Fatty acids increase presenilin-1 levels and γ-secretase activity in PSwt-1 cells

Abstract

Presenilin-1 (PS1) is an important determinant of the γ-secretase activity necessary for the generation of β-amyloid (Aβ), likely the central pathogenic molecule in Alzheimer's disease. Most presenilin is rapidly degraded, and determinants of the level of the active cleaved form are unknown. We examined the influence of fatty acids on PS1 levels and γ-secretase activity using stably transfected CHO cells that express human PS1 and the human amyloid precursor protein. Cells cultured with 0.4 mM oleic acid (OA), with 0.1 mM linoleic acid, or with a triglyceride emulsion expressed increased PS1 and Aβ. This effect was independent of any secondary increase in cellular cholesterol. Cells cultured in 0.4 mM OA also exhibited significantly increased γ-secretase activity. PS1 mRNA levels were unchanged, and pulse-chase experiments indicated that OA slowed presenilin holoprotein degradation. Nontransfected human neuroblastoma cells also showed increased presenilin when cultured in 0.4 mM OA. Lipids may be important biological determinants of PS1 level and γ-secretase activity.