The dominant amyloid cascade hypothesis for Alzheimer's disease broadly states that amyloid-β aggregation occurs early in the progression of the condition, setting the stage for later and much more damaging neuroinflammation and tau aggregation. There remains a great deal of room to debate the details of this progression, how exactly amyloid-β and tau aggregation are linked. Is it as simple as a matter of chronic inflammation generated by amyloid-β aggregation slowly rising to the level of inciting a feedback loop between tau aggregation and further inflammatory signaling? Or some other more direct connection between the biochemistry of amyloid-β aggregation and tau aggregation? Here, researchers advance a novel theory on this topic.
Alzheimer's disease (AD) is defined by cognitive decline in conjunction with accumulation of aggregated amyloid β (Aβ) and tau, yet existing models of AD fail to provide a simple connection between Aβ and tau. However, microtubules provide an intriguing nexus for pathological interactions between the two. Tau binds to microtubules and is critical to maintaining their proper function. We demonstrate that Aβ also binds to microtubules with affinity comparable to that of tau itself.
We hypothesize that displacement of tau by Aβ leads to microtubule dysfunction and facilitates tau phosphorylation and aggregation. Importantly, in this model, aggregation of Aβ is not the primary cause of toxicity, which allows many of the apparent contradictions between Aβ pathology and cognition to be rationalized. This model highlights the importance of both tau and Aβ and enables additional therapeutic and intervention strategies to be considered.
Link: https://doi.org/10.1093/pnasnexus/pgag034
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