Abstract
In Alzheimer's disease (AD), pathological tau protein shows a progressive accumulation of post-translational modifications (PTMs), reflecting disease severity, progression, and prion-like activity. Although many neurodegenerative diseases with dementia display tau aggregates, the pathological proteoforms of tau protein from each disease type remain unknown. Here, using a quantitative mass spectrometry-based proteomics platform, FLEXITau, deep characterization of pathological tau protein isolated from the brains of 203 human subjects with AD, familial AD (fAD), chronic traumatic encephalopathy (CTE), corticobasal degeneration (CBD), Pick's disease (PiD), progressive supranuclear palsy (PSP), dementia with Lewy bodies (DLB)-a non-tauopathy symptomatic control-and healthy controls (CTR) is performed. Unsupervised data analyses and supervised machine learning identify distinct molecular features of pathological tau for each disease, enabling molecular disease stratification. This study identifies potential disease-specific biomarkers and therapeutic targets for tauopathies and provides critical quantitative information for pharmacokinetic modeling required for therapeutic and disease mechanism studies.