title: Proteasomal Degradation of Proinsulin Requires Derlin-2, HRD1 and p97.
abstract: Patients with type 1 diabetes (T1D) suffer from beta-cell destruction by CD8+ T-cells that have preproinsulin as an important target autoantigen. It is of great importance to understand the molecular mechanism underlying the processing of preproinsulin into these CD8+ T-cell epitopes. We therefore studied a pathway that may contribute to the production of these antigenic peptides: degradation of proinsulin via ER associated protein degradation (ERAD). Analysis of the MHC class I peptide ligandome confirmed the presentation of the most relevant MHC class I-restricted diabetogenic epitopes in our cells: the signal peptide-derived sequence A15-A25 and the insulin B-chain epitopes H29-A38 and H34-V42. We demonstrate that specific silencing of Derlin-2, p97 and HRD1 by shRNAs increases steady state levels of proinsulin. This indicates that these ERAD constituents are critically involved in proinsulin degradation and may therefore also play a role in subsequent antigen generation. These ERAD proteins therefore represent interesting targets for novel therapies aiming at the reduction and possibly also prevention of beta-cell directed auto-immune reactions in T1D.
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Hanneke
authors.initials: H
authors.lastname: Hoelen
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Zaldumbide
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Wouter F
authors.initials: WF
authors.lastname: van Leeuwen
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Ellen C W
authors.initials: EC
authors.lastname: Torfs
authors.affiliation: Department of Nephrology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Marten A
authors.initials: MA
authors.lastname: Engelse
authors.affiliation: Department of Immunohematology & Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Chopie
authors.initials: C
authors.lastname: Hassan
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: Lebbink
authors.affiliation: Department of Nephrology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Eelco J
authors.initials: EJ
authors.lastname: de Koning
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands; Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Maaike E
authors.initials: ME
authors.lastname: Resssing
authors.affiliation: Department of Immunohematology & Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Arnoud H
authors.initials: AH
authors.lastname: de Ru
authors.affiliation: Department of Immunohematology & Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Peter A
authors.initials: PA
authors.lastname: van Veelen
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Rob C
authors.initials: RC
authors.lastname: Hoeben
authors.affiliation: Department of Immunohematology & Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Bart O
authors.initials: BO
authors.lastname: Roep
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Emmanuel J H J
authors.initials: EJ
authors.lastname: Wiertz
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000276:immunology; D000595:Amino Acid Sequence; D001324:Autoantigens / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D060746:Endoplasmic Reticulum-Associated Degradation / Q000235:genetics / Q000276:immunology; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D005805:Genes, MHC Class I / Q000276:immunology; D006801:Humans; D050417:Insulin-Secreting Cells / Q000276:immunology / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology; D009687:Nuclear Proteins / Q000235:genetics* / Q000276:immunology; D011384:Proinsulin / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000276:immunology
chemical_list: D001324:Autoantigens; C513305:DERL2 protein, human; D000939:Epitopes; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011384:Proinsulin; C482345:SYVN1 protein, human; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C404942:p97 ATPase