Abstract
Purpose :
Glycosphingolipids (GSLs) exhibit a crucial role in cell signaling and differentiation. GSL synthesis depends on the relative expression of specific glycosyltransferases that sequentially add glycan motifs to a ceramide core. Based on the composition of the glycan chain, GSLs are classified in different families such as globosides and gangliosides. The role and distribution of GSLs in the cornea is not completely understood. Here, we present a comprehensive analysis of the GSL expression patterns in human and mouse cornea.
Methods :
Single-cell RNA-seq databases from human (GSE155683) and mouse (GSE158454) cornea were obtained from the Gene Expression Omnibus public repository. The Seurat R package was used for the analysis of principal components from highly variable genes. Louvain algorithm was applied to generate cell clusters. Human corneas were provided by Lions VisionGift and processed for cryosectioning. Immunofluorescence was performed with antibodies against the globosides SSEA3, SSEA4 and GloboH.
Results :
Analysis of human scRNAseq dataset revealed low expression of GSL glycosyltransferases in limbal stem cells (LSCs) compared to more differentiated epithelial cells. Transferases responsible for the initial synthesis of glucosylceramide (UGCG) and lactosylceramide (B4GALT5) were higher in more superficial cells of the corneal and conjunctival epithelia as compared to basal cells and LSCs. A similar pattern was found when analyzing the globo- (A4GALT) and lacto/neolacto-series (B3GNT5), with a higher expression towards more differentiated cells. Immunofluorescence staining of human corneas confirmed low expression of the globosides SSEA3, SSEA4 and GloboH in basal limbal epithelial regions and an increased staining in the central cornea. The examination of murine scRNAseq dataset showed major differences compared to human. Mouse LSCs exhibited high levels of the ganglioside transferase B4galnt1, which was decreased towards central epithelium, and lacked expression of globo- and lacto/neolacto-related enzymes.
Conclusions :
Human and mouse corneal epithelia differ in the expression and distribution of GSLs. These results might have implications for the unique biology of the corneal epithelium in different species.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.