Downregulation of a mitogen-activated protein kinase signaling pathway in the placentas of women with preeclampsia.

Objective: To investigate whether the activity of the three mitogen-activated protein kinases (Jun aminoterminal kinase, extracellular regulated kinase, and p38) is altered in placental tissue of women with preeclampsia and hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome.

Methods: Placental activity (measured by immunoprecipitation-kinase assay) and protein expression (measured by western blot) of Jun aminoterminal kinase, extracellular regulated kinase, and p38 mitogen-activated protein kinase were measured in four groups of eight women each with preeclampsia, HELLP syndrome, and normal vaginal or cesarean deliveries. To further characterize the Jun aminoterminal kinase signal transduction pathway, phosphorylation of c-Jun, a downstream effector of Jun aminoterminal kinase- mitogen-activated protein kinase, was analyzed by western blotting, and the activity of Rac1, an upstream activator of the Jun aminoterminal kinase signaling pathway, was determined by pull-down assay.