Abstract
Purpose :
Anophthalmia (congenital absence of the eye) and microphthalmia (congenital reduction in eye size) are ocular developmental disorders that affect 1-3.2 in 10000 human live births. While mutations in genes encoding transcription factors and signaling molecules have been linked to anophthalmia and microphthalmia, the significance of RNA binding proteins (RBPs) in early eye developmental processes or their defects is not yet defined. Here, we report on the identification of a new RBP Rbm24 (RNA binding motif protein 24) that exhibits conserved expression in vertebrate eye development, and whose deficiency causes anophthalmia, microphthalmia and lens defects in mouse mutants.
Methods :
The bioinformatics tool iSyTE (integrated Systems Tool for Eye gene discovery) was applied to predict Rbm24 as a candidate gene with potential function in eye development. In situ hybridization (ISH) and immunofluorescence (IF) were used to investigate Rbm24 mRNA and protein expression in mouse eye development. Rbm24 function in the eye was investigated by generating Rbm24 targeted deletion mouse mutants. Phenotypic characterization of mutant eye tissue was performed by histological analysis and IF assays with well-characterized markers of eye development.
Results :
Rbm24 protein expression is detected early in mouse eye development in the optic vesicle and the surface ectoderm at embryonic day (E)9.5. From E10.5 onwards, Rbm24 exhibits highly enriched expression in the lens, being scored among the top 1% of lens enriched genes, according to iSyTE microarray analysis. The high lens-enriched expression of Rbm24 is validated by ISH analysis. We find Rbm24-/- mice to exhibit anophthalmia and microphthalmia at 75% penetrance. Further, embryonic Rbm24-/- microphthalmic eyes exhibit a significant reduction in the lens markers gamma Crystallin and E-cadherin, suggesting that Rbm24 controls the proteome of lens epithelial and fiber cells, in addition to its function in early eye development.
Conclusions :
We report here the first evidence of an RNA binding protein Rbm24 linked to mammalian early eye defects, namely anophthalmia and microphthalmia, as well as to lens abnormalities. These data, together with our recent findings on the function of other RBPs Tdrd7, Caprin2 and Celf1 in the eye, suggest that conserved post-transcriptional gene expression regulators have evolved to orchestrate eye development in vertebrates.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.