Single Cell RNAseq Analysis of Thyroid Hormone Effects on Retinal Glial Cells

Thyroid hormone (TH) signaling regulates cellular metabolism and stress response in the retina. Increased TH levels in circulation are associated with a higher incidence of age-related macular degeneration. Furthermore, stimulation of TH signaling induces retinal degeneration in mice, which is accompanied by the activation of retinal glial cells. Here, we investigated the transcriptional changes induced by triiodothyronine (T3) in retinal glial cells using single-cell RNA sequencing (scRNAseq) and bioinformatic analyses. One-month-old C57BL/6 mice were given T3 (20 μg/ml in drinking water) for four weeks, after which their retinal cells were collected to assess viability and undergo scRNAseq. The resulting data were analyzed using the Seurat package, visualized by the Loupe Browser, and Ingenuity Pathway Analysis. Analyses of differentially expressed genes (DEGs) in Müller cells, astrocytes, and microglia revealed significant enrichment in pathways associated with stress, immune response, and degeneration. Müller cells exhibited upregulation of mitochondrial dysfunction, acute-phase response, and sirtuin signaling pathways. Astrocytes displayed downregulation of synaptogenesis, neurovascular coupling, cAMP response elements, and calcium signaling. Microglia showed upregulation of coordinated lysosomal expression and regulation signaling, systemic lupus erythematosus in T cells, and multiple sclerosis signaling, and downregulation of actin-binding Rho activating signaling, retinoic acid receptor activation signaling, and IL-17 signaling. The distinct and overlapping transcriptional responses suggest that each retinal glial cell type plays a specific and coordinated role in adapting to stress. This study offers new insights into TH-induced retinal stress and degeneration at the transcriptional and pathway-level responses of retinal glial cells.