Mechanism investigation of PIP4K2A in metabolic disturbance in Alzheimer’s disease model cells

Background: Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases that cause dementia in the world. There are increasing connections between metabolic syndromes and AD, in which Type 2 Diabetes Mellitus (T2DM) is the strongest link. The identification of phosphatidylinositol-5-phosphate 4-kinase type 2 alpha (PIP4K2A) in the cellular processes of AD and T2DM offers valuable insights into the development of biomarkers for diagnosis and therapy. Thus, it is necessary to build a cell model to investigate the mechanisms of AD and insulin resistance pathologies in cells.

Methods: In this project, palmitic acid and acrolein were used to establish insulin resistant and AD-like cell models from human neuroblastoma SH-SY5Y. Cells viability was measured by cell counting kit CCK8 while being treated with acrolein and palmitic acid in different concentrations and time points to identify the half maximal inhibitory concentration (IC50). The relative number of cells with long or short neurites was counted after treatment. The levels of AD and insulin resistance biomarker levels were analyzed using Western blotting. Finally, PIP4K2A tagged with a green fluorescent protein was overexpressed in SH-SY5Y and observed under fluorescence microscopy.

Results: From the cell viability test, we determined the IC50 values which were 10 μM for acrolein and 400 μM for palmitic acid, respectively. In the cells acrolein induced AD biomarkers such as enhanced phosphorylated Tau and reduced Abelson helper integration site-1 while palmitic acid inhibited insulin signaling pathway. The combination of acrolein and palmitic acid reduced p-Akt and p-ERK 1/2, worsened cell survival, promoted AD pathogenesis, which involved PIP4K2A alteration. Further experiments showed that PIP4K2A localized on the cell membrane, triggered downstream pathway to activate hyperphosphorylation of Tau and drove cells to apoptosis. THZ-P1-2, a PIP4K2A inhibitor, ameliorated the AD pathogenesis by reducing Tau phosphorylation and apoptosis.

Conclusions: Application of palmitic acid and acrolein in SH-SY5Y cell culture could induce insulin resistant and AD-like pathologies which mimicked the condition of sporadic AD patients suffering from neurodegeneration with metabolic syndrome. The model cells had raised PIP4K2A expression and caused Tau pathologies and apoptosis process.