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Boyer CK, Blom SE, Machado AE, Rohli KE, Maxson ME, Stephens SB. Loss of the Golgi-localized v-ATPase subunit does not alter insulin granule formation or pancreatic islet β-cell function. Am J Physiol Endocrinol Metab 2024; 326:E245-E257. [PMID: 38265287 PMCID: PMC11193524 DOI: 10.1152/ajpendo.00342.2023] [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: 10/18/2023] [Revised: 01/11/2024] [Accepted: 01/11/2024] [Indexed: 01/25/2024]
Abstract
Delayed Golgi export of proinsulin has recently been identified as an underlying mechanism leading to insulin granule loss and β-cell secretory defects in type 2 diabetes (T2D). Because acidification of the Golgi lumen is critical for proinsulin sorting and delivery into the budding secretory granule, we reasoned that dysregulation of Golgi pH may contribute to proinsulin trafficking defects. In this report, we examined pH regulation of the Golgi and identified a partial alkalinization of the Golgi lumen in a diabetes model. To further explore this, we generated a β-cell specific knockout (KO) of the v0a2 subunit of the v-ATPase pump, which anchors the v-ATPase to the Golgi membrane. Although loss of v0a2 partially neutralized Golgi pH and was accompanied by distension of the Golgi cisternae, proinsulin export from the Golgi and insulin granule formation were not affected. Furthermore, β-cell function was well preserved. β-cell v0a2 KO mice exhibited normal glucose tolerance in both sexes, no genotypic difference to diet-induced obesity, and normal insulin secretory responses. Collectively, our data demonstrate the v0a2 subunit contributes to β-cell Golgi pH regulation but suggest that additional disturbances to Golgi structure and function contribute to proinsulin trafficking defects in diabetes.NEW & NOTEWORTHY Delayed proinsulin export from the Golgi in diabetic β-cells contributes to decreased insulin granule formation, but the underlying mechanisms are not clear. Here, we explored if dysregulation of Golgi pH can alter Golgi function using β-cell specific knockout (KO) of the Golgi-localized subunit of the v-ATPase, v0a2. We show that partial alkalinization of the Golgi dilates the cisternae, but does not affect proinsulin export, insulin granule formation, insulin secretion, or glucose homeostasis.
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Affiliation(s)
- Cierra K Boyer
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, Iowa, United States
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, United States
| | - Sandra E Blom
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, United States
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Ashleigh E Machado
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, United States
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Kristen E Rohli
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, United States
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, Iowa, United States
| | - Michelle E Maxson
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Samuel B Stephens
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, United States
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, Iowa, United States
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2
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Campelo F, Tian M, von Blume J. Rediscovering the intricacies of secretory granule biogenesis. Curr Opin Cell Biol 2023; 85:102231. [PMID: 37657367 DOI: 10.1016/j.ceb.2023.102231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 09/03/2023]
Abstract
Regulated secretion, an essential cellular process, relies on secretory granules (SGs) for the controlled release of a diverse range of cargo molecules, including proteins, peptides, hormones, enzymes, and neurotransmitters. SG biogenesis encompasses cargo selection, sorting, packaging, and trafficking, with the trans-Golgi Network (TGN) playing a central role. Research in the last three decades has revealed significant components required for SG biogenesis; however, no cargo receptor transferring granule cargo from the TGN to immature SGs (ISGs) has yet been identified. Consequently, recent research has devoted significant attention to studying receptor-independent cargo sorting mechanisms, shedding new light on the complexities of regulated secretion. Understanding the underlying molecular and biophysical mechanisms behind cargo sorting into ISGs holds great promise for advancing our knowledge of cellular communication and disease mechanisms.
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Affiliation(s)
- Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels, Barcelona, Spain
| | - Meng Tian
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Julia von Blume
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
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Štepihar D, Florke Gee RR, Hoyos Sanchez MC, Fon Tacer K. Cell-specific secretory granule sorting mechanisms: the role of MAGEL2 and retromer in hypothalamic regulated secretion. Front Cell Dev Biol 2023; 11:1243038. [PMID: 37799273 PMCID: PMC10548473 DOI: 10.3389/fcell.2023.1243038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/31/2023] [Indexed: 10/07/2023] Open
Abstract
Intracellular protein trafficking and sorting are extremely arduous in endocrine and neuroendocrine cells, which synthesize and secrete on-demand substantial quantities of proteins. To ensure that neuroendocrine secretion operates correctly, each step in the secretion pathways is tightly regulated and coordinated both spatially and temporally. At the trans-Golgi network (TGN), intrinsic structural features of proteins and several sorting mechanisms and distinct signals direct newly synthesized proteins into proper membrane vesicles that enter either constitutive or regulated secretion pathways. Furthermore, this anterograde transport is counterbalanced by retrograde transport, which not only maintains membrane homeostasis but also recycles various proteins that function in the sorting of secretory cargo, formation of transport intermediates, or retrieval of resident proteins of secretory organelles. The retromer complex recycles proteins from the endocytic pathway back to the plasma membrane or TGN and was recently identified as a critical player in regulated secretion in the hypothalamus. Furthermore, melanoma antigen protein L2 (MAGEL2) was discovered to act as a tissue-specific regulator of the retromer-dependent endosomal protein recycling pathway and, by doing so, ensures proper secretory granule formation and maturation. MAGEL2 is a mammalian-specific and maternally imprinted gene implicated in Prader-Willi and Schaaf-Yang neurodevelopmental syndromes. In this review, we will briefly discuss the current understanding of the regulated secretion pathway, encompassing anterograde and retrograde traffic. Although our understanding of the retrograde trafficking and sorting in regulated secretion is not yet complete, we will review recent insights into the molecular role of MAGEL2 in hypothalamic neuroendocrine secretion and how its dysregulation contributes to the symptoms of Prader-Willi and Schaaf-Yang patients. Given that the activation of many secreted proteins occurs after they enter secretory granules, modulation of the sorting efficiency in a tissue-specific manner may represent an evolutionary adaptation to environmental cues.
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Affiliation(s)
- Denis Štepihar
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
- Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Rebecca R. Florke Gee
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
| | - Maria Camila Hoyos Sanchez
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
| | - Klementina Fon Tacer
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States
- Texas Center for Comparative Cancer Research (TC3R), Amarillo, TX, United States
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4
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Alghalayini A, Hossain KR, Moghaddasi S, Turkewitz DR, D’Amario C, Wallach M, Valenzuela SM. In Vitro Enzymatic Studies Reveal pH and Temperature Sensitive Properties of the CLIC Proteins. Biomolecules 2023; 13:1394. [PMID: 37759794 PMCID: PMC10526857 DOI: 10.3390/biom13091394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 09/09/2023] [Accepted: 09/10/2023] [Indexed: 09/29/2023] Open
Abstract
Chloride intracellular ion channel (CLIC) proteins exist as both soluble and integral membrane proteins, with CLIC1 capable of shifting between two distinct structural conformations. New evidence has emerged indicating that members of the CLIC family act as moonlighting proteins, referring to the ability of a single protein to carry out multiple functions. In addition to their ion channel activity, CLIC family members possess oxidoreductase enzymatic activity and share significant structural and sequence homology, along with varying overlaps in their tissue distribution and cellular localization. In this study, the 2-hydroxyethyl disulfide (HEDS) assay system was used to characterize kinetic properties, as well as the temperature and pH profiles of three CLIC protein family members (CLIC1, CLIC3, CLIC4). We also assessed the effects of the drugs rapamycin and amphotericin B, on the three CLIC proteins' enzymatic activity in the HEDS assay. Our results demonstrate CLIC1 to be highly heat-sensitive, with optimal enzymatic activity observed at neutral pH7 and at a temperature of 37 °C, while CLIC3 had higher oxidoreductase activity in more acidic pH5 and was found to be relatively heat stable. CLIC4, like CLIC1, was temperature sensitive with optimal enzymatic activity observed at 37 °C; however, it showed optimal activity in more alkaline conditions of pH8. Our current study demonstrates individual differences in the enzymatic activity between the three CLIC proteins, suggesting each CLIC protein is likely regulated in discrete ways, involving changes in the subcellular milieu and microenvironment.
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Affiliation(s)
- Amani Alghalayini
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
- ARC Research Hub for Integrated Device for End-User Analysis at Low-Levels (IDEAL), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Khondker Rufaka Hossain
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
- ARC Research Hub for Integrated Device for End-User Analysis at Low-Levels (IDEAL), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Saba Moghaddasi
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Daniel R. Turkewitz
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Claudia D’Amario
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Michael Wallach
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Stella M. Valenzuela
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
- ARC Research Hub for Integrated Device for End-User Analysis at Low-Levels (IDEAL), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
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Mobayen G, Smith K, Ediriwickrema K, Starke RD, Solomonidis EG, Laffan MA, Randi AM, McKinnon TAJ. von Willebrand factor binds to angiopoietin-2 within endothelial cells and after release from Weibel-Palade bodies. J Thromb Haemost 2023; 21:1802-1812. [PMID: 37011710 DOI: 10.1016/j.jtha.2023.03.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 03/20/2023] [Accepted: 03/22/2023] [Indexed: 04/04/2023]
Abstract
BACKGROUND The von Willebrand factor (VWF) is a multimeric plasma glycoprotein essential for hemostasis, inflammation, and angiogenesis. The majority of VWF is synthesized by endothelial cells (ECs) and stored in Weibel-Palade bodies (WPB). Among the range of proteins shown to co-localize to WPB is angiopoietin-2 (Angpt-2), a ligand of the receptor tyrosine kinase Tie-2. We have previously shown that VWF itself regulates angiogenesis, raising the hypothesis that some of the angiogenic activity of VWF may be mediated by its interaction with Angpt-2. METHODS Static-binding assays were used to probe the interaction between Angpt-2 and VWF. Binding in media from cultured human umbilical vein ECs s and in plasma was determined by immunoprecipitation experiments. Immunofluorescence was used to detect the presence of Angpt-2 on VWF strings, and flow assays were used to investigate the effect on VWF function. RESULTS Static-binding assays revealed that Angpt-2 bound to VWF with high affinity (KD,app ∼3 nM) in a pH and calcium-dependent manner. The interaction was localized to the VWF A1 domain. Co-immunoprecipitation experiments demonstrated that the complex persisted following stimulated secretion from ECs and was present in plasma. Angpt-2 was also visible on VWF strings on stimulated ECs. The VWF-Angpt-2 complex did not inhibit the binding of Angpt-2 to Tie-2 and did not significantly interfere with VWF-platelet capture. CONCLUSIONS Together, these data demonstrate a direct binding interaction between Angpt-2 and VWF that persists after secretion. VWF may act to localize Angpt-2; further work is required to establish the functional consequences of this interaction.
