101
|
Lecomte MJ, Pechberty S, Machado C, Da Barroca S, Ravassard P, Scharfmann R, Czernichow P, Duvillié B. Aggregation of Engineered Human β-Cells Into Pseudoislets: Insulin Secretion and Gene Expression Profile in Normoxic and Hypoxic Milieu. CELL MEDICINE 2016; 8:99-112. [PMID: 28003935 DOI: 10.3727/215517916x692843] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Innovative treatments to cure type 1 diabetes are being actively researched. Among the different strategies, the replacement of β-cells has given promising results. Classically, islets from cadaveric donors are transplanted into diabetic patients, but recently phase I clinical trials that use stem cell-derived β-cells have been started. Such protocols require either an immunosuppressive treatment or the macroencapsulation of the β-cells. They involve cell aggregation and the exposure of the cells to hypoxia. Using an engineered human β-cell, we have addressed these two problems: a novel human β-cell line called EndoC-βH3 was cultured as single cells or aggregated clusters. EndoC-βH3 cells were also cultured at normal atmospheric oxygen tension (pO2 = 21%) or hypoxia (pO2 = 3%) in the presence or absence of modulators of the hypoxia-inducible factor 1α (HIF1α) pathway. Cell aggregation improved glucose-stimulated insulin secretion, demonstrating the benefit of cell-cell contacts. Low oxygen tension decreased β-cell viability and their sensitivity to glucose, but did not alter insulin production nor the insulin secretion capacity of the remaining cells. To investigate the role of HIF1α, we first used a HIF stabilizer at pO2 = 21%. This led to a mild decrease in cell viability, impaired glucose sensitivity, and altered insulin secretion. Finally, we used a HIF inhibitor on EndoC-βH3 pseudoislets exposed to hypoxia. Such treatment considerably decreased cell viability. In conclusion, aggregation of the EndoC-βH3 cells seems to be important to improve their function. A fraction of the EndoC-βH3 cells are resistant to hypoxia, depending on the level of activity of HIF1α. Thus, these cells represent a good human cell model for future investigations on islet cell transplantation analysis.
Collapse
Affiliation(s)
- Marie-José Lecomte
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Séverine Pechberty
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Cécile Machado
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Sandra Da Barroca
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Philippe Ravassard
- † Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, Institut du cerveau et de la moelle (ICM)-Hôpital Pitié-Salpêtrière , Paris , France
| | - Raphaël Scharfmann
- ‡INSERM U1016, Institut Cochin, Paris, France; §Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| | - Paul Czernichow
- Univercell-Biosolutions, Centre de recherche des Cordeliers , Paris , France
| | - Bertrand Duvillié
- ‡INSERM U1016, Institut Cochin, Paris, France; §Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| |
Collapse
|
102
|
McGuigan AP, Javaherian S. Tissue Patterning: Translating Design Principles from In Vivo to In Vitro. Annu Rev Biomed Eng 2016; 18:1-24. [DOI: 10.1146/annurev-bioeng-083115-032943] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Alison P. McGuigan
- Department of Chemical Engineering and Applied Chemistry and
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3E5, Canada;
| | | |
Collapse
|
103
|
Yokawa S, Furuno T, Suzuki T, Inoh Y, Suzuki R, Hirashima N. Effect of Cell Adhesion Molecule 1 Expression on Intracellular Granule Movement in Pancreatic α Cells. Cell Biochem Biophys 2016; 74:391-8. [DOI: 10.1007/s12013-016-0737-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 05/23/2016] [Indexed: 01/18/2023]
|
104
|
Zhang C, Caldwell TA, Mirbolooki MR, Duong D, Park EJ, Chi NW, Chessler SD. Extracellular CADM1 interactions influence insulin secretion by rat and human islet β-cells and promote clustering of syntaxin-1. Am J Physiol Endocrinol Metab 2016; 310:E874-85. [PMID: 27072493 PMCID: PMC4935136 DOI: 10.1152/ajpendo.00318.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 04/08/2016] [Indexed: 11/22/2022]
Abstract
Contact between β-cells is necessary for their normal function. Identification of the proteins mediating the effects of β-cell-to-β-cell contact is a necessary step toward gaining a full understanding of the determinants of β-cell function and insulin secretion. The secretory machinery of the β-cells is nearly identical to that of central nervous system (CNS) synapses, and we hypothesize that the transcellular protein interactions that drive maturation of the two secretory machineries upon contact of one cell (or neural process) with another are also highly similar. Two such transcellular interactions, important for both synaptic and β-cell function, have been identified: EphA/ephrin-A and neuroligin/neurexin. Here, we tested the role of another synaptic cleft protein, CADM1, in insulinoma cells and in rat and human islet β-cells. We found that CADM1 is a predominant CADM isoform in β-cells. In INS-1 cells and primary β-cells, CADM1 constrains insulin secretion, and its expression decreases after prolonged glucose stimulation. Using a coculture model, we found that CADM1 also influences insulin secretion in a transcellular manner. We asked whether extracellular CADM1 interactions exert their influence via the same mechanisms by which they influence neurotransmitter exocytosis. Our results suggest that, as in the CNS, CADM1 interactions drive exocytic site assembly and promote actin network formation. These results support the broader hypothesis that the effects of cell-cell contact on β-cell maturation and function are mediated by the same extracellular protein interactions that drive the formation of the presynaptic exocytic machinery. These interactions may be therapeutic targets for reversing β-cell dysfunction in diabetes.
Collapse
Affiliation(s)
- Charles Zhang
- Department of Medicine, University of California, Irvine, School of Medicine, Irvine, California
| | - Thomas A Caldwell
- Department of Medicine, University of California, Irvine, School of Medicine, Irvine, California
| | - M Reza Mirbolooki
- Department of Medicine, University of California, Irvine, School of Medicine, Irvine, California
| | - Diana Duong
- Pediatric Diabetes Research Center, University of California San Diego, La Jolla, California; and
| | - Eun Jee Park
- Department of Medicine, University of California, Irvine, School of Medicine, Irvine, California
| | - Nai-Wen Chi
- Research Service, Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Steven D Chessler
- Department of Medicine, University of California, Irvine, School of Medicine, Irvine, California;
| |
Collapse
|
105
|
Chen W, Zhang Q, Luk BT, Fang RH, Liu Y, Gao W, Zhang L. Coating nanofiber scaffolds with beta cell membrane to promote cell proliferation and function. NANOSCALE 2016; 8:10364-70. [PMID: 27139582 PMCID: PMC4866884 DOI: 10.1039/c6nr00535g] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The cell membrane cloaking technique has emerged as an intriguing strategy in nanomaterial functionalization. Coating synthetic nanostructures with natural cell membranes bestows the nanostructures with unique cell surface antigens and functions. Previous studies have focused primarily on development of cell membrane-coated spherical nanoparticles and the uses thereof. Herein, we attempt to extend the cell membrane cloaking technique to nanofibers, a class of functional nanomaterials that are drastically different from nanoparticles in terms of dimensional and mechanophysical characteristics. Using pancreatic beta cells as a model cell line, we demonstrate successful preparation of cell membrane-coated nanofibers and validate that the modified nanofibers possess an antigenic exterior closely resembling that of the source beta cells. When such nanofiber scaffolds are used to culture beta cells, both cell proliferation rate and function are significantly enhanced. Specifically, glucose-dependent insulin secretion from the cells is increased by near five-fold compared with the same beta cells cultured in regular, unmodified nanofiber scaffolds. Overall, coating cell membranes onto nanofibers could add another dimension of flexibility and controllability in harnessing cell membrane functions and offer new opportunities for innovative applications.
Collapse
Affiliation(s)
- Wansong Chen
- Department of NanoEngineering and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA.
| | | | | | | | | | | | | |
Collapse
|
106
|
Gylfe E. Glucose control of glucagon secretion-'There's a brand-new gimmick every year'. Ups J Med Sci 2016; 121:120-32. [PMID: 27044660 PMCID: PMC4900067 DOI: 10.3109/03009734.2016.1154905] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 02/10/2016] [Accepted: 02/11/2016] [Indexed: 11/13/2022] Open
Abstract
Glucagon from the pancreatic α-cells is a major blood glucose-regulating hormone whose most important role is to prevent hypoglycaemia that can be life-threatening due to the brain's strong dependence on glucose as energy source. Lack of blood glucose-lowering insulin after malfunction or autoimmune destruction of the pancreatic β-cells is the recognized cause of diabetes, but recent evidence indicates that diabetic hyperglycaemia would not develop unless lack of insulin was accompanied by hypersecretion of glucagon. Glucagon release has therefore become an increasingly important target in diabetes management. Despite decades of research, an understanding of how glucagon secretion is regulated remains elusive, and fundamentally different mechanisms continue to be proposed. The autonomous nervous system is an important determinant of glucagon release, but it is clear that secretion is also directly regulated within the pancreatic islets. The present review focuses on pancreatic islet mechanisms involved in glucose regulation of glucagon release. It will be argued that α-cell-intrinsic processes are most important for regulation of glucagon release during recovery from hypoglycaemia and that paracrine inhibition by somatostatin from the δ-cells shapes pulsatile glucagon release in hyperglycaemia. The electrically coupled β-cells ultimately determine islet hormone pulsatility by releasing synchronizing factors that affect the α- and δ-cells.
Collapse
Affiliation(s)
- Erik Gylfe
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| |
Collapse
|
107
|
Kriebel J, Herder C, Rathmann W, Wahl S, Kunze S, Molnos S, Volkova N, Schramm K, Carstensen-Kirberg M, Waldenberger M, Gieger C, Peters A, Illig T, Prokisch H, Roden M, Grallert H. Association between DNA Methylation in Whole Blood and Measures of Glucose Metabolism: KORA F4 Study. PLoS One 2016; 11:e0152314. [PMID: 27019061 PMCID: PMC4809492 DOI: 10.1371/journal.pone.0152314] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 03/11/2016] [Indexed: 12/22/2022] Open
Abstract
Epigenetic regulation has been postulated to affect glucose metabolism, insulin sensitivity and the risk of type 2 diabetes. Therefore, we performed an epigenome-wide association study for measures of glucose metabolism in whole blood samples of the population-based Cooperative Health Research in the Region of Augsburg F4 study using the Illumina HumanMethylation 450 BeadChip. We identified a total of 31 CpG sites where methylation level was associated with measures of glucose metabolism after adjustment for age, sex, smoking, and estimated white blood cell proportions and correction for multiple testing using the Benjamini-Hochberg (B-H) method (four for fasting glucose, seven for fasting insulin, 25 for homeostasis model assessment-insulin resistance [HOMA-IR]; B-H-adjusted p-values between 9.2x10(-5) and 0.047). In addition, DNA methylation at cg06500161 (annotated to ABCG1) was associated with all the aforementioned phenotypes and 2-hour glucose (B-H-adjusted p-values between 9.2x10(-5) and 3.0x10(-3)). Methylation status of additional three CpG sites showed an association with fasting insulin only after additional adjustment for body mass index (BMI) (B-H-adjusted p-values = 0.047). Overall, effect strengths were reduced by around 30% after additional adjustment for BMI, suggesting that this variable has an influence on the investigated phenotypes. Furthermore, we found significant associations between methylation status of 21 of the aforementioned CpG sites and 2-hour insulin in a subset of samples with seven significant associations persisting after additional adjustment for BMI. In a subset of 533 participants, methylation of the CpG site cg06500161 (ABCG1) was inversely associated with ABCG1 gene expression (B-H-adjusted p-value = 1.5x10(-9)). Additionally, we observed an enrichment of the top 1,000 CpG sites for diabetes-related canonical pathways using Ingenuity Pathway Analysis. In conclusion, our study indicates that DNA methylation and diabetes-related traits are associated and that these associations are partially BMI-dependent. Furthermore, the interaction of ABCG1 with glucose metabolism is modulated by epigenetic processes.
