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Hummer BH, Carter T, Sellers BL, Triplett JD, Asensio CS. Identification of the functional domain of the dense core vesicle biogenesis factor HID-1. PLoS One 2023; 18:e0291977. [PMID: 37751424 PMCID: PMC10522040 DOI: 10.1371/journal.pone.0291977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 09/08/2023] [Indexed: 09/28/2023] Open
Abstract
Large dense core vesicles (LDCVs) mediate the regulated release of neuropeptides and peptide hormones. HID-1 is a trans-Golgi network (TGN) localized peripheral membrane protein contributing to LDCV formation. There is no information about HID-1 structure or domain architecture, and thus it remains unknown how HID-1 binds to the TGN and performs its function. We report that the N-terminus of HID-1 mediates membrane binding through a myristoyl group with a polybasic amino acid patch but lacks specificity for the TGN. In addition, we show that the C-terminus serves as the functional domain. Indeed, this isolated domain, when tethered to the TGN, can rescue the neuroendocrine secretion and sorting defects observed in HID-1 KO cells. Finally, we report that a point mutation within that domain, identified in patients with endocrine and neurological deficits, leads to loss of function.
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Affiliation(s)
- Blake H. Hummer
- Department of Biological Sciences, University of Denver, Denver, CO, United States of America
| | - Theodore Carter
- Department of Biological Sciences, University of Denver, Denver, CO, United States of America
| | - Breanna L. Sellers
- Department of Biological Sciences, University of Denver, Denver, CO, United States of America
| | - Jenna D. Triplett
- Department of Biological Sciences, University of Denver, Denver, CO, United States of America
| | - Cedric S. Asensio
- Department of Biological Sciences, University of Denver, Denver, CO, United States of America
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2
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Asensio CS. Imaging Secretory Granule Budding from the Trans-Golgi Network Using Retention Using Selective Hook (RUSH). Methods Mol Biol 2022; 2473:23-28. [PMID: 35819756 DOI: 10.1007/978-1-0716-2209-4_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The retention using selective hook (RUSH) system enables us to synchronize and visualize the movement of cargoes along the secretory pathway. A fluorescently tagged cargo of interest is retained in the endoplasmic reticulum and released in a biotin-dependent manner. Here, we report a detailed protocol describing the steps necessary to perform RUSH experiments to study secretory granule biogenesis at the trans-Golgi network (TGN).
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Affiliation(s)
- Cedric S Asensio
- Department of Biological Sciences, University of Denver, Denver, CO, USA.
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3
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van der Welle REN, Jobling R, Burns C, Sanza P, van der Beek JA, Fasano A, Chen L, Zwartkruis FJ, Zwakenberg S, Griffin EF, ten Brink C, Veenendaal T, Liv N, van Ravenswaaij‐Arts CMA, Lemmink HH, Pfundt R, Blaser S, Sepulveda C, Lozano AM, Yoon G, Santiago‐Sim T, Asensio CS, Caldwell GA, Caldwell KA, Chitayat D, Klumperman J. Neurodegenerative VPS41 variants inhibit HOPS function and mTORC1-dependent TFEB/TFE3 regulation. EMBO Mol Med 2021; 13:e13258. [PMID: 33851776 PMCID: PMC8103106 DOI: 10.15252/emmm.202013258] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 02/19/2021] [Accepted: 02/22/2021] [Indexed: 11/09/2022] Open
Abstract
Vacuolar protein sorting 41 (VPS41) is as part of the Homotypic fusion and Protein Sorting (HOPS) complex required for lysosomal fusion events and, independent of HOPS, for regulated secretion. Here, we report three patients with compound heterozygous mutations in VPS41 (VPS41S285P and VPS41R662* ; VPS41c.1423-2A>G and VPS41R662* ) displaying neurodegeneration with ataxia and dystonia. Cellular consequences were investigated in patient fibroblasts and VPS41-depleted HeLa cells. All mutants prevented formation of a functional HOPS complex, causing delayed lysosomal delivery of endocytic and autophagic cargo. By contrast, VPS41S285P enabled regulated secretion. Strikingly, loss of VPS41 function caused a cytosolic redistribution of mTORC1, continuous nuclear localization of Transcription Factor E3 (TFE3), enhanced levels of LC3II, and a reduced autophagic response to nutrient starvation. Phosphorylation of mTORC1 substrates S6K1 and 4EBP1 was not affected. In a C. elegans model of Parkinson's disease, co-expression of VPS41S285P /VPS41R662* abolished the neuroprotective function of VPS41 against α-synuclein aggregates. We conclude that the VPS41 variants specifically abrogate HOPS function, which interferes with the TFEB/TFE3 axis of mTORC1 signaling, and cause a neurodegenerative disease.
