The Effect Of PI3K-AKT-mTOR Signal Pathway On The Expression Of Foxp3

Abstract :Objective To investigate the effect of PI3K-AKT-mTOR signal pathway on the expression of Foxp3 in vivo.;to explore the effect of the expression of Foxp3 and the activation of the mTOR through different doseages of RAPA ,and analysis whether it has dependability between the level of Foxp3's expression and PI3K-AKT-mTOR signal pathway's activation,so it can provide a new way to explore the concrete mechanism of Foxp3's expression induced by RAPA.Methods 60 Kunming-strain mice at the age of 8 weeks were divided into a control group (A) and three experimental groups (B,C,D) . The mice in the groups B,C and D were fed with RAPA 0.2 mg·d-1,0.4 mg·d-1 and 0.6 mg·d-1 via intragastric administration. The mice in the group A were given with sterile water as the control group. After three weeks, the peripheral blood (with EDTA anticoagulant) was collected under sterile conditions and the splenocytes were seperated to generate a single-cell suspension. The levels of CD4~+CD25~+Treg cells in the mouse peripheral blood and splenocytes were detected by flow cytometer. (The ratio of CD4~+CD25~+Treg cells to CD4+ Treg cells). The expression of Foxp3 mRNA in spleen cells of mice were detected with RT-PCR assay. Variation of p-mTOR expression in spleens were observed with immunohistochemical staining (SP method) and the mean optical density of protein p-mTOR's expression between experimental groups and control group were tested with computer image analytical technique.Results 1 The CD4~+CD25~+Treg cells in the mouse peripheral blood and splenocytes of the experimental groups (B,C,D) were (9.62±1.43,13.76±1.97,15.41±2.45) % and (12.23±4.56,23.03±6.18,25.17±6.42) %. The CD4~+CD25~+Treg cells in the mouse peripheral blood and splenocytes of the control group (A) were (3.52±0.65) % and (6.53±3.01) %. The levels of the CD4 + CD25 + Treg cells either in the peripheral blood or splenocytes of the groups B, C and D were significantly higher than group A (P<0.05). There were significant differences between the groups C,D and B according to the level of the CD4~+CD25~+Treg cells (P<0.05) while there were no significant differences between the groups C and D according to the level of the CD4~+CD25~+Treg cells (P>0.05).2 The levels of Foxp3 mRNA in spleen cells of mice among experimental groups (B,C,D) were 0.4853±0.0574,0.7886±0.1085 and 0.9639±0.2015 respectively,which were significantly higher than control group A(0.1345±0.0271)( P< 0.05);The average opticals of protein p-mTOR's expression among experimental groups (B,C,D) were 0.2326±0.0431,0.1156±0.0223 and 0.0556±0.0041, respectively,which were lower than control group A(0.4223±0.0534)(P<0.05). It showed that there was a negative correlation between the expression of Foxp3 mRNA and protein p-mTOR which were handled through pearson correlation analysis.Conclusion 1 RAPA can induce Kunming-strain mouse CD4~+CD25~+Treg cells proliferations in vivo and the level of CD4~+CD25~+Treg cells proliferations in vivo is influenced by the dose of RAPA used.2 RAPA can enhance the expression of Foxp3 by inhibiting PI3K-AKT-mTOR signal pathway. There is a negative correlation between the activation of PI3K-AKT-mTOR signal pathway and the expression of Foxp3.