Fig. 4

Fih-1 negatively regulates Vegf-aa₁₆₅ in zebrafish embryos.

(A) At 28 hpf, both fih-1 and vegf-aa₁₆₅ transcript are selectively expressed within the anterior somites and ventral mesoderm. (B) Attenuation of Fih-1 activity in zebrafish elevates the level of vegf-aa₁₆₅ expression at 50 hpf. Arrowheads point to vegf-aa₁₆₅ expression in somites caused by lack of Fih-1 activity. Similarly, the level of vegfaa transcript in 48 hpf control or fih-1 MO-injected embryos was evaluated by quantitative RT-PCR. Error bars are standard deviation (right). (C) Ectopic expression of Fih-1 decreases the level of vegf-aa₁₆₅ expression in a dose-dependent manner at 28 hpf. (D) Functional relationship between Fih-1 and Vegf-aa₁₆₅. Ectopic expression of Vegf-aa₁₆₅ under the regulation of hsp70l promoter caused a similar vascular phenotype as observed in fih-1 MO-injected embryos. Moreover, inhibition of Vegf-A signaling can drastically reduce the exuberant angiogenic sprouts in fih-1 MO-injected embryos at 80 hpf. Arrows point to ectopic sprouts.