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Jevon D, Cottle L, Hallahan N, Harwood R, Samra JS, Gill AJ, Loudovaris T, Thomas HE, Thorn P. Capillary contact points determine beta cell polarity, control secretion and are disrupted in the db/db mouse model of diabetes. Diabetologia 2024; 67:1683-1697. [PMID: 38814445 PMCID: PMC11343897 DOI: 10.1007/s00125-024-06180-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 03/26/2024] [Indexed: 05/31/2024]
Abstract
AIMS/HYPOTHESIS Almost all beta cells contact one capillary and insulin granule fusion is targeted to this region. However, there are reports of beta cells contacting more than one capillary. We therefore set out to determine the proportion of beta cells with multiple contacts and the impact of this on cell structure and function. METHODS We used pancreatic slices in mice and humans to better maintain cell and islet structure than in isolated islets. Cell structure was assayed using immunofluorescence and 3D confocal microscopy. Live-cell two-photon microscopy was used to map granule fusion events in response to glucose stimulation. RESULTS We found that 36% and 22% of beta cells in islets from mice and humans, respectively, have separate contact with two capillaries. These contacts establish a distinct form of cell polarity with multiple basal regions. Both capillary contact points are enriched in presynaptic scaffold proteins, and both are a target for insulin granule fusion. Cells with two capillary contact points have a greater capillary contact area and secrete more, with analysis showing that, independent of the number of contact points, increased contact area is correlated with increased granule fusion. Using db/db mice as a model for type 2 diabetes, we observed changes in islet capillary organisation that significantly reduced total islet capillary surface area, and reduced area of capillary contact in single beta cells. CONCLUSIONS/INTERPRETATION Beta cells that contact two capillaries are a significant subpopulation of beta cells within the islet. They have a distinct form of cell polarity and both contact points are specialised for secretion. The larger capillary contact area of cells with two contact points is correlated with increased secretion. In the db/db mouse, changes in capillary structure impact beta cell capillary contact, implying that this is a new factor contributing to disease progression.
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Affiliation(s)
- Dillon Jevon
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Louise Cottle
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Nicole Hallahan
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Richard Harwood
- Charles Perkins Centre, Sydney Microscopy and Microanalysis, University of Sydney, Camperdown, NSW, Australia
| | - Jaswinder S Samra
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Anthony J Gill
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Department of Anatomical Pathology, Royal North Shore Hospital, St Leonards, NSW, Australia
- Cancer Diagnosis and Pathology Research Group, Kolling Institute of Medical Research, St Leonards, NSW, Australia
| | | | - Helen E Thomas
- St Vincent's Institute, Fitzroy, VIC, Australia
- Department of Medicine, St Vincent's Hospital, University of Melbourne, Fitzroy, VIC, Australia
| | - Peter Thorn
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia.
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2
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Lee EY, Hughes JW. Rediscovering Primary Cilia in Pancreatic Islets. Diabetes Metab J 2023; 47:454-469. [PMID: 37105527 PMCID: PMC10404530 DOI: 10.4093/dmj.2022.0442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/15/2023] [Indexed: 04/29/2023] Open
Abstract
Primary cilia are microtubule-based sensory and signaling organelles on the surfaces of most eukaryotic cells. Despite their early description by microscopy studies, islet cilia had not been examined in the functional context until recent decades. In pancreatic islets as in other tissues, primary cilia facilitate crucial developmental and signaling pathways in response to extracellular stimuli. Many human developmental and genetic disorders are associated with ciliary dysfunction, some manifesting as obesity and diabetes. Understanding the basis for metabolic diseases in human ciliopathies has been aided by close examination of cilia action in pancreatic islets at cellular and molecular levels. In this article, we review the evidence for ciliary expression on islet cells, known roles of cilia in pancreas development and islet hormone secretion, and summarize metabolic manifestations of human ciliopathy syndromes. We discuss emerging data on primary cilia regulation of islet cell signaling and the structural basis of cilia-mediated cell crosstalk, and offer our interpretation on the role of cilia in glucose homeostasis and human diseases.
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Affiliation(s)
- Eun Young Lee
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Jing W. Hughes
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
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3
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Polino AJ, Sviben S, Melena I, Piston DW, Hughes JW. Scanning electron microscopy of human islet cilia. Proc Natl Acad Sci U S A 2023; 120:e2302624120. [PMID: 37205712 PMCID: PMC10235940 DOI: 10.1073/pnas.2302624120] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/12/2023] [Indexed: 05/21/2023] Open
Abstract
Human islet primary cilia are vital glucose-regulating organelles whose structure remains uncharacterized. Scanning electron microscopy (SEM) is a useful technique for studying the surface morphology of membrane projections like cilia, but conventional sample preparation does not reveal the submembrane axonemal structure, which holds key implications for ciliary function. To overcome this challenge, we combined SEM with membrane-extraction techniques to examine primary cilia in native human islets. Our data show well-preserved cilia subdomains which demonstrate both expected and unexpected ultrastructural motifs. Morphometric features were quantified when possible, including axonemal length and diameter, microtubule conformations, and chirality. We further describe a ciliary ring, a structure that may be a specialization in human islets. Key findings are correlated with fluorescence microscopy and interpreted in the context of cilia function as a cellular sensor and communications locus in pancreatic islets.
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Affiliation(s)
- Alexander J. Polino
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO63110
| | - Sanja Sviben
- Washington University Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO63110
| | - Isabella Melena
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO63110
| | - David W. Piston
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO63110
| | - Jing W. Hughes
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO63110
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO63110
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4
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Polino AJ, Sviben S, Melena I, Piston DW, Hughes J. Scanning electron microscopy of human islet cilia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.15.528685. [PMID: 36824775 PMCID: PMC9949088 DOI: 10.1101/2023.02.15.528685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Human islet primary cilia are vital glucose-regulating organelles whose structure remains uncharacterized. Scanning electron microscopy (SEM) is a useful technique for studying the surface morphology of membrane projections like primary cilia, but conventional sample preparation does not reveal the sub-membrane axonemal structure which holds key implications for cilia function. To overcome this challenge, we combined SEM with membrane-extraction techniques to examine cilia in native human islets. Our data show well-preserved cilia subdomains which demonstrate both expected and unexpected ultrastructural motifs. Morphometric features were quantified when possible, including axonemal length and diameter, microtubule conformations and chirality. We further describe a novel ciliary ring, a structure that may be a specialization in human islets. Key findings are correlated with fluorescence microscopy and interpreted in the context of cilia function as a cellular sensor and communications locus in pancreatic islets.
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5
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Melena I, Hughes JW. Islet cilia and glucose homeostasis. Front Cell Dev Biol 2022; 10:1082193. [PMID: 36531945 PMCID: PMC9751591 DOI: 10.3389/fcell.2022.1082193] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 11/22/2022] [Indexed: 09/05/2023] Open
Abstract
Diabetes is a growing pandemic affecting over ten percent of the U.S. population. Individuals with all types of diabetes exhibit glucose dysregulation due to altered function and coordination of pancreatic islets. Within the critical intercellular space in pancreatic islets, the primary cilium emerges as an important physical structure mediating cell-cell crosstalk and signal transduction. Many events leading to hormone secretion, including GPCR and second-messenger signaling, are spatiotemporally regulated at the level of the cilium. In this review, we summarize current knowledge of cilia action in islet hormone regulation and glucose homeostasis, focusing on newly implicated ciliary pathways that regulate insulin exocytosis and intercellular communication. We present evidence of key signaling proteins on islet cilia and discuss ways in which cilia might functionally connect islet endocrine cells with the non-endocrine compartments. These discussions aim to stimulate conversations regarding the extent of cilia-controlled glucose homeostasis in health and in metabolic diseases.
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Affiliation(s)
| | - Jing W. Hughes
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
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6
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Cho JH, Hughes JW. Cilia Action in Islets: Lessons From Mouse Models. Front Endocrinol (Lausanne) 2022; 13:922983. [PMID: 35813631 PMCID: PMC9260721 DOI: 10.3389/fendo.2022.922983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 05/23/2022] [Indexed: 11/30/2022] Open
Abstract
Primary cilia as a signaling organelle have garnered recent attention as a regulator of pancreatic islet function. These rod-like sensors exist on all major islet endocrine cell types and transduce a variety of external cues, while dysregulation of cilia function contributes to the development of diabetes. The complex role of islet primary cilia has been examined using genetic deletion targeting various components of cilia. In this review, we summarize experimental models for the study of islet cilia and current understanding of mechanisms of cilia regulation of islet hormone secretion. Consensus from these studies shows that pancreatic cilia perturbation can cause both endocrine and exocrine defects that are relevant to human disease. We discuss future research directions that would further elucidate cilia action in distinct groups of islet cells, including paracrine and juxtacrine regulation, GPCR signaling, and endocrine-exocrine crosstalk.
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Affiliation(s)
| | - Jing W. Hughes
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
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7
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Super-Resolution Imaging of the Actin Cytoskeleton in Living Cells Using TIRF-SIM. Methods Mol Biol 2021. [PMID: 34542846 DOI: 10.1007/978-1-0716-1661-1_1] [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: 08/06/2023]
Abstract
Super-resolution (SR) imaging techniques have advanced rapidly in recent years, but only a subset of these techniques is gentle enough to be used by cell biologists to study living cells with minimal photodamage. Our research is focused on studies of the dynamic remodeling of the actin cytoskeleton in living pancreatic beta cells during insulin secretion. These studies require super-resolution light microscopic techniques that are gentle enough to record rapid changes of the actin cytoskeleton in real time. In this chapter, we describe an SR technique that breaks the diffraction limit of the conventional light microscope called TIRF-SIM. Using this SR techniques, we have been able to show that (1) microvilli on pancreatic beta cells translocate in the plane of the plasma membrane and (2) the cortical actin network reorganizes when cells are stimulated to secrete insulin. We describe the FIJI plugins that were used to process and analyze the TIRF-SIM images to obtain quantitative data.
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8
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Zhao R, Lu J, Li Q, Xiong F, Zhang Y, Zhu J, Peng G, Yang J. Single-cell heterogeneity analysis and CRISPR screens in MIN6 cell line reveal transcriptional regulators of insulin. Cell Cycle 2021; 20:2053-2065. [PMID: 34494921 DOI: 10.1080/15384101.2021.1969204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Diabetes mellitus is caused by either insulin resistance or insulin deficiency. The pancreatic β cells are the primary producers of insulin. Large-scale CRISPR screens combined with single-cell RNA sequencing (scRNA-seq) on β cells has identified novel insulin regulators and revealed the presence of a highly complex inner network. Here, we performed pooled CRISPR delivery with single-cell transcriptome analysis on the MIN6 cell line, a pancreatic β-cell line. We have presented the scRNA-seq readout and demonstrated that the MIN6 cell line might develop genetic heterogeneity with increasing passage number based on GO and KEGG pathway analysis. Both computational and biological analyses revealed that the function of MIN6 cell lines could be divided into five clusters, including endocrine cells, basal cells, epithelial cells, and neuroendocrine cells. The fifth cluster was different from the other four clusters due to the differentially expressed insulin transcription and was called the lncRNA-enriched cluster. The experiments also confirmed that uncharacterized lncRNAs GM26917 and Cenpw were associated with insulin transcription. This study provides information that can be used to systematically characterize insulin regulator genes and other genes that control protein folding and vesicle trafficking.