Collapse
Affiliation(s)
- Jennifer Kriebel
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
| | - Christian Herder
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Wolfgang Rathmann
- Institute for Biometrics and Epidemiology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Simone Wahl
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
| | - Sonja Kunze
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
| | - Sophie Molnos
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
| | - Nadezda Volkova
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
| | - Katharina Schramm
- Institute of Human Genetics, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Human Genetics, Technische Universitaet Muenchen, Munich, Germany
| | - Maren Carstensen-Kirberg
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Melanie Waldenberger
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
| | - Christian Gieger
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
| | - Annette Peters
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
| | - Thomas Illig
- Hannover Unified Biobank, Hannover Medical School, Hanover, Germany
- Institute of Human Genetics, Hannover Medical School, Hanover, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Human Genetics, Technische Universitaet Muenchen, Munich, Germany
| | - Michael Roden
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Duesseldorf, Duesseldorf, Germany
- Department of Endocrinology and Diabetology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Harald Grallert
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Muenchen-Neuherberg, Germany
| |
Collapse
|
108
|
Wang Y, Wu Z, Thorin E, Tremblay J, Lavoie JL, Luo H, Peng J, Qi S, Wu T, Chen F, Shen J, Hu S, Wu J. Estrogen and testosterone in concert with EFNB3 regulate vascular smooth muscle cell contractility and blood pressure. Am J Physiol Heart Circ Physiol 2016; 310:H861-72. [PMID: 26851246 DOI: 10.1152/ajpheart.00873.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 02/02/2016] [Indexed: 12/20/2022]
Abstract
EPH kinases and their ligands, ephrins (EFNs), have vital and diverse biological functions, although their function in blood pressure (BP) control has not been studied in detail. In the present study, we report that Efnb3 gene knockout (KO) led to increased BP in female but not male mice. Vascular smooth muscle cells (VSMCs) were target cells for EFNB3 function in BP regulation. The deletion of EFNB3 augmented contractility of VSMCs from female but not male KO mice, compared with their wild-type (WT) counterparts. Estrogen augmented VSMC contractility while testosterone reduced it in the absence of EFNB3, although these sex hormones had no effect on the contractility of VSMCs from WT mice. The effect of estrogen on KO VSMC contractility was via a nongenomic pathway involving GPER, while that of testosterone was likely via a genomic pathway, according to VSMC contractility assays and GPER knockdown assays. The sex hormone-dependent contraction phenotypes in KO VSMCs were reflected in BP in vivo. Ovariectomy rendered female KO mice normotensive. At the molecular level, EFNB3 KO in VSMCs resulted in reduced myosin light chain kinase phosphorylation, an event enhancing sensitivity to Ca(2+)flux in VSMCs. Our investigation has revealed previously unknown EFNB3 functions in BP regulation and show that EFNB3 might be a hypertension risk gene in certain individuals.
Collapse
Affiliation(s)
- Yujia Wang
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Zenghui Wu
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada;
| | - Eric Thorin
- Montreal Heart Institute, Montreal, Quebec, Canada
| | - Johanne Tremblay
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Julie L Lavoie
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada; Département de Kinésiologie, Université de Montréal, Montreal, Quebec, Canada
| | - Hongyu Luo
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Junzheng Peng
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Shijie Qi
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Tao Wu
- Institute of Cardiology, First Affiliated Hospital, Zhejiang University Medical College, Hangzhou, China; and
| | - Fei Chen
- Institute of Cardiology, First Affiliated Hospital, Zhejiang University Medical College, Hangzhou, China; and
| | - Jianzhong Shen
- Institute of Cardiology, First Affiliated Hospital, Zhejiang University Medical College, Hangzhou, China; and
| | - Shenjiang Hu
- Institute of Cardiology, First Affiliated Hospital, Zhejiang University Medical College, Hangzhou, China; and
| | - Jiangping Wu
- Research Centre, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada; Nephrology Service, CRCHUM, Montreal, Quebec, Canada
| |
Collapse
|
109
|
Mechanisms of ephrin-Eph signalling in development, physiology and disease. Nat Rev Mol Cell Biol 2016; 17:240-56. [PMID: 26790531 DOI: 10.1038/nrm.2015.16] [Citation(s) in RCA: 461] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eph receptor Tyr kinases and their membrane-tethered ligands, the ephrins, elicit short-distance cell-cell signalling and thus regulate many developmental processes at the interface between pattern formation and morphogenesis, including cell sorting and positioning, and the formation of segmented structures and ordered neural maps. Their roles extend into adulthood, when ephrin-Eph signalling regulates neuronal plasticity, homeostatic events and disease processes. Recently, new insights have been gained into the mechanisms of ephrin-Eph signalling in different cell types, and into the physiological importance of ephrin-Eph in different organs and in disease, raising questions for future research directions.
Collapse
|
110
|
Hutchens T, Piston DW. EphA4 Receptor Forward Signaling Inhibits Glucagon Secretion From α-Cells. Diabetes 2015; 64:3839-51. [PMID: 26251403 PMCID: PMC4613968 DOI: 10.2337/db15-0488] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/29/2015] [Indexed: 12/18/2022]
Abstract
The loss of inhibition of glucagon secretion exacerbates hyperglycemia in type 1 and 2 diabetes. However, the molecular mechanisms that regulate glucagon secretion in unaffected and diabetic states remain relatively unexplained. We present evidence supporting a new model of juxtacrine-mediated regulation of glucagon secretion where neighboring islet cells negatively regulate glucagon secretion through tonic stimulation of α-cell EphA receptors. Primarily through EphA4 receptors, this stimulation correlates with maintenance of a dense F-actin network. In islets, additional stimulation and inhibition of endogenous EphA forward signaling result in inhibition and enhancement, respectively, of glucagon secretion, accompanied by an increase and decrease, respectively, in α-cell F-actin density. Sorted α-cells lack endogenous stimulation of EphA forward signaling from neighboring cells, resulting in enhanced basal glucagon secretion as compared with islets and the elimination of glucose inhibition of glucagon secretion. Restoration of EphA forward signaling in sorted α-cells recapitulates both normal basal glucagon secretion and glucose inhibition of glucagon secretion. Additionally, α-cell-specific EphA4(-/-) mice exhibit abnormal glucagon dynamics, and EphA4(-/-) α-cells contain less dense F-actin networks than EphA4(+/+) α-cells. This juxtacrine-mediated model provides insight into the functional and dysfunctional regulation of glucagon secretion and opens up new therapeutic strategies for the clinical management of diabetes.
Collapse
Affiliation(s)
- Troy Hutchens
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - David W Piston
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
| |
Collapse
|
111
|
Jain D, Weber G, Eberhard D, Mehana AE, Eglinger J, Welters A, Bartosinska B, Jeruschke K, Weiss J, Päth G, Ariga H, Seufert J, Lammert E. DJ-1 Protects Pancreatic Beta Cells from Cytokine- and Streptozotocin-Mediated Cell Death. PLoS One 2015; 10:e0138535. [PMID: 26422139 PMCID: PMC4589499 DOI: 10.1371/journal.pone.0138535] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 09/01/2015] [Indexed: 01/07/2023] Open
Abstract
A hallmark feature of type 1 and type 2 diabetes mellitus is the progressive dysfunction and loss of insulin-producing pancreatic beta cells, and inflammatory cytokines are known to trigger beta cell death. Here we asked whether the anti-oxidant protein DJ-1 encoded by the Parkinson’s disease gene PARK7 protects islet cells from cytokine- and streptozotocin-mediated cell death. Wild type and DJ-1 knockout mice (KO) were treated with multiple low doses of streptozotocin (MLDS) to induce inflammatory beta cell stress and cell death. Subsequently, glucose tolerance tests were performed, and plasma insulin as well as fasting and random blood glucose concentrations were monitored. Mitochondrial morphology and number of insulin granules were quantified in beta cells. Moreover, islet cell damage was determined in vitro after streptozotocin and cytokine treatment of isolated wild type and DJ-1 KO islets using calcein AM/ethidium homodimer-1 staining and TUNEL staining. Compared to wild type mice, DJ-1 KO mice became diabetic following MLDS treatment. Insulin concentrations were substantially reduced, and fasting blood glucose concentrations were significantly higher in MLDS-treated DJ-1 KO mice compared to equally treated wild type mice. Rates of beta cell apoptosis upon MLDS treatment were twofold higher in DJ-1 KO mice compared to wild type mice, and in vitro inflammatory cytokines led to twice as much beta cell death in pancreatic islets from DJ-1 KO mice versus those of wild type mice. In conclusion, this study identified the anti-oxidant protein DJ-1 as being capable of protecting pancreatic islet cells from cell death induced by an inflammatory and cytotoxic setting.
Collapse
Affiliation(s)
- Deepak Jain
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
- Institute for Beta Cell Biology, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
- German Center for Diabetes Research (DZD e.V.), Düsseldorf Partner Institute, Düsseldorf, Germany
| | - Gesine Weber
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
| | - Daniel Eberhard
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
- Institute for Beta Cell Biology, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
| | - Amir E. Mehana
- Division of Endocrinology and Diabetology, Department of Internal Medicine II, University Hospital of Freiburg, Freiburg, Germany
- Department of Zoology, Faculty of Science, Suez Canal University, Ismailia, Egypt
| | - Jan Eglinger
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
- Institute for Beta Cell Biology, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
- German Center for Diabetes Research (DZD e.V.), Düsseldorf Partner Institute, Düsseldorf, Germany
| | - Alena Welters
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
- Institute for Beta Cell Biology, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
- German Center for Diabetes Research (DZD e.V.), Düsseldorf Partner Institute, Düsseldorf, Germany
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children’s Hospital Düsseldorf, Düsseldorf, Germany
| | - Barbara Bartosinska
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
| | - Kay Jeruschke
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
| | - Jürgen Weiss
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
| | - Günter Päth
- Division of Endocrinology and Diabetology, Department of Internal Medicine II, University Hospital of Freiburg, Freiburg, Germany
| | - Hiroyoshi Ariga
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-Ku, N12 W6, Sapporo, Japan
| | - Jochen Seufert
- Division of Endocrinology and Diabetology, Department of Internal Medicine II, University Hospital of Freiburg, Freiburg, Germany
| | - Eckhard Lammert
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
- Institute for Beta Cell Biology, German Diabetes Center at Heinrich Heine University, Leibniz Center for Diabetes Research, Düsseldorf, Germany
- German Center for Diabetes Research (DZD e.V.), Düsseldorf Partner Institute, Düsseldorf, Germany
- * E-mail:
| |
Collapse
|
112
|
Hu Y, Wang X, Wu Y, Jin W, Cheng B, Fang X, Martel-Pelletier J, Kapoor M, Peng J, Qi S, Shi G, Wu J, Luo H. Role of EFNB1 and EFNB2 in Mouse Collagen-Induced Arthritis and Human Rheumatoid Arthritis. Arthritis Rheumatol 2015; 67:1778-88. [PMID: 25779027 DOI: 10.1002/art.39116] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 03/10/2015] [Indexed: 02/05/2023]
Abstract
OBJECTIVE EFNB1 and EFNB2 are ligands for Eph receptor tyrosine kinases. This study was undertaken to investigate how the expression of Efnb1 and Efnb2 on murine T cells influences the pathogenesis of collagen-induced arthritis (CIA) and to assess correlations between the T cell expression of these 2 molecules and measures of disease activity in patients with rheumatoid arthritis (RA). METHODS CIA was studied in mice with T cell-specific deletion (double gene knockout [dKO]) of both Efnb1 and Efnb2. Expression of EFNB1 and EFNB2 messenger RNA (mRNA) in peripheral blood T cells from patients with RA was determined by quantitative reverse transcription- polymerase chain reaction. RESULTS In dKO mice, clinical scores of arthritis were reduced compared to those in wild-type (WT) control mice. Serum collagen-specific antibody titers in dKO mice were lower than those in WT mice. In analyses based on equal cell numbers, dKO mouse T cells, as compared to WT mouse T cells, provided vastly inferior help to B cells in the production of collagen-specific antibodies in vitro. T cells from dKO mice were compromised in their ability to migrate to the arthritic paws in vivo and in their ability to undergo chemotaxis toward CXCL12 in vitro. Deletion mutation of Efnb1 and Efnb2 intracellular tails revealed critical regions in controlling T cell chemotaxis. T cells from RA patients expressed higher EFNB1 mRNA levels, which correlated with RA symptoms and laboratory findings. CONCLUSION Efnb1 and Efnb2 in T cells are essential for pathogenic antibody production and for T cell migration to the inflamed paws in mice with CIA. These findings suggest that the expression of EFNB1 in T cells might be a useful parameter for monitoring RA disease activity and treatment responses.
