Abstract
Purpose :
MicroRNAs (miRNAs) are small, non-coding RNAs which comprise a large family of post-transcriptional regulators of gene expression. Several miRNAs (miR-146a, -125b, and -34a) have been associated in the pathogenesis of age-related macular degeneration (AMD). Here, we tested 10 selected candidate miRNAs in tear fluids, eye tissues and 5 different brain regions (neocortex-hippocampus, olfactory bulb, striatum-thalamus-hypothalamus, brainstem, and cerebellum) of a transgenic AMD mouse model and its matched control to see the miRNA expression levels and their direction of regulation over time.
Methods :
High-fat diet apolipoprotein E knockout (ApoE−/−) and wildtype (WT, C57BL/6J) female mice (n=16, 4 per group) were studied at young, 3-4 months and old, 9-10 months. Expression level of mature miRNAs -101a-3p, -125b-5p, -140-3p, -146a-5p, -15a-5p, 34a-5p, -342-3p, -374c-5p, -302c-3p and -653-5p were determined using TaqMan advanced miRNA assays. Cycle threshold (Ct) values normalized to Cel-miR-39-3p were compared between young ApoE−/− vs. WT and between old ApoE−/− vs. WT mice separately for tear fluids, eye tissues and brain regions. A statistically significant (2-tailed Welch’s t-test at a Bonferroni corrected P <0.01) intergroup >2-fold difference was used to determine the differentially expressed miRNAs.
Results :
8 miRNAs were detected at Ct <35.0. miR-146a, a proinflammatory marker was significantly upregulated in the tears of both young (7.8-fold) and old (5.8-fold) ApoE−/− mice compared to its age-matched WT control. miRNAs -34a, -15a and -342 were also significantly upregulated in the tears of old ApoE−/− mice. Between young ApoE−/− vs. WT eyes, miR-374c (2.7-fold), and between old ApoE−/− vs. WT eyes, miR-146a (6.5-fold), -125b (4.1-fold) and -374c (3.6-fold) were significantly upregulated. Regarding different brain regions, all tested miRNAs were significantly downregulated or insignificant in young ApoE−/− mice. In contrast, most of the tested miRNAs were significantly upregulated in old ApoE−/− mice. Notably, miR-146a was upregulated by 62.4, 41, and 32.7 folds in neocortex-hippocampus, olfactory bulb and brainstem, respectively.
Conclusions :
Our study has demonstrated the translational potential of tear fluids’ miRNAs in a transgenic early stage AMD model and with changes over time. Detailed interpretation and significance of the results will be discussed.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.