Abstract
Purpose :
ELV, a novel lipid mediator class, derived from 32:6n3 and 34:6n3. We established stereochemistry of ELV, showing ELV mediate cell death protection from uncompensated oxidative stress (UOS) in human RPE and brain (Jun B, et al. Sci Rep 2017; Bhattacharjee S, et al. Sci Adv. 2017; Bazan NG. Mol Aspects Med. 2018). The present study investigates the role of ELV on telomerase activity and telomere-independent function under UOS or oligomeric amyloid β (OAβ). Telomerase is involved in senescence, DNA damage repair (DDR), and age-related pathologies. Telomeres act as mitotic clocks in neurodegeneration fueled by inflammation, and non-telomeric functions for the telomerase proteins TERT (Telomerase reverse transcriptase), TTI1 (TELO2-interacting protein 1 homolog), and RAP1 (repressor/activator protein1) influence key cellular processes in oxidative stress resistance and cell survival. These telomere-independent functions and signaling pathways are critical for cell survival. Thus, we investigated ELV function in modulating telomerase activity.
Methods :
Serum-starved primary RPE cultures were UOS - H2O2 (1200µM) +TNFα (10ng/ml) or OAβ (10μM) stressed and treated with ELV or other lipid mediators (200nM). Protein abundance was checked by Western blots, RNA transcripts and absolute telomere length (ATL) analyzed by RT-PCR, and Global DNA and histone H3K9 methylation assayed by ELISA.
Results :
Induction of TTI1 & RAP1 protein abundance upon UOS was attenuated by ELV-32:6 and 34:6, resp. ELV rescue TERT transcription upon UOS or OAβ, and compensate UOS and OAβ-upregulated global DNA methylation (5mC). UOS or OAβ upregulate H3K9 methylation in presence of ELV. ELV restore ATL in UOS and OAβ-stressed RPE.
Conclusions :
Our data suggest that ELV reduction of UOS or OAβ-induced TTI1 & RAP1, and upregulation of TERT, neuroprotection, restoration of ATL, and 5mC involve key targets of telomerase. The telomerase complex is involved in DDR; we know DNA repair enzymes are activated in photoreceptors by photo-oxidative stress. We are currently defining ELV-specific mechanisms; this novel signaling may be fundamental for photoreceptor integrity. ELV may act as epigenetic regulators contributing to cell survival/senescence decisions.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.