Whether you have done your own deep dive into Alzheimer's disease or have only heard about it briefly on a television segment, you have probably heard someone mention “tau” and its relation to this form of dementia. We have certainly mentioned tau in previous WITS blog posts, but it’s time to answer some important questions: What is tau? Why is it a problem?
In a healthy brain, tau stabilizes microtubules. These microtubules are like cell skeletons, which need to be stabilized to prevent brain cells from collapsing. When microtubules are functioning, they allow everything within the brain cell to run smoothly. Messages are relayed seamlessly from one cell to the next, which allows the brain to do incredible things from decision-making, to spatial awareness, to memory.
Phosphorylation is a common biological process that happens to many molecules in the body for different reasons. It can cause a molecule to become active, to stop its activity, or take on a new activity altogether. In the case of tau, phosphorylation causes things to go awry. When tau is phosphorylated and starts aggregating, it causes instability in the microtubules it is supporting and forms clumps . In addition to the structural disruption, this causes a disruption in communication between brain cells, hindering their ability to send each other signals and interfering with the brain’s ability to function.
When lots of these aggregates form, we call that a “tangle.” Tau tangles tend to start accumulating in certain areas of the brain before they spread to the rest of the brain, which aligns with our current understanding of Alzheimer’s disease progression. Tau tangle accumulation in areas of the brain important for memory are what lead to the early symptoms of Alzheimer’s.
Although we know the function of tau and what happens when that function is disrupted, there hasn’t been success in developing drugs that target tau. However, hopefully what we do know will guide us in the right direction to better understanding and fighting against Alzheimer’s disease.
References
Guo T, Noble W, Hanger DP. Roles of tau protein in health and disease. Acta Neuropathol. 2017;133(5):665-704. doi:10.1007/s00401-017-1707-9
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