The Expression And Significance Of ERα36 In Central Nervous System And Its Effect On PC12 Cell Apoptosis And Differentiation

As we all know that estrogen has a wide neuroprotective effect on central nervous system (CNS). Estrogen can bind to intracellular estrogen receptors and exert act as transcription factors to regulate downstream gene transcription. There are two types of classic estrogen receptors (ERs), ERαand ERβ. ERαcontains three members: ERα66, ERα46 and ERα36. Different from ERα66 which is mainly expressed in nuclear, ERα36 is mainly expressed in cytoplasm and plasma membrane. In many cancer cells, ERα36 can transduce membrane initiated signal pathway and promote cell proliferation. Our former study shows that ERα36 is widely expressed in SD rat brain. However, very little is known about the function of ERα36 in CNS.We first detected the expression and location of ERα36 in Kunming mouse brain of different development stages and several neuron cells by Western Blot and immunofluorescence cytochemistry. Then, flow cytometry and Hoechst33342 staining were performed to study the effect of ERα36 down-regulation on cell apoptosis and the protein expression changes induced by MPP~+ after pretreatment with E2 on PC12 cell. Finally, undifferentiated PC12 cell was used to study the effects of ERα36 on protein expression changes in cell differentiation. The purpose of this research is to provide a theoretical basis to illustrate the function and mechanism of ERα36 and the relationship between ERα36 and neurodegenerative disease in CNS.The results show that:(1) ERα36 was widely expressed in different regions of Kunming mouse brain and neuron cells; there is no significant change of ERα36 in hippocampus, cerebellum and brain stem of different development stages. But in cortex, the expression of ERα36 increase along with the increase of age, while ERα66 and ERα46 increase at first and then decrease along with the increase of age.(2) After pretreatment with E2, the apoptosis reduced by MPP~+ (48h) of PC12 cell and PC12-ERα36L1 cell decrease, and the survival rate of PC12-ERα36L1 cell is higher than that of PC12 cell. The expression of Caspase-3 in PC12-ERα36L1 cell is lower than that of PC12 cell. (3) NF-κB and p-P38 were activated after ERα36 was down regulated by the transfection of ERα36 shRNA in undifferentiated PC12 cell (PC12-unD cell). And the expression of Nestin decrease while the expression of Tubulin and Neu-n increase in PC12-unD cell.Conclusions: (1) ERα36 is widely distributed in central nervous system and neuron cells. (2) Estrogen pretreatment can reduce the apoptosis induced by MPP~+ and ERα36 may be involved in the process. (3) ERα36 gene silence can influence the differentiation of PC12 cell.