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Affiliation(s)
- Ruxuan Zhao
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing China
| | - Jing Lu
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing China
| | - Qi Li
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing China
| | - Fengran Xiong
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing China
| | - Yingchao Zhang
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing China
| | - Juanjuan Zhu
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing China
| | - Gongxin Peng
- Center for Bioinformatics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Jinkui Yang
- Beijing Key Laboratory of Diabetes Research and Care, Beijing Tongren Hospital, Capital Medical University, Beijing China
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Cottle L, Gilroy I, Deng K, Loudovaris T, Thomas HE, Gill AJ, Samra JS, Kebede MA, Kim J, Thorn P. Machine Learning Algorithms, Applied to Intact Islets of Langerhans, Demonstrate Significantly Enhanced Insulin Staining at the Capillary Interface of Human Pancreatic β Cells. Metabolites 2021; 11:metabo11060363. [PMID: 34200432 PMCID: PMC8229564 DOI: 10.3390/metabo11060363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 11/16/2022] Open
Abstract
Pancreatic β cells secrete the hormone insulin into the bloodstream and are critical in the control of blood glucose concentrations. β cells are clustered in the micro-organs of the islets of Langerhans, which have a rich capillary network. Recent work has highlighted the intimate spatial connections between β cells and these capillaries, which lead to the targeting of insulin secretion to the region where the β cells contact the capillary basement membrane. In addition, β cells orientate with respect to the capillary contact point and many proteins are differentially distributed at the capillary interface compared with the rest of the cell. Here, we set out to develop an automated image analysis approach to identify individual β cells within intact islets and to determine if the distribution of insulin across the cells was polarised. Our results show that a U-Net machine learning algorithm correctly identified β cells and their orientation with respect to the capillaries. Using this information, we then quantified insulin distribution across the β cells to show enrichment at the capillary interface. We conclude that machine learning is a useful analytical tool to interrogate large image datasets and analyse sub-cellular organisation.
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Affiliation(s)
- Louise Cottle
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown 2006, Australia
| | - Ian Gilroy
- School of Computer Science, University of Sydney, Camperdown 2006, Australia
| | - Kylie Deng
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown 2006, Australia
| | | | - Helen E Thomas
- St Vincent's Institute, Fitzroy 3065, Australia
- Department of Medicine, St Vincent's Hospital, University of Melbourne, Fitzroy 3065, Australia
| | - Anthony J Gill
- Northern Clinical School, University of Sydney, St Leonards 2065, Australia
- Department of Anatomical Pathology, Royal North Shore Hospital, St Leonards 2065, Australia
- Cancer Diagnosis and Pathology Research Group, Kolling Institute of Medical Research, St Leonards 2065, Australia
| | - Jaswinder S Samra
- Northern Clinical School, University of Sydney, St Leonards 2065, Australia
- Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, St Leonards 2065, Australia
| | - Melkam A Kebede
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown 2006, Australia
| | - Jinman Kim
- School of Computer Science, University of Sydney, Camperdown 2006, Australia
| | - Peter Thorn
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown 2006, Australia
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10
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Cottle L, Gan WJ, Gilroy I, Samra JS, Gill AJ, Loudovaris T, Thomas HE, Hawthorne WJ, Kebede MA, Thorn P. Structural and functional polarisation of human pancreatic beta cells in islets from organ donors with and without type 2 diabetes. Diabetologia 2021; 64:618-629. [PMID: 33399909 PMCID: PMC7864831 DOI: 10.1007/s00125-020-05345-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/09/2020] [Indexed: 12/05/2022]
Abstract
AIMS/HYPOTHESIS We hypothesised that human beta cells are structurally and functional polarised with respect to the islet capillaries. We set out to test this using confocal microscopy to map the 3D spatial arrangement of key proteins and live-cell imaging to determine the distribution of insulin granule fusion around the cells. METHODS Human pancreas samples were rapidly fixed and processed using the pancreatic slice technique, which maintains islet structure and architecture. Slices were stained using immunofluorescence for polarity markers (scribble, discs large [Dlg] and partitioning defective 3 homologue [Par3]) and presynaptic markers (liprin, Rab3-interacting protein [RIM2] and piccolo) and imaged using 3D confocal microscopy. Isolated human islets were dispersed and cultured on laminin-511-coated coverslips. Live 3D two-photon microscopy was used on cultured cells to image exocytic granule fusion events upon glucose stimulation. RESULTS Assessment of the distribution of endocrine cells across human islets found that, despite distinct islet-to-islet complexity and variability, including multi-lobular islets, and intermixing of alpha and beta cells, there is still a striking enrichment of alpha cells at the islet mantle. Measures of cell position demonstrate that most beta cells contact islet capillaries. Subcellularly, beta cells consistently position polar determinants, such as Par3, Dlg and scribble, with a basal domain towards the capillaries and apical domain at the opposite face. The capillary interface/vascular face is enriched in presynaptic scaffold proteins, such as liprin, RIM2 and piccolo. Interestingly, enrichment of presynaptic scaffold proteins also occurs where the beta cells contact peri-islet capillaries, suggesting functional interactions. We also observed the same polarisation of synaptic scaffold proteins in islets from type 2 diabetic patients. Consistent with polarised function, isolated beta cells cultured onto laminin-coated coverslips target insulin granule fusion to the coverslip. CONCLUSIONS/INTERPRETATION Structural and functional polarisation is a defining feature of human pancreatic beta cells and plays an important role in the control of insulin secretion.
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Affiliation(s)
- Louise Cottle
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Wan Jun Gan
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
- Temasek Life-Science Laboratory, Singapore, Republic of Singapore
| | - Ian Gilroy
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Jaswinder S Samra
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Anthony J Gill
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Department of Anatomical Pathology, Royal North Shore Hospital, St Leonards, NSW, Australia
- Cancer Diagnosis and Pathology Research Group, Kolling Institute of Medical Research, St Leonards, NSW, Australia
| | | | - Helen E Thomas
- St Vincent's Institute, Fitzroy, VIC, Australia
- The University of Melbourne, Department of Medicine, St Vincent's Hospital, Fitzroy, VIC, Australia
| | - Wayne J Hawthorne
- Centre for Transplant and Renal Research, Westmead Hospital, Sydney, NSW, Australia
- Westmead Clinical School, Faculty of Health and Medicine, University of Sydney, Sydney, Australia
| | - Melkam A Kebede
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Peter Thorn
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia.
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11
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Over 60 Years of Experimental Hematology (without a License). Exp Hematol 2020; 89:1-12. [PMID: 32798645 DOI: 10.1016/j.exphem.2020.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 11/21/2022]
Abstract
I am deeply honored to receive the International Society for Experimental Hematology (ISEH) 2020 Donald Metcalf Lecture Award. Although I am not a physician and have had no formal training in hematology, I have had the privilege of working with some of the top hematologists in the world, beginning in 1970 when Dr. David Nathan was a sabbatical visitor in my laboratory and introduced me to hematological diseases. And I take this award to be given not just to me but to an exceptional group of MD and PhD trainees and visitors in my laboratory who have cloned and characterized many proteins and RNAs important for red cell development and function. Many of these projects involved taking exceptionally large risks in developing and employing novel experimental technologies. Unsurprisingly, all of these trainees have gone on to become leaders in hematology and, more broadly, in molecular cell biology and molecular medicine. To illustrate some of the challenges we have faced and the technologies we had to develop, I have chosen several of our multiyear projects to describe in some detail: elucidating the regulation of translation of α- and β-globin mRNAs and the defect in beta thalassemia in the 1970s; cloning the Epo receptor and several red cell membrane proteins in the 1980s and 1990s; and more recently, determining the function of many microRNAs and long noncoding RNAs in red cell development. I summarize how we are currently utilizing single-cell transcriptomics (scRNAseq) to understand how dividing transit-amplifying burst-forming unit erythroid progenitors balance the need for more progenitor cells with the need for terminally differentiated erythroid cells, and to identify drugs potentially useful in treating Epo-resistant anemias such as Diamond Blackfan anemia. I hope that the lessons I learned in managing these diverse fellows and projects, initially without having grants to support them, will be helpful to others who would like to undertake ambitious and important lines of research in hematology.
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12
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Ohara-Imaizumi M, Aoyagi K, Ohtsuka T. Role of the active zone protein, ELKS, in insulin secretion from pancreatic β-cells. Mol Metab 2020; 27S:S81-S91. [PMID: 31500835 PMCID: PMC6768504 DOI: 10.1016/j.molmet.2019.06.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Background Insulin is stored within large dense-core granules in pancreatic beta (β)-cells and is released by Ca2+-triggered exocytosis with increasing blood glucose levels. Polarized and targeted secretion of insulin from β-cells in pancreatic islets into the vasculature has been proposed; however, the mechanisms related to cellular and molecular localization remain largely unknown. Within nerve terminals, the Ca2+-dependent release of a polarized transmitter is limited to the active zone, a highly specialized area of the presynaptic membrane. Several active zone-specific proteins have been characterized; among them, the CAST/ELKS protein family members have the ability to form large protein complexes with other active zone proteins to control the structure and function of the active zone for tight regulation of neurotransmitter release. Notably, ELKS but not CAST is also expressed in β-cells, implying that ELKS may be involved in polarized insulin secretion from β-cells. Scope of review This review provides an overview of the current findings regarding the role(s) of ELKS and other active zone proteins in β-cells and focuses on the molecular mechanism underlying ELKS regulation within polarized insulin secretion from islets. Major conclusions ELKS localizes at the vascular-facing plasma membrane of β-cells in mouse pancreatic islets. ELKS forms a potent insulin secretion complex with L-type voltage-dependent Ca2+ channels on the vascular-facing plasma membrane of β-cells, enabling polarized Ca2+ influx and first-phase insulin secretion from islets. This model provides novel insights into the functional polarity observed during insulin secretion from β-cells within islets at the molecular level. This active zone-like region formed by ELKS at the vascular side of the plasma membrane is essential for coordinating physiological insulin secretion and may be disrupted in diabetes.
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Affiliation(s)
- Mica Ohara-Imaizumi
- Department of Cellular Biochemistry, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
| | - Kyota Aoyagi
- Department of Cellular Biochemistry, Kyorin University School of Medicine, Tokyo 181-8611, Japan
| | - Toshihisa Ohtsuka
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
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ELKS/Voltage-Dependent Ca 2+ Channel-β Subunit Module Regulates Polarized Ca 2+ Influx in Pancreatic β Cells. Cell Rep 2020; 26:1213-1226.e7. [PMID: 30699350 DOI: 10.1016/j.celrep.2018.12.106] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 10/29/2018] [Accepted: 12/27/2018] [Indexed: 12/14/2022] Open
Abstract
Pancreatic β cells secrete insulin by Ca2+-triggered exocytosis. However, there is no apparent secretory site similar to the neuronal active zones, and the cellular and molecular localization mechanism underlying polarized exocytosis remains elusive. Here, we report that ELKS, a vertebrate active zone protein, is used in β cells to regulate Ca2+ influx for insulin secretion. β cell-specific ELKS-knockout (KO) mice showed impaired glucose-stimulated first-phase insulin secretion and reduced L-type voltage-dependent Ca2+ channel (VDCC) current density. In situ Ca2+ imaging of β cells within islets expressing a membrane-bound G-CaMP8b Ca2+ sensor demonstrated initial local Ca2+ signals at the ELKS-localized vascular side of the β cell plasma membrane, which were markedly decreased in ELKS-KO β cells. Mechanistically, ELKS directly interacted with the VDCC-β subunit via the GK domain. These findings suggest that ELKS and VDCCs form a potent insulin secretion complex at the vascular side of the β cell plasma membrane for polarized Ca2+ influx and first-phase insulin secretion from pancreatic islets.
