INS1 cells reduced Drp1 expression resulted in diminished expression of proteins regulating mitochondrial fusion, namely mitofusin 1 and 2, and optic atrophy protein 1. Diminished mitochondrial dynamics can therefore be assumed. After down-regulation of Drp1 in INS1 cells and spread mouse islets the initially homogenous mitochondrial network characterised by a moderate level of interconnections shifted towards high heterogeneity with elongated, clustered and looped mitochondria. These morphological changes were found to correlate directly with functional alterations. Mitochondrial membrane potential and ATP generation were significantly reduced in INS1 cells after Drp1down-regulation. Finally, a significant loss of glucose-stimulated insulin secretion was demonstrated in INS1 cells and mouse pancreatic islets. In conclusion, Drp1 expression is important in pancreatic beta cells to maintain the regulation of insulin secretion. PMID:27154223

  17. Inorganic mercury causes pancreatic beta-cell death via the oxidative stress-induced apoptotic and necrotic pathways

    SciTech Connect

    Chen Yawen; Huang Chunfa; Yang Chingyao; Yen Chengchieh; Tsai Kehsung; Liu Shinghwa

    2010-03-15

    Mercury is a well-known highly toxic metal. In this study, we characterize and investigate the cytotoxicity and its possible mechanisms of inorganic mercury in pancreatic beta-cells. Mercury chloride (HgCl{sub 2}) dose-dependently decreased the function of insulin secretion and cell viability in pancreatic beta-cell-derived HIT-T15 cells and isolated mouse pancreatic islets. HgCl{sub 2} significantly increased ROS formation in HIT-T15 cells. Antioxidant N-acetylcysteine effectively reversed HgCl{sub 2}-induced insulin secretion dysfunction in HIT-T15 cells and isolated mouse pancreatic islets. Moreover, HgCl{sub 2} increased sub-G1 hypodiploids and annexin-V binding in HIT-T15 cells, indicating that HgCl{sub 2} possessed ability in apoptosis induction. HgCl{sub 2} also displayed several features of mitochondria-dependent apoptotic signals including disruption of the mitochondrial membrane potential, increase of mitochondrial cytochrome c release and activations of poly (ADP-ribose) polymerase (PARP) and caspase 3. Exposure of HIT-T15 cells to HgCl{sub 2} could significantly increase both apoptotic and necrotic cell populations by acridine orange/ethidium bromide dual staining. Meanwhile, HgCl{sub 2} could also trigger the depletion of intracellular ATP levels and increase the LDH release from HIT-T15 cells. These HgCl{sub 2}-induced cell death-related signals could be significantly reversed by N-acetylcysteine. The intracellular mercury levels were markedly elevated in HgCl{sub 2}-treated HIT-T15 cells. Taken together, these results suggest that HgCl{sub 2}-induced oxidative stress causes pancreatic beta-cell dysfunction and cytotoxicity involved the co-existence of apoptotic and necrotic cell death.

  18. GLIS3, a susceptibility gene for type 1 and type 2 diabetes, modulates pancreatic beta cell apoptosis via regulation of a splice variant of the BH3-only protein Bim.

    PubMed

    Nogueira, Tatiane C; Paula, Flavia M; Villate, Olatz; Colli, Maikel L; Moura, Rodrigo F; Cunha, Daniel A; Marselli, Lorella; Marchetti, Piero; Cnop, Miriam; Julier, Cécile; Eizirik, Decio L

    2013-05-01

    Mutations in human Gli-similar (GLIS) 3 protein cause neonatal diabetes. The GLIS3 gene region has also been identified as a susceptibility risk locus for both type 1 and type 2 diabetes. GLIS3 plays a role in the generation of pancreatic beta cells and in insulin gene expression, but there is no information on the role of this gene on beta cell viability and/or susceptibility to immune- and metabolic-induced stress. GLIS3 knockdown (KD) in INS-1E cells, primary FACS-purified rat beta cells, and human islet cells decreased expression of MafA, Ins2, and Glut2 and inhibited glucose oxidation and insulin secretion, confirming the role of this transcription factor for the beta cell differentiated phenotype. GLIS3 KD increased beta cell apoptosis basally and sensitized the cells to death induced by pro-inflammatory cytokines (interleukin 1β + interferon-γ) or palmitate, agents that may contribute to beta cell loss in respectively type 1 and 2 diabetes. The increased cell death was due to activation of the intrinsic (mitochondrial) pathway of apoptosis, as indicated by cytochrome c release to the cytosol, Bax translocation to the mitochondria and activation of caspases 9 and 3. Analysis of the pathways implicated in beta cell apoptosis following GLIS3 KD indicated modulation of alternative splicing of the pro-apoptotic BH3-only protein Bim, favouring expression of the pro-death variant BimS via inhibition of the splicing factor SRp55. KD of Bim abrogated the pro-apoptotic effect of GLIS3 loss of function alone or in combination with cytokines or palmitate. The present data suggest that altered expression of the candidate gene GLIS3 may contribute to both type 1 and 2 type diabetes by favouring beta cell apoptosis. This is mediated by alternative splicing of the pro-apoptotic protein Bim and exacerbated formation of the most pro-apoptotic variant BimS. PMID:23737756

  19. GLIS3, a Susceptibility Gene for Type 1 and Type 2 Diabetes, Modulates Pancreatic Beta Cell Apoptosis via Regulation of a Splice Variant of the BH3-Only Protein Bim

    PubMed Central

    Colli, Maikel L.; Moura, Rodrigo F.; Cunha, Daniel A.; Marselli, Lorella; Marchetti, Piero; Cnop, Miriam; Julier, Cécile; Eizirik, Decio L.

    2013-01-01

    Mutations in human Gli-similar (GLIS) 3 protein cause neonatal diabetes. The GLIS3 gene region has also been identified as a susceptibility risk locus for both type 1 and type 2 diabetes. GLIS3 plays a role in the generation of pancreatic beta cells and in insulin gene expression, but there is no information on the role of this gene on beta cell viability and/or susceptibility to immune- and metabolic-induced stress. GLIS3 knockdown (KD) in INS-1E cells, primary FACS-purified rat beta cells, and human islet cells decreased expression of MafA, Ins2, and Glut2 and inhibited glucose oxidation and insulin secretion, confirming the role of this transcription factor for the beta cell differentiated phenotype. GLIS3 KD increased beta cell apoptosis basally and sensitized the cells to death induced by pro-inflammatory cytokines (interleukin 1β + interferon-γ) or palmitate, agents that may contribute to beta cell loss in respectively type 1 and 2 diabetes. The increased cell death was due to activation of the intrinsic (mitochondrial) pathway of apoptosis, as indicated by cytochrome c release to the cytosol, Bax translocation to the mitochondria and activation of caspases 9 and 3. Analysis of the pathways implicated in beta cell apoptosis following GLIS3 KD indicated modulation of alternative splicing of the pro-apoptotic BH3-only protein Bim, favouring expression of the pro-death variant BimS via inhibition of the splicing factor SRp55. KD of Bim abrogated the pro-apoptotic effect of GLIS3 loss of function alone or in combination with cytokines or palmitate. The present data suggest that altered expression of the candidate gene GLIS3 may contribute to both type 1 and 2 type diabetes by favouring beta cell apoptosis. This is mediated by alternative splicing of the pro-apoptotic protein Bim and exacerbated formation of the most pro-apoptotic variant BimS. PMID:23737756

  20. Direct Reprogramming for Pancreatic Beta-Cells Using Key Developmental Genes

    PubMed Central

    Cavelti-Weder, Claudia; Li, Weida; Zumsteg, Adrian; Stemann, Marianne; Yamada, Takatsugu; Bonner-Weir, Susan; Weir, Gordon

    2015-01-01

    Direct reprogramming is a promising approach for regenerative medicine whereby one cell type is directly converted into another without going through a multipotent or pluripotent stage. This reprogramming approach has been extensively explored for the generation of functional insulin-secreting cells from non-beta-cells with the aim of developing novel cell therapies for the treatment of people with diabetes lacking sufficient endogenous beta-cells. A common approach for such conversion studies is the introduction of key regulators that are important in controlling beta-cell development and maintenance. In this review, we will summarize the recent advances in the field of beta-cell reprogramming and discuss the challenges of creating functional and long-lasting beta-cells. PMID:26998407

  1. Glucagon-Like Peptide-1 Triggers Protective Pathways in Pancreatic Beta-Cells Exposed to Glycated Serum

    PubMed Central

    Puddu, Alessandra; Sanguineti, Roberta; Durante, Arianna; Nencioni, Alessio; Mach, François; Montecucco, Fabrizio; Viviani, Giorgio L.

    2013-01-01

    Advanced glycation end products (AGEs) might play a pathophysiological role in the development of diabetes and its complications. AGEs negatively affect pancreatic beta-cell function and the expression of transcriptional factors regulating insulin gene. Glucagon-like peptide-1 (GLP-1), an incretin hormone that regulates glucose homeostasis, might counteract the harmful effects of AGEs on the beta cells in culture. The aim of this study was to identify the intracellular mechanisms underlying GLP-1-mediated protection from AGE-induced detrimental activities in pancreatic beta cells. HIT-T15 cells were cultured for 5 days with glycated serum (GS, consisting in a pool of AGEs), in the presence or absence of 10 nmol/L GLP-1. After evaluation of oxidative stress, we determined the expression and subcellular localization of proteins involved in maintaining redox balance and insulin gene expression, such as nuclear factor erythroid-derived 2 (Nrf2), glutathione reductase, PDX-1, and MafA. Then, we investigated proinsulin production. The results showed that GS increased oxidative stress, reduced protein expression of all investigated factors through proteasome activation, and decreased proinsulin content. Furthermore, GS reduced ability of PDX-1 and MafA to bind DNA. Coincubation with GLP-1 reversed these GS-mediated detrimental effects. In conclusion, GLP-1, protecting cells against oxidants, triggers protective intercellular pathways in HIT-T15 cells exposed to GS. PMID:23737644

  2. Incretin Receptor Null Mice Reveal Key Role of GLP-1 but Not GIP in Pancreatic Beta Cell Adaptation to Pregnancy

    PubMed Central

    Moffett, R. Charlotte; Vasu, Srividya; Thorens, Bernard; Drucker, Daniel J.; Flatt, Peter R.

    2014-01-01

    Islet adaptations to pregnancy were explored in C57BL6/J mice lacking functional receptors for glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP). Pregnant wild type mice and GIPRKO mice exhibited marked increases in islet and beta cell area, numbers of medium/large sized islets, with positive effects on Ki67/Tunel ratio favouring beta cell growth and enhanced pancreatic insulin content. Alpha cell area and glucagon content were unchanged but prohormone convertases PC2 and PC1/3 together with significant amounts of GLP-1 and GIP were detected in alpha cells. Knockout of GLP-1R abolished these islet adaptations and paradoxically decreased pancreatic insulin, GLP-1 and GIP. This was associated with abolition of normal pregnancy-induced increases in plasma GIP, L-cell numbers, and intestinal GIP and GLP-1 stores. These data indicate that GLP-1 but not GIP is a key mediator of beta cell mass expansion and related adaptations in pregnancy, triggered in part by generation of intra-islet GLP-1. PMID:24927416

  3. Nicotinamide-functionalized multiwalled carbon nanotubes increase insulin production in pancreatic beta cells via MIF pathway

    PubMed Central

    Ilie, Ioana; Ilie, Razvan; Mocan, Teodora; Tabaran, Flaviu; Iancu, Cornel; Mocan, Lucian

    2013-01-01

    Recent data in the literature support the role of nicotinamide (NA) as a pharmacologic agent that stimulates pancreatic beta-cells to produce insulin in vitro. There are data showing that carbon nanotubes may be useful in initiating and maintaining cellular metabolic responses. This study shows that administration of multiwalled carbon nanotubes (MWCNTs) functionalized with nicotinamide (NA-MWCNTs) leads to significant insulin production compared with individual administration of NA, MWCNTs, and a control solution. Treatment of 1.4E7 cells for 30 minutes with NA-MWCNTs at concentrations ranging from 1 mg/L to 20 mg/L resulted in significantly increased insulin release (0.18 ± 0.026 ng/mL for 1 mg/L, 0.21 ± 0.024 ng/mL for 5 mg/L, and 0.27 ± 0.028 ng/mL for 20 mg/L). Thus, compared with cells treated with NA only (0.1 ± 0.01 ng/mL for 1 mg/L, 0.12 ± 0.017 ng/mL for 5 mg/L, and 0.17 ± 0.01 ng/mL for 20 mg/L) we observed a significant positive effect on insulin release in cells treated with NA-MWCNTs. The results were confirmed using flow cytometry, epifluorescence microscopy combined with immunochemistry staining, and enzyme-linked immunosorbent assay techniques. In addition, using immunofluorescence microscopy techniques, we were able to demonstrate that MWCNTs enhance insulin production via the macrophage migration inhibitory factor pathway. The application and potential of NA combined with MWCNTs as an antidiabetic agent may represent the beginning of a new chapter in the nanomediated treatment of diabetes mellitus. PMID:24039418

  4. Knockdown of prolactin receptors in a pancreatic beta cell line: effects on DNA synthesis, apoptosis, and gene expression.

    PubMed

    Arumugam, Ramamani; Fleenor, Don; Freemark, Michael

    2014-08-01

    Prolactin (PRL) and placental lactogen stimulate beta cell replication and insulin production in vitro and in vivo. The molecular mechanisms by which lactogens promote beta cell expansion are unclear. We treated rat insulinoma cells with a PRL receptor (PRLR) siRNA to determine if PRLR signaling is required for beta cell DNA synthesis and cell survival and to identify beta cell cycle genes whose expression depends upon lactogen action. Effects of PRLR knockdown were compared with those of PRL treatment. PRLR knockdown (-80 %) reduced DNA synthesis, increased apoptosis, and inhibited expression of cyclins D2 and B2, IRS-2, Tph1, and the anti-apoptotic protein PTTG1; p21 and BCL6 mRNAs increased. Conversely, PRL treatment increased DNA synthesis, reduced apoptosis, and enhanced expression of A, B and D2 cyclins, CDK1, IRS-2, FoxM1, BCLxL, and PTTG1; BCL6 declined. PRLR signaling is required for DNA synthesis and survival of rat insulinoma cells. The effects of lactogens are mediated by down-regulation of cell cycle inhibitors (BCL6, p21) and induction of A, B, and D2 cyclins, IRS-2, Tph1, FoxM1, and the anti-apoptotic proteins BCLxL and PTTG1. PMID:24114406

  5. Maternal obesity accelerates fetal pancreatic beta-cell but not alpha-cell development in sheep: prenatal consequences.

    PubMed

    Ford, Stephen P; Zhang, Liren; Zhu, Meijun; Miller, Myrna M; Smith, Derek T; Hess, Bret W; Moss, Gary E; Nathanielsz, Peter W; Nijland, Mark J

    2009-09-01

    Maternal obesity affects offspring weight, body composition, and organ function, increasing diabetes and metabolic syndrome risk. We determined effects of maternal obesity and a high-energy diet on fetal pancreatic development. Sixty days prior to breeding, ewes were assigned to control [100% of National Research Council (NRC) recommendations] or obesogenic (OB; 150% NRC) diets. At 75 days gestation, OB ewes exhibited elevated insulin-to-glucose ratios at rest and during a glucose tolerance test, demonstrating insulin resistance compared with control ewes. In fetal studies, ewes ate their respective diets from 60 days before to 75 days after conception when animals were euthanized under general anesthesia. OB and control ewes increased in body weight by approximately 43% and approximately 6%, respectively, from diet initiation until necropsy. Although all organs were heavier in fetuses from OB ewes, only pancreatic weight increased as a percentage of fetal weight. Blood glucose, insulin, and cortisol were elevated in OB ewes and fetuses on day 75. Insulin-positive cells per unit pancreatic area were 50% greater in fetuses from OB ewes as a result of increased beta-cell mitoses rather than decreased programmed cell death. Lambs of OB ewes were born earlier but weighed the same as control lambs; however, their crown-to-rump length was reduced, and their fat mass was increased. We conclude that increased systemic insulin in fetuses from OB ewes results from increased glucose exposure and/or cortisol-induced accelerated fetal beta-cell maturation and may contribute to premature beta-cell function loss and predisposition to obesity and metabolic disease in offspring. PMID:19605766

  6. The class I histone deacetylase inhibitor MS-275 prevents pancreatic beta cell death induced by palmitate.

    PubMed

    Plaisance, Valérie; Rolland, Laure; Gmyr, Valéry; Annicotte, Jean-Sébastien; Kerr-Conte, Julie; Pattou, François; Abderrahmani, Amar

    2014-01-01

    Elevation of the dietary saturated fatty acid palmitate contributes to the reduction of functional beta cell mass in the pathogenesis of type 2 diabetes. The diabetogenic effect of palmitate is achieved by increasing beta cell death through induction of the endoplasmic reticulum (ER) stress markers including activating transcription factor 3 (Atf3) and CAAT/enhancer-binding protein homologous protein-10 (Chop). In this study, we investigated whether treatment of beta cells with the MS-275, a HDAC1 and HDAC3 activity inhibitor which prevents beta cell death elicited by cytokines, is beneficial for combating beta cell dysfunction caused by palmitate. We show that culture of isolated human islets and MIN6 cells with MS-275 reduced apoptosis evoked by palmitate. The protective effect of MS-275 was associated with the attenuation of the expression of Atf3 and Chop. Silencing of HDAC3, but not of HDAC1, mimicked the effects of MS-275 on the expression of the two ER stress markers and apoptosis. These data point to HDAC3 as a potential drug target for preserving beta cells against lipotoxicity in diabetes. PMID:25610877

  7. The Class I Histone Deacetylase Inhibitor MS-275 Prevents Pancreatic Beta Cell Death Induced by Palmitate

    PubMed Central

    Plaisance, Valérie; Rolland, Laure; Gmyr, Valéry; Annicotte, Jean-Sébastien; Kerr-Conte, Julie; Pattou, François; Abderrahmani, Amar

    2014-01-01

    Elevation of the dietary saturated fatty acid palmitate contributes to the reduction of functional beta cell mass in the pathogenesis of type 2 diabetes. The diabetogenic effect of palmitate is achieved by increasing beta cell death through induction of the endoplasmic reticulum (ER) stress markers including activating transcription factor 3 (Atf3) and CAAT/enhancer-binding protein homologous protein-10 (Chop). In this study, we investigated whether treatment of beta cells with the MS-275, a HDAC1 and HDAC3 activity inhibitor which prevents beta cell death elicited by cytokines, is beneficial for combating beta cell dysfunction caused by palmitate. We show that culture of isolated human islets and MIN6 cells with MS-275 reduced apoptosis evoked by palmitate. The protective effect of MS-275 was associated with the attenuation of the expression of Atf3 and Chop. Silencing of HDAC3, but not of HDAC1, mimicked the effects of MS-275 on the expression of the two ER stress markers and apoptosis. These data point to HDAC3 as a potential drug target for preserving beta cells against lipotoxicity in diabetes. PMID:25610877

  8. Adult Human Pancreatic Islet Beta-Cells Display Limited Turnover and Long Lifespan as Determined by In-Vivo Thymidine Analog Incorporation and Radiocarbon Dating

    SciTech Connect

    Perl, S; Kushner, J A; Buchholz, B A; Meeker, A K; Stein, G M; Hsieh, M; Kirby, M; Pechhold, S; Liu, E H; Harlan, D M; Tisdale, J F

    2010-03-15

    Diabetes mellitus results from an absolute or relative deficiency of insulin producing pancreatic beta-cells. The adult human beta-cell's turnover rate remains unknown. We employed novel techniques to examine adult human islet beta-cell turnover and longevity in vivo. Subjects enrolled in NIH clinical trials received thymidine analogues [iododeoxyuridine (IdU) or bromodeoxyuridine (BrdU)] 8-days to 4-years prior to death. Archival autopsy samples from ten patients (aged 17-74 years) were employed to assess beta-cell turnover by scoring nuclear analog labeling within insulin staining cells. Human adult beta-cell longevity was determined by estimating the cells genomic DNA integration of atmospheric carbon-14 ({sup 14}C). DNA was purified from pancreatic islets isolated from cadaveric donors; whole islet prep DNA was obtained from a 15 year old donor, and purified beta-cell DNA was obtained from two donors (age 48 and 80 years). {sup 14}C levels were then determined using accelerator mass spectrometry (AMS). Cellular 'birth date' was determined by comparing the subject's DNA {sup 14}C content relative to a well-established {sup 14}C atmospheric prevalence curve. In the two subjects less than age 20 years, 1-2% of the beta-cell nuclei co-stained for BrdU/IdU. No beta-cell nuclei co-stained in the eight patients more than 30 years old. Consistent with the BrdU/IdU turnover data, beta-cell DNA {sup 14}C content indicated the cells 'birth date' occurred within the subject's first 30 years of life. Under typical circumstances, adult human beta-cells and their cellular precursors are established by young adulthood.

  9. Beneficial effect of 17{beta}-estradiol on hyperglycemia and islet {beta}-cell functions in a streptozotocin-induced diabetic rat model

    SciTech Connect

    Yamabe, Noriko; Kang, Ki Sung; Zhu Baoting

    2010-11-15

    The modulating effect of estrogen on glucose homeostasis remains a controversial issue at present. In this study, we sought to determine the beneficial effect of 17{beta}-estradiol (E{sub 2}) on hyperglycemia and islet {beta}-cell functions in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were injected i.p. with STZ to induce a relatively mild diabetic condition. The rats were then treated with E{sub 2} orally at 500 {mu}g/kg body weight/day for 15 days to evaluate the modulating effect on hyperglycemia, insulin secretion, and islet {beta}-cell proliferation. E{sub 2} administration for 10 days significantly lowered plasma glucose levels, increased plasma insulin levels, and improved glucose tolerance by attenuating insulin response to oral glucose loading. These beneficial effects of E{sub 2} were accompanied by increases in islet number and volume, rate of islet cell proliferation, and the amount of insulin secreted. The growth-stimulatory effect of E{sub 2} on islet cells was linked to the functions of the estrogen receptor {alpha}. Notably, these protective effects of E{sub 2} on diabetic conditions were basically not observed when the STZ-treated rats had a more severe degree of islet damage and hyperglycemia. Taken together, we conclude that E{sub 2} can promote the regeneration of damaged pancreatic islets by stimulating {beta}-cell proliferation in diabetic rats, and this effect is accompanied by improvements in glucose tolerance and a decrease in plasma glucose levels. These findings suggest that oral administration of E{sub 2} may be beneficial in diabetic patients with an accelerated loss of islet {beta}-cells.

  10. Inter-domain tagging implicates caveolin-1 in insulin receptor trafficking and Erk signaling bias in pancreatic beta-cells

    PubMed Central

    Boothe, Tobias; Lim, Gareth E.; Cen, Haoning; Skovsø, Søs; Piske, Micah; Li, Shu Nan; Nabi, Ivan R.; Gilon, Patrick; Johnson, James D.

    2016-01-01

    Objective The role and mechanisms of insulin receptor internalization remain incompletely understood. Previous trafficking studies of insulin receptors involved fluorescent protein tagging at their termini, manipulations that may be expected to result in dysfunctional receptors. Our objective was to determine the trafficking route and molecular mechanisms of functional tagged insulin receptors and endogenous insulin receptors in pancreatic beta-cells. Methods We generated functional insulin receptors tagged with pH-resistant fluorescent proteins between domains. Confocal, TIRF and STED imaging revealed a trafficking pattern of inter-domain tagged insulin receptors and endogenous insulin receptors detected with antibodies. Results Surprisingly, interdomain-tagged and endogenous insulin receptors in beta-cells bypassed classical Rab5a- or Rab7-mediated endocytic routes. Instead, we found that removal of insulin receptors from the plasma membrane involved tyrosine-phosphorylated caveolin-1, prior to trafficking within flotillin-1-positive structures to lysosomes. Multiple methods of inhibiting caveolin-1 significantly reduced Erk activation in vitro or in vivo, while leaving Akt signaling mostly intact. Conclusions We conclude that phosphorylated caveolin-1 plays a role in insulin receptor internalization towards lysosomes through flotillin-1-positive structures and that caveolin-1 helps bias physiological beta-cell insulin signaling towards Erk activation. PMID:27110488

  11. Neogenesis and proliferation of {beta}-cells induced by human betacellulin gene transduction via retrograde pancreatic duct injection of an adenovirus vector

    SciTech Connect

    Tokui, Yae . E-mail: ytokui@imed2.med.osaka-u.ac.jp; Kozawa, Junji; Yamagata, Kazuya; Zhang, Jun; Ohmoto, Hiroshi; Tochino, Yoshihiro; Okita, Kohei; Iwahashi, Hiromi; Namba, Mitsuyoshi; Shimomura, Iichiro; Miyagawa, Jun-ichiro |

    2006-12-01

    Betacellulin (BTC) has been shown to have a role in the differentiation and proliferation of {beta}-cells both in vitro and in vivo. We administered a human betacellulin (hBTC) adenovirus vector to male ICR mice via retrograde pancreatic duct injection. As a control, we administered a {beta}-galactosidase adenovirus vector. In the mice, hBTC protein was mainly overexpressed by pancreatic duct cells. On immunohistochemical analysis, we observed features of {beta}-cell neogenesis as newly formed insulin-positive cells in the duct cell lining or islet-like cell clusters (ICCs) closely associated with the ducts. The BrdU labeling index of {beta}-cells was also increased by the betacellulin vector compared with that of control mice. These results indicate that hBTC gene transduction into adult pancreatic duct cells promoted {beta}-cell differentiation (mainly from duct cells) and proliferation of pre-existing {beta}-cells, resulting in an increase of the {beta}-cell mass that improved glucose tolerance in diabetic mice.

  12. ER stress and the decline and fall of pancreatic beta cells in type 1 diabetes

    PubMed Central

    Brozzi, Flora

    2016-01-01

    Components of the unfolded protein response (UPR) modulate beta cell inflammation and death in early type 1 diabetes (T1D). The UPR is a mechanism by which cells react to the accumulation of misfolded proteins in the endoplasmic reticulum (ER). It aims to restore cellular homeostasis, but in case of chronic or overwhelming ER stress the persistent activation of the UPR triggers apoptosis, contributing to the loss of beta cells in both T1D and type 2 diabetes. It remains to be determined how and why the transition from ‘physiological’ to ‘pathological’ UPR takes place. A key component of the UPR is the ER transmembrane protein IRE1α (inositol-requiring enzyme 1α). IRE1α activity is modulated by both intra-ER signals and by the formation of protein complexes at its cytosolic domain. The amplitude and duration of IRE1α signaling is critical for the transition between the adaptive and cell death programs, with particular relevance for the activation of the pro-apoptotic c-Jun N-terminal kinase (JNK) in beta cells. In the present review we discuss the available information on IRE1α-regulating proteins in beta cells and their downstream targets, and the important differences observed between cytokine-induced UPR in human and rodent beta cells. PMID:26899404

  13. Baculovirus p35 increases pancreatic {beta}-cell resistance to apoptosis

    SciTech Connect

    Hollander, Kenneth; Bar-Chen, Michal; Efrat, Shimon . E-mail: sefrat@post.tau.ac.il

    2005-07-01

    {beta}-cells die by apoptosis in type 1 diabetes as a result of autoimmune attack mediated by cytokines, and in type 2 diabetes by various perpetrators including human islet amyloid polypeptide (hIAPP). The cascade of apoptotic events induced by cytokines and hIAPP is mediated through caspases and reactive oxygen species. The baculovirus p35 protein is a potent anti-apoptotic agent shown to be effective in a variety of species and able to inhibit a number of apoptotic pathways. Here, we aimed at determining the protective potential of p35 in {beta}-cells exposed to cytokines and hIAPP, as well as the effects of p35 on {beta}-cell function. The p35 gene was introduced into {beta}TC-tet cells, a differentiated murine {beta}-cell line capable of undergoing inducible growth-arrest. Both proliferating and growth-arrested cells expressing p35 manifested increased resistance to cytokines and hIAPP, compared with control cells, as judged by cell viability, DNA fragmentation, and caspase-3 activity assays. p35 was significantly more protective in growth-arrested, compared with proliferating, cells. No significant differences were observed in proliferation and insulin content between cells expressing p35 and control cells. In contrast, p35 manifested a perturbing effect on glucose-induced insulin secretion. These findings suggest that p35 could be incorporated as part of a multi-pronged approach of immunoprotective strategies to provide protection from recurring autoimmunity for transplanted {beta}-cells, as well as in preventive gene therapy in type 1 diabetes. p35 may also be protective from {beta}-cell damage caused by hIAPP in type 2 diabetes.

  14. Restoring Mitochondrial Function: A Small Molecule-mediated Approach to Enhance Glucose Stimulated Insulin Secretion in Cholesterol Accumulated Pancreatic beta cells

    PubMed Central

    Asalla, Suman; Girada, Shravan Babu; Kuna, Ramya S.; Chowdhury, Debabrata; Kandagatla, Bhaskar; Oruganti, Srinivas; Bhadra, Utpal; Bhadra, Manika Pal; Kalivendi, Shasi Vardhan; Rao, Swetha Pavani; Row, Anupama; Ibrahim, A; Ghosh, Partha Pratim; Mitra, Prasenjit

    2016-01-01

    Dyslipidemia, particularly the elevated serum cholesterol levels, aggravate the pathophysiology of type 2 diabetes. In the present study we explored the relationship between fasting blood sugar and serum lipid parameters in human volunteers which revealed a significant linear effect of serum cholesterol on fasting blood glucose. Short term feeding of cholesterol enriched diet to rodent model resulted in elevated serum cholesterol levels, cholesterol accumulation in pancreatic islets and hyperinsulinemia with modest increase in plasma glucose level. To explore the mechanism, we treated cultured BRIN-BD11 pancreatic beta cells with soluble cholesterol. Our data shows that cholesterol treatment of cultured pancreatic beta cells enhances total cellular cholesterol. While one hour cholesterol exposure enhances insulin exocytosis, overnight cholesterol accumulation in cultured pancreatic beta cells affects cellular respiration, and inhibits Glucose stimulated insulin secretion. We further report that (E)-4-Chloro-2-(1-(2-(2,4,6-trichlorophenyl) hydrazono) ethyl) phenol (small molecule M1) prevents the cholesterol mediated blunting of cellular respiration and potentiates Glucose stimulated insulin secretion which was abolished in pancreatic beta cells on cholesterol accumulation. PMID:27282931

  15. Restoring Mitochondrial Function: A Small Molecule-mediated Approach to Enhance Glucose Stimulated Insulin Secretion in Cholesterol Accumulated Pancreatic beta cells.

