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Ravirajsinh Jadeja, Folami Lamoke Powell, Menaka Thounaojam, Malita A Jones, Manuela Bartoli, Pamela M Martin; MicroRNA 144 regulates Nrf2 and related antioxidant signaling in RPE. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5381. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Nrf2 is a master regulator of antioxidant responses. Our prior published work confirmed the importance of Nrf2 signaling in the limitation of oxidative stress and the therapeutic induction of fetal hemoglobin (HbF) in erythroid and retinal pigment epithelial (RPE) cells, factors highly relevant to the prevention and clinical management of systemic and retinal complications of sickle cell disease (SCD). miR-144 emerged recently as a potential direct regulator of Nrf2, however little is known about the relationship between miR-144, Nrf2 and antioxidant signaling in retina. Given the critical involvement of and our keen interest in oxidative damage to RPE in SCD retinopathy and other degenerative retinal diseases, here we investigated the relevance of miR-144 expression to the regulation of Nrf2 and related antioxidant responses in RPE.
miR-144 expression was evaluated in RPE tissue isolated from HbAA (normal) and HbSS (SCD) mouse eyes. Additional inhibition or overexpression studies were performed in ARPE-19 cells transfected with anti-miR-144 or miR-144 mimic, respectively, and exposed to normal or pro-oxidant conditions (e.g., exposure to hypoxia or tert-butyl hydroperoxide, t-BHP). mRNA and protein analyses were performed using standard methods. Luciferase reporter assay was used to evaluate miR-144 and 3’-UTR binding.
miR-144 expression was significantly upregulated in SCD RPE compared to normal RPE, and in ARPE-19 cells exposed to hypoxic and/or pro-oxidant conditions. Importantly, miR144 was found to correlate negatively with Nrf2 expression. Overexpression of miR-144 in ARPE-19 cells resulted in a significant down-regulation of Nrf2 and HbF and increased susceptibility to t-BHP mediated oxidative stress and cytotoxicity, whereas, miR-144 inhibition significantly improved Nrf2 and HbF expression. Further, miR-144 overexpression in ARPE-19 enhanced susceptibility of cells to t-BHP mediated oxidative stress and cytotoxicity. Luciferase reporter assays confirmed the interaction of miR-144 with the 3’-UTR of Nrf2 to regulate its expression in RPE cells.
Our data support the role of miR-144 as a key regulator of Nrf2 expression and downstream antioxidant signaling in RPE, and therefore its potential utility as a therapeutic target and/or biomarker in degenerating retina. Future research efforts will be directed to validating these implications.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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