Abstract
Abstract: :
Purpose: To increase the database of genes expressed in human cornea and to gain insights into the molecular basis of keratoconus (KC). Methods: A cDNA library was constructed from KC corneas harvested at keratoplasty and used for expressed sequence tag (EST) analysis. Data were analyzed using GRIST. Expression of selected clones was examined by RT–PCR. Results: A total of 7680 clones were sequenced from the 5’ end. After bioinformatics analysis, 4090 clusters of clones, each potentially representing individual genes, were identified. Of these, 887 genes were represented by more than one clone. The five most abundant transcripts, represented by more than 60 clones each, were Keratin 12, TGFBI (BIGH3), decorin, ALDH3, and enolase 1, all known markers for cornea. Many other markers for epithelial, stromal and endothelial expressed genes were also present. One cluster of 6 clones came from an apparently novel gene (designated ‘KC6’) located on chromosome 18p12.3. RT–PCR of RNA from several human tissues detected ‘KC6’ transcripts only in cornea. In addition, no clones were observed for the usually prominent corneal epithelial cell marker aquaporin 5 (AQP5), a water channel protein. Semi–quantitative RT–PCR confirmed that expression of AQP5 is much lower in KC cornea than in non–KC cornea. Conclusions: This analysis increases the database of genes expressed in the human cornea and provides insights into KC. ‘KC6’ is a novel gene of unknown function that shows cornea–preferred expression while the suppression of transcripts for AQP5 provides the first clear evidence of molecular defect identified in KC.
Keywords: cornea: basic science • cornea: clinical science • keratoconus