    PubMed

    Asalla, Suman; Girada, Shravan Babu; Kuna, Ramya S; Chowdhury, Debabrata; Kandagatla, Bhaskar; Oruganti, Srinivas; Bhadra, Utpal; Bhadra, Manika Pal; Kalivendi, Shasi Vardhan; Rao, Swetha Pavani; Row, Anupama; Ibrahim, A; Ghosh, Partha Pratim; Mitra, Prasenjit

    2016-01-01

    Dyslipidemia, particularly the elevated serum cholesterol levels, aggravate the pathophysiology of type 2 diabetes. In the present study we explored the relationship between fasting blood sugar and serum lipid parameters in human volunteers which revealed a significant linear effect of serum cholesterol on fasting blood glucose. Short term feeding of cholesterol enriched diet to rodent model resulted in elevated serum cholesterol levels, cholesterol accumulation in pancreatic islets and hyperinsulinemia with modest increase in plasma glucose level. To explore the mechanism, we treated cultured BRIN-BD11 pancreatic beta cells with soluble cholesterol. Our data shows that cholesterol treatment of cultured pancreatic beta cells enhances total cellular cholesterol. While one hour cholesterol exposure enhances insulin exocytosis, overnight cholesterol accumulation in cultured pancreatic beta cells affects cellular respiration, and inhibits Glucose stimulated insulin secretion. We further report that (E)-4-Chloro-2-(1-(2-(2,4,6-trichlorophenyl) hydrazono) ethyl) phenol (small molecule M1) prevents the cholesterol mediated blunting of cellular respiration and potentiates Glucose stimulated insulin secretion which was abolished in pancreatic beta cells on cholesterol accumulation. PMID:27282931

  16. βIV-Spectrin and CaMKII facilitate Kir6.2 regulation in pancreatic beta cells

    PubMed Central

    Kline, Crystal F.; Wright, Patrick J.; Koval, Olha M.; Zmuda, Erik J.; Johnson, Benjamin L.; Anderson, Mark E.; Hai, Tsonwin; Hund, Thomas J.; Mohler, Peter J.

    2013-01-01

    Identified over a dozen years ago in the brain and pancreatic islet, βIV-spectrin is critical for the local organization of protein complexes throughout the nervous system. βIV-Spectrin targets ion channels and adapter proteins to axon initial segments and nodes of Ranvier in neurons, and βIV-spectrin dysfunction underlies ataxia and early death in mice. Despite advances in βIV-spectrin research in the nervous system, its role in pancreatic islet biology is unknown. Here, we report that βIV-spectrin serves as a multifunctional structural and signaling platform in the pancreatic islet. We report that βIV-spectrin directly associates with and targets the calcium/calmodulin-dependent protein kinase II (CaMKII) in pancreatic islets. In parallel, βIV-spectrin targets ankyrin-B and the ATP-sensitive potassium channel. Consistent with these findings, βIV-spectrin mutant mice lacking CaMKII- or ankyrin-binding motifs display selective loss of expression and targeting of key protein components, including CaMKIIδ. βIV-Spectrin–targeted CaMKII directly phosphorylates the inwardly-rectifying potassium channel, Kir6.2 (alpha subunit of KATP channel complex), and we identify the specific residue, Kir6.2 T224, responsible for CaMKII-dependent regulation of KATP channel function. CaMKII-dependent phosphorylation alters channel regulation resulting in KATP channel inhibition, a cellular phenotype consistent with aberrant insulin regulation. Finally, we demonstrate aberrant KATP channel phosphorylation in βIV-spectrin mutant mice. In summary, our findings establish a broader role for βIV-spectrin in regulation of cell membrane excitability in the pancreatic islet, define the pathway for CaMKII local control in pancreatic beta cells, and identify the mechanism for CaMKII-dependent regulation of KATP channels. PMID:24101510

  17. βIV-Spectrin and CaMKII facilitate Kir6.2 regulation in pancreatic beta cells.

    PubMed

    Kline, Crystal F; Wright, Patrick J; Koval, Olha M; Zmuda, Erik J; Johnson, Benjamin L; Anderson, Mark E; Hai, Tsonwin; Hund, Thomas J; Mohler, Peter J

    2013-10-22

    Identified over a dozen years ago in the brain and pancreatic islet, βIV-spectrin is critical for the local organization of protein complexes throughout the nervous system. βIV-Spectrin targets ion channels and adapter proteins to axon initial segments and nodes of Ranvier in neurons, and βIV-spectrin dysfunction underlies ataxia and early death in mice. Despite advances in βIV-spectrin research in the nervous system, its role in pancreatic islet biology is unknown. Here, we report that βIV-spectrin serves as a multifunctional structural and signaling platform in the pancreatic islet. We report that βIV-spectrin directly associates with and targets the calcium/calmodulin-dependent protein kinase II (CaMKII) in pancreatic islets. In parallel, βIV-spectrin targets ankyrin-B and the ATP-sensitive potassium channel. Consistent with these findings, βIV-spectrin mutant mice lacking CaMKII- or ankyrin-binding motifs display selective loss of expression and targeting of key protein components, including CaMKIIδ. βIV-Spectrin-targeted CaMKII directly phosphorylates the inwardly-rectifying potassium channel, Kir6.2 (alpha subunit of KATP channel complex), and we identify the specific residue, Kir6.2 T224, responsible for CaMKII-dependent regulation of KATP channel function. CaMKII-dependent phosphorylation alters channel regulation resulting in KATP channel inhibition, a cellular phenotype consistent with aberrant insulin regulation. Finally, we demonstrate aberrant KATP channel phosphorylation in βIV-spectrin mutant mice. In summary, our findings establish a broader role for βIV-spectrin in regulation of cell membrane excitability in the pancreatic islet, define the pathway for CaMKII local control in pancreatic beta cells, and identify the mechanism for CaMKII-dependent regulation of KATP channels. PMID:24101510

  18. CREB is a regulatory target for the protein kinase Akt/PKB in the differentiation of pancreatic ductal cells into islet {beta}-cells mediated by hepatocyte growth factor

    SciTech Connect

    Li, Xin-Yu; Zhan, Xiao-Rong; Liu, Xiao-Min; Wang, Xiao-Chen

    2011-01-14

    Research highlights: {yields} CREB is a regulatory target for the protein kinase Akt/PKB in pancreatic duct cells. {yields} Activation of the PI3K/AKT/CREB pathway plays a critical role in the HGF-mediated differentiation of pancreatic duct cells in vivo. {yields} CREB was causally linked to the expression of transcription factors during PDEC differentiation induced by HGF. -- Abstract: We have previously reported that the PI3K/Akt signaling pathway is involved in hepatocyte growth factor (HGF)-induced differentiation of adult rat pancreatic ductal epithelial cells (PDECs) into islet {beta}-cells in vitro. The transcription factor CREB is one of the downstream key effectors of the PI3K/Akt signaling pathway. Recent studies showing that CREB is required for the survival of certain cell types prompted us to examine whether CREB is a nuclear target for activation via the HGF-dependent Ser/Thr kinase Akt/PKB in the differentiation of pancreatic duct cell into islet {beta}-cells. In this study, we first attempted to examine whether HGF modulates the Akt-dependent activation of target gene CREB and then investigated whether CREB activity affects the differentiation of HGF-induced PDECs. Finally, we studied the role of CREB in modulating the expression of transcription factors in PDECs during the differentiation of HGF-induced PDECs. Our results demonstrated that CREB is a regulatory target for the protein kinase Akt/PKB in the differentiation of pancreatic ductal cells into islet {beta}-cells mediated by HGF.

  19. Glucose tolerance normalization following transplantation of pig pancreatic primordia into non-immunosuppressed diabetic ZDF rats.

    PubMed

    Rogers, Sharon A; Chen, Feng; Talcott, Mike; Liapis, Helen; Hammerman, Marc R

    2006-11-01

    Pancreas or pancreatic islet transplantation in humans is limited by organ availability, and success of the latter is negatively impacted upon by tissue loss post-transplantation and limited potential for expansion of beta cells. A way to overcome the supply and expansion problems is to xenotransplant embryonic tissue. Previously, we have shown that beta cells originating from embryonic day (E) 28 (E28) pig pancreatic primordia transplanted into the mesentery of streptozotocin-diabetic (type 1) Lewis rats engraft without the need for host immune-suppression and normalize glucose tolerance. Here we show long-term engraftment of pig beta cells within liver, pancreas and mesenteric lymph nodes post-transplantation of E28 pig pancreatic primordia into diabetic ZDF rats, a model for type 2 diabetes. Porcine insulin is present in circulation after an oral glucose load. Glucose tolerance is normalized in transplanted ZDF hosts and insulin sensitivity restored in formerly diabetic ZDF males. Release of porcine insulin in vitro from tissue originating in transplanted rats occurs within 1 min of glucose stimulation characteristic of first-phase secretion from beta cells. Of potential importance for application of this transplantation technology to treatment of type 2 diabetes in humans and confirmatory of our previous findings in Lewis rats, no host immunosuppression is required for engraftment of E28 pig pancreatic primordia. PMID:17138051

  20. Analysis of the noise-induced bursting-spiking transition in a pancreatic beta-cell model.

    PubMed

    Aguirre, Jacobo; Mosekilde, Erik; Sanjuán, Miguel A F

    2004-04-01

    A stochastic model of the electrophysiological behavior of the pancreatic beta cell is studied, as a paradigmatic example of a bursting biological cell embedded in a noisy environment. The analysis is focused on the distortion that a growing noise causes to the basic properties of the membrane potential signals, such as their periodic or chaotic nature, and their bursting or spiking behavior. We present effective computational tools to obtain as much information as possible from these signals, and we suggest that the methods could be applied to real time series. Finally, a universal dependence of the main characteristics of the membrane potential on the size of the considered cell cluster is presented. PMID:15169046

  1. Endocytosis of secretory granules in mouse pancreatic beta-cells evoked by transient elevation of cytosolic calcium.

    PubMed Central

    Eliasson, L; Proks, P; Ammälä, C; Ashcroft, F M; Bokvist, K; Renström, E; Rorsman, P; Smith, P A

    1996-01-01

    1. To investigate the mechanisms regulating the reuptake of secretory granule membranes following regulated exocytosis, we have monitored changes in cell capacitance in single pancreatic beta-cells. 2. Membrane retrieval (endocytosis) occurred both in a continuous manner and in abrupt steps, corresponding to the simultaneous retrieval of 50-100 granules. The large endocytotic steps were associated with a conductance change of about 1 nS which we attribute to the formation of a fission pore with a pore radius of approximately 1 nm. 3. In some cells, we observed large amplitude capacitance fluctuations, suggesting that aggregates of granules are connected to the plasma membrane by a single pore and are subsequently retrieved as a single unit. 4. Endocytosis was evoked by elevation of cytosolic [Ca2+]i, but once initiated, a sustained increase in [Ca2+]i was not required for endocytosis to continue. 5. The [Ca2+]i dependence of exo- and endocytosis was studied by photorelease of Ca2+ from the 'caged' precursor Ca(2+)-nitrophenyl-EGTA (Ca(2+)-NP-EGTA). Both exo- and endocytosis were initiated at between 0.5 and 2 microM Cai(2+). The rate of endocytosis saturated above 2 microM Cai(2+), whereas exocytosis continued to increase up to 4 microM Cai(2+). The maximum rate of endocytosis was < 25% of that of exocytosis. 6. Unlike exocytosis, endocytosis proceeded equally well in the presence or absence of Mg-ATP. 7. Our data indicate that in the pancreatic beta-cell, exocytosis and endocytosis are regulated by different mechanisms. Images Figure 6 Figure 8 PMID:8799897

  2. Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis

    PubMed Central

    Fridlyand, Leonid E.; Philipson, Louis H.

    2016-01-01

    Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger

  3. In vitro effects of mycophenolic acid on survival, function, and gene expression of pancreatic beta-cells.

    PubMed

    Gallo, R; Natale, M; Vendrame, F; Boggi, U; Filipponi, F; Marchetti, P; Laghi Pasini, F; Dotta, F

    2012-12-01

    Post-transplant diabetes mellitus represents an important complication of prolonged immunosuppressive treatment after solid organ transplantation. The immunosuppressive toxicity, responsible for a persistent impairment of glucose metabolism in pancreatic islet-transplanted patients, is mainly attributed to calcineurin inhibitors and steroids, while other immunosuppressive molecules (azathioprine and mycophenolic acid, MPA) are considered not to have a toxic effect. In the present study, in vitro effects of MPA have been investigated in mouse beta-cell lines (βTC-1 and βTC-6) and in purified human pancreatic islets. βTC-1, βTC-6, and human pancreatic islets were exposed to various concentrations of MPA for different times. Consequently, we evaluated the viability, the induction of apoptosis, the glucose-stimulated insulin secretion, and the expression of β-cell function genes (Isl1, Pax6, Glut-2, glucokinase) and apoptosis-related genes (Bax and Bcl2). βTC-1, βTC-6, and human islets treated, respectively, for 48 and 72 h with 15-30 nM MPA showed altered islet architecture, as compared with control cells. We observed for βTC-1 and βTC-6 almost 70% reduction in cell viability; three to sixfold induction of TUNEL/apoptotic-positive cells quantified by FACS analysis. A twofold increase in apoptotic cells was observed in human islets after MPA exposure associated with strong inhibition of glucose-stimulated insulin secretion. Furthermore, we showed significant down-regulation of gene expression of molecules involved in β-cell function and increase rate between Bax/Bcl2. Our data demonstrate that MPA has an in vitro diabetogenic effect interfering at multiple levels with survival and function of murine and human pancreatic β-cells. PMID:22249339

  4. The transcription factors Nkx6.1 and Nkx6.2 possess equivalent activities in promoting beta-cell fate specification in Pdx1+ pancreatic progenitor cells.

    PubMed

    Nelson, Shelley B; Schaffer, Ashleigh E; Sander, Maike

    2007-07-01

    Despite much progress in identifying transcriptional regulators that control the specification of the different pancreatic endocrine cell types, the spatiotemporal aspects of endocrine subtype specification have remained largely elusive. Here, we address the mechanism by which the transcription factors Nkx6.1 (Nkx6-1) and Nkx6.2 (Nkx6-2) orchestrate development of the endocrine alpha- and beta-cell lineages. Specifically, we assayed for the rescue of insulin-producing beta-cells in Nkx6.1 mutant mice upon restoring Nkx6 activity in select progenitor cell populations with different Nkx6-expressing transgenes. Beta-cell formation and maturation was restored when Nkx6.1 was expressed in multipotential Pdx1(+) pancreatic progenitors, whereas no rescue was observed upon expression in committed Ngn3(+) (Neurog3(+)) endocrine progenitors. Although not excluding additional roles downstream of Ngn3, this finding suggests a first requirement for Nkx6.1 in specifying beta-cell progenitors prior to Ngn3 activation. Surprisingly, although Nkx6.2 only compensates for Nkx6.1 in alpha-but not in beta-cell development in Nkx6.1(-/-) mice, a Pdx1-promoter-driven Nkx6.2 transgene had the same ability to rescue beta-cells as the Pdx1-Nkx6.1 transgene. This demonstrates that the distinct requirements for Nkx6.1 and Nkx6.2 in endocrine differentiation are a consequence of their divergent spatiotemporal expression domains rather than their biochemical activities and implies that both Nkx6.1 and Nkx6.2 possess alpha- and beta-cell-specifying activities. PMID:17537793

  5. Is Transforming Stem Cells to Pancreatic Beta Cells Still the Holy Grail for Type 2 Diabetes?

    PubMed

    Kahraman, Sevim; Okawa, Erin R; Kulkarni, Rohit N

    2016-08-01

    Diabetes is a progressive disease affecting millions of people worldwide. There are several medications and treatment options to improve the life quality of people with diabetes. One of the strategies for the treatment of diabetes could be the use of human pluripotent stem cells or induced pluripotent stem cells. The recent advances in differentiation of stem cells into insulin-secreting beta-like cells in vitro make the transplantation of the stem cell-derived beta-like cells an attractive approach for treatment of type 1 and type 2 diabetes. While stem cell-derived beta-like cells provide an unlimited cell source for beta cell replacement therapies, these cells can also be used as a platform for drug screening or modeling diseases. PMID:27313072

  6. GLUT2 (SLC2A2) is not the principal glucose transporter in human pancreatic beta cells: implications for understanding genetic association signals at this locus.

    PubMed

    McCulloch, Laura J; van de Bunt, Martijn; Braun, Matthias; Frayn, Keith N; Clark, Anne; Gloyn, Anna L

    2011-12-01

    SLC2A2 encoding glucose transporter -2 (GLUT2) acts as the primary glucose transporter and sensor in rodent pancreatic islets and is widely assumed to play a similar role in humans. In healthy adults SLC2A2 variants are associated with elevated fasting plasma glucose (fpg) concentrations but physiological characterisation does not support a defect in pancreatic beta-cell function. Interspecies differences can create barriers for the follow up of disease association signals. We hypothesised that GLUT2 is not the principal glucose transporter in human beta-cells and that SLC2A2 variants exert their effect on fpg levels through defects in other tissues. SLC2A1-4 (GLUT 1-4) mRNA expression levels were determined in human and mouse islets, beta-cells, liver, muscle and adipose tissue by qRT-PCR whilst GLUT1-3 protein levels were examined by immunohistochemistry. The presence of all three glucose transporters was demonstrated in human and mouse islets and purified beta-cells. Quantitative expression profiling demonstrated that Slc2a2 is the predominant glucose transporter (expression >10 fold higher that Slc2a1) in mouse islets whilst SLC2A1 and SLC2A3 predominate in both human islets and beta-cells (expression 2.8 and 2.7 fold higher than SLC2A2 respectively). Our data therefore suggest that GLUT2 is unlikely to be the principal glucose transporter in human beta-cells and that SLC2A2 defects in other metabolic tissues drive the observed differences in glucose levels between carriers of SLC2A2 variants. Direct extrapolation from rodent to human islet glucose transporter activity is unlikely to be appropriate. PMID:21920790

  7. Exendin-4 Protects Mitochondria from Reactive Oxygen Species Induced Apoptosis in Pancreatic Beta Cells

    PubMed Central

    Li, Zhen; Zhou, Zhiguang; Huang, Gan; Hu, Fang; Xiang, Yufei; He, Lining

    2013-01-01

    Objective Mitochondrial oxidative stress is the basis for pancreatic β-cell apoptosis and a common pathway for numerous types of damage, including glucotoxicity and lipotoxicity. We cultivated mice pancreatic β-cell tumor Min6 cell lines in vitro and observed pancreatic β-cell apoptosis and changes in mitochondrial function before and after the addition of Exendin-4. Based on these observations, we discuss the protective role of Exendin-4 against mitochondrial oxidative damage and its relationship with Ca2+-independent phospholipase A2. Methods We established a pancreatic β-cell oxidative stress damage model using Min6 cell lines cultured in vitro with tert-buty1 hydroperoxide and hydrogen peroxide. We then added Exendin-4 to observe changes in the rate of cell apoptosis (Annexin-V-FITC-PI staining flow cytometry and DNA ladder). We detected the activity of the caspase 3 and 8 apoptotic factors, measured the mitochondrial membrane potential losses and reactive oxygen species production levels, and detected the expression of cytochrome c and Smac/DLAMO in the cytosol and mitochondria, mitochondrial Ca2-independent phospholipase A2 and Ca2+-independent phospholipase A2 mRNA. Results The time-concentration curve showed that different percentages of apoptosis occurred at different time-concentrations in tert-buty1 hydroperoxide- and hydrogen peroxide-induced Min6 cells. Incubation with 100 µmol/l of Exendin-4 for 48 hours reduced the Min6 cell apoptosis rate (p<0.05). The mitochondrial membrane potential loss and total reactive oxygen species levels decreased (p<0.05), and the release of cytochrome c and Smac/DLAMO from the mitochondria was reduced. The study also showed that Ca2+-independent phospholipase A2 activity was positively related to Exendin-4 activity. Conclusion Exendin-4 reduces Min6 cell oxidative damage and the cell apoptosis rate, which may be related to Ca2-independent phospholipase A2. PMID:24204601

  8. Extracellular ATP-induced nuclear Ca{sup 2+} transient is mediated by inositol 1,4,5-trisphosphate receptors in mouse pancreatic {beta}-cells

    SciTech Connect

    Chen, Zheng; Li, Zhengzheng; Peng, Gong; Chen, Xiaoli; Yin, Wenxuan; Kotlikoff, Michael I.; Yuan, Zeng-qiang; Ji, Guangju

    2009-05-01

    Extracellular ATP (eATP) induces an intracellular Ca{sup 2+} transient by activating phospholipase C (PLC)-associated P2X4 purinergic receptors, leading to production of inositol 1,4,5-trisphosphate (IP3) and subsequent Ca{sup 2+} release from intracellular stores in mouse pancreatic {beta}-cells. Using laser scanning confocal microscopy, Ca{sup 2+} indicator fluo-4 AM, and the cell permeable nuclear indicator Hoechst 33342, we examined the properties of eATP-induced Ca{sup 2+} release in pancreatic {beta}-cell nuclei. eATP induced a higher nuclear Ca{sup 2+} transient in pancreatic {beta}-cell nuclei than in the cytosol. After pretreatment with thapsigargin (TG), an inhibitor of sarco-endoplasmic reticulum Ca{sup 2+}-ATPase (SERCA) pumps, the amplitude of eATP-induced Ca{sup 2+} transients in the nucleus was still much higher than those in the cytosol. This effect of eATP was not altered by inhibition of either the plasma membrane Ca{sup 2+}-ATPase (PMCA) or the plasma membrane Na{sup +}/Ca{sup 2+} exchanger (NCX) by LaCl{sub 3} or by replacement of Na{sup +} with N-Methyl-Glucosamine. eATP-induced nuclear Ca{sup 2+} transients were abolished by a cell-permeable IP3R inhibitor, 2-aminoethoxydiphenyl borate (2-APB), but were not blocked by the ryanodine receptor (RyR) antagonist ryanodine. Immunofluorescence studies showed that IP3Rs are expressed on the nuclear envelope of pancreatic {beta}-cells. These results indicate that eATP triggers nuclear Ca{sup 2+} transients by mobilizing a nuclear Ca{sup 2+} store via nuclear IP3Rs.

  9. Effects of low intensity laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes

    NASA Astrophysics Data System (ADS)

    Xiong, Guoxin; Xiong, Leilei; Li, Xinzhong

    2016-09-01

    To investigate the effects of low intensity semiconductor laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes, a method using a high-fat diet and low-dose intraperitoneal injections of streptozotocin established a type 2 diabetes mellitus rat model. Model rats were randomly divided into a laser acupoint irradiation group, rosiglitazone control group, and placebo group; each group had 10 rats. In addition, 10 normal male rats were selected for the normal control group. The Housanli, Neiting and Yishu acupoints of the rats in the laser acupoint irradiation group were irradiated with a 10 mW semiconductor laser; each point was irradiated for 15 min, once every 2 d over 28 d, for a total of 14 episodes of irradiation. The rosiglitazone group rats were given rosiglitazone (0.2 mg kg‑1) intragastrically; the placebo group rats were given 0.9% brine (0.2 mg kg‑1) intragastrically, once daily, for four consecutive weeks. The change of fasting blood glucose was determined before and after each treatment. The islet beta-cell apoptosis was determined. The islet beta-cell apoptosis rates of the laser acupoint irradiation group and the rosiglitazone group were significantly lower than the rate of the placebo group. Even though the rate was lower in the laser acupoint irradiation group than in the rosiglitazone group, there was no significant difference between them. It is shown that acupoint irradiation with a semiconductor laser can effectively inhibit islet beta-cell apoptosis in rats with type 2 diabetes.

  10. Hormetic and regulatory effects of lipid peroxidation mediators in pancreatic beta cells.

    PubMed

    Maulucci, Giuseppe; Daniel, Bareket; Cohen, Ofir; Avrahami, Yossef; Sasson, Shlomo

    2016-06-01

    proliferator-activated receptor δ (PPARδ) in vascular endothelial cells and insulin secreting beta cells, promote such adaptive responses to ameliorate detrimental effects of high glucose and diabetes-like conditions. In addition, due to the electrophilic nature of these reactive aldehydes they form covalent adducts with electronegative moieties in proteins, phosphatidylethanolamine and nucleotides. Normally these non-enzymatic modifications are maintained below the cytotoxic range due to efficient cellular neutralization processes of 4-hydroxyalkenals. The major neutralizing enzymes include fatty aldehyde dehydrogenase (FALDH), aldose reductase (AR) and alcohol dehydrogenase (ADH), which transform the aldehyde to the corresponding carboxylic acid or alcohols, respectively, or by biding to the thiol group in glutathione (GSH) by the action of glutathione-S-transferase (GST). This review describes the hormetic and cytotoxic roles of oxygen free radicals and 4-hydroxyalkenals in beta cells exposed to nutritional challenges and the cellular mechanisms they employ to maintain their level at functional range below the cytotoxic threshold. PMID:27012748

  11. Characterization of Phospholipids in Insulin Secretory Granules and Mitochondria in Pancreatic Beta Cells and Their Changes with Glucose Stimulation*

    PubMed Central

    MacDonald, Michael J.; Ade, Lacmbouh; Ntambi, James M.; Ansari, Israr-Ul H.; Stoker, Scott W.

    2015-01-01

    The lipid composition of insulin secretory granules (ISG) has never previously been thoroughly characterized. We characterized the phospholipid composition of ISG and mitochondria in pancreatic beta cells without and with glucose stimulation. The phospholipid/protein ratios of most phospholipids containing unsaturated fatty acids were higher in ISG than in whole cells and in mitochondria. The concentrations of negatively charged phospholipids, phosphatidylserine, and phosphatidylinositol in ISG were 5-fold higher than in the whole cell. In ISG phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin, fatty acids 12:0 and 14:0 were high, as were phosphatidylserine and phosphatidylinositol containing 18-carbon unsaturated FA. With glucose stimulation, the concentration of many ISG phosphatidylserines and phosphatidylinositols increased; unsaturated fatty acids in phosphatidylserine increased; and most phosphatidylethanolamines, phosphatidylcholines, sphingomyelins, and lysophosphatidylcholines were unchanged. Unsaturation and shorter fatty acid length in phospholipids facilitate curvature and fluidity of membranes, which favors fusion of membranes. Recent evidence suggests that negatively charged phospholipids, such as phosphatidylserine, act as coupling factors enhancing the interaction of positively charged regions in SNARE proteins in synaptic or secretory vesicle membrane lipid bilayers with positively charged regions in SNARE proteins in the plasma membrane lipid bilayer to facilitate docking of vesicles to the plasma membrane during exocytosis. The results indicate that ISG phospholipids are in a dynamic state and are consistent with the idea that changes in ISG phospholipids facilitate fusion of ISG with the plasma membrane-enhancing glucose-stimulated insulin exocytosis. PMID:25762724

  12. Glucocorticoid overexposure in neonatal life alters pancreatic beta-cell function in newborn foals.

    PubMed

    Jellyman, J K; Allen, V L; Holdstock, N B; Fowden, A L

    2013-01-01

    Studies in humans and animals have linked abnormal programming of adult tissue function to excess glucocorticoids during perinatal development. The current study investigated the hypothesis that physiological variations in glucocorticoid concentrations during early neonatal life of the foal alter the secretory responses of the pancreatic β cells 2 and 12 wk after treatment. Spontaneously delivered foals received either saline or long-acting ACTH for 5 d from 1 d after birth to maintain an endogenous rise in cortisol concentrations. Starting at d 10, pancreatic β cell function was studied using an intravenous (i.v.) glucose tolerance test, an i.v. arginine challenge, and an i.v. tolbutamide challenge. The maximum increment in plasma insulin achieved in response to exogenous glucose was less in ACTH-treated foals at both 2 and 12 wk of age (P<0.05). By 12 wk of age, developmental changes also occurred in the magnitude and biphasic pattern of glucose-stimulated insulin release. The area under the insulin curve during the early phase of insulin secretion (0 to 30 min) was not different between the 2- and 12-wk-old animals but was significantly greater during the later phase (30 to 120 min) at 12 wk than at 2 wk (P<0.05). Arginine infusion induced a brief 5 to 15 min increase in plasma concentrations of insulin that was not different in saline- and ACTH-treated foals. The β-cell response to tolbutamide infusion was rapid and monophasic, and there was no difference (P>0.05) in the area under the insulin curve with treatment at 2 or at 12 wk. However, after tolbutamide, plasma insulin concentrations remained increased for a longer period in the ACTH-treated than in the saline-treated foals at 12 wk of age (P<0.05). Hence, this is the first study to show altered pancreatic β-cell function after ACTH-induced glucocorticoid overexposure during early postnatal life in foals. PMID:23100584

  13. Protein Fractions from Korean Mistletoe (Viscum Album coloratum) Extract Induce Insulin Secretion from Pancreatic Beta Cells

    PubMed Central

    Kim, Jong-Bae

    2014-01-01

    Mistletoe (Viscum Album coloratum) has been known as a medicinal plant in European and Asian countries. Recent data show that biological activity of mistletoe alleviates hypertension, heart disease, renal failure, and cancer development. In this study, we report the antidiabetic effect of Korean mistletoe extract (KME). KME treatments enhanced the insulin secretion from the pancreatic β-cell without any effects of cytotoxicity. PDX-1 and beta2/neuroD known as transcription factors that regulate the expression of insulin gene were upregulated by treatment of the KME protein fractions isolated by ion-exchange chromatography after ammonium sulfate precipitation. Furthermore, these KME protein fractions significantly lowered the blood glucose level and the volume of drinking water in alloxan induced hyperglycemic mice. Taken together with the findings, it provides new insight that KME might be served as a useful source for the development of medicinal reagent to reduce blood glucose level of type I diabetic patients. PMID:24959189

  14. Guiding pancreatic beta cells to target electrodes in a whole-cell biosensor for diabetes.

    PubMed

    Pedraza, Eileen; Karajić, Aleksandar; Raoux, Matthieu; Perrier, Romain; Pirog, Antoine; Lebreton, Fanny; Arbault, Stéphane; Gaitan, Julien; Renaud, Sylvie; Kuhn, Alexander; Lang, Jochen

    2015-10-01

    We are developing a cell-based bioelectronic glucose sensor that exploits the multi-parametric sensing ability of pancreatic islet cells for the treatment of diabetes. These cells sense changes in the concentration of glucose and physiological hormones and immediately react by generating electrical signals. In our sensor, signals from multiple cells are recorded as field potentials by a micro-electrode array (MEA). Thus, cell response to various factors can be assessed rapidly and with high throughput. However, signal quality and consequently overall sensor performance rely critically on close cell-electrode proximity. Therefore, we present here a non-invasive method of further exploiting the electrical properties of these cells to guide them towards multiple micro-electrodes via electrophoresis. Parameters were optimized by measuring the cell's zeta potential and modeling the electric field distribution. Clonal and primary mouse or human β-cells migrated directly to target electrodes during the application of a 1 V potential between MEA electrodes for 3 minutes. The morphology, insulin secretion, and electrophysiological characteristics were not altered compared to controls. Thus, cell manipulation on standard MEAs was achieved without introducing any external components and while maintaining the performance of the biosensor. Since the analysis of the cells' electrical activity was performed in real time via on-chip recording and processing, this work demonstrates that our biosensor is operational from the first step of electrically guiding cells to the final step of automatic recognition. Our favorable results with pancreatic islets, which are highly sensitive and fragile cells, are encouraging for the extension of this technique to other cell types and microarray devices. PMID:26282013

  15. Fluorescence microscopy studies with a fluorescent glibenclamide derivative, a high-affinity blocker of pancreatic beta-cell ATP-sensitive K+ currents.

