Cyclization of Peptides Enhances the Inhibitory Activity against Ganglioside-Induced Aβ Fibril Formation

Area of Science:

• Neuroscience
• Biochemistry
• Drug Discovery

Background:

• Alzheimer's disease (AD) is a leading cause of dementia, characterized by amyloid β-protein (Aβ) aggregation.
• Aβ assembly on cell membranes is initiated by interactions with gangliosides like GM1, forming toxic fibrils.
• Previous work identified a GM1 cluster-binding peptide (GCBP) that inhibits Aβ assembly.

Purpose of the Study:

• To design and synthesize novel cyclic peptides derived from GCBP.
• To evaluate the binding affinity, specificity, and inhibitory potential of these cyclic peptides against Aβ assembly.

Main Methods:

• Cyclization of cysteine-substituted GCBP mutants via disulfide bond formation.
• Affinity assays and surface topography analysis to assess membrane binding and nanocluster recognition.
• Inhibitory kinetic assays to determine the efficacy (IC50) against Aβ fibril formation.

Main Results:

• A cyclic peptide mutant exhibited enhanced affinity for GM1-containing membranes and specifically recognized GM1 nanoclusters.
• The cyclic peptide demonstrated potent inhibition of Aβ fibril formation with an IC50 of 1.2 fM, significantly outperforming GCBP.
• The cyclic peptide also cleared existing Aβ fibrils and suppressed toxic Aβ assembly.

Conclusions:

• The developed cyclic peptide is a highly effective inhibitor of ganglioside-induced Aβ assembly.
• This peptide represents a potential novel therapeutic agent for Alzheimer's disease.
• Targeting ganglioside nanoclusters offers a promising strategy for inhibiting Aβ pathogenesis.