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Yi H, Gong D, Daddysman MK, Renn M, Scherer NF. Distinct Sub- to Superdiffuse Insulin Granule Transport Behaviors in β-Cells Are Strongly Affected by Granule Age. J Phys Chem B 2024; 128:6246-6256. [PMID: 38861346 DOI: 10.1021/acs.jpcb.4c01403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Intracellular transport is a complex process that is difficult to describe by a single general model for motion. Here, we study the transport of insulin containing vesicles, termed granules, in live MIN6 cells. We characterize how the observed heterogeneity is affected by different intracellular factors by constructing a MIN6 cell line by CRISPR-CAS9 that constitutively expresses mCherry fused to insulin and is thus packaged in granules. Confocal microscopy imaging and single particle tracking of the granule transport provide long trajectories of thousands of single granule trajectories for statistical analysis. Mean squared displacement (MSD), angle correlation distribution, and step size distribution analysis allowed identifying five distinct granule transport subpopulations, from nearly immobile and subdiffusive to run-pause and superdiffusive. The subdiffusive subpopulation recapitulates the subordinated random walk we reported earlier (Tabei, 2013; ref 18). We show that the transport characteristics of the five subpopulations have a strong dependence on the age of insulin granules. The five subpopulations also reflect the effect of local microtubule and actin networks on transport in different cellular regions. Our results provide robust metrics to clarify the heterogeneity of granule transport and demonstrate the roles of microtubule versus actin networks with granule age since initial packaging in the Golgi.
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Affiliation(s)
- Hannah Yi
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
| | - Daozheng Gong
- Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
- Graduate Program in Biophysical Science, University of Chicago, Chicago, Illinois 60637, United States
| | - Matthew K Daddysman
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
| | - Martha Renn
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
| | - Norbert F Scherer
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
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2
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Kawasaki E. Anti-Islet Autoantibodies in Type 1 Diabetes. Int J Mol Sci 2023; 24:10012. [PMID: 37373160 DOI: 10.3390/ijms241210012] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/08/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Anti-islet autoantibodies serve as key markers in immune-mediated type 1 diabetes (T1D) and slowly progressive T1D (SPIDDM), also known as latent autoimmune diabetes in adults (LADA). Autoantibodies to insulin (IAA), glutamic acid decarboxylase (GADA), tyrosine phosphatase-like protein IA-2 (IA-2A), and zinc transporter 8 (ZnT8A) are currently employed in the diagnosis, pathological analysis, and prediction of T1D. GADA can also be detected in non-diabetic patients with autoimmune diseases other than T1D and may not necessarily reflect insulitis. Conversely, IA-2A and ZnT8A serve as surrogate markers of pancreatic β-cell destruction. A combinatorial analysis of these four anti-islet autoantibodies demonstrated that 93-96% of acute-onset T1D and SPIDDM cases were diagnosed as immune-mediated T1D, while the majority of fulminant T1D cases were autoantibody-negative. Evaluating the epitopes and immunoglobulin subclasses of anti-islet autoantibodies help distinguish between diabetes-associated and non-diabetes-associated autoantibodies and is valuable for predicting future insulin deficiency in SPIDDM (LADA) patients. Additionally, GADA in T1D patients with autoimmune thyroid disease reveals the polyclonal expansion of autoantibody epitopes and immunoglobulin subclasses. Recent advancements in anti-islet autoantibody assays include nonradioactive fluid-phase assays and the simultaneous determination of multiple biochemically defined autoantibodies. Developing a high-throughput assay for detecting epitope-specific or immunoglobulin isotype-specific autoantibodies will facilitate a more accurate diagnosis and prediction of autoimmune disorders. The aim of this review is to summarize what is known about the clinical significance of anti-islet autoantibodies in the pathogenesis and diagnosis of T1D.
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Affiliation(s)
- Eiji Kawasaki
- Diabetes Center, Shin-Koga Hospital, Kurume 830-8577, Japan
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3
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Kreissl FK, Banki MA, Droujinine IA. Molecular methods to study protein trafficking between organs. Proteomics 2023; 23:e2100331. [PMID: 36478633 DOI: 10.1002/pmic.202100331] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/16/2022] [Accepted: 11/21/2022] [Indexed: 12/13/2022]
Abstract
Interorgan communication networks are key regulators of organismal homeostasis, and their dysregulation is associated with a variety of pathologies. While mass spectrometry proteomics identifies circulating proteins and can correlate their abundance with disease phenotypes, the tissues of origin and destinations of these secreted proteins remain largely unknown. In vitro approaches to study protein secretion are valuable, however, they may not mimic the complexity of in vivo environments. More recently, the development of engineered promiscuous BirA* biotin ligase derivatives has enabled tissue-specific tagging of cellular secreted proteomes in vivo. The use of biotin as a molecular tag provides information on the tissue of origin and destination, and enables the enrichment of low-abundance hormone proteins. Therefore, promiscuous protein biotinylation is a valuable tool to study protein secretion in vivo.
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Affiliation(s)
- Felix K Kreissl
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California, USA
| | - Michael A Banki
- Department of Molecular Medicine, Scripps Research, La Jolla, California, USA
| | - Ilia A Droujinine
- Department of Molecular Medicine, Scripps Research, La Jolla, California, USA
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4
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Göcz B, Takács S, Skrapits K, Rumpler É, Solymosi N, Póliska S, Colledge WH, Hrabovszky E, Sárvári M. Estrogen differentially regulates transcriptional landscapes of preoptic and arcuate kisspeptin neuron populations. Front Endocrinol (Lausanne) 2022; 13:960769. [PMID: 36093104 PMCID: PMC9454256 DOI: 10.3389/fendo.2022.960769] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/28/2022] [Indexed: 11/17/2022] Open
Abstract
Kisspeptin neurons residing in the rostral periventricular area of the third ventricle (KPRP3V) and the arcuate nucleus (KPARC) mediate positive and negative estrogen feedback, respectively. Here, we aim to compare transcriptional responses of KPRP3V and KPARC neurons to estrogen. Transgenic mice were ovariectomized and supplemented with either 17β-estradiol (E2) or vehicle. Fluorescently tagged KPRP3V neurons collected by laser-capture microdissection were subjected to RNA-seq. Bioinformatics identified 222 E2-dependent genes. Four genes encoding neuropeptide precursors (Nmb, Kiss1, Nts, Penk) were robustly, and Cartpt was subsignificantly upregulated, suggesting putative contribution of multiple neuropeptides to estrogen feedback mechanisms. Using overrepresentation analysis, the most affected KEGG pathways were neuroactive ligand-receptor interaction and dopaminergic synapse. Next, we re-analyzed our previously obtained KPARC neuron RNA-seq data from the same animals using identical bioinformatic criteria. The identified 1583 E2-induced changes included suppression of many neuropeptide precursors, granins, protein processing enzymes, and other genes related to the secretory pathway. In addition to distinct regulatory responses, KPRP3V and KPARC neurons exhibited sixty-two common changes in genes encoding three hormone receptors (Ghsr, Pgr, Npr2), GAD-65 (Gad2), calmodulin and its regulator (Calm1, Pcp4), among others. Thirty-four oppositely regulated genes (Kiss1, Vgf, Chrna7, Tmem35a) were also identified. The strikingly different transcriptional responses in the two neuron populations prompted us to explore the transcriptional mechanism further. We identified ten E2-dependent transcription factors in KPRP3V and seventy in KPARC neurons. While none of the ten transcription factors interacted with estrogen receptor-α, eight of the seventy did. We propose that an intricate, multi-layered transcriptional mechanism exists in KPARC neurons and a less complex one in KPRP3V neurons. These results shed new light on the complexity of estrogen-dependent regulatory mechanisms acting in the two functionally distinct kisspeptin neuron populations and implicate additional neuropeptides and mechanisms in estrogen feedback.
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Affiliation(s)
- Balázs Göcz
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, Hungary
- *Correspondence: Erik Hrabovszky, ; Miklós Sárvári, ; Balázs Göcz,
| | - Szabolcs Takács
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Katalin Skrapits
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Éva Rumpler
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Norbert Solymosi
- Centre for Bioinformatics, University of Veterinary Medicine, Budapest, Hungary
| | - Szilárd Póliska
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - William H. Colledge
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Erik Hrabovszky
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
- *Correspondence: Erik Hrabovszky, ; Miklós Sárvári, ; Balázs Göcz,
| | - Miklós Sárvári
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
- *Correspondence: Erik Hrabovszky, ; Miklós Sárvári, ; Balázs Göcz,
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5
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Bulfoni M, Bouyioukos C, Zakaria A, Nigon F, Rapone R, Del Maestro L, Ait-Si-Ali S, Scharfmann R, Cosson B. Glucose controls co-translation of structurally related mRNAs via the mTOR and eIF2 pathways in human pancreatic beta cells. Front Endocrinol (Lausanne) 2022; 13:949097. [PMID: 35992129 PMCID: PMC9388909 DOI: 10.3389/fendo.2022.949097] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
Pancreatic beta cell response to glucose is critical for the maintenance of normoglycemia. A strong transcriptional response was classically described in rodent models but, interestingly, not in human cells. In this study, we exposed human pancreatic beta cells to an increased concentration of glucose and analysed at a global level the mRNAs steady state levels and their translationalability. Polysome profiling analysis showed an early acute increase in protein synthesis and a specific translation regulation of more than 400 mRNAs, independently of their transcriptional regulation. We clustered the co-regulated mRNAs according to their behaviour in translation in response to glucose and discovered common structural and sequence mRNA features. Among them mTOR- and eIF2-sensitive elements have a predominant role to increase mostly the translation of mRNAs encoding for proteins of the translational machinery. Furthermore, we show that mTOR and eIF2α pathways are independently regulated in response to glucose, participating to a translational reshaping to adapt beta cell metabolism. The early acute increase in the translation machinery components prepare the beta cell for further protein demand due to glucose-mediated metabolism changes.
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Affiliation(s)
- Manuel Bulfoni
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | - Costas Bouyioukos
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | - Albatoul Zakaria
- Université Paris Cité, Institut Cochin, INSERM, CNRS, Paris, France
| | - Fabienne Nigon
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | - Roberta Rapone
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | | | | | | | - Bertrand Cosson
- Université Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
- *Correspondence: Bertrand Cosson,
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6
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Sevillano J, Sánchez-Alonso MG, Pizarro-Delgado J, Ramos-Álvarez MDP. Role of Receptor Protein Tyrosine Phosphatases (RPTPs) in Insulin Signaling and Secretion. Int J Mol Sci 2021; 22:ijms22115812. [PMID: 34071721 PMCID: PMC8198922 DOI: 10.3390/ijms22115812] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/21/2021] [Accepted: 05/24/2021] [Indexed: 01/12/2023] Open
Abstract
Changes in lifestyle in developed countries have triggered the prevalence of obesity and type 2 diabetes mellitus (T2DM) in the latest years. Consequently, these metabolic diseases associated to insulin resistance, and the morbidity associated with them, accounts for enormous costs for the health systems. The best way to face this problem is to identify potential therapeutic targets and/or early biomarkers to help in the treatment and in the early detection. In the insulin receptor signaling cascade, the activities of protein tyrosine kinases and phosphatases are coordinated, thus, protein tyrosine kinases amplify the insulin signaling response, whereas phosphatases are required for the regulation of the rate and duration of that response. The focus of this review is to summarize the impact of transmembrane receptor protein tyrosine phosphatase (RPTPs) in the insulin signaling cascade and secretion, and their implication in metabolic diseases such as obesity and T2DM.
