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Rutter GA, Gresch A, Delgadillo Silva L, Benninger RKP. Exploring pancreatic beta-cell subgroups and their connectivity. Nat Metab 2024:10.1038/s42255-024-01097-6. [PMID: 39117960 DOI: 10.1038/s42255-024-01097-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 07/05/2024] [Indexed: 08/10/2024]
Abstract
Functional pancreatic islet beta cells are essential to ensure glucose homeostasis across species from zebrafish to humans. These cells show significant heterogeneity, and emerging studies have revealed that connectivity across a hierarchical network is required for normal insulin release. Here, we discuss current thinking and areas of debate around intra-islet connectivity, cellular hierarchies and potential "controlling" beta-cell populations. We focus on methodologies, including comparisons of different cell preparations as well as in vitro and in vivo approaches to imaging and controlling the activity of human and rodent islet preparations. We also discuss the analytical approaches that can be applied to live-cell data to identify and study critical subgroups of cells with a disproportionate role in control Ca2+ dynamics and thus insulin secretion (such as "first responders", "leaders" and "hubs", as defined by Ca2+ responses to glucose stimulation). Possible mechanisms by which this hierarchy is achieved, its physiological relevance and how its loss may contribute to islet failure in diabetes mellitus are also considered. A glossary of terms and links to computational resources are provided.
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Affiliation(s)
- Guy A Rutter
- CHUM Research Center and Faculty of Medicine, University of Montréal, Montréal, QC, Canada.
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK.
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
| | - Anne Gresch
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Luis Delgadillo Silva
- CHUM Research Center and Faculty of Medicine, University of Montréal, Montréal, QC, Canada
| | - Richard K P Benninger
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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2
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Šterk M, Zhang Y, Pohorec V, Leitgeb EP, Dolenšek J, Benninger RKP, Stožer A, Kravets V, Gosak M. Network representation of multicellular activity in pancreatic islets: Technical considerations for functional connectivity analysis. PLoS Comput Biol 2024; 20:e1012130. [PMID: 38739680 PMCID: PMC11115366 DOI: 10.1371/journal.pcbi.1012130] [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] [Received: 01/03/2024] [Revised: 05/23/2024] [Accepted: 05/02/2024] [Indexed: 05/16/2024] Open
Abstract
Within the islets of Langerhans, beta cells orchestrate synchronized insulin secretion, a pivotal aspect of metabolic homeostasis. Despite the inherent heterogeneity and multimodal activity of individual cells, intercellular coupling acts as a homogenizing force, enabling coordinated responses through the propagation of intercellular waves. Disruptions in this coordination are implicated in irregular insulin secretion, a hallmark of diabetes. Recently, innovative approaches, such as integrating multicellular calcium imaging with network analysis, have emerged for a quantitative assessment of the cellular activity in islets. However, different groups use distinct experimental preparations, microscopic techniques, apply different methods to process the measured signals and use various methods to derive functional connectivity patterns. This makes comparisons between findings and their integration into a bigger picture difficult and has led to disputes in functional connectivity interpretations. To address these issues, we present here a systematic analysis of how different approaches influence the network representation of islet activity. Our findings show that the choice of methods used to construct networks is not crucial, although care is needed when combining data from different islets. Conversely, the conclusions drawn from network analysis can be heavily affected by the pre-processing of the time series, the type of the oscillatory component in the signals, and by the experimental preparation. Our tutorial-like investigation aims to resolve interpretational issues, reconcile conflicting views, advance functional implications, and encourage researchers to adopt connectivity analysis. As we conclude, we outline challenges for future research, emphasizing the broader applicability of our conclusions to other tissues exhibiting complex multicellular dynamics.
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Affiliation(s)
- Marko Šterk
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Yaowen Zhang
- Department of Pediatrics, Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Viljem Pohorec
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Jurij Dolenšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Richard K. P. Benninger
- Department of Bioengineering, Barbara Davis Center for Diabetes, Aurora, Colorado, United States of America
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Vira Kravets
- Department of Pediatrics, Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
- Department of Bioengineering, Jacobs School of Engineering, University of California, San Diego, La Jolla, California, United States of America
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, Maribor
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3
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Paradiž Leitgeb E, Kerčmar J, Križančić Bombek L, Pohorec V, Skelin Klemen M, Slak Rupnik M, Gosak M, Dolenšek J, Stožer A. Exendin-4 affects calcium signalling predominantly during activation and activity of beta cell networks in acute mouse pancreas tissue slices. Front Endocrinol (Lausanne) 2024; 14:1315520. [PMID: 38292770 PMCID: PMC10826511 DOI: 10.3389/fendo.2023.1315520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/22/2023] [Indexed: 02/01/2024] Open
Abstract
Tight control of beta cell stimulus-secretion coupling is crucial for maintaining homeostasis of energy-rich nutrients. While glucose serves as a primary regulator of this process, incretins augment beta cell function, partly by enhancing cytosolic [Ca2+] dynamics. However, the details of how precisely they affect beta cell recruitment during activation, their active time, and functional connectivity during plateau activity, and how they influence beta cell deactivation remain to be described. Performing functional multicellular Ca2+ imaging in acute mouse pancreas tissue slices enabled us to systematically assess the effects of the GLP-1 receptor agonist exendin-4 (Ex-4) simultaneously in many coupled beta cells with high resolution. In otherwise substimulatory glucose, Ex-4 was able to recruit approximately a quarter of beta cells into an active state. Costimulation with Ex-4 and stimulatory glucose shortened the activation delays and accelerated beta cell activation dynamics. More specifically, active time increased faster, and the time required to reach half-maximal activation was effectively halved in the presence of Ex-4. Moreover, the active time and regularity of [Ca2+]IC oscillations increased, especially during the first part of beta cell response. In contrast, subsequent addition of Ex-4 to already active cells did not significantly enhance beta cell activity. Network analyses further confirmed increased connectivity during activation and activity in the presence of Ex-4, with hub cell roles remaining rather stable in both control experiments and experiments with Ex-4. Interestingly, Ex-4 demonstrated a biphasic effect on deactivation, slightly prolonging beta cell activity at physiological concentrations and shortening deactivation delays at supraphysiological concentrations. In sum, costimulation by Ex-4 and glucose increases [Ca2+]IC during beta cell activation and activity, indicating that the effect of incretins may, to an important extent, be explained by enhanced [Ca2+]IC signals. During deactivation, previous incretin stimulation does not critically prolong cellular activity, which corroborates their low risk of hypoglycemia.
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Affiliation(s)
- Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jasmina Kerčmar
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Vilijem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
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Cohrs CM, Chen C, Atkinson MA, Drotar DM, Speier S. Bridging the Gap: Pancreas Tissue Slices From Organ and Tissue Donors for the Study of Diabetes Pathogenesis. Diabetes 2024; 73:11-22. [PMID: 38117999 PMCID: PMC10784654 DOI: 10.2337/dbi20-0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 10/14/2023] [Indexed: 12/22/2023]
Abstract
Over the last two decades, increased availability of human pancreatic tissues has allowed for major expansions in our understanding of islet biology in health and disease. Indeed, studies of fixed and frozen pancreatic tissues, as well as efforts using viable isolated islets obtained from organ donors, have provided significant insights toward our understanding of diabetes. However, the procedures associated with islet isolation result in distressed cells that have been removed from any surrounding influence. The pancreas tissue slice technology was developed as an in situ approach to overcome certain limitations associated with studies on isolated islets or fixed tissue. In this Perspective, we discuss the value of this novel platform and review how pancreas tissue slices, within a short time, have been integrated in numerous studies of rodent and human islet research. We show that pancreas tissue slices allow for investigations in a less perturbed organ tissue environment, ranging from cellular processes, over peri-islet modulations, to tissue interactions. Finally, we discuss the considerations and limitations of this technology in its future applications. We believe the pancreas tissue slices will help bridge the gap between studies on isolated islets and cells to the systemic conditions by providing new insight into physiological and pathophysiological processes at the organ level. ARTICLE HIGHLIGHTS Human pancreas tissue slices represent a novel platform to study human islet biology in close to physiological conditions. Complementary to established technologies, such as isolated islets, single cells, and histological sections, pancreas tissue slices help bridge our understanding of islet physiology and pathophysiology from single cell to intact organ. Diverse sources of viable human pancreas tissue, each with distinct characteristics to be considered, are available to use in tissue slices for the study of diabetes pathogenesis.
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Affiliation(s)
- Christian M. Cohrs
- Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of Helmholtz Munich at the University Hospital and Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Chunguang Chen
- Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of Helmholtz Munich at the University Hospital and Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Mark A. Atkinson
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, FL
| | - Denise M. Drotar
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, FL
| | - Stephan Speier
- Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of Helmholtz Munich at the University Hospital and Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
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5
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Šterk M, Barać U, Stožer A, Gosak M. Both electrical and metabolic coupling shape the collective multimodal activity and functional connectivity patterns in beta cell collectives: A computational model perspective. Phys Rev E 2023; 108:054409. [PMID: 38115462 DOI: 10.1103/physreve.108.054409] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 10/20/2023] [Indexed: 12/21/2023]
Abstract
Pancreatic beta cells are coupled excitable oscillators that synchronize their activity via different communication pathways. Their oscillatory activity manifests itself on multiple timescales and consists of bursting electrical activity, subsequent oscillations in the intracellular Ca^{2+}, as well as oscillations in metabolism and exocytosis. The coordination of the intricate activity on the multicellular level plays a key role in the regulation of physiological pulsatile insulin secretion and is incompletely understood. In this paper, we investigate theoretically the principles that give rise to the synchronized activity of beta cell populations by building up a phenomenological multicellular model that incorporates the basic features of beta cell dynamics. Specifically, the model is composed of coupled slow and fast oscillatory units that reflect metabolic processes and electrical activity, respectively. Using a realistic description of the intercellular interactions, we study how the combination of electrical and metabolic coupling generates collective rhythmicity and shapes functional beta cell networks. It turns out that while electrical coupling solely can synchronize the responses, the addition of metabolic interactions further enhances coordination, the spatial range of interactions increases the number of connections in the functional beta cell networks, and ensures a better consistency with experimental findings. Moreover, our computational results provide additional insights into the relationship between beta cell heterogeneity, their activity profiles, and functional connectivity, supplementing thereby recent experimental results on endocrine networks.
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Affiliation(s)
- Marko Šterk
- Department of Physics, Faculty of Natural Sciences and Mathematics, Koroška cesta 160, University of Maribor, 2000 Maribor, Slovenia
- Institute of Physiology, Faculty of Medicine, Taborska ulica 8, University of Maribor, 2000 Maribor, Slovenia
- Alma Mater Europaea, Slovenska ulica 17, 2000 Maribor, Slovenia
| | - Uroš Barać
- Department of Physics, Faculty of Natural Sciences and Mathematics, Koroška cesta 160, University of Maribor, 2000 Maribor, Slovenia
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, Taborska ulica 8, University of Maribor, 2000 Maribor, Slovenia
| | - Marko Gosak
- Department of Physics, Faculty of Natural Sciences and Mathematics, Koroška cesta 160, University of Maribor, 2000 Maribor, Slovenia
- Institute of Physiology, Faculty of Medicine, Taborska ulica 8, University of Maribor, 2000 Maribor, Slovenia
- Alma Mater Europaea, Slovenska ulica 17, 2000 Maribor, Slovenia
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6
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Skelin Klemen M, Dolenšek J, Križančić Bombek L, Pohorec V, Gosak M, Slak Rupnik M, Stožer A. The effect of forskolin and the role of Epac2A during activation, activity, and deactivation of beta cell networks. Front Endocrinol (Lausanne) 2023; 14:1225486. [PMID: 37701894 PMCID: PMC10494243 DOI: 10.3389/fendo.2023.1225486] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/08/2023] [Indexed: 09/14/2023] Open
Abstract
Beta cells couple stimulation by glucose with insulin secretion and impairments in this coupling play a central role in diabetes mellitus. Cyclic adenosine monophosphate (cAMP) amplifies stimulus-secretion coupling via protein kinase A and guanine nucleotide exchange protein 2 (Epac2A). With the present research, we aimed to clarify the influence of cAMP-elevating diterpene forskolin on cytoplasmic calcium dynamics and intercellular network activity, which are two of the crucial elements of normal beta cell stimulus-secretion coupling, and the role of Epac2A under normal and stimulated conditions. To this end, we performed functional multicellular calcium imaging of beta cells in mouse pancreas tissue slices after stimulation with glucose and forskolin in wild-type and Epac2A knock-out mice. Forskolin evoked calcium signals in otherwise substimulatory glucose and beta cells from Epac2A knock-out mice displayed a faster activation. During the plateau phase, beta cells from Epac2A knock-out mice displayed a slightly higher active time in response to glucose compared with wild-type littermates, and stimulation with forskolin increased the active time via an increase in oscillation frequency and a decrease in oscillation duration in both Epac2A knock-out and wild-type mice. Functional network properties during stimulation with glucose did not differ in Epac2A knock-out mice, but the presence of Epac2A was crucial for the protective effect of stimulation with forskolin in preventing a decline in beta cell functional connectivity with time. Finally, stimulation with forskolin prolonged beta cell activity during deactivation, especially in Epac2A knock-out mice.
