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R. Lu, F. Bian, L. Zhang, S. Pflugfelder, D.-Q. Li; TCF4 Serves as a Potential Marker for Human Limbal Epithelial Progenitor Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2955.
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© ARVO (1962-2015); The Authors (2016-present)
TCF4, a key transcription factor in Wnt signaling pathway, has been recently found to function for maintaining stemness in skin epithelial stem cells. This study was to explore the functional role of TCF4 serving as a potential marker for corneal limbal epithelial progenitor cells.
Fresh corneal limbal tissues were used to make cryosections, isolate limbal epithelial cells and generate primary cultures. Limbal epithelial progenitor cells isolated from fresh tissues by adhesion on collagen IV were used for Affymetrix GeneChip® human genome U133 Plus 2.0 microarrays. Gene expression was further validated by reverse transcription and real time PCR with TaqMan primers and probes, as well as immunofluorescent staining. The expression and functional role of TCF4 and associated genes were further evaluated in cultured limbal epithelial cells at different growth stages,and in wound healing conditions.
Human genome microarrays revealed that TCF4 transcripts were highly expressed by limbal progenitor cells, the rapid adherent cells (RAC) isolated from adhesion to collagen IV. TCF4 mRNA was confirmed to be highly expressed by RAC and by limbal epithelium. TCF4 protein was found to be immunolocalized in the basal cells of limbal epithelium where corneal epithelial stem cells locate. The immunoreactivity of β-catenin at cell membrane and cytoplasm was also stronger in basal than suprabasal layers of limbal epithelium. TCF4 was expressed higher in younger epithelial cells than in differentiated cells by analysis of different growth stages of limbal epithelial cultures. The expression pattern of TCF4 was well correlated with limbal stem cell associated markers, ABCG2, p63 and integrin β1. In an in vitro wound healing model of limbal epithelial cultures, TCF4 expression significantly increased in 6-24 hours after wounding, accompanied by nuclear translocation of β-catenin immunoreactivity and upregulated expression of proliferation associated markers including p63, EGF receptor, growth arrest-specific 1 (GAS1), tissue factor pathway inhibitor (TFPI) and transgelin.
These findings demonstrate that transcription factor TCF4 was mainly expressed and immunolocated in the basal layer of limbal epithelium. TCF4 plays an important role in maintaining the undifferentiated status and proliferative capacity of limbal stem cell. TCF4 may serve as a novel molecular marker for limbal epithelial progenitor cells.
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