Abstract
Purpose::
Some lines of studies suggest the possible roles of matricellular protein tenascin-C (TNC) for maintaining the homeostasis of stem cells. The expression of TNC is tightly controlled in adult tissues, and it accumulates beneath the limbal basal cells in adult cornea. To investigate the possible roles of TNC for corneal epithelial stem cell homeostasis, we examined the effect of TNC for the expression of the stem cell-related molecule beta-catenin.
Methods::
Human corneal epithelial cells were grown on TNC-, BSA- or fibronectin (FN)- coated dishes. Immunocytochemical analysis was carried out for beta-catenin and ki-67 antigen expression after 4hrs- to 24hrs-culture on the dishes. To quantify beta-catenin expression, western blot analysis was conducted. In addition, human limbal tissues were immunostained with beta-catenin and TNC antibodies.
Results::
Increased cytoplasmic beta-catenin staining was observed for corneal epithelial cells grown on the TNC substrate compared to FN- or BSA- coated dishes. Cadherin associated-peripheral beta-catenin staining was observed for corneal epithelial cells grown on the FN substrate. The number of ki-67 antigen positive cells on FN substrate was significantly higher than that on TNC substrate. Western blot analysis showed that beta-catenin expression was increased in the corneal epithelial cell lysate of TN- coated dishes. Positive beta-catenin immnostaining was observed in the cytoplasm at basal and supra-basal limbal epithelial cells, and it was confined to the cell periphery of superficial corneal cells.
Conclusions::
The corneal epithelial cells grown on TNC substrate showed higher level of non-cadherin-associated beta-catenin and reduced rate of cell proliferation compared to those on FN substrate. The TNC molecule may contribute to the formation of corneal epithelial stem cell niche through controlling beta-catenin signals.
Keywords: cornea: epithelium • extracellular matrix • cornea: basic science