Related Experiment Videos
Endostatins derived from collagens XV and XVIII differ in structural and binding properties, tissue distribution and
Abstract:
Endostatin is a fragment of the C-terminal domain NC1 of collagen XVIII that inhibits angiogenesis and tumor growth. We report the characterization of a collagen XV endostatin analogue and its parent NC1 domain, obtained by recombinant expression in mammalian cells. Both NC1 domains contain a trimerization domain, a hinge region that is more sensitive to proteolysis in collagen XVIII and the endostatin domain. Unlike endostatin-XVIII, endostatin-XV does not bind zinc or heparin, which is explained by the crystal structure of endostatin-XV. The collagen XV and XVIII fragments inhibited chorioallantoic membrane angiogenesis induced by basic fibroblast growth factor (FGF-2) or vascular endothelial growth factor (VEGF), but there are striking differences depending on which cytokine is used and whether free endostatins or NC1 domains are applied. The collagen XV and XVIII fragments showed a similar binding repertoire for extracellular matrix proteins. Differences were found in the immunohistological localization in vessel walls and basement membrane zones. Together, these data indentify endostatin-XV as an angiogenesis inhibitor, which differs from endostatin-XVIII in several important functional details.
Insights
We characterized endostatin-XV, an angiogenesis inhibitor. It differs functionally from endostatin-XVIII, impacting tumor growth and vessel formation through distinct mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Endostatin, a collagen XVIII fragment, inhibits angiogenesis and tumor growth.
- Recombinant expression allows for the characterization of collagen XV endostatin analogues and their parent NC1 domains.
Purpose of the Study:
- To characterize a collagen XV endostatin analogue and its parent NC1 domain.
- To compare the functional and structural properties of endostatin-XV with endostatin-XVIII.
Main Methods:
- Recombinant expression in mammalian cells.
- Crystal structure determination of endostatin-XV.
- Inhibition assays of chorioallantoic membrane angiogenesis induced by FGF-2 or VEGF.
- Analysis of extracellular matrix protein binding.
- Immunohistological localization studies.
Main Results:
- Both collagen XV and XVIII NC1 domains contain trimerization and hinge regions, with collagen XVIII's hinge being more sensitive to proteolysis.
- Endostatin-XV does not bind zinc or heparin, unlike endostatin-XVIII, as confirmed by its crystal structure.
- Both fragments inhibited FGF-2 and VEGF-induced angiogenesis, but with notable differences based on the cytokine and application method.
- Similar binding affinities for extracellular matrix proteins were observed for both fragments.
- Distinct immunohistological localization patterns were found in vessel walls and basement membrane zones.
Conclusions:
- Endostatin-XV is identified as an angiogenesis inhibitor.
- Endostatin-XV exhibits significant functional differences compared to endostatin-XVIII, particularly in its interaction with cytokines and its lack of zinc/heparin binding.
- These findings highlight the diverse roles and mechanisms of different endostatin family members in regulating angiogenesis.