Stabilization of dynamic microtubules by mDia1 drives Tau-dependent Aβ_1-42 synaptotoxicity

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Oligomeric amyloid beta (Aβ) is implicated in Alzheimer's disease (AD) synaptotoxicity.
• Hyperphosphorylated tau exacerbates Aβ toxicity, but their direct link is debated.
• Microtubule (MT) dynamics are crucial for neuronal function.

Purpose of the Study:

• To investigate the role of microtubule dynamics in Aβ-induced synaptotoxicity.
• To elucidate the mechanism linking Aβ and tau pathology.
• To identify potential therapeutic targets for AD.

Main Methods:

• Utilized hippocampal neuron cultures.
• Investigated Aβ effects on tubulin posttranslational modifications (PTMs) and MT dynamics.
• Assessed the impact of mDia1 inhibition on Aβ-induced neuronal damage.
• Examined tau phosphorylation and dendritic spine morphology.

Main Results:

• Aβ acutely stabilizes dynamic microtubules by reducing catastrophe frequency.
• Inhibition of the formin mDia1 reversed Aβ-induced synaptotoxicity and axonal transport deficits.
• Microtubule stabilization promoted tau-dependent dendritic spine loss and tau hyperphosphorylation.
• mDia1 plays a critical role in mediating Aβ's detrimental effects.

Conclusions:

• mDia1 is a novel player in Aβ-mediated synaptotoxicity.
• Inhibition of MT dynamics and PTM accumulation drive tau-mediated neuronal damage in AD.
• Targeting mDia1 or MT dynamics may offer therapeutic strategies for Alzheimer's disease.