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14
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Alessandra G, Algerta M, Paola M, Carsten S, Cristina L, Paolo M, Elisa M, Gabriella T, Carla P. Shaping Pancreatic β-Cell Differentiation and Functioning: The Influence of Mechanotransduction. Cells 2020; 9:E413. [PMID: 32053947 PMCID: PMC7072458 DOI: 10.3390/cells9020413] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/29/2020] [Accepted: 02/07/2020] [Indexed: 02/08/2023] Open
Abstract
Embryonic and pluripotent stem cells hold great promise in generating β-cells for both replacing medicine and novel therapeutic discoveries in diabetes mellitus. However, their differentiation in vitro is still inefficient, and functional studies reveal that most of these β-like cells still fail to fully mirror the adult β-cell physiology. For their proper growth and functioning, β-cells require a very specific environment, the islet niche, which provides a myriad of chemical and physical signals. While the nature and effects of chemical stimuli have been widely characterized, less is known about the mechanical signals. We here review the current status of knowledge of biophysical cues provided by the niche where β-cells normally live and differentiate, and we underline the possible machinery designated for mechanotransduction in β-cells. Although the regulatory mechanisms remain poorly understood, the analysis reveals that β-cells are equipped with all mechanosensors and signaling proteins actively involved in mechanotransduction in other cell types, and they respond to mechanical cues by changing their behavior. By engineering microenvironments mirroring the biophysical niche properties it is possible to elucidate the β-cell mechanotransductive-regulatory mechanisms and to harness them for the promotion of β-cell differentiation capacity in vitro.
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Affiliation(s)
- Galli Alessandra
- Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20134 Milan, Italy
| | - Marku Algerta
- Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20134 Milan, Italy
| | - Marciani Paola
- Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20134 Milan, Italy
| | - Schulte Carsten
- CIMAINA, Department of Physics, Università degli Studi di Milano, 20133 Milan, Italy
| | - Lenardi Cristina
- CIMAINA, Department of Physics, Università degli Studi di Milano, 20133 Milan, Italy
| | - Milani Paolo
- CIMAINA, Department of Physics, Università degli Studi di Milano, 20133 Milan, Italy
| | - Maffioli Elisa
- Department of Veterinary Medicine, Università degli Studi di Milano, 20133 Milan, Italy
| | - Tedeschi Gabriella
- Department of Veterinary Medicine, Università degli Studi di Milano, 20133 Milan, Italy
| | - Perego Carla
- Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20134 Milan, Italy
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15
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Gan WJ, Do OH, Cottle L, Ma W, Kosobrodova E, Cooper-White J, Bilek M, Thorn P. Local Integrin Activation in Pancreatic β Cells Targets Insulin Secretion to the Vasculature. Cell Rep 2019; 24:2819-2826.e3. [PMID: 30208309 DOI: 10.1016/j.celrep.2018.08.035] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 07/20/2018] [Accepted: 08/13/2018] [Indexed: 01/10/2023] Open
Abstract
The extracellular matrix (ECM) critically affects β cell functions via integrin activation. But whether these ECM actions drive the spatial organization of β cells, as they do in epithelial cells, is unknown. Here, we show that within islets of Langerhans, focal adhesion activation in β cells occurs exclusively where they contact the capillary ECM (vascular face). In cultured β cells, 3D mapping shows enriched insulin granule fusion where the cells contact ECM-coated coverslips, which depends on β1 integrin receptor activation. Culture on micro-contact printed stripes of E-cadherin and fibronectin shows that β cell contact at the fibronectin stripe selectively activates focal adhesions and enriches exocytic machinery and insulin granule fusion. Culture of cells in high glucose, as a model of glucotoxicity, abolishes granule targeting. We conclude that local integrin activation targets insulin secretion to the islet capillaries. This mechanism might be important for islet function and may change in disease.
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Affiliation(s)
- Wan Jun Gan
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Oanh Hoang Do
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Louise Cottle
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Wei Ma
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Elena Kosobrodova
- School of Physics, University of Sydney, Camperdown, NSW 2006, Australia
| | - Justin Cooper-White
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Marcela Bilek
- School of Physics, University of Sydney, Camperdown, NSW 2006, Australia; School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Camperdown, NSW 2006, Australia; Sydney Nanoscience Institute, University of Sydney, Camperdown, NSW 2006, Australia
| | - Peter Thorn
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia.
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16
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Lammert E, Thorn P. The Role of the Islet Niche on Beta Cell Structure and Function. J Mol Biol 2019; 432:1407-1418. [PMID: 31711959 DOI: 10.1016/j.jmb.2019.10.032] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 01/15/2023]
Abstract
The islets of Langerhans or pancreatic islets are pivotal in the control of blood glucose and are complex microorgans embedded within the larger volume of the exocrine pancreas. Humans can have ~3.2 million islets [1] which, to our current knowledge, function in a similar manner to sense circulating blood glucose levels and respond with the secretion of a mix of different hormones that act to maintain glucose concentrations around a specific set point [2]. At a cellular level, the control of hormone secretion by glucose and other secretagogues is well-understood [3]. The key signal cascades have been identified and many details of the secretory process are known. However, if we shift focus from single cells and consider cells within intact islets, we do not have a comprehensive model as to how the islet environment influences cell function and how the islets work as a whole. This is important because there is overwhelming evidence that the structure and function of the individual endocrine cells are dramatically affected by the islet environment [4,5]. Uncovering the influence of this islet niche might drive future progress in treatments for Type 2 diabetes [6] and cell replacement therapies for Type 1 diabetes [7]. In this review, we focus on the insulin secreting beta cells and their interactions with the immediate environment that surrounds them including endocrine-endocrine interactions and contacts with capillaries.
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Affiliation(s)
- Eckhard Lammert
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany; Institute for Vascular and Islet Cell Biology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University, Düsseldorf, Germany; German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
| | - Peter Thorn
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW 2006, Australia.
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17
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Gallego FQ, Miranda CA, Sinzato YK, Iessi IL, Dallaqua B, Pando RH, Rocha NS, Volpato GT, Damasceno DC. Temporal analysis of distribution pattern of islet cells and antioxidant enzymes for diabetes onset in postnatal critical development window in rats. Life Sci 2019; 226:57-67. [PMID: 30930115 DOI: 10.1016/j.lfs.2019.03.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/12/2019] [Accepted: 03/25/2019] [Indexed: 12/22/2022]
Abstract
AIM At performing a temporal analysis of the distribution pattern of islet endocrine cells and antioxidant enzymes in diabetic rats during the post-natal critical development window. MAIN METHODS The newborns received streptozotocin (STZ) at birth for diabetes induction, and control females received the vehicle. The animals were euthanized at different lifetimes: D5, D10, D15, and D30. Morphological analysis of pancreas and biochemical assays was performed. KEY FINDINGS The STZ-induced rats presented irregular shape of islet on D5 and there was an attempt to restore of this shape in other life moment studied. There was an increase progressive in islet area, however they maintained smaller than those of control rats, with lower labeling intensity for insulin, higher for glucagon and somatostatin, lower for SOD-1 was lower in the islets of the STZ-induced animals at all times studied and for GSH-Px in D10 and D30. SIGNIFICANCE Although STZ-induced diabetic rats presented compensatory mechanisms to restore the mass of endocrine cells, this was not sufficient since these rats developed the diabetic state. This was confirmed by the oral glucose tolerance test from D30. In addition, the delta (δ)-cells presented ectopic location in islets, indicating a possible relationship for beta (β)-cell mass restoration. There was a response of the pancreas to reduce the hyperglycemia in the first month of life. Furthermore, the cells from the endocrine pancreas of diabetic animals show a decline of antioxidant enzymatic, contributing to the increased susceptibility of cells to hyperglycemia-induced ROS in this postnatal critical development window.
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Affiliation(s)
- Franciane Quintanilha Gallego
- Laboratory of Experimental Research of Gynecology and Obstetrics, Postgraduate Course of Gynecology, Obstetrics and Mastology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Carolina Abreu Miranda
- Laboratory of Experimental Research of Gynecology and Obstetrics, Postgraduate Course of Gynecology, Obstetrics and Mastology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Yuri Karen Sinzato
- Laboratory of Experimental Research of Gynecology and Obstetrics, Postgraduate Course of Gynecology, Obstetrics and Mastology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Isabela Lovizutto Iessi
- Laboratory of Experimental Research of Gynecology and Obstetrics, Postgraduate Course of Gynecology, Obstetrics and Mastology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Bruna Dallaqua
- DeVry Ruy Barbosa School (DeVry Brazil Group), Salvador, Bahia State, Brazil
| | - Rogelio Hernandez Pando
- Department of Pathology, National Institute of Medical Sciences and Nutrition "Salvador Zubirán", Mexico City, Mexico
| | - Noeme Sousa Rocha
- Department of Pathology, School of Veterinary Medicine and Animal Science (FMVZ), São Paulo State University (UNESP), Botucatu, São Paulo, Brazil
| | - Gustavo Tadeu Volpato
- Laboratory of System Physiology and Reproductive Toxicology, Institute of Biological and Health Sciences, Federal University of Mato Grosso (UFMT), Barra do Garças, Mato Grosso State, Brazil
| | - Débora Cristina Damasceno
- Laboratory of Experimental Research of Gynecology and Obstetrics, Postgraduate Course of Gynecology, Obstetrics and Mastology, Botucatu Medical School, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil.
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18
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Farack L, Golan M, Egozi A, Dezorella N, Bahar Halpern K, Ben-Moshe S, Garzilli I, Tóth B, Roitman L, Krizhanovsky V, Itzkovitz S. Transcriptional Heterogeneity of Beta Cells in the Intact Pancreas. Dev Cell 2018; 48:115-125.e4. [PMID: 30503750 DOI: 10.1016/j.devcel.2018.11.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/14/2018] [Accepted: 10/31/2018] [Indexed: 12/27/2022]
Abstract
Pancreatic beta cells have been shown to be heterogeneous at multiple levels. However, spatially interrogating transcriptional heterogeneity in the intact tissue has been challenging. Here, we developed an optimized protocol for single-molecule transcript imaging in the intact pancreas and used it to identify a sub-population of "extreme" beta cells with elevated mRNA levels of insulin and other secretory genes. Extreme beta cells contain higher ribosomal and proinsulin content but lower levels of insulin protein in fasted states, suggesting they may be tuned for basal insulin secretion. They exhibit a distinctive intra-cellular polarization pattern, with elevated mRNA concentrations in an apical ER-enriched compartment, distinct from the localization of nascent and mature proteins. The proportion of extreme cells increases in db/db diabetic mice, potentially facilitating the required increase in basal insulin. Our results thus highlight a sub-population of beta cells that may carry distinct functional roles along physiological and pathological timescales.
