Hyperphosphorylation of microtubule-associated tau protein plays dual role in neurodegeneration and neuroprotection.

The microtubule-associated protein tau plays a major role in maintaining the normal morphology of the neurons. The major biological activity of tau is to promote microtubule assembly and stabilize the microtubules. In the brain of Alzheimer's disease (AD) patients, tau protein is abnormally hyperphosphorylated and thus become incompetent in promoting microtubule assemble and maintaining the stability of the microtubules. These detrimental effects of tau may lead the neurons to degeneration. Recent studies show that tau hyperphorylation may be neuroprotective in the early stages of the disease process. The primary aim of this review is to summarize the latest developments and perspectives in our understanding about the roles of tau hyperphosphorylation in neurodegeneration and neuroprotection.