Identification of the ectonucleotidases expressed in mouse, rat, and human Langerhans islets: potential role of NTPDase3 in insulin secretion

2010 ◽  
Vol 299 (4) ◽  
pp. E647-E656 ◽  
Author(s):  
Elise G. Lavoie ◽  
Michel Fausther ◽  
Gilles Kauffenstein ◽  
Filip Kukulski ◽  
Beat M. Künzli ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Endocrine Cells ◽  
Islet Cells ◽  
Receptor Activation ◽  
Extracellular Nucleotides ◽  
Local Concentration ◽  
Human Pancreas ◽  
Β Cells ◽  
Potential Implication ◽  
Langerhans Islets

Extracellular nucleotides and adenosine regulate endocrine pancreatic functions such as insulin secretion by Langerhans islet β-cells via the activation of specific P2 and P1 receptors. Membrane-bound ectonucleotidases regulate the local concentration of these ligands and consequently control the activation of their receptors. The objective of this study was to identify and localize the major ectonucleotidases, namely NTPDases and ecto-5′-nucleotidase, present in the endocrine pancreas. In addition, the potential implication of ecto-ATPase activity on insulin secretion was investigated in the rat β-cell line INS-1 (832/13). The localization of ectonucleotidase activity and protein was carried out in situ by enzyme histochemistry and immunolocalization in mouse, rat, and human pancreas sections. NTPDase1 was localized in all blood vessels and acini, and NTPDase2 was localized in capillaries of Langerhans islets and in peripheral conjunctive tissue, whereas NTPDase3 was detected in all Langerhans islet cell types. Interestingly, among the mammalian species tested, ecto-5′-nucleotidase was present only in rat Langerhans islet cells, where it was coexpressed with NTPDase3. Notably, the inhibition of NTPDase3 activity by BG0136 and NF279 facilitated insulin release from INS-1 (832/13) cells under conditions of low glycemia, probably by affecting P2 receptor activation. NTPDase3 activity also regulated the inhibitory effect of exogenous ATP in the presence of a high glucose concentration most likely by controlling adenosine production. In conclusion, all pancreatic endocrine cells express NTPDase3 that was shown to modulate insulin secretion in rat INS-1 (832/13) β-cells. Ecto-5′-nucleotidase is expressed in rat Langerhans islet cells but absent in human and mouse endocrine cells.

scholarly journals SARS-CoV-2 Cell Entry Factors ACE2 and TMPRSS2 are Expressed in the Pancreas but are Not Enriched in Islet Endocrine Cells

2020 ◽  
Author(s):  
Katie C. Coate ◽  
Jeeyeon Cha ◽  
Shristi Shrestha ◽  
Wenliang Wang ◽  
Luciana Mateus Gonçalves ◽  
...  
Keyword(s):  
Pancreatic Islet ◽  
Endocrine Cells ◽  
Islet Cells ◽  
Cell Entry ◽  
Pancreatic Ducts ◽  
Human Pancreas ◽  
Β Cells ◽  
Ductal Cells ◽  
Putative Receptor ◽  
New Onset

Summary/AbstractReports of new-onset diabetes and diabetic ketoacidosis in individuals with COVID-19 have led to the hypothesis that SARS-CoV-2, the virus that causes COVID-19, is directly cytotoxic to pancreatic islet β cells. This would require binding and entry of SARS-CoV-2 into host β cells via cell surface co-expression of ACE2 and TMPRSS2, the putative receptor and effector protease, respectively. To define ACE2 and TMPRSS2 expression in the human pancreas, we examined six transcriptional datasets from primary human islet cells and assessed protein expression by immunofluorescence in pancreata from donors with and without diabetes. ACE2 and TMPRSS2 transcripts were low or undetectable in pancreatic islet endocrine cells as determined by bulk or single cell RNA sequencing, and neither protein was detected in α or β cells from these donors. Instead, ACE2 protein was expressed in the islet and exocrine tissue microvasculature and also found in a subset of pancreatic ducts, whereas TMPRSS2 protein was restricted to ductal cells. The absence of significant ACE2 and TMPRSS2 co-expression in islet endocrine cells reduces the likelihood that SARS-CoV-2 directly infects pancreatic islet β cells through these cell entry proteins.

scholarly journals Regulation of Insulin Secretion and β-Cell Mass by Activating Signal Cointegrator 2

2006 ◽  
Vol 26 (12) ◽  
pp. 4553-4563 ◽  
Author(s):  
Seon-Yong Yeom ◽  
Geun Hyang Kim ◽  
Chan Hee Kim ◽  
Heun Don Jung ◽  
So-Yeon Kim ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Endocrine Cells ◽  
Potential Role ◽  
Cell Mass ◽  
Dominant Negative ◽  
Transcriptional Coactivator ◽  
Β Cells ◽  
Β Cell ◽  
Islet Mass

