Fig. 5

Hnf1ba is required for Wnt signaling activity in the foregut endoderm. (A-C) Double antibody (myosin; blue) and in situ hybridization staining (ventral view) of 24 hpf wild-type foregut endoderm for expression of hnf1ba (A), wnt2bb (B) and prox1 (C, arrowheads). (D) Illustration summarizing foregut expression domains showing restricted prox1 expression within the anterior region of the hnf1ba foregut expression domain and adjacent to the wnt2bb expression domain in the lateral plate mesoderm. Pronephric hnf1ba expression (red asterisks in A) and dorsal pancreas prox1 expression (dp) are not depicted in the illustration. (E-G) Three-dimensional rendering (lateral view) of 36 hpf foregut endoderm in wild-type (E), Tg(hsp70l:wnt8a-GFP)^w34 (F) and Tg(hsp70l:wnt8a-GFP)^w34; hnf1ba^s430/hi2169 (G) embryos heat-shocked from 21-28 hpf at 37°C and stained for Prox1 and myosin. Compared with wild type, heat-shocked Tg(hsp70l:wnt8a-GFP)^w34 embryos show significant posterior expansion of Prox1 in the foregut endoderm (yellow arrows; n=8/8). In Tg(hsp70l:wnt8a-GFP)^w34; hnf1ba^s430/hi2169 embryos, only weak or no Prox1 expression is observed (yellow arrows; n=6/6). (H-L) Double antibody and in situ hybridization staining (ventral view) of cmyc at 36 hpf in wild-type (H), Tg(hsp70l:wnt8a-GFP)^w34 (I), Tg(hsp70l:dkk1-GFP)^w32 (J), hnf1ba^s430-/- (K) and Tg(hsp70l:dkk1-GFP)^w32; hnf1ba^s430/hi216 (L) embryos heat-shocked from 21 to 28 hpf. cmyc expression is restricted in the wild-type foregut endoderm (white arrowhead in H) but is expanded posteriorly in Tg(hsp70l:wnt8a-GFP)^w34 (yellow arrows in I; n=12/12) or severely reduced in Tg(hsp70l:dkk1-GFP)^w32 (white arrowhead in J) embryos. cmyc expression is reduced or lost in the hnf1ba^s430 foregut endoderm (white arrowhead in K; n=4/4), and only weakly induced in Tg(hsp70l:wnt8a-GFP)^w34; hnf1ba^s430/hi2169 embryos (yellow arrow in L; n=4/4).