Fig 7. Transient transfection of a transmembrane form of DRAGON restored the BMP signaling activation and trophoblast formation.

(A). G-GFP or AR1-c1 hES cells were transfected with the engineered DRAGON™ vector or the control pDisplay vector, together with the Id1-luciferase reporter plasmid and the EF.lacZ as in Fig 6a. Six hours after transfection, cells were stimulated in the absence (-) or presence (+) of BMP4 for 20 hours and harvested. The Id1-luc activity was measured, normalized by the lacZ activity, and calculated relative to the level without BMP4 stimulation (defined as 1) for each cell type. The normalized mean and SD values (n=4) were plotted. The difference between Samples A and B is significant (p<0.05). (B). Human CGα gene expression in AR1-c1 cells after DRAGON™ transfection and BMP4 stimulation. G-GFP (samples 1) or AR1-c1 (samples 2) hES cells in pair were transfected with the DRAGON™ or control vector at day 0 for six hours, and treated in the absence or presence of BMP4 (50 ng/ml) for 2 days. Two days after, the same treatment was repeated. After a total of 5 days, various types of transfected cells were either harvested for RT-PCR (B) or fixed for TROMA-I immuno-staining (C). Scale bar: 50 μm.