Estradiol Attenuates Tau Hyperphosphorylation Induced by Upregulation of Protein Kinase-A

Protein kinase A (PKA) plays a crucial role in tau hyperphosphorylation, an early event of Alzheimer disease (AD), and 17β-estradiol replacement in aging women forestalls the onset of AD. However, the role of estradiol in PKA-induced tau hyperphosphorylation is not known. Here, we investigated the effect of 17β-estradiol on cAMP/PKA activity and the PKA-induced tau hyperphosphorylation in HEK293 cells stably expressing tau441. We found that 17β-estradiol effectively attenuated forskolin-induced overactivation of PKA and elevation of cAMP, and thus prevented tau from hyperphosphorylation. These data provide the first evidence that 17β-estradiol can inhibit PKA overactivation and the PKA-induced tau hyperphosphorylation, implying a preventive role of 17β-estradiol in AD-like tau pathology.