    PubMed

    Zünkler, Bernd J; Wos-Maganga, Maria; Panten, Uwe

    2004-04-15

    Hypoglycemic sulfonylureas (e.g. tolbutamide, glibenclamide) exert their stimulatory effects on pancreatic beta-cells by closure of ATP-sensitive K(+) (K(ATP)) channels. Pancreatic K(ATP) channels are composed of two subunits, a pore-forming inwardly rectifying K(+) channel (Kir6.2) subunit and a regulatory subunit (the sulfonylurea receptor of subtype 1 (SUR1)) in a (SUR1/Kir6.2)(4) stoichiometry. The aim of the present study was to characterize the interaction of green-fluorescent 3-[3-(4,4 difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-S-indacen-3-yl)propanamido] glibenclamide (Bodipy-glibenclamide) with pancreatic beta-cell K(ATP) channels using patch-clamp and fluorescence microscopy techniques. Bodipy-glibenclamide inhibited K(ATP) currents from the clonal insulinoma cell line RINm5F half-maximally at a concentration of 0.6nM. Using laser-scanning confocal microscopy Bodipy-glibenclamide was shown to induce a diffuse fluorescence across the RINm5F cell, but only about 17% of total Bodipy-glibenclamide-induced fluorescence intensity in RINm5F cells was due to specific binding to SUR1. Using fluorescence correlation spectroscopy, it could be demonstrated that the fluorescence label contributes to the protein binding and, therefore, possibly also to the non-specific binding of Bodipy-glibenclamide observed in RINm5F cells. Specific binding of Bodipy-glibenclamide to SUR1 in RINm5F cells might be localized to different intracellular structures (nuclear envelope, endoplasmic reticulum, Golgi compartment, insulin secretory granules) as well as to the plasma membrane. In conclusion, Bodipy-glibenclamide is a high-affinity blocker of pancreatic beta-cell K(ATP) currents and can be used for visualizing SUR1 in intact pancreatic beta-cells, although non-specific binding must be taken into account in confocal microscopy experiments on intact beta-cells. PMID:15041461

  16. Immune Intervention and Preservation of Pancreatic Beta Cell Function in Type 1 Diabetes.

    PubMed

    Simmons, Kimber M; Gottlieb, Peter A; Michels, Aaron W

    2016-10-01

    Type 1 diabetes (T1D) results from the immune-mediated destruction of insulin-producing β cells located within the pancreatic islets of Langerhans. The autoimmune process leads to a deficiency in insulin production and resultant hyperglycemia requiring lifelong treatment with insulin administration. T1D continues to dramatically increase in incidence, especially in young children. Substantial knowledge surrounding human disease pathogenesis exists, such that T1D is now predictable with the measurement of antibodies in the peripheral blood directed against insulin and other β cell proteins. With the ability to predict, it naturally follows that T1D should be preventable. As such, over the last two decades, numerous well-controlled clinical trials have been completed attempting to prevent diabetes onset or maintain residual β cell function after clinical onset, all providing relatively disappointing results. Here, we review the T1D prevention efforts, the current landscape of clinical therapies, and end with a discussion regarding the future outlook for preventing T1D. PMID:27558810

  17. Cdk5 inhibitory peptide (CIP) inhibits Cdk5/p25 activity induced by high glucose in pancreatic beta cells and recovers insulin secretion from p25 damage.

    PubMed

    Zheng, Ya-Li; Li, Congyu; Hu, Ya-Fang; Cao, Li; Wang, Hui; Li, Bo; Lu, Xiao-Hua; Bao, Li; Luo, Hong-Yan; Shukla, Varsha; Amin, Niranjana D; Pant, Harish C

    2013-01-01

    Cdk5/p25 hyperactivity has been demonstrated to lead to neuron apoptosis and degenerations. Chronic exposure to high glucose (HG) results in hyperactivity of Cdk5 and reduced insulin secretion. Here, we set out to determine whether abnormal upregulation of Cdk5/p25 activity may be induced in a pancreatic beta cell line, Min6 cells. We first confirmed that p25 were induced in overexpressed p35 cells treated with HG and increased time course dependence. Next, we showed that no p25 was detected under short time HG stimulation (4-12 hrs), however was detectable in the long exposure in HG cells (24 hrs and 48 hrs). Cdk5 activity in the above cells was much higher than low glucose treated cells and resulted in more than 50% inhibition of insulin secretion. We confirmed these results by overexpression of p25 in Min6 cells. As in cortical neurons, CIP, a small peptide, inhibited Cdk5/p25 activity and restored insulin secretion. The same results were detected in co-infection of dominant negative Cdk5 (DNCdk5) with p25. CIP also reduced beta cells apoptosis induced by Cdk5/p25. These studies indicate that Cdk5/p25 hyperactivation deregulates insulin secretion and induces cell death in pancreatic beta cells and suggests that CIP may serve as a therapeutic agent for type 2 diabetes. PMID:24039692

  18. Activation of PPAR{delta} up-regulates fatty acid oxidation and energy uncoupling genes of mitochondria and reduces palmitate-induced apoptosis in pancreatic {beta}-cells

    SciTech Connect

    Wan, Jun; Jiang, Li; Lue, Qingguo; Ke, Linqiu; Li, Xiaoyu; Tong, Nanwei

    2010-01-15

    Recent evidence indicates that decreased oxidative capacity, lipotoxicity, and mitochondrial aberrations contribute to the development of insulin resistance and type 2 diabetes. The goal of this study was to investigate the effects of peroxisome proliferator-activated receptor {delta} (PPAR{delta}) activation on lipid oxidation, mitochondrial function, and insulin secretion in pancreatic {beta}-cells. After HIT-T15 cells (a {beta}-cell line) were exposed to high concentrations of palmitate and GW501516 (GW; a selective agonist of PPAR{delta}), we found that administration of GW increased the expression of PPAR{delta} mRNA. GW-induced activation of PPAR{delta} up-regulated carnitine palmitoyltransferase 1 (CPT1), long-chain acyl-CoA dehydrogenase (LCAD), pyruvate dehydrogenase kinase 4 (PDK4), and uncoupling protein 2 (UCP2); alleviated mitochondrial swelling; attenuated apoptosis; and reduced basal insulin secretion induced by increased palmitate in HIT cells. These results suggest that activation of PPAR{delta} plays an important role in protecting pancreatic {beta}-cells against aberrations caused by lipotoxicity in metabolic syndrome and diabetes.

  19. Direct visualisation of peptide hormones in cultured pancreatic islet alpha- and beta-cells by intact-cell mass spectrometry.

    PubMed

    Buchanan, Christina M; Malik, Arpita S; Cooper, Garth J S

    2007-01-01

    The application of intact-cell mass spectrometry (ICM) by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry to achieve direct protein-profiling of bacterial species is now well established. However, this methodology has not to our knowledge been applied to the analysis of mammalian cells in routine culture. Here, we describe a novel application of ICM by which we have identified proteins in intact cells from two lines representative of pancreatic islet alpha- and beta-cells. Adherent alphaTC1 clone 9 and betaTC6 F7 cells were harvested into phosphate-buffered saline (PBS) using enzyme-free dissociation buffer before 1 microL of cell suspension was spotted onto MALDI plates. Cells were overlaid with sinapinic acid then washed with pure water before application of a final coat of sinapinic acid. Data in the 2000-20,000 m/z range were acquired in linear mode on a Voyager DE-Pro mass spectrometer. The proteins which ionised were composed in large part of peptide hormones (e.g. insulin and glucagon) known to be packaged into the secretory granules of the beta- and alpha-cells respectively. However, in addition to visualising the peptides expected to be associated with these cells, a mass consistent with oxyntomodulin was identified in the cultured alpha-cells, a finding not previously reported to our knowledge. In summary, this paper describes, for the first time, a rapid and direct method useful for identifying secretory products in intact endocrine cells. PMID:17918213

  20. Insulin exerts metabolic and growth-promoting effects by a direct action on the liver in vivo: clarification of the functional significance of the portal vascular link between the beta cells of the pancreatic islets and the liver.

    PubMed Central

    Griffen, S C; Russell, S M; Katz, L S; Nicoll, C S

    1987-01-01

    The functional significance of the portal vascular link between the beta cells of the pancreatic islets and the liver has not been established. Previous studies indicated that insulin does not acutely regulate glucose metabolism by a direct hepatic effect. More recent observations suggest that the role of insulin in regulating body growth may be mediated, at least in part, by the liver. Our experiments were designed to test whether insulin can promote body growth and regulate glucose metabolism by a direct hepatic action in vivo. Rats were made diabetic by injections of streptozotocin, and insulin or solvent was infused into the jugular vein (JV) or the hepatic portal vein (HPV) for 14 days using catheters that were attached to osmotic minipumps. Infusion of a low dose of insulin (2 units per kg per day) into the JV had no effects on the hyperglycemia, body weight gain, tail growth, tibial epiphysial cartilage plate thickness, or serum levels of somatomedin C in the diabetic rats. However, the same dose given into the HPV caused a 30% reduction of blood glucose and stimulated a significant degree of growth, as determined by all indices. Infusion of a higher dose of insulin (5 units per kg per day) into either vein caused full restoration of body weight gain and tail growth and it restored the glycemic status almost to normal. However, it did not increase the tibial epiphysial plate width or serum somatomedin C levels above those of the rats given the low dose of the hormone into the HPV. These results indicate that insulin can act directly on the liver to promote body growth and to regulate glucose metabolism. The significance of direct delivery of insulin from the pancreatic beta cells to the liver may be as much for growth control as for glucose homeostasis. Images PMID:3313390

  1. Islet Stellate Cells Isolated from Fibrotic Islet of Goto-Kakizaki Rats Affect Biological Behavior of Beta-Cell.

    PubMed

    Li, Feng-Fei; Chen, Bi-Jun; Li, Wei; Li, Ling; Zha, Min; Zhou, S; Bachem, M G; Sun, Zi-Lin

    2016-01-01

    We previously isolated islet stellate cells (ISCs) from healthy Wistar rat islets. In the present study, we isolated "already primed by diabetic environment" ISCs from islets of Goto-Kakizaki rats, determined the gene profile of these cells, and assessed the effects of these ISCs on beta-cell function and survival. We detected gene expression of ISCs by digital gene expression. INS-1 cell proliferation, apoptosis, and insulin production were measured after being treated with ISCs supernatant (SN). We observed the similar expression pattern of ISCs and PSCs, but 1067 differentially expressed genes. Insulin production in INS-1 cells cultured with ISC-SN was significantly reduced. The 5-ethynyl-2'-deoxyuridine-positive INS-1 cells treated with ISC-SN were decreased. Propidium iodide- (PI-) positive INS-1 cells were 2.6-fold higher than those in control groups. Caspase-3 activity was increased. In conclusion, ISCs presented in fibrotic islet of GK rats might be special PSCs, which impaired beta-cell function and proliferation and increased beta-cell apoptosis. PMID:26697502

  2. Glucagon-like peptide-1 counteracts the detrimental effects of Advanced Glycation End-Products in the pancreatic beta cell line HIT-T 15

    SciTech Connect

    Puddu, A.; Storace, D.; Durante, A.; Odetti, P.; Viviani, G.L.

    2010-07-30

    Research highlights: {yields} GLP-1 prevents AGEs-induced cell death. {yields} GLP-1 prevents AGEs-induced oxidative stress. {yields} GLP-1 ameliorated AGEs-induced cell dysfunction. {yields} GLP-1 attenuates AGEs-induced RAGE increment. {yields} GLP-1 counteracts AGEs-induced pancreatic cell death and dysfunction. -- Abstract: Advanced Glycation End-Products (AGEs), a group of compounds resulting from the non-enzymatic reaction of reducing sugars with the free amino group of proteins, are implicated in diabetic complications. We previously demonstrated that exposure of the pancreatic islet cell line HIT-T 15 to high concentrations of AGEs significantly decreases cell proliferation and insulin secretion, and affects transcription factors regulating insulin gene transcription. The glucagon-like peptide-1 (GLP-1) is an incretin hormone that increases proinsulin biosynthesis, stimulates insulin secretion, and improves pancreatic beta-cell viability. The aim of this work was to investigate the effects of GLP-1 on the function and viability of HIT-T 15 cells cultured with AGEs. HIT-T 15 cells were cultured for 5 days in presence of AGEs alone, or supplemented with 10 nmol/l GLP-1. Cell viability, insulin secretion, redox balance, and expression of the AGEs receptor (RAGE) were then determined. The results showed that GLP-1 protected beta cell against AGEs-induced cell death preventing both apoptosis and necrosis. Moreover, addition of GLP-1 to the AGEs culture medium restored the redox balance, improved the responsiveness to glucose, and attenuated AGEs-induced RAGE expression. These findings provide evidence that GLP-1 protects beta cells from the dangerous effects of AGEs.

  3. To Be(ta Cell) or Not to Be(ta cell): New Mouse Models for Studying Gene Function in the Pancreatic β-Cell.

    PubMed

    Estall, Jennifer L; Screaton, Robert A

    2015-07-01

    A challenge in the pancreatic β-cell field has been to identify a promoter fragment that is active only in the β-cell compartment and inactive in other regions, such as the hypothalamic region of the brain. The presence of Cre recombinase alone in some models may also affect glucoregulation, confounding interpretation of gene function in the β-cell. A paper presented within describes the development and characterization of 2 new transgenic mice expressing Cre recombinase under the mouse insulin1 promoter that are useful for β-cell-specific gene ablation: the first is constitutive and coexpresses DsRed (Ins1-Cre-DsRed); the second allows β-cell-specific expression of the reverse tetracycline-controlled transactivator, which can be used for drug-dependent expression of a target gene of interest for overexpression studies. These novel models show robust specificity and efficiency and will be valuable tools for functional studies of gene action in β-cells, potentially alleviating current issues associated with previously available mouse lines. PMID:26091426

  4. O-Linked β-N-acetylglucosamine (O-GlcNAc) Acts as a Glucose Sensor to Epigenetically Regulate the Insulin Gene in Pancreatic Beta Cells.

    PubMed

    Durning, Sean P; Flanagan-Steet, Heather; Prasad, Nripesh; Wells, Lance

    2016-01-29

    The post-translational protein modification O-linked β-N-acetylglucosamine (O-GlcNAc) is a proposed nutrient sensor that has been shown to regulate multiple biological pathways. This dynamic and inducible enzymatic modification to intracellular proteins utilizes the end product of the nutrient sensing hexosamine biosynthetic pathway, UDP-GlcNAc, as its substrate donor. Type II diabetic patients have elevated O-GlcNAc-modified proteins within pancreatic beta cells due to chronic hyperglycemia-induced glucose overload, but a molecular role for O-GlcNAc within beta cells remains unclear. Using directed pharmacological approaches in the mouse insulinoma-6 (Min6) cell line, we demonstrate that elevating nuclear O-GlcNAc increases intracellular insulin levels and preserves glucose-stimulated insulin secretion during chronic hyperglycemia. The molecular mechanism for these observed changes appears to be, at least in part, due to elevated O-GlcNAc-dependent increases in Ins1 and Ins2 mRNA levels via elevations in histone H3 transcriptional activation marks. Furthermore, RNA deep sequencing reveals that this mechanism of altered gene transcription is restricted and that the majority of genes regulated by elevated O-GlcNAc levels are similarly regulated by a shift from euglycemic to hyperglycemic conditions. These findings implicate the O-GlcNAc modification as a potential mechanism for hyperglycemic-regulated gene expression in the beta cell. PMID:26598517

  5. Increased secretion of insulin and proliferation of islet {beta}-cells in rats with mesenteric lymph duct ligation

    SciTech Connect

    Nagino, Ko; Yokozawa, Junji; Sasaki, Yu; Matsuda, Akiko; Takeda, Hiroaki; Kawata, Sumio

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Insulin secretion was increased during the OGTT or IVGTT in mesenteric lymph duct-ligated rats. Black-Right-Pointing-Pointer Proliferation of islet {beta}-cells was upregulated in lymph duct-ligated rats. Black-Right-Pointing-Pointer Mesenteric lymph duct flow has a role in glucose metabolism. -- Abstract: Background and aims: It has been suggested that intestinal lymph flow plays an important role in insulin secretion and glucose metabolism after meals. In this study, we investigated the influence of ligation of the mesenteric lymph duct on glucose metabolism and islet {beta}-cells in rats. Methods: Male Sprague-Dawley rats (10 weeks old) were divided into two groups: one underwent ligation of the mesenteric lymph duct above the cistern (ligation group), and the other underwent a sham operation (sham group). After 1 and 2 weeks, fasting plasma concentrations of glucose, insulin, triglyceride, glucose-dependent insulinotropic polypeptide (GIP), and the active form of glucagon-like peptide-1 (GLP-1) were measured. At 2 weeks after the operation, the oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT) were performed. After the rats had been sacrificed, the insulin content of the pancreas was measured and the proliferation of {beta}-cells was assessed immunohistochemically using antibodies against insulin and Ki-67. Results: During the OGTT, the ligation group showed a significant decrease in the plasma glucose concentration at 120 min (p < 0.05) and a significant increase in the plasma insulin concentration by more than 2-fold at 15 min (p < 0.01). On the other hand, the plasma GIP concentration was significantly decreased at 60 min (p < 0.01) in the ligated group, while the active form of GLP-1 showed a significantly higher level at 90 min (1.7-fold; p < 0.05) and 120 min (2.5-fold; p < 0.01). During the IVGTT, the plasma insulin concentration in the ligation group was significantly higher at 2

  6. Delayed-rectifier (KV2.1) regulation of pancreatic beta-cell calcium responses to glucose: inhibitor specificity and modeling.

    PubMed

    Tamarina, Natalia A; Kuznetsov, Andrey; Fridlyand, Leonid E; Philipson, Louis H

    2005-10-01

    The delayed-rectifier (voltage-activated) K(+) conductance (K(V)) in pancreatic islet beta-cells has been proposed to regulate plasma membrane repolarization during responses to glucose, thereby determining bursting and Ca(2+) oscillations. Here, we verified the expression of K(V)2.1 channel protein in mouse and human islets of Langerhans. We then probed the function of K(V)2.1 channels in islet glucose responses by comparing the effect of hanatoxin (HaTx), a specific blocker of K(V)2.1 channels, with a nonspecific K(+) channel blocker, tetraethylammonium (TEA). Application of HaTx (1 microM) blocked delayed-rectifier currents in mouse beta-cells, resulting in a 40-mV rightward shift in threshold of activation of the voltage-dependent outward current. In the presence of HaTx, there was negligible voltage-activated outward current below 0 mV, suggesting that K(V)2.1 channels form the predominant part of this current in the physiologically relevant range. We then employed HaTx to study the role of K(V)2.1 in the beta-cell Ca(2+) responses to elevated glucose in comparison with TEA. Only HaTx was able to induce slow intracellular Ca(2+) concentration ([Ca(2+)](i)) oscillations in cells stimulated with 20 mM glucose, whereas TEA induced an immediate rise in [Ca(2+)](i) followed by rapid oscillations. In human islets, HaTx acted in a similar fashion. The data were analyzed using a detailed mathematical model of ionic flux and Ca(2+) regulation in beta-cells. The results can be explained by a specific HaTx effect on the K(V) current, whereas TEA affects multiple K(+) conductances. The results underscore the importance of K(V)2.1 channel in repolarization of the pancreatic beta-cell plasma membrane and its role in regulating insulin secretion. PMID:16014354

  7. Obestatin Accelerates the Recovery in the Course of Ischemia/Reperfusion-Induced Acute Pancreatitis in Rats

    PubMed Central

    Bukowczan, Jakub; Warzecha, Zygmunt; Ceranowicz, Piotr; Kuśnierz-Cabala, Beata; Tomaszewska, Romana

    2015-01-01

    Objective Several previous studies have shown that obestatin exhibits protective and regenerative effects in some organs including the stomach, kidney, and the brain. In the pancreas, pretreatment with obestatin inhibits the development of cerulein-induced acute pancreatitis, and promotes survival of pancreatic beta cells and human islets. However, no studies investigated the effect of obestatin administration following the onset of experimental acute pancreatitis. Aim The aim of this study was to evaluate the impact of obestatin therapy in the course of ischemia/reperfusion-induced pancreatitis. Moreover, we tested the influence of ischemia/reperfusion-induced acute pancreatitis and administration of obestatin on daily food intake and pancreatic exocrine secretion. Methods Acute pancreatitis was induced by pancreatic ischemia followed by reperfusion of the pancreas. Obestatin (8nmol/kg/dose) was administered intraperitoneally twice a day, starting 24 hours after the beginning of reperfusion. The effect of obestatin in the course of necrotizing pancreatitis was assessed between 2 and 14 days, and included histological, functional, and biochemical analyses. Secretory studies were performed on the third day after sham-operation or induction of acute pancreatitis in conscious rats equipped with chronic pancreatic fistula. Results Treatment with obestatin ameliorated morphological signs of pancreatic damage including edema, vacuolization of acinar cells, hemorrhages, acinar necrosis, and leukocyte infiltration of the gland, and led to earlier pancreatic regeneration. Structural changes were accompanied by biochemical and functional improvements manifested by accelerated normalization of interleukin-1β level and activity of myeloperoxidase and lipase, attenuation of the decrease in pancreatic DNA synthesis, and by an improvement of pancreatic blood flow. Induction of acute pancreatitis by pancreatic ischemia followed by reperfusion significantly decreased daily food

  8. Differentiation and transplantation of functional pancreatic beta cells generated from induced pluripotent stem cells derived from a type 1 diabetes mouse model.

    PubMed

    Jeon, Kilsoo; Lim, Hyejin; Kim, Jung-Hyun; Thuan, Nguyen Van; Park, Seung Hwa; Lim, Yu-Mi; Choi, Hye-Yeon; Lee, Eung-Ryoung; Kim, Jin-Hoi; Lee, Myung-Shik; Cho, Ssang-Goo

    2012-09-20

    The nonobese diabetic (NOD) mouse is a classical animal model for autoimmune type 1 diabetes (T1D), closely mimicking features of human T1D. Thus, the NOD mouse presents an opportunity to test the effectiveness of induced pluripotent stem cells (iPSCs) as a therapeutic modality for T1D. Here, we demonstrate a proof of concept for cellular therapy using NOD mouse-derived iPSCs (NOD-iPSCs). We generated iPSCs from NOD mouse embryonic fibroblasts or NOD mouse pancreas-derived epithelial cells (NPEs), and applied directed differentiation protocols to differentiate the NOD-iPSCs toward functional pancreatic beta cells. Finally, we investigated whether the NPE-iPSC-derived insulin-producing cells could normalize hyperglycemia in transplanted diabetic mice. The NOD-iPSCs showed typical embryonic stem cell-like characteristics such as expression of markers for pluripotency, in vitro differentiation, teratoma formation, and generation of chimeric mice. We developed a method for stepwise differentiation of NOD-iPSCs into insulin-producing cells, and found that NPE-iPSCs differentiate more readily into insulin-producing cells. The differentiated NPE-iPSCs expressed diverse pancreatic beta cell markers and released insulin in response to glucose and KCl stimulation. Transplantation of the differentiated NPE-iPSCs into diabetic mice resulted in kidney engraftment. The engrafted cells responded to glucose by secreting insulin, thereby normalizing blood glucose levels. We propose that NOD-iPSCs will provide a useful tool for investigating genetic susceptibility to autoimmune diseases and generating a cellular interaction model of T1D, paving the way for the potential application of patient-derived iPSCs in autologous beta cell transplantation for treating diabetes. PMID:22512788

  9. The Rab-binding protein Noc2 is associated with insulin-containing secretory granules and is essential for pancreatic beta-cell exocytosis.

    PubMed

    Cheviet, Séverine; Coppola, Thierry; Haynes, Lee P; Burgoyne, Robert D; Regazzi, Romano

    2004-01-01

    The small GTPases Rab3 and Rab27 are associated with secretory granules of pancreatic beta-cells and regulate insulin exocytosis. In this study, we investigated the role of Noc2, a potential partner of these two GTPases, in insulin secretion. In the beta-cell line INS-1E wild-type Noc2, Noc265E, and Noc258A, a mutant capable of interacting with Rab27 but not Rab3, colocalized with insulin-containing vesicles. In contrast, two mutants (Noc2138S,141S and Noc2154A,155A,156A) that bind neither Rab3 nor Rab27 did not associate with secretory granules and were uniformly distributed throughout the cell cytoplasm. Overexpression of wild-type Noc2, Noc265E, or Noc258A inhibited hormone secretion elicited by insulin secretagogues. In contrast, overexpression of the mutants not targeted to secretory granules was without effect. Silencing of the Noc2 gene by RNA interference led to a strong impairment in the capacity of INS-1E cells to respond to insulin secretagogues, indicating that appropriate levels of Noc2 are essential for pancreatic beta-cell exocytosis. The defect was already detectable in the early secretory phase (0-10 min) but was particularly evident during the sustained release phase (10-45 min). Protein-protein binding studies revealed that Noc2 is a potential partner of Munc13, a component of the machinery that controls vesicle priming and insulin exocytosis. These data suggest that Noc2 is involved in the recruitment of secretory granules at the plasma membrane possibly via the interaction with Munc13. PMID:14593078

  10. PED/PEA-15 Inhibits Hydrogen Peroxide-Induced Apoptosis in Ins-1E Pancreatic Beta-Cells via PLD-1

    PubMed Central

    Raciti, Gregory Alexander; Zatterale, Federica; Nigro, Cecilia; Mirra, Paola; Falco, Roberta; Ulianich, Luca; Di Jeso, Bruno; Formisano, Pietro; Miele, Claudia; Beguinot, Francesco

    2014-01-01

    The small scaffold protein PED/PEA-15 is involved in several different physiologic and pathologic processes, such as cell proliferation and survival, diabetes and cancer. PED/PEA-15 exerts an anti-apoptotic function due to its ability to interfere with both extrinsic and intrinsic apoptotic pathways in different cell types. Recent evidence shows that mice overexpressing PED/PEA-15 present larger pancreatic islets and increased beta-cells mass. In the present work we investigated PED/PEA-15 role in hydrogen peroxide-induced apoptosis in Ins-1E beta-cells. In pancreatic islets isolated from TgPED/PEA-15 mice hydrogen peroxide-induced DNA fragmentation was lower compared to WT islets. TUNEL analysis showed that PED/PEA-15 overexpression increases the viability of Ins-1E beta-cells and enhances their resistance to apoptosis induced by hydrogen peroxide exposure. The activity of caspase-3 and the cleavage of PARP-1 were markedly reduced in Ins-1E cells overexpressing PED/PEA-15 (Ins-1EPED/PEA-15). In parallel, we observed a decrease of the mRNA levels of pro-apoptotic genes Bcl-xS and Bad. In contrast, the expression of the anti-apoptotic gene Bcl-xL was enhanced. Accordingly, DNA fragmentation was higher in control cells compared to Ins-1EPED/PEA-15 cells. Interestingly, the preincubation with propranolol, an inhibitor of the pathway of PLD-1, a known interactor of PED/PEA-15, responsible for its deleterious effects on glucose tolerance, abolishes the antiapoptotic effects of PED/PEA-15 overexpression in Ins-1E beta-cells. The same results have been obtained by inhibiting PED/PEA-15 interaction with PLD-1 in Ins-1EPED/PEA-15. These results show that PED/PEA-15 overexpression is sufficient to block hydrogen peroxide-induced apoptosis in Ins-1E cells through a PLD-1 mediated mechanism. PMID:25489735

  11. The transcription factor C/EBP delta has anti-apoptotic and anti-inflammatory roles in pancreatic beta cells.

    PubMed

    Moore, Fabrice; Santin, Izortze; Nogueira, Tatiane C; Gurzov, Esteban N; Marselli, Lorella; Marchetti, Piero; Eizirik, Decio L

    2012-01-01

    In the course of Type 1 diabetes pro-inflammatory cytokines (e.g., IL-1β, IFN-γ and TNF-α) produced by islet-infiltrating immune cells modify expression of key gene networks in β-cells, leading to local inflammation and β-cell apoptosis. Most known cytokine-induced transcription factors have pro-apoptotic effects, and little is known regarding "protective" transcription factors. To this end, we presently evaluated the role of the transcription factor CCAAT/enhancer binding protein delta (C/EBPδ) on β-cell apoptosis and production of inflammatory mediators in the rat insulinoma INS-1E cells, in purified primary rat β-cells and in human islets. C/EBPδ is expressed and up-regulated in response to the cytokines IL-1β and IFN-γ in rat β-cells and human islets. Small interfering RNA-mediated C/EBPδ silencing exacerbated IL-1β+IFN-γ-induced caspase 9 and 3 cleavage and apoptosis in these cells. C/EBPδ deficiency increased the up-regulation of the transcription factor CHOP in response to cytokines, enhancing expression of the pro-apoptotic Bcl-2 family member BIM. Interfering with C/EBPδ and CHOP or C/EBPδ and BIM in double knockdown approaches abrogated the exacerbating effects of C/EBPδ deficiency on cytokine-induced β-cell apoptosis, while C/EBPδ overexpression inhibited BIM expression and partially protected β-cells against IL-1β+IFN-γ-induced apoptosis. Furthermore, C/EBPδ silencing boosted cytokine-induced production of the chemokines CXCL1, 9, 10 and CCL20 in β-cells by hampering IRF-1 up-regulation and increasing STAT1 activation in response to cytokines. These observations identify a novel function of C/EBPδ as a modulatory transcription factor that inhibits the pro-apoptotic and pro-inflammatory gene networks activated by cytokines in pancreatic β-cells. PMID:22347430

  12. The relationship between node degree and dissipation rate in networks of diffusively coupled oscillators and its significance for pancreatic beta cells

    NASA Astrophysics Data System (ADS)

    Gosak, Marko; Stožer, Andraž; Markovič, Rene; Dolenšek, Jurij; Marhl, Marko; Slak Rupnik, Marjan; Perc, Matjaž

    2015-07-01

    Self-sustained oscillatory dynamics is a motion along a stable limit cycle in the phase space, and it arises in a wide variety of mechanical, electrical, and biological systems. Typically, oscillations are due to a balance between energy dissipation and generation. Their stability depends on the properties of the attractor, in particular, its dissipative characteristics, which in turn determine the flexibility of a given dynamical system. In a network of oscillators, the coupling additionally contributes to the dissipation, and hence affects the robustness of the oscillatory solution. Here, we therefore investigate how a heterogeneous network structure affects the dissipation rate of individual oscillators. First, we show that in a network of diffusively coupled oscillators, the dissipation is a linearly decreasing function of the node degree, and we demonstrate this numerically by calculating the average divergence of coupled Hopf oscillators. Subsequently, we use recordings of intracellular calcium dynamics in pancreatic beta cells in mouse acute tissue slices and the corresponding functional connectivity networks for an experimental verification of the presented theory. We use methods of nonlinear time series analysis to reconstruct the phase space and calculate the sum of Lyapunov exponents. Our analysis reveals a clear tendency of cells with a higher degree, that is, more interconnected cells, having more negative values of divergence, thus confirming our theoretical predictions. We discuss these findings in the context of energetic aspects of signaling in beta cells and potential risks for pathological changes in the tissue.

