title: Specific soluble oligomers of amyloid-β peptide undergo replication and form non-fibrillar aggregates in interfacial environments.
abstract: Aggregates of amyloid-β (Aβ) peptides have been implicated in the etiology of Alzheimer disease. Among the different forms of Aβ aggregates, low molecular weight species ranging between ~2- and 50-mers, also called "soluble oligomers," have emerged as the species responsible for early synaptic dysfunction and neuronal loss. Emerging evidence suggests that the neurotoxic oligomers need not be formed along the obligatory nucleation-dependant fibril formation pathway. In our earlier work, we reported the isolation of one such "off-pathway" 12-18-mer species of Aβ42 generated from fatty acids called large fatty acid-derived oligomers (LFAOs) (Kumar, A., Bullard, R. L., Patel, P., Paslay, L. C., Singh, D., Bienkiewicz, E. A., Morgan, S. E., and Rangachari, V. (2011) PLoS One 6, e18759). Here, we report the physiochemical aspects of LFAO-monomer interactions as well as LFAO-LFAO associations in the presence of interfaces. We discovered that LFAOs are a replicating strain of oligomers that recruit Aβ42 monomers and quantitatively convert them into LFAO assemblies at the expense of fibrils, a mechanism similar to prion propagation. We also found that in the presence of hexane-buffer or chloroform-buffer interfaces LFAOs are able to associate with themselves to form larger but non-fibrillar aggregates. These results further support the hypothesis that low molecular weight oligomers can be generated via non-fibril formation pathways. Furthermore, the unique replicating property of off-pathway oligomers may hold profound significance for Alzheimer disease pathology.
authors.affiliation: Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.forename: Lea C
authors.initials: LC
authors.lastname: Paslay
authors.forename: Daniel
authors.initials: D
authors.lastname: Lyons
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Morgan
authors.forename: John J
authors.initials: JJ
authors.lastname: Correia
authors.forename: Vijayaraghavan
authors.initials: V
authors.lastname: Rangachari
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D012995:Solubility
chemical_list: D016229:Amyloid beta-Peptides; D005227:Fatty Acids; D046912:Multiprotein Complexes; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)