Abstract
Purpose: :
To examine the expression of Notch ligands and receptors in the adult human corneal and limbal epithelium. Notch signaling is a highly conserved cell to cell signaling system that is crucial in cell fate determination during develoopment. It also appears to play a role in differentiation and proliferation in many adult tissues.
Methods: :
Corneal epithelial cells from the central and limbal areas were isolated from human donor corneas. RNA was extracted and semi–quantitative RT–PCR was performed to determine the relative expression of various Notch receptors, ligands, and modulators. Protein expression for selected ligands and receptors was evaluated by immunofluorescence.
Results: :
RT–PCR confirmed the expression of Notch1, Notch2, Delta1, Delta4, Jagged1, Jagged2, Numb, and Lunatic Fringe in the human corneal and limbal epithelium. The expression of Notch1, Jagged1 and Delta1 was higher in the limbal than in the corneal epithelium. Notch3, Notch4, Delta2, Manic Fringe, and Dlk1 were not expressed in the human corneal and limbal epithelium. Immunofluorescence revealed the expression of Notch1 throughout all layers of the corneal and limbal epithelium. Jagged1 was expressed in the basal, while Delta1 was expressed in the suprabasal cells most prominently in the limbal epithelium.
Conclusions: :
These results demonstrate the expression of the Notch receptors and ligands in the corneal and limbal epithelium. Further studies are underway to determine their precise functional role in corneal epithelial differentiation.
Keywords: cornea: epithelium • receptors • differentiation