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C.–C. Cheng, D.–Y. Wang, M.–H. Kao, J.–K. Chen; Expression of p63 Transcription Factor by Limbal Keratinocytes Indicates Low Differentiation and High Proliferative Potential . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2100.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Limbal epithelial stem cells (LSC) are the progenitors of corneal epithelium and p63 has been suggested to be the putative marker of the limbal epithelial stem cell. P63 protein consists of six isoforms belonging to either the transcriptional activation (TA) from or the delta N (ΔN) form. The possible roles of p63 protein isoforms in the regulation of corneal differentiation lineage and the maintenance of limbal epithelial stem cell remained to be explored. Methods: Real–time quantitative reverse transcription PCR (real–time Q–RT–PCR), immunofluorescent staining, p63 antisense oligo blockage, and confocal microscopy were employed to exam the expression patterns of p63, keratin 3 and keratin 14 in freshly prepared corneal and limbal tissues, and in limbal explants and epithelial outgrowth cultured on amniotic membrane (AM). Results: P63 positive cells are unevenly distributed in different quadrants of the limbus and it is positively correlated with the potential of the epithelial outgrowth when explanted on AM. Blockage of p63 expression with antisense oligos, especially the ΔNp63, effectively, suppresses epithelial outgrowth. Immunostaining shows that blockage of TAp63 with antisense oligo enhances Keratin 3 expression. Conclusions: Our results show that the abundance of p63–positive cells is positively correlated with the potential of the epithelial outgrowth of the limbal explant. In vitro study show that ΔNp63 expression by antisense indicates that ΔNp63 is important for the proliferation of limbal epithelial cells. In contrast, TAp63 seems important for limbal epithelial cells to stay in a less differentiated state as the blockade of its expression enhances Keratin 3 expression.
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