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Affiliation(s)
- Reini E N van der Welle
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Rebekah Jobling
- Department of PediatricsDivision of Clinical and Metabolic GeneticsThe Hospital for Sick ChildrenUniversity of TorontoTorontoONCanada
| | - Christian Burns
- Department of Biological SciencesDivision of Natural Sciences and MathematicsUniversity of DenverDenverCOUSA
| | - Paolo Sanza
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Jan A van der Beek
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Alfonso Fasano
- Edmond J. Safra Program in Parkinson’s DiseaseMorton and Gloria Shulman Movement Disorders ClinicToronto Western Hospital, UHNTorontoONCanada
- Division of NeurologyUniversity of TorontoTorontoONCanada
- Krembil Brain InstituteTorontoONCanada
- Center for Advancing Neurotechnological Innovation to Application (CRANIA)TorontoONCanada
| | - Lan Chen
- Department of Biological SciencesDivision of Natural Sciences and MathematicsUniversity of DenverDenverCOUSA
| | - Fried J Zwartkruis
- Section Molecular Cancer ResearchCenter for Molecular MedicineUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Susan Zwakenberg
- Section Molecular Cancer ResearchCenter for Molecular MedicineUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Edward F Griffin
- Department of Biological SciencesThe University of AlabamaTuscaloosaALUSA
- Department of NeurologyCenter for Neurodegeneration and Experimental TherapeuticsNathan Shock Center for Basic Research in the Biology of AgingUniversity of Alabama at Birmingham School of MedicineBirminghamALUSA
| | - Corlinda ten Brink
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Tineke Veenendaal
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Nalan Liv
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | | | - Henny H Lemmink
- Department of GeneticsUniversity Medical Center GroningenUniversity of GroningenGroningenThe Netherlands
| | - Rolph Pfundt
- Department of Human GeneticsRadboud University Medical CenterNijmegenThe Netherlands
| | - Susan Blaser
- Department of Diagnostic ImagingHospital for Sick ChildrenTorontoONCanada
| | - Carolina Sepulveda
- Edmond J. Safra Program in Parkinson’s DiseaseMorton and Gloria Shulman Movement Disorders ClinicToronto Western Hospital, UHNTorontoONCanada
- Division of NeurologyUniversity of TorontoTorontoONCanada
| | - Andres M Lozano
- Krembil Brain InstituteTorontoONCanada
- Center for Advancing Neurotechnological Innovation to Application (CRANIA)TorontoONCanada
- Department of NeurosurgeryToronto Western Hospital, UHNTorontoONCanada
- University of TorontoTorontoONCanada
| | - Grace Yoon
- Department of PediatricsDivision of Clinical and Metabolic GeneticsThe Hospital for Sick ChildrenUniversity of TorontoTorontoONCanada
| | | | - Cedric S Asensio
- Department of Biological SciencesDivision of Natural Sciences and MathematicsUniversity of DenverDenverCOUSA
| | - Guy A Caldwell
- Department of Biological SciencesThe University of AlabamaTuscaloosaALUSA
- Department of NeurologyCenter for Neurodegeneration and Experimental TherapeuticsNathan Shock Center for Basic Research in the Biology of AgingUniversity of Alabama at Birmingham School of MedicineBirminghamALUSA
| | - Kim A Caldwell
- Department of Biological SciencesThe University of AlabamaTuscaloosaALUSA
- Department of NeurologyCenter for Neurodegeneration and Experimental TherapeuticsNathan Shock Center for Basic Research in the Biology of AgingUniversity of Alabama at Birmingham School of MedicineBirminghamALUSA
| | - David Chitayat
- Department of PediatricsDivision of Clinical and Metabolic GeneticsThe Hospital for Sick ChildrenUniversity of TorontoTorontoONCanada
- The Prenatal Diagnosis and Medical Genetics ProgramDepartment of Obstetrics and GynecologyUniversity of TorontoTorontoONCanada
| | - Judith Klumperman
- Section Cell BiologyCenter for Molecular MedicineInstitute of BiomembranesUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
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4
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Burns CH, Yau B, Rodriguez A, Triplett J, Maslar D, An YS, van der Welle REN, Kossina RG, Fisher MR, Strout GW, Bayguinov PO, Veenendaal T, Chitayat D, Fitzpatrick JAJ, Klumperman J, Kebede MA, Asensio CS. Pancreatic β-Cell-Specific Deletion of VPS41 Causes Diabetes Due to Defects in Insulin Secretion. Diabetes 2021; 70:436-448. [PMID: 33168621 PMCID: PMC7881869 DOI: 10.2337/db20-0454] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 11/03/2020] [Indexed: 12/14/2022]
Abstract
Insulin secretory granules (SGs) mediate the regulated secretion of insulin, which is essential for glucose homeostasis. The basic machinery responsible for this regulated exocytosis consists of specific proteins present both at the plasma membrane and on insulin SGs. The protein composition of insulin SGs thus dictates their release properties, yet the mechanisms controlling insulin SG formation, which determine this molecular composition, remain poorly understood. VPS41, a component of the endolysosomal tethering homotypic fusion and vacuole protein sorting (HOPS) complex, was recently identified as a cytosolic factor involved in the formation of neuroendocrine and neuronal granules. We now find that VPS41 is required for insulin SG biogenesis and regulated insulin secretion. Loss of VPS41 in pancreatic β-cells leads to a reduction in insulin SG number, changes in their transmembrane protein composition, and defects in granule-regulated exocytosis. Exploring a human point mutation, identified in patients with neurological but no endocrine defects, we show that the effect on SG formation is independent of HOPS complex formation. Finally, we report that mice with a deletion of VPS41 specifically in β-cells develop diabetes due to severe depletion of insulin SG content and a defect in insulin secretion. In sum, our data demonstrate that VPS41 contributes to glucose homeostasis and metabolism.
