401
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Griesche N, Sanchez G, Hermans C, Idevall-Hagren O. Cortical mitochondria regulate insulin secretion by local Ca 2+ buffering in rodent beta cells. J Cell Sci 2019; 132:jcs.228544. [PMID: 30926624 DOI: 10.1242/jcs.228544] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 03/11/2019] [Indexed: 12/27/2022] Open
Abstract
Mitochondria play an essential role in regulating insulin secretion from beta cells by providing the ATP needed for the membrane depolarization that results in voltage-dependent Ca2+ influx and subsequent insulin granule exocytosis. Ca2+, in turn, is also rapidly taken up by the mitochondria and exerts important feedback regulation of metabolism. The aim of this study was to determine whether the distribution of mitochondria within beta cells is important for the secretory capacity of these cells. We find that cortically localized mitochondria are abundant in rodent beta cells, and that these mitochondria redistribute towards the cell interior following depolarization. The redistribution requires Ca2+-induced remodeling of the cortical F-actin network. Using light-regulated motor proteins, we increased the cortical density of mitochondria twofold and found that this blunted the voltage-dependent increase in cytosolic Ca2+ concentration and suppressed insulin secretion. The activity-dependent changes in mitochondria distribution are likely to be important for the generation of Ca2+ microdomains required for efficient insulin granule release.
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Affiliation(s)
- Nadine Griesche
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, 75123 Uppsala, Sweden
| | - Gonzalo Sanchez
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, 75123 Uppsala, Sweden
| | - Cedric Hermans
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, 75123 Uppsala, Sweden
| | - Olof Idevall-Hagren
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, 75123 Uppsala, Sweden
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402
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Calcium intake in high-risk pregnant women assisted in a high-complexity hospital. Mol Biol Rep 2019; 46:2851-2856. [PMID: 30847848 DOI: 10.1007/s11033-019-04731-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 02/28/2019] [Indexed: 02/07/2023]
Abstract
Pregnancy is characterized by physiological changes. One of these changes involves calcium. During this period, an increased in calcium excretion occurs as well as an increased intestinal absorption and renal reabsorption, so that the adequate growth and development of the fetus can happen. Low calcium intake is associated with chronic diseases, such as diabetes and hypertension, which have negative impact on both mother and fetus. This study aimed to evaluate the average calcium intake of high-risk pregnant women, assisted in a clinic of high complexity service and correlated with chronic diseases. To perform this study, it was used a food frequency questionnaire. As a result, high-risk pregnant women showed daily calcium intake lower than the recommended by DRI during this period. Hypertensive or diabetic pregnant women showed lower average intake of calcium. Significant association between calcium intake and nutritional status was not observed. Calcium supplementation was present, however, at low percentage in the groups with hypertensive pregnant women. To analyze the relation between calcium intake and the comorbidities, as well as calcium intake and the nutritional status of the pregnant women, it was used one-way analysis of variance and Bonferroni multiple comparison. Further studies are required for evaluating other parameters that justify the low calcium intake among this population group, and the definition of pathways for the management of the nutritional deficit considering the possible damage to maternal and neonatal health in the short and long term.
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403
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Pedersen MG, Tagliavini A, Henquin JC. Calcium signaling and secretory granule pool dynamics underlie biphasic insulin secretion and its amplification by glucose: experiments and modeling. Am J Physiol Endocrinol Metab 2019; 316:E475-E486. [PMID: 30620637 DOI: 10.1152/ajpendo.00380.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Glucose-stimulated insulin secretion from pancreatic β-cells is controlled by a triggering pathway that culminates in calcium influx and regulated exocytosis of secretory granules, and by a less understood amplifying pathway that augments calcium-induced exocytosis. In response to an abrupt increase in glucose concentration, insulin secretion exhibits a first peak followed by a lower sustained second phase. This biphasic secretion pattern is disturbed in diabetes. It has been attributed to depletion and subsequent refilling of a readily releasable pool of granules or to the phasic cytosolic calcium dynamics induced by glucose. Here, we apply mathematical modeling to experimental data from mouse islets to investigate how calcium and granule pool dynamics interact to control dynamic insulin secretion. Experimental calcium traces are used as inputs in three increasingly complex models of pool dynamics, which are fitted to insulin secretory patterns obtained using a set of protocols of glucose and tolbutamide stimulation. New calcium and secretion data for so-called staircase protocols, in which the glucose concentration is progressively increased, are presented. These data can be reproduced without assuming any heterogeneity in the model, in contrast to previous modeling, because of nontrivial calcium dynamics. We find that amplification by glucose can be explained by increased mobilization and priming of granules. Overall, our results indicate that calcium dynamics contribute substantially to shaping insulin secretion kinetics, which implies that better insight into the events creating phasic calcium changes in human β-cells is needed to understand the cellular mechanisms that disturb biphasic insulin secretion in diabetes.
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Affiliation(s)
- Morten Gram Pedersen
- Department of Information Engineering, University of Padova , Padova , Italy
- Department of Mathematics "Tullio Levi-Civita, " University of Padova , Padova , Italy
- Padova Neuroscience Center, University of Padova , Padova , Italy
| | - Alessia Tagliavini
- Department of Information Engineering, University of Padova , Padova , Italy
| | - Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain , Brussels , Belgium
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404
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Davey JS, Carmichael RE, Craig TJ. Protein SUMOylation regulates insulin secretion at multiple stages. Sci Rep 2019; 9:2895. [PMID: 30814610 PMCID: PMC6393506 DOI: 10.1038/s41598-019-39681-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 01/21/2019] [Indexed: 01/24/2023] Open
Abstract
Type-II Diabetes Mellitus (T2DM) is one of the fastest growing public health issues of modern times, consuming 12% of worldwide health budgets and affecting an estimated 400 million people. A key pathological trait associated with this disease is the failure of normal glucose-stimulated insulin secretion (GSIS) from pancreatic beta cells. Several lines of evidence suggest that vesicle trafficking events such as insulin secretion are regulated by the post-translational modification, SUMOylation, and indeed SUMOylation has been proposed to act as a ‘brake’ on insulin exocytosis. Here, we show that diabetic stimuli which inhibit GSIS are correlated with an increase in cellular protein SUMOylation, and that inhibition of deSUMOylation reduces GSIS. We demonstrate that manipulation of cellular protein SUMOylation levels, by overexpression of several different components of the SUMOylation pathway, have varied and complex effects on GSIS, indicating that SUMOylation regulates this process at multiple stages. We further demonstrate that inhibition of syntaxin1A SUMOylation, via a knockdown-rescue strategy, greatly enhances GSIS. Our data are therefore consistent with the model that SUMOylation acts as a brake on GSIS, and we have identified SUMOylation of syntaxin 1 A as a potential component of this brake. However, our data also demonstrate that the role of SUMOylation in GSIS is complex and may involve many substrates.
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Affiliation(s)
- Jeffrey S Davey
- Centre for Research in Biosciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK
| | - Ruth E Carmichael
- College of Life and Environmental Sciences, Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Tim J Craig
- Centre for Research in Biosciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK.
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405
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Henquin JC. Influence of organ donor attributes and preparation characteristics on the dynamics of insulin secretion in isolated human islets. Physiol Rep 2019. [PMID: 29536672 PMCID: PMC5849575 DOI: 10.14814/phy2.13646] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In vitro studies of human pancreatic islets are critical for understanding normal insulin secretion and its perturbations in diabetic β-cells, but the influence of islet preparation characteristics and organ donor attributes in such experiments is poorly documented. Preparations from normal donors were tested with a standardized protocol evaluating dynamic insulin secretion induced by glucose, tolbutamide, and cAMP (forskolin). Secretion rates, normalized to insulin content (fractional insulin secretion), were analyzed as a function of preparation and donor characteristics. Low purity (25-45%) of the preparation (n = 8) blunted the first phase of insulin secretion induced by glucose or tolbutamide and increased basal secretion, resulting in threefold lower stimulation index than in more pure (55-95%) preparations (n = 43). In these more pure preparations, cold ischemia time (1-13 h) before pancreas digestion did not impact insulin secretion. Islet size (estimated by the islet size index) did not influence the dynamics of secretion, but fractional insulin secretion rates were greater in large than small islets, and positively correlated with islet size. Age of the donors (20-68 years) had no influence on islet size and insulin content or on dynamics and amplitude of insulin secretion, which were also similar in islets from male and female donors. In contrast, islet size and islet insulin content (normalized for size), and basal or stimulated insulin secretion positively correlated with Body-Mass Index (19-33). These results contradict previous reports on the impact of donor age and islet size and point to possible confounding effects of donor BMI in insulin secretion studies with isolated human islets.