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Affiliation(s)
- Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | | | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, European Center Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, European Center Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
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Fletcher PA, Thompson B, Liu C, Bertram R, Satin LS, Sherman AS. Ca 2+ release or Ca 2+ entry, that is the question: what governs Ca 2+ oscillations in pancreatic β cells? Am J Physiol Endocrinol Metab 2023; 324:E477-E487. [PMID: 37074988 PMCID: PMC10228667 DOI: 10.1152/ajpendo.00030.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 04/06/2023] [Accepted: 04/07/2023] [Indexed: 04/20/2023]
Abstract
The standard model for Ca2+ oscillations in insulin-secreting pancreatic β cells centers on Ca2+ entry through voltage-activated Ca2+ channels. These work in combination with ATP-dependent K+ channels, which are the bridge between the metabolic state of the cells and plasma membrane potential. This partnership underlies the ability of the β cells to secrete insulin appropriately on a minute-to-minute time scale to control whole body plasma glucose. Though this model, developed over more than 40 years through many cycles of experimentation and mathematical modeling, has been very successful, it has been challenged by a hypothesis that calcium-induced calcium release from the endoplasmic reticulum through ryanodine or inositol trisphosphate (IP3) receptors is instead the key driver of islet oscillations. We show here that the alternative model is in fact incompatible with a large body of established experimental data and that the new observations offered in support of it can be better explained by the standard model.
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Affiliation(s)
- Patrick A Fletcher
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, Maryland, United States
| | - Ben Thompson
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Chanté Liu
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Richard Bertram
- Department of Mathematics and Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, Florida, United States
| | - Leslie S Satin
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Arthur S Sherman
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, Maryland, United States
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Mastracci TL, Apte M, Amundadottir LT, Alvarsson A, Artandi S, Bellin MD, Bernal-Mizrachi E, Caicedo A, Campbell-Thompson M, Cruz-Monserrate Z, El Ouaamari A, Gaulton KJ, Geisz A, Goodarzi MO, Hara M, Hull-Meichle RL, Kleger A, Klein AP, Kopp JL, Kulkarni RN, Muzumdar MD, Naren AP, Oakes SA, Olesen SS, Phelps EA, Powers AC, Stabler CL, Tirkes T, Whitcomb DC, Yadav D, Yong J, Zaghloul NA, Pandol SJ, Sander M. Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases: Workshop Proceedings. Diabetes 2023; 72:433-448. [PMID: 36940317 PMCID: PMC10033248 DOI: 10.2337/db22-0942] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 12/29/2022] [Indexed: 03/22/2023]
Abstract
The Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases workshop was a 1.5-day scientific conference at the National Institutes of Health (Bethesda, MD) that engaged clinical and basic science investigators interested in diseases of the pancreas. This report provides a summary of the proceedings from the workshop. The goals of the workshop were to forge connections and identify gaps in knowledge that could guide future research directions. Presentations were segregated into six major theme areas, including 1) pancreas anatomy and physiology, 2) diabetes in the setting of exocrine disease, 3) metabolic influences on the exocrine pancreas, 4) genetic drivers of pancreatic diseases, 5) tools for integrated pancreatic analysis, and 6) implications of exocrine-endocrine cross talk. For each theme, multiple presentations were followed by panel discussions on specific topics relevant to each area of research; these are summarized here. Significantly, the discussions resulted in the identification of research gaps and opportunities for the field to address. In general, it was concluded that as a pancreas research community, we must more thoughtfully integrate our current knowledge of normal physiology as well as the disease mechanisms that underlie endocrine and exocrine disorders so that there is a better understanding of the interplay between these compartments.
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Affiliation(s)
- Teresa L. Mastracci
- Department of Biology, Indiana University–Purdue University Indianapolis, Indianapolis, IN
| | - Minoti Apte
- Faculty of Medicine and Health, University of New South Wales, Sydney, Australia
| | | | - Alexandra Alvarsson
- Diabetes, Obesity, and Metabolism Institute, Mount Sinai Hospital, New York, NY
| | - Steven Artandi
- Department of Internal Medicine, Stanford University, Stanford, CA
| | - Melena D. Bellin
- Departments of Pediatrics and Surgery, University of Minnesota Medical School, Minneapolis, MN
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL
| | - Alejandro Caicedo
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL
| | - Martha Campbell-Thompson
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL
| | - Zobeida Cruz-Monserrate
- Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH
| | | | - Kyle J. Gaulton
- Department of Pediatrics, University of California San Diego, La Jolla, CA
| | - Andrea Geisz
- Department of Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA
| | - Mark O. Goodarzi
- Division of Endocrinology, Diabetes, and Metabolism, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Manami Hara
- Department of Medicine, The University of Chicago, Chicago, IL
| | - Rebecca L. Hull-Meichle
- Department of Medicine, Division of Metabolism, Endocrinology, and Nutrition, University of Washington, Seattle, WA
| | - Alexander Kleger
- Institute of Molecular Oncology and Stem Cell Biology, Ulm University, Ulm, Germany
| | - Alison P. Klein
- Department of Pathology and Medicine, Johns Hopkins School of Medicine, Baltimore MD
| | - Janel L. Kopp
- Department of Cellular & Physiological Sciences, The University of British Columbia, Vancouver, Canada
| | | | - Mandar D. Muzumdar
- Departments of Genetics and Internal Medicine (Oncology), Yale University School of Medicine, New Haven, CT
| | | | - Scott A. Oakes
- Department of Pathology, The University of Chicago, Chicago, IL
| | - Søren S. Olesen
- Department of Gastroenterology and Hepatology, Aalborg University Hospital, Aalborg, Denmark
| | - Edward A. Phelps
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL
| | - Alvin C. Powers
- Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, TN
| | - Cherie L. Stabler
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL
| | - Temel Tirkes
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN
| | | | - Dhiraj Yadav
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Jing Yong
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Norann A. Zaghloul
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Stephen J. Pandol
- Department of Gastroenterology, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Maike Sander
- Department of Pediatrics and Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA
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9
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Galvis D, Hodson DJ, Wedgwood KC. Spatial distribution of heterogeneity as a modulator of collective dynamics in pancreatic beta-cell networks and beyond. FRONTIERS IN NETWORK PHYSIOLOGY 2023; 3:fnetp.2023.1170930. [PMID: 36987428 PMCID: PMC7614376 DOI: 10.3389/fnetp.2023.1170930] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
We study the impact of spatial distribution of heterogeneity on collective dynamics in gap-junction coupled beta-cell networks comprised on cells from two populations that differ in their intrinsic excitability. Initially, these populations are uniformly and randomly distributed throughout the networks. We develop and apply an iterative algorithm for perturbing the arrangement of the network such that cells from the same population are increasingly likely to be adjacent to one another. We find that the global input strength, or network drive, necessary to transition the network from a state of quiescence to a state of synchronised and oscillatory activity decreases as network sortedness increases. Moreover, for weak coupling, we find that regimes of partial synchronisation and wave propagation arise, which depend both on network drive and network sortedness. We then demonstrate the utility of this algorithm for studying the distribution of heterogeneity in general networks, for which we use Watts-Strogatz networks as a case study. This work highlights the importance of heterogeneity in node dynamics in establishing collective rhythms in complex, excitable networks and has implications for a wide range of real-world systems that exhibit such heterogeneity.
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Affiliation(s)
- Daniel Galvis
- Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, UK
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Correspondence: Daniel Galvis,
| | - David J. Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Oxford Centre for Diabetes, Endocrinology, and Metabolism (OCDEM), Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Kyle C.A. Wedgwood
- Living Systems Institute, University of Exeter, Exeter, UK
- EPSRC Hub for Quantitative Modelling in Healthcare, University of Exeter, Exeter, UK
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
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10
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Šterk M, Dolenšek J, Skelin Klemen M, Križančić Bombek L, Paradiž Leitgeb E, Kerčmar J, Perc M, Slak Rupnik M, Stožer A, Gosak M. Functional characteristics of hub and wave-initiator cells in β cell networks. Biophys J 2023; 122:784-801. [PMID: 36738106 PMCID: PMC10027448 DOI: 10.1016/j.bpj.2023.01.039] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 12/22/2022] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
Islets of Langerhans operate as multicellular networks in which several hundred β cells work in synchrony to produce secretory pulses of insulin, a hormone crucial for controlling metabolic homeostasis. Their collective rhythmic activity is facilitated by gap junctional coupling and affected by their functional heterogeneity, but the details of this robust and coordinated behavior are still not fully understood. Recent advances in multicellular imaging and optogenetic and photopharmacological strategies, as well as in network science, have led to the discovery of specialized β cell subpopulations that were suggested to critically determine the collective dynamics in the islets. In particular hubs, i.e., β cells with many functional connections, are believed to significantly enhance communication capacities of the intercellular network and facilitate an efficient spreading of intercellular Ca2+ waves, whereas wave-initiator cells trigger intercellular signals in their cohorts. Here, we determined Ca2+ signaling characteristics of these two β cell subpopulations and the relationship between them by means of functional multicellular Ca2+ imaging in mouse pancreatic tissue slices in combination with methods of complex network theory. We constructed network layers based on individual Ca2+ waves to identify wave initiators, and functional correlation-based networks to detect hubs. We found that both cell types exhibit a higher-than-average active time under both physiological and supraphysiological glucose concentrations, but also that they differ significantly in many other functional characteristics. Specifically, Ca2+ oscillations in hubs are more regular, and their role appears to be much more stable over time than for initiator cells. Moreover, in contrast to wave initiators, hubs transmit intercellular signals faster than other cells, which implies a stronger intercellular coupling. Our research indicates that hubs and wave-initiator cell subpopulations are both natural features of healthy pancreatic islets, but their functional roles in principle do not overlap and should thus not be considered equal.
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Affiliation(s)
- Marko Šterk
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | | | | | - Jasmina Kerčmar
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Matjaž Perc
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; Alma Mater Europaea, Maribor, Slovenia; Complexity Science Hub Vienna, Vienna, Austria; Department of Physics, Kyung Hee University, Dongdaemun-gu, Seoul, Republic of Korea
| | - Marjan Slak Rupnik
- Faculty of Medicine, University of Maribor, Maribor, Slovenia; Alma Mater Europaea, Maribor, Slovenia; Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia.
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Faculty of Medicine, University of Maribor, Maribor, Slovenia; Alma Mater Europaea, Maribor, Slovenia.
