Anesthesia-induced hyperphosphorylation detaches 3-repeat tau from microtubules without affecting their stability in...

Area of Science:

• Neuroscience
• Cell Biology

Background:

• Hyperphosphorylation of tau is a hallmark of Alzheimer's disease (AD).
• Detachment of tau from microtubules (MTs) is hypothesized to cause MT destabilization and aggregation.
• The in vivo functional consequences of tau hyperphosphorylation remain incompletely understood.

Purpose of the Study:

• To investigate the in vivo impact of tau hyperphosphorylation on its interaction with MTs.
• To determine if hyperphosphorylation leads to tau detachment from MTs and subsequent MT network destabilization.

Main Methods:

• Utilized a previously established in vivo mouse model.
• Induced hypothermia via anesthesia to promote tau hyperphosphorylation.
• Examined tau-MT binding and MT network integrity in wild-type and transgenic mice.

Main Results:

• Anesthesia-induced hypothermia led to hyperphosphorylation of MT-free tau, impairing its MT-binding and assembly-promoting abilities.
• MT-bound tau exhibited greater resistance to hyperphosphorylation.
• In wild-type mice, tau remained bound to MTs; however, in transgenic mice, 3-repeat tau detached.
• Surprisingly, tau detachment did not result in tubulin depolymerization or axonal MT network collapse.

Conclusions:

• A subpopulation of MT-bound tau resists dissociation even under extensive hyperphosphorylation in vivo.
• Sufficient tau remains bound to MTs to maintain axonal MT network integrity.
• These findings challenge the direct link between tau hyperphosphorylation, detachment, and MT network destabilization in vivo.