Transcriptional regulation of the Notch and Vegf signalling pathways during angiogenesis and arterio-venous differentiation

The correct formation of blood vessels is essential for human development and health. However, mistakes in vessel growth or formation occur in a large variety of diseases. For example, the development of solid tumours involves the growth of new blood vessels into the tumour to provide the required nutrients, and a number of eye diseases are caused by faulty blood vessel growth in the retina. Consequently, it is very important that we increase our understanding of how the formation and growth of blood vessels is controlled.

The growth of blood vessels requires the precise regulation of a large number of genes, and it is this regulation that our laboratory investigates. In particular, we are interested in how genes are specifically switched on in blood vessels but remain off in other tissues. This MRC project will investigate the regulation of a group of related genes that make up the Notch and VEGF signalling pathways in blood vessels. These pathways are different, but related, ways in which blood vessels receive information from their surroundings suggesting that a new blood vessel needs to be formed, and the type of vessel that is needed. For example, if a tissue is short of oxygen and therefore wants more blood vessels, it will utilise these two pathways (and others) to signal this need. The two processes we are investigating are angiogenesis, which is the process by which new vessels first form, and how arteries and veins mature.

The benefits stemming from this work will include a massive increase in our understanding of how the process of signalling to form new vessels is controlled, and how the processes of vessel growth and differentiation are regulated. It is anticipated that the results will help drive forward the development of therapies to prevent, alter or encourage vascular growth in many different diseases, including cancer, eye disease, inflammatory and autoimmune disorders, and heart disease.

The correct formation of blood vessels is essential for embryonic growth and development, but this process can also be co-opted by a number of pathological conditions. The Notch and VEGF signalling pathways play a significant role in vessel differentiation and angiogenic vascular growth, and are consequently attractive candidates for anti-angiogenesis therapy. However, resistance to VEGF inhibitors, in part mediated by the Notch pathway, is emerging as a major clinical limitation to current anti-angiogenic therapies. Consequently, in order to develop effective, targeted interventions to pathological vessel growth, it is increasingly important that we understand the biology of these two pathways in endothelial cells. The aim of this proposal is to understand the regulatory networks that control the transcription of genes within the Notch and VEGF pathways during vessel growth via the systematic identification, validation and characterization of regulatory enhancer elements. These will be identified in silico, validated in transgenic zebrafish and characterized using targeted single-copy transgenic mouse models. Key regulatory factors will be identified through a combination of validated phylogenic footprints, mutations of cis-motifs and identification of binding factors e.g. with SILAC. The role of novel vascular factors will be further investigated via gene knock-down or knock-out strategies in both in vivo and in vitro models. In conclusion, this investigation will delineate the entire transcriptional pathway regulating the Notch and VEGF pathways during angiogenic sprouting and vascular differentiation, and identify key transcription factors involved in these processes.

The proposed project seeks to delineate the entire transcriptional pathway regulating angiogenic sprouting and vascular differentiation, and to identify the transcription factors involved in these processes. It is anticipated that this research will provide key insights regarding the manner in which components of the Notch and VEGF vascular signalling pathways interact with themselves, each other, and other angiogenic pathways such as TGF-beta and Wnt signalling, during both physiological and pathological vessel growth. Resistance to VEGF inhibitors, in part mediated by the Notch pathway, is emerging as a major clinical limitation to current anti-angiogenic therapies. Consequently, although this proposal covers basic science research, the thorough understanding of how these two major pathways are transcriptionally regulated during vessel growth that will be gained is anticipated to have long-term, important implications for both the design of new anti-angiogenic therapies, and the treatment regimes utilized with current therapeutics.