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Affiliation(s)
- Lydia Farack
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Matan Golan
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Adi Egozi
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nili Dezorella
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Keren Bahar Halpern
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shani Ben-Moshe
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Immacolata Garzilli
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Beáta Tóth
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lior Roitman
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Valery Krizhanovsky
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shalev Itzkovitz
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
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19
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Farack L, Egozi A, Itzkovitz S. Single molecule approaches for studying gene regulation in metabolic tissues. Diabetes Obes Metab 2018; 20 Suppl 2:145-156. [PMID: 30230176 DOI: 10.1111/dom.13390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/16/2018] [Accepted: 05/30/2018] [Indexed: 12/25/2022]
Abstract
Gene expression in metabolic tissues can be regulated at multiple levels, ranging from the control of promoter accessibilities, transcription rates, mRNA degradation rates and mRNA localization. Modulating these processes can differentially affect important performance criteria of cells. These include precision, cellular economy, rapid response and maintenance of DNA integrity. In this review we will describe how distinct strategies of gene regulation impact the trade-offs between the cells' performance criteria. We will highlight tools based on single molecule visualization of transcripts that can be used to measure promoter states, transcription rates and mRNA degradation rates in intact tissues. These approaches revealed surprising recurrent patterns in mammalian tissues, that include transcriptional bursting, nuclear retention of mRNA, and coordination of mRNA lifetimes to facilitate rapid adaptation to changing metabolic inputs. The ability to characterize gene expression at the single molecule level can uncover the design principles of gene regulation in metabolic tissues such as the liver and the pancreas.
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Affiliation(s)
- Lydia Farack
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Adi Egozi
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Shalev Itzkovitz
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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20
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Medina A, Parween S, Ullsten S, Vishnu N, Siu YT, Quach M, Bennet H, Balhuizen A, Åkesson L, Wierup N, Carlsson PO, Ahlgren U, Lernmark Å, Fex M. Early deficits in insulin secretion, beta cell mass and islet blood perfusion precede onset of autoimmune type 1 diabetes in BioBreeding rats. Diabetologia 2018; 61:896-905. [PMID: 29209740 PMCID: PMC6448977 DOI: 10.1007/s00125-017-4512-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/18/2017] [Indexed: 11/25/2022]
Abstract
AIMS/HYPOTHESIS Genetic studies show coupling of genes affecting beta cell function to type 1 diabetes, but hitherto no studies on whether beta cell dysfunction could precede insulitis and clinical onset of type 1 diabetes are available. METHODS We used 40-day-old BioBreeding (BB) DRLyp/Lyp rats (a model of spontaneous autoimmune type 1 diabetes) and diabetes-resistant DRLyp/+ and DR+/+ littermates (controls) to investigate beta cell function in vivo, and insulin and glucagon secretion in vitro. Beta cell mass was assessed by optical projection tomography (OPT) and morphometry. Additionally, measurements of intra-islet blood flow were performed using microsphere injections. We also assessed immune cell infiltration, cytokine expression in islets (by immunohistochemistry and qPCR), as well as islet Glut2 expression and ATP/ADP ratio to determine effects on glucose uptake and metabolism in beta cells. RESULTS DRLyp/Lyp rats were normoglycaemic and without traces of immune cell infiltrates. However, IVGTTs revealed a significant decrease in the acute insulin response to glucose compared with control rats (1685.3 ± 121.3 vs 633.3 ± 148.7; p < 0.0001). In agreement, insulin secretion was severely perturbed in isolated islets, and both first- and second-phase insulin release were lowered compared with control rats, while glucagon secretion was similar in both groups. Interestingly, after 5-7 days of culture of islets from DRLyp/Lyp rats in normal media, glucose-stimulated insulin secretion (GSIS) was improved; although, a significant decrease in GSIS was still evident compared with islets from control rats at this time (7393.9 ± 1593.7 vs 4416.8 ± 1230.5 pg islet-1 h-1; p < 0.0001). Compared with controls, OPT of whole pancreas from DRLyp/Lyp rats revealed significant reductions in medium (4.1 × 109 ± 9.5 × 107 vs 3.8 × 109 ± 5.8 × 107 μm3; p = 0.044) and small sized islets (1.6 × 109 ± 5.1 × 107 vs 1.4 × 109 ± 4.5 × 107 μm3; p = 0.035). Finally, we found lower intra-islet blood perfusion in vivo (113.1 ± 16.8 vs 76.9 ± 11.8 μl min-1 [g pancreas]-1; p = 0.023) and alterations in the beta cell ATP/ADP ratio in DRLyp/Lyp rats vs control rats. CONCLUSIONS/INTERPRETATION The present study identifies a deterioration of beta cell function and mass, and intra-islet blood flow that precedes insulitis and diabetes development in animals prone to autoimmune type 1 diabetes. These underlying changes in islet function may be previously unrecognised factors of importance in type 1 diabetes development.
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Affiliation(s)
- Anya Medina
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden.
| | - Saba Parween
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Sara Ullsten
- Medical Cell Biology, Uppsala Biomedical Centre, Uppsala, Sweden
| | - Neelanjan Vishnu
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
| | - Yuk Ting Siu
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
| | - My Quach
- Medical Cell Biology, Uppsala Biomedical Centre, Uppsala, Sweden
| | - Hedvig Bennet
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
| | - Alexander Balhuizen
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
| | - Lina Åkesson
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
| | - Nils Wierup
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
| | - Per Ola Carlsson
- Medical Cell Biology, Uppsala Biomedical Centre, Uppsala, Sweden
| | - Ulf Ahlgren
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Åke Lernmark
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
| | - Malin Fex
- Lund University Diabetes Centre, Clinical Research Centre, Skåne University Hospital (SUS), Jan Waldentrömsgata 35, SE-20502, Malmö, Sweden
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21
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Koekkoek LL, Mul JD, la Fleur SE. Glucose-Sensing in the Reward System. Front Neurosci 2017; 11:716. [PMID: 29311793 PMCID: PMC5742113 DOI: 10.3389/fnins.2017.00716] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/07/2017] [Indexed: 01/14/2023] Open
Abstract
Glucose-sensing neurons are neurons that alter their activity in response to changes in extracellular glucose. These neurons, which are an important mechanism the brain uses to monitor changes in glycaemia, are present in the hypothalamus, where they have been thoroughly investigated. Recently, glucose-sensing neurons have also been identified in brain nuclei which are part of the reward system. However, little is known about the molecular mechanisms by which they function, and their role in the reward system. We therefore aim to provide an overview of molecular mechanisms that have been studied in the hypothalamic glucose-sensing neurons, and investigate which of these transporters, enzymes and channels are present in the reward system. Furthermore, we speculate about the role of glucose-sensing neurons in the reward system.
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Affiliation(s)
- Laura L Koekkoek
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Laboratory of Endocrinology, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Metabolism and Reward Group, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Joram D Mul
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Laboratory of Endocrinology, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Metabolism and Reward Group, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Susanne E la Fleur
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Laboratory of Endocrinology, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Metabolism and Reward Group, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
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22
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Nagaki Y, Ito K, Kuwahara M. WTC rat has unique characteristics such as resistant to streptozotocin. Biochem Biophys Rep 2017; 8:157-161. [PMID: 28955952 PMCID: PMC5613963 DOI: 10.1016/j.bbrep.2016.08.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 07/25/2016] [Accepted: 08/29/2016] [Indexed: 11/03/2022] Open
Abstract
Because we found that WTC rats might be resistant to streptozotocin (STZ), we have elucidated the mechanisms of resistant to the diabetogenic effects of STZ in the WTC rats. Dose response to STZ was evaluated with glucose levels. No significant changes in glucose level to STZ administration were observed in WTC rats. Insulin secretion by suppling glucose was preserved in WTC rats even after STZ administration. Although there was no significant difference in gene expression of both GLUT2 and Kir6.2, which were involved in STZ resistance, between WTC rats and Wistar rats, the expression of metallothionein 2a in pancreas and liver to STZ administration of WTC rats was significantly higher than that of Wistar rats. Moreover, alloxan did not induce diabetes in WTC rats as same as STZ. These results suggest that WTC rats might have powerful antioxidant property to protect β cells in pancreas. Because the STZ-resistant property is very close characteristics to human beings, WTC rats will become a useful animal model in diabetic researches.
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Affiliation(s)
- Yoshiaki Nagaki
- Department of Veterinary Pathophysiology and Animal Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Koichi Ito
- Department of Veterinary Pathophysiology and Animal Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Masayoshi Kuwahara
- Department of Veterinary Pathophysiology and Animal Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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23
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Petrenko V, Saini C, Giovannoni L, Gobet C, Sage D, Unser M, Heddad Masson M, Gu G, Bosco D, Gachon F, Philippe J, Dibner C. Pancreatic α- and β-cellular clocks have distinct molecular properties and impact on islet hormone secretion and gene expression. Genes Dev 2017; 31:383-398. [PMID: 28275001 PMCID: PMC5358758 DOI: 10.1101/gad.290379.116] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 02/02/2017] [Indexed: 01/10/2023]
Abstract
Here, Petrenko et al. present the first integrative analysis of the molecular properties of circadian clocks in α and β pancreatic cells and provide new insights into the complex regulation of islet cell physiology at transcriptional and functional levels. A critical role of circadian oscillators in orchestrating insulin secretion and islet gene transcription has been demonstrated recently. However, these studies focused on whole islets and did not explore the interplay between α-cell and β-cell clocks. We performed a parallel analysis of the molecular properties of α-cell and β-cell oscillators using a mouse model expressing three reporter genes: one labeling α cells, one specific for β cells, and a third monitoring circadian gene expression. Thus, phase entrainment properties, gene expression, and functional outputs of the α-cell and β-cell clockworks could be assessed in vivo and in vitro at the population and single-cell level. These experiments showed that α-cellular and β-cellular clocks are oscillating with distinct phases in vivo and in vitro. Diurnal transcriptome analysis in separated α and β cells revealed that a high number of genes with key roles in islet physiology, including regulators of glucose sensing and hormone secretion, are differentially expressed in these cell types. Moreover, temporal insulin and glucagon secretion exhibited distinct oscillatory profiles both in vivo and in vitro. Altogether, our data indicate that differential entrainment characteristics of circadian α-cell and β-cell clocks are an important feature in the temporal coordination of endocrine function and gene expression.
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Affiliation(s)
- Volodymyr Petrenko
- Endocrinology, Diabetes, Hypertension, and Nutrition, University Hospital of Geneva, CH-1211 Geneva, Switzerland.,Department of Cellular Physiology and Metabolism, Diabetes Center, Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, CH-1211 Geneva, Switzerland
| | - Camille Saini
- Endocrinology, Diabetes, Hypertension, and Nutrition, University Hospital of Geneva, CH-1211 Geneva, Switzerland.,Department of Cellular Physiology and Metabolism, Diabetes Center, Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, CH-1211 Geneva, Switzerland
| | - Laurianne Giovannoni
- Endocrinology, Diabetes, Hypertension, and Nutrition, University Hospital of Geneva, CH-1211 Geneva, Switzerland.,Department of Cellular Physiology and Metabolism, Diabetes Center, Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, CH-1211 Geneva, Switzerland
| | - Cedric Gobet
- Department of Diabetes and Circadian Rhythms, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland.,School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Daniel Sage
- Biomedical Imaging Group, EPFL, CH-1015 Lausanne, Switzerland
| | - Michael Unser
- Biomedical Imaging Group, EPFL, CH-1015 Lausanne, Switzerland
| | - Mounia Heddad Masson
- Endocrinology, Diabetes, Hypertension, and Nutrition, University Hospital of Geneva, CH-1211 Geneva, Switzerland
| | - Guoqiang Gu
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37240, USA
| | - Domenico Bosco
- Department of Surgery, Cell Isolation and Transplantation Centre, University Hospital of Geneva, CH-1211 Geneva, Switzerland
| | - Frédéric Gachon
- Department of Diabetes and Circadian Rhythms, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland.,School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jacques Philippe
- Endocrinology, Diabetes, Hypertension, and Nutrition, University Hospital of Geneva, CH-1211 Geneva, Switzerland
| | - Charna Dibner
- Endocrinology, Diabetes, Hypertension, and Nutrition, University Hospital of Geneva, CH-1211 Geneva, Switzerland.,Department of Cellular Physiology and Metabolism, Diabetes Center, Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland.,Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, CH-1211 Geneva, Switzerland
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24
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Roscioni SS, Migliorini A, Gegg M, Lickert H. Impact of islet architecture on β-cell heterogeneity, plasticity and function. Nat Rev Endocrinol 2016; 12:695-709. [PMID: 27585958 DOI: 10.1038/nrendo.2016.147] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although β-cell heterogeneity was discovered more than 50 years ago, the underlying principles have been explored only during the past decade. Islet-cell heterogeneity arises during pancreatic development and might reflect the existence of distinct populations of progenitor cells and the developmental pathways of endocrine cells. Heterogeneity can also be acquired in the postnatal period owing to β-cell plasticity or changes in islet architecture. Furthermore, β-cell neogenesis, replication and dedifferentiation represent alternative sources of β-cell heterogeneity. In addition to a physiological role, β-cell heterogeneity influences the development of diabetes mellitus and its response to treatment. Identifying phenotypic and functional markers to discriminate distinct β-cell subpopulations and the mechanisms underpinning their regulation is warranted to advance current knowledge of β-cell function and to design novel regenerative strategies that target subpopulations of β cells. In this context, the Wnt/planar cell polarity (PCP) effector molecule Flattop can distinguish two unique β-cell subpopulations with specific transcriptional signatures, functional properties and differential responses to environmental stimuli. In vivo targeting of these β-cell subpopulations might, therefore, represent an alternative strategy for the future treatment of diabetes mellitus.
