Abstract
Purpose: :
. Nucleostemin (Gnl3) is a candidate marker for stem cells. It is expressed in the nucleolus of various stem cells such as embryonic stem cells, neural stem cells and also in cancer stem cells, but not in most differentiated cells. Gnl3 is thought to be involved in regulation of cell cycle and proliferation. To investigate the possible use of Gnl3 as a marker for corneal stem cells, we examined the expression patterns of Gnl3 in human and mouse cornea.
Methods: :
Expression of Gnl3 in normal human and mouse corneal epithelium was examined by RT-PCR and immunohistochemistry. The expression in wounded mouse corneal epithelium and in cultured human corneal epithelial cells was also examined. Co-expression of Gnl3 with the stem cell markers p63, K15 and K19, and with the proliferation marker Ki67 was also examined by immunohistochemistry.
Results: :
Gnl3 expression was detected in both human and mouse corneal epithelium by RT-PCR. Immunohistochemistry revealed that Gnl3 was expressed predominantly in basal cells of the limbal area through the conjunctiva. In addition, Gnl3 was also expressed in suprabasal cells, including the central area of corneal epithelium, although the level was not as high. Furthermore, expression was found in keratocytes and endothelial cells, which are thought to be quiescent. The expression of Gnl3 was not associated with the expression of K15, K19, or Ki67 but overlapped with the expression of p63. Wound repair-associated upregulation of Gnl3 was also observed.
Keywords: cornea: epithelium • gene/expression • immunohistochemistry