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11
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Chabosseau P, Yong F, Delgadillo-Silva LF, Lee EY, Melhem R, Li S, Gandhi N, Wastin J, Noriega LL, Leclerc I, Ali Y, Hughes JW, Sladek R, Martinez-Sanchez A, Rutter GA. Molecular phenotyping of single pancreatic islet leader beta cells by "Flash-Seq". Life Sci 2023; 316:121436. [PMID: 36706832 DOI: 10.1016/j.lfs.2023.121436] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/11/2023] [Accepted: 01/20/2023] [Indexed: 01/26/2023]
Abstract
AIMS Spatially-organized increases in cytosolic Ca2+ within pancreatic beta cells in the pancreatic islet underlie the stimulation of insulin secretion by high glucose. Recent data have revealed the existence of subpopulations of beta cells including "leaders" which initiate Ca2+ waves. Whether leader cells possess unique molecular features, or localisation, is unknown. MAIN METHODS High speed confocal Ca2+ imaging was used to identify leader cells and connectivity analysis, running under MATLAB and Python, to identify highly connected "hub" cells. To explore transcriptomic differences between beta cell sub-groups, individual leaders or followers were labelled by photo-activation of the cryptic fluorescent protein PA-mCherry and subjected to single cell RNA sequencing ("Flash-Seq"). KEY FINDINGS Distinct Ca2+ wave types were identified in individual islets, with leader cells present in 73 % (28 of 38 islets imaged). Scale-free, power law-adherent behaviour was also observed in 29 % of islets, though "hub" cells in these islets did not overlap with leaders. Transcripts differentially expressed (295; padj < 0.05) between leader and follower cells included genes involved in cilium biogenesis and transcriptional regulation. Providing some support for these findings, ADCY6 immunoreactivity tended to be higher in leader than follower cells, whereas cilia number and length tended to be lower in the former. Finally, leader cells were located significantly closer to delta, but not alpha, cells in Euclidian space than were follower cells. SIGNIFICANCE The existence of both a discrete transcriptome and unique localisation implies a role for these features in defining the specialized function of leaders. These data also raise the possibility that localised signalling between delta and leader cells contributes to the initiation and propagation of islet Ca2+ waves.
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Affiliation(s)
- Pauline Chabosseau
- Centre de Recherche du CHUM, Faculté de Médicine, Université de Montréal, Montréal, QC, Canada
| | - Fiona Yong
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom; Lee Kong Chian Imperial Medical School, Nanyang Technological University, Singapore
| | - Luis F Delgadillo-Silva
- Centre de Recherche du CHUM, Faculté de Médicine, Université de Montréal, Montréal, QC, Canada
| | - Eun Young Lee
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States; Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, South Korea
| | - Rana Melhem
- Centre de Recherche du CHUM, Faculté de Médicine, Université de Montréal, Montréal, QC, Canada
| | - Shiying Li
- Centre de Recherche du CHUM, Faculté de Médicine, Université de Montréal, Montréal, QC, Canada
| | - Nidhi Gandhi
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Jules Wastin
- Centre de Recherche du CHUM, Faculté de Médicine, Université de Montréal, Montréal, QC, Canada
| | - Livia Lopez Noriega
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Isabelle Leclerc
- Centre de Recherche du CHUM, Faculté de Médicine, Université de Montréal, Montréal, QC, Canada
| | - Yusuf Ali
- Lee Kong Chian Imperial Medical School, Nanyang Technological University, Singapore
| | - Jing W Hughes
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
| | - Robert Sladek
- Departments of Medicine and Human Genetics, McGill University and Genome Quebec Innovation Centre, Montreal, QC, Canada
| | - Aida Martinez-Sanchez
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Guy A Rutter
- Centre de Recherche du CHUM, Faculté de Médicine, Université de Montréal, Montréal, QC, Canada; Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom; Lee Kong Chian Imperial Medical School, Nanyang Technological University, Singapore.
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12
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Gosak M, Yan-Do R, Lin H, MacDonald PE, Stožer A. Ca2+ Oscillations, Waves, and Networks in Islets From Human Donors With and Without Type 2 Diabetes. Diabetes 2022; 71:2584-2596. [PMID: 36084321 PMCID: PMC9750953 DOI: 10.2337/db22-0004] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 09/01/2022] [Indexed: 01/11/2023]
Abstract
Pancreatic islets are highly interconnected structures that produce pulses of insulin and other hormones, maintaining normal homeostasis of glucose and other nutrients. Normal stimulus-secretion and intercellular coupling are essential to regulated secretory responses, and these hallmarks are known to be altered in diabetes. In the current study, we used calcium imaging of isolated human islets to assess their collective behavior. The activity occurred in the form of calcium oscillations, was synchronized across different regions of islets through calcium waves, and was glucose dependent: higher glucose enhanced the activity, elicited a greater proportion of global calcium waves, and led to denser and less fragmented functional networks. Hub regions were identified in stimulatory conditions, and they were characterized by long active times. Moreover, calcium waves were found to be initiated in different subregions and the roles of initiators and hubs did not overlap. In type 2 diabetes, glucose dependence was retained, but reduced activity, locally restricted waves, and more segregated networks were detected compared with control islets. Interestingly, hub regions seemed to suffer the most by losing a disproportionately large fraction of connections. These changes affected islets from donors with diabetes in a heterogeneous manner.
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Affiliation(s)
- Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Richard Yan-Do
- Hong Kong Centre for Cerebro-Cardiovascular Health Engineering, Hong Kong Science Park, Department of Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Haopeng Lin
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Patrick E. MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
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13
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Pai VP, Cooper BG, Levin M. Screening Biophysical Sensors and Neurite Outgrowth Actuators in Human Induced-Pluripotent-Stem-Cell-Derived Neurons. Cells 2022; 11:cells11162470. [PMID: 36010547 PMCID: PMC9406775 DOI: 10.3390/cells11162470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/26/2022] [Accepted: 08/04/2022] [Indexed: 11/16/2022] Open
Abstract
All living cells maintain a charge distribution across their cell membrane (membrane potential) by carefully controlled ion fluxes. These bioelectric signals regulate cell behavior (such as migration, proliferation, differentiation) as well as higher-level tissue and organ patterning. Thus, voltage gradients represent an important parameter for diagnostics as well as a promising target for therapeutic interventions in birth defects, injury, and cancer. However, despite much progress in cell and molecular biology, little is known about bioelectric states in human stem cells. Here, we present simple methods to simultaneously track ion dynamics, membrane voltage, cell morphology, and cell activity (pH and ROS), using fluorescent reporter dyes in living human neurons derived from induced neural stem cells (hiNSC). We developed and tested functional protocols for manipulating ion fluxes, membrane potential, and cell activity, and tracking neural responses to injury and reinnervation in vitro. Finally, using morphology sensor, we tested and quantified the ability of physiological actuators (neurotransmitters and pH) to manipulate nerve repair and reinnervation. These methods are not specific to a particular cell type and should be broadly applicable to the study of bioelectrical controls across a wide range of combinations of models and endpoints.
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Affiliation(s)
- Vaibhav P. Pai
- Allen Discovery Center at Tufts University, Medford, MA 02155, USA
| | - Ben G. Cooper
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, MA 02155, USA
- Correspondence:
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14
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Stožer A, Šterk M, Paradiž Leitgeb E, Markovič R, Skelin Klemen M, Ellis CE, Križančić Bombek L, Dolenšek J, MacDonald PE, Gosak M. From Isles of Königsberg to Islets of Langerhans: Examining the Function of the Endocrine Pancreas Through Network Science. Front Endocrinol (Lausanne) 2022; 13:922640. [PMID: 35784543 PMCID: PMC9240343 DOI: 10.3389/fendo.2022.922640] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 05/16/2022] [Indexed: 12/12/2022] Open
Abstract
Islets of Langerhans are multicellular microorgans located in the pancreas that play a central role in whole-body energy homeostasis. Through secretion of insulin and other hormones they regulate postprandial storage and interprandial usage of energy-rich nutrients. In these clusters of hormone-secreting endocrine cells, intricate cell-cell communication is essential for proper function. Electrical coupling between the insulin-secreting beta cells through gap junctions composed of connexin36 is particularly important, as it provides the required, most important, basis for coordinated responses of the beta cell population. The increasing evidence that gap-junctional communication and its modulation are vital to well-regulated secretion of insulin has stimulated immense interest in how subpopulations of heterogeneous beta cells are functionally arranged throughout the islets and how they mediate intercellular signals. In the last decade, several novel techniques have been proposed to assess cooperation between cells in islets, including the prosperous combination of multicellular imaging and network science. In the present contribution, we review recent advances related to the application of complex network approaches to uncover the functional connectivity patterns among cells within the islets. We first provide an accessible introduction to the basic principles of network theory, enumerating the measures characterizing the intercellular interactions and quantifying the functional integration and segregation of a multicellular system. Then we describe methodological approaches to construct functional beta cell networks, point out possible pitfalls, and specify the functional implications of beta cell network examinations. We continue by highlighting the recent findings obtained through advanced multicellular imaging techniques supported by network-based analyses, giving special emphasis to the current developments in both mouse and human islets, as well as outlining challenges offered by the multilayer network formalism in exploring the collective activity of islet cell populations. Finally, we emphasize that the combination of these imaging techniques and network-based analyses does not only represent an innovative concept that can be used to describe and interpret the physiology of islets, but also provides fertile ground for delineating normal from pathological function and for quantifying the changes in islet communication networks associated with the development of diabetes mellitus.
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Affiliation(s)
- Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Šterk
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Rene Markovič
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Institute of Mathematics and Physics, Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Cara E. Ellis
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | | | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Patrick E. MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
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15
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Marolt U, Paradiž Leitgeb E, Pohorec V, Lipovšek S, Venglovecz V, Gál E, Ébert A, Menyhárt I, Potrč S, Gosak M, Dolenšek J, Stožer A. Calcium imaging in intact mouse acinar cells in acute pancreas tissue slices. PLoS One 2022; 17:e0268644. [PMID: 35657915 PMCID: PMC9165796 DOI: 10.1371/journal.pone.0268644] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/04/2022] [Indexed: 12/22/2022] Open
Abstract
The physiology and pathophysiology of the exocrine pancreas are in close connection to changes in intra-cellular Ca2+ concentration. Most of our knowledge is based on in vitro experiments on acinar cells or acini enzymatically isolated from their surroundings, which can alter their structure, physiology, and limit our understanding. Due to these limitations, the acute pancreas tissue slice technique was introduced almost two decades ago as a complementary approach to assess the morphology and physiology of both the endocrine and exocrine pancreas in a more conserved in situ setting. In this study, we extend previous work to functional multicellular calcium imaging on acinar cells in tissue slices. The viability and morphological characteristics of acinar cells within the tissue slice were assessed using the LIVE/DEAD assay, transmission electron microscopy, and immunofluorescence imaging. The main aim of our study was to characterize the responses of acinar cells to stimulation with acetylcholine and compare them with responses to cerulein in pancreatic tissue slices, with special emphasis on inter-cellular and inter-acinar heterogeneity and coupling. To this end, calcium imaging was performed employing confocal microscopy during stimulation with a wide range of acetylcholine concentrations and selected concentrations of cerulein. We show that various calcium oscillation parameters depend monotonically on the stimulus concentration and that the activity is rather well synchronized within acini, but not between acini. The acute pancreas tissue slice represents a viable and reliable experimental approach for the evaluation of both intra- and inter-cellular signaling characteristics of acinar cell calcium dynamics. It can be utilized to assess many cells simultaneously with a high spatiotemporal resolution, thus providing an efficient and high-yield platform for future studies of normal acinar cell biology, pathophysiology, and screening pharmacological substances.
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Affiliation(s)
- Urška Marolt
- Clinical department for abdominal and general surgery, University Medical Centre Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Saška Lipovšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Chemistry and Chemical Engineering, University of Maribor, Maribor, Slovenia
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Eleonóra Gál
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Attila Ébert
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - István Menyhárt
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Stojan Potrč
- Clinical department for abdominal and general surgery, University Medical Centre Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
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16
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Postić S, Gosak M, Tsai WH, Pfabe J, Sarikas S, Stožer A, Korošak D, Yang SB, Slak Rupnik M. pH-Dependence of Glucose-Dependent Activity of Beta Cell Networks in Acute Mouse Pancreatic Tissue Slice. Front Endocrinol (Lausanne) 2022; 13:916688. [PMID: 35837307 PMCID: PMC9273738 DOI: 10.3389/fendo.2022.916688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 05/24/2022] [Indexed: 12/01/2022] Open
Abstract
Extracellular pH has the potential to affect various aspects of the pancreatic beta cell function. To explain this effect, a number of mechanisms was proposed involving both extracellular and intracellular targets and pathways. Here, we focus on reassessing the influence of extracellular pH on glucose-dependent beta cell activation and collective activity in physiological conditions. To this end we employed mouse pancreatic tissue slices to perform high-temporally resolved functional imaging of cytosolic Ca2+ oscillations. We investigated the effect of either physiological H+ excess or depletion on the activation properties as well as on the collective activity of beta cell in an islet. Our results indicate that lowered pH invokes activation of a subset of beta cells in substimulatory glucose concentrations, enhances the average activity of beta cells, and alters the beta cell network properties in an islet. The enhanced average activity of beta cells was determined indirectly utilizing cytosolic Ca2+ imaging, while direct measuring of insulin secretion confirmed that this enhanced activity is accompanied by a higher insulin release. Furthermore, reduced functional connectivity and higher functional segregation at lower pH, both signs of a reduced intercellular communication, do not necessary result in an impaired insulin release.
