Cellular Cholesterol Loss Impairs Synaptic Vesicle Mobility via the CAMK2/Synapsin-1 Signaling Pathway

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Neuronal cholesterol deficiency is implicated in Alzheimer's disease (AD) synaptopathy.
• Disrupted synaptic vesicle (SV) mobility is a hallmark of AD-related synaptopathy.

Purpose of the Study:

• To investigate the impact of cellular cholesterol deficiency on SV mobility.
• To elucidate the mechanisms linking cholesterol loss to AD synaptopathy.

Main Methods:

• Constructed DHCR24 knock-down/knock-in SHSY-5Y cell models.
• Utilized Filipin III staining and confocal microscopy for cholesterol visualization.
• Performed immunoblotting to quantify key proteins including DHCR24, CAMK-2, synapsin-1, and synaptophysin.

Main Results:

• DHCR24 knockdown reduced phosphorylated CAMK2 and synapsin-1, impairing SV mobility.
• Cholesterol loss downregulated caveolin-1 and synaptophysin expression.
• DHCR24 knockdown reversed these effects, suggesting lipid raft involvement.

Conclusions:

• Cellular cholesterol depletion impairs SV mobility via CAMK2-mediated synapsin-1 phosphorylation, potentially through lipid rafts.
• Reduced synaptophysin expression contributes to AD-related synaptopathy.
• Targeting cholesterol metabolism presents a potential therapeutic avenue for AD.