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Murine epidermal growth factor peptide (33-42) binds to a YIGSR-specific laminin receptor on both tumor and
J Nelson1, W N Scott, W E Allen
1Centre for Peptide and Protein Engineering, School of Biology and Biochemistry, The Queen's University of Belfast, Belfast BT9 7BL, Northern Ireland, United Kingdom.
Abstract:
A laminin-antagonist peptide, comprising amino acids 33-42 of murine epidermal growth factor (mEGF-(33-42)), interacts with a breast cancer- and endothelial cell-associated receptor, which is specific for the laminin B1 chain sequence, CDPGYIGSR-NH2 (Lam.B1-(925-933)), and is immunologically similar to a previously described 67-kDa laminin receptor. In whole cell receptor assays, mEGF-(33-42), Lam. B1-(925-933), and laminin all have IC50 values for displacement of 125I-laminin in the range 1-5 nM. Cell attachment to solid-phase laminin is also blocked by all three ligands, but in contrast to the receptor assays, mEGF-(33-42) or Lam.B1-(925-933), while equipotent with each other, were less effective than laminin. The concentrations of the peptides required to produce half-maximal inhibition of attachment were in the range 230-390 nM, but those for laminin were 1000-fold lower, in the range 0.2-0.3 nM. Like laminin, solid-phase mEGF-(33-42) supports cell attachment, and this ability is blocked by anti-67-kDa receptor antibodies. Modeling studies suggest that both peptides present a tyrosyl and an arginyl residue on the same face of a right-handed helical fold with elliptical cross-section.
Insights
A laminin-antagonist peptide, murine epidermal growth factor (mEGF)-(33-42), binds to a laminin receptor on cancer and endothelial cells. This peptide, along with another sequence (Lam.B1-(925-933)), inhibits cell attachment to laminin, though less effectively than laminin itself.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Laminin is a key extracellular matrix protein involved in cell adhesion and migration.
- A specific receptor for laminin, immunologically similar to the 67-kDa laminin receptor, is associated with breast cancer and endothelial cells.
- Peptides derived from murine epidermal growth factor (mEGF) and laminin B1 chain sequences can interact with this receptor.
Purpose of the Study:
- To investigate the interaction of mEGF-(33-42) and Lam.B1-(925-933) peptides with the laminin receptor.
- To compare the efficacy of these peptides and laminin in blocking 125I-laminin displacement and cell attachment assays.
- To explore the structural basis for peptide-receptor interaction.
Main Methods:
- Whole cell receptor binding assays using 125I-laminin.
- Cell attachment assays to solid-phase laminin and mEGF-(33-42).
- Inhibition studies using mEGF-(33-42), Lam.B1-(925-933), laminin, and anti-67-kDa receptor antibodies.
- Molecular modeling studies.
Main Results:
- Both mEGF-(33-42) and Lam.B1-(925-933) peptides bind to the laminin receptor with high affinity (IC50 1-5 nM), comparable to laminin.
- These peptides effectively block cell attachment to laminin, but require higher concentrations (230-390 nM) compared to laminin (0.2-0.3 nM).
- Solid-phase mEGF-(33-42) supports cell attachment, an effect inhibited by anti-67-kDa receptor antibodies, suggesting the peptide mimics laminin's adhesive function.
Conclusions:
- The mEGF-(33-42) peptide acts as a laminin antagonist by binding to the 67-kDa laminin receptor.
- While capable of receptor interaction and blocking laminin-mediated attachment, the peptides exhibit different functional efficacies compared to native laminin.
- Structural analysis suggests specific residues (tyrosine and arginine) are crucial for peptide interaction with the receptor.