Mutant presenilin (A260V) affects Rab8 in PC12D cell

Area of Science:

• Neuroscience
• Cell Biology
• Genetics

Background:

• Familial early-onset Alzheimer's disease (FAD) is primarily caused by mutations in the presenilin-1 (PS1) gene.
• Elevated levels of amyloid-beta 42 (Abeta) are a key indicator of abnormal PS1 function and are linked to Alzheimer's disease (AD).
• Understanding the interaction between PS1 and amyloid precursor protein (APP) is crucial for elucidating AD's molecular mechanisms.

Purpose of the Study:

• To investigate the impact of PS1 mutations on APP metabolism.
• To examine how PS1 mutations affect the transport of APP and its fragments within the cell.

Main Methods:

• Developed PC12D cell lines expressing either wild-type human PS1 or a mutant form (PS1A260V).
• Analyzed the levels of Rab8 GTPase, a protein involved in intracellular transport.
• Investigated the accumulation of APP C-terminal fragments (CTF) in cellular fractions.

Main Results:

• PC12D cells expressing the PS1A260V mutant showed significantly reduced levels of Rab8.
• APP CTF accumulated in heavy membrane fractions associated with trans-Golgi network (TGN) to plasma membrane (PM) transport.
• Total intracellular Abeta production was decreased in cells with the PS1A260V mutation.

Conclusions:

• PS1 mutations disrupt membrane vesicle transport, specifically along the TGN-to-PM pathway.
• The prolonged retention of APP CTF during transport is linked to reduced Abeta production.
• This study provides insights into the cellular mechanisms underlying FAD pathogenesis.