  13. The relationship between node degree and dissipation rate in networks of diffusively coupled oscillators and its significance for pancreatic beta cells.

    PubMed

    Gosak, Marko; Stožer, Andraž; Markovič, Rene; Dolenšek, Jurij; Marhl, Marko; Rupnik, Marjan Slak; Perc, Matjaž

    2015-07-01

    Self-sustained oscillatory dynamics is a motion along a stable limit cycle in the phase space, and it arises in a wide variety of mechanical, electrical, and biological systems. Typically, oscillations are due to a balance between energy dissipation and generation. Their stability depends on the properties of the attractor, in particular, its dissipative characteristics, which in turn determine the flexibility of a given dynamical system. In a network of oscillators, the coupling additionally contributes to the dissipation, and hence affects the robustness of the oscillatory solution. Here, we therefore investigate how a heterogeneous network structure affects the dissipation rate of individual oscillators. First, we show that in a network of diffusively coupled oscillators, the dissipation is a linearly decreasing function of the node degree, and we demonstrate this numerically by calculating the average divergence of coupled Hopf oscillators. Subsequently, we use recordings of intracellular calcium dynamics in pancreatic beta cells in mouse acute tissue slices and the corresponding functional connectivity networks for an experimental verification of the presented theory. We use methods of nonlinear time series analysis to reconstruct the phase space and calculate the sum of Lyapunov exponents. Our analysis reveals a clear tendency of cells with a higher degree, that is, more interconnected cells, having more negative values of divergence, thus confirming our theoretical predictions. We discuss these findings in the context of energetic aspects of signaling in beta cells and potential risks for pathological changes in the tissue. PMID:26232966

  14. A Novel GLP1 Receptor Interacting Protein ATP6ap2 Regulates Insulin Secretion in Pancreatic Beta Cells.

    PubMed

    Dai, Feihan F; Bhattacharjee, Alpana; Liu, Ying; Batchuluun, Battsetseg; Zhang, Ming; Wang, Xinye Serena; Huang, Xinyi; Luu, Lemieux; Zhu, Dan; Gaisano, Herbert; Wheeler, Michael B

    2015-10-01

    GLP1 activates its receptor, GLP1R, to enhance insulin secretion. The activation and transduction of GLP1R requires complex interactions with a host of accessory proteins, most of which remain largely unknown. In this study, we used membrane-based split ubiquitin yeast two-hybrid assays to identify novel GLP1R interactors in both mouse and human islets. Among these, ATP6ap2 (ATPase H(+)-transporting lysosomal accessory protein 2) was identified in both mouse and human islet screens. ATP6ap2 was shown to be abundant in islets including both alpha and beta cells. When GLP1R and ATP6ap2 were co-expressed in beta cells, GLP1R was shown to directly interact with ATP6ap2, as assessed by co-immunoprecipitation. In INS-1 cells, overexpression of ATP6ap2 did not affect insulin secretion; however, siRNA knockdown decreased both glucose-stimulated and GLP1-induced insulin secretion. Decreases in GLP1-induced insulin secretion were accompanied by attenuated GLP1 stimulated cAMP accumulation. Because ATP6ap2 is a subunit required for V-ATPase assembly of insulin granules, it has been reported to be involved in granule acidification. In accordance with this, we observed impaired insulin granule acidification upon ATP6ap2 knockdown but paradoxically increased proinsulin secretion. Importantly, as a GLP1R interactor, ATP6ap2 was required for GLP1-induced Ca(2+) influx, in part explaining decreased insulin secretion in ATP6ap2 knockdown cells. Taken together, our findings identify a group of proteins that interact with the GLP1R. We further show that one interactor, ATP6ap2, plays a novel dual role in beta cells, modulating both GLP1R signaling and insulin processing to affect insulin secretion. PMID:26272612

  15. Combined Optical Coherence and Fluorescence Microscopy to assess dynamics and specificity of pancreatic beta-cell tracers

    PubMed Central

    Berclaz, Corinne; Pache, Christophe; Bouwens, Arno; Szlag, Daniel; Lopez, Antonio; Joosten, Lieke; Ekim, Selen; Brom, Maarten; Gotthardt, Martin; Grapin-Botton, Anne; Lasser, Theo

    2015-01-01

    The identification of a beta-cell tracer is a major quest in diabetes research. However, since MRI, PET and SPECT cannot resolve individual islets, optical techniques are required to assess the specificity of these tracers. We propose to combine Optical Coherence Microscopy (OCM) with fluorescence detection in a single optical platform to facilitate these initial screening steps from cell culture up to living rodents. OCM can image islets and vascularization without any labeling. Thereby, it alleviates the need of both genetically modified mice to detect islets and injection of external dye to reveal vascularization. We characterized Cy5.5-exendin-3, an agonist of glucagon-like peptide 1 receptor (GLP1R), for which other imaging modalities have been used and can serve as a reference. Cultured cells transfected with GLP1R and incubated with Cy5.5-exendin-3 show full tracer internalization. We determined that a dose of 1 μg of Cy5.5-exendin-3 is sufficient to optically detect in vivo the tracer in islets with a high specificity. In a next step, time-lapse OCM imaging was used to monitor the rapid and specific tracer accumulation in murine islets and its persistence over hours. This optical platform represents a versatile toolbox for selecting beta-cell specific markers for diabetes research and future clinical diagnosis. PMID:25988507

  16. Combined Optical Coherence and Fluorescence Microscopy to assess dynamics and specificity of pancreatic beta-cell tracers.

    PubMed

    Berclaz, Corinne; Pache, Christophe; Bouwens, Arno; Szlag, Daniel; Lopez, Antonio; Joosten, Lieke; Ekim, Selen; Brom, Maarten; Gotthardt, Martin; Grapin-Botton, Anne; Lasser, Theo

    2015-01-01

    The identification of a beta-cell tracer is a major quest in diabetes research. However, since MRI, PET and SPECT cannot resolve individual islets, optical techniques are required to assess the specificity of these tracers. We propose to combine Optical Coherence Microscopy (OCM) with fluorescence detection in a single optical platform to facilitate these initial screening steps from cell culture up to living rodents. OCM can image islets and vascularization without any labeling. Thereby, it alleviates the need of both genetically modified mice to detect islets and injection of external dye to reveal vascularization. We characterized Cy5.5-exendin-3, an agonist of glucagon-like peptide 1 receptor (GLP1R), for which other imaging modalities have been used and can serve as a reference. Cultured cells transfected with GLP1R and incubated with Cy5.5-exendin-3 show full tracer internalization. We determined that a dose of 1 μg of Cy5.5-exendin-3 is sufficient to optically detect in vivo the tracer in islets with a high specificity. In a next step, time-lapse OCM imaging was used to monitor the rapid and specific tracer accumulation in murine islets and its persistence over hours. This optical platform represents a versatile toolbox for selecting beta-cell specific markers for diabetes research and future clinical diagnosis. PMID:25988507

  17. Knowledge Gaps in Rodent Pancreas Biology: Taking Human Pluripotent Stem Cell-Derived Pancreatic Beta Cells into Our Own Hands

    PubMed Central

    Santosa, Munirah Mohamad; Low, Blaise Su Jun; Pek, Nicole Min Qian; Teo, Adrian Kee Keong

    2016-01-01

    In the field of stem cell biology and diabetes, we and others seek to derive mature and functional human pancreatic β cells for disease modeling and cell replacement therapy. Traditionally, knowledge gathered from rodents is extended to human pancreas developmental biology research involving human pluripotent stem cells (hPSCs). While much has been learnt from rodent pancreas biology in the early steps toward Pdx1+ pancreatic progenitors, much less is known about the transition toward Ngn3+ pancreatic endocrine progenitors. Essentially, the later steps of pancreatic β cell development and maturation remain elusive to date. As a result, the most recent advances in the stem cell and diabetes field have relied upon combinatorial testing of numerous growth factors and chemical compounds in an arbitrary trial-and-error fashion to derive mature and functional human pancreatic β cells from hPSCs. Although this hit-or-miss approach appears to have made some headway in maturing human pancreatic β cells in vitro, its underlying biology is vaguely understood. Therefore, in this mini-review, we discuss some of these late-stage signaling pathways that are involved in human pancreatic β cell differentiation and highlight our current understanding of their relevance in rodent pancreas biology. Our efforts here unravel several novel signaling pathways that can be further studied to shed light on unexplored aspects of rodent pancreas biology. New investigations into these signaling pathways are expected to advance our knowledge in human pancreas developmental biology and to aid in the translation of stem cell biology in the context of diabetes treatments. PMID:26834702

  18. Cooperation between HMGA1, PDX-1, and MafA is Essential for Glucose-Induced Insulin Transcription in Pancreatic Beta Cells

    PubMed Central

    Arcidiacono, Biagio; Iiritano, Stefania; Chiefari, Eusebio; Brunetti, Francesco S.; Gu, Guoqiang; Foti, Daniela Patrizia; Brunetti, Antonio

    2014-01-01

    The high-mobility group AT-hook 1 (HMGA1) protein is a nuclear architectural factor that can organize chromatin structures. It regulates gene expression by controlling the formation of stereospecific multiprotein complexes called “enhanceosomes” on the AT-rich regions of target gene promoters. Previously, we reported that defects in HMGA1 caused decreased insulin receptor expression and increased susceptibility to type 2 diabetes mellitus in humans and mice. Interestingly, mice with disrupted HMGA1 gene had significantly smaller islets and decreased insulin content in their pancreata, suggesting that HMGA1 may have a direct role in insulin transcription and secretion. Herein, we investigate the regulatory roles of HMGA1 in insulin transcription. We provide evidence that HMGA1 physically interacts with PDX-1 and MafA, two critical transcription factors for insulin gene expression and beta-cell function, both in vitro and in vivo. We then show that the overexpression of HMGA1 significantly improves the transactivating activity of PDX-1 and MafA on human and mouse insulin promoters, while HMGA1 knockdown considerably decreased this transactivating activity. Lastly, we demonstrate that high glucose stimulus significantly increases the binding of HMGA1 to the insulin (INS) gene promoter, suggesting that HMGA1 may act as a glucose-sensitive element controlling the transcription of the INS gene. Together, our findings provide evidence that HMGA1, by regulating PDX-1- and MafA-induced transactivation of the INS gene promoter, plays a critical role in pancreatic beta-cell function and insulin production. PMID:25628604

  19. Doc2b Serves as a Scaffolding Platform for Concurrent Binding of Multiple Munc18 Isoforms in Pancreatic Islet Beta Cells

    PubMed Central

    Ramalingam, Latha; Lu, Jingping; Hudmon, Andy; Thurmond, Debbie C.

    2015-01-01

    Biphasic glucose-stimulated insulin secretion (GSIS) from pancreatic beta cells involves SNARE protein-regulated exocytosis. SNARE complex assembly further requires the regulatory proteins Munc18c, Munc18-1 and Doc2b. Munc18-1 and Munc18c are required for 1st- and 2nd-phase GSIS, respectively. These distinct Munc18-1 and Munc18c roles are related to their transient high-affinity binding with their cognate t-SNAREs; Syntaxin 1A and Syntaxin 4, respectively. Doc2b is essential for both phases of GSIS, yet the molecular basis for this remains unresolved. Because Doc2b binds to Munc18-1 and Munc18c via it’s distinct C2A and C2B domains, respectively, we hypothesized that Doc2b may provide a plasma membrane-localized scaffold/platform for transient docking of these Munc18 isoforms during GSIS. Toward this, macromolecular complexes composed of Munc18c, Doc2b, and Munc18-1 were detected in beta cells. In vitro interaction assays indicated that Doc2b is required to bridge the interaction between Munc18c and Munc18-1 in the macromolecular complex; Munc18c and Munc18-1 failed to associate in the absence of Doc2b. Competition-based GST-Doc2b interaction assays revealed that Doc2b could simultaneously bind both Munc18-1 and Munc18c. Hence, these data support a working model wherein Doc2b functions as a docking platform/scaffold for transient interactions with the multiple Munc18 isoforms operative in insulin release, promoting SNARE assembly. PMID:25190515

  20. Down-regulation of zinc transporter 8 (SLC30A8) in pancreatic beta-cells promotes cell survival.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pancreatic islet contains high levels of zinc in granular vesicles of ß-cells where insulin is matured, crystallized, and stored before secretion. Zinc is an essential co-factor for insulin crystallization forming dense cores in secretory granules. In insulin-containing secretory granules, zinc ...

  1. Maternal Obesity Accelerates Fetal Pancreatic Beta Cell but not Alpha Cell Development in the Sheep: Prenatal and Postnatal Consequences

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maternal obesity affects offspring weight, body composition and organ function, increasing diabetes and metabolic syndrome risk. We determined effects of maternal obesity and a high energy diet on fetal pancreatic development. Sixty days prior to breeding. ewes were assigned to control (C, 100% of N...

  2. Determinants of glucose toxicity and its reversibility in the pancreatic islet beta-cell line, HIT-T15.

    PubMed

    Gleason, C E; Gonzalez, M; Harmon, J S; Robertson, R P

    2000-11-01

    HIT-T15 cells, a clonal beta-cell line, were cultured and passaged weekly for 6 mo in RPMI 1640 media containing various concentrations of glucose. Insulin content decreased in the intermediate- and late-passage cells as a continuous rather than a threshold glucose concentration effect. In a second series of experiments, cells were grown in media containing either 0.8 or 16.0 mM glucose from passages 76 through 105. Subcultures of passages 86, 92, and 99 that had been grown in media containing 16.0 mM glucose were switched to media containing 0.8 mM glucose and also carried forward to passage 105. Dramatic increases in insulin content and secretion and insulin gene expression were observed when the switches were made at passages 86 and 92 but not when the switch was made at passage 99. These findings suggest that glucose toxicity of insulin-secreting cells is a continuous rather than a threshold function of glucose concentration and that the shorter the period of antecedent glucose toxicity, the more likely that full recovery of cell function will occur. PMID:11052953

  3. Pattern of rise in subplasma membrane Ca{sup 2+} concentration determines type of fusing insulin granules in pancreatic {beta} cells

    SciTech Connect

    Ohara-Imaizumi, Mica; Aoyagi, Kyota; Nakamichi, Yoko; Nishiwaki, Chiyono; Sakurai, Takashi; Nagamatsu, Shinya

    2009-07-31

    We simultaneously analyzed insulin granule fusion with insulin fused to green fluorescent protein and the subplasma membrane Ca{sup 2+} concentration ([Ca{sup 2+}]{sub PM}) with the Ca{sup 2+} indicator Fura Red in rat {beta} cells by dual-color total internal reflection fluorescence microscopy. We found that rapid and marked elevation in [Ca{sup 2+}]{sub PM} caused insulin granule fusion mostly from previously docked granules during the high KCl-evoked release and high glucose-evoked first phase release. In contrast, the slow and sustained elevation in [Ca{sup 2+}]{sub PM} induced fusion from newcomers translocated from the internal pool during the low KCl-evoked release and glucose-evoked second phase release. These data suggest that the pattern of the [Ca{sup 2+}]{sub PM} rise directly determines the types of fusing granules.

  4. Measurements of insulin responses as predictive markers of pancreatic beta-cell mass in normal and beta-cell-reduced lean and obese Göttingen minipigs in vivo.

    PubMed

    Larsen, Marianne O; Rolin, Bidda; Sturis, Jeppe; Wilken, Michael; Carr, Richard D; Pørksen, Niels; Gotfredsen, Carsten F

    2006-04-01

    At present, the best available estimators of beta-cell mass in humans are those based on measurement of insulin levels or appearance rates in the circulation. In several animal models, these estimators have been validated against beta-cell mass in lean animals. However, as many diabetic humans are obese, a correlation between in vivo tests and beta-cell mass must be evaluated over a range of body weights to include different levels of insulin sensitivity. For this purpose, obese (n = 10) and lean (n = 25) Göttingen minipigs were studied. Beta-cell mass had been reduced (n = 16 lean, n = 5 obese) with a combination of nicotinamide (67 mg/kg) and streptozotocin (125 mg/kg), acute insulin response (AIR) to intravenous glucose and/or arginine was tested, pulsatile insulin secretion was evaluated by deconvolution (n = 30), and beta-cell mass was determined histologically. AIR to 0.3 (r(2) = 0.4502, P < 0.0001) or 0.6 g/kg glucose (r(2) = 0.6806, P < 0.0001), 67 mg/kg arginine (r(2) = 0.5730, P < 0.001), and maximum insulin concentration (r(2) = 0.7726, P < 0.0001) were all correlated to beta-cell mass when evaluated across study groups, and regression lines were not different between lean and obese groups except for AIR to 0.3 g/kg glucose. Baseline pulse mass was not significantly correlated to beta-cell mass across the study groups (r(2) = 0.1036, NS), whereas entrained pulse mass did show a correlation across groups (r(2) = 0.4049, P < 0.001). This study supports the use of in vivo tests of insulin responses to evaluate beta-cell mass over a range of body weights in the minipig. Extensive stimulation of insulin secretion by a combination of glucose and arginine seems to give the best correlation to beta-cell mass. PMID:16278249

  5. Canine Fibroblast Growth Factor 21 Ameliorates Hyperglycemia Associated with Inhibiting Hepatic Gluconeogenesis and Improving Pancreatic Beta-Cell Survival in Diabetic Mice and Dogs

    PubMed Central

    Xu, Pengfei; Zhang, Yingjie; Jiang, Xinghao; Li, Junyan; Song, Liying; Khoso, Mir Hasson; Liu, Yunye; Wu, Qiang; Ren, Guiping; Li, Deshan

    2016-01-01

    Diabetes mellitus is a common endocrinopathy in dog. Fibroblast growth factor 21 (FGF-21) is a secreted protein, which is involved in glucose homeostasis. We speculate that the recombinant canine FGF-21 (cFGF-21) has the potential to become a powerful therapeutics to treat canine diabetes. The cFGF-21 gene was cloned and expressed in E. coli Rosetta (DE3). After purification, a cFGF-21 protein with the purity exceeding 95% was obtained. Mouse 3T3-L1 adipocytes and type 1 diabetic mice/dogs induced by STZ were used to examine the biological activity of cFGF-21 in vitro and in vivo, respectively. Results showed that cFGF-21 stimulated glucose uptake in adipocytes significantly in a dose-dependent manner, and reduced plasma glucose significantly in diabetic mice/dogs. After treatment with cFGF-21, the serum insulin level, glycosylated hemoglobin (HbA1c) level and the expressions of the hepatic gluconeogenesis genes (glucose-6-phosphatase, G6Pase and phosphoenolpyruvate carboxykinase, PCK) of the diabetic mice/dogs were attenuated significantly. In the mouse experiment, we also found that the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the expression of suppressor of cytokine signaling 3 (SOCS3) were up-regulated significantly in the livers after treatment. Histopathological and immunohistochemical results showed that treatment with cFGF-21 promoted recovery of pancreatic islets from STZ-induced apoptosis. Besides, we also found that treatment with cFGF-21 protected liver against STZ or hyperglycemia induced damage and the mechanism of this action associated with inhibiting oxidative stress. In conclusion, cFGF-21 represents a promising candidate for canine diabetes therapeutics. The mechanism of cFGF-21 ameliorates hyperglycemia associated with inhibiting hepatic gluconeogenesis by regulation of STAT3 signal pathway and improving pancreatic beta-cell survival. PMID:27203422

  6. Canine Fibroblast Growth Factor 21 Ameliorates Hyperglycemia Associated with Inhibiting Hepatic Gluconeogenesis and Improving Pancreatic Beta-Cell Survival in Diabetic Mice and Dogs.

    PubMed

    Xu, Pengfei; Zhang, Yingjie; Jiang, Xinghao; Li, Junyan; Song, Liying; Khoso, Mir Hasson; Liu, Yunye; Wu, Qiang; Ren, Guiping; Li, Deshan

    2016-01-01

    Diabetes mellitus is a common endocrinopathy in dog. Fibroblast growth factor 21 (FGF-21) is a secreted protein, which is involved in glucose homeostasis. We speculate that the recombinant canine FGF-21 (cFGF-21) has the potential to become a powerful therapeutics to treat canine diabetes. The cFGF-21 gene was cloned and expressed in E. coli Rosetta (DE3). After purification, a cFGF-21 protein with the purity exceeding 95% was obtained. Mouse 3T3-L1 adipocytes and type 1 diabetic mice/dogs induced by STZ were used to examine the biological activity of cFGF-21 in vitro and in vivo, respectively. Results showed that cFGF-21 stimulated glucose uptake in adipocytes significantly in a dose-dependent manner, and reduced plasma glucose significantly in diabetic mice/dogs. After treatment with cFGF-21, the serum insulin level, glycosylated hemoglobin (HbA1c) level and the expressions of the hepatic gluconeogenesis genes (glucose-6-phosphatase, G6Pase and phosphoenolpyruvate carboxykinase, PCK) of the diabetic mice/dogs were attenuated significantly. In the mouse experiment, we also found that the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the expression of suppressor of cytokine signaling 3 (SOCS3) were up-regulated significantly in the livers after treatment. Histopathological and immunohistochemical results showed that treatment with cFGF-21 promoted recovery of pancreatic islets from STZ-induced apoptosis. Besides, we also found that treatment with cFGF-21 protected liver against STZ or hyperglycemia induced damage and the mechanism of this action associated with inhibiting oxidative stress. In conclusion, cFGF-21 represents a promising candidate for canine diabetes therapeutics. The mechanism of cFGF-21 ameliorates hyperglycemia associated with inhibiting hepatic gluconeogenesis by regulation of STAT3 signal pathway and improving pancreatic beta-cell survival. PMID:27203422

  7. Low dose monoethyl phthalate (MEP) exposure triggers proliferation by activating PDX-1 at 1.1B4 human pancreatic beta cells.

    PubMed

    Güven, Celal; Dal, Fulya; Aydoğan Ahbab, Müfide; Taskin, Eylem; Ahbab, Süleyman; Adin Çinar, Suzan; Sırma Ekmekçi, Sema; Güleç, Çağrı; Abacı, Neslihan; Akçakaya, Handan

    2016-07-01

    Phthalate plasticizers used in a wide range of common plastic products are released into the environment and may pose a risk of increased incidence of type 2 diabetes. In this work, we studied the effects of monoethyl phthalate (MEP), the metabolite of diethyl phthalate, exposure on 1.1B4 human pancreatic beta cells at low doses (1-1000 nM). We showed that MEP treatment induced proliferation in 1.1B4 cells. Also PCNA protein expression levels were increased related to proliferation induction. It has been noted that phthalates can exert estrogen mediated response by interacting with ER. In our study 24 h MEP treatment decreased ERα protein expression level conversely it increased the same protein expression level after 72 h treatment. Also MEP treatment decreased ERβ expression after 72 h at 1.1B4 cells. Our results further show that insulin content of 1.1B4 cells were increased with low dose MEP treatment. Along with our insulin content results, PDX- 1 expression levels were also increased at 1.1B4 cells with MEP treatment. These findings suggest that MEP acts as an estrogenic compound and PPARγ agonist at lower concentrations. Also it should be noted that PDX-1 may be a critical regulator of 1.1B4 cells treated with MEP. PMID:27133914

  8. Role of antioxidant enzymes and antioxidant compound probucol in antiradical protection of pancreatic beta-cells during alloxan-induced diabetes.

    PubMed

    Lankin, V Z; Korchin, V I; Konovalova, G G; Lisina, M O; Tikhaze, A K; Akmaev, I G

    2004-01-01

    The severity of disturbances in carbohydrate metabolism in rats with alloxan-induced diabetes depended on activity of antioxidant enzymes in the target organ (pancreas). Damage to the pancreas is related to intensive generation of reactive oxygen species, free radicals, and lipid peroxides. Alloxan-induced diabetes in rats is a free radical disease, which in vivo serves as a useful model for the search for pharmacological preparations with antiradical and antioxidant properties. The antioxidant compound probucol indirectly increased activity of antioxidant enzymes in the pancreas and prevented the development of alloxan-induced diabetes in rats. Our results indicate that different sensitivity of laboratory animals of various species (rats and guinea pigs) to the influence of alloxan is associated with abnormal variations in activity of enzymes utilizing reactive oxygen species and lipid peroxides in mammalian pancreatic cells. PMID:15085236

  9. Involvement of a mitochondrial phosphatase in the regulation of ATP production and insulin secretion in pancreatic beta cells.

    PubMed

    Pagliarini, David J; Wiley, Sandra E; Kimple, Michelle E; Dixon, Jesse R; Kelly, Patrick; Worby, Carolyn A; Casey, Patrick J; Dixon, Jack E

    2005-07-22

    Reversible phosphorylation is the cell's most prevalent form of posttranslational modification, yet its role in the regulation of mitochondrial functions is poorly understood. We have discovered that a member of the dual-specific protein tyrosine phosphatase (DS-PTP) family, PTPMT1 (PTP localized to the Mitochondrion 1) resides nearly exclusively in mitochondria. PTPMT1 is targeted to the mitochondrion by an N-terminal signal sequence and is found anchored to the matrix face of the inner membrane. Knockdown of PTPMT1 expression in the pancreatic insulinoma cell line INS-1 832/13 alters the mitochondrial phosphoprotein profile and markedly enhances both ATP production and insulin secretion. These data define PTPMT1 as a potential drug target for the treatment of type II diabetes and strengthen the notion that mitochondria are an underappreciated site of signaling by reversible phosphorylation. PMID:16039589

  10. Synthesis and evaluation of [18F]Exendin (9-39) as a potential biomarker to measure pancreatic beta-cell mass

    PubMed Central

    Wang, Yi; Lim, Keunpoong; Normandin, Marc; Zhao, Xiaojian; Cline, Gary W.; Ding, Yu-Shin

    2015-01-01

    Introduction Glucagon-like peptide 1 (GLP-1) is released in response to food intake and plays an important role in maintaining blood glucose homeostasis. Exendin (9-39), a potent GLP-1R antagonist, has been labeled with In-111 for SPECT imaging. We report here the first radiosynthesis of [18F]exendin (9-39) ([18F]Ex(9-39)) and an evaluation of its potential as a biomarker for in vivo PET imaging of pancreatic β-cell mass (BCM) in rats. Methods F-18 label was introduced by conjugation of [18F]4-fluorobenzaldehyde with an Ex(9-39) derivative containing a 6-hydrazinonicotinyl group on the -amine of Lys27. PET imaging was carried out in Sprague-Dawley rats (5 control, 5 streptozotocin-induced diabetic) and BioBreeding-Diabetes Prone rats (3 at 7 wks, 3 at 12 wks) using HRRT following 0.187±0.084 mCi [18F]Ex(9-39) administration. Time activity curves were obtained from pancreas, liver and kidney. Pancreases were assayed for insulin content after the imaging study. Results Site-specifically labeled [18F]Ex(9-39) was purified on a G15 open column with radiochemical and chemical purities >98%. PET imaging showed pancreatic SUV peaked at 10 min, and plateaued by 50 min to the end of scan (240 min). No correlations of pancreatic SUV with post-mortem measures of insulin content were seen. Conclusions [18F]Ex(9-39) was successfully prepared and used for PET imaging for the first time to measure pancreatic BCM. The results suggest that derivatization of the Lys27 residue might reduce binding affinity, as evidenced by the absence of specific binding. Exendin analogs radiolabeled at other sites may elucidate the active site required for binding. PMID:22033026

  11. Antibody Response to Serpin B13 Induces Adaptive Changes in Mouse Pancreatic Islets and Slows Down the Decline in the Residual Beta Cell Function in Children with Recent Onset of Type 1 Diabetes Mellitus.

