An expression profile of active genes in human conjunctival epithelium

The purpose of this study was to describe the quantitatively and qualitatively genes expressed in in vivo human conjunctival epithelium. A cDNA library was created from human conjunctival epithelial cells obtained from 38 normal eyes by brush cytology. Poly A(+)RNA isolated from these cells was used as a template for cDNA synthesis by the vector-priming method. A 3'-directed cDNA library consisting of the cDNA moiety covering the poly A(+)RNA tail through the nearest Mbo I site was constructed and transformed into Escherichia coli. Inserts in 933 randomly chosen clones were sequenced. The resulting sequences were compared to determine frequency of appearance in the library, and to establish an expression profile of genes in the conjunctival epithelium. The sequences were sent to GenBank for gene identification. The result was an expression profile of active genes reflecting their relative abundance in the conjunctival epithelial mRNA population. The expression profile of human conjunctival epithelium showed that the most abundant gene transcript in human conjunctival epithelium was that for cytokeratin 13. Altogether 102 genes were found to be very active, including beta-2 microglobulin, lipocortin I and insulin-like growth factor binding protein-3. The gene expression profile of the conjunctival epithelium reflects the unique properties and functions of this tissue. Comparison of this expression profile with that obtained from corneal epithelium discloses clear differences and helps us better understand the physiology and pathophysiology of the ocular surface in humans.