Overcoming Cell Death and Tau Phosphorylation Mediated by PI3K-Inhibition: A Cell Assay to Measure Neuroprotection

Few targets for neuroprotection have been defined in Alzheimer's disease (AD). Recent data from the role of Wnt, insulin-like growth factor-1 and estradiol pathways in AD suggest some therapeutic targets for disease treatment, and have led us to evaluate the common factors in these pathways as further candidate targets. These data have led us to propose that glycogen synthase kinase-3 (GSK-3) inhibition appears to be a common feature of these pathways. Besides, considering that GSK-3 activation seems to be correlated with neurodegeneration, its selection as a relevant target appears obvious. The capacity of different GSK-3 inhibitors to prevent amyloid beta-peptide neurotoxicity and tau phosphorylation has been evaluated in order to develop novel clinical and therapeutic approaches. Different approaches could be used to search for new neuroprotective compounds. The most classical of these is to first define the target and then design a specific in vitro screening assay for it. Alternatively, a cell model of cell culture could be used as a primary screen. Following this rationale, we have used a combined approach in which we first used an in vitro system to select compounds able to inhibit recombinant GSK3. Subsequently, we subjected the candidate compounds to three consecutive cell-based complementary screening assays. First, cell viability was assessed using a neuroblastoma cell line before assaying the capacity of the compounds to reduce tau phosphorylation. Finally, we designed a neuronal cell model of apoptosis using the phosphatidylinositol kinase-3 inhibitor LY294002. Finally, we summarize several new compounds with neuroprotective properties.