Abstract
Purpose :
Transposable elements (TEs) are mobile nucleotide fragments that account for approximately half of the human genome. Their aberrant expression is pathogenic for a range of neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and age-related macular degeneration (AMD). However, whether TEs are players in anaphylatoxin-triggered alternate complement signaling in dry AMD is unknown. We investigated alternate complement-induced TE activation in AMD pathogenesis using a well-established induced pluripotent stem cell derived RPE (iRPE) model.
Methods :
Mature iRPE grown on transwells were treated with complement competent human serum (CC-HS) with activated anaphylatoxins to model dry AMD or complement incompetent human serum (CI-HS) with heat inactivated anaphylatoxins as a control (as described in Sharma et al., 2021). Total RNA was extracted with mirVana miRNA Isolation Kit, then assessed for integrity with nanodrop and bioanalyzer. RNA sequencing employing a custom-built index with TEToolkit GTF was performed to identify TE subtypes. Differentially expressed TEs were determined by degree of fold change and statistical significance. Differentially expressed genes located within 500kb of differentially expressed TE subtypes, were also analyzed as potential interacting elements of TE and regulatory network/pathway via ingenuity pathway analysis.
Results :
Among 211 top differentially expressed TE elements (e.g. Short-interspersed element (SINE) Alu; LINE1; SINER, VNTR, and Alu (SVA) and ERV), 129 were endogenous retrovirus (ERV) subtypes. ERVs also account for majority of TE count in the human genome. Residing near ERVs, genes involved in mitogenesis, branching of epithelial tissue, branching of cells, development of vasculature, cell movement of connective tissue cells, quantity of cells, size of body, inflammation (IL-8,and IL-15 signaling) and organismal death were identified.
Conclusions :
Activated-anaphylatoxins induced TEs, particularly, ERV in iRPE and altered set of genes/pathways that control cellular properties, likely leading to RPE degeneration. These data suggest TEs can serve as novel biomarkers of complement-mediated dry AMD pathogenesis.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.