Collapse
Affiliation(s)
- Yan Hu
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Xuehai Wang
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Yongqiang Wu
- West China Hospital of Sichuan University, Chengdu, China
| | - Wei Jin
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Baoli Cheng
- First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Xiangming Fang
- First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | | | - Mohit Kapoor
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Junzheng Peng
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Shijie Qi
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Guixiu Shi
- First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Jiangping Wu
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Hongyu Luo
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| |
Collapse
|
113
|
Yesildag B, Bock T, Herrmanns K, Wollscheid B, Stoffel M. Kin of IRRE-like Protein 2 Is a Phosphorylated Glycoprotein That Regulates Basal Insulin Secretion. J Biol Chem 2015; 290:25891-906. [PMID: 26324709 DOI: 10.1074/jbc.m115.684704] [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: 08/11/2015] [Indexed: 12/17/2022] Open
Abstract
Direct interactions among pancreatic β-cells via cell surface proteins inhibit basal and enhance stimulated insulin secretion. Here, we functionally and biochemically characterized Kirrel2, an immunoglobulin superfamily protein with β-cell-specific expression in the pancreas. Our results show that Kirrel2 is a phosphorylated glycoprotein that co-localizes and interacts with the adherens junction proteins E-cadherin and β-catenin in MIN6 cells. We further demonstrate that the phosphosites Tyr(595-596) are functionally relevant for the regulation of Kirrel2 stability and localization. Analysis of the extracellular and intracellular domains of Kirrel2 revealed that it is cleaved and shed from MIN6 cells and that the remaining membrane spanning cytoplasmic domain is processed by γ-secretase complex. Kirrel2 knockdown with RNA interference in MIN6 cells and ablation of Kirrel2 from mice with genetic deletion resulted in increased basal insulin secretion from β-cells, with no immediate influence on stimulated insulin secretion, total insulin content, or whole body glucose metabolism. Our results show that in pancreatic β-cells Kirrel2 localizes to adherens junctions, is regulated by multiple post-translational events, including glycosylation, extracellular cleavage, and phosphorylation, and engages in the regulation of basal insulin secretion.
Collapse
Affiliation(s)
- Burcak Yesildag
- From the Department of Biology, Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Otto-Stern-Weg 7, 8093 Zurich
| | - Thomas Bock
- the Department of Health Sciences and Technology, Institute of Molecular Systems Biology, Swiss Federal Institute of Technology Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, and
| | - Karolin Herrmanns
- From the Department of Biology, Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Otto-Stern-Weg 7, 8093 Zurich
| | - Bernd Wollscheid
- the Department of Health Sciences and Technology, Institute of Molecular Systems Biology, Swiss Federal Institute of Technology Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, and
| | - Markus Stoffel
- From the Department of Biology, Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Otto-Stern-Weg 7, 8093 Zurich, the Department of Health Sciences and Technology, Institute of Molecular Systems Biology, Swiss Federal Institute of Technology Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, and the Faculty of Medicine, University of Zurich, 8091 Zurich, Switzerland
| |
Collapse
|
114
|
Trans-Activation between EphA and FGFR Regulates Self-Renewal and Differentiation of Mouse Embryonic Neural Stem/Progenitor Cells via Differential Activation of FRS2α. PLoS One 2015; 10:e0128826. [PMID: 26024354 PMCID: PMC4449203 DOI: 10.1371/journal.pone.0128826] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/30/2015] [Indexed: 12/05/2022] Open
Abstract
Ephs and FGFRs belong to a superfamily of receptor tyrosine kinases, playing important roles in stem cell biology. We previously reported that EphA4 and FGFR form a heterodimer following stimulation with ligands, trans-activating each other and signaling through a docking protein, FRS2α, that binds to both receptors. Here, we investigated whether the interaction between EphA4 and FGFRs can be generalized to other Ephs and FGFRs, and, in addition, examined the downstream signal mediating their function in embryonic neural stem/progenitor cells. We revealed that various Ephs and FGFRs interact with each other through similar molecular domains. When neural stem/progenitor cells were stimulated with FGF2 and ephrin-A1, the signal transduced from the EphA4/FGFR/FRS2α complex enhanced self-renewal, while stimulation with ephrin-A1 alone induced neuronal differentiation. The downstream signal required for neuronal differentiation appears to be MAP kinase mainly linked to the Ras family of G proteins. MAP kinase activation was delayed and sustained, distinct from the transient activation induced by FGF2. Interestingly, this effect on neuronal differentiation required the presence of FGFRs. Specific FGFR inhibitor almost completely abolished the function of ephrin-A1 stimulation. These findings suggest that the ternary complex of EphA, FGFR and FRS2α formed by ligand stimulation regulates self-renewal and differentiation of mouse embryonic neural stem/progenitor cells by ligand-specific fine tuning of the downstream signal via FRS2α.
Collapse
|
115
|
Wang Y, Thorin E, Luo H, Tremblay J, Lavoie JL, Wu Z, Peng J, Qi S, Wu J. EPHB4 Protein Expression in Vascular Smooth Muscle Cells Regulates Their Contractility, and EPHB4 Deletion Leads to Hypotension in Mice. J Biol Chem 2015; 290:14235-44. [PMID: 25903126 DOI: 10.1074/jbc.m114.621615] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Indexed: 11/06/2022] Open
Abstract
EPH kinases are the largest family of receptor tyrosine kinases, and their ligands, ephrins (EFNs), are also cell surface molecules. This work presents evidence that EPHB4 on vascular smooth muscle cells (VSMCs) is involved in blood pressure regulation. We generated gene KO mice with smooth muscle cell-specific deletion of EPHB4. Male KO mice, but not female KO mice, were hypotensive. VSMCs from male KO mice showed reduced contractility when compared with their WT counterparts. Signaling both from EFNBs to EPHB4 (forward signaling) and from EPHB4 to EFNB2 (reverse signaling) modulated VSMC contractility. At the molecular level, the absence of EPHB4 in VSMCs resulted in compromised signaling from Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) to myosin light chain kinase (MLCK) to myosin light chain, the last of which controls the contraction force of motor molecule myosin. Near the cell membrane, an adaptor protein GRIP1, which can associate with EFNB2, was found to be essential in mediating EPHB4-to-EFNB reverse signaling, which regulated VSMC contractility, based on siRNA gene knockdown studies. Our research indicates that EPHB4 plays an essential role in regulating small artery contractility and blood pressure.
Collapse
Affiliation(s)
- Yujia Wang
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9
| | - Eric Thorin
- the Montreal Heart Institute, Montreal, Quebec H1T 1C8
| | - Hongyu Luo
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9
| | - Johanne Tremblay
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9
| | - Julie L Lavoie
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9, the Département de Kinésiologie, Université de Montréal, Montreal, Quebec H3T 1J4, and
| | - Zenghui Wu
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9
| | - Junzheng Peng
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9
| | - Shijie Qi
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9
| | - Jiangping Wu
- From the Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec H2X 0A9, the Nephrology Service, CHUM, Montreal, Quebec H2L 4M1, Canada
| |
Collapse
|
116
|
Jain N, Lee EJ. Islet Endothelial Cells Derived From Mouse Embryonic Stem Cells. Cell Transplant 2015; 25:97-108. [PMID: 25751085 DOI: 10.3727/096368915x687732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The islet endothelium comprises a specialized population of islet endothelial cells (IECs) expressing unique markers such as nephrin and α-1 antitrypsin (AAT) that are not found in endothelial cells in surrounding tissues. However, due to difficulties in isolating and maintaining a pure population of these cells, the information on these islet-specific cells is currently very limited. Interestingly, we have identified a large subpopulation of endothelial cells exhibiting IEC phenotype, while deriving insulin-producing cells from mouse embryonic stem cells (mESCs). These cells were identified by the uptake of low-density lipoprotein (LDL) and were successfully isolated and subsequently expanded in endothelial cell culture medium. Further analysis demonstrated that the mouse embryonic stem cell-derived endothelial cells (mESC-ECs) not only express classical endothelial markers, such as platelet endothelial cell adhesion molecule (PECAM1), thrombomodulin, intercellular adhesion molecule-1 (ICAM-1), and endothelial nitric oxide synthase (eNOS) but also IEC-specific markers such as nephrin and AAT. Moreover, mESC-ECs secrete basement membrane proteins such as collagen type IV, laminin, and fibronectin in culture and form tubular networks on a layer of Matrigel, demonstrating angiogenic activity. Further, mESC-ECs not only express eNOS, but also its eNOS expression is glucose dependent, which is another characteristic phenotype of IECs. With the ability to obtain highly purified IECs derived from pluripotent stem cells, it is possible to closely examine the function of these cells and their interaction with pancreatic β-cells during development and maturation in vitro. Further characterization of tissue-specific endothelial cell properties may enhance our ability to formulate new therapeutic angiogenic approaches for diabetes.
Collapse
Affiliation(s)
- Neha Jain
- New Jersey Institute of Technology, Department of Biomedical Engineering, Newark, NJ, USA
| | | |
Collapse
|
117
|
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: 3.9] [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.
Collapse
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.
| |
Collapse
|
118
|
Kapodistria K, Tsilibary EP, Politis P, Moustardas P, Charonis A, Kitsiou P. Nephrin, a transmembrane protein, is involved in pancreatic beta-cell survival signaling. Mol Cell Endocrinol 2015; 400:112-28. [PMID: 25448064 DOI: 10.1016/j.mce.2014.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 10/15/2014] [Accepted: 11/03/2014] [Indexed: 01/15/2023]
Abstract
Nephrin, a cell surface signaling receptor, regulates podocyte function in health and disease. We study the role of nephrin in β-cell survival signaling. We report that in mouse islet β-cells and the mouse pancreatic beta-cell line (βTC-6 cells) nephrin is associated and partly co-localized with PI3-kinase. Incubation of cells with functional anti-nephrin antibodies induced nephrin clustering at the plasma membrane, nephrin phosphorylation and recruitment of PI3-kinase to nephrin thus resulting in increased PI3K-dependent Akt phosphorylation and augmented phosphorylation/inhibition of pro-apoptotic Bad and FoxO. Nephrin silencing abolished Akt activation and increased susceptibility of cells to apoptosis. High glucose impaired nephrin signaling, increased nephrin internalization and up-regulated PKCα expression. Interestingly, a marked decrease in nephrin expression and phosphorylated Akt was observed in pancreatic islets of db/db lepr-/- diabetic mice. Our findings revealed that nephrin is involved in β-cell survival and suggest that glucose-induced changes in nephrin signaling may contribute to gradual pancreatic β-cell loss in type 2 diabetes.
