Identification of a novel TCF4 isoform in the human corneal endothelium

Purpose: Alternative splice isoforms of TCF4, a gene implicated in Fuchs corneal dystrophy, have been identified in multiple human tissues outside of the eye. The aim of this study was to identify the transcriptional profile of TCF4 in the corneal endothelium. Methods: We extracted RNA from the donor corneal endothelium and performed rapid amplification of cDNA ends. We tested the expression pattern of 1 newly identified isoform (7b) in a panel of cDNA derived from multiple human tissues and included cDNA from corneal endothelial (CE) and retinal pigment epithelial cell lines. To further delineate differential expression of TCF4 splice variants that span CTG18.1, we analyzed expression of 6 alternative splice isoforms that are transcribed from either exon 2 or 3 in RNA extracted from the corneal endothelium of 3 normal donors and a CE cell line. Results: We identified 11 different isoforms in control CE tissue, including 1 isoform (7b) not reported previously. This isoform is enriched specifically in the corneal endothelium and placenta compared with other tissues in a panel of human cDNA. Conclusions: We demonstrate the complex expression profile of TCF4 in the human corneal endothelium and reveal expression of alternative splice variants of TCF4.