Ligand-specific differences in VEGFR-2 activation in response to VEGF-A and VEGF-E binding
Angiogenesis is the process of generating new blood vessels from existing ones. Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are the main proteins and receptors involved in this process. VEGFR-2 is the main receptor in the VEGFR family that contributes to angiogenesis, however, the activation of VEGFR-2 by human VEGF-A results in leaky and disorganised blood vessels which can promote tumour formation. VEGF-E is an Orf virus-derived VEGF that has been previously tested on mice and shown to form uniform and organised blood vessels without promoting tumour formation when activating VEGFR-2. Previous studies suggest that VEGF-A and VEGF-E generate a different rate of VEGFR-2 receptor internalization with differing amounts of VEGFR-2-Y951 and Src phosphorylation, a non-receptor protein tyrosine kinase.This project aims to investigate whether VEGF-E-induced VEGFR-2 internalization is delayed relative to VEGF-A, and if this is associated with reduced Src and VEGFR-2- Y951 phosphorylation. HEK293 cells were transfected to express VEGFR-2-YFP (yellow fluorescence protein) with an haemagglutinin (HA) tag, the rate of receptor internalization is tested using an internalization assay and the phosphorylation of Src and VEGFR-2-Y951 is tested using western blot.The study found that the internalization rate of VEGFR-2 when activated by VEGF-E, was significantly delayed compared to VEGF-A. The difference of Src and VEGFR-2- Y951 phosphorylation is unclear due to phosphorylated Src and VEGFR-2-Y951 are barely detected for both VEGF-E and VEGF-A.1These findings suggest that VEGF-E induces a delayed internalization rate of VEGFR- 2 compared to VEGF-A. However, more studies need to be done on signalling molecules such as Src and other phosphorylation sites on VEGFR-2 to gain more understanding of VEGF-E. This investigation of the differences caused by VEGF-E and VEGF-A induced VEGFR-2 activation can develop potential treatments to normalise angiogenesis process for immune cells to target tumours.
Advisor: Wise, Lyn; Finlay, David
Degree Name: Bachelor of Biomedical Sciences with Honours
Degree Discipline: Department of Pharmacology and Toxicology
Publisher: University of Otago
Keywords: VEGFR-2; VEGF-A; VEGF-E; Src; Y951; internalization
Research Type: Thesis