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Affiliation(s)
- Sandra Postić
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- *Correspondence: Sandra Postić,
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Wen-Hao Tsai
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Johannes Pfabe
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Srdjan Sarikas
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Dean Korošak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Shi-Bing Yang
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Marjan Slak Rupnik
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea – European Center Maribor, Maribor, Slovenia
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17
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In Vitro Disease Models of the Endocrine Pancreas. Biomedicines 2021; 9:biomedicines9101415. [PMID: 34680532 PMCID: PMC8533367 DOI: 10.3390/biomedicines9101415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/30/2021] [Accepted: 10/05/2021] [Indexed: 12/12/2022] Open
Abstract
The ethical constraints and shortcomings of animal models, combined with the demand to study disease pathogenesis under controlled conditions, are giving rise to a new field at the interface of tissue engineering and pathophysiology, which focuses on the development of in vitro models of disease. In vitro models are defined as synthetic experimental systems that contain living human cells and mimic tissue- and organ-level physiology in vitro by taking advantage of recent advances in tissue engineering and microfabrication. This review provides an overview of in vitro models and focuses specifically on in vitro disease models of the endocrine pancreas and diabetes. First, we briefly review the anatomy, physiology, and pathophysiology of the human pancreas, with an emphasis on islets of Langerhans and beta cell dysfunction. We then discuss different types of in vitro models and fundamental elements that should be considered when developing an in vitro disease model. Finally, we review the current state and breakthroughs in the field of pancreatic in vitro models and conclude with some challenges that need to be addressed in the future development of in vitro models.
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18
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Stožer A, Skelin Klemen M, Gosak M, Križančić Bombek L, Pohorec V, Slak Rupnik M, Dolenšek J. Glucose-dependent activation, activity, and deactivation of beta cell networks in acute mouse pancreas tissue slices. Am J Physiol Endocrinol Metab 2021; 321:E305-E323. [PMID: 34280052 DOI: 10.1152/ajpendo.00043.2021] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/09/2021] [Indexed: 12/14/2022]
Abstract
Many details of glucose-stimulated intracellular calcium changes in β cells during activation, activity, and deactivation, as well as their concentration-dependence, remain to be analyzed. Classical physiological experiments indicated that in islets, functional differences between individual cells are largely attenuated, but recent findings suggest considerable intercellular heterogeneity, with some cells possibly coordinating the collective responses. To address the above with an emphasis on heterogeneity and describing the relations between classical physiological and functional network properties, we performed functional multicellular calcium imaging in mouse pancreas tissue slices over a wide range of glucose concentrations. During activation, delays to activation of cells and any-cell-to-first-responder delays are shortened, and the sizes of simultaneously responding clusters increased with increasing glucose concentrations. Exactly the opposite characterized deactivation. The frequency of fast calcium oscillations during activity increased with increasing glucose up to 12 mM glucose concentration, beyond which oscillation duration became longer, resulting in a homogenous increase in active time. In terms of functional connectivity, islets progressed from a very segregated network to a single large functional unit with increasing glucose concentration. A comparison between classical physiological and network parameters revealed that the first-responders during activation had longer active times during plateau and the most active cells during the plateau tended to deactivate later. Cells with the most functional connections tended to activate sooner, have longer active times, and deactivate later. Our findings provide a common ground for recent differing views on β cell heterogeneity and an important baseline for future studies of stimulus-secretion and intercellular coupling.NEW & NOTEWORTHY We assessed concentration-dependence in coupled β cells, degree of functional heterogeneity, and uncovered possible specialized subpopulations during the different phases of the response to glucose at the level of many individual cells. To this aim, we combined acute mouse pancreas tissue slices with functional multicellular calcium imaging over a wide range from threshold (7 mM) and physiological (8 and 9 mM) to supraphysiological (12 and 16 mM) glucose concentrations, classical physiological, and advanced network analyses.
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Affiliation(s)
- Andraž Stožer
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Marko Gosak
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | | | - Viljem Pohorec
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
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19
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Domínguez-Bendala J, Qadir MMF, Pastori RL. Temporal single-cell regeneration studies: the greatest thing since sliced pancreas? Trends Endocrinol Metab 2021; 32:433-443. [PMID: 34006411 PMCID: PMC8239162 DOI: 10.1016/j.tem.2021.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/12/2021] [Accepted: 04/16/2021] [Indexed: 01/01/2023]
Abstract
The application of single-cell analytic techniques to the study of stem/progenitor cell niches supports the emerging view that pancreatic cell lineages are in a state of flux between differentiation stages. For all their value, however, such analyses merely offer a snapshot of the cellular palette of the tissue at any given time point. Conclusions about potential developmental/regeneration paths are solely based on bioinformatics inferences. In this context, the advent of new techniques for the long-term culture and lineage tracing of human pancreatic slices offers a virtual window into the native organ and presents the field with a unique opportunity to serially resolve pancreatic regeneration dynamics at the single-cell level.
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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
- Section of Endocrinology and Metabolism, Tulane University Health Sciences Center, New Orleans, LA 70112, 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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20
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Rustenbeck I, Schulze T, Morsi M, Alshafei M, Panten U. What Is the Metabolic Amplification of Insulin Secretion and Is It (Still) Relevant? Metabolites 2021; 11:metabo11060355. [PMID: 34199454 PMCID: PMC8229681 DOI: 10.3390/metabo11060355] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/27/2021] [Accepted: 05/31/2021] [Indexed: 12/24/2022] Open
Abstract
The pancreatic beta-cell transduces the availability of nutrients into the secretion of insulin. While this process is extensively modified by hormones and neurotransmitters, it is the availability of nutrients, above all glucose, which sets the process of insulin synthesis and secretion in motion. The central role of the mitochondria in this process was identified decades ago, but how changes in mitochondrial activity are coupled to the exocytosis of insulin granules is still incompletely understood. The identification of ATP-sensitive K+-channels provided the link between the level of adenine nucleotides and the electrical activity of the beta cell, but the depolarization-induced Ca2+-influx into the beta cells, although necessary for stimulated secretion, is not sufficient to generate the secretion pattern as produced by glucose and other nutrient secretagogues. The metabolic amplification of insulin secretion is thus the sequence of events that enables the secretory response to a nutrient secretagogue to exceed the secretory response to a purely depolarizing stimulus and is thus of prime importance. Since the cataplerotic export of mitochondrial metabolites is involved in this signaling, an orienting overview on the topic of nutrient secretagogues beyond glucose is included. Their judicious use may help to define better the nature of the signals and their mechanism of action.
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Affiliation(s)
- Ingo Rustenbeck
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D38106 Braunschweig, Germany; (T.S.); (M.M.); (M.A.); (U.P.)
- Correspondence: ; Tel.: +49-(0)53-139-156-70
| | - Torben Schulze
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D38106 Braunschweig, Germany; (T.S.); (M.M.); (M.A.); (U.P.)
| | - Mai Morsi
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D38106 Braunschweig, Germany; (T.S.); (M.M.); (M.A.); (U.P.)
- Department of Pharmacology, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
| | - Mohammed Alshafei
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D38106 Braunschweig, Germany; (T.S.); (M.M.); (M.A.); (U.P.)
| | - Uwe Panten
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D38106 Braunschweig, Germany; (T.S.); (M.M.); (M.A.); (U.P.)
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21
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Saadati M, Jamali Y. The effects of beta-cell mass and function, intercellular coupling, and islet synchrony on [Formula: see text] dynamics. Sci Rep 2021; 11:10268. [PMID: 33986325 PMCID: PMC8119479 DOI: 10.1038/s41598-021-89333-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 04/26/2021] [Indexed: 11/30/2022] Open
Abstract
Type 2 diabetes (T2D) is a challenging metabolic disorder characterized by a substantial loss of [Formula: see text]-cell mass and alteration of [Formula: see text]-cell function in the islets of Langerhans, disrupting insulin secretion and glucose homeostasis. The mechanisms for deficiency in [Formula: see text]-cell mass and function during the hyperglycemia development and T2D pathogenesis are complex. To study the relative contribution of [Formula: see text]-cell mass to [Formula: see text]-cell function in T2D, we make use of a comprehensive electrophysiological model of human [Formula: see text]-cell clusters. We find that defect in [Formula: see text]-cell mass causes a functional decline in single [Formula: see text]-cell, impairment in intra-islet synchrony, and changes in the form of oscillatory patterns of membrane potential and intracellular [Formula: see text] concentration, which can lead to changes in insulin secretion dynamics and in insulin levels. The model demonstrates a good correspondence between suppression of synchronizing electrical activity and published experimental measurements. We then compare the role of gap junction-mediated electrical coupling with both [Formula: see text]-cell synchronization and metabolic coupling in the behavior of [Formula: see text] concentration dynamics within human islets. Our results indicate that inter-[Formula: see text]-cellular electrical coupling depicts a more important factor in shaping the physiological regulation of islet function and in human T2D. We further predict that varying the whole-cell conductance of delayed rectifier [Formula: see text] channels modifies oscillatory activity patterns of [Formula: see text]-cell population lacking intercellular coupling, which significantly affect [Formula: see text] concentration and insulin secretion.
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Affiliation(s)
- Maryam Saadati
- Biomathematics Laboratory, Department of Applied Mathematics, School of Mathematical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Yousef Jamali
- Biomathematics Laboratory, Department of Applied Mathematics, School of Mathematical Sciences, Tarbiat Modares University, Tehran, Iran
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22
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Šterk M, Križančić Bombek L, Skelin Klemen M, Slak Rupnik M, Marhl M, Stožer A, Gosak M. NMDA receptor inhibition increases, synchronizes, and stabilizes the collective pancreatic beta cell activity: Insights through multilayer network analysis. PLoS Comput Biol 2021; 17:e1009002. [PMID: 33974632 PMCID: PMC8139480 DOI: 10.1371/journal.pcbi.1009002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 05/21/2021] [Accepted: 04/26/2021] [Indexed: 12/15/2022] Open
Abstract
NMDA receptors promote repolarization in pancreatic beta cells and thereby reduce glucose-stimulated insulin secretion. Therefore, NMDA receptors are a potential therapeutic target for diabetes. While the mechanism of NMDA receptor inhibition in beta cells is rather well understood at the molecular level, its possible effects on the collective cellular activity have not been addressed to date, even though proper insulin secretion patterns result from well-synchronized beta cell behavior. The latter is enabled by strong intercellular connectivity, which governs propagating calcium waves across the islets and makes the heterogeneous beta cell population work in synchrony. Since a disrupted collective activity is an important and possibly early contributor to impaired insulin secretion and glucose intolerance, it is of utmost importance to understand possible effects of NMDA receptor inhibition on beta cell functional connectivity. To address this issue, we combined confocal functional multicellular calcium imaging in mouse tissue slices with network science approaches. Our results revealed that NMDA receptor inhibition increases, synchronizes, and stabilizes beta cell activity without affecting the velocity or size of calcium waves. To explore intercellular interactions more precisely, we made use of the multilayer network formalism by regarding each calcium wave as an individual network layer, with weighted directed connections portraying the intercellular propagation. NMDA receptor inhibition stabilized both the role of wave initiators and the course of waves. The findings obtained with the experimental antagonist of NMDA receptors, MK-801, were additionally validated with dextrorphan, the active metabolite of the approved drug dextromethorphan, as well as with experiments on NMDA receptor KO mice. In sum, our results provide additional and new evidence for a possible role of NMDA receptor inhibition in treatment of type 2 diabetes and introduce the multilayer network paradigm as a general strategy to examine effects of drugs on connectivity in multicellular systems.