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7
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Harrison NJ, Connolly E, Gascón Gubieda A, Yang Z, Altenhein B, Losada Perez M, Moreira M, Sun J, Hidalgo A. Regenerative neurogenic response from glia requires insulin-driven neuron-glia communication. eLife 2021; 10:58756. [PMID: 33527895 PMCID: PMC7880684 DOI: 10.7554/elife.58756] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 02/01/2021] [Indexed: 12/21/2022] Open
Abstract
Understanding how injury to the central nervous system induces de novo neurogenesis in animals would help promote regeneration in humans. Regenerative neurogenesis could originate from glia and glial neuron-glia antigen-2 (NG2) may sense injury-induced neuronal signals, but these are unknown. Here, we used Drosophila to search for genes functionally related to the NG2 homologue kon-tiki (kon), and identified Islet Antigen-2 (Ia-2), required in neurons for insulin secretion. Both loss and over-expression of ia-2 induced neural stem cell gene expression, injury increased ia-2 expression and induced ectopic neural stem cells. Using genetic analysis and lineage tracing, we demonstrate that Ia-2 and Kon regulate Drosophila insulin-like peptide 6 (Dilp-6) to induce glial proliferation and neural stem cells from glia. Ectopic neural stem cells can divide, and limited de novo neurogenesis could be traced back to glial cells. Altogether, Ia-2 and Dilp-6 drive a neuron-glia relay that restores glia and reprogrammes glia into neural stem cells for regeneration.
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Affiliation(s)
- Neale J Harrison
- Structural Plasticity & Regeneration Group, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Elizabeth Connolly
- Structural Plasticity & Regeneration Group, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Alicia Gascón Gubieda
- Structural Plasticity & Regeneration Group, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Zidan Yang
- Structural Plasticity & Regeneration Group, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | | | - Maria Losada Perez
- Instituto Cajal, Consejo Superior de Investigaciones Cientificas (CSIC), Madrid, Spain
| | - Marta Moreira
- Structural Plasticity & Regeneration Group, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Jun Sun
- Structural Plasticity & Regeneration Group, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Alicia Hidalgo
- Structural Plasticity & Regeneration Group, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
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8
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Reiterer V, Pawłowski K, Desrochers G, Pause A, Sharpe HJ, Farhan H. The dead phosphatases society: a review of the emerging roles of pseudophosphatases. FEBS J 2020; 287:4198-4220. [PMID: 32484316 DOI: 10.1111/febs.15431] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/12/2020] [Accepted: 05/27/2020] [Indexed: 12/11/2022]
Abstract
Phosphatases are a diverse family of enzymes, comprising at least 10 distinct protein folds. Like most other enzyme families, many have sequence variations that predict an impairment or loss of catalytic activity classifying them as pseudophosphatases. Research on pseudoenzymes is an emerging area of interest, with new biological functions repurposed from catalytically active relatives. Here, we provide an overview of the pseudophosphatases identified to date in all major phosphatase families. We will highlight the degeneration of the various catalytic sequence motifs and discuss the challenges associated with the experimental determination of catalytic inactivity. We will also summarize the role of pseudophosphatases in various diseases and discuss the major challenges and future directions in this field.
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Affiliation(s)
| | | | - Guillaume Desrochers
- Department of Biochemistry, McGill University, Montréal, QC, Canada.,Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada
| | - Arnim Pause
- Department of Biochemistry, McGill University, Montréal, QC, Canada.,Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada
| | | | - Hesso Farhan
- Institute of Basic Medical Sciences, University of Oslo, Norway
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9
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Smith KE, Purvis WG, Davis MA, Min CG, Cooksey AM, Weber CS, Jandova J, Price ND, Molano DS, Stanton JB, Kelly AC, Steyn LV, Lynch RM, Limesand SW, Alexander M, Lakey JRT, Seeberger K, Korbutt GS, Mueller KR, Hering BJ, McCarthy FM, Papas KK. In vitro characterization of neonatal, juvenile, and adult porcine islet oxygen demand, β-cell function, and transcriptomes. Xenotransplantation 2018; 25:e12432. [PMID: 30052287 DOI: 10.1111/xen.12432] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/20/2018] [Accepted: 05/24/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND There is currently a shortage of human donor pancreata which limits the broad application of islet transplantation as a treatment for type 1 diabetes. Porcine islets have demonstrated potential as an alternative source, but a study evaluating islets from different donor ages under unified protocols has yet to be conducted. METHODS Neonatal porcine islets (NPI; 1-3 days), juvenile porcine islets (JPI; 18-21 days), and adult porcine islets (API; 2+ years) were compared in vitro, including assessments of oxygen consumption rate, membrane integrity determined by FDA/PI staining, β-cell proliferation, dynamic glucose-stimulated insulin secretion, and RNA sequencing. RESULTS Oxygen consumption rate normalized to DNA was not significantly different between ages. Membrane integrity was age dependent, and API had the highest percentage of intact cells. API also had the highest glucose-stimulated insulin secretion response during a dynamic insulin secretion assay and had 50-fold higher total insulin content compared to NPI and JPI. NPI and JPI had similar glucose responsiveness, β-cell percentage, and β-cell proliferation rate. Transcriptome analysis was consistent with physiological assessments. API transcriptomes were enriched for cellular metabolic and insulin secretory pathways, while NPI exhibited higher expression of genes associated with proliferation. CONCLUSIONS The oxygen demand, membrane integrity, β-cell function and proliferation, and transcriptomes of islets from API, JPI, and NPI provide a comprehensive physiological comparison for future studies. These assessments will inform the optimal application of each age of porcine islet to expand the availability of islet transplantation.
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Affiliation(s)
- Kate E Smith
- Department of Physiological Sciences, University of Arizona, Tucson, AZ, USA.,Department of Surgery, University of Arizona, Tucson, AZ, USA
| | | | - Melissa A Davis
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Catherine G Min
- Department of Physiological Sciences, University of Arizona, Tucson, AZ, USA.,Department of Surgery, University of Arizona, Tucson, AZ, USA
| | - Amanda M Cooksey
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Craig S Weber
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Jana Jandova
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | | | - Diana S Molano
- Department of Surgery, University of Arizona, Tucson, AZ, USA
| | | | - Amy C Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Leah V Steyn
- Department of Surgery, University of Arizona, Tucson, AZ, USA
| | - Ronald M Lynch
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Michael Alexander
- Department of Surgery, University of California-Irvine, Orange, CA, USA
| | | | - Karen Seeberger
- Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AL, Canada
| | - Gregory S Korbutt
- Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AL, Canada
| | - Kate R Mueller
- Schulze Diabetes Institute, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Bernhard J Hering
- Schulze Diabetes Institute, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Fiona M McCarthy
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
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10
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Quinault A, Leloup C, Denwood G, Spiegelhalter C, Rodriguez M, Lefebvre P, Messaddeq N, Zhang Q, Dacquet C, Pénicaud L, Collins SC. Modulation of large dense core vesicle insulin content mediates rhythmic hormone release from pancreatic beta cells over the 24h cycle. PLoS One 2018; 13:e0193882. [PMID: 29543849 PMCID: PMC5854349 DOI: 10.1371/journal.pone.0193882] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 02/20/2018] [Indexed: 11/19/2022] Open
Abstract
The rhythmic nature of insulin secretion over the 24h cycle in pancreatic islets has been mostly investigated using transcriptomics studies showing that modulation of insulin secretion over this cycle is achieved via distal stages of insulin secretion. We set out to measure β-cell exocytosis using in depth cell physiology techniques at several time points. In agreement with the activity and feeding pattern of nocturnal rodents, we find that C57/Bl6J islets in culture for 24h exhibit higher insulin secretion during the corresponding dark phase than in the light phase (Zeitgeber Time ZT20 and ZT8, respectively, in vivo). Glucose-induced insulin secretion is increased by 21% despite normal intracellular Ca2+ transients and depolarization-evoked exocytosis, as measured by whole-cell capacitance measurements. This paradox is explained by a 1.37-fold increase in beta cell insulin content. Ultramorphological analyses show that vesicle size and density are unaltered, demonstrating that intravesicular insulin content per granule is modulated over the 24h cycle. Proinsulin levels did not change between ZT8 and ZT20. Islet glucagon content was inversely proportional to insulin content indicating that this unique feature is likely to support a physiological role. Microarray data identified the differential expression of 301 transcripts, of which 26 are miRNAs and 54 are known genes (including C2cd4b, a gene previously involved in insulin processing, and clock genes such as Bmal1 and Rev-erbα). Mouse β-cell secretion over the full course of the 24h cycle may rely on several distinct cellular functions but late night increase in insulin secretion depends solely on granule insulin content.
