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Epiregulin is a potent pan-ErbB ligand that preferentially activates heterodimeric receptor complexes

M Shelly1, R Pinkas-Kramarski, B C Guarino

  • 1Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel.

The Journal of Biological Chemistry
|May 30, 1998
PubMed

Insights

Epiregulin, an epidermal growth factor (EGF)-like ligand, activates all ErbB receptor combinations. Despite lower binding affinity, it elicits a stronger mitogenic signal than EGF by preventing receptor down-regulation.

Area of Science:

  • Cellular Biology
  • Molecular Signaling
  • Receptor Tyrosine Kinases

Background:

  • The ErbB signaling network involves four receptor tyrosine kinases and numerous ligands with an epidermal growth factor (EGF) motif.
  • Signal specificity among ErbB ligands is complex due to partially overlapping signaling pathways.

Purpose of the Study:

  • To investigate the signaling specificity and bioactivity of epiregulin, a novel ligand for ErbB-1.
  • To understand the relationship between epiregulin's binding affinity and its biological effects on ErbB receptor activation.

Main Methods:

  • Utilized engineered factor-dependent cell lines expressing individual ErbB receptors or combinations.
  • Assessed epiregulin's ability to stimulate homodimeric and heterodimeric ErbB complexes.
  • Compared epiregulin's binding affinity and mitogenic potency to EGF across various receptor configurations.

Main Results:

  • Epiregulin demonstrated the broadest specificity among characterized EGF-like ligands, activating all ErbB homodimers and heterodimers.
  • Epiregulin exhibited approximately 100-fold lower binding affinity compared to high-selectivity ligands like EGF.
  • Epiregulin induced a more potent mitogenic signal than EGF across most receptor combinations.
  • This enhanced bioactivity is linked to a mechanism preventing receptor down-regulation, leading to prolonged receptor activation.

Conclusions:

  • Epiregulin is a unique, broad-specificity ligand within the ErbB network.
  • The dissociation between low binding affinity and high bioactivity suggests a novel activation mechanism.
  • Epiregulin's prolonged receptor activation offers insights into differential signaling outcomes in the ErbB pathway.

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