Figure 5

Activation of BMP responsive promoter construct by ectopic expression of axolotl BMP-2. The graphic summarizes BMP responsive luciferase activity performed in the human chondrocyte cell line, C28/I2, after the transfection of BMP-2, Noggin or BMP-2 and Noggin expression plasmids combined. For each condition, the BMP responsive reporter construct and the β-galactosidase reporter construct were always co-transfected. The first bar shows the basal luciferase activity (transfected with mRFP without axolotl BMP-2 or Xenopus laevis Noggin) of 4.6 ± 0.6. The second bar shows a significant increase (27.7 ± 3.4) in luciferase activity when the axolotl BMP-2 expressing plasmid was transfected. The third bar indicates that transfection of the Xenopus laevis Noggin expressing plasmid decreased luciferase activity (3.1 ± 0.3) compared to basal activity. The fourth bar shows the luciferase activity from the co-transfection of the axolotl BMP-2 and the Xenopus laevis Noggin expressing plasmids. This co-expression resulted in a significant decrease in luciferase activity (13.3 ± 1.9) compared to the expression of BMP-2 alone. All results (mean ± sd; n = 3/condition) are expressed as relative light unit (RLU) normalised with β-galactosidase activity.