Abstract
The retinoid cycle is a metabolic process in the vertebrate retina that continuously regenerates 11-cis-retinal (11-cisRAL) from the all-trans-retinal (atRAL) isomer. atRAL accumulation can cause photoreceptor degeneration and irreversible visual dysfunction associated with incurable blinding retinal diseases, such as Stargardt disease, retinitis pigmentosa (RP), and atrophic age-related macular degeneration (AMD). The underlying cellular mechanisms leading to retinal degeneration remain uncertain, although previous studies have shown that atRAL promotes calcium influx associated with cell apoptosis. To identify compounds that mitigate the effects of atRAL toxicity, here we developed an unbiased and robust image-based assay that can detect changes in intracellular calcium levels in U2OS cells. Using our assay in a high-throughput screen of 2,400 compounds, we noted that selective estrogen receptor modulators (SERMs) potently stabilize intracellular calcium and thereby counteract atRAL-induced toxicity. In a light-induced retinal degeneration mouse model (Abca4-/- Rdh8-/-), raloxifene (a benzothiophene-type scaffold SERM) prevented the onset of photoreceptor apoptosis and thus protected the retina from degeneration. The minor structural differences between raloxifene and one of its derivatives (Y 134) had a major impact on calcium homeostasis after atRAL exposure in vitro, and we verified this differential impact in vivo. In summary, the SERM raloxifene has structural and functional neuroprotective effects in the retina. Wepropose that the highly sensitive image-based assay developed here could be applied for the discovery of additional drug candidates preventing photoreceptor degeneration.
| Original language | English |
|---|---|
| Pages (from-to) | 9461-9475 |
| Number of pages | 15 |
| Journal | Journal of Biological Chemistry |
| Volume | 294 |
| Issue number | 24 |
| DOIs | |
| State | Published - 14 Jun 2019 |
| Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2019 Getter et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc.
Funding
This research was supported in part by NEI, National Institutes of Health, Grants R24EY024864 and R24EY027283 (to K. P.), EY024992 (to Y. C.), T32GM007250 and F30EY029136-01A1 (to S. S.), and R01EY027691 (to J. T. H.); an unrestricted grant from Research to Prevent Blindness to the Department of Ophthalmology at the University of California (Irvine, CA); the Canadian Institute for Advanced Research (CIFAR); and the Alcon Research Institute (ARI). K. P. is Chief Scientific Officer at Polgenix, Inc. Z. D. and X. M. are employees of Polgenix, Inc. The content is solely the respon-sibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This research was supported in part by NEI, National Institutes of Health, Grants R24EY024864 and R24EY027283 (to K. P.), EY024992 (to Y. C.), T32GM007250 and F30EY029136-01A1 (to S. S.), and R01EY027691 (to J. T. H.); an unrestricted grant from Research to Prevent Blindness to the Department of Ophthalmology at the University of California (Irvine, CA); the Canadian Institute for Advanced Research (CIFAR); and the Alcon Research Institute (ARI)
| Funders | Funder number |
|---|---|
| Alcon Research Institute | |
| Canadian Institute for Advanced Research | |
| National Institutes of Health | EY024992, T32GM007250, F30EY029136-01A1 |
| National Eye Institute | R24EY024864, R01EY027691, R24EY027283 |
| Research to Prevent Blindness | |
| University of California | |
| Canadian Institute for Advanced Research | |
| Alcon Research Institute |