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Affiliation(s)
- Sara S Roscioni
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
| | - Adriana Migliorini
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
| | - Moritz Gegg
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Technische Universität München, 81675 München, Germany
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25
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Macroporous biohybrid cryogels for co-housing pancreatic islets with mesenchymal stromal cells. Acta Biomater 2016; 44:178-87. [PMID: 27506126 DOI: 10.1016/j.actbio.2016.08.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 07/19/2016] [Accepted: 08/05/2016] [Indexed: 01/11/2023]
Abstract
UNLABELLED Intrahepatic transplantation of allogeneic pancreatic islets offers a promising therapy for type 1 diabetes. However, long-term insulin independency is often not achieved due to severe islet loss shortly after transplantation. To improve islet survival and function, extrahepatic biomaterial-assisted transplantation of pancreatic islets to alternative sites has been suggested. Herein, we present macroporous, star-shaped poly(ethylene glycol) (starPEG)-heparin cryogel scaffolds, covalently modified with adhesion peptides, for the housing of pancreatic islets in three-dimensional (3D) co-culture with adherent mesenchymal stromal cells (MSC) as accessory cells. The implantable biohybrid scaffolds provide efficient transport properties, mechanical protection, and a supportive extracellular environment as a desirable niche for the islets. MSC colonized the cryogel scaffolds and produced extracellular matrix proteins that are important components of the natural islet microenvironment known to facilitate matrix-cell interactions and to prevent cellular stress. Islets survived the seeding procedure into the cryogel scaffolds and secreted insulin after glucose stimulation in vitro. In a rodent model, intact islets and MSC could be visualized within the scaffolds seven days after subcutaneous transplantation. Overall, this demonstrates the potential of customized macroporous starPEG-heparin cryogel scaffolds in combination with MSC to serve as a multifunctional islet supportive carrier for transplantation applications. STATEMENT OF SIGNIFICANCE Diabetes results in the insufficient production of insulin by the pancreatic β-cells in the islets of Langerhans. Transplantation of pancreatic islets offers valuable options for treating the disease; however, many transplanted islets often do not survive the transplantation or die shortly thereafter. Co-transplanted, supporting cells and biomaterials can be instrumental for improving islet survival, function and protection from the immune system. In the present study, islet supportive hydrogel sponges were explored for the co-transplantation of islets and mesenchymal stromal cells. Survival and continued function of the supported islets were demonstrated in vitro. The in vivo feasibility of the approach was shown by transplantation in a mouse model.
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26
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Mziaut H, Mulligan B, Hoboth P, Otto O, Ivanova A, Herbig M, Schumann D, Hildebrandt T, Dehghany J, Sönmez A, Münster C, Meyer-Hermann M, Guck J, Kalaidzidis Y, Solimena M. The F-actin modifier villin regulates insulin granule dynamics and exocytosis downstream of islet cell autoantigen 512. Mol Metab 2016; 5:656-668. [PMID: 27656403 PMCID: PMC5021679 DOI: 10.1016/j.molmet.2016.05.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 01/02/2023] Open
Abstract
Objective Insulin release from pancreatic islet β cells should be tightly controlled to avoid hypoglycemia and insulin resistance. The cortical actin cytoskeleton is a gate for regulated exocytosis of insulin secretory granules (SGs) by restricting their mobility and access to the plasma membrane. Prior studies suggest that SGs interact with F-actin through their transmembrane cargo islet cell autoantigen 512 (Ica512) (also known as islet antigen 2/Ptprn). Here we investigated how Ica512 modulates SG trafficking and exocytosis. Methods Transcriptomic changes in Ica512−/− mouse islets were analyzed. Imaging as well as biophysical and biochemical methods were used to validate if and how the Ica512-regulated gene villin modulates insulin secretion in mouse islets and insulinoma cells. Results The F-actin modifier villin was consistently downregulated in Ica512−/− mouse islets and in Ica512-depleted insulinoma cells. Villin was enriched at the cell cortex of β cells and dispersed villin−/− islet cells were less round and less deformable. Basal mobility of SGs in villin-depleted cells was enhanced. Moreover, in cells depleted either of villin or Ica512 F-actin cages restraining cortical SGs were enlarged, basal secretion was increased while glucose-stimulated insulin release was blunted. The latter changes were reverted by overexpressing villin in Ica512-depleted cells, but not vice versa. Conclusion Our findings show that villin controls the size of the F-actin cages restricting SGs and, thus, regulates their dynamics and availability for exocytosis. Evidence that villin acts downstream of Ica512 also indicates that SGs directly influence the remodeling properties of the cortical actin cytoskeleton for tight control of insulin secretion. Ica512-depletion reduces the genetic expression of the F-actin modifier villin. Villin-depletion enhances basal insulin granule mobility and exocytosis. Villin regulates the size of actin cages restraining insulin granules. Villin acts downstream of insulin granule cargo Ica512. The Ica512-villin genetic link enables granules to control cytoskeleton plasticity.
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Key Words
- D, diffusion coefficient
- EGFP, enhanced green fluorescent protein
- F-actin
- Granules
- IPGTT, intraperitoneal glucose tolerance test
- IVGTT, intravenous glucose tolerance test
- Ica512
- Ica512, islet cell autoantigen
- Insulin
- OGTT, oral glucose tolerance test
- RT-DC, real-time deformability cytometry
- SE, standard error
- SG, secretory granules
- Secretion
- TIRFM, total internal reflection fluorescence microscopy
- Villin
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Affiliation(s)
- Hassan Mziaut
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Bernard Mulligan
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Peter Hoboth
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Oliver Otto
- Biotechnology Center Dresden, 01307 Dresden, Germany
| | - Anna Ivanova
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Maik Herbig
- Biotechnology Center Dresden, 01307 Dresden, Germany
| | - Desiree Schumann
- Boehringer Ingelheim Pharma GmbH & Co. KG. Cardiometabolic Research, 88397 Biberach, Germany
| | - Tobias Hildebrandt
- Boehringer Ingelheim Pharma GmbH & Co. KG. Cardiometabolic Research, 88397 Biberach, Germany
| | - Jaber Dehghany
- Helmholtz Centre for Infection Research (HZI), Braunschweig Integrated Centre for Systems Biology (BRICS), 38124 Braunschweig, Germany
| | - Anke Sönmez
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Carla Münster
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany
| | - Michael Meyer-Hermann
- Helmholtz Centre for Infection Research (HZI), Braunschweig Integrated Centre for Systems Biology (BRICS), 38124 Braunschweig, Germany
| | - Jochen Guck
- Biotechnology Center Dresden, 01307 Dresden, Germany
| | - Yannis Kalaidzidis
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Michele Solimena
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the Univ. Hospital, Faculty of Medicine Carl Gustav Carus, Technische Univ. Dresden, 01307 Dresden, Germany; German Center for Diabetes Research (DZD e.V.), 85674 Neuherberg, Germany; Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
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27
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Thorn P, Zorec R, Rettig J, Keating DJ. Exocytosis in non-neuronal cells. J Neurochem 2016; 137:849-59. [PMID: 26938142 DOI: 10.1111/jnc.13602] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 02/02/2016] [Accepted: 03/01/2016] [Indexed: 12/18/2022]
Abstract
Exocytosis is the process by which stored neurotransmitters and hormones are released via the fusion of secretory vesicles with the plasma membrane. It is a dynamic, rapid and spatially restricted process involving multiple steps including vesicle trafficking, tethering, docking, priming and fusion. For many years great steps have been undertaken in our understanding of how exocytosis occurs in different cell types, with significant focus being placed on synaptic release and neurotransmission. However, this process of exocytosis is an essential component of cell signalling throughout the body and underpins a diverse array of essential physiological pathways. Many similarities exist between different cell types with regard to key aspects of the exocytosis pathway, such as the need for Ca(2+) to trigger it or the involvement of members of the N-ethyl maleimide-sensitive fusion protein attachment protein receptor protein families. However, it is also equally clear that non-neuronal cells have acquired highly specialized mechanisms to control the release of their own unique chemical messengers. This review will focus on several important non-neuronal cell types and discuss what we know about the mechanisms they use to control exocytosis and how their specialized output is relevant to the physiological role of each individual cell type. These include enteroendocrine cells, pancreatic β cells, astrocytes, lactotrophs and cytotoxic T lymphocytes. Non-neuronal cells have acquired highly specialized mechanisms to control the release of unique chemical messengers, such as polarised fusion of insulin granules in pancreatic β cells targeted towards the vasculature (top). This review discusses mechanisms used in several important non-neuronal cell types to control exocytosis, and the relevance of intermediate vesicle fusion pore states (bottom) and their specialized output to the physiological role of each cell type. These include enteroendocrine cells, pancreatic β cells, astrocytes, lactotrophs and cytotoxic T lymphocytes. This article is part of a mini review series on Chromaffin cells (ISCCB Meeting, 2015).
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Affiliation(s)
- Peter Thorn
- Charles Perkins Centre, John Hopkins Drive, The University of Sydney, Camperdown, NSW, Australia
| | - Robert Zorec
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Jens Rettig
- Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Damien J Keating
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, SA, Australia.,South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia
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28
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Fournel A, Marlin A, Abot A, Pasquio C, Cirillo C, Cani PD, Knauf C. Glucosensing in the gastrointestinal tract: Impact on glucose metabolism. Am J Physiol Gastrointest Liver Physiol 2016; 310:G645-58. [PMID: 26939867 PMCID: PMC4867329 DOI: 10.1152/ajpgi.00015.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 02/25/2016] [Indexed: 01/31/2023]
Abstract
The gastrointestinal tract is an important interface of exchange between ingested food and the body. Glucose is one of the major dietary sources of energy. All along the gastrointestinal tube, e.g., the oral cavity, small intestine, pancreas, and portal vein, specialized cells referred to as glucosensors detect variations in glucose levels. In response to this glucose detection, these cells send hormonal and neuronal messages to tissues involved in glucose metabolism to regulate glycemia. The gastrointestinal tract continuously communicates with the brain, especially with the hypothalamus, via the gut-brain axis. It is now well established that the cross talk between the gut and the brain is of crucial importance in the control of glucose homeostasis. In addition to receiving glucosensing information from the gut, the hypothalamus may also directly sense glucose. Indeed, the hypothalamus contains glucose-sensitive cells that regulate glucose homeostasis by sending signals to peripheral tissues via the autonomous nervous system. This review summarizes the mechanisms by which glucosensors along the gastrointestinal tract detect glucose, as well as the results of such detection in the whole body, including the hypothalamus. We also highlight how disturbances in the glucosensing process may lead to metabolic disorders such as type 2 diabetes. A better understanding of the pathways regulating glucose homeostasis will further facilitate the development of novel therapeutic strategies for the treatment of metabolic diseases.
