Elsevier

Neurobiology of Aging

Volume 47, November 2016, Pages 113-126
Neurobiology of Aging

Regular article
Analysis of isoform-specific tau aggregates suggests a common toxic mechanism involving similar pathological conformations and axonal transport inhibition

https://doi.org/10.1016/j.neurobiolaging.2016.07.015Get rights and content
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Abstract

Misfolded tau proteins are characteristic of tauopathies, but the isoform composition of tau inclusions varies by tauopathy. Using aggregates of the longest tau isoform (containing 4 microtubule-binding repeats and 4-repeat tau), we recently described a direct mechanism of toxicity that involves exposure of the N-terminal phosphatase-activating domain (PAD) in tau, which triggers a signaling pathway that disrupts axonal transport. However, the impact of aggregation on PAD exposure for other tau isoforms was unexplored. Here, results from immunochemical assays indicate that aggregation-induced increases in PAD exposure and oligomerization are common features among all tau isoforms. The extent of PAD exposure and oligomerization was larger for tau aggregates composed of 4-repeat isoforms compared with those made of 3-repeat isoforms. Most important, aggregates of all isoforms exhibited enough PAD exposure to significantly impair axonal transport in the squid axoplasm. We also show that PAD exposure and oligomerization represent common pathological characteristics in multiple tauopathies. Collectively, these results suggest a mechanism of toxicity common to each tau isoform that likely contributes to degeneration in different tauopathies.

Keywords

Tauopathy
Alzheimer's disease
Oligomer
Axon
Aggregation
Microtubule-associated protein
Pathological conformations

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