Abstract
Purpose :
To investigate the expression of Notch signaling pathway in ocular surface epithelial cells, and to determine the effect of Notch signaling pathway on the proliferation and differentiation of the ocular surface epithelial cells.
Methods :
Normal human limbal tissues were collected and embedded in OCT for cryosection. Limbal epithelial cells were clonal cultured in SHEM with 3T3 feeder layers. TKE2 cells were cultured in KSFM or with additional calcium or 10% FBS. Morphological change of TKE2 cells was observed and photographed. The expression of proliferation markers and Notch related factors in TKE2 cells, human limbal tissue and epithelial colonies were performed by immunohistochemistry, fluorescence and Western blot.
Results :
Notch receptors Notch1, Notch2, and Notch4, but not Notch3 were expressed in human limbal and corneal epithelium, as well as limbal epithelial colonies. Notch ligands such as Jagged1 and Jagged2 were expressed in limbal corneal epithelium. The down stream gene of Notch signal Hes1 were expressed in central corneal epithelium, and co-localized with stem cell marker p63 in corneal epithelial colonies. TKE2 cells cultured in KSFM showed strong expression of p63, PCNA, Ki67, K14, and K16. Notch1 and Hes1 were expressed in the nuclei, while Notch2 and Hey1 were expressed in the cytoplasm and nuclei of TKE2 cells in KSFM medium. However, the expression of p63, Notch1,Notch2, Jagged1,Jagged2 and Hes1 were significantly reduced, while Math1, as the Hes1 inhibitor was highly increased in TKE2 cultured in high calcium or serum containing medium.
Conclusions :
Notch signaling pathway is activated in human limbal epithelial tissues, human limbal epithelial clones and TKE2 cell line with high proliferative capacity, but not in TKE2 cell lines in differentiated state. Notch signaling pathway may play an important role in maintaining proliferative potential and phenotype of limbal stem cells.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.