Collapse
Affiliation(s)
- Katerina Kapodistria
- Institute of Biosciences and Applications, National Centre for Scientific Research, N.C.S.R. "Demokritos", Terma Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Attiki, Greece
| | - Effie-Photini Tsilibary
- Institute of Biosciences and Applications, National Centre for Scientific Research, N.C.S.R. "Demokritos", Terma Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Attiki, Greece
| | - Panagiotis Politis
- Center for Basic Research, Biomedical Research Foundation Academy of Athens (BRFAA), 4 Soranou Ephessiou, Athens 115 27, Greece
| | - Petros Moustardas
- Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation Academy of Athens (BRFAA), 4 Soranou Ephessiou, Athens 115 27, Greece
| | - Aristidis Charonis
- Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation Academy of Athens (BRFAA), 4 Soranou Ephessiou, Athens 115 27, Greece
| | - Paraskevi Kitsiou
- Institute of Biosciences and Applications, National Centre for Scientific Research, N.C.S.R. "Demokritos", Terma Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Attiki, Greece.
| |
Collapse
|
119
|
Yang EY, Kronenfeld JP, Stabler CL. Engineering biomimetic materials for islet transplantation. Curr Diabetes Rev 2015; 11:163-9. [PMID: 25776871 PMCID: PMC4447569 DOI: 10.2174/1573399811666150317130440] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 12/30/2022]
Abstract
A closed-loop system that provides both the sensing of glucose and the appropriate dosage of insulin could dramatically improve treatment options for insulin-dependent diabetics. The intrahepatic implantation of allogeneic islets has the potential to provide this intimate control, by transplanting the very cells that have this inherent sensing and secretion capacity. Limiting islet transplantation, however, is the significant loss and dysfunction of islets following implantation, due to the poor engraftment environment and significant immunological attack. In this review, we outline approaches that seek to address these challenges via engineering biomimetic materials. These materials can serve to mimic natural processes that work toward improving engraftment, minimizing inflammation, and directing immunological responses. Biomimetic materials can serve to house cells, recapitulate native microenvironments, release therapeutic agents in a physiological manner, and/or present agents to direct cells towards desired responses. By integrating these approaches, superior platforms capable of improving long-term engraftment and acceptance of transplanted islets are on the horizon.
Collapse
Affiliation(s)
| | | | - Cherie L Stabler
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.
| |
Collapse
|
120
|
Benninger RKP, Hutchens T, Head WS, McCaughey MJ, Zhang M, Le Marchand SJ, Satin LS, Piston DW. Intrinsic islet heterogeneity and gap junction coupling determine spatiotemporal Ca²⁺ wave dynamics. Biophys J 2014; 107:2723-33. [PMID: 25468351 DOI: 10.1016/j.bpj.2014.10.048] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/09/2014] [Accepted: 10/08/2014] [Indexed: 10/24/2022] Open
Abstract
Insulin is released from the islets of Langerhans in discrete pulses that are linked to synchronized oscillations of intracellular free calcium ([Ca(2+)]i). Associated with each synchronized oscillation is a propagating calcium wave mediated by Connexin36 (Cx36) gap junctions. A computational islet model predicted that waves emerge due to heterogeneity in β-cell function throughout the islet. To test this, we applied defined patterns of glucose stimulation across the islet using a microfluidic device and measured how these perturbations affect calcium wave propagation. We further investigated how gap junction coupling regulates spatiotemporal [Ca(2+)]i dynamics in the face of heterogeneous glucose stimulation. Calcium waves were found to originate in regions of the islet having elevated excitability, and this heterogeneity is an intrinsic property of islet β-cells. The extent of [Ca(2+)]i elevation across the islet in the presence of heterogeneity is gap-junction dependent, which reveals a glucose dependence of gap junction coupling. To better describe these observations, we had to modify the computational islet model to consider the electrochemical gradient between neighboring β-cells. These results reveal how the spatiotemporal [Ca(2+)]i dynamics of the islet depend on β-cell heterogeneity and cell-cell coupling, and are important for understanding the regulation of coordinated insulin release across the islet.
Collapse
Affiliation(s)
- Richard K P Benninger
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee; Department of Bioengineering, University of Colorado, Aurora, Colorado; Barbara Davis Center, University of Colorado, Aurora, Colorado.
| | - Troy Hutchens
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - W Steven Head
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Michael J McCaughey
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Min Zhang
- Department of Pharmacology, Virginia Commonwealth University, Richmond, Virginia
| | - Sylvain J Le Marchand
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Leslie S Satin
- Department of Pharmacology, Virginia Commonwealth University, Richmond, Virginia; Department of Pharmacology, University of Michigan, Ann Arbor, Michigan; Brehm Diabetes Center, University of Michigan, Ann Arbor, Michigan
| | - David W Piston
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee.
| |
Collapse
|
121
|
Li W, Cavelti-Weder C, Zhang Y, Zhang Y, Clement K, Donovan S, Gonzalez G, Zhu J, Stemann M, Xu K, Hashimoto T, Yamada T, Nakanishi M, Zhang Y, Zeng S, Gifford D, Meissner A, Weir G, Zhou Q. Long-term persistence and development of induced pancreatic beta cells generated by lineage conversion of acinar cells. Nat Biotechnol 2014; 32:1223-30. [PMID: 25402613 DOI: 10.1038/nbt.3082] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 10/23/2014] [Indexed: 01/17/2023]
Abstract
Direct lineage conversion is a promising approach to generate therapeutically important cell types for disease modeling and tissue repair. However, the survival and function of lineage-reprogrammed cells in vivo over the long term has not been examined. Here, using an improved method for in vivo conversion of adult mouse pancreatic acinar cells toward beta cells, we show that induced beta cells persist for up to 13 months (the length of the experiment), form pancreatic islet-like structures and support normoglycemia in diabetic mice. Detailed molecular analyses of induced beta cells over 7 months reveal that global DNA methylation changes occur within 10 d, whereas the transcriptional network evolves over 2 months to resemble that of endogenous beta cells and remains stable thereafter. Progressive gain of beta-cell function occurs over 7 months, as measured by glucose-regulated insulin release and suppression of hyperglycemia. These studies demonstrate that lineage-reprogrammed cells persist for >1 year and undergo epigenetic, transcriptional, anatomical and functional development toward a beta-cell phenotype.
Collapse
Affiliation(s)
- Weida Li
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Claudia Cavelti-Weder
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, Massachusetts, USA
| | | | - Yinying Zhang
- 1] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Kendell Clement
- 1] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Scott Donovan
- 1] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | | | - Jiang Zhu
- 1] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [2] Center for System Biology and Center for Cancer Research, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Marianne Stemann
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, Massachusetts, USA
| | - Ke Xu
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Tatsu Hashimoto
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Takatsugu Yamada
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, Massachusetts, USA
| | - Mio Nakanishi
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Yuemei Zhang
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Samuel Zeng
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| | - David Gifford
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Alexander Meissner
- 1] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Gordon Weir
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, Massachusetts, USA
| | - Qiao Zhou
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA
| |
Collapse
|
122
|
Bakke J, Haj FG. Protein-tyrosine phosphatase 1B substrates and metabolic regulation. Semin Cell Dev Biol 2014; 37:58-65. [PMID: 25263014 DOI: 10.1016/j.semcdb.2014.09.020] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 09/15/2014] [Accepted: 09/21/2014] [Indexed: 01/19/2023]
Abstract
Metabolic homeostasis requires integration of complex signaling networks which, when deregulated, contribute to metabolic syndrome and related disorders. Protein-tyrosine phosphatase 1B (PTP1B) has emerged as a key regulator of signaling networks that are implicated in metabolic diseases such as obesity and type 2 diabetes. In this review, we examine mechanisms that regulate PTP1B-substrate interaction, enzymatic activity and experimental approaches to identify PTP1B substrates. We then highlight findings that implicate PTP1B in metabolic regulation. In particular, insulin and leptin signaling are discussed as well as recently identified PTP1B substrates that are involved in endoplasmic reticulum stress response, cell-cell communication, energy balance and vesicle trafficking. In summary, PTP1B exhibits exquisite substrate specificity and is an outstanding pharmaceutical target for obesity and type 2 diabetes.
Collapse
Affiliation(s)
- Jesse Bakke
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States
| | - Fawaz G Haj
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States; Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of California Davis, Sacramento, CA 95817, United States; Comprehensive Cancer Center, University of California Davis, Sacramento, CA 95817, United States.
| |
Collapse
|
123
|
Hraha TH, Bernard AB, Nguyen LM, Anseth KS, Benninger RKP. Dimensionality and size scaling of coordinated Ca(2+) dynamics in MIN6 β-cell clusters. Biophys J 2014; 106:299-309. [PMID: 24411262 DOI: 10.1016/j.bpj.2013.11.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 10/29/2013] [Accepted: 11/11/2013] [Indexed: 01/15/2023] Open
Abstract
Pancreatic islets of Langerhans regulate blood glucose homeostasis by the secretion of the hormone insulin. Like many neuroendocrine cells, the coupling between insulin-secreting β-cells in the islet is critical for the dynamics of hormone secretion. We have examined how this coupling architecture regulates the electrical dynamics that underlie insulin secretion by utilizing a microwell-based aggregation method to generate clusters of a β-cell line with defined sizes and dimensions. We measured the dynamics of free-calcium activity ([Ca(2+)]i) and insulin secretion and compared these measurements with a percolating network model. We observed that the coupling dimension was critical for regulating [Ca(2+)]i dynamics and insulin secretion. Three-dimensional coupling led to size-invariant suppression of [Ca(2+)]i at low glucose and robust synchronized [Ca(2+)]i oscillations at elevated glucose, whereas two-dimensional coupling showed poor suppression and less robust synchronization, with significant size-dependence. The dimension- and size-scaling of [Ca(2+)]i at high and low glucose could be accurately described with the percolating network model, using similar network connectivity. As such this could explain the fundamentally different behavior and size-scaling observed under each coupling dimension. This study highlights the dependence of proper β-cell function on the coupling architecture that will be important for developing therapeutic treatments for diabetes such as islet transplantation techniques. Furthermore, this will be vital to gain a better understanding of the general features by which cellular interactions regulate coupled multicellular systems.
Collapse
Affiliation(s)
- Thomas H Hraha
- Department of Bioengineering, University of Colorado, Anschutz Medical campus, Aurora, CO
| | - Abigail B Bernard
- Department of Biological and Chemical Engineering and the Howard Hughes Medical Institute, University of Colorado, Boulder, CO
| | - Linda M Nguyen
- Department of Bioengineering, University of Colorado, Anschutz Medical campus, Aurora, CO
| | - Kristi S Anseth
- Department of Biological and Chemical Engineering and the Howard Hughes Medical Institute, University of Colorado, Boulder, CO
| | - Richard K P Benninger
- Department of Bioengineering, University of Colorado, Anschutz Medical campus, Aurora, CO; Barbara Davis Center for Childhood Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO.
| |
Collapse
|
124
|
Liu S, Xi Y, Bettaieb A, Matsuo K, Matsuo I, Kulkarni RN, Haj FG. Disruption of protein-tyrosine phosphatase 1B expression in the pancreas affects β-cell function. Endocrinology 2014; 155:3329-38. [PMID: 24956127 PMCID: PMC4138572 DOI: 10.1210/en.2013-2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Protein-tyrosine phosphatase 1B (PTP1B) is a physiological regulator of glucose homeostasis and energy balance. However, the role of PTP1B in pancreatic endocrine function remains largely unknown. To investigate the metabolic role of pancreatic PTP1B, we generated mice with pancreas PTP1B deletion (panc-PTP1B KO). Mice were fed regular chow or a high-fat diet, and metabolic parameters, insulin secretion and glucose tolerance were determined. On regular chow, panc-PTP1B KO and control mice exhibited comparable glucose tolerance whereas aged panc-PTP1B KO exhibited mild glucose intolerance. Furthermore, high-fat feeding promoted earlier impairment of glucose tolerance and attenuated glucose-stimulated insulin secretion in panc-PTP1B KO mice. The secretory defect in glucose-stimulated insulin secretion was recapitulated in primary islets ex vivo, suggesting that the effects were likely cell-autonomous. At the molecular level, PTP1B deficiency in vivo enhanced basal and glucose-stimulated tyrosyl phosphorylation of EphA5 in islets. Consistently, PTP1B overexpression in the glucose-responsive MIN6 β-cell line attenuated EphA5 tyrosyl phosphorylation, and substrate trapping identified EphA5 as a PTP1B substrate. In summary, these studies identify a novel role for PTP1B in pancreatic endocrine function.
