Novel screening cascade identifies MKK4 as key kinase regulating Tau phosphorylation at Ser422.

Phosphorylation of Tau at serine 422 promotes Tau aggregation. The kinase that is responsible for this key phosphorylation event has so far not been identified but could be a potential drug target for Alzheimer's disease. We describe here an assay strategy to identify this kinase. Using a combination of screening a library of 65'000 kinase inhibitors and in vitro inhibitor target profiling of the screening hits using the Ambit kinase platform, MKK4 was identified as playing a key role in Tau-S422 phosphorylation in human neuroblastoma cells.