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Grumbine MK, Kamat V, Bao K, Crupi T, Mokate K, Lim R, Chao JR, Robbings BM, Hass DT, Hurley JB, Sweet IR. Maintaining and Assessing Various Tissue and Cell Types of the Eye Using a Novel Pumpless Fluidics System. J Vis Exp 2023:10.3791/65399. [PMID: 37522735 PMCID: PMC10791547 DOI: 10.3791/65399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023] Open
Abstract
Many in vitro models used to investigate tissue function and cell biology require a flow of media to provide adequate oxygenation and optimal cell conditions required for the maintenance of function and viability. Toward this end, we have developed a multi-channel flow culture system to maintain tissue and cells in culture and continuously assess function and viability by either in-line sensors and/or collection of outflow fractions. The system combines 8-channel, continuous optical sensing of oxygen consumption rate with a built-in fraction collector to simultaneously measure production rates of metabolites and hormone secretion. Although it is able to maintain and assess a wide range of tissue and cell models, including islets, muscle, and hypothalamus, here we describe its operating principles and the experimental preparations/protocols that we have used to investigate bioenergetic regulation of isolated mouse retina, mouse retinal pigment epithelium (RPE)-choroid-sclera, and cultured human RPE cells. Innovations in the design of the system, such as pumpless fluid flow, have produced a greatly simplified operation of a multi-channel flow system. Videos and images are shown that illustrate how to assemble, prepare the instrument for an experiment, and load the different tissue/cell models into the perifusion chambers. In addition, guidelines for selecting conditions for protocol- and tissue-specific experiments are delineated and discussed, including setting the correct flow rate to tissue ratio to obtain consistent and stable culture conditions and accurate determinations of consumption and production rates. The combination of optimal tissue maintenance and real-time assessment of multiple parameters yields highly informative data sets that will have great utility for research in the physiology of the eye and drug discovery for the treatment of impaired vision.
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Affiliation(s)
| | - Varun Kamat
- UW Medicine Diabetes Institute, University of Washington
| | | | | | - Kedar Mokate
- UW Medicine Diabetes Institute, University of Washington
| | - Rayne Lim
- Department of Ophthalmology, University of Washington
| | | | | | - Daniel T Hass
- Department of Biochemistry, University of Washington
| | | | - Ian R Sweet
- EnTox Sciences, Inc; UW Medicine Diabetes Institute, University of Washington;
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Chen KH, Doliba N, May CL, Roman J, Ustione A, Tembo T, Negron A, Radovick S, Piston DW, Glaser B, Kaestner KH, Matschinsky FM. Genetic activation of glucokinase in a minority of pancreatic beta cells causes hypoglycemia in mice. Life Sci 2022; 309:120952. [PMID: 36100080 PMCID: PMC10312065 DOI: 10.1016/j.lfs.2022.120952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 09/06/2022] [Accepted: 09/08/2022] [Indexed: 01/05/2023]
Abstract
AIMS Glucokinase (GK) is expressed in the glucose-sensing cells of the islets of Langerhans and plays a critical role in glucose homeostasis. Here, we tested the hypothesis that genetic activation of GK in a small subset of β-cells is sufficient to change the glucose set-point of the whole islet. MATERIAL AND METHODS Mouse models of cell-type specific GK deficiency (GKKO) and genetic enzyme activation (GKKI) in a subset of β-cells were obtained by crossing the αGSU (gonadotropin alpha subunit)-Cre transgene with the appropriate GK mutant alleles. Metabolic analyses consisted of glucose tolerance tests, perifusion of isolated islets and intracellular calcium measurements. KEY FINDINGS The αGSU-Cre transgene produced genetically mosaic islets, as Cre was active in 15 ± 1.2 % of β-cells. While mice deficient for GK in a subset of islet cells were normal, unexpectedly, GKKI mice were chronically hypoglycemic, glucose intolerant, and had a lower threshold for glucose stimulated insulin secretion. GKKI mice exhibited an average fasting blood glucose level of 3.5 mM. GKKI islets responded with intracellular calcium signals that spread through the whole islets at 1 mM and secreted insulin at 3 mM glucose. SIGNIFICANCE Genetic activation of GK in a minority of β-cells is sufficient to change the glucose threshold for insulin secretion in the entire islet and thereby glucose homeostasis in the whole animal. These data support the model in which β-cells with higher GK activity function as 'hub' or 'trigger' cells and thus control insulin secretion by the β-cell collective within the islet.
