Effect Of The Novel Estrogen Receptor Alpha 36 Low Expression On PC12 Cell Proliferation And The Apoptosis

Estrogen receptor is widely distributed in central nervous system. Recent study shows that besides improve learning and memory via the combination with estrogen, estrogen receptor can also mediate the process of anti-inflammation and anti-oxidation effect. ERα36, the newly identified estrogen receptor, is also found widely distributed in central nervous system. But the mechanism of MISS mediated by ERα36 is not clear. PC12 cell has the dopaminergic uptake system, and is always used as dopaminergic neurons model. In this study, our purpose is to study the effect of ERα36 low expression on PC12 proliferation and apoptosis induced by MPP+ in order to study the effect of ERα36 in membrane initiated estrogen signal pathway in neuron growth and apoptosis and provide a theoretical basis to illustrate the mechanism of membrane initiated estrogen signal pathway in CNS.Firstly, the expression and location of ERα36 in primary cultured hippocampal neurons and PC12 cell were observed by western blot and immunohistochemistry. Then ERα36 shRNA plasmid was transfected into PC12 cell to establish ERα36 low expression cell model PC12-36L1 which is screened by G418. After that, flow cytometry was performed to study the changes of cell cycle and the effect on cell proliferation after ERα36 gene knocked down. The expression of PCNA and cyclinD1were both observed. Finally, PC12-36L1 cell model was used to study the influence of ERα36 low expression on cell apoptosis after treatment with MPP+ in vitro. The expression of AKT and P38 related to apoptosis signal pathway were also detected to study its possible mechanism.The results showed that:(1)Both of primary cultured hippocampal neurons and PC12 cells have ERα36 expression. ERα36 is mainly distributed in nuclear in both primary cultured hippocampal neurons and PC12 cell.(2)The ERα36 low expression cell model PC12-36L1 was successfully established and the ERα36 expression was about 47﹪of PC12 cells. In PC12-36L1 cell, the expression of PCNA and cyclinD1 that related to cell growth and proliferation increase. S stage shortens and doubling time decrease shows that the growth and proliferation of PC12-36L1 cell increase.(3)PC12cell and PC12-36L1 cell all shows apoptosis after treatment with MPP~+. And the p-AKT expression was down regulated while the p-P38 expression was up regulated in both PC12cell and PC12-36L1 cell. But the survival rate of PC12-36L1 cell was higher than that of PC12 cell. We also observed that the p-AKT expression of PC12-36L1 cell was higher than that of PC12 cell while the p-P38 expression was lower than that of PC12 cell.Conclusion: ERα36 could be expressed in both hippocampal neurons and PC12 cells. Down regulation of the ERα36 by RNA interference can promote cell growth and proliferation and reduce the apoptosis induced by MPP~+ in PC12 cell. It suggested that ERα36 can inhibit the excess proliferation of PC12 cell and medicate the apoptosis.