Folate Deficiency Decreases Apoptosis Of Endometrium Decidual Cells In Pregnant Mice Via The Mitochondrial Pathway

Objective:It is well known that maternal folate deficiency results in adverse pregnancy outcomes, including embryonic malformations, abortion, preterm, low birth weight and so on. Among them, the relationship between folate deficiency and neural tube defects (NTD) has been recognized by the scholars. Previous studies focused their eyes on the effect of folate deficiency on the fetus while ignoring its impact on the maternal aspects. In addition to aspects in embryonic development, maternal uterine receptivity and decidualization of stromal cells are also very important for a successful pregnancy. Our previous study revealed that there was no effect of folate deficiency on embryo implantation, and both the expression of uterine receptivity marker genes and the number of implantation sites showed no significant difference between the folate deficiency group and control group. However, the outcome of the folate-deficient pregnant mice was not favorable, which indicates more embryo loss and smaller embryo volume. In this study, we investigated whether apoptosis of the decidual cells was impaired under folate-deficient conditions and explored maternal uterine endometrium decidualization in that condition.Methods:A folate-deficient pregnant mouse model and a normal diet pregnant mice model were established. Flow cytometry, JC-1 detection and TUNEL were used to detect apoptosis of the decidual cells isolated from pregnant mice on day 7 and 8. TEM was used to observe the morphology of mitochondria and endoplasmic reticulum. Immunohistochemistry was used to detect the protein expression and location of Bax and Bcl2. The expression of Bax、Bcl2、cleaved-Caspase3、pro-Caspase3、cytochrome c were detected using Western blot. Immunofluorescence and laser scanning confocal microscope were used to observe the release of cytochrome c from mitochondria to cytoplasm. Western blot and RT-PCR were used to detect the expression of genes Hoxa10, BMP2, MMP2, MMP9, which were related to endometrium decidualization.Results:Decidual cells of mice in the control group exhibited dilation of the endoplasmic reticulum and distended mitochondria, while the folate-deficient mice did not show corresponding changes. Flow cytometry, JC-1 detection and TUNEL all showed that folate deficienct group had less apoptosis of decidual cells. Western blot revealed that folate deficient group expressed less Bax and cleaved-Caspase3 while the expression of Bcl2 and pro-Caspase3 was alike in the two group. Immunohistochemistry results of Bax and Bcl2 were consistant with Western blot. Mitochondria of folate deficient decidual cell released less cytochrome c to plasma compared with the normal group. Decidual tissue from folate-deficient group expressed less Hoxa10, BMP2, MMP2 and MMP9.Conclusion:Apoptosis of folate-deficient decidual cells was inhibited and there was significant difference between folate deficient group and normal group in protein expression and distribution related to mitochondria. These results indicate that folate deficiency may inhibit apoptosis of mouse decidual cells via mitochondria pathway, and then the decidualization of endometrium stromal cells was impaired.