Effects Of Mutated Presenilin 1 On The Functions Of RA-induced PC12 Cells

The mutation of Presenilin 1 is one of the primary cause of the early onset familial autosomal dominant inherited Alzheimer′s disease (EOFAD). The studies demonstrated that the PS-1 mutations can result in unnormal cleavage of APP and increase the production of Aβ42 .The cells expressing the mutated PS-1 gene are more sensitive to apoptosis induced by apoptosis induction factors. The many studied results, whether morphologic or functional, had demonstrated that the occurrence of AD is mainly involved in the cholinergic neurons. However, up to now, there are more difficulty in separation and purification, especially enrichment of cholinergic neurons. So, it is one of the focuses looking for a substitution of cholinergic neurons. In this research, we propose PC12 cells induced by RA as in vitro substitute cells of cholinergic neurons. We observed the changes of morphologic and function of RA-induced PC12 cells by the MTT assay, flow cytometry, TUNEL method, spectrophotometer, radiochemistry assay, and so on, in order to choice the best induced condition. On the basis of successful induced PC12, we further investigated the effect of mutated PS-1 on the morphologic and functions of PC12 cells following RA-induced, and discussed the related mechanisms. The results were as follows:1. RA elevated the activity of ChAT under the concentration between 1 to 20 μmol/L. The activity of ChAT induced by the 10μmol/L RA was higher than that induced by the others concentrations. RA didn't influencethe activity of AchE in the experiment.2. The apoptosis of RA-induced PC12 cells was markedly increased when RA concentration was over 10μmol/L. 3. A concentration-dependent inhibition of proliferation was demonstrated in the RA-induced PC12 cells. PC12 cells proliferation was blocked in the G1→S phase. 4. An inhabition of proliferation was demonstrated in the RA-induced PC12 cells expressing PS-1 mutant L286V. The proliferation of the cells was blocked in the G1→S phase.5. The activity of ChAT and AchE was inhabited in the RA-induced PC12 cells that carried PS-1 mutant L286V.6. Whether with or without FBS, PS-1 mutant L286V can accelerate the apoptosis of RA-induced PC12 cells. This action was enhanced markly under the culture without FBS.Our studies indicated that RA-induced PC12 cells showed the cholinergic properties and 10μmol/L was the optimal concentration. RA can be used to induce the PC12 cells and make them show the properties of cholinergic neuron. RA-induced PC12 cells can be used in some research of AD as substitute of cholinergic neuron. The RA-induced PC12 cells expressing PS-1 mutant L286V showed that proliferation was blocked in the G1→S phase and the activity of ChAT and AchE was inhabited. Whether with or without FBS, PS-1 mutant L286V can accelerate the apoptosis of RA-induced PC12 cells. This action was enhanced markly under the culture without FBS.