Abstract
Purpose :
A gradual decline of visual sensory functions in aged individuals reflects underlying transcriptional dysregulation during aging in the mammalian retina. Understanding cellular and molecular aberrations in distinct retinal cell types is crucial for comprehending the complexities of aging. We report single-cell RNA sequencing analysis based on an optimized protocol to identify age-associated transcriptional changes of retinal cells.
Methods :
Cells from whole retina, before and after rod-depletion via CD73 marker, of 3-, 12-, 18- and 24-month-old mice were obtained by enzymatic dissociation and used for scRNA-seq by 10X Genomics platform. An optimized Cell Ranger/Seurat pipeline including decontX, DoubletFinder, and SCTransform tools was employed. Cell type, age-dependent differential expression analyses were performed using the Wilcoxon Rank Sum test.
Results :
Single cell profiles from ~72,000 cells were used in unsupervised clustering and annotated for 35 distinct clusters representing the 6 major neuronal cell types, glial and endothelial cells, and pericytes. Quantitative composition of neuronal cell types was not significantly different during aging; yet, higher number of differentially expressed genes were observed for photoreceptors, bipolar cells, and Muller glia. In addition, our analysis revealed the existence of transcriptionally distinct, heterogeneous subpopulations of rod photoreceptors. Phototransduction efficient rods exhibited high expression of genes involved in scotopic light detection, cellular response to hypoxia, and mitochondrial ATP synthesis, whereas synaptic transmission-efficient rods revealed high expression of genes involved in neurotransmission.
Conclusions :
We identified altered transcriptomic profiles and biological pathways associated with the 6 major neuronal cell types in the aging retina. CD73 depletion allowed for significant enrichment of non-rod cell types at each age, particularly rod and cone bipolar cells. Cellular heterogeneity contributes to the complexity of understanding of aging’s effect on the retina. Further investigations will provide deeper insights into molecular mechanisms underlying visual function defects in aging retinal cells.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.