Abstract
Vascular endothelial growth factor receptor 3 (VEGFR3) regulates the growth and differentiation of blood and lymphatic vessels. To determine whether matrix metalloproteinase 14 (MMP14) modulates VEGFR3 expression in the corneal epithelium to influence the avascularity of the cornea, VEGFR3 expression was compared between wild-type and MMP14-deficient (MMP14 Δexon4) corneal epithelial cells. Western blot analysis showed that VEGFR3 protein expression was higher on MMP14 Δexon4 corneal epithelial cells than on wild-type cells, and quantitative RT-PCR analysis showed that VEGFR3 gene expression was highly induced in MMP14 Δexon4 corneal epithelial cells but not in wild-type corneal epithelial cells or wild-type and MMP14 Δexon4 corneal keratocytes. Unlike in epithelial cells, MMP14 Δexon4 keratocytes did not express relatively higher levels of VEGFR3 than wild-type keratocytes. Interestingly, in vitro proteolysis experiments showed that MMP14 does not cleave VEGFR3 in vitro as it does VEGFR1, indicating that other genes may be involved in the modulation of VEGFR3 expression by MMP14. Using proteomic analysis to identify candidate factors, we found that 39 nuclear proteins were differentially expressed between wildtype and MMP14 Δexon4 corneal epithelial cells. These findings suggest that MMP14 may regulate VEGFR3 expression at the transcriptional level on corneal epithelial cells but not on corneal keratocytes.
Keywords: MMP14, VEGFR3, corneal epithelial cell, angiogenesis, corneal keratocyte, lymphangiogenesis.