Identification of Human Islet Amyloid Polypeptide as a BACE2 Substrate

PLoS One. 2016 Feb 3;11(2):e0147254. doi: 10.1371/journal.pone.0147254. eCollection 2016.

Abstract

Pancreatic amyloid formation by islet amyloid polypeptide (IAPP) is a hallmark pathological feature of type 2 diabetes. IAPP is stored in the secretory granules of pancreatic beta-cells and co-secreted with insulin to maintain glucose homeostasis. IAPP is innocuous under homeostatic conditions but imbalances in production or processing of IAPP may result in homodimer formation leading to the rapid production of cytotoxic oligomers and amyloid fibrils. The consequence is beta-cell dysfunction and the accumulation of proteinaceous plaques in and around pancreatic islets. Beta-site APP-cleaving enzyme 2, BACE2, is an aspartyl protease commonly associated with BACE1, a related homolog responsible for amyloid processing in the brain and strongly implicated in Alzheimer's disease. Herein, we identify two distinct sites of the mature human IAPP sequence that are susceptible to BACE2-mediated proteolytic activity. The result of proteolysis is modulation of human IAPP fibrillation and human IAPP protein degradation. These results suggest a potential therapeutic role for BACE2 in type 2 diabetes-associated hyperamylinaemia.

MeSH terms

  • Amino Acid Sequence
  • Amyloid Precursor Protein Secretases / antagonists & inhibitors
  • Amyloid Precursor Protein Secretases / metabolism*
  • Animals
  • Aspartic Acid Endopeptidases / antagonists & inhibitors
  • Aspartic Acid Endopeptidases / metabolism*
  • Cell Line
  • Diabetes Mellitus, Type 2 / genetics
  • Diabetes Mellitus, Type 2 / metabolism
  • Diabetes Mellitus, Type 2 / pathology
  • Humans
  • Insulin / metabolism
  • Insulin / pharmacology
  • Insulin-Secreting Cells / metabolism
  • Insulin-Secreting Cells / pathology
  • Islet Amyloid Polypeptide / chemistry
  • Islet Amyloid Polypeptide / genetics
  • Islet Amyloid Polypeptide / metabolism*
  • Mass Spectrometry
  • Mice
  • Molecular Sequence Data
  • Mutation
  • Plaque, Amyloid / metabolism
  • Proteolysis / drug effects
  • Recombinant Proteins
  • Substrate Specificity

Substances

  • Insulin
  • Islet Amyloid Polypeptide
  • Recombinant Proteins
  • Amyloid Precursor Protein Secretases
  • Aspartic Acid Endopeptidases
  • BACE2 protein, human
  • BACE1 protein, human

Grants and funding

All authors were employees of Amgen Inc. at the time of their contribution to this manuscript. The authors received no specific funding for this work.