Prevention of amyloid β fibril deposition on the synaptic membrane in the precuneus by ganglioside nanocluster-targeting inhibitors

Alzheimer's disease (AD), a progressive neurodegenerative condition, is one of the most common causes of dementia. Senile plaques, a hallmark of AD, are formed by the accumulation of amyloid β protein (Aβ), which starts to aggregate before the onset of the disease. Gangliosides, sialic acid-containing glycosphingolipids, play a key role in the formation of toxic Aβ aggregates. In membrane rafts, ganglioside-bound complexes (GAβ) act as nuclei for Aβ assembly, suggesting that GAβ is a promising target for AD therapy. The formation of GAβ-induced Aβ assemblies has been evaluated using reconstituted planar lipid membranes composed of synaptosomal plasma membrane (SPM) lipids extracted from human and mouse brains. Although the effects of gangliosides on Aβ accumulation in the precuneus have been established, effects on Aβ fibrils have not been determined. In this study, Aβ₄₂ fibrils on reconstituted membranes composed of SPM lipids prepared from the precuneus cortex of human autopsied brains were evaluated by atomic force microscopy. In particular, Aβ₄₂ accumulation, as well as the fibril number and size were higher for membranes with precuneus lipids than for membranes with calcarine cortex lipids. In addition, artificial peptide inhibitors targeting Aβ-sensitive ganglioside nanoclusters cleared Aβ assemblies on synaptic membranes in the brain, providing a novel therapeutic strategy for AD.