The Mechanism Of MCM6 In The Regulation Of Dentritic Cells Treated With 17β-estrogen

Dentritic Cells are professional antigen-present cells, they play a critical role in the initiation of primary immune responses and stimulate naive T cells. Female sex hormones, including 17β-estradiol (E2), are strongly implicated in gender bias of autoimmune diseases. Meanwhile, DCs are present in abnormal numbers in the peripheral blood and synovial fluid of patients with autoimmune diseases, which indicate DC also play a role in autoimmune diseases. It is reported that E2 could regulate the maturation and the function of DCs, but the mechanism remains unknown. Therefore, to explore the mechanism how E2 regulate the DCs might be important to understand the gender bias of the autoimmune diseases.Our previous study found MCM family members participated in the regulation of the immune cells, so this study focused on the signal of how E2 modulated DCs and the role of MCM6 in this regulation. Besides, we tested the level of MCM6 in the patients with SLE, which is a typical autoimmune diseases, in order to reveal the mechanism of the gender bias in SLE. Firstly, we demonstrated that E2 could up-regulate expression level of CD40, CD80, CD86 and MHCⅡin DCs by using RT-PCR, western blot and flow cytometry, meanwhile, E2 could regulated the MCM6 level of DCs. Then we found E2 regulated the MCM6 and CD40 levels through the activation of p38 and JNK. Is there any relation between MCM6 and CD40? To answer this question, we developed the siRNA targeting MCM6 and after knocked down the MCM6 protein, we found the up-regulation induced by E2 was abolished. To further study the function of MCM6 in DCs, we tested the cell proliferation by cck-8 kit and 3H assay, the apoptosis percentage by PI & Annexin V kit, the endocytosis by FITC-dextran, the ability of DCs driving allogeneic T cells by 3H assay, the secretion of IL-12p70 and TNF-a level by ELSIA kit. We found the down-regulation of MCM6 would only affect the ability of DCs driving T cells but not their other functions.Besides, we also collected several clinical samples from drum town hospital and found that MCM6 expression levels were significant higher in SLE patients than those in healthy controls. Importantly, the MCM6 level was relative to the serum level of E2 in SLE patients. In order to study MCM6 function in the cell cycle of DCs, we generated the mutant JNK1 plasmid by chemical-genetic stratage, which had the normal kinase activity but could be specifically inhibited by ATP analog.To sum up, in the present study we demonstrated that E2 can induce CD40 expression in DCs via the activation of p38 and JNK pathways in a MCM6 dependent way. MCM6 also contribute to the immunostimulatory function of DCs in driving T cells. MCM6 may be a critical mediator of sex-based differences in autoimmune disease. Our findings first clarify the mechanism of E2-induced CD40 expression and may provide a potential novel therapy target for autoimmune diseases.