Study of corneal epithelial progenitor origin and the Yap1 requirement using keratin 12 lineage tracing transgenic mice.

Ramesh Babu Kasetti,Qiutang Li,Winston W-Y Kao,Subhash Gaddipati,Shifu Tian,Qingxian Lu,Lei Xue

doi:10.1038/srep35202

Ramesh Babu Kasetti, Qiutang Li + Show 5 more

Open Access

https://doi.org/10.1038/srep35202

Copy DOI

Abstract

Key issues in corneal epithelium biology are the mechanism for corneal epithelium stem cells to maintain the corneal epithelial homeostasis and wound healing responses, and what are the regulatory molecular pathways involved. There are apparent discrepancies about the locations of the progenitor populations responsible for corneal epithelial self-renewal. We have developed a genetic mouse model to trace the corneal epithelial progenitor lineages during adult corneal epithelial homeostasis and wound healing response. Our data revealed that the early corneal epithelial progenitor cells expressing keratin-12 originated from limbus, and gave rise to the transit amplifying cells that migrated centripetally to differentiate into corneal epithelial cells. Our results support a model that both corneal epithelial homeostasis and wound healing are mainly maintained by the activated limbal stem cells originating form limbus, but not from the corneal basal epithelial layer. In the present study, we further demonstrated the nuclear expression of transcriptional coactivator YAP1 in the limbal and corneal basal epithelial cells and its essential role for maintaining the high proliferative potential of those corneal epithelial progenitor cells in vivo.

Highlights

Key issues in corneal epithelium biology are the mechanism for corneal epithelium stem cells to maintain the corneal epithelial homeostasis and wound healing responses, and what are the regulatory molecular pathways involved
Corneal epithelium serves as the surface barrier for the eye, which is constantly renewed with complete turnover for every 6–7 days[1,2]
We showed that the limbal Krt12+- progenitor cells labeled by Dox-induced GFP survived up to 4 months; and when activated, could give rise to GFP-positive transit amplifying cell (TAC) that migrated centripetally to differentiate into corneal epithelial cells, and produced actinomorphic GFP tracking strips

Summary

Introduction

Key issues in corneal epithelium biology are the mechanism for corneal epithelium stem cells to maintain the corneal epithelial homeostasis and wound healing responses, and what are the regulatory molecular pathways involved. Our results support a model that both corneal epithelial homeostasis and wound healing are mainly maintained by the activated limbal stem cells originating form limbus, but not from the corneal basal epithelial layer. They usually lack specific corneal differentiation markers, such as keratin-3 (Krt3) and keratin-12 (Krt12), and proliferate slowly[3,4,5] Some of these limbal stem cells can divide asymmetrically to produce two different types of cells with one as a new generation of stem cell to maintain a constant stem cell population, and the other as a differentiating transit amplifying cell (TAC) that proliferates and migrates centripetally to populate the basal layer of the corneal epithelium[6,7]. While YAP has been implicated in maintenance of progenitor cell identity and proliferation, the precise role it plays in regulation of the corneal epithelial progenitor cell has not been characterized

Methods

Results

Conclusion