Collapse
Affiliation(s)
- Siming Liu
- Nutrition Department (S.L., Y.X., A.B., K.M., I.M., F.G.H.), University of California Davis, Davis, California 95616; Joslin Diabetes Center (R.N.K.), Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215; and Division of Endocrinology, Diabetes and Metabolism (F.G.H.), Department of Internal Medicine, and Comprehensive Cancer Center, University of California Davis, Sacramento, California 95817
| | | | | | | | | | | | | |
Collapse
|
125
|
Hassan-Mohamed I, Giorgio C, Incerti M, Russo S, Pala D, Pasquale EB, Zanotti I, Vicini P, Barocelli E, Rivara S, Mor M, Lodola A, Tognolini M. UniPR129 is a competitive small molecule Eph-ephrin antagonist blocking in vitro angiogenesis at low micromolar concentrations. Br J Pharmacol 2014; 171:5195-208. [PMID: 24597515 DOI: 10.1111/bph.12669] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 01/21/2014] [Accepted: 01/31/2014] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE The Eph receptor tyrosine kinases and their ephrin ligands are key players in tumorigenesis and many reports have correlated changes in their expression with a poor clinical prognosis in many solid tumours. Agents targeting the Eph-ephrin system might emerge as new tools useful for the inhibition of different components of cancer progression. Even if different classes of small molecules targeting Eph-ephrin interactions have been reported, their use is hampered by poor chemical stability and low potency. Stable and potent ligands are crucial to achieve robust pharmacological performance. EXPERIMENTAL APPROACH UniPR129 (the L-homo-Trp conjugate of lithocholic acid) was designed by means of computational methods, synthetized and tested for its ability to inhibit the interaction between the EphA2 receptor and the ephrin-A1 ligand in an elisa binding study. The ability of UniPR129 to disrupt EphA2-ephrin-A1 interaction was functionally evaluated in a prostate adenocarcinoma cell line and its anti-angiogenic effect was tested in vitro using cultures of HUVECs. KEY RESULTS UniPR129 disrupted EphA2-ephrin-A1 interaction with Ki = 370 nM in an elisa binding assay and with low micromolar potency in cellular functional assays, including inhibition of EphA2 activation, inhibition of PC3 cell rounding and disruption of in vitro angiogenesis, without cytotoxic effects. CONCLUSIONS AND IMPLICATIONS The discovery of UniPR129 represents not only a major advance in potency compared with the existing Eph-ephrin antagonists but also an improvement in terms of cytotoxicity, making this molecule a useful pharmacological tool and a promising lead compound.
Collapse
Affiliation(s)
- I Hassan-Mohamed
- Dipartimento di Farmacia, Università degli Studi di Parma, Parma, Italy
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
126
|
Allonby O, El Zawily AM, Freywald T, Mousseau DD, Chlan J, Anderson D, Benmerah A, Sidhu V, Babu M, DeCoteau J, Freywald A. Ligand stimulation induces clathrin- and Rab5-dependent downregulation of the kinase-dead EphB6 receptor preceded by the disruption of EphB6-Hsp90 interaction. Cell Signal 2014; 26:2645-57. [PMID: 25152371 DOI: 10.1016/j.cellsig.2014.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/25/2014] [Accepted: 08/15/2014] [Indexed: 12/13/2022]
Abstract
Ligand-induced internalisation and subsequent downregulation of receptor tyrosine kinases (RTKs) serve to determine biological outputs of their signalling. Intrinsically kinase-deficient RTKs control a variety of biological responses, however, the mechanism of their downregulation is not well understood and its analysis is focused exclusively on the ErbB3 receptor. The Eph group of RTKs is represented by the EphA and EphB subclasses. Each bears one kinase-inactive member, EphA10 and EphB6, respectively, suggesting an important role for these molecules in the Eph signalling network. While EphB6 effects on cell behaviour have been assessed, the mechanism of its downregulation remains elusive. Our work reveals that EphB6 and its kinase-active relative, and signalling partner, EphB4, are downregulated in a similar manner in response to their common ligand, ephrin-B2. Following stimulation, both receptors are internalised through clathrin-coated pits and are degraded in lysosomes. Their targeting for lysosomal degradation relies on the activity of an early endosome regulator, the Rab5 GTPase, as this process is inhibited in the presence of a Rab5 dominant-negative mutant. EphB6 also interacts with the Hsp90 chaperone and EphB6 downregulation is preceded by their rapid dissociation. Moreover, the inhibition of Hsp90 results in EphB6 degradation, mimicking its ligand-induced downregulation. These processes appear to rely on overlapping mechanisms, since Hsp90 inhibition does not significantly enhance ligand-induced EphB6 elimination. Taken together, our observations define a novel mechanism for intrinsically kinase-deficient RTK downregulation and support an intriguing model, where Hsp90 dissociation acts as a trigger for ligand-induced receptor removal.
Collapse
Affiliation(s)
- Odette Allonby
- Department of Pathology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Amr M El Zawily
- Department of Pathology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Tanya Freywald
- Department of Pathology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Darrell D Mousseau
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Jennifer Chlan
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Deborah Anderson
- Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; Cancer Research Unit, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Alexandre Benmerah
- INSERM U1163, Laboratory of Inherited Kidney Diseases, 75015 Paris, France; Université Paris Descartes - Sorbonne Paris Cité, Institut Imagine, 75015 Paris, France.
| | - Vishaldeep Sidhu
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, SK,S4S 0A2, Canada.
| | - Mohan Babu
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, SK,S4S 0A2, Canada.
| | - John DeCoteau
- Department of Pathology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Andrew Freywald
- Department of Pathology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada; Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| |
Collapse
|
127
|
Jonatan D, Spence JR, Method AM, Kofron M, Sinagoga K, Haataja L, Arvan P, Deutsch GH, Wells JM. Sox17 regulates insulin secretion in the normal and pathologic mouse β cell. PLoS One 2014; 9:e104675. [PMID: 25144761 PMCID: PMC4140688 DOI: 10.1371/journal.pone.0104675] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 07/16/2014] [Indexed: 02/06/2023] Open
Abstract
SOX17 is a key transcriptional regulator that can act by regulating other transcription factors including HNF1β and FOXA2, which are known to regulate postnatal β cell function. Given this, we investigated the role of SOX17 in the developing and postnatal pancreas and found a novel role for SOX17 in regulating insulin secretion. Deletion of the Sox17 gene in the pancreas (Sox17-paLOF) had no observable impact on pancreas development. However, Sox17-paLOF mice had higher islet proinsulin protein content, abnormal trafficking of proinsulin, and dilated secretory organelles suggesting that Sox17-paLOF adult mice are prediabetic. Consistant with this, Sox17-paLOF mice were more susceptible to aged-related and high fat diet-induced hyperglycemia and diabetes. Overexpression of Sox17 in mature β cells using Ins2-rtTA driver mice resulted in precocious secretion of proinsulin. Transcriptionally, SOX17 appears to broadly regulate secretory networks since a 24-hour pulse of SOX17 expression resulted in global transcriptional changes in factors that regulate hormone transport and secretion. Lastly, transient SOX17 overexpression was able to reverse the insulin secretory defects observed in MODY4 animals and restored euglycemia. Together, these data demonstrate a critical new role for SOX17 in regulating insulin trafficking and secretion and that modulation of Sox17-regulated pathways might be used therapeutically to improve cell function in the context of diabetes.
Collapse
Affiliation(s)
- Diva Jonatan
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States of America
| | - Jason R. Spence
- Department of Internal Medicine, Division of Gastroenterology, University of Michigan Medical School, Ann Arbor, MI, United States of America
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, United States of America
- Center for Organogenesis, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Anna M. Method
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States of America
| | - Matthew Kofron
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States of America
| | - Katie Sinagoga
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States of America
| | - Leena Haataja
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Peter Arvan
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Gail H. Deutsch
- Seattle Children’s Hospital, Seattle, WA, United States of America
| | - James M. Wells
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States of America
- Division of Endocrinology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States of America
- * E-mail:
| |
Collapse
|
128
|
Improvement of beta cell function in intraportal transplantation of islet cell cluster using secretion signal peptide-linked exendin-4 gene. Macromol Res 2014. [DOI: 10.1007/s13233-014-2120-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
129
|
Benninger RKP, Piston DW. Cellular communication and heterogeneity in pancreatic islet insulin secretion dynamics. Trends Endocrinol Metab 2014; 25:399-406. [PMID: 24679927 PMCID: PMC4112137 DOI: 10.1016/j.tem.2014.02.005] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 11/20/2022]
Abstract
Coordinated pulses of electrical activity and insulin secretion are a hallmark of the islet of Langerhans. These coordinated behaviors are lost when β cells are dissociated, which also leads to increased insulin secretion at low glucose levels. Islets without gap junctions exhibit asynchronous electrical activity similar to dispersed cells, but their secretion at low glucose levels is still clamped off, putatively by a juxtacrine mechanism. Mice lacking β cell gap junctions have near-normal average insulin levels, but are glucose intolerant due to reduced first-phase and pulsatile insulin secretion, illustrating the importance of temporal dynamics. Here, we review the quantitative data on islet synchronization and the current mathematical models that have been developed to explain these behaviors and generate greater understanding of the underlying mechanisms.
Collapse
Affiliation(s)
- Richard K P Benninger
- Department of Bioengineering and Barbara Davis Center, University of Colorado Anschutz Medical campus, Aurora, CO, USA.
| | - David W Piston
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN, USA.
| |
Collapse
|
130
|
Avolio F, Pfeifer A, Courtney M, Gjernes E, Ben-Othman N, Vieira A, Druelle N, Faurite B, Collombat P. From pancreas morphogenesis to β-cell regeneration. Curr Top Dev Biol 2014; 106:217-38. [PMID: 24290351 DOI: 10.1016/b978-0-12-416021-7.00006-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Type 1 diabetes is a metabolic disease resulting in the selective loss of pancreatic insulin-producing β-cells and affecting millions of people worldwide. The side effects of diabetes are varied and include cardiovascular, neuropathologic, and kidney diseases. Despite the most recent advances in diabetes care, patients suffering from type 1 diabetes still display a shortened life expectancy compared to their healthy counterparts. In an effort to improve β-cell-replacement therapies, numerous approaches are currently being pursued, most of these aiming at finding ways to differentiate stem/progenitor cells into β-like cells by mimicking embryonic development. Unfortunately, these efforts have hitherto not allowed the generation of fully functional β-cells. This chapter summarizes recent findings, allowing a better insight into the molecular mechanisms underlying the genesis of β-cells during the course of pancreatic morphogenesis. Furthermore, a focus is made on new research avenues concerning the conversion of pre-existing pancreatic cells into β-like cells, such approaches holding great promise for the development of type 1 diabetes therapies.
