Abstract
Abstract: :
Purpose: Previous our work shows that MMPs were involved in the process of corneal development. The purpose of this study was to investigate the spatial expression patterns of MMPs and ECM as well as adhesion–related molecules during corneal development. Methods: Corneas were isolated from developing day 5, 7, 10, 14, 18 embryos, and 2 days and 2 months old chick. Immunohistochemistry was also performed to detect the localization of MMPs (stromelysin–1, collagenase–3, MT–MMP) and TIMP–2, adhesive proteins (CD44v6, N–cadherin, and ADAM10), and fibronectin as well as tenascin expression. Epithelial and stromal cells isolated from developing cornea were primary cultured, and MT–MMP and ADAM10 expressions were confirmed by western blot analysis and immunofluorescence staining. Results: Based on the important roles of CD44 for stromal cell migration, CD44v6 and its cleaved forms of CD44v6 were highly expressed in the early corneal development. Furthermore, its expression was strongly detected invading neural crest cells and neural crest–derived stromal cells as well as developing epithelium in early corneal development. However, its expression was dramatically decreased in stromal layer 14 days after corneal development, but strongly detected in maturating corneal epithelium. Both MT–MMP and ADAM10 cleave the ectodomain of CD44v6 at the leading edge of migrating cells, and facilitate cell migration and reorganization of the extracellular matrix. As expected, active form of MT3–MMP was strongly expressed in the all layer of developing cornea at day 7, 14, and 18. Stromelysin–1 expression pattern showed similar to MT3–MMP expression patterns. ADAM10 was expressed in the all layer of early developing cornea, but its expression was not detected in the epithelium at day 14 and 18. Furthermore, by in vitro culture, we found that 50–KDa of ADAM10 was secreted form and 82–KDa was cell surface bound form. Interestingly, tenascin and fibronectin as well as N–cadherin expression was distinctly expressed in the epithelium, stroma, and endothelium depends on the developing day of cornea. Conclusions: Our results suggest that temporally and spatially expressed ECM as well as CD44v6 and MMPs/TIMP, and MT3–MMP and ADAM10 may act function together to effect the migration of neural crest–derived mesenchymal cell into the stroma and the proliferation and differentiation of epithelium and endothelium as well as remodeling of cornea.
Keywords: cornea: basic science • cornea: stroma and keratocytes • cornea: epithelium