title: The 'Arctic' APP mutation (E693G) causes Alzheimer's disease by enhanced Abeta protofibril formation.
abstract: Several pathogenic Alzheimer's disease (AD) mutations have been described, all of which cause increased amyloid beta-protein (Abeta) levels. Here we present studies of a pathogenic amyloid precursor protein (APP) mutation, located within the Abeta sequence at codon 693 (E693G), that causes AD in a Swedish family. Carriers of this 'Arctic' mutation showed decreased Abeta42 and Abeta40 levels in plasma. Additionally, low levels of Abeta42 were detected in conditioned media from cells transfected with APPE693G. Fibrillization studies demonstrated no difference in fibrillization rate, but Abeta with the Arctic mutation formed protofibrils at a much higher rate and in larger quantities than wild-type (wt) Abeta. The finding of increased protofibril formation and decreased Abeta plasma levels in the Arctic AD may reflect an alternative pathogenic mechanism for AD involving rapid Abeta protofibril formation leading to accelerated buildup of insoluble Abeta intra- and/or extracellularly.
authors.affiliation: Karolinska Institutet, Department of Neurotec, Geriatric Medicine, Novum KFC, S-141 86 Huddinge, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Nilsberth
authors.forename: A
authors.initials: A
authors.lastname: Westlind-Danielsson
authors.forename: C B
authors.initials: CB
authors.lastname: Eckman
authors.forename: M M
authors.initials: MM
authors.lastname: Condron
authors.forename: K
authors.initials: K
authors.lastname: Axelman
authors.forename: C
authors.initials: C
authors.lastname: Forsell
authors.forename: C
authors.initials: C
authors.lastname: Stenh
authors.forename: J
authors.initials: J
authors.lastname: Luthman
authors.forename: D B
authors.initials: DB
authors.lastname: Teplow
authors.forename: S G
authors.initials: SG
authors.lastname: Younkin
authors.forename: J
authors.initials: J
authors.lastname: Näslund
authors.forename: L
authors.initials: L
authors.lastname: Lannfelt
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics*; D016229:Amyloid beta-Peptides / Q000097:blood / Q000737:chemistry / Q000502:physiology*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics*; D002460:Cell Line / Q000378:metabolism; D003470:Culture Media / Q000378:metabolism; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D009154:Mutation / Q000502:physiology*; D010375:Pedigree; D010446:Peptide Fragments / Q000502:physiology; D013548:Sweden
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D003470:Culture Media; D010446:Peptide Fragments