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Affiliation(s)
| | - Belinda Yau
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
| | | | - Jenna Triplett
- Department of Biological Sciences, University of Denver, Denver, CO
| | - Drew Maslar
- Department of Biological Sciences, University of Denver, Denver, CO
| | - You Sun An
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
| | - Reini E N van der Welle
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Ross G Kossina
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Max R Fisher
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Gregory W Strout
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Peter O Bayguinov
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Tineke Veenendaal
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - David Chitayat
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Ontario, Canada
| | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
- Departments of Neuroscience and Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Judith Klumperman
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Melkam A Kebede
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
| | - Cedric S Asensio
- Department of Biological Sciences, University of Denver, Denver, CO
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5
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Hummer BH, Maslar D, Soltero-Gutierrez M, de Leeuw NF, Asensio CS. Differential sorting behavior for soluble and transmembrane cargoes at the trans-Golgi network in endocrine cells. Mol Biol Cell 2019; 31:157-166. [PMID: 31825717 PMCID: PMC7001476 DOI: 10.1091/mbc.e19-10-0561] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Regulated secretion of neuropeptides and peptide hormones by secretory granules (SGs) is central to physiology. Formation of SGs occurs at the trans-Golgi network (TGN) where their soluble cargo aggregates to form a dense core, but the mechanisms controlling the sorting of regulated secretory cargoes (soluble and transmembrane) away from constitutively secreted proteins remain unclear. Optimizing the use of the retention using selective hooks method in (neuro-)endocrine cells, we now quantify TGN budding kinetics of constitutive and regulated secretory cargoes. We further show that, by monitoring two cargoes simultaneously, it becomes possible to visualize sorting to the constitutive and regulated secretory pathways in real time. Further analysis of the localization of SG cargoes immediately after budding from the TGN revealed that, surprisingly, the bulk of two studied transmembrane SG cargoes (phogrin and VMAT2) does not sort directly onto SGs during budding, but rather exit the TGN into nonregulated vesicles to get incorporated to SGs at a later step. This differential behavior of soluble and transmembrane cargoes suggests a more complex model of SG biogenesis than anticipated.
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Affiliation(s)
| | | | | | - Noah F de Leeuw
- Department of Physics and Astronomy, University of Denver, Denver, CO 80210
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Topalidou I, Cattin-Ortolá J, Hummer B, Asensio CS, Ailion M. EIPR1 controls dense-core vesicle cargo retention and EARP complex localization in insulin-secreting cells. Mol Biol Cell 2019; 31:59-79. [PMID: 31721635 PMCID: PMC6938272 DOI: 10.1091/mbc.e18-07-0469] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dense-core vesicles (DCVs) are secretory vesicles found in neurons and endocrine cells. DCVs package and release cargoes including neuropeptides, biogenic amines, and peptide hormones. We recently identified the endosome-associated recycling protein (EARP) complex and the EARP-interacting-protein EIPR-1 as proteins important for controlling levels of DCV cargoes in Caenorhabditis elegans neurons. Here we determine the role of mammalian EIPR1 in insulinoma cells. We find that in Eipr1 KO cells, there is reduced insulin secretion, and mature DCV cargoes such as insulin and carboxypeptidase E (CPE) accumulate near the trans-Golgi network and are not retained in mature DCVs in the cell periphery. In addition, we find that EIPR1 is required for the stability of the EARP complex subunits and for the localization of EARP and its association with membranes, but EIPR1 does not affect localization or function of the related Golgi-associated retrograde protein (GARP) complex. EARP is localized to two distinct compartments related to its function: an endosomal compartment and a DCV biogenesis-related compartment. We propose that EIPR1 functions with EARP to control both endocytic recycling and DCV maturation.
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Affiliation(s)
- Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | | | - Blake Hummer
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Cedric S Asensio
- Department of Biological Sciences, University of Denver, Denver, CO 80210
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, WA 98195
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Silm K, Yang J, Marcott PF, Asensio CS, Eriksen J, Guthrie DA, Newman AH, Ford CP, Edwards RH. Synaptic Vesicle Recycling Pathway Determines Neurotransmitter Content and Release Properties. Neuron 2019; 102:786-800.e5. [PMID: 31003725 PMCID: PMC6541489 DOI: 10.1016/j.neuron.2019.03.031] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 01/28/2019] [Accepted: 03/19/2019] [Indexed: 01/03/2023]
Abstract
In contrast to temporal coding by synaptically acting neurotransmitters such as glutamate, neuromodulators such as monoamines signal changes in firing rate. The two modes of signaling have been thought to reflect differences in release by different cells. We now find that midbrain dopamine neurons release glutamate and dopamine with different properties that reflect storage in different synaptic vesicles. The vesicles differ in release probability, coupling to presynaptic Ca2+ channels and frequency dependence. Although previous work has attributed variation in these properties to differences in location or cytoskeletal association of synaptic vesicles, the release of different transmitters shows that intrinsic differences in vesicle identity drive different modes of release. Indeed, dopamine but not glutamate vesicles depend on the adaptor protein AP-3, revealing an unrecognized linkage between the pathway of synaptic vesicle recycling and the properties of exocytosis. Storage of the two transmitters in different vesicles enables the transmission of distinct signals.
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Affiliation(s)
- Kätlin Silm
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Jing Yang
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Pamela F Marcott
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Cedric S Asensio
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Jacob Eriksen
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Daryl A Guthrie
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program, Baltimore, MD 21224, USA
| | - Amy H Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program, Baltimore, MD 21224, USA
| | - Christopher P Ford
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Robert H Edwards
- Departments of Neurology and Physiology, Graduate Programs in Neuroscience and Cell Biology, Kavli Institute for Fundamental Neuroscience, Weill Institute for the Neurosciences, UCSF School of Medicine, San Francisco, CA 94143, USA.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Abstract
One of the most powerful ways to test the function of a protein is to characterize the consequences of its deletion. In the past, this has involved inactivation of the gene by homologous recombination either in the germline or later through conditional deletion. RNA interference (RNAi) provides an alternative way to knock down proteins, but both of these approaches have their limitations. Recently, the CRISPR/Cas9 system has suggested another way to selectively inactivate genes. We have now tested this system in postmitotic neurons by targeting two well-characterized synaptic proteins, the obligatory GluN1 subunit of the NMDA receptor and the GluA2 subunit of the AMPA receptor. Expression of CRISPR/Cas9 in hippocampal slice cultures completely eliminated NMDA receptor and GluA2 function. CRISPR/Cas9 thus provides a powerful tool to study the function of synaptic proteins.
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Affiliation(s)
- Salvatore Incontro
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Cedric S Asensio
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Robert H Edwards
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Roger A Nicoll
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA.
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10
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Abstract
OBJECTIVE To investigate the impact of beta-adrenoceptor deficiency on the metabolic effects of leptin. MEASUREMENTS Leptin was infused subcutaneously through an osmotic minipump in wild-type (WT) and beta(1)/beta(2)/beta(3)-adrenoceptor knockout (beta-less) mice and its effects on food intake, energy expenditure, carbohydrate and lipid utilization as well as on the levels of expression of the brown adipose tissue (BAT), thermogenic marker uncoupling protein-1 (UCP1) and type II deiodinase (D2) mRNAs were compared. RESULTS Leptin treatment decreased food intake by 23% in both the WT and the beta-less mice. In pair-fed animals being used as controls, leptin treatment was found to increase energy expenditure in WT, but not in beta-less mice. No difference was observed in carbohydrate or fat utilization between leptin-treated WT and beta-less mice. Leptin increased UCP1 and D2 mRNA levels in WT mouse BAT 1.7- and 3-fold, respectively, but had no effect on the expression of these genes in beta-less mouse BAT. CONCLUSION The stimulatory effects of leptin on oxygen consumption, BAT UCP1 and D2 expression require functional beta-adrenoceptors, but its inhibitory effect on food intake and its stimulatory effect on fat utilization is independent of the beta-adrenoceptor signalling.
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Affiliation(s)
- C S Asensio
- Department of Cell Physiology and Metabolism, Medical University Centre, Geneva, Switzerland.
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