APP binds DR6 to trigger axon pruning and neuron death via distinct caspases

Nature. 2009 Feb 19;457(7232):981-9. doi: 10.1038/nature07767.

Abstract

Naturally occurring axonal pruning and neuronal cell death help to sculpt neuronal connections during development, but their mechanistic basis remains poorly understood. Here we report that beta-amyloid precursor protein (APP) and death receptor 6 (DR6, also known as TNFRSF21) activate a widespread caspase-dependent self-destruction program. DR6 is broadly expressed by developing neurons, and is required for normal cell body death and axonal pruning both in vivo and after trophic-factor deprivation in vitro. Unlike neuronal cell body apoptosis, which requires caspase 3, we show that axonal degeneration requires caspase 6, which is activated in a punctate pattern that parallels the pattern of axonal fragmentation. DR6 is activated locally by an inactive surface ligand(s) that is released in an active form after trophic-factor deprivation, and we identify APP as a DR6 ligand. Trophic-factor deprivation triggers the shedding of surface APP in a beta-secretase (BACE)-dependent manner. Loss- and gain-of-function studies support a model in which a cleaved amino-terminal fragment of APP (N-APP) binds DR6 and triggers degeneration. Genetic support is provided by a common neuromuscular junction phenotype in mutant mice. Our results indicate that APP and DR6 are components of a neuronal self-destruction pathway, and suggest that an extracellular fragment of APP, acting via DR6 and caspase 6, contributes to Alzheimer's disease.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Retracted Publication

MeSH terms

  • Alzheimer Disease / metabolism
  • Amyloid beta-Protein Precursor / chemistry
  • Amyloid beta-Protein Precursor / metabolism*
  • Animals
  • Axons / metabolism*
  • Caspase 3 / metabolism
  • Caspase 6 / metabolism*
  • Caspases / metabolism*
  • Cell Death
  • Ligands
  • Mice
  • Neurons / cytology*
  • Neurons / metabolism*
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Protein Binding
  • Receptors, Tumor Necrosis Factor / metabolism*
  • Signal Transduction
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism

Substances

  • Amyloid beta-Protein Precursor
  • Bax protein, mouse
  • Ligands
  • Peptide Fragments
  • Receptors, Tumor Necrosis Factor
  • Tnfrsf21 protein, mouse
  • bcl-2-Associated X Protein
  • Caspase 3
  • Caspase 6
  • Caspases