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Affiliation(s)
- Marko Šterk
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | | | | | - Marjan Slak Rupnik
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Alma Mater Europaea–ECM, Maribor, Slovenia
| | - Marko Marhl
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Education, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Gosak
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
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23
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Zmazek J, Klemen MS, Markovič R, Dolenšek J, Marhl M, Stožer A, Gosak M. Assessing Different Temporal Scales of Calcium Dynamics in Networks of Beta Cell Populations. Front Physiol 2021; 12:612233. [PMID: 33833686 PMCID: PMC8021717 DOI: 10.3389/fphys.2021.612233] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/26/2021] [Indexed: 01/06/2023] Open
Abstract
Beta cells within the pancreatic islets of Langerhans respond to stimulation with coherent oscillations of membrane potential and intracellular calcium concentration that presumably drive the pulsatile exocytosis of insulin. Their rhythmic activity is multimodal, resulting from networked feedback interactions of various oscillatory subsystems, such as the glycolytic, mitochondrial, and electrical/calcium components. How these oscillatory modules interact and affect the collective cellular activity, which is a prerequisite for proper hormone release, is incompletely understood. In the present work, we combined advanced confocal Ca2+ imaging in fresh mouse pancreas tissue slices with time series analysis and network science approaches to unveil the glucose-dependent characteristics of different oscillatory components on both the intra- and inter-cellular level. Our results reveal an interrelationship between the metabolically driven low-frequency component and the electrically driven high-frequency component, with the latter exhibiting the highest bursting rates around the peaks of the slow component and the lowest around the nadirs. Moreover, the activity, as well as the average synchronicity of the fast component, considerably increased with increasing stimulatory glucose concentration, whereas the stimulation level did not affect any of these parameters in the slow component domain. Remarkably, in both dynamical components, the average correlation decreased similarly with intercellular distance, which implies that intercellular communication affects the synchronicity of both types of oscillations. To explore the intra-islet synchronization patterns in more detail, we constructed functional connectivity maps. The subsequent comparison of network characteristics of different oscillatory components showed more locally clustered and segregated networks of fast oscillatory activity, while the slow oscillations were more global, resulting in several long-range connections and a more cohesive structure. Besides the structural differences, we found a relatively weak relationship between the fast and slow network layer, which suggests that different synchronization mechanisms shape the collective cellular activity in islets, a finding which has to be kept in mind in future studies employing different oscillations for constructing networks.
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Affiliation(s)
- Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | | | - Rene Markovič
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Education, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
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24
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Chen AW, Jeremic A, Zderic V. Ex Vivo Imaging of Ultrasound-Stimulated Metabolic Activity in Rat Pancreatic Slices. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:666-678. [PMID: 33257101 PMCID: PMC7856007 DOI: 10.1016/j.ultrasmedbio.2020.10.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/23/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
Ultrasound has previously been reported to produce a reversible stimulatory effect in cultured rat beta cells. Here, we quantified and assessed dynamic metabolic changes in an in situ pancreatic slice model evoked by ultrasound application. After plating, pancreas slices were imaged using a confocal microscope at 488 and 633 nm to image lipodamine dehydrogenase (Lip-DH) autofluorescence and a far red fluorescence, respectively. Ultrasound was applied at intensities of 0.5 and 1 W/cm2 at both 800 kHz and 1 MHz. Additionally, 800 kHz at 1 W/cm2 was applied in a pulsing scheme. No ultrasound (control) and glucose application experiments were performed. A difference in fluorescence signal before and after treatment application was the metric for analysis. Comparison of experimental groups using far red fluorescence revealed significant differences between all experimental groups and control in the islet (p < 0.05) and between all ultrasound experimental groups and control (p < 0.05) in pancreatic exocrine tissue. However, this difference in response between control and glucose did not exist in the exocrine tissue. We also observed using Lip-DH autofluorescence that glucose produces a significantly increased metabolic response in islet tissue compared with exocrine tissue (p < 0.05). Pulsed ultrasound appeared to increase metabolic activity in the pancreatic slice in a more consistent manner compared with continuous ultrasound application. Our results indicate that therapeutic ultrasound may have a stimulatory metabolic effect on the pancreatic islets similar to that of glucose.
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Affiliation(s)
- Andrew W Chen
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - Aleksandar Jeremic
- Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Vesna Zderic
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA.
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25
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Corezola do Amaral ME, Kravets V, Dwulet JM, Farnsworth NL, Piscopio R, Schleicher WE, Miranda JG, Benninger RKP. Caloric restriction recovers impaired β-cell-β-cell gap junction coupling, calcium oscillation coordination, and insulin secretion in prediabetic mice. Am J Physiol Endocrinol Metab 2020; 319:E709-E720. [PMID: 32830549 PMCID: PMC7750515 DOI: 10.1152/ajpendo.00132.2020] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 12/16/2022]
Abstract
Caloric restriction can decrease the incidence of metabolic diseases, such as obesity and Type 2 diabetes mellitus. The mechanisms underlying the benefits of caloric restriction involved in insulin secretion and glucose homeostasis are not fully understood. Intercellular communication within the islets of Langerhans, mediated by Connexin36 (Cx36) gap junctions, regulates insulin secretion dynamics and glucose homeostasis. The goal of this study was to determine whether caloric restriction can protect against decreases in Cx36 gap junction coupling and altered islet function induced in models of obesity and prediabetes. C57BL6 mice were fed with a high-fat diet (HFD), showing indications of prediabetes after 2 mo, including weight gain, insulin resistance, and elevated fasting glucose and insulin levels. Subsequently, mice were submitted to 1 mo of 40% caloric restriction (2 g/day of HFD). Mice under 40% caloric restriction showed reversal in weight gain and recovered insulin sensitivity, fasting glucose, and insulin levels. In islets of mice fed the HFD, caloric restriction protected against obesity-induced decreases in gap junction coupling and preserved glucose-stimulated calcium signaling, including Ca2+ oscillation coordination and oscillation amplitude. Caloric restriction also promoted a slight increase in glucose metabolism, as measured by increased NAD(P)H autofluorescence, as well as recovering glucose-stimulated insulin secretion. We conclude that declines in Cx36 gap junction coupling that occur in obesity can be completely recovered by caloric restriction and obesity reversal, improving Ca2+ dynamics and insulin secretion regulation. This suggests a critical role for caloric restriction in the context of obesity to prevent islet dysfunction.
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Affiliation(s)
| | - Vira Kravets
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
| | - JaeAnn M. Dwulet
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
| | - Nikki L. Farnsworth
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
| | - Robert Piscopio
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
| | - Wolfgang E. Schleicher
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
| | - Jose Guadalupe Miranda
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
| | - Richard K. P. Benninger
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Denver, Colorado
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26
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Panzer JK, Hiller H, Cohrs CM, Almaça J, Enos SJ, Beery M, Cechin S, Drotar DM, Weitz JR, Santini J, Huber MK, Muhammad Fahd Qadir M, Pastori RL, Domínguez-Bendala J, Phelps EA, Atkinson MA, Pugliese A, Caicedo A, Kusmartseva I, Speier S. Pancreas tissue slices from organ donors enable in situ analysis of type 1 diabetes pathogenesis. JCI Insight 2020; 5:134525. [PMID: 32324170 DOI: 10.1172/jci.insight.134525] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/19/2020] [Indexed: 12/13/2022] Open
Abstract
In type 1 diabetes (T1D), autoimmune destruction of pancreatic β cells leads to insulin deficiency and loss of glycemic control. However, knowledge about human pancreas pathophysiology in T1D remains incomplete. To address this limitation, we established a pancreas tissue slice platform of donor organs with and without diabetes, facilitating the first live cell studies of human pancreas in T1D pathogenesis to our knowledge. We show that pancreas tissue slices from organ donors allow thorough assessment of processes critical for disease development, including insulin secretion, β cell physiology, endocrine cell morphology, and immune infiltration within the same donor organ. Using this approach, we compared detailed pathophysiological profiles for 4 pancreata from donors with T1D with 19 nondiabetic control donors. We demonstrate that β cell loss, β cell dysfunction, alterations of β cell physiology, and islet infiltration contributed differently to individual cases of T1D, allowing insight into pathophysiology and heterogeneity of T1D pathogenesis. Thus, our study demonstrates that organ donor pancreas tissue slices represent a promising and potentially novel approach in the search for successful prevention and reversal strategies of T1D.
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Affiliation(s)
- Julia K Panzer
- Paul Langerhans Institute Dresden of the Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - Helmut Hiller
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, Florida, USA
| | - Christian M Cohrs
- Paul Langerhans Institute Dresden of the Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - Joana Almaça
- Department of Medicine, Division of Metabolism, Endocrinology and Diabetes, and
| | - Stephen J Enos
- Paul Langerhans Institute Dresden of the Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - Maria Beery
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, Florida, USA
| | - Sirlene Cechin
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Denise M Drotar
- Paul Langerhans Institute Dresden of the Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - John R Weitz
- Department of Medicine, Division of Metabolism, Endocrinology and Diabetes, and
| | - Jorge Santini
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Mollie K Huber
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, Florida, USA.,J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Mirza Muhammad Fahd Qadir
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida, USA.,Department of Cell Biology and Anatomy and
| | - Ricardo L Pastori
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Juan Domínguez-Bendala
- Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida, USA.,Department of Cell Biology and Anatomy and
| | - Edward A Phelps
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA
| | - Mark A Atkinson
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, Florida, USA
| | - Alberto Pugliese
- Department of Medicine, Division of Metabolism, Endocrinology and Diabetes, and.,Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, Florida, USA.,Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Alejandro Caicedo
- Department of Medicine, Division of Metabolism, Endocrinology and Diabetes, and
| | - Irina Kusmartseva
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, Florida, USA
| | - Stephan Speier
- Paul Langerhans Institute Dresden of the Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
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27
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Korošak D, Slak Rupnik M. Random Matrix Analysis of Ca 2+ Signals in β-Cell Collectives. Front Physiol 2019; 10:1194. [PMID: 31620017 PMCID: PMC6759485 DOI: 10.3389/fphys.2019.01194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 09/03/2019] [Indexed: 12/26/2022] Open
Abstract
Even within small organs like pancreatic islets, different endocrine cell types and subtypes form a heterogeneous collective to sense the chemical composition of the extracellular solution and compute an adequate hormonal output. Erroneous cellular processing and hormonal output due to challenged heterogeneity result in various disorders with diabetes mellitus as a flagship metabolic disease. Here we attempt to address the aforementioned functional heterogeneity with comparing pairwise cell-cell cross-correlations obtained from simultaneous measurements of cytosolic calcium responses in hundreds of islet cells in an optical plane to statistical properties of correlations predicted by the random matrix theory (RMT). We find that the bulk of the empirical eigenvalue spectrum is almost completely described by RMT prediction, however, the deviating eigenvalues that exist below and above RMT spectral edges suggest that there are local and extended modes driving the correlations. We also show that empirical nearest neighbor spacing of eigenvalues follows universal RMT properties regardless of glucose stimulation, but that number variance displays clear separation from RMT prediction and can differentiate between empirical spectra obtained under non-stimulated and stimulated conditions. We suggest that RMT approach provides a sensitive tool to assess the functional cell heterogeneity and its effects on the spatio-temporal dynamics of a collective of beta cells in pancreatic islets in physiological resting and stimulatory conditions, beyond the current limitations of molecular and cellular biology.