    PubMed

    Kryvalap, Yury; Lo, Chi-Wen; Manuylova, Ekaterina; Baldzizhar, Raman; Jospe, Nicholas; Czyzyk, Jan

    2016-01-01

    Type 1 diabetes mellitus (T1D) is characterized by a heightened antibody (Ab) response to pancreatic islet self-antigens, which is a biomarker of progressive islet pathology. We recently identified a novel antibody to clade B serpin that reduces islet-associated T cell accumulation and is linked to the delayed onset of T1D. As natural immunity to clade B arises early in life, we hypothesized that it may influence islet development during that time. To test this possibility healthy young Balb/c male mice were injected with serpin B13 mAb or IgG control and examined for the number and cellularity of pancreatic islets by immunofluorescence and FACS. Beta cell proliferation was assessed by measuring nucleotide analog 5-ethynyl-2'-deoxyuridine (5-EdU) incorporation into the DNA and islet Reg gene expression was measured by real time PCR. Human studies involved measuring anti-serpin B13 autoantibodies by Luminex. We found that injecting anti-serpin B13 monoclonal Ab enhanced beta cell proliferation and Reg gene expression, induced the generation of ∼80 pancreatic islets per animal, and ultimately led to increase in the beta cell mass. These findings are relevant to human T1D because our analysis of subjects just diagnosed with T1D revealed an association between baseline anti-serpin activity and slower residual beta cell function decline in the first year after the onset of diabetes. Our findings reveal a new role for the anti-serpin immunological response in promoting adaptive changes in the endocrine pancreas and suggests that enhancement of this response could potentially help impede the progression of T1D in humans. PMID:26578518

  12. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells.

    PubMed

    Gerencser, Akos A; Mookerjee, Shona A; Jastroch, Martin; Brand, Martin D

    2016-01-01

    The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions. PMID:27404273

  13. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells

    PubMed Central

    Gerencser, Akos A.; Mookerjee, Shona A.; Jastroch, Martin; Brand, Martin D.

    2016-01-01

    The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions. PMID:27404273

  14. Stevioside counteracts the glyburide-induced desensitization of the pancreatic beta-cell function in mice: studies in vitro.

    PubMed

    Chen, Jianguo; Jeppesen, Per Bendix; Nordentoft, Iver; Hermansen, Kjeld

    2006-12-01

    The sulfonylurea glyburide (GB) is one of the most frequently used drugs in diabetes treatment. Long-term pretreatment with GB causes elevated basal insulin secretion (BIS) and decreased glucose-stimulated insulin secretion (GSIS). These characteristics may play an important role for the development of hypoglycemia and secondary failure. Stevioside (SVS), a substance extracted from leaves of Stevia rebaudiana Bertoni, enhances GSIS but not BIS. The aim of the present study was to clarify whether 24-hour exposure of isolated mouse islets to GB causes dose-dependent decrease in the GSIS and whether it is possible to counteract this desensitization by SVS. We also tested the impact of the incretin glucagon-like peptide-1 (GLP-1) on the GB-induced desensitization. After 24-hour preincubation with GB in combination with SVS or GLP-1, we measured the basal and glucose-stimulated insulin responses and the total islet insulin content. We also determined the fold change in gene expression of pancreatic and duodenal homeobox 1 and glucose transporter isoform 2. After 24-hour preincubation in 11.1 mmol/L glucose, GB (10(-11)-10(-3) mol/L) caused a dose-dependent decrease in GSIS (16.7 mmol/L glucose) (P < .001). GB (10(-7) mol/L) pretreatment elevated BIS, but neither SVS (10(-7) mol/L) nor GLP-1 (10(-7) mol/L) could reverse this. Interestingly, the GB-induced desensitization of GSIS was counteracted by both SVS (P < .05) and GLP-1 (P < .05). SVS reversed the decrease in insulin content caused by GB pretreatment (P < .05). GB pretreatment did not change gene expression of pancreatic and duodenal homeobox 1 nor glucose transporter isoform 2, whereas SVS significantly up-regulated the expression of both genes by more than 2-fold (P < .05). Our results showed that SVS in combination with GB did not reverse GB-induced increase in BIS, whereas both SVS and GLP-1 counteracted GB-induced desensitization of GSIS. SVS is able to counteract the desensitizing effects of GB and may be a

  15. KAT2B Is Required for Pancreatic Beta Cell Adaptation to Metabolic Stress by Controlling the Unfolded Protein Response.

    PubMed

    Rabhi, Nabil; Denechaud, Pierre-Damien; Gromada, Xavier; Hannou, Sarah Anissa; Zhang, Hongbo; Rashid, Talha; Salas, Elisabet; Durand, Emmanuelle; Sand, Olivier; Bonnefond, Amélie; Yengo, Loic; Chavey, Carine; Bonner, Caroline; Kerr-Conte, Julie; Abderrahmani, Amar; Auwerx, Johan; Fajas, Lluis; Froguel, Philippe; Annicotte, Jean-Sébastien

    2016-05-01

    The endoplasmic reticulum (ER) unfolded protein response (UPR(er)) pathway plays an important role in helping pancreatic β cells to adapt their cellular responses to environmental cues and metabolic stress. Although altered UPR(er) gene expression appears in rodent and human type 2 diabetic (T2D) islets, the underlying molecular mechanisms remain unknown. We show here that germline and β cell-specific disruption of the lysine acetyltransferase 2B (Kat2b) gene in mice leads to impaired insulin secretion and glucose intolerance. Genome-wide analysis of Kat2b-regulated genes and functional assays reveal a critical role for Kat2b in maintaining UPR(er) gene expression and subsequent β cell function. Importantly, Kat2b expression is decreased in mouse and human diabetic β cells and correlates with UPR(er) gene expression in normal human islets. In conclusion, Kat2b is a crucial transcriptional regulator for adaptive β cell function during metabolic stress by controlling UPR(er) and represents a promising target for T2D prevention and treatment. PMID:27117420

  16. Pharmacological attenuation of chronic alcoholic pancreatitis induced hypersensitivity in rats

    PubMed Central

    McIlwrath, Sabrina L; Westlund, Karin N

    2015-01-01

    AIM: To characterize an alcohol and high fat diet induced chronic pancreatitis rat model that mimics poor human dietary choices. METHODS: Experimental rats were fed a modified Lieber-DeCarli alcohol (6%) and high-fat (65%) diet (AHF) for 10 wk while control animals received a regular rodent chow diet. Weekly behavioral tests determined mechanical and heat sensitivity. In week 10 a fasting glucose tolerance test was performed, measuring blood glucose levels before and after a 2 g/kg bodyweight intraperitoneal (i.p.) injection of glucose. Post mortem histological analysis was performed by staining pancreas and liver tissue sections with hematoxylin and eosin. Pancreas sections were also stained with Sirius red and fast green to quantify collagen content. Insulin-expressing cells were identified immunohistochemically in separate sections. Tissue staining density was quantified using Image J software. After mechanical and heat sensitivity became stable (weeks 6-10) in the AHF-fed animals, three different drugs were tested for their efficacy in attenuating pancreatitis associated hypersensitivity: a Group II metabotropic glutamate receptor specific agonist (2R,4R)-4-Aminopyrrolidine-2,4-dicarboxylate (APDC, 3 mg/kg, ip; Tocris, Bristol, United Kingdom), nociceptin (20, 60, 200 nmol/kg, ip; Tocris), and morphine sulfate (3 mg/kg, μ-opioid receptor agonist; Baxter Healthcare, Deerfield, IL, United States). RESULTS: Histological analysis of pancreas and liver determined that unlike control rats, AHF fed animals had pancreatic fibrosis, acinar and beta cell atrophy, with steatosis in both organs. Fat vacuolization was significantly increased in AHF fed rats (6.4% ± 1.1% in controls vs 23.8% ± 4.2%, P < 0.05). Rats fed the AHF diet had reduced fasting glucose tolerance in week 10 when peak blood glucose levels reached significantly higher concentrations than controls (127.4 ± 9.2 mg/dL in controls vs 161.0 ± 8.6 mg/dL, P < 0.05). This concurred with a 3.5 fold higher

  17. On the origin of the beta cell.

    PubMed

    Oliver-Krasinski, Jennifer M; Stoffers, Doris A

    2008-08-01

    The major forms of diabetes are characterized by pancreatic islet beta-cell dysfunction and decreased beta-cell numbers, raising hope for cell replacement therapy. Although human islet transplantation is a cell-based therapy under clinical investigation for the treatment of type 1 diabetes, the limited availability of human cadaveric islets for transplantation will preclude its widespread therapeutic application. The result has been an intense focus on the development of alternate sources of beta cells, such as through the guided differentiation of stem or precursor cell populations or the transdifferentiation of more plentiful mature cell populations. Realizing the potential for cell-based therapies, however, requires a thorough understanding of pancreas development and beta-cell formation. Pancreas development is coordinated by a complex interplay of signaling pathways and transcription factors that determine early pancreatic specification as well as the later differentiation of exocrine and endocrine lineages. This review describes the current knowledge of these factors as they relate specifically to the emergence of endocrine beta cells from pancreatic endoderm. Current therapeutic efforts to generate insulin-producing beta-like cells from embryonic stem cells have already capitalized on recent advances in our understanding of the embryonic signals and transcription factors that dictate lineage specification and will most certainly be further enhanced by a continuing emphasis on the identification of novel factors and regulatory relationships. PMID:18676806

  18. Closing in on Mass Production of Mature Human Beta Cells.

    PubMed

    Kieffer, Timothy J

    2016-06-01

    Human pluripotent stem cell differentiation protocols based on mimicking developmental pathways are getting close to generating fully fledged pancreatic endocrine cells, including insulin-producing beta cells. However, challenges remain in identifying pathways to trigger the attainment of robust glucose responsiveness that occurs postnatally in beta cells. PMID:27257758

  19. TRPV6 channel modulates proliferation of insulin secreting INS-1E beta cell line.

    PubMed

    Skrzypski, M; Khajavi, N; Mergler, S; Szczepankiewicz, D; Kołodziejski, P A; Metzke, D; Wojciechowicz, T; Billert, M; Nowak, K W; Strowski, M Z

    2015-12-01

    Transient receptor potential channel vanilloid type 6 (TRPV6) is a non-selective cation channel with high permeability for Ca²⁺ ions. So far, the role of TRPV6 in pancreatic beta cells is unknown. In the present study, we characterized the role of TRPV6 in controlling calcium signaling, cell proliferation as well as insulin expression, and secretion in experimental INS-1E beta cell model. TRPV6 protein production was downregulated using siRNA by approx. 70%, as detected by Western blot. Intracellular free Ca²⁺ ([Ca²⁺]i) was measured by fluorescence Ca²⁺ imaging using fura-2. Calcineurin/NFAT signaling was analyzed using a NFAT reporter assay as well as a calcineurin activity assay. TRPV6 downregulation resulted in impaired cellular calcium influx. Its downregulation also reduced cell proliferation and decreased insulin mRNA expression. These changes were companied by the inhibition of the calcineurin/NFAT signaling. In contrast, insulin exocytosis was not affected by TRPV6 downregulation. In conclusion, this study demonstrates for the first time the expression of TRPV6 in INS-1E cells and rat pancreatic beta cells and describes its role in modulating calcium signaling, beta cell proliferation and insulin mRNA expression. In contrast, TRPV6 fails to influence insulin secretion. PMID:26384871

  20. Gabapentin-induced mitogenic activity in rat pancreatic acinar cells.

    PubMed

    Dethloff, L; Barr, B; Bestervelt, L; Bulera, S; Sigler, R; LaGattuta, M; de La Iglesia, F

    2000-05-01

    Gabapentin induces pancreatic acinar cell tumors in rats through unknown, yet apparently nongenotoxic mechanisms. The primary objective of this study was to determine whether gabapentin acts as a tumor promoter by stimulating acinar cell proliferation in rat pancreas. To this end, indices of pancreatic growth, including increased pancreatic weight, stimulation of acinar cell proliferation, and/or enhanced expression of immediate-early oncogenes were monitored in rats given gabapentin in the diet at 2 g/kg/day for up to 12 months. Rats fed raw soy flour (RSF), a known inducer of pancreatic acinar cell tumors through cholecystokinin-mediated mitogenic stimulation, were used throughout as positive controls. In addition, recent data suggests that gabapentin binds to the alpha(2)delta subunit of a voltage-gated, L-type calcium channel. Because signaling pathways for proliferative processes in pancreatic acinar cells involve intracellular calcium mobilization, the effects of gabapentin on intracellular calcium mobilization ([Ca(2+)](i)) and (3)H-thymidine incorporation were investigated in pancreatic acinar cells isolated from normal rat pancreas and in the AR42J rat pancreatic tumor cell line. As indicated by BrdU labeling indices, acinar cell proliferation increased 3-fold by Day 3 of RSF treatment and remained slightly greater than controls throughout the experiment. Pancreatic weights of RSF-fed rats were 32 to 56% greater than controls throughout the experiment. In contrast, gabapentin had no effect on pancreatic weight or acinar cell labeling index, and therefore had no apparent effect on pancreatic growth. In isolated pancreatic acinar cells, however, gabapentin induced mobilization of intracellular calcium and caused a slight increase in (3)H-thymidine incorporation. The data suggest that gabapentin may possess low level mitogenic activity, which is not easily detectable in in vivo assays. PMID:10788559

  1. A stereological study of effects of aqueous extract of Tamarindus indica seeds on pancreatic islets in streptozotocin-induced diabetic rats.

    PubMed

    Hamidreza, Hamidreza; Heidari, Zahra; Shahraki, Mohammadreza; Moudi, Bita

    2010-10-01

    Tamarindus indica Linn was used as a traditional medicine for the management of diabetes mellitus in human and experimental animals. This study investigated effects of aqueous extract of Tamarindus indica seeds (AETIS) against STZ-induced damages in pancreatic islands by means of stereological methods. sixty matured normoglycemic male Wistar rats, weighing 200-250 gr, were selected and randomly divided into 6 groups (n=10). Control, STZ-induced diabetic; by intraperitoneal injection of 55 mg/Kg streptozotocin, Treated control group (TC); received AETIS at a dose of 200mg/kg/day, and AETIS treated diabetic groups (TD1-3); received respectively AETIS at the dose of 50, 100,and 200 mg/kg/day by gavage from one week after induction of diabetes by STZ. After 8 weeks of experiment, stereological estimation of volume density and total volume of islets and beta cells, volume weighted mean islets volume, mass of beta cells, islets, and pancreas and total number of islets were done. Volume density and total volume of islets, volume weighted mean islets volume, volume density islets/pancreas, volume density beta cells/islet, mass of islets and pancreas of treated diabetic groups (TD1-3) were significantly higher than untreated diabetic group (P<0.001), and in TD3 group these values were comparable to controls. Although total volume and mass of beta cells in TD1-3 were significantly higher than D group but they were significantly lower than control group (P>0.05). Total number of islets, pancreas wet weight and volume did not show any significant changes between control and experimental groups (P>0.05). Results suggested that AETIS partially restores pancreatic beta cells and repairs STZ-induced damages in rats. PMID:20884458

  2. Evidence that down-regulation of. beta. -cell glucose transporters in non-insulin-dependent diabetes may be the cause of diabetic hyperglycemia

    SciTech Connect

    Orci, L.; Ravazzola, M.; Baetens, D.; Amherdt, M. ); Inman, L.; Johnson, J.H.; Unger, R.H. Dept. of Veterans Affairs Medical Center, Dallas, TX ); Peterson, R.G. ); Newgard, C.B. )

    1990-12-01

    Non-insulin-dependent diabetes mellitus (NIDDM) is attributed to a failure of pancreatic {beta} cells to maintain insulin secretion at a level sufficient to compensate for underlying insulin resistance. In the ZDF rat, a model of NIDDM that closely resembles the human syndrome, the authors have previously reported profound underexpression of GLUT-2, the high-K{sub m} facilitative glucose transporter expressed by {beta} cells of normal animals. Here they report that islets of diabetic rats exhibit a marked decrease in the volume density of GLUT-2-positive {beta} cells and a reduction at the electron-microscopic level in the number of GLUT-2-immunoreactive sites per unit of {beta}-cell plasma membrane. The deficiency of GLUT-2 cannot be induced in normal {beta} cells by in vivo or in vitro exposure to high levels of glucose nor can it be prevented in {beta} cells of prediabetic ZDF rats by elimination of hyperglycemia. They conclude that this dearth of immunodetectable GLUT-2 in NIDDM is not secondary to hyperglycemia and therefore that it may well play a causal role in the development of hyperglycemia.

  3. In vivo regeneration of insulin-producing beta-cells.

    PubMed

    Jun, Hee-Sook

    2010-01-01

    Type 1 and type 2 diabetes mellitus are considered to be caused by defective control of blood glucose resulting from a reduced beta-cell mass. Thus, the restoration of a functional beta-cell mass by replacing the damaged beta-cells or stimulating beta-cell regeneration is a logical approach for the treatment of diabetes. Strategies for increasing the beta-cell mass include stimulating beta-cell replication and differentiation and inhibiting beta-cell death. Treatment with various growth factors such as GLP-1, BTC, HGF, and EGF and forced expression of beta-cell transcription factors such as Pdx-1, NeuroD, and MafA resulted in the regeneration of beta-cells in vivo. Another approach is the administration of stem/progenitor cells, which can differentiate into insulin-producing cells. However, there are no satisfactory methods yet for clinical application. Understanding the mechanisms of the regenerative process of pancreatic beta-cells will pave the way for the development of regenerative medicine for treatment of diabetes. PMID:20217517

  4. Emodin promoted pancreatic claudin-5 and occludin expression in experimental acute pancreatitis rats

    PubMed Central

    Xia, Xian-Ming; Li, Bang-Ku; Xing, Shi-Mei; Ruan, Hai-Ling

    2012-01-01

    AIM: To investigate the effect of emodin on pancreatic claudin-5 and occludin expression, and pancreatic paracellular permeability in acute pancreatitis (AP). METHODS: Experimental pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. Emodin was injected via the external jugular vein 0 or 6 h after induction of AP. Rats from sham operation and AP groups were injected with normal saline at the same time. Samples of pancreas were obtained 6 or 12 h after drug administration. Pancreatic morphology was examined with hematoxylin and eosin staining. Pancreatic edema was estimated by measuring tissue water content. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 level were measured by enzyme-linked immunosorbent assay. Pancreatic paracellular permeability was assessed by tissue dye extravasation. Expression of pancreatic claudin-5 and occludin was examined by immunohistology, quantitative real-time reverse transcriptase polymerase chain reaction and western blotting. RESULTS: Pancreatic TNF-α and IL-6 levels, wet/dry ratio, dye extravasation, and histological score were significantly elevated at 3, 6 and 12 h following sodium taurocholate infusion; treatment with emodin prevented these changes at all time points. Immunostaining of claudin-5 and occludin was detected in rat pancreas, which was distributed in pancreatic acinar cells, ductal cells and vascular endothelial cells, respectively. Sodium taurocholate infusion significantly decreased pancreatic claudin-5 and occludin mRNA and protein levels at 3, 6 and 12 h, and that could be promoted by intravenous administration of emodin at all time points. CONCLUSION: These results demonstrate that emodin could promote pancreatic claudin-5 and occludin expression, and reduce pancreatic paracellular permeability. PMID:22563203

  5. Regeneration of beta cells in islets of Langerhans of pancreas of alloxan diabetic rats by acetone extract of Momordica charantia (Linn.) (bitter gourd) fruits.

    PubMed

    Singh, Neera; Gupta, Manushma

    2007-12-01

    Acetone extract of whole fruit powder of M. charantia (bitter gourd) in doses 25, 50 and 75 mg/100 g body weight lowered the blood glucose from 13.30 to 50% after 8 to 30 days treatment in alloxan diabetic albino rats, confirming antihyperglycemic effect of this plant in diabetic animals and humans. Histological observations with acetone extract showed different phases of recovery of beta cells of the islets of Langerhans of pancreas, which in the untreated diabetic rats were less in number and showed varied degree of atrophy. The most important finding of the present study was observation of the presence of small scattered islets among the acinar tissue in some experimental animals, which may reflect neoformation of islets from pre-existing islet cells. The liver of alloxan diabetic rats showed hydropic degeneration, fatty change and necrosis at some places but liver of extract treated animals was normal. Glycogen localization in liver of diabetic rats was faint but after 30 days treatment with different doses of extract, normal to heavy glycogen localization was observed. PMID:18254212

  6. Activity of "nonspecific pancreatic carboxylesterase" in rat serum in experimentally induced acute pancreatitis (preliminary results).

    PubMed

    Kálmán, A; Kálmán, Z; Velösy, G; Vargha, G; Vargha, G; Papp, M

    1989-01-01

    The aim of this study was to obtain more information on the serum level of "nonspecific pancreatic carboxylesterase" (PCE) in experimentally induced acute pancreatitis in rats. The effects of caerulein stimulation, hepatic duct ligation, bile-pancreatic duct ligation or the effect of retrograde injection of saline, 5% taurocholate and sunflower oil were investigated. The activity of PCE and amylase was measured in the serum, pancreatic tissue, pancreatic juice and ascitic fluid. The changes in PCE activity were greater (both in directions to increase or decrease) than that of amylase, produced by different experimental procedures. The results confirm the thesis that the serum activity of PCE is a more sensitive diagnostic method than that of amylase to detect the inflammatory process in the pancreas or the effect of obstruction of the pancreatic duct. PMID:2480696

  7. Isolation, Characterization and Potential Role in Beta Cell-Endothelium Cross-Talk of Extracellular Vesicles Released from Human Pancreatic Islets

    PubMed Central

    De Lena, Michela; Beltramo, Silvia; Romagnoli, Renato; Salizzoni, Mauro; Melzi, Raffaella; Nano, Rita; Piemonti, Lorenzo; Tetta, Ciro; Biancone, Luigi; Camussi, Giovanni

    2014-01-01

    The cross-talk between beta cells and endothelium plays a key role in islet physiopathology and in the revascularization process after islet transplantation. However, the molecular mechanisms involved in this cross-talk are not fully elucidated. Extracellular vesicles (EVs) are secreted membrane nanoparticles involved in inter-cellular communication through the transfer of proteins and nucleic acids. The aims of this study were: 1) isolation and characterization of EVs from human islets; 2) evaluation of the pro-angiogenic effect of islet-derived EVs on human islet endothelial cells (IECs). EVs were isolated by ultracentrifugation from conditioned medium of human islets and characterized by nanotrack analysis (Nanosight), FACS, western blot, bioanalyzer, mRNA/microRNA RT-PCR array. On IECs, we evaluated EV-induced insulin mRNA transfer, proliferation, resistance to apoptosis, in vitro angiogenesis, migration, gene and protein profiling. EVs sized 236±54 nm, expressed different surface molecules and islet-specific proteins (insulin, C-peptide, GLP1R) and carried several mRNAs (VEGFa, eNOS) and microRNAs (miR-27b, miR-126, miR-130 and miR-296) involved in beta cell function, insulin secretion and angiogenesis. Purified EVs were internalized into IECs inducing insulin mRNA expression, protection from apoptosis and enhancement of angiogenesis. Human islets release biologically active EVs able to shuttle specific mRNAs and microRNAs (miRNAs) into target endothelial cells. These results suggest a putative role for islet-derived EVs in beta cell-endothelium cross-talk and in the neoangiogenesis process which is critical for engraftment of transplanted islets. PMID:25028931

  8. Isolation, characterization and potential role in beta cell-endothelium cross-talk of extracellular vesicles released from human pancreatic islets.

    PubMed

    Figliolini, Federico; Cantaluppi, Vincenzo; De Lena, Michela; Beltramo, Silvia; Romagnoli, Renato; Salizzoni, Mauro; Melzi, Raffaella; Nano, Rita; Piemonti, Lorenzo; Tetta, Ciro; Biancone, Luigi; Camussi, Giovanni

    2014-01-01

    The cross-talk between beta cells and endothelium plays a key role in islet physiopathology and in the revascularization process after islet transplantation. However, the molecular mechanisms involved in this cross-talk are not fully elucidated. Extracellular vesicles (EVs) are secreted membrane nanoparticles involved in inter-cellular communication through the transfer of proteins and nucleic acids. The aims of this study were: 1) isolation and characterization of EVs from human islets; 2) evaluation of the pro-angiogenic effect of islet-derived EVs on human islet endothelial cells (IECs). EVs were isolated by ultracentrifugation from conditioned medium of human islets and characterized by nanotrack analysis (Nanosight), FACS, western blot, bioanalyzer, mRNA/microRNA RT-PCR array. On IECs, we evaluated EV-induced insulin mRNA transfer, proliferation, resistance to apoptosis, in vitro angiogenesis, migration, gene and protein profiling. EVs sized 236±54 nm, expressed different surface molecules and islet-specific proteins (insulin, C-peptide, GLP1R) and carried several mRNAs (VEGFa, eNOS) and microRNAs (miR-27b, miR-126, miR-130 and miR-296) involved in beta cell function, insulin secretion and angiogenesis. Purified EVs were internalized into IECs inducing insulin mRNA expression, protection from apoptosis and enhancement of angiogenesis. Human islets release biologically active EVs able to shuttle specific mRNAs and microRNAs (miRNAs) into target endothelial cells. These results suggest a putative role for islet-derived EVs in beta cell-endothelium cross-talk and in the neoangiogenesis process which is critical for engraftment of transplanted islets. PMID:25028931

  9. MicroRNA-29a is up-regulated in beta-cells by glucose and decreases glucose-stimulated insulin secretion

    SciTech Connect

    Bagge, Annika; Clausen, Trine R.; Larsen, Sylvester; Ladefoged, Mette; Rosenstierne, Maiken W.; Larsen, Louise; Vang, Ole; Nielsen, Jens H.; Dalgaard, Louise T.

    2012-09-21

    Highlights: Black-Right-Pointing-Pointer MicroRNA-29a (miR-29a) levels are increased by glucose in human and rat islets and INS-1E cells. Black-Right-Pointing-Pointer miR-29a increases proliferation of INS-1E beta-cells. Black-Right-Pointing-Pointer Forced expression of miR-29a decreases glucose-stimulated insulin secretion (GSIS). Black-Right-Pointing-Pointer Depletion of beta-cell miR-29a improves GSIS. Black-Right-Pointing-Pointer miR-29a may be a mediator of glucose toxicity in beta-cells. -- Abstract: Chronically elevated levels of glucose impair pancreatic beta-cell function while inducing beta-cell proliferation. MicroRNA-29a (miR-29a) levels are increased in several tissues in diabetic animals and mediate decreased insulin-stimulated glucose-transport of adipocytes. The aim was to investigate the impact of glucose on miR-29a levels in INS-1E beta-cells and in human islets of Langerhans and furthermore to evaluate the impact of miR-29a on beta-cell function and proliferation. Increased glucose levels up-regulated miR-29a in beta-cells and human and rat islets of Langerhans. Glucose-stimulated insulin-secretion (GSIS) of INS-1E beta-cells was decreased by forced expression of miR-29a, while depletion of endogenous miR-29a improved GSIS. Over-expression of miR-29a increased INS-1E proliferation. Thus, miR-29a up-regulation is involved in glucose-induced proliferation of beta-cells. Furthermore, as depletion of miR-29a improves beta-cell function, miR-29a is a mediator of glucose-induced beta-cell dysfunction. Glucose-induced up-regulation of miR-29a in beta-cells could be implicated in progression from impaired glucose tolerance to type 2 diabetes.

  10. Protective role of sodium butyrate, a HDAC inhibitor on beta-cell proliferation, function and glucose homeostasis through modulation of p38/ERK MAPK and apoptotic pathways: study in juvenile diabetic rat.

    PubMed

    Khan, S; Jena, G B

    2014-04-25

    Type 1 diabetes (T1D) also known as juvenile diabetes is a chronic autoimmune disorder that precipitates in genetically susceptible individuals by environmental factors particularly during early age. Both genetic and epigenetic factors are implicated in the beta-cell development, proliferation, differentiation and function. Recent evidences suggested that there is a link between diabetes and histone deacetylases (HDACs), because HDAC inhibitors promote beta-cell development, proliferation and function as well as improve glucose homeostasis. Sodium butyrate (NaB) is a short chain fatty acid having HDAC inhibition activity. The present study was aimed to investigate the protective role of NaB treatment on the beta-cell proliferation, function and glucose homeostasis as well as apoptosis in juvenile diabetic rat. Diabetes was induced by single injection of STZ (60 mg/kg, i.p.) in chilled citrate buffer, while NaB (500 mg/kg/day) was administrated by i.p. route for 21 days as pre- and post-treatment schedule. Plasma glucose and insulin levels, HbA1c, glucose tolerance, apoptosis, and expression of proliferating cell nuclear antigen (PCNA), p38, p53, caspase-3, extracellular signal-regulated kinase-1/2 (ERK-1/2), forkhead box protein O1 (FOXO1) and insulin receptor substrate-1 (IRS-1) as well as histone acetylation were evaluated. NaB treatment decreased plasma glucose, HbA1c, beta-cell apoptosis and improved plasma insulin level and glucose homeostasis through HDAC inhibition and histone acetylation in diabetic animal as compared to control. NaB treatment improved the beta-cell proliferation, function and glucose homeostasis as well as reduced beta-cell apoptosis in juvenile diabetic rat by the modulation of p38/ERK MAPK and apoptotic pathway. PMID:24530320

  11. Diabetes in the Cohen Rat Intensifies the Fetal Pancreatic Damage Induced by the Diabetogenic High Sucrose Low Copper Diet.

