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

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