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Affiliation(s)
- Kevin H Chen
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Nicolai Doliba
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Catherine L May
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Jeffrey Roman
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Alessandro Ustione
- Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Teguru Tembo
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Ariel Negron
- Department of Medicine and Pediatrics, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA
| | - Sally Radovick
- Department of Medicine and Pediatrics, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Benjamin Glaser
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA.
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA.
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Schulze T, Mattern K, Erfle P, Brüning D, Scherneck S, Dietzel A, Rustenbeck I. A Parallel Perifusion Slide From Glass for the Functional and Morphological Analysis of Pancreatic Islets. Front Bioeng Biotechnol 2021; 9:615639. [PMID: 33763408 PMCID: PMC7982818 DOI: 10.3389/fbioe.2021.615639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 02/12/2021] [Indexed: 12/15/2022] Open
Abstract
An islet-on-chip system in the form of a completely transparent microscope slide optically accessible from both sides was developed. It is made from laser-structured borosilicate glass and enables the parallel perifusion of five microchannels, each containing one islet precisely immobilized in a pyramidal well. The islets can be in inserted via separate loading windows above each pyramidal well. This design enables a gentle, fast and targeted insertion of the islets and a reliable retention in the well while at the same time permitting a sufficiently fast exchange of the media. In addition to the measurement of the hormone content in the fractionated efflux, parallel live cell imaging of the islet is possible. By programmable movement of the microscopic stage imaging of five wells can be performed. The current chip design ensures sufficient time resolution to characterize typical parameters of stimulus-secretion coupling. This was demonstrated by measuring the reaction of the islets to stimulation by glucose and potassium depolarization. After the perifusion experiment islets can be removed for further analysis. The live-dead assay of the removed islets confirmed that the process of insertion and removal was not detrimental to islet structure and viability. In conclusion, the present islet-on-chip design permits the practical implementation of parallel perifusion experiments on a single and easy to load glass slide. For each immobilized islet the correlation between secretion, signal transduction and morphology is possible. The slide concept allows the scale-up to even higher degrees of parallelization.
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Affiliation(s)
- Torben Schulze
- Institute of Pharmacology and Toxicology, Technische Universität Braunschweig, Braunschweig, Germany.,Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany
| | - Kai Mattern
- Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany.,Institute of Microtechnology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Per Erfle
- Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany.,Institute of Microtechnology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Dennis Brüning
- Institute of Pharmacology and Toxicology, Technische Universität Braunschweig, Braunschweig, Germany.,Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany
| | - Stephan Scherneck
- Institute of Pharmacology and Toxicology, Technische Universität Braunschweig, Braunschweig, Germany.,Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany
| | - Andreas Dietzel
- Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany.,Institute of Microtechnology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Ingo Rustenbeck
- Institute of Pharmacology and Toxicology, Technische Universität Braunschweig, Braunschweig, Germany.,Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Braunschweig, Germany
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Kuok IT, Rountree AM, Jung SR, Sweet IR. Palmitate is not an effective fuel for pancreatic islets and amplifies insulin secretion independent of calcium release from endoplasmic reticulum. Islets 2019; 11:51-64. [PMID: 31084524 PMCID: PMC6548485 DOI: 10.1080/19382014.2019.1601490] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The aim of the study was to determine the acute contribution of fuel oxidation in mediating the increase in insulin secretion rate (ISR) in response to fatty acids. Measures of mitochondrial metabolism, as reflected by oxygen consumption rate (OCR) and cytochrome c reduction, calcium signaling, and ISR by rat islets were used to evaluate processes stimulated by acute exposure to palmitic acid (PA). The contribution of mitochondrial oxidation of PA was determined in the presence and absence of a blocker of mitochondrial transport of fatty acids (etomoxir) at different glucose concentrations. Subsequent to increasing glucose from 3 to 20 mM, PA caused small increases in OCR and cytosolic calcium (about 20% of the effect of glucose). In contrast, the effect of PA on ISR was almost 3 times that by glucose, suggesting that the metabolism of PA is not the dominant mechanism mediating PA's effect on ISR. This was further supported by lack of inhibition of PA-stimulated OCR and ISR when blocking entry of PA into mitochondria (with etomoxir), and PA's lack of stimulation of reduced cytochrome c in the presence of high glucose. Consistent with the lack of metabolic stimulation by PA, an inhibitor of calcium release from the endoplasmic reticulum, but not a blocker of L-type calcium channels, abolished the PA-induced elevation of cytosolic calcium. Notably, ISR was unaffected by thapsigargin showing the dissociation of endoplasmic reticulum calcium release and second phase insulin secretion. In conclusion, stimulation of ISR by PA was mediated by mechanisms largely independent of the oxidation of the fuel.
