Abstract
Purpose: :
Wnt proteins are signalling molecules that play a role in stem cell communication, corneal epithelial cell proliferation, epithelial-mesenchymal transition and ocular development. Nuclear beta-catenin is a product of Wnt signalling. Wnt4 has been found in human limbus. This study sought to confirm the presence of Wnt4 and investigate whether Wnt3, Wnt5a and beta-catenin are present in the normal adult limbus and cultured limbal epithelial cells.
Methods: :
Normal human adult corneolimbal rims (n=15) were obtained. Immunohistochemistry was performed on formalin fixed, paraffin embedded tissue using the Bond-XTM automated immunostainer and Polymer Refine Detection System (Vision BioSystems). Sections were incubated with Wnt3, Wnt4, Wnt5a and beta-catenin antibodies and diaminobenzidine was used as the chromogen. Primers for Wnt3, Wnt4, and Wnt5a were obtained from Sigma - Aldrich. RT-PCR was performed on serial passages of human adult limbal epithelial cells (HLEC) with standard reagents. Slow-cycling (pulsed bromodeoxyuridine label-retaining) limbal epithelium in corneal organ culture was studied for the expression of Wnt3, Wnt4, Wnt5a and beta-catenin.
Results: :
Positive immunostaining of the cytoplasm and nucleus were observed for Wnt4 in all layers of the limbal epithelium. Beta-catenin was present in the cell membranes in all layers of the corneal limbus as well as in the central corneal epithelium. Nuclear beta-catenin and Wnt5a staining were confined to a small population of cells in the basal limbus. Wnt3, Wnt4 and Wnt5a were expressed in serial passages of HLEC. Wnt4 and β-catenin were co-localised to BrdU label-retaining cells.
Keywords: cornea: epithelium • cornea: basic science • cell-cell communication