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Affiliation(s)
- Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium
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406
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Abstract
Despite considerable advances in the past few years, obesity and type 2 diabetes mellitus (T2DM) remain two major challenges for public health systems globally. In the past 9 years, genome-wide association studies (GWAS) have established a major role for genetic variation within the MTNR1B locus in regulating fasting plasma levels of glucose and in affecting the risk of T2DM. This discovery generated a major interest in the melatonergic system, in particular the melatonin MT2 receptor (which is encoded by MTNR1B). In this Review, we discuss the effect of melatonin and its receptors on glucose homeostasis, obesity and T2DM. Preclinical and clinical post-GWAS evidence of frequent and rare variants of the MTNR1B locus confirmed its importance in regulating glucose homeostasis and T2DM risk with minor effects on obesity. However, these studies did not solve the question of whether melatonin is beneficial or detrimental, an issue that will be discussed in the context of the peculiarities of the melatonergic system. Melatonin receptors might have therapeutic potential as they belong to the highly druggable G protein-coupled receptor superfamily. Clarifying the precise role of melatonin and its receptors on glucose homeostasis is urgent, as melatonin is widely used for other indications, either as a prescribed medication or as a supplement without medical prescription, in many countries in Europe and in the USA.
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Affiliation(s)
- Angeliki Karamitri
- Inserm, U1016, Institut Cochin, Paris, France
- CNRS UMR 8104, Paris, France
- Université Paris Descartes, Université Sorbonne Paris Cité, Paris, France
| | - Ralf Jockers
- Inserm, U1016, Institut Cochin, Paris, France.
- CNRS UMR 8104, Paris, France.
- Université Paris Descartes, Université Sorbonne Paris Cité, Paris, France.
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407
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Vergari E, Knudsen JG, Ramracheya R, Salehi A, Zhang Q, Adam J, Asterholm IW, Benrick A, Briant LJB, Chibalina MV, Gribble FM, Hamilton A, Hastoy B, Reimann F, Rorsman NJG, Spiliotis II, Tarasov A, Wu Y, Ashcroft FM, Rorsman P. Insulin inhibits glucagon release by SGLT2-induced stimulation of somatostatin secretion. Nat Commun 2019; 10:139. [PMID: 30635569 PMCID: PMC6329806 DOI: 10.1038/s41467-018-08193-8] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 12/18/2018] [Indexed: 02/08/2023] Open
Abstract
Hypoglycaemia (low plasma glucose) is a serious and potentially fatal complication of insulin-treated diabetes. In healthy individuals, hypoglycaemia triggers glucagon secretion, which restores normal plasma glucose levels by stimulation of hepatic glucose production. This counterregulatory mechanism is impaired in diabetes. Here we show in mice that therapeutic concentrations of insulin inhibit glucagon secretion by an indirect (paracrine) mechanism mediated by stimulation of intra-islet somatostatin release. Insulin’s capacity to inhibit glucagon secretion is lost following genetic ablation of insulin receptors in the somatostatin-secreting δ-cells, when insulin-induced somatostatin secretion is suppressed by dapagliflozin (an inhibitor of sodium-glucose co-tranporter-2; SGLT2) or when the action of secreted somatostatin is prevented by somatostatin receptor (SSTR) antagonists. Administration of these compounds in vivo antagonises insulin’s hypoglycaemic effect. We extend these data to isolated human islets. We propose that SSTR or SGLT2 antagonists should be considered as adjuncts to insulin in diabetes therapy. Impaired glucagon secretion in patients with diabetes causes hypoglycemia. Here the authors show that therapeutic concentrations of insulin inhibit alpha-cell glucagon secretion by stimulating delta-cell insulin receptor and the release of somatostatin. Blocking somatostatin secretion or action ameliorates this effect.
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Affiliation(s)
- Elisa Vergari
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Jakob G Knudsen
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Reshma Ramracheya
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Albert Salehi
- Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Box 430, Göteborg, SE40530, Sweden
| | - Quan Zhang
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Julie Adam
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Ingrid Wernstedt Asterholm
- Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Box 430, Göteborg, SE40530, Sweden
| | - Anna Benrick
- Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Box 430, Göteborg, SE40530, Sweden
| | - Linford J B Briant
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Margarita V Chibalina
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Fiona M Gribble
- Cambridge Institute of Metabolic Science and MRC Metabolic Diseases Unit, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK
| | - Alexander Hamilton
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Benoit Hastoy
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Frank Reimann
- Cambridge Institute of Metabolic Science and MRC Metabolic Diseases Unit, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, UK
| | - Nils J G Rorsman
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Ioannis I Spiliotis
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK.,Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Andrei Tarasov
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK.,Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Yanling Wu
- Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Box 430, Göteborg, SE40530, Sweden
| | - Frances M Ashcroft
- Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Box 430, Göteborg, SE40530, Sweden.,Department of Physiology, Anatomy and Genetics, Henry Wellcome Centre for Gene Function, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Patrik Rorsman
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LE, UK. .,Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Box 430, Göteborg, SE40530, Sweden. .,Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, OX3 7LE, UK.
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408
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Abstract
Type 2 diabetes is a progressive disorder, but exactly how the progression occurs remains unknown. In this issue of Cell Metabolism, Zhang et al. (2019) present evidence that diabetes, via hyperglycemia, leads to aberrant insertion of a mitochondrial ion channel in the plasma membrane, rendering it leaky to key intracellular signaling molecules with resultant suppression of insulin secretion.
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Affiliation(s)
- Jakob G Knudsen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK; Metabolic Physiology, Department of Physiology, University of Göteborg, Box 430, SE-405 30 Göteborg, Sweden.
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409
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Domínguez-Bendala J, Qadir MMF, Pastori RL. Pancreatic Progenitors: There and Back Again. Trends Endocrinol Metab 2019; 30:4-11. [PMID: 30502039 PMCID: PMC6354578 DOI: 10.1016/j.tem.2018.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 02/06/2023]
Abstract
Adult pancreatic regeneration is one of the most contentious topics in modern biology. The long-held view that the islets of Langerhans can be replenished throughout adult life through the reactivation of ductal progenitor cells has been replaced over the past decade by the now prevailing notion that regeneration does not involve progenitors and occurs only through the duplication of pre-existing mature cells. Here we dissect the limitations of lineage tracing (LT) to draw categorical conclusions about pancreatic regeneration, especially in view of emerging evidence that traditional lineages are less homogeneous and cell fates more dynamic than previously thought. This new evidence further suggests that the two competing hypotheses about regeneration are not mutually exclusive.
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Affiliation(s)
- Juan Domínguez-Bendala
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
| | - Mirza Muhammad Fahd Qadir
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Ricardo Luis Pastori
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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410
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Navarro-Tableros V, Gomez Y, Brizzi MF, Camussi G. Generation of Human Stem Cell-Derived Pancreatic Organoids (POs) for Regenerative Medicine. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1212:179-220. [PMID: 31025308 DOI: 10.1007/5584_2019_340] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin-dependent diabetes mellitus or type 1 diabetes mellitus (T1DM) is an auto-immune condition characterized by the loss of pancreatic β-cells. The curative approach for highly selected patients is the pancreas or the pancreatic islet transplantation. Nevertheless, these options are limited by a growing shortage of donor organs and by the requirement of immunosuppression.Xenotransplantation of porcine islets has been extensively investigated. Nevertheless, the strong xenoimmunity and the risk of transmission of porcine endogenous retroviruses, have limited their application in clinic. Generation of β-like cells from stem cells is one of the most promising strategies in regenerative medicine. Embryonic, and more recently, adult stem cells are currently the most promising cell sources exploited to generate functional β-cells in vitro. A number of studies demonstrated that stem cells could generate functional pancreatic organoids (POs), able to restore normoglycemia when implanted in different preclinical diabetic models. Nevertheless, a gradual loss of function and cell dead are commonly detected when POs are transplanted in immunocompetent animals. So far, the main issue to be solved is the post-transplanted islet loss, due to the host immune attack. To avoid this hurdle, nanotechnology has provided a number of polymers currently under investigation for islet micro and macro-encapsulation. These new approaches, besides conferring PO immune protection, are able to supply oxygen and nutrients and to preserve PO morphology and long-term viability.Herein, we summarize the current knowledge on bioengineered POs and the stem cell differentiation platforms. We also discuss the in vitro strategies used to generate functional POs, and the protocols currently used to confer immune-protection against the host immune attack (micro- and macro-encapsulation). In addition, the most relevant ongoing clinical trials, and the most relevant hurdles met to move towards clinical application are revised.