Collapse
Affiliation(s)
- Fabio Avolio
- Univ. Nice Sophia Antipolis, iBV, UMR 7277, Nice, France; Inserm, iBV, U1091, Nice, France; CNRS, iBV, UMR 7277, Nice, France
| | | | | | | | | | | | | | | | | |
Collapse
|
131
|
Iwasaki M, Minami K, Shibasaki T, Miki T, Miyazaki JI, Seino S. Establishment of new clonal pancreatic β-cell lines (MIN6-K) useful for study of incretin/cyclic adenosine monophosphate signaling. J Diabetes Investig 2014; 1:137-42. [PMID: 24843422 PMCID: PMC4008005 DOI: 10.1111/j.2040-1124.2010.00026.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Incretin/cyclic adenosine monophosphate (cAMP) signaling is critical for potentiation of insulin secretion. Although several cell lines of pancreatic β‐cells are currently available, there are no cell lines suitable for investigation of incretin/cAMP signaling. In the present study, we have newly established pancreatic β‐cell lines (named MIN6‐K) from the IT6 mouse, which develops insulinoma. MIN6‐K8 cells respond to both glucose and incretins, such as glucagon‐like peptide‐1 (GLP‐1) and glucose‐dependent insulinotropic polypeptide (GIP), as is the case in pancreatic islets, whereas MIN6‐K20 cells respond to glucose, but not to incretins. Despite the difference in incretin‐potentiated insulin secretion between these two cell lines, the accumulation of cAMP after stimulation of GLP‐1 is comparable in these cells. Interestingly, we also found that incretin responsiveness is drastically induced by the formation of pseudoislets from MIN6‐K20 cells to a level comparable to that of pancreatic islets. Thus, these cell lines are useful for studying incretin/cAMP signaling in β‐cells. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00026.x, 2010)
Collapse
Affiliation(s)
- Masahiro Iwasaki
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe
| | - Kohtaro Minami
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe
| | - Tadao Shibasaki
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe
| | - Takashi Miki
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe ; Department of Autonomic Physiology, Graduate School of Medicine, Chiba University, Chiba
| | - Jun-Ichi Miyazaki
- Department of Nutrition and Physiological Chemistry, Osaka University Graduate School of Medicine, Osaka
| | - Susumu Seino
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe ; Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe ; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, Saitama, Japan
| |
Collapse
|
132
|
Nguyen LM, Pozzoli M, Hraha TH, Benninger RK. Decreasing cx36 gap junction coupling compensates for overactive KATP channels to restore insulin secretion and prevent hyperglycemia in a mouse model of neonatal diabetes. Diabetes 2014; 63:1685-97. [PMID: 24458355 PMCID: PMC3994954 DOI: 10.2337/db13-1048] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 01/08/2014] [Indexed: 11/13/2022]
Abstract
Mutations to the ATP-sensitive K(+) channel (KATP channel) that reduce the sensitivity of ATP inhibition cause neonatal diabetes mellitus via suppression of β-cell glucose-stimulated free calcium activity ([Ca(2+)]i) and insulin secretion. Connexin-36 (Cx36) gap junctions also regulate islet electrical activity; upon knockout of Cx36, β-cells show [Ca(2+)]i elevations at basal glucose. We hypothesized that in the presence of overactive ATP-insensitive KATP channels, a reduction in Cx36 would allow elevations in glucose-stimulated [Ca(2+)]i and insulin secretion to improve glucose homeostasis. To test this, we introduced a genetic knockout of Cx36 into mice that express ATP-insensitive KATP channels and measured glucose homeostasis and islet metabolic, electrical, and insulin secretion responses. In the normal presence of Cx36, after expression of ATP-insensitive KATP channels, blood glucose levels rapidly rose to >500 mg/dL. Islets from these mice showed reduced glucose-stimulated [Ca(2+)]i and no insulin secretion. In mice lacking Cx36 after expression of ATP-insensitive KATP channels, normal glucose levels were maintained. Islets from these mice had near-normal glucose-stimulated [Ca(2+)]i and insulin secretion. We therefore demonstrate a novel mechanism by which islet function can be recovered in a monogenic model of diabetes. A reduction of gap junction coupling allows sufficient glucose-stimulated [Ca(2+)]i and insulin secretion to prevent the emergence of diabetes.
Collapse
Affiliation(s)
- Linda M. Nguyen
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Marina Pozzoli
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Thomas H. Hraha
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
| | - Richard K.P. Benninger
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO
- Barbara Davis Center for Childhood Diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO
| |
Collapse
|
133
|
Szepietowska B, Horvath TL, Sherwin RS. Role of synaptic plasticity and EphA5-ephrinA5 interaction within the ventromedial hypothalamus in response to recurrent hypoglycemia. Diabetes 2014; 63:1140-7. [PMID: 24222347 PMCID: PMC3931406 DOI: 10.2337/db13-1259] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hypoglycemia stimulates counterregulatory hormone release to restore euglycemia. This protective response is diminished by recurrent hypoglycemia, limiting the benefits of intensive insulin treatment in patients with diabetes. We previously reported that EphA5 receptor-ephrinA5 interactions within the ventromedial hypothalamus (VMH) influence counterregulatory hormone responses during acute hypoglycemia in nondiabetic rats. In this study, we examined whether recurrent hypoglycemia alters the capacity of the ephrinA5 ligand to activate VMH EphA5 receptors, and if so, whether these changes could contribute to pathogenesis of defective glucose counterregulation in response to a standard hypoglycemic stimulus. The expression of ephrinA5, but not EphA5 receptors within the VMH, was reduced by antecedent recurrent hypoglycemia. In addition, the number of synaptic connections was increased and astroglial synaptic coverage was reduced. Activation of VMH EphA5 receptors via targeted microinjection of ephrinA5-Fc before a hyperinsulinemic hypoglycemic clamp study caused a reduction in the glucose infusion rate in nondiabetic rats exposed to recurrent hypoglycemia. The increase in the counterregulatory response to insulin-induced hypoglycemia was associated with a 150% increase in glucagon release (P < 0.001). These data suggest that changes in ephrinA5/EphA5 interactions and synaptic plasticity within the VMH, a key glucose-sensing region in the brain, may contribute to the impairment in glucagon secretion and counterregulatory responses caused by recurrent hypoglycemia.
Collapse
Affiliation(s)
- Barbara Szepietowska
- Yale University School of Medicine, Department of Internal Medicine and Endocrinology, New Haven, CT
| | - Tamas L. Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT
| | - Robert S. Sherwin
- Yale University School of Medicine, Department of Internal Medicine and Endocrinology, New Haven, CT
- Corresponding author: Robert S. Sherwin,
| |
Collapse
|
134
|
Farnsworth NL, Benninger RKP. New insights into the role of connexins in pancreatic islet function and diabetes. FEBS Lett 2014; 588:1278-87. [PMID: 24583073 DOI: 10.1016/j.febslet.2014.02.035] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/13/2014] [Accepted: 02/19/2014] [Indexed: 12/22/2022]
Abstract
Multi-cellular systems require complex signaling mechanisms for proper tissue function, to mediate signaling between cells in close proximity and at distances. This holds true for the islets of Langerhans, which are multicellular micro-organs located in the pancreas responsible for glycemic control, through secretion of insulin and other hormones. Coupling of electrical and metabolic signaling between islet β-cells is required for proper insulin secretion and effective glycemic control. β-cell specific coupling is established through gap junctions composed of connexin36, which results in coordinated insulin release across the islet. Islet connexins have been implicated in both Type-1 and Type-2 diabetes; however a clear link remains to be determined. The goal of this review is to discuss recent discoveries regarding the role of connexins in regulating insulin secretion, the regulation of connexins within the islet, and recent studies which support a role for connexins in diabetes. Further studies which investigate the regulation of connexins in the islet and their role in diabetes may lead to novel diabetes therapies which regulate islet function and β-cell survival through modulation of gap junction coupling.
Collapse
Affiliation(s)
- Nikki L Farnsworth
- Barbara Davis center for childhood diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Richard K P Benninger
- Barbara Davis center for childhood diabetes, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, United States; Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, United States.
| |
Collapse
|
135
|
Subcellular glucose exposure biases the spatial distribution of insulin granules in single pancreatic beta cells. Sci Rep 2014; 4:4123. [PMID: 24535122 PMCID: PMC3927211 DOI: 10.1038/srep04123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 02/03/2014] [Indexed: 01/08/2023] Open
Abstract
In living tissues, a cell is exposed to chemical substances delivered partially to its surface. Such a heterogeneous chemical environment potentially induces cell polarity. To evaluate this effect, we developed a microfluidic device that realizes spatially confined delivery of chemical substances at subcellular resolution. Our microfluidic device allows simple setup and stable operation for over 4 h to deliver chemicals partially to a single cell. Using the device, we showed that subcellular glucose exposure triggers an intracellular [Ca(2+)] change in the β-cells. In addition, the imaging of a cell expressing GFP-tagged insulin showed that continuous subcellular exposure to glucose biased the spatial distribution of insulin granules toward the site where the glucose was delivered. Our approach illustrates an experimental technique that will be applicable to many biological experiments for imaging the response to subcellular chemical exposure and will also provide new insights about the development of polarity of β-cells.
Collapse
|
136
|
Bernard AB, Chapman RZ, Anseth KS. Controlled local presentation of matrix proteins in microparticle-laden cell aggregates. Biotechnol Bioeng 2013; 111:1028-37. [PMID: 24255014 DOI: 10.1002/bit.25153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 11/08/2013] [Accepted: 11/14/2013] [Indexed: 01/17/2023]
Abstract
Multi-cellular aggregates are found in healthy and diseased tissues, and while cell-cell contact is important for regulating many cell functions, cells also interact, to varying degrees, with extra-cellular matrix (ECM) proteins. Islets of Langerhans are one such example of cell aggregates in contact with ECM, both at the periphery of the cluster and dispersed throughout. While several studies have investigated the effect of reintroducing contact with ECM proteins on islet cell survival and function, the majority of these experiments only allow contact with the exterior cells. Thus, cell-culture platforms that enable the study of ECM-cell interactions throughout multi-cellular aggregates are of interest. Here, local presentation of ECM proteins was achieved using hydrogel microwell arrays to incorporate protein-laden microparticles during formation of MIN6 β-cell aggregates. Varying the microparticle seeding density reproducibly controlled the number of microparticles incorporated within three-dimensional aggregates (i.e., total amount of protein). Further, a relatively uniform spatial distribution of laminin- and fibronectin-coated microparticles was achieved throughout the x-, y-, and z-directions. Multiple ECM proteins were presented to β-cells in concert by incorporating two distinct populations of microparticles throughout the aggregates. Finally, scaling the microwell device dimensions allowed for the formation of two different sized cell-particle aggregates, ∼80 and 160 µm in diameter. While the total number of microparticles incorporated per aggregate varied with size, the fraction of the aggregate occupied by microparticles was affected only by the microparticle seeding density, indicating that uniform local concentrations of proteins can be preserved while changing the overall aggregate dimensions.
Collapse
Affiliation(s)
- Abigail B Bernard
- Department of Chemical and Biological Engineering, University of Colorado, 3415 Colorado Avenue, Boulder, Colorado, 80303
| | | | | |
Collapse
|
137
|
Yamada T, Yuasa M, Masaoka T, Taniyama T, Maehara H, Torigoe I, Yoshii T, Shinomiya K, Okawa A, Sotome S. After repeated division, bone marrow stromal cells express inhibitory factors with osteogenic capabilities, and EphA5 is a primary candidate. Bone 2013; 57:343-54. [PMID: 24029132 DOI: 10.1016/j.bone.2013.08.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 08/23/2013] [Accepted: 08/29/2013] [Indexed: 01/01/2023]
Abstract
The differentiation capability of human bone marrow stromal cells (hBMSCs) is thought to deteriorate over multiple doubling processes. To clarify the deterioration mechanisms, the multilineage differentiation capabilities of short- and long-term passaged BMSCs were compared. Predictably, long-term passaged BMSCs showed reduced differentiation capacities compared to short-term passaged cells. Furthermore, a non-human primate heterotopic bone formation model demonstrated that long-term passaged BMSCs have bone formation capabilities but also exert inhibitory effects on bone formation. This finding indicated that long-term passaged BMSCs express higher levels of inhibitory factors than short-term passaged BMSCs do. Co-culture assays of short- and long-term passaged BMSCs suggested that the inhibitory signals required cell-cell contact and would therefore be expressed on the cell membrane. A microarray analysis of BMSCs identified ephrin type-A receptor 5 (EphA5) as an inhibitory factor candidate. Quantitative PCR revealed that among all members of the ephrin and Eph receptor families, only the expression of EphA5 was increased by BMSC proliferation. A gene knockdown analysis using siRNAs demonstrated that knockdown of EphA5 gene expression in long-term passaged BMSCs led to an increase in ALP mRNA expression. These results indicate that EphA5 may be a negative regulator of bone formation. A better understanding of the roles of the ephrin and Eph receptor families in hBMSCs may lead to alternative approaches for manipulating hBMSC fate. In addition, this avenue of discovery may provide new therapeutic targets and quality-control markers of the osteogenic differentiation capabilities of hBMSCs.
