Solid-phase synthesis and pathological evaluation of pyroglutamate amyloid-β_3-42 peptide

Pyroglutamate amyloid-β_3-42 (Aβ_pE3-42) is an N-terminally truncated and pyroglutamate-modified Aβ peptide retaining highly hydrophobic, amyloidogenic, and neurotoxic properties. In Alzheimer's disease (AD) patients, Aβ_pE3-42 peptides accumulate into oligomers and induce cellular toxicity and synaptic dysfunction. Aβ_pE3-42 aggregates further seed the formation of amyloid plaques, which are the pathological hallmarks of AD. Given that Aβ_pE3-42 peptides play critical roles in the development of neurodegeneration, a reliable and reproducible synthetic access to these peptides may support pathological and medicinal studies of AD. Here, we synthesized Aβ_pE3-42 peptides through the microwave-assisted solid-phase peptide synthesis (SPPS). Utilizing thioflavin T fluorescence assay and dot blotting analysis with anti-amyloid oligomer antibody, the amyloidogenic activity of synthesized Aβ_pE3-42 peptides was confirmed. We further observed the cytotoxicity of Aβ_pE3-42 aggregates in cell viability test. To examine the cognitive deficits induced by synthetic Aβ_pE3-42 peptides, Aβ_pE3-42 oligomers were intracerebroventricularly injected into imprinting control region mice and Y-maze and Morris water maze tests were performed. We found that Aβ_pE3-42 aggregates altered the expression level of postsynaptic density protein 95 in cortical lysates. Collectively, we produced Aβ_pE3-42 peptides in the microwave-assisted SPPS and evaluated the amyloidogenic and pathological function of the synthesized peptides.