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Affiliation(s)
- Victor Navarro-Tableros
- 2i3T Società per la gestione dell'incubatore di imprese e per il trasferimento tecnologico Scarl, University of Turin, Turin, Italy
| | - Yonathan Gomez
- Department of Medical Sciences, University of Turin, Turin, Italy
| | | | - Giovanni Camussi
- Department of Medical Sciences, University of Turin, Turin, Italy.
- Fondazione per la Ricerca Biomedica-ONLUS, Turin, Italy.
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411
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Wong WKM, Sørensen AE, Joglekar MV, Hardikar AA, Dalgaard LT. Non-Coding RNA in Pancreas and β-Cell Development. Noncoding RNA 2018; 4:E41. [PMID: 30551650 PMCID: PMC6315983 DOI: 10.3390/ncrna4040041] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/10/2018] [Accepted: 12/11/2018] [Indexed: 12/17/2022] Open
Abstract
In this review, we provide an overview of the current knowledge on the role of different classes of non-coding RNAs for islet and β-cell development, maturation and function. MicroRNAs (miRNAs), a prominent class of small RNAs, have been investigated for more than two decades and patterns of the roles of different miRNAs in pancreatic fetal development, islet and β-cell maturation and function are now emerging. Specific miRNAs are dynamically regulated throughout the period of pancreas development, during islet and β-cell differentiation as well as in the perinatal period, where a burst of β-cell replication takes place. The role of long non-coding RNAs (lncRNA) in islet and β-cells is less investigated than for miRNAs, but knowledge is increasing rapidly. The advent of ultra-deep RNA sequencing has enabled the identification of highly islet- or β-cell-selective lncRNA transcripts expressed at low levels. Their roles in islet cells are currently only characterized for a few of these lncRNAs, and these are often associated with β-cell super-enhancers and regulate neighboring gene activity. Moreover, ncRNAs present in imprinted regions are involved in pancreas development and β-cell function. Altogether, these observations support significant and important actions of ncRNAs in β-cell development and function.
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Affiliation(s)
- Wilson K M Wong
- NHMRC Clinical Trials Center, University of Sydney, Camperdown NSW 2050, Sydney, Australia.
| | - Anja E Sørensen
- Department of Science and Environment, Roskilde University, DK-4000 Roskilde, Denmark.
| | - Mugdha V Joglekar
- NHMRC Clinical Trials Center, University of Sydney, Camperdown NSW 2050, Sydney, Australia.
| | - Anand A Hardikar
- NHMRC Clinical Trials Center, University of Sydney, Camperdown NSW 2050, Sydney, Australia.
| | - Louise T Dalgaard
- Department of Science and Environment, Roskilde University, DK-4000 Roskilde, Denmark.
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412
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Balboa D, Saarimäki-Vire J, Otonkoski T. Concise Review: Human Pluripotent Stem Cells for the Modeling of Pancreatic β-Cell Pathology. Stem Cells 2018; 37:33-41. [PMID: 30270471 PMCID: PMC7379656 DOI: 10.1002/stem.2913] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/21/2018] [Accepted: 08/28/2018] [Indexed: 12/11/2022]
Abstract
Pancreatic β‐cells are the only source of insulin. Disturbances in β‐cell development or function may thus result in insulin deficiency or excess, presenting as hyper‐ or hypoglycemia. It is increasingly evident that common forms of diabetes (types 1 and 2) are pathogenically heterogeneous. Development of efficient therapies is dependent on reliable disease models. Although animal models are remarkably useful research tools, they present limitations because of species differences. As an alternative, human pluripotent stem cell technologies offer multiple possibilities for the study of human diseases in vitro. In the last decade, advances in the derivation of induced pluripotent stem cells from diabetic patients, combined with β‐cell differentiation protocols, have resulted in the generation of useful disease models for diabetes. First disease models have been focusing on monogenic diabetes. The development of genome editing technologies, more advanced differentiation protocols and humanized mouse models based on transplanted cells have opened new horizons for the modeling of more complex forms of β‐cell dysfunction. We present here the incremental progress made in the modeling of diabetes using pluripotent stem cells. We discuss the current challenges and opportunities of these approaches to dissect β‐cell pathology and devise new pharmacological and cell replacement therapies. stem cells2019;37:33–41
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Affiliation(s)
- Diego Balboa
- Research Programs Unit, Molecular Neurology, Biomedicum Stem Cell Centre, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jonna Saarimäki-Vire
- Research Programs Unit, Molecular Neurology, Biomedicum Stem Cell Centre, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Timo Otonkoski
- Research Programs Unit, Molecular Neurology, Biomedicum Stem Cell Centre, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Children's Hospital, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland
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413
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Frank JA, Broichhagen J, Yushchenko DA, Trauner D, Schultz C, Hodson DJ. Optical tools for understanding the complexity of β-cell signalling and insulin release. Nat Rev Endocrinol 2018; 14:721-737. [PMID: 30356209 DOI: 10.1038/s41574-018-0105-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Following stimulation, pancreatic β-cells must orchestrate a plethora of signalling events to ensure the appropriate release of insulin and maintenance of normal glucose homeostasis. Failure at any point in this cascade leads to impaired insulin secretion, elevated blood levels of glucose and eventually type 2 diabetes mellitus. Likewise, β-cell replacement or regeneration strategies for the treatment of both type 1 and type 2 diabetes mellitus might fail if the correct cell signalling phenotype cannot be faithfully recreated. However, current understanding of β-cell function is complicated because of the highly dynamic nature of their intracellular and intercellular signalling as well as insulin release itself. β-Cells must precisely integrate multiple signals stemming from multiple cues, often with differing intensities, frequencies and cellular and subcellular localizations, before converging these signals onto insulin exocytosis. In this respect, optical approaches with high resolution in space and time are extremely useful for properly deciphering the complexity of β-cell signalling. An increased understanding of β-cell signalling might identify new mechanisms underlying insulin release, with relevance for future drug therapy and de novo stem cell engineering of functional islets.
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Affiliation(s)
- James A Frank
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Johannes Broichhagen
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Dmytro A Yushchenko
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Dirk Trauner
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Chemistry, New York University, New York, NY, USA
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Heidelberg, Germany.
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA.
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK.
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK.
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414
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Hastoy B, Godazgar M, Clark A, Nylander V, Spiliotis I, van de Bunt M, Chibalina MV, Barrett A, Burrows C, Tarasov AI, Scharfmann R, Gloyn AL, Rorsman P. Electrophysiological properties of human beta-cell lines EndoC-βH1 and -βH2 conform with human beta-cells. Sci Rep 2018; 8:16994. [PMID: 30451893 PMCID: PMC6242937 DOI: 10.1038/s41598-018-34743-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/19/2018] [Indexed: 12/30/2022] Open
Abstract
Limited access to human islets has prompted the development of human beta cell models. The human beta cell lines EndoC-βH1 and EndoC-βH2 are increasingly used by the research community. However, little is known of their electrophysiological and secretory properties. Here, we monitored parameters that constitute the glucose-triggering pathway of insulin release. Both cell lines respond to glucose (6 and 20 mM) with 2- to 3-fold stimulation of insulin secretion which correlated with an elevation of [Ca2+]i, membrane depolarisation and increased action potential firing. Similar to human primary beta cells, KATP channel activity is low at 1 mM glucose and is further reduced upon increasing glucose concentration; an effect that was mimicked by the KATP channel blocker tolbutamide. The upstroke of the action potentials reflects the activation of Ca2+ channels with some small contribution of TTX-sensitive Na+ channels. The repolarisation involves activation of voltage-gated Kv2.2 channels and large-conductance Ca2+-activated K+ channels. Exocytosis presented a similar kinetics to human primary beta cells. The ultrastructure of these cells shows insulin vesicles composed of an electron-dense core surrounded by a thin clear halo. We conclude that the EndoC-βH1 and -βH2 cells share many features of primary human β-cells and thus represent a useful experimental model.