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Affiliation(s)
- Dean Korošak
- Faculty of Medicine, Institute for Physiology, University of Maribor, Maribor, Slovenia
- Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Faculty of Medicine, Institute for Physiology, University of Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Alma Mater Europaea - European Center Maribor, Maribor, Slovenia
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28
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Loppini A, Chiodo L. Biophysical modeling of β-cells networks: Realistic architectures and heterogeneity effects. Biophys Chem 2019; 254:106247. [PMID: 31472460 DOI: 10.1016/j.bpc.2019.106247] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/06/2019] [Accepted: 08/06/2019] [Indexed: 11/29/2022]
Abstract
The β-cells dynamics is the regulator of insulin secretion in the pancreas, and its investigation is a central aspect in designing effective treatment strategies for diabetes. Despite great efforts, much is still unknown about the complex organization of such endocrine cells and realistic mathematical modeling represents a useful tool to elucidate key aspects of glucose control in humans. In this contribution, we study the human β-cells collective behaviour, by modeling their electric and metabolic coupling in a cluster, of size and architecture similar to human islets of Langerhans. We focus on the effect of coupling on various dynamics regimes observed in the islets, that are spiking and bursting on multiple timescales. In particular, we test the effect of hubs, that are highly glucose-sensitive β-cells, on the overall network dynamics, observing different modulation depending on the timescale of the dynamics. By properly taking into account the role of cells heterogeneity, recently emerged, our model effectively describes the effect of hubs on the synchronization of the islet response and the correlation of β-cells activity.
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Affiliation(s)
- A Loppini
- Department of Engineering, University Campus Bio-Medico of Rome, Via Á. del Portillo 21, 00128 Rome, Italy.
| | - L Chiodo
- Department of Engineering, University Campus Bio-Medico of Rome, Via Á. del Portillo 21, 00128 Rome, Italy
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29
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Gál E, Dolenšek J, Stožer A, Pohorec V, Ébert A, Venglovecz V. A Novel in situ Approach to Studying Pancreatic Ducts in Mice. Front Physiol 2019; 10:938. [PMID: 31396104 PMCID: PMC6668154 DOI: 10.3389/fphys.2019.00938] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/09/2019] [Indexed: 12/19/2022] Open
Abstract
Introduction: The tissue slice technique offers several benefits compared to isolated cells and cell clusters that help us understand the (patho)physiology of several organs in situ. The most prominent features are preserved architecture and function, with intact homotypic and heterotypic interactions between cells in slices. In the pancreas, this technique has been utilized successfully to study acinar and endocrine islet cells. However, it has never been used to investigate ductal function. Since pancreatic ductal epithelial cells (PDECs) play an essential role in the physiology of the pancreas, our aim was to use this technique to study PDEC structure and function in situ. Materials and methods: Eight- to sixteen weeks old C57BL/6 mice were used for preparation of pancreas tissue slices. Low melting point agarose was injected into the common bile duct and the whole organ was extracted. For morphological studies, pieces of tissue were embedded in agarose and cryosectioned to obtain 15 μm thick slices. In order to visualize pancreatic ducts, (i) the Giemsa dye was added to the agarose and visualized using light microscopy or (ii) immunostaining for the cystic fibrosis transmembrane conductance regulator (CFTR) was performed. For functional characterization, agarose-embedded tissue was immediately cut to 140 μm thick tissue slices that were loaded with the cell permeant form of the Oregon Green 488 BAPTA-1 dye and used for confocal calcium imaging. Results: Giemsa staining has shown that the injected agarose reaches the head and body of the pancreas to a greater extent than the tail, without disrupting the tissue architecture. Strong CFTR expression was detected at the apical membranes of PDECs and acinar cells, whereas islet cells were completely negative for CFTR. Stimulation with chenodeoxycholic acid (CDCA, 1 mM) resulted in a robust transient increase in intracellular calcium concentration that was readily visible in >40 ductal cells per slice. Conclusion: Our results confirm that the acutely-isolated pancreas tissue slice technique is suitable for structural and functional investigation of PDECs and their relationship with other cell types, such as acini and endocrine cells in situ. In combination with different genetic, pharmacological or dietary approaches it could become a method of choice in the foreseeable future.
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Affiliation(s)
- Eleonóra Gál
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Jurij Dolenšek
- Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Viljem Pohorec
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Attila Ébert
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
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Stožer A, Markovič R, Dolenšek J, Perc M, Marhl M, Slak Rupnik M, Gosak M. Heterogeneity and Delayed Activation as Hallmarks of Self-Organization and Criticality in Excitable Tissue. Front Physiol 2019; 10:869. [PMID: 31333504 PMCID: PMC6624746 DOI: 10.3389/fphys.2019.00869] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 06/21/2019] [Indexed: 12/14/2022] Open
Abstract
Self-organized critical dynamics is assumed to be an attractive mode of functioning for several real-life systems and entails an emergent activity in which the extent of observables follows a power-law distribution. The hallmarks of criticality have recently been observed in a plethora of biological systems, including beta cell populations within pancreatic islets of Langerhans. In the present study, we systematically explored the mechanisms that drive the critical and supercritical behavior in networks of coupled beta cells under different circumstances by means of experimental and computational approaches. Experimentally, we employed high-speed functional multicellular calcium imaging of fluorescently labeled acute mouse pancreas tissue slices to record calcium signals in a large number of beta cells simultaneously, and with a high spatiotemporal resolution. Our experimental results revealed that the cellular responses to stimulation with glucose are biphasic and glucose-dependent. Under physiological as well as under supraphysiological levels of stimulation, an initial activation phase was followed by a supercritical plateau phase with a high number of global intercellular calcium waves. However, the activation phase displayed fingerprints of critical behavior under lower stimulation levels, with a progressive recruitment of cells and a power-law distribution of calcium wave sizes. On the other hand, the activation phase provoked by pathophysiologically high glucose concentrations, differed considerably and was more rapid, less continuous, and supercritical. To gain a deeper insight into the experimentally observed complex dynamical patterns, we built up a phenomenological model of coupled excitable cells and explored empirically the model’s necessities that ensured a good overlap between computational and experimental results. It turned out that such a good agreement between experimental and computational findings was attained when both heterogeneous and stimulus-dependent time lags, variability in excitability levels, as well as a heterogeneous cell-cell coupling were included into the model. Most importantly, since our phenomenological approach involved only a few parameters, it naturally lends itself not only for determining key mechanisms of self-organized criticality at the tissue level, but also points out various features for comprehensive and realistic modeling of different excitable systems in nature.
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Affiliation(s)
- Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Rene Markovič
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia.,Faculty of Education, University of Maribor, Maribor, Slovenia.,Faculty of Energy Technology, University of Maribor, Krško, Slovenia
| | - Jurij Dolenšek
- Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Matjaž Perc
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia.,Center for Applied Mathematics and Theoretical Physics, University of Maribor, Maribor, Slovenia.,Complexity Science Hub Vienna, Vienna, Austria
| | - Marko Marhl
- Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia.,Faculty of Education, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Institute of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.,Alma Mater Europaea - ECM, Maribor, Slovenia
| | - Marko Gosak
- Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
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31
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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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Spitters TWGM, Andersen PL, Martel C, Vermette P. Multiple-Condition Analysis in a Retrievable Subcutaneous Animal Model for Drug Screening on Full Pancreatic Tissue Digest. Assay Drug Dev Technol 2018; 16:462-471. [PMID: 30106594 DOI: 10.1089/adt.2018.846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The lack of understanding on how to treat pancreas-related diseases and develop new therapeutics is partly due to the unavailability of appropriate models. In vitro models fail to provide a physiological environment. Testing new drug targets in these models can give rise to bias and misleading results. Therefore, we developed an in vivo model for drug testing on full pancreatic digests, which maintains the interactions between endo- and exocrine tissues and allows retrieving the samples for further analyses. The use of full pancreatic digest eliminates the need to isolate islets, reducing time and cost. In this model, four different conditions can be implanted subcutaneously within the same animal. Each condition consists of full pancreatic tissue digests embedded in alginate beads. All alginate beads in one animal contained full pancreatic digest of the same donor and, after 5-day implantation, were retrieved for analysis focusing on survival, function, and/or organization. Proof-of-principle of the platform was evidenced by showing the effect of hyaluronic acid and vascular endothelial growth factor on the overall function of the full pancreatic digest and on endothelial cells in the pancreatic digest, respectively. Retrieval from identical animals allows direct comparison between conditions. Metabolism (MTT) quantification, dithizone staining, and glucose-stimulated insulin secretion assessment allow to discriminate, using a minimal number of animals, between treatments and validate the system. Because of its simplicity, the model is highly adaptable to specific needs of the user.
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Affiliation(s)
- Tim W G M Spitters
- Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke, Canada.,Pharmacology Institute of Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Canada
| | - Parker L Andersen
- Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke, Canada.,Pharmacology Institute of Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Canada
| | - Chloé Martel
- Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke, Canada.,Pharmacology Institute of Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Canada
| | - Patrick Vermette
- Laboratoire de bio-ingénierie et de biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke, Canada.,Pharmacology Institute of Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Canada
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33
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Computational modeling of the effect of temperature variations on human pancreatic β-cell activity. J Therm Biol 2018; 75:69-80. [PMID: 30017054 DOI: 10.1016/j.jtherbio.2018.05.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 05/23/2018] [Accepted: 05/24/2018] [Indexed: 11/22/2022]
Abstract
The effect of temperature variations on the pancreatic β-cell activity and the role of different model compartments in temperature sensing have been investigated using a computational modeling approach. The results of our study show that temperature variations by several degrees can change the dynamical states of the β-cell system. In addition, temperature variations can alter the characteristic features of the membrane voltage, which correlates with insulin secretion. Simulation results show that the ion channels such as the L-type calcium, the hERG potassium, sodium channels and the glycolysis pathway are the possible sites for sensing temperature variation. Results indicate that for a small temperature change, even though the frequency and amplitude of electrical activity are altered, the area under the membrane potential curve remains almost unchanged, which implies the existence of a thermoregulatory mechanism for preserving the amount of insulin secretion. Furthermore, the computational analysis shows that the β-cell electrical activity exhibits a bursting pattern in physiological temperature (37 °C) while in vitro studies reported almost the spiking activity at lower temperatures. Since hormone-secreting systems work more efficient in bursting mode, we propose that the pancreatic β-cell works better in the physiological temperature compared with the reference temperature (33 °C).
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34
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Biological mechanisms beyond network analysis via mathematical modeling. Phys Life Rev 2018; 24:156-158. [DOI: 10.1016/j.plrev.2017.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 12/05/2017] [Indexed: 01/09/2023]
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35
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Gosak M, Markovič R, Dolenšek J, Slak Rupnik M, Marhl M, Stožer A, Perc M. Network science of biological systems at different scales: A review. Phys Life Rev 2018; 24:118-135. [DOI: 10.1016/j.plrev.2017.11.003] [Citation(s) in RCA: 174] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/13/2017] [Accepted: 10/15/2017] [Indexed: 12/20/2022]
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36
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Korošak D, Slak Rupnik M. Collective Sensing of β-Cells Generates the Metabolic Code. Front Physiol 2018; 9:31. [PMID: 29416515 PMCID: PMC5787558 DOI: 10.3389/fphys.2018.00031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/09/2018] [Indexed: 01/24/2023] Open
Abstract
Major part of a pancreatic islet is composed of β-cells that secrete insulin, a key hormone regulating influx of nutrients into all cells in a vertebrate organism to support nutrition, housekeeping or energy storage. β-cells constantly communicate with each other using both direct, short-range interactions through gap junctions, and paracrine long-range signaling. However, how these cell interactions shape collective sensing and cell behavior in islets that leads to insulin release is unknown. When stimulated by specific ligands, primarily glucose, β-cells collectively respond with expression of a series of transient Ca2+ changes on several temporal scales. Here we reanalyze a set of Ca2+ spike trains recorded in acute rodent pancreatic tissue slice under physiological conditions. We found strongly correlated states of co-spiking cells coexisting with mostly weak pairwise correlations widespread across the islet. Furthermore, the collective Ca2+ spiking activity in islet shows on-off intermittency with scaling of spiking amplitudes, and stimulus dependent autoassociative memory features. We use a simple spin glass-like model for the functional network of a β-cell collective to describe these findings and argue that Ca2+ spike trains produced by collective sensing of β-cells constitute part of the islet metabolic code that regulates insulin release and limits the islet size.
