Synaptotagmins interact with APP and promote Aβ generation

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Alzheimer's disease (AD) is characterized by amyloid-beta (Aβ) peptide accumulation.
• Synaptic Aβ toxicity impairs neuronal function.
• Proteins regulating Aβ generation at synapses are largely uncharacterized.

Purpose of the Study:

• Identify synaptic proteins interacting with the extracellular domain of amyloid precursor protein (APP).
• Investigate the role of these proteins in regulating Aβ generation.

Main Methods:

• Affinity purification-coupled mass spectrometry to identify interacting proteins.
• GST pull-down assays to map interaction sites.
• Cellular overexpression and knockdown models (CHO, PC12, primary neurons) to assess Aβ generation.
• Measurement of Aβ, APP-CTF, and sAPP levels.

Main Results:

• Synaptotagmin (Syt)-1, -2, and -9 identified as novel APP-interacting proteins.
• Syt interaction site mapped to the APP linker region.
• Syt-1 and Syt-9 overexpression increased Aβ generation.
• Syt-1 knockdown significantly reduced Aβ generation in cell lines and primary neurons.
• Syt-1 regulates Aβ generation by modulating BACE1-mediated APP cleavage.

Conclusions:

• Synaptic vesicle proteins Syt-1 and Syt-9 are novel APP-interacting proteins.
• These proteins promote Aβ generation.
• Syt-1 and Syt-9 may play a significant role in Alzheimer's disease pathogenesis.