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. Author manuscript; available in PMC: 2015 Feb 24.
Published in final edited form as: Dev Cell. 2014 Feb 13;28(4):423–437. doi: 10.1016/j.devcel.2014.01.006

Figure 1. PGE2 affects Embryonic Liver Outgrowth.

Figure 1

(A) In situ hybridization for transferrin, a liver-specific marker, reveals that embryonic liver size is regulated by PGE2. Exposure to dmPGE2 from 48-80 hpf dramatically increases embryonic liver size (51.4% embryos with an enlarged liver, n = 18 / 35) whereas exposure to Indomethacin (Indo) decreases embryonic liver size (76.5% embryos with a smaller liver, n = 26 / 34). Left lateral view, row below is magnified view.

(B) FACS quantification of GFP+ liver cells in lfabp:GFP embryos at 72 hpf following exposure to dmPGE2 or Indo. dmPGE2 increases the relative number of liver cells, whereas Indo decreases the relative number of liver cells. (Data are represented as mean ± SEM; ***significant across treatment groups, ANOVA, p=0.0009).

(C) Confocal microscopy visualization of the liver in lfabp:GFP embryos at 72 hpf following exposure to dmPGE2 or Indo. Exposure to dmPGE2 from 48-72 hpf enlarges the developing liver, whereas exposure to Indo severely abrogates liver development. Left lateral view. (Data are represented as mean ± SEM; n = 5 / treatment).

(D) Analysis of liver [volume] × [mean fluorescence intensity] visualized by confocal microscopy, corroborating the effect of dmPGE2 to increase embryonic liver size and Indo to diminish embryonic liver size. (Data are represented as mean ± SEM; n = 5 / treatment, ****significant across treatment groups, ANOVA, p<0.0001).

(E) Histological analysis reveals that modulation of PGE2 levels changes embryonic liver size, but does not alter liver morphology (n = 5 / treatment). TUNEL analysis shows no apoptosis following modulation of PGE2 activity (n = 5 / treatment). Scale bar = 100 μm.

(F-I) Morpholino-mediated knockdown of PGE2 synthetic enzymes (F,G) or PGE2 receptors ep2a and ep4a (H,I) alters liver development, as visualized by fluorescence in lfabp:GFP embryos. Left lateral view. Impact on liver size is quantified by [area] × [fluorescence intensity] in lfabp:GFP embryos as shown in (Figure 1G,I). (Data are represented as mean ± SEM; n ≥ 30 / condition; significant by t-test comparing each morpholino vs. control and each morpholino without vs. with dmPGE2, **** p<0.0001, * p<0.05, *** p<0.001, n.s. = not significant).

See also Figure S1.