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Affiliation(s)
- Benoît Hastoy
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Mahdieh Godazgar
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Anne Clark
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Vibe Nylander
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Ioannis Spiliotis
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Martijn van de Bunt
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 1936 8948grid.4991.5Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Margarita V. Chibalina
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Amy Barrett
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Carla Burrows
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Andrei I. Tarasov
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Raphael Scharfmann
- 0000 0001 2188 0914grid.10992.33INSERM U1016, Cochin Institute, Université Paris Descartes, Paris, France
| | - Anna L. Gloyn
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 1936 8948grid.4991.5Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 0488 9484grid.415719.fNational Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Oxford, United Kingdom
| | - Patrik Rorsman
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 0488 9484grid.415719.fNational Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Oxford, United Kingdom ,0000 0000 9919 9582grid.8761.8Department of Physiology, Institute of Neuroscience and Physiology, University of Goteborg, Goteborg, Sweden
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415
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Sulis PM, Dambrós BF, Mascarello A, dos Santos ARS, Yunes RA, Nunes RJ, Frederico MJS, Barreto Silva FRM. Sulfonyl(thio)urea derivative induction of insulin secretion is mediated by potassium, calcium, and sodium channel signal transduction. J Cell Physiol 2018; 234:10138-10147. [DOI: 10.1002/jcp.27680] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 10/08/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Paola Miranda Sulis
- Departamento de Bioquímica, Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
| | - Betina Fernanda Dambrós
- Departamento de Bioquímica, Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
| | - Alessandra Mascarello
- Departamento de Química, Centro de Ciências Físicas e Matemáticas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
| | - Adair Roberto Soares dos Santos
- Departamento de Ciências Fisiológicas, Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
| | - Rosendo Augusto Yunes
- Departamento de Química, Centro de Ciências Físicas e Matemáticas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
| | - Ricardo José Nunes
- Departamento de Química, Centro de Ciências Físicas e Matemáticas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
| | - Marisa Jádna Silva Frederico
- Departamento de Bioquímica, Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
| | - Fátima Regina Mena Barreto Silva
- Departamento de Bioquímica, Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Campus Universitário Florianópolis Brazil
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416
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Karatekin E. Toward a unified picture of the exocytotic fusion pore. FEBS Lett 2018; 592:3563-3585. [PMID: 30317539 PMCID: PMC6353554 DOI: 10.1002/1873-3468.13270] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/30/2018] [Accepted: 10/10/2018] [Indexed: 11/07/2022]
Abstract
Neurotransmitter and hormone release involve calcium-triggered fusion of a cargo-loaded vesicle with the plasma membrane. The initial connection between the fusing membranes, called the fusion pore, can evolve in various ways, including rapid dilation to allow full cargo release, slow expansion, repeated opening-closing and resealing. Pore dynamics determine the kinetics of cargo release and the mode of vesicle recycling, but how these processes are controlled is poorly understood. Previous reconstitutions could not monitor single pores, limiting mechanistic insight they could provide. Recently developed nanodisc-based fusion assays allow reconstitution and monitoring of single pores with unprecedented detail and hold great promise for future discoveries. They recapitulate various aspects of exocytotic fusion pores, but comparison is difficult because different approaches suggested very different exocytotic fusion pore properties, even for the same cell type. In this Review, I discuss how most of the data can be reconciled, by recognizing how different methods probe different aspects of the same fusion process. The resulting picture is that fusion pores have broadly distributed properties arising from stochastic processes which can be modulated by physical constraints imposed by proteins, lipids and membranes.
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Affiliation(s)
- Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
- Centre National de la Recherche Scientifique (CNRS), Paris, France
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417
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Vedovato N, Rorsman O, Hennis K, Ashcroft FM, Proks P. Role of the C-terminus of SUR in the differential regulation of β-cell and cardiac K ATP channels by MgADP and metabolism. J Physiol 2018; 596:6205-6217. [PMID: 30179258 PMCID: PMC6292810 DOI: 10.1113/jp276708] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Abstract
Key points β‐Cell KATP channels are partially open in the absence of metabolic substrates, whereas cardiac KATP channels are closed. Using cloned channels heterologously expressed in Xenopus oocytes we measured the effect of MgADP on the MgATP concentration–inhibition curve immediately after patch excision. MgADP caused a far more striking reduction in ATP inhibition of Kir6.2/SUR1 channels than Kir6.2/SUR2A channels; this effect declined rapidly after patch excision. Exchanging the final 42 amino acids of SUR was sufficient to switch the Mg‐nucleotide regulation of Kir6.2/SUR1 and Kir6.2/SUR2A channels, and partially switch their sensitivity to metabolic inhibition. Deletion of the C‐terminal 42 residues of SUR abolished MgADP activation of both Kir6.2/SUR1 and Kir6.2/SUR2A channels. We conclude that the different metabolic sensitivity of Kir6.2/SUR1 and Kir6.2/SUR2A channels is at least partially due to their different regulation by Mg‐nucleotides, which is determined by the final 42 amino acids.
Abstract ATP‐sensitive potassium (KATP) channels couple the metabolic state of a cell to its electrical activity and play important physiological roles in many tissues. In contrast to β‐cell (Kir6.2/SUR1) channels, which open when extracellular glucose levels fall, cardiac (Kir6.2/SUR2A) channels remain closed. This is due to differences in the SUR subunit rather than cell metabolism. As ATP inhibition and MgADP activation are similar for both types of channels, we investigated channel inhibition by MgATP in the presence of 100 μm MgADP immediately after patch excision [when the channel open probability (PO) is near maximal]. The results were strikingly different: 100 μm MgADP substantially reduced MgATP inhibition of Kir6.2/SUR1, but had no effect on MgATP inhibition of Kir6.2/SUR2A. Exchanging the final 42 residues of SUR2A with that of SUR1 switched the channel phenotype (and vice versa), and deleting this region abolished Mg‐nucleotide activation. This suggests the C‐terminal 42 residues are important for the ability of MgADP to influence ATP inhibition at Kir6.2. This region was also necessary, but not sufficient, for activation of the KATP channel in intact cells by metabolic inhibition (azide). We conclude that the ability of MgADP to impair ATP inhibition at Kir6.2 accounts, in part, for the differential metabolic sensitivities of β‐cell and cardiac KATP channels. β‐Cell KATP channels are partially open in the absence of metabolic substrates, whereas cardiac KATP channels are closed. Using cloned channels heterologously expressed in Xenopus oocytes we measured the effect of MgADP on the MgATP concentration–inhibition curve immediately after patch excision. MgADP caused a far more striking reduction in ATP inhibition of Kir6.2/SUR1 channels than Kir6.2/SUR2A channels; this effect declined rapidly after patch excision. Exchanging the final 42 amino acids of SUR was sufficient to switch the Mg‐nucleotide regulation of Kir6.2/SUR1 and Kir6.2/SUR2A channels, and partially switch their sensitivity to metabolic inhibition. Deletion of the C‐terminal 42 residues of SUR abolished MgADP activation of both Kir6.2/SUR1 and Kir6.2/SUR2A channels. We conclude that the different metabolic sensitivity of Kir6.2/SUR1 and Kir6.2/SUR2A channels is at least partially due to their different regulation by Mg‐nucleotides, which is determined by the final 42 amino acids.
