To understand the causes of early pregnancy pathologies and miscarriages we need to increase our understanding of early mammalian development. Moreover, knowledge about how the first lineages in the mammalian embryo are formed is elemental for defining the optimal conditions for maintaining pluripotent embryonic stem (ES) cells in a stable undifferentiated state and inducing them to differentiate. This in turn is critical to provide safe and effective cell therapies in regenerative medicine.

This project aims to understand when and how the epiblast – a pluripotent cell lineage that gives rise to the whole fetus (and is a source of ES cells) – arises within the developing preimplantation embryo. In particular we want to determine whether the signals initiating epiblast specification come from cell-cell and cell-environment interactions or whether the process remains under the genetic control of transcriptional factors. We also want to clarify what factors are crucial for the stabilisation of the epiblast lineage during development.

In this project a student will have chance to learn basic molecular biology methods as well as more advance methods used in experimental embryology and IVF clinics, such as embryo handling and culture, microinjection and micromanipulation.

Sprouting of new capillaries from pre-existing vessels (angiogenesis) promotes the formation of almost all blood vessels during development, growth and tissue regeneration. Furthermore, imbalances in angiogenesis contribute to numerous disease states, including cancer, blindness, arthritis and ischemic disorders. Recent studies have determined that angiogenesis involves coordinated sprouting of specialized endothelial cells with distinct cell-fate specifications and behaviours. Endothelial “tip cells” lead sprouting vessels, extend filopodia and migrate in response to gradients of the soluble ligand, vascular endothelial growth factor (VEGF). In contrast, “stalk cells” trail behind tip cells, do not actively migrate and generate a vascular lumen. The induction of specific endothelial cell phenotypes and angiogenesis involves the tight spatiotemporal control tip/stalk cell-specific gene expression. However, the cell-type-specific transcriptional mechanisms that control gene expression during angiogenesis are unclear. Combining advanced genomic and in vivo cell biological approaches in the zebrafish model system we have identified various tip/stalk cell-specific genes that play key roles during angiogenesis in zebrafish. This project will define the cis regulatory elements controlling expression of these tip/stalk cell-restricted genes in vivo. Furthermore, these cis-regulatory elements will be exploited to develop zebrafish transgenic tools that will allow the genetic manipulation tip/stalk cell gene expression and angiogenesis in vivo. This project will use molecular biological, cell biological, advanced genomic, zebrafish transgenic and in vivo live imaging approaches. Ultimately, this project aims to uncover a detailed transcriptional framework for the control of angiogenic sprouting in vivo.

• Herbert, S. & Stainier, D (2011). Molecular control of endothelial cell behaviour during blood vessel morphogenesis. Nat Rev Mol Cell Biol, 12(9), 551-64.
   
• Herbert, S., Huisken, J., et al. (2009). Arterial-venous segregation by selective cell sprouting: an alternative mode of blood vessel formation. Science, 326(5950), 294-8.
   
• Siekmann, A. & Lawson, N (2007) Notch signalling limits angiogenic cell behaviour in developing zebrafish arteries. Nature, 445(7129), 781-4
   
• Hellstrom, M., Phng, L., et al. (2007) Dll4 signalling through Notch1 regulates formation of tip cells during angiogenesis. Nature, 445(7129), 776-80