Signal transduction in endothelial cells by the angiogenesis inhibitor histidine-rich glycoprotein targets focal adhesions

• Histidine-rich glycoprotein (HRGP) is an abundant heparin-binding plasma protein. We have shown that a fragment released from the central histidine/proline-rich (His/Pro-rich) domain of HRGP blocks endothelial cell migration in vitro and vascularization and growth of murine fibrosarcoma in vivo. The minimal active HRGP domain exerting the anti-angiogenic effect was recently narrowed down to a 35 amino acid peptide, HRGP330, derived from the His/Pro-rich domain of HRGP. By use of a signal transduction antibody array representing 400 different signal transduction molecules, we now show that HRGP and the synthetic peptide HRGP330 specifically induce tyrosine phosphorylation of focal adhesion kinase and its downstream substrate paxillin in endothelial cells. HRGP/HRGP330 treatment of endothelial cells induced disruption of actin stress fibers, a process reversed by treatment of cells with the FAK inhibitor geldanamycin. In addition, VEGF-mediated endothelial cell tubular morphogenesis in a three-dimensional collagen matrix was inhibited by HRGP and HRGP330. In contrast, VEGF-induced proliferation was not affected by HRGP or HRGP330, demonstrating the central role of cell migration during tube formation. In conclusion, our data show that HRGP targets focal adhesions in endothelial cells, thereby disrupting the cytoskeletal organization and the ability of endothelial cells to assemble into vessel structures.

Keyword

Actins/metabolism

Angiogenesis Inhibitors/*pharmacology

Animals

Benzoquinones

Cattle

Cell Proliferation/drug effects

Cells; Cultured

Endothelial Cells/*cytology/*drug effects

Focal Adhesion Protein-Tyrosine Kinases/metabolism

Focal Adhesions/*drug effects

Humans

Lactams; Macrocyclic

Mice

Peptides/pharmacology

Phosphoproteins/metabolism

Phosphorylation/drug effects

Phosphotyrosine/metabolism

Protein Array Analysis

Proteins/*pharmacology

Quinones/pharmacology

Signal Transduction/*drug effects

Stress Fibers/drug effects

Vascular Endothelial Growth Factor A/pharmacology

Publication and Content Type

ref (subject category)

art (subject category)