Post-translational modifications and molecular interactions regulating VEGFR2 activity

The work described in this thesis has been mainly focused on the study of a key molecule involved in blood vessel formation, the tyrosine kinase receptor VEGFR2. Considering that VEGFR2 biology should be tighly regulated to allow proper blood vessel formation and maintenance, we investigated two different mechanims influencing VEGFR2 activity: post translational modification and receptor complex formation. Since VEGFR2 biology is governed through protein modication, mainly phosphorylation, we decided to investigate the possible role of acetylation in VEGFR2 activity. Combining biochemical and proteomic studies, we showed that VEGFR2 is modified by acetylation. Starting from this observation, we further investigated the impact of VEGFR2 acetylation on protein stability and phosphorylation in response to ligand. These findings are of particular interest, since, to our knowledge, this is the first report that a tyrosine kinase receptor might be regulated by acetylation. Additionally, we decided to elucidate the interaction of VEGFR2 with its coreceptor Neuropilin1, with particular attention to the Neuropilin1 molecule, by taking advantage of the FRET imaging technique. Collectively, our work characterizes VEGFR2-Neuropilin1 and Neuropilin1-Neuropilin1 complex formation in response to VEGFs and SEMA3A. Altough we do not provide direct evidence for Neuropilin1 direct signalling, our data suggest that Neuropilin1 oligomer formation might be a key step in Neuropilin1 biology.