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" Transcriptional Regulation of the Developing Retina "
Goodson, Noah Branch
Brzezinski, Joseph A.
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Latin Dissertation
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English
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| Record Number
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1053898
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| Doc. No
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TL53015
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| Main Entry
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Goodson, Noah Branch
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| Title & Author
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Transcriptional Regulation of the Developing Retina\ Goodson, Noah BranchBrzezinski, Joseph A.
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| College
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University of Colorado Denver, Anschutz Medical Campus
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| Date
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2020
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Ph.D.
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2020
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| Note
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248 p.
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| Abstract
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The retina is a complex stratified neural tissue required for all mammalian vision. During development, tightly controlled transcriptional regulation drives diversification from a homogenous population of retinal progenitor cells into seven major types and dozens of subtypes of cells. Here, we explored the role of the transcription factors Otx2, Prdm1, Prdm13, and Vsx2 in driving the formation of specific neurons from retinal progenitors. We first showed that PRDM13 is expressed in a subset of developing amacrine interneurons. Loss of Prdm13 leads to a 25% reduction in amacrine cells and disruption of retinal sublamina formation. Next, we explored the role of Prdm1 and Vsx2 in driving the correct formation of rod photoreceptors and bipolar interneurons. In OTX2+ cells late in retinal development, Prdm1 and Vsx2 work in opposition, such that Prdm1 promotes photoreceptor cell fate and Vsx2 bipolar cell fate. We deleted Prdm1 and Vsx2 or their cell type-specific enhancers simultaneously using a CRISPR/Cas9 in vivo retina electroporation strategy. Double enhancer targeting favored bipolar outcomes whereas double gene targeting favored photoreceptor fates. Both conditions generated excess amacrine cells. We show photoreceptors are a default fate outcome in OTX2+ cells and VSX2 is required during a narrow temporal window to drive bipolar cell formation. Prdm1 and Vsx2 appear to redundantly restrict the competence of OTX2+ cells, preventing amacrine cell formation. Next, we explored the stability of VSX2+ bipolar fates. To do this, we created a system to conditionally misexpress Prdm1 during bipolar cell development. We found that Prdm1 blocks bipolar formation if expressed before the fate choice decision occurred. Constitutive PRDM1 expression in nascent bipolar cells can cause a fate shift to rods but has no effect on mature bipolar cells. PRDM1 was selectively toxic to mature rods. Our data show that bipolar fate is malleable, but only for a short period following fate specification. OTX2+ cells use Prdm1 and Vsx2 to stabilize photoreceptor and bipolar cell identities during development and maturation of proper amacrine subtypes requires Prdm13. Our work provides novel insights into the complex regulatory mechanisms that control cell fate choice in the developing murine retina.
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| Descriptor
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Developmental biology
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Neurosciences
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Ophthalmology
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Brzezinski, Joseph A.
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University of Colorado Denver, Anschutz Medical Campus
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