title: Decorin binds to a narrow region of the epidermal growth factor (EGF) receptor, partially overlapping but distinct from the EGF-binding epitope.
abstract: Decorin, a small leucine-rich proteoglycan, is a key regulator of tumor growth by acting as an antagonist of the epidermal growth factor receptor (EGFR) tyrosine kinase. To search for cell surface receptors interacting with decorin, we generated a decorin/alkaline phosphatase chimeric protein and used it to screen a cDNA library by expression cloning. We identified two strongly reactive clones that encoded either the full-length EGFR or its ectodomain. A physiologically relevant interaction between decorin and EGFR was confirmed in the yeast two-hybrid system and further validated by experiments using EGF/EGFR interaction and transient cell transfection assays. Using a panel of deletion mutants, decorin binding was mapped to a narrow region of the EGFR within its ligand-binding L2 domain. Moreover, the central leucine-rich repeat 6 of decorin was required for interaction with the EGFR. Site-directed mutagenesis of the EGFR L2 domain showed that a cluster of residues, His(394)-Ile(402), was essential for both decorin and EGF binding. In contrast, K465, previously shown to be cross-linked to epidermal growth factor (EGF), was required for EGF but not for decorin binding. Thus, decorin binds to a discrete region of the EGFR, partially overlapping with but distinct from the EGF-binding domain. These findings could lead to the generation of protein mimetics capable of suppressing EGFR function.
authors.affiliation: Department of Pathology, Anatomy and Cell Biology, Room 249 Jefferson Alumni Hall, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Manoranjan
authors.initials: M
authors.lastname: Santra
authors.forename: Charles C
authors.initials: CC
authors.lastname: Reed
authors.forename: Renato V
authors.initials: RV
authors.lastname: Iozzo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D058575:Decorin; D004815:Epidermal Growth Factor / Q000276:immunology / Q000378:metabolism*; D000939:Epitopes / Q000378:metabolism*; D066246:ErbB Receptors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016326:Extracellular Matrix Proteins; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011509:Proteoglycans / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: C546878:DCN protein, human; D058575:Decorin; D000939:Epitopes; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D004815:Epidermal Growth Factor; D066246:ErbB Receptors