Constitutive α- and β-secretase cleavages of the amyloid precursor protein are partially coupled in neurons, but not in frequently used cell lines

Neurobiol Dis. 2013 Jan;49:137-47. doi: 10.1016/j.nbd.2012.08.011. Epub 2012 Aug 24.

Abstract

Proteolytic cleavage of the amyloid precursor protein (APP) by the two proteases α- and β-secretases controls the generation of the amyloid β peptide (Aβ), a key player in Alzheimer's disease pathogenesis. The α-secretase ADAM10 and the β-secretase BACE1 have opposite effects on Aβ generation and are assumed to compete for APP as a substrate, such that their cleavages are inversely coupled. This concept was mainly demonstrated in studies using activation or overexpression of α- and β-secretases. Here, we report that this inverse coupling is not seen to the same extent upon inhibition of the endogenous proteases. Genetic and pharmacological inhibition of ADAM10 and BACE1 revealed that the endogenous, constitutive α-secretase cleavage of APP is largely uncoupled from β-secretase cleavage and Aβ generation in neuroglioma H4 cells and in neuronally differentiated SH-SY5Y cells. In contrast, inverse coupling was observed in primary cortical neurons. However, this coupling was not bidirectional. Inhibition of BACE1 increased ADAM10 cleavage of APP, but a reduction of ADAM10 activity did not increase the BACE1 cleavage of APP in the neurons. Our analysis shows that the inverse coupling of the endogenous α- and β-secretase cleavages depends on the cellular model and suggests that a reduction of ADAM10 activity is unlikely to increase the AD risk through increased β-secretase cleavage.

Keywords: Alpha-secretase; Alzheimer's disease; Amyloid precursor protein; Beta-secretase.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADAM Proteins / antagonists & inhibitors
  • ADAM Proteins / genetics
  • ADAM Proteins / metabolism
  • ADAM10 Protein
  • Amyloid Precursor Protein Secretases / antagonists & inhibitors
  • Amyloid Precursor Protein Secretases / genetics
  • Amyloid Precursor Protein Secretases / metabolism*
  • Amyloid beta-Protein Precursor / metabolism*
  • Animals
  • Aspartic Acid Endopeptidases / antagonists & inhibitors
  • Aspartic Acid Endopeptidases / genetics
  • Aspartic Acid Endopeptidases / metabolism
  • Cell Line, Tumor
  • Cells, Cultured
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / enzymology
  • Gene Knockdown Techniques
  • HEK293 Cells
  • Humans
  • Membrane Proteins / antagonists & inhibitors
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice, Knockout
  • Neurons / drug effects
  • Neurons / enzymology*
  • Protease Inhibitors / pharmacology

Substances

  • APP protein, human
  • Amyloid beta-Protein Precursor
  • Membrane Proteins
  • Protease Inhibitors
  • Amyloid Precursor Protein Secretases
  • Aspartic Acid Endopeptidases
  • BACE1 protein, human
  • Bace1 protein, mouse
  • ADAM Proteins
  • ADAM10 Protein
  • ADAM10 protein, human
  • Adam10 protein, mouse