Identification of a new role of membrane‐type 1 matrix metalloproteinases in corneal neovascularization

Project Summary/Abstract Corneal neovascularization (NV) can be caused by severe corneal injury or infection and is a leading cause of blindness. Balance of pro-angiogenic factors and anti-angiogenic factors are important to maintain avascular corneal tissue. Pro-angiogenic factors such as VEGFA and FGF2 are highly induced in inflamed corneas and lead to activation of its receptor proteins such as VEGFR2 and FGFR2. Membrane-type 1 matrix metalloproteinase (MMP-14) is involved in remodeling of extracellular matrix (ECM) through its proteolytic activity. Recent studies have revealed that MMP-14 is a regulator of VEGFA/VEGFR2-mediated corneal NV via unique and selective cleavage of VEGFR1 which is a decoy receptor for VEGFR2. FGF2-induced corneal NV is delayed in MMP-14 knockout (KO) mice, indicating there is some correlation between FGF2 and MMP-14. However, how MMP-14 interacts with FGF2 is still largely unknown. The goal of this application is to characterize mechanism of MMP-14 on regulation of FGFR2 levels via ADAM-9 enzyme. We demonstrated that FGFR2 level was low in MMP-14 KO corneal fibroblast cells. On the other hand, ADAM-9, which is substrate of MMP-14, was higher in MMP-14 KO fibroblast than WT cells. We have also discovered that expression of MMP-8, MMP-9, and ADAM-17, all of which are underlying FGF2/FGFR2-system, were highly induced in WT than MMP-14 KO cells upon stimulation of FGF2. Thus, inhibition of MMP-14 can reduce FGF2/FGFR2-mediated corneal NV and inflammation. Furthermore, our results show that FDA-approved small molecule drugs, clioquinol, chloroxine, and folic acid, all of which contain a quinoline scaffold, inhibit MMP-14 enzyme activity. We propose three specific aims: (1) Mechanism of two enzyme cascades, MMP-14 and ADAM-9, to regulate FGFR2 level and expression of FGF2/FGFR2-mediated MMPs; (2) investigate the effect of MMP-14 in FGF2/FGFR2-mediated corneal inflammation; (3) Characterize quinoline analogs as selective MMP-14 inhibitors. We will complete these aims using innovative techniques from molecular biology and biophysics in vitro and in vivo.