Abstract
Purpose :
The vascular endothelial growth factor (VEGF) receptor VEGFR1 has been previously shown to be cleaved during corneal angiogenesis. In this study, we investigated whether the metalloproteinase (MMP) MMP14 might be a potential agent for cleavage of VEGFR1 in the cornea, and we explored a possible mechanistic purpose for VEGFR1 during angiogenesis.
Methods :
Recombinant mouse (rm) VEGFR1 was incubated with various concentrations of recombinant MMP14 to examine proteolysis in vitro. The reaction mixture was analyzed by SDS-PAGE and stained with Coomassie blue. The fragments resulting from rmVEGFR1 cleavage by MMP14 were subjected to Edman degradation, and the amino acid sequences were aligned with rmVEGFR1 sequences. Surface plasmon resonance was used to determine the equilibrium dissociation constant (KD) between MMP14 and rmVEGFR1. The KD value of rmVEGFR1 and the 59.8-kDa cleavage product binding to VEGF-A165 were also determined. Cell proliferation assays were performed in the presence of VEGF-A165 plus the 59.8-kDa VEGFR1 fragment or VEGF-A165 alone.
Results :
MMP14 binds and cleaves rmVEGFR1 to produce 59.8-kDa (N-terminal fragment, Ig domains 1-5), 35-kDa (C-terminal fragment containing, IgG and His-tag), and 21-kDa (Ig domains 6-7) fragments. The 59.8-kDa fragment showed binding to VEGF-A165 and inhibited VEGF-induced endothelial cell mitogenesis.
Conclusions :
Our findings suggest that VEGFR1 cleavage by MMP14 in the cornea leads to a VEGF-trap effect, reducing the pro-angiogenic effect of VEGF-A165, there by reducing corneal angiogenesis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.