Involvement of signal transducers and activators of transcription in trophoblast differentiation

Introduction: To explore the involvement of signal transducers and activators of transcription (STATs) in trophoblast differentiation. Methods and results: First, the localization of STATs in human placentas was detected via immunohistochemistry (IHC) and immunofluorescence (IF). Cytotrophoblasts (CTBs) expressed both STAT1 and 3, but syncytiotrophoblasts (STBs) did not. Staining for these two proteins showed a distinct upregulation from the proximal part to the distal end of cell columns. STAT5B was mainly expressed in the STBs, low in the CTBs, and absent in the extravillous tmphoblasts (EVTs). Next, the 44 placenta samples were tested via western blot (WB) and quantitative real time polymerase chain reaction (qRT-PCR). We found a decrease in STAT1 and 3 and an increase in STAT5B as gestation increased from five to 10 weeks. Then, an in vitro co-culture model of placenta with or without decidua stromal cells (DSCs), as detected via flow cytometry, revealed an increase in the human leukocyte antigen (HLA)-G positive rate in trophoblasts from placentas co-cultured with DSCs, accompanied by an increase in p-STAT1 and 3 and a decrease in p-STAT5 and STAT5B. Finally, mRNA of matrix metalloproteinases (MMPs) and integrins after STAT silencing in HTR-8/SVneo was detected via qRT-PCR. STAT1 silencing decreased MMP9 expression, STAT3 silencing decreased MMP9, integrin alpha 6, and beta 4 expression, and STAT5B silencing increased MMP2 and integrin beta 1 expression. Discussion: Different trophoblasts showed distinct STAT expression profiles which were related to their MMP and integrin expression. DSCs promoted trophoblast differentiation into EVTs, possibly by regulating the STAT expression of the trophoblasts.