Abstract
Purpose :
Age is an important risk factor for developing several ocular pathologies (e.g. glaucoma, age-related macular degeneration). Menopause is a major biological life event that affects aging women and has also been linked to ocular pathologies (Douglass et al. 2022).Here we investigate changes in gene expression associated with TGF-β, TNF-α, and ECM pathways in the retina with age and after surgical menopause (ovariectomy).
Methods :
Retinal RNA was isolated from 12 young (3-4 months) and 12 middle-aged (9–10 months) female Brown Norway rats evenly divided to undergo Sham surgery or ovariectomy (OVX). OVX is the surgical removal of ovaries causing a decrease in ovarian hormones. After 8 weeks we performed bulk RNA sequencing on retinal tissues to obtain count data. Count data were normalized and differentially expressed genes were identified using DESeq2. Gene set variation analysis was used to identify differentially enriched TGF-β, TNF-α and ECM related gene sets.
Results :
Hierarchical clustering revealed regions of upregulated and downregulated gene expression in middle-aged compared to young animals, suggesting age affects retinal gene expression (Fig.1). Principal component analysis (PCA) displayed that Young OVX samples were closer to both middle-aged cohorts (Sham and OVX). Volcano plot analysis showed differential expression in TGF-β, TNF-α, and ECM gene set related pathways for both age and OVX effects. TGF-β1 (downregulated), ADAM15 (upregulated), ADAMTS2 (upregulated) were among the top differentially expressed genes in middle-aged compared to young Sham animals (adjusted p-value<0.03). SPHK1, a gene involved in cell proliferation and junction formation that may signal retinal stress (Chen et al. 2013) was the top upregulated gene(adjusted p-value<0.05) in OVX animals compared to Sham.
Conclusions :
Our results show differential gene expression following aging and OVX in TGF-β, TNF-α and ECM related pathways. PCA results suggest greater OVX effect in younger animals. These results suggest that the age of OVX plays a role in the underlying cellular response. Notably, OVX affected gene expression along the TGF-β, TNF-α, ECM pathways, which may impact the cellular response of the retina to an insult or injury. Further research is needed to understand how these changes in gene expression are related to developing retinal pathologies.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.