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Affiliation(s)
- Aurore Quinault
- CSGA, AgroSup Dijon, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, Dijon, France
| | - Corinne Leloup
- CSGA, AgroSup Dijon, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, Dijon, France
| | - Geoffrey Denwood
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, Oxford, United Kingdom
| | | | - Marianne Rodriguez
- Metabolism Discovery Research Pole of Therapeutical innovation Institut de Recherche Servier, 11 rue des Moulineaux Suresnes, France
| | - Philippe Lefebvre
- European Genomic Institute for Diabetes and UMR 1011 Inserm Université Nord de France-Institut Pasteur de Lille, Boulevard du Professeur Leclerc, Lille, France
| | | | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Headington, Oxford, United Kingdom
| | - Catherine Dacquet
- Biotechnology and Biomarker Research, Institut de Recherche Servier, 125 Chemin de Ronde, Croissy sur Seine, France
| | - Luc Pénicaud
- CSGA, AgroSup Dijon, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, Dijon, France
| | - Stephan C. Collins
- CSGA, AgroSup Dijon, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, Dijon, France
- IGBMC, 1 Rue Laurent Fries, Illkirch-Graffenstaden, France
- * E-mail:
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11
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Huang H, Zhu Y, Eliot MN, Knopik VS, McGeary JE, Carskadon MA, Hart AC. Combining Human Epigenetics and Sleep Studies in Caenorhabditis elegans: A Cross-Species Approach for Finding Conserved Genes Regulating Sleep. Sleep 2018; 40:3738764. [PMID: 28431118 DOI: 10.1093/sleep/zsx063] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Study Objectives We aimed to test a combined approach to identify conserved genes regulating sleep and to explore the association between DNA methylation and sleep length. Methods We identified candidate genes associated with shorter versus longer sleep duration in college students based on DNA methylation using Illumina Infinium HumanMethylation450 BeadChip arrays. Orthologous genes in Caenorhabditis elegans were identified, and we examined whether their loss of function affected C. elegans sleep. For genes whose perturbation affected C. elegans sleep, we subsequently undertook a small pilot study to re-examine DNA methylation in an independent set of human participants with shorter versus longer sleep durations. Results Eighty-seven out of 485,577 CpG sites had significant differential methylation in young adults with shorter versus longer sleep duration, corresponding to 52 candidate genes. We identified 34 C. elegans orthologs, including NPY/flp-18 and flp-21, which are known to affect sleep. Loss of five additional genes alters developmentally timed C. elegans sleep (B4GALT6/bre-4, DOCK180/ced-5, GNB2L1/rack-1, PTPRN2/ida-1, ZFYVE28/lst-2). For one of these genes, ZFYVE28 (also known as hLst2), the pilot replication study again found decreased DNA methylation associated with shorter sleep duration at the same two CpG sites in the first intron of ZFYVE28. Conclusions Using an approach that combines human epigenetics and C. elegans sleep studies, we identified five genes that play previously unidentified roles in C. elegans sleep. We suggest sleep duration in humans may be associated with differential DNA methylation at specific sites and that the conserved genes identified here likely play roles in C. elegans sleep and in other species.
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Affiliation(s)
- Huiyan Huang
- Department of Neuroscience, Brown University, Providence, RI
| | - Yong Zhu
- Department of Environmental Health Sciences, Yale University School of Public Health, New Haven, CT
| | - Melissa N Eliot
- Department of Epidemiology, Brown University, Providence, RI
| | - Valerie S Knopik
- Division of Behavioral Genetics, Department of Psychiatry, Rhode Island Hospital, Providence, RI.,Department of Psychiatry and Human Behavior, Brown University, Providence, RI
| | - John E McGeary
- Division of Behavioral Genetics, Department of Psychiatry, Rhode Island Hospital, Providence, RI.,Department of Psychiatry and Human Behavior, Brown University, Providence, RI.,Providence Veterans Affairs Medical Center, Providence, RI
| | - Mary A Carskadon
- Department of Psychiatry and Human Behavior, Brown University, Providence, RI.,E.P. Bradley Hospital Sleep Research Laboratory, Providence, RI.,Center for Sleep Research, University of South Australia, Adelaide, Australia
| | - Anne C Hart
- Department of Neuroscience, Brown University, Providence, RI
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12
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Cai T, Notkins AL. Pathophysiologic changes in IA-2/IA-2β null mice are secondary to alterations in the secretion of hormones and neurotransmitters. Acta Diabetol 2016; 53:7-12. [PMID: 25861885 PMCID: PMC5243143 DOI: 10.1007/s00592-015-0750-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 03/26/2015] [Indexed: 12/13/2022]
Abstract
IA-2 and IA-2β are transmembrane proteins of dense-core vesicles (DCV). The deletion of these proteins results in a reduction in the number of DCV and the secretion of hormones and neurotransmitters. As a result, this leads to a variety of pathophysiologic changes. The purpose of this review is to describe these changes, which are characterized by glucose intolerance, female infertility, behavior and learning abnormalities and alterations in the diurnal circadian rhythms of blood pressure, heart rate, spontaneous physical activity and body temperature. These findings show that the deletion of IA-2 and IA-2β results in multiple pathophysiologic changes and represents a unique in vivo model for studying the effect of hormone and neurotransmitter reduction on known and still unrecognized targets.
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Affiliation(s)
- Tao Cai
- Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), B30/Rm106, Bethesda, MD, 20892, USA
| | - Abner L Notkins
- Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), B30/Rm106, Bethesda, MD, 20892, USA.
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13
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Xu H, Abuhatzira L, Carmona GN, Vadrevu S, Satin LS, Notkins AL. The Ia-2β intronic miRNA, miR-153, is a negative regulator of insulin and dopamine secretion through its effect on the Cacna1c gene in mice. Diabetologia 2015; 58:2298-306. [PMID: 26141787 PMCID: PMC6754265 DOI: 10.1007/s00125-015-3683-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 06/11/2015] [Indexed: 12/23/2022]
Abstract
AIMS/HYPOTHESIS miR-153 is an intronic miRNA embedded in the genes that encode IA-2 (also known as PTPRN) and IA-2β (also known as PTPRN2). Islet antigen (IA)-2 and IA-2β are major autoantigens in type 1 diabetes and are important transmembrane proteins in dense core and synaptic vesicles. miR-153 and its host genes are co-regulated in pancreas and brain. The present experiments were initiated to decipher the regulatory network between miR-153 and its host gene Ia-2β (also known as Ptprn2). METHODS Insulin secretion was determined by ELISA. Identification of miRNA targets was assessed using luciferase assays and by quantitative real-time PCR and western blots in vitro and in vivo. Target protector was also employed to evaluate miRNA target function. RESULTS Functional studies revealed that miR-153 mimic suppresses both glucose- and potassium-induced insulin secretion (GSIS and PSIS, respectively), whereas miR-153 inhibitor enhances both GSIS and PSIS. A similar effect on dopamine secretion also was observed. Using miRNA target prediction software, we found that miR-153 is predicted to target the 3'UTR region of the calcium channel gene, Cacna1c. Further studies confirmed that Cacna1c mRNA and protein are downregulated by miR-153 mimics and upregulated by miR-153 inhibitors in insulin-secreting freshly isolated mouse islets, in the insulin-secreting mouse cell line MIN6 and in the dopamine-secreting cell line PC12. CONCLUSIONS/INTERPRETATION miR-153 is a negative regulator of both insulin and dopamine secretion through its effect on Cacna1c expression, which suggests that IA-2β and miR-153 have opposite functional effects on the secretory pathway.
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Affiliation(s)
- Huanyu Xu
- Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Liron Abuhatzira
- Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Gilberto N Carmona
- Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Suryakiran Vadrevu
- Brehm Diabetes Research Center, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Leslie S Satin
- Brehm Diabetes Research Center, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Abner L Notkins
- Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
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14
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Cai T, Hirai H, Xu H, Notkins AL. The minimal promoter region of the dense-core vesicle protein IA-2: transcriptional regulation by CREB. Acta Diabetol 2015; 52:573-80. [PMID: 25528004 PMCID: PMC5273861 DOI: 10.1007/s00592-014-0689-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 11/20/2014] [Indexed: 11/29/2022]
Abstract
AIMS IA-2 is a transmembrane protein found in the dense-core vesicles (DCV) of neuroendocrine cells and one of the major autoantigens in type 1 diabetes. DCV are involved in the secretion of hormones (e.g., insulin) and neurotransmitters. Stimulation of pancreatic β cells with glucose upregulates the expression of IA-2 and an increase in IA-2 results in an increase in the number of DCV. Little is known, however, about the promoter region of IA-2 or the transcriptional factors that regulate the expression of this gene. METHODS In the present study, we constructed eight deletion fragments from the upstream region of the IA-2 transcription start site and linked them to a luciferase reporter. RESULTS By this approach, we have identified a short bp region (-216 to +115) that has strong promoter activity. We also identified a transcription factor, cAMP responsive element-binding protein (CREB), which binds to two CREB-related binding sites located in this region. The binding of CREB to these sites enhanced IA-2 transcription by more than fivefold. We confirmed these findings by site-directed mutagenesis, chromatin immunoprecipitation assays and RNAi inhibition. CONCLUSION Based on these findings, we conclude that the PKA pathway is a critical, but not the exclusive signaling pathway involved in IA-2 gene expression.
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Affiliation(s)
- Tao Cai
- Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), B30/Rm106, Bethesda, MD, 20892, USA,
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15
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Aged insulin granules display reduced microtubule-dependent mobility and are disposed within actin-positive multigranular bodies. Proc Natl Acad Sci U S A 2015; 112:E667-76. [PMID: 25646459 DOI: 10.1073/pnas.1409542112] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insulin secretion is key for glucose homeostasis. Insulin secretory granules (SGs) exist in different functional pools, with young SGs being more mobile and preferentially secreted. However, the principles governing the mobility of age-distinct SGs remain undefined. Using the time-reporter insulin-SNAP to track age-distinct SGs we now show that their dynamics can be classified into three components: highly dynamic, restricted, and nearly immobile. Young SGs display all three components, whereas old SGs are either restricted or nearly immobile. Both glucose stimulation and F-actin depolymerization recruit a fraction of nearly immobile young, but not old, SGs for highly dynamic, microtubule-dependent transport. Moreover, F-actin marks multigranular bodies/lysosomes containing aged SGs. These data demonstrate that SGs lose their responsiveness to glucose stimulation and competence for microtubule-mediated transport over time while changing their relationship with F-actin.