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Affiliation(s)
- Golzar Mobayen
- Department of Immunology and Inflammation, Centre for Haematology, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Koval Smith
- National Heart and Lung Institute (NHLI) Cardiovascular Sciences, Unit Imperial College Academic Health Science Centre, Hammersmith Hospital, London, United Kingdom
| | - Kushani Ediriwickrema
- Department of Immunology and Inflammation, Centre for Haematology, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Richard D Starke
- National Heart and Lung Institute (NHLI) Cardiovascular Sciences, Unit Imperial College Academic Health Science Centre, Hammersmith Hospital, London, United Kingdom
| | - Emmanouil Georgios Solomonidis
- Department of Immunology and Inflammation, Centre for Haematology, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Michael A Laffan
- Department of Immunology and Inflammation, Centre for Haematology, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom
| | - Anna M Randi
- National Heart and Lung Institute (NHLI) Cardiovascular Sciences, Unit Imperial College Academic Health Science Centre, Hammersmith Hospital, London, United Kingdom
| | - Thomas A J McKinnon
- Department of Immunology and Inflammation, Centre for Haematology, Imperial College London, Hammersmith Hospital Campus, London, United Kingdom.
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6
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Kwok ACM, Chan WS, Wong JTY. Dinoflagellate Amphiesmal Dynamics: Cell Wall Deposition with Ecdysis and Cellular Growth. Mar Drugs 2023; 21:md21020070. [PMID: 36827111 PMCID: PMC9959387 DOI: 10.3390/md21020070] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/11/2023] [Accepted: 01/17/2023] [Indexed: 01/24/2023] Open
Abstract
Dinoflagellates are a major aquatic protist group with amphiesma, multiple cortical membranous "cell wall" layers that contain large circum-cortical alveolar sacs (AVs). AVs undergo extensive remodeling during cell- and life-cycle transitions, including ecdysal cysts (ECs) and resting cysts that are important in some harmful algal bloom initiation-termination. AVs are large cortical vesicular compartments, within which are elaborate cellulosic thecal plates (CTPs), in thecate species, and the pellicular layer (PL). AV-CTPs provide cellular mechanical protection and are targets of vesicular transport that are replaced during EC-swarmer cell transition, or with increased deposition during the cellular growth cycle. AV-PL exhibits dynamical-replacement with vesicular trafficking that are orchestrated with amphiesmal chlortetracycline-labeled Ca2+ stores signaling, integrating cellular growth with different modes of cell division cycle/progression. We reviewed the dynamics of amphiesma during different cell division cycle modes and life cycle stages, and its multifaceted regulations, focusing on the regulatory and functional readouts, including the coral-zooxanthellae interactions.
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7
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Parchure A, Tian M, Stalder D, Boyer CK, Bearrows SC, Rohli KE, Zhang J, Rivera-Molina F, Ramazanov BR, Mahata SK, Wang Y, Stephens SB, Gershlick DC, von Blume J. Liquid-liquid phase separation facilitates the biogenesis of secretory storage granules. J Cell Biol 2022; 221:e202206132. [PMID: 36173346 PMCID: PMC9526250 DOI: 10.1083/jcb.202206132] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 02/03/2023] Open
Abstract
Insulin is synthesized by pancreatic β-cells and stored into secretory granules (SGs). SGs fuse with the plasma membrane in response to a stimulus and deliver insulin to the bloodstream. The mechanism of how proinsulin and its processing enzymes are sorted and targeted from the trans-Golgi network (TGN) to SGs remains mysterious. No cargo receptor for proinsulin has been identified. Here, we show that chromogranin (CG) proteins undergo liquid-liquid phase separation (LLPS) at a mildly acidic pH in the lumen of the TGN, and recruit clients like proinsulin to the condensates. Client selectivity is sequence-independent but based on the concentration of the client molecules in the TGN. We propose that the TGN provides the milieu for converting CGs into a "cargo sponge" leading to partitioning of client molecules, thus facilitating receptor-independent client sorting. These findings provide a new receptor-independent sorting model in β-cells and many other cell types and therefore represent an innovation in the field of membrane trafficking.
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Affiliation(s)
- Anup Parchure
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Meng Tian
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Danièle Stalder
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Cierra K. Boyer
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
- Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA
| | - Shelby C. Bearrows
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
- Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA
| | - Kristen E. Rohli
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
- Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA
| | - Jianchao Zhang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI
- Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI
| | - Felix Rivera-Molina
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Bulat R. Ramazanov
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Sushil K. Mahata
- Department of Medicine, University of California San Diego, La Jolla, CA
- VA San Diego Healthcare System, San Diego, CA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI
- Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI
| | - Samuel B. Stephens
- Departments of Pharmacology and Neuroscience, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA
| | - David C. Gershlick
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Julia von Blume
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
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Griffith MB, Pearce CS, Heaslip AT. Dense granule biogenesis, secretion, and function in Toxoplasma gondii. J Eukaryot Microbiol 2022; 69:e12904. [PMID: 35302693 PMCID: PMC9482668 DOI: 10.1111/jeu.12904] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Toxoplasma gondii is an obligate intracellular parasite and the causative agent of Toxoplasmosis. A key to understanding and treating the disease lies with determining how the parasite can survive and replicate within cells of its host. Proteins released from specialized secretory vesicles, named the dense granules (DGs), have diverse functions that are critical for adapting the intracellular environment, and are thus key to survival and pathogenicity. In this review, we describe the current understanding and outstanding questions regarding dense granule biogenesis, trafficking, and regulation of secretion. In addition, we provide an overview of dense granule protein ("GRA") function upon secretion, with a focus on proteins that have recently been identified.
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Affiliation(s)
- Michael B Griffith
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Camille S Pearce
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Aoife T Heaslip
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
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9
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Cargo receptor Surf4 regulates endoplasmic reticulum export of proinsulin in pancreatic β-cells. Commun Biol 2022; 5:458. [PMID: 35562580 PMCID: PMC9106718 DOI: 10.1038/s42003-022-03417-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 04/26/2022] [Indexed: 11/08/2022] Open
Abstract
Insulin is an essential peptide hormone that maintains blood glucose levels. Although the mechanisms underlying insulin exocytosis have been investigated, the mechanism of proinsulin export from the endoplasmic reticulum (ER) remains unclear. Here, we demonstrated that Surf4, a cargo receptor homolog, regulates the ER export of proinsulin via its recruitment to ER exit sites (ERES). Under high-glucose conditions, Surf4 expression was upregulated, and Surf4 proteins mainly localized to the ER at a steady state and accumulated in the ERES, along with proinsulin in rat insulinoma INS-1 cells. Surf4-knockdown resulted in proinsulin retention in the ER and decreased the levels of mature insulin in secretory granules, thereby significantly reducing insulin secretion. Surf4 forms an oligomer and can physically interact with proinsulin and Sec12, essential for COPII vesicle formation. Our findings suggest that Surf4 interacts with proinsulin and delivers it into COPII vesicles for ER export in co-operation with Sec12 and COPII.
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10
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Xu H, Chang F, Jain S, Heller BA, Han X, Liu Y, Edwards RH. SNX5 targets a monoamine transporter to the TGN for assembly into dense core vesicles by AP-3. J Cell Biol 2022; 221:e202106083. [PMID: 35426896 PMCID: PMC9016777 DOI: 10.1083/jcb.202106083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/06/2021] [Accepted: 02/16/2022] [Indexed: 11/22/2022] Open
Abstract
The time course of signaling by peptide hormones, neural peptides, and other neuromodulators depends on their storage inside dense core vesicles (DCVs). Adaptor protein 3 (AP-3) assembles the membrane proteins that confer regulated release of DCVs and is thought to promote their trafficking from endosomes directly to maturing DCVs. We now find that regulated monoamine release from DCVs requires sorting nexin 5 (SNX5). Loss of SNX5 disrupts trafficking of the vesicular monoamine transporter (VMAT) to DCVs. The mechanism involves a role for SNX5 in retrograde transport of VMAT from endosomes to the TGN. However, this role for SNX5 conflicts with the proposed function of AP-3 in trafficking from endosomes directly to DCVs. We now identify a transient role for AP-3 at the TGN, where it associates with DCV cargo. Thus, retrograde transport from endosomes by SNX5 enables DCV assembly at the TGN by AP-3, resolving the apparent antagonism. A novel role for AP-3 at the TGN has implications for other organelles that also depend on this adaptor.
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Affiliation(s)
- Hongfei Xu
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Fei Chang
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Shweta Jain
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
| | - Bradley Austin Heller
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
| | - Xu Han
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Yongjian Liu
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
- Departments of Pharmacology and Biological Chemistry, University of Pittsburgh, Pittsburgh, PA
| | - Robert H. Edwards
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
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11
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Gomi H, Nagumo T, Asano K, Konosu M, Yasui T, Torii S, Hosaka M. Differential Expression of Secretogranins II and III in Canine Adrenal Chromaffin Cells and Pheochromocytomas. J Histochem Cytochem 2022; 70:335-356. [PMID: 35400231 PMCID: PMC9058372 DOI: 10.1369/00221554221091000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Secretogranin II (SgII) and III (SgIII) function within peptide hormone-producing cells and are involved in secretory granule formation. However, their function in active amine-producing cells is not fully understood. In this study, we analyzed the expression profiles of SgII and SgIII in canine adrenal medulla and pheochromocytomas by immunohistochemical staining. In normal adrenal tissues, the intensity of coexpression of these two secretogranins (Sgs) differed from each chromaffin cell, although a complete match was not observed. The coexpression of vesicular monoamine transporter 2 (VMAT2) with SgIII was similar to that with chromogranin A, but there was a subpopulation of VMAT2-expressing cells that were negative or hardly detectable for SgII. These results are the first to indicate that there are distinct expression patterns for SgII and SgIII in adrenal chromaffin cells. Furthermore, the expression of these two Sgs varied in intensity among pheochromocytomas and did not necessarily correlate with clinical plasma catecholamine levels in patients. However, compared with SgIII, the expression of SgII was shown to be strong at the single-cell level in some tumor tissues. These findings provide a fundamental understanding of the expression differences between SgII and SgIII in normal adrenal chromaffin cells and pheochromocytomas.
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Affiliation(s)
- Hiroshi Gomi
- Department of Veterinary Anatomy, College of Bioresource Sciences
| | - Takahiro Nagumo
- Department of Veterinary Surgery, College of Bioresource Sciences.,Nihon University, Fujisawa, Japan; Division of Companion Animal Surgery, Veterinary Teaching Hospital, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Kazushi Asano
- Department of Veterinary Surgery, College of Bioresource Sciences
| | - Makoto Konosu
- Department of Veterinary Anatomy, College of Bioresource Sciences
| | - Tadashi Yasui
- Department of Veterinary Anatomy, College of Bioresource Sciences
| | - Seiji Torii
- Center for Food Science and Wellness, Gunma University, Maebashi, Japan
| | - Masahiro Hosaka
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Akita, Japan
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12
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Rohli KE, Boyer CK, Blom SE, Stephens SB. Nutrient Regulation of Pancreatic Islet β-Cell Secretory Capacity and Insulin Production. Biomolecules 2022; 12:335. [PMID: 35204835 PMCID: PMC8869698 DOI: 10.3390/biom12020335] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 01/27/2023] Open
Abstract
Pancreatic islet β-cells exhibit tremendous plasticity for secretory adaptations that coordinate insulin production and release with nutritional demands. This essential feature of the β-cell can allow for compensatory changes that increase secretory output to overcome insulin resistance early in Type 2 diabetes (T2D). Nutrient-stimulated increases in proinsulin biosynthesis may initiate this β-cell adaptive compensation; however, the molecular regulators of secretory expansion that accommodate the increased biosynthetic burden of packaging and producing additional insulin granules, such as enhanced ER and Golgi functions, remain poorly defined. As these adaptive mechanisms fail and T2D progresses, the β-cell succumbs to metabolic defects resulting in alterations to glucose metabolism and a decline in nutrient-regulated secretory functions, including impaired proinsulin processing and a deficit in mature insulin-containing secretory granules. In this review, we will discuss how the adaptative plasticity of the pancreatic islet β-cell's secretory program allows insulin production to be carefully matched with nutrient availability and peripheral cues for insulin signaling. Furthermore, we will highlight potential defects in the secretory pathway that limit or delay insulin granule biosynthesis, which may contribute to the decline in β-cell function during the pathogenesis of T2D.