ABSTRACT Activating signal cointegrator 2 (ASC-2) is a transcriptional coactivator of many nuclear receptors (NRs) and other transcription factors and contains two NR-interacting LXXLL motifs (NR boxes). In the pancreas, ASC-2 is expressed only in the endocrine cells of the islets of Langerhans, but not in the exocrine cells. Thus, we examined the potential role of ASC-2 in insulin secretion from pancreatic β-cells. Overexpressed ASC-2 increased glucose-elicited insulin secretion, whereas insulin secretion was decreased in islets from ASC-2+/− mice. DN1 and DN2 are two dominant-negative fragments of ASC-2 that contain NR boxes 1 and 2, respectively, and block the interactions of cognate NRs with the endogenous ASC-2. Primary rat islets ectopically expressing DN1 or DN2 exhibited decreased insulin secretion. Furthermore, relative to the wild type, ASC-2+/− mice showed reduced islet mass and number, which correlated with increased apoptosis and decreased proliferation of ASC-2+/− islets. These results suggest that ASC-2 regulates insulin secretion and β-cell survival and that the regulatory role of ASC-2 in insulin secretion appears to involve, at least in part, its interaction with NRs via its two NR boxes.

Fluorescence-activated cell sorted rat islet cells and studies of the insulin secretory process

1996 ◽  
Vol 149 (1) ◽  
pp. 145-154 ◽  
Author(s):  
K Josefsen ◽  
J P Stenvang ◽  
H Kindmark ◽  
P-O Berggren ◽  
T Horn ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cells ◽  
Endocrine Cells ◽  
Islet Cells ◽  
Single Cells ◽  
Cell Types ◽  
Glucose Sensing ◽  
Secretory Process ◽  
Functional Coupling ◽  
Paracrine Interaction

Abstract Studies of individual cell types in the islets of Langerhans are complicated by the cells' functional coupling by gap junctions and paracrine interaction. Access to purified alpha and beta cells is therefore desirable. We present a simplified and optimized method for fluorescence-activated cell sorting of endocrine pancreatic rat islets. For dispersion of the islets, dispase was superior to trypsin, as the number of vital single cells was higher (1·1 ± 0·1 × 103 vs 0·6 ± 0·1 × 103/islet, P<0·05). The purity of the sorted cells was 96·7 ± 1·2% for the non-beta cells and 97·8 ± 0·6% for the beta cells (numbers in percentages of endocrine cells). In culture, isolated beta cells, non-beta cells and mixtures of beta and non-beta cells formed aggregates, but not at low temperature (4 °C) and not in medium with low serum content (2%). Finally, in pure beta cell aggregates, glucose stimulated changes in cytoplasmic free Ca2+ concentration although both glucose- and arginine-induced insulin secretion was much reduced. We conclude that alpha cells are necessary for insulin secretion but not for glucose sensing. Journal of Endocrinology (1996) 149, 145–154

scholarly journals Insulin secretory actions of extracts of Asparagus racemosus root in perfused pancreas, isolated islets and clonal pancreatic β-cells

2007 ◽  
Vol 192 (1) ◽  
pp. 159-168 ◽  
Author(s):  
J M A Hannan ◽  
Lamin Marenah ◽  
Liaquat Ali ◽  
Begum Rokeya ◽  
Peter R Flatt ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Ethyl Acetate ◽  
Islet Cells ◽  
Ethanol Extract ◽  
Asparagus Racemosus ◽  
Active Components ◽  
Β Cells ◽  
Perfused Rat Pancreas ◽  
Reduce Blood Glucose ◽  
Intracellular Ca

Asparagus racemosus root has previously been reported to reduce blood glucose in rats and rabbits. In the present study, the effects of the ethanol extract and five partition fractions of the root of A. racemosus were evaluated on insulin secretion together with exploration of their mechanisms of action. The ethanol extract and each of the hexane, chloroform and ethyl acetate partition fractions concentration-dependently stimulated insulin secretion in isolated perfused rat pancreas, isolated rat islet cells and clonal β-cells. The stimulatory effects of the ethanol extract, hexane, chloroform and ethyl acetate partition fractions were potentiated by glucose, 3-isobutyl-1-methyl xanthine IBMX, tolbutamide and depolarizing concentration of KCl. Inhibition of A. racemosus-induced insulin release was observed with diazoxide and verapamil. Ethanol extract and five fractions increased intracellular Ca2+, consistent with the observed abolition of insulin secretory effects under Ca2+-free conditions. These findings reveal that constituents of A. racemosus root extracts have wide-ranging stimulatoryeffects on physiological insulinotropic pathways. Future work assessing the use of this plant as a source of active components may provide new opportunities for diabetes therapy.