Collapse
Affiliation(s)
- Tsuyoshi Yamada
- Department of Orthopaedic and Spinal Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan; Global Center of Excellence (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
138
|
Therapeutic perspectives of Eph-ephrin system modulation. Drug Discov Today 2013; 19:661-9. [PMID: 24291785 DOI: 10.1016/j.drudis.2013.11.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/23/2013] [Accepted: 11/20/2013] [Indexed: 12/24/2022]
Abstract
Eph receptors are the largest class of kinase receptors and, together with their ligands ephrins, they have a primary role in embryogenesis. Their expression has been found deregulated in several cancer tissues and, in many cases, abnormal levels of these proteins have been correlated to a poor prognosis. Recently, the Eph-ephrin system was found to be deregulated in other pathological processes, involving the nervous and cardiovascular systems. The increasing body of evidence supports the Eph-ephrin system as a target not only for the treatment of solid tumors, but also to face other critical diseases such as amyotrophic lateral sclerosis and diabetes driving current efforts toward the development of pharmacological tools potentially able to treat these pathologies.
Collapse
|
139
|
Effect of reduced EPHB4 expression in thymic epithelial cells on thymocyte development and peripheral T cell function. Mol Immunol 2013; 58:1-9. [PMID: 24246266 DOI: 10.1016/j.molimm.2013.10.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/11/2013] [Accepted: 10/15/2013] [Indexed: 11/24/2022]
Abstract
The Eph kinase (EPH) and ephrin (EFN) families are involved in a broad range of developmental processes. Increasing evidence is demonstrating the important roles of EPHBs and EphrinBs in the immune system. In this study on epithelial cell-specific Ephb4 knockout (KO) mice, we investigated T-cell development and function after EPHB4 deletion. KO mice presented normal thymic weight and cellularity. Their thymocyte subpopulation percentages were in the normal range. KO mice had normal T-cell numbers and percentages in the spleen, and T cells were activated and proliferated normally upon TCR ligation. Furthermore, naïve spleen CD4 cells from KO and wild type mice were capable of differentiating, in a comparable manner, into Th1, Th17 and Treg cells. In vivo, KO mice mounted effective delayed type hypersensitivity responses, indicating that thymocytes develop normally in the absence of TEC EPHB4, and T cells derived from EPHB4-deleted thymic epithelian cells (TEC) have normal function. Our data suggest that heavy redundancy and promiscuous interaction between EPHs and EFNs compensate for the missing EPHB4 in TECs, and TEC EPHB4's role in T cell development might only be revealed if multiple EPHs are ablated simultaneously. We cannot exclude the possibility that (1) some immunological parameters not examined in this study are affected by the deletion; (2) the deletion is not complete due to the leaky Cre-LoxP system, and the remaining EPHB4 in TEC is sufficient for thymocyte development; or (3) EPHB4 expression in TEC is not required for T cell development and function.
Collapse
|
140
|
Nagano K, Kanasaki SI, Yamashita T, Maeda Y, Inoue M, Higashisaka K, Yoshioka Y, Abe Y, Mukai Y, Kamada H, Tsutsumi Y, Tsunoda SI. Expression of Eph receptor A10 is correlated with lymph node metastasis and stage progression in breast cancer patients. Cancer Med 2013; 2:972-7. [PMID: 24403271 PMCID: PMC3892402 DOI: 10.1002/cam4.156] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/30/2013] [Accepted: 10/04/2013] [Indexed: 01/08/2023] Open
Abstract
Eph receptor A10 (EphA10) is a valuable breast cancer marker that is highly expressed in breast cancer tissues by comparison with normal breast tissues, as we previously reported. However, the role of EphA10 expression in breast cancer is not well understood. Here, we have analyzed the expression of EphA10 at the mRNA- and protein-level in clinical breast cancer tissues and then evaluated the relationship with clinicopathological parameters for each sample. EphA10 mRNA expression was quantified by real-time polymerase chain reaction using complimentary DNA (cDNA) samples derived from breast cancer patients. Lymph node (LN) metastasis and stage progression were significantly correlated with EphA10 expression at the mRNA level (P = 0.0091 and P = 0.034, respectively). Furthermore, immunohistochemistry (IHC) staining of breast cancer tissue microarrays (TMAs) revealed that EphA10 expression at the protein level was also associated with LN metastasis and stage progression (P = 0.016 and P = 0.011, respectively). These results indicate that EphA10 expression might play a role in tumor progression and metastasis. Our findings will help elucidate the role of EphA10 in clinical breast cancer progression.
Collapse
Affiliation(s)
- Kazuya Nagano
- Laboratory of Biopharmaceutical Research, National Institute of Biomedical Innovation, 7-6-8 Saito-Asagi, Ibaraki, Osaka, 567-0085, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
141
|
Planas-Paz L, Lammert E. Mechanical forces in lymphatic vascular development and disease. Cell Mol Life Sci 2013; 70:4341-54. [PMID: 23665871 PMCID: PMC11113353 DOI: 10.1007/s00018-013-1358-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 04/26/2013] [Accepted: 04/29/2013] [Indexed: 12/11/2022]
Abstract
The lymphatic vasculature is essential for fluid homeostasis and transport of immune cells, inflammatory molecules, and dietary lipids. It is composed of a hierarchical network of blind-ended lymphatic capillaries and collecting lymphatic vessels, both lined by lymphatic endothelial cells (LECs). The low hydrostatic pressure in lymphatic capillaries, their loose intercellular junctions, and attachment to the surrounding extracellular matrix (ECM) permit passage of extravasated blood plasma from the interstitium into the lumen of the lymphatic capillaries. It is generally thought that interstitial fluid accumulation leads to a swelling of the ECM, to which the LECs of lymphatic capillaries adhere, for example via anchoring filaments. As a result, LECs are pulled away from the vascular lumen, the junctions open, and fluid enters the lymphatic vasculature. The collecting lymphatic vessels then gather the plasma fluid from the capillaries and carry it through the lymph nodes to the blood circulation. The collecting vessels contain intraluminal bicuspid valves that prevent fluid backflow, and are embraced by smooth muscle cells that contribute to fluid transport. Although the lymphatic vessels are regular subject to mechanical strain, our knowledge of its influence on lymphatic development and pathologies is scarce. Here, we discuss the mechanical forces and molecular mechanisms regulating lymphatic vascular growth and maturation in the developing mouse embryo. We also consider how the lymphatic vasculature might be affected by similar mechanomechanisms in two pathological processes, namely cancer cell dissemination and secondary lymphedema.
Collapse
Affiliation(s)
- Lara Planas-Paz
- Institute of Metabolic Physiology, Heinrich-Heine University, Universitätsstrasse 1, 40225, Düsseldorf, Germany,
| | | |
Collapse
|
142
|
Microbead-based biomimetic synthetic neighbors enhance survival and function of rat pancreatic β-cells. Sci Rep 2013; 3:2863. [PMID: 24091640 PMCID: PMC3790197 DOI: 10.1038/srep02863] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 09/12/2013] [Indexed: 12/24/2022] Open
Abstract
Diabetes is caused by the loss or dysfunction of insulin-secreting β-cells in the pancreas. β-cells reduce their mass and lose insulin-producing ability in vitro, likely due to insufficient cell-cell and cell-extracellular matrix (ECM) interactions as β-cells lose their native microenvironment. Herein, we built an ex-vivo cell microenvironment by culturing primary β-cells in direct contact with ‘synthetic neighbors', cell-sized soft polymer microbeads that were modified with cell-cell signaling factors as well as components from pancreatic-tissue-specific ECMs. This biomimetic 3D microenvironment was able to promote native cell-cell and cell-ECM interactions. We obtained sustained maintenance of β-cell function in vitro enhanced cell viability from the few days usually observed in 2D culture to periods exceeding three weeks, with enhanced β-cell stability and insulin production. Our approach can be extended to create a general 3D culture platform for other cell types.
Collapse
|
143
|
A novel role for adipose ephrin-B1 in inflammatory response. PLoS One 2013; 8:e76199. [PMID: 24098442 PMCID: PMC3787942 DOI: 10.1371/journal.pone.0076199] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 08/20/2013] [Indexed: 11/19/2022] Open
Abstract
Aims Ephrin-B1 (EfnB1) was selected among genes of unknown function in adipocytes or adipose tissue and subjected to thorough analysis to understand its role in the development of obesity. Methods and Results EfnB1 mRNA and protein levels were significantly decreased in adipose tissues of obese mice and such reduction was mainly observed in mature adipocytes. Exposure of 3T3-L1 adipocytes to tumor necrosis factor-α (TNF-α) and their culture with RAW264.7 cells reduced EFNB1 levels. Knockdown of adipose EFNB1 increased monocyte chemoattractant protein-1 (Mcp-1) mRNA level and augmented the TNF-α-mediated THP-1 monocyte adhesion to adipocytes. Adenovirus-mediated adipose EFNB1-overexpression significantly reduced the increase in Mcp-1 mRNA level induced by coculture of 3T3-L1 adipocytes with RAW264.7 cells. Monocyte adherent assay showed that adipose EfnB1-overexpression significantly decreased the increase of monocyte adhesion by coculture with RAW264.7 cells. TNF-α-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) was reduced by EFNB1-overexpression. Conclusions EFNB1 contributes to the suppression of adipose inflammatory response. In obesity, reduction of adipose EFNB1 may accelerate the vicious cycle involved in adipose tissue inflammation.
Collapse
|
144
|
Huan X, Shi J, Lim L, Mitra S, Zhu W, Qin H, Pasquale EB, Song J. Unique structure and dynamics of the EphA5 ligand binding domain mediate its binding specificity as revealed by X-ray crystallography, NMR and MD simulations. PLoS One 2013; 8:e74040. [PMID: 24086308 PMCID: PMC3782497 DOI: 10.1371/journal.pone.0074040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/25/2013] [Indexed: 12/26/2022] Open
Abstract
The 16 EphA and EphB receptors represent the largest family of receptor tyrosine kinases, and their interactions with 9 ephrin-A and ephrin-B ligands initiate bidirectional signals controlling many physiological and pathological processes. Most interactions occur between receptor and ephrins of the same class, and only EphA4 can bind all A and B ephrins. To understand the structural and dynamic principles that enable Eph receptors to utilize the same jellyroll β-sandwich fold to bind ephrins, the VAPB-MSP domain, peptides and small molecules, we have used crystallography, NMR and molecular dynamics (MD) simulations to determine the first structure and dynamics of the EphA5 ligand-binding domain (LBD), which only binds ephrin-A ligands. Unexpectedly, despite being unbound, the high affinity ephrin-binding pocket of EphA5 resembles that of other Eph receptors bound to ephrins, with a helical conformation over the J–K loop and an open pocket. The openness of the pocket is further supported by NMR hydrogen/deuterium exchange data and MD simulations. Additionally, the EphA5 LBD undergoes significant picosecond-nanosecond conformational exchanges over the loops, as revealed by NMR and MD simulations, but lacks global conformational exchanges on the microsecond-millisecond time scale. This is markedly different from the EphA4 LBD, which shares 74% sequence identity and 87% homology. Consequently, the unbound EphA5 LBD appears to comprise an ensemble of open conformations that have only small variations over the loops and appear ready to bind ephrin-A ligands. These findings show how two proteins with high sequence homology and structural similarity are still able to achieve distinctive binding specificities through different dynamics, which may represent a general mechanism whereby the same protein fold can serve for different functions. Our findings also suggest that a promising strategy to design agonists/antagonists with high affinity and selectivity might be to target specific dynamic states of the Eph receptor LBDs.