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Affiliation(s)
- Kristen E. Rohli
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Cierra K. Boyer
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Sandra E. Blom
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Samuel B. Stephens
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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13
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Reck J, Beuret N, Demirci E, Prescianotto-Baschong C, Spiess M. Small disulfide loops in peptide hormones mediate self-aggregation and secretory granule sorting. Life Sci Alliance 2022; 5:5/5/e202101279. [PMID: 35086936 PMCID: PMC8807871 DOI: 10.26508/lsa.202101279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 01/12/2022] [Accepted: 01/14/2022] [Indexed: 11/24/2022] Open
Abstract
Unlike constitutively secreted proteins, peptide hormones are stored in densely packed secretory granules, before regulated release upon stimulation. Secretory granules are formed at the TGN by self-aggregation of prohormones as functional amyloids. The nonapeptide hormone vasopressin, which forms a small disulfide loop, was shown to be responsible for granule formation of its precursor in the TGN as well as for toxic fibrillar aggregation of unfolded mutants in the ER. Several other hormone precursors also contain similar small disulfide loops suggesting their function as a general device to mediate aggregation for granule sorting. To test this hypothesis, we studied the capacity of small disulfide loops of different hormone precursors to mediate aggregation in the ER and the TGN. They indeed induced ER aggregation in Neuro-2a and COS-1 cells. Fused to a constitutively secreted reporter protein, they also promoted sorting into secretory granules, enhanced stimulated secretion, and increased Lubrol insolubility in AtT20 cells. These results support the hypothesis that small disulfide loops act as novel signals for sorting into secretory granules by self-aggregation.
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14
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Germanos M, Gao A, Taper M, Yau B, Kebede MA. Inside the Insulin Secretory Granule. Metabolites 2021; 11:metabo11080515. [PMID: 34436456 PMCID: PMC8401130 DOI: 10.3390/metabo11080515] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 12/19/2022] Open
Abstract
The pancreatic β-cell is purpose-built for the production and secretion of insulin, the only hormone that can remove glucose from the bloodstream. Insulin is kept inside miniature membrane-bound storage compartments known as secretory granules (SGs), and these specialized organelles can readily fuse with the plasma membrane upon cellular stimulation to release insulin. Insulin is synthesized in the endoplasmic reticulum (ER) as a biologically inactive precursor, proinsulin, along with several other proteins that will also become members of the insulin SG. Their coordinated synthesis enables synchronized transit through the ER and Golgi apparatus for congregation at the trans-Golgi network, the initiating site of SG biogenesis. Here, proinsulin and its constituents enter the SG where conditions are optimized for proinsulin processing into insulin and subsequent insulin storage. A healthy β-cell is continually generating SGs to supply insulin in vast excess to what is secreted. Conversely, in type 2 diabetes (T2D), the inability of failing β-cells to secrete may be due to the limited biosynthesis of new insulin. Factors that drive the formation and maturation of SGs and thus the production of insulin are therefore critical for systemic glucose control. Here, we detail the formative hours of the insulin SG from the luminal perspective. We do this by mapping the journey of individual members of the SG as they contribute to its genesis.
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15
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Bäck N, Mains RE, Eipper BA. PAM: diverse roles in neuroendocrine cells, cardiomyocytes, and green algae. FEBS J 2021; 289:4470-4496. [PMID: 34089560 DOI: 10.1111/febs.16049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/28/2021] [Accepted: 06/02/2021] [Indexed: 12/13/2022]
Abstract
Our understanding of the ways in which peptides are used for communication in the nervous and endocrine systems began with the identification of oxytocin, vasopressin, and insulin, each of which is stored in electron-dense granules, ready for release in response to an appropriate stimulus. For each of these peptides, entry of its newly synthesized precursor into the ER lumen is followed by transport through the secretory pathway, exposing the precursor to a sequence of environments and enzymes that produce the bioactive products stored in mature granules. A final step in the biosynthesis of many peptides is C-terminal amidation by peptidylglycine α-amidating monooxygenase (PAM), an ascorbate- and copper-dependent membrane enzyme that enters secretory granules along with its soluble substrates. Biochemical and cell biological studies elucidated the highly conserved mechanism for amidated peptide production and raised many questions about PAM trafficking and the effects of PAM on cytoskeletal organization and gene expression. Phylogenetic studies and the discovery of active PAM in the ciliary membranes of Chlamydomonas reinhardtii, a green alga lacking secretory granules, suggested that a PAM-like enzyme was present in the last eukaryotic common ancestor. While the catalytic features of human and C. reinhardtii PAM are strikingly similar, the trafficking of PAM in C. reinhardtii and neuroendocrine cells and secretion of its amidated products differ. A comparison of PAM function in neuroendocrine cells, atrial myocytes, and C. reinhardtii reveals multiple ways in which altered trafficking allows PAM to accomplish different tasks in different species and cell types.
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Affiliation(s)
- Nils Bäck
- Department of Anatomy, University of Helsinki, Finland
| | - Richard E Mains
- Department of Neuroscience, UConn Health, Farmington, CT, USA
| | - Betty A Eipper
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
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16
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Ma CIJ, Burgess J, Brill JA. Maturing secretory granules: Where secretory and endocytic pathways converge. Adv Biol Regul 2021; 80:100807. [PMID: 33866198 DOI: 10.1016/j.jbior.2021.100807] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 10/21/2022]
Abstract
Secretory granules (SGs) are specialized organelles responsible for the storage and regulated release of various biologically active molecules from the endocrine and exocrine systems. Thus, proper SG biogenesis is critical to normal animal physiology. Biogenesis of SGs starts at the trans-Golgi network (TGN), where immature SGs (iSGs) bud off and undergo maturation before fusing with the plasma membrane (PM). How iSGs mature is unclear, but emerging studies have suggested an important role for the endocytic pathway. The requirement for endocytic machinery in SG maturation blurs the line between SGs and another class of secretory organelles called lysosome-related organelles (LROs). Therefore, it is important to re-evaluate the differences and similarities between SGs and LROs.
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Affiliation(s)
- Cheng-I Jonathan Ma
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Medical Sciences Building, Room 2374, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Jason Burgess
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, Medical Sciences Building, Room 4396, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Julie A Brill
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Medical Sciences Building, Room 2374, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Medical Sciences Building, Room 4396, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
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17
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Halcrow PW, Geiger JD, Chen X. Overcoming Chemoresistance: Altering pH of Cellular Compartments by Chloroquine and Hydroxychloroquine. Front Cell Dev Biol 2021; 9:627639. [PMID: 33634129 PMCID: PMC7900406 DOI: 10.3389/fcell.2021.627639] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/18/2021] [Indexed: 12/12/2022] Open
Abstract
Resistance to the anti-cancer effects of chemotherapeutic agents (chemoresistance) is a major issue for people living with cancer and their providers. A diverse set of cellular and inter-organellar signaling changes have been implicated in chemoresistance, but it is still unclear what processes lead to chemoresistance and effective strategies to overcome chemoresistance are lacking. The anti-malaria drugs, chloroquine (CQ) and its derivative hydroxychloroquine (HCQ) are being used for the treatment of various cancers and CQ and HCQ are used in combination with chemotherapeutic drugs to enhance their anti-cancer effects. The widely accepted anti-cancer effect of CQ and HCQ is their ability to inhibit autophagic flux. As diprotic weak bases, CQ and HCQ preferentially accumulate in acidic organelles and neutralize their luminal pH. In addition, CQ and HCQ acidify the cytosolic and extracellular environments; processes implicated in tumorigenesis and cancer. Thus, the anti-cancer effects of CQ and HCQ extend beyond autophagy inhibition. The present review summarizes effects of CQ, HCQ and proton pump inhibitors on pH of various cellular compartments and discuss potential mechanisms underlying their pH-dependent anti-cancer effects. The mechanisms considered here include their ability to de-acidify lysosomes and inhibit autophagosome lysosome fusion, to de-acidify Golgi apparatus and secretory vesicles thus affecting secretion, and to acidify cytoplasm thus disturbing aerobic metabolism. Further, we review the ability of these agents to prevent chemotherapeutic drugs from accumulating in acidic organelles and altering their cytosolic concentrations.
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Affiliation(s)
| | | | - Xuesong Chen
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States
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18
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Liu M, Huang Y, Xu X, Li X, Alam M, Arunagiri A, Haataja L, Ding L, Wang S, Itkin-Ansari P, Kaufman RJ, Tsai B, Qi L, Arvan P. Normal and defective pathways in biogenesis and maintenance of the insulin storage pool. J Clin Invest 2021; 131:142240. [PMID: 33463547 PMCID: PMC7810482 DOI: 10.1172/jci142240] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Both basal and glucose-stimulated insulin release occur primarily by insulin secretory granule exocytosis from pancreatic β cells, and both are needed to maintain normoglycemia. Loss of insulin-secreting β cells, accompanied by abnormal glucose tolerance, may involve simple exhaustion of insulin reserves (which, by immunostaining, appears as a loss of β cell identity), or β cell dedifferentiation, or β cell death. While various sensing and signaling defects can result in diminished insulin secretion, somewhat less attention has been paid to diabetes risk caused by insufficiency in the biosynthetic generation and maintenance of the total insulin granule storage pool. This Review offers an overview of insulin biosynthesis, beginning with the preproinsulin mRNA (translation and translocation into the ER), proinsulin folding and export from the ER, and delivery via the Golgi complex to secretory granules for conversion to insulin and ultimate hormone storage. All of these steps are needed for generation and maintenance of the total insulin granule pool, and defects in any of these steps may, weakly or strongly, perturb glycemic control. The foregoing considerations have obvious potential relevance to the pathogenesis of type 2 diabetes and some forms of monogenic diabetes; conceivably, several of these concepts might also have implications for β cell failure in type 1 diabetes.