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Affiliation(s)
- Iok Teng Kuok
- University of Washington Diabetes Research Institute, University of Washington, Seattle, WA, USA
| | - Austin M. Rountree
- University of Washington Diabetes Research Institute, University of Washington, Seattle, WA, USA
| | - Seung-Ryoung Jung
- University of Washington Diabetes Research Institute, University of Washington, Seattle, WA, USA
| | - Ian R. Sweet
- University of Washington Diabetes Research Institute, University of Washington, Seattle, WA, USA
- CONTACT Ian R. Sweet UW Diabetes Institute, University of Washington, Box 358062, 750 Republican Street, Seattle, WA 98195-8062
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Rickels MR, Perez EM, Peleckis AJ, Alshehabi E, Nguyen HL, Stefanovski D, Rickels K, Teff KL. Contribution of parasympathetic muscarinic augmentation of insulin secretion to olanzapine-induced hyperinsulinemia. Am J Physiol Endocrinol Metab 2018; 315:E250-E257. [PMID: 29351487 PMCID: PMC6139492 DOI: 10.1152/ajpendo.00315.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Atypical antipsychotic drugs have been associated with the development of obesity and diabetes. In particular, olanzapine can induce peripheral insulin resistance and compensatory hyperinsulinemia independent of weight gain or psychiatric disease. To determine if this compensatory increase in insulin is mediated by parasympathetic muscarinic stimulation, we randomized 15 healthy subjects 2:1 to receive double-blind olanzapine or placebo for 9 days under diet- and activity-controlled inpatient conditions. Before and after 7 days of study drug administration, subjects underwent frequently sampled intravenous glucose tolerance tests with either saline or atropine infused on subsequent days to assess insulin secretion and hepatic insulin extraction in the absence or presence of muscarinic blockade. We found that olanzapine led to an increase in the acute insulin response to glucose, which was not seen with placebo, and was attenuated in the olanzapine group by atropine. Deconvolution of C-peptide data confirmed an increase in insulin secretion with olanzapine, which was blocked by atropine, with a modest reduction in hepatic insulin extraction with olanzapine. These results support the contribution of muscarinic augmentation of insulin secretion to olanzapine-induced hyperinsulinemia, and provide a mechanism for the compensatory hyperinsulinemia that normally serves to prevent deterioration of glucose tolerance under conditions of metabolic challenge.
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Affiliation(s)
- Michael R Rickels
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Elys M Perez
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Amy J Peleckis
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Erica Alshehabi
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Huong-Lan Nguyen
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
- Monell Chemical Senses Center , Philadelphia, Pennsylvania
| | - Darko Stefanovski
- Department of Biostatistics, School of Veterinary Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Karl Rickels
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Karen L Teff
- Monell Chemical Senses Center , Philadelphia, Pennsylvania
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Lu S, Dugan CE, Kennedy RT. Microfluidic Chip with Integrated Electrophoretic Immunoassay for Investigating Cell-Cell Interactions. Anal Chem 2018; 90:5171-5178. [PMID: 29578696 PMCID: PMC6943824 DOI: 10.1021/acs.analchem.7b05304] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Microfluidics have been used to create "body-on-chip" systems to mimic in vivo cellular interactions with a high level of control. Most such systems rely on optical observation of cells as a readout. In this work we integrated a cell-cell interaction chip with online microchip electrophoresis immunoassay to monitor the effects of the interaction on protein secretion dynamics. The system was used to investigate the effects of adipocytes on insulin secretion. Chips were loaded with 190 000 3T3-L1 adipocytes and a single islet of Langerhans in separate chambers. The chambers were perfused at 300-600 nL/min so that adipocyte secretions flowed over the islets for 3 h. Adipocytes produced 80 μM of nonesterified fatty acids (NEFAs), a factor known to impact insulin secretion, at the islets. After perfusion, islets were challenged with a step change in glucose from 3 to 11 mM while monitoring insulin secretion at 8 s intervals by online immunoassay. Adipocyte treatment augmented insulin secretion by 6-fold compared to controls. The effect was far greater than comparable concentrations of NEFA applied to the islets demonstrating that adipocytes release multiple factors that can strongly potentiate insulin secretion. The experiments reveal that integration of chemical analysis with cell-cell interaction can provide valuable insights into cellular functions.