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Affiliation(s)
- Audren Fournel
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Alysson Marlin
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Anne Abot
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Charles Pasquio
- 1NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
| | - Carla Cirillo
- 2Laboratory for Enteric NeuroScience (LENS), University of Leuven, Leuven, Belgium; and
| | - Patrice D. Cani
- 3NeuroMicrobiota, European Associated Laboratory, Université Catholique de Louvain (UCL), Louvain Drug Research Institute (LDRI), Metabolism and Nutrition Research Group, WELBIO (Walloon Excellence in Life sciences and BIOtechnology), Brussels, Belgium
| | - Claude Knauf
- NeuroMicrobiota, European Associated Laboratory, Institut National de la Santé et de la Recherche Médicale (INSERM) U1220, Institut de Recherche en Santé Digestive (IRSD), Toulouse, France;
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29
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Gan WJ, Zavortink M, Ludick C, Templin R, Webb R, Webb R, Ma W, Poronnik P, Parton RG, Gaisano HY, Shewan AM, Thorn P. Cell polarity defines three distinct domains in pancreatic β-cells. J Cell Sci 2016; 130:143-151. [PMID: 26919978 PMCID: PMC5394774 DOI: 10.1242/jcs.185116] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/08/2016] [Indexed: 12/15/2022] Open
Abstract
The structural organisation of pancreatic β-cells in the islets of Langerhans is relatively unknown. Here, using three-dimensional (3D) two-photon, 3D confocal and 3D block-face serial electron microscopy, we demonstrate a consistent in situ polarisation of β-cells and define three distinct cell surface domains. An apical domain located at the vascular apogee of β-cells, defined by the location of PAR-3 (also known as PARD3) and ZO-1 (also known as TJP1), delineates an extracellular space into which adjacent β-cells project their primary cilia. A separate lateral domain, is enriched in scribble and Dlg, and colocalises with E-cadherin and GLUT2 (also known as SLC2A2). Finally, a distinct basal domain, where the β-cells contact the islet vasculature, is enriched in synaptic scaffold proteins such as liprin. This 3D analysis of β-cells within intact islets, and the definition of distinct domains, provides new insights into understanding β-cell structure and function. Summary: 3D imaging methods identify three structural and functional domains within β-cells in islets: apical, lateral and basal.
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Affiliation(s)
- Wan J Gan
- School of Biomedical Sciences, University of Queensland, St Lucia, Queensland 4072, Australia.,Charles Perkins Centre, John Hopkins Drive, University of Sydney, Camperdown, New South Wales, 2050, Australia
| | - Michael Zavortink
- School of Biomedical Sciences, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Christine Ludick
- School of Biomedical Sciences, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Rachel Templin
- Centre for Microscopy and Microanalysis, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Robyn Webb
- Centre for Microscopy and Microanalysis, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Richard Webb
- Centre for Microscopy and Microanalysis, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Wei Ma
- Charles Perkins Centre, John Hopkins Drive, University of Sydney, Camperdown, New South Wales, 2050, Australia
| | - Philip Poronnik
- Department of Physiology, School of Medical Sciences, The University of Sydney, Camperdown, New South Wales, 2006, Australia
| | - Robert G Parton
- Centre for Microscopy and Microanalysis, University of Queensland, St Lucia, Queensland 4072, Australia.,Institute for Molecular Bioscience, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Herbert Y Gaisano
- Department of Medicine, University of Toronto, Toronto, Ontario, M5S1A8, Canada
| | - Annette M Shewan
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Peter Thorn
- School of Biomedical Sciences, University of Queensland, St Lucia, Queensland 4072, Australia .,Charles Perkins Centre, John Hopkins Drive, University of Sydney, Camperdown, New South Wales, 2050, Australia
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30
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Hoang Do O, Thorn P. Insulin secretion from beta cells within intact islets: location matters. Clin Exp Pharmacol Physiol 2015; 42:406-14. [PMID: 25676261 PMCID: PMC4418378 DOI: 10.1111/1440-1681.12368] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 12/21/2014] [Accepted: 01/06/2015] [Indexed: 12/17/2022]
Abstract
The control of hormone secretion is central to body homeostasis, and its dysfunction is important in many diseases. The key cellular steps that lead to hormone secretion have been identified, and the stimulus-secretion pathway is understood in outline for many endocrine cells. In the case of insulin secretion from pancreatic beta cells, this pathway involves the uptake of glucose, cell depolarization, calcium entry, and the triggering of the fusion of insulin-containing granules with the cell membrane. The wealth of information on the control of insulin secretion has largely been obtained from isolated single-cell studies. However, physiologically, beta cells exist within the islets of Langerhans, with structural and functional specializations that are not preserved in single-cell cultures. This review focuses on recent work that is revealing distinct aspects of insulin secretion from beta cells within the islet.
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Affiliation(s)
- Oanh Hoang Do
- School of Biomedical Sciences, University of Queensland, St Lucia, Brisbane, Qld, Australia
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31
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Geron E, Boura-Halfon S, Schejter ED, Shilo BZ. The Edges of Pancreatic Islet β Cells Constitute Adhesive and Signaling Microdomains. Cell Rep 2015; 10:317-325. [PMID: 25600867 DOI: 10.1016/j.celrep.2014.12.031] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/11/2014] [Accepted: 12/12/2014] [Indexed: 10/24/2022] Open
Abstract
Pancreatic islet β cells are organized in rosette-like structures around blood vessels and exhibit an artery-to-vein orientation, but they do not display the typical epithelial polarity. It is unclear whether these cells present a functional asymmetry related to their spatial organization. Here, we identify murine β cell edges, the sites at which adjacent cell faces meet at a sharp angle, as surface microdomains of cell-cell adhesion and signaling. The edges are marked by enrichment of F-actin and E-cadherin and are aligned between neighboring cells. The edge organization is E-cadherin contact dependent and correlates with insulin secretion capacity. Edges display elevated levels of glucose transporters and SNAP25 and extend numerous F-actin-rich filopodia. A similar β cell edge organization was observed in human islets. When stimulated, β cell edges exhibit high calcium levels. In view of the functional importance of intra-islet communication, the spatial architecture of their edges may prove fundamental for coordinating physiological insulin secretion.
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Affiliation(s)
- Erez Geron
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sigalit Boura-Halfon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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32
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Thorens B. Neural regulation of pancreatic islet cell mass and function. Diabetes Obes Metab 2014; 16 Suppl 1:87-95. [PMID: 25200301 DOI: 10.1111/dom.12346] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 05/15/2014] [Indexed: 12/24/2022]
Abstract
Intracellular glucose signalling pathways control the secretion of glucagon and insulin by pancreatic islet α- and β-cells, respectively. However, glucose also indirectly controls the secretion of these hormones through regulation of the autonomic nervous system that richly innervates this endocrine organ. Both parasympathetic and sympathetic nervous systems also impact endocrine pancreas postnatal development and plasticity in adult animals. Defects in these autonomic regulations impair β-cell mass expansion during the weaning period and β-cell mass adaptation in adult life. Both branches of the autonomic nervous system also regulate glucagon secretion. In type 2 diabetes, impaired glucose-dependent autonomic activity causes the loss of cephalic and first phases of insulin secretion, and impaired suppression of glucagon secretion in the postabsorptive phase; in diabetic patients treated with insulin, it causes a progressive failure of hypoglycaemia to trigger the secretion of glucagon and other counterregulatory hormones. Therefore, identification of the glucose-sensing cells that control the autonomic innervation of the endocrine pancreatic and insulin and glucagon secretion is an important goal of research. This is required for a better understanding of the physiological control of glucose homeostasis and its deregulation in diabetes. This review will discuss recent advances in this field of investigation.
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Affiliation(s)
- B Thorens
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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33
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Wong JCY, Jack MM, Li Y, O'Neill C. The epigenetic bivalency of core pancreatic β-cell transcription factor genes within mouse pluripotent embryonic stem cells is not affected by knockdown of the polycomb repressive complex 2, SUZ12. PLoS One 2014; 9:e97820. [PMID: 24845830 PMCID: PMC4028244 DOI: 10.1371/journal.pone.0097820] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/23/2014] [Indexed: 12/19/2022] Open
Abstract
This study assesses changes in activator and repressor modifications to histones associated with the core transcription factor genes most highly upregulated or downregulated in pancreatic β-cells relative to expression in an embryonic stem cell line. Epigenetic analysis of the Oct4, Utf1, Nanog and Sox2 (pluripotency) and Pdx1, Nkx6.1, Nkx2.2 and MafA (pancreatic β-cells) transcription factor genes in embryonic stem cells and a β-cell line (MIN6) showed the pluripotency genes were enriched for active (histone 3 trimethylated at lysine 4 and histone 3 acetylated at lysine 9) and depleted of repressor modifications (histone 3 trimethylated at lysine 27 and histone 3 trimethylated at lysine 9) around the transcription start site in mouse embryonic stem cells (D3), and this was reversed in MIN6 cells. The β-cell transcription factors were bivalently enriched for activating (histone 3 trimethylated at lysine 4) and repressor (histone 3 trimethylated at lysine 27) modifications in embryonic stem cells but were monovalent for the activator modification (histone 3 trimethylated at lysine 4) in the β-cells. The polycomb repressor complex 2 acts as a histone 3 lysine 27 methylase and an essential component of this complex, SUZ12, was enriched at the β-cell transcription factors in embryonic stem cells and was reduced MIN6. Knock-down of SUZ12 in embryonic stem cells, however, did not reduce the level of histone 3 trimethylated at lysine 27 at β-cell transcription factor loci or break the transcriptional repression of these genes in embryonic stem cells. This study shows the reduction in the total SUZ12 level was not a sufficient cause of the resolution of the epigenetic bivalency of β-cell transcription factors in embryonic stem cells.
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Affiliation(s)
- Jennifer C. Y. Wong
- Centre for Developmental and Regenerative Medicine, Kolling Institute of Medical Research, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Michelle M. Jack
- Department of Endocrinology, Royal North Shore Hospital, Sydney, New South Wales, Australia
| | - Yan Li
- Centre for Developmental and Regenerative Medicine, Kolling Institute of Medical Research, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Christopher O'Neill
- Centre for Developmental and Regenerative Medicine, Kolling Institute of Medical Research, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
- * E-mail:
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Abstract
Monogenic diabetes represents a heterogeneous group of disorders resulting from defects in single genes. Defects are categorized primarily into two groups: disruption of β-cell function or a reduction in the number of β-cells. A complex network of transcription factors control pancreas formation, and a dysfunction of regulators high in the hierarchy leads to pancreatic agenesis. Dysfunction among factors further downstream might cause organ hypoplasia, absence of islets of Langerhans or a reduction in the number of β-cells. Many transcription factors have pleiotropic effects, explaining the association of diabetes with other congenital malformations, including cerebellar agenesis and pituitary agenesis. Monogenic diabetes variants are classified conventionally according to age of onset, with neonatal diabetes occurring before the age of 6 months and maturity onset diabetes of the young (MODY) manifesting before the age of 25 years. Recently, certain familial genetic defects were shown to manifest as neonatal diabetes, MODY or even adult onset diabetes. Patients with neonatal diabetes require a thorough genetic work-up in any case, and because extensive phenotypic overlap exists between monogenic, type 2, and type 1 diabetes, genetic analysis will also help improve diagnosis in these cases. Next generation sequencing will facilitate rapid screening, leading to the discovery of digenic and oligogenic diabetes variants, and helping to improve our understanding of the genetics underlying other types of diabetes. An accurate diagnosis remains important, because it might lead to a change in the treatment of affected subjects and influence long-term complications.