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Affiliation(s)
- Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Yumeng Huang
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Xiaoxi Xu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Xin Li
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Maroof Alam
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Anoop Arunagiri
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Leena Haataja
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Li Ding
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Shusen Wang
- Organ Transplant Center, Tianjin First Central Hospital, Tianjin, China
| | | | - Randal J. Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Billy Tsai
- Department of Cell and Developmental Biology, and
| | - Ling Qi
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan, USA
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19
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Viinikangas T, Khosrowabadi E, Kellokumpu S. N-Glycan Biosynthesis: Basic Principles and Factors Affecting Its Outcome. EXPERIENTIA SUPPLEMENTUM (2012) 2021; 112:237-257. [PMID: 34687012 DOI: 10.1007/978-3-030-76912-3_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Carbohydrate chains are the most abundant and diverse of nature's biopolymers and represent one of the four fundamental macromolecular building blocks of life together with proteins, nucleic acids, and lipids. Indicative of their essential roles in cells and in multicellular organisms, genes encoding proteins associated with glycosylation account for approximately 2% of the human genome. It has been estimated that 50-80% of all human proteins carry carbohydrate chains-glycans-as part of their structure. Despite cells utilize only nine different monosaccharides for making their glycans, their order and conformational variation in glycan chains together with chain branching differences and frequent post-synthetic modifications can give rise to an enormous repertoire of different glycan structures of which few thousand is estimated to carry important structural or functional information for a cell. Thus, glycans are immensely versatile encoders of multicellular life. Yet, glycans do not represent a random collection of unpredictable structures but rather, a collection of predetermined but still dynamic entities that are present at defined quantities in each glycosylation site of a given protein in a cell, tissue, or organism.In this chapter, we will give an overview of what is currently known about N-glycan synthesis in higher eukaryotes, focusing not only on the processes themselves but also on factors that will affect or can affect the final outcome-the dynamicity and heterogeneity of the N-glycome. We hope that this review will help understand the molecular details underneath this diversity, and in addition, be helpful for those who plan to produce optimally glycosylated antibody-based therapeutics.
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Affiliation(s)
- Teemu Viinikangas
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Elham Khosrowabadi
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Sakari Kellokumpu
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
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20
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Chen X, Geiger JD. Janus sword actions of chloroquine and hydroxychloroquine against COVID-19. Cell Signal 2020; 73:109706. [PMID: 32629149 PMCID: PMC7333634 DOI: 10.1016/j.cellsig.2020.109706] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/26/2020] [Accepted: 06/29/2020] [Indexed: 02/06/2023]
Abstract
Chloroquine (CQ) and its analogue hydroxychloroquine (HCQ) have been thrust into our everyday vernacular because some believe, based on very limited basic and clinical data, that they might be helpful in preventing and/or lessening the severity of the pandemic coronavirus disease 2019 (COVID-19). However, lacking is a temperance in enthusiasm for their possible use as well as sufficient perspective on their effects and side-effects. CQ and HCQ have well-known properties of being diprotic weak bases that preferentially accumulate in acidic organelles (endolysosomes and Golgi apparatus) and neutralize luminal pH of acidic organelles. These primary actions of CQ and HCQ are responsible for their anti-malarial effects; malaria parasites rely on acidic digestive vacuoles for survival. Similarly, de-acidification of endolysosomes and Golgi by CQ and HCQ may block severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) integration into host cells because SARS-CoV-2 may require an acidic environment for its entry and for its ability to bud and infect bystander cells. Further, de-acidification of endolysosomes and Golgi may underly the immunosuppressive effects of these two drugs. However, modern cell biology studies have shown clearly that de-acidification results in profound changes in the structure, function and cellular positioning of endolysosomes and Golgi, in signaling between these organelles and other subcellular organelles, and in fundamental cellular functions. Thus, studying the possible therapeutic effects of CQ and HCQ against COVID-19 must occur concurrent with studies of the extent to which these drugs affect organellar and cell biology. When comprehensively examined, a better understanding of the Janus sword actions of these and other drugs might yield better decisions and better outcomes.
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Affiliation(s)
- Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America.
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
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21
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Fujita-Yoshigaki J, Yokoyama M, Katsumata-Kato O. Switching of cargo sorting from the constitutive to regulated secretory pathway by the addition of cystatin D sequence in salivary acinar cells. Am J Physiol Gastrointest Liver Physiol 2020; 319:G74-G86. [PMID: 32538138 DOI: 10.1152/ajpgi.00103.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The mechanism for segregation of cargo proteins into the regulated and constitutive secretory pathways in exocrine cells remains to be elucidated. We examined the transport of HaloTag proteins fused with full-length cystatin D (fCst5-Halo) or only its signal peptide (ssCst5-Halo) in parotid acinar cells. Although both fusion proteins were observed to be colocalized with amylase in the secretory granules, the coefficients for overlapping and correlation of fCst5-Halo with amylase were higher than those of ssCst5-Halo. The secretion of both the proteins was enhanced by the addition of the β-adrenergic receptor agonist isoproterenol as well as endogenous amylase. In contrast, unstimulated secretion of ssCst5-Halo without isoproterenol was significantly higher than that of fCst5-Halo and amylase. Simulation analysis using a mathematical model revealed that a large proportion of ssCst5-Halo was secreted through the constitutive pathway, whereas fCst5-Halo was transported into the secretory granules more efficiently. Precipitation of fCst5-Halo from cell lysates was increased at a low pH, which may mimic the milieu of the trans-Golgi networks. These data suggest that the addition of a full-length sequence of cystatin D facilitates efficient selective transport into the regulated pathway by aggregation at low pH in the trans-Golgi network.NEW & NOTEWORTHY The mechanism underlying the segregation of cargo proteins to the regulated and constitutive secretory pathways in exocrine cells remains to be solved. We analyzed unstimulated secretion in salivary acinar cells by performing double-labeling experiments using HaloTag technology and computer simulation. It revealed that the majority of HaloTag with only signal peptide sequence was secreted through the constitutive pathway and that the addition of a full-length cystatin D sequence changed its sorting to the regulated pathway.
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Affiliation(s)
- Junko Fujita-Yoshigaki
- Department of Physiology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba, Japan.,Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba, Japan
| | - Megumi Yokoyama
- Department of Physiology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba, Japan.,Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba, Japan
| | - Osamu Katsumata-Kato
- Department of Physiology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba, Japan.,Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba, Japan
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22
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Carmon O, Laguerre F, Riachy L, Delestre-Delacour C, Wang Q, Tanguy E, Jeandel L, Cartier D, Thahouly T, Haeberlé AM, Fouillen L, Rezazgui O, Schapman D, Haefelé A, Goumon Y, Galas L, Renard PY, Alexandre S, Vitale N, Anouar Y, Montero-Hadjadje M. Chromogranin A preferential interaction with Golgi phosphatidic acid induces membrane deformation and contributes to secretory granule biogenesis. FASEB J 2020; 34:6769-6790. [PMID: 32227388 DOI: 10.1096/fj.202000074r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/28/2020] [Accepted: 03/14/2020] [Indexed: 12/14/2022]
Abstract
Chromogranin A (CgA) is a key luminal actor of secretory granule biogenesis at the trans-Golgi network (TGN) level but the molecular mechanisms involved remain obscure. Here, we investigated the possibility that CgA acts synergistically with specific membrane lipids to trigger secretory granule formation. We show that CgA preferentially interacts with the anionic glycerophospholipid phosphatidic acid (PA). In accordance, bioinformatic analysis predicted a PA-binding domain (PABD) in CgA sequence that effectively bound PA (36:1) or PA (40:6) in membrane models. We identified PA (36:1) and PA (40:6) as predominant species in Golgi and granule membranes of secretory cells, and we found that CgA interaction with these PA species promotes artificial membrane deformation and remodeling. Furthermore, we demonstrated that disruption of either CgA PABD or phospholipase D (PLD) activity significantly alters secretory granule formation in secretory cells. Our findings show for the first time the ability of CgA to interact with PLD-generated PA, which allows membrane remodeling and curvature, key processes necessary to initiate secretory granule budding.
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Affiliation(s)
- Ophélie Carmon
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Fanny Laguerre
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Lina Riachy
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Charlène Delestre-Delacour
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Emeline Tanguy
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Lydie Jeandel
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Dorthe Cartier
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Tamou Thahouly
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Anne-Marie Haeberlé
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Laetitia Fouillen
- Laboratoire de Biogénèse Membranaire, CNRS, Plateforme Métabolome, Université de Bordeaux, UMR-5200, Villenave D'Ornon, France
| | - Olivier Rezazgui
- INSA Rouen, CNRS, Normandie University, UNIROUEN, COBRA, UMR 6014 and FR 3038, Rouen, France
| | - Damien Schapman
- Normandie University, UNIROUEN, INSERM, PRIMACEN, Rouen, France
| | - Alexandre Haefelé
- INSA Rouen, CNRS, Normandie University, UNIROUEN, COBRA, UMR 6014 and FR 3038, Rouen, France
| | - Yannick Goumon
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Ludovic Galas
- Normandie University, UNIROUEN, INSERM, PRIMACEN, Rouen, France
| | - Pierre-Yves Renard
- INSA Rouen, CNRS, Normandie University, UNIROUEN, COBRA, UMR 6014 and FR 3038, Rouen, France
| | - Stéphane Alexandre
- Polymères, Biopolymères, Surfaces Laboratory, CNRS, Normandie University, UNIROUEN, UMR 6270, Rouen, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Université de Strasbourg, Strasbourg, France
| | - Youssef Anouar
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Maité Montero-Hadjadje
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
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Parmer RJ, Gong Y, Yoo SH, Miles LA. Neuroendocrine Targeting of Tissue Plasminogen Activator (t-PA). JOURNAL OF NEUROLOGICAL DISORDERS & STROKE 2020; 7:1153. [PMID: 32549050 PMCID: PMC7297194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
t-PA has a widespread neuroendocrine distribution including prominent expression in chromaffin cells of the sympathoadrenal system. Chromaffin cell t-PA is sorted into catecholamine storage vesicles and co-released with catecholamines in response to sympathoadrenal activation, suggesting that catecholamine storage vesicles may serve as a reservoir for the rapid release of t-PA. Chromogranin A (CgA), a major core protein in secretory vesicles throughout the neuroendocrine system, may play a crucial role in targeting proteins into the regulated secretory pathway, by forming aggregated "granin" complexes to which other proteins destined for the regulated secretory vesicle bind and become separated from constitutively secreted proteins in the trans-Golgi network (TGN). Formation of such complexes is facilitated by conditions of the TGN (low pH, high Ca+2). We tested the hypothesis that t-PA interacts specifically with CgA and that this interaction is enhanced under conditions of the TGN. Immobilized t-PA was incubated with 125I-CgA. t-PA interacted specifically and saturably with CgA and the interaction was domain-specific, mediated by the EGF/finger and kringle 1 domains of t-PA and by a specific internal hydrophilic domain within CgA (KERTHQQKKHSSYEDELSEVL) as assessed by antibody and peptide competition studies. The interaction of t-PA with aggregated CgA complexes may play a role in the targeting of t-PA and its release from neurosecretory cells. These results may have broad implications for the regulation of local neurosecretory cell plasminogen activation under both normal physiological conditions and pathological conditions including cerebral ischemia.
