Study Reveals How Tau Protein Escapes Lysosomes to Spread Between Brain Cells
Researchers used cryo-electron tomography to investigate how tau protein fibrils spread between brain cells via the endolysosomal system, identifying key molecular pathways involved in this process. The study found that tau pre-formed fibrils (PFFs) do not directly damage lysosomal membranes but instead co-aggregate with cellular materials inside lysosomes and leak into the cytosol through reversible membrane holes. Understanding this mechanism is important for developing therapies targeting tau spread in Alzheimer's disease and other tauopathies.
A new preprint study published on bioRxiv examined the structural mechanisms by which tau proteins — implicated in Alzheimer's disease and related neurodegenerative disorders — spread from cell to cell through the endolysosomal network. Using cryo-electron tomography, the researchers found that tau pre-formed fibrils (PFFs) do not directly interact with or distort lysosomal membranes, distinguishing their mechanism from classical lysosome-damaging agents like LLOMe. Instead, tau PFFs appear to co-aggregate with other cellular materials within lysosomes, with the resulting aggregates leaking into the cytosol via reversible holes in the lysosomal membrane. The study also identified several cellular pathways that restrict tau seeding: the PITT pathway and the lipid transporter VPS13C were strongly implicated in both neurons and astrocytes, while the CASM pathway played a major role specifically in astrocytes. These findings refine the current model of prion-like tau propagation and highlight potential therapeutic targets within the lysosomal damage-sensing and repair machinery.
What's missing
As a preprint, this study has not yet undergone formal peer review, so findings should be interpreted with caution. The study does not address whether the reversible membrane holes observed are sufficient to explain the full extent of tau spread seen in human disease, nor does it clarify the precise molecular trigger that initiates co-aggregation within lysosomes. The in vitro and cell-culture findings may not fully translate to the complex in vivo environment of the aging human brain.
What different sources said
- bioRxivCenter
Structural Mechanism and Cellular Restriction of Tau Seeding from Endolysosomes
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