DLPC Liposomes Inhibit A beta Fibrillation and Remodel Preformed Fibrils Through a Detergent-like Mechanism

Abstract

The aggregation of amyloid-b (Ab) on neuronal lipid bilayers is implicated in the neurotoxicity associated with Alzheimer’s disease. It is suggested that the aggregation on lipid bilayers is accelerated. This aggregation, in turn, is capable of disrupting bilayer integrity which induces cell death. We have found, however, that lipid bilayers composed of dilauroyl phosphatidylcholine (DLPC) undergo a unique mechanism of disruption. Through a combination of fluorescence measurements, microscopy, CD spectroscopy, and solid state NMR we have found that DLPC liposomes are rapidly disrupted through interactions with monomeric and early oligomeric forms of Ab. This disruption generates free lipid which successfully impedes amyloid formation through a detergent-like mechanism and stabilizes nontoxic, off pathway oligomers. DLPC liposomes are also capable of remodeling preformed fibrils of Ab into on-pathway, toxic protofibrillar species. All previous evidence of membrane disruption by Ab has been the result of fibrillation, pointing to a unique interaction occurring at the surface of DLPC membranes which is capable of halting amyloid formation in the early stages.