Abstract
Purpose :
To evaluate the in situ spatial mRNA expression of 4 Wnt ligands (WNT2, WNT6, WNT11, WNT16B), 4 Wnt inhibitors (dickkopf WNT Signaling Pathway Inhibitor 1 [DKK1], secreted frizzled-related protein 5 [SFRP5], frizzled-related protein [FRZB], WNT inhibitory factor 1 [WIF1]), and frizzled7 (Fzd7), that have been shown previously upregulated in the limbus by differential gene profiling using q-RT-PCR.
Methods :
The V2 fluorescent RNAscope (ACD, Newark, California) was performed on fresh frozen tissue sections from 5 human corneas with less than 8 hours of death to preservation time and intact epithelium. Positive signals were quantified using Imaris software.
Results :
All 4 Wnt ligands, 4 Wnt inhibitors, and Fzd7 were preferentially expressed in the basal layer of the cornea and limbus compared to the suprabasal layer (P<0.05). When compared with the basal corneal epithelial layer, all 4 Wnt ligands, FRZB, and Fzd7 were preferentially expressed in the basal limbal epithelial layer in a decreasing gradient manner towards the superficial layers (P<0.05). No gradients were found for DKK1, WIF1, and SFRP5 expression. All 4 Wnt ligands, 4 Wnt inhibitors, and Fzd7 were also detected in the limbal stroma (P<0.05). Fzd7 was preferentially expressed in the basal limbal epithelial layer of the superior limbus compared with other limbal quadrants (P<0.05).
Conclusions :
Wnt ligands are expressed in a gradient manner towards the superficial layers. Both paracrine and autocrine Wnt signaling pathways are involved in LSCs regulation, suggesting that a fine tuning of Wnt signaling exists to control LSC differentiation and proliferation.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.