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16
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Harashima SI, Horiuchi T, Wang Y, Notkins AL, Seino Y, Inagaki N. Sorting nexin 19 regulates the number of dense core vesicles in pancreatic β-cells. J Diabetes Investig 2014; 3:52-61. [PMID: 24843546 PMCID: PMC4014933 DOI: 10.1111/j.2040-1124.2011.00138.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Aims/Introduction: Insulinoma‐associated protein 2 (IA‐2) regulates insulin secretion and the number of dense core vesicles (DCV). However, the mechanism of regulation of DCV number by IA‐2 is unknown. We examined the effect of sorting nexin 19 (SNX19), an IA‐2 interacting protein, on insulin secretion and the number of dense core vesicles (DCV). Materials and Methods: Stable SNX19 knockdown (SNX19KD) MIN6, a mouse pancreatic β‐cell line, and stable SNX19‐reintroduced SNX19KD MIN6 were established. Quantification of DCV, and lysosomes was carried out using electron micrographs. The half‐life of DCV was detected by pulse‐chase experiment. Results: Insulin secretion and content were decreased in stable SNX19KD MIN6 cells compared with those in control MIN6 cells. Electron micrographs showed that DCV number in SNX19KD cells was decreased by approximately 75% and that DCV size was decreased by approximately 40% compared with those in control cells, respectively. Furthermore, when SNX19 was reintroduced in SNX19KD cells, insulin content, insulin secretion and DCV number were increased. The half‐life of DCV was decreased in SNX19KD cells, but was increased in SNX19KD cells in which SNX19 was reintroduced. The number of lysosomes and the activity of lysosome enzyme cathepsin D were increased by approximately threefold in SNX19KD cells compared with those in control cells. In contrast, they were decreased to approximately half to one‐third in SNX19‐reintroduced SNX19KD cells. Conclusions: SNX19 regulates the number of DCV and insulin content by stabilizing DCV in β‐cells. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00138.x, 2012)
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Affiliation(s)
- Shin-Ichi Harashima
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto
| | - Takahiko Horiuchi
- Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yu Wang
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto
| | - Abner Louis Notkins
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Yutaka Seino
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto
| | - Nobuya Inagaki
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto
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17
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Fernando R, Vonberg A, Atkins SJ, Pietropaolo S, Pietropaolo M, Smith TJ. Human fibrocytes express multiple antigens associated with autoimmune endocrine diseases. J Clin Endocrinol Metab 2014; 99:E796-803. [PMID: 24517144 PMCID: PMC4010713 DOI: 10.1210/jc.2013-3072] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Factors common to multiple autoimmune diseases have been sought vigorously. Graves' disease (GD) and type 1 diabetes mellitus (T1DM) involve end-organ remodeling. Fibrocytes participate in inflammatory diseases and were recently shown to express thyroid-specific proteins such as the thyrotropin receptor and thyroglobulin. OBJECTIVE The objective of the study was to determine whether a broader repertoire of autoantigen expression, such as proteins associated with T1DM, can be ascribed to fibrocytes. DESIGN, SETTING, AND PARTICIPANTS Fibrocytes and fibroblasts were collected and analyzed from healthy individuals and those with autoimmune diseases in an academic clinical practice. MAIN OUTCOME MEASURES Real-time PCR, Western blot analysis, gene promoter analysis, cell transfections, and flow cytometric cell sorting were performed. RESULTS Islet cell antigen ICA512 (IA-2) and islet cell autoantigen of 69 kDa (ICA69), two islet-specific proteins implicated in T1DM, are expressed by fibrocytes from healthy donors and those with T1DM, GD, and multiple sclerosis. Both transcripts are detected by PCR, the proteins are resolved on Western blots, and both gene promoters are active in fibrocytes. Levels of ICA69 are substantially higher than those of IA-2 in fibrocytes. ICA69 localizes to CD34(+) GD orbital fibroblasts putatively derived from fibrocytes, whereas higher levels of IA-2 are found in CD34(-) fibroblasts. CONCLUSIONS In addition to autoantigens implicated in thyroid autoimmunity, fibrocytes and derivative fibroblasts express multiple autoantigens associated with T1DM. This expression results from active gene promoters and abundant steady-state mRNA encoding ICA69 and IA-2. These latest findings demonstrate that fibrocytes express antigens relevant to multiple forms of endocrine autoimmunity. They suggest the potential for these cells playing a direct role in immune reactivity directed at the thyroid and pancreatic islets.
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Affiliation(s)
- Roshini Fernando
- Department of Ophthalmology and Visual Sciences (R.F., S.J.A., T.J.S.), Kellogg Eye Center and Division of Metabolism, Endocrinology, and Diabetes (A.V., S.P., M.P., T.J.S.), Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48105
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18
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Carmona GN, Nishimura T, Schindler CW, Panlilio LV, Notkins AL. The dense core vesicle protein IA-2, but not IA-2β, is required for active avoidance learning. Neuroscience 2014; 269:35-42. [PMID: 24662847 DOI: 10.1016/j.neuroscience.2014.03.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 03/12/2014] [Accepted: 03/13/2014] [Indexed: 10/25/2022]
Abstract
The islet-antigens IA-2 and IA-2β are major autoantigens in type-1 diabetes and transmembrane proteins in dense core vesicles (DCV). Recently we showed that deletion of both IA-2 and IA-2β alters the secretion of hormones and neurotransmitters and impairs behavior and learning. The present study was designed to evaluate the contribution to learning of each of these genes by using single knockout (SKO) and double knockout (DKO) mice in an active avoidance test. After 5 days of training, wild-type (WT) mice showed 60-70% active avoidance responses, whereas the DKO mice showed only 10-15% active avoidance responses. The degree of active avoidance responses in the IA-2 SKO mice was similar to that of the DKO mice, but in contrast, the IA-2β SKO mice behaved like WT mice showing 60-70% active avoidance responses. Molecular studies revealed a marked decrease in the phosphorylation of the cAMP response element-binding protein (CREB) and Ca(2+)/calmodulin-dependent protein kinase II (CAMKII) in the striatum and hippocampus of the IA-2 SKO and DKO mice, but not in the IA-2β SKO mice. To evaluate the role of CREB and CAMKII in the SKO and DKO mice, GBR-12909, which selectively blocks the dopamine uptake transporter and increases CREB and CAMKII phosphorylation, was administered. GBR-12909 restored the phosphorylation of CREB and CAMKII and increased active avoidance learning in the DKO and IA-2 SKO to near the normal levels found in the WT and IA-2β SKO mice. We conclude that in the absence of the DCV protein IA-2, active avoidance learning is impaired.
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Affiliation(s)
- G N Carmona
- Experimental Medicine Section, Laboratory of Sensory Biology Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - T Nishimura
- Experimental Medicine Section, Laboratory of Sensory Biology Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - C W Schindler
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - L V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - A L Notkins
- Experimental Medicine Section, Laboratory of Sensory Biology Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA.
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19
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Insight into insulin secretion from transcriptome and genetic analysis of insulin-producing cells of Drosophila. Genetics 2014; 197:175-92. [PMID: 24558258 PMCID: PMC4012477 DOI: 10.1534/genetics.113.160663] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Insulin-producing cells (IPCs) in the Drosophila brain produce and release insulin-like peptides (ILPs) to the hemolymph. ILPs are crucial for growth and regulation of metabolic activity in flies, functions analogous to those of mammalian insulin and insulin-like growth factors (IGFs). To identify components functioning in IPCs to control ILP production, we employed genomic and candidate gene approaches. We used laser microdissection and messenger RNA sequencing to characterize the transcriptome of larval IPCs. IPCs highly express many genes homologous to genes active in insulin-producing β-cells of the mammalian pancreas. The genes in common encode ILPs and proteins that control insulin metabolism, storage, secretion, β-cell proliferation, and some not previously linked to insulin production or β-cell function. Among these novelties is unc-104, a kinesin 3 family gene, which is more highly expressed in IPCs compared to most other neurons. Knockdown of unc-104 in IPCs impaired ILP secretion and reduced peripheral insulin signaling. Unc-104 appears to transport ILPs along axons. As a complementary approach, we tested dominant-negative Rab genes to find Rab proteins required in IPCs for ILP production or secretion. Rab1 was identified as crucial for ILP trafficking in IPCs. Inhibition of Rab1 in IPCs increased circulating sugar levels, delayed development, and lowered weight and body size. Immunofluorescence labeling of Rab1 showed its tight association with ILP2 in the Golgi of IPCs. Unc-104 and Rab1 join other proteins required for ILP transport in IPCs.
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20
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Goodyer WR, Gu X, Liu Y, Bottino R, Crabtree GR, Kim SK. Neonatal β cell development in mice and humans is regulated by calcineurin/NFAT. Dev Cell 2012; 23:21-34. [PMID: 22814600 DOI: 10.1016/j.devcel.2012.05.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 01/04/2012] [Accepted: 05/19/2012] [Indexed: 11/29/2022]
Abstract
Little is known about the mechanisms governing neonatal growth and maturation of organs. Here we demonstrate that calcineurin/Nuclear Factor of Activated T cells (Cn/NFAT) signaling regulates neonatal pancreatic development in mouse and human islets. Inactivation of calcineurin b1 (Cnb1) in mouse islets impaired dense core granule biogenesis, decreased insulin secretion, and reduced cell proliferation and mass, culminating in lethal diabetes. Pancreatic β cells lacking Cnb1 failed to express genes revealed to be direct NFAT targets required for replication, insulin storage, and secretion. In contrast, glucokinase activation stimulated Cn-dependent expression of these genes. Calcineurin inhibitors, such as tacrolimus, used for human immunosuppression, induce diabetes. Tacrolimus exposure reduced Cn/NFAT-dependent expression of factors essential for insulin dense core granule formation and secretion and neonatal β cell proliferation, consistent with our genetic studies. Discovery of conserved pathways regulating β cell maturation and proliferation suggests new strategies for controlling β cell growth or replacement in human islet diseases.
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Affiliation(s)
- William R Goodyer
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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21
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Punia S, Rumery KK, Yu EA, Lambert CM, Notkins AL, Weaver DR. Disruption of gene expression rhythms in mice lacking secretory vesicle proteins IA-2 and IA-2β. Am J Physiol Endocrinol Metab 2012; 303:E762-76. [PMID: 22785238 PMCID: PMC3468428 DOI: 10.1152/ajpendo.00513.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulinoma-associated protein (IA)-2 and IA-2β are transmembrane proteins involved in neurotransmitter secretion. Mice with targeted disruption of both IA-2 and IA-2β (double-knockout, or DKO mice) have numerous endocrine and physiological disruptions, including disruption of circadian and diurnal rhythms. In the present study, we have assessed the impact of disruption of IA-2 and IA-2β on molecular rhythms in the brain and peripheral oscillators. We used in situ hybridization to assess molecular rhythms in the hypothalamic suprachiasmatic nuclei (SCN) of wild-type (WT) and DKO mice. The results indicate significant disruption of molecular rhythmicity in the SCN, which serves as the central pacemaker regulating circadian behavior. We also used quantitative PCR to assess gene expression rhythms in peripheral tissues of DKO, single-knockout, and WT mice. The results indicate significant attenuation of gene expression rhythms in several peripheral tissues of DKO mice but not in either single knockout. To distinguish whether this reduction in rhythmicity reflects defective oscillatory function in peripheral tissues or lack of entrainment of peripheral tissues, animals were injected with dexamethasone daily for 15 days, and then molecular rhythms were assessed throughout the day after discontinuation of injections. Dexamethasone injections improved gene expression rhythms in liver and heart of DKO mice. These results are consistent with the hypothesis that peripheral tissues of DKO mice have a functioning circadian clockwork, but rhythmicity is greatly reduced in the absence of robust, rhythmic physiological signals originating from the SCN. Thus, IA-2 and IA-2β play an important role in the regulation of circadian rhythms, likely through their participation in neurochemical communication among SCN neurons.
