Inhibiting oxysterol-mitigated Aβ-peptide aggregation with cationic arginine rich mimetic peptides​

Seymour Haque¹, Victor de Paula¹, Deguo Du¹

1. Florida Atlantic University

Cholesterol homeostasis dysregulation is a key driver of Alzheimer’s disease (AD); excessive intracellular accumulation of cholesterol and oxysterols is observed to be neurotoxic by accelerating Aβ aggregation. Activation of LRP-1 via lipoprotein binding can be neuroprotective by promoting toxic amyloid-beta aggregate efflux in neurons. Consequently, our strategy involves synthesizing cationic-arginine rich peptides (CARPs) bound to an amphipathic ELK-helical domain serving as LRP-1 agonists while inhibiting Aβ aggregation. Various computational tools were utilized such as HADDOCK software to conduct molecular docking studies as well as VMD/NAMD to conduct molecular dynamics simulations of the mimetic-receptor complexes. Subsequent in-vitro studies such as ThT aggregation kinetic assays and circular dichroism (CD) spectroscopy were utilized to monitor amyloid-beta aggregation. Atomic force microscopy will be utilized to characterize fibril formation, while lipid vesicle studies will be utilized to monitor Aβ-membrane interactions. Key residues in the binding of these mimetic peptides to LRP-1 were identified using MD simulations; arginine residues substituted at certain atomic positions possess higher hydrogen-bond occupancies and more stable mimetic-receptor complexes. Certain CARP-mimetic peptides were shown to inhibit Aβ-aggregation in-vitro using CD spectroscopy and ThT aggregation kinetics assay, yielding more information on current peptide-mimetic leads. Future studies involve visualizing amyloid fibrils using AFM and testing the therapeutic efficacy of these peptides to halt AD progression and verify the agonistic activities of these mimetic peptides using a neuronal cell culture model. Various techniques such as fluorescence microscopy and cytotoxicity assays will be used to verify the efficacy of these peptides.