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Affiliation(s)
- Natascia Vedovato
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Olof Rorsman
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Konstantin Hennis
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Frances M Ashcroft
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Peter Proks
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
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418
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Ceasrine AM, Lin EE, Lumelsky DN, Iyer R, Kuruvilla R. Adrb2 controls glucose homeostasis by developmental regulation of pancreatic islet vasculature. eLife 2018; 7:39689. [PMID: 30303066 PMCID: PMC6200393 DOI: 10.7554/elife.39689] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/07/2018] [Indexed: 12/12/2022] Open
Abstract
A better understanding of processes controlling the development and function of pancreatic islets is critical for diabetes prevention and treatment. Here, we reveal a previously unappreciated function for pancreatic β2-adrenergic receptors (Adrb2) in controlling glucose homeostasis by restricting islet vascular growth during development. Pancreas-specific deletion of Adrb2 results in glucose intolerance and impaired insulin secretion in mice, and unexpectedly, specifically in females. The metabolic phenotypes were recapitulated by Adrb2 deletion from neonatal, but not adult, β-cells. Mechanistically, Adrb2 loss increases production of Vascular Endothelial Growth Factor-A (VEGF-A) in female neonatal β-cells and results in hyper-vascularized islets during development, which in turn, disrupts insulin production and exocytosis. Neonatal correction of islet hyper-vascularization, via VEGF-A receptor blockade, fully rescues functional deficits in glucose homeostasis in adult mutant mice. These findings uncover a regulatory pathway that functions in a sex-specific manner to control glucose metabolism by restraining excessive vascular growth during islet development.
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Affiliation(s)
- Alexis M Ceasrine
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - Eugene E Lin
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - David N Lumelsky
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - Radhika Iyer
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - Rejji Kuruvilla
- Department of Biology, Johns Hopkins University, Baltimore, United States
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419
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420
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Abstract
PURPOSE OF REVIEW To discuss advances in our understanding of beta-cell heterogeneity and the ramifications of this for type 1 diabetes (T1D) and its therapy. RECENT FINDINGS A number of studies have challenged the long-standing dogma that the majority of beta cells are eliminated in T1D. As many as 80% are present in some T1D subjects. Why don't these cells function properly to release insulin in response to high glucose? Other findings deploying single-cell "omics" to study both healthy and diseased cells-from patients with both T1D and type 2 diabetes (T2D)-have revealed cell subpopulations and heterogeneity at the transcriptomic/protein level between individual cells. Finally, our own and others' findings have demonstrated the importance of functional beta-cell subpopulations for insulin secretion. Heterogeneity may endow beta cells with molecular features that predispose them to failure/death during T1D.
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Affiliation(s)
- Richard K. P. Benninger
- 0000 0001 0703 675Xgrid.430503.1Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
- 0000 0001 0703 675Xgrid.430503.1Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Craig Dorrell
- 0000 0000 9758 5690grid.5288.7Oregon Stem Cell Center, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239 USA
| | - David J. Hodson
- 0000 0004 1936 7486grid.6572.6Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, B15 2TT UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TH UK
- COMPARE, University of Birmingham and University of Nottingham Midlands, Nottingham, UK
| | - Guy A. Rutter
- 0000 0001 2113 8111grid.7445.2Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, London, W12 0NN UK
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421
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Ribeiro RA, Bonfleur ML, Batista TM, Borck PC, Carneiro EM. Regulation of glucose and lipid metabolism by the pancreatic and extra-pancreatic actions of taurine. Amino Acids 2018; 50:1511-1524. [PMID: 30206707 DOI: 10.1007/s00726-018-2650-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 09/04/2018] [Indexed: 12/17/2022]
Abstract
The beneficial actions of L-taurine (Tau) against glucose intolerance, obesity, type 2 diabetes (T2D), and non-alcoholic fat liver disease (NAFLD) have been linked to its antioxidant and anti-inflammatory effects, which ameliorate tissue insulin sensitivity. Importantly, there are several lines of evidence that indicate a direct action of Tau on the endocrine pancreas to regulate the secretion and paracrine actions of insulin, glucagon, and somatostatin. Furthermore, Tau can also ameliorate glucose metabolism through the enhancement of insulin signaling. However, some of the benefits of Tau upon intermediary metabolism may manifest via considerable antagonism of the action of insulin. Therefore, this review discusses the mechanisms of action by which Tau may regulate endocrine pancreatic morphofunction, and glucose and lipid homeostasis.
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Affiliation(s)
- Rosane A Ribeiro
- NUPEM, Universidade Federal do Rio de Janeiro, Campus UFRJ-Macaé, Avenida São José do Barreto, 764, Macaé, RJ, CEP: 27965-045, Brazil.
| | - Maria L Bonfleur
- Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná (UNIOESTE), Cascavel, PR, Brazil
| | - Thiago M Batista
- Departamento de Biologia Estrutural e Funcional, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Patricia C Borck
- Departamento de Biologia Estrutural e Funcional, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Everardo M Carneiro
- Departamento de Biologia Estrutural e Funcional, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil
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422
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Tarasov AI, Galvanovskis J, Rorsman O, Hamilton A, Vergari E, Johnson PRV, Reimann F, Ashcroft FM, Rorsman P. Monitoring real-time hormone release kinetics via high-content 3-D imaging of compensatory endocytosis. LAB ON A CHIP 2018; 18:2838-2848. [PMID: 30083680 PMCID: PMC6250124 DOI: 10.1039/c8lc00417j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 07/26/2018] [Indexed: 05/02/2023]
Abstract
High-content real-time imaging of hormone secretion in tissues or cell populations is a challenging task, which is unlikely to be resolved directly, despite immense translational value. We approach this problem indirectly, using compensatory endocytosis, a process that closely follows exocytosis in the cell, as a surrogate read-out for secretion. The tissue is immobilized in an open-air perifusion chamber and imaged using a two-photon microscope. A fluorescent polar tracer, perifused through the experimental circuit, gets trapped into the cells via endocytosis, and is quantified using a feature-detection algorithm. The signal of the tracer that accumulates into the endocytotic system reliably reflects stimulated exocytosis, which is demonstrated via co-imaging of the latter using existing reporters. A high signal-to-noise ratio and compatibility with multisensor imaging affords the real-time quantification of the secretion at the tissue/population level, whereas the cumulative nature of the signal allows imprinting of the "secretory history" within each cell. The technology works for several cell types, reflects disease progression and can be used for human tissue.
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Affiliation(s)
- Andrei I Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, OX3 7LE, Oxford, UK. and Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford OX3 7LE, UK
| | - Juris Galvanovskis
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, OX3 7LE, Oxford, UK.
| | - Olof Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, OX3 7LE, Oxford, UK.
| | - Alexander Hamilton
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, OX3 7LE, Oxford, UK.
| | - Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, OX3 7LE, Oxford, UK.
| | - Paul R V Johnson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, OX3 7LE, Oxford, UK.
| | - Frank Reimann
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, CB2 0QQ UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks road, Oxford, OX1 3PT, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, OX3 7LE, Oxford, UK. and Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford OX3 7LE, UK and Institute of Neuroscience of Physiology, Department of Physiology, Metabolic Research Unit, University of Göteborg, Box 430, SE-405 30 Göteborg, Sweden
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423
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Esguerra JLS, Nagao M, Ofori JK, Wendt A, Eliasson L. MicroRNAs in islet hormone secretion. Diabetes Obes Metab 2018; 20 Suppl 2:11-19. [PMID: 30230181 DOI: 10.1111/dom.13382] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/10/2018] [Accepted: 05/23/2018] [Indexed: 12/12/2022]
Abstract
Pancreatic islet hormone secretion is central in the maintenance of blood glucose homeostasis. During development of hyperglycaemia, the β-cell is under pressure to release more insulin to compensate for increased insulin resistance. Failure of the β-cells to secrete enough insulin results in type 2 diabetes (T2D). MicroRNAs (miRNAs) are short non-coding RNA molecules suitable for rapid regulation of the changes in target gene expression needed in β-cell adaptations. Moreover, miRNAs are involved in the maintenance of α-cell and β-cell phenotypic identities via cell-specific, or cell-enriched expression. Although many of the abundant miRNAs are highly expressed in both cell types, recent research has focused on the role of miRNAs in β-cells. It has been shown that highly abundant miRNAs, such as miR-375, are involved in several cellular functions indispensable in maintaining β-cell phenotypic identity, almost acting as "housekeeping genes" in the context of hormone secretion. Despite the abundance and importance of miR-375, it has not been shown to be differentially expressed in T2D islets. On the contrary, the less abundant miRNAs such as miR-212/miR-132, miR-335, miR-130a/b and miR-152 are deregulated in T2D islets, wherein the latter three miRNAs were shown to play key roles in regulating β-cell metabolism. In this review, we focus on β-cell function and describe miRNAs involved in insulin biosynthesis and processing, glucose uptake and metabolism, electrical activity and Ca2+ -influx and exocytosis of the insulin granules. We present current status on miRNA regulation in α-cells, and finally we discuss the involvement of miRNAs in β-cell dysfunction underlying T2D pathogenesis.
