Over-expression of Fih-1 inhibits the formation of angiogenic vessels during development.

(A) Whole-mount in situ hybridization with fli1a and kdrl in control or fih-1 mRNA-injected embryos. In fih-1 mRNA-injected embryos, the number of intersegmental vessels (black arrowheads) was substantially reduced. (B) Microangiography of fih-1 mRNA-injected embryos shows a lack of circulation in intersegmental vessels. (C) Ectopic expression of vegf-aa165 restored impaired angiogenic vessel formation in fih-1 mRNA-injected embryos at 52 hpf. Arrowheads point to intersegmental vessels which fail to anastomose at the dorsal-most part of the embryos. (D) Schematic diagram of two constructs that encode either N-terminus or C-terminus deleted Fih-1. Both N-terminus only Fih-1 (Fih-1ΔC) and C-terminus only Fih-1 (Fih-1ΔN) contain JmjC domain and metal binding sites which are essential for hydroxylation of HIF-1α. (E) C-terminus of Fih-1 is essential for its anti-angiogenic activity. While full length fih-1 or fih-1ΔN mRNA-injected embryos inhibit angiogenic sprouts of intersegmental vessels, fih-1ΔC mRNA-injected embryos at 72 hpf do not show any obvious vascular defects. Arrowheads point to angiogenic sprouts which fail to extend to the dorsal-most side of the embryos.