Figure 5.

Prochondrogenic activity of ACVR1^Q207E is suppressed by BMP antagonist NOG. (A) Chicken micromass cells were co-infected with RCAS virus encoding ACVR1^WT, ACVR1^Q207D−c.a. or indicated FOP mutation (viral titre 2 × 10⁷ PFU/ml) and increasing titres of RCAS expressing NOG. Cultures were stained with Alcian blue after 7 days to visualize cartilage formation. While ACVR1^Q207D−c.a-infected cultures produced extracellular cartilage matrix in the presence of NOG, control and ACVR1^WT cultures were strongly inhibited by NOG. Cartilage matrix production of ACVR1^Q207E and ACVR1^R206H infected cultures was also inhibited with increasing NOG titres but were less sensitive compared with ACVR1^WT. (B) Photometric Alcian blue quantification of chicken micromass cultures shown in (A) bars represent mean ± SD of quadruplicate samples from one representative of three experiments. Two-tailed Student's t-test was performed. Significant differences in comparison with ACVR1^WT with the indicated NOG titre are given as: *P < 0.05; **P < 0.01; ***P < 0.001, ns not significant, n = 4.