Figure 2. The EP receptors are expressed in chondrocytes and regulated by BMP-2 and PGE2.
Primary murine sternal chondrocytes were isolated and plated in monolayer culture. Sixteen hours after plating, chondrocyte cultures were treated with either vehicle, 1μM PGE2, 100 ng/ml BMP-2, or PGE2 and BMP-2 in combination. Total RNA was isolated from the cultures after 2, 5, or 8 days of culture and real time PCR was performed as described in Methods. Real-time PCR analysis was performed using primers specific for the EP 1, 2, 3, and 4 receptors and expression levels were normalized to β-actin. The relative expressions of the various EP receptors were measured in 2 day vehicle cultures (A). The gene expression of the EP1 (B), EP2 (C), EP3 (D), and EP4 (E) normalized to the 2-day vehicle control level was determined after 2, 5, and 8 days in culture. Asterisk denotes p≤0.05 with comparisons made to the control value at each respective day.