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Affiliation(s)
- Shusheng Lu
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109 , United States
| | - Colleen E Dugan
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109 , United States
| | - Robert T Kennedy
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109 , United States
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7
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Doliba NM, Liu Q, Li C, Chen P, Liu C, Naji A, Matschinsky FM. Inhibition of cholinergic potentiation of insulin secretion from pancreatic islets by chronic elevation of glucose and fatty acids: Protection by casein kinase 2 inhibitor. Mol Metab 2017; 6:1240-1253. [PMID: 29031723 PMCID: PMC5641685 DOI: 10.1016/j.molmet.2017.07.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 07/24/2017] [Accepted: 07/31/2017] [Indexed: 01/24/2023] Open
Abstract
Objectives Chronic hyperlipidemia and hyperglycemia are characteristic features of type 2 diabetes (T2DM) that are thought to cause or contribute to β-cell dysfunction by “glucolipotoxicity.” Previously we have shown that acute treatment of pancreatic islets with fatty acids (FA) decreases acetylcholine-potentiated insulin secretion. This acetylcholine response is mediated by M3 muscarinic receptors, which play a key role in regulating β-cell function. Here we examine whether chronic FA exposure also inhibits acetylcholine-potentiated insulin secretion using mouse and human islets. Methods Islets were cultured for 3 or 4 days at different glucose concentration with 0.5 mM palmitic acid (PA) or a 2:1 mixture of PA and oleic acid (OA) at 1% albumin (PA/BSA molar ratio 3.3). Afterwards, the response to glucose and acetylcholine were studied in perifusion experiments. Results FA-induced impairment of insulin secretion and Ca2+ signaling depended strongly on the glucose concentrations of the culture medium. PA and OA in combination reduced acetylcholine potentiation of insulin secretion more than PA alone, both in mouse and human islets, with no evidence of a protective role of OA. In contrast, lipotoxicity was not observed with islets cultured for 3 days in medium containing less than 1 mM glucose and a mixture of glutamine and leucine (7 mM each). High glucose and FAs reduced endoplasmic reticulum (ER) Ca2+ storage capacity; however, preserving ER Ca2+ by blocking the IP3 receptor with xestospongin C did not protect islets from glucolipotoxic effects on insulin secretion. In contrast, an inhibitor of casein kinase 2 (CK2) protected the glucose dependent acetylcholine potentiation of insulin secretion in mouse and human islets against glucolipotoxicity. Conclusions These results show that chronic FA treatment decreases acetylcholine potentiation of insulin secretion and that this effect is strictly glucose dependent and might involve CK2 phosphorylation of β-cell M3 muscarinic receptors. Glucolipotoxicity impairs acetylcholine-potentiation of insulin secretion. Glucose amplification of insulin secretion rather than triggering is damaged by FA. Inhibitor of casein kinase 2 preserved islet function against glucolipotoxicity.
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Affiliation(s)
- Nicolai M Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA.
| | - Qin Liu
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
| | - Changhong Li
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Pan Chen
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Chengyang Liu
- Department of Surgery, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
| | - Ali Naji
- Department of Surgery, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
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Abstract
The pancreatic β-cell secretes insulin in response to elevated plasma glucose. This review applies an external bioenergetic critique to the central processes of glucose-stimulated insulin secretion, including glycolytic and mitochondrial metabolism, the cytosolic adenine nucleotide pool, and its interaction with plasma membrane ion channels. The control mechanisms responsible for the unique responsiveness of the cell to glucose availability are discussed from bioenergetic and metabolic control standpoints. The concept of coupling factor facilitation of secretion is critiqued, and an attempt is made to unravel the bioenergetic basis of the oscillatory mechanisms controlling secretion. The need to consider the physiological constraints operating in the intact cell is emphasized throughout. The aim is to provide a coherent pathway through an extensive, complex, and sometimes bewildering literature, particularly for those unfamiliar with the field.