    PubMed

    Ergaz, Zivanit; Neeman-Azulay, Meytal; Weinstein-Fudim, Liza; Weksler-Zangen, Sarah; Shoshani-Dror, Dana; Szyf, Moshe; Ornoy, Asher

    2016-02-01

    Intrauterine hyperglycemic environment could harm the fetus making it more susceptible to develop postnatal glucose intolerance. A possible mechanism is compromise of the fetal pancreatic development. We previously found that a high sucrose low copper diabetogenic diet induces type 2 diabetes in the Cohen diabetic sensitive rats, but not in the Sabra control rats. However, oxidative stress was observed in the placenta and term fetal liver of diabetic and nondiabetic controls. We now investigated whether the fetal pancreas is affected by this diet and whether the effects result from oxidative stress, maternal hyperglycemia, or both. Term fetal pancreases were evaluated for morphology, beta cells, oxidative stress, apoptosis, and DNA methylation. There were no microscopic changes in hematoxylin and eosin stained sections and beta cells immunostaining in the pancreas of fetuses of both strains. Fetuses of the sensitive strain fed diabetogenic diet had significantly higher activity of superoxide dismutase and catalase, elevated levels of low molecular weight antioxidants, and more intense immunostaining for nuclear factor kappa-B and hypoxia inducing factor-1α. Both strains fed diabetogenic diet had increased immunostaining for Bcl-2-like protein and caspase 3 and decreased immunostaining for 5-methylcytosine in their islets and acini. Our data suggest that maternal diabetogenic diet alters apoptotic rate and epigenetic steady states in the term fetal pancreas, unrelated to maternal diabetes. Maternal hyperglycemia further increases pancreatic oxidative stress, aggravating the pancreatic damage. The diet-induced insults to the fetal pancreas may be an important contributor to the high susceptibility to develop diabetes following metabolic intrauterine insults. PMID:26748987

  12. Ca2+-dependent dephosphorylation of kinesin heavy chain on beta-granules in pancreatic beta-cells. Implications for regulated beta-granule transport and insulin exocytosis

    NASA Technical Reports Server (NTRS)

    Donelan, Matthew J.; Morfini, Gerardo; Julyan, Richard; Sommers, Scott; Hays, Lori; Kajio, Hiroshi; Briaud, Isabelle; Easom, Richard A.; Molkentin, Jeffery D.; Brady, Scott T.; Rhodes, Christopher J.

    2002-01-01

    The specific biochemical steps required for glucose-regulated insulin exocytosis from beta-cells are not well defined. Elevation of glucose leads to increases in cytosolic [Ca2+]i and biphasic release of insulin from both a readily releasable and a storage pool of beta-granules. The effect of elevated [Ca2+]i on phosphorylation of isolated beta-granule membrane proteins was evaluated, and the phosphorylation of four proteins was found to be altered by [Ca2+]i. One (a 18/20-kDa doublet) was a Ca2+-dependent increase in phosphorylation, and, surprisingly, three others (138, 42, and 36 kDa) were Ca2+-dependent dephosphorylations. The 138-kDa beta-granule phosphoprotein was found to be kinesin heavy chain (KHC). At low levels of [Ca2+]i KHC was phosphorylated by casein kinase 2, but KHC was rapidly dephosphorylated by protein phosphatase 2B beta (PP2Bbeta) as [Ca2+]i increased. Inhibitors of PP2B specifically reduced the second, microtubule-dependent, phase of insulin secretion, suggesting that dephosphorylation of KHC was required for transport of beta-granules from the storage pool to replenish the readily releasable pool of beta-granules. This is distinct from synaptic vesicle exocytosis, because neurotransmitter release from synaptosomes did not require a Ca2+-dependent KHC dephosphorylation. These results suggest a novel mechanism for regulating KHC function and beta-granule transport in beta-cells that is mediated by casein kinase 2 and PP2B. They also implicate a novel regulatory role for PP2B/calcineurin in the control of insulin secretion downstream of a rise in [Ca2+]i.

  13. Everolimus and Octreotide Acetate With or Without Bevacizumab in Treating Patients With Locally Advanced or Metastatic Pancreatic Neuroendocrine Tumors That Cannot Be Removed by Surgery

    ClinicalTrials.gov

    2016-06-20

    Gastrin-Producing Neuroendocrine Tumor; Malignant Pancreatic Gastrinoma; Malignant Pancreatic Glucagonoma; Malignant Pancreatic Insulinoma; Malignant Pancreatic Somatostatinoma; Pancreatic Alpha Cell Adenoma; Pancreatic Beta Cell Adenoma; Pancreatic Delta Cell Adenoma; Pancreatic G-Cell Adenoma; Pancreatic Glucagonoma; Pancreatic Insulinoma; Pancreatic Polypeptide Tumor; Recurrent Pancreatic Carcinoma; Recurrent Pancreatic Neuroendocrine Carcinoma; Somatostatin-Producing Neuroendocrine Tumor; Stage III Pancreatic Cancer; Stage IV Pancreatic Cancer

  14. Monitoring of beta cell replacement outcomes.

    PubMed

    Chang, Charles A; Haque, Waqas Z; Yoshimatsu, Gumpei; Balajii, Prathab S; Lawrence, Michael C; Naziruddin, Bashoo

    2016-03-01

    Pancreatic islet transplantation is a promising beta cell replacement treatment for patients with "brittle" type 1 diabetes (T1D) or intractable chronic pancreatitis to restore or preserve pancreatic endocrine function. Early after transplant, a significant islet mass is lost due to an innate inflammatory response, and further loss of the islet graft occurs over time due to immune response, drug toxicity, or metabolic exhaustion. Thus, clinically feasible techniques are essential to monitor islet graft function and survival to maintain appropriate therapy. Currently, islet graft function is monitored using blood glucose levels, insulin and C-peptide levels, and islet imaging. However, these tests are influenced by physiological changes, including beta cell stimulation. Biomarkers that are independent of metabolic stimuli would be more accurate and reliable in detecting islet damage. Antibodies against islet autoantigens are useful but not reliable markers of islet injury due to their presence during the pretransplant period. Several islet-specific proteins such as Glutamate decarboxylase-65, doublecortin, protein phosphatase 1, regulatory (inhibitor) subunit 1A, ubiquitin C-terminal hydrolase-L1, and the high-mobility group box-1 protein have been proposed as candidates to monitor islet damage, but these biomarkers have short half-lives and unreliable detection. Unmethylated insulin DNA has been studied in T1D patients and has been documented as a highly correlative and selective biomarker for beta cell death. More recently, microRNAs (miRNAs) that are selectively expressed in islets have been shown to provide sensitive and accurate quantification of islet damage. Analysis of plasma samples from autologous and allogeneic islet transplant patients has demonstrated the value of miRNA-375 as a specific biomarker to accurately assess islet damage. Use of selective, sensitive, and measurably reproducible biomarkers of islets will lead to effective monitoring of beta

  15. One-step purification of functional human and rat pancreatic alpha cells.

    PubMed

    Köhler, Martin; Daré, Elisabetta; Ali, Muhammed Yusuf; Rajasekaran, Subu Surendran; Moede, Tilo; Leibiger, Barbara; Leibiger, Ingo B; Tibell, Annika; Juntti-Berggren, Lisa; Berggren, Per-Olof

    2012-02-01

    Pancreatic alpha cells contribute to glucose homeostasis by the regulated secretion of glucagon, which increases glycogenolysis and hepatic gluconeogenesis in response to hypoglycemia. Alterations of glucagon secretion are observed in diabetic patients and exacerbate the disease. The restricted availability of purified primary alpha cells has limited our understanding of their function in health and disease. This study was designed to establish convenient protocols for the purification of viable alpha cells from rat and human pancreatic islets by FACS, using intrinsic cellular properties. Islets were isolated from the pancreata of Wistar rats or deceased human organ donors. Dispersed islet cells were separated by FACS based on light scatter and autofluorescence. Purity of sorted cells was evaluated by immunocytochemistry using hormone specific antibodies. Relative hormone expression was further determined by quantitative RT-PCR. Viability was determined by Annexin V and propidium iodide staining and function was assessed by monitoring cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) using Fura-2/AM. We developed species-specific FACS gating strategies that resulted in populations consisting mainly of alpha cells (96.6 ± 1.4%, n = 3 for rat; 95.4 ± 1.7%, n = 4 for human, mean ± SEM). These cell fractions showed ~5-fold and ~4-fold enrichment (rat and human, respectively) of glucagon mRNA expression compared to total ungated islet cells. Most of the sorted cells were viable and functional, as they responded with an increase in [Ca(2+)](i) upon stimulation with L-arginine (10 mM). The majority of the sorted human alpha cells responded also to stimulation with kainate (100 μM), whereas this response was infrequent in rat alpha cells. Using the same sample preparation, but a different gating strategy, we were also able to sort rat and human populations enriched in beta cells. In conclusion, we have simplified and optimized a method for the purification of rat

  16. Intravenous contrast medium aggravates the impairment of pancreatic microcirculation in necrotizing pancreatitis in the rat.

    PubMed Central

    Schmidt, J; Hotz, H G; Foitzik, T; Ryschich, E; Buhr, H J; Warshaw, A L; Herfarth, C; Klar, E

    1995-01-01

    BACKGROUND: Previous reports demonstrated that radiographic contrast medium, as used in contrast-enhanced computed tomography, increases acinar necrosis and mortality in experimental pancreatitis. The authors studied the possibility that these changes may be related to an additional impairment of pancreatic microcirculation. METHODS: Fifty Wistar rats had acute pancreatitis induced by intraductal glycodeoxycholic acid (10 mmol/L for 10 min) and intravenous cerulein (5 micrograms/kg/hr for 6 hrs). After rehydration (16 mL/kg), pancreatic capillary perfusion was quantified by means of intravital microscopy at baseline before intravenous infusion of contrast medium (n = 25) or saline (n = 25), and 30 and 60 minutes thereafter. In addition to total capillary flow, capillaries were categorized as high- or low-flow (> or < 1.6 nL/min). RESULTS: Pancreatic capillary flow did not change in either high- or low-flow capillaries after saline infusion. However, contrast medium infusion induced a significant decrease of total capillary flow (p < 0.001). Analysis according to the relative flow rate revealed that this was primarily because of a significant additional reduction of perfusion in low-flow capillaries (p < 0.0001). Furthermore, complete capillary stasis was observed in 15.9 +/- 3.4% after contrast medium as compared with 3.2 +/- 1.2% after saline infusion (p < 0.006). CONCLUSION: Radiographic contrast medium aggravates the impairment of pancreatic microcirculation in experimental necrotizing pancreatitis. PMID:7717779

  17. Proteomic analysis of pancreatic intraepithelial neoplasia and pancreatic carcinoma in rat models

    PubMed Central

    Wang, Lei; Liu, Hai-Lin; Li, Ya; Yuan, Ping

    2011-01-01

    AIM: To detect the proteomic variabilities of pancreatic intraepithelial neoplasia (PanIN) and pancreatic carcinoma (PC) induced by 7,12-dimethylbenzanthracene (DMBA) in rat models and to identify potential biomarkers. METHODS: Sixty adult male Sprague Dawley rats were randomized into three groups. The rats had DMBA implanted into their pancreas for one (n = 20) or two months (n = 20) or assigned to the normal group (n = 20). The rats were killed after one or two months, and were evaluated histopathologically. Three tissue samples from each group of rats with either normal pancreas, PanIN (PanIN-2) or PC were examined by 2D-DIGE. The different expression spot features were analyzed by matrix-assisted laser desorption/ionization-time of flight/time of flight (MALDI-TOF/TOF) tandem mass spectrometry. The expression of enolase 1, a differentially expressed protein, was identified by immunohistochemistry. RESULTS: There was significant difference in the proportions of neoplastic changes between the 1- and 2-mogroups (P = 0.0488). There was an increase in the frequency of adenocarcinomas in the 2-mo group compared with the 1-mo group (P = 0.0309). No neoplastic changes were observed in any of the animals in the normal group. Enolase 1, pancreatic ELA3B, necdin, Hbp23, CHD3, hnRNP A2/B1, Rap80, and Gnb2l1 were up-regulated in the PanIN and PC tissues, and CEL, TPT1, NME2, PCK2, an unnamed protein product, and glycine C-acetyltransferase were down-regulated in the PanIN and PC tissues. The immunohistochemical results showed that enolase 1 expression was up-regulated in the pancreatic cancer tissues of rats and humans. CONCLUSION: The pancreatic protein expression changes induced by DMBA suggest potential molecular targets for the early diagnosis and treatment of PC. PMID:21472101

  18. Curcumin enhances recovery of pancreatic islets from cellular stress induced inflammation and apoptosis in diabetic rats

    SciTech Connect

    Rashid, Kahkashan; Sil, Parames C.

    2015-02-01

    The phytochemical, curcumin, has been reported to play many beneficial roles. However, under diabetic conditions, the detail mechanism of its beneficial action in the glucose homeostasis regulatory organ, pancreas, is poorly understood. The present study has been designed and carried out to explore the role of curcumin in the pancreatic tissue of STZ induced and cellular stress mediated diabetes in eight weeks old male Wistar rats. Diabetes was induced with a single intraperitoneal dose of STZ (65 mg/kg body weight). Post to diabetes induction, animals were treated with curcumin at a dose of 100 mg/kg body weight for eight weeks. Underlying molecular and cellular mechanism was determined using various biochemical assays, DNA fragmentation, FACS, histology, immunoblotting and ELISA. Treatment with curcumin reduced blood glucose level, increased plasma insulin and mitigated oxidative stress related markers. In vivo and in vitro experimental results revealed increased levels of proinflammatory cytokines (TNF-α, IL1-β and IFN-γ), reduced level of cellular defense proteins (Nrf-2 and HO-1) and glucose transporter (GLUT-2) along with enhanced levels of signaling molecules of ER stress dependent and independent apoptosis (cleaved Caspase-12/9/8/3) in STZ administered group. Treatment with curcumin ameliorated all the adverse changes and helps the organ back to its normal physiology. Results suggest that curcumin protects pancreatic beta-cells by attenuating inflammatory responses, and inhibiting ER/mitochondrial dependent and independent pathways of apoptosis and crosstalk between them. This uniqueness and absence of any detectable adverse effect proposes the possibility of using this molecule as an effective protector in the cellular stress mediated diabetes mellitus. - Highlights: • STZ induced cellular stress plays a vital role in pancreatic dysfunction. • Cellular stress causes inflammation, pancreatic islet cell death and diabetes. • Deregulation of Nrf-2

  19. The expression of dominant negative TCF7L2 in pancreatic beta cells during the embryonic stage causes impaired glucose homeostasis

    PubMed Central

    Shao, Weijuan; Xiong, Xiaoquan; Ip, Wilfred; Xu, Fenghao; Song, Zhuolun; Zeng, Kejing; Hernandez, Marcela; Liang, Tao; Weng, Jianping; Gaisano, Herbert; Nostro, M. Cristina; Jin, Tianru

    2015-01-01

    Objective Disruption of TCF7L2 in mouse pancreatic β-cells has generated different outcomes in several investigations. Here we aim to clarify role of β-cell TCF7L2 and Wnt signaling using a functional-knockdown approach. Methods Adenovirus-mediated dominant negative TCF7L2 (TCF7L2DN) expression was conducted in Ins-1 cells. The fusion gene in which TCF7L2DN expression is driven by PTRE3G was utilized to generate the transgenic mouse line TCF7L2DNTet. The double transgenic line was created by mating TCF7L2DNTet with Ins2-rtTA, designated as βTCFDN. β-cell specific TCF7L2DN expression was induced in βTCFDN by doxycycline feeding. Results TCF7L2DN expression in Ins-1 cells reduced GSIS, cell proliferation and expression of a battery of genes including incretin receptors and β-cell transcription factors. Inducing TCF7L2DN expression in βTCFDN during adulthood or immediately after weaning generated no or very modest metabolic defect, while its expression during embryonic development by doxycycline feeding in pregnant mothers resulted in significant glucose intolerance associated with altered β-cell gene expression and reduced β-cell mass. Conclusions Our observations support a cell autonomous role for TCF7L2 in pancreatic β-cells suggested by most, though not all, investigations. βTCFDN is a novel model for further exploring the role of TCF7L2 in β-cell genesis and metabolic homeostasis. PMID:25830097

  20. Targeting insulin-producing beta cells for regenerative therapy.

    PubMed

    Migliorini, Adriana; Roscioni, Sara S; Lickert, Heiko

    2016-09-01

    Pancreatic beta cells differ in terms of glucose responsiveness, insulin secretion and proliferative capacity; however, the molecular pathways that regulate this cellular heterogeneity are unknown. We have identified the Wnt-planar cell polarity (PCP) effector Flattop (FLTP) as a biomarker that identifies mature beta cells in the islets of Langerhans. Interestingly, three-dimensional architecture and Wnt-PCP ligands are sufficient to trigger mouse and human beta cell maturation. These results highlight the fact that novel biomarkers shed light on the long-standing mystery of beta cell heterogeneity and identify the Wnt-PCP pathway as triggering beta cell maturation. Understanding heterogeneity in the islets of Langerhans might allow targeting of beta cell subpopulations for regenerative therapy and provide building principles for stem cell-derived islets. This review summarises a presentation given at the 'Can we make a better beta cell?' symposium at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by Amin Ardestani and Kathrin Maedler, DOI: 10.1007/s00125-016-3892-9 , and by Harry Heimberg and colleagues, DOI: 10.1007/s00125-016-3879-6 ) and a commentary by the Session Chair, Shanta Persaud (DOI: 10.1007/s00125-016-3870-2 ). PMID:27412250

  1. Muscarinic receptors and amylase secretion of rat pancreatic acini during cerulein-induced acute pancreatitis.

    PubMed

    Morisset, J; Wood, J; Solomon, T E; Larose, L

    1987-08-01

    This study examines the effects of cerulein-induced acute pancreatitis on the secretory response of rat pancreatic acini to carbamylcholine and concentration of acinar muscarinic receptors. Rats were injected subcutaneously every 8 hr with cerulein, 12 micrograms/kg, for two days. They were sacrificed 2 and 4 hr after the first injection, 4 hr after the second and third, and 8 hr after the sixth. By 2 hr after the first injection, carbamylcholine showed decreased potency for stimulating amylase release; decreased potency becomes maximal after the second injection. Four hours after the first injection, carbamylcholine also showed decreased efficacy for causing maximal amylase release. In the course of development of pancreatitis, progressive reductions in muscarinic receptor concentrations were evident from 4 hr after the second injection. Following the complete treatment (8 hr after the sixth injection), no alteration could be observed in the affinity or proportions of each agonist class of muscarinic receptors. These studies indicate that the pancreatic acinar cells still remain functional after acute cerulein-induced pancreatitis, although significant reductions in potency and efficacy of carbamylcholine to cause amylase release and reduced muscarinic receptor concentration occur. PMID:2440647

  2. Intestinal disaccharidase activity following pancreatic duct occlusion in the rat.

    PubMed

    Hauer-Jensen, M; Christensen, K; Wilson, H D; Schedl, H P

    1987-01-01

    The influence of pancreatic secretions on growth and brush-border enzyme activity, throughout the entire small intestine, was examined in the rat. Pancreatic secretions were excluded from the gut lumen by stapling the pancreatic ducts, without interruption of bile flow. The entire small intestine was studied as four segments; the duodenum and three distal segments of equal length. Weight of intestine and mucosa, and mucosal sucrase, isomaltase, lactase, and alkaline phosphatase activity were measured 10-15 days following pancreatic duct occlusion, or sham-operation. The duodenum of pancreatic duct-occluded animals exhibited significant hypertrophy. In general, specific and total disaccharidase activities were greater in duct-occluded animals than in controls throughout the intestine. The increase was more pronounced in distal than in proximal segments. The sucrase/isomaltase ratio was significantly greater in pancreatic duct-occluded animals than in controls in the two distal segments. Alkaline phosphatase activity was not affected by pancreatic duct occlusion. The greater relative increase of disaccharidase activities and sucrase/isomaltase activity ratios in the distal segments of duct-occluded animals, indicates a more important regulatory role of pancreatic enzymes in the distal small intestine. It is concluded that regulation of intestinal brush-border enzyme activity by pancreatic secretion is selective for enzyme and site as follows: disaccharidases, but not alkaline phosphatase, are regulated; the sucrase subunit of the sucrase/isomaltase complex is most sensitive to regulation, while lactase is least sensitive; and the regulatory effect on disaccharidases is greater in distal than in proximal intestine. PMID:3114740

  3. Maturation of Stem Cell-Derived Beta-cells Guided by the Expression of Urocortin 3

    PubMed Central

    van der Meulen, Talitha; Huising, Mark O.

    2014-01-01

    Type 1 diabetes (T1D) is a devastating disease precipitated by an autoimmune response directed at the insulin-producing beta-cells of the pancreas for which no cure exists. Stem cell-derived beta-cells show great promise for a cure as they have the potential to supply unlimited numbers of cells that could be derived from a patient's own cells, thus eliminating the need for immunosuppression. Current in vitro protocols for the differentiation of stem cell-derived beta-cells can successfully generate pancreatic endoderm cells. In diabetic rodents, such cells can differentiate further along the beta-cell lineage until they are eventually capable of restoring normoglycemia. While these observations demonstrate that stem cell-derived pancreatic endoderm has the potential to differentiate into mature, glucose-responsive beta-cells, the signals that direct differentiation and maturation from pancreatic endoderm onwards remain poorly understood. In this review, we analyze the sequence of events that culminates in the formation of beta-cells during embryonic development. and summarize how current protocols to generate beta-cells have sought to capitalize on this ontogenic template. We place particular emphasis on the current challenges and opportunities which occur in the later stages of beta-cell differentiation and maturation of transplantable stem cell-derived beta-cells. Another focus is on the question how the use of recently identified maturation markers such as urocortin 3 can be instrumental in guiding these efforts. PMID:25148370

  4. Glucagon-Like Peptide-1 Receptor Agonists: Beta-Cell Protection or Exhaustion?

    PubMed

    van Raalte, Daniël H; Verchere, C Bruce

    2016-07-01

    Glucagon-like peptide (GLP)-1 receptor agonists enhance insulin secretion and may improve pancreatic islet cell function. However, GLP-1 receptor (GLP-1R) agonist treatment may have more complex, and sometimes deleterious, effects on beta cells. We discuss the concepts of beta cell protection versus exhaustion for different GLP-1R agonists based on recent data. PMID:27160799

  5. Bone marrow-derived pancreatic stellate cells in rats.

    PubMed

    Sparmann, Gisela; Kruse, Marie-Luise; Hofmeister-Mielke, Nicole; Koczan, Dirk; Jaster, Robert; Liebe, Stefan; Wolff, Daniel; Emmrich, Jörg

    2010-03-01

    Origin and fate of pancreatic stellate cells (PSCs) before, during and after pancreatic injury are a matter of debate. The crucial role of PSCs in the pathogenesis of pancreatic fibrosis is generally accepted. However, the turnover of the cells remains obscure. The present study addressed the issue of a potential bone marrow (BM) origin of PSCs. We used a model of stable hematopoietic chimerism by grafting enhanced green fluorescence protein (eGFP)-expressing BM cells after irradiation of acceptor rats. Chimerism was detected by FACS analysis of eGFP-positive cells in the peripheral blood. Dibutyltin dichloride (DBTC) was used to induce acute pancreatic inflammation with subsequent recovery over 4 weeks. Investigations have been focused on isolated cells to detect the resting PSC population. The incidence of eGFP-positive PSC obtained from the pancreas of chimeric rats was approximately 7% in healthy pancreatic tissue and increased significantly to a mean of 18% in the restored pancreas 4 weeks after DBTC-induced acute inflammation. Our results suggest that BM-derived progenitor cells represent a source of renewable stellate cells in the pancreas. Increased numbers of resting PSCs after regeneration point toward enhanced recruitment of BM-derived cells to the pancreas and/or re-acquisition of a quiescent state after inflammation-induced activation. PMID:20101265

  6. BPC 157 therapy to detriment sphincters failure-esophagitis-pancreatitis in rat and acute pancreatitis patients low sphincters pressure.

    PubMed

    Petrovic, I; Dobric, I; Drmic, D; Sever, M; Klicek, R; Radic, B; Brcic, L; Kolenc, D; Zlatar, M; Kunjko, K; Jurcic, D; Martinac, M; Rasic, Z; Boban Blagaic, A; Romic, Z; Seiwerth, S; Sikiric, P

    2011-10-01

    Possibly, acute esophagitis and pancreatitis cause each other, and we focused on sphincteric failure as the common causative key able to induce either esophagitis and acute pancreatitis or both of them, and thereby investigate the presence of a common therapy nominator. This may be an anti-ulcer pentadecapeptide BPC 157 (tested for inflammatory bowel disease, wound treatment) affecting esophagitis, lower esophageal and pyloric sphincters failure and acute pancreatitis (10 μg/kg, 10 ng/kg intraperitoneally or in drinking water). The esophagitis-sphincter failure procedure (i.e., insertion of the tubes into the sphincters, lower esophageal and pyloric) and acute pancreatitis procedure (i.e., bile duct ligation) were combined in rats. Esophageal manometry was done in acute pancreatitis patients. In rats acute pancreatitis procedure produced also esophagitis and both sphincter failure, decreased pressure 24 h post-surgery. Furthermore, bile duct ligation alone immediately declines the pressure in both sphincters. Vice versa, the esophagitis-sphincter failure procedure alone produced acute pancreatitis. What's more, these lesions (esophagitis, sphincter failure, acute pancreatitis when combined) aggravate each other (tubes into sphincters and ligated bile duct). Counteraction occurred by BPC 157 therapies. In acute pancreatitis patients lower pressure at rest was in both esophageal sphincters in acute pancreatitis patients. We conclude that BPC 157 could cure esophagitis/sphincter/acute pancreatitis healing failure. PMID:22204800

  7. The role of the innate immune system in destruction of pancreatic beta cells in NOD mice and humans with type I diabetes.

    PubMed

    Tai, Ningwen; Wong, F Susan; Wen, Li

    2016-07-01

    Type 1 diabetes (T1D) is an organ-specific autoimmune disease characterized by T cell-mediated destruction of the insulin-producing pancreatic β cells. A combination of genetic and environmental factors eventually leads to the loss of functional β cell mass and hyperglycemia. Both innate and adaptive immunity are involved in the development of T1D. In this review, we have highlighted the most recent findings on the role of innate immunity, especially the pattern recognition receptors (PRRs), in disease development. In murine models and human studies, different PRRs, such as toll-like receptors (TLRs) and nucleotide-binding domain, leucine-rich repeat-containing (or Nod-like) receptors (NLRs), have different roles in the pathogenesis of T1D. These PRRs play a critical role in defending against infection by sensing specific ligands derived from exogenous microorganisms to induce innate immune responses and shape adaptive immunity. Animal studies have shown that TLR7, TLR9, MyD88 and NLPR3 play a disease-predisposing role in T1D, while controversial results have been found with other PRRs, such as TLR2, TLR3, TLR4, TLR5 and others. Human studies also shown that TLR2, TLR3 and TLR4 are expressed in either islet β cells or infiltrated immune cells, indicating the innate immunity plays a role in β cell autoimmunity. Furthermore, some human genetic studies showed a possible association of TLR3, TLR7, TLR8 or NLRP3 genes, at single nucleotide polymorphism (SNP) level, with human T1D. Increasing evidence suggest that the innate immunity modulates β cell autoimmunity. Thus, targeting pathways of innate immunity may provide novel therapeutic strategies to fight this disease. PMID:27021275

  8. Beta-cell-specific production of IL6 in conjunction with a mainly intracellular but not mainly surface viral protein causes diabetes

    PubMed Central

    Van Belle, Tom L.; Pagni, Philippe P.; Liao, Jeanette; Sachithanantham, Sowbarnika; Dave, Amy; Hani, Amira Bel; Manenkova, Yulia; Amirian, Natalie; Yang, Cheng; Morin, Bret; Zhang, Haiqing; Campbell, Iain L.; von Herrath, Matthias G.

    2014-01-01

    Inflammatory mechanisms play a key role in the pathogenesis of type 1 and type 2 diabetes. IL6, a pleiotropic cytokine with impact on immune and non-immune cell types, has been proposed to be involved in the events causing both forms of diabetes and to play a key role in experimental insulin-dependent diabetes development. The aim of this study was to investigate how beta-cell specific overexpression of IL-6 influences diabetes development. We developed two lines of rat insulin promoter (RIP)-lymphocytic choriomeningitis virus (LCMV) mice that also co-express IL6 in their beta-cells. Expression of the viral nucleoprotein (NP), which has a predominantly intracellular localization, together with IL6 led to hyperglycemia, which was associated with a loss of GLUT-2 expression in the pancreatic beta-cells and infiltration of CD11b+ cells, but not T cells, in the pancreas. In contrast, over-expression of the LCMV glycoprotein (GP), which can localize to the surface, with IL-6 did not lead to spontaneous diabetes, but accelerated virus-induced diabetes by increasing autoantigen-specific CD8+ T cell responses and reducing the regulatory T cell fraction, leading to increased pancreatic infiltration by CD4+ and CD8+ T cells as well as CD11b+ and CD11c+ cells. The production of IL-6 in beta-cells acts prodiabetic, underscoring the potential benefit of targeting IL6 in diabetes. PMID:24582317

  9. Partial regeneration of beta-cells in the islets of Langerhans by Nymphayol a sterol isolated from Nymphaea stellata (Willd.) flowers.

    PubMed

    Subash-Babu, P; Ignacimuthu, S; Agastian, P; Varghese, Babu

    2009-04-01

    Reduction of the beta-cell mass is critical in the pathogenesis of diabetes mellitus. The discovery of agents which induce regeneration of pancreatic beta-cells would be useful to develop new therapeutic approaches to treat diabetes. The present study was aimed at identifying a new agent for the control of diabetes through regeneration of pancreatic beta cells and insulin secretory potential. Nymphaea stellata flower chloroform extract (NSFCExt) showed significant plasma glucose lowering effect. Further NSFCExt was utilized to isolate and identify the lead compound based on bioassay guided fractionation; we found Nymphayol (25,26-dinorcholest-5-en-3beta-ol) a new crystal [space group P2(1) (No. 4), a=9.618(5), b=7.518(5), c=37.491(5)]. It was purified by repeat column. The structure was determined on the basis of X-ray crystallography and spectral data. Oral administration of Nymphayol for 45 days significantly (p<0.05) lowered the blood glucose level and more importantly it effectively increased the insulin content in diabetic rats. In addition, Nymphayol increased the number of beta cell mass enormously. Islet-like cell clusters in the islets of Langerhans were clearly observed based on histochemical and immunohistochemical study. PMID:19272781

  10. WS6 induces both alpha and beta cell proliferation without affecting differentiation or viability

    PubMed Central

    Boerner, Brian P.; George, Nicholas M.; Mir, Shakeel U.R.; Sarvetnick, Nora E.

