Expression and Tissue Distribution of P63–Isoforms on Ocular Surface Epithelia

Abstract

Abstract: : Purpose: The functional significance of p63 in maintaining cell proliferative capacity especially in the stem cells of various epithelial tissues has previously been established. Although functional differences are still unknown, more than six isoforms have been reported for this protein. We studied the expression and the spatial distribution of the 6 p63–isoforms within human ocular surface epithelia. Methods: Individual layers (basal, intermediate, superficial) of human ocular surface epithelia (cornea, limbus, conjunctiva) were separately obtained using a laser micro–dissection device. These samples were equally amplified using a SMART^TM PCR cDNA Synthesis Kit and subjected to RT–PCR analysis with primer pairs, which specifically recognize five isoform–determining regions and the six p63–isoforms. Results: ΔNp63α was detected in the basal to intermediate layers of limbus and conjunctiva. The other 5 isoforms were not detected in any layers of any epithelia. Conclusions: These results suggest that ΔNp63α is the most dominant isoform in the human ocular surface epithelia. This protein may contribute, at least in part, to the maintenance of putative stem cells and early progenitor cells in limbal or conjunctival epithelium possibly via its dominant negative effect on p53–dependent apoptosis.

Keywords: cornea: epithelium • conjunctiva