WISCHIK, C. M. | bioRxiv Science

bioRxiv2025

A proteomic analysis of the PHF-forming tau fragment (tau297-391) following uptake into differentiated human neuronal SHSY5Y cells

Tau self-assembly and intracellular deposition is associated with a group of neurodegenerative diseases called tauopathies, which include Alzheimers disease (AD) and Picks disease. Here, we measured the proteome response in human neuronal cells (differentiated SH-SY5Y) following addition of a spontaneously amyloidogenic region of tau known as dGAE (tau297-391) which forms AD-like paired helical filaments in vitro and proteomic analysis showed increased endogenous tau expression. Further interactome analysis uncovered increased association between tau and proteins associated with nuclear chromatin, the nucleolus, and the spliceosome as well as the thiol-peroxidase, PRDX6 alongside an increase in reactive oxygen species (ROS). This work highlights a method to identify proteome pathways that may play an important role in the development of tau pathology.

cell biology↗

bioRxiv2025

Inhibiting disulphide bonding in truncated tau297-391 results in enhanced self-assembly of tau into seed-competent assemblies.

Tau undergoes fibrillogenesis in a group of neurodegenerative diseases termed tauopathies. Each tauopathy is characterized by tau fibrils with disease-specific conformations, highlighting the complexity of tau self-assembly. This has led to debate surrounding the precise mechanisms that govern the self-assembly of tau in disease, especially the involvement of disulphide bonding (DSB) between cysteine residues. In this study, we use a truncated form of tau, dGAE, capable of forming filaments identical to those in disease. We reveal the impact of DSB in dGAE assembly and propagation by resolving the global mechanisms that dominate its assembly. We found evidence for surface-mediated secondary nucleation and fragmentation being active in dGAE assembly. The inhibition of DSB during dGAE assembly leads to an enhanced aggregation rate through a reduced lag phase, but with no effect on the global assembly mechanisms. We suggest this is due to the formation a dominant, seed-competent species in the absence of DSB that facilitates elongation and secondary nucleation resulting in enhanced assembly. In vitro seeding assays reveal the recruitment of endogenous tau in a cell model only when using dGAE species formed under conditions that inhibit DSB. Our results further support the use of the in vitro dGAE tau aggregation model for investigating the mechanism of tau assembly, the effect of varying conditions on tau assembly and how these conditions affect the resultant species. Further studies may utilise dGAE and its aggregates to investigate tau seeding, propagation and to highlight or test potential targets for therapies that reduce the spread of pathologic tau throughout the brain.

biochemistry↗