p63α and γ Induce TAU Phosphorylation in Cultured Mammalian Cells

Here we show by western blotting that transcriptionally active isoforms of p63 (p63α and p63γ) induce the phosphorylation of human 2N4R tau at the tau-1/AT8 epitope in HEK293a cells; a phospho-epitope increased in Alzheimer's disease. Confocal microscopy shows that tau and p63α are spatially separated intracellularly. Tau was found in the cytoskeletal compartment, whilst p63α was located in the nucleus, indicating that the effects of p63 on tau phosphorylation are indirectly mediated. Tau phosphorylation occurred independently of the known tau kinases, protein kinase C delta (PKCδ), c-Jun N-terminal kinase (JNK), extracellular-signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38), glycogen synthase kinase 3 (GSK3), v-akt murine thymoma viral oncogene homolog (AKT) and cyclin-dependent kinase 5 (Cdk5) and the tau protein phosphatases (PP), PP1 and PP2A-Aα/β. Considering that p63 and tau are both associated with developmental processes, these findings have ramifications for neuronal development and synaptic plasticity and also neurodegenerative diseases such as Alzheimer's disease and other tauopathies