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Affiliation(s)
- Robert J. Parmer
- Department of Medicine, University of California, USA
- Veterans Administration San Diego Healthcare System, San Diego, CA, USA
| | - Yun Gong
- Department of Pathology, M.D. Anderson Cancer Center, USA
| | | | - Lindsey A. Miles
- Department of Molecular Medicine, The Scripps Research Institute, USA
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24
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Abstract
Maintenance of the main Golgi functions, glycosylation and sorting, is dependent on the unique Golgi pH microenvironment that is thought to be set by the balance between the rates of V-ATPase-mediated proton pumping and its leakage back to the cytoplasm via an unknown pathway. The concentration of other ions, such as chloride, potassium, calcium, magnesium, and manganese, is also important for Golgi homeostasis and dependent on the transport activity of other ion transporters present in the Golgi membranes. During the last decade, several new disorders have been identified that are caused by, or are associated with, dysregulated Golgi pH and ion homeostasis. Here, we will provide an updated overview on these disorders and the proteins involved. We will also discuss other disorders for which the molecular defects remain currently uncertain but which potentially involve proteins that regulate Golgi pH or ion homeostasis.
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25
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Laguerre F, Anouar Y, Montero-Hadjadje M. Chromogranin A in the early steps of the neurosecretory pathway. IUBMB Life 2019; 72:524-532. [PMID: 31891241 DOI: 10.1002/iub.2218] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 12/10/2019] [Indexed: 12/20/2022]
Abstract
Chromogranin A (CgA) is a soluble glycoprotein stored with hormones and neuropeptides in secretory granules (SG) of most (neuro)endocrine cells and neurons. Since its discovery in 1967, many studies have reported its structural characteristics, biological roles, and mechanisms of action. Indeed, CgA is both a precursor of various biologically active peptides and a granulogenic protein regulating the storage and secretion of hormones and neuropeptides. This review emphasizes the findings and theoretical concepts around the CgA-linked molecular machinery controlling hormone/neuropeptide aggregation and the interaction of CgA-hormone/neuropeptide aggregates with the trans-Golgi membrane to allow hormone/neuropeptide targeting and SG biogenesis. We will also discuss the intriguing alteration of CgA expression and secretion in various neurological disorders, which could provide insights to elucidate the molecular mechanisms underlying these pathophysiological conditions.
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Affiliation(s)
- Fanny Laguerre
- Normandie Univ, UNIROUEN, INSERM, U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Rouen, France
| | - Youssef Anouar
- Normandie Univ, UNIROUEN, INSERM, U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Rouen, France
| | - Maité Montero-Hadjadje
- Normandie Univ, UNIROUEN, INSERM, U1239, Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Rouen, France
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26
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Wang WA, Agellon LB, Michalak M. Organellar Calcium Handling in the Cellular Reticular Network. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a038265. [PMID: 31358518 DOI: 10.1101/cshperspect.a038265] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ca2+ is an important intracellular messenger affecting diverse cellular processes. In eukaryotic cells, Ca2+ is handled by a myriad of Ca2+-binding proteins found in organelles that are organized into the cellular reticular network (CRN). The network is comprised of the endoplasmic reticulum, Golgi apparatus, lysosomes, membranous components of the endocytic and exocytic pathways, peroxisomes, and the nuclear envelope. Membrane contact sites between the different components of the CRN enable the rapid movement of Ca2+, and communication of Ca2+ status, within the network. Ca2+-handling proteins that reside in the CRN facilitate Ca2+ sensing, buffering, and cellular signaling to coordinate the many processes that operate within the cell.
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Affiliation(s)
- Wen-An Wang
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
| | - Luis B Agellon
- School of Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
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27
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Clustering and dynamics of crowded proteins near membranes and their influence on membrane bending. Proc Natl Acad Sci U S A 2019; 116:24562-24567. [PMID: 31740611 DOI: 10.1073/pnas.1910771116] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atomistic molecular dynamics simulations of concentrated protein solutions in the presence of a phospholipid bilayer are presented to gain insights into the dynamics and interactions at the cytosol-membrane interface. The main finding is that proteins that are not known to specifically interact with membranes are preferentially excluded from the membrane, leaving a depletion zone near the membrane surface. As a consequence, effective protein concentrations increase, leading to increased protein contacts and clustering, whereas protein diffusion becomes faster near the membrane for proteins that do occasionally enter the depletion zone. Since protein-membrane contacts are infrequent and short-lived in this study, the structure of the lipid bilayer remains largely unaffected by the crowded protein solution, but when proteins do contact lipid head groups, small but statistically significant local membrane curvature is induced, on average.
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28
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Lietzén N, Hirvonen K, Honkimaa A, Buchacher T, Laiho JE, Oikarinen S, Mazur MA, Flodström-Tullberg M, Dufour E, Sioofy-Khojine AB, Hyöty H, Lahesmaa R. Coxsackievirus B Persistence Modifies the Proteome and the Secretome of Pancreatic Ductal Cells. iScience 2019; 19:340-357. [PMID: 31404834 PMCID: PMC6699423 DOI: 10.1016/j.isci.2019.07.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/08/2019] [Accepted: 07/25/2019] [Indexed: 02/08/2023] Open
Abstract
The group B Coxsackieviruses (CVB), belonging to the Enterovirus genus, can establish persistent infections in human cells. These persistent infections have been linked to chronic diseases including type 1 diabetes. Still, the outcomes of persistent CVB infections in human pancreas are largely unknown. We established persistent CVB infections in a human pancreatic ductal-like cell line PANC-1 using two distinct CVB1 strains and profiled infection-induced changes in cellular protein expression and secretion using mass spectrometry-based proteomics. Persistent infections, showing characteristics of carrier-state persistence, were associated with a broad spectrum of changes, including changes in mitochondrial network morphology and energy metabolism and in the regulated secretory pathway. Interestingly, the expression of antiviral immune response proteins, and also several other proteins, differed clearly between the two persistent infections. Our results provide extensive information about the protein-level changes induced by persistent CVB infection and the potential virus-associated variability in the outcomes of these infections.
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Affiliation(s)
- Niina Lietzén
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, FI-20520 Turku, Finland
| | - Karoliina Hirvonen
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, FI-20520 Turku, Finland
| | - Anni Honkimaa
- Faculty of Medicine and Health Technology, Tampere University, FI-33014 Tampere, Finland
| | - Tanja Buchacher
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, FI-20520 Turku, Finland
| | - Jutta E Laiho
- Faculty of Medicine and Health Technology, Tampere University, FI-33014 Tampere, Finland
| | - Sami Oikarinen
- Faculty of Medicine and Health Technology, Tampere University, FI-33014 Tampere, Finland
| | - Magdalena A Mazur
- Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, Karolinska University Hospital, Stockholm 141 86, Sweden
| | - Malin Flodström-Tullberg
- Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, Karolinska University Hospital, Stockholm 141 86, Sweden
| | - Eric Dufour
- Faculty of Medicine and Life Sciences, BioMediTech Institute and Tampere University Hospital, FI-33014 Tampere, Finland
| | | | - Heikki Hyöty
- Faculty of Medicine and Health Technology, Tampere University, FI-33014 Tampere, Finland; Fimlab Laboratories, Pirkanmaa Hospital District, FI-33520 Tampere, Finland
| | - Riitta Lahesmaa
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, FI-20520 Turku, Finland.
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29
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Sundberg EL, Deng Y, Burd CG. Syndecan-1 Mediates Sorting of Soluble Lipoprotein Lipase with Sphingomyelin-Rich Membrane in the Golgi Apparatus. Dev Cell 2019; 51:387-398.e4. [PMID: 31543446 DOI: 10.1016/j.devcel.2019.08.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/05/2019] [Accepted: 08/21/2019] [Indexed: 12/12/2022]
Abstract
In the secretory pathway, budding of vesicular transport carriers from the trans-Golgi network (TGN) must coordinate specification of lipid composition with selection of secreted proteins. We elucidate a mechanism of soluble protein cargo sorting into secretory vesicles with a sphingomyelin-rich membrane; the integral membrane proteoglycan Syndecan-1 (SDC1) acts as a sorting receptor, capturing the soluble enzyme lipoprotein lipase (LPL) during export from the TGN. Sorting of LPL requires bivalent interactions between LPL and SDC1-linked heparan sulfate chains and between LPL and the Golgi membrane. Physical features of the SDC1 transmembrane domain, rather than a specific sequence, confer targeting of SDC1 and bound LPL into the sphingomyelin secretion pathway. This study establishes that physicochemical properties of a protein transmembrane domain that drive lateral heterogeneity of the plasma membrane also operate at the TGN to confer sorting of an integral membrane protein and its ligand within the biosynthetic secretory pathway.
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Affiliation(s)
- Emma L Sundberg
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Yongqiang Deng
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Christopher G Burd
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
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30
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Bearrows SC, Bauchle CJ, Becker M, Haldeman JM, Swaminathan S, Stephens SB. Chromogranin B regulates early-stage insulin granule trafficking from the Golgi in pancreatic islet β-cells. J Cell Sci 2019; 132:jcs.231373. [PMID: 31182646 DOI: 10.1242/jcs.231373] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/31/2019] [Indexed: 12/12/2022] Open
Abstract
Chromogranin B (CgB, also known as CHGB) is abundantly expressed in dense core secretory granules of multiple endocrine tissues and has been suggested to regulate granule biogenesis in some cell types, including the pancreatic islet β-cell, though the mechanisms are poorly understood. Here, we demonstrate a critical role for CgB in regulating secretory granule trafficking in the β-cell. Loss of CgB impairs glucose-stimulated insulin secretion, impedes proinsulin processing to yield increased proinsulin content, and alters the density of insulin-containing granules. Using an in situ fluorescent pulse-chase strategy to track nascent proinsulin, we show that loss of CgB impairs Golgi budding of proinsulin-containing secretory granules, resulting in a substantial delay in trafficking of nascent granules to the plasma membrane with an overall decrease in total plasma membrane-associated granules. These studies demonstrate that CgB is necessary for efficient trafficking of secretory proteins into the budding granule, which impacts the availability of insulin-containing secretory granules for exocytic release.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Shelby C Bearrows
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52246, USA.,Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52246, USA
| | - Casey J Bauchle
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52246, USA.,Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52246, USA
| | - McKenzie Becker
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52246, USA.,Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52246, USA
| | - Jonathan M Haldeman
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27710, USA.,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Svetha Swaminathan
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52246, USA.,Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52246, USA
| | - Samuel B Stephens
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52246, USA .,Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Iowa, Iowa City, IA 52246, USA
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31
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Kellokumpu S. Golgi pH, Ion and Redox Homeostasis: How Much Do They Really Matter? Front Cell Dev Biol 2019; 7:93. [PMID: 31263697 PMCID: PMC6584808 DOI: 10.3389/fcell.2019.00093] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 05/16/2019] [Indexed: 02/06/2023] Open
Abstract
Exocytic and endocytic compartments each have their own unique luminal ion and pH environment that is important for their normal functioning. A failure to maintain this environment - the loss of homeostasis - is not uncommon. In the worst case, all the main Golgi functions, including glycosylation, membrane trafficking and protein sorting, can be perturbed. Several factors contribute to Golgi homeostasis. These include not only ions such as H+, Ca2+, Mg2+, Mn2+, but also Golgi redox state and nitric oxide (NO) levels, both of which are dependent on the oxygen levels in the cells. Changes to any one of these factors have consequences on Golgi functions, the nature of which can be dissimilar or similar depending upon the defects themselves. For example, altered Golgi pH homeostasis gives rise to Cutis laxa disease, in which glycosylation and membrane trafficking are both affected, while altered Ca2+ homeostasis due to the mutated SCPA1 gene in Hailey-Hailey disease, perturbs various protein sorting, proteolytic cleavage and membrane trafficking events in the Golgi. This review gives an overview of the molecular machineries involved in the maintenance of Golgi ion, pH and redox homeostasis, followed by a discussion of the organelle dysfunction and disease that frequently result from their breakdown. Congenital disorders of glycosylation (CDGs) are discussed only when they contribute directly to Golgi pH, ion or redox homeostasis. Current evidence emphasizes that, rather than being mere supporting factors, Golgi pH, ion and redox homeostasis are in fact key players that orchestrate and maintain all Golgi functions.
