Abstract
Placental growth factor (PlGF) is a critical mediator of blood vessel formation, yet mechanisms of its action and regulation are incompletely understood. Here we demonstrate that proteolytic processing regulates the biological activity of PlGF. Specifically, we show that plasmin processing of PlGF-2 yields a protease-resistant core fragment comprising the vascular endothelial growth factor receptor-1 binding site but lacking the carboxyl-terminal domain encoding the heparin-binding domain and an 8-amino acid peptide encoded by exon 7. We have identified plasmin cleavage sites, generated a truncated PlGF118 isoform mimicking plasmin-processed PlGF, and explored its biological function in comparison with that of PlGF-1 and -2. The angiogenic responses induced by the diverse PlGF forms were distinct. Whereas PlGF-2 increased endothelial cell chemotaxis, vascular sprouting, and granulation tissue formation upon skin injury, these activities were abrogated following plasmin digestion. Investigation of PlGF/Neuropilin-1 binding and function suggests a critical role for heparin-binding domain/Neuropilin-1 interaction and its regulation by plasmin processing. Collectively, here we provide new mechanistic insights into the regulation of PlGF-2/Neuropilin-1-mediated tissue vascularization and growth.
Highlights
The mechanisms of placental growth factor (PlGF)-mediated blood vessel formation are incompletely understood
Placental growth factor (PlGF) Is Cleaved by Plasmin—To investigate the hypothesis that PlGF might be a substrate for the serine protease plasmin, PlGF-1 and PlGF-2 were incubated with plasmin and samples were subjected to gel electrophoresis and analyzed by silver staining (Fig. 1, A–C) and Western blotting (Fig. 1D)
We demonstrated that PlGF-1 and -2 are substrates for plasmin and that plasmin-catalyzed cleavage results in loss of the carboxyl-terminal domain in both proteins
Summary
The mechanisms of placental growth factor (PlGF)-mediated blood vessel formation are incompletely understood. Significance: Plasmin-mediated carboxyl-terminal processing of VEGF family members may be considered as a principal mechanism to regulate their biological activity. We show that plasmin processing of PlGF-2 yields a protease-resistant core fragment comprising the vascular endothelial growth factor receptor-1 binding site but lacking the carboxyl-terminal domain encoding the heparin-binding domain and an 8-amino acid peptide encoded by exon 7. We and others have demonstrated the susceptibility of VEGF-A165 to proteolytic cleavage by plasmin and metalloproteinases [21,22,23,24,25] Both proteases generate a protease-resistant core fragment containing the VEGFR binding domain but lacking the carboxyl-terminal domain coding for the HBD and the domain encoded by exon 8. Our findings unveil a dual control of PlGF activity by transcriptional regulation and proteolytic mechanisms
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
