Forkhead box transcription factor FoxC1 preserves corneal transparency by regulating vascular growth

S Seo, HP Singh, PM Lacal… - Proceedings of the …, 2012 - National Acad Sciences
S Seo, HP Singh, PM Lacal, A Sasman, A Fatima, T Liu, KM Schultz, DW Losordo
Proceedings of the National Academy of Sciences, 2012National Acad Sciences
Normal vision requires the precise control of vascular growth to maintain corneal
transparency. Here we provide evidence for a unique mechanism by which the Forkhead
box transcription factor FoxC1 regulates corneal vascular development. Murine Foxc1 is
essential for development of the ocular anterior segment, and in humans, mutations have
been identified in Axenfeld–Rieger syndrome, a disorder characterized by anterior segment
dysgenesis. We show that FOXC1 mutations also lead to corneal angiogenesis, and that …
Normal vision requires the precise control of vascular growth to maintain corneal transparency. Here we provide evidence for a unique mechanism by which the Forkhead box transcription factor FoxC1 regulates corneal vascular development. Murine Foxc1 is essential for development of the ocular anterior segment, and in humans, mutations have been identified in Axenfeld–Rieger syndrome, a disorder characterized by anterior segment dysgenesis. We show that FOXC1 mutations also lead to corneal angiogenesis, and that mice homozygous for either a global (Foxc1−/−) or neural crest (NC)-specific (NC-Foxc1−/−) null mutation display excessive growth of corneal blood and lymphatic vessels. This is associated with disorganization of the extracellular matrix and increased expression of multiple matrix metalloproteinases. Heterozygous mutants (Foxc1+/− and NC-Foxc1+/−) exhibit milder phenotypes, such as disrupted limbal vasculature. Moreover, environmental exposure to corneal injury significantly increases growth of both blood and lymphatic vessels in both Foxc1+/− and NC-Foxc1+/− mice compared with controls. Notably, this amplification of the angiogenic response is abolished by inhibition of VEGF receptor 2. Collectively, these findings identify a role for FoxC1 in inhibiting corneal angiogenesis, thereby maintaining corneal transparency by regulating VEGF signaling.
National Acad Sciences