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Polydom/SVEP1 is a ligand for integrin α9β1
Ryoko Sato-Nishiuchi1, Itsuko Nakano, Akio Ozawa
1Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan.
The Journal of Biological Chemistry
|June 2, 2012
Summary
Polydom (SVEP1) is identified as a novel, high-affinity ligand for integrin α9β1. This discovery reveals a key interaction in cell adhesion and identifies a previously unknown physiological ligand in mouse tissues.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Integrin α9β1 plays a role in cell adhesion, but its physiological ligands with high affinity remain largely unknown.
- Known ligands like tenascin-C and osteopontin exhibit lower binding affinities compared to other integrin-ligand interactions.
Purpose of the Study:
- To identify novel physiological ligands for integrin α9β1.
- To characterize the binding interaction between polydom (SVEP1) and integrin α9β1.
Main Methods:
- Recombinant protein expression and purification.
- Integrin binding assays using purified proteins and synthetic peptides.
- Alanine-scanning mutagenesis to map the binding site.
- Immunohistochemistry and in situ binding assays on mouse embryonic tissues.
Main Results:
- Polydom (SVEP1) binds directly to integrin α9β1 with significantly higher affinity than previously known ligands.
- The integrin-binding site was mapped to the 21st complement control protein domain of polydom, specifically the EDDMMEVPY sequence.
- Polydom colocalizes with integrin α9 in various mouse embryonic organs and mediates significant integrin α9β1 binding in tissues.
Conclusions:
- Polydom (SVEP1) is a newly discovered, high-affinity physiological ligand for integrin α9β1.
- The identified binding site and sequence are crucial for the interaction between polydom and integrin α9β1.
- This finding advances our understanding of integrin-mediated cell adhesion and identifies a key player in tissue development.
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