scholarly journals Exploration of NPTX2 in Islets of Langerhans

2020 ◽  
Vol 21 (2) ◽  
Author(s):  
Lindsay Elisha Wald
Keyword(s):  
Type 1 Diabetes ◽  
Insulin Secretion ◽  
Islet Cells ◽  
The Body ◽  
Immunofluorescent Staining ◽  
Β Cells ◽  
Healthy Human ◽  
Neuronal Pentraxin ◽  
The Brain

NPTX2 (neuronal pentraxin-2) is a synaptic protein found abundantly in only two locations in a healthy human body: the brain and the pancreas, specifically islet of Langerhans cells. NPTX2’s role in the brain has been a focus of study in the pathology of Parkinson’s disease, as it is upregulated in PD patients. Its primary functions in the brain are to establish excitatory synapses and to recruit alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors to said synapses. These AMPA receptors signal for the neurotransmitter, glutamate, that regulates insulin secretion. This is of pathological significance to the onset of type 1 diabetes. Type 1 diabetes is characterized by the depletion of islet β-cells in the pancreas, which are responsible for insulin secretion. Without a supply of insulin, fatal consequences will ensue. NPTX2’s function in the pancreas is unstudied and extremely relevant to unraveling the complex processes that the body undergoes with the onset of this autoimmune disease. In recent mRNA studies, NPTX2 mRNA was significantly downregulated in type 1 diabetes. To understand the underlying cause of this downregulation and its potential role in the destruction of islet β-cells, it is first necessary to localize NPTX2 in the islet cells of type 1 diabetic, auto-antibody positive, and control donors. Immunofluorescent staining indicates that NPTX2’s co-expression in 

scholarly journals Perilipin2 down-regulation in β cells impairs insulin secretion under nutritional stress and damages mitochondria

2020 ◽  
Author(s):  
Akansha Mishra ◽  
Siming Liu ◽  
Joseph Promes ◽  
Mikako Harata ◽  
William Sivitz ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Function ◽  
Islet Cells ◽  
Cell Metabolism ◽  
Nutritional Stress ◽  
Β Cells ◽  
Β Cell ◽  
Down Regulation

Perilipin 2 (PLIN2) is the lipid droplet (LD) protein in β cells that increases under nutritional stress. Down-regulation of PLIN2 is often sufficient to reduce LD accumulation. To determine whether PLIN2 positively or negatively affects β cell function under nutritional stress, PLIN2 was down-regulated in mouse β cells, INS1 cells, and human islet cells. β cell specific deletion of PLIN2 in mice on a high fat diet reduced glucose-stimulated insulin secretion (GSIS) in vivo and in vitro. Down-regulation of PLIN2 in INS1 cells blunted GSIS after 24 h incubation with 0.2 mM palmitic acids. Down-regulation of PLIN2 in human pseudoislets cultured at 5.6 mM glucose impaired both phases of GSIS, indicating that PLIN2 is critical for GSIS. Down-regulation of PLIN2 decreased specific OXPHOS proteins in all three models and reduced oxygen consumption rates in INS1 cells and mouse islets. Moreover, we found that PLIN2 deficient INS1 cells increased the distribution of a fluorescent oleic acid analog to mitochondria and showed signs of mitochondrial stress as indicated by susceptibility to fragmentation and alterations of acyl-carnitines and glucose metabolites. Collectively, PLIN2 in β cells have an important role in preserving insulin secretion, β cell metabolism and mitochondrial function under nutritional stress.

scholarly journals Human stem cell model of HNF1A deficiency shows uncoupled insulin to C-peptide secretion with accumulation of abnormal insulin granules

2021 ◽  
Author(s):  
Bryan J. González ◽  
Haoquan Zhao ◽  
Jacqueline Niu ◽  
Damian J. Williams ◽  
Jaeyop Lee ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Insulin Secretion ◽  
Intracellular Calcium ◽  
Cell Fate ◽  
Endocrine Cells ◽  
Secretory Granules ◽  
Β Cells ◽  
C Peptide ◽  
Pancreatic Endocrine Cells

