An inducible mouse model of p25 accumulation (the CK-p25 mouse) that displays key pathological hallmarks of Alzheimer disease (AD) is used as a gold-standard to test the proposed algorithm by providing a conditional control of rapid neurodegeneration.
Deregulation of Cyclin-dependent kinase 5 (Cdk5) activity by production of its hyperactivator p25 is involved in the formation of tau and amyloid pathology reminiscent of Alzheimer's disease (AD).
Cyclin-dependent kinase 5 (Cdk5), which binds to and is activated by p35, phosphorylates multiple substrates and plays an essential role in the development and function of the CNS; however, proteolytic production of p25 from p35 under stress conditions leads to the inappropriate activation of Cdk5 and contributes to hyperphosphorylation of τ and other substrates that are related to the pathogenesis of Alzheimer's disease.
These results reveal a link between p25 and BACE1 in AD brains and suggest that upregulated Cdk5 activation by p25 accelerates AD pathogenesis by enhancing BACE1 activity via phosphorylation.
Together, these results reveal a physiological role of p25 production in synaptic plasticity and memory and provide new insights into the function of p25 in Aβ-associated neurotoxicity and AD-like pathology.
The deregulation of cyclin-dependent kinase 5 (Cdk5) by p25 has been shown to contribute to the pathogenesis in a number of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD) and Alzheimer's disease (AD).
The calpain-mediated cleavage of p35 to p25 and the resulting aberrant activity and neurotoxicity of Cdk5 have been implicated in neurological disorders, such as Alzheimer's disease.
Here, we tested the early compensation hypothesis by analyzing the levels of p25 and its precursor p35 in AD postmortem samples from different brain regions at different stages of tau pathology, using quantitative Western blots.
Therefore, p25 formation may initially be a compensatory response for early learning deficits in Alzheimer's disease, but continued formation could contribute to detrimental changes in Alzheimer's disease.
Cdk5 phosphorylates tau at AD-specific phospho-epitopes when it associates with p25. p25 is a truncated activator, which is produced from the physiological Cdk5 activator p35 upon exposure to Abeta peptides.