Abstract
Purpose: :
During development, cells and tissues are constantly remodeled and apoptosis is one of the major mechanisms by which cells are dying. In this study we compared the gene and protein expression of two groups of pro-apoptotic molecules (Bad, Bak, Bax, and Fas, FasL, TRAIL) in the fetal and adult eye and investigated the localization of such molecules. The latter group of molecules contributes to the acquisition of immune privilege status of the eye.
Methods: :
Levels of apoptosis-related molecules were measured by real-time PCR on RNA extracted from fetal and adult eyes. Protein expression was examined by immunofluorescent staining and western blotting at different ages.
Results: :
The two groups of molecules showed different patterns of gene expression in fetal and adult eyes. We found that one group of pro-apoptotic molecules, Bad, Bak, and Bax, were more highly expressed in the fetal eyes, while the other group, Fas, FasL, and TRAIL had greater expression in the adult eye. Immunofluorescent staining of Bad showed that beginning at E16 staining was seen in the area of the developing RPE, while on days E18 and P1 staining was seen in the RPE and in the developing ganglion cell layer. In the adult eye, the strongest staining was seen in the RPE, with less staining in the ganglion cell layer. Staining was present on the corneal epithelium at all time points.
Conclusions: :
Higher levels of Bad, Bak, and Bax transcripts are expressed in fetal eyes, while Fas, FasL, and TRAIL are more highly expressed in adult eyes. The difference between these two groups of apoptosis-related molecules could be due to predominance of different mechanisms of apoptosis at different ages.
Keywords: apoptosis/cell death • development • retinal pigment epithelium