DESCRIPTION (provided by applicant):Our long-term goal is to understand the role of basonuclin in rRNA transcription in corneal keratinocytes. This knowledge will help the elucidation of the mechanisms that regulate the proliferation of cornea! epithelium. Several transcription factors have been shown to be involved in the regulation of rRNA transcription. These factors, however, are ubiquitous and cell-type specific regulators of rRNA synthesis are still poorly understood. Basonuclin, a zinc finger protein found in abundance in the keratinocytes of stratified epithelia and the germ cells of testis and ovary, is likely to be a cell type-specific, and proliferation-related transcriptional regulator for the rRNA genes, the first of its kind. Basonuclin was detected in the neonatal and adult corneal epithelium. Our hypothesis is that basonuclin is required for the normal development and maintenance of the mouse corneal epithelium. Basonuclin enhances rRNA transcription to fulfill the demand of protein synthesis in corneal keratinocytes during development and wound healing. The following three specific aims are proposed to test this hypothesis: Specific Aim 1, To investigate if basonuclin +/- ES cells can form corneal keratinocytes in ROSA mouse chimeras. Specific Aim 2, To examine the correlation between the cellular rRNA content and the presence of basonuclin in the cornea and other ocular tissues during eye development. Specific Aim 3, To interfere with the rRNA transcription in permeabilized corneal keratinocytes by dominant-negative reagents of basonuclin function.