Collapse
Affiliation(s)
- Xuelu Huan
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Republic of Singapore
| | - Jiahai Shi
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Republic of Singapore
| | - Liangzhong Lim
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Republic of Singapore
| | - Sayantan Mitra
- Sanford-Burnham Medical Research Institute, La Jolla, California, United States of America
| | - Wanlong Zhu
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Republic of Singapore
| | - Haina Qin
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Republic of Singapore
| | - Elena B. Pasquale
- Sanford-Burnham Medical Research Institute, La Jolla, California, United States of America
- Pathology Department, University of California San Diego, La Jolla, California, United States of America
| | - Jianxing Song
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Republic of Singapore
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Republic of Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
- * E-mail:
| |
Collapse
|
145
|
Kharkar PM, Kiick KL, Kloxin AM. Designing degradable hydrogels for orthogonal control of cell microenvironments. Chem Soc Rev 2013; 42:7335-72. [PMID: 23609001 PMCID: PMC3762890 DOI: 10.1039/c3cs60040h] [Citation(s) in RCA: 498] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Indexed: 12/12/2022]
Abstract
Degradable and cell-compatible hydrogels can be designed to mimic the physical and biochemical characteristics of native extracellular matrices and provide tunability of degradation rates and related properties under physiological conditions. Hence, such hydrogels are finding widespread application in many bioengineering fields, including controlled bioactive molecule delivery, cell encapsulation for controlled three-dimensional culture, and tissue engineering. Cellular processes, such as adhesion, proliferation, spreading, migration, and differentiation, can be controlled within degradable, cell-compatible hydrogels with temporal tuning of biochemical or biophysical cues, such as growth factor presentation or hydrogel stiffness. However, thoughtful selection of hydrogel base materials, formation chemistries, and degradable moieties is necessary to achieve the appropriate level of property control and desired cellular response. In this review, hydrogel design considerations and materials for hydrogel preparation, ranging from natural polymers to synthetic polymers, are overviewed. Recent advances in chemical and physical methods to crosslink hydrogels are highlighted, as well as recent developments in controlling hydrogel degradation rates and modes of degradation. Special attention is given to spatial or temporal presentation of various biochemical and biophysical cues to modulate cell response in static (i.e., non-degradable) or dynamic (i.e., degradable) microenvironments. This review provides insight into the design of new cell-compatible, degradable hydrogels to understand and modulate cellular processes for various biomedical applications.
Collapse
Affiliation(s)
- Prathamesh M. Kharkar
- Department of Materials Science and Engineering , University of Delaware , Newark , DE 19716 , USA . ;
| | - Kristi L. Kiick
- Department of Materials Science and Engineering , University of Delaware , Newark , DE 19716 , USA . ;
- Biomedical Engineering , University of Delaware , Newark , DE 19716 , USA
- Delaware Biotechnology Institute , University of Delaware , Newark , DE 19716 , USA
| | - April M. Kloxin
- Department of Materials Science and Engineering , University of Delaware , Newark , DE 19716 , USA . ;
- Department of Chemical and Biomolecular Engineering , University of Delaware , Newark , DE 19716 , USA
| |
Collapse
|
146
|
Lisabeth EM, Falivelli G, Pasquale EB. Eph receptor signaling and ephrins. Cold Spring Harb Perspect Biol 2013; 5:5/9/a009159. [PMID: 24003208 DOI: 10.1101/cshperspect.a009159] [Citation(s) in RCA: 314] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Eph receptors are the largest of the RTK families. Like other RTKs, they transduce signals from the cell exterior to the interior through ligand-induced activation of their kinase domain. However, the Eph receptors also have distinctive features. Instead of binding soluble ligands, they generally mediate contact-dependent cell-cell communication by interacting with surface-associated ligands-the ephrins-on neighboring cells. Eph receptor-ephrin complexes emanate bidirectional signals that affect both receptor- and ephrin-expressing cells. Intriguingly, ephrins can also attenuate signaling by Eph receptors coexpressed in the same cell. Additionally, Eph receptors can modulate cell behavior independently of ephrin binding and kinase activity. The Eph/ephrin system regulates many developmental processes and adult tissue homeostasis. Its abnormal function has been implicated in various diseases, including cancer. Thus, Eph receptors represent promising therapeutic targets. However, more research is needed to better understand the many aspects of their complex biology that remain mysterious.
Collapse
Affiliation(s)
- Erika M Lisabeth
- Cancer Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA
| | | | | |
Collapse
|
147
|
Signaling mechanisms of glucose-induced F-actin remodeling in pancreatic islet β cells. Exp Mol Med 2013; 45:e37. [PMID: 23969997 PMCID: PMC3789261 DOI: 10.1038/emm.2013.73] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 06/24/2013] [Indexed: 12/12/2022] Open
Abstract
The maintenance of whole-body glucose homeostasis is critical for survival, and is controlled by the coordination of multiple organs and endocrine systems. Pancreatic islet β cells secrete insulin in response to nutrient stimuli, and insulin then travels through the circulation promoting glucose uptake into insulin-responsive tissues such as liver, skeletal muscle and adipose. Many of the genes identified in human genome-wide association studies of diabetic individuals are directly associated with β cell survival and function, giving credence to the idea that β-cell dysfunction is central to the development of type 2 diabetes. As such, investigations into the mechanisms by which β cells sense glucose and secrete insulin in a regulated manner are a major focus of current diabetes research. In particular, recent discoveries of the detailed role and requirements for reorganization/remodeling of filamentous actin (F-actin) in the regulation of insulin release from the β cell have appeared at the forefront of islet function research, having lapsed in prior years due to technical limitations. Recent advances in live-cell imaging and specialized reagents have revealed localized F-actin remodeling to be a requisite for the normal biphasic pattern of nutrient-stimulated insulin secretion. This review will provide an historical look at the emergent focus on the role of the actin cytoskeleton and its regulation of insulin secretion, leading up to the cutting-edge research in progress in the field today.
Collapse
|
148
|
Borden P, Houtz J, Leach SD, Kuruvilla R. Sympathetic innervation during development is necessary for pancreatic islet architecture and functional maturation. Cell Rep 2013; 4:287-301. [PMID: 23850289 DOI: 10.1016/j.celrep.2013.06.019] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 05/24/2013] [Accepted: 06/18/2013] [Indexed: 12/30/2022] Open
Abstract
Sympathetic neurons depend on target-derived neurotrophic cues to control their survival and growth. However, whether sympathetic innervation contributes reciprocally to the development of target tissues is less clear. Here, we report that sympathetic innervation is necessary for the formation of the pancreatic islets of Langerhans and for their functional maturation. Genetic or pharmacological ablation of sympathetic innervation during development resulted in altered islet architecture, reduced insulin secretion, and impaired glucose tolerance in mice. Similar defects were observed with pharmacological blockade of β-adrenergic signaling. Conversely, the administration of a β-adrenergic agonist restored islet morphology and glucose tolerance in deinnervated animals. Furthermore, in neuron-islet cocultures, sympathetic neurons promoted islet cell migration in a β-adrenergic-dependent manner. This study reveals that islet architecture requires extrinsic inductive cues from neighboring tissues such as sympathetic nerves and suggests that early perturbations in sympathetic innervation might underlie metabolic disorders.
Collapse
Affiliation(s)
- Philip Borden
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | | | | |
Collapse
|
149
|
Zhang C, Suckow AT, Chessler SD. Coculture analysis of extracellular protein interactions affecting insulin secretion by pancreatic beta cells. J Vis Exp 2013:e50365. [PMID: 23793074 DOI: 10.3791/50365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Interactions between cell-surface proteins help coordinate the function of neighboring cells. Pancreatic beta cells are clustered together within pancreatic islets and act in a coordinated fashion to maintain glucose homeostasis. It is becoming increasingly clear that interactions between transmembrane proteins on the surfaces of adjacent beta cells are important determinants of beta-cell function. Elucidation of the roles of particular transcellular interactions by knockdown, knockout or overexpression studies in cultured beta cells or in vivo necessitates direct perturbation of mRNA and protein expression, potentially affecting beta-cell health and/or function in ways that could confound analyses of the effects of specific interactions. These approaches also alter levels of the intracellular domains of the targeted proteins and may prevent effects due to interactions between proteins within the same cell membrane to be distinguished from the effects of transcellular interactions. Here a method for determining the effect of specific transcellular interactions on the insulin secreting capacity and responsiveness of beta cells is presented. This method is applicable to beta-cell lines, such as INS-1 cells, and to dissociated primary beta cells. It is based on coculture models developed by neurobiologists, who found that exposure of cultured neurons to specific neuronal proteins expressed on HEK293 (or COS) cell layers identified proteins important for driving synapse formation. Given the parallels between the secretory machinery of neuronal synapses and of beta cells, we reasoned that beta-cell functional maturation might be driven by similar transcellular interactions. We developed a system where beta cells are cultured on a layer of HEK293 cells expressing a protein of interest. In this model, the beta-cell cytoplasm is untouched while extracellular protein-protein interactions are manipulated. Although we focus here primarily on studies of glucose-stimulated insulin secretion, other processes can be analyzed; for example, changes in gene expression as determined by immunoblotting or qPCR.
Collapse
Affiliation(s)
- Charles Zhang
- Pediatric Diabetes Research Center, University of California, San Diego
| | | | | |
Collapse
|
150
|
Zhang C, Suckow AT, Chessler SD. Altered pancreatic islet function and morphology in mice lacking the Beta-cell surface protein neuroligin-2. PLoS One 2013; 8:e65711. [PMID: 23776533 PMCID: PMC3679192 DOI: 10.1371/journal.pone.0065711] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 05/03/2013] [Indexed: 11/24/2022] Open
Abstract
Neuroligin-2 is a transmembrane, cell-surface protein originally identified as an inhibitory synapse-associated protein in the central nervous system. Neuroligin-2 is also present on the pancreatic beta-cell surface, and there it engages in transcellular interactions that drive functional maturation of the insulin secretory machinery; these are necessary for normal insulin secretion. The effects of neuroligin-2 deficiency on brain and neuronal function and morphology and on behavior and coordination have been extensively characterized using neuroligin-2 knockout mice. The effects of absent neuroligin-2 expression on islet development and function, however, are unknown. Here, to help test whether neuroligin-2 is necessary for normal islet development, we characterized islet morphology in mice lacking neuroligin-2. To test whether–as predicted by our earlier co-culture studies–absence of neuroligin-2 impairs beta cell function, we compared glucose-stimulated insulin secretion by islets from mutant and wild-type mice. Our results show that while islets from neuroligin-2-deficient mice do not to appear to differ architecturally from wild-type islets, they are smaller, fewer in number, and contain beta cells with lower insulin content. Evaluation of transcript levels suggests that upregulation of neuroligin-1 helps compensate for loss of neuroligin-2. Surprisingly, under both basal and stimulating glucose levels, isolated islets from the knockout mice secreted more of their intracellular insulin content. Rat islets with shRNA-mediated neuroligin-2 knockdown also exhibited increased insulin secretion. Neurexin transcript levels were lower in the knockout mice and, consistent with our prior finding that neurexin is a key constituent of the insulin granule docking machinery, insulin granule docking was reduced. These results indicate that neuroligin-2 is not necessary for the formation of pancreatic islets but that neuroligin-2 influences islet size and number. Neuroligin-2–perhaps through its effects on the expression and/or activity of its binding partner neurexin–promotes insulin granule docking, a known constraint on insulin secretion.
Collapse
Affiliation(s)
- Charles Zhang
- Department of Medicine, University of California Irvine, School of Medicine, Irvine, California, United States of America
| | - Arthur T. Suckow
- Pediatric Diabetes Research Center, University of California San Diego, La Jolla, California, United States of America
| | - Steven D. Chessler
- Department of Medicine, University of California Irvine, School of Medicine, Irvine, California, United States of America
- * E-mail:
| |
Collapse
|