Abstract
Purpose :
Elovanoids (ELVs) are cell-specific neuroprotective lipid mediators derived from 32:6n3 and 34:6n3 that contribute to photoreceptor cell integrity and survival (Jun et al, 2017.Sci Rep 7(1):5279). Epigenomic perturbations are linked to telomerase integrity and histone modifications, which are mediated by inflammatory responses, senescence, and aging. Given that ELVs protect RPE cells and photoreceptors, we hypothesized that ELVs may act as epigenetic regulators by counteracting the damage triggered by several stressors in RPE cells.
Methods :
Serum-starved primary RPE cultures were exposed to uncompensated oxidative stress (UOS) [H2O2 (1200µM)+TNFα(10ng/ml)] or oligomeric amyloid beta (Oaβ) (10μM) or erastin stressed (10μM) (perturbs ferroptosis-dependent cell death) and treated with ELV (200nM). RNA transcripts analyzed by RT-PCR for telomerase integrity and telomere length, senescence gene programming; DNA and histone modifications assayed by ELISA. Retina and RPE-eyecups were isolated from 4-week-old Mfrprd6 , Adipor1-/- , and control wild-type (WT) mice. RNA was extracted and analyzed by RT-PCR for telomerase integrity.
Results :
In RPE cells, ELVs counteract UOS or Oaβ DNA methylation 5-methyl cytosine (5-mC) perturbation, ten-eleven translocation (TET)/DNA hydroxymethylation (5-hmC), DNA methyltransferase (DNMT) activity, and histone modifications (H3K9 hypermethylation and acetylation), thereby restoring telomere length attrition and telomerase activity. ELVs also counteract senescence-associated gene transcription: p16INK4a, p27KIP, p21CIP1, and p53. Interestingly, Mfrprd6 and Adipor1-/- retina had depleted levels of telomerase reverse transcriptase (TERT) when compared to age-matched controls.
Conclusions :
We uncovered that ELVs regulate epigenetic cues mediated by DNA and histone modifications, promoting RPE cell function and protecting photoreceptor integrity. Since, in RPE cells in culture, ELVs modulate telomerase (TERT) activity, we tested in vivo in Mfrprd6 and Adipor1-/- mice retina, with deleted key enzymes for the synthesis of the precursors of these lipid mediators. In fact, the ELV pathway is obliterated in these KO mice.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.