    2016-01-01

    Agents that stimulate human pancreatic beta cell proliferation are needed to improve diabetes mellitus treatment. Recently, a small molecule, WS6, was observed to stimulate human beta cell proliferation. However, little is known about its other effects on human islets. To better understand the role of WS6 as a possible beta cell regenerative therapy, we carried out in-depth phenotypic analysis of WS6-treated human islets, exploring its effects on non-beta cell proliferation, beta cell differentiation, and islet cell viability. WS6 not only stimulated beta cell proliferation in cultured human islets (in agreement with previous reports), but also human alpha cell proliferation, indicating that WS6 is not a beta cell-specific mitogen. WS6 did not change the proportion of insulin-positive beta cells or the expression of beta cell-specific transcription factors, suggesting that WS6 does not alter beta cell differentiation, and WS6 had no effect on human islet cell apoptosis or viability. In conclusion, WS6 stimulates proliferation of both human beta and alpha cells while maintaining cellular viability and the beta cell differentiated phenotype. These findings expand the literature on WS6 and support the suggestion that WS6 may help increase human islet mass needed for successful treatment of diabetes. PMID:25739404

  11. Vitamin D3 supplementation increases insulin level by regulating altered IP3 and AMPA receptor expression in the pancreatic islets of streptozotocin-induced diabetic rat.

    PubMed

    Jayanarayanan, Sadanandan; Anju, Thoppil R; Smijin, Soman; Paulose, Cheramadathikudiyil Skaria

    2015-10-01

    Pancreatic islets, particularly insulin-secreting β cells, share common characteristics with neurons. Glutamate is one of the major excitatory neurotransmitter in the brain and pancreas, and its action is mediated through glutamate receptors. In the present work, we analysed the role of vitamin D3 in the modulation of AMPA receptor subunit and their functional role in insulin release. Radio receptor binding study in diabetic rats showed a significant increase in AMPA receptor density. Insulin AMPA colabelling study showed an altered AMPA GluR2 and GluR4 subunit expression in the pancreatic beta cells. We also found lowered IP3 content and decreased IP3 receptor in pancreas of diabetic rats. The alterations in AMPA and IP3 receptor resulted in reduced cytosolic calcium level concentration, which further blocks Ca(2+)-mediated insulin release. Vitamin D3 supplementation restored the alteration in vitamin D receptor expression, AMPA receptor density and AMPA and IP3 receptor expression in the pancreatic islets that helps to restore the calcium-mediated insulin secretion. Our study reveals the antidiabetic property of vitamin D3 that is suggested to have therapeutic role through regulating glutamatergic function in diabetic rats. PMID:26054778

  12. Pancreatic and Pancreatic-Like Microbial Proteases Accelerate Gut Maturation in Neonatal Rats

    PubMed Central

    Prykhodko, Olena; Pierzynowski, Stefan G.; Nikpey, Elham; Arevalo Sureda, Ester; Fedkiv, Olexandr; Weström, Björn R.

    2015-01-01

    Objectives Postnatal gut maturation in neonatal mammals, either at natural weaning or after precocious inducement, is coinciding with enhanced enzymes production by exocrine pancreas. Since the involvement of enzymes in gut functional maturation was overlooked, the present study aimed to investigate the role of enzymes in gut functional maturation using neonatal rats. Methods Suckling rats (Rattus norvegicus) were instagastrically gavaged with porcine pancreatic enzymes (Creon), microbial-derived amylase, protease, lipase and mixture thereof, while controls received α-lactalbumin or water once per day during 14–16 d of age. At 17 d of age the animals were euthanized and visceral organs were dissected, weighed and analyzed for structural and functional properties. For some of the rats, gavage with the macromolecular markers such as bovine serum albumin and bovine IgG was performed 3 hours prior to blood collection to assess the intestinal permeability. Results Gavage with the pancreatic or pancreatic-like enzymes resulted in stimulated gut growth, increased gastric acid secretion and switched intestinal disaccharidases, with decreased lactase and increased maltase and sucrase activities. The fetal-type vacuolated enterocytes were replaced by the adult-type in the distal intestine, and macromolecular transfer to the blood was declined. Enzyme exposure also promoted pancreas growth with increased amylase and trypsin production. These effects were confined to the proteases in a dose-dependent manner. Conclusion Feeding exogenous enzymes, containing proteases, induced precocious gut maturation in suckling rats. This suggests that luminal exposure to proteases by oral loading or, possibly, via enhanced pancreatic secretion involves in the gut maturation of young mammals. PMID:25658606

  13. Quantitative Assessment of Proliferative Effects of Oral Vanadium on Pancreatic Islet Volumes and Beta Cell Numbers of Diabetic Rats

    PubMed Central

    Pirmoradi, Leila; Noorafshan, Ali; Safaee, Akbar; Dehghani, Gholam Abbas

    2016-01-01

    Background: Oral vanadyl sulfate (vanadium) induces normoglycemia, proliferates beta cells and prevents pancreatic islet atrophy in streptozotocin-induced diabetic rats. Soteriological method is used to quantitate the proliferative effects of vanadium on beta-cell numbers and islet volumes of normal and diabetic rats. Methods: Adult male Sprague-Dawley rats were made diabetic with intravenous streptozotocin injection (40 mg/kg). Normal and diabetic rats were divided into four groups. While control normal and diabetic (CD) groups used water, vanadium-treated normal (VTN) and diabetic (VTD) groups used solutions containing vanadyl sulfate (0.5-1 mg/mL, VOSO4+5H2O). Tail blood samples were used to measure blood glucose (BG) and plasma insulin. Two months after treatment, rats were sacrificed, pancreata prepared, and stereology method was used to quantitatively evaluate total beta cell numbers (TBCN) and total islet volumes (TISVOL). Results: Normoglycemia persisted in VTN with significantly decreased plasma insulin (0.190.08 vs. 0.970.27 ng/dL, P<0.002). The respective high BG (53249 vs. 14446 mg/dL, P<0.0001) and reduced plasma insulin (0.260.15 vs. 0.540.19 ng/dL, P<0.002) seen in CD were reversed in VTD during vanadium treatment or withdrawal. While the induction of diabetes, compared to their control, significantly decreased TISVOL (1.90.2 vs. 3.030.6 mm3, P<0.003) and TBCN (0.990.1 vs. 3.20.2 x 106, P<0.003), vanadium treatment significantly increased TISVOL (2.90.8 and 4.071.0 mm3, P<0.003) and TBCN (1.50.3 and 3.80.6 x 106, P<0.03). Conclusion: Two-month oral vanadium therapy in STZ-diabetic rats ameliorated hyperglycemia by partially restoring plasma insulin. This action was through proliferative actions of vanadium in preventing islet atrophy by increasing beta-cell numbers. PMID:26459400

  14. Quantitative-Proteomic Comparison of Alpha and Beta Cells to Uncover Novel Targets for Lineage Reprogramming

    PubMed Central

    Mertins, Philipp; Udeshi, Namrata D.; Dančík, Vlado; Fomina-Yadlin, Dina; Kubicek, Stefan; Clemons, Paul A.; Schreiber, Stuart L.; Carr, Steven A.; Wagner, Bridget K.

    2014-01-01

    Type-1 diabetes (T1D) is an autoimmune disease in which insulin-secreting pancreatic beta cells are destroyed by the immune system. An emerging strategy to regenerate beta-cell mass is through transdifferentiation of pancreatic alpha cells to beta cells. We previously reported two small molecules, BRD7389 and GW8510, that induce insulin expression in a mouse alpha cell line and provide a glimpse into potential intermediate cell states in beta-cell reprogramming from alpha cells. These small-molecule studies suggested that inhibition of kinases in particular may induce the expression of several beta-cell markers in alpha cells. To identify potential lineage reprogramming protein targets, we compared the transcriptome, proteome, and phosphoproteome of alpha cells, beta cells, and compound-treated alpha cells. Our phosphoproteomic analysis indicated that two kinases, BRSK1 and CAMKK2, exhibit decreased phosphorylation in beta cells compared to alpha cells, and in compound-treated alpha cells compared to DMSO-treated alpha cells. Knock-down of these kinases in alpha cells resulted in expression of key beta-cell markers. These results provide evidence that perturbation of the kinome may be important for lineage reprogramming of alpha cells to beta cells. PMID:24759943

  15. Distinct glucose lowering and beta cell protective effects of vanadium and food restriction in streptozotocin-diabetes.

    PubMed

    Cam, M C; Rodrigues, B; McNeill, J H

    1999-11-01

    Vanadium is an oral insulin-mimetic agent that diminishes hyperglycemia, improves beta-cell insulin store and secretory function, and can reverse the diabetic state chronically after withdrawal from treatment. As food restriction has been reported to enhance insulin sensitivity and reduce insulin demand, we assessed the contribution of a reduced food intake to the glucose lowering and beta-cell protective effects of vanadium. Streptozotocin (STZ)-diabetic rats were untreated (D) or administered vanadyl sulfate in the drinking water (DT) at one week prior to and for 5 weeks following the administration of STZ. An additional group was pair-fed (DP) with an equal amount of food as that consumed by the DT group. Shortly after the induction of diabetes, hyperglycemic D rats demonstrated a significant rise in plasma insulin to levels that initially exceeded that of the controls. This was followed by a steady reduction over several weeks, suggesting a gradual depletion of functional beta-cells. Both vanadium treatment and pair-feeding abolished the insulin hypersecretory response following STZ administration. Glucose lowering was enhanced in DT animals when administered higher concentrations of vanadium, despite no further reduction in food intake, and all DT animals (10/10) were normoglycemic by 5 weeks. Mean pancreatic insulin content in DT rats was improved fourfold and was associated with a greater number of granulated beta-cells. Conversely, food restriction only modestly improved glycemia and the pancreatic insulin store and, unlike DT, DP rats remained highly glucose-intolerant. At 5 weeks of diabetes, fed circulating glucose and insulin levels were strongly correlated (P=0.0002) in the D and DP groups, supporting the notion that glucose lowering with food restriction is dependent on improved plasma insulin levels. A separate correlation was observed in DT animals within a lower range of plasma insulin, suggesting that vanadium, unlike food restriction, reduced

  16. Protective effect of a microtubule stabilizer taxol on caerulein-induced acute pancreatitis in rat.

    PubMed Central

    Ueda, T; Takeyama, Y; Kaneda, K; Adachi, M; Ohyanagi, H; Saitoh, Y

    1992-01-01

    The effect of taxol, which is a microtubule stabilizer, was examined in a model of acute edematous pancreatitis induced in rat by the administration of caerulein. Prophylactic administration of taxol ameliorated inhibition of pancreatic secretion, increased level of serum amylase, pancreatic edema, and histological alterations in this model. Immunofluorescence studies revealed that taxol stabilized the arrangement of microtubules by the action of promoting tubulin polymerization and prevented inhibition of pancreatic digestive enzyme secretion. In isolated rat pancreatic acini, taxol reversed the inhibition of amylase secretion induced by supramaximal concentrations of cholecystokinin octapeptide and did not affect the binding of cholecystokinin octapeptide to its receptor. The results obtained in this study suggest that microtubule disorganization is the initiating event in caerulein-induced pancreatitis and that the inhibition of pancreatic digestive enzyme secretion by interfering with intracellular vesicular transport due to microtubule disorganization causes caerulein-induced pancreatitis. Images PMID:1370296

  17. Role of microRNAs in islet beta-cell compensation and failure during diabetes.

    PubMed

    Plaisance, Valérie; Waeber, Gérard; Regazzi, Romano; Abderrahmani, Amar

    2014-01-01

    Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes. PMID:24734255

  18. Role of MicroRNAs in Islet Beta-Cell Compensation and Failure during Diabetes

    PubMed Central

    Plaisance, Valérie; Waeber, Gérard

    2014-01-01

    Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes. PMID:24734255

  19. Effects of Local Pancreatic Renin-Angiotensin System on the Microcirculation of Rat with Severe Acute Pancreatitis.

    PubMed

    Pan, Zhijian; Feng, Ling; Long, Haocheng; Wang, Hui; Feng, Jiarui; Chen, Feixiang

    2015-07-01

    Severe acute pancreatitis (SAP) is normally related to multiorgan dysfunction and local complications. Studies have found that local pancreatic renin-angiotensin system (RAS) was significantly upregulated in drug-induced SAP. The present study aimed to investigate the effects of angiotensin II receptors inhibitor valsartan on dual role of RAS in SAP in a rat model and to elucidate the underlying mechanisms. 3.8% sodium taurocholate (1 ml/kg) was injected to the pancreatic capsule in order for pancreatitis induction. Rats in the sham group were injected with normal saline in identical locations. We also investigated the regulation of experimentally induced SAP on local RAS expression in the pancreas through determination of the activities of serum amylase, lipase and myeloperoxidase, histological and biochemical analysis, radioimmunoassay, fluorescence quantitative PCR and Western blot analysis. The results indicated that valsartan could effectively suppress the local RAS to protect against experimental acute pancreatitis through inhibition of microcirculation disturbances and inflammation. The results suggest that pancreatic RAS plays a critical role in the regulation of pancreatic functions and demonstrates application potential as AT1 receptor antagonists. Moreover, other RAS inhibitors could be a new therapeutic target in acute pancreatitis. PMID:26170733

  20. Effects of Local Pancreatic Renin-Angiotensin System on the Microcirculation of Rat with Severe Acute Pancreatitis

    PubMed Central

    Feng, Ling; Long, Haocheng; Wang, Hui; Feng, Jiarui; Chen, Feixiang

    2015-01-01

    Severe acute pancreatitis (SAP) is normally related to multiorgan dysfunction and local complications. Studies have found that local pancreatic renin-angiotensin system (RAS) was significantly upregulated in drug-induced SAP. The present study aimed to investigate the effects of angiotensin II receptors inhibitor valsartan on dual role of RAS in SAP in a rat model and to elucidate the underlying mechanisms. 3.8% sodium taurocholate (1 ml/kg) was injected to the pancreatic capsule in order for pancreatitis induction. Rats in the sham group were injected with normal saline in identical locations. We also investigated the regulation of experimentally induced SAP on local RAS expression in the pancreas through determination of the activities of serum amylase, lipase and myeloperoxidase, histological and biochemical analysis, radioimmunoassay, fluorescence quantitative PCR and Western blot analysis. The results indicated that valsartan could effectively suppress the local RAS to protect against experimental acute pancreatitis through inhibition of microcirculation disturbances and inflammation. The results suggest that pancreatic RAS plays a critical role in the regulation of pancreatic functions and demonstrates application potential as AT1 receptor antagonists. Moreover, other RAS inhibitors could be a new therapeutic target in acute pancreatitis. PMID:26170733

  1. Serum levels of pancreatic stone protein (PSP)/reg1A as an indicator of beta-cell apoptosis suggest an increased apoptosis rate in hepatocyte nuclear factor 1 alpha (HNF1A-MODY) carriers from the third decade of life onward

    PubMed Central

    2012-01-01

    Background Mutations in the transcription factor hepatocyte nuclear factor-1-alpha (HNF1A) result in the commonest type of maturity onset diabetes of the young (MODY). HNF1A-MODY carriers have reduced pancreatic beta cell mass, partially due to an increased rate of apoptosis. To date, it has not been possible to determine when apoptosis is occurring in HNF1A-MODY.We have recently demonstrated that beta cell apoptosis stimulates the expression of the pancreatic stone protein/regenerating (PSP/reg) gene in surviving neighbour cells, and that PSP/reg1A protein is subsequently secreted from these cells. The objective of this study was to determine whether serum levels of PSP/reg1A are elevated during disease progression in HNF1A-MODY carriers, and whether it may provide information regarding the onset of beta-cell apoptosis. Methods We analysed serum PSP/reg1A levels and correlated with clinical and biochemical parameters in subjects with HNF1A-MODY, glucokinase (GCK-MODY), and type 1 diabetes mellitus. A control group of normoglycaemic subjects was also analysed. Results PSP/reg1A serum levels were significantly elevated in HNF1A-MODY (n = 37) subjects compared to controls (n = 60) (median = 12.50 ng/ml, IQR = 10.61-17.87 ng/ml versus median = 10.72 ng/ml, IQR = 8.94-12.54 ng/ml, p = 0.0008). PSP/reg1A correlated negatively with insulin levels during OGTT, (rho = −0.40, p = 0.02). Interestingly we noted a significant positive correlation of PSP/reg1A with age of the HNF1A-MODY carriers (rho = 0.40 p = 0.02) with an age of 25 years separating carriers with low and high PSP/reg1A levels. Patients with type 1 diabetes mellitus also had elevated serum levels of PSP/reg1A compared to controls, however this was independent of the duration of diabetes. Conclusion Our data suggest that beta cell apoptosis contributes increasingly to the pathophysiology of HNF1A-MODY in patients 25 years and over. PSP/reg1A may be

  2. Pancreatic functions in high salt fed female rats

    PubMed Central

    Lasheen, Noha N

    2015-01-01

    Salt consumption has been increased worldwide and the association of high salt diets with enhanced inflammation and target organ damage was reported. Little data were available about the effect of high salt diet on exocrine function of pancreas, while the relation between high salt intake and insulin sensitivity was controversial. This study was designed to investigate the effect of high salt diet on exocrine and endocrine pancreatic functions, and to elucidate the possible underlying mechanism(s). Twenty adult female Wistar rats were randomly divided into two groups; control group; fed standard rodent diet containing 0.3% NaCl, and high salt fed group; fed 8% NaCl for 8 weeks. On the day of sacrifice, rats were anesthized by i.p. pentobarbitone (40 μg/kg B.W.). Nasoanal length was measured and fasting blood glucose was determined from rat tail. Blood samples were obtained from abdominal aorta for determination of plasma sodium, potassium, amylase, lipase, aldosterone, insulin, transforming growth factor-β (TGF-β1), and interleukin 6 (IL6). Pancreata of both groups were histologically studied. Compared to control group, 8-week high salt fed group showed: significant elevation in body weight, body mass index, Lee index, plasma sodium, TGF-β1 and IL6, however, plasma aldosterone, amylase, lipase, and insulin levels were significantly decreased. A nonsignificant increase in plasma potassium and nonsignificant changes in fasting blood glucose and HOMA-IR were detected between groups. Pancreatic fibrosis was observed in test group. High salt diet for 8 weeks caused pancreatic fibrosis evidenced by decline of both exocrine and endocrine functions of pancreas in Wistar rats. PMID:26216433

  3. Effect of modafinil on pancreatic exocrine secretion in rats. A comparison with adrafinil and related drugs.

    PubMed

    Chariot, J; Appia, F; Vaille, C; Rozé, C

    1987-01-01

    The effects of modafinil and adrafinil, 2 drugs that induce locomotor hyperactivity, and those of the parent compounds CRL 40467 and CRL 40385, were studied on the external pancreatic secretion of anaesthetized and conscious rats. In anaesthetized rats modafinil, adrafinil, and CRL 40385 antagonized the central vagal stimulation of protein output induced by 2-deoxy-D-glucose in the pancreatic juice. In conscious rats, modafinil and adrafinil inhibited the output of protein in the basal interdigestive pancreatic secretion. Modafinil was more active than adrafinil as an inhibitor of pancreatic secretion. The effects of modafinil and adrafinil were different from those of sympathetic amines and dopamine: they did not stimulate the output of bicarbonate in anaesthetized rats, and pancreatic inhibition observed in conscious rats was not inhibited by either yohimbine or prazosin. PMID:2893764

  4. Muscarinic cholinergic receptors in pancreatic acinar carcinoma of rat.

    PubMed

    Taton, G; Delhaye, M; Swillens, S; Morisset, J; Larose, L; Longnecker, D S; Poirier, G G

    1985-04-15

    The active enantiomer of tritiated quinuclidinyl benzilate (3H(-)QNB) was used as a ligand to evaluate the muscarinic receptors. The 3H(-)QNB binding characteristics of muscarinic cholinergic receptors obtained from normal and neoplastic tissues were studied to determine changes in receptor properties during neoplastic transformation. Saturable and stereospecific binding sites for 3H(-)QNB are present in homogenates of rat pancreatic adenocarcinoma. The proportions of high- and low-affinity agonist binding sites are similar for neoplastic and normal tissues. The density of muscarinic receptors is higher in neoplastic (200 femtomoles/mg protein) than in normal pancreatic homogenates (80 femtomoles/mg protein). The muscarinic binding sites of the neoplastic and fetal pancreas show similar KD values which are higher than those observed for normal pancreas. PMID:2580801

  5. Beta-cell mitochondrial carriers and the diabetogenic stress response.

    PubMed

    Brun, Thierry; Maechler, Pierre

    2016-10-01

    Mitochondria play a central role in pancreatic beta-cells by coupling metabolism of the secretagogue glucose to distal events of regulated insulin exocytosis. This process requires transports of both metabolites and nucleotides in and out of the mitochondria. The molecular identification of mitochondrial carriers and their respective contribution to beta-cell function have been uncovered only recently. In type 2 diabetes, mitochondrial dysfunction is an early event and may precipitate beta-cell loss. Under diabetogenic conditions, characterized by glucotoxicity and lipotoxicity, the expression profile of mitochondrial carriers is selectively modified. This review describes the role of mitochondrial carriers in beta-cells and the selective changes in response to glucolipotoxicity. In particular, we discuss the importance of the transfer of metabolites (pyruvate, citrate, malate, and glutamate) and nucleotides (ATP, NADH, NADPH) for beta-cell function and dysfunction. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou. PMID:26979549

  6. Mesobiliverdin IXα Enhances Rat Pancreatic Islet Yield and Function.

    PubMed

    Ito, Taihei; Chen, Dong; Chang, Cheng-Wei Tom; Kenmochi, Takashi; Saito, Tomonori; Suzuki, Satoshi; Takemoto, Jon Y

    2013-01-01

    The aims of this study were to produce mesobiliverdin IXα, an analog of anti-inflammatory biliverdin IXα, and to test its ability to enhance rat pancreatic islet yield for allograft transplantation into diabetic recipients. Mesobiliverdin IXα was synthesized from phycocyanobilin derived from cyanobacteria, and its identity and purity were analyzed by chromatographic and spectroscopic methods. Mesobiliverdin IXα was a substrate for human NADPH biliverdin reductase. Excised Lewis rat pancreata infused with mesobiliverdin IXα and biliverdin IXα-HCl (1-100 μM) yielded islet equivalents as high as 86.7 and 36.5%, respectively, above those from non-treated controls, and the islets showed a high degree of viability based on dithizone staining. When transplanted into livers of streptozotocin-induced diabetic rats, islets from pancreata infused with mesobiliverdin IXα lowered non-fasting blood glucose (BG) levels in 55.6% of the recipients and in 22.2% of control recipients. In intravenous glucose tolerance tests, fasting BG levels of 56 post-operative day recipients with islets from mesobiliverdin IXα infused pancreata were lower than those for controls and showed responses that indicate recovery of insulin-dependent function. In conclusion, mesobiliverdin IXα infusion of pancreata enhanced yields of functional islets capable of reversing insulin dysfunction in diabetic recipients. Since its production is scalable, mesobiliverdin IXα has clinical potential as a protectant of pancreatic islets for allograft transplantation. PMID:23630498

  7. Increased expression of transforming growth factor beta s after acute oedematous pancreatitis in rats suggests a role in pancreatic repair.

    PubMed Central

    Riesle, E; Friess, H; Zhao, L; Wagner, M; Uhl, W; Baczako, K; Gold, L I; Korc, M; Büchler, M W

    1997-01-01

    BACKGROUND: Transforming growth factor beta isoforms (TGF beta s) belong to a family of multifunctional regulators of cellular growth and differentiation. They are mitogenic and chemotactic for fibroblasts and are potent stimulators of extracellular matrix production (collagen) and deposition. Upregulation of TGF beta transcription has been reported for several in vivo systems during repair after injury. AIMS: To study the expression of the three mammalian isoforms of TGF beta (TGF beta 1-3) and their relation to collagen expression as a marker for fibroblast response in acute oedematous pancreatitis in rats. METHODS: Using northern blot analysis and immunohistochemistry, the expression and localisation of TGF beta isoforms, collagen, and amylase were analysed during the course of acute oedematous pancreatitis in rats, experimentally induced by intravenous caerulein infusion. RESULTS: Induction of acute pancreatitis resulted in a biphasic peak pattern of expression of TGF beta 1, beta 2, and beta 3 mRNA, with a pronounced increase from day 1 to day 3 (sixfold, 2.5-fold, fivefold, respectively) and again from day 5 to day 7 (three-fold, 2.3-fold, 3.5-fold, respectively). The temporal changes in TGF beta mRNA identically paralleled the expression in collagen mRNA. In contrast, amylase mRNA expression, used as a general indicator of acinar cell integrity, was slightly decreased after induction of acute pancreatitis. Immunohistochemical analysis of pancreatitis tissue showed that increased expression of TGF beta s was mainly present in the pancreatic acinar and ductal cells; this was evident within one day after pancreatitis induction. CONCLUSION: Overexpression of TGF beta s after induction of acute pancreatitis suggests a role for these proteins in pancreatic repair and remodelling. The increased levels of TGF beta s may help suppress immune activation, and may contribute to the increase in the extracellular matrix including collagen and to the repair of the

  8. Comparative effects of Citrullus colocynthis, sunflower and olive oil-enriched diet in streptozotocin-induced diabetes in rats.

    PubMed

    Sebbagh, N; Cruciani-Guglielmacci, C; Ouali, F; Berthault, M-F; Rouch, C; Sari, D Chabane; Magnan, C

    2009-06-01

    Citrullus colocynthis (colocynth) seeds are traditionally used as antidiabetic medication in Mediterranean countries. The present study evaluated the differential effects of diets enriched with C. colocynthis, sunflower or olive oils on the pancreatic beta-cell mass in streptozotocin (STZ)-induced diabetes in rats. STZ injection induced rapid hyperglycaemia in all animals. However, 2 months later, hyperglycaemia was significantly less pronounced in the rats fed a C. colocynthis oil-enriched diet compared with other rat groups (7.9mM versus 12mM and 16mM with colocynth versus olive and sunflower oils, respectively). Assessment of insulin sensitivity using the homoeostasis model assessment (HOMA) method also indicated less insulin resistance in the rats fed a C. colocynthis oil-enriched diet versus the other rats. Finally, 2 months after STZ injection, the pancreatic beta-cell mass was similar in both the STZ-treated rats fed the colocynth oil-enriched diet and their controls fed the same diet. In contrast, the pancreatic beta-cell mass remained lower in the STZ-induced diabetic rats fed with olive oil- and sunflower oil-enriched diets compared with the C. colocynthis group. We conclude that C. colocynthis oil supplementation may have a beneficial effect by partly preserving or restoring pancreatic beta-cell mass in the STZ-induced diabetes rat model. PMID:19264524

  9. Time course and cellular source of pancreatic regeneration following acute pancreatitis in the rat

    SciTech Connect

    Elsaesser, H.P.A.; Adler, G.; Kern, H.F.

    1986-01-01

    The regenerative capacity of the different cell types in the rat exocrine pancreas has been studied in a model of hormone-induced acute pancreatitis in which pancreatic edema, inflammation, and acinar cell destruction were induced within 12 h of infusion of supramaximal concentrations of cerulein (5 micrograms/kg/h). A sequential biochemical and structural analysis of the pancreas in daily intervals was combined with the autoradiographic quantitation of labeling indices of five cell populations following /sup 3/H-thymidine injection at days 1-7 after induction of pancreatitis. Desquamation of acinar cell apical cytoplasm and release of cytoplasmic segments into the acinar lumen on the first day following induction of pancreatitis led to formation of duct-like tubular complexes. Enzyme content in the pancreas decreased progressively following the formation of the edema to levels 15-20% of controls and remained reduced during the initial 5 days. Thymidine incorporation into total DNA showed a biphasic pattern with a distinct peak at day 1 and a second broader peak between days 4 and 7. Autoradiographic quantitation of labeling indices demonstrated the exclusive incorporation into intercalated duct cells and interstitial cells during the initial 24 h, while the second peak was predominantly due to labeling of acinar cells. Larger interlobular ducts and islets did not show changes in labeling index. In vivo labeling with /sup 3/H-thymidine during the first day and analysis of labeling indices 14 days later showed the persistence of label in intercalated duct cells and interstitial cells and argued against the stem cell hypothesis and against transformation of duct cells into acinar cells.

  10. Metabonomic changes from pancreatic intraepithelial neoplasia to pancreatic ductal adenocarcinoma in tissues from rats.

    PubMed

    Wen, Shi; Li, Zhishui; Feng, Jianghua; Bai, Jianxi; Lin, Xianchao; Huang, Heguang

    2016-06-01

    Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors and is difficult to diagnose in the early phase. This study was aimed at obtaining the metabolic profiles and characteristic metabolites of pancreatic intraepithelial neoplasia (PanIN) and PDAC tissues from Sprague-Dawley (SD) rats to establish metabonomic methods used in the early diagnosis of PDAC. In the present study, the animal models were established by embedding 7,12-dimethylbenzanthracene (DMBA) in the pancreas of SD rats to obtain PanIN and PDAC tissues. After the preprocessing of tissues, (1) H nuclear magnetic resonance (NMR) spectroscopy combined with multivariate and univariate statistical analysis was applied to identify the potential metabolic signatures and the corresponding metabolic pathways. Pattern recognition models were successfully established and differential metabolites, including glucose, amino acids, carboxylic acids and coenzymes, were screened out. Compared with the control, the trends in the variation of several metabolites were similar in both PanIN and PDAC. Kynurenate and methionine levels were elevated in PanIN but decreased in PDAC, thus, could served as biomarkers to distinguish PanIN from PDAC. Our results suggest that NMR-based techniques combined with multivariate statistical analysis can distinguish the metabolic differences among PanIN, PDAC and normal tissues, and, therefore, present a promising approach for physiopathologic metabolism investigations and early diagnoses of PDAC. PMID:27019331

  11. IL-13 improves beta-cell survival and protects against IL-1beta-induced beta-cell death

    PubMed Central

    Rütti, Sabine; Howald, Cédric; Arous, Caroline; Dermitzakis, Emmanouil; Halban, Philippe A.; Bouzakri, Karim

    2015-01-01

    Objectives IL-13 is a cytokine classically produced by anti-inflammatory T-helper-2 lymphocytes; it is decreased in the circulation of type 2 diabetic patients and impacts positively on liver and skeletal muscle. Although IL-13 can exert positive effects on beta-cell lines, its impact and mode of action on primary beta-cell function and survival remain largely unexplored. Methods Beta-cells were cultured for 48 h in the presence of IL-13 alone or in combination with IL-1β or cytokine cocktail (IL-1β, IFNγ, TNFα). Results IL-13 protected human and rat beta-cells against cytokine induced death. However, IL-13 was unable to protect from IL-1β impaired glucose stimulated insulin secretion and did not influence NFκB nuclear relocalization induced by IL-1β. IL-13 induced phosphorylation of Akt, increased IRS2 protein expression and counteracted the IL-1β induced regulation of several beta-cell stress response genes. Conclusions The prosurvival effects of IL-13 thus appear to be mediated through IRS2/Akt signaling with NFκB independent regulation of gene expression. In addition to previously documented beneficial effects on insulin target tissues, these data suggest that IL-13 may be useful for treatment of type 2 diabetes by preserving beta-cell mass or slowing its rate of decline. PMID:26909320

  12. Minireview: beta-cell replacement therapy for diabetes in the 21st century: manipulation of cell fate by directed differentiation.

