The Mechanistic Link Between Tau-Driven Proteotoxic Stress and Cellular Senescence in Alzheimer's Disease

Area of Science:

• Neuroscience
• Cell Biology
• Pathology

Background:

• Tau protein hyperphosphorylation and misfolding in Alzheimer's disease (AD) lead to its dissociation from microtubules.
• Multiple cellular degradation pathways, including proteasomes and autophagy, are involved in tau clearance.
• Impaired aggrephagy leads to neurofibrillary tangle (NFT) formation and recruitment of chaperones like VCP and HSP70 for tau degradation via the ubiquitin-proteasome system (UPS).

Purpose of the Study:

• To review the sequential failure of tau degradation mechanisms in AD.
• To elucidate the mechanistic link between tau-driven proteotoxic stress and cellular senescence.
• To summarize evidence on how impaired tau clearance contributes to AD pathogenesis.

Main Methods:

• Comprehensive literature review of studies on tau degradation pathways in AD.
• Analysis of mechanisms linking tau pathology to proteotoxic stress and cellular senescence.
• Synthesis of evidence on tau secretion, uptake, and subsequent cellular responses.

Main Results:

• Failure in tau degradation pathways contributes to tau accumulation and extracellular secretion.
• Secreted tau seeds pathology in various brain cells, inducing proteotoxic stress.
• Proteotoxic stress triggers cellular senescence, characterized by senescence-associated secretory phenotype (SASP) factors, leading to brain atrophy.

Conclusions:

• Tau degradation failure is a critical early event in AD.
• Tau-driven proteotoxic stress and cellular senescence are mechanistically linked, contributing to neurodegeneration.
• Understanding these pathways offers potential therapeutic targets for AD.