Expression Of ESRP1 In The Human Placenta And Its Effect On The Trophoblast Function

Background : Epithelial splicing regulatory protein 1(ESRP1)is an epithelial cell-specific alternative splicing regulator discovered in recent years.ESRP1 regulates the alternative splicing of a variety of precursor m RNA through post-transcriptional mechanisms,associated with reorganization of the cytoskeleton and maintenance of cell-cell adhesion,tight junctions,and cell polarity.ESRP1 has been demonstrated to play essential roles in the epithelial-to-mesenchymal transition(EMT)splicing program,and is widely involved in the embryonic organogenesis,carcinogenesis and progression and somatic cell reprogramming.Accumulating evidence suggests that villous cytotrophoblasts undergo a partial EMT when differentiating into extravillous cytotrophoblasts and obtain the capacity to migrate and invade.However,the role of ESRP1 in placental development remains to be elucidated.Objective: To detect the exact expression profile of ESRP1 in the placental tissues throughout pregnancy.To examine the effects of ESRP1 on the function of trophoblast cell line HTR-8/SVneo cells and villous explants.To detect the expression level of ESRP1 in the placental tissues of early-onset preeclampsia and gestational age-matched normal pregnancy.Methods: Immunohistochemistry and western blotting assays were used to detect the expression and localization of ESRP1 protein in the placentae at different stages of pregnancy.Cellular immunofluorescence assay was performed to detect the expression of ESRP1 in HTR-8/SVneo cells,and small-interfering RNA was used to knockdown the expression of ESRP1 in HTR-8/SVneo cells.Cell proliferation assay was performed by using an Ed U cell proliferation kit;the effects of ESRP1 on the migration and invasion of HTR-8/SVneo cells were evaluated by using the scratch wound-healing assay and transwell invasion assay;the expression levels of E-cadherin,N-cadherin,vimentin and CD44 in HTR-8/SVneo cells were detected by western blotting.Small-interfering RNA was utilized to down-regulate the expression of ESRP1 in villous explants derived from early pregnancy,and the outgrowth and migration distance of extravillous trophoblasts was calculated.Immunohistochemistry and western blotting assays were used to detect the difference of ESRP1 expression level in the placental tissues between patients with early-onset preeclampsia and gestational age-matched normal pregnancy women.Results: ESRP1 was expressed in placental tissues at different stages of pregnancy,and was mainly localized within the cytotrophoblasts,cell column trophoblasts and interstitial extravillous trophoblasts.The expression level of ESRP1 in placental tissues in the first and second trimester was lower than that in the third trimester.During early pregnancy,the expression level of ESRP1 on the proximal trophoblast column was significantly higher than that on the distal trophoblast column.ESRP1 knockdown promoted the migration and invasion of HTR-8/SVneo cells without affecting the proliferation capacity.ESRP1 knockdown resulted in the up-regulation of N-cadherin,vimentin and CD44 proteins in HTR-8/SVneo cells.Down-regulation of ESRP1 significantly enhanced the outgrowth and migration of extravillous trophoblasts from the first trimester placental villi.There was no significant difference in the expression level of ESRP1 between the early-onset preeclamptic placentae and the gestational age-matched normal placentae.Conclusion: This study demonstrated the expression profile of ESRP1 in placental tissues at different stages of pregnancy and its effect on trophoblast function.The results suggested that ESRP1 may be a negative regulator of trophoblast migration and invasion,and play an important role in the process of placental development.ESRP1 affected the migration and invasion of trophoblasts by regulating the process of EMT.This study investigated the regulation of trophoblast function by the alternative splicing regulator ESRP1,and provided new insights into understanding the placental development and placental-derived diseases such as early-onset preeclampsia at the post-transcriptional level.