Sodium selenate specifically activates PP2A phosphatase, dephosphorylates tau and reverses memory deficits in an Alzheimer's disease model.

Neurofibrillary tangles composed of abnormally hyperphosphorylated tau protein are a hallmark of Alzheimer's disease (AD) and related tauopathies. Tau hyperphosphorylation is thought to promote aggregation with subsequent tangle formation. Reducing tau phosphorylation by boosting the activity of the key phosphatase/s that mediate dephosphorylation of tau could be a viable clinical strategy in AD. One of the key phosphatases implicated in regulating tau protein phosphorylation is the serine-threonine phosphatase PP2A. We have determined that sodium selenate can act as a specific agonist for PP2A, significantly boosting phosphatase activity. Acute treatment of either neuroblastoma cells or normal aged mice with sodium selenate rapidly reduced tau protein phosphorylation. Sodium selenate-treated transgenic TAU441 mice had significantly lower levels of phospho- and total tau levels in the hippocampus and amygdala compared with controls and exhibited significantly improved spatial learning and memory on the Morris Water Maze task. Sodium selenate is a specific activator of PP2A with excellent oral bioavailability, and favourable central nervous system penetrating properties. Clinical studies in patients with AD are envisaged in the near future.