Talk abstracts

Talk on Saturday 11:45-12:00pm submitted by Soma Dash

Rbm24-mediated post-transcriptional gene regulation is necessary for vertebrate eye development

Soma Dash (Department of Biological Sciences, University of Delaware), Lindy K. Brastorm (Department of Biological Sciences, University of Iowa), C. Anthony Scott (Department of Biological Sciences, University of Iowa), Diane C. Slusarski (Department of Biological Sciences, University of Iowa), Salil A. Lachke (Department of Biological Sciences, University of Delaware)

While transcriptional and signaling regulation are well-defined in eye development, post-transcriptional control (PTC) mediated by RNA binding proteins (RBP) remains less clear. Recently we described three RBPs Tdrd7, Celf1 and Caprin2 required for vertebrate lens development. Here we define the function of another RBP Rbm24 - identified using iSyTE (integrated Systems Tool for Eye gene discovery) – in vertebrate eye development. In zebrafish rbm24a expression begins in the ocular tissue at 1-somite stage, while in mouse it is expressed in lens and retina at embryonic day (E) 9.5. rbm24a morpholino knockdown zebrafish morphants exhibit microphthalmia (abnormally small eye). We generated new targeted germline deletion mouse mutants of Rbm24 (Rbm24-/-), which exhibit 100% penetrant microphthalmia and 50% penetrant anophthalmia (absence of eye). Interestingly, the human anophthalmia-linked gene SOX2 is downregulated at both mRNA and protein levels in Rbm24-/- ocular tissue. RNA immunoprecipitation assay suggests that Rbm24 binds to Sox2 mRNA in E14.5 mouse eye tissue. Further, to characterize Rbm24 mediated control over Sox2 we co-transfected NIH3T3 cells with Rbm24 overexpression vector and luciferase reporter vector wherein Renilla luciferase is fused to 3’UTR of Sox2. Following actinomycin-D treatment, we find the half-life of luciferase mRNA fused to 3’UTR of Sox2 is increased in Rbm24 overexpressing cells compared to control. This suggests that Rbm24 binds to the 3’UTR of Sox2 and stabilizes its mRNA. Further, mutation of the AU-rich elements (ARE) in the 3’UTR of Sox2 in the luciferase reporter vector failed to increase the mRNA half-life of luciferase with Rbm24 overexpression. This suggests that Rbm24-medited Sox2 mRNA stability is mediated by its binding to the ARE sites in 3’UTR of Sox2. These data identify Rbm24 as a new factor controlling vertebrate eye development and define a new RBP-mediated post-transcriptional mechanism to control Sox2 expression.

Keywords: RNA Binding Proteins, Post-transcriptional regulation