Purpose: The tumor-suppressor gene p53 encodes a phosphoprotein involved in the control of cell growth. Its expression and function have been documented in malignancy, apoptosis, and other abnormal cell proliferation processes. Recently, expression of p53 has been demonstrated in certain normal tissues, including whole eye. The purpose of the study was to map and to characterize expression of p53 in the normal murine eye.
Methods: Eyes of adult C57BL/6 mice were enucleated after death by CO2 narcosis. Expression of p53 in frozen sections of whole cryoprotected eyes was mapped by indirect immunofluorescence microscopy using the anti-p53 monoclonal antibodies 248 and 421 and the polyclonal antibody FL-393. Additionally, eyes were freshly dissected to separate the various ocular tissues. In these ocular tissues, expression of p53 was quantitated with ELISA and Western blot analyses.
Results: Strong expression of p53 was observed in various normal ocular tissues. The corneal and conjunctival epithelium exhibited very high cytoplasmic p53 protein levels. High nuclear p53 protein staining was seen in the lens epithelial cells of the central and pre-equatorial zones and in the lens fiber nuclear bow, situated posterior to the epithelial germinative zone. Cells of the actual lens germinative zone did not stain for p53 protein. Low levels of p53 protein were expressed in retinal tissue.
Conclusions: High levels of p53 protein are found in various normal murine ocular tissues, especially the corneal and conjunctival structures and the lens epithelium. Each of these tissues demonstrate unique patterns of staining.