Netrin-1 inhibits sprouting angiogenesis in developing avian embryos.

Area of Science:

• Developmental Biology
• Molecular Biology
• Vascular Biology

Background:

• Netrin-1 is a known axonal guidance cue acting as a bifunctional signaling molecule.
• Netrin-1's role in angiogenesis is suggested, potentially mediated by unknown receptors for attraction and UNC5B for repulsion.
• The evolutionary conservation of vascular UNC5B expression and function is not well understood.

Purpose of the Study:

• To investigate the evolutionary conservation of vascular UNC5B expression and function.
• To determine Netrin-1's pro- or anti-angiogenic activities in avian embryos.

Main Methods:

• Cloned the chick unc5b homologue.
• Examined unc5b expression in chick and quail embryos.
• Grafted cell lines expressing recombinant Netrin-1 into avian embryos to assess effects on angiogenesis.

Main Results:

• Chick and quail embryos exhibited unc5b expression in arterial endothelial cells and sprouting capillaries.
• Netrin-1 expressing cells inhibited angiogenic sprouting in blood vessels expressing UNC5B.
• Netrin-1 demonstrated no pro-angiogenic activity or effect on endothelial precursor cell recruitment.

Conclusions:

• Vascular UNC5B expression and function are conserved between avian and mouse species.
• Netrin-1 acts as an anti-angiogenic factor in avian embryos, mediated by UNC5B.
• Netrin-1 does not promote angiogenesis or endothelial precursor cell recruitment.