Abstract
Purpose :
Variants in MYRF have been identified in patients with nanophthalmos, with variable retinal degenerative findings. Analysis of early eye field loss of Myrf utilizing the Rx>Cre transgene. showed retinal pigment epithelial (RPE) defects and retinal degeneration. Here, we use scRNAseq on developmental and early postnatal eye cups from Myrf fl/fl;RxCre and control mice to uncover critical signaling pathways between the RPE and neighboring cell types to gain insights into mechanisms of eye growth.
Methods :
scRNAseq was performed on eye cups from three developmental time points in controls and Myrf fl/fl;RxCre mutants. Sequencing data was analyzed using Seurat and Nichenetr to evaluate differential expression and cellular communication. Differentially expressed genes were confirmed by immunostaining and RNAscope in the Myrf fl/fl;Rxcre and inducible Myrf fl/f/; RPE-Tyrosinase-CreErT2 mutant mice.
Results :
Bioinformatic analysis revealed differential expression of TGFbeta signaling family members within the RPE, including Wfikkn2, Tgfb2, Id1, and Id3. They suggest signaling interactions between the RPE, retina, and sclera which regulate eye development. Preliminary results suggest alterations in BMP signaling in the sclera of Myrf fl/fl;Rxcre mutants at P0, as detected by pSMAD 1/5/9 immunostaining suggesting this as a target cell type. Further, upregulation and expansion of Prss56 expression in late retinal progenitors (RPCs) was observed in Myrf fl/fl;Rxcre, suggesting a compensatory response from RPCs to maintain eye size. These hypotheses are being validated in an inducible RPE-specific deletion of Myrf, using the RPE-Tyrosinase-CreErT2 mice, to confirm loss of MYRF from the RPE causes the resulting phenotypes.
Conclusions :
These results suggest TGFbeta signaling as a major pathway controlled by MYRF in RPE and retinal development. Our studies also establish multiple models for analyzing the role of MYRF in the mouse and provide insights into cellular communication controlling eye growth.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.