Targeting angiogenesis: Structural characterization and biological properties of a de novo engineered VEGF mimicking peptide

Abstract

Modulating angiogenesis is an attractive goal because many pathological conditions depend on the growth of new vessels. Angiogenesis is mainly regulated by the VEGF, a mitogen specific for endothelial cells. In the last years, many efforts have been pursued to modulate the angiogenic response targeting VEGF and its receptors. Based on the x-ray structure of VEGF bound to the receptor, we designed a peptide, QK, reproducing a region of the VEGF binding interface: the helix region 17-25. NMR conformation analysis of QK revealed that it adopts a helical conformation in water, whereas the peptide corresponding to the ␣-helix region of VEGF, VEGF15, is unstructured. Biological assays in vitro and on bovine aorta endothelial cells suggested that QK binds to the VEGF receptors and competes with VEGF. VEGF15 did not bind to the receptors indicating that the helical structure is necessary for the biological activity. Furthermore, QK induced endothelial cells proliferation, activated cell signaling dependent on VEGF, and increased the VEGF biological response. QK promoted capillary formation and organization in an in vitro assay on matrigel. These results suggested that the helix region 17-25 of VEGF is involved in VEGF receptor activation. The peptide designed to resemble this region shares numerous biological properties of VEGF, thus suggesting that this region is of potential interest for biomedical applications, and molecules mimicking it could be attractive for therapeutic and diagnostic applications.helical peptides ͉ peptide design ͉ VEGF ͉ angiogenesis ͉ NMR spectroscopy

Supramolecular nanostructures that mimic VEGF as a strategy for ischemic tissue repair

“…The mutant PA again demonstrated no effect on VEGFR2 phosphorylation, establishing this as an ideal material control for the VEGF PA. Both the VEGF PA and the VEGF peptide signal similarly to the VEGF assay control for both receptors, confirming reports on the discovery of the epitope (30). Examining the effect of VEGF PA stimulation over time ( Fig.…”

“…1C). The reported bioactive secondary structure of the VEGF-mimetic sequence is α-helical (30,31). CD of the VEGF PA revealed a signal characteristic of α-helix (Fig.…”

“…The VEGF PA (Fig. 1A) was designed to display on the surface of nanostructures a peptide sequence that mimics VEGF, KLTWQELYQLKYKGI-NH 2 (30). At the N terminus of this peptide, we covalently attached a K 3 G sequence to facilitate solubility and a V 2 A 2 β-domain followed by a C 16 alkyl chain to promote self-assembly into cylindrical nanostructures through intermolecular hydrogen bonding and hydrophobic collapse (Fig.…”

“…In addition, a number of synthetic strategies have emerged to modulate angiogenesis through small molecules or peptides and have been developed to antagonize receptors for cancer therapies or to promote angiogenesis by signaling through these receptors (28,29). Currently, only one synthetic oligopeptide has been demonstrated to mimic VEGF through the activation of its receptors (30,31). This peptide was designed based on the native α-helical receptor-binding domain of VEGF and was shown to mimic native VEGF through activation of VEGF receptors.…”

Nonerythropoietic, tissue-protective peptides derived from the tertiary structure of erythropoietin

“…Previous study has shown that peptides can be synthesized to mimic the helical structure of a protein that interacts with its receptor to reproduce the biological activities of the full molecule (24). Upon further consideration, however, we reasoned that because helix B is amphipathic and of the 4-3 ␣-helix type, specific amino acid residues within the hydrophilic portion face the external, aqueous face (i.e., every fourth and third residue in the b and f position, respectively).…”