Figure 3. PRDC^WT and PRDC^C120S are potent BMP inhibitors.

A-B) Inhibition of BMP2 by PRDC^WT (A) and PRDC^C120S (B) was analyzed in a luciferase promoter assay. A BMP-responsive BRE-luc stable cell line was treated with 1 nM of BMP2 alone or combined with PRDC proteins titrated from 0.1 nM to 7.5 nM. Luciferase activity was normalized (100%) to cells treated with BMP2 ligand alone. Errors bars represent the standard deviation of 4 replicates. C) Activities of PRDC^WT and PRDC^C120S were measured by their ability to inhibit BMP signaling in vivo. Control buffer (PBS, 0.1% BSA), PRDC^WT or PRDC^C120S were injected at low (1 μM) and high (10 μM) concentrations into the blastocoel cavity at blastula stage 9 of Xenopus embryos, which were assayed by in situ hybridization for expression of the BMP target gene sizzled at stage 11.5 or cultured to stage 32/33 to assess the whole embryo phenotype.