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Affiliation(s)
- David G Nicholls
- Buck Institute for Research on Aging, Novato, California; and Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmo, Sweden
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Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis. PLoS One 2016; 11:e0152869. [PMID: 27138453 PMCID: PMC4854486 DOI: 10.1371/journal.pone.0152869] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/21/2016] [Indexed: 12/17/2022] Open
Abstract
Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger pathway interactions will improve understanding of critical regulatory sites, how different GPCRs interact and pharmacological targets for modulating insulin secretion in type 2 diabetes.
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Simvastatin Impairs Insulin Secretion by Multiple Mechanisms in MIN6 Cells. PLoS One 2015; 10:e0142902. [PMID: 26561346 PMCID: PMC4641640 DOI: 10.1371/journal.pone.0142902] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 10/28/2015] [Indexed: 01/17/2023] Open
Abstract
Statins are widely used in the treatment of hypercholesterolemia and are efficient in the prevention of cardiovascular disease. Molecular mechanisms explaining statin-induced impairment in insulin secretion remain largely unknown. In the current study, we show that simvastatin decreased glucose-stimulated insulin secretion in mouse pancreatic MIN6 β-cells by 59% and 79% (p<0.01) at glucose concentration of 5.5 mmol/l and 16.7 mmol/l, respectively, compared to control, whereas pravastatin did not impair insulin secretion. Simvastatin induced decrease in insulin secretion occurred through multiple targets. In addition to its established effects on ATP-sensitive potassium channels (p = 0.004) and voltage-gated calcium channels (p = 0.004), simvastatin suppressed insulin secretion stimulated by muscarinic M3 or GPR40 receptor agonists (Tak875 by 33%, p = 0.002; GW9508 by 77%, p = 0.01) at glucose level of 5.5 mmol/l, and inhibited calcium release from the endoplasmic reticulum. Impaired insulin secretion caused by simvastatin treatment were efficiently restored by GPR119 or GLP-1 receptor stimulation and by direct activation of cAMP-dependent signaling pathways with forskolin. The effects of simvastatin treatment on insulin secretion were not affected by the presence of hyperglycemia. Our observation of the opposite effects of simvastatin and pravastatin on glucose-stimulated insulin secretion is in agreement with previous reports showing that simvastatin, but not pravastatin, was associated with increased risk of incident diabetes.
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11
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Doliba NM, Liu Q, Li C, Chen J, Chen P, Liu C, Frederick DW, Baur JA, Bennett MJ, Naji A, Matschinsky FM. Accumulation of 3-hydroxytetradecenoic acid: Cause or corollary of glucolipotoxic impairment of pancreatic β-cell bioenergetics? Mol Metab 2015; 4:926-39. [PMID: 26909309 PMCID: PMC4731732 DOI: 10.1016/j.molmet.2015.09.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 09/16/2015] [Accepted: 09/25/2015] [Indexed: 12/20/2022] Open
Abstract
Objectives Hyperglycemia and elevated blood lipids are the presumed precipitating causes of β-cell damage in T2DM as the result of a process termed “glucolipotoxicity”. Here, we tested whether glucolipotoxic pathophysiology is caused by defective bioenergetics using islets in culture. Methods Insulin secretion, respiration, ATP generation, fatty acid (FA) metabolite profiles and gene expression were determined in isolated islets treated under glucolipotoxic culture conditions. Results Over time, chronic exposure of mouse islets to FAs with glucose leads to bioenergetic failure and reduced insulin secretion upon stimulation with glucose or amino acids. Islets exposed to glucolipotoxic conditions displayed biphasic changes of the oxygen consumption rate (OCR): an initial increase in baseline and Vmax of OCR after 3 days, followed by decreased baseline and glucose stimulated OCR after 5 days. These changes were associated with lower islet ATP levels, impaired glucose-induced ATP generation, a trend for reduced mitochondrial DNA content and reduced expression of mitochondrial transcription factor A (Tfam). We discovered the accumulation of carnitine esters of hydroxylated long chain FAs, in particular 3-hydroxytetradecenoyl-carnitine. Conclusions As long chain 3-hydroxylated FA metabolites are known to uncouple heart and brain mitochondria [53], [54], [55], we propose that under glucolipotoxic condition, unsaturated hydroxylated long-chain FAs accumulate, uncouple and ultimately inhibit β-cell respiration. This leads to the slow deterioration of mitochondrial function progressing to bioenergetics β-cell failure. We found low capacity of islets to generate ATP after glucolipotoxic treatment. Found biphasic (up/down) respiratory time course as expression of glucolipotoxicity. We found β-Hydroxylated long FA metabolites as new glucolipotoxicity mediators. β-Hydroxylated long FAs are known to uncouple Ox/Phos. We propose defective bioenergetics as main cause of glucolipotoxicity.
