Journal Article

Proteasomal Degradation of Proinsulin Requires Derlin-2, HRD1 and p97

Hoeben, Rob C., Roep, Bart O., Hoelen, Hanneke, Torfs, Ellen C. W., Wiertz, Emmanuel J. H. J., de Koning, Eelco J., de Ru, Arnoud H., van Veelen, Peter A., Zaldumbide, Arnaud, van Leeuwen, Wouter F., Engelse, Marten A., Hassan, Chopie, Resssing, Maaike E., Lebbink, Robert Jan

2015

Overview

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.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Adenosine Triphosphatases - genetics / Adenosine Triphosphatases - immunology / Amino Acid Sequence / Antigen presentation / Antigens / Autoantigens - immunology / Beta cells / Biodegradation / Blood transfusions / CD8 antigen / CD8-Positive T-Lymphocytes - immunology / CD8-Positive T-Lymphocytes - pathology / Degradation / Diabetes / Diabetes mellitus / Diabetes mellitus (insulin dependent) / Diabetes Mellitus, Type 1 - immunology / Diabetes Mellitus, Type 1 - metabolism / Diabetes Mellitus, Type 1 - pathology / Endoplasmic reticulum / Endoplasmic Reticulum-Associated Degradation - genetics / Endoplasmic Reticulum-Associated Degradation - immunology / Epitopes / Epitopes - genetics / Epitopes - immunology / Genes, MHC Class I - immunology / Humans / Immunology / Insulin / Insulin-Secreting Cells - immunology / Insulin-Secreting Cells - metabolism / Lymphocytes T / Major histocompatibility complex / Membrane Proteins - genetics / Membrane Proteins - immunology / Molecular biology / Molecular chains / Nephrology / Nuclear Proteins - genetics / Nuclear Proteins - immunology / Peptides / Preproinsulin / Proinsulin - biosynthesis / Proinsulin - genetics / Proinsulin - immunology / Proteasome Endopeptidase Complex - genetics / Proteasome Endopeptidase Complex - metabolism / Proteasomes / Proteins / Proteolysis / Ubiquitin-Protein Ligases - genetics / Ubiquitin-Protein Ligases - immunology