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Affiliation(s)
- Jonathan L S Esguerra
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Mototsugu Nagao
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Jones K Ofori
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Anna Wendt
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Lena Eliasson
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
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424
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Ramracheya R, Chapman C, Chibalina M, Dou H, Miranda C, González A, Moritoh Y, Shigeto M, Zhang Q, Braun M, Clark A, Johnson PR, Rorsman P, Briant LJB. GLP-1 suppresses glucagon secretion in human pancreatic alpha-cells by inhibition of P/Q-type Ca 2+ channels. Physiol Rep 2018; 6:e13852. [PMID: 30187652 PMCID: PMC6125244 DOI: 10.14814/phy2.13852] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/31/2018] [Accepted: 08/07/2018] [Indexed: 01/13/2023] Open
Abstract
Glucagon is the body's main hyperglycemic hormone, and its secretion is dysregulated in type 2 diabetes mellitus (T2DM). The incretin hormone glucagon-like peptide-1 (GLP-1) is released from the gut and is used in T2DM therapy. Uniquely, it both stimulates insulin and inhibits glucagon secretion and thereby lowers plasma glucose levels. In this study, we have investigated the action of GLP-1 on glucagon release from human pancreatic islets. Immunocytochemistry revealed that only <0.5% of the α-cells possess detectable GLP-1R immunoreactivity. Despite this, GLP-1 inhibited glucagon secretion by 50-70%. This was due to a direct effect on α-cells, rather than paracrine signaling, because the inhibition was not reversed by the insulin receptor antagonist S961 or the somatostatin receptor-2 antagonist CYN154806. The inhibitory effect of GLP-1 on glucagon secretion was prevented by the PKA-inhibitor Rp-cAMPS and mimicked by the adenylate cyclase activator forskolin. Electrophysiological measurements revealed that GLP-1 decreased action potential height and depolarized interspike membrane potential. Mathematical modeling suggests both effects could result from inhibition of P/Q-type Ca2+ channels. In agreement with this, GLP-1 and ω-agatoxin (a blocker of P/Q-type channels) inhibited glucagon secretion in islets depolarized by 70 mmol/L [K+ ]o , and these effects were not additive. Intracellular application of cAMP inhibited depolarization-evoked exocytosis in individual α-cells by a PKA-dependent (Rp-cAMPS-sensitive) mechanism. We propose that inhibition of glucagon secretion by GLP-1 involves activation of the few GLP-1 receptors present in the α-cell membrane. The resulting small elevation of cAMP leads to PKA-dependent inhibition of P/Q-type Ca2+ channels and suppression of glucagon exocytosis.
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Affiliation(s)
- Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Caroline Chapman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Margarita Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Haiqiang Dou
- Institute of Neuroscience and PhysiologyMetabolic Research UnitUniversity of GöteborgGöteborgSweden
| | - Caroline Miranda
- Institute of Neuroscience and PhysiologyMetabolic Research UnitUniversity of GöteborgGöteborgSweden
| | - Alejandro González
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Yusuke Moritoh
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Makoto Shigeto
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Matthias Braun
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Paul R. Johnson
- Nuffield Department of SurgeryUniversity of OxfordJohn Radcliffe HospitalOxfordUnited Kingdom
- NIHR Oxford Biomedical Research CentreOxfordUnited Kingdom
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
- Institute of Neuroscience and PhysiologyMetabolic Research UnitUniversity of GöteborgGöteborgSweden
- NIHR Oxford Biomedical Research CentreOxfordUnited Kingdom
| | - Linford J. B. Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
- Department of Computer ScienceUniversity of OxfordOxfordUnited Kingdom
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425
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Wendt A, Esguerra JL, Eliasson L. Islet microRNAs in health and type-2 diabetes. Curr Opin Pharmacol 2018; 43:46-52. [PMID: 30144686 DOI: 10.1016/j.coph.2018.08.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/02/2018] [Indexed: 12/24/2022]
Abstract
Failure of the β-cell to secrete enough insulin is a major contributing factor in the pathogenesis of type-2 diabetes (T2D). MicroRNAs provide an extra layer in the regulation of protein expression, and are thus involved in β-cell compensation during development of the disease. In this review, we discuss how microRNAs can regulate their target protein expression and phenotypic output, present the status of nutritional regulation of microRNA expression, and summarize work on microRNA expression in human islets. In conclusion, current data lend support to microRNAs being essential regulators of insulin secretion. Future work will describe microRNAs in α-cell function, details of the microRNA-mRNA network, and possibilities to use microRNAs as biomarkers and in therapeutic treatment of T2D and complications.
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Affiliation(s)
- Anna Wendt
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University and Clinical Research Centre, SUS, Malmö, Sweden
| | - Jonathan Ls Esguerra
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University and Clinical Research Centre, SUS, Malmö, Sweden
| | - Lena Eliasson
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University and Clinical Research Centre, SUS, Malmö, Sweden.
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426
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Fehrentz T, Huber FME, Hartrampf N, Bruegmann T, Frank JA, Fine NHF, Malan D, Danzl JG, Tikhonov DB, Sumser M, Sasse P, Hodson DJ, Zhorov BS, Klöcker N, Trauner D. Optical control of L-type Ca 2+ channels using a diltiazem photoswitch. Nat Chem Biol 2018; 14:764-767. [PMID: 30013061 DOI: 10.1038/s41589-018-0090-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 05/21/2018] [Indexed: 01/21/2023]
Abstract
L-type Ca2+ channels (LTCCs) play a crucial role in excitation-contraction coupling and release of hormones from secretory cells. They are targets of antihypertensive and antiarrhythmic drugs such as diltiazem. Here, we present a photoswitchable diltiazem, FHU-779, which can be used to reversibly block endogenous LTCCs by light. FHU-779 is as potent as diltiazem and can be used to place pancreatic β-cell function and cardiac activity under optical control.
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Affiliation(s)
- Timm Fehrentz
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany.
| | - Florian M E Huber
- Department of Chemistry, University of Munich and Center for Integrated Protein Science (CIPSM), Munich, Germany.,Roche Diagnostics GmbH, DXRERA, Penzberg, Germany
| | - Nina Hartrampf
- Department of Chemistry, University of Munich and Center for Integrated Protein Science (CIPSM), Munich, Germany
| | - Tobias Bruegmann
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany.,Research Training Group 1873, University of Bonn, Bonn, Germany
| | - James A Frank
- Department of Chemistry, University of Munich and Center for Integrated Protein Science (CIPSM), Munich, Germany.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Nicholas H F Fine
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Daniela Malan
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Johann G Danzl
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Denis B Tikhonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Martin Sumser
- Department of Chemistry, University of Munich and Center for Integrated Protein Science (CIPSM), Munich, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Boris S Zhorov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.,Institute of Molecular Biology and Genetics, Almazov Federal Heart, Blood and Endocrinology Centre, St. Petersburg, Russia.,Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany.
| | - Dirk Trauner
- Department of Chemistry, University of Munich and Center for Integrated Protein Science (CIPSM), Munich, Germany. .,Department of Chemistry and Neuroscience Institute, New York University, New York, NY, USA.
