Abstract
Purpose: :
Altered iron homeostasis is associated with Age related macular degeneration (AMD). In a mouse model of defective iron storage protein we have observed an increase sensitivity of the retina to light induced damage. To determine the role of iron homeostasis proteins in iron regulation under oxidative stress conditions and as a function of age, we have compared the expression of the main iron proteins.
Methods: :
We used the retina from 3-4 and 16-18 months old mice heterozygous for the H Ferritin chain (HFt+/-) . Normal and HFt+/- mice were exposed to white light (13000 lux) for 24 hours and analysed 24 hours later for Iron regulation proteins expression ( H and L Ferritin, hephaestin, ceruloplasmin, ferroportin, transferrin, transferrin receptor, hepcidin, IRP1 and IRP2) by RT-qPCR.
Results: :
We observed after light injury that HFt but not LFt expression decreased in young mice retina conversely to LFt protein content which showed identical increase. With light, Transferrin and Tf receptor expression varied in opposite direction. Ceruloplasmin increased, hephaestin decreased as hepcidin, IRP1 and IRP2 but not ferroportin, independently of age and genotype
Conclusions: :
These results demonstrate that the illumination paradigm in these experiments is correlated with variations in gene expression of several iron responsive proteins reflecting an adaptation of the retina to an iron flux. Some of these responses may be impaired differently in young and old retina and may participate to the higher sensitivity of the aging retina to oxidative stress.
Keywords: retina • aging • retinal degenerations: cell biology