Figure 3.

ERα is selectively expressed in human trophoblasts and increases with trophoblast differentiation. Freshly isolated human placental cytotrophoblasts were suspended in DMEM containing 2% FBS and cultured for up to 96 h. A, RNA was isolated from cells either before culture (day 0) or after 24, 48, 72, or 96 h, and the expression of hCYP191.1, ERα, and ERβ were analyzed by qRT-PCR. Data are the mean ± sem of values from three independent experiments, each conducted in triplicate, and are expressed relative to those of cytotrophoblasts before culture. *, P < 0.05 for 0, 24, and 48 h. B, Nuclear proteins (30 μg) extracted from freshly isolated cytotrophoblasts (Cyto) and from syncytiotrophoblast (Syn) after 72 h of culture were analyzed by immunoblotting using antisera to ERα and ERβ [Ab-7 (AER320) mouse monoclonal; Neomarkers, Fremont, CA] and ERβ (PA 1-310B, rabbit polyclonal; Affinity Bioreagents, Golden, CO). COS-7 cells overexpressing ERα or ERβ were analyzed as a control.