Figure 8

chch suppresses the transcriptional response to Nodal signaling. Embryos were microinjected with either 250 pg chch-EnR mRNA, 0.5 pg sqt mRNA, 2.5 pg sqt mRNA, or co-injected with 250 pg chch-EnR mRNA and 0.5 pg or 2.5 pg sqt mRNA and were analyzed at shield stage by real-time PCR with the dorsal markers gsc (A), chd (B), and flh (C), the endodermal marker mixer (D) and the pan-mesodermal marker ntl (E). All of these markers show little change in gene expression in embryos injected with chch-EnR mRNA and a dose dependent response to sqt mRNA. When both chch-EnR and sqt mRNA were co-injected, synergistic increases in marker expression were observed. These results demonstrate that chch suppresses the response to Nodal signaling. Conversely, microinjection of chch-VP-16 mRNA suppresses the transcriptional response to Nodal signaling. Embryos were microinjected with 2.5 pg sqt, 500 pg chch mRNA, 500 pg chch-VP16 mRNA, or co-injected with sqt and chch mRNA or chch-VP16 mRNA. Embryos were collected at shield stage and analyzed by real-time PCR with gsc (F), chd (G), flh (H), mixer (I), and ntl (J). Co-injection of chch-VP16 mRNA along with sqt mRNA supresses the transcriptional response to sqt.