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Affiliation(s)
- Valerie M Schwitzgebel
- Pediatric Endocrine and Diabetes UnitDepartment of Child and Adolescent HealthChildren's University HospitalGenevaSwitzerland
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35
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Beta-cell specific production of IL6 in conjunction with a mainly intracellular but not mainly surface viral protein causes diabetes. J Autoimmun 2014; 55:24-32. [PMID: 24582317 DOI: 10.1016/j.jaut.2014.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 01/23/2014] [Accepted: 02/03/2014] [Indexed: 12/19/2022]
Abstract
Inflammatory mechanisms play a key role in the pathogenesis of type 1 and type 2 diabetes. IL6, a pleiotropic cytokine with impact on immune and non-immune cell types, has been proposed to be involved in the events causing both forms of diabetes and to play a key role in experimental insulin-dependent diabetes development. The aim of this study was to investigate how beta-cell specific overexpression of IL-6 influences diabetes development. We developed two lines of rat insulin promoter (RIP)-lymphocytic choriomeningitis virus (LCMV) mice that also co-express IL6 in their beta-cells. Expression of the viral nucleoprotein (NP), which has a predominantly intracellular localization, together with IL6 led to hyperglycemia, which was associated with a loss of GLUT-2 expression in the pancreatic beta-cells and infiltration of CD11b(+) cells, but not T cells, in the pancreas. In contrast, overexpression of the LCMV glycoprotein (GP), which can localize to the surface, with IL-6 did not lead to spontaneous diabetes, but accelerated virus-induced diabetes by increasing autoantigen-specific CD8(+) T cell responses and reducing the regulatory T cell fraction, leading to increased pancreatic infiltration by CD4(+) and CD8(+) T cells as well as CD11b(+) and CD11c(+) cells. The production of IL-6 in beta-cells acts prodiabetic, underscoring the potential benefit of targeting IL6 in diabetes.
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36
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Tsai PJ, Wang HS, Lin CH, Weng ZC, Chen TH, Shyu JF. Intraportal injection of insulin-producing cells generated from human bone marrow mesenchymal stem cells decreases blood glucose level in diabetic rats. Endocr Res 2014; 39:26-33. [PMID: 23772634 DOI: 10.3109/07435800.2013.797432] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We studied the process of trans-differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) into insulin-producing cells. Streptozotocin (STZ)-induced diabetic rat model was used to study the effect of portal vein transplantation of these insulin-producing cells on blood sugar levels. The BM-MSCs were differentiated into insulin-producing cells under defined conditions. Real-time PCR, immunocytochemistry and glucose challenge were used to evaluate in vitro differentiation. Flow cytometry showed that hBM-MSCs were strongly positive for CD44, CD105 and CD73 and negative for hematopoietic markers CD34, CD38 and CD45. Differentiated cells expressed C-peptide as well as β-cells specific genes and hormones. Glucose stimulation increased C-peptide secretion in these cells. The insulin-producing, differentiated cells were transplanted into the portal vein of STZ-induced diabetic rats using a Port-A catheter. The insulin-producing cells were localized in the liver of the recipient rat and expressed human C-peptide. Blood glucose levels were reduced in diabetic rats transplanted with insulin-producing cells. We concluded that hBM-MSCs could be trans-differentiated into insulin-producing cells in vitro. Portal vein transplantation of insulin-producing cells alleviated hyperglycemia in diabetic rats.
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Affiliation(s)
- Pei-Jiun Tsai
- Institute of Clinical Medicine, National Yang Ming University, Taipei , Taiwan , R.O.C
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37
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EMT in developmental morphogenesis. Cancer Lett 2013; 341:9-15. [DOI: 10.1016/j.canlet.2013.02.037] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 02/14/2013] [Accepted: 02/14/2013] [Indexed: 12/24/2022]
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38
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Alam CM, Silvander JSG, Daniel EN, Tao GZ, Kvarnström SM, Alam P, Omary MB, Hänninen A, Toivola DM. Keratin 8 modulates β-cell stress responses and normoglycaemia. J Cell Sci 2013; 126:5635-44. [PMID: 24144696 DOI: 10.1242/jcs.132795] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Keratin intermediate filament (IF) proteins are epithelial cell cytoskeletal components that provide structural stability and protection from cell stress, among other cellular and tissue-specific functions. Numerous human diseases are associated with IF gene mutations, but the function of keratins in the endocrine pancreas and their potential significance for glycaemic control are unknown. The impact of keratins on β-cell organisation and systemic glucose control was assessed using keratin 8 (K8) wild-type (K8(+/+)) and K8 knockout (K8(-/-)) mice. Islet β-cell keratins were characterised under basal conditions, in streptozotocin (STZ)-induced diabetes and in non-obese diabetic (NOD) mice. STZ-induced diabetes incidence and islet damage was assessed in K8(+/+) and K8(-/-) mice. K8 and K18 were the predominant keratins in islet β-cells and K8(-/-) mice expressed only remnant K18 and K7. K8 deletion resulted in lower fasting glucose levels, increased glucose tolerance and insulin sensitivity, reduced glucose-stimulated insulin secretion and decreased pancreatic insulin content. GLUT2 localisation and insulin vesicle morphology were disrupted in K8(-/-) β-cells. The increased levels of cytoplasmic GLUT2 correlated with resistance to high-dose STZ-induced injury in K8(-/-) mice. However, K8 deletion conferred no long-term protection from STZ-induced diabetes and prolonged STZ-induced stress caused increased exocrine damage in K8(-/-) mice. β-cell keratin upregulation occurred 2 weeks after treatments with low-dose STZ in K8(+/+) mice and in diabetic NOD mice, suggesting a role for keratins, particularly in non-acute islet stress responses. These results demonstrate previously unrecognised functions for keratins in β-cell intracellular organisation, as well as for systemic blood glucose control under basal conditions and in diabetes-induced stress.
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Affiliation(s)
- Catharina M Alam
- Department of Biosciences, Cell Biology, Åbo Akademi University, Tykistökatu 6A, FIN-20520 Turku, Finland
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39
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Cloning expeditions: risky but rewarding. Mol Cell Biol 2013; 33:4620-7. [PMID: 24061478 DOI: 10.1128/mcb.01111-13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the 1980s, a good part of my laboratory was using the then-new recombinant DNA techniques to clone and characterize many important cell surface membrane proteins: GLUT1 (the red cell glucose transporter) and then GLUT2 and GLUT4, the red cell anion exchange protein (Band 3), asialoglycoprotein receptor subunits, sucrase-isomaltase, the erythropoietin receptor, and two of the subunits of the transforming growth factor β (TGF-β) receptor. These cloned genes opened many new fields of basic research, including membrane insertion and trafficking of transmembrane proteins, signal transduction by many members of the cytokine and TGF-β families of receptors, and the cellular physiology of glucose and anion transport. They also led to many insights into the molecular biology of several cancers, hematopoietic disorders, and diabetes. This work was done by an exceptional group of postdocs and students who took exceptionally large risks in developing and using novel cloning technologies. Unsurprisingly, all have gone on to become leaders in the fields of molecular cell biology and molecular medicine.
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40
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Mazur MA, Winkler M, Ganić E, Colberg JK, Johansson JK, Bennet H, Fex M, Nuber UA, Artner I. Microphthalmia transcription factor regulates pancreatic β-cell function. Diabetes 2013; 62:2834-42. [PMID: 23610061 PMCID: PMC3717881 DOI: 10.2337/db12-1464] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Precise regulation of β-cell function is crucial for maintaining blood glucose homeostasis. Pax6 is an essential regulator of β-cell-specific factors like insulin and Glut2. Studies in the developing eye suggest that Pax6 interacts with Mitf to regulate pigment cell differentiation. Here, we show that Mitf, like Pax6, is expressed in all pancreatic endocrine cells during mouse postnatal development and in the adult islet. A Mitf loss-of-function mutation results in improved glucose tolerance and enhanced insulin secretion but no increase in β-cell mass in adult mice. Mutant β-cells secrete more insulin in response to glucose than wild-type cells, suggesting that Mitf is involved in regulating β-cell function. In fact, the transcription of genes critical for maintaining glucose homeostasis (insulin and Glut2) and β-cell formation and function (Pax4 and Pax6) is significantly upregulated in Mitf mutant islets. The increased Pax6 expression may cause the improved β-cell function observed in Mitf mutant animals, as it activates insulin and Glut2 transcription. Chromatin immunoprecipitation analysis shows that Mitf binds to Pax4 and Pax6 regulatory regions, suggesting that Mitf represses their transcription in wild-type β-cells. We demonstrate that Mitf directly regulates Pax6 transcription and controls β-cell function.
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Affiliation(s)
| | | | | | | | | | - Hedvig Bennet
- Unit for Diabetes and Celiac Disease, Clinical Research Center, Diabetes Center, Lund University, Sweden
| | - Malin Fex
- Unit for Diabetes and Celiac Disease, Clinical Research Center, Diabetes Center, Lund University, Sweden
| | | | - Isabella Artner
- Stem Cell Center, Lund University, Sweden
- Corresponding author: Isabella Artner,
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41
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Takemitsu H, Zhao D, Ishikawa S, Michishita M, Arai T, Yamamoto I. Mechanism of insulin production in canine bone marrow derived mesenchymal stem cells. Gen Comp Endocrinol 2013; 189:1-6. [PMID: 23624121 DOI: 10.1016/j.ygcen.2013.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/20/2013] [Accepted: 04/11/2013] [Indexed: 01/09/2023]
Abstract
Insulin is a critical hormone in the regulation of blood glucose levels and is produced exclusively by pancreatic islet beta-cells. Insulin deficiency due to reduced pancreatic islet beta-cell number underlies the progression of diabetes mellitus, prompting efforts to develop beta-cell replacement therapies. However, precise information on beta-cell replacement and differentiation in canines is limited. In this study, we established insulin-producing cells from bone marrow derived mesenchymal stem cells transiently expressing canine pancreatic and duodenal homeobox 1 (Pdx1), beta cell transactivator 2 (Beta2) and V-maf avian musculoaponeurotic fibrosarcoma oncogene homolog A (Mafa) using a gene transfer technique. Real-time PCR analysis revealed an increase in insulin mRNA expression of transfected cells. And ELISA revealed that insulin protein expressed was detected in cytoplasmic fraction. Insulin immunostaining analysis was performed and observed in cytoplasmic fraction. These results suggest that co-transfection of Pdx1, Beta2 and Mafa induce insulin production in canine BMSCs. Our findings provide a clue to basic research into the mechanisms underlying insulin production in the canines.