    PubMed

    Yechoor, Vijay; Chan, Lawrence

    2010-08-01

    Pancreatic beta-cell failure underlies type 1 diabetes; it also contributes in an essential way to type 2 diabetes. beta-Cell replacement is an important component of any cure for diabetes. The current options of islet and pancreas transplantation are not satisfactory as definitive forms of therapy. Here, we review strategies for induced de novo pancreatic beta-cell formation, which depend on the targeted differentiation of cells into pancreatic beta-cells. With this objective in mind, one can manipulate the fate of three different types of cells: 1) from terminally differentiated cells, e.g. exocrine pancreatic cells, into beta-cells; 2) from multipotent adult stem cells, e.g. hepatic oval cells, into pancreatic islets; and 3) from pluripotent stem cells, e.g. embryonic stem cells and induced pluripotent stem cells, into beta-cells. We will examine the pros and cons of each strategy as well as the hurdles that must be overcome before these approaches to generate new beta-cells will be ready for clinical application. PMID:20219891

  13. Genetic predisposition for beta cell fragility underlies type 1 and type 2 diabetes.

    PubMed

    Dooley, James; Tian, Lei; Schonefeldt, Susann; Delghingaro-Augusto, Viviane; Garcia-Perez, Josselyn E; Pasciuto, Emanuela; Di Marino, Daniele; Carr, Edward J; Oskolkov, Nikolay; Lyssenko, Valeriya; Franckaert, Dean; Lagou, Vasiliki; Overbergh, Lut; Vandenbussche, Jonathan; Allemeersch, Joke; Chabot-Roy, Genevieve; Dahlstrom, Jane E; Laybutt, D Ross; Petrovsky, Nikolai; Socha, Luis; Gevaert, Kris; Jetten, Anton M; Lambrechts, Diether; Linterman, Michelle A; Goodnow, Chris C; Nolan, Christopher J; Lesage, Sylvie; Schlenner, Susan M; Liston, Adrian

    2016-05-01

    Type 1 (T1D) and type 2 (T2D) diabetes share pathophysiological characteristics, yet mechanistic links have remained elusive. T1D results from autoimmune destruction of pancreatic beta cells, whereas beta cell failure in T2D is delayed and progressive. Here we find a new genetic component of diabetes susceptibility in T1D non-obese diabetic (NOD) mice, identifying immune-independent beta cell fragility. Genetic variation in Xrcc4 and Glis3 alters the response of NOD beta cells to unfolded protein stress, enhancing the apoptotic and senescent fates. The same transcriptional relationships were observed in human islets, demonstrating the role of beta cell fragility in genetic predisposition to diabetes. PMID:26998692

  14. Chronic stress sensitizes rats to pancreatitis induced by cerulein: Role of TNF-α

    PubMed Central

    Binker, Marcelo G; Binker-Cosen, Andres A; Richards, Daniel; Gaisano, Herbert Y; de Cosen, Rodica H; Cosen-Binker, Laura I

    2010-01-01

    AIM: To investigate chronic stress as a susceptibility factor for developing pancreatitis, as well as tumor necrosis factor-α (TNF-α) as a putative sensitizer. METHODS: Rat pancreatic acini were used to analyze the influence of TNF-α on submaximal (50 pmol/L) cholecystokinin (CCK) stimulation. Chronic restraint (4 h every day for 21 d) was used to evaluate the effects of submaximal (0.2 μg/kg per hour) cerulein stimulation on chronically stressed rats. RESULTS: In vitro exposure of pancreatic acini to TNF-α disorganized the actin cytoskeleton. This was further increased by TNF-α/CCK treatment, which additionally reduced amylase secretion, and increased trypsin and nuclear factor-κB activities in a protein-kinase-C δ and ε-dependent manner. TNF-α/CCK also enhanced caspases’ activity and lactate dehydrogenase release, induced ATP loss, and augmented the ADP/ATP ratio. In vivo, rats under chronic restraint exhibited elevated serum and pancreatic TNF-α levels. Serum, pancreatic, and lung inflammatory parameters, as well as caspases’activity in pancreatic and lung tissue, were substantially enhanced in stressed/cerulein-treated rats, which also experienced tissues’ ATP loss and greater ADP/ATP ratios. Histological examination revealed that stressed/cerulein-treated animals developed abundant pancreatic and lung edema, hemorrhage and leukocyte infiltrate, and pancreatic necrosis. Pancreatitis severity was greatly decreased by treating animals with an anti-TNF-α-antibody, which diminished all inflammatory parameters, histopathological scores, and apoptotic/necrotic markers in stressed/cerulein-treated rats. CONCLUSION: In rats, chronic stress increases susceptibility for developing pancreatitis, which involves TNF-α sensitization of pancreatic acinar cells to undergo injury by physiological cerulein stimulation. PMID:21105189

  15. Developmental patterns for pancreatic opioids in the rat.

    PubMed

    Powell, A M; Voyles, N R; Wilkins, S D; Zalenski, C M; Timmers, K I; Recant, L

    1989-01-01

    Developmental patterns for rat pancreatic opioid peptides and islet hormones were studied from gestational day 20 through adulthood. Fetal tissue was obtained as well as pancreas at birth (day 0), and postnatal days 3, 7, 14, and 21, and 7 weeks. The hormones measured included insulin, glucagon, and somatostatin. The opioids measured were beta-endorphin, Met- and Leu-enkephalins, and the high molecular weight enkephalin precursors. Pancreata were pooled as necessary and extracted (acid alcohol, or hot acetic acid), and opioids were further purified on reversed-phase C-18 (Sep-pak) cartridges. In all instances measurements were made by radioimmunoassays. Precursor peptides were first digested (with trypsin and carboxypeptidase B) prior to immunoassay. All opioids and hormones except the precursors for enkephalins showed a well-defined surge in pancreatic concentration during the first postnatal week. In contrast, the precursors had the highest concentration in the fetus, and by the seventh day of life had decreased by greater than 50%. This progressive decrease may represent maturation of the enkephalin convertase and trypsin-like enzymes in the islets. The opioid and hormonal surges that we have described are similar to the surge in islet concentration of thyroid-releasing hormone (TRH) previously described in neonatal rat islets. It is suggested that these postnatal alterations in opioid and hormone concentration relate to a specific function in the development of the endocrine pancreas. PMID:2530576

  16. Beta-cell preservation…Is weight loss the answer?

    PubMed

    Mazza, Angela D; Pratley, Richard E; Smith, Steven R

    2011-01-01

    Obesity is associated with an increased risk of type 2 diabetes (T2D). Pancreatic beta-cell failure is an early event in the development of glucose dysregulation and diabetes. Interventions to halt beta-cell failure in T2D include diet modification, exercise, and use of pharmacologic agents. There is evidence that abdominal obesity may contribute to diabetes through insulin resistance and beta-cell impairment. Pivotal long-term studies into the prevention of T2D have shown the importance of weight loss beside diet, lifestyle, and medication. The Finnish Diabetes Prevention Program (DPP) showed that weight loss gradually reduces the risk of diabetes, and that even modest weight loss can significantly reduce the incidence of T2D. Similarly, in the US DPP, weight loss as part of intensive lifestyle modification was the major factor in reducing the incidence of T2D in high-risk subjects, being more effective than drug intervention. While understanding the relationship between obesity and diabetes is complex, we know that weight loss has positive effects on adipose tissue. It causes an increase in the beneficial fat cell hormone adiponectin, and a decrease in adipose tissue inflammation. Also, it is associated with reduced insulin resistance and a consequential reduction in glucolipotoxicity, which can improve beta-cell function. In summary, weight loss improves glycemic control and thereby mitigates diabetes symptoms and complications, possibly through the preservation of beta-cell function. Therefore, efforts to prevent diabetes and preserve beta-cell function in patients with T2D should more consequently emphasize and target weight loss. PMID:22580726

  17. Ascorbic acid recycling by cultured beta cells: effects of increased glucose metabolism.

    PubMed

    Steffner, Robert J; Wu, Lan; Powers, Alvin C; May, James M

    2004-11-15

    Ascorbic acid is necessary for optimal insulin secretion from pancreatic islets. We evaluated ascorbate recycling and whether it is impaired by increased glucose metabolism in the rat beta-cell line INS-1. INS-1 cells, engineered with the potential for overexpression of glucokinase under the control of a tetracycline-inducible gene expression system, took up and reduced dehydroascorbic acid to ascorbate in a concentration-dependent manner that was optimal in the presence of physiologic D-glucose concentrations. Ascorbate uptake did not affect intracellular GSH concentrations. Whereas depletion of GSH in culture to levels about 25% of normal also did not affect the ability of the cells to reduce dehydroascorbic acid, more severe acute GSH depletion to less than 10% of normal levels did impair dehydroascorbic acid reduction. Culture of inducible cells in 11.8 mM D-glucose and doxycycline for 48 h enhanced glucokinase activity, increased glucose utilization, abolished D-glucose-dependent insulin secretion, and increased generation of reactive oxygen species. The latter may have contributed to subsequent decreases in the ability of the cells both to maintain intracellular ascorbate and to recycle it from dehydroascorbic acid. Cultured beta cells have a high capacity to recycle ascorbate, but this is sensitive to oxidant stress generated by increased glucose metabolism due to culture in high glucose concentrations and increased glucokinase expression. Impaired ascorbate recycling as a result of increased glucose metabolism may have implications for the role of ascorbate in insulin secretion in diabetes mellitus and may partially explain glucose toxicity in beta cells. PMID:15477012

  18. Impaired pancreatic duct-cell growth in focal areas of regeneration after partial pancreatectomy in the adult Goto-Kakizaki rat, a spontaneous model of non-insulin dependent diabetes mellitus.

    PubMed

    Plachot, C; Portha, B

    2001-03-01

    The Paris colony of adult Goto-Kakizaki (GK/Par) rat, a genetic model of non-insulin dependent diabetes mellitus, is characterized by a restriction of the beta-cell mass and reduced beta-cell regeneration capacity. In order to have a better understanding of the impaired mechanism(s) leading to reduced beta-cell plasticity in the GK/Par rat, we have investigated duct-cell growth capacity following 90% pancreatectomy, a well-defined procedure leading in non-diabetic rats, to sequential duct proliferation and subsequent differentiation. To this aim, we have performed pancreatectomy in 8-10-week-old male normoglycaemic Wistar and diabetic GK rats. Duct-cell proliferation and apoptosis were evaluated at different time points: day 0 (D0), day 2 (D2), day 7 (D7) and day 14 (D14) after pancreatectomy. A transient wave of duct-cell proliferation was observed on D2 in both small and main ducts in the pancreatectomized Wistar rats. A similar increase occurred in the similarly treated GK rats, but to a higher extent as compared to the Wistar rats. Thereafter, duct-cell proliferation from main or small ducts returned to non-pancreatectomized values on D7 and remained at this level on D14 in both the Wistar and GK pancreatectomized groups. In the common pancreatic duct, the number of proliferative duct-cells was higher in GK rats compared to Wistar on D0. In both the operated Wistar and GK rats, duct-cell proliferation from the common pancreatic duct similarly decreased on D2. On D7 and D14, the same parameter returned to non-pancreatectomized values in the Wistar rats, while it was maintained lower in the GK rats as compared to the GK values on D0. In focal areas of regeneration, duct-cell proliferation was significantly lower in the pancreatectomized GK group compared to the age-related Wistar group on D7 (Wistar: 5.85+/-0.98%, GK: 3.02+/-0.69%; p < 0.01) and D14 (Wistar: 3.82+/-0.29%, GK: 2.62+/-0.27%; ns). Only a few apoptotic duct-cells were observed, with no difference

  19. Oxidative stress increases the risk of pancreatic β cell damage in chronic renal hypertensive rats.

    PubMed

    Gao, Shan; Park, Byung M; Cha, Seung A; Bae, Ui J; Park, Byung H; Park, Woo H; Kim, Suhn H

    2016-08-01

    Hypertension often occurs in conjunction with insulin resistance. The purpose of this study was to evaluate whether sustained renal hypertension increases the risk of diabetes mellitus in rats, and to define the underlying mechanisms. Two-kidney, one-clip hypertensive (2K1C) rats received captopril (50 mg/kg/day), α-lipoic acid (100 mg/kg/day), or vehicle treatment for 3 months after surgery. Blood pressure was measured by tail cuff plethysmography. Oral glucose tolerance test (OGTT), immunohistochemistry, and western blotting were performed. In addition, insulin secretion from islet cells was measured. OGTT yielded abnormal results, and the number of islet cells and the size of pancreatic β/α cells were decreased in 2K1C rats. Basal insulin levels were also reduced in the plasma. Insulin secretion from pancreatic islet cells in response to high glucose was also attenuated in 2K1C rats compared with sham rats. The levels of oxidative stress markers, including 8-hydroxydeoxyguanosine and NADPH oxidase-4, were increased in pancreatic tissue and pancreatic islets in 2K1C rats. The abnormalities observed in 2K1C rats were improved by captopril or α-lipoic acid treatment. These findings indicate that sustained renal hypertension may lead to pancreatic dysfunction, increasing oxidative stress in pancreatic islets. PMID:27535482

  20. Effect of Phyllanthus amarus on serum biochemical changes in azaserine induced pancreatic cancer in Wistar rats

    PubMed Central

    Prajapati, Ankit S.; Raval, Sunant K.; Sinha, Suprita; Varia, Tapan N.; Mashiyava, Parimal H.

    2015-01-01

    Aim: The present study was performed to investigate the effect of Phyllanthus amarus extracts on serum biochemical changes in azaserine induced pancreatic cancer in Wistar rats. Materials and Methods: Pancreatic cancer was developed in Wistar rats by intraperitoneal administration of azaserine (cancer inducer) for 21 days at the concentration of 5 mg/kg body weight. Aqueous and alcoholic extracts were given to rats of different groups as per protocol. Results: The results data revealed that oral administration of P. amarus extracts had a significant change in pancreatic amylase, lipase, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activity. Conclusion: We concluded that extract of P. amarus possessed chemoprotective activity against azaserine induced pancreatic cancer in Wistar rats. PMID:27047180

  1. Sensitivity of rat pancreatic A and B cells to somatostatin.

    PubMed

    Schuit, F C; Derde, M P; Pipeleers, D G

    1989-03-01

    Islet A and B cells were purified from the rat pancreas and examined for their respective sensitivity to somatostatin. Both somatostatin-14 (S14) and -28 (S28) inhibited glucagon and insulin release through direct interactions with the corresponding cell types. A dose-dependent suppression of the secretory activities was paralleled by a reduction in cellular cyclic AMP formation with similar ED50 values for both actions. The somatostatin effects on pancreatic hormone release may thus be mediated via an inhibition of adenylate cyclase activity. In pancreatic A cells, S14 and S28 were equally potent inhibitors with ED50 values ranging from 2 x 10(-12) to 2 x 10(-11) mol/l. Pancreatic B cells exhibited a similar sensitivity to S28 as the A cells (ED50 of 2 to 5 x 10(-11) mol/l), but not to S14 (ED50 of 2 x 10(-9) mol/l). Extrapolation of these in vitro sensitivities of islet A and B cells to the in vivo situation suggests that both cell types can respond to circulating S28 levels and that A cells are sensitive to both locally and distally released S14. Islet B cells appear insensitive to the normal peripheral S14 levels but could respond to locally released somatostatin. The marked difference in the sensitivities of islet A and B cells to S14 suggest that these cell types are equipped with different somatostatin receptors. This notion was further supported by the cell-selective actions of the synthetic S14 analogues [D-Trp8, D-Cys14]S14 and desAsn5[D-Trp8, D-Ser13]S14. PMID:2568961

  2. A Simple Matter of Life and Death—The Trials of Postnatal Beta-Cell Mass Regulation

    PubMed Central

    Tarabra, Elena; Pelengaris, Stella; Khan, Michael

    2012-01-01

    Pancreatic beta-cells, which secrete the hormone insulin, are the key arbiters of glucose homeostasis. Defective beta-cell numbers and/or function underlie essentially all major forms of diabetes and must be restored if diabetes is to be cured. Thus, the identification of the molecular regulators of beta-cell mass and a better understanding of the processes of beta-cell differentiation and proliferation may provide further insight for the development of new therapeutic targets for diabetes. This review will focus on the principal hormones and nutrients, as well as downstream signalling pathways regulating beta-cell mass in the adult. Furthermore, we will also address more recently appreciated regulators of beta-cell mass, such as microRNAs. PMID:22577380

  3. Regulation of. beta. -cell glucose transporter gene expression

    SciTech Connect

    Chen, Ling; Alam, Tausif; Johnson, J.H.; Unger, R.H. Department of Veterans Affairs Medical Center, Dallas, TX ); Hughes, S.; Newgard, C.B. )

    1990-06-01

    It has been postulated that a glucose transporter of {beta} cells (GLUT-2) may be important in glucose-stimulated insulin secretion. To determine whether this transporter is constitutively expressed or regulated, the authors subjected conscious unrestrained Wistar rats to perturbations in glucose homeostasis and quantitated {beta}-cell GLUT-2 mRNA by in situ hybridization. After 3 hr of hypoglycemia, GLUT-2 and proinsulin mRNA signal densities were reduced by 25% of the level in control rats. After 4 days, GLUT-2 and proinsulin mRNA densities were reduced by 85% and 65%, respectively. After 12 days of hypoglycemia, the K{sub m} for 3-O-methyl-D-glucose transport in isolated rat islets, normally 18-20 mM, was 2.5 mM. This provides functional evidence of a profound reduction of high K{sub m} glucose transporter in {beta} cells. In contrast, GLUT-2 was only slightly reduced by hypoglycemia in liver. To determine the effect of prolonged hyperglycemia, they also infused animals with 50% (wt/vol) glucose for 5 days. Hyperglycemic clamping increased GLUT-2 mRNA by 46% whereas proinsulin mRNA doubled. They conclude that GLUT-2 expression in {beta} cells, but not liver, is subject to regulation by certain perturbations in blood glucose homeostasis.

  4. Role of pancreatic enzymes and their substrates in autodigestion of the pancreas. In vitro studies with isolated rat pancreatic acini.

    PubMed

    Nagai, H; Henrich, H; Wünsch, P H; Fischbach, W; Mössner, J

    1989-03-01

    Intrapancreatic activation of proteases is believed to play a major role in the pathogenesis of acute necrotizing pancreatitis. Several authors have questioned, however, the central role of trypsin in autodigestion of the pancreas. To clarify the direct effects of pancreatic enzymes and other related factors on acinar cells, we used the model of isolated pancreatic acini. Acini were prepared from male Wistar rats by collagenase digestion. Protein synthesis was measured by incubation of acini with [35S]methionine. Acini were resuspended thereafter in fresh buffer and further incubated for 30-90 min under various conditions [e.g., with pancreatic homogenates, ascites (from rats with pancreatitis induced by sodium taurocholate), pure pancreatic enzymes, and other factors]. The percentage of release of newly synthesized proteins into the culture medium was regarded as a biochemical parameter of cellular integrity. A morphologic score of cellular integrity was obtained via light microscopic evaluation of acini at the end of the various incubations by measuring the degree of cell lysis, loss of cell granules, ballooning, formation of vacuoles, and karyopyknosis. When normal [35S]methionine-labeled pancreatic acini were incubated with various factors, the percentage of release of labeled proteins into the medium was as follows: incubation with HEPES/Ringer's buffer, 1.8%; hemorrhagic pancreatic ascites, 3.8%; pancreatic homogenates, 2.0%; lipase, 1.8%; phospholipase A2, 3.0%; phospholipase A2 + lecithin, 3.2%; trypsin, 2.5%; 5% olive oil, 1.8%; ascites + olive oil, 78.3%; ascites + homogenized epididymal fat, 79.9%; lipase + olive oil, 32.0%; pancreatic homogenates + olive oil, 28.0%; diolein, 2.65%; and oleic acid, 62.9%. The cellular release of radiolabeled proteins showed an inverse correlation with cellular integrity as shown by light microscopy. We postulate that interstitial release of degradation products from triglycerides by lipase causes cellular disruption

  5. Functional somatostatin receptors on a rat pancreatic acinar cell line

    SciTech Connect

    Viguerie, N.; Tahiri-Jouti, N.; Esteve, J.P.; Clerc, P.; Logsdon, C.; Svoboda, M.; Susini, C.; Vaysse, N.; Ribet, A. Mount Zion Hospital and Medical Center, San Francisco, CA Universite Libre de Bruxelles, Brussels )

    1988-07-01

    Somatostatin receptors from a rat pancreatic acinar cell line, AR4-2J, were characterized biochemically, structurally, and functionally. Binding of {sup 125}I-(Tyr{sup 11})Somatostatin to AR4-2J cells was saturable, exhibiting a single class of high-affinity binding sites with a maximal binding capacity of 258 {plus minus} 20 fmol/10{sup 6} cells. Somatostatin receptor structure was analyzed by covalently cross-linking {sup 125}I-(Tyr{sup 11})somatostatin to its plasma membrane receptors. Gel electrophoresis and autoradiography of cross-linked proteins revealed a peptide containing the somatostatin receptor. Somatostatin inhibited vasoactive intestinal peptide (VIP)-stimulated adenosine 3{prime},5{prime}-cyclic monophosphate (cAMP) formation in a dose-dependent manner. The concentration of somatostatin that caused half-maximal inhibition of cAMP formation was close to the receptor affinity for somatostatin. Pertussis toxin pretreatment of AR4-2J cells prevented somatostatin inhibition of VIP-stimulated cAMP formation as well as somatostatin binding. The authors conclude that AR4-2J cells exhibit functional somatostatin receptors that retain both specificity and affinity of the pancreatic acinar cell somatostatin receptors and act via the pertussis toxin-sensitive guanine nucleotide-binding protein N{sub i} to inhibit adenylate cyclase.

  6. Parathyroid Hormone-Related Peptide (1-36) Enhances Beta Cell Regeneration and Increases Beta Cell Mass in a Mouse Model of Partial Pancreatectomy

    PubMed Central

    Mozar, Anaïs; Lin, Hugo; Williams, Katoura; Chin, Connie; Li, Rosemary; Kondegowda, Nagesha Guthalu; Stewart, Andrew F.; Garcia-Ocaña, Adolfo; Vasavada, Rupangi Chhaya

    2016-01-01

    Aims/Hypothesis Finding ways to stimulate the regeneration of endogenous pancreatic beta cells is an important goal in the treatment of diabetes. Parathyroid hormone-related protein (PTHrP), the full-length (1–139) and amino-terminal (1–36) peptides, enhance beta cell function, proliferation, and survival. Therefore, we hypothesize that PTHrP(1–36) has the potential to regenerate endogenous beta cells. Methods The partial pancreatectomy (PPx) mouse model of beta cell injury was used to test this hypothesis. Male Balb/c mice underwent either sham-operation or PPx, and were subsequently injected with PTHrP(1–36) (160μg/kg) or vehicle (veh), for 7, 30, or 90 days. The four groups of mice, sham-veh, sham-PTHrP, PPx-veh, and PPx-PTHrP were assessed for PTHrP and receptor expression, and glucose and beta cell homeostasis. Results PTHrP-receptor, but not the ligand, was significantly up-regulated in islets from mice that underwent PPx compared to sham-operated mice. This suggests that exogenous PTHrP could further enhance beta cell regeneration after PPx. PTHrP did not significantly affect body weight, blood glucose, plasma insulin, or insulin sensitivity, in either sham or PPx mice. Glucose tolerance improved in the PPx-PTHrP versus PPx-veh mice only in the early stages of treatment. As hypothesized, there was a significant increase in beta cell proliferation in PPx-PTHrP mice at days 7 and 30; however, this was normalized by day 90, compared to PPx-veh mice. Enhanced beta cell proliferation translated to a marked increase in beta cell mass at day 90, in PPx-PTHrP versus PPx-veh mice. Conclusions PTHrP(1–36) significantly enhances beta cell regeneration through increased beta cell proliferation and beta cell mass after PPx. Future studies will determine the potential of PTHrP to enhance functional beta cell mass in the setting of diabetes. PMID:27391423

  7. Effects of urtica dioica extract on experimental acute pancreatitis model in rats

    PubMed Central

    Yilmaz, Baris; Basar, Ömer; Aktas, Bora; Altinbas, Akif; Ekiz, Fuat; Büyükcam, Fatih; Albayrak, Aynur; Ginis, Zeynep; Öztürk, Gülfer; Coban, Sahin; Ucar, Engin; Kaya, Oskay; Yüksel, Osman; Caner, Sedat; Delibasi, Tuncay

    2014-01-01

    Acute pancreatitis is the acute inflammation of pancreas and peripancreatic tissues, and distant organs are also affected. The aim of this study was to investigate the effect of Urtica dioica extract (UDE) treatment on cerulein induced acute pancreatitis in rats. Twenty-one Wistar Albino rats were divided into three groups: Control, Pancreatitis, and UDE treatment group. In the control group no procedures were performed. In the pancreatitis and treatment groups, pancreatitis was induced with intraperitoneal injection of cerulein, followed by intraperitoneal injection of 1 ml saline (pancreatitis group) and 1 ml 5.2% UDE (treatment group). Pancreatic tissues were examined histopathologically. Pro-inflammatory cytokines (tumor necrosis factor-α), amylase and markers of apoptosis (M30, M65) were also measured in blood samples. Immunohistochemical staining was performed with Caspase-3 antibody. Histopathological findings in the UDE treatment group were less severe than in the pancreatitis group (5.7 vs 11.7, p = 0.010). TNF-α levels were not statistically different between treated and control groups (63.3 vs. 57.2, p = 0.141). UDE treatment was associated with less apoptosis [determined by M30, caspase-3 index (%)], (1.769 vs. 0.288, p = 0.056; 3% vs. 2.2%, p = 0.224; respectively). UDE treatment of pancreatitis merits further study. PMID:24995088

  8. Quantitative trait loci on chromosome 8q24 for pancreatic beta-cell function and 7q11 for insulin sensitivity in obese nondiabetic white and black families: evidence from genome-wide linkage scans in the NHLBI Hypertension Genetic Epidemiology Network (HyperGEN) study.

    PubMed

    An, Ping; Freedman, Barry I; Rich, Stephen S; Mandel, Stephen A; Arnett, Donna K; Myers, Richard H; Chen, Yii-Der I; Hunt, Steven C; Rao, D C

    2006-02-01

    Genome-wide linkage scans were carried out using a multipoint variance components method in white and black families of the NHLBI Hypertension Genetic Epidemiology Network (HyperGEN) study to identify quantitative trait loci (QTLs) for pancreatic beta-cell function and insulin sensitivity estimated through the newly released nonlinear computer version of homeostasis model assessment 2. Participants fasting <8 h, with diagnosed type 2 diabetes, or taking blood glucose or blood lipid-lowering medications were excluded. Both phenotypes were adjusted separately by race and sex for the effects of age, BMI, and field center before linkage scans using 370 microsatellite markers were performed. A total of 685 white families (1,180 sibpairs) and 773 black families (775 sibpairs) were evaluated as well as subsets including 267 obese white families (757 sibpairs) and 427 obese black families (599 sibpairs) identified through tree-linkage analyses using interacting covariates of age, sex, and BMI. For beta-cell function in the obese white families, significant (logarithm of odds [LOD] score >3.6) evidence supporting linkages was detected on chromosome 8q24 at D8S1179 (135 cM, LOD score 4.2, empirical P = 0.002) and at D8S1128 (140 cM, LOD score 3.7, empirical P = 0.003). In addition, two regions supported linkage for insulin sensitivity index in the obese black families on chromosome 7q11 at D7S3046 (79 cM, LOD score 3.0, empirical P = 0.018) and on chromosome 6q26 at D6S1277 (173 cM, LOD score 3.0, empirical P = 0.018). Reducing clinical heterogeneity using obesity data and improved estimates of beta-cell function and insulin sensitivity may have permitted identification of a QTL on chromosome 8q24 for beta-cell function in the presence of estimated insulin resistance and a QTL on chromosome 7q11 for insulin sensitivity. These regions replicate previous reports for type 2 diabetes-associated traits. PMID:16443794

  9. Circadian Transcription from Beta Cell Function to Diabetes Pathophysiology.

    PubMed

    Perelis, Mark; Ramsey, Kathryn Moynihan; Marcheva, Biliana; Bass, Joseph

    2016-08-01

    The mammalian circadian clock plays a central role in the temporal coordination of physiology across the 24-h light-dark cycle. A major function of the clock is to maintain energy constancy in anticipation of alternating periods of fasting and feeding that correspond with sleep and wakefulness. While it has long been recognized that humans exhibit robust variation in glucose tolerance and insulin sensitivity across the sleep-wake cycle, experimental genetic analysis has now revealed that the clock transcription cycle plays an essential role in insulin secretion and metabolic function within pancreatic beta cells. This review addresses how studies of the beta cell clock may elucidate the etiology of subtypes of diabetes associated with circadian and sleep cycle disruption, in addition to more general forms of the disease. PMID:27440914

  10. Pancreatitis

    MedlinePlus

    ... the hormones insulin and glucagon into the bloodstream. Pancreatitis is inflammation of the pancreas. It happens when digestive enzymes start digesting the pancreas itself. Pancreatitis can be acute or chronic. Either form is ...