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Affiliation(s)
- Sohan Punia
- Experimental Medicine Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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22
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Receptor type protein tyrosine phosphatases (RPTPs) - roles in signal transduction and human disease. J Cell Commun Signal 2012; 6:125-38. [PMID: 22851429 DOI: 10.1007/s12079-012-0171-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 07/12/2012] [Indexed: 01/06/2023] Open
Abstract
Protein tyrosine phosphorylation is a fundamental regulatory mechanism controlling cell proliferation, differentiation, communication, and adhesion. Disruption of this key regulatory mechanism contributes to a variety of human diseases including cancer, diabetes, and auto-immune diseases. Net protein tyrosine phosphorylation is determined by the dynamic balance of the activity of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Mammals express many distinct PTKs and PTPs. Both of these families can be sub-divided into non-receptor and receptor subtypes. Receptor protein tyrosine kinases (RPTKs) comprise a large family of cell surface proteins that initiate intracellular tyrosine phosphorylation-dependent signal transduction in response to binding of extracellular ligands, such as growth factors and cytokines. Receptor-type protein tyrosine phosphatases (RPTPs) are enzymatic and functional counterparts of RPTKs. RPTPs are a family of integral cell surface proteins that possess intracellular PTP activity, and extracellular domains that have sequence homology to cell adhesion molecules. In comparison to extensively studied RPTKs, much less is known about RPTPs, especially regarding their substrate specificities, regulatory mechanisms, biological functions, and their roles in human diseases. Based on the structure of their extracellular domains, the RPTP family can be grouped into eight sub-families. This article will review one representative member from each RPTP sub-family.
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23
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Rajagopal C, Mains RE, Eipper BA. Signaling from the secretory granule to the nucleus. Crit Rev Biochem Mol Biol 2012; 47:391-406. [PMID: 22681236 DOI: 10.3109/10409238.2012.694845] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Neurons and endocrine cells use a complex array of signaling molecules to communicate with each other and with various targets. The majority of these signaling molecules are stored in specialized organelles awaiting release on demand: 40-60 nm vesicles carry conventional or small molecule neurotransmitters, and 200-400 nm granules contain bioactive peptides. The supply of small molecule neurotransmitters is tightly regulated by local feedback of synthetic rates and transport processes at sites of release. The larger granules that contain bioactive peptides present the secretory cell with special challenges, as the peptide precursors are inserted into the lumen of the secretory pathway in the cell soma and undergo biosynthetic processing while being transported to distant sites for eventual secretion. One solution to this dilemma in information handling has been to employ proteolytic cleavage of secretory granule membrane proteins to produce cytosolic fragments that can signal to the nucleus, affecting gene expression. The use of regulated intramembrane proteolysis to signal from secretory granules to the nucleus is compared to its much better understood role in relaying information from the endoplasmic reticulum by SREBP and ATF6 and from the plasma membrane by cadherins, Notch and ErbB4.
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Affiliation(s)
- Chitra Rajagopal
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
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24
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Benitez CM, Goodyer WR, Kim SK. Deconstructing pancreas developmental biology. Cold Spring Harb Perspect Biol 2012; 4:cshperspect.a012401. [PMID: 22587935 DOI: 10.1101/cshperspect.a012401] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The relentless nature and increasing prevalence of human pancreatic diseases, in particular, diabetes mellitus and adenocarcinoma, has motivated further understanding of pancreas organogenesis. The pancreas is a multifunctional organ whose epithelial cells govern a diversity of physiologically vital endocrine and exocrine functions. The mechanisms governing the birth, differentiation, morphogenesis, growth, maturation, and maintenance of the endocrine and exocrine components in the pancreas have been discovered recently with increasing tempo. This includes recent studies unveiling mechanisms permitting unexpected flexibility in the developmental potential of immature and mature pancreatic cell subsets, including the ability to interconvert fates. In this article, we describe how classical cell biology, genetic analysis, lineage tracing, and embryological investigations are being complemented by powerful modern methods including epigenetic analysis, time-lapse imaging, and flow cytometry-based cell purification to dissect fundamental processes of pancreas development.
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Affiliation(s)
- Cecil M Benitez
- Department of Developmental Biology, Stanford University School of Medicine, California 94305-5329, USA
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Cellular Mechanisms for the Biogenesis and Transport of Synaptic and Dense-Core Vesicles. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:27-115. [DOI: 10.1016/b978-0-12-394310-1.00002-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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26
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Cai T, Hirai H, Zhang G, Zhang M, Takahashi N, Kasai H, Satin LS, Leapman RD, Notkins AL. Deletion of Ia-2 and/or Ia-2β in mice decreases insulin secretion by reducing the number of dense core vesicles. Diabetologia 2011; 54:2347-57. [PMID: 21732083 PMCID: PMC3168514 DOI: 10.1007/s00125-011-2221-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 05/23/2011] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Islet antigen 2 (IA-2) and IA-2β are dense core vesicle (DCV) transmembrane proteins and major autoantigens in type 1 diabetes. The present experiments were initiated to test the hypothesis that the knockout of the genes encoding these proteins impairs the secretion of insulin by reducing the number of DCV. METHODS Insulin secretion, content and DCV number were evaluated in islets from single knockout (Ia-2 [also known as Ptprn] KO, Ia-2β [also known as Ptprn2] KO) and double knockout (DKO) mice by a variety of techniques including electron and two-photon microscopy, membrane capacitance, Ca(2+) currents, DCV half-life, lysosome number and size and autophagy. RESULTS Islets from single and DKO mice all showed a significant decrease in insulin content, insulin secretion and the number and half-life of DCV (p < 0.05 to 0.001). Exocytosis as evaluated by two-photon microscopy, membrane capacitance and Ca(2+) currents supports these findings. Electron microscopy of islets from KO mice revealed a marked increase (p < 0.05 to 0.001) in the number and size of lysosomes and enzymatic studies showed an increase in cathepsin D activity (p < 0.01). LC3 protein, an indicator of autophagy, also was increased in islets of KO compared with wild-type mice (p < 0.05 to 0.01) suggesting that autophagy might be involved in the deletion of DCV. CONCLUSIONS/INTERPRETATION We conclude that the decrease in insulin content and secretion, resulting from the deletion of Ia-2 and/or Ia-2β, is due to a decrease in the number of DCV.
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Affiliation(s)
- T. Cai
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA
- Correspondences: T. Cai: OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-402-5320; Fax: 301-402-4163; ; Or A. Notkins: EMS, OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-496-4535; Fax: 301-402-4163;
| | - H. Hirai
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA
| | - G. Zhang
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, Maryland 20892, USA
| | - M. Zhang
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - N. Takahashi
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-Ku, Tokyo, 113-0033, Japan
| | - H. Kasai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-Ku, Tokyo, 113-0033, Japan
| | - L. S. Satin
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
- Department of Pharmacology and Brehm Diabetes Center, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - R. D. Leapman
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, Maryland 20892, USA
| | - A. L. Notkins
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA
- Correspondences: T. Cai: OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-402-5320; Fax: 301-402-4163; ; Or A. Notkins: EMS, OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-496-4535; Fax: 301-402-4163;
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Koshimizu H, Cawley NX, Kim T, Yergey AL, Loh YP. Serpinin: a novel chromogranin A-derived, secreted peptide up-regulates protease nexin-1 expression and granule biogenesis in endocrine cells. Mol Endocrinol 2011; 25:732-44. [PMID: 21436258 DOI: 10.1210/me.2010-0124] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Previously we demonstrated that chromogranin A (CgA) promoted secretory granule biogenesis in endocrine cells by stabilizing and preventing granule protein degradation in the Golgi, through up-regulation of expression of the protease inhibitor, protease nexin-1 (PN-1). However, the mechanism by which CgA signals the increase of PN-1 expression is unknown. Here we identified a 2.9-kDa CgA-C-terminus peptide, which we named serpinin, in conditioned media from AtT-20 cells, a corticotroph cell line, which up-regulated PN-1 mRNA expression. Serpinin was secreted from AtT-20 cells upon high potassium stimulation and increased PN-1 mRNA transcription in these cells, in an actinomycin D-inhibitable manner. CgA itself and other CgA-derived peptides, when added to AtT-20 cell media, had no effect on PN-1 expression. Treatment of AtT-20 cells with 10 nm serpinin elevated cAMP levels and PN-1 mRNA expression, and this effect was inhibited by a protein kinase A inhibitor, 6-22 amide. Serpinin and a cAMP analog, 8-bromo-cAMP, promoted the translocation of the transcription factor Sp1 into the nucleus, which is known to drive PN-1 expression. Additionally, an Sp1 inhibitor, mithramycin A inhibited the serpinin-induced PN-1 mRNA up-regulation. Furthermore, a luciferase reporter assay demonstrated serpinin-induced up-regulation of PN-1 promoter activity in an Sp1-dependent manner. When added to CgB-transfected 6T3 cells, a mutant AtT20 cell line, serpinin induced granule biogenesis as evidenced by the presence of CgB puncta accumulation in the processes and tips. Our findings taken together show that serpinin, a novel CgA-derived peptide, is secreted upon stimulation of corticotrophs and plays an important autocrine role in up-regulating PN-1-dependent granule biogenesis via a cAMP-protein kinase A-Sp1 pathway to replenish released granules.
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Affiliation(s)
- Hisatsugu Koshimizu
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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Liang M, Yang JL, Bian MJ, Liu J, Hong XQ, Wang YC, Huang YF, Gu SP, Yu M, Huang F, Fei J. Requirement of regulated endocrine-specific protein-18 for development and expression of regulated endocrine-specific protein-18 isoform c in mice. Mol Biol Rep 2010; 38:2557-62. [PMID: 21104147 DOI: 10.1007/s11033-010-0394-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 11/08/2010] [Indexed: 11/30/2022]
Abstract
Regulated endocrine-specific protein-18 (RESP18) is distributed mainly in the peripheral endocrine and neuroendocrine tissues. The expression of RESP18 protein is regulated by physiological factors, such as blood glucose or dopaminergic drugs, but its functions remain unclear. In this study, to explore the biological functions of RESP18 in vivo, we generated RESP18 heterozygous deficient mice, and further found RESP18 was essential for embryonic development. In addition, we cloned a new isoform of mouse RESP18 by reverse transcription-polymerase chain reaction (RT-PCR), and denominated it as RESP18-c. Mouse RESP18-c, by skipping exon4 (43 bp in length), encodes a shorter protein of 120 amino acid residues. The distribution of RESP18-c mRNA is similar with that of RESP18 mRNA in the peripheral tissues and brains of mice.
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Affiliation(s)
- Min Liang
- State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai, 200032, People's Republic of China
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Pugliese A. Insulin: a critical autoantigen and potential therapeutic agent in Type 1 diabetes. Expert Rev Clin Immunol 2010; 2:419-31. [PMID: 20476913 DOI: 10.1586/1744666x.2.3.419] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Insulin is a polypeptide hormone secreted by pancreatic beta-cells and is critical for glucose homeostasis. Abnormalities in insulin secretion result in various forms of diabetes. Type 1A diabetes is an autoimmune form in which insulin has been identified as a critical autoantigen. Recent studies have identified genetic determinants of insulin-specific autoimmune responses and insulin epitopes targeted by autoreactive T lymphocytes. The study of insulin as an autoantigen has also led to discoveries about basic mechanisms of immunological tolerance and autoimmunity. Experimental and clinical evidence suggests that insulin and insulin-derived peptides may delay and perhaps prevent the development of diabetes. Further clinical trials may identify effective treatment modalities for inhibiting diabetogenic autoimmunity and preventing disease development.
