Fig. 1. Comparison of Gdf3 and Nodal signaling activities. (A)
Schematic depiction of mouse Gdf3 and modified Gdf3 proteins; the sites of
prodomain cleavage is indicated (arrows). (B) Gdf3 activity is Cripto
and Foxh1 dependent. The indicated plasmids were co-transfected into 293T
cells together with the A3-luc reporter. (Insets) Western blot
detection of mature Nodal (
12 kDa) and mature Gdf3 (
17 kDa) proteins
in conditioned media using
-Nodal antibody or
-Gdf3 antibody.
(C) Gdf3 activity is facilitated by Cripto, but not Cryptic. 293T cells
were co-transfected with expression vectors for Nodal or bf-Gdf3, Foxh1 and
FLAG-epitope-tagged Cryptic, Cripto or Oep; control samples correspond to
cells transfected with Nodal or bf-Gdf3 and Foxh1 without EGF-CFC proteins.
(Inset) Western blot detection of EGF-CFC proteins in cell lysates using
-FLAG antibody (FLAG-Cryptic,
22 and
20 kDa; FLAG-Cripto,
21 and
19 kDa; FLAG-Oep,
21 kDa). (D) Lefty1 inhibits
Gdf3 activity. Cells were co-transfected with expression constructs for Nodal
or bf-Gdf3, Cripto and Foxh1, in the presence or absence of Lefty1; controls
correspond to these cells without Nodal or bf-Gdf3 transfection. (Inset)
Western blot detection of mature Lefty1 protein (
30 kDa) in conditioned
media. In all panels, assays were performed in triplicate; error bars
represent s.d.