Activation of enzymes of cell death, the so-called Caspase precedes the formation of neurofibrillary tangles of the tau protein in neurons in the brains of Alzheimer’s patients, argue US scientists in the journal Nature.
Neurofibrillary tangles, also known as neurofibrillary degenerations, are abnormal deposits of excessively phosphorylated tau protein, present in the cytoplasm of neurons in some neurodegenerative diseases – mainly in Alzheimer’s disease and the so-called frontotemporal dementia.
Studies of the brain tissue of patients who died from Alzheimer’s have shown that neurofibrillary tangles are present in regions of massive neuronal death, leading to the hypothesis that these degenerations lead to damage and death of nerve cells in Alzheimer’s disease and dementia.
In their latest work, Bradley Hyman and colleagues from Harvard Medical School and Massachusetts General Hospital, using brain imaging techniques of living mice, showed that in fact the opposite is true – the tau protein allows neurons in which activation of caspases – enzymes that lead to cell death – to survive . Scientists have observed that the neurons that form tangles of the tau protein survive and quench caspase activity, while the rest die.
Based on the results of their research, they proposed a new theory according to which caspases cleave the tau protein, form tangles and the cell avoids death. In their opinion, it is not the filamentous, but the soluble form of the tau protein that can be toxic and lead to neurodegeneration. (PAP)