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Affiliation(s)
- Alberto Pugliese
- Diabetes Research Institute, University of Miami Miller School of Medicine, 1450 NW 10th Avenue, Miami, FL 33136, USA.
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30
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Morran MP, Casu A, Arena VC, Pietropaolo S, Zhang YJ, Satin LS, Nelson P, Omenn GS, Trucco M, Becker DJ, Pietropaolo M. Humoral autoimmunity against the extracellular domain of the neuroendocrine autoantigen IA-2 heightens the risk of type 1 diabetes. Endocrinology 2010; 151:2528-37. [PMID: 20382696 PMCID: PMC2875834 DOI: 10.1210/en.2009-1257] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The objective of this study was to determine whether antigenic determinants localized within the extracellular domain of the neuroendocrine autoantigen tyrosine phosphatase-like protein IA-2 are targets of humoral responses in type 1 diabetes (T1DM). Previous studies indicated that the immunodominant region of IA-2 is localized within its intracellular domain (IA-2ic; amino acids 601-979). We analyzed 333 subjects from the Children's Hospital of Pittsburgh study, 102 of whom progressed to insulin-requiring diabetes (prediabetics). Autoantibodies from these individuals were initially assayed for ICA512bdc (Barbara Davis Center amino acids 257-556; 630-979), IA-2ic (amino acids 601-979), and IA-2 full-length (amino acids 1-979) in addition to islet cell antibody (ICA), glutamic acid decarboxylase, 65-kDa isoform, and insulin autoantibodies. We identified an autoantibody response reactive with the extracellular domain of IA-2 that is associated with very high risk of T1DM progression. Relatives with no detectable autoantibodies against ICA512bdc (or IA-2ic) exhibited antibody responses against the IA-2 full-length peptide (log rank, P = 0.008). This effect was also observed in first-degree relatives who were positive for glutamic acid decarboxylase, 65-kDa isoform (log rank, P = 0.026) or at least two islet autoantibodies but were negative for ICA512bdc (log rank, P = 0.022). Competitive binding experiments and immunoprecipitation of the IA-2 extracellular domain (amino acid residues 26-577) further lend support for the presence of autoantibodies reactive with new antigenic determinants within the extracellular domain of IA-2. In summary, the addition of measurements of autoantibodies reactive with the IA-2 extracellular domain to assays geared to assess the progression of autoimmunity to clinical T1DM may more accurately characterize this risk. This has considerable implications not only for stratifying high diabetes risk but also facilitating the search for pathogenic epitopes to enable the design of peptide-based immunotherapies that may prevent the progression to overt T1DM at its preclinical stages.
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Affiliation(s)
- Michael P Morran
- Laboratory of Immunogenetics, The Brehm Center for Diabetes Research, 1000 Wall Street, Ann Arbor, Michigan 48105.
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Nishimura T, Harashima SI, Yafang H, Notkins AL. IA-2 modulates dopamine secretion in PC12 cells. Mol Cell Endocrinol 2010; 315:81-6. [PMID: 19799965 PMCID: PMC3495171 DOI: 10.1016/j.mce.2009.09.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 09/16/2009] [Accepted: 09/22/2009] [Indexed: 11/28/2022]
Abstract
The secretion of the hormone insulin from beta cells is modulated by the expression of the dense core vesicle transmembrane protein IA-2. Since IA-2 is found in neuroendocrine cells throughout the body, the present experiments were initiated to determine whether the expression of IA-2 also modulates the secretion of neurotransmitters. Using the dopamine-secreting pheochromocytoma cell line PC12, we found that the overexpressions of IA-2 increased the cellular content and secretion of dopamine, whereas the knockdown of IA-2 by siRNA decreased the cellular content and secretion of dopamine. Neither the overexpression nor knockdown of IA-2 influenced the uptake of [H(3)]dopamine by PC12 cells, but did influence the amount of [H(3)]dopamine secreted. Overexpression of IA-2 also increased the level of the dense core vesicle-associated proteins Rab3A, IA-2beta and secretogranin II, whereas the knockdown of IA-2 decreased the level of these proteins. We conclude that the expression of IA-2 profoundly influences the function of dense core vesicles and has a broad modulating effect on the cellular content and secretion of both hormones and neurotransmitters.
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Affiliation(s)
- Takuya Nishimura
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Shin-ichi Harashima
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hu Yafang
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
- Center for Cancer and Immunology Research, Children’s National Medical Center, Washington, DC, USA
| | - Abner Louis Notkins
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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Nishimura T, Kubosaki A, Ito Y, Notkins AL. Disturbances in the secretion of neurotransmitters in IA-2/IA-2beta null mice: changes in behavior, learning and lifespan. Neuroscience 2009; 159:427-37. [PMID: 19361477 DOI: 10.1016/j.neuroscience.2009.01.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 12/24/2008] [Accepted: 01/07/2009] [Indexed: 11/15/2022]
Abstract
Islet-associated protein 2 (IA-2) and IA-2beta are major autoantigens in type 1 diabetes and transmembrane proteins in dense core secretory vesicles (DCV) of neuroendocrine cells. The deletion of these genes results in a decrease in insulin secretion. The present study was initiated to test the hypothesis that this deletion not only affects the secretion of insulin, but has a more global effect on neuroendocrine secretion that leads to disturbances in behavior and learning. Measurement of neurotransmitters showed that norepinephrine, dopamine and 5-HT were significantly decreased in the brain of double knockout (DKO) mice (P<0.05 to <0.001). In tests evaluating anxiety-like behavior and conditioned-learning, the DKO mice showed a highly significant increase in anxiety-like behavior (P<0.01 to <0.001) and impairment of conditioned learning (P<0.01) as compared to WT mice. The DKO mice also displayed an increase in spontaneous and induced seizures (P<0.01) and age-related death. Contrary to the generally held view that IA-2 and IA-2beta are expressed exclusively in DCV, subcellular fractionation studies revealed that IA-2beta, but not IA-2, co-purifies with fractions rich in synaptic vesicles (SV), and that the secretion of dopamine, GABA and glutamate from the synaptosomes of the DKO mice was significantly decreased as was the number of SV (P<0.01). Taken together, these findings show that IA-2beta is present in both DCV and SV, and that the deletion of IA-2/IA-2beta has a global effect on the secretion of neurotransmitters. The impairment of secretion leads to behavioral and learning disturbances, seizures and reduced lifespan.
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Affiliation(s)
- T Nishimura
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4322, USA
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Kim SM, Power A, Brown TM, Constance CM, Coon SL, Nishimura T, Hirai H, Cai T, Eisner C, Weaver DR, Piggins HD, Klein DC, Schnermann J, Notkins AL. Deletion of the secretory vesicle proteins IA-2 and IA-2beta disrupts circadian rhythms of cardiovascular and physical activity. FASEB J 2009; 23:3226-32. [PMID: 19433624 DOI: 10.1096/fj.09-132019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Targeted deletion of IA-2 and IA-2beta, major autoantigens in type 1 diabetes and transmembrane secretory vesicle proteins, results in impaired secretion of hormones and neurotransmitters. In the present study, we evaluated the effect of these deletions on daily rhythms in blood pressure, heart rate, core body temperature, and spontaneous physical and neuronal activity. We found that deletion of both IA-2 and IA-2beta profoundly disrupts the usual diurnal variation of each of these parameters, whereas the deletion of either IA-2 or IA-2beta alone did not produce a major change. In situ hybridization revealed that IA-2 and IA-2beta transcripts are highly but nonrhythmically expressed in the suprachiasmatic nuclei, the site of the brain's master circadian oscillator. Electrophysiological studies on tissue slices from the suprachiasmatic nuclei showed that disruption of both IA-2 and IA-2beta results in significant alterations in neuronal firing. From these studies, we concluded that deletion of IA-2 and IA-2beta, structural proteins of secretory vesicles and modulators of neuroendocrine secretion, has a profound effect on the circadian system.
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Affiliation(s)
- Soo Mi Kim
- Kidney Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Hu Y, Nishimura T, Zhang A, Notkins AL. Comment on: Torii et al. (2009) Gene silencing of phogrin unveils its essential role in glucose-responsive pancreatic beta-cell growth. Diabetes 58:682-692. Diabetes 2009; 58:e8. [PMID: 19401431 DOI: 10.2337/db09-0168] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Loss of the transcriptional repressor PAG-3/Gfi-1 results in enhanced neurosecretion that is dependent on the dense-core vesicle membrane protein IDA-1/IA-2. PLoS Genet 2009; 5:e1000447. [PMID: 19343207 PMCID: PMC2657203 DOI: 10.1371/journal.pgen.1000447] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Accepted: 03/06/2009] [Indexed: 01/09/2023] Open
Abstract
It is generally accepted that neuroendocrine cells regulate dense core vesicle (DCV) biogenesis and cargo packaging in response to secretory demands, although the molecular mechanisms of this process are poorly understood. One factor that has previously been implicated in DCV regulation is IA-2, a catalytically inactive protein phosphatase present in DCV membranes. Our ability to directly visualize a functional, GFP-tagged version of an IA-2 homolog in live Caenorhabditis elegans animals has allowed us to capitalize on the genetics of the system to screen for mutations that disrupt DCV regulation. We found that loss of activity in the transcription factor PAG-3/Gfi-1, which functions as a repressor in many systems, results in a dramatic up-regulation of IDA-1/IA-2 and other DCV proteins. The up-regulation of DCV components was accompanied by an increase in presynaptic DCV numbers and resulted in phenotypes consistent with increased neuroendocrine secretion. Double mutant combinations revealed that these PAG-3 mutant phenotypes were dependent on wild type IDA-1 function. Our results support a model in which IDA-1/IA-2 is a critical element in DCV regulation and reveal a novel genetic link to PAG-3-mediated transcriptional regulation. To our knowledge, this is the first mutation identified that results in increased neurosecretion, a phenotype that has clinical implications for DCV-mediated secretory disorders. Within secretory cells, hormones are packaged into vesicles (called DCVs) that are released upon stimulation. The number of DCVs is regulated to meet the secretory demands of the cell by a mechanism that is poorly understood, although a protein in the membrane of DCVs, called IA-2, is thought to play a role. A genetic screen in the nematode C. elegans is used, here, to find mutations that mis-regulate the corresponding worm protein called IDA-1. Capitalizing on the simple neuroanatomy of the nematode and its transparency, we visualize IDA-1 protein levels directly in the animal using a fluorescent tag. We find that mutations in the transcription factor PAG-3/Gfi-1 result in elevated levels of IDA-1 protein, increased numbers of presynaptic DCVs, and behaviors consistent with increased neurosecretion. Our results demonstrate that IDA-1/IA-2 protein levels correlate with the biogenesis, utilization, or stability of DCVs. We propose that PAG-3 normally down regulates the production of IDA-1, thus serving as part of the mechanism underlying DCV regulation. This is the first reported mutation that increases DCV numbers and secretion, offering insight into DCV homeostasis and a potential therapeutic target for diseases that would benefit from a boost in neuroendocrine secretion.
