Figure 6.

TRAF4 is a positive regulator of BMP signaling. (A) TRAF4 enhances mesoderm induction by BMP4 in stage 10.5 animal caps. TRAF4 suppresses neural and cement gland induction (B) by a truncated, dominant-negative BMP receptor (tBR) and (C) by Noggin in stage 17 animal caps. (D) On the top is the alignment of 5′UTR regions of TRAF4a and TRAF4b immediately upstream of ATG start codon (red letters). Antisense morpholino oligo (MO) target sequences for TRAF4a (MOa) and TRAF4b (MOb) are indicated by a blue or pink underline, respectively. A western blot on the bottom shows translation of injected TRAF4a mRNA is blocked by MOa but not by MOb. Unspecific bands serve as loading control. (E) Treatment of animal caps with TRAF4 MOa promotes neural induction by a subthreshold dose of Chordin in stage 17 animal caps. In each graph, the y-axis shows the relative expression level of each gene in animal caps expressed as percentage of expression of the same gene in a stage-matched whole embryo. These expression levels are also normalized to an internal control “housekeeping” gene expressed in all cells, ornithine decarboxylase. Results are representative of two to six independent experiments.