Dissertation
A tale of two organs: Dysregulation of rbm24a leads to microphthalmia and cardiomyopathy in zebrafish
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2020
DOI: 10.17077/etd.005657
Abstract
RNA binding proteins are a large family of proteins involved in the post-transcriptional regulation of target genes. These proteins regulate at the level of RNA through several processes including RNA stability, polyadenylation, and alternative splicing. Recently, the RNA binding motif protein, Rbm24a, has been identified for its roles in both eye and heart development in vertebrates, with knockdown and mutation of rbm24a leading to microphthalmia and cardiomyopathy respectively. We modulated rbm24a activity in zebrafish and found a dose-dependent effect leading from normal eyes to severe microphthalmia. We performed visual assays on moderately affected embryos and found visual defects which worsened with more severe phenotypes. In order to further understand the mechanism of rbm24a function in the eye, we identified a target RNA: the proliferative and pluripotency factor sox2. We demonstrated that sox2 RNA levels were reduced in rbm24a knockdown embryos and we examined proliferation and apoptosis in these knockdown zebrafish, finding evidence for increased apoptosis. In functional assays to determine the interaction between Rbm24a and sox2, we found the microphthalmia phenotype induced by depletion of rbm24a can be suppressed with exogenous sox2 RNA. Moreover, we demonstrated functional restoration of vision in embryos which received both rbm24a knockdown and sox2 RNA when compared to rbm24a knockdown alone. Finally, we characterized the cardiomyopathy phenotype and reduced heart tube size in rbm24a depleted embryos when compared to control embryos. A potential cardiac target of Rbm24a: myh6, an atrium-specific factor needed for proper contractions, was decreased in rbm24a depleted embryos. Taken together, my work displays the importance and multifunctionality of post-transcriptional regulation by RNA binding proteins, specifically rbm24a.
Details
- Title: Subtitle
- A tale of two organs: Dysregulation of rbm24a leads to microphthalmia and cardiomyopathy in zebrafish
- Creators
- Melinda Kimberlee Brastrom
- Contributors
- Diane C Slusarski (Advisor)Douglas W Houston (Committee Member)Sheila A Baker (Committee Member)Michael E Dailey (Committee Member)Bryan T Phillips (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Biology
- Date degree season
- Autumn 2020
- DOI
- 10.17077/etd.005657
- Publisher
- University of Iowa
- Number of pages
- xiv,193 pages
- Copyright
- Copyright 2020 Melinda Kimberlee Brastrom
- Language
- English
- Description illustrations
- illustrations (some color)
- Description bibliographic
- Includes bibliographical references (pages 171-193).
- Public Abstract (ETD)
The regulation of gene expression is critical to the development of all organisms. While the regulation at the level of DNA, or transcriptional regulation, has been well studied, the regulation of RNA, or post-transcriptional regulation, has been neglected. We analyzed the RNA binding motif protein, or rbm24a, for its role in development. We found that decreasing the amount of rbm24a in our animal model, the zebrafish, lead to smaller than normal eyes (microphthalmia) and a deformed heart which accumulated fluid (cardiac edema). We investigated the visual capabilities of the zebrafish with microphthalmia and showed they were capable of detecting light but could not process a pattern of black and white lines. We next identified a target RNA of Rbm24a that is important for cell growth and survival (sox2). By simultaneously decreasing rbm24a and providing exogenous sox2, we were able to show that sox2 was able to phenotypically and partially functionally restore visual capabilities. In addition to rbm24a leading to microphthalmia, we also investigated its other prominent phenotype: cardiomyopathy leading to cardiac edema. We determined size of the early developing heart is smaller in rbm24a knockdown embryos and identified a potential RNA target, myh6. This work displays the importance of RNA binding proteins, specifically rbm24a, in the formation and function of the eye and heart.
- Academic Unit
- Biology
- Record Identifier
- 9984035795302771
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