Decorin Binds to a Narrow Region of the Epidermal Growth Factor (EGF) Receptor, Partially Overlapping but Distinct from the EGF-binding Epitope

• Published in: The Journal of biological chemistry Vol. 277; no. 38; pp. 35671 - 35681
• Main Authors: Santra, Manoranjan, Reed, Charles C, Iozzo, Renato V
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 20.09.2002
• Subjects: Amino Acid Sequence; Animals; Binding Sites; Cell Line; Decorin; Epidermal Growth Factor - immunology; Epidermal Growth Factor - metabolism; Epitopes - metabolism; ErbB Receptors - chemistry; ErbB Receptors - genetics; ErbB Receptors - metabolism; Extracellular Matrix Proteins; Humans; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Protein Binding; Proteoglycans - metabolism; Two-Hybrid System Techniques
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M205317200

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.