The cholesterol ester cycle regulates signalling complexes and synapse damage caused by amyloid-β

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Cholesterol is crucial for cellular signalling platforms.
• Amyloid-β (Aβ) oligomers, implicated in Alzheimer's disease, bind to cellular prion proteins (PrP^C) in synaptosomes.
• This binding increases cholesterol, recruits cytoplasmic phospholipase A₂ (cPLA₂) to lipid rafts, and activates cPLA₂.

Purpose of the Study:

• To investigate the role of the cholesterol ester cycle in regulating Aβ-PrP^C complex formation and subsequent signalling.
• To determine the impact of cholesterol esterification and hydrolysis on Aβ-induced synapse damage.

Main Methods:

• Studied the effect of Aβ on cholesterol ester hydrolases and esterification in synaptosomes.
• Examined the impact of modulating the cholesterol ester cycle on Aβ-PrP^C complex stability.
• Investigated the effects of cholesterol ester hydrolase inhibitors and cholesterol esterification inhibitors on Aβ-induced synapse damage in cultured neurons.

Main Results:

• Aβ activated cholesterol ester hydrolases, releasing cholesterol, stabilizing Aβ-PrP^C complexes, and activating cPLA₂.
• Cholesterol esterification reduced cholesterol, dispersed Aβ-PrP^C complexes, and protected neurons from Aβ-induced synapse damage.
• Inhibition of cholesterol esterification exacerbated Aβ-induced synapse damage.

Conclusions:

• The cholesterol ester cycle is a key regulator of Aβ-induced signalling platform dispersal.
• Esterification of cholesterol is critical for deactivating signalling pathways involved in cPLA₂ activation and synapse degeneration.
• Targeting the cholesterol ester cycle may offer a therapeutic strategy for Alzheimer's disease by preventing synapse damage.