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Wuttke M, Papewalis C, Jacobs B, Schott M. Identifying tumor antigens in endocrine malignancies. Trends Endocrinol Metab 2009; 20:122-9. [PMID: 19269848 DOI: 10.1016/j.tem.2008.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 11/25/2008] [Accepted: 12/02/2008] [Indexed: 11/27/2022]
Abstract
Tumor antigens are surface molecules that are mostly cancer specific, often overexpressed and recognized by the immune system. Therefore, identifying tumor antigens is of key importance for developing new immunotherapies for incurable cancers. For endocrine malignancies, several different tumor-associated antigens have been described, including polypeptide hormones and/or vesicle-associated antigens in Th1-mediated autoimmune diseases. Other antigens have been identified by screening tumor DNA libraries. Furthermore, vaccination studies in humans and animal models have revealed a tumor-antigen-specific immunity and clinical responses with reduced tumor size. Here, we provide an overview of the recent progress achieved in identifying tumor antigens and predict how this knowledge can be used in the future for developing anti-tumor vaccinations.
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Affiliation(s)
- Margret Wuttke
- Endocrine Cancer Center, Department of Endocrinology, Diabetology and Rheumatology, University Hospital Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany.
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Torii S, Saito N, Kawano A, Hou N, Ueki K, Kulkarni RN, Takeuchi T. Gene silencing of phogrin unveils its essential role in glucose-responsive pancreatic beta-cell growth. Diabetes 2009; 58:682-92. [PMID: 19073770 PMCID: PMC2646067 DOI: 10.2337/db08-0970] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Phogrin and IA-2, autoantigens in insulin-dependent diabetes, have been shown to be involved in insulin secretion in pancreatic beta-cells; however, implications at a molecular level are confusing from experiment to experiment. We analyzed biological functions of phogrin in beta-cells by an RNA interference technique. RESEARCH DESIGN AND METHODS Adenovirus-mediated expression of short hairpin RNA specific for phogrin (shPhogrin) was conducted using cultured beta-cell lines and mouse islets. Both glucose-stimulated insulin secretion and cell proliferation rate were determined in the phogrin-knockdown cells. Furthermore, protein expression was profiled in these cells. To see the binding partner of phogrin in beta-cells, coimmunoprecipitation analysis was carried out. RESULTS Adenoviral expression of shPhogrin efficiently decreased its endogenous expression in pancreatic beta-cells. Silencing of phogrin in beta-cells abrogated the glucose-mediated mitogenic effect, which was accompanied by a reduction in the level of insulin receptor substrate 2 (IRS2) protein, without any changes in insulin secretion. Phogrin formed a complex with insulin receptor at the plasma membrane, and their interaction was promoted by high-glucose stimulation that in turn led to stabilization of IRS2 protein. Corroboratively, phogrin knockdown had no additional effect on the proliferation of beta-cell line derived from the insulin receptor-knockout mouse. CONCLUSIONS Phogrin is involved in beta-cell growth via regulating stability of IRS2 protein by the molecular interaction with insulin receptor. We propose that phogrin and IA-2 function as an essential regulator of autocrine insulin action in pancreatic beta-cells.
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Affiliation(s)
- Seiji Torii
- Secretion Biology Lab, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
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Torii S. Expression and function of IA-2 family proteins, unique neuroendocrine-specific protein-tyrosine phosphatases. Endocr J 2009; 56:639-48. [PMID: 19550073 DOI: 10.1507/endocrj.k09e-157] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
IA-2 (also known as islet cell antigen ICA-512) and IA-2 beta (also known as phogrin, phosphatase homologue in granules of insulinoma) are major autoantigens in insulin-dependent diabetes mellitus (IDDM). Autoantibodies against both proteins are expressed years before clinical onset, and they become predictive markers for high-risk subjects. However, the role of these genes in the IDDM pathogenesis has been reported fairly negative by recent studies. IA-2 and IA-2 beta are type I transmembrane proteins that possess one inactive protein-tyrosine phosphatase (PTP) domain in the cytoplasmic region, and act as one of the constituents of regulated secretory pathways in various neuroendocrine cell types including pancreatic beta-cells. Existence of IA-2 homologues in different species suggests a fundamental role in neuroendocrine function. Studies of knockout animals have shown their involvement in maintaining hormone content, however, their specific steps in the secretory pathway IA-2 functions as well as their molecular mechanisms in the hormone content regulation are still unknown. More recent studies have suggested a novel function showing that they contribute to pancreatic beta-cell growth. This review attempts to show the possible biological functions of IA-2 family, focusing on their expression and localization in the neuroendocrine cells.
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Affiliation(s)
- Seiji Torii
- Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan.
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Kim SM, Theilig F, Qin Y, Cai T, Mizel D, Faulhaber-Walter R, Hirai H, Bachmann S, Briggs JP, Notkins AL, Schnermann J. Dense-core vesicle proteins IA-2 and IA-2{beta} affect renin synthesis and secretion through the {beta}-adrenergic pathway. Am J Physiol Renal Physiol 2008; 296:F382-9. [PMID: 19019914 DOI: 10.1152/ajprenal.90543.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
IA-2 and IA-2beta, major autoantigens in type 1 diabetes, are transmembrane proteins in dense-core vesicles, and their expression influences the secretion of hormones and neurotransmitters. The present experiments were performed to examine whether IA-2 and IA-2beta modulate the release of renin from dense-core vesicles of juxtaglomerular granular cells in the kidney. Plasma renin concentration (PRC; ng angiotensin I.ml(-1).h(-1)) was significantly reduced in mice with null mutations in IA-2, IA-2beta, or both IA-2 and IA-2beta compared with wild-type mice (876 +/- 113, 962 +/- 130, and 596 +/- 82 vs. 1,367 +/- 93; P < 0.01, P < 0.02, and P < 0.001). Renin mRNA levels were reduced to 26.4 +/- 5.1, 39 +/- 5.4, and 35.3 +/- 5.5% of wild-type in IA-2-/-, IA-2beta-/-, and IA-2/IA-2beta-/- mice. Plasma aldosterone levels were not significantly different among genotypes. The regulation of PRC by furosemide and salt intake, and of aldosterone by salt intake, was maintained in all genotypes. IA-2 and IA-2beta expression did not colocalize with renin but showed overlapping immunoreactivity with tyrosine hydroxylase. While propranolol reduced PRC in wild-type mice, it had no effect on PRC in IA-2/ IA-2beta-/- mice. Renal tyrosine hydroxylase mRNA and immunoreactivity were reduced in IA-2/IA-2beta-/- mice as was the urinary excretion of catecholamines. We conclude that IA-2 and IA-2beta are required to maintain normal levels of renin expression and renin release, most likely by permitting normal rates of catecholamine release from sympathetic nerve terminals.
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Affiliation(s)
- Soo Mi Kim
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bldg. 10, Rm. 4D51, 10 Center Dr.-MSC 1370, Bethesda, MD 20892, USA
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41
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Trajkovski M, Mziaut H, Schubert S, Kalaidzidis Y, Altkrüger A, Solimena M. Regulation of insulin granule turnover in pancreatic beta-cells by cleaved ICA512. J Biol Chem 2008; 283:33719-29. [PMID: 18824546 DOI: 10.1074/jbc.m804928200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Insulin maintains homeostasis of glucose by promoting its uptake into cells from the blood. Hyperglycemia triggers secretion of insulin from pancreatic beta-cells. This process is mediated by secretory granule exocytosis. However, how beta-cells keep granule stores relatively constant is still unknown. ICA512 is an intrinsic granule membrane protein, whose cytosolic domain binds beta2-syntrophin, an F-actin-associated protein, and is cleaved upon granule exocytosis. The resulting cleaved cytosolic fragment, ICA512-CCF, reaches the nucleus and up-regulates the transcription of granule genes, including insulin and ICA512. Here, we show that ICA512-CCF also dimerizes with intact ICA512 on granules, thereby displacing it from beta2-syntrophin. This leads to increased granule mobility and insulin release. Based on these findings, we propose a model whereby the generation of ICA512-CCF first amplifies insulin secretion. The ensuing reduction of granule stores would then increase the probability of newly generated ICA512-CCF to reach the nucleus and enhance granule biogenesis, thus allowing beta-cells to constantly adjust production of granules to their storage size and consumption. Pharmacological modulation of these feedback loops may alleviate deficient insulin release in diabetes.
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Affiliation(s)
- Mirko Trajkovski
- Laboratory of Experimental Diabetology, School of Medicine, Dresden University of Technology, Dresden 01307, Germany
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Park JJ, Koshimizu H, Loh YP. Biogenesis and Transport of Secretory Granules to Release Site in Neuroendocrine Cells. J Mol Neurosci 2008; 37:151-9. [DOI: 10.1007/s12031-008-9098-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 05/06/2008] [Indexed: 11/29/2022]
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Kim J, Bang H, Ko S, Jung I, Hong H, Kim-Ha J. Drosophila ia2 modulates secretion of insulin-like peptide. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:180-4. [PMID: 18634898 DOI: 10.1016/j.cbpa.2008.06.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 06/19/2008] [Accepted: 06/19/2008] [Indexed: 11/26/2022]
Abstract
Islet antigen-2 (IA-2) is a major autoantigen in type I diabetes. To throw light on the function of IA-2 we examined the role of ia2, a Drosophila homologue, during Drosophila development. In situ hybridization showed that ia2 was expressed in the central nervous system and midgut region. The neuronal expression pattern of ia2 was very similar to that of IA-2 in mammals. Disruption of gut-specific ia2 expression by double stranded RNA interference (dsRNAi) resulted in defects in gut development, and this phenotype was rescued by overexpression of hexokinase. Until now the roles of IA-2 and hexokinase in insulin signaling have been described separately but we found that ia2 modulated the expression of both insulin and hexokinase. Moreover this modulation seems to be important for gut development during metamorphosis. As the pancreas develops from the gut during vertebrate development, our results suggest a possible role of IA-2 in insulin and hexokinase regulation.
