Korean scientists have discovered new functions of the tau protein, known as the main cause of Alzheimer's disease.
The Department of Bio and Brain Engineering at the Korea Advanced Institute of Science and Technology (KAIST) and a research team led by Professor Choi Myung-chul announced on Dec. 16 that they had found that the tau protein can control power between microtubules, a structure found in the cells of the body, including those of the brain.
Microtubules are tube-shaped protein polymers that transport cytologic materials within cells like nerve cells, or neurons. They act as “highways inside of cells,” measuring 20 nm in diameter. Tau proteins are proteins that perform the function of stabilizing nerve cells by binding to microtubules and preventing their disintegration. Alzheimer's disease is caused by the interaction between tau proteins and microtubules. In other words, the disease occurs when neurons cannot properly receive signals after the structural stability of microtubules, which are detached from the tau protein, decreases.
In the human body, there are six different types of tau proteins, and each of them consists of the binding domain, which unites with microtubules, and the projection domain, which is projected out. Until now, the functions of the short, medium and long chains of projection domains have not been unknown.
The research team observed microtubules, which are raised into tubulin, or the basic protein that forms microtubules, refined from small nerve cells, through the “X-ray scattering accelerator” after putting them in biodegradable polymers, polyethylene glycol. As a result, the structure of microtubules started changing when the force exerted on microtubules surpasses the critical value. However, the modification of the tau protein in the long chain of the projection domain completely disappeared when the tau protein was united.
This was because the projection domain of the tau protein serves as a bumper which buffers the forces between microtubules, maintaining the stability.
This latest research was recently released in the online edition of Proceedings of the National Academy of Sciences of the United States.
Prof. Choi Myung-chul said, “Through the continuous research on structural interactions between the tau protein and microtubules, we will find out critical clues to get over brain diseases, such as Alzheimer's and Parkinson's diseases.”