Nanoparticle-mediated Zn delivery impacts neural protein phosphatase activity

In recent years, the use of nanoparticles (NPs) in diagnosis and treatment of different disorders has been a matter of intensive research. Due to their physical and chemical properties, zinc oxide nanoparticles (ZnO NP) have been explored in a range of biological applications, including cancer and neurological diseases. Regarding the latter, while some studies report protective effects of ZnO NP in cultured cells and animal models, others indicate that these NPs have a harmful impact on the brain, such as promoting oxidative stress and cell death. Previous results from our group have suggested beneficial effects for zinc (Zn) cations in both modulating protein aggregation and on Alzheimer's disease (AD) pathology. In this context, the effect of encapsulated Zn as a nanoparticle on protein aggregation and its influence on protein phosphorylation events associated with AD were explored. The results herein presented show that ZnO NP contributed to a decrease in protein aggregation in neuronal cells. However, these NPs were also found to decrease PP1 and PP2A activity, potentially contributing to increased phosphorylation of tau and APP, which are AD pathology hallmarks. In conclusion, while the use of NPs as a Zn delivery system may offer benefits by reducing aggregate formation, they also appear to induce undesired molecular changes, like those observed in AD. Therefore, a holistic approach should be incorporated as we move forward in this research line, as their effects on distinct cellular processes may be dual edged.