Reversible acetylation regulates vascular endothelial growth factor receptor-2 activity

The tyrosine kinase receptor Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) is a key regulator of angiogenesis. Activity of the receptor in endothelial cells follows interaction with its cognate ligands, primarily the members of the VEGF family, and involves phosphorylation of various tyrosine residues in the intracytoplasmic portion of the receptor. By combining biochemical and proteomics studies, here we provide the first evidence that membrane-associated VEGFR2 is acetylated in endothelial cells at four lysine residues forming a dense cluster in the kinase insert domain, and in a single lysine located in the receptor activation loop. These modifications are under the dynamic control of the acetyltransferase p300 and the two deacetylases HDAC5 and HDAC6. We demonstrate that VEGFR2 acetylation essentially regulates receptor phosphorylation. In particular, VEGFR2 acetylation counteracts the process of receptor desensitization following VEGF stimulation, still allowing receptor phosphorylation and intracellular signaling upon prolonged ligand treatment. Cells expressing VEGFR2 mutants that cannot be acetylated display reduced levels of receptor phosphorylation and impaired migratory capacity. Consistent with these findings, molecular dynamics simulations indicated that acetylation of the lysine in the activation loop contributes to the transition to an open active state, in which tyrosine phosphorylation is favored by better exposure of the kinase target residues. Taken together, these findings indicate that post-translational modification by acetylation is a critical mechanism that directly affects VEGFR2 function.