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Affiliation(s)
- Dean Korošak
- Institute for Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Maribor, Slovenia.,Percipio Ltd., Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute for Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Center for Physiology and Pharmacology, Institute for Physiology, Medical University of Vienna, Vienna, Austria.,Alma Mater Europaea - European Center Maribor, Maribor, Slovenia
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37
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Gosak M, Stožer A, Markovič R, Dolenšek J, Perc M, Rupnik MS, Marhl M. Critical and Supercritical Spatiotemporal Calcium Dynamics in Beta Cells. Front Physiol 2017; 8:1106. [PMID: 29312008 PMCID: PMC5743929 DOI: 10.3389/fphys.2017.01106] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/14/2017] [Indexed: 01/12/2023] Open
Abstract
A coordinated functioning of beta cells within pancreatic islets is mediated by oscillatory membrane depolarization and subsequent changes in cytoplasmic calcium concentration. While gap junctions allow for intraislet information exchange, beta cells within islets form complex syncytia that are intrinsically nonlinear and highly heterogeneous. To study spatiotemporal calcium dynamics within these syncytia, we make use of computational modeling and confocal high-speed functional multicellular imaging. We show that model predictions are in good agreement with experimental data, especially if a high degree of heterogeneity in the intercellular coupling term is assumed. In particular, during the first few minutes after stimulation, the probability distribution of calcium wave sizes is characterized by a power law, thus indicating critical behavior. After this period, the dynamics changes qualitatively such that the number of global intercellular calcium events increases to the point where the behavior becomes supercritical. To better mimic normal in vivo conditions, we compare the described behavior during supraphysiological non-oscillatory stimulation with the behavior during exposure to a slightly lower and oscillatory glucose challenge. In the case of this protocol, we observe only critical behavior in both experiment and model. Our results indicate that the loss of oscillatory changes, along with the rise in plasma glucose observed in diabetes, could be associated with a switch to supercritical calcium dynamics and loss of beta cell functionality.
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Affiliation(s)
- Marko Gosak
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Rene Markovič
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Education, University of Maribor, Maribor, Slovenia
- Faculty of Energy Technology, University of Maribor, Krško, Slovenia
| | - Jurij Dolenšek
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Matjaž Perc
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Center for Applied Mathematics and Theoretical Physics, University of Maribor, Maribor, Slovenia
- Complexity Science Hub, Vienna, Austria
| | - Marjan S. Rupnik
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Institute of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Education, University of Maribor, Maribor, Slovenia
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Skelin Klemen M, Dolenšek J, Slak Rupnik M, Stožer A. The triggering pathway to insulin secretion: Functional similarities and differences between the human and the mouse β cells and their translational relevance. Islets 2017; 9:109-139. [PMID: 28662366 PMCID: PMC5710702 DOI: 10.1080/19382014.2017.1342022] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In β cells, stimulation by metabolic, hormonal, neuronal, and pharmacological factors is coupled to secretion of insulin through different intracellular signaling pathways. Our knowledge about the molecular machinery supporting these pathways and the patterns of signals it generates comes mostly from rodent models, especially the laboratory mouse. The increased availability of human islets for research during the last few decades has yielded new insights into the specifics in signaling pathways leading to insulin secretion in humans. In this review, we follow the most central triggering pathway to insulin secretion from its very beginning when glucose enters the β cell to the calcium oscillations it produces to trigger fusion of insulin containing granules with the plasma membrane. Along the way, we describe the crucial building blocks that contribute to the flow of information and focus on their functional role in mice and humans and on their translational implications.
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Affiliation(s)
- Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Institute of Physiology; Center for Physiology and Pharmacology; Medical University of Vienna; Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
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Chen C, Cohrs CM, Stertmann J, Bozsak R, Speier S. Human beta cell mass and function in diabetes: Recent advances in knowledge and technologies to understand disease pathogenesis. Mol Metab 2017; 6:943-957. [PMID: 28951820 PMCID: PMC5605733 DOI: 10.1016/j.molmet.2017.06.019] [Citation(s) in RCA: 298] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/31/2017] [Accepted: 06/07/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Plasma insulin levels are predominantly the product of the morphological mass of insulin producing beta cells in the pancreatic islets of Langerhans and the functional status of each of these beta cells. Thus, deficiency in either beta cell mass or function, or both, can lead to insufficient levels of insulin, resulting in hyperglycemia and diabetes. Nonetheless, the precise contribution of beta cell mass and function to the pathogenesis of diabetes as well as the underlying mechanisms are still unclear. In the past, this was largely due to the restricted number of technologies suitable for studying the scarcely accessible human beta cells. However, in recent years, a number of new platforms have been established to expand the available techniques and to facilitate deeper insight into the role of human beta cell mass and function as cause for diabetes and as potential treatment targets. SCOPE OF REVIEW This review discusses the current knowledge about contribution of human beta cell mass and function to different stages of type 1 and type 2 diabetes pathogenesis. Furthermore, it highlights standard and newly developed technological platforms for the study of human beta cell biology, which can be used to increase our understanding of beta cell mass and function in human glucose homeostasis. MAJOR CONCLUSIONS In contrast to early disease models, recent studies suggest that in type 1 and type 2 diabetes impairment of beta cell function is an early feature of disease pathogenesis while a substantial decrease in beta cell mass occurs more closely to clinical manifestation. This suggests that, in addition to beta cell mass replacement for late stage therapies, the development of novel strategies for protection and recovery of beta cell function could be most promising for successful diabetes treatment and prevention. The use of today's developing and wide range of technologies and platforms for the study of human beta cells will allow for a more detailed investigation of the underlying mechanisms and will facilitate development of treatment approaches to specifically target human beta cell mass and function.
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Affiliation(s)
- Chunguang Chen
- Paul Langerhans Institute Dresden (PLID) of Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Christian M. Cohrs
- Paul Langerhans Institute Dresden (PLID) of Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Julia Stertmann
- Paul Langerhans Institute Dresden (PLID) of Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Robert Bozsak
- Paul Langerhans Institute Dresden (PLID) of Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Stephan Speier
- Paul Langerhans Institute Dresden (PLID) of Helmholtz Zentrum München at the University Clinic Carl Gustav Carus of Technische Universität Dresden, Helmholtz Zentrum München, München-Neuherberg, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
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40
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Daraio T, Bombek LK, Gosak M, Valladolid-Acebes I, Klemen MS, Refai E, Berggren PO, Brismar K, Rupnik MS, Bark C. SNAP-25b-deficiency increases insulin secretion and changes spatiotemporal profile of Ca 2+oscillations in β cell networks. Sci Rep 2017; 7:7744. [PMID: 28798351 PMCID: PMC5552776 DOI: 10.1038/s41598-017-08082-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 07/04/2017] [Indexed: 01/02/2023] Open
Abstract
SNAP-25 is a protein of the core SNARE complex mediating stimulus-dependent release of insulin from pancreatic β cells. The protein exists as two alternatively spliced isoforms, SNAP-25a and SNAP-25b, differing in 9 out of 206 amino acids, yet their specific roles in pancreatic β cells remain unclear. We explored the effect of SNAP-25b-deficiency on glucose-stimulated insulin release in islets and found increased secretion both in vivo and in vitro. However, slow photo-release of caged Ca2+ in β cells within pancreatic slices showed no significant differences in Ca2+-sensitivity, amplitude or rate of exocytosis between SNAP-25b-deficient and wild-type littermates. Therefore, we next investigated if Ca2+ handling was affected in glucose-stimulated β cells using intracellular Ca2+-imaging and found premature activation and delayed termination of [Ca2+]i elevations. These findings were accompanied by less synchronized Ca2+-oscillations and hence more segregated functional β cell networks in SNAP-25b-deficient mice. Islet gross morphology and architecture were maintained in mutant mice, although sex specific compensatory changes were observed. Thus, our study proposes that SNAP-25b in pancreatic β cells, except for participating in the core SNARE complex, is necessary for accurate regulation of Ca2+-dynamics.
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Affiliation(s)
- Teresa Daraio
- The Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Lidija Križančić Bombek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000, Maribor, Slovenia.,Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000, Maribor, Slovenia
| | - Ismael Valladolid-Acebes
- The Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000, Maribor, Slovenia
| | - Essam Refai
- The Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Kerstin Brismar
- The Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000, Maribor, Slovenia. .,Center for Physiology and Pharmacology, Medical University of Vienna, A-1090, Vienna, Austria.
| | - Christina Bark
- The Rolf Luft Research Center for Diabetes and Endocrinology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76, Stockholm, Sweden.
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41
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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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42
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Kulkarni RU, Yin H, Pourmandi N, James F, Adil MM, Schaffer DV, Wang Y, Miller EW. A Rationally Designed, General Strategy for Membrane Orientation of Photoinduced Electron Transfer-Based Voltage-Sensitive Dyes. ACS Chem Biol 2017; 12:407-413. [PMID: 28004909 DOI: 10.1021/acschembio.6b00981] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Voltage imaging with fluorescent dyes offers promise for interrogating the complex roles of membrane potential in coordinating the activity of neurons in the brain. Yet, low sensitivity often limits the broad applicability of optical voltage indicators. In this paper, we use molecular dynamics (MD) simulations to guide the design of new, ultrasensitive fluorescent voltage indicators that use photoinduced electron transfer (PeT) as a voltage-sensing switch. MD simulations predict an approximately 16% increase in voltage sensitivity resulting purely from improved alignment of dye with the membrane. We confirm this theoretical finding by synthesizing 9 new voltage-sensitive (VoltageFluor, or VF) dyes and establishing that all of them display the expected improvement of approximately 19%. This synergistic outworking of theory and experiment enabled computational and theoretical estimation of VF dye orientation in lipid bilayers and has yielded the most sensitive PeT-based VF dye to date. We use this new voltage indicator to monitor voltage spikes in neurons from rat hippocampus and human pluripotent-stem-cell-derived dopaminergic neurons.
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Affiliation(s)
| | - Hang Yin
- Shenzhen
Research Institute and Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | | | | | | | | | - Yi Wang
- Shenzhen
Research Institute and Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
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43
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Dolenšek J, Špelič D, Skelin Klemen M, Žalik B, Gosak M, Slak Rupnik M, Stožer A. Membrane Potential and Calcium Dynamics in Beta Cells from Mouse Pancreas Tissue Slices: Theory, Experimentation, and Analysis. SENSORS 2015; 15:27393-419. [PMID: 26516866 PMCID: PMC4701238 DOI: 10.3390/s151127393] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/11/2015] [Accepted: 10/14/2015] [Indexed: 12/17/2022]
Abstract
Beta cells in the pancreatic islets of Langerhans are precise biological sensors for glucose and play a central role in balancing the organism between catabolic and anabolic needs. A hallmark of the beta cell response to glucose are oscillatory changes of membrane potential that are tightly coupled with oscillatory changes in intracellular calcium concentration which, in turn, elicit oscillations of insulin secretion. Both membrane potential and calcium changes spread from one beta cell to the other in a wave-like manner. In order to assess the properties of the abovementioned responses to physiological and pathological stimuli, the main challenge remains how to effectively measure membrane potential and calcium changes at the same time with high spatial and temporal resolution, and also in as many cells as possible. To date, the most wide-spread approach has employed the electrophysiological patch-clamp method to monitor membrane potential changes. Inherently, this technique has many advantages, such as a direct contact with the cell and a high temporal resolution. However, it allows one to assess information from a single cell only. In some instances, this technique has been used in conjunction with CCD camera-based imaging, offering the opportunity to simultaneously monitor membrane potential and calcium changes, but not in the same cells and not with a reliable cellular or subcellular spatial resolution. Recently, a novel family of highly-sensitive membrane potential reporter dyes in combination with high temporal and spatial confocal calcium imaging allows for simultaneously detecting membrane potential and calcium changes in many cells at a time. Since the signals yielded from both types of reporter dyes are inherently noisy, we have developed complex methods of data denoising that permit for visualization and pixel-wise analysis of signals. Combining the experimental approach of high-resolution imaging with the advanced analysis of noisy data enables novel physiological insights and reassessment of current concepts in unprecedented detail.
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Affiliation(s)
- Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
| | - Denis Špelič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (D.Š.); (B.Ž.)
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
| | - Borut Žalik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (D.Š.); (B.Ž.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; E-Mails: (J.D.); (M.S.K.); (M.G.); (M.S.R.)
- Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +386-2-2345843
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44
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Calcium modulation of exocytosis-linked plasma membrane potential oscillations in INS-1 832/13 cells. Biochem J 2015; 471:111-22. [DOI: 10.1042/bj20150616] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/04/2015] [Indexed: 01/17/2023]
Abstract
Oscillations in plasma membrane potential initiated by substrate-dependent blockade of ATP-sensitive K+ channels in insulin-secreting INS-1 832/13 are differentially linked to distinct voltage-activated Ca2+ channels and drive exocytosis. Ca2+ feeds back to control oscillation frequency, amplitude and prevalence.
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45
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Huang YL, Walker AS, Miller EW. A Photostable Silicon Rhodamine Platform for Optical Voltage Sensing. J Am Chem Soc 2015; 137:10767-76. [PMID: 26237573 DOI: 10.1021/jacs.5b06644] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This paper describes the design and synthesis of a photostable, far-red to near-infrared (NIR) platform for optical voltage sensing. We developed a new, sulfonated silicon rhodamine fluorophore and integrated it with a phenylenevinylene molecular wire to create a Berkeley Red Sensor of Transmembrane potential, or BeRST 1 ("burst"). BeRST 1 is the first member of a class of far-red to NIR voltage sensitive dyes that make use of a photoinduced electron transfer (PeT) trigger for optical interrogation of membrane voltage. We show that BeRST 1 displays bright, membrane-localized fluorescence in living cells, high photostability, and excellent voltage sensitivity in neurons. Depolarization of the plasma membrane results in rapid fluorescence increases (24% ΔF/F per 100 mV). BeRST 1 can be used in conjunction with fluorescent stains for organelles, Ca(2+) indicators, and voltage-sensitive fluorescent proteins. In addition, the red-shifted spectral profile of BeRST 1, relative to commonly employed optogenetic actuators like ChannelRhodopsin2 (ChR2), which require blue light, enables optical electrophysiology in neurons. The high speed, sensitivity, photostability and long-wavelength fluorescence profiles of BeRST 1 make it a useful platform for the noninvasive, optical dissection of neuronal activity.
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Affiliation(s)
- Yi-Lin Huang
- Departments of Chemistry, ‡Molecular & Cell Biology, and §Helen Wills Neuroscience Institute, University of California , Berkeley, California 94720, United States
| | - Alison S Walker
- Departments of Chemistry, ‡Molecular & Cell Biology, and §Helen Wills Neuroscience Institute, University of California , Berkeley, California 94720, United States
| | - Evan W Miller
- Departments of Chemistry, ‡Molecular & Cell Biology, and §Helen Wills Neuroscience Institute, University of California , Berkeley, California 94720, United States
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46
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Gosak M, Stožer A, Markovič R, Dolenšek J, Marhl M, Rupnik MS, Perc M. The relationship between node degree and dissipation rate in networks of diffusively coupled oscillators and its significance for pancreatic beta cells. CHAOS (WOODBURY, N.Y.) 2015; 25:073115. [PMID: 26232966 DOI: 10.1063/1.4926673] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Self-sustained oscillatory dynamics is a motion along a stable limit cycle in the phase space, and it arises in a wide variety of mechanical, electrical, and biological systems. Typically, oscillations are due to a balance between energy dissipation and generation. Their stability depends on the properties of the attractor, in particular, its dissipative characteristics, which in turn determine the flexibility of a given dynamical system. In a network of oscillators, the coupling additionally contributes to the dissipation, and hence affects the robustness of the oscillatory solution. Here, we therefore investigate how a heterogeneous network structure affects the dissipation rate of individual oscillators. First, we show that in a network of diffusively coupled oscillators, the dissipation is a linearly decreasing function of the node degree, and we demonstrate this numerically by calculating the average divergence of coupled Hopf oscillators. Subsequently, we use recordings of intracellular calcium dynamics in pancreatic beta cells in mouse acute tissue slices and the corresponding functional connectivity networks for an experimental verification of the presented theory. We use methods of nonlinear time series analysis to reconstruct the phase space and calculate the sum of Lyapunov exponents. Our analysis reveals a clear tendency of cells with a higher degree, that is, more interconnected cells, having more negative values of divergence, thus confirming our theoretical predictions. We discuss these findings in the context of energetic aspects of signaling in beta cells and potential risks for pathological changes in the tissue.
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Affiliation(s)
- Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
| | - Rene Markovič
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marko Marhl
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
| | - Matjaž Perc
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
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47
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Lebreton F, Pirog A, Belouah I, Bosco D, Berney T, Meda P, Bornat Y, Catargi B, Renaud S, Raoux M, Lang J. Slow potentials encode intercellular coupling and insulin demand in pancreatic beta cells. Diabetologia 2015; 58:1291-9. [PMID: 25788295 DOI: 10.1007/s00125-015-3558-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/23/2015] [Indexed: 11/24/2022]
Abstract
AIMS/HYPOTHESIS Ion fluxes constitute a major integrative signal in beta cells that leads to insulin secretion and regulation of gene expression. Understanding these electrical signals is important for deciphering the endogenous algorithms used by islets to attain homeostasis and for the design of new sensors for monitoring beta cell function. METHODS Mouse and human islets were cultured on multielectrode arrays (MEAs) for 3-13 days. Extracellular electrical activities received on each electrode were continuously amplified and recorded for offline characterisation. RESULTS Differential band-pass filtering of MEA recordings of mouse islets showed two extracellular voltage waveforms: action potentials (lasting 40-60 ms) and very robust slow potentials (SPs, lasting 800-1,500 ms), the latter of which have not been described previously. The frequency of SPs directly correlated with glucose concentration, peaked at 10 mmol/l glucose and was further augmented by picomolar concentrations of glucagon-like peptide-1. SPs required the closure of ATP-dependent potassium channels as they were induced by glucose or glibenclamide but were not elicited by KCl-induced depolarisation. Pharmacological tools and the use of beta cell specific knockout mice showed that SPs reflected cell coupling via connexin 36. Moreover, increasing and decreasing glucose ramps showed hysteresis with reduced glucose sensitivity during the decreasing phase. SPs were also observed in human islets and could be continuously recorded over 24 h. CONCLUSIONS/INTERPRETATION This novel electrical signature reflects the syncytial function of the islets and is specific to beta cells. Moreover, the observed hysteresis provides evidence for an endogenous algorithm naturally present in islets to protect against hypoglycaemia.
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Affiliation(s)
- Fanny Lebreton
- CNRS UMR 5248, Chimie et Biologie des Membranes et Nano-objets, Université de Bordeaux, Batiment B14, Allée Geoffroy St Hilaire, CS90063, 33615, Pessac, France
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48
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Rutter GA, Hodson DJ. Beta cell connectivity in pancreatic islets: a type 2 diabetes target? Cell Mol Life Sci 2015; 72:453-467. [PMID: 25323131 PMCID: PMC11113448 DOI: 10.1007/s00018-014-1755-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/30/2014] [Accepted: 10/01/2014] [Indexed: 12/12/2022]
Abstract
Beta cell connectivity describes the phenomenon whereby the islet context improves insulin secretion by providing a three-dimensional platform for intercellular signaling processes. Thus, the precise flow of information through homotypically interconnected beta cells leads to the large-scale organization of hormone release activities, influencing cell responses to glucose and other secretagogues. Although a phenomenon whose importance has arguably been underappreciated in islet biology until recently, a growing number of studies suggest that such cell-cell communication is a fundamental property of this micro-organ. Hence, connectivity may plausibly be targeted by both environmental and genetic factors in type 2 diabetes mellitus (T2DM) to perturb normal beta cell function and insulin release. Here, we review the mechanisms that contribute to beta cell connectivity, discuss how these may fail during T2DM, and examine approaches to restore insulin secretion by boosting cell communication.
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Affiliation(s)
- Guy A Rutter
- Section of Cell Biology, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
| | - David J Hodson
- Section of Cell Biology, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
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49
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Markovič R, Stožer A, Gosak M, Dolenšek J, Marhl M, Rupnik MS. Progressive glucose stimulation of islet beta cells reveals a transition from segregated to integrated modular functional connectivity patterns. Sci Rep 2015; 5:7845. [PMID: 25598507 PMCID: PMC4297961 DOI: 10.1038/srep07845] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 12/16/2014] [Indexed: 01/11/2023] Open
Abstract
Collective beta cell activity in islets of Langerhans is critical for the supply of insulin within an organism. Even though individual beta cells are intrinsically heterogeneous, the presence of intercellular coupling mechanisms ensures coordinated activity and a well-regulated exocytosis of insulin. In order to get a detailed insight into the functional organization of the syncytium, we applied advanced analytical tools from the realm of complex network theory to uncover the functional connectivity pattern among cells composing the intact islet. The procedure is based on the determination of correlations between long temporal traces obtained from confocal functional multicellular calcium imaging of beta cells stimulated in a stepwise manner with a range of physiological glucose concentrations. Our results revealed that the extracted connectivity networks are sparse for low glucose concentrations, whereas for higher stimulatory levels they become more densely connected. Most importantly, for all ranges of glucose concentration beta cells within the islets form locally clustered functional sub-compartments, thereby indicating that their collective activity profiles exhibit a modular nature. Moreover, we show that the observed non-linear functional relationship between different network metrics and glucose concentration represents a well-balanced setup that parallels physiological insulin release.
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Affiliation(s)
- Rene Markovič
- Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, 2000 Maribor, Slovenia
| | - Andraž Stožer
- 1] Institute of Physiology, Faculty of Medicine, University of Maribor, Taborska ulica 8, 2000 Maribor, Slovenia [2] Centre for Open Innovations and Research, University of Maribor, Slomškov trg 15, 2000 Maribor, Slovenia
| | - Marko Gosak
- 1] Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, 2000 Maribor, Slovenia [2] Centre for Open Innovations and Research, University of Maribor, Slomškov trg 15, 2000 Maribor, Slovenia [3] Faculty of Education, University of Maribor, Koroška cesta 160, 2000 Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Taborska ulica 8, 2000 Maribor, Slovenia
| | - Marko Marhl
- 1] Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, 2000 Maribor, Slovenia [2] Centre for Open Innovations and Research, University of Maribor, Slomškov trg 15, 2000 Maribor, Slovenia [3] Faculty of Education, University of Maribor, Koroška cesta 160, 2000 Maribor, Slovenia
| | - Marjan Slak Rupnik
- 1] Institute of Physiology, Faculty of Medicine, University of Maribor, Taborska ulica 8, 2000 Maribor, Slovenia [2] Centre for Open Innovations and Research, University of Maribor, Slomškov trg 15, 2000 Maribor, Slovenia [3] Institute of Physiology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraβe 17, A-1090 Vienna, Austria
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50
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Dolenšek J, Rupnik MS, Stožer A. Structural similarities and differences between the human and the mouse pancreas. Islets 2015; 7:e1024405. [PMID: 26030186 PMCID: PMC4589993 DOI: 10.1080/19382014.2015.1024405] [Citation(s) in RCA: 202] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 02/08/2023] Open
Abstract
Mice remain the most studied animal model in pancreas research. Since the findings of this research are typically extrapolated to humans, it is important to understand both similarities and differences between the 2 species. Beside the apparent difference in size and macroscopic organization of the organ in the 2 species, there are a number of less evident and only recently described differences in organization of the acinar and ductal exocrine tissue, as well as in the distribution, composition, and architecture of the endocrine islets of Langerhans. Furthermore, the differences in arterial, venous, and lymphatic vessels, as well as innervation are potentially important. In this article, the structure of the human and the mouse pancreas, together with the similarities and differences between them are reviewed in detail in the light of conceivable repercussions for basic research and clinical application.
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Affiliation(s)
- Jurij Dolenšek
- Institute of Physiology; Faculty of Medicine; University of Maribor; Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology; Faculty of Medicine; University of Maribor; Maribor, Slovenia
- Centre for Open Innovations and Research Core@UM; University of Maribor; Maribor, Slovenia
- Institute of Physiology; Center for Physiology and Pharmacology; Medical University of Vienna; Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology; Faculty of Medicine; University of Maribor; Maribor, Slovenia
- Centre for Open Innovations and Research Core@UM; University of Maribor; Maribor, Slovenia
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