Exposure to subthreshold dose of UVR-B induces apoptosis in the lens epithelial cells and does not in the lens cortical fibre cells.

PURPOSE: The aim of this study was to investigate in which part of the lens in vivo exposure to subthreshold dose of UVR-B radiation induces apoptosis.

METHODS: Twenty 6-week-old female albino Sprague-Dawley rats were exposed to subthreshold dose (1 kJ/m2 ) of UVR-B unilaterally and killed at 120 hr after exposure. Lenses were enucleated and dissected on three regions: the lens epithelium, the cortex and the nucleus. The lens nucleus then was removed. Apoptosis markers p53 and caspase 3 were used to study apoptosis in the lens regions. qRT-PCR and Western blot were utilized to analyse the lenses.

RESULTS: TP53 and CASP3 mRNA expressions are increased in exposed lenses, both in the lens epithelium and in the cortex regions, in relation to non-exposed lenses. Expression of p53 protein is increased in exposed lens epithelium in relation to non-exposed lens epithelium. Caspase 3 protein is expressed in exposed lens epithelial cells, while it is not expressed in non-exposed lens epithelial cells. p53 and caspase 3 proteins are not expressed in either exposed nor non-exposed lens fibre cells.

CONCLUSION: Exposure to UVR-B increases mRNA transcription of apoptosis marker p53 in vivo in both regions of the lens and of apoptosis marker caspase 3 in the lens cortex. Exposure to UVR-B increases p53 and caspase 3 proteins expression just in the lens epithelium. In vivo exposure to subthreshold dose of UVR-B induces apoptosis in the lens epithelial cells and does not in the lens fibre cells.