Abstract
Purpose :
Early events in lens development involve interactions between the optic vesicle and the overlying surface ectoderm. This leads to induction of the presumptive lens ectoderm into forming the lens placode that undergoes morphogenesis to form the lens vesicle. This subsequently develops into the lens comprising of anteriorly localized epithelial cells and posteriorly localized fiber cells. While factors involved in signaling and transcription that regulate these processes are well defined, those involved in post-transcriptional control are not well characterized. Therefore, we sought to understand the role of the RNA-binding protein (RBP) Rbm24 (RNA-binding motif protein 24) in the early eye and lens development in mouse and Xenopus animal models.
Methods :
We used iSyTE (integrated Systems Tool for Eye gene discovery) to identify Rbm24 as a high-priority candidate based on the lens-enriched expression. Rbm24 germline and conditional knockout (cKO) mice were generated and phenotypically and molecularly characterized. Immunostaining was performed on wildtype and cKO mouse embryonic day (E)10.5 eye tissue using various antibodies. Rbm24 expression in Xenopus tropicalis was validated by RT-qPCR.
Results :
Rbm24 expression was confirmed in mouse optic vesicle and lens at E9.5 and in later stages. In X. tropicalis, the ortholog of mouse Rbm24 was also confirmed to be expressed in the lens, indicating its conserved expression in vertebrates. Additionally, in X. tropicalis, Rbm24 was knocked down in cells that contribute to the eye by using a morpholino that blocks translation. X. tropicalis Rbm24 morphants exhibit small eye defects at stage 42. Similarly in mouse, Rbm24 germline and cKO animals exhibit ocular defects namely, small eye and/or absence of discernable eye and lens tissue. Rbm24 cKO mice also exhibited reduced expression of multiple eye and/or lens markers.
Conclusions :
Here we show that Rbm24 expression in the lens is conserved between mouse and Xenopus. Further, Rbm24 knockdown or knockout in Xenopus and mouse, respectively, results in eye defects. This uncovers a conserved role for Rbm24 in vertebrate eye development. Finally, the establishment of Rbm24 X. tropicalis morphants represents a resource to perform rescue experiments with Rbm24-downstream targets, thus allowing the definition of the specific pathways that contribute to the eye and lens defects.
This is a 2020 ARVO Annual Meeting abstract.