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Affiliation(s)
- Sakari Kellokumpu
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
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32
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Stevenson MJ, Uyeda KS, Harder NHO, Heffern MC. Metal-dependent hormone function: the emerging interdisciplinary field of metalloendocrinology. Metallomics 2019; 11:85-110. [PMID: 30270362 PMCID: PMC10249669 DOI: 10.1039/c8mt00221e] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
For over 100 years, there has been an incredible amount of knowledge amassed concerning hormones in the endocrine system and their central role in human health. Hormones represent a diverse group of biomolecules that are released by glands, communicate signals to their target tissue, and are regulated by feedback loops to maintain organism health. Many disease states, such as diabetes and reproductive disorders, stem from misregulation or dysfunction of hormones. Increasing research is illuminating the intricate roles of metal ions in the endocrine system where they may act advantageously in concert with hormones or deleteriously catalyze hormone-associated disease states. As the critical role of metal ions in the endocrine system becomes more apparent, it is increasingly important to untangle the complex mechanisms underlying the connections between inorganic biochemistry and hormone function to understand and control endocrinological phenomena. This tutorial review harmonizes the interdisciplinary fields of endocrinology and inorganic chemistry in the newly-termed field of "metalloendocrinology". We describe examples linking metals to both normal and aberrant hormone function with a focus on highlighting insight to molecular mechanisms. Hormone activities related to both essential metal micronutrients, such as copper, iron, zinc, and calcium, and disruptive nonessential metals, such as lead and cadmium are discussed.
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Affiliation(s)
- Michael J Stevenson
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
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33
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Harno E, Gali Ramamoorthy T, Coll AP, White A. POMC: The Physiological Power of Hormone Processing. Physiol Rev 2019; 98:2381-2430. [PMID: 30156493 DOI: 10.1152/physrev.00024.2017] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pro-opiomelanocortin (POMC) is the archetypal polypeptide precursor of hormones and neuropeptides. In this review, we examine the variability in the individual peptides produced in different tissues and the impact of the simultaneous presence of their precursors or fragments. We also discuss the problems inherent in accurately measuring which of the precursors and their derived peptides are present in biological samples. We address how not being able to measure all the combinations of precursors and fragments quantitatively has affected our understanding of the pathophysiology associated with POMC processing. To understand how different ratios of peptides arise, we describe the role of the pro-hormone convertases (PCs) and their tissue specificities and consider the cellular processing pathways which enable regulated secretion of different peptides that play crucial roles in integrating a range of vital physiological functions. In the pituitary, correct processing of POMC peptides is essential to maintain the hypothalamic-pituitary-adrenal axis, and this processing can be disrupted in POMC-expressing tumors. In hypothalamic neurons expressing POMC, abnormalities in processing critically impact on the regulation of appetite, energy homeostasis, and body composition. More work is needed to understand whether expression of the POMC gene in a tissue equates to release of bioactive peptides. We suggest that this comprehensive view of POMC processing, with a focus on gaining a better understanding of the combination of peptides produced and their relative bioactivity, is a necessity for all involved in studying this fascinating physiological regulatory phenomenon.
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Affiliation(s)
- Erika Harno
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Thanuja Gali Ramamoorthy
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anthony P Coll
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anne White
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
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34
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Mennerich D, Kellokumpu S, Kietzmann T. Hypoxia and Reactive Oxygen Species as Modulators of Endoplasmic Reticulum and Golgi Homeostasis. Antioxid Redox Signal 2019; 30:113-137. [PMID: 29717631 DOI: 10.1089/ars.2018.7523] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
SIGNIFICANCE Eukaryotic cells execute various functions in subcellular compartments or organelles for which cellular redox homeostasis is of importance. Apart from mitochondria, hypoxia and stress-mediated formation of reactive oxygen species (ROS) were shown to modulate endoplasmic reticulum (ER) and Golgi apparatus (GA) functions. Recent Advances: Research during the last decade has improved our understanding of disulfide bond formation, protein glycosylation and secretion, as well as pH and redox homeostasis in the ER and GA. Thus, oxygen (O2) itself, NADPH oxidase (NOX) formed ROS, and pH changes appear to be of importance and indicate the intricate balance of intercompartmental communication. CRITICAL ISSUES Although the interplay between hypoxia, ER stress, and Golgi function is evident, the existence of more than 20 protein disulfide isomerase family members and the relative mild phenotypes of, for example, endoplasmic reticulum oxidoreductin 1 (ERO1)- and NOX4-knockout mice clearly suggest the existence of redundant and alternative pathways, which remain largely elusive. FUTURE DIRECTIONS The identification of these pathways and the key players involved in intercompartmental communication needs suitable animal models, genome-wide association, as well as proteomic studies in humans. The results of those studies will be beneficial for the understanding of the etiology of diseases such as type 2 diabetes, Alzheimer's disease, and cancer, which are associated with ROS, protein aggregation, and glycosylation defects.
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Affiliation(s)
- Daniela Mennerich
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu , Oulu, Finland
| | - Sakari Kellokumpu
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu , Oulu, Finland
| | - Thomas Kietzmann
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu , Oulu, Finland
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35
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Venugopal K, Marion S. Secretory organelle trafficking in Toxoplasma gondii: A long story for a short travel. Int J Med Microbiol 2018; 308:751-760. [DOI: 10.1016/j.ijmm.2018.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/10/2018] [Accepted: 07/15/2018] [Indexed: 12/15/2022] Open
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Tang J, Yin HY, Zhang JL. A luminescent aluminium salen complex allows for monitoring dynamic vesicle trafficking from the Golgi apparatus to lysosomes in living cells. Chem Sci 2018; 9:1931-1939. [PMID: 29675239 PMCID: PMC5892405 DOI: 10.1039/c7sc04498d] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/05/2018] [Indexed: 12/21/2022] Open
Abstract
Tracking vesicle transport from the Golgi apparatus to lysosomes based on an Al3+–phospholipid coordination strategy.
The Golgi apparatus is well-known as the center of vesicle trafficking whose malfunction might cause the breakdown of overall cellular architecture and ultimately cell death. The development of fluorescent probes to not only precisely stain the Golgi apparatus but also monitor dynamic vesicle trafficking is of great significance. While fluorescent proteins and fluorescent lipid analogs have been reported, they are sometime limited by either overexpression and toxicity or lack of high selectivity, respectively. We herein report a novel approach based on metal-induced coordination between the phosphate anions of phospholipids and the metal center of a luminescent Alsalen complex AlL, which can in situ track membrane vesicle trafficking from the Golgi apparatus to the lysosomes in living cells. This work opens a new avenue for designing luminescent metal probes based on the Lewis acidity of metal ions and allows the use of metal ions with different charge states, polarities, and reactivities within a similar structural scaffold to expand coordination chemistry for biological studies.
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Affiliation(s)
- Juan Tang
- Beijing National Laboratory for Molecular Sciences , State Key Laboratory of Rare Earth Materials Chemistry and Applications , College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , P. R. China .
| | - Hao-Yan Yin
- Beijing National Laboratory for Molecular Sciences , State Key Laboratory of Rare Earth Materials Chemistry and Applications , College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , P. R. China .
| | - Jun-Long Zhang
- Beijing National Laboratory for Molecular Sciences , State Key Laboratory of Rare Earth Materials Chemistry and Applications , College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , P. R. China .
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37
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Chromofungin (CHR: CHGA47-66) is downregulated in persons with active ulcerative colitis and suppresses pro-inflammatory macrophage function through the inhibition of NF-κB signaling. Biochem Pharmacol 2017; 145:102-113. [DOI: 10.1016/j.bcp.2017.08.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/17/2017] [Indexed: 12/22/2022]
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38
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Hummer BH, de Leeuw NF, Burns C, Chen L, Joens MS, Hosford B, Fitzpatrick JAJ, Asensio CS. HID-1 controls formation of large dense core vesicles by influencing cargo sorting and trans-Golgi network acidification. Mol Biol Cell 2017; 28:3870-3880. [PMID: 29074564 PMCID: PMC5739301 DOI: 10.1091/mbc.e17-08-0491] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/05/2017] [Accepted: 10/16/2017] [Indexed: 12/19/2022] Open
Abstract
The peripheral membrane protein HID-1 localizes to the trans-Golgi network, where it contributes to the formation of large dense core vesicles of neuroendocrine cells by influencing cargo sorting and trans-Golgi network acidification. Large dense core vesicles (LDCVs) mediate the regulated release of neuropeptides and peptide hormones. They form at the trans-Golgi network (TGN), where their soluble content aggregates to form a dense core, but the mechanisms controlling biogenesis are still not completely understood. Recent studies have implicated the peripheral membrane protein HID-1 in neuropeptide sorting and insulin secretion. Using CRISPR/Cas9, we generated HID-1 KO rat neuroendocrine cells, and we show that the absence of HID-1 results in specific defects in peptide hormone and monoamine storage and regulated secretion. Loss of HID-1 causes a reduction in the number of LDCVs and affects their morphology and biochemical properties, due to impaired cargo sorting and dense core formation. HID-1 KO cells also exhibit defects in TGN acidification together with mislocalization of the Golgi-enriched vacuolar H+-ATPase subunit isoform a2. We propose that HID-1 influences early steps in LDCV formation by controlling dense core formation at the TGN.
