Abstract
Objective: We evaluated the gene expression profile of the rabbit corneal endothelium to isolate candidate genes for corneal dystrophies.
Materials and methods: We performed a random sequence and homology search analysis of 1,000 clones from the rabbit corneal endothelial cDNA library in the previous study. Forty-five genes, including six unknown genes, were listed as frequently observed cDNAs in the library. We re-analyzed these cDNAs by a similarity search of the latest database, including the human genome sequence. The newly identified genes were selected for further characterization.
Results: Two cDNA sequences (C82954 and C83005) showed significant similarity to the newly identified human genes. 1. C82954 showed significant similarity to the human esophageal cancer related gene 4 protein (ECRG4), which was mapped to human chromosome 2. A rabbit cDNA clone, containing a 444 bp open reading frame, was isolated using the 5'rapid amplification of cDNA ends (5'RACE) method. We presumed that the cDNA is a rabbit homologue of ECRG4. The expression of ECRG4 was observed in all the tissues examined using RT-PCR. 2. The human homologue of C83005 was similar to part of the mouse polydomain protein gene (polydom), which was mapped to human chromosome 9. RT-PCR study indicated that the expression of this gene was detected in the corneal endothelium, conjunctiva, tunica mucosa oris, intestine, lung, spleen, and esophagus. In situ hybridization using C83005 as a probe showed the specific labeling of endothelial cells in the cornea and lymphocytes in the spleen.
Conclusions: ECRG4 and polydom are possible genes which are highly expressed in the corneal endothelium.
