Spatiotemporal expression profiling of retinoschisin (RS1) homologues Rs1a and Rs1b in the developing zebrafish retina

Abstract

Purpose : The protein retinoschisin (RS1) is essential for normal retinal architecture. In patients lacking this protein, retinal lamination is compromised and cystic cavities develop in the inner retina. As the RS1 gene is location on the X-chromosome, the disease affects males. Symptoms generally start in early childhood. The exact role of RS1 in retinal development is still unclear. Zebrafish are a promising model for studying retinal development, as the majority of the development occurs already within five days post-fertilization. The zebrafish genome contains two homologues for RS1; Rs1a and Rs1b. In this study, we have characterized the gene and protein expression of these genes in zebrafish, and their localization throughout the first five days of retinal development.

Methods : Wildtype Tüpfel Longfin zebrafish larvae were raised according to ZFIN standards. Wildtype larvae were sacrificed at regular time points between 24 – 120 hours post-fertilization (hpf). Adult zebrafish tissue was collected at 2 months of age. Gene and protein expression of these and other genes related to retinal development were assessed with respectively RT-(q)PCR and Western Blot. Immunohistochemistry was used to determine (co-)localization of the proteins.

Results : We have characterized the spatiotemporal profile of Rs1a and Rs1b gene expression and Rs1a and Rs1b protein presence up to 120 hours post-fertilization. For both genes, expression started at 48 hpf and reached stable levels from 96 hpf onwards. Detectable protein presence followed at 36 hpf and continually increased up to 120 hpf.

Conclusions : Zebrafish provide a rapid, easily accessible model organism and are thus promising for studying RS1 in the context of retinal development. The spatiotemporal expression profile of RS1 homologues coincides with important events in retinal development. Rs1a and Rs1b may be involved in the coordination and maintenance of retinal architecture.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.