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Affiliation(s)
- Blake H Hummer
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Noah F de Leeuw
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Christian Burns
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Lan Chen
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Matthew S Joens
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO 63110
| | - Bethany Hosford
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO 63110
| | - Cedric S Asensio
- Department of Biological Sciences, University of Denver, Denver, CO 80210
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Carter SD, Mageswaran SK, Farino ZJ, Mamede JI, Oikonomou CM, Hope TJ, Freyberg Z, Jensen GJ. Distinguishing signal from autofluorescence in cryogenic correlated light and electron microscopy of mammalian cells. J Struct Biol 2017; 201:15-25. [PMID: 29078993 DOI: 10.1016/j.jsb.2017.10.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 10/21/2017] [Accepted: 10/23/2017] [Indexed: 01/09/2023]
Abstract
In cryogenic correlated light and electron microscopy (cryo-CLEM), frozen targets of interest are identified and located on EM grids by fluorescence microscopy and then imaged at higher resolution by cryo-EM. Whilst working with these methods, we discovered that a variety of mammalian cells exhibit strong punctate autofluorescence when imaged under cryogenic conditions (80 K). Autofluorescence originated from multilamellar bodies (MLBs) and secretory granules. Here we describe a method to distinguish fluorescent protein tags from these autofluorescent sources based on the narrower emission spectrum of the former. The method is first tested on mitochondria and then applied to examine the ultrastructural variability of secretory granules within insulin-secreting pancreatic beta-cell-derived INS-1E cells.
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Affiliation(s)
- Stephen D Carter
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
| | - Shrawan K Mageswaran
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
| | - Zachary J Farino
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - João I Mamede
- Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA
| | | | - Thomas J Hope
- Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA
| | - Zachary Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Cell Biology, University of Pittsburgh, PA 15213, USA.
| | - Grant J Jensen
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute (HHMI), California Institute of Technology, Pasadena, CA 91125, USA.
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40
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Eissa N, Hussein H, Kermarrec L, Grover J, Metz-Boutigue MHE, Bernstein CN, Ghia JE. Chromofungin Ameliorates the Progression of Colitis by Regulating Alternatively Activated Macrophages. Front Immunol 2017; 8:1131. [PMID: 28951733 PMCID: PMC5599789 DOI: 10.3389/fimmu.2017.01131] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/28/2017] [Indexed: 12/24/2022] Open
Abstract
Ulcerative colitis (UC) is characterized by a functional dysregulation of alternatively activated macrophage (AAM) and intestinal epithelial cells (IECs) homeostasis. Chromogranin-A (CHGA) secreted by neuroendocrine cells is implicated in intestinal inflammation and immune dysregulation. CHGA undergoes proteolytic processing to generate CHGA-derived peptides. Chromofungin (CHR: CHGA47–66) is a short CHGA-derived peptide encoded by CHGA Exon-IV and is involved in innate immune regulation, but the basis is poorly investigated. We investigated the expression of CHR in colonic tissue of patients with active UC and assessed the effects of the CHR in dextran sulfate sodium (DSS) colitis in mice and on macrophages and human colonic epithelial cells. We found that mRNA expression of CHR correlated positively with mRNA levels of AAM markers and gene expression of tight junction (TJ) proteins and negatively with mRNA levels of interleukin (IL)-8, IL-18, and collagen in patients with active UC. Moreover, AAM markers correlated positively with gene expression of TJ proteins and negatively with IL-8, IL-18, and collagen gene expression. Experimentally, intracolonic administration of CHR protected against DSS-induced colitis by priming macrophages into AAM, reducing colonic collagen deposition, and maintaining IECs homeostasis. This effect was associated with a significant increase of AAM markers, reduction of colonic IL-18 release and conservation of gene expression of TJ proteins. In vitro, CHR enhanced AAM polarization and increased the production of anti-inflammatory mediators. CHR-treated AAM conditioned medium increased Caco-2 cell migration, viability, proliferation, and mRNA levels of TJ proteins, and decreased oxidative stress-induced apoptosis and proinflammatory cytokines release. Direct CHR treatments had the same effect. In conclusion, CHR treatment reduces the severity of colitis and the inflammatory process via enhancing AAM functions and maintaining IECs homeostasis. CHR is involved in the pathogenesis of inflammation in experimental colitis. These findings provide insight into the mechanisms of colonic inflammation and could lead to new therapeutic strategies for UC.
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Affiliation(s)
- Nour Eissa
- Immunology Department, University of Manitoba, Winnipeg, MB, Canada.,Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
| | - Hayam Hussein
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Ohio State University, Columbus, OH, United States
| | | | - Jasmine Grover
- Immunology Department, University of Manitoba, Winnipeg, MB, Canada
| | - Marie-Hélène Et Metz-Boutigue
- INSERM U977, Biomatériaux et Ingéniérie tissulaire, Institut Leriche 2éme étage, Hôpital Civil, Porte de l'Hôpital, Strasbourg, France
| | - Charles N Bernstein
- Rady Faculty of Health Sciences, Department of Internal Medicine, Section of Gastroenterology, University of Manitoba, Winnipeg, MB, Canada.,University of Manitoba IBD Clinical and Research Centre, Winnipeg, MB, Canada
| | - Jean-Eric Ghia
- Immunology Department, University of Manitoba, Winnipeg, MB, Canada.,Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada.,Rady Faculty of Health Sciences, Department of Internal Medicine, Section of Gastroenterology, University of Manitoba, Winnipeg, MB, Canada.,University of Manitoba IBD Clinical and Research Centre, Winnipeg, MB, Canada
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41
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Determinants for selective transport of exogenously expressed cargo proteins into regulated and constitutive secretory pathways. J Oral Biosci 2017. [DOI: 10.1016/j.job.2017.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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42
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Troger J, Theurl M, Kirchmair R, Pasqua T, Tota B, Angelone T, Cerra MC, Nowosielski Y, Mätzler R, Troger J, Gayen JR, Trudeau V, Corti A, Helle KB. Granin-derived peptides. Prog Neurobiol 2017; 154:37-61. [PMID: 28442394 DOI: 10.1016/j.pneurobio.2017.04.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 04/10/2017] [Accepted: 04/16/2017] [Indexed: 12/14/2022]
Abstract
The granin family comprises altogether 7 different proteins originating from the diffuse neuroendocrine system and elements of the central and peripheral nervous systems. The family is dominated by three uniquely acidic members, namely chromogranin A (CgA), chromogranin B (CgB) and secretogranin II (SgII). Since the late 1980s it has become evident that these proteins are proteolytically processed, intragranularly and/or extracellularly into a range of biologically active peptides; a number of them with regulatory properties of physiological and/or pathophysiological significance. The aim of this comprehensive overview is to provide an up-to-date insight into the distribution and properties of the well established granin-derived peptides and their putative roles in homeostatic regulations. Hence, focus is directed to peptides derived from the three main granins, e.g. to the chromogranin A derived vasostatins, betagranins, pancreastatin and catestatins, the chromogranin B-derived secretolytin and the secretogranin II-derived secretoneurin (SN). In addition, the distribution and properties of the chromogranin A-derived peptides prochromacin, chromofungin, WE14, parastatin, GE-25 and serpinins, the CgB-peptide PE-11 and the SgII-peptides EM66 and manserin will also be commented on. Finally, the opposing effects of the CgA-derived vasostatin-I and catestatin and the SgII-derived peptide SN on the integrity of the vasculature, myocardial contractility, angiogenesis in wound healing, inflammatory conditions and tumors will be discussed.
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Affiliation(s)
- Josef Troger
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria.
| | - Markus Theurl
- Department of Internal Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Rudolf Kirchmair
- Department of Internal Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Teresa Pasqua
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Bruno Tota
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Tommaso Angelone
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Maria C Cerra
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Yvonne Nowosielski
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria
| | - Raphaela Mätzler
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria
| | - Jasmin Troger
- Department of Ophthalmology, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Vance Trudeau
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Angelo Corti
- Vita-Salute San Raffaele University and Division of Experimental Oncology, San Raffaele Scientific Institute, Milan, Italy
| | - Karen B Helle
- Department of Biomedicine, University of Bergen, Norway
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43
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Kaur H, Sparvoli D, Osakada H, Iwamoto M, Haraguchi T, Turkewitz AP. An endosomal syntaxin and the AP-3 complex are required for formation and maturation of candidate lysosome-related secretory organelles (mucocysts) in Tetrahymena thermophila. Mol Biol Cell 2017; 28:1551-1564. [PMID: 28381425 PMCID: PMC5449153 DOI: 10.1091/mbc.e17-01-0018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/22/2017] [Accepted: 03/28/2017] [Indexed: 12/14/2022] Open
Abstract
Lysosome-related organelles (LROs) are secretory organelles formed by convergence between secretory and endosomal trafficking pathways. In Tetrahymena, secretory vesicles that resemble dense core granules are a new class of LROs whose synthesis depends on a conserved syntaxin required for heterotypic fusion and AP-3 for maturation. The ciliate Tetrahymena thermophila synthesizes large secretory vesicles called mucocysts. Mucocyst biosynthesis shares features with dense core granules (DCGs) in animal cells, including proteolytic processing of cargo proteins during maturation. However, other molecular features have suggested relatedness to lysosome-related organelles (LROs). LROs, which include diverse organelles in animals, are formed via convergence of secretory and endocytic trafficking. Here we analyzed Tetrahymena syntaxin 7-like 1 (Stx7l1p), a Qa-SNARE whose homologues in other lineages are linked with vacuoles/LROs. Stx7l1p is targeted to both immature and mature mucocysts and is essential in mucocyst formation. In STX7L1-knockout cells, the two major classes of mucocyst cargo proteins localize independently, accumulating in largely nonoverlapping vesicles. Thus initial formation of immature mucocysts involves heterotypic fusion, in which a subset of mucocyst proteins is delivered via an endolysosomal compartment. Further, we show that subsequent maturation requires AP-3, a complex widely implicated in LRO formation. Knockout of the µ-subunit gene does not impede delivery of any known mucocyst cargo but nonetheless arrests mucocyst maturation. Our data argue that secretory organelles in ciliates may represent a new class of LROs and reveal key roles of an endosomal syntaxin and AP-3 in the assembly of this complex compartment.
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Affiliation(s)
- Harsimran Kaur
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Daniela Sparvoli
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Hiroko Osakada
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Masaaki Iwamoto
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
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44
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Bonnemaison ML, Duffy ME, Mains RE, Vogt S, Eipper BA, Ralle M. Copper, zinc and calcium: imaging and quantification in anterior pituitary secretory granules. Metallomics 2016; 8:1012-22. [PMID: 27426256 DOI: 10.1039/c6mt00079g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The anterior pituitary is specialized for the synthesis, storage and release of peptide hormones. The activation of inactive peptide hormone precursors requires a specific set of proteases and other post-translational processing enzymes. High levels of peptidylglycine α-amidating monooxygenase (PAM), an essential peptide processing enzyme, occur in the anterior pituitary. PAM, which converts glycine-extended peptides into amidated products, requires copper and zinc to support its two catalytic activities and calcium for structure. We used X-ray fluorescence microscopy on rat pituitary sections and inductively coupled plasma mass spectrometry on subcellular fractions prepared from rat anterior pituitary to localize and quantify copper, zinc and calcium. X-ray fluorescence microscopy indicated that the calcium concentration in pituitary tissue was about 2.5 mM, 10-times more than zinc and 50-times more than copper. Although no higher than cytosolic levels, secretory granule levels of copper exceeded PAM levels by a factor of 10. Atp7a, which transports copper into the lumen of the secretory pathway, was enriched in endosomes and Golgi, not in secretory granules. If Atp7a transfers copper directly to PAM, this pH-dependent process is likely to occur in Golgi and endosomes.
