Acción protectora de la proteína tau en la enfermedad de Alzheimer

Neurofibrillary tangles (NFT) composed of tau protein abnormally assembled are the hallamarks of Alzheimer'diseased brains. NFTs represent dense accumulation of paired helical filaments (PHF). Hyperphosphorylation and endogenous proteolysis (truncation) are the two major pathological changes found in tau-PHF. Despite the fact that the majority of studies focus on the hyperphosphorylation as a key event in Alzheimer's disease (AD) pathogenesis, some reports are contradictory in the sense that they have not found any evidence of toxicity of the hyperphosphorylated NFT. Moreover, these same studies suggest that hyperphosphorylated tau has, in fact, a protective role in AD against to the progressive cytoplasmic accumulation of a truncated tau fragment at Glu391. This fragment of 90-92 aminoacid length is so-called the PHF «core». This fragment is highly toxic and the cause of neuronal death in AD. In this review, we analyzed the role the hyperhosphorylated and truncated tau species focusing in toxicity and protection in AD pathogenesis.