Purpose. The bcl-2 oncogene is one of the regulatory oncogenes for programmed cell death (apoptosis) and has been found to inhibit cellular death without affecting cellular proliferation. Expression of bcl-2 is limited to self-renewing tissues such as bone marrow and skin. In skin, bcl-2 expression is expressed only in the basal epidermis. In this study, we investigated the expression of bcl-2 in normal human ocular surface epithelia and its implications. Methods. Human ocular surface epithelia were obtained from cadaver eyes. To study the bcl-2 protein expression, immunohistochemistry was performed on frozen tissue sections with a monoclonal anti-bcl-2 antibody and biotin-avidin-immunoperoxidase. RT-PCR and Southern hybridization were performed to study the bcl-2 gene expression using primers (MBR 1 & 3) and a oligoprobe (MBR 2) specific for the normal allele of bcl-2 gene. Results. By immunohistochemistry, bcl-2 protein was expressed in the basal layers of conjunctival and limbal epithelia. Sporadic staining was also noted in the conjunctival goblet cells. In contrast, no evident bcl-2 was detected in coraeal basal epithelium. By RT-PCR, m-RNA of bcl-2 was detected in all three epithelia with a preferential expression in the conjunctival epithelium, a finding consistent with protein expression in these tissues. The specificity of PCR products of bcl-2 was confirmed by Southern blots. Conclusions. Preferential expression of bcl-2 in the basal layers of conjunctival and limbal epithelia implicates the self-renewing nature of these cells. Paucity of bcl-2 expression in normal cornea suggests that corneal epithelium may be more susceptible to apoptosis than limbal and conjunctival epithelia.
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|