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Affiliation(s)
- Jihyun Kim
- Department of Molecular Biology, Sejong University, 98 Kunja-dong, Kwangjin ku 143-747, Seoul, South Korea
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Speidel D, Salehi A, Obermueller S, Lundquist I, Brose N, Renström E, Rorsman P. CAPS1 and CAPS2 regulate stability and recruitment of insulin granules in mouse pancreatic beta cells. Cell Metab 2008; 7:57-67. [PMID: 18177725 DOI: 10.1016/j.cmet.2007.11.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 10/15/2007] [Accepted: 11/19/2007] [Indexed: 11/25/2022]
Abstract
CAPS1 and CAPS2 regulate dense-core vesicle release of transmitters and hormones in neuroendocrine cells, but their precise roles in the secretory process remain enigmatic. Here we show that CAPS2(-/-) and CAPS1(+/-);CAPS2(-/-) mice, despite having increased insulin sensitivity, are glucose intolerant and that this effect is attributable to a marked reduction of glucose-induced insulin secretion. This correlates with diminished Ca(2+)-dependent exocytosis, a reduction in the size of the morphologically docked pool, a decrease in the readily releasable pool of secretory vesicles, slowed granule priming, and suppression of second-phase (but not first-phase) insulin secretion. In beta cells of CAPS1(+/-);CAPS2(-/-) mice, the lowered insulin content and granule numbers were associated with an increase in lysosome numbers and lysosomal enzyme activity. We conclude that although CAPS proteins are not required for Ca(2+)-dependent exocytosis to proceed, they exert a modulatory effect on insulin granule priming, exocytosis, and stability.
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Affiliation(s)
- Dina Speidel
- Department of Clinical Sciences Malmö, Lund University, UMAS, Malmö, Sweden.
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Nakayama M, Beilke JN, Jasinski JM, Kobayashi M, Miao D, Li M, Coulombe MG, Liu E, Elliott JF, Gill RG, Eisenbarth GS. Priming and effector dependence on insulin B:9-23 peptide in NOD islet autoimmunity. J Clin Invest 2007; 117:1835-43. [PMID: 17607359 PMCID: PMC1904318 DOI: 10.1172/jci31368] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Accepted: 03/20/2007] [Indexed: 11/17/2022] Open
Abstract
NOD mice with knockout of both native insulin genes and a mutated proinsulin transgene, alanine at position B16 in preproinsulin (B16:A-dKO mice), do not develop diabetes. Transplantation of NOD islets, but not bone marrow, expressing native insulin sequences (tyrosine at position B16) into B16:A-dKO mice rapidly restored development of insulin autoantibodies (IAAs) and insulitis, despite the recipients' pancreatic islets lacking native insulin sequences. Splenocytes from B16:A-dKO mice that received native insulin-positive islets induced diabetes when transferred into wild-type NOD/SCID or B16:A-dKO NOD/SCID mice. Splenocytes from mice immunized with native insulin B chain amino acids 9-23 (insulin B:9-23) peptide in CFA induced rapid diabetes upon transfer only in recipients expressing the native insulin B:9-23 sequence in their pancreata. Additionally, CD4(+) T cells from B16:A-dKO mice immunized with native insulin B:9-23 peptide promoted IAAs in NOD/SCID mice. These results indicate that the provision of native insulin B:9-23 sequences is sufficient to prime anti-insulin autoimmunity and that subsequent transfer of diabetes following peptide immunization requires native insulin B:9-23 expression in islets. Our findings demonstrate dependence on B16 alanine versus tyrosine of insulin B:9-23 for both the initial priming and the effector phase of NOD anti-islet autoimmunity.
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Affiliation(s)
- Maki Nakayama
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Joshua N. Beilke
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jean M. Jasinski
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Masakazu Kobayashi
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Dongmei Miao
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Marcella Li
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Marilyne G. Coulombe
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Edwin Liu
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - John F. Elliott
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Ronald G. Gill
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - George S. Eisenbarth
- Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center (UCHSC), Aurora, Colorado, USA.
Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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Harashima SI, Harashima C, Nishimura T, Hu Y, Notkins AL. Overexpression of the autoantigen IA-2 puts beta cells into a pre-apoptotic state: autoantigen-induced, but non-autoimmune-mediated, tissue destruction. Clin Exp Immunol 2007; 150:49-60. [PMID: 17725654 PMCID: PMC2219291 DOI: 10.1111/j.1365-2249.2007.03455.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
IA-2 is a major autoantigen in type 1 diabetes and autoantibodies to it have become important diagnostic and predictive markers. IA-2 also is an intrinsic transmembrane component of dense core secretory vesicles and knock-out studies showed that IA-2 is a regulator of insulin secretion. Here we show that overexpression of IA-2 puts mouse insulinoma MIN-6 beta cells into a pre-apoptotic state and that exposure to high glucose results in G2/M arrest and apoptosis. Molecular study revealed a decrease in phosphoinositide-dependent kinase (PDK)-1 and Akt/protein kinase B (PKB) phosphorylation. Treatment of IA-2-transfected cells with IA-2 siRNA prevented both G2/M arrest and apoptosis and increased Akt/PKB phosphorylation. A search for IA-2 interacting proteins revealed that IA-2 interacts with sorting nexin (SNX)19 and that SNX19, but not IA-2, inhibits the conversion of PtdIns(4,5)P2 to PtdIns(3,4,5)P3 and thereby suppresses the phosphorylation of proteins in the Akt signalling pathway resulting in apoptosis. We conclude that IA-2 acts through SNX19 to initiate the pre-apoptotic state. Our findings point to the possibility that in autoimmune diseases, tissue destruction may be autoantigen-induced, but not necessarily immunologically mediated.
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Affiliation(s)
- S-I Harashima
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892, USA
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Kuwahata M, Tomoe Y, Harada N, Amano S, Segawa H, Tatsumi S, Ito M, Oka T, Miyamoto KI. Characterization of the molecular mechanisms involved in the increased insulin secretion in rats with acute liver failure. Biochim Biophys Acta Mol Basis Dis 2006; 1772:60-5. [PMID: 17097861 DOI: 10.1016/j.bbadis.2006.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2006] [Revised: 09/15/2006] [Accepted: 10/02/2006] [Indexed: 12/24/2022]
Abstract
To investigate the mechanism of hyperinsulinaemia in rats with acute liver failure induced by the administration of d-galactosamine (GalN), we focused on the role of polyprimidine tract-binding protein (PTB) in islet insulin synthesis. Recent reports indicate that PTB binds and stabilizes mRNA encoding insulin and insulin secretory granule proteins, including islet cell autoantigen 512 (ICA512), prohormone convertase 1/3 (PC1/3), and PC2. In the present study, glucose-stimulated insulin secretion was significantly increased in GalN-treated rats compared to controls. Levels of mRNA encoding insulin 1, ICA512, and PC1/3 were increased in the pancreatic islets of GalN-treated rats. This mRNA level elevation was not prevented by pretreatment with actinomycin D. When the PTB-binding site in insulin 1 mRNA was incubated with the islet cytosolic fraction, the RNA-protein complex level was increased in the cytosolic fraction obtained from GalN-treated rats compared to the level in control rats. The cytosolic fraction obtained from pancreatic islets obtained from GalN-treated rats had an increased PTB level compared to the levels obtained from the pancreatic islets of control rats. These findings suggest that, in rats with acute liver failure, cytosolic PTB binds and stabilizes mRNA encoding insulin and its secretory granule proteins.
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Affiliation(s)
- Masashi Kuwahata
- Department of Molecular Nutrition, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima 770-8503, Japan.
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48
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Kim T, Gondré-Lewis MC, Arnaoutova I, Loh YP. Dense-core secretory granule biogenesis. Physiology (Bethesda) 2006; 21:124-33. [PMID: 16565478 DOI: 10.1152/physiol.00043.2005] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The dense-core secretory granule is a key organelle for secretion of hormones and neuropeptides in endocrine cells and neurons, in response to stimulation. Cholesterol and granins are critical for the assembly of these organelles at the trans-Golgi network, and their biogenesis is regulated quantitatively by posttranscriptional and posttranslational mechanisms.
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Affiliation(s)
- Taeyoon Kim
- Section on Cellular Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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49
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Borgonovo B, Ouwendijk J, Solimena M. Biogenesis of secretory granules. Curr Opin Cell Biol 2006; 18:365-70. [PMID: 16806882 DOI: 10.1016/j.ceb.2006.06.010] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Accepted: 06/08/2006] [Indexed: 11/22/2022]
Abstract
Secretory granules of neuroendocrine cells store and release peptide hormones and neuropeptides in response to various stimuli. Generation of granules from the Golgi complex involves the aggregation of cargo proteins and their sorting from non-regulated secretory molecules. Recent findings on knockout mice lacking individual granule constituents have challenged the hypothesis that an 'essential' protein for the assembly of these organelles exists, while studies on polypyrimidine tract-binding protein and ICA512/IA-2 have provided insight into the mechanisms for adjusting granule production in relation to stimulation and secretory activity.
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Affiliation(s)
- Barbara Borgonovo
- Experimental Diabetology, Carl Gustav Carus Medical School, Dresden University of Technology, Fetscherstrasse 74, 01307 Dresden, Germany
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50
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Mziaut H, Trajkovski M, Kersting S, Ehninger A, Altkrüger A, Lemaitre RP, Schmidt D, Saeger HD, Lee MS, Drechsel DN, Müller S, Solimena M. Synergy of glucose and growth hormone signalling in islet cells through ICA512 and STAT5. Nat Cell Biol 2006; 8:435-45. [PMID: 16622421 DOI: 10.1038/ncb1395] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Accepted: 03/27/2006] [Indexed: 01/08/2023]
Abstract
Nutrients and growth hormones promote insulin production and the proliferation of pancreatic beta-cells. An imbalance between ever-increasing metabolic demands and insulin output causes diabetes. Recent evidence indicates that beta-cells enhance insulin gene expression depending on their secretory activity. This signalling pathway involves a catalytically inactive receptor tyrosine phosphatase, ICA512, whose cytoplasmic tail is cleaved on glucose-stimulated exocytosis of insulin secretory granules and then moves into the nucleus, where it upregulates insulin transcription. Here, we show that the cleaved cytosolic fragment of ICA512 enhances the transcription of secretory granule genes (including its own gene) by binding to tyrosine phosphorylated signal transducers and activators of transcription (STAT) 5 and preventing its dephosphorylation. Sumoylation of ICA512 by the E3 SUMO ligase PIASy, in turn, may reverse this process by decreasing the binding of ICA512 to STAT5. These findings illustrate how the exocytosis of secretory granules, through a retrograde pathway that sustains STAT activity, converges with growth hormone signalling to induce adaptive changes in beta-cells in response to metabolic demands.
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Affiliation(s)
- Hassan Mziaut
- Experimental Diabetology, School of Medicine, Dresden University of Technology, Dresden 01307, Germany
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