title: Cholesterol-dependent gamma-secretase activity in buoyant cholesterol-rich membrane microdomains.
abstract: Buoyant membrane fractions containing presenilin 1 (PS1), an essential component of the gamma-secretase complex, and APP CTFbeta, a gamma-secretase substrate, can be isolated from cultured cells and brain by several different fractionation procedures that are compatible with in vitro gamma-secretase assays. Analysis of these gradients for amyloid beta protein (Abeta) and CTFgamma production indicated that gamma-secretase activity is predominantly localized in these buoyant membrane microdomains. Consistent with this localization, we find that gamma-secretase activity is cholesterol dependent. Depletion of membrane cholesterol completely inhibits gamma-secretase cleavage, which can be restored by cholesterol replacement. Thus, altering cholesterol levels may influence the development of Alzheimer's disease (AD) by influencing production and deposition of Abeta within cholesterol rich membrane microdomains.
authors.affiliation: Department of Neuroscience and Pharmacology, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, Florida 32224, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Wahrle
authors.forename: Pritam
authors.initials: P
authors.lastname: Das
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Nyborg
authors.forename: Chris
authors.initials: C
authors.lastname: McLendon
authors.forename: Mikio
authors.initials: M
authors.lastname: Shoji
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kawarabayashi
authors.forename: Linda H
authors.initials: LH
authors.lastname: Younkin
authors.forename: Steven G
authors.initials: SG
authors.lastname: Younkin
authors.forename: Todd E
authors.initials: TE
authors.lastname: Golde
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism; D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D002458:Cell Fractionation; D002784:Cholesterol / Q000378:metabolism*; D006224:Cricetinae; D010450:Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D053764:Presenilin-1
chemical_list: D016229:Amyloid beta-Peptides; D008565:Membrane Proteins; D053764:Presenilin-1; D002784:Cholesterol; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases