It is demonstrated that conformationally distinct tau polymorphs associate with disease-specific interaction networks across Alzheimer's disease, progressive supranuclear palsy, and dementia with Lewy bodies, providing molecular insight into tauopathy heterogeneity.
Abstract
Tau protein aggregates adopt distinct conformations across tauopathies, yet the protein interactions engaged by disease-specific polymorphs remain poorly characterized. Here, we demonstrate that conformationally distinct tau polymorphs associate with disease-specific interaction networks across Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and dementia with Lewy bodies (DLB). Interactome profiling of tau aggregates from PBS- and sarkosyl-soluble brain fractions identified 493 high-confidence interactors exhibiting remarkable disease specificity. As an exploratory feature discovery machine learning classification discriminated against diseases using as few as four to six protein features. AD tau selectively engaged glycolytic enzymes, TCA cycle components, and glutamate/GABA cycling machinery, with the astrocytic transporter SLC1A2 showing 27-fold enrichment. PSP tau exhibited extensive interactor depletion alongside selective proteasome enrichment, whereas DLB tau associated with neurogenesis modulators while depleting neuroinflammatory mediators. Interaction patterns were corroborated by parallel reaction monitoring mass spectrometry and proximity ligation assays and corresponded to disease-specific post-translational modification profiles. These findings show that tau polymorph conformations are associated with disease-specific interaction networks, providing molecular insight into tauopathy heterogeneity.
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by synaptic dysfunction, protein aggregation, and widespread molecular alterations in the brain. In this study, we applied quantitative mass spectrometry-based proteomics and phosphoproteomics to characterize synaptosomes and sarkosyl-insoluble protein inclusions from the post-mortem frontal lobes of AD and control cases. We identified >3700 proteins across both fractions, revealing AD-associated changes in synaptic composition and phosphorylation patterns. Proteomic analyses indicated mitochondrial deficits and disruptions in vesicle trafficking within synapses, whereas insoluble protein inclusions showed an accumulation of spliceosomal components and glial activation markers as well as an enrichment of N-terminally truncated amyloid beta peptides in AD cases, suggesting involvement of postfibrillar processing events mediated by specific proteases in amyloid plaque pathology. Phosphoproteomic analysis revealed extensive alterations in pathways regulating vesicle trafficking, Golgi homeostasis, and synaptic function. We observed increased tau phosphorylation at AD-associated sites in insoluble inclusions and distinct phosphorylation changes in synaptic tau, particularly at S285 and S305, suggesting altered tau function and aggregation properties. These findings provide new molecular insights into AD-related nerve terminal composition and protein aggregation, advancing our understanding of disease-associated changes at the subcellular level.
S. B. Elmkvist, Camilla Thygesen, Pia Jensen et al.· Journal of Proteome Research· 0 citations
It is reported that X-linked Dystonia-Parkinsonism (XDP), caused by a non-coding retrotransposon-associated repeat insertion in TAF1, involves a significant imbalance of tau isoforms and the accumulation of hyperphosphorylated, four-repeat tau in the brain.
C. J. Reyes, Aloysius Domingo, E. Penney et al.· medRxiv· 0 citations
Routine and accessible plasma measures can be leveraged to recover reproducible, biologically distinct progression modules that improve characterization of heterogeneous AD and have practical value for risk stratification, trial enrichment, or treatment monitoring.
R. R. Butler, M. P. Brown, A. Weber et al.· medRxiv· 0 citations
Tau aggregation and hyperphosphorylation are key pathological features of Alzheimer's disease (AD). Because Tau is intrinsically disordered, conventional small-molecule inhibitors have achieved limited success. Proteolysis-targeting chimeras (PROTACs) enable the targeted proteasomal degradation of previously considered undruggable proteins. We designed Tau-targeted PROTAC candidates using methylene blue (MB) as a recognition moiety for aggregation-prone motifs within the microtubule-binding region and varied the linker lengths and E3 ligase recruitment ligands to optimize degradation efficiency. Cell-based screening revealed that MB-2-VHL1 and MB-2-VHL2 are active degraders. In vivo studies confirmed a reduction in total Tau levels and degradation of phosphorylated Tau (p-Tau). In 3xTg-AD mice, subcutaneous administration of MB-2-VHL2 was associated with reduced hippocampal Tau and p-Tau levels and improved recognition memory and spatial learning. MB-2-VHL2 was also detectable in both serum and brain tissue by LC-MS/MS after subcutaneous administration and did not cause detectable histological or biochemical toxicity. These results indicate that MB-2-VHL2 can reduce both total Tau and p-Tau levels in vivo. Although the reduction in p-Tau appeared more pronounced under our experimental conditions, whether MB-2-VHL2 preferentially targets pathological Tau remains to be determined. Overall, these findings support further optimization and preclinical evaluation of Tau-targeted PROTACs as a potential therapeutic strategy for AD.
Tianrun Zhao, Tian-Yang Wang, Haosen Wang et al.· ACS Chemical Biology· 0 citations
Alzheimer’s disease (AD) pathogenesis involves complex, multifactorial changes to the brain proteome that conventional unfractionated analyses may obscure. Proteins frequently occupy multiple subcellular compartments as spatial proteoforms, yet the contribution of aberrant protein localization to AD pathogenesis remains poorly understood. To address this, we fractionated post-mortem human hippocampi from 13 AD and 14 non-AD individuals into four subcellular fractions and quantified 6,123 proteins by TMT-LC-MS. Although 75% of proteins were detected in more than one fraction, 78% of significant AD-associated alterations were restricted to a single fraction, demonstrating that subcellular localization is a primary determinant of disease vulnerability. Discordant abundance patterns between fractions revealed retromer complex mislocalization, nuclear transport dysfunction, and insoluble protein accumulation, with the endosomal-lysosomal and protein folding pathways most consistently perturbed. To examine how these perturbations evolve with disease progression, we applied the QUAD strategy to measure protein degradation in two fractions of APPswePS1delta9 mouse cortex at 2, 5, and 12 months. Degradation rates diverged between fractions and genotypes in an age-dependent manner, and cross-dataset comparison identified six proteins altered at the earliest pre-pathological timepoint, implicating vesicle transport and proteostasis disruption as initiating features of AD. These findings establish spatial proteoforms as essential units of pathogenic analysis and reveal disease-relevant signals invisible to bulk tissue approaches.
Daniel B. McClatchy, Natalie P. Turner, John R. Yates· bioRxiv· 0 citations
It is demonstrated that kinase-specific phosphorylation outside the amyloid core can be sufficient to bias tau toward a defined fibril structure, establishing a direct mechanistic link between kinase specificity, post-translational modification, and tau strain formation.
A new machine-learning framework aims to improve the success rate of computational protein design while moving away from results that reproduce sequences found in nature.
