The First Draft of the Endostatin Interaction Network

Abstract

Endostatin is a C-terminal proteolytic fragment of collagen XVIII that is localized in vascular basement membrane zones in various organs. It binds to heparin/heparan sulfate and to a number of proteins, but its molecular mechanisms of action are not fully elucidated. We have used surface plasmon resonance (SPR) arrays to identify new partners of endostatin, and to give further insights on its molecular mechanism of action. New partners of endostatin include glycosaminoglycans (chondroitin and dermatan sulfate), matricellular proteins (thrombospondin-1 and SPARC), collagens (I, IV, and VI), the amyloid peptide A␤-(1-42), and transglutaminase-2. The biological functions of the endostatin network involve a number of extracellular proteins containing epidermal growth factor and epidermal growth factor-like domains, and able to bind calcium. Depending on the trigger event, and on the availability of its members in a given tissue at a given time, the endostatin network might be involved either in the control of angiogenesis, and tumor growth, or in neurogenesis and neurodegenerative diseases.Endostatin is a C-terminal proteolytic fragment of collagen XVIII that is localized in vascular basement membrane zones in various organs. It inhibits angiogenesis and tumor growth (1-3). The effect of endostatin depends on its concentration (4, 5), on the length of exposure (6), on the type of endothelial cells (7), and on the growth factor inducing cell proliferation (fibroblast growth factor 2 or VEGF) 3 (8, 9). Endostatin binds to several membrane proteins including ␣5␤1 and ␣v␤3 integrins (10, 11), heparan sulfate proteoglycans (glypican-1 and -4) (12), and KDR/Flk1/VEGFR2 (13). We have previously characterized the binding of endostatin to heparan sulfate chains (9), and of endostatin to integrins (11). Furthermore, we have shown that ␣5␤1, ␣v␤3, and ␣v␤5 integrins bind to heparin/heparan sulfate (11).The broad molecular targets of endostatin suggest that multiple signaling systems are involved in mediation of its antiangiogenic action. Endostatin is a broad spectrum angiogenesis inhibitor that suppresses angiogenesis by blocking general mechanisms that govern endothelial cell growth (14), and initiates a complex network of signaling at the gene level (15). However, its molecular mechanism of action is still a matter of debate. An integrative view of the endostatin interaction network, including interactions between endostatin partners, is necessary to provide a clear understanding of how all these molecules work together to regulate angiogenesis, and tumor growth. This global approach places individual proteins into a functional context, and takes into account the fact that a single molecule such as endostatin can affect a wide range of other cell components. Indeed, most proteins and other components carry out their functions within a complex network of interactions and this approach based on protein-protein interaction networks has been developed for several years to give new clues on biological processes (16).This study ...

Large-Scale Investigation of Leishmania Interaction Networks with Host Extracellular Matrix by Surface Plasmon Resonance Imaging

“…In order to identify the partners of Leishmania on a large scale, we performed binding assays with intact live Leishmania promastigotes by using protein and glycosaminoglycan arrays previously developed in our laboratory (12)(13)(14). We investigated the ability of the logarithmic-phase promastigotes of 24 Leishmania strains and of the stationary-phase promastigotes of three of these strains to interact with ϳ70 molecules present in the skin, basement membrane, and blood vessels of their mammalian hosts.…”

The Collagen Family

“…These data can be used to build extracellular interaction networks of a molecule, a tissue or a disease and to make functional hypothesis. New tools to identify binding partners of a protein ( protein and glycosaminoglycan arrays probed by surface plasmon resonance imaging (Faye et al 2009(Faye et al , 2010, and a proteomics workflow to isolate complexes associated with integrin adhesion receptors (Humphries et al 2009), will be helpful in deciphering the functions of collagens at the systems biology level.…”

Anti-angiogenesis and anticancer effects of a plasmid expressing both ENDO-VEGI151 and small interfering RNA against survivin

“…Although current understanding of its mechanism is incomplete, we have proved that fusion protein could be detected by anti-endostatin and anti-VEGI 151 , indicating that fusion protein may preserve the biological activities of both proteins. Previous research indicates that endostatin and VEGI 151 have distinct mechanisms (23)(24)(25)(26). Therefore, fusion protein could block the angiogenesis by promoting apoptosis of endothelial cells, inhibiting the migration and blocking the signals for angiogenesis enhancement.…”