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Affiliation(s)
- Nicolai M. Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
- Corresponding author. University of Pennsylvania, Biochemistry/Biophysics, 3400 Civic Center Blvd, Smilow Center for Translation Research, TRC12-131, Philadelphia, PA 19104, United States. Tel.: +1 215 898 4366; fax: +1 215 898 5408.
| | - Qing Liu
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Changhong Li
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Jie Chen
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Pan Chen
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Chengyang Liu
- Department of Surgery, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - David W. Frederick
- Department of Physiology, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Joseph A. Baur
- Department of Physiology, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Michael J. Bennett
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Ali Naji
- Department of Surgery, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Franz M. Matschinsky
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
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Volpato AM, Zugno AI, Quevedo J. Recent evidence and potential mechanisms underlying weight gain and insulin resistance due to atypical antipsychotics. BRAZILIAN JOURNAL OF PSYCHIATRY 2014; 35:295-304. [PMID: 24142093 DOI: 10.1590/1516-4446-2012-1052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 12/20/2012] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Atypical antipsychotics (AAPs) promote obesity and insulin resistance. In this regard, the main objective of this study was to present potential mechanisms and evidence concerning side effects of atypical antipsychotics in humans and rodents. METHOD A systematic review of the literature was performed using the MEDLINE database. We checked the references of selected articles, review articles, and books on the subject. RESULTS This review provides consistent results concerning the side effects of olanzapine (OL) and clozapine (CLZ), whereas we found conflicting results related to other AAPs. Most studies involving humans describe the effects on body weight, adiposity, lipid profile, and blood glucose levels. However, it seems difficult to identify an animal model replicating the wide range of changes observed in humans. Animal lineage, route of administration, dose, and duration of treatment should be carefully chosen for the replication of the findings in humans. CONCLUSIONS Patients undergoing treatment with AAPs are at higher risk of developing adverse metabolic changes. This increased risk must be taken into account when making decisions about treatment. The influence of AAPs on multiple systems is certainly the cause of such effects. Specifically, muscarinic and histaminergic pathways seem to play important roles.
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Affiliation(s)
- Ana Maria Volpato
- Universidade do Extremo Sul Catarinense, Laboratory of Neurosciences, CriciúmaSC, Brazil
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Xiang JN, Chen DL, Yang LY. Effect of PANDER in βTC6-cell lipoapoptosis and the protective role of exendin-4. Biochem Biophys Res Commun 2012; 421:701-6. [PMID: 22542939 DOI: 10.1016/j.bbrc.2012.04.065] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 04/13/2012] [Indexed: 12/29/2022]
Abstract
Chronic exposure to high concentrations of saturated fatty acids, such as palmitic acid (PA), leads to apoptosis of pancreatic β-cells through the activation of the c-Jun N-terminal kinase (JNK) signaling pathway. This study of β-cell lipoapoptosis was designed to investigate the roles of pancreatic-derived factor (PANDER), a pro-apoptosis cytokine-like peptide, and exendin-4, a long-acting agonist of the hormone glucagon-like peptide-1 (GLP-1) receptor and anti-apoptosis factor. The glucose-sensitive mouse β-pancreatic cell line, βTC6, was used to investigate the mechanisms of PA-induced apoptosis. Twenty-four hours of PA exposure led to increased PANDER expression in a dose- and time-dependent manner, and significantly increased phosphorylation of JNK. Treatment with the JNK-specific inhibitor SP600125 reduced the PA-induced PANDER expression. After the 24h of PA exposure, cells also underwent marked apoptosis and showed increased activation of the apoptosis protease, caspase-3. The small interfering (si)RNA-mediated silencing of PANDER gene expression significantly reduced both of these effects. When PA-treated βTC6 cells were exposed to exogenous exendin-4, JNK activation was inhibited, PANDER expression was decreased, and the numbers of apoptotic cells were reduced. Collectively, these results demonstrated that the JNK-mediated signaling mechanism of PA-induced β-cell apoptosis involves up-regulated expression of PANDER and activation of caspase-3. Exendin-4 may protect against lipoapoptosis by interfering with the JNK-PANDER pathway.
