Abstract 12659: Hepatoma-Derived Growth Factor Related Protein-3 as a Novel Endothelial Ligand
Background: Endothelial ligands extrinsically regulate a broad spectrum of vascular functions with therapeutic potentials, but are traditionally identified on a case-by-case basis with technical challenges. We recently developed open reading frame phage display (OPD) for unbiased identification of phagocytosis ligands. In this study, we identified hepatoma-derived growth factor related protein-3 (HRP-3) as a putative endothelial ligand by OPD. We hypothesized that HRP-3 is a novel endothelial growth factor, capable of promoting endothelial cell (EC) growth and migration.
Methods and Results: We performed 3 rounds of in vivo phage binding selection in mice with an OPD library, screened enriched phage clones by next generation DNA sequencing, and identified HRP-3 as one of the putative endothelial ligands. To confirm the finding, clonal phages displaying HRP-3, VEGF and GFP were generated and analyzed for their binding to human umbilical vein endothelial cells (HUVECs). The results show that HRP-3-Phage and VEGF-Phage had significantly higher binding to HUVECs than GFP-Phage. Functional analysis showed that purified recombinant HRP-3 significantly increased the proliferation of HUVECs at 24 and 48 h, whereas VEGF induced significant growth only at 48 h. Consistent with these findings, HRP-3 significantly stimulated cell proliferation by MTT assay. In vitro wound-healing assay indicated that both HRP-3 (500 ng/ml) and VEGF (50 ng/ml) significantly promoted the migration of HUVECs into the denuded area. To dissect the downstream signaling pathway, we demonstrated that HRP-3 significantly induced ERK1/2 phosphorylation in HUVECs after 10 min treatment. Similar effects of HRP-3 and VEGF on EC growth, migration, and ERK activation were also verified using human aorta endothelial cells.
Conclusions: Our findings demonstrate that HRP-3 is a novel ligand, capable of promoting proliferation and migration of ECs. The pro-growth effect of HRP-3 is at least partially mediated through ERK pathway activation. These results in turn support the broad applicability of OPD for the systematic discovery of endothelial ligands.
Author Disclosures: M. LeBlanc: None. W. Wang: None. F. Guo: None. C. Shen: None. R. Chen: None. F. Wang: None. W. Li: None.
This research has received full or partial funding support from the American Heart Association
- © 2014 by American Heart Association, Inc.