Expression and significance of SATB1 and wnt/β-catenin signaling molecule in the placenta of preeclampsia

Abstract

To explore the role of specific AT rich sequence binding protein 1(SATB1) and wnt/β-catenin signaling pathways in the regulation of trophoblast invasion and its effect in the pathogenesis of preeclampsia. From March 2013 to March 2014, 20 cases of human villous tissues (early pregnancy group) from women of 8-10 gestational weeks who received artificial abortion at the First Affiliated Hospital of Chongqing Medical University, 18 cases of placental tissues (mid-pregnancy group) from women of 18-20 gestational weeks who had labor induction by water bag, 20 cases of placental tissues (normal full-term group) from healthy full-term pregnancy women and 20 cases of placental tissues (preeclamptic group) from women with preeclampsia who received elective c-section in were collected. Immunohistochemical SP method was utilized to determine the position of SATB1 and beta-catenin in villous tissues or placental tissues. Western blot was performed to analyze the expression level of SATB1 and beta-catenin in villous tissues or placental tissues. Immunofluorescence assay was used to determine the location of SATB1 and β-catenin in HTR8/SVneo cells. Western blot was performed to detect the expression level of SATB1 and beta-catenin in HTR8/SVneo cells cultured in normoxia and hypoxia reoxygenation (H/R) condition. Co-Immunoprecipitation detection was used to evaluate the interaction between SATB1 and β-catenin in placental tissues in preeclamptic group and HTR8/SVneo cells in H/R group. Gelatin zymography analysis was used to measure the activity of matrix metalloproteinases (MMP)-2 and 9 in placental tissues from preeclamptic group and HTR8/SVneo cells in H/R group. (1) In the normal full-term group, rare syncytiotrophoblastic nodule, less fibrinoid necrosis and abundant numbers of capillary could be observed in placental tissues. In comparison, there were obvious vacuolation in the cytoblast of syncytiotrophoblast, rich fibrinoid necrosis and poor numbers of villous capillary in placental tissues from preeclamptic group. (2) SATB1 could be found by immunochemical staining in placenta or villous tissues from all the groups. The staining intensity of SATB1 were more weakening in preeclamptic group than in the normal full-term group. (3) β-catenin could be found by immunochemical staining in placenta or villous tissues from all the groups. The staining intensity of β-catenin were more weakening in preeclamptic group than in the normal full-term group. (4) The protein expression levels of SATB1 in early pregnancy group, mid-pregnancy group, normal full-term group and preeclamptic group were 0.300 ± 0.009, 0.271±0.015, 0.238±0.018 and 0.153±0.007, respectively. The protein levels of β-catenin among the above groups were 0.743±0.041, 0.648±0.021, 0.549±0.069 and 0.269±0.047, respectively. Both the expression of SATB1 and β-catenin protein were significant decreased in placental tissues from preeclamptic group compared with the other three groups. (5) The SATB1 and β-catenin protein was located in nucleus of trophoblast and a small amount was in the cytoplasm. The fluorescence intensity of both SATB1 and β-catenin in the H/R group were significantly decreasing when compared to the normoxia group. (6) HTR8/SVneo cells in H/R group showed a significant decrease in both SATB1 and β-catenin protein levels when compared to the normoxia group. The protein level of SATB1 in the normoxia group was 0.213±0.005, while was 0.083±0.021 in the H/R group. The protein level of β-catenin in the normoxia group was 0.797±0.081, and was 0.543±0.131 in the H/R group. (7) There was an interaction between SATB1 and β-catenin in placental tissues from the preeclamptic group and HTR8/SVneo cells exposed by H/R. (8) The enzymatic activity of MMP-2 and MMP-9 protein were decreased significantly in placental tissues from the preeclamptic group (2.251±0.310, 1.447±0.102, respectively) when compared to the normal full-term group (7.098±0.451, 5.502±0.197, respectively). MMP-2 and MMP-9 were significantly decreased in the H/R group (0.471±0.104, 0.297±0.103, respectively) when compared to the normoxia group (0.842±0.209, 0.595±0.100, respectively). The expression of SATB1 decreased in the placenta of preeclampsia. This may influence the activity of MMP-2 and 9 by regulating Wnt/β-catenin signaling pathways, affect trophoblast invasion and eventually result in preeclampsia.