Large quantities of Abeta peptide are constitutively released during amyloid precursor protein metabolism in vivo and in vitro.

Published

Journal Article

The metabolism of the amyloid precursor protein (APP) has been extensively investigated because its processing generates the amyloid-β-peptide (Aβ), which is a likely cause of Alzheimer disease. Much prior research has focused on APP processing using transgenic constructs and heterologous cell lines. Work to date in native neuronal cultures suggests that Aβ is produced in very large amounts. We sought to investigate APP metabolism and Aβ production simultaneously under more physiological conditions in vivo and in vitro using cultured rat cortical neurons and live pigs. We found in cultured neurons that both APP and Aβ are secreted rapidly and at extremely high rates into the extracellular space (2-4 molecules/neuron/s for Aβ). Little APP is degraded outside of the pathway that leads to extracellular release. Two metabolic pools of APP are identified, one that is metabolized extremely rapidly (t1/2;) = 2.2 h), and another, surface pool, composed of both synaptic and extrasynaptic elements, that turns over very slowly. Aβ release and accumulation in the extracellular medium can be accounted for stoichiometrically by the extracellular release of β-cleaved forms of the APP ectodomain. Two α-cleavages of APP occur for every β-cleavage. Consistent with the results seen in cultured neurons, an extremely high rate of Aβ production and secretion from the brain was seen in juvenile pigs. In summary, our experiments show an enormous and rapid production and extracellular release of Aβ and the soluble APP ectodomain. A small, slowly metabolized, surface pool of full-length APP is also identified.

Full Text

Duke Authors

Cited Authors

  • Moghekar, A; Rao, S; Li, M; Ruben, D; Mammen, A; Tang, X; O'Brien, RJ

Published Date

  • May 6, 2011

Published In

Volume / Issue

  • 286 / 18

Start / End Page

  • 15989 - 15997

PubMed ID

  • 21454701

Pubmed Central ID

  • 21454701

Electronic International Standard Serial Number (EISSN)

  • 1083-351X

Digital Object Identifier (DOI)

  • 10.1074/jbc.M110.191262

Language

  • eng

Conference Location

  • United States