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427
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Abstract
The somatostatin-secreting δ-cells comprise ~5% of the cells of the pancreatic islets. The δ-cells have complex morphology and might interact with many more islet cells than suggested by their low numbers. δ-Cells contain ATP-sensitive potassium channels, which open at low levels of glucose but close when glucose is elevated. This closure initiates membrane depolarization and electrical activity and increased somatostatin secretion. Factors released by neighbouring α-cells or β-cells amplify the glucose-induced effects on somatostatin secretion from δ-cells, which act locally within the islets as paracrine or autocrine inhibitors of insulin, glucagon and somatostatin secretion. The effects of somatostatin are mediated by activation of somatostatin receptors coupled to the inhibitory G protein, which culminates in suppression of the electrical activity and exocytosis in α-cells and β-cells. Somatostatin secretion is perturbed in animal models of diabetes mellitus, which might explain the loss of appropriate hypoglycaemia-induced glucagon secretion, a defect that could be mitigated by somatostatin receptor 2 antagonists. Somatostatin antagonists or agents that suppress somatostatin secretion have been proposed as an adjunct to insulin therapy. In this Review, we summarize the cell physiology of somatostatin secretion, what might go wrong in diabetes mellitus and the therapeutic potential of agents targeting somatostatin secretion or action.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, University of Oxford, Oxford, UK.
- Department of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.
| | - Mark O Huising
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, USA
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428
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Paschen M, Moede T, Valladolid-Acebes I, Leibiger B, Moruzzi N, Jacob S, García-Prieto CF, Brismar K, Leibiger IB, Berggren PO. Diet-induced β-cell insulin resistance results in reversible loss of functional β-cell mass. FASEB J 2018; 33:204-218. [PMID: 29957055 PMCID: PMC6355083 DOI: 10.1096/fj.201800826r] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although convincing in genetic models, the relevance of β-cell insulin resistance in diet-induced type 2 diabetes (T2DM) remains unclear. Exemplified by diabetes-prone, male, C57B1/6J mice being fed different combinations of Western-style diet, we show that β-cell insulin resistance occurs early during T2DM progression and is due to a combination of lipotoxicity and increased β-cell workload. Within 8 wk of being fed a high-fat, high-sucrose diet, mice became obese, developed impaired insulin and glucose tolerances, and displayed noncompensatory insulin release, due, at least in part, to reduced expression of syntaxin-1A. Through reporter islets transplanted to the anterior chamber of the eye, we demonstrated a concomitant loss of functional β-cell mass. When mice were changed from diabetogenic diet to normal chow diet, the diabetes phenotype was reversed, suggesting a remarkable plasticity of functional β-cell mass in the early phase of T2DM development. Our data reinforce the relevance of diet composition as an environmental factor determining different routes of diabetes progression in a given genetic background. Employing the in vivo reporter islet–monitoring approach will allow researchers to define key times in the dynamics of reversible loss of functional β-cell mass and, thus, to investigate the underlying, molecular mechanisms involved in the progression toward T2DM manifestation.—Paschen, M., Moede, T., Valladolid-Acebes, I., Leibiger, B., Moruzzi, N., Jacob, S., García-Prieto, C. F., Brismar, K., Leibiger, I. B., Berggren, P.-O. Diet-induced β-cell insulin resistance results in reversible loss of functional β-cell mass.
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Affiliation(s)
- Meike Paschen
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Tilo Moede
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Ismael Valladolid-Acebes
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Noah Moruzzi
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Stefan Jacob
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Concha F García-Prieto
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Kerstin Brismar
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
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429
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Perrier R, Pirog A, Jaffredo M, Gaitan J, Catargi B, Renaud S, Raoux M, Lang J. Bioelectronic organ-based sensor for microfluidic real-time analysis of the demand in insulin. Biosens Bioelectron 2018; 117:253-259. [PMID: 29909196 DOI: 10.1016/j.bios.2018.06.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/04/2018] [Accepted: 06/06/2018] [Indexed: 12/31/2022]
Abstract
On-line and real-time analysis of micro-organ activity permits to use the endogenous analytical power of cellular signal transduction algorithms as biosensors. We have developed here such a sensor using only a few pancreatic endocrine islets and the avoidance of transgenes or chemical probes reduces bias and procures general usage. Nutrient and hormone-induced changes in islet ion fluxes through channels provide the first integrative read-out of micro-organ activity. Using extracellular electrodes we captured this read-out non-invasively as slow potentials which reflect glucose concentration-dependent (3-15 mM) micro-organ activation and coupling. Custom-made PDMS-based microfluidics with platinum black micro-electrode arrays required only some tens of islets and functioned at flow rates of 1-10 µl/min which are compatible with microdialysis. We developed hardware solutions for on-line real-time analysis on a reconfigurable Field-Programmable Gate Array (FPGA) that offered resource-efficient architecture and storage of intermediary processing stages. Moreover, real-time adaptive and reconfigurable algorithms accounted for signal disparities and noise distribution. Based on islet slow potentials, this integrated set-up allowed within less than 40 μs the discrimination and precise automatic ranking of small increases (2 mM steps) of glucose concentrations in real time and within the physiological glucose range. This approach shall permit further development in continuous monitoring of the demand for insulin in type 1 diabetes as well as monitoring of organs-on-chip or maturation of stem-cell derived islets.
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Affiliation(s)
- R Perrier
- Laboratoire de Chimie et Biologie des Membranes et des Nano-Objets (CBMN), UMR CNRS 5248, Univ. Bordeaux, 18 Av Geoffroy St Hilaire, 33600 Pessac, France
| | - A Pirog
- Laboratoire d'Intégration du Matériau au Système (IMS), UMR CNRS 5218, Univ. Bordeaux, Bordeaux INP, 33400 Talence, France
| | - M Jaffredo
- Laboratoire de Chimie et Biologie des Membranes et des Nano-Objets (CBMN), UMR CNRS 5248, Univ. Bordeaux, 18 Av Geoffroy St Hilaire, 33600 Pessac, France
| | - J Gaitan
- Laboratoire de Chimie et Biologie des Membranes et des Nano-Objets (CBMN), UMR CNRS 5248, Univ. Bordeaux, 18 Av Geoffroy St Hilaire, 33600 Pessac, France
| | - B Catargi
- Laboratoire de Chimie et Biologie des Membranes et des Nano-Objets (CBMN), UMR CNRS 5248, Univ. Bordeaux, 18 Av Geoffroy St Hilaire, 33600 Pessac, France; Hôpital St André, Bordeaux University Hospital, Univ. Bordeaux, 1 rue Jean Burguet, 33000 Bordeaux, France
| | - S Renaud
- Laboratoire d'Intégration du Matériau au Système (IMS), UMR CNRS 5218, Univ. Bordeaux, Bordeaux INP, 33400 Talence, France
| | - M Raoux
- Laboratoire de Chimie et Biologie des Membranes et des Nano-Objets (CBMN), UMR CNRS 5248, Univ. Bordeaux, 18 Av Geoffroy St Hilaire, 33600 Pessac, France
| | - J Lang
- Laboratoire de Chimie et Biologie des Membranes et des Nano-Objets (CBMN), UMR CNRS 5248, Univ. Bordeaux, 18 Av Geoffroy St Hilaire, 33600 Pessac, France.
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430
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The somatostatin-secreting pancreatic δ-cell in health and disease. NATURE REVIEWS. ENDOCRINOLOGY 2018. [PMID: 29773871 DOI: 10.1038/s41574‐018‐0020‐6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The somatostatin-secreting δ-cells comprise ~5% of the cells of the pancreatic islets. The δ-cells have complex morphology and might interact with many more islet cells than suggested by their low numbers. δ-Cells contain ATP-sensitive potassium channels, which open at low levels of glucose but close when glucose is elevated. This closure initiates membrane depolarization and electrical activity and increased somatostatin secretion. Factors released by neighbouring α-cells or β-cells amplify the glucose-induced effects on somatostatin secretion from δ-cells, which act locally within the islets as paracrine or autocrine inhibitors of insulin, glucagon and somatostatin secretion. The effects of somatostatin are mediated by activation of somatostatin receptors coupled to the inhibitory G protein, which culminates in suppression of the electrical activity and exocytosis in α-cells and β-cells. Somatostatin secretion is perturbed in animal models of diabetes mellitus, which might explain the loss of appropriate hypoglycaemia-induced glucagon secretion, a defect that could be mitigated by somatostatin receptor 2 antagonists. Somatostatin antagonists or agents that suppress somatostatin secretion have been proposed as an adjunct to insulin therapy. In this Review, we summarize the cell physiology of somatostatin secretion, what might go wrong in diabetes mellitus and the therapeutic potential of agents targeting somatostatin secretion or action.
