EST Analysis of Human Pterygium cDNA Library

Abstract

Purpose: : Pterygia are lesions that grow across the corneal surface and are associated with sunlight exposure. In order to characterize pterygial tissue and compare it with other ocular surface tissue, we produced and analyzed a cDNA library, generating a profile of abundantly expressed transcripts.

Methods: : The cDNA library was prepared from RNA extracted from 9 pooled specimens of surgically removed pterygia. DNA sequence was obtained from 2298 randomly picked clones and analyzed using GRIST to group and identify sequence tags. Expression of selected genes was verified by Western blot analysis or immunohistochemical localization on cryosections of the ocular surface of post–mortem human eyes having pterygia.

Results: : There were 1856 unique clusters, representing single genes, found among the 2298 clones analyzed.The most abundant transcripts are for eukaryotic translation elongation factor 1 alpha 1, clusterin, keratin 13, Ig light chain, calgranulin B spermidine/spermine N1–acetyltransferase and keratin 4, each representing 0.4–1.0% of the total transcripts. Markers for both conjunctiva (such as keratin 13 and AQP3) and corneal epithelium (such as keratin 12 and AQP5) are present, with conjunctival markers predominating.

Conclusions: : We have generated a molecular portrait of pterygial tissue by compiling a profile of abundantly expressed genes in the cDNA library. The major class of tissue–specific markers are for conjunctiva, although corneal markers are also present. Several highly expressed genes, including spermidine/spermine N1–acetyltransferase, are associated with cell migration and so provide potential targets for intervention in pterygial growth and new insights into the pathophysiology of pterygium.

Keywords: Pterygium • anterior segment • gene/expression