Abstract
Purpose: :
Keratin 12 is one of the most specifically expressed genes in corneal epithelial cells. Although several efforts have been made for the indication of the mechanism by which keratin 12 gene is specifically expressed in corneal epithelial cells, the exact mechanism is still in question. In this study, we investigated the epigenetic regulation of the keratin 12 gene and attempted to identify the cis-regulatory region of that gene in a rabbit model.
Methods: :
For the investigation of epigenetic regulation, we performed bisulfite sequencing analysis for epithelial cells of rabbit cornea, conjunctiva, skin epidermis, and oral mucosa. For the identification of cis-regulatory elements of the rabbit keratin 12 gene, we performed a reporter gene assay using a primary culture of rabbit corneal epithelial cells. Subcultured rabbit iris stromal cells and corneal epithelial cells were also used as keratin 12 negative cells.
Results: :
Compared to other types of epithelia, the degree of methylation in the CpG dinucleotides residing around the keratin 12 gene was significantly low in the rabbit corneal epithelial cells compared to other keratin 12-negative epithelial cell types. The reporter gene assay indicated that the transcription-activating region may be located between -350 ~ 0 bps upstream of the translation initiation site of the rabbit keratin 12 gene. This region was included by the differentially methylated region which was identified by the bisulfate sequencing analysis and also has quite high similarity to the promoter sequence of the human keratin 12 gene, which was also found to be differentially methylated.
Conclusions: :
The cis-regulatory region identified in this study may be involved in the tissue-specific expression of the keratin 12 gene maybe via the regulation by the putative cornea-specific transcription factors as well as the epigenetic status.
Keywords: cornea: epithelium • transcription