Transcriptional regulation of beta-secretase by p25/cdk5 leads to enhanced amyloidogenic processing.

Cyclin-dependent kinase 5 (cdk5) has been implicated in Alzheimer's disease (AD) pathogenesis. Here, we demonstrate that overexpression of p25, an activator of cdk5, led to increased levels of BACE1 mRNA and protein in vitro and in vivo. A p25/cdk5 responsive region containing multiple sites for signal transducer and activator of transcription (STAT1/3) was identified in the BACE1 promoter.

Interplay between cyclin-dependent kinase 5 and glycogen synthase kinase 3 beta mediated by neuregulin signaling leads to differential effects on tau phosphorylation and amyloid precursor protein processing.

Cyclin-dependent kinase 5 (cdk5) and glycogen synthase kinase 3beta (GSK3beta) have been implicated in pathogenic processes associated with Alzheimer's disease because both kinases regulate tau hyperphosphorylation and enhance amyloid precursor protein (APP) processing leading to an increase in amyloid beta (Abeta) production. Here we show that young p25 overexpressing mice have enhanced cdk5 activity but reduced GSK3beta activity attributable to phosphorylation at the inhibitory GSK3beta-serine 9 (GSK3beta-S9) site. Phosphorylation at this site was mediated by enhanced activity of the neuregulin receptor complex, ErbB, and activation of the downstream phosphatidylinositol 3 kinase/Akt pathway.