AbstractMutations in HNF1A cause Maturity Onset Diabetes of the Young type 3 (MODY3), the most prevalent form of monogenic diabetes. We generated stem cell-derived pancreatic endocrine cells from human embryonic stem cells (hESCs) with induced hypomorphic mutations in HNF1A. Using these cells, we show that HNF1A orchestrates a transcriptional program required for distinct aspects of β-cell fate and function. During islet cell differentiation, HNF1A deficiency biases islet endocrine cells towards an α-cell fate associated with PAX4 down-regulation. HNF1A- deficient β-cells display impaired basal and glucose stimulated-insulin secretion in association with a reduction in CACNA1A and intracellular calcium levels, and impaired insulin granule exocytosis in association with SYT13 down-regulation. Knockout of PAX4, CACNA1A and SYT13 reproduce the relevant phenotypes. Reduction of insulin secretion is associated with accumulation of enlarged secretory granules, and altered stoichiometry of secreted insulin to C-peptide. In HNF1A deficient β-cells, glibenclamide, a sulfonylurea drug used in the treatment of MODY3 patients, increases intracellular calcium to levels beyond those achieved by glucose, and restores C-peptide and insulin secretion to a normal stoichiometric ratio. To study HNF1A deficiency in the context of a human disease model, we also generated stem cell-derived pancreatic endocrine cells from two MODY3 patient’s induced pluripotent stem cells (iPSCs). While insulin secretion defects are constitutive in cells with complete HNF1A loss of function, β-cells heterozygous for hypomorphic HNF1A mutations are initially normal, but lose the ability to secrete insulin and acquire abnormal stoichiometric secretion ratios. Importantly, the defects observed in these stem cell models are also seen in circulating proportions of insulin:C-peptide in nine MODY3 patients.One sentence of summaryDeficiency of the transcription factor HNF1A biases islet endocrine cell fate towards α-cells, impairs intracellular calcium homeostasis and insulin exocytosis, alters the stoichiometry of insulin to C-peptide release, and leads to an accumulation of abnormal insulin secretory granules in β-cells.

scholarly journals The Cells of the Islets of Langerhans

2018 ◽  
Vol 7 (3) ◽  
pp. 54 ◽  
Author(s):  
Gabriela Da Silva Xavier
Keyword(s):  
Islets Of Langerhans ◽  
Islet Cell ◽  
Islet Cells ◽  
Cell Mass ◽  
Current Data ◽  
Treatment Modalities ◽  
Human Pancreas ◽  
Β Cells ◽  
Β Cell ◽  
Islet Mass

Islets of Langerhans are islands of endocrine cells scattered throughout the pancreas. A number of new studies have pointed to the potential for conversion of non-β islet cells in to insulin-producing β-cells to replenish β-cell mass as a means to treat diabetes. Understanding normal islet cell mass and function is important to help advance such treatment modalities: what should be the target islet/β-cell mass, does islet architecture matter to energy homeostasis, and what may happen if we lose a particular population of islet cells in favour of β-cells? These are all questions to which we will need answers for islet replacement therapy by transdifferentiation of non-β islet cells to be a reality in humans. We know a fair amount about the biology of β-cells but not quite as much about the other islet cell types. Until recently, we have not had a good grasp of islet mass and distribution in the human pancreas. In this review, we will look at current data on islet cells, focussing more on non-β cells, and on human pancreatic islet mass and distribution.

scholarly journals The Plasticity of Pancreatic β-Cells

Metabolites ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 218
Author(s):  
Norikiyo Honzawa ◽  
Kei Fujimoto
Keyword(s):  
Insulin Secretion ◽  
Progenitor Cells ◽  
Islet Cells ◽  
Cell Mass ◽  
Pancreatic Β Cell ◽  
Cell Plasticity ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Impaired Insulin

Type 2 diabetes is caused by impaired insulin secretion and/or insulin resistance. Loss of pancreatic β-cell mass detected in human diabetic patients has been considered to be a major cause of impaired insulin secretion. Additionally, apoptosis is found in pancreatic β-cells; β-cell mass loss is induced when cell death exceeds proliferation. Recently, however, β-cell dedifferentiation to pancreatic endocrine progenitor cells and β-cell transdifferentiation to α-cell was reported in human islets, which led to a new underlying molecular mechanism. Hyperglycemia inhibits nuclear translocation and expression of forkhead box-O1 (FoxO1) and induces the expression of neurogenin-3(Ngn3), which is required for the development and maintenance of pancreatic endocrine progenitor cells. This new hypothesis (Foxology) is attracting attention because it explains molecular mechanism(s) underlying β-cell plasticity. The lineage tracing technique revealed that the contribution of dedifferentiation is higher than that of β-cell apoptosis retaining to β-cell mass loss. In addition, islet cells transdifferentiate each other, such as transdifferentiation of pancreatic β-cell to α-cell and vice versa. Islet cells can exhibit plasticity, and they may have the ability to redifferentiate into any cell type. This review describes recent findings in the dedifferentiation and transdifferentiation of β-cells. We outline novel treatment(s) for diabetes targeting islet cell plasticity.

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