VEZF1 is a ubiquitously expressed transcription factor with epigenetic roles at gene regulatory elements, including protection from DNA methylation. Genetic ablation of Vezf1 in murine embryos is lethal due to haemorrhages localised in head and neck mainly. Interestingly, Vezf1 seems to be important for the generation of erythroid cells. The role of human VEZF1 in erythroid gene regulation was the primary focus of this study. Previous work found that VEZF1 unexpectedly interacts with the majority of erythroid-specific enhancer elements, including those at the α- and β-globin gene clusters, in the K562 cell line, a long- standing model for erythroid progenitor cells. The co-occupancy of VEZF1 with well characterised erythroid transcription factors and histone marks associated with active enhancers indicated that VEZF1 may support the regulation of the erythroid gene regulatory programme. To understand the role of VEZF1 in erythroid gene regulation and differentiation, we used CRISPR technology to knock out VEZF1 in K562 and hESCs. RNA-seq analysis revealed that VEZF1 does have regulatory roles at several erythroid genes, but it is not essential for the erythroid gene regulatory programme. VEZF1 null K562 cells display increased levels of haemoglobin biosynthesis. Intriguingly, we find that VEZF1 protein levels are progressively downregulated during the in vitro erythroid differentiation of human ESCs. VEZF1 null ESC cultures commit more readily to the erythroid lineage at the onset of erythropoiesis, which then proceeds as normal. VEZF1 is therefore not required for human erythropoiesis and appears to be an early regulatory block to erythropoiesis proceeding effectively. Careful inspection of the cultures at a stage prior to the onset of erythroid differentiation revealed that a sub-population of endothelial precursors was absent in VEZF1 null ESC cultures. We demonstrate that the absence of VEZF1 prevents the efficient differentiation of endothelial cells. The role of VEZF1 in vascular endothelial development is therefore conserved in mammals, although the impact on human endothelial differentiation appears to be more profound. VEZF1 is anticipated to be a key regulator of the vascular endothelial gene regulatory programme.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:721453 |
| Date | January 2017 |
| Creators | Rivera Gonzalez, Alejandro Xchel |
| Publisher | University of Glasgow |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://theses.gla.ac.uk/8337/ |
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