Structure function analysis of vascular endothelial growth factor receptors in angiogenesis

Lead Research Organisation: University of Birmingham
Department Name: Mechanical Engineering

Abstract

Heart attack or stroke can block blood vessels leading to local tissue damage or even death; there is therefore a need to increase blood flow and promote circulation by making new blood vessels. In contrast, inhibiting blood vessel growth prevents cancer and blindness respectively. The formation of blood vessels (angiogenesis) is complex: They are lined with endothelial cells, which divide and re-arrange themselves into new tube-like vessels. Vascular endothelial growth factor is an essential protein for the blood vessel formation and works by binding to receptors on the endothelial cells. This project will determine how these receptors signal to co-ordinate new vessel formation. Discoveries from this study will provide new insight for the development of novel therapeutic approaches to promote or block the growth of new blood vessels.

Technical Summary

Nitric oxide (NO) not only regulates blood vessel tone but also promotes angiogenesis. Vascular endothelial growth factor-A (VEGF) is critical for vascular development, angiogenesis and revascularisation after endothelial injury and acts via two receptors, VEGFR-1 and VEGFR-2. The loss of either receptor leads to death in utero. In contrast, the loss of VEGFR-1 catalytic activity does not impair vascular development, but inhibits pathological neovascularisation suggesting that VEGFR-1 is also important in angiogenesis-driven diseases. We hypothesise that VEGF utilises alternative signalling pathways via VEGFR-1 or VEGFR-2 to regulate NO and promote angiogenesis. We will determine the relative roles of these two receptors using chimeric receptors in which the extracellular domain of the epidermal growth factor receptor was substituted for that of VEGFR-1 or VEGFR-2 and transduced into human endothelial cells. To determine the structural-functional relationship between VEGFR-1 and VEGFR-2, NO and angiogenesis, a series of tyrosine-to-phenylalanine mutants will be analysed in NO release and capillary-like tube formation assays. A proteomic approach will be employed to identify the proteins associated with key VEGF receptor tyrosine residues that are required for eNOS activation and/or capillary morphogenesis and their downstream effectors. The downstream effectors of VEGFR-1 and VEGFR-2 and identified tyrosine residues will then be investigated by manipulating the signal transduction pathways of phosphatidylinositol 3-kinase (PI3K/PDK-1/Akt), phospholipase C-gamma1 and protein kinase C isozymes. This will be achieved by selective inhibition using either gene knockdown or over-expression of dominant-negative mutants of the signalling proteins using lentiviral and adenoviral vectors respectively. These studies will identify new sites of modulation in VEGF-mediated vascular morphogenesis and NO release that may highlight new therapeutic targets for management of vascular insufficiencies and cancer.

Publications

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Findley CM (2007) VEGF induces Tie2 shedding via a phosphoinositide 3-kinase/Akt dependent pathway to modulate Tie2 signaling. in Arteriosclerosis, thrombosis, and vascular biology

 
Description Dr C.D. Kontos 
Organisation Duke University
Country United States 
Sector Academic/University 
PI Contribution We undertook studies on sTie2 shedding in response to VEGF in endothelial cells.
Collaborator Contribution Reagents over the years and joint publication.
Impact Publication in ATVB, 2007. Circulation, 2009.
Start Year 2006
 
Description Dr David Thickett 
Organisation University of Birmingham
Department College of Medical and Dental Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution Vascular endothelial growth factor promotes physical wound repair and is anti-apoptotic in primary distal lung epithelial and A549 cells.
Collaborator Contribution Publication in Crit Care Med
Impact Publication in Crit Care Med., 2007. Also Dr Thickett was awarded a Senior Clinical Fellowship from the Wellcome Trust in 2008; we have a another manuscript to complete.
Start Year 2006
 
Description AngioNET 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact AngioNET is a European wide researchers in biology, maths and chemistry, includes industry.

there has been an increase awareness of the role of VEGFR-1 in angiogenesis from our studies.
Year(s) Of Engagement Activity 2008
 
Description Mail Online - Breakthrough in fight against pre-eclampsia 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Breakthrough in fight against pre-eclampsia: Scientists may have found cause of the life-threatening pregnancy condition

1. Giving hydrogen sulfide can reduce the risk of pre-eclampsia
2. The chemical is found naturally in the body, but some have lower levels
3. Scientists ay that if used safely in the form of a drug it can make up for this natural shortfall and help maintain a healthy blood flow to the placenta



A lot of request for its use in women with preeclampsia; asking when could such a treatment become available to them.
Year(s) Of Engagement Activity 2013
 
Description Mayo Clinic Angiogenesis Symposium 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact International Angiogenesis Audience, including world leaders in the field.

there has been an increase awareness of the role of VEGFR-1 in angiogenesis from our studies.
Year(s) Of Engagement Activity 2007
 
Description Trans-Institute Angiogenesis Research Program, NIH, Washington DC 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Trans-Institute Angiogenesis Research Program, NIH, Washington DC

Awareness of our work and discussion on the future direction of angiogenesis research in the USA.
Year(s) Of Engagement Activity 2007