Abstract
Purpose :
Cholesterol plays crucial biological roles and dysregulation of cholesterol homeostasis is associated with many neurodegenerative disorders. Retinal cholesterol accumulation is involved in age-related macular degeneration, the leading cause of vision loss in western countries. Under physiologic conditions, cholesterol homeostasis relies on neuron-glia communication and the elimination of cholesterol involves its conversion into oxysterols through the action of cholesterol hydroxylases, including the retinal CYP27A1 enzyme. We aim to determine the importance of Cyp27a1 orthologous genes in neuron-glia interactions and the integrity of the visual system during aging in the powerful genetic model that is Drosophila.
Methods :
Potential drosophila Cyp27a1 orthologous genes were screened for their expression in the retina using a dual approach. Their expression levels were measured using RT-qPCR on flies following specific inhibition by RNA interference (RNAi) of candidate genes in the retina, or in eyeless flies compared to control flies. Then, the expression of the selected Cyp27a1 orthologous genes was downregulated specifically in retinal glial cells or photoreceptors by RNAi to determine their role in retinal cholesterol metabolism and the maintenance of retinal integrity. Retinal cholesterol levels of flies were measured by gas chromatography coupled with mass spectrometry. The structure of their retina was studied by immunohistochemistry.
Results :
We identified DmCyp12c1 gene that is mainly expressed in the retina of Drosophila. Retinal cholesterol levels of flies with invalidated DmCyp12c1 gene expression in glial or neuronal cells are similar from those of control flies, either in young or aged flies reared on cholesterol-supplemented food. Interestingly, we observed an age-related disorganization of the ommatidia in adult flies when DmCyp12c1 gene was specifically invalidated in neuronal cells of the retina during adulthood.
Conclusions :
DmCyp12c1 gene expression seems to be only required in photoreceptors for retinal integrity in Drosophila. Its mechanism of action and its potential role in cholesterol homeostasis in Drosophila retina still remains to be determined.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.