Mutation in the Kinase Domain Alters the VEGFR2 Membrane Dynamics

Recently, the substitution R1051Q in VEGFR2 has been described as a cancer-associated "gain of function" mutation. VEGFR2^R1051Q phosphorylation is ligand-independent and enhances the activation of intracellular pathways and cell growth both in vitro and in vivo. In cancer, this mutation is found in heterozygosity, suggesting that an interaction between VEGFR2^R1051Q and VEGFR2^WT may occur and could explain, at least in part, how VEGFR2^R1051Q acts to promote VEGFR2 signaling. Despite this, the biochemical/biophysical mechanism of the activation of VEGFR2^R1051Q remains poorly understood. On these bases, the aim of our study is to address how VEGFR2R1051Q influences the biophysical behavior (dimerization and membrane dynamics) of the co-expressed VEGFR2^WT.

We employed quantitative FLIM/FRET and FRAP imaging techniques using CHO cells co-transfected with the two forms of VEGFR2 to mimic heterozygosity.

Membrane protein biotinylation reveals that VEGFR2^WT is more exposed on the cell membrane with respect to VEGFR2^R1051Q. The imaging analyses show the ability of VEGFR2^WT to form heterodimers with VEGFR2^R1051Q and this interaction alters its membrane dynamics. Indeed, when the co-expression of VEGFR2^WT/VEGFR2^R1051Q occurs, VEGFR2^WT shows reduced lateral motility and a minor pool of mobile fraction.

This study demonstrates that active VEGFR2^R1051Q can affect the membrane behavior of the VEGFR2^WT.