Expression of Extracellular Signal-Regulated Kinase1/2 and p38 Mitogen-Activated Protein Kinase in the Invasive Trophoblasts at the Human Placental Bed

BackgroundMitogen-activated protein kinases (MAP kinases) participate in signal transduction pathways that control embryogenesis, cell differentiation, cell proliferation and cell death. The roles of extracellular signal-regulated kinase1/2 (ERK1/2) and p38 MAP kinase in the differentiation and invasion of human trophoblasts have been studied. However, the in vivo expression and activation of ERK1/2 and p38 at the placental bed have not been elucidated.MethodsThe study group consisted of placental bed biopsy tissues obtained from the pregnancies without preeclampsia (n = 24) and with preeclampsia (n = 8) between 31 and 40 weeks of gestation. We evaluated the expressions and phosphorylations of ERK1/2 and p38 MAP kinase in the invasive trophoblasts in the placental bed tissues using immunohistochemistry.Resultsp38 and phospho-p38 MAP kinase were not detected in invasive trophoblasts in cases or controls. ERK1/2 and phospho-ERK1/2 were positive in invasive trophoblasts albeit with variable staining. Phosphorylation of ERK1/2 was significantly less frequent in invasive trophoblasts in placental bed biopsies from women with preeclampsia compared with normotensive controls.ConclusionThese findings suggest that preeclampsia is associated with decreased activation of ERK1/2 in invasive trophoblasts in vivo.