Abstract
Abstract: :
Purpose: Our objective was to identify endogenous retinal neuroprotective factors using differential display reverse transcription-PCR (DDRT-PCR). Method: Rats were born and reared in dim (5 lux) or bright (400 lux) cyclic (12/12) light for six weeks. Retina mRNA from each group was subjected to DDRT-PCR using an oligo-dT anchor with random 13mer primers. Differentially expressed sequence tags (ESTs) were sequenced and subjected to BLAST analysis. Differential regulation was confirmed at the message level by Northern blot and at the protein level by Western blot. In situ hybridization was used to localize COX-III expression in the retina. Results: Using DDRT-PCR we identified several EST that were differentially expressed. One EST showed 97% similarity to COX-III found in mitochondria. Retinal COX-III was down-regulated in bright cyclic light-reared animals. This difference was confirmed by Northern analysis and by Western blot. By in situ hybridization, we found down-regulation of COX-III throughout the retina including the photoreceptors. Conclusion: These results suggest a potential role for COX-III in adaptive neuroprotection in the retina. Down-regulation of COX-III, one of catalytic subunits of COX that regulates cytochrome C metabolism, suggests that one mechanism of stress-related adaptation may involve control of metabolism in mitochondria in photoreceptors and the neural retina. The mechanism and significance of the down-regulation of COX-III by light and its influence on mitochondria-mediated apoptosis are being studied.
Keywords: 554 retina • 592 stress response • 323 apoptosis/cell death