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431
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Godazgar M, Zhang Q, Chibalina MV, Rorsman P. Biphasic voltage-dependent inactivation of human Na V 1.3, 1.6 and 1.7 Na + channels expressed in rodent insulin-secreting cells. J Physiol 2018; 596:1601-1626. [PMID: 29441586 PMCID: PMC5924821 DOI: 10.1113/jp275587] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/06/2018] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS Na+ current inactivation is biphasic in insulin-secreting cells, proceeding with two voltage dependences that are half-maximal at ∼-100 mV and -60 mV. Inactivation of voltage-gated Na+ (NaV ) channels occurs at ∼30 mV more negative voltages in insulin-secreting Ins1 and primary β-cells than in HEK, CHO or glucagon-secreting αTC1-6 cells. The difference in inactivation between Ins1 and non-β-cells persists in the inside-out patch configuration, discounting an involvement of a diffusible factor. In Ins1 cells and primary β-cells, but not in HEK cells, inactivation of a single NaV subtype is biphasic and follows two voltage dependences separated by 30-40 mV. We propose that NaV channels adopt different inactivation behaviours depending on the local membrane environment. ABSTRACT Pancreatic β-cells are equipped with voltage-gated Na+ channels that undergo biphasic voltage-dependent steady-state inactivation. A small Na+ current component (10-15%) inactivates over physiological membrane potentials and contributes to action potential firing. However, the major Na+ channel component is completely inactivated at -90 to -80 mV and is therefore inactive in the β-cell. It has been proposed that the biphasic inactivation reflects the contribution of different NaV α-subunits. We tested this possibility by expression of TTX-resistant variants of the NaV subunits found in β-cells (NaV 1.3, NaV 1.6 and NaV 1.7) in insulin-secreting Ins1 cells and in non-β-cells (including HEK and CHO cells). We found that all NaV subunits inactivated at 20-30 mV more negative membrane potentials in Ins1 cells than in HEK or CHO cells. The more negative inactivation in Ins1 cells does not involve a diffusible intracellular factor because the difference between Ins1 and CHO persisted after excision of the membrane. NaV 1.7 inactivated at 15--20 mV more negative membrane potentials than NaV 1.3 and NaV 1.6 in Ins1 cells but this small difference is insufficient to solely explain the biphasic inactivation in Ins1 cells. In Ins1 cells, but never in the other cell types, widely different components of NaV inactivation (separated by 30 mV) were also observed following expression of a single type of NaV α-subunit. The more positive component exhibited a voltage dependence of inactivation similar to that found in HEK and CHO cells. We propose that biphasic NaV inactivation in insulin-secreting cells reflects insertion of channels in membrane domains that differ with regard to lipid and/or membrane protein composition.
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Affiliation(s)
- Mahdieh Godazgar
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordChurchill HospitalOxfordOX3 7LEUK
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordChurchill HospitalOxfordOX3 7LEUK
| | - Margarita V. Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordChurchill HospitalOxfordOX3 7LEUK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordChurchill HospitalOxfordOX3 7LEUK
- Metabolic PhysiologyDepartment of Neuroscience and PhysiologyMedicinaregatan 11GothenburgS‐413 09Sweden
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432
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Functional Characterization of Native, High-Affinity GABA A Receptors in Human Pancreatic β Cells. EBioMedicine 2018; 30:273-282. [PMID: 29606630 PMCID: PMC5952339 DOI: 10.1016/j.ebiom.2018.03.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 02/02/2018] [Accepted: 03/12/2018] [Indexed: 01/19/2023] Open
Abstract
In human pancreatic islets, the neurotransmitter γ-aminobutyric acid (GABA) is an extracellular signaling molecule synthesized by and released from the insulin-secreting β cells. The effective, physiological GABA concentration range within human islets is unknown. Here we use native GABAA receptors in human islet β cells as biological sensors and reveal that 100–1000 nM GABA elicit the maximal opening frequency of the single-channels. In saturating GABA, the channels desensitized and stopped working. GABA modulated insulin exocytosis and glucose-stimulated insulin secretion. GABAA receptor currents were enhanced by the benzodiazepine diazepam, the anesthetic propofol and the incretin glucagon-like peptide-1 (GLP-1) but not affected by the hypnotic zolpidem. In type 2 diabetes (T2D) islets, single-channel analysis revealed higher GABA affinity of the receptors. The findings reveal unique GABAA receptors signaling in human islets β cells that is GABA concentration-dependent, differentially regulated by drugs, modulates insulin secretion and is altered in T2D. In human islets GABA (≤μM) activates β cell-specific GABAA receptors that become supersensitive to GABA in type 2 diabetes. GABAA receptors activity in β cells is enhanced by diazepam, anesthetics, the incretin GLP-1 but not the hypnotic zolpidem. GABA modulates rate of insulin granule exocytosis and glucose-stimulated insulin secretion.
GABA is a signal molecule in the brain but is also secreted by the insulin-producing β cells in pancreatic islets. GABA has many roles in human islets that most aim at optimizing function and survival of β cells. In the report by Korol, Jin et al. the authors identify and characterize the molecular unit that GABA binds to in human β cells, the GABAA receptors. These receptors normally sensitive become super-sensitive to GABA in type 2 diabetes. The GABAA receptors regulate insulin secretion and can themselves be regulated by the anxiolytic diazepam, anesthetics, the incretin GLP-1 but not the hypnotic zolpidem. Targeting GABA signaling in human islets in diabetes mellitus is likely to be a part of the solution when curing diabetes.
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433
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Abstract
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.
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Affiliation(s)
- Gabriela Da Silva Xavier
- Section of Functional Genomics and Cell Biology, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston B15 2TT, UK.
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434
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Lei CL, Kellard JA, Hara M, Johnson JD, Rodriguez B, Briant LJ. Beta-cell hubs maintain Ca 2+ oscillations in human and mouse islet simulations. Islets 2018; 10:151-167. [PMID: 30142036 PMCID: PMC6113907 DOI: 10.1080/19382014.2018.1493316] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/22/2018] [Indexed: 12/17/2022] Open
Abstract
Islet β-cells are responsible for secreting all circulating insulin in response to rising plasma glucose concentrations. These cells are a phenotypically diverse population that express great functional heterogeneity. In mice, certain β-cells (termed 'hubs') have been shown to be crucial for dictating the islet response to high glucose, with inhibition of these hub cells abolishing the coordinated Ca2+ oscillations necessary for driving insulin secretion. These β-cell hubs were found to be highly metabolic and susceptible to pro-inflammatory and glucolipotoxic insults. In this study, we explored the importance of hub cells in human by constructing mathematical models of Ca2+ activity in human islets. Our simulations revealed that hubs dictate the coordinated Ca2+ response in both mouse and human islets; silencing a small proportion of hubs abolished whole-islet Ca2+ activity. We also observed that if hubs are assumed to be preferentially gap junction coupled, then the simulations better adhere to the available experimental data. Our simulations of 16 size-matched mouse and human islet architectures revealed that there are species differences in the role of hubs; Ca2+ activity in human islets was more vulnerable to hub inhibition than mouse islets. These simulation results not only substantiate the existence of β-cell hubs, but also suggest that hubs may be favorably coupled in the electrical and metabolic network of the islet, and that targeted destruction of these cells would greatly impair human islet function.
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Affiliation(s)
- Chon-Lok Lei
- Doctoral Training Centre, University of Oxford, Oxford, UK
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Joely A. Kellard
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, UK
| | - Manami Hara
- Department of Medicine, The University of Chicago, Chicago, USA
| | - James D. Johnson
- Department of Cellular and Physiological Sciences, Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Linford J.B. Briant
- Department of Computer Science, University of Oxford, Oxford, UK
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, UK
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