The Role Of The Interaction Between HIF-1α And Notch-1Signaling In Alzheimer’s Disease And Related Mechanism

Objective:This study aims to investigate the role which the interaction between hypoxia-inducible factor-la and Notch-1signaling pathway might plays in Alzheimer’s disease (AD), utilizing ADDLs to intervene primary mouse cortical neuron and astrocyte co-culture as an in vitro model of AD.Methods:In this study, Aβ oligomers (ADDLs) was applied to intervene the primary mouse cortical neuron and astrocyte co-culture system to mimic an in vitro AD model. Immunofluorescence staining was used to identify the expressions of HIF-la and Notch-1protein in neurons and astrocytes; After that, a HIF-1α inducer DMOG, a HIF-1α inhibitor YC-1and a Notch-1signaling pathway blocker (γ-secretase inhibitors) DAPT were applied to the in vitro model of AD; The cell viability of the primary co-culture under various conditions were assessed with CCK-8assays; And Western Blot method was used to detect expression levels of HIF-1α and NICD(Notch-1intracellular domain) of the primary co-cultured system under different conditions. Besides, real-time PCR was used to detect the mRNA level of apoptosis-related proteins caspase-3of the primary co-cultured system under different conditions.Results:Firstly with immunofluorescence staining, HIF-la was expressed in some of the neurons and astrocytes of the primary mouse cortical neuron and astrocyte co-culture system, while Notch-1was mainly expressed in most of the astrocytes of the primary co-culture, with no obvious expression of Notch-1being found in the neurons. Secondly, CCK-8assays showed that comparatively low concentration of ADDLs had no significant effect on the cell viability of primary mouse cortical neuron and astrocyte co-culture, but ADDLs at higher concentrations showed significant toxic effect on the cell viability of the primary co-culture system time-dependently and concentration-dependently. Along with the above toxic effect, the intervention of ADDLs up-regulated the NICD of HIF-1α levels of the primary co-culture system with similar changing tendency, in which protein level increased after the intervenetion of ADDLs and then reduced. YC-1and DAPT both showed significant protective effect against ADDLs induced toxic effect to cell viability of the primary co-culture at4hours. What’s more, both YC-1and DAPT inhibited the up-regulation of mRNA level of apoptosis-related protein caspase-3of the primary co-culture induced by ADDLs at the same time point. Along with the above protective effects, YC-1and DAPT significantly inhibited the up-regulation of HIF-1α and NICD levels of the primary co-culture system induced by ADDLs at4hours. While at24hours, there were no significant effect of YC-1and DAPT to cell viability and HIF-1α and NICD levels of the in vitro AD model.Conclusion:The toxicity of Aβ oligomers (ADDLs) correlated with a transient up-regulation of HIF-la and NICD levels, and furtherly the interaction between HIF-la and Notch-1signaling pathway; YC-1and DAPT both can antagonize the toxic effects and apoptosis induction of ADDLs, and the protective effects might contribute to the regulation of the interaction between HIF-1α and Notch-1signaling pathway.