Tissue Transglutaminase Promotes Cell Adhesion and Collagen Gel Contraction Induced by Keratocytes

Abstract

Abstract: : Purpose: Cell–surface tissue transglutaminase (tTG) affects cell–matrix interactions in cell adhesion, migration and extracellular matrix reorganization. However, the influence of tTG on keratocytes has not been well understood yet. In this study, to understand the role of tTG in corneal stromal wound healing, we investigated the effect of tTG on cell adhesion and collagen gel contraction by keratocytes. Methods: Human keratocytes were seeded on fibronectin–coated or BSA–coated plates, and were incubated with tTG (0.01–0.1U/ml) with or without RGD or RGE peptide(200–400µM) for 90 minutes. The number of attached cells was subsequently measured by MTT assay. In other experiments, keratocytes in collagen gels were cultured with serum–free MEM medium containing tTG (0.1–0.3U/ml) with or without anti–tTG antibody(10µg/ml ), fibronectin(10µg/ml), TGF–ß(0.1ng/ml) and PDGF(10ng/ml) for 5 days. The gel diameters were then measured. Results: tTG enhanced cell adhesion of keratocytes in a dose–dependent manner. The tTG–induced cell adhesion was inhibited not by RGE peptide but by RGD peptide on both BSA–coated and fibronectin–coated plates. On the other hand, tTG stimulated collagen gel contraction by keratocytes in a dose–dependent manner as well. The stimulative effect on collagen gel contraction was antagonized by anti–tTG antibody. Moreover, fibronectin, TGF–ß and PDGF also contributed to the stimulation to collagen gel contraction by keratocytes. tTG also enhanced these stimulative effects on collagen gel contraction. Conclusions: These findings suggest that tTG promotes both the RGD–dependent cell adhesion and collagen gel contraction by keratocytes.

Keywords: cornea: stroma and keratocytes • cell adhesions/cell junctions • extracellular matrix