A common enemy
The same enzyme contributes to the development of Alzheimer's and Parkinson's diseases
Evgenia Efimova, Vesti
It cannot be said that Alzheimer's and Parkinson's diseases are the same: they affect different areas of the brain and have their own distinctive genetic and environmental risk factors. Nevertheless, scientists say, at the biochemical level, these two neurodegenerative diseases have similarities: during their development, sticky proteins form plaques in brain cells. And, as it turned out, the same enzyme stimulates this process in two cases. The similarities between the two different diseases may lead to the creation of new treatments for Parkinson's disease, experts say.
As already mentioned, with the development of diseases, sticky protein forms toxic clots (plaques) in brain cells. So, in Alzheimer's disease, the "destroyer" inside the cells is called tau-a protein that forms neurofibrillary tangles. In Parkinson's disease, the sticky protein is alpha-synuclein, which forms Levi's corpuscles.
Earlier, researcher Keqiang Ye and his colleagues from Emory University showed that the enzyme asparagine endopeptidase (AEP) cuts tau protein, thus making it more sticky and toxic. Medications that inhibit (suppress) AEP have had a positive effect in the treatment of Alzheimer's disease in animals.
Now, researchers have shown that the AEP enzyme acts in the same way with respect to alpha-synuclein. In other words, the same enzyme contributes to the development of two different diseases.
"With the development of Parkinson's disease, alpha-synuclein behaves in the same way as tau protein when Alzheimer's disease occurs. We hypothesized that if the AEP enzyme can cut tau protein, then it can do the same with alpha-synuclein," Ye said (in a Drug discovery press release: Alzheimer's and Parkinson's spurred by the same enzyme – VM).
It is noted that usually AEP is contained inside lysosomes, cellular stations for the disposal of "garbage", and never leaves them, but in case of violations in their work, it can penetrate into the rest of the cells.
Scientists tracked the vital activity of nerve cells in brain samples of people suffering from Parkinson's disease and found that AEP molecules actually interacted with alpha-synuclein and cut it off, RIA Novosti reports.
According to experts, the reaction rate between the protein and the enzyme depends on one parameter – the age of a person. The older it is, the faster AEP destroys alpha-synuclein molecules and forms tangles from its scraps. Biologists attribute this to the fact that lysosomes begin to "leak" more strongly in old age due to the accumulation of problems in the work of genes and proteins in neurons.
Since researchers have previously successfully suppressed the effect of AEP in experiments on animal models suffering from Alzheimer's disease, the discovery could potentially contribute to the creation of a cure for Parkinson's disease, scientists believe. However, they warn that AEP, unfortunately, is not the only protein capable of cutting alpha-synuclein into toxic pieces. Moreover, even whole this protein can cause harm. Nevertheless, experts intend in the future to test drugs that suppress the effect of AEP on animals with Parkinson's disease.
The results of the study are published in the scientific publication Nature Structural and Molecular Biology (Zhang et al., Asparagine endopeptidase cleaves α-synuclein and mediates pathological activities in Parkinson's disease).
Let's add that scientists around the world are trying to find different ways to treat both diseases. So, recently one group of specialists found out that transfusion of "young" blood to elderly people reduced the risk of developing Alzheimer's disease, and pig cells began to be used against Parkinson's disease.
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04.07.2017