Protein Arc ferries Alzheimer’s tau between neurons

Tau proteins accumulate inside brain cells in Alzheimer’s, causing damage. But how do those proteins travel from one neuron to another? The researchers identified the protein Arc as a crucial link in that process. The results were published in Cell.

Neurons package tau into extracellular vesicles (small parcels that cells release to exchange substances). Arc turns out to bind directly to tau and is required to load tau into those vesicles. In mice with the Arc gene switched off, the vesicles contained significantly less tau. The ability of those vesicles to seed tau aggregation in healthy cells also dropped sharply.

Less spread, but more local damage

There is a trade-off. Mice without Arc had less tau in their vesicles but more tau accumulating inside their own neurons. In the early stage of disease, this came with a modest increase in cell toxicity. That suggests blocking Arc could slow the spread of Alzheimer’s while slightly increasing local toxicity. This trade-off needs further investigation before targeted therapies can be developed.

Strong link to human brain tissue

The findings are not limited to mice. In brain tissue from people with Alzheimer’s, the amount of Arc in vesicles correlated strongly with the amount of phosphorylated tau (tau that is chemically modified and more prone to clumping). That makes Arc a more credible target for future drugs, though clinical applications remain distant.

From a longevity science perspective, this research matters because it shows that the progression of neurodegeneration is actively driven by specific proteins. Aging increases the risk of tau accumulation; understanding how that accumulation spreads is a step toward intervening earlier in the disease process.

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