GSBS Dissertations and Theses

Approval Date

5-17-2013

Document Type

Doctoral Dissertation

Academic Program

Interdisciplinary Graduate Program

Department

Molecular, Cell and Cancer Biology Department

First Thesis Advisor

Nathan Lawson, PhD

Keywords

Zebrafish Proteins, Endothelial Cells, MicroRNAs

Subjects

Dissertations, UMMS; Zebrafish Proteins; Endothelial Cells; MicroRNAs

Abstract

Etv2 is an endothelial-specific ETS transcription factor that is essential for endothelial differentiation and vascular morphogenesis in vertebrates. However, etv2 expression dynamics during development and the mechanisms regulating it are poorly understood. I found that etv2 transcript and protein expression are highly transient during zebrafish vascular development, with both expressed early during development and then subsequently downregulated. Inducible knockdown of Etv2 in zebrafish embryos prior to mid-somitogenesis, but not later, causes severe vascular defects, suggesting a role for Etv2 in specifying angioblasts from the lateral mesoderm. I further demonstrate that the 3’UTR of etv2 is post-transcriptionally regulated in part by the let-7 family of microRNAs. Ectopic expression of let-7a represses endogenous Etv2 transcript and protein expression with a concomitant reduction in endothelial cell gene expression. Additionally, overexpressed Etv2 in HEK293T cells is ubiquitinated and degraded by the proteasome. Accordingly, endogenous zebrafish Etv2 protein is rapidly degraded in the presence of the translation inhibitor cycloheximide in vivo. Taken together, our results suggest that etv2 acts during early development to specify endothelial lineages and is subsequently downregulated through post-transcriptional and post-translational mechanisms, to allow normal vascular development to proceed.

DOI

10.13028/M21K56

Rights and Permissions

Copyright is held by the author, with all rights reserved.

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