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Affiliation(s)
- Jing-Nan Xiang
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian 350005, China
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Chen W, Lisowski M, Khalil G, Sweet IR, Shen AQ. Microencapsulated 3-dimensional sensor for the measurement of oxygen in single isolated pancreatic islets. PLoS One 2012; 7:e33070. [PMID: 22479359 PMCID: PMC3315556 DOI: 10.1371/journal.pone.0033070] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 02/03/2012] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Oxygen consumption reflects multiple processes in pancreatic islets including mechanisms contributing to insulin secretion, oxidative stress and viability, providing an important readout in studies of islet function, islet viability and drug testing. Due to the scarcity, heterogeneity, and intrinsic kinetic properties of individual islets, it would be of great benefit to detect oxygen consumption by single islets. We present a novel method we have developed to image oxygen in single islets. METHODOLOGY/PRINCIPAL FINDINGS Using a microfluidics system, individual islets and a fluorescent oxygen-sensitive dye were encased within a thin alginate polymer layer. Insulin secretion by the encapsulated islets was normal. Fluorescent signal from the encased dye, detected using a standard inverted fluorescence microscope and digital camera, was stable and proportional to the amount of oxygen in the media. When integrated into a perifusion system, the sensing system detected changes in response to metabolic substrates, mitochondrial poisons, and induced-oscillations. Glucose responses averaged 30.1±7.1% of the response to a metabolic inhibitor (cyanide), increases were observed in all cases (n = 6), and the system was able to resolve changes in oxygen consumption that had a period greater than 0.5 minutes. The sensing system operated similarly from 2-48 hours following encapsulation, and viability and function of the islets were not significantly affected by the encapsulation process. CONCLUSIONS/SIGNIFICANCE An oxygen-dependent dye situated around and within a pancreatic islet encapsulated by a thin layer of alginate was sensitive to changes in oxygen consumption, and was not harmful to the function or viability of islets over the course of two days. The microcapsule-based sensing method is particularly suited to assessing the effects of compounds (dose responses and time courses) and chronic changes occurring over the course of days. The approach should be applicable to other cell types and dyes sensitive to other biologically important molecules.
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Affiliation(s)
- Wanyu Chen
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
- School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, China
| | - Mark Lisowski
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Gamal Khalil
- Department of Aeronautics and Astronautics Department, University of Washington, Seattle, Washington, Unites States of America
| | - Ian R. Sweet
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Amy Q. Shen
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
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Doliba NM, Qin W, Najafi H, Liu C, Buettger CW, Sotiris J, Collins HW, Li C, Stanley CA, Wilson DF, Grimsby J, Sarabu R, Naji A, Matschinsky FM. Glucokinase activation repairs defective bioenergetics of islets of Langerhans isolated from type 2 diabetics. Am J Physiol Endocrinol Metab 2012; 302:E87-E102. [PMID: 21952036 PMCID: PMC3328091 DOI: 10.1152/ajpendo.00218.2011] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/20/2011] [Indexed: 12/31/2022]
Abstract
It was reported previously that isolated human islets from individuals with type 2 diabetes mellitus (T2DM) show reduced glucose-stimulated insulin release. To assess the possibility that impaired bioenergetics may contribute to this defect, glucose-stimulated respiration (Vo(2)), glucose usage and oxidation, intracellular Ca(2+), and insulin secretion (IS) were measured in pancreatic islets isolated from three healthy and three type 2 diabetic organ donors. Isolated mouse and rat islets were studied for comparison. Islets were exposed to a "staircase" glucose stimulus, whereas IR and Vo(2) were measured. Vo(2) of human islets from normals and diabetics increased sigmoidally from equal baselines of 0.25 nmol/100 islets/min as a function of glucose concentration. Maximal Vo(2) of normal islets at 24 mM glucose was 0.40 ± 0.02 nmol·min(-1)·100 islets(-1), and the glucose S(0.5) was 4.39 ± 0.10 mM. The glucose stimulation of respiration of islets from diabetics was lower, V(max) of 0.32 ± 0.01 nmol·min(-1)·100 islets(-1), and the S(0.5) shifted to 5.43 ± 0.13 mM. Glucose-stimulated IS and the rise of intracellular Ca(2+) were also reduced in diabetic islets. A clinically effective glucokinase activator normalized the defective Vo(2), IR, and free calcium responses during glucose stimulation in islets from type 2 diabetics. The body of data shows that there is a clear relationship between the pancreatic islet energy (ATP) production rate and IS. This relationship was similar for normal human, mouse, and rat islets and the data for all species fitted a single sigmoidal curve. The shared threshold rate for IS was ∼13 pmol·min(-1)·islet(-1). Exendin-4, a GLP-1 analog, shifted the ATP production-IS curve to the left and greatly potentiated IS with an ATP production rate threshold of ∼10 pmol·min(-1)·islet(-1). Our data suggest that impaired β-cell bioenergetics resulting in greatly reduced ATP production is critical in the molecular pathogenesis of type 2 diabetes mellitus.