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Affiliation(s)
- Hiroshi Takemitsu
- Department of Veterinary Science, School of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan
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42
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Harcourt BE, Penfold SA, Forbes JM. Coming full circle in diabetes mellitus: from complications to initiation. Nat Rev Endocrinol 2013; 9:113-23. [PMID: 23296171 DOI: 10.1038/nrendo.2012.236] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glycaemic control, reduction of blood pressure using agents that block the renin-angiotensin system and control of dyslipidaemia are the major strategies used in the clinical management of patients with diabetes mellitus. Each of these approaches interrupts a number of pathological pathways, which directly contributes to the vascular complications of diabetes mellitus, including renal disease, blindness, neuropathy and cardiovascular disease. However, research published over the past few years has indicated that many of the pathological pathways important in the development of the vascular complications of diabetes mellitus are equally relevant to the initiation of diabetes mellitus itself. These pathways include insulin signalling, generation of cellular energy, post-translational modifications and redox imbalances. This Review will examine how the development of diabetes mellitus has come full circle from initiation to complications and suggests that the development of diabetes mellitus and the progression to chronic complications both require the same mechanistic triggers.
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Affiliation(s)
- Brooke E Harcourt
- Glycation and Diabetes Complications, Mater Medical Research Institute, Raymond Terrace, South Brisbane, QLD, Australia
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43
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Pan FC, Bankaitis ED, Boyer D, Xu X, Van de Casteele M, Magnuson MA, Heimberg H, Wright CVE. Spatiotemporal patterns of multipotentiality in Ptf1a-expressing cells during pancreas organogenesis and injury-induced facultative restoration. Development 2013; 140:751-64. [PMID: 23325761 DOI: 10.1242/dev.090159] [Citation(s) in RCA: 222] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pancreatic multipotent progenitor cells (MPCs) produce acinar, endocrine and duct cells during organogenesis, but their existence and location in the mature organ remain contentious. We used inducible lineage-tracing from the MPC-instructive gene Ptf1a to define systematically in mice the switch of Ptf1a(+) MPCs to unipotent proacinar competence during the secondary transition, their rapid decline during organogenesis, and absence from the mature organ. Between E11.5 and E15.5, we describe tip epithelium heterogeneity, suggesting that putative Ptf1a(+)Sox9(+)Hnf1β(+) MPCs are intermingled with Ptf1a(HI)Sox9(LO) proacinar progenitors. In the adult, pancreatic duct ligation (PDL) caused facultative reactivation of multipotency factors (Sox9 and Hnf1β) in Ptf1a(+) acini, which undergo rapid reprogramming to duct cells and longer-term reprogramming to endocrine cells, including insulin(+) β-cells that are mature by the criteria of producing Pdx1(HI), Nkx6.1(+) and MafA(+). These Ptf1a lineage-derived endocrine/β-cells are likely formed via Ck19(+)/Hnf1β(+)/Sox9(+) ductal and Ngn3(+) endocrine progenitor intermediates. Acinar to endocrine/β-cell transdifferentiation was enhanced by combining PDL with pharmacological elimination of pre-existing β-cells. Thus, we show that acinar cells, without exogenously introduced factors, can regain aspects of embryonic multipotentiality under injury, and convert into mature β-cells.
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Affiliation(s)
- Fong Cheng Pan
- Vanderbilt University Program in Developmental Biology, Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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44
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Abstract
The pancreatic beta cell is responsible for maintaining normoglycaemia by secreting an appropriate amount of insulin according to blood glucose levels. The accurate sensing of the beta cell extracellular environment is therefore crucial to this endocrine function and is transmitted via its cell surface proteome. Various surface proteins that mediate or affect beta cell endocrine function have been identified, including growth factor and cytokine receptors, transporters, ion channels and proteases, attributing important roles to surface proteins in the adaptive behaviour of beta cells in response to acute and chronic environmental changes. However, the largely unknown composition of the beta cell surface proteome is likely to harbour yet more information about these mechanisms and provide novel points of therapeutic intervention and diagnostic tools. This article will provide an overview of the functional complexity of the beta cell surface proteome and selected surface proteins, outline the mechanisms by which their activity may be modulated, discuss the methods and challenges of comprehensively mapping and studying the beta cell surface proteome, and address the potential of this interesting subproteome for diagnostic and therapeutic applications in human disease.
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Affiliation(s)
- I. Stützer
- Institute of Molecular Systems Biology, HPT E73, ETH Zurich, Wolfgang-Pauli-Str. 16, 8093 Zurich, Switzerland
- Competence Center for Systems Physiology and Metabolic Diseases, ETH Zurich, Zurich, Switzerland
| | - D. Esterházy
- Institute of Molecular Systems Biology, HPT E73, ETH Zurich, Wolfgang-Pauli-Str. 16, 8093 Zurich, Switzerland
- Competence Center for Systems Physiology and Metabolic Diseases, ETH Zurich, Zurich, Switzerland
| | - M. Stoffel
- Institute of Molecular Systems Biology, HPT E73, ETH Zurich, Wolfgang-Pauli-Str. 16, 8093 Zurich, Switzerland
- Competence Center for Systems Physiology and Metabolic Diseases, ETH Zurich, Zurich, Switzerland
- Faculty of Medicine, University of Zurich, Zurich, Switzerland
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45
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Balon TW. SGLT and GLUT: are they teammates? Focus on “Mouse SGLT3a generates proton-activated currents but does not transport sugar”. Am J Physiol Cell Physiol 2012; 302:C1071-2. [DOI: 10.1152/ajpcell.00054.2012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Thomas W. Balon
- Diabetes Research Unit, Section of Endocrinology, Department of Medicine, Boston University Medical Center, Boston, Massachusetts
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46
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Merigo F, Benati D, Cristofoletti M, Osculati F, Sbarbati A. Glucose transporters are expressed in taste receptor cells. J Anat 2011. [PMID: 21592100 DOI: 10.1111/j.1469‐7580.2011.01385.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In the intestine, changes of sugar concentration generated in the lumen during digestion induce adaptive responses of glucose transporters in the epithelium. A close matching between the intestinal expression of glucose transporters and the composition and amount of the diet has been provided by several experiments. Functional evidence has demonstrated that the regulation of glucose transporters into enterocytes is induced by the sensing of sugar of the enteroendocrine cells through activation of sweet taste receptors (T1R2 and T1R3) and their associated elements of G-protein-linked signaling pathways (e.g. α-gustducin, phospholipase C β type 2 and transient receptor potential channel M5), which are signaling molecules also involved in the perception of sweet substances in the taste receptor cells (TRCs) of the tongue. Considering this phenotypical similarity between the intestinal cells and TRCs, we evaluated whether the TRCs themselves possess proteins of the glucose transport mechanism. Therefore, we investigated the expression of the typical intestinal glucose transporters (i.e. GLUT2, GLUT5 and SGLT1) in rat circumvallate papillae, using immunohistochemistry, double-labeling immunofluorescence, immunoelectron microscopy and reverse transcriptase-polymerase chain reaction analysis. The results showed that GLUT2, GLUT5 and SGLT1 are expressed in TRCs; their immunoreactivity was also observed in cells that displayed staining for α-gustducin and T1R3 receptor. The immunoelectron microscopic results confirmed that GLUT2, GLUT5 and SGLT1 were predominantly expressed in cells with ultrastructural characteristics of chemoreceptor cells. The presence of glucose transporters in TRCs adds a further link between chemosensory information and cellular responses to sweet stimuli that may have important roles in glucose homeostasis, contributing to a better understanding of the pathways implicated in glucose metabolism.
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Affiliation(s)
- Flavia Merigo
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Human Anatomy and Histology Section, School of Medicine, University of Verona, Verona, Italy.
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47
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Merigo F, Benati D, Cristofoletti M, Osculati F, Sbarbati A. Glucose transporters are expressed in taste receptor cells. J Anat 2011; 219:243-52. [PMID: 21592100 DOI: 10.1111/j.1469-7580.2011.01385.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In the intestine, changes of sugar concentration generated in the lumen during digestion induce adaptive responses of glucose transporters in the epithelium. A close matching between the intestinal expression of glucose transporters and the composition and amount of the diet has been provided by several experiments. Functional evidence has demonstrated that the regulation of glucose transporters into enterocytes is induced by the sensing of sugar of the enteroendocrine cells through activation of sweet taste receptors (T1R2 and T1R3) and their associated elements of G-protein-linked signaling pathways (e.g. α-gustducin, phospholipase C β type 2 and transient receptor potential channel M5), which are signaling molecules also involved in the perception of sweet substances in the taste receptor cells (TRCs) of the tongue. Considering this phenotypical similarity between the intestinal cells and TRCs, we evaluated whether the TRCs themselves possess proteins of the glucose transport mechanism. Therefore, we investigated the expression of the typical intestinal glucose transporters (i.e. GLUT2, GLUT5 and SGLT1) in rat circumvallate papillae, using immunohistochemistry, double-labeling immunofluorescence, immunoelectron microscopy and reverse transcriptase-polymerase chain reaction analysis. The results showed that GLUT2, GLUT5 and SGLT1 are expressed in TRCs; their immunoreactivity was also observed in cells that displayed staining for α-gustducin and T1R3 receptor. The immunoelectron microscopic results confirmed that GLUT2, GLUT5 and SGLT1 were predominantly expressed in cells with ultrastructural characteristics of chemoreceptor cells. The presence of glucose transporters in TRCs adds a further link between chemosensory information and cellular responses to sweet stimuli that may have important roles in glucose homeostasis, contributing to a better understanding of the pathways implicated in glucose metabolism.
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Affiliation(s)
- Flavia Merigo
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Human Anatomy and Histology Section, School of Medicine, University of Verona, Verona, Italy.
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48
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Lock LT, Laychock SG, Tzanakakis ES. Pseudoislets in stirred-suspension culture exhibit enhanced cell survival, propagation and insulin secretion. J Biotechnol 2011; 151:278-86. [DOI: 10.1016/j.jbiotec.2010.12.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 10/29/2010] [Accepted: 12/15/2010] [Indexed: 11/24/2022]
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49
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Augustin R. The protein family of glucose transport facilitators: It's not only about glucose after all. IUBMB Life 2010; 62:315-33. [PMID: 20209635 DOI: 10.1002/iub.315] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The protein family of facilitative glucose transporters comprises 14 isoforms that share common structural features such as 12 transmembrane domains, N- and C-termini facing the cytoplasm of the cell, and a N-glycosylation side either within the first or fifth extracellular loop. Based on their sequence homology, three classes can be distinguished: class I includes GLUT1-4 and GLUT14, class II the "odd transporters" GLUT5, 7, 9, 11, and class III the "even transporters" GLUT6, 8, 10, 12 and the proton driven myoinositol transporter HMIT (or GLUT13). With the cloning and characterization of the more recent class II and III isoforms, it became apparent that despite their structural similarities, the different isoforms not only show a distinct tissue-specific expression pattern but also show distinct characteristics such as alternative splicing, specific (sub)cellular localization, and affinities for a spectrum of substrates. This review summarizes the current understanding of the physiological role for the various transport facilitators based on human genetically inherited disorders or single-nucleotide polymorphisms and knockout mice models. The emphasis of the review will be on the potential functional role of the more recent isoforms.
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Affiliation(s)
- Robert Augustin
- Department of Cardiometabolic Diseases Research, Boehringer-Ingelheim Pharma GmbH&Co KG, Biberach a.d. Riss, Germany.
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50
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Lange K. Fundamental role of microvilli in the main functions of differentiated cells: Outline of an universal regulating and signaling system at the cell periphery. J Cell Physiol 2010; 226:896-927. [PMID: 20607764 DOI: 10.1002/jcp.22302] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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