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Affiliation(s)
- Mathilde L Bonnemaison
- Department of Molecular Biology and Biophysics, UConn Health, 263 Farmington Avenue, Farmington, CT 06030, USA.
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45
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Bustos-Morán E, Blas-Rus N, Martín-Cófreces NB, Sánchez-Madrid F. Orchestrating Lymphocyte Polarity in Cognate Immune Cell-Cell Interactions. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 327:195-261. [PMID: 27692176 DOI: 10.1016/bs.ircmb.2016.06.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The immune synapse (IS) is a specialized structure established between different immune cells that fulfills several functions, including a role as a communication bridge. This intimate contact between a T cell and an antigen-presenting cell promotes the proliferation and differentiation of lymphocytes involved in the contact. T-cell activation requires the specific triggering of the T-cell receptor (TCR), which promotes the activation of different signaling pathways inducing the polarization of the T cell. During this process, different adhesion and signaling receptors reorganize at specialized membrane domains, concomitantly to the polarization of the tubulin and actin cytoskeletons, forming stable polarization platforms. The centrosome also moves toward the IS, driving the movement of different organelles, such as the biosynthetic, secretory, degrading machinery, and mitochondria, to sustain T-cell activation. A proper orchestration of all these events is essential for T-cell effector functions and the accomplishment of a complete immune response.
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Affiliation(s)
- Eugenio Bustos-Morán
- Vascular Pathophysiology Area, Spanish National Center of Cardiovascular Research (CNIC), Madrid, Spain
| | - Noelia Blas-Rus
- Department of Immunology, La Princesa Hospital, Autonomus University of Madrid (UAM), Health Research Institute of Princesa Hospital (ISS-IP), Madrid, Spain
| | - Noa Beatriz Martín-Cófreces
- Vascular Pathophysiology Area, Spanish National Center of Cardiovascular Research (CNIC), Madrid, Spain.,Department of Immunology, La Princesa Hospital, Autonomus University of Madrid (UAM), Health Research Institute of Princesa Hospital (ISS-IP), Madrid, Spain
| | - Francisco Sánchez-Madrid
- Vascular Pathophysiology Area, Spanish National Center of Cardiovascular Research (CNIC), Madrid, Spain.,Department of Immunology, La Princesa Hospital, Autonomus University of Madrid (UAM), Health Research Institute of Princesa Hospital (ISS-IP), Madrid, Spain
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46
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Topalidou I, Cattin-Ortolá J, Pappas AL, Cooper K, Merrihew GE, MacCoss MJ, Ailion M. The EARP Complex and Its Interactor EIPR-1 Are Required for Cargo Sorting to Dense-Core Vesicles. PLoS Genet 2016; 12:e1006074. [PMID: 27191843 PMCID: PMC4871572 DOI: 10.1371/journal.pgen.1006074] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/30/2016] [Indexed: 12/15/2022] Open
Abstract
The dense-core vesicle is a secretory organelle that mediates the regulated release of peptide hormones, growth factors, and biogenic amines. Dense-core vesicles originate from the trans-Golgi of neurons and neuroendocrine cells, but it is unclear how this specialized organelle is formed and acquires its specific cargos. To identify proteins that act in dense-core vesicle biogenesis, we performed a forward genetic screen in Caenorhabditis elegans for mutants defective in dense-core vesicle function. We previously reported the identification of two conserved proteins that interact with the small GTPase RAB-2 to control normal dense-core vesicle cargo-sorting. Here we identify several additional conserved factors important for dense-core vesicle cargo sorting: the WD40 domain protein EIPR-1 and the endosome-associated recycling protein (EARP) complex. By assaying behavior and the trafficking of dense-core vesicle cargos, we show that mutants that lack EIPR-1 or EARP have defects in dense-core vesicle cargo-sorting similar to those of mutants in the RAB-2 pathway. Genetic epistasis data indicate that RAB-2, EIPR-1 and EARP function in a common pathway. In addition, using a proteomic approach in rat insulinoma cells, we show that EIPR-1 physically interacts with the EARP complex. Our data suggest that EIPR-1 is a new interactor of the EARP complex and that dense-core vesicle cargo sorting depends on the EARP-dependent trafficking of cargo through an endosomal sorting compartment. Animal cells package and store many important signaling molecules in specialized compartments called dense-core vesicles. Molecules stored in dense-core vesicles include peptide hormones like insulin and small molecule neurotransmitters like dopamine. Defects in the release of these compounds can lead to a wide range of metabolic and mental disorders in humans, including diabetes, depression, and drug addiction. However, it is not well understood how dense-core vesicles are formed in cells and package the appropriate molecules. Here we use a genetic screen in the microscopic worm C. elegans to identify proteins that are important for early steps in the generation of dense-core vesicles, such as packaging the correct molecular cargos in the vesicles. We identify several factors that are conserved between worms and humans and point to a new role for a protein complex that had previously been shown to be important for controlling trafficking in other cellular compartments. The identification of this complex suggests new cellular trafficking events that may be important for the generation of dense-core vesicles.
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Affiliation(s)
- Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Jérôme Cattin-Ortolá
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Andrea L. Pappas
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Kirsten Cooper
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Gennifer E. Merrihew
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Michael J. MacCoss
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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47
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Cawley NX, Li Z, Loh YP. 60 YEARS OF POMC: Biosynthesis, trafficking, and secretion of pro-opiomelanocortin-derived peptides. J Mol Endocrinol 2016; 56:T77-97. [PMID: 26880796 PMCID: PMC4899099 DOI: 10.1530/jme-15-0323] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 12/15/2022]
Abstract
Pro-opiomelanocortin (POMC) is a prohormone that encodes multiple smaller peptide hormones within its structure. These peptide hormones can be generated by cleavage of POMC at basic residue cleavage sites by prohormone-converting enzymes in the regulated secretory pathway (RSP) of POMC-synthesizing endocrine cells and neurons. The peptides are stored inside the cells in dense-core secretory granules until released in a stimulus-dependent manner. The complexity of the regulation of the biosynthesis, trafficking, and secretion of POMC and its peptides reflects an impressive level of control over many factors involved in the ultimate role of POMC-expressing cells, that is, to produce a range of different biologically active peptide hormones ready for action when signaled by the body. From the discovery of POMC as the precursor to adrenocorticotropic hormone (ACTH) and β-lipotropin in the late 1970s to our current knowledge, the understanding of POMC physiology remains a monumental body of work that has provided insight into many aspects of molecular endocrinology. In this article, we describe the intracellular trafficking of POMC in endocrine cells, its sorting into dense-core secretory granules and transport of these granules to the RSP. Additionally, we review the enzymes involved in the maturation of POMC to its various peptides and the mechanisms involved in the differential processing of POMC in different cell types. Finally, we highlight studies pertaining to the regulation of ACTH secretion in the anterior and intermediate pituitary and POMC neurons of the hypothalamus.
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Affiliation(s)
- Niamh X Cawley
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Zhaojin Li
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Y Peng Loh
- Section on Cellular NeurobiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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48
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Amyloid formation of growth hormone in presence of zinc: Relevance to its storage in secretory granules. Sci Rep 2016; 6:23370. [PMID: 27004850 PMCID: PMC4804206 DOI: 10.1038/srep23370] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/04/2016] [Indexed: 11/16/2022] Open
Abstract
Amyloids are cross-β-sheet fibrillar aggregates, associated with various human diseases and native functions such as protein/peptide hormone storage inside secretory granules of neuroendocrine cells. In the current study, using amyloid detecting agents, we show that growth hormone (GH) could be stored as amyloid in the pituitary of rat. Moreover, to demonstrate the formation of GH amyloid in vitro, we studied various conditions (solvents, glycosaminoglycans, salts and metal ions) and found that in presence of zinc metal ions (Zn(II)), GH formed short curvy fibrils. The amyloidogenic nature of these fibrils was examined by Thioflavin T binding, Congo Red binding, transmission electron microscopy and X-ray diffraction. Our biophysical studies also suggest that Zn(II) initiates the early oligomerization of GH that eventually facilitates the fibrillation process. Furthermore, using immunofluorescence study of pituitary tissue, we show that GH in pituitary significantly co-localizes with Zn(II), suggesting the probable role of zinc in GH aggregation within secretory granules. We also found that GH amyloid formed in vitro is capable of releasing monomers. The study will help to understand the possible mechanism of GH storage, its regulation and monomer release from the somatotrophs of anterior pituitary.
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49
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Taatjes DJ, Roth J. The Histochemistry and Cell Biology omnium-gatherum: the year 2015 in review. Histochem Cell Biol 2016; 145:239-74. [DOI: 10.1007/s00418-016-1417-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2016] [Indexed: 02/07/2023]
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50
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Cawley NX, Rathod T, Young S, Lou H, Birch N, Loh YP. Carboxypeptidase E and Secretogranin III Coordinately Facilitate Efficient Sorting of Proopiomelanocortin to the Regulated Secretory Pathway in AtT20 Cells. Mol Endocrinol 2015; 30:37-47. [PMID: 26646096 DOI: 10.1210/me.2015-1166] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Proopiomelanocortin (POMC) is a multivalent prohormone that can be processed into at least 7 biologically active peptide hormones. Processing can begin in the trans-Golgi network (TGN) and continues in the secretory granules of the regulated secretory pathway (RSP). Sorting of POMC into these granules is a complex process. Previously, a membrane-associated form of carboxypeptidase E (CPE) was shown to bind to POMC and facilitate its trafficking into these granules. More recently, secretogranin III (SgIII) was also found to affect POMC trafficking. Here, we show by RNA silencing that CPE and SgIII play a synergistic role in the trafficking of POMC to granules of the RSP in AtT20 cells. Reduction of either protein resulted in increased constitutive secretion of POMC and chromogranin A, which was increased even further when both proteins were reduced together, indicative of missorting at the TGN. In SgIII-reduced cells, POMC accumulated in a compartment that cofractionated and colocalized with syntaxin 6, a marker of the TGN, on sucrose density gradients and in immunocytochemistry, respectively, indicating an accumulation of this protein in the presumed sorting compartment. Regulated secretion of ACTH, as a measure of sorting and processing of POMC in mature granules, was reduced in the SgIII down-regulated cells but was increased in the CPE down-regulated cells. These results suggest that multiple sorting systems exist, providing redundancy to ensure the important task of continuous and accurate trafficking of prohormones to the granules of the RSP for the production of peptide hormones.
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Affiliation(s)
- Niamh X Cawley
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Trushar Rathod
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Sigrid Young
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Hong Lou
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Nigel Birch
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
| | - Y Peng Loh
- Section on Cellular Neurobiology (N.X.C., T.R., S.Y., H.L., Y.P.L.), Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4480; and School of Biological Sciences (N.B.), Centre for Brain Research and Brain Research New Zealand, Rangahau Roro Aotearoa, University of Auckland, New Zealand
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