Authors:
Leppänen, V-M.;
Jeltsch, M.;
Anisimov, A.;
Tvorogov, D.;
Aho, K.;
Kalkkinen, N.;
Toivanen, P.;
Ylä-Herttuala, S.;
Ballmer-Hofer, K.;
Alitalo, K.Source:
Blood (2010)
URL:
http://bloodjournal.hematologylibrary.org/cgi/content/abstract/blood-2010-08-301549v1
Abstract:
Vascular endothelial growth factors (VEGFs) and their tyrosine kinase receptors (VEGFR-1-3) are central mediators of angiogenesis and lymphangiogenesis. VEGFR-3 ligands VEGF-C and VEGF-D are produced as precursor proteins with long N- and C-terminal propeptides and show enhanced VEGFR-2 and VEGFR-3 binding upon proteolytic removal of the propeptides. Two different proteolytic cleavage sites have been reported in the VEGF-D N-terminus. We report here the crystal structure of the human VEGF-D Cys117Ala mutant at 2.9 Å resolution. Comparison of the VEGF-D and VEGF-C structures shows similar extended N-terminal helices, conserved overall folds and VEGFR-2 interacting residues. Consistent with this, the affinity and the thermodynamic parameters for VEGFR-2 binding are very similar. In comparison with VEGF-C structures, however, the VEGF-D N-terminal helix was extended by two more turns because of a better resolution. Both receptor binding and functional assays of N-terminally truncated VEGF-D polypeptides indicated that the residues between the reported proteolytic cleavage sites are important for VEGF-D binding and activation of VEGFR-3, but not of VEGFR-2. Thus, we define here a VEGFR-2 specific form of VEGF-D that is angiogenic, but not lymphangiogenic. These results provide important new insights into VEGF-D structure and function.