Fig. 4. Inhibition of WNT signalling requires the CT domain of CTGF. (A) Domain
structures of CTGF and CTGF
CT. (B-D) CTGFCT cannot inhibit
induction of secondary axes by Xwnt8. (B) Secondary axis induced by Xwnt8. (C)
Inhibition of secondary axis formation by CTGF. (D) CTGFCT cannot
inhibit secondary axis formation. (E) CTGFCT is a poor inhibitor of
Xwnt8-induced activation of the TOPFLASH reporter; CTGF cannot inhibit
activation of the TOPFLASH reporter by Dishevelled. Both blastomeres of
Xenopus embryos at the 2-cell stage received injections of 20 pg
TOPFLASH DNA, 10 pg pRLTK DNA and the indicated combinations of 1 ng CTGF RNA,
1 ng CTGFCT RNA, 50 pg Xwnt8 RNA and 1 ng Dishevelled RNA. Animal caps
were dissected at stage 8, and 20 caps per sample were assayed for Firefly and
Renilla luciferase activities 3 hours later. Firefly luciferase activities
were then normalised to Renilla activities. This experiment represents a
typical result out of three independent experiments. (F-H) CTGFCT
cannot inhibit activin-induced elongation of Xenopus animal caps. (F)
Animal caps treated with 8 units/ml of activin protein undergo elongation. (G)
Animal caps derived from embryos injected with 1 ng Ctgf RNA do not
undergo elongation. (H) Elongation of animal caps is not inhibited by 1 ng of
CtgfCT RNA.