Activity of alpha-secretase as the common final effector of protein kinase C-dependent and -independent modulation of amyloid precursor protein metabolism

J Neurochem. 1999 Jun;72(6):2464-70. doi: 10.1046/j.1471-4159.1999.0722464.x.

Abstract

The metabolic fate of the amyloid precursor protein (APP) is one of the key factors in the pathogenesis of Alzheimer's disease (AD). A complex cellular mechanism regulates the rate at which the precursor is cleaved by alpha-secretase and released as soluble protein in the extracellular space. We show here that alpha-secretase constitutes the common final effector of several independent means of stimulation of soluble APP (sAPP) release. The release of sAPP by alpha-secretase resembles that of several other membrane-bound proteins with soluble counterparts, a process that is sensitive to matrix metalloprotease inhibitors. The hydroxamic acid-based compound KD-IX-73-4 inhibits phorbol ester-mediated sAPP release from COS cells with an IC50 of 8 microM, consistent with previous data for the same compound against leukocyte L-selectin shedding. Beyond direct protein kinase C (PKC) activation we show that KD-IX-73-4 inhibits also receptor-mediated sAPP release induced by carbachol in SH-SY5Y cells and by bradykinin in human skin fibroblasts, with the latter being a PKC-independent mechanism. Altogether these data suggest that all pharmacological means of stimulating sAPP release converge to a hydroxamic acid-based inhibitor-sensitive proteolytic enzyme. Moreover, because KD-IX-73-4 was effective in the inhibition of stimulated but not constitutive sAPP release, these data suggest the existence of different enzymes regulating the two metabolic pathways leading to sAPP secretion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid Precursor Protein Secretases
  • Amyloid beta-Peptides / metabolism*
  • Amyloid beta-Protein Precursor / metabolism*
  • Animals
  • Aspartic Acid Endopeptidases
  • Bradykinin / pharmacology
  • COS Cells
  • Carbachol / pharmacology
  • Cells, Cultured
  • Culture Media, Conditioned
  • Dipeptides / pharmacology
  • Endopeptidases / metabolism*
  • Enzyme Inhibitors / pharmacology
  • Fibroblasts / cytology
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Humans
  • Hydroxamic Acids / pharmacology
  • Neuroblastoma
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Protein Kinase C / metabolism*
  • Protein Processing, Post-Translational
  • Skin / cytology
  • Skin / drug effects
  • Skin / metabolism*
  • Tumor Cells, Cultured

Substances

  • Amyloid beta-Peptides
  • Amyloid beta-Protein Precursor
  • Culture Media, Conditioned
  • Dipeptides
  • Enzyme Inhibitors
  • Hydroxamic Acids
  • KD-IX 73-4
  • Phorbol 12,13-Dibutyrate
  • Carbachol
  • Protein Kinase C
  • Amyloid Precursor Protein Secretases
  • Endopeptidases
  • Aspartic Acid Endopeptidases
  • BACE1 protein, human
  • Bradykinin