Tau kinetics in Alzheimer's disease

Area of Science:

• Neuroscience
• Biochemistry
• Systems Biology

Background:

• The cytoskeletal protein tau is central to Alzheimer's disease (AD) pathogenesis.
• AD is characterized by neurofibrillary tangles of hyperphosphorylated tau.
• Elevated soluble tau levels are observed in the brain, cerebrospinal fluid (CSF), and plasma of AD patients.

Purpose of the Study:

• To elucidate the mechanisms behind elevated tau levels in Alzheimer's disease.
• To develop and utilize a kinetic model to understand tau dynamics.

Main Methods:

• A three-compartment kinetic model (brain, CSF, plasma) was developed.
• The model incorporates zero-order kinetics for tau synthesis and first-order kinetics for release, absorption, and clearance.
• Model parameters, including half-lives, were estimated for each compartment.

Main Results:

• Estimated tau half-lives: 552 h (brain), 9.9 h (CSF), 10 h (plasma).
• The model predicts that increased tau levels in AD are best explained by a decreased tau catabolism rate.
• Increased brain tau half-life in AD is attributed to reduced catabolism, not increased synthesis.

Conclusions:

• Decreased tau catabolism is the primary driver of elevated tau in the brain, CSF, and plasma in Alzheimer's disease.
• Neuronal tau clearance predominantly occurs via catabolism rather than release into the CSF.
• Further experimental data are needed for precise model parameter determination.