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Affiliation(s)
- Nicolai M Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania, 415 Curie Blvd., Philadelphia, PA 19104-6140, USA
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Teff KL, Kim SF. Atypical antipsychotics and the neural regulation of food intake and peripheral metabolism. Physiol Behav 2011; 104:590-8. [PMID: 21664918 PMCID: PMC3139777 DOI: 10.1016/j.physbeh.2011.05.033] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/26/2011] [Accepted: 05/31/2011] [Indexed: 12/18/2022]
Abstract
The atypical antipsychotics (AAPs) are associated with weight gain and an increased incidence of metabolic disease including type 2 diabetes mellitus. Epidemiological, cross-sectional and prospective studies suggest that two of the AAPs, olanzapine and clozapine, cause the most dramatic weight gain and metabolic impairments including increased fasting glucose, insulin and triglycerides. Relative to the other AAPs, both olanzapine and clozapine exhibit a particularly high antagonistic affinity for histamine and muscarinic receptors which have been hypothesized as mediators of the reported increase in weight and glucose abnormalities. In this article, we review the current evidence for the AAP associated weight gain and abnormal glucose metabolism. We postulate that the effects of the AAPs on food intake and peripheral metabolism are initially independently regulated but with increasing body adiposity, the early AAP-induced impairments in peripheral metabolism will be exacerbated, thereby establishing a vicious cycle such that the effects of the AAP are magnified by the known pathophysiological consequences of obesity. Furthermore, we examine how inhibition of the histaminergic pathway may mediate increases in food intake and the potential role of the vagus nerve in the reported peripheral metabolic effects.
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Affiliation(s)
- Karen L Teff
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA.
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Song SC, Choi SH, Choi DW, Heo JS, Kim WS, Kim MJ. Potential risk factors for nonalcoholic steatohepatitis related to pancreatic secretions following pancreaticoduodenectomy. World J Gastroenterol 2011; 17:3716-23. [PMID: 21990953 PMCID: PMC3181457 DOI: 10.3748/wjg.v17.i32.3716] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/16/2011] [Accepted: 04/23/2011] [Indexed: 02/06/2023] Open
Abstract
AIM: To identify risk factors for nonalcoholic steatohepatitis following pancreaticoduodenectomy, with a focus on factors related to pancreatic secretions.
METHODS: The medical records of 228 patients who had a pancreaticoduodenectomy over a 16-mo period were reviewed retrospectively. The 193 patients who did not have fatty liver disease preoperatively were included in the final analysis. Hepatic steatosis was diagnosed using the differences between splenic and hepatic attenuation and liver-to-spleen attenuation as measured by non-enhanced computed tomography.
RESULTS: Fifteen patients (7.8%) who showed postoperative hepatic fatty changes were assigned to Group A, and the remaining patients were assigned to Group B. Patient demographics, preoperative laboratory findings (including levels of C-peptide, glucagon, insulin and glucose tolerance test results), operation types, and final pathological findings did not differ significantly between the two groups; however, the frequency of pancreatic fistula (P = 0.020) and the method of pancreatic duct stenting (P = 0.005) showed significant differences between the groups. A multivariate analysis identified pancreatic fistula (HR = 3.332, P = 0.037) and external pancreatic duct stenting (HR = 4.530, P = 0.017) as independent risk factors for the development of postoperative steatohepatitis.
CONCLUSION: Pancreatic fistula and external pancreatic duct stenting were identified as independent risk factors for the development of steatohepatitis following pancreaticoduodenectomy.
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Bibliography. Current world literature. Adrenal cortex. Curr Opin Endocrinol Diabetes Obes 2